2020-10-30T10:44:10Zhttp://edoc.mpg.de/ac_ft_oai.ploai:edoc.mpg.de:5428202011-03-1161:916
The Supersymmetric Parameter Space in Light of B-physics Observables and Electroweak Precision Data
Ellis, J.
Heinemeyer, S.
Olive, K. A.
Weber, A. M.
Weiglein, G.
notspecified
Phenomenology of High Energy Physics
Indirect information about the possible scale of supersymmetry (SUSY) breaking is provided by B-physics observables (BPO) as well as electroweak precision observables (EWPO). We combine the constraints imposed by recent measurements of the BPO BR(b -> s gamma), BR(B_s -> mu^+ mu^-), BR(B_u -> tau nu_tau) and Delta M_{B_s} with those obtained from the experimental measurements of the EWPO M_W, sin^2 theta_eff, Gamma_Z, (g-2)_mu and M_h, incorporating the latest theoretical calculations of these observables within the Standard Model and supersymmetric extensions. We perform a chi^2 fit to the parameters of the constrained minimal supersymmetric extension of the Standard Model (CMSSM), in which the SUSY-breaking parameters are universal at the GUT scale, and the non-universal Higgs model (NUHM), in which this constraint is relaxed for the soft SUSY-breaking contributions to the Higgs masses. Assuming that the lightest supersymmetric particle (LSP) provides the cold dark matter density preferred by WMAP and other cosmological data, we scan over the remaining parameter space. Within the CMSSM, we confirm the preference found previously for a relatively low SUSY-breaking scale, though there is some slight tension between the EWPO and the BPO. In studies of some specific NUHM scenarios compatible with the cold dark matter constraint we investigate M_A-tan_beta planes and find preferred regions that have values of chi^2 somewhat lower than in the CMSSM.
2007
Article
http://edoc.mpg.de/542820
Journal of High Energy Physics, 083 (2007)
oai:edoc.mpg.de:5428222011-03-1161:916
Search for Excited Electrons in ep Collisions at HERA
H1 Collaboration
notspecified
H1
A search for excited electrons is performed using the full $e^{\pm}p$ data sample collected by the H1 experiment at HERA, corresponding to a total luminosity of 475 pb$^{-1}$. The electroweak decays of excited electrons ${e}^{*}\to{e}{\gamma}$, ${e}^{*}\to{e}Z$ and ${e}^{*}{\to}\nu W$ with subsequent hadronic or leptonic decays of the $W$ and $Z$ bosons are considered. No evidence for excited electron production is found. Mass dependent exclusion limits on $e^*$ production cross sections and on the ratio $f/{\Lambda}$ of the coupling to the compositeness scale are derived within gauge mediated models. These limits extend the excluded region compared to previous excited electron searches. The $e^*$ production via contact interactions is also addressed for the first time in $ep$ collisions.
2008
Article
http://edoc.mpg.de/542822
Physics Letters B, 131-139 (2008)
oai:edoc.mpg.de:5428242011-03-1161:916
Revisiting cosmological bounds on radiative neutrino lifetime
Mirizzi, A.
Montanino, D.
Serpico, P.
notspecified
Astroparticle Physics
Neutrino oscillation experiments and direct bounds on absolute masses constrain neutrino mass differences to fall into the microwave energy range, for most of the allowed parameter space. As a consequence of these recent phenomenological advances, older constraints on radiative neutrino decays based on diffuse background radiations and assuming strongly hierarchical masses in the eV range are now outdated. We thus derive new bounds on the radiative neutrino lifetime using the high precision cosmic microwave background spectral data collected by the Far Infrared Absolute Spectrophotometer instrument on board of Cosmic Background Explorer. The lower bound on the lifetime is between a few x 10^19 s and 5 x 10^20 s, depending on the neutrino mass ordering and on the absolute mass scale. However, due to phase space limitations, the upper bound in terms of the effective magnetic moment mediating the decay is not better than ~ 10^-8 Bohr magnetons. We also comment about possible improvements of these limits, by means of recent diffuse infrared photon background data. We compare these bounds with pre-existing limits coming from laboratory or astrophysical arguments. We emphasize the complementarity of our results with others available in the literature.
2007
Article
http://edoc.mpg.de/542824
Physical Review D, 053007 (2007)
oai:edoc.mpg.de:5428252011-03-1161:916
Solar neutrino limit on the axion-like interpretation of the DAMA signal
Gondolo, Paolo
Raffelt, Georg
notspecified
Astroparticle Physics
The annual modulation signature of the DAMA experiments has been interpreted in terms of keV-mass axion-like particles with a dimensionless coupling to electrons exceeding 2 x 10^-11. Even for multi-keV masses, such couplings are excluded by several orders of magnitude by the usual globular-cluster limits on stellar energy losses. In addition, we here show that the solar neutrino flux measured by SNO is enough to rule out such particles. Our new argument can be applied to other low-mass particles as well.
2009
Article
http://edoc.mpg.de/542825
Physical Review D, 107301 (2009)
oai:edoc.mpg.de:5428262011-03-1161:916
Upgrade of the ATLS Muon Trigger for the SLHC
Dubbert, Jörg
Horvat, Sandra
Kortner, Oliver
Kroha, Hubert
Richter, Robert
notspecified
ATLAS
The outer shell of the ATLAS experiment at the LHC consists of a system of toroidal air-core magnets in order to allow for the precise measurement of the transverse momentum p$_T$ of muons, which in many physics channels are a signature of interesting physics processes. For the precise determination of the muon momentum Monitored Drift Tube chambers (MDT) with high position accuracy are used, while for the fast identification of muon tracks chambers with high time resolution are used, able to select muons above a predefined p$_T$ threshold for use in the first Level of the ATLAS triggering system (Level-1 trigger). When the luminosity of the LHC will be upgraded to 4-5 times the present nominal value (SLHC) in about a decade from now, an improvement of the selectivity of the ATLAS Level-1 triggering system will be mandatory in order to cope with the maximum allowed trigger rate of 100 kHz. For the Level-1 trigger of the ATLAS muon spectrometer this means an increase of the p$_T$ threshold for single muons. Due to the limited spatial resolution of the trigger chambers, however, the selectivity for tracks above ~20 GeV/c is insufficient for an effective reduction of the Level-1 rate. We describe how the track coordinates measured in the MDT precision chambers can be used to decisively improve the selectivity for high momentum tracks. The resulting increase in latency will also be discussed.
2010
Conference-Paper
http://edoc.mpg.de/542826
Journal of Instrumentation, 5, C12016 (2010)
Robert Richter: TWEPP 2010, Aachen, C12016 (2010)
oai:edoc.mpg.de:5428272011-03-1161:916
Discovery of VHE Gamma Radiation from IC443 with the MAGIC Telescope
MAGIC Collaboration
notspecified
MAGIC
We report the detection of a new source of very high energy (VHE, E_gamma >= 100GeV) gamma-ray emission located close to the Galactic Plane, MAGIC J0616+225, which is spatially coincident with SNR IC443. The observations were carried out with the MAGIC telescope in the periods December 2005 - January 2006 and December 2006 - January 2007. Here we present results from this source, leading to a VHE gamma-ray signal with a statistical significance of 5.7 sigma in the 2006/7 data and a measured differential gamma-ray flux consistent with a power law, described as dN_gamma/(dA dt dE) = (1.0 +/- 0.2)*10^(-11)(E/0.4 TeV)^(-3.1 +/- 0.3) cm^(-2)s^(-1)TeV^(-1). We briefly discuss the observational technique used and the procedure implemented for the data analysis. The results are put in the perspective of the multiwavelength emission and the molecular environment found in the region of IC443.
2007
Article
http://edoc.mpg.de/542827
Astrophysical Journal Letters, L87 (2007)
oai:edoc.mpg.de:5428282011-03-1161:916
Correlated Variability in Blazars
Wagner, Robert
notspecified
MAGIC
lazars are thought to emit highly-collimated outflows,
so-called jets. By their close alignment to our line of sight, relativistic beaming effects enable us to observe these jets over the whole electromagnetic spectrum up to TeV energies, making them ideal laboratories for studying jet physics. In the last years multiwavelength observations of blazars provided us with detailed data sets which helped to characterize the two main components of the non-relativistic emission, peaking in the optical to X-ray and GeV/TeV energy region, respectively. In leptonic acceleration models, they are explained by synchrotron radiation of electrons and inverse-Compton emission from the same electron population and thus, correlations of both emission regimes are expected. We review recent observational results on the presence and absence of such correlations in blazars, and discuss constraints on emission models by quantitative correlation analyses.
Conference-Paper
http://edoc.mpg.de/542828
oai:edoc.mpg.de:5428292011-03-1161:916
Symplectic structure of N=1 supergravity with anomalies and Chern-Simons terms
Rydt, Jan De
Rosseel, Jan
Schmidt, Torsten T.
Proeyen, Antoine Van
Zagermann, Marco
notspecified
Field Theory
The general actions of matter-coupled N=1 supergravity have Peccei-Quinn terms that may violate gauge and supersymmetry invariance. In addition, N=1 supergravity with vector multiplets may also contain generalized Chern-Simons terms. These have often been neglected in the literature despite their importance for gauge and supersymmetry invariance. We clarify the interplay of Peccei-Quinn terms, generalized Chern-Simons terms and quantum anomalies in the context of N=1 supergravity and exhibit conditions that have to be satisfied for their mutual consistency. This extension of the previously known N=1 matter-coupled supergravity actions follows naturally from the embedding of the gauge group into the group of symplectic duality transformations. Our results regarding this extension provide the supersymmetric framework for studies of string compactifications with axionic shift symmetries, generalized Chern-Simons terms and quantum anomalies.
2007
Article
http://edoc.mpg.de/542829
Classical and Quantum Gravity, 5201-5220 (2007)
oai:edoc.mpg.de:5428302011-03-1161:916
Role of dense matter in collective supernova neutrino transformations
Esteban-Pretel, A.
Mirizzi, A.
Pastor, S.
Tomas, R.
Raffelt, G. G.
Serpico, P. D.
Sigl, G.
notspecified
Astroparticle Physics
For neutrinos streaming from a supernova (SN) core, dense matter suppresses self-induced flavor transformations if the electron density n_e significantly exceeds the neutrino density n_nu in the conversion region. If n_e is comparable to n_nu one finds multi-angle decoherence, whereas the standard self-induced transformation behavior requires that in the transformation region n_nu is safely above n_e. This condition need not be satisfied in the early phase after supernova core bounce. Our new multi-angle effect is a subtle consequence of neutrinos traveling on different trajectories when streaming from a source that is not point-like.
2008
Article
http://edoc.mpg.de/542830
Physical Review D, 085012 (2008)
oai:edoc.mpg.de:5428332011-03-1161:916
Finite baryon and isospin chemical potential in AdS/CFT with flavor
Erdmenger, Johanna
Kaminski, Matthias
Kerner, Patrick
Rust, Felix
notspecified
Theoretical Physics
We investigate the thermodynamics of a thermal field theory in presence of both a baryon and an isospin chemical potential. For this we consider a probe of several D7-branes embedded in the AdS-Schwarzschild black hole background. We determine the structure of the phase diagram and calculate the relevant thermodynamical quantities both in the canonical and in the grand canonical ensemble. We discuss how accidental symmetries present reflect themselves in the phase diagram: In the case of two flavors, for small densities, there is a rotational symmetry in the plane spanned by the baryon and isospin density which breaks down at large densities, leaving a Z_4-symmetry. Finally, we calculate vector mode spectral functions and determine their dependence on either the baryon or the isospin density. For large densities, a new excitation forms with energy below the known supersymmetric spectrum. Increasing the density further, this excitation becomes unstable. We speculate that this instability indicates a new phase of condensed mesons.
2008
Article
http://edoc.mpg.de/542833
Journal of High Energy Physics, 031 (2008)
oai:edoc.mpg.de:5428342011-03-1161:916
Decoherence in supernova neutrino transformations suppressed by deleptonization
Esteban-Pretel, Andreu
Pastor, Sergio
Tomas, Ricard
Raffelt, Georg G.
Sigl, Gunter
notspecified
Astroparticle Physics
In the dense-neutrino region at 50-400 km above the neutrino sphere in a supernova, neutrino-neutrino interactions cause large flavor transformations. We study when the multi-angle nature of the neutrino trajectories leads to flavor decoherence between different angular modes. We consider a two-flavor mixing scenario between nu_e and another flavor nu_x and assume the usual hierarchy F(nu_e)>F{antinu_e)>F(nu_x)=F(antinu_x) for the number fluxes. We define epsilon=(F(nu_e)-F(antinu_e))/(F(antinu_e)-F(antinu_x)) as a measure for the deleptonization flux which is the one crucial parameter. The transition between the quasi single-angle behavior and multi-angle decoherence is abrupt as a function of epsilon. For typical choices of other parameters, multi-angle decoherence is suppressed for epsilon>0.3, but a much smaller asymmetry suffices if the neutrino mass hierarchy is normal and the mixing angle small. The critical epsilon depends logarithmically on the neutrino luminosity. In a realistic supernova scenario, the deleptonization flux is probably enough to suppress multi-angle decoherence.
2007
Article
http://edoc.mpg.de/542834
Physical Review D, 125018 (2007)
oai:edoc.mpg.de:5428352011-03-1161:916
Search for Nearly Mass-Degenerate Charginos and Neutralinos at LEP
The OPAL collaboration
Abbiendi, G.
et al.
notspecified
OPAL
A search was performed for charginos with masses close to the mass of the lightest neutralino in e+e- collisions at centre-of-mass energies of 189-209 GeV recorded by the OPAL detector at LEP. Events were selected if they had an observed high-energy photon from initial state radiation, reducing the dominant background from two-photon scattering to a negligible level. No significant excess over Standard Model expectations has been observed in the analysed data set corresponding to an integrated luminosity of 570pb-1. Upper limits were derived on the chargino pair-productin cross-section, and lower limits on the chargino mass were derived in the context of the Minimal Supersymmetric Extension of the Standard Model for the gravity and anomaly mediated Supersymmetry breaking scenarios.
2003
Article
http://edoc.mpg.de/542835
European Physical Journal C, 479-489 (2003)
oai:edoc.mpg.de:5428362011-03-1161:916
Constraints on Supersymmetric Models from Catalytic Primordial Nucleosynthesis of Beryllium
Pospelov, Maxim
Pradler, Josef
Steffen, Frank Daniel
notspecified
Astroparticle Physics
The catalysis of nuclear reactions by negatively charged relics leads to increased outputs of primordial ^6Li and ^9Be. In combination with observational constraints on the primordial fractions of ^6Li and ^9Be, this imposes strong restrictions on the primordial abundance and the lifetime of charged relics. We analyze the constraints from the catalysis of ^9Be on supersymmetric models in which the gravitino is the lightest supersymmetric particle and a charged slepton--such as the lighter stau--the next-to-lightest supersymmetric particle (NLSP). Barring the special cases in which the primordial fraction of the slepton NLSP is significantly depleted, we find that the ^9Be data require a slepton NLSP lifetime of less than 6x10^3 seconds. We also address the issue of the catalytic destruction of ^6Li and ^9Be by late forming bound states of protons with negatively charged relics finding that it does not lead to any significant modification of the limit on the slepton lifetime.
2008
Article
http://edoc.mpg.de/542836
Journal of Cosmology and Astroparticle Physics, 020 (2008)
oai:edoc.mpg.de:5428372011-03-1161:916
p-values for Model Evaluation
Beaujean, Frederik
Caldwell, Allen
Kollar, Daniel
Kroeninger, Kevin
notspecified
Experimental Physics
Deciding whether a model provides a good description of data is often based on a goodness-of-fit criterion summarized by a p-value. Although there is considerable confusion concerning the meaning of p-values, leading to their misuse, they are nevertheless of practical importance in common data analysis tasks. We motivate their application using a Bayesian argumentation. We then describe commonly and less commonly known discrepancy variables and how they are used to define p-values. The distribution of these are then extracted for examples modeled on typical data analysis tasks, and comments on their usefulness for determining goodness-of-fit are given.
2011
Article
http://edoc.mpg.de/542837
Physical Review D, 012004 (2011)
oai:edoc.mpg.de:5428382011-03-1161:916
The effective theory of type IIA AdS4 compactifications on nilmanifolds and cosets
Caviezel, Claudio
Koerber, Paul
Kors, Simon
Lust, Dieter
Tsimpis, Dimitrios
Zagermann, Marco
notspecified
Theoretical Physics
We consider string theory compactifications of the form AdS4 x M6 with orientifold six-planes, where M6 is a six-dimensional compact space that is either a nilmanifold or a coset. For all known solutions of this type we obtain the four-dimensional N=1 low energy effective theory by computing the superpotential, the Kaehler potential and the mass spectrum for the light moduli. For the nilmanifold examples we perform a cross-check on the result for the mass spectrum by calculating it alternatively from a direct Kaluza-Klein reduction and find perfect agreement. We show that in all but one of the coset models all moduli are stabilized at the classical level. As an application we show that all but one of the coset models can potentially be used to bypass a recent no-go theorem against inflation in type IIA theory.
2009
Article
http://edoc.mpg.de/542838
Classical and Quantum Gravity, 025014 (2009)
oai:edoc.mpg.de:5428392011-03-1161:916
Measurement of D^{+} and Lambda_{c}^{+} production in deep inelastic scattering at HERA
The ZEUS Collaboration
notspecified
ZEUS
Charm production in deep inelastic scattering has been measured with the ZEUS detector at HERA using an integrated luminosity of 120 pb^{-1}. The hadronic decay channels D^{+} -> K^{0}_{S} pi^{+}, Lambda_{c}^{+} -> p K^{0}_{S} and Lambda_{c}^{+} -> Lambda pi^{+}, and their charge conjugates, were reconstructed. The presence of a neutral strange hadron in the final state reduces the combinatorial background and extends the measured sensitivity into the low transverse momentum region. The kinematic range is 0 < p_{T}(D^{+}, Lambda_{c}^{+}) < 10 GeV, |eta(D^{+}, Lambda_{c}^{+})| < 1.6, 1.5 < Q^{2} < 1000 GeV^{2} and 0.02 < y < 0.7. Inclusive and differential cross sections for the production of D^{+} mesons are compared to next-to-leading-order QCD predictions. The fraction of c quarks hadronising into Lambda_{c}^{+} baryons is extracted.
2010
Article
http://edoc.mpg.de/542839
Journal of High Energy Physics, 009 (2010)
oai:edoc.mpg.de:5428402011-03-1161:916
Measurement of beauty production in DIS and F_2^bbbar extraction at ZEUS
ZEUS collaboration
Abramowicz, H.
Abt, I.
Adamczyk, L.
Adamus, M.
Aggarwal, R.
Antonelli, S.
Antonioli, P.
Antonov, A.
Arneodo, M.
Aushev, V.
Aushev, Y.
Bachynska, O.
Bamberger, A.
Barakbaev, A. N.
Barbagli, G.
Bari, G.
Barreiro, F.
Bartsch, D.
Basile, M.
Behnke, O.
Behr, J.
Behrens, U.
Bellagamba, L.
Bertolin, A.
Bhadra, S.
Bindi, M.
Blohm, C.
Bold, T.
Boos, E. G.
Borodin, M.
Borras, K.
Boscherini, D.
Bot, D.
Boutle, S. K.
Brock, I.
Brownson, E.
Brugnera, R.
Bruemmer, N.
Bruni, A.
Bruni, G.
Brzozowska, B.
Bussey, P. J.
Butterworth, J. M.
Bylsma, B.
Caldwell, A.
Capua, M.
Carlin, R.
Catterall, C. D.
Chekanov, S.
Chwastowski, J.
Ciborowski, J.
Ciesielski, R.
Cifarelli, L.
Cindolo, F.
Contin, A.
Cooper-Sarkar, A. M.
Coppola, N.
Corradi, M.
Corriveau, F.
Costa, M.
D'Agostini, G.
de Favereau, J.
del Peso, J.
Dementiev, R. K.
De Pasquale, S.
Derrick, M.
Devenish, R. C. E.
Dobur, D.
Dolgoshein, B. A.
Doyle, A. T.
Drugakov, V.
Durkin, L. S.
Dusini, S.
Eisenberg, Y.
Ermolov, P. F.
Eskreys, A.
Fang, S.
Fazio, S.
Ferrando, J.
Ferrero, M. I.
Figiel, J.
Forrest, M.
Foster, B.
Fourletov, S.
Gach, G.
Galas, A.
Gallo, E.
Garfagnini, A.
Geiser, A.
Gialas, I.
Gladilin, L. K.
Gladkov, D.
Glasman, C.
Gogota, O.
Golubkov, Yu. A.
Goettlicher, P.
Grabowska-Bold, I.
Grebenyuk, J.
Gregor, I.
Grigorescu, G.
Grzelak, G.
Gwenlan, C.
Haas, T.
Hain, W.
Hamatsu, R.
Hart, J. C.
Hartmann, H.
Hartner, G.
Hilger, E.
Hochman, D.
Holm, U.
Hori, R.
Horton, K.
Huettmann, A.
Iacobucci, G.
Ibrahim, Z. A.
Iga, Y.
Ingbir, R.
Ishitsuka, M.
Jakob, H. -P.
Januschek, F.
Jimenez, M.
Jones, T. W.
Juengst, M.
Kadenko, I.
Kahle, B.
Kamaluddin, B.
Kananov, S.
Kanno, T.
Karshon, U.
Karstens, F.
Katkov, I. I.
Kaur, M.
Kaur, P.
Keramidas, A.
Khein, L. A.
Kim, J. Y.
Kisielewska, D.
Kitamura, S.
Klanner, R.
Klein, U.
Koffeman, E.
Kollar, D.
Kooijman, P.
Korol, Ie.
Korzhavina, I. A.
Kotanski, A.
Koetz, U.
Kowalski, H.
Kulinski, P.
Kuprash, O.
Kuze, M.
Kuzmin, V. A.
Lee, A.
Levchenko, B. B.
Levy, A.
Libov, V.
Limentani, S.
Ling, T. Y.
Lisovyi, M.
Lobodzinska, E.
Lohmann, W.
Loehr, B.
Lohrmann, E.
Loizides, J. H.
Long, K. R.
Longhin, A.
Lontkovskyi, D.
Lukina, O. Yu.
Luzniak, P.
Maeda, J.
Magill, S.
Makarenko, I.
Malka, J.
Mankel, R.
Margotti, A.
Marini, G.
Martin, J. F.
Mastroberardino, A.
Matsumoto, T.
Mattingly, M. C. K.
Melzer-Pellmann, I. -A.
Miglioranzi, S.
Mohamad Idris, F.
Monaco, V.
Montanari, A.
Morris, J. D.
Musgrave, B.
Nagano, K.
Namsoo, T.
Nania, R.
Nicholass, D.
Nigro, A.
Ning, Y.
Noor, U.
Notz, D.
Nowak, R. J.
Nuncio-Quiroz, A. E.
Oh, B. Y.
Okazaki, N.
Oliver, K.
Olkiewicz, K.
Onishchuk, Yu.
Ota, O.
Papageorgiu, K.
Parenti, A.
Paul, E.
Pawlak, J. M.
Pawlik, B.
Pelfer, P. G.
Pellegrino, A.
Perlanski, W.
Perrey, H.
Piotrzkowski, K.
Plucinski, P.
Pokrovskiy, N. S.
Polini, A.
Proskuryakov, A. S.
Przybycien, M.
Raval, A.
Reeder, D. D.
Reisert, B.
Ren, Z.
Repond, J.
Ri, Y. D.
Robertson, A.
Roloff, P.
Ron, E.
Rubinsky, I.
Ruspa, M.
Sacchi, R.
Salii, A.
Samson, U.
Sartorelli, G.
Savin, A. A.
Saxon, D. H.
Schioppa, M.
Schlenstedt, S.
Schleper, P.
Schmidke, W. B.
Schneekloth, U.
Schoenberg, V.
Schoerner-Sadenius, T.
Schwartz, J.
Sciulli, F.
Shcheglova, L. M.
Shehzadi, R.
Shimizu, S.
Singh, I.
Skillicorn, I. O.
Slominski, W.
Smith, W. H.
Sola, V.
Solano, A.
Son, D.
Sosnovtsev, V.
Spiridonov, A.
Stadie, H.
Stanco, L.
Stern, A.
Stewart, T. P.
Stifutkin, A.
Stopa, P.
Suchkov, S.
Susinno, G.
Suszycki, L.
Sztuk, J.
Szuba, D.
Szuba, J.
Tapper, A. D.
Tassi, E.
Terron, J.
Theedt, T.
Tiecke, H.
Tokushuku, K.
Tomalak, O.
Tomaszewska, J.
Tsurugai, T.
Turcato, M.
Tymieniecka, T.
Uribe-Estrada, C.
Vazquez, M.
Verbytskyi, A.
Viazlo, V.
Vlasov, N. N.
Volynets, O.
Walczak, R.
Wan Abdullah, W. A. T.
Whitmore, J. J.
Whyte, J.
Wiggers, L.
Wing, M.
Wlasenko, M.
Wolf, G.
Wolfe, H.
Wrona, K.
Yagues-Molina, A. G.
Yamada, S.
Yamazaki, Y.
Yoshida, R.
Youngman, C.
Zarnecki, A. F.
Zawiejski, L.
Zenaiev, O.
Zeuner, W.
Zhautykov, B. O.
Zhmak, N.
Zhou, C.
Zichichi, A.
Zolko, M.
Zotkin, D. S.
Zulkapli, Z.
notspecified
ZEUS
Beauty production in deep inelastic scattering with events in which a muon and a jet are observed in the final state has been measured with the ZEUS detector at HERA using an integrated luminosity of 114 pb^-1. The fraction of events with beauty quarks in the data was determined using the distribution of the transverse momentum of the muon relative to the jet. The cross section for beauty production was measured in the kinematic range of photon virtuality, Q^2 > 2 Gev^2, and inelasticity, 0.05 < y < 0.7, with the requirement of a muon and a jet. Total and differential cross sections are presented and compared to QCD predictions. The beauty contribution to the structure function F_2 was extracted and is compared to theoretical predictions.
Article
http://edoc.mpg.de/542840
oai:edoc.mpg.de:5428412011-03-1161:916
String GUT Scenarios with Stabilised Moduli
Blumenhagen, Ralph
Moster, Sebastian
Plauschinn, Erik
notspecified
Theoretical Physics
Taking into account the recently proposed poly-instanton corrections to the superpotential and combining the race-track with a KKLT respectively LARGE Volume Scenario in an intricate manner, we show that we gain exponential control over the parameters in an effective superpotential. This allows us to dynamically stabilise moduli such that a conventional MSSM scenario with the string scale lowered to the GUT scale is realised. Depending on the cycles wrapped by the MSSM branes, two different scenarios for the hierarchy of soft masses arise. The first one is a supergravity mediated model with M_3/2=1TeV while the second one features mixed anomaly-supergravity mediation with M_3/2=10^10GeV and split supersymmetry. We also comment on dynamically lowering the scales such that the tree-level cosmological constant is of the order \Lambda=(10^-3eV)^4.
2008
Article
http://edoc.mpg.de/542841
Physical Review D, 066008 (2008)
oai:edoc.mpg.de:5428432011-03-1161:916
The contribution of fermionic seesaws to the anomalous magnetic moment of leptons
Biggio, C.
notspecified
Phenomenology of High Energy Physics
We calculate the contribution to the anomalous magnetic moment of leptons in the type-I and type-III seesaw models. We show that, even if the scale of the new physics is pushed down to the electroweak scale, this contribution is not large enough to explain the measured discrepancy of the muon anomalous magnetic moment.
2008
Article
http://edoc.mpg.de/542843
Physics Letters B, 378-384 (2008)
oai:edoc.mpg.de:5428442011-03-1161:916
VHE Gamma-Ray Observation of the Crab Nebula and its Pulsar with the MAGIC Telescope
MAGIC Collaboration
Albert, J.
notspecified
MAGIC
We report about very high energy (VHE) gamma-ray observations of the Crab Nebula with the MAGIC telescope. The gamma-ray flux from the nebula was measured between 60 GeV and 9 TeV. The energy spectrum can be described with a curved power law dF/dE=f0 (E/300 GeV)^(a+b*log10(E/300 GeV)) with a flux normalization f0 of(6.0+-0.2)*10^-10 1/(cm^2 s TeV), a=-2.31+-0.06 and b=-0.26+-0.07. The position of the IC-peak is determined at (77+-47) GeV. Within the observation time and the experimental resolution of the telescope, the gamma-ray emission is steady and pointlike. The emission's center of gravity coincides with the position of the pulsar. Pulsed gamma-ray emission from the pulsar could not be detected. We constrain the cutoff energy of the spectrum to be less than 27 GeV, assuming that the differential energy spectrum has an exponential cutoff. For a super-exponential shape, the cutoff energy can be as high as 60 GeV.
2008
Article
http://edoc.mpg.de/542844
Astrophysical Journal, 1037-1055 (2008)
oai:edoc.mpg.de:5428452011-03-1161:916
Distributions for MSSM Higgs boson + jet production at hadron colliders
Brein, Oliver
Hollik, Wolfgang
notspecified
Phenomenology of High Energy Physics
We present pseudorapidity and transverse momentum distributions for the cross section for the production of the lightest neutral Higgs boson in association with a high-p_T hadronic jet, calculated in the framework of the minimal supersymmetric standard model (MSSM). We discuss the theoretical predictions for the differential cross sections at the Large Hadron Collider and the Tevatron for the most common benchmark scenarios.
2007
Article
http://edoc.mpg.de/542845
Physical Review D, 035002 (2007)
oai:edoc.mpg.de:5428472011-03-1161:916
Instantons and Holomorphic Couplings in Intersecting D-brane Models
Akerblom, Nikolas
Blumenhagen, Ralph
Lust, Dieter
Schmidt-Sommerfeld, Maximilian
notspecified
Theoretical Physics
We clarify certain aspects and discuss extensions of the recently introduced string D-instanton calculus (href{/abs/hep-th/0609191}{hep-th/0609191}). The one-loop determinants are related to one-loop open string threshold corrections in intersecting D6-brane models. Utilising a non-renormalisation theorem for the holomorphic Wilsonian gauge kinetic functions, we derive a number of constraints for the moduli dependence of the matter field Kaehler potentials of intersecting D6-brane models on the torus. Moreover, we compute string one-loop corrections to the Fayet-Iliopoulos terms on the D6-branes finding that they are proportional to the gauge threshold corrections. Employing these results, we discuss the issue of holomorphy for E2-instanton corrections to the superpotential. Eventually, we discuss E2-instanton corrections to the gauge kinetic functions and the FI-terms.
2007
Article
http://edoc.mpg.de/542847
Journal of High Energy Physics, 44 (2007)
oai:edoc.mpg.de:5428492011-03-1161:916
The effective electroweak mixing angle $\sin^2\theta_{eff}$ with two-loop bosonic contributions
Hollik, W.
Meier, U.
Uccirati, S.
notspecified
Phenomenology of High Energy Physics
We present the results for the full electroweak two-loop bosonic contributions to the effective leptonic mixing angle of the $Z$ boson, $\sin^2\theta_{\rm eff}$, in the Standard Model. A method applied to extract collinear divergences from two-loop vertex-functions is described. Comparisons of our results with those from a recent previous calculation show complete agreement.
2007
Article
http://edoc.mpg.de/542849
Nuclear Physics B, 154-165 (2007)
oai:edoc.mpg.de:5428502011-03-1161:916
Search for Squarks in R-parity Violating Supersymmetry in ep Collisions at HERA
H1 Collaboration
notspecified
H1
A search for squarks in R-parity violating supersymmetry is performed in e^+- p collisions at HERA using the H1 detector. The full data sample taken at a centre-of-mass energy sqrt{s}=319 GeV is used for the analysis, corresponding to an integrated luminosity of 255 pb^-1 of e^+ p and 183 pb^-1 of e^- p collision data. The resonant production of squarks via a Yukawa coupling lambda' is considered, taking into account direct and indirect R-parity violating decay modes. Final states with jets and leptons are investigated. No evidence for squark production is found and mass dependent limits on lambda' are obtained in the framework of the Minimal Supersymmetric Standard Model and in the Minimal Supergravity Model. In the considered part of the parameter space, for a Yukawa coupling of electromagnetic strength lambda'= 0.3, squarks of all flavours are excluded up to masses of 275 GeV at 95% confidence level, with down-type squarks further excluded up to masses of 290 GeV.
Article
http://edoc.mpg.de/542850
oai:edoc.mpg.de:5428512011-03-1161:916
Thresholds for Intersecting D-branes Revisited
Akerblom, Nikolas
Blumenhagen, Ralph
Lust, Dieter
Schmidt-Sommerfeld, Maximilian
notspecified
Theoretical Physics
Gauge threshold corrections for intersecting D6-brane string models on toroidal orbifold backgrounds are reconsidered. Both by dimensionally regularising the appearing open string one-loop diagrams in tree-channel as well as by zeta-function regularisation of the corresponding loop-channel one-loop diagrams, we arrive at a result which takes into account the infrared divergence from the contribution of the massless states in the running of the gauge coupling constant as well as the contribution of states, which become light in certain regions of the moduli space.
2007
Article
http://edoc.mpg.de/542851
Physics Letters B, 53-59 (2007)
oai:edoc.mpg.de:5428522011-03-1161:916
Measurement of alpha_S in e+e- collisions at LEP and JADE
Schieck, J.
notspecified
JADE
Data from e+e- annihilation into hadrons collected by the JADE, the L3 and the OPAL experiment at centre-of-mass energies between 14 GeV and 209 GeV are used to determine the strong coupling alpha_S. Observables in leading order sensitive to alpha_S as well as alpha_S**2 are used. The evolution of alpha_S with respect to the centre-of-mass energy as predicted by QCD is studied and confirmed with high precision. All measurements of alpha_S are consistent with the current world average.
Conference-Paper
http://edoc.mpg.de/542852
oai:edoc.mpg.de:5428532011-03-1161:916
Collective neutrino flavor transitions in supernovae and the role of trajectory averaging
Fogli, G. L.
Lisi, E.
Marrone, A.
Mirizzi, A.
notspecified
Astroparticle Physics
Non-linear effects on supernova neutrino oscillations, associated with neutrino self-interactions, are known to induce collective flavor transitions near the supernova core for theta_13 \neq 0. In scenarios with very shallow electron density profiles, these transformations have been shown to couple with ordinary matter effects, jointly producing spectral distortions both in normal and inverted hierarchy. In this work we consider a complementary scenario, characterized by higher electron density, as indicated by post-bounce shock-wave simulations. In this case, early collective flavor transitions are decoupled from later, ordinary matter effects. Moreover, such transitions become more amenable to both numerical computations and analytical interpretations in inverted hierarchy, while they basically vanish in normal hierarchy. We numerically evolve the neutrino density matrix in the region relevant for self-interaction effects. In the approximation of averaged intersection angle between neutrino trajectories, our simulations neatly show the collective phenomena of synchronization, bipolar oscillations, and spectral split, recently discussed in the literature. In the more realistic (but computationally demanding) case of non-averaged neutrino trajectories, our simulations do not show new significant features, apart from the smearing of ``fine structures'' such as bipolar nutations. Our results seem to suggest that, at least for non-shallow matter density profiles, averaging over neutrino trajectories plays a minor role in the final outcome. In this case, the swap of nu_e and nu_{\mu,\tau} spectra above a critical energy may represent an unmistakable signature of the inverted hierarchy, especially for theta_{13} small enough to render further matter effects irrelevant.
2007
Article
http://edoc.mpg.de/542853
Journal of Cosmology and Astroparticle Physics, 010 (2007)
oai:edoc.mpg.de:5428542011-03-1161:916
A Combination of Preliminary Electroweak Measurements and Constraints on the Standard Model
The LEP Collaborations
ALEPH Collaboration
DELPHI Collaboration
L3 Collaboration
OPAL Collaboration
the LEP Electroweak Working Group
Electroweak, the SLD
Groups, Heavy Flavour
notspecified
OPAL
This note presents a combination of published and preliminary electroweak results from the four LEP collaborations and the SLD collaboration which were prepared for the 2004 summer conferences. [...] The main changes with respect to the experimental results presented in summer 2003 are updates to the W branching fractions and four-fermion cross sections measured at LEP-2, and the SLD/LEP heavy-flavour results measured at the Z pole. The results are compared with precise electroweak measurements from other experiments, notably the final result on the electroweak mixing angle determined in neutrino-nucleon scattering by the NuTeV collaboration, the latest result in atomic parity violation in Caesium, and the measurement of the electroweak mixing angle in Moller scattering. The parameters of the Standard Model are evaluated, first using the combined LEP electroweak measurements, and then using the full set of high-$Q^2$ electroweak results.
Article
http://edoc.mpg.de/542854
oai:edoc.mpg.de:5428562011-03-1161:916
Measurement of Dijet Cross Sections in ep Interactions with a Leading Neutron at HERA
H1 Collaboration
notspecified
H1
Measurements are reported of the production of dijet events with a leading neutron in ep interactions at HERA. Differential cross sections for photoproduction and deep inelastic scattering are presented as a function of several kinematic variables. Leading order QCD simulation programs are compared with the measurements. Models in which the real or virtual photon interacts with a parton of an exchanged pion are able to describe the data. Next-to-leading order perturbative QCD calculations based on pion exchange are found to be in good agreement with the measured cross sections. The fraction of leading neutron dijet events with respect to all dijet events is also determined. The dijet events with a leading neutron have a lower fraction of resolved photon processes than do the inclusive dijet data.
2005
Article
http://edoc.mpg.de/542856
European Physical Journal C, 273-286 (2005)
oai:edoc.mpg.de:5428602011-03-1161:916
Stochastic Gravitational Wave Background from Cosmological Supernovae
Buonanno, Alessandra
Sigl, Guenter
Raffelt, Georg G.
Janka, Hans-Thomas
Mueller, Ewald
notspecified
Astroparticle Physics
Based on new developments in the understanding of supernovae as gravitational-wave (GW) sources, we estimate the GW background from all cosmic supernovae. While our estimate is uncertain within a few orders of magnitude, this background may become detectable by second-generation space-based interferometers such as the proposed Big-Bang Observatory. At frequencies below about 1 Hz this GW background is stochastic. Down to about 0.01 Hz it could well be of comparable magnitude to the one expected from standard inflationary models, especially in the presence of an early population of massive stars.
2005
Article
http://edoc.mpg.de/542860
Physical Review D, 084001 (2005)
oai:edoc.mpg.de:5428612011-03-1161:916
The CRESST Dark Matter Search
Majorovits, B.
Angloher, G.
Bucci, C.
Christ, P.
Cozzini, C.
von Feilitzsch, F.
Hauff, D.
Henry, S.
Jagemann, Th.
Jochum, J.
Kraus, H.
Mikhailik, V.
Ninkovic, J.
Petricca, F.
Potzel, W.
Proebst, F.
Ramachers, Y.
Razeti, M.
Rau, W.
Seidel, W.
Stark, M.
Stodolsky, L.
Tolhurst, A. J. B.
Wahl, D.
Westphal, W.
Wulandari, H.
notspecified
CRESST
We present first competitive results on WIMP dark matter using the phonon-light-detection technique. A particularly strong limit for WIMPs with coherent scattering results from selecting a region of the phonon-light plane corresponding to tungsten recoils. The observed count rate in the neutron band is compatible with the rate expected from neutron background. CRESST is presently being upgraded with a 66 channel SQUID readout system, a neutron shield and a muon veto system. This results in a significant improvement in sensitivity.
World Scientific
2005
Conference-Paper
http://edoc.mpg.de/542861
V. Kudryavtsdev, N. Spooner: Proceedings of the 5th International Workshop on the Identification and Detection of Dark Matter IDM 2004, Edinburgh, Sept. 2004, World Scientific (2005)
oai:edoc.mpg.de:5428692011-03-1161:916
Pseudorapidity Asymmetry and Centrality Dependence of Charged Hadron Spectra in d+Au Collisions at $\sqrt{s_{NN}}=200$ GeV
STAR Collaboration
Adams, J.
Eckardt, V.
Putschke, J.
Schmitz, N.
Seyboth, P.
Simon, F.
et al.
notspecified
STAR
The pseudorapidity asymmetry and centrality dependence of charged hadron spectra in d+Au collisions at $\sqrt{s_{NN}}=200$ GeV are presented. The charged particle density at mid-rapidity, its pseudorapidity asymmetry and centrality dependence are reasonably reproduced by a Multi-Phase Transport model, by HIJING, and by the latest calculations in a saturation model. Ratios of transverse momentum spectra between backward and forward pseudorapidity are above unity for \pT below 5 GeV/$c$. The ratio of central to peripheral spectra in d+Au collisions shows enhancement at 2 $<$ \pT $<$ 6 GeV/$c$, with a larger effect at backward rapidity than forward rapidity. Our measurements are in qualitative agreement with gluon saturation and in contrast to calculations based on incoherent multiple partonic scatterings.
2004
Article
http://edoc.mpg.de/542869
Physical Review C, 064907 (2004)
oai:edoc.mpg.de:5428702011-03-1161:916
Measurements of transverse energy distributions in Au+Au collisions at $\sqrt{s_{NN}}= 200$ GeV
STAR Collaboration
Adams, J.
Eckardt, V.
Mora-Corral, M.
Putschke, J.
Schmitz, N.
Seyboth, P.
Simon, F.
et al.
notspecified
STAR
Transverse energy ($E_T$) distributions have been measured for Au+Au collisions at $\sqrt{s_{NN}}= 200$ GeV by the STAR collaboration at RHIC. $E_T$ is constructed from its hadronic and electromagnetic components, which have been measured separately. $E_T$ production for the most central collisions is well described by several theoretical models whose common feature is large energy density achieved early in the fireball evolution. The magnitude and centrality dependence of $E_T$ per charged particle agrees well with measurements at lower collision energy, indicating that the growth in $E_T$ for larger collision energy results from the growth in particle production. The electromagnetic fraction of the total $E_T$ is consistent with a final state dominated by mesons and independent of centrality.
2004
Article
http://edoc.mpg.de/542870
Physical Review C, 054907 (2004)
oai:edoc.mpg.de:5428712011-03-1161:916
Photon and neutral pion production in Au+Au collisions at sqrt(s_{NN}) = 130 GeV
STAR Collaboration
Adams, J.
Eckardt, V.
Mora-Corral, M.
Putschke, J.
Schmitz, N.
Seyboth, P.
Simon, F.
et al.
notspecified
STAR
We report the first inclusive photon measurements about mid-rapidity (|y|<0.5) from Au+Au collisions at sqrt(s_{NN}) = 130 GeV at RHIC. Photon pair conversions were reconstructed from electron and positron tracks measured with the Time Projection Chamber (TPC) of the STAR experiment. With this method, an energy resolution of Delta(E)/E = 2% at 0.5 GeV has been achieved. Reconstructed photons have also been used to measure the transverse momentum (pt) spectra of pi0 mesons about mid-rapidity (|y|<1) via the pi0 -> photon photon decay channel. The fractional contribution of the pi0 -> photon photon decay to the inclusive photon spectrum decreases by 20% +/- 5% between pt = 1.65 GeV/c and pt = 2.4 GeV/c in the most central events, indicating that relative to pi0 -> photon photon decay the contribution of other photon sources is substantially increasing.
2004
Article
http://edoc.mpg.de/542871
Physical Review C, 044902 (2004)
oai:edoc.mpg.de:5428722011-03-1161:916
Strangeness from 20 AGeV to 158 AGeV
Alt, C.
Eckardt, V.
Schmitz, N.
Seyboth, P.
et al.
notspecified
NA49
New results from the energy scan programme of NA49, in particular kaon
production at 30AGeV and Phi production at 40 and 80AGeV are presented. The
K^+/pi^+ ratio shows a pronounced maximum at 30AGeV; the kaon slope parameters
are constant at SPS energies. Both findings support the scenario of a phase transition
at about 30AGeV beam energy. The Phi/pi ratio increases smoothly with beam energy,
showing an energy dependence similar to K^-/pi^-. The measured particle yields can be
reproduced by a hadron gas model, with chemical freeze-out parameters on a smooth
curve in the T - mu_B plane. The transverse spectra can be understood as resulting from
a rapidly expanding, locally equilibrated source. No evidence for an earlier kinetic
decoupling of heavy hyperons is found.
2004
Article
http://edoc.mpg.de/542872
Journal of Physics G: Nuclear and Particle Physics, 119-128 (2004)
oai:edoc.mpg.de:5428732011-03-1161:916
Self-induced spectral splits in supernova neutrino fluxes
Raffelt, Georg G.
Smirnov, Alexei Yu.
notspecified
Astroparticle Physics
In the dense-neutrino region above the neutrino sphere of a supernova (r < 400 km), neutrino-neutrino refraction causes collective flavor transformations. They can lead to "spectral splits" where an energy E_c splits the transformed spectrum sharply into parts of almost pure but different flavors. Unless there is an ordinary MSW resonance in the dense-neutrino region, E_c is determined by flavor-lepton number conservation alone. Spectral splits are created by an adiabatic transition between regions of large and small neutrino density. We solve the equations of motion in the adiabatic limit explicitly and provide analytic expressions for a generic example.
2007
Article
http://edoc.mpg.de/542873
Physical Review D, 081301 (2007)
oai:edoc.mpg.de:5428742011-03-1161:916
Diffuse Cosmic Neutrino Background from Population III Stars
Iocco, F.
Mangano, G.
Miele, G.
Raffelt, G. G.
Serpico, P. D.
notspecified
Astroparticle Physics
We study the expected diffuse cosmic neutrino flux produced by Population III (PopIII) stars during their nuclear burning phases as well as from their final stages of evolution (core collapse). Assuming a fraction f_III=10^(-3) of all baryons forms PopIII stars, our flux estimate is comparable to the diffuse neutrino flux produced by the ordinary stars and by the ordinary core-collapse supernovae in the universe, i.e. of order 1-10 cm^(-2) s^(-1). Due to the large cosmic redshift, however, the typical energies are in the MeV and sub-MeV range where the solar and geophysical neutrino fluxes are much larger. A direct detection of the diffuse cosmic flux is out of the question with presently known experimental techniques.
2005
Article
http://edoc.mpg.de/542874
Astroparticle Physics, 303 (2005)
oai:edoc.mpg.de:5428752011-03-1161:916
Electroweak Physics
Hollik, W.
et al.
notspecified
Phenomenology of High Energy Physics
Work on electroweak precision calculations and event generators for
electroweak physics studies at current and future colliders is summarized.
2004
Conference-Paper
http://edoc.mpg.de/542875
Acta Physica Polonica B, 35, 2533-2555 (2004)
oai:edoc.mpg.de:5428762011-03-1161:916
Production of $e^+e^-$ Pairs Accompanied by Nuclear Dissociation in Ultra-Peripheral Heavy Ion Collisions
STAR Collaboration
Adams, J.
Eckardt, V.
Mora-Corral, M.
Putschke, J.
Schmitz, N.
Seyboth, P.
Simon, F.
et al.
notspecified
STAR
We present the first data on $e^+e^-$ pair production accompanied by nuclear breakup in ultra-peripheral gold-gold collisions at a center of mass energy of 200 GeV per nucleon pair. The nuclear breakup requirement selects events at small impact parameters, where higher-order corrections to the pair production cross section should be enhanced. We compare the pair kinematic distributions with two calculations: one based on the equivalent photon approximation, and the other using lowest-order quantum electrodynamics (QED); the latter includes the photon virtuality. The cross section, pair mass, rapidity and angular distributions are in good agreement with both calculations. The pair transverse momentum, $p_T$, spectrum agrees with the QED calculation, but not with the equivalent photon approach. We set limits on higher-order contributions to the cross section. The $e^+$ and $e^-$ $p_T$ spectra are similar, with no evidence for interference effects due to higher-order diagrams.
2004
Article
http://edoc.mpg.de/542876
Physical Review C, 031902 (2004)
oai:edoc.mpg.de:5428772011-03-1161:916
Centrality and pseudorapidity dependence of charged hadron production at intermediate p_T in Au + Au collisions at sqrt(s_NN) = 130 GeV
STAR Collaboration
Adams, J.
Eckardt, V.
Mora-Corral, M.
Putschke, J.
Schmitz, N.
Seyboth, P.
Simon, F.
et al.
notspecified
STAR
We present STAR measurements of charged hadron production as a function of centrality in Au + Au collisions at sqrt(s_NN) = 130 GeV. The measurements cover a phase space region of 0.2 < p_T < 6.0 GeV/c in transverse momentum and -1 < eta < 1 in pseudorapidity. Inclusive transverse momentum distributions of charged hadrons in the pseudorapidity region 0.5 < |eta| < 1 are reported and compared to our previously published results for |eta| < 0.5. No significant difference is seen for inclusive p_T distributions of charged hadrons in these two pseudorapidity bins. We measured dN/deta distributions and truncated mean p_T in a region of p_T > p_T^cut, and studied the results in the framework of participant and binary scaling. No clear evidence is observed for participant scaling of charged hadron yield in the measured p_T region. The relative importance of hard scattering process is investigated through binary scaling fraction of particle production.
2004
Article
http://edoc.mpg.de/542877
Physical Review C, 044901 (2004)
oai:edoc.mpg.de:5428782011-03-1161:916
Probing the Reheating Temperature at Colliders and with Primordial Nucleosynthesis
Steffen, Frank Daniel
notspecified
Astroparticle Physics
Considering gravitino dark matter scenarios with a long-lived charged slepton, we show that collider measurements of the slepton mass and its lifetime can probe not only the gravitino mass but also the post-inflationary reheating temperature TR. In a model independent way, we derive upper limits on TR and discuss them in light of the constraints from the primordial catalysis of ^6Li through bound-state effects. In the collider-friendly region of slepton masses below 1 TeV, the obtained conservative estimate of the maximum reheating temperature is about TR=3\times 10^9 GeV for the limiting case of a small gluino-slepton mass splitting and about TR=10^8 GeV for the case that is typical for universal soft supersymmetry breaking parameters at the scale of grand unification. We find that a determination of the gluino-slepton mass ratio at the Large Hadron Collider will test the possibility of TR>10^9 GeV and thereby the viability of thermal leptogenesis.
2008
Article
http://edoc.mpg.de/542878
Physics Letters B, 74-80 (2008)
oai:edoc.mpg.de:5428792011-03-1161:916
Electric charge fluctuations in central Pb+Pb collisions at 20, 30, 40, 80 and 158 AGeV
NA49 Collaboration
Alt, C.
Eckardt, V.
Schmitz, N.
Seyboth, P.
et al.
notspecified
NA49
Results are presented on event-by-event electric charge fluctuations in central Pb+Pb collisions at 20, 30, 40, 80 and 158 AGeV. The observed fluctuations are close to those expected for a gas of pions correlated by global charge conservation only. These fluctuations are considerably larger than those calculated for an ideal gas of deconfined quarks and gluons. The present measurements do not necessarily exclude reduced fluctuations from a quark-gluon plasma because these might be masked by contributions from resonance decays.
2004
Article
http://edoc.mpg.de/542879
Physical Review C, 064903 (2004)
oai:edoc.mpg.de:5428812011-03-1161:916
Azimuthal anisotropy and correlations at large transverse momenta in $p+p$ and Au+Au collisions at $\sqrt{s_{_{NN}}}$= 200 GeV
STAR Collaboration
Adams, J.
Eckardt, V.
Putschke, J.
Schmitz, N.
Seyboth, P.
Simon, F.
et al.
notspecified
STAR
Results on high transverse momentum charged particle emission with respect to the reaction plane are presented for Au+Au collisions at $\sqrt{s_{_{NN}}}$= 200 GeV. Two- and four-particle correlations results are presented as well as a comparison of azimuthal correlations in Au+Au collisions to those in $p+p$ at the same energy. Elliptic anisotropy, $v_2$, is found to reach its maximum at $p_t \sim 3$ GeV/c, then decrease slowly and remain significant up to $p_t\approx 7$ -- 10 GeV/c. Stronger suppression is found in the back-to-back high-$p_t$ particle correlations for particles emitted out-of-plane compared to those emitted in-plane. The centrality dependence of $v_2$ at intermediate $p_t$ is compared to simple models based on jet quenching.
2004
Article
http://edoc.mpg.de/542881
Physical Review Letters, 252301 (2004)
oai:edoc.mpg.de:5428822011-03-1161:916
Field Theory on Kappa-Spacetime
Dimitrijevic, M.
Jonke, L.
Moeller, L.
Tsouchnike, E.
Wess, J.
notspecified
Theoretical Physics
A general formalism is developed that allows the construction of field theory on quantum spaces which are deformations of ordinary spacetime. The symmetry group of spacetime is replaced by a quantum group. This formalism is demonstrated for the kappa-deformed Poincare algebra and its quantum space. The algebraic setting is mapped to the algebra of functions of commuting variables with a suitable star-product. Fields are elements of this function algebra. As an example, the Klein-Gordon equation is defined and derived from an action.
2004
Conference-Paper
http://edoc.mpg.de/542882
Czechoslovak Journal of Physics, 54, 1243-1248 (2004)
oai:edoc.mpg.de:5428862011-03-1161:916
A Direct Search for Stable Magnetic Monopoles Produced in Positron-Proton Collisions at HERA
H1 Collaboration
notspecified
H1
A direct search has been made for magnetic monopoles produced in e^+ p collisions at a centre of mass energy of 300 GeV at HERA. The beam pipe surrounding the interaction region in 1995-1997 was investigated using a SQUID magnetometer to look for stopped magnetic monopoles. During this time an integrated luminosity of 62 pb^{-1} was delivered. No magnetic monopoles were observed and charge and mass dependent upper limits on the e^+ p production cross section are set.
2005
Article
http://edoc.mpg.de/542886
European Physical Journal C, 133-141 (2005)
oai:edoc.mpg.de:5428872011-03-1161:916
Search for Light Gravitinos in Events with Photons and Missing Transverse Momentum at HERA
H1 Collaboration
notspecified
H1
A search for gravitinos produced in ep collisions is performed using the H1 detector at HERA. The data were taken at a centre-of-mass energy of 319 GeV and correspond to an integrated luminosity of 64.3 pb^{-1} for e^+p collisions and 13.5 pb^{-1} for e^-p collisions. If R-parity is not conserved, the t-channel exchange of a selectron can produce a neutralino, which, in models where the gravitino is the lightest supersymmetric particle, subsequently decays into a photon and a light gravitino. The resulting event signature, which involves an isolated photon, a jet and missing transverse energy, is analysed for the first time at HERA. No deviation from the Standard Model is found. Exclusion limits on the cross section and on R-parity-violating Yukawa couplings are derived in a Gauge Mediated Supersymmetry Breaking scenario. The results are independent of the squark sector. Neutralinos and supersymmetric partners of the left-handed electron with masses up to 112 GeV and 164 GeV, respectively, can be ruled out at the 95% confidence level for R-parity-violating couplings lambda' equal to 1.
2005
Article
http://edoc.mpg.de/542887
Physics Letters B, 31-42 (2005)
oai:edoc.mpg.de:5428882011-03-1161:916
Measurement of F2cc and F2bb at High Q2 using the H1 Vertex Detector at HERA
H1 Collaboration
notspecified
H1
Measurements are presented of inclusive charm and beauty cross sections in e^+p collisions at HERA for values of photon virtuality Q^2 > 150 GeV^2 and of inelasticity 0.1 < y < 0.7. The charm and beauty fractions are determined using a method based on the impact parameter, in the transverse plane, of tracks to the primary vertex, as measured by the H1 vertex detector. The data are divided into four regions in Q^2 and Bjorken x, and values for the structure functions F_2^{c\bar{c}} and F_2^{b\bar{b}} are obtained. The results are found to be compatible with the predictions of perturbative quantum chromodynamics.
2005
Article
http://edoc.mpg.de/542888
European Physical Journal C, 349-359 (2005)
oai:edoc.mpg.de:5428892011-03-1161:916
Prospects in Constraining the Dark Energy Potential
Fernandez-Martinez, Enrique
Verde, Licia
notspecified
Astroparticle Physics
We generalize to non-flat geometries the formalism of Simon et al. (2005) to reconstruct the dark energy potential. This formalism makes use of quantities similar to the Horizon-flow parameters in inflation, can, in principle, be made non-parametric and is general enough to be applied outside the simple, single scalar field quintessence. Since presently available and forthcoming data do not allow a non-parametric and exact reconstruction of the potential, we consider a general parametric description in term of Chebyshev polynomials. We then consider present and future measurements of H(z), Baryon Acoustic Oscillations surveys and Supernovae type 1A surveys, and investigate their constraints on the dark energy potential. We find that, relaxing the flatness assumption increases the errors on the reconstructed dark energy evolution but does not open up significant degeneracies, provided that a modest prior on geometry is imposed. Direct measurements of H(z), such as those provided by BAO surveys, are crucially important to constrain the evolution of the dark energy potential and the dark energy equation of state, especially for non-trivial deviations from the standard LambdaCDM model.
2008
Article
http://edoc.mpg.de/542889
Journal of Cosmology and Astroparticle Physics, 023 (2008)
oai:edoc.mpg.de:5428902011-03-1161:916
Constraints on Anomalous Quaric Gauge Boson Couplings from vv gamma gamma and qq gamma gamma events at LEP 2
The OPAL collaboration
Abbiendi, G.
et al.
notspecified
OPAL
Anomalous quartic couplings between the electroweak gauge bosons may contribute to the vv gamma gamma and qq gamma gamma final states produced in e+e- collisions. This analysis uses the LEP2 OPAL data sample at centre-of-mass energies up to 209 GeV. Event selections identify vv gamma gamma and qq gamma gamma events in which the two photons are reconstructed within the detector acceptance. The cross-section for the process e+e- -> qq gamma gamma is measured. Averaging over all energies, the ratio of the observed e+e- -> qq gamma gamma cross-section to the Standard Model expectation is R(data/SM) = 0.92 +- 0.07 +- 0.04 where the errors represent the statistical and systematic uncertainties respectively. The vv gamma gamma and qq gamma gamma data are used to constrain possible anomalous W+W- gamma gamma and ZZ gamma gamma couplings. Combining with previous OPAL results from the W+W- gamma final state, the 95% confidence level limits on the anomalous coupling parameters aoz, acz, aow and acw are found to be: -0.007 GeV^-2 < aoz/Lambda^2 < 0.023 GeV^-2 -0.029 GeV^-2 < acz/Lambda^2 < 0.029 GeV^-2 -0.020 GeV^-2 < aow/Lambda^2 < 0.020 GeV^-2 -0.052 GeV^-2 < acw/Lambda^2 < 0.037 GeV^-2 where Lamdba is the energy scale of the new physics. Limits found when allowing two or more parameters to vary are also presented.
2004
Article
http://edoc.mpg.de/542890
Physical Review D, 032005 (2004)
oai:edoc.mpg.de:5428962011-03-1161:916
On the Unfathomableness of Consciousness by Consciousness: Why do physicists widely agree on the assured extent of their professional knowledge, but not so philosophers? An exchange of letters with Carl Friedrich von Weizsaecker
Gottstein, Klaus
notspecified
Philosophy
On the occasion of Carl Friedrich von Weizsaecker's 81st birthday, a colloquium was held on July 3, 1993. One of the topics was "The epistemological foundation of physics from Kant to von Weizsaecker". I took part in the discussion. Afterwards I got the impression that I had not succeeded in making my points clear. Therefore, I wrote an explanatory letter to Prof. von Weizsaecker. This was the beginning of a correspondence on the questions intimated by the title above. In addition, a private discussion between Prof. von Weizsaecker and myself took place. Some readers may be interested in the answers which Carl Friedrich von Weizsaecker has given to the naive questions and views of a physicist with only a rudimentary education in philosophy. The starting point of our discussion was my remark that the conspicuous inability of philosophers to agree on the deepest elements of human existence including the basic questions of ethics, which is tantamount to the occurrence of different schools of philosophy competing with each other, could perhaps be traced back to the fundamental inability of man to attain self-knowledge. Physicists, on the other hand, can reach consent, in an equally remarkable way, on the results of their measurements and on whether or not these results agree with the ideas of theory. They just have to deal with res extensa. Here the yardstick does not intend to measure itself, but objects which are external to it, and this is possible. There remains only the question what consequences can be drawn from this realization. Is philosophy, in as much as it gives statements on the totality of human existence, only an expression of the prevailing social circumstances and views, interesting enough as such, but not a gateway to truth?
Springer
2003
InBook
http://edoc.mpg.de/542896
Time, Quantum and Information, 59-72 (2003)
oai:edoc.mpg.de:5428972011-03-1161:916
Heavy Quarkonium Physics
Brambilla, N.
Krämer, M.
Mussa, R.
Vairo, A.
Bali, G.
Bodwin, G. T.
Braaten, E.
Eichten, E.
Eidelman, S.
Godfrey, S.
Hoang, A.
Jamin, M.
Kharzeev, D.
Lombardo, M. P.
Lourenco, C.
Meyer, A. B.
Papadimitriou, V.
Patrignani, C.
Rosati, M.
Sanchis-Lozano, M. A.
Satz, H.
Soto, J.
Besson, D. Z.
Bettoni, D.
Böhrer, A.
Boogert, S.
Chang, C. -H.
Cooper, P.
Crochet, P.
Datta, S.
Davies, C.
Deandrea, A.
Faustov, R.
Ferguson, T.
Galik, R.
Harris, F.
Iouchtchenko, O.
Kaczmarek, O.
Karsch, F.
Kienzle, M.
Kiselev, V. V.
Klein, S. R.
Kroll, P.
Kronfeld, A.
Kuang, Y. -P.
Laporta, V.
Lee, Jungil
Leibovich, A.
Ma, J. P.
Mackenzie, P.
Maiani, L.
Mangano, M. L.
Meyer, A.
Mo, X. H.
Morningstar, C.
Nairz, A.
Napolitano, J.
Olsen, S.
Penin, A.
Petreczky, P.
Piccinini, F.
Pineda, A.
Polosa, A. D.
Ramello, L.
Rapp, R.
notspecified
Phenomenology of High Energy Physics
This report is the result of the collaboration and research effort of the Quarkonium Working Group over the last three years. It provides a comprehensive overview of the state of the art in heavy-quarkonium theory and experiment, covering quarkonium spectroscopy, decay, and production, the determination of QCD parameters from quarkonium observables, quarkonia in media, and the effects on quarkonia of physics beyond the Standard Model. An introduction to common theoretical and experimental tools is included. Future opportunities for research in quarkonium physics are also discussed.
Article
http://edoc.mpg.de/542897
oai:edoc.mpg.de:5428992011-03-1161:916
Supernova Neutrino Oscillations
Raffelt, Georg G.
notspecified
Astroparticle Physics
Observing a high-statistics neutrino signal from a galactic supernova (SN) would allow one to test the standard delayed explosion scenario and may allow one to distinguish between the normal and inverted neutrino mass ordering due to the effects of flavor oscillations in the SN envelope. One may even observe a signature of SN shock-wave propagation in the detailed time-evolution of the neutrino spectra. A clear identification of flavor oscillation effects in a water Cherenkov detector probably requires a megatonne-class experiment.
2005
Conference-Paper
http://edoc.mpg.de/542899
Physica Scripta T, 121, 102-105 (2005)
oai:edoc.mpg.de:5429002011-03-1161:916
An updated nuclear reaction network for BBN
Serpico, P. D.
notspecified
Astroparticle Physics
The key Standard-Physics inputs of the Big Bang Nucleosynthesis (BBN) are the light nuclei reaction rates. Both the network and the nuclear rates have been recently reanalyzed and updated, and cosmological and New-Physics constraints (taking into account the WMAP Cosmic Microwave Background anisotropies measurement) obtained with a new code are presented.
Conference-Paper
http://edoc.mpg.de/542900
oai:edoc.mpg.de:5429012011-03-1161:916
Supersymmetric AdS(4)
compactifications of IIA supergravity
Luest, Dieter
Tsimpis, Dimitrios
notspecified
Theoretical Physics
We derive necessary and sufficient conditions for N=1 compactifications of (massive) IIA supergravity to AdS(4) in the language of SU(3) structures. We find new solutions characterized by constant dilaton and nonzero fluxes for all form fields. All fluxes are given in terms of the geometrical data of the internal compact space. The latter is constrained to belong to a special class of half-flat manifolds.
2005
Article
http://edoc.mpg.de/542901
Journal of High Energy Physics, 027 (2005)
oai:edoc.mpg.de:5429022011-03-1161:916
Scientific Culture and Its Role in International Negotiations
Gottstein, Klaus L.
notspecified
History of Physics and Physics and Society
Scientists as diplomats (historical examples). Scientists as advisors to governments and the public. Nongovernmental organisations and international conferences on security questions, initiated by scientists and based on their professional culture.
Lexington Books
2003
InBook
http://edoc.mpg.de/542902
Professional Cultures in International Negotiation. Bridge or Rift?, 27-42 (2003)
oai:edoc.mpg.de:5429042011-03-1161:916
EXCLUSIVE ELECTROPRODUCTION OF J/PSI MESONS AT HERA.
ZEUS Collaboration
Chekanov, S.
et al.
notspecified
ZEUS
The exclusive electroproduction of J/psi mesons, ep->epJ/psi, has been studied with the ZEUS detector at HERA for virtualities of the exchanged photon in the ranges 0.15<Q^2<0.8 GeV^2 and 2<Q^2<100 GeV^2 using integrated luminosities of 69 pb^-1 and 83 pb^-1, respectively.The photon-proton centre-of-mass energy was in the range 30<W<220 GeV and the squared four-momentum transfer at the proton vertex |t|<1.The cross sections and decay angular distributions are presented as functions of Q^2, W and t. The effective parameters of the Pomeron trajectory are in agreement with those found in J/psi photoproduction. The spin-density matrix elements, calculated from the decay angular distributions, are consistent with the hypothesis of s-channel helicity conservation. The ratio of the longitudinal to transverse cross sections, sigma_L/sigma_T, grows with Q^2, whilst no dependence on W or t is observed. The results are in agreement with perturbative QCD calculations and exhibit a strong sensitivity to the gluon distribution in the proton.
2004
Article
http://edoc.mpg.de/542904
Nuclear Physics B, 3-37 (2004)
oai:edoc.mpg.de:5429092011-03-1161:916
Measurement of the Strong Coupling alpha_S from the Four-Jet Rate in e+e- annihilation
Schieck, Jochen
notspecified
OPAL
Data from e+e- annihilation into hadrons at centre-of-mass energies between 91 GeV and 209 GeV are used to study the four-jet rate as a function of the Durham algorithm's resolution parameter y_cut. The four-jet rate is compared to next-to-leading order calculations that include the resummation of large logarithms. The strong coupling measured from the four-jet rate is 0.1208 +-0.0006(stat.)+-0.0021(exp.)+-0.0019(had.)+-0.0024(scale) in agreement with the world average.
2004
Conference-Paper
http://edoc.mpg.de/542909
Nuclear Physics B - Proceedings Supplements, 152, 11-14 (2004)
oai:edoc.mpg.de:5429102011-03-1161:916
The Higgs sector of the complex MSSM at two-loop order: QCD contributions
Heinemeyer, S.
Hollik, W.
Rzehak, H.
Weiglein, G.
notspecified
Phenomenology of High Energy Physics
Results are presented for the leading two-loop contributions of O(alpha_t alpha_s) to the masses and mixing effects in the Higgs sector of the MSSM with complex parameters. They are obtained in the Feynman-diagrammatic approach using on-shell renormalization. The full dependence on all complex phases is taken into account. The renormalization of the appropriate contributions of the Higgs-boson sector and the scalar top and bottom sector is discussed. Our numerical analysis for the lightest MSSM Higgs-boson mass is based on the new two-loop corrections, supplemented by the full one-loop result. The corrections induced by the phase variation in the scalar top sector are enhanced by the two-loop contributions. We find that the corresponding shift in M_h1 can amount to 5 GeV.
2007
Article
http://edoc.mpg.de/542910
Physics Letters B, 300-309 (2007)
oai:edoc.mpg.de:5429152011-03-1261:916
NLO corrections to WWZ and ZZZ production at the ILC
Boudjema, Fawzi
Ninh, Le Duc
Hao, Sun
Weber, Marcus M.
notspecified
Phenomenology of High Energy Physics
We calculate the full one-loop electroweak corrections to tri-boson production (ZZZ and WWZ) at the ILC. This is important to understand the Standard Model (SM) gauge quartic couplings which can be a window on the mechanism of spontaneous symmetry breaking. We find that even after subtracting the leading QED corrections, the electroweak corrections can still be large especially as the energy increases.
2010
Conference-Paper
http://edoc.mpg.de/542915
Poscpp, 2010, 014 (2010)
CPP2010, 014 (2010)
oai:edoc.mpg.de:5429192011-03-1161:916
A recursive formula for N-point SYM tree amplitudes
Mafra, Carlos R.
Schlotterer, Oliver
Stieberger, Stephan
Tsimpis, Dimitrios
notspecified
Theoretical Physics
We propose a recursive formula for super Yang-Mills color-ordered N-point tree amplitudes based on the cohomology of pure spinor superspace in ten space-time dimensions. The amplitudes are organized into BRST covariant building blocks with diagrammatic interpretation. Manifestly cyclic expressions (no longer than one line each) are explicitly given up to N = 10 and higher leg generalizations are straightforward.
Article
http://edoc.mpg.de/542919
oai:edoc.mpg.de:5429202011-03-1161:916
Electroweak corrections to $gamma Z$ production at hadron colliders
Hollik, Wolfgang
Meier, Christoph
notspecified
Phenomenology of High Energy Physics
In this paper we present the results from a calculation of the full electroweak one-loop corrections for $\gamma Z$ vector-boson pair production at hadron colliders. The cases of proton--antiproton as well as proton--proton collisions, at the Tevatron and the LHC, respectively, are considered. Results are presented for the distribution of the $\gamma Z$ invariant mass and for the transverse momentum of the final-state photon. The higher-order electroweak effects are numerically significant, in particular for probing possible anomalous gauge-boson couplings.
2004
Article
http://edoc.mpg.de/542920
Physics Letters B, 69-75 (2004)
oai:edoc.mpg.de:5429212011-03-1161:916
Large underground, liquid based detectors for astro-particle physics in Europe: scientific case and prospects
Aysto, J.
Badertscher, A.
Bezrukov, L.
Bouchez, J.
Bueno, A.
Busto, J.
Campagne, J. -E.
Cavata, Ch.
de Bellefon, A.
Dumarchez, J.
Ebert, J.
Enqvist, T.
Ereditato, A.
von Feilitzsch, F.
Fileviez Perez, P.
Goger-Neff, M.
Gninenko, S.
Gruber, W.
Hagner, C.
Hess, M.
Hochmuth, K. A.
Kisiel, J.
Knecht, L.
Kreslo, I.
Kudryavtsev, V. A.
Kuusiniemi, P.
Lachenmaier, T.
Laffranchi, M.
Lefievre, B.
Lightfoot, P. K.
Lindner, M.
Maalampi, J.
Maltoni, M.
Marchionni, A.
Marrodan Undagoitia, T.
Meregaglia, A.
Messina, M.
Mezzetto, M.
Mirizzi, A.
Mosca, L.
Moser, U.
Muller, A.
Natterer, G.
Oberauer, L.
Otiougova, P.
Patzak, T.
Peltoniemi, J.
Potzel, W.
Pistillo, C.
Raffelt, G. G.
Rondio, E.
Roos, M.
Rossi, B.
Rubbia, A.
Savvinov, N.
Schwetz, T.
Sobczyk, J.
Spooner, N. J. C.
Stefan, D.
Tonazzo, A.
Trzaska, W.
Ulbricht, J.
Volpe, C.
Winter, J.
Wurm, M.
Zalewska, A.
Zimmermann, R.
notspecified
Astroparticle Physics
This document reports on a series of experimental and theoretical studies conducted to assess the astro-particle physics potential of three future large-scale particle detectors proposed in Europe as next generation underground observatories. The proposed apparatus employ three different and, to some extent, complementary detection techniques: GLACIER (liquid Argon TPC), LENA (liquid scintillator) and MEMPHYS (\WC), based on the use of large mass of liquids as active detection media. The results of these studies are presented along with a critical discussion of the performance attainable by the three proposed approaches coupled to existing or planned underground laboratories, in relation to open and outstanding physics issues such as the search for matter instability, the detection of astrophysical- and geo-neutrinos and to the possible use of these detectors in future high-intensity neutrino beams.
2007
Article
http://edoc.mpg.de/542921
Journal of Cosmology and Astroparticle Physics, 011 (2007)
oai:edoc.mpg.de:5429222011-03-1161:916
Electroweak Absorptive Parts in NRQCD Matching Conditions
Hoang, A. H.
Reisser, C. J.
notspecified
Phenomenology of High Energy Physics
Electroweak corrections associated to the instability of the top quark to the next-to-next-to-leading logarithmic (NNLL) total top pair threshold cross section in e+e- annihilation are determined. Our method is based on absorptive parts in electroweak matching conditions of the NRQCD operators and the optical theorem. The corrections lead to ultraviolet phase space divergences that have to be renormalized and lead to NLL mixing effects. Numerically, the corrections can amount to several percent and are comparable to the known NNLL QCD corrections.
2005
Article
http://edoc.mpg.de/542922
Physical Review D, 074022 (2005)
oai:edoc.mpg.de:5429252011-03-1161:916
Continuum Limit of B_K from 2+1 Flavor Domain Wall QCD
Aoki, Y.
Arthur, R.
Blum, T.
Boyle, P. A.
Brömmel, D.
Christ, N. H.
Dawson, C.
Izubuchi, T.
Jung, C.
Kelly, C.
Kenway, R. D.
Lightman, M.
Mawhinney, R. D.
Ohta, Shigemi
Sachrajda, C. T.
Scholz, E. E.
Soni, A.
Sturm, C.
Wennekers, J.
Zhou, R.
notspecified
Phenomenology of High Energy Physics
We determine the neutral kaon mixing matrix element $B_K$ in the continuum limit with 2+1 flavors of domain wall fermions, using the Iwasaki gauge action at two different lattice spacings. These lattice fermions have near exact chiral symmetry and therefore avoid artificial lattice operator mixing. We introduce a significant improvement to the conventional NPR method in which the bare matrix elements are renormalized non-perturbatively in the RI-MOM scheme and are then converted into the MSbar scheme using continuum perturbation theory. In addition to RI-MOM, we introduce and implement four non-exceptional intermediate momentum schemes that suppress infrared non-perturbative uncertainties in the renormalization procedure. We compute the conversion factors relating the matrix elements in this family of RI-SMOM schemes and MSbar at one-loop order. Comparison of the results obtained using these different intermediate schemes allows for a more reliable estimate of the unknown higher-order contributions and hence for a correspondingly more robust estimate of the systematic error. We also apply a recently proposed approach in which twisted boundary conditions are used to control the Symanzik expansion for off-shell vertex functions leading to a better control of the renormalization in the continuum limit. We control chiral extrapolation errors by considering both the NLO SU(2) chiral effective theory, and an analytic mass expansion. We obtain $B_K^{\msbar}(3 GeV) = 0.529(5)_{stat}(15)_\chi(2)_{FV}(11)_{NPR}$. This corresponds to $\hat{B}_K = 0.749(7)_{stat}(21)_\chi(3)_{FV}(15)_{NPR}$. Adding all sources of error in quadrature we obtain $\hat{B}_K = 0.749(27)_{combined}$, with an overall combined error of 3.6%.
Article
http://edoc.mpg.de/542925
oai:edoc.mpg.de:5429282011-03-1161:916
Generalised G_2-structures and type IIB superstrings
Jeschek, Claus
Witt, Frederik
notspecified
Field Theory
The recent mathematical literature introduces generalised geometries
which are defined by a reduction from the structure group $SO(d,d)$
of the vector bundle $T^d\oplus T^{d*}$ to a special subgroup. In
this article we show that compactification of IIB superstring vacua
on 7-manifolds with two covariantly constant spinors leads to a
generalised $G_2$-structure associated with a reduction from
$SO(7,7)$ to $G_2\times G_2$. We also consider compactifications on
6-manifolds where analogously we obtain a generalised
$SU(3)$-structure associated with $SU(3)\times SU(3)$, and show how
these relate to generalised $G_2$-structures.
2005
Article
http://edoc.mpg.de/542928
Journal of High Energy Physics, 053 (2005)
oai:edoc.mpg.de:5429332011-03-1161:916
Are cosmological neutrinos free-streaming?
Basboll, Anders
Bjaelde, Ole Eggers
Hannestad, Steen
Raffelt, Georg G.
notspecified
Astroparticle Physics
Precision data from cosmology suggest neutrinos stream freely and hence interact very weakly around the epoch of recombination. We study this issue in a simple framework where neutrinos recouple instantaneously and stop streaming freely at a redshift z_i. The latest cosmological data imply z_i < 1500, the exact constraint depending somewhat on the assumed prior on z_i. This bound translates into a limit on the coupling strength between neutrinos and majoron-like particles phi, implying tau > 1 x 10^10 s (m_2/50 meV)^3 for the decay nu_2 -> nu_1+phi.
2009
Article
http://edoc.mpg.de/542933
Physical Review D, 043512 (2009)
oai:edoc.mpg.de:5429352011-03-1161:916
Electroweak contributions to squark--gluino production at the LHC
Hollik, Wolfgang
Mirabella, Edoardo
Trenkel, Maike K.
notspecified
Phenomenology of High Energy Physics
We calculated the electroweak contributions to the hadronic production of a squark in association with a gluino within the Minimal Supersymmetric Standard Model (MSSM). Presented are complete next-to-leading order electroweak (NLO EW) corrections at O(alpha_s^2 alpha), which include real photon and real quark radiation processes. Also considered are photon induced tree level O(alpha_s alpha) contributions.
2009
Article
http://edoc.mpg.de/542935
Journal of High Energy Physics, 002 (2009)
oai:edoc.mpg.de:5429372011-03-1261:916
Observations of 54 Active Galactic Nuclei with the HEGRA System of Cherenkov Telescopes
The HEGRA Collaboration
Aharonian, F.
Akhperjanian, A.
Beilicke, M.
notspecified
HEGRA
A sample of 54 selected Active Galactic Nuclei (AGN) has been observed with the HEGRA stereoscopic system of Cherenkov Telescopes between 1996 and 2002 in the TeV energy regime. The observations were motivated by the positive results obtained for Mkn 421 and Mkn 501. The distances of the selected objects vary over a large range of redshifts between z = 0.004 and z = 0.7. Among the observed AGN are the meanwhile established TeV-emitting BL Lac type objects H1426+428 and 1ES1959+650. Furthermore the BL Lac object 1ES2344+514 and the radio galaxy M87 show evidence for a signal on a 4 sigma level. The observation of 1ES2344+514 together with the Whipple results firmly establishes this AGN as a TeV source. Several objects (PKS2155-304, BL Lacertae, 3C066A) that have been claimed as TeV gamma-ray emitters by other groups are included in this data sample but could not be confirmed using data analysed here. The upper limits of several AGN included in this analysis are compared with predictions in the frame-work of SSC models.
2004
Article
http://edoc.mpg.de/542937
Astronomy &Amp; Astrophysics, 529-537 (2004)
oai:edoc.mpg.de:5429382011-03-1161:916
Observational bounds on the cosmic radiation density
Hamann, Jan
Hannestad, Steen
Raffelt, Georg G.
Wong, Yvonne Y. Y.
notspecified
Astroparticle Physics
We consider the inference of the cosmic radiation density, traditionally parameterised as the effective number of neutrino species N_eff, from precision cosmological data. Paying particular attention to systematic effects, notably scale-dependent biasing in the galaxy power spectrum, we find no evidence for a significant deviation of N_eff from the standard value of N_eff^0=3.046 in any combination of cosmological data sets, in contrast to some recent conclusions of other authors. The combination of all available data in the linear regime prefers, in the context of a ``vanilla+N_eff'' cosmological model, 1.1<N_eff<4.8 (95% C.L.) with a best-fit value of 2.6. Adding data at smaller scales, notably the Lyman-alpha forest, we find 2.2<N_eff<5.8 (95% C.L.) with 3.8 as the best fit. Inclusion of the Lyman-alpha data shifts the preferred N_eff upwards because the sigma_8 value derived from the SDSS Lyman-alpha data is inconsistent with that inferred from CMB. In an extended cosmological model that includes a nonzero mass for N_eff neutrino flavours, a running scalar spectral index and a w parameter for the dark energy, we find 0.8<N_eff<6.1 (95% C.L.) with 3.0 as the best fit.
2007
Article
http://edoc.mpg.de/542938
Journal of Cosmology and Astroparticle Physics, 021 (2007)
oai:edoc.mpg.de:5429422011-03-1161:916
Squark anti-squark pair production at the LHC: the electroweak contribution
Hollik, Wolfgang
Mirabella, Edoardo
notspecified
Phenomenology of High Energy Physics
We present the complete NLO electroweak contribution of $\mathcal{O}(\alpha^2_s \alpha)$ to the production of diagonal squark--anti-squark pairs in proton--proton collisions. Compared to the lowest-order $\mathcal{O}(\alpha_s\alpha + \alpha^2)$ electroweak terms, the NLO contributions are also significant. We discuss the LO and NLO electroweak effects in cross sections and distributions at the LHC for the production of squarks different from top squarks, in various supersymmetric benchmark scenarios.
2008
Article
http://edoc.mpg.de/542942
Journal of High Energy Physics, 087 (2008)
oai:edoc.mpg.de:5429442011-03-1161:916
Expansion around half-integer values, binomial sums and inverse binomial sums
Weinzierl, Stefan
notspecified
Phenomenology of High Energy Physics
I consider the expansion of transcendental functions in a small parameter around rational numbers. This includes in particular the expansion around half-integer values. I present algorithms which are suitable for an implementation within a symbolic computer algebra system. The method is an extension of the technique of nested sums. The algorithms allow in addition the evaluation of binomial sums, inverse binomial sums and generalizations thereof.
2004
Article
http://edoc.mpg.de/542944
Journal of Mathematical Physics, 2656-2673 (2004)
oai:edoc.mpg.de:5429462011-03-1161:916
Perturbative analysis of the gradient flow in non-abelian gauge theories
Lüscher, Martin
Weisz, Peter
notspecified
Field Theory
The gradient flow in non-abelian gauge theories on R^4 is defined by a local diffusion equation that evolves the gauge field as a function of the flow time in a gauge-covariant manner. Similarly to the case of the Langevin equation, the correlation functions of the time-dependent field can be expanded in perturbation theory, the Feynman rules being those of a renormalizable field theory on R^4 x [0,oo). For any matter multiplet and to all loop orders, we show that the correlation functions are finite, i.e.~do not require additional renormalization, once the theory in four dimensions is renormalized in the usual way. The flow thus maps the gauge field to a one-parameter family of smooth renormalized fields.
Article
http://edoc.mpg.de/542946
oai:edoc.mpg.de:5429472011-03-1161:916
Physical renormalization condition for the quark-mixing matrix
Denner, A.
Kraus, E.
Roth, M.
notspecified
Phenomenology of High Energy Physics
We investigate the renormalization of the quark-mixing matrix in the Electroweak Standard Model. We show that the corresponding counterterms must be gauge independent as a consequence of extended BRS invariance. Using rigid SU(2)_L symmetry, we proof that the ultraviolet-divergent parts of the invariant counterterms are related to the field renormalization constants of the quark fields. We point out that for a general class of renormalization schemes rigid SU(2)_L symmetry cannot be preserved in its classical form, but is renormalized by finite counterterms. Finally, we discuss a genuine physical renormalization condition for the quark-mixing matrix that is gauge independent and does not destroy the symmetry between quark generations.
2004
Article
http://edoc.mpg.de/542947
Physical Review D, 033002 (2004)
oai:edoc.mpg.de:5429492011-03-1161:916
Anatomy of Prominent B and K Decays and Signatures of CP-Violating New Physics in the Electroweak Penguin Sector
Buras, Andrzej J.
Fleischer, Robert
Recksiegel, Stefan
Schwab, Felix
notspecified
Phenomenology of High Energy Physics
The recent observation of B_d -> pi^0 pi^0 at the B factories with a surprisingly large branching ratio represents a challenge for theory, and complements the amazingly small B_d -> pi^+ pi^- rate. We point out that all puzzling B -> pi pi features can be accommodated in the Standard Model (SM) through non-factorizable hadronic interference effects, extract the relevant parameters, and predict the CP asymmetries of B_d -> pi^0 pi^0. Using then SU(3) flavour-symmetry and plausible dynamical assumptions, we fix the hadronic B -> pi K parameters through their B -> pi pi counterparts, and determine the CKM angle gamma, with a result in remarkable accordance with the usual fits for the unitarity triangle. We may then analyse the B -> pi K system in the SM, where we find agreement with the experimental picture, with the exception of those observables that are significantly affected by electroweak (EW) penguins, thereby suggesting new physics (NP) in this sector. Indeed, a moderate enhancement of these topologies and a large CP-violating NP phase allow us to describe any currently observed feature of the B -> pi K modes, and to predict the CP-violating B_d -> pi^0 K_S observables. If we then restrict ourselves to a specific scenario where NP enters only through Z^0 penguins, we obtain a link to rare K and B decays, where the most spectacular NP effects are an enhancement of the K_L -> pi^0 nu nu_bar rate by one order of magnitude with BR(K_L -> pi^0 nu nu_bar) ~ 4 BR(K^+ -> pi^+ nu nu_bar), BR(K_L -> pi^0 e^+ e^-) = O(10^-10), (sin 2beta)_{pi nu nu_bar} < 0, and a large forward-backward CP asymmetry in B_d -> K^* mu^+ mu^-. We address also epsilon'/epsilon and other prominent decays, including B -> phi K and B -> J/psi K modes.
2004
Article
http://edoc.mpg.de/542949
Nuclear Physics B, 133-206 (2004)
oai:edoc.mpg.de:5429532011-03-1161:916
Scattering of Gauge, Matter, and Moduli Fields from Intersecting Branes
Lust, D.
Mayr, P.
Richter, R.
Stieberger, S.
notspecified
Theoretical Physics
We calculate various tree-level (disk) scattering amplitudes involving gauge, matter and moduli fields in type IIB toroidal orbifold/orientifold backgrounds with D9,D5 respectively D7,D3-branes or via T-duality D6-branes in type IIA compactifications. In type IIB the D-branes may have non-vanishing fluxes on their world-volume. From these results we extract the moduli and flux dependence of the tree-level gauge couplings, the metrics for the moduli and matter fields. The non-vanishing fluxes correspond in the T-dual type IIA description to intersecting D6-branes. This allows us to determine the moduli dependence of the tree-level matter field metrics in the effective action of intersecting D6-brane models. In addition we derive the physical Yukawa couplings with their correct normalization.
2004
Article
http://edoc.mpg.de/542953
Nuclear Physics B, 205-250 (2004)
oai:edoc.mpg.de:5429542011-03-1161:916
Feasibility study of the observation of the neutrino accompanied double beta-decay of Ge-76 to the 0+(1) excited state of Se-76 using segmented germanium detectors
Kröninger, K.
Pandola, L.
Tretyak, V.
notspecified
GERDA
Neutrino accompanied double beta-decay of Ge-76 can populate the ground state and the excited states of Se-76. While the decay to the ground state has been observed with a half-life of 1.74 +0.18 -0.16 10^21 years, decays to the excited states have not yet been observed. Nuclear matrix elements depend on details of the nuclear transitions. A measurement of the half-life of the transition considered here could help to reduce the uncertainties of the calculations of the nuclear matrix element for the neutrinoless double beta decay of Ge-76. This parameter relates the half-life of the process to the effective Majorana neutrino mass. The results of a feasibility study to detect the neutrino accompanied double beta-decay of Ge-76 to the excited states of Se-76 are presented in this paper. Segmented germanium detectors were assumed in this study. Such detectors, enriched in Ge-76 to a level of about 86%, will be deployed in the GERDA experiment located at the INFN Gran Sasso National Laboratory, Italy. It is shown that the decay of Ge-76 to the 1122 keV 0+ level of Se-76 can be observed in GERDA provided that the half-life of the process is in the range favoured by the present calculations which is 7.5 10^21 y to 3.1 10^23 y.
2007
Article
http://edoc.mpg.de/542954
Ukrainian Journal of Physics, 1036-1044 (2007)
oai:edoc.mpg.de:5429562011-03-1161:916
Gluonic Meson Production
Minkowski, Peter
Ochs, Wolfgang
notspecified
Phenomenology of High Energy Physics
The existence of glueballs is predicted in QCD, the lightest one with quantum numbers J^{PC}=0^{++}, but different calculations do not well agree on its mass in the range below 1800 MeV. Several theoretical schemes have been proposed to cope with the experimental data which often have considerable uncertainties. Further experimental studies of the scalar meson sector are therefore important and we discuss recent proposals to study leading clusters in gluon jets and charmless B-decays to serve this purpose.
World Scientific
2004
Conference-Paper
http://edoc.mpg.de/542956
G. Grindhammer, B.A. Kniehl, G. Kramer, W. Ochs: New Trends in HERA Physics 2003, World Scientific, 169-182 (2004)
oai:edoc.mpg.de:5429572011-03-1161:916
Measurement of the inclusive D*+- production in gamma-gamma collisions at LEP
ALEPH Collaboration
Heister, Arno
et al.
notspecified
ALEPH
The inclusive production of D$^{*\pm}$ mesons in two-photon collisions is measured with the ALEPH detector at $\epem$ centre-of-mass energies from 183$\unit{GeV}$ to 209$\unit{GeV}$. A total of $360 \pm 27$ D$^{*\pm}$ meson events were observed from an integrated luminosity of 699\unit{pb^{-1}}$. Contributions from direct and single-resolved rocesses are separated using the ratio of the transverse momentum $p_{\rm t}^{\rm D^{*\pm}}$ of the D$^{*\pm}$ to the visible invariant mass $W_{\mathrm{vis}}$ of the event. Differential cross sections of D$^{*\pm}$ production as functions of $p_{\rm t}^{\rm D^{*\pm}}$ and the pseudorapidity $|\eta^{\rm D^{*\pm}}| $ are measured in the range $ 2\unit{GeV}/c < p_{\rm t}^{\rm D^{*\pm}} < 12\unit{GeV}/c $ and $ |\eta^{\rm D^{*\pm}}| < 1.5 $. They are compared to next-to-leading order (NLO)perturbative QCD calculations. The extrapolation of the integrated visible D$^{*\pm}$ cross section to the total charm cross section, based on the Pythia Monte Carlo program, yields $ \sigma (\epem \to \epem \ccbar)_ {=197\unit{GeV}} = 731 \pm 74_{\mathrm{stat}} \pm 47_{\mathrm{syst}} \pm 157_{\mathrm{extr}} \unit{pb} $.
2003
Article
http://edoc.mpg.de/542957
European Physical Journal C, 437-449 (2003)
oai:edoc.mpg.de:5429582011-03-1161:916
MAGIC Observations of a 13-Day Flare Complex in M87 in Februrary 2008
Albert, J.
et al.
notspecified
MAGIC
M87 is the only known non-blazar radio galaxy to emit very high energy (VHE) gamma-rays. During a monitoring program of M87, a rapid flare in VHE gamma-rays was detected by the MAGIC telescope in early 2008. The flux was found to be variable above 350 GeV on a timescale as short as 1 day on a significance level of 5.6 sigma. The highest measured flux reached 15% of the Crab nebula flux. We observed a rather complex flare structure with several substantial changes of he flux level during the 13-day observing period. The flux at lower energies (150 GeV to 350 GeV), instead, is compatible with being constant. The energy spectrum can be described by a power law with a photon index of 2.30+- 0.11(stat)+-0.20(syst). The observed day-scale flux variability at VHE prefers the M87 core as source of the emission and implies that either the emission region is very compact (just few Schwarzschild radii) or the Doppler factor of the emitting blob is rather large in case of a non-expanding emission region.
2008
Article
http://edoc.mpg.de/542958
Astrophysical Journal Letters (2008)
oai:edoc.mpg.de:5429592011-03-1161:916
Pulse shapes from electron and photon induced events in segmented high-purity germanium detectors
Abt, I.
Caldwell, A.
Kröninger, K.
Liu, J.
Liu, X.
Majorovits, B.
notspecified
GERDA
Experiments built to search for neutrinoless double beta-decay are limited in their sensitivity not only by the exposure but also by the amount of background encountered. Radioactive isotopes in the surrounding of the detectors which emit gamma-radiation are expected to be a significant source of background in the GERmanium Detector Array, GERDA.
Methods to select electron induced events and discriminate against photon induced events inside a germanium detector are presented in this paper. The methods are based on the analysis of the time structure of the detector response. Data were taken with a segmented GERDA prototype detector. It is shown that the analysis of the time response of the detector can be used to distinguish multiply scattered photons from electrons.
2007
Article
http://edoc.mpg.de/542959
European Physical Journal C, 19-27 (2007)
oai:edoc.mpg.de:5429602011-03-1161:916
Triviality of $\phi^4_4$ theory: small volume expansion and new data
Weisz, P.
Wolff, U.
notspecified
Field Theory
We study a renormalized coupling g and mass m in four dimensional phi^4
theory on tori with finite size z=mL. Precise numerical values close to the
continuum limit are reported for z=1,2,4, based on Monte Carlo simulations
performed in the equivalent all-order strong coupling reformulation. Ordinary
renormalized perturbation theory is found to work marginally at z=2 and and to
fail at z=1. By exactly integrating over the constant field mode we set up a
renormalized expansion in z and compute three nontrivial orders. These results
reasonably agree with the numerical data at small z. In the new expansion, the
universal continuum limit exists as expected from multiplicative
renormalizability. The triviality scenario is corroborated with significant
precision.
Article
http://edoc.mpg.de/542960
oai:edoc.mpg.de:5429612011-03-1161:916
A measurement of the gluon splitting rate into ccbar pairs in hadronic Z decays
ALEPH Collaboration
Heister, Arno
et al.
notspecified
ALEPH
The rate of gluons splitting into $c \bar{c}$ pairs in hadronic $Z$ decays is measured using the data sample collected by ALEPH from 1991 to 1995. The selection is based on the identification of leptons (electrons and muons) originating from semileptonic charm decays, and on the topological properties of signal events. The result derived from the selected sample is $g_{c \bar{c}}=(3.26 \pm 0.23 \rm{(stat)} \pm 0.42 \rm{(syst)}) %$
2003
Article
http://edoc.mpg.de/542961
Physics Letters B, 213-224 (2003)
oai:edoc.mpg.de:5429632011-03-1161:916
Search for stable hadronizing squarks and gluinos in e+e- collisions up to sqrt(s) = 209 GeV
ALEPH Collaboration
Heister, Arno
et al.
notspecified
ALEPH
Searches for stable, hadronizing scalar quarks and gluinos are performed using the data collected with the ALEPH detector at LEP. Gluon splitting into a gluino or a squark pair is searched for at centre-of-mass energies around the Z resonance, in the e+e- -> q qbar gluino gluino and q qbar squark antisquark processes. Stable squark pair production, and stop pair production with subsequent decays into a stable gluino, stop -> c gluino, are also directly searched for at centre-of-mass energies from 183 to 209 GeV. Altogether, stable hadronizing stop (sbottom) quarks are excluded up to masses of 95 (92) GeV/c2, and stable hadronizing gluinos are excluded up to 26.9 GeV/c2, at 95% confidence level. In the framework of R-parity-conserving supersymmetric models in which the gluino and the stop quark are the two lightest supersymmetric particles, a 95% C.L. lower limit of 80 GeV/c2 is set on the stop quark mass.
2003
Article
http://edoc.mpg.de/542963
European Physical Journal C, 327-342 (2003)
oai:edoc.mpg.de:5429642011-03-1161:916
Mesons from global Anti-de Sitter space
Erdmenger, Johanna
Filev, Veselin
notspecified
Theoretical Physics
In the context of gauge/gravity duality, we study both probe D7-- and probe D5--branes in global Anti-de Sitter space. The dual field theory is N=4 theory on R x S^3 with added flavour. The branes undergo a geometrical phase transition in this geometry as function of the bare quark mass m_q in units of 1/R with R the S^3 radius. The meson spectra are obtained from fluctuations of the brane probes. First, we study them numerically for finite quark mass through the phase transition. Moreover, at zero quark mass we calculate the meson spectra analytically both in supergravity and in free field theory on R x S^3 and find that the results match: For the chiral primaries, the lowest level is given by the zero point energy or by the scaling dimension of the operator corresponding to the fluctuations, respectively. The higher levels are equidistant. Similar results apply to the descendents. Our results confirm the physical interpretation that the mesons cannot pair-produce any further when their zero-point energy exceeds their binding energy.
2011
Article
http://edoc.mpg.de/542964
Journal of High Energy Physics, 119 (2011)
oai:edoc.mpg.de:5429662011-03-1161:916
The soft-energy region in the radiative decay of bound states
Ruiz-Femenia, Pedro D.
notspecified
Phenomenology of High Energy Physics
The orthopositronium decay to three photons is studied in the phase-space region where one of the photons has an energy comparable to the relative three-momentum of the e+e- system (w~m alpha). The NRQED computation in this regime shows that the dominant contribution arises from distances ~ 1/(mw)^(1/2), which allows to treat the Coulomb interaction perturbatively. The small-photon energy expansion of the 1-loop decay spectrum from full QED yields the same result as the effective theory. By doing the threshold expansion of the 1-loop QED amplitude we confirm that the leading term arises from a loop-momentum region where q^0 ~ q^2/m ~ w. This corresponds to a new non-relativistic loop-momentum region, which has to be taken into account for the description of a non-relativistic particle-antiparticle system that decays through soft photon emission.
2008
Article
http://edoc.mpg.de/542966
Nuclear Physics B, 21-46 (2008)
oai:edoc.mpg.de:5429672011-03-1161:916
Study of hadronic final states from double tagged gammagamma events at LEP
ALEPH Collaboration
Heister, Arno
et al.
notspecified
ALEPH
The interaction of virtual photons is investigated using double tagged gammagamma events with hadronic final states recorded by the ALEPH experiment at e^+e^- centre-of-mass energies between 188 and 209 GeV. The measured cross section is compared to Monte Carlo models, and to next-to-leading-order QCD and BFKL calculations.
Article
http://edoc.mpg.de/542967
oai:edoc.mpg.de:5429682011-03-1161:916
Di-Jet Production in Photon-Photon colisions at sqrt(s)ee from 189 to 209 GeV
The OPAL collaboration
Abbiendi, G.
et al.
notspecified
OPAL
Di-jet producion is studied in collisions of quasi-real photons at e+e- centre- of-mass energies sqrt(s)ee from 189 to 209 GeV at LEP. The data were collected with the OPAL detector. Jets are reconstructed using an inclusive k_t clustering algorithm for all cross-section measurements presented. A cone jet algorithm is used in addition to study the different structure of the jets resulting from either of the algorithms. The inclusive di-jet cross-section is measured as a function of the mean transverse energy Etm(jet) of the two leading jets, and as a functiuon of the estimated fraction of the photon momentum carried by the parton entering the hard sub-process, xg, for different regions of Etm (jet). Angular distribution in di-jet events are measured and used to demonstrate the dominance of quark and gluon initiated processes in different regions of phase space. Furthermore the inclusive di-jet cross-section as a function of |eta(jet)| and |delta eta (jet)| is presented where eta(jet) is the jet pseudo-rapidity. Different regions of the xg+ -xg- -space are explored to study and control the influence of an underlying event. The results are compared to next-to-leading order perturbative QCD calculations and to the predictions of the leading order Monte Carlo generator PYTHIA.
2003
Article
http://edoc.mpg.de/542968
European Physical Journal C, 307-325 (2003)
oai:edoc.mpg.de:5429692011-03-1161:916
The Littlest Higgs Model with T-Parity Facing CP-Violation in B_s - anti-B_s Mixing
Blanke, Monika
Buras, Andrzej J.
Recksiegel, Stefan
Tarantino, Cecilia
notspecified
Phenomenology of High Energy Physics
The non-minimal flavour violating interactions of mirror quarks and new heavy gauge bosons in the Littlest Higgs model with T-parity (LHT) give rise to naturally large CP-violating effects in the B_s system. In view of a large new CP phase in B_s - anti-B_s mixing hinted by the CDF and D0 data and the recent UTfit analysis, we update our 2006 analysis of particle-antiparticle mixing and rare K and B decays in the LHT model, using the most recent values of a number of input parameters and performing a more careful error analysis. We find that the CP-asymmetry S_{psi phi} can easily reach values ~ 0.15-0.20, compared to the SM value ~ 0.04, while higher values are rather unlikely though not excluded. Large enhancements are also possible in the branching ratios for K_L -> pi0 nu anti-nu, K+ -> pi+ nu anti-nu and K_L -> pi0 l+ l- with much more modest effects in B_{s,d} -> mu+ mu-. We perform a detailed study of correlations between the latter decays and S_{psi phi} as well as of the correlation between S_{psi phi} and S_{psi K_S}. We also point out that the possible tension between epsilon_K and the tree level CKM determination recently hinted by various analyses can easily be resolved in the LHT model.
Article
http://edoc.mpg.de/542969
oai:edoc.mpg.de:5429702011-03-1161:916
Low-energy couplings of QCD from current correlators near the chiral limit
Giusti, L.
Hernandez, P.
Laine, M.
Weisz, P.
Wittig, H.
notspecified
Field Theory
We investigate a new numerical procedure to compute fermionic correlation functions at very small quark masses. Large statistical fluctuations, due to the presence of local ``bumps'' in the wave functions associated with the low-lying eigenmodes of the Dirac operator, are reduced by an exact low-mode averaging. To demonstrate the feasibility of the technique, we compute the two-point correlator of the left-handed vector current with Neuberger fermions in the quenched approximation, for lattices with a linear extent of L~1.5 fm, a lattice spacing a~0.09 fm, and quark masses down to the epsilon-regime. By matching the results with the corresponding (quenched) chiral perturbation theory expressions, an estimate of (quenched) low-energy constants can be obtained. We find agreement between the quenched values of F extrapolated from the p-regime and extracted in the epsilon-regime.
2004
Article
http://edoc.mpg.de/542970
Journal of High Energy Physics, 013 (2004)
oai:edoc.mpg.de:5429712011-03-1161:916
An Improved limit on the axion-photon coupling from the CAST experiment
Andriamonje, S.
Aune, S.
Autiero, D.
Barth, K.
Belov, A.
Beltran, B.
Brauninger, H.
Carmona, J. M.
Cebrian, S.
Collar, J. I.
Dafni, T.
Davenport, M.
Di Lella, L.
Eleftheriadis, C.
Englhauser, J.
Fanourakis, G.
Ferrer Ribas, E.
Fischer, H.
Franz, J.
Friedrich, P.
Geralis, T.
Giomataris, I.
Gninenko, S.
Gomez, H.
Hasinoff, M.
Heinsius, F. H.
Hoffmann, D. H. H.
Irastorza, I. G.
Jacoby, J.
Jakovcic, K.
Kang, D.
Konigsmann, K.
Kotthaus, R.
Krcmar, M.
Kousouris, K.
Kuster, M.
Lakic, B.
Lasseur, C.
Liolios, A.
Ljubicic, A.
Lutz, G.
Luzon, G.
Miller, D.
Morales, A.
Morales, J.
Ortiz, A.
Papaevangelou, T.
Placci, A.
Raffelt, G.
Riege, H.
Rodrguez, A.
Ruz, J.
Savvidis, I.
Semertzidis, Y.
Serpico, P.
Stewart, L.
Vieira, J.
Villar, J.
Vogel, J.
Walckiers, L.
Zioutas, K.
notspecified
CAST
We have searched for solar axions or similar particles that couple to two photons by using the CERN Axion Solar Telescope (CAST) setup with improved conditions in all detectors. From the absence of excess X-rays when the magnet was pointing to the Sun, we set an upper limit on the axion-photon coupling of 8.8 x 10^{-11} GeV^{-1} at 95% CL for m_a <~ 0.02 eV. This result is the best experimental limit over a broad range of axion masses and for m_a <~ 0.02 eV also supersedes the previous limit derived from energy-loss arguments on globular-cluster stars.
2007
Article
http://edoc.mpg.de/542971
Journal of Cosmology and Astroparticle Physics, 010 (2007)
oai:edoc.mpg.de:5429742011-03-1161:916
Bose-Einstein Correlations of pi0 Pairs from Hadronic Z0 Decays
The OPAL collaboration
Abbiendi, G.
et al.
notspecified
OPAL
We observed Bose-Einstein correlation in pi0 pairs produced in Z0 decays using the data sample collected by the OPAL detector at LEP 1 from 1991 to 1995. Using a static Gaussian picture for the pion emitter source, we obtain the chaoticity parameter lambda = 0.55 +- 0.10 +- 0.10 and the source radius R = (0.59 +- 0.08 +- 0.05) fm. according to the JETSET and HERWIG Monte Carlo models, the Bose-Einstein correlations in our data sample largely connect pi0s originating from the decays of different hadrons. Prompt pions formed at string break-up of cluster decays only form a small fraction of the sample.
2003
Article
http://edoc.mpg.de/542974
Physics Letters B, 131-143 (2003)
oai:edoc.mpg.de:5429752011-03-1161:916
Collective neutrino oscillations in non-spherical geometry
Dasgupta, B.
Dighe, A.
Mirizzi, A.
Raffelt, G. G.
notspecified
Astroparticle Physics
The rich phenomenology of collective neutrino oscillations has been studied only in one-dimensional or spherically symmetric systems. Motivated by the non-spherical example of coalescing neutron stars, presumably the central engines of short gamma-ray bursts, we use the Liouville equation to formulate the problem for general source geometries. Assuming the neutrino ensemble displays self-maintained coherence, the problem once more becomes effectively one-dimensional along the streamlines of the overall neutrino flux. This approach for the first time provides a formal definition of the ``single-angle approximation'' frequently used for supernova neutrinos and allows for a natural generalization to non-spherical geometries. We study the explicit example of a disk-shaped source as a proxy for coalescing neutron stars.
2008
Article
http://edoc.mpg.de/542975
Physical Review D, 033014 (2008)
oai:edoc.mpg.de:5429782011-03-1161:916
Signatures of axion-like particles in the spectra of TeV gamma-ray sources
Mirizzi, Alessandro
Raffelt, Georg G.
Serpico, Pasquale D.
notspecified
Astroparticle Physics
One interpretation of the unexplained signature observed in the PVLAS experiment invokes a new axion-like particle (ALP) with a two-photon vertex, allowing for photon-ALP oscillations in the presence of magnetic fields. In the range of masses and couplings suggested by PVLAS, the same effect would lead to a peculiar dimming of high-energy photon sources. For typical parameters of the turbulent magnetic field in the galaxy, the effect sets in at E_gamma >~ 10 TeV, providing an ALP signature in the spectra of TeV gamma sources that can be probed with Cherenkov telescopes. A dedicated search will be strongly motivated if the ongoing photon regeneration experiments confirm the PVLAS particle interpretation.
2007
Article
http://edoc.mpg.de/542978
Physical Review D, 023001 (2007)
oai:edoc.mpg.de:5429802011-03-1161:916
Five-Brane Superpotentials, Blow-Up Geometries and SU(3) Structure Manifolds
Grimm, Thomas W.
Klemm, Albrecht
Klevers, Denis
notspecified
Theoretical Physics
We investigate the dynamics of space-time filling five-branes wrapped on curves in heterotic and orientifold Calabi-Yau compactifications. We first study the leading N=1 scalar potential on the infinite deformation space of the brane-curve around a supersymmetric configuration. The higher order potential is also determined by a brane superpotential which we compute for a subset of light deformations. We argue that these deformations map to new complex structure deformations of a non-Calabi-Yau manifold which is obtained by blowing up the brane-curve into a four-cycle and by replacing the brane by background fluxes. This translates the original brane-bulk system into a unifying geometrical formulation. Using this blow-up geometry we compute the complete set of open-closed Picard-Fuchs differential equations and identify the brane superpotential at special points in the field space for five-branes in toric Calabi-Yau hypersurfaces. This has an interpretation in open mirror symmetry and enables us to list compact disk instanton invariants. As a first step towards promoting the blow-up geometry to a supersymmetric heterotic background we propose a non-Kaehler SU(3) structure and an identification of the three-form flux.
Article
http://edoc.mpg.de/542980
oai:edoc.mpg.de:5429812011-03-1161:916
Universal properties of particle production in the soft limit p_T -> 0
Ochs, Wolfgang
Khoze, Valery A.
Ryskin, M. G.
notspecified
Phenomenology of High Energy Physics
The momentum spectra of particles in different high energy processes, such as e^+e^- annihilation, pp and nuclear collisions in the limit p,p_T -> 0 exhibit similar properties because of the dominant role of coherent soft gluon bremsstrahlung. We observe the following general features: the inclusive particle density approaches a limiting behaviour and becomes independent of primary collision energy; furthermore, it becomes proportional to the QCD colour factors C_A,C_F which appear in the Born term for the respective minimal partonic processes. In this limit, nuclear collisions reach with good accuracy participant (``wounded nucleon'') scaling. Particle ratios in the low momentum region display a universal behaviour. Future measurements at the LHC will provide crucial tests for the contributions from additional incoherent multi-component processes.
Conference-Paper
http://edoc.mpg.de/542981
oai:edoc.mpg.de:5429822011-03-1161:916
Non-universal shear viscosity from Einstein gravity
Erdmenger, Johanna
Kerner, Patrick
Zeller, Hansjörg
notspecified
Theoretical Physics
A very famous result of gauge/gravity duality is the universality of the ratio of shear viscosity to entropy density in every field theory holographically dual to classical, two-derivative (Einstein) gravity. We present a way to obtain deviation form this universality by breaking the rotational symmetry spontaneously. In anisotropic fluids additional shear modes exist and their corresponding shear viscosities may be non-universal. We confirm this by explicitly calculating the shear viscosities in a transversely isotropic background, a p-wave superfluid, and study its critical behavior. This is a first decisive step towards further applications of gauge/gravity duality to physical systems.
Article
http://edoc.mpg.de/542982
oai:edoc.mpg.de:5429842011-03-1161:916
Correlations between epsilon'/epsilon and Rare K Decays in the Littlest Higgs Model with T-Parity
Blanke, Monika
Buras, Andrzej J.
Recksiegel, Stefan
Tarantino, Cecilia
Uhlig, Selma
notspecified
Phenomenology of High Energy Physics
We calculate the CP-violating ratio epsilon'/epsilon in the Littlest Higgs model with T-parity (LHT) and investigate its correlations with the branching ratios for K_L -> pi^0 nu {bar nu}, K_L -> pi^0 l^+ l^- and K^+ -> pi^+ nu {bar nu}. The resulting correlations are rather strong in the case of K_L decays, but less pronounced in the case of K^+ -> pi^+ nu {bar nu}. Unfortunately, they are subject to large hadronic uncertainties present in epsilon'/epsilon, whose theoretical prediction in the Standard Model is reviewed and updated here. With the matrix elements of Q_6 (gluon penguin) and Q_8 (electroweak penguin) evaluated in the large-N limit and m_s^MS(2 GeV) = 100 MeV from lattice QCD, (epsilon'/epsilon)_SM turns out to be close to the data so that significant departures of Br(K_L -> pi^0 nu {bar nu}) and Br(K_L -> pi^0 l^+ l^-) from the SM expectations are unlikely, while Br(K^+ -> pi^+ nu {bar nu}) can be enhanced even by a factor 5. On the other hand, modest departures of the relevant hadronic matrix elements from their large-N values allow for a consistent description of epsilon'/epsilon within the LHT model accompanied by large enhancements of Br(K_L -> pi^0 nu {bar nu}) and Br(K_L -> pi^0 l^+ l^-), but only modest enhancements of Br(K^+ -> pi^+ nu {bar nu}).
2007
Article
http://edoc.mpg.de/542984
Journal of High Energy Physics, 082 (2007)
oai:edoc.mpg.de:5429852011-03-1161:916
Status of particle physics solutions to the UHECR puzzle
Kachelriess, M.
notspecified
Astroparticle Physics
The status of solutions to the ultra-high energy cosmic ray puzzle that involve particle physics beyond the standard model is reviewed. Signatures and experimental constraints are discussed for most proposals like the Z burst model and topological defects (both allowed only as subdominant contribution), supermassive dark matter (no positive evidence from its key signatures galactic anisotropy and photon dominance), strongly interacting neutrinos or new primaries (no viable models known), and violation of Lorentz invariance (possible).
2004
Article
http://edoc.mpg.de/542985
Comptes Rendus Physique, 441-452 (2004)
oai:edoc.mpg.de:5429872011-03-1161:916
Direct Coupling of SiPMs to Scintillator Tiles for Imaging Calorimetry and Triggering
Simon, Frank
Soldner, Christian
Joram, Christian
notspecified
ILC
The recent availability of blue sensitive silicon photomultipliers allows the direct readout of blue emitting plastic scintillator tiles without the use of a wavelength shifting fiber. Such directly read out tiles, without light guides, are attractive for the use in highly granular calorimeters that use large numbers of individual cells and in other applications where very compact designs are needed. However, the total signal amplitude and the uniformity of the response can be problematic in such cases. We have developed a scanning setup to investigate the response of scintillator tiles with SiPM readout in detail. It was used to develop optimized scintillator tile geometries for highly granular hadronic calorimetry at future colliders and to investigate the feasibility of a SiPM readout for the trigger of the ATLAS ALFA luminosity detectors. We report on results obtained with specialized scintillator tile geometries, discuss first results obtained with directly coupled SiPM readout of the ATLAS ALFA trigger tiles and introduce the application of fiberless readout in an experiment to study the time structure of hadronic showers.
2010
Conference-Paper
http://edoc.mpg.de/542987
IEEE Nuclear Science Symposium 2010 (2010)
oai:edoc.mpg.de:5429882011-03-1161:916
Isospin diffusion in thermal AdS/CFT with flavor
Erdmenger, Johanna
Kaminski, Matthias
Rust, Felix
notspecified
Theoretical Physics
We study the gauge/gravity dual of a finite temperature field theory at finite isospin chemical potential by considering a probe of two coincident D7-branes embedded in the AdS-Schwarzschild black hole background. The isospin chemical potential is obtained by giving a vev to the time component of the non-Abelian gauge field on the brane. The fluctuations of the non-Abelian gauge field on the brane are dual to the SU(2) flavor current in the field theory. For the embedding corresponding to vanishing quark mass, we calculate all Green functions corresponding to the components of the flavor current correlator. We discuss the physical properties of these Green functions, which go beyond linear response theory. In particular, we show that the isospin chemical potential leads to a frequency-dependent isospin diffusion coefficient.
2007
Article
http://edoc.mpg.de/542988
Physical Review D, 046001 (2007)
ResultSet_9ziPzmkP180_range_100-199