2020-10-28T11:12:33Zhttp://edoc.mpg.de/ac_p_oai.ploai:edoc.mpg.de:269202003-08-0737:452
Statistical Theory of Nuclear Reactions
Weidenmüller, H. A.
expertsonly
Academic Press
2002
InBook
http://edoc.mpg.de/26920
Scattering: scattering and inverse scattering in pure and applied science, 1393-1413 (2002)
en
oai:edoc.mpg.de:269282003-08-0737:452
Unordnung und Chaos in Quantensystemen
Weidenmüller, H. A.
expertsonly
Soc.
2002
InBook
http://edoc.mpg.de/26928
Deutschen Akademie der Naturforscher Leopoldina (Halle/Saale): Jahrbuch 2001 der Deutschen Akademie der Naturforscher Leopoldina (Halle/Saale), 343-355 (2002)
de
oai:edoc.mpg.de:269332003-07-3037:452
Georg Christoph Lichtenberg
Brix, Peter
popular
Margot-und-Friedrich-Becke-Stiftung
2002
InBook
http://edoc.mpg.de/26933
Zimmermann, Hans-Joachim, Brix, Peter: Die Vermehrung des Wissens und die Ausbreitung der Dummheit: zwei Vorträge gehalten im Rahmen der Margot-und-Friedrich-Becke-Stiftung am 5. Mai 2001 in Heidelberg ..., 51-66 (2002)
de
oai:edoc.mpg.de:277102003-08-0737:452
Spreading widths for superdeformed states in Hg-194 and Pb-194
Krucken, R.
Dewald, A.
von Brentano, P.
Weidenmüller, H. A.
expertsonly
Using several theoretical models, we have obtained estimates for the spreading widths Gamma (!) for the decay out of a superdeformed (SD) band. We pay particular attention to the statistical model by Gu and Weidenmuller. Our results for Hg- 194 and Pb-194 are compared to other theoretical predictions and to experimental upperbounds for Gamma (!). We find that the models of Gu and Weidenmuller and of Vigezzi et al. yield a consistent description of the data. We relate Gamma (!) to the strength v of the interaction that couples the normally deformed levels to the SD level at which the decay out of the SD band occurs. Using an exponential spin dependence of v, we are able to reproduce the intraband intensities in the SD bands in Hg-194 and Pb-194.
2001
Article
http://edoc.mpg.de/27710
urn:ISSN:0556-2813
Physical Review C, v.6406, 064316-064316 (2001)
en
oai:edoc.mpg.de:277142009-09-0337:452
Partition functions in statistical mechanics, symmetric functions, and group representations
Balantekin, A. B.
expertsonly
Partition functions for noninteracting particles are known to be symmetric functions. It is shown that powerful group- theoretical techniques can be used not only to derive these relationships, but also to significantly simplify calculation of the partition functions for particles that carry internal quantum numbers. The partition function is shown to be a sum of one or more group characters. The utility of character expansions in calculating the partition functions is explored. Several examples are given to illustrate these techniques.
2001
Article
http://edoc.mpg.de/27714
Physical Review E, v.6406 (2001)
en
oai:edoc.mpg.de:277232003-08-0737:452
Spreading widths for superdeformed states in Hg-194 and Pb-194
Krucken, R.
Dewald, A.
von Brentano, P.
Weidenmüller, H. A.
expertsonly
Using several theoretical models, we have obtained estimates for the spreading widths Gamma (!) for the decay out of a superdeformed (SD) band. We pay particular attention to the statistical model by Gu and Weidenmuller. Our results for Hg- 194 and Pb-194 are compared to other theoretical predictions and to experimental upperbounds for Gamma (!). We find that the models of Gu and Weidenmuller and of Vigezzi et al. yield a consistent description of the data. We relate Gamma (!) to the strength v of the interaction that couples the normally deformed levels to the SD level at which the decay out of the SD band occurs. Using an exponential spin dependence of v, we are able to reproduce the intraband intensities in the SD bands in Hg-194 and Pb-194.
2001
Article
http://edoc.mpg.de/27723
Physical Review C, v.6406, 064316-064316 (2001)
en
oai:edoc.mpg.de:277982003-08-0737:452
Stochastic properties of many-body systems
Weidenmüller, H. A.
expertsonly
random-matrix theory; shell model; spectral statistics
The k-body embedded ensembles of random matrices originally defined by Mon and French are investigated as paradigmatic models of stochasticity in Fermionic many-body systems. In these ensembles, m Fermions in I degenerate single-particle states, interact via a random k-body interaction which obeys unitary or orthogonal symmetry. We focus attention on the spectral properties of these ensembles. We always take the limit l --> infinity. For 2k > m, the spectral properties of the k-body embedded unitary and orthogonal ensembles coincide with those of the canonical Gaussian unitary and orthogonal random-matrix ensemble, respectively. For k < < in < < l, the spectral fluctuations become Poissonian. The reason for this behavior is displayed by constructing limiting ensembles. The case of embedded Bosonic ensembles (m Bosons in l degenerate single-particle states interact via a random k-body interaction which obeys unitary or orthogonal symmetry) is also considered and compared with the case of Fermions. (C) 2001 Elsevier Science B.V. All rights reserved.
2001
Article
http://edoc.mpg.de/27798
Physica A, v.302, 302-309 (2001)
en
oai:edoc.mpg.de:278012003-08-0737:452
Wilson loops in N = 4 supersymmetric Yang-Mills theory from random matrix theory
Akemann, G.
Damgaard, P. H.
expertsonly
2002
Article
http://edoc.mpg.de/27801
urn:ISSN:0370-2693
Physics Letters B, v.524, 400-400 (2002)
en
oai:edoc.mpg.de:278172003-08-0737:452
Nonadiabatic controlled-NOT gate for the Kane solid-state quantum computer
Wellard, C.
Hollenberg, L. C. L.
Pauli, H. C.
expertsonly
The method of iterated resolvents is used to obtain an effective Hamiltonian for neighboring qubits in the Kane solid- state quantum computer. In contrast to the adiabatic gate processes inherent in the Kane proposal we show that free evolution of the qubit-qubit system, as generated by this effective Hamiltonian, combined with single-qubit operations, is sufficient to produce a controlled-NOT gate. Thus the usual set of universal gates can be obtained on the Kane quantum computer without the need for adiabatic switching of the controllable parameters as prescribed by Kane [Nature (London) 393, 133 (1998)]. Both the fidelity and the gate time of this nonadiabatic controlled-NOT gate are determined by numerical simulation.
2002
Article
http://edoc.mpg.de/27817
urn:ISSN:1050-2947
Physical Review A, v.65, 032303-032303 (2002)
en
oai:edoc.mpg.de:278242003-08-0737:452
Modeling the reversible decoherence of mesoscopic superpositions in dissipative environments
Mokarzel, S. G.
Salgueiro, A. N.
Nemes, M. C.
expertsonly
A model is presented to describe the recently proposed experiment [J. Raimond, M. Brune, and S. Haroche, Phys. Rev. Lett 79, 1964 (1997)] in which a mesoscopic superposition of radiation states is prepared in a high-Q cavity that is coupled to a similar resonator. The dynamical coherence loss of such a state in the absence of dissipation is reversible and can be observed in principle. We show how this picture is modified due to the presence of the environmental couplings. Analytical expressions for the experimental conditional probabilities and the linear entropy are given. We conclude that the phenomenon can still be observed provided the ratio between the damping constant and the intercavities coupling does not exceed about a few percent. This observation is favored for superpositions of states with a large overlap.
2002
Article
http://edoc.mpg.de/27824
Physical Review A, v.65 (2002)
en
oai:edoc.mpg.de:278302003-08-0737:452
Rate equations for sympathetic cooling of trapped bosons or fermions
Papenbrock, T.
Salgueiro, A. N.
Weidenmüller, H. A.
expertsonly
We derive two different sets of rate equations for sympathetic cooling of harmonically trapped bosons or fermions. The rate equations are obtained from a master equation derived earlier by Lewenstein et al. [Phys. Rev. A 51, 4617 (1995)] by means of decoherence and ergodicity arguments. We show analytically that the thermal equilibrium state is a stationary solution of our rate equation. We present analytical results for the rate coefficients which are needed to solve the rate equations, and we give approximate formulas that permit their computation in practice. We solve the two sets of rate equations numerically and compare the results. The cooling times obtained in both approaches agree very well. The equilibration rates show fair agreement.
2002
Article
http://edoc.mpg.de/27830
Physical Review A, v.65 (2002)
en
oai:edoc.mpg.de:281862003-08-0737:452
Recursive construction for a class of radial functions. II. Superspace
Guhr, T.
Kohler, H.
expertsonly
We extend the recursion formula for matrix Bessel functions, which we obtained previously, to superspace. It is sufficient to do this for the unitary orthosymplectic supergroup. By direct computations, we show that fairly explicit results can be obtained, at least up to dimension 8x8 for the supermatrices. Since we introduce a new technique, we discuss various of its aspects in some detail. (C) 2002 American Institute of Physics.
2002
Article
http://edoc.mpg.de/28186
urn:ISSN:0022-2488
Journal of Mathematical Physics, v.43, 2741-2769 (2002)
en
oai:edoc.mpg.de:281902003-08-0737:452
Correlations of Wilson lines and the proton structure function F-2
Pirner, H. J.
Yuan, F.
expertsonly
We discuss deep inelastic scattering at low x as a critical phenomenon in 2 + 1 space - time dimensions. QCD (SU2) near the light cone becomes a critical theory in the limit of x --> 0 with a correlation mass m(x) proportional to x(v/2). We conjecture that the perturbative dipole wave function of the virtual photon in the region 1/Q < x(perpendicular to) < 1/m obeys correlation scaling Psi proportional to (x(perpendicular to))(-(1+n)) before exponentially decaying for distances larger than the inverse correlation mass. Using this behavior combined with an x-independent dipole proton cross section we calculate the proton structure function and compare with the experimental data.
2002
Article
http://edoc.mpg.de/28190
urn:ISSN:0920-5632
Nuclear Physics B-Proceedings Supplements, v.108, 313-317 (2002)
en
oai:edoc.mpg.de:281912003-07-1137:452
On the effective Hamiltonian for QCD: An overview and status report
Pauli, H. C.
expertsonly
The session on effective Hamiltonians and chiral dynamics is overviewed, combined with a review on the bound-state problem. The progress during this session allows to remove all dependence on regularization in an effective interaction, and to solve front form as if they were instant-form equations, with all the advantages implied.
2002
Article
http://edoc.mpg.de/28191
urn:ISSN:0920-5632
Nuclear Physics B-Proceedings Supplements, v.108, 273-280 (2002)
en
oai:edoc.mpg.de:281922003-08-0737:452
On helicity and spin on the light cone
Krassnigg, A.
Pauli, H. C.
expertsonly
Starting from a one-body front-form equation with Lepage- Brodsky spinors we show, with a fair amount of new technology, how an integral equation in standard momentum space with Bjorken-Drell spinors can be obtained. The integral equation decouples for singlets and triplets.
2002
Article
http://edoc.mpg.de/28192
urn:ISSN:0920-5632
Nuclear Physics B-Proceedings Supplements, v.108, 251-255 (2002)
en
oai:edoc.mpg.de:281932003-07-1137:452
Renormalization of an effective model Hamiltonian by a counterterm
Frewer, M.
Frederico, T.
Pauli, H. C.
expertsonly
An ill-defined integral equation for modeling the mass-spectrum of mesons is regulated with an additional but unphysical parameter. This parameter dependance is removed by renormalization. Illustrative graphical examples are given.
2002
Article
http://edoc.mpg.de/28193
urn:ISSN:0920-5632
Nuclear Physics B-Proceedings Supplements, v.108, 239-241 (2002)
en
oai:edoc.mpg.de:281942003-08-0737:452
Renormalized QCD-inspired model for the pion and mesons
Frederico, T.
Frewer, M.
Pauli, H. C.
expertsonly
We apply the subtraction method to an effective QCD-inspired model, which includes the Coulomb plus a zero-range hyperfine interactions, to define a renormalized Hamiltonian for mesons. The spectrum of the renormalized Hamiltonian agrees with the one obtained with a smeared hyperfine interaction. The masses of the low-lying pseudoscalar and vector mesons are reasonably described within the model.
2002
Article
http://edoc.mpg.de/28194
urn:ISSN:0920-5632
Nuclear Physics B-Proceedings Supplements, v.108, 234-238 (2002)
en
oai:edoc.mpg.de:282342003-08-0737:452
Symmetry properties of the k-body embedded unitary Gaussian ensemble of random matrices
Pluhar, Z.
Weidenmüller, H. A.
expertsonly
We extend the recent study of the k-body embedded Gaussian ensembles by L. Benet, T. Rupp. and H. A. Weidenmuller (2001. Benet. Phys. Rev. Lett. 87, 101601-1 and 2001, Aim. Phys. (N.Y.) 292. 67) and by T Asaga. L. Benet. T. Rupp. and H. A. Weidenmuller (cond-mat/0107363 and condmat/0107364). We show that central results of these papers can be derived directly from the symmetry properties of both the many-particle states and the random k-body interaction. We offer new insight into the structure of the matrix of second moments of the embedded ensemble and of the supersymmetry approach. We extend the concept of the embedded ensemble and define it purely group- theoretically. (C) 2002 Elsevier Science (USA).
2002
Article
http://edoc.mpg.de/28234
urn:ISSN:0003-4916
Annals of Physics, v.297, 344-362 (2002)
en
oai:edoc.mpg.de:282352003-08-0737:452
Mixing of bound and unbound levels
von Brentano, P.
Jolos, R. V.
Weidenmüller, H. A.
expertsonly
We consider a system of two discrete levels coupled to a channel. The levels are close to threshold. We investigate the influence of the channel threshold on positions and widths of the levels. We introduce a simple parameterization of the energy dependence of the coupling matrix elements. Simple examples demonstrate the importance of this dependence. (C) 2002 Published by Elsevier Science B.V.
2002
Article
http://edoc.mpg.de/28235
urn:ISSN:0370-2693
Physics Letters B, v.534, 63-68 (2002)
en
oai:edoc.mpg.de:282562003-08-0737:452
Spectral properties of the k-body embedded Gaussian ensembles of random matrices for bosons
Asaga, T.
Benet, L.
Rupp, T.
Weidenmüller, H. A.
expertsonly
We consider m spinless Bosons distributed over I degenerate single-particle states and interacting through a k-body random interaction with Gaussian probability distribution (the Bosonic embedded k-body ensembles). We address the cases of orthogonal and unitary symmetry in the limit of infinite matrix dimension, attained either as l --> infinity, or as m --> infinity. We derive an eigenvalue expansion for the second moment of the many-body matrix elements of these ensembles. Using properties of this expansion, the supersymmetry technique, and the binary correlation method, we show that in the limit l --> infinity the ensembles have nearly the same spectral properties as the corresponding Fermionic embedded ensembles. Novel features specific for Bosons arise in the dense limit defined as m --> infinity with both k and l fixed. Here we show that the ensemble is not ergodic and that the spectral fluctuations are not of Wigner-Dyson type. We present numerical results for the dense limit using both ensemble unfolding and spectral unfolding. These differ strongly, demonstrating the lack of ergodicity of the ensemble. Spectral unfolding shows a strong tendency toward picket-fence-type spectra. Certain eigenfunctions of individual realizations of the ensemble display Fock-space localization. (C) 2002 Elsevier Science (USA).
2002
Article
http://edoc.mpg.de/28256
urn:ISSN:0003-4916
Annals of Physics, v.298, 229-247 (2002)
en
oai:edoc.mpg.de:282602003-07-1137:452
Bayesian analysis of level-spacing distributions for chaotic systems with broken symmetry
Abul-Magd, A. Y.
Dembowski, C.
Harney, H. L.
Simbel, M. H.
expertsonly
Bayesian inference is applied to the nearest-neighbor and next- nearest-neighbor spacing distributions of levels of coupled superconducting microwave billiards. The weakly coupled resonators are equivalent to a quantum system with a partially broken symmetry. The coupling parameters are obtained with help from Bayes's theorem. This procedure does not require the introduction of a set of bins. The results are more accurate than those obtained from other bin-independent procedures.
2002
Article
http://edoc.mpg.de/28260
urn:ISSN:1063-651X
Physical Review E, v.65, 056221-056221 (2002)
en
oai:edoc.mpg.de:288452003-07-1437:452
On the form factor of physical mesons and their distribution function
Pauli, H. C.
expertsonly
This work addresses more to the technical rather than to the physical problem, how to calculate analytically the form factor F(Q), the associated mean-square radius (r(2)), and the distribution function Phi(x, Q(2)) for a given light-cone wave function psi(q)((q)) over bar (x, (k) over right arrow (perpendicular to)) of the pion. They turn out to be functions of only one dimensionless parameter, which is the ratio of the constituent quark mass and an effective Bohr momentum which measures the width of the wave function in momentum space. Both parameters are subject to change in the future, when the presently used solution for the over simplified up arrowdown arrow-model will be replaced by something better. Their relation to and agreement with experiment is discussed in detail. The procedure can be generalized also to other hadrons. (C) 2002 Elsevier Science B.V. All rights reserved.
2002
Article
http://edoc.mpg.de/28845
urn:ISSN:0375-9474
Nuclear Physics A, v.705, 73-89 (2002)
en
oai:edoc.mpg.de:288462003-08-0737:452
Random matrix approach to cross correlations in financial data
Plerou, V.
Gopikrishnan, P.
Rosenow, B.
Amaral, L. A. N.
Guhr, T.
Stanley, H. E.
expertsonly
We analyze cross correlations between price fluctuations of different stocks using methods of random matrix theory (RMT). Using two large databases, we calculate cross-correlation matrices C of returns constructed from (i) 30-min returns of 1000 US stocks for the 2-yr period 1994-1995, (ii) 30-min returns of 881 US stocks for the 2-yr period 1996-1997, and (iii) 1-day returns of 422 US stocks for the 35-yr period 1962- 1996. We test the statistics of the eigenvalues lambda(i) of C against a "null hypothesis" - a random correlation matrix constructed from mutually uncorrelated time series. We find that a majority of the eigenvalues of C fall within the RMT bounds [lambda(-),lambda(+)] for the eigenvalues of random correlation matrices. We test the eigenvalues of C within the RMT bound for universal properties of random matrices and find good agreement with the results for the Gaussian orthogonal ensemble of random matrices-implying a large degree of randomness in the measured cross-correlation coefficients. Further, we find that the distribution of eigenvector components for the eigenvectors corresponding to the eigenvalues outside the RMT bound display systematic deviations from the RMT prediction. In addition, we find that these "deviating eigenvectors" are stable in time. We analyze the components of the deviating eigenvectors and find that the largest eigenvalue corresponds to an influence common to all stocks. Our analysis of the remaining deviating eigenvectors shows distinct groups, whose identities correspond to conventionally identified business sectors. Finally, we discuss applications to the construction of portfolios of stocks that have a stable ratio of risk to return.
2002
Article
http://edoc.mpg.de/28846
urn:ISSN:1063-651X
Physical Review E, v.65, 066126-066126 (2002)
en
oai:edoc.mpg.de:288492003-08-0737:452
Transmission phase of an isolated Coulomb blockade resonance
Weidenmüller, H. A.
expertsonly
In two recent papers, O. Entin-Wohlman [cond-mat/0109328 (unpublished) and (private communication)] studied the question: "Which physical information is carried by the transmission phase through a quantum dot?" In the present paper, this question is answered for an islolated Coulomb blockade resonance and within a theoretical model which is more closely patterned after the geometry of the actual experiment by Schuster [Nature 385, 417 (1997)] than is the model of O. Entin-Wohlman We conclude that whenever the number of leads coupled to the Aharanov-Bohm interferometer is larger than two, and the total number of channels is sufficiently large, the transmission phase does reflect the Breit-Wigner behavior of the resonance phase shift.
2002
Article
http://edoc.mpg.de/28849
urn:ISSN:0163-1829
Physical Review B, v.65, 245322-245322 (2002)
en
oai:edoc.mpg.de:288662003-08-0737:452
Sympathetic cooling and growth of a Bose-Einstein condensate
Papenbrock, T.
Salgueiro, A. N.
Weidenmüller, H. A.
expertsonly
We study two sets of rate equations for sympathetic cooling of harmonically trapped Bose gases. Calculations for mixtures of Na-Rb and Li-Cs show that both sets yield similar results for the cooling times. The equilibration rates are in fair agreement with each other and differ considerably from classical rates. The onset of Bose-Einstein condensation is rather sudden and nonexponential in time, and the growth of the condensate differs for the two different mixtures we studied.
2002
Article
http://edoc.mpg.de/28866
urn:ISSN:1050-2947
Physical Review A, v.66, 025603-025603 (2002)
en
oai:edoc.mpg.de:288712003-08-0737:452
Critical correlations of Wilson lines in SU(3) and the high energy gamma(*)p cross section
Pirner, H. J.
Yuan, F.
expertsonly
2002
Article
http://edoc.mpg.de/28871
urn:ISSN:0556-2821
Physical Review D, v.66, 034020-034020 (2002)
en
oai:edoc.mpg.de:288722003-08-0737:452
S-matrix unitarity, impact parameter profiles, gluon saturation and high-energy scattering
Shoshi, A. I.
Steffen, F. D.
Pirner, H. J.
expertsonly
gluon saturation; high-energy scattering; impact parameter profiles; loop-loop scattering; multiple-gluon exchange; pomeron; QCD; stochastic vacuum model; unitarity
A model combining perturbative and non-perturbative QCD is developed to compute high-energy reactions of hadrons and photons and to investigate saturation effects that manifest the S-matrix unitarity. Following a functional integral approach, the S-matrix factorizes into light-cone wave functions and the universal amplitude for the scattering of two color-dipoles which are represented by Wegner-Wilson loops. In the framework of the non-perturbative stochastic vacuum model of QCD supplemented by perturbative gluon exchange, the loop-loop correlation is calculated and related to lattice QCD investigations. With a universal energy dependence motivated by the two-pomeron (soft + hard) picture that respects the unitarity condition in impact parameter space, a unified description of pp, pip, Kp, gamma*p, and gammagamma reactions is achieved in good agreement with experimental data for cross sections, slope parameters, and structure functions. Impact parameter profiles for pp and gamma(L)*p reactions and the gluon distribution of the proton xG(x, Q(2), \(b) over right arrow (perpendicular to)\) are calculated and found to saturate in accordance with S-matrix unitarity. The c.m. energies and Bjorken x at which saturation sets in are determined. (C) 2002 Elsevier Science B.V. All rights reserved.
2002
Article
http://edoc.mpg.de/28872
urn:ISSN:0375-9474
Nuclear Physics A, v.709, 131-183 (2002)
en
oai:edoc.mpg.de:288732003-08-0737:452
Integration over matrix spaces with unique invariant measures
Prosen, T.
Seligman, T. H.
Weidenmüller, H. A.
expertsonly
We present a method to calculate integrals over monomials of matrix elements with invariant measures in terms of Wick contractions. The method gives exact results for monomials of low order. For higher-order monomials, it leads to an error of order 1/N-alpha, where N is the dimension of the matrix and where alpha is independent of the degree of the monomial. We give a lower bound on the integer alpha and show how alpha can be increased systematically. The method is particularly suited for symbolic computer calculation. Explicit results are given for O(N), U(N), and for the circular orthogonal ensemble. (C) 2002 American Institute of Physics.
2002
Article
http://edoc.mpg.de/28873
urn:ISSN:0022-2488
Journal of Mathematical Physics, v.43, 5135-5144 (2002)
en
oai:edoc.mpg.de:288782003-08-0737:452
Mean-field approximation to the master equation for sympathetic cooling of trapped bosons
Wang, S. J.
Nemes, M. C.
Salgueiro, A. N.
Weidenmüller, H. A.
expertsonly
We use the mean-field approximation to simplify the master equation for sympathetic cooling of bosons. For the mean single-particle occupation numbers, this approach yields the same equations as the factorization assumption introduced in an early paper. The stationary or equilibrium solution of the resulting master equation for the one-body density matrix shows that the mean-field approximation breaks down whenever the fraction of condensate bosons exceeds 10% or so of the total. Using group-theoretical methods, we also solve the time- dependent master equation for the one-body density matrix. Given the time dependence of the mean single-particle occupation numbers, this solution is obtained by quadratures. It tends asymptotically towards the equilibrium solution.
2002
Article
http://edoc.mpg.de/28878
urn:ISSN:1050-2947
Physical Review A, v.66, 033608-033608 (2002)
en
oai:edoc.mpg.de:288792003-08-0737:452
Splitting of the pi-rho spectrum in a renormalized light-cone QCD-inspired model
Frederico, T.
Pauli, H. C.
Zhou, S. G.
expertsonly
We show that the splitting between the light pseudoscalar and vector meson states is due to the strong short-range attraction in the S-1(0) sector which makes the pion and the kaon light particles. We use a light-cone QCD-inspired model of the mass squared operator with harmonic confinement and a Dirac-delta interaction. We apply a renormalization method to define the model, in which the pseudoscalar ground state mass fixes the renormalized strength of the Dirac-delta interaction.
2002
Article
http://edoc.mpg.de/28879
urn:ISSN:0556-2821
Physical Review D, v.66, 054007-054007 (2002)
en
oai:edoc.mpg.de:288992003-08-0737:452
Thermal noise in a solid state quantum computer
Wellard, C. J.
Hollenberg, L. C. L.
expertsonly
The Kane proposal for the construction of a solid state quantum computer calls for the placement of a metallic A-gate above each nuclear qubit. Voltage biases applied to these A-gates are to be used to control the evolution of the qubits. In this paper, we consider the decohering effect of thermal fluctuations, the so-called Johnson noise, in the A-gate biases, on the average evolution of qubits undergoing single qubit rotations, as well as those that are not undergoing any operation at all. We find that although the errors introduced are of a different nature for each case, phase errors for the static qubits and both phase and bit-flip errors for qubits undergoing operations, the net error probability is similar for both, and low enough when compared to the timescale of single qubit operations for them to be corrected efficiently.
2002
Article
http://edoc.mpg.de/28899
urn:ISSN:0022-3727
Journal of Physics D-Applied Physics, v.35, 2499-2502 (2002)
en
oai:edoc.mpg.de:291242003-08-0737:452
Decomposition of the QCD string into dipoles and unintegrated gluon distributions
Shoshi, A. I.
Steffen, F. D.
Dosch, H. G.
Pirner, H. J.
notspecified
We present the perturbative and non-perturbative QCD structure of the dipole-dipole scattering amplitude in momentum space. The perturbative contribution is described by the two-gluon exchange and the non-perturbative contribution by the stochastic vacuum model which leads to confinement of the quark and antiquark in the dipole via a string of color fields. This QCD string gives important nonperturbative contributions to high-energy reactions. A new structure different from the perturbative dipole factors is found in the string-string scattering amplitude. The string can be represented as an integral over stringless dipoles with a given dipole number density. This decomposition of the QCD string into dipoles allows us to calculate the unintegrated gluon distribution of hadrons and photons from the dipole-hadron and dipole-photon cross section via \(k) over right arrow (perpendicular to)\ factorization.
2002
Article
http://edoc.mpg.de/29124
urn:ISSN:0556-2821
Physical Review D, v.66, 094019-094019 (2002)
en
oai:edoc.mpg.de:291482003-08-0737:452
Universal description of S-wave meson spectra in a renormalized light-cone QCD-inspired model
Frederico, T.
Pauli, H. C.
Zhou, S. G.
expertsonly
A light-cone QCD-inspired model, with the mass squared operator consisting of a harmonic oscillator potential as confinement and a Dirac delta interaction, is used to study S-wave meson spectra. The two parameters of the harmonic potential and quark masses are fixed by the masses of rho(770), rho(1450), J/psi, psi(2S), K*(892), and B*. We apply a renormalization method to define the model, in which the pseudoscalar ground state mass fixes the renormalized strength of the Dirac delta interaction. The model presents a universal and satisfactory description of both singlet and triplet states of S-wave mesons and the corresponding radial excitations.
2002
Article
http://edoc.mpg.de/29148
urn:ISSN:0556-2821
Physical Review D, v.66, 116011-116011 (2002)
en
oai:edoc.mpg.de:291512003-07-1637:452
Observation of a chiral state in a microwave cavity
Dembowski, C.
Dietz, B.
Graf, H. D.
Harney, H. L.
Heine, A.
Heiss, W. D.
Richter, A.
expertsonly
A microwave experiment has been realized to measure the phase difference of the oscillating electric field at two points inside the cavity. The technique has been applied to a dissipative resonator which exhibits a singularity-called exceptional point-in its eigenvalue and eigenvector spectrum. At the singularity, two modes coalesce with a phase difference of pi/2. We conclude that the state excited at the singularity has a definitive chirality.
2003
Article
http://edoc.mpg.de/29151
urn:ISSN:0031-9007
Physical Review Letters, v.90, 034101-034101 (2003)
en
oai:edoc.mpg.de:292272003-07-1637:452
Experimental versus simulated Coulomb-explosion images of flexible molecules: Structure of protonated acetylene C2H3+
Knoll, L.
Vager, Z.
Marx, D.
expertsonly
The most probable structure of protonated acetylene C2H3+ (the "vinyl cation") is inferred from both Coulomb-explosion experiments and finite-temperature ab initio quantum simulations followed by simulations of foil effects. It is found that C2H3+ features significant deviations from the planar bridged equilibrium structure as well as from the planar Y-shaped local minimum structure, which are known from static electronic structure calculations. In particular, the "axial protons" feature a significant out-of-plane trans-bending due to fluctuation effects. This implies that the nonplanarity has to be taken into account in theoretical treatments that aim at describing this fluxional molecule.
2003
Article
http://edoc.mpg.de/29227
urn:ISSN:1050-2947
Physical Review A, v.67, 022506-022506 (2003)
en
oai:edoc.mpg.de:292332003-08-0737:452
Character expansions for the orthogonal and symplectic groups
Balantekin, A. B.
Cassak, P.
expertsonly
Formulas for the expansion of arbitrary invariant group functions in terms of the characters for the Sp(2N), SO(2N+1), and SO(2N) groups are derived using a combinatorial method. The method is similar to one used by Balantekin to expand group functions over the characters of the U(N) group. All three expansions have been checked for all N by using them to calculate the known expansions of the generating function of the homogeneous symmetric functions. An expansion of the exponential of the traces of group elements, appearing in the finite-volume gauge field partition functions, is worked out for the orthogonal and symplectic groups. (C) 2002 American Institute of Physics.
2002
Article
http://edoc.mpg.de/29233
urn:ISSN:0022-2488
Journal of Mathematical Physics, v.43, 604-620 (2002)
en
oai:edoc.mpg.de:292352004-06-1137:452
Decoherence in chaotic and integrable systems: a random matrix approach
Gorin, T.
Seligman, T. H.
expertsonly
We study the influence of chaos and order on entanglement and decoherence. In view of applications in quantum computing and teleportation which should be able to work with arbitrarily complicated states, we pay particular attention to the behavior of random states. While studies with coherent states indicate that chaos accelerates decoherence and entanglement, we find that there is practically no difference between the chaotic and the integrable case, as far as random states are concerned. In the present studies we use unitary time evolution of the total system, and partial traces to emulate decoherence. Random matrix models are a natural choice to describe the dynamics of random states. The invariant aspects of chaos and order are then reflected in the different spectral statistics. We develop random matrix models for the evolution of entanglement for a large variety of situations, discussing the strong coupling case in full detail. (C) 2003 Elsevier Science B.V. All rights reserved.
2003
Article
http://edoc.mpg.de/29235
urn:ISSN:0375-9601
Physics Letters A, v.309, 61-67 (2003)
en
oai:edoc.mpg.de:292412003-07-1637:452
EDM operator free from Schiff's theorem
Asaga, T.
Fujita, T.
Hiramoto, M.
expertsonly
We present a generalization of Schiff's transformation of electric dipole moments (EDM) in quantum field theory. Under the unitary transformation, the time and parity violating interaction i ge/2 (ψ) over bar sigma(muv) gamma(5) psi F- muv is transformed into a new form, but its nonrelativistic reduction has a unique form to which Schiff's theorem does not apply. The relativistic corrections to the new EDM operator slightly increase the EDM, as given by b(2) (alphaZ)(2) with b(2) similar or equal to 2. It is thus seen that the calculation of the EDM with nonrelativistic Hartree-Fock wave functions presents a conservative but reliable estimation for the enhancement factor of the EDM in atoms.
2001
Article
http://edoc.mpg.de/29241
urn:ISSN:0033-068X
Progress of Theoretical Physics, v.106, 1223-1238 (2001)
en
oai:edoc.mpg.de:328162003-08-0737:452
Quantum corrections to the ground state energy of inhomogeneous neutron matter
Bulgac, A.
Magierski, P.
expertsonly
2002
Article
http://edoc.mpg.de/32816
urn:ISSN:0375-9474
Nuclear Physics A, v.703, 892-892 (2002)
en
oai:edoc.mpg.de:328192003-08-0737:452
Effective dielectric constant of a two-component material with shape distribution
Gao, L.
Gu, J. Z.
expertsonly
The effective dielectric constant of a two-component material is investigated. By considering the shape distribution of the components, we derive Maxwell-Garnett-type approximation, which has been established based on the reciprocity theorem (del Rio J A et al 1998 Solid State Commun. 106 183). Based on a self- consistent condition on the electric field (Bruggeman-type effective medium approximation), we obtain the well-known Lichtenecker's mixture formulae with alpha = 1/2. Moreover, we derive the differential effective medium approximation by taking into account the shape distribution. All these formulae are checked through the spectral density function and compared with previous bounds.
2002
Article
http://edoc.mpg.de/32819
urn:ISSN:0022-3727
Journal of Physics D-Applied Physics, v.35, 267-271 (2002)
en
oai:edoc.mpg.de:328202003-07-2137:452
Three-body confinement force in hadron spectroscopy
Pepin, S.
Stancu, F.
expertsonly
Recently it has been argued that a three-body color confinement interaction can affect the stability condition of a three-quark system and the spectrum of a tetraquark described by any constituent quark model. Here we discuss the role of a three- body color confinement interaction in a simple quark model and present some of its implications for the spectra of baryons, tetraquarks and six-quark systems.
2002
Article
http://edoc.mpg.de/32820
urn:ISSN:0556-2821
Physical Review D, v.65, 054032-054032 (2002)
en
oai:edoc.mpg.de:328232003-07-2137:452
Scaling behavior of layered high-T-c superconductors with columnar defects
Braverman, G. M.
Gredeskul, S. A.
Avishai, Y.
expertsonly
It was recently observed [van der Beek et al., Phys, Rev. B 54, R792 (1996)] that irradiated layered high-T-c superconductors subject to perpendicular magnetic field manifest two similar scaling behaviors corresponding to two different critical temperatures. We show that this phenomenon is explained within the framework of the Ginzburg-Landau theory. In the weak field region, the scaling function differs from that of a clean sample mainly because of the renormalization of the critical temperature, due to defects. In the strong field region, defects are effectively suppressed and the scaling function, as well as the critical temperature, are the same as in a clean superconductor, The theory presented here agrees quite satisfactory with experiment.
2002
Article
http://edoc.mpg.de/32823
urn:ISSN:0163-1829
Physical Review B, v.6505, 054512-054512 (2002)
en
oai:edoc.mpg.de:328272003-08-0737:452
Classical scattering from oscillating targets
Papachristou, P. K.
Diakonos, F. K.
Constantoudis, V.
Schmelcher, P.
Benet, L.
expertsonly
We study planar classical scattering from an oscillating heavy target whose dynamics defines a five-dimensional phase space. Although the system possesses no periodic orbits, and thus topological chaos is not present, the scattering functions display a variety of structures on different time scales. These structures are due to scattering events with a strong energy transfer from the projectile to the moving disk resulting in low-velocity peaks. We encounter initial conditions for which the projectile exhibits infinitely many bounces with the oscillating disk. Our numerical investigations are supported by analytical results on a specific model with a simple time-law. The observed properties possess universal character for scattering off oscillating targets. (C) 2002 Elsevier Science B.V. All rights reserved.
2002
Article
http://edoc.mpg.de/32827
urn:ISSN:0375-9601
Physics Letters A, v.306, 116-126 (2002)
en
oai:edoc.mpg.de:330282003-07-2137:452
Occurrence of planetary rings with shepherds
Benet, L.
expertsonly
planetary rings; shepherd moons; periodic orbits
We consider the system of planetary rings with shepherds as a restricted three or four-body problem, neglecting interactions between ring particles. We show that the generic occurrence of rings for the case of rotating short-range potentials can be extended to the case of gravitational potentials. The consecutive collision periodic orbits created by saddle-center bifurcations are of central importance.
2001
Article
http://edoc.mpg.de/33028
urn:ISSN:0923-2958
Celestial Mechanics & Dynamical Astronomy, v.81, 123-128 (2001)
en
oai:edoc.mpg.de:604922004-06-1137:452
Crossing of two Coulomb blockade resonances
Weidenmüller, H. A.
expertsonly
We investigate theoretically the transport of noninteracting electrons through an Aharanov-Bohm (AB) interferometer with two quantum dots (QD's) embedded into its arms. In the Coulomb blockade regime, transport through each QD proceeds via a single resonance. The resonances are coupled through the arms of the AB device, but may also be coupled directly. In the framework of the Landauer-Büttiker approach, we present expressions for the scattering matrix which depend explicitly on the energies of the two resonances and on the AB phase. We pay particular attention to the crossing of the two resonances.
©2003 The American Physical Society
2003
Article
http://edoc.mpg.de/60492
Physical Review B (Condensed Matter and Materials Physics -15(II)), v.68, 125326-125334 (2003)
en
oai:edoc.mpg.de:608712004-01-2137:452
Review of the k-body embedded ensembles of Gaussian random matrices
Benet, L.
Weidenmüller, H.A.
expertsonly
The embedded ensembles were introduced by Mon and French (1975 Ann. Phys., NY 95 90) as physically more plausible stochastic models of many-body systems governed by one- and two-body interactions than provided by standard random-matrix theory. We review several approaches aimed at determining the spectral density, the spectral fluctuation properties and the ergodic properties of these ensembles: moments methods, numerical simulations, the replica trick, the eigenvector decomposition of the matrix of second moments and supersymmetry, the binary correlation approximation, and the study of correlations between matrix elements.
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Copyright © Institute of Physics and IOP Publishing Limited 2004.
2003
Article
http://edoc.mpg.de/60871
Journal of Physics A: Mathematical and General, v.36, 3569-3593 (2003)
en
oai:edoc.mpg.de:611252004-01-2337:452
Localization properties of two interacting electrons in a disordered quasi one-dimensional potential
Richert, J.
Weidenmüller, H.A.
expertsonly
We study the transport properties of two electrons in a quasi one-dimensional disordered wire. The electrons are subject to both a disorder potential and a short range two-body interaction. Using the approach developed by Iida et al (1990 Ann. Phys., NY 200 219), the supersymmetry technique and a suitable truncation of Hilbert space, we work out the two-point correlation function in the framework of a nonlinear model. We study the loop corrections to arbitrary order. We obtain a remarkably simple and physically transparent expression for the change of the localization length caused by the two-body interaction.
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Author: Vol/Year: Issue: Page/Article No:
Copyright © Institute of Physics and IOP Publishing Limited 2004.
2003
Article
http://edoc.mpg.de/61125
Journal of Physics A: Mathematical and General, v.36, 3281-3288 (2003)
en
oai:edoc.mpg.de:612522004-01-2637:452
Two interacting electrons in a disorder potential: localization properties
Richert, J.
Weidenmüller, H.A.
expertsonly
Two electrons move in a quasi one-dimensional wire under the influence of a short-range interaction. We restrict Hilbert space to those states where the two electrons are close to each other. Using supersymmetry, we present a complete analytical solution to this problem. The two-body interaction affects the density of states and, thereby, the localization length. We derive a criterion for the onset of changes of the localization length due to the two-body interaction.
Copyright © 2003 Elsevier Science (USA). All rights reserved.
2003
Article
http://edoc.mpg.de/61252
Annals of Physics, v.306, 96-131 (2003)
en
oai:edoc.mpg.de:612532004-01-2637:452
Spectral Properties of the k-Body Embedded Gaussian Ensembles of Random Matrices for Bosons
Asaga, T.
Benet, L.
Rupp, T.
Weidenmüller, H.A.
expertsonly
We consider m spinless Bosons distributed over l degenerate single-particle states and interacting through a k-body random interaction with Gaussian probability distribution (the Bosonic embedded k-body ensembles). We address the cases of orthogonal and unitary symmetry in the limit of infinite matrix dimension, attained either as l goes against infiniti or as m goes adainst infiniti. We derive an eigenvalue expansion for the second moment of the many-body matrix elements of these ensembles. Using properties of this expansion, the supersymmetry technique, and the binary correlation method, we show that in the limit l goes against infiniti the ensembles have nearly the same spectral properties as the corresponding Fermionic embedded ensembles. Novel features specific for Bosons arise in the dense limit defined as m goes against infiniti with both k and l fixed. Here we show that the ensemble is not ergodic and that the spectral fluctuations are not of Wigner-Dyson type. We present numerical results for the dense limit using both ensemble unfolding and spectral unfolding. These differ strongly, demonstrating the lack of ergodicity of the ensemble. Spectral unfolding shows a strong tendency toward picket-fence-type spectra. Certain eigenfunctions of individual realizations of the ensemble display Fock-space localization.
Copyright © 2002 Elsevier Science (USA). All rights reserved.
2002
Article
http://edoc.mpg.de/61253
Annals of Physics, v.298, 229-249 (2002)
en
oai:edoc.mpg.de:612552004-01-2637:452
Symmetry Properties of the k-Body Embedded Unitary Gaussian Ensemble of Random Matrices
Pluhar, Z.
Weidenmüller, H.A.
expertsonly
We extend the recent study of the k-body embedded Gaussian ensembles by L. Benet, T. Rupp, and H. A. Weidenmüller (2001, Benet, Phys. Rev. Lett.87, 101601-1 and 2001, Ann. Phys. (N.Y.)292, 67) and by T. Asaga, L. Benet, T. Rupp, and H. A. Weidenmüller (cond-mat/0107363 and cond-mat/0107364). We show that central results of these papers can be derived directly from the symmetry properties of both the many-particle states and the random k-body interaction. We offer new insight into the structure of the matrix of second moments of the embedded ensemble and of the supersymmetry approach. We extend the concept of the embedded ensemble and define it purely group-theoretically.
Copyright © 2002 Elsevier Science (USA). All rights reserved.
2002
Article
http://edoc.mpg.de/61255
Annals of Physics, v.297, 344-362 (2002)
en
oai:edoc.mpg.de:612592004-01-2637:452
Rate equations for sympathetic cooling of trapped bosons or fermions
Papenbrock, T.
Salgueiro, A.N.
Weidenmüller, H.A.
expertsonly
We derive two different sets of rate equations for sympathetic cooling of harmonically trapped bosons or fermions. The rate equations are obtained from a master equation derived earlier by Lewenstein et al. [Phys. Rev. A 51, 4617 (1995)] by means of decoherence and ergodicity arguments. We show analytically that the thermal equilibrium state is a stationary solution of our rate equation. We present analytical results for the rate coefficients which are needed to solve the rate equations, and we give approximate formulas that permit their computation in practice. We solve the two sets of rate equations numerically and compare the results. The cooling times obtained in both approaches agree very well. The equilibration rates show fair agreement.
©2002 The American Physical Society
2002
Article
http://edoc.mpg.de/61259
Physical Review A (Atomic, Molecular, and Optical Physics), v.65, 1-14 (2002)
en
oai:edoc.mpg.de:612752004-01-2637:452
Sympathetic cooling and growth of a Bose-Einstein condensate
Papenbrock, T.
Salgueiro, A.N.
Weidenmüller, H.A.
expertsonly
We study two sets of rate equations for sympathetic cooling of harmonically trapped Bose gases. Calculations for mixtures of Na-Rb and Li-Cs show that both sets yield similar results for the cooling times. The equilibration rates are in fair agreement with each other and differ considerably from classical rates. The onset of Bose-Einstein condensation is rather sudden and nonexponential in time, and the growth of the condensate differs for the two different mixtures we studied.
©2002 The American Physical Society
2002
Article
http://edoc.mpg.de/61275
Physical Review A (Atomic, Molecular, and Optical Physics), v.66, 1-4 (2002)
en
oai:edoc.mpg.de:613862004-01-2737:452
Statistical Theory of Nuclear Reactions
Weidenmüller, H.A.
expertsonly
Academic Press
2001
InBook
http://edoc.mpg.de/61386
Scattering: scattering and inverse scattering in pure and applied science, 1393-1413 (2001)
en
oai:edoc.mpg.de:618762004-03-0437:452
Transmission phase of an isolated Coulomb blockade resonance
Weidenmüller, H.A.
expertsonly
In two recent papers, O. Entin-Wohlman et al. [cond-mat/0109328 (unpublished) and (private communication)] studied the question: "Which physical information is carried by the transmission phase through a quantum dot?" In the present paper, this question is answered for an islolated Coulomb blockade resonance and within a theoretical model which is more closely patterned after the geometry of the actual experiment by Schuster et al. [Nature 385, 417 (1997)] than is the model of O. Entin-Wohlman et al. We conclude that whenever the number of leads coupled to the Aharanov-Bohm interferometer is larger than two, and the total number of channels is sufficiently large, the transmission phase does reflect the Breit-Wigner behavior of the resonance phase shift.
©2002 The American Physical Society
2002
Article
http://edoc.mpg.de/61876
Physical Review B (Condensed Matter and Materials Physics), v.65, 1-6 (2002)
en
oai:edoc.mpg.de:618842004-01-2937:452
Mean-field approximation to the master equation for sympathetic cooling of trapped bosons
Wang, S.J.
Nemes, M.C.
Salgueiro, A.N.
Weidenmüller, H.A.
expertsonly
We use the mean-field approximation to simplify the master equation for sympathetic cooling of bosons. For the mean single-particle occupation numbers, this approach yields the same equations as the factorization assumption introduced in an early paper. The stationary or equilibrium solution of the resulting master equation for the one-body density matrix shows that the mean-field approximation breaks down whenever the fraction of condensate bosons exceeds 10% or so of the total. Using group-theoretical methods, we also solve the time-dependent master equation for the one-body density matrix. Given the time dependence of the mean single-particle occupation numbers, this solution is obtained by quadratures. It tends asymptotically towards the equilibrium solution.
©2002 The American Physical Society
2002
Article
http://edoc.mpg.de/61884
Physical Review A (Atomic, Molecular, and Optical Physics), v.66, 1-8 (2002)
en
oai:edoc.mpg.de:618912004-01-2837:452
Integration over matrix spaces with unique invariant measures
Prosen, T.
Seligman, T. H.
Weidenmüller, H. A.
expertsonly
We present a method to calculate integrals over monomials of matrix elements with invariant measures in terms of Wick contractions. The method gives exact results for monomials of low order. For higher-order monomials, it leads to an error of order 1/N, where N is the dimension of the matrix and where α is independent of the degree of the monomial. We give a lower bound on the integer and show how α can be increased systematically. The method is particularly suited for symbolic computer calculation. Explicit results are given for O(N), U(N), and for the circular orthogonal ensemble.
©2002 American Institute of Physics.
2002
Article
http://edoc.mpg.de/61891
Journal of Mathematical Physics, v.43, 5135-5144 (2002)
en
oai:edoc.mpg.de:621672004-01-2937:452
Mixing of bound and unbound levels
von Brentano, P.
Jolos, R.V.
Weidenmüller, H.A.
expertsonly
We consider a system of two discrete levels coupled to a channel. The levels are close to threshold. We investigate the influence of the channel threshold on positions and widths of the levels. We introduce a simple parameterization of the energy dependence of the coupling matrix elements. Simple examples demonstrate the importance of this dependence.
Copyright © 2002 Published by Elsevier Science B.V. All rights reserved.
2002
Article
http://edoc.mpg.de/62167
Physics Letters B, v.534, 63-68 (2002)
en
oai:edoc.mpg.de:631042004-02-1037:452
Unordnung und Chaos in Quantensystemen
Weidenmüller, H.A.
popular
LEOPOLDINA 47
2002
InBook
http://edoc.mpg.de/63104
Jahrbuch 2001 der Deutschen Akademie der Naturforscher Leopoldina, 343-355 (2002)
de
oai:edoc.mpg.de:631992004-12-3037:452
Chaos in Atomkernen
Weidenmüller, H.A.
popular
2004
Article
http://edoc.mpg.de/63199
Physik Journal, 41-48 (2004)
de
oai:edoc.mpg.de:632012004-12-3037:452
Persistent currents in n-fold twisted Moebius strips
Ferreira, E.H.M.
Nemes, M.C.
Sampaio, M.D.
Weidenmüller, H.A.
expertsonly
2004
Article
http://edoc.mpg.de/63201
Europhysics Letters, v.333, 146-151 (2004)
en
oai:edoc.mpg.de:632212004-02-1137:452
On the size of hadrons
Pauli, H.C.
Mukherjee, A.
expertsonly
The form factor and the mean-square radius of the pion are calculated analytically from a parametrized form of a q (q) over bar wave function. The numerical wave function was obtained previously by solving numerically an eigenvalue equation for the pion in a particular model. The analytical formulas are of more general interest than just being valid for the pion and can be generalized to the case with unequal quark masses. Two different parametrizations are investigated. Because of the highly relativistic problem, noticeable deviations from a nonrelativistic formula are obtained.
WORLD SCIENTIFIC PUBL CO PTE LTD, JOURNAL DEPT PO BOX 128 FARRER ROAD, SINGAPORE 912805, SINGAPORE
2001
Article
http://edoc.mpg.de/63221
International Journal of Modern Physics A, v.16, 4351-4364 (2001)
en
oai:edoc.mpg.de:632242004-02-2637:452
Power-law wave functions and generalized parton distributions for the pion
Mukherjee, A.
Musatov, I. V.
Pauli, H. C.
Radyushkin, A. V.
expertsonly
We propose a model for generalized parton distributions of the pion based on the power-law Ansatz for the effective light-cone wave function.
©2003 The American Physical Society
2003
Article
http://edoc.mpg.de/63224
Physical Review D (Particles and Fields), v.67, 1-19 (2003)
en
oai:edoc.mpg.de:632372004-02-1237:452
On the form factor of physical mesons and their distribution function
Pauli, H.C.
expertsonly
This work addresses more to the technical rather than to the physical problem, how to calculate analytically the form factor F(Q), the associated mean-square radius <r2>, and the distribution function Φ(x,Q2) for a given light-cone wave function Ψ qqbar( x, kbar) of the pion. They turn out to be functions of only one dimensionless parameter, which is the ratio of the constituent quark mass and an effective Bohr momentum which measures the width of the wave function in momentum space. Both parameters are subject to change in the future, when the presently used solution for the over simplified -model will be replaced by something better. Their relation to and agreement with experiment is discussed in detail. The procedure can be generalized also to other hadrons.
Copyright © 2002 Elsevier Science B.V. All rights reserved.
2002
Article
http://edoc.mpg.de/63237
Nuclear Physics A, v.705, 73-89 (2002)
en
oai:edoc.mpg.de:632402004-02-1237:452
Nonadiabatic controlled CNOT gate for the Kane solid-state quantum computer
Wellard, C.
Hollenberg, L. C. L.
Pauli, H. C.
expertsonly
The method of iterated resolvents is used to obtain an effective Hamiltonian for neighboring qubits in the Kane solid-state quantum computer. In contrast to the adiabatic gate processes inherent in the Kane proposal we show that free evolution of the qubit-qubit system, as generated by this effective Hamiltonian, combined with single-qubit operations, is sufficient to produce a controlled-NOT gate. Thus the usual set of universal gates can be obtained on the Kane quantum computer without the need for adiabatic switching of the controllable parameters as prescribed by Kane [Nature (London) 393, 133 (1998)]. Both the fidelity and the gate time of this nonadiabatic controlled-NOT gate are determined by numerical simulation.
©2002 The American Physical Society
2002
Article
http://edoc.mpg.de/63240
Physical Review A (Atomic, Molecular, and Optical Physics), v.65, 1-4 (2002)
en
oai:edoc.mpg.de:632412004-02-1237:452
Renormalization of an effective light-cone QCD-inspired theory for the pion and other mesons
Frederico, T.
Pauli, H.C.
expertsonly
The renormalization of the effective QCD Hamiltonian theory for the quark-antiquark channel is performed in terms of a renormalized or fixed-point Hamiltonian that leads to subtracted dynamical equations. The fixed-point Hamiltonian gives the renormalization conditions as well as the counterterms that render the theory finite. The approach is renormalization group invariant. The parameters of the renormalized effective QCD Hamiltonian come from the pion mass and radius for a given constituent quark mass. The 1s and excited 2s states of u-bar q are calculated as a function of the mass of the quark q being s, c, or b, and compared to the experimental values.
©2001 The American Physical Society
2001
Article
http://edoc.mpg.de/63241
Physical Review D (Particles and Fields), v.64, 054007 -1-054007 - 13 (2001)
en
oai:edoc.mpg.de:632432004-02-1237:452
Splitting of the pi-rho spectrum in a renormalized light-cone QCD-inspired model
Frederico, T.
Pauli, H.C.
Zhou, S.G.
expertsonly
We show that the splitting between the light pseudoscalar and vector meson states is due to the strong short-range attraction in the 1S0 sector which makes the pion and the kaon light particles. We use a light-cone QCD-inspired model of the mass squared operator with harmonic confinement and a Dirac-delta interaction. We apply a renormalization method to define the model, in which the pseudoscalar ground state mass fixes the renormalized strength of the Dirac-delta interaction
©2002 The American Physical Society
2002
Article
http://edoc.mpg.de/63243
Physical Review D (Particles and Fields), v.66, 054007-1-054007-6 (2002)
en
oai:edoc.mpg.de:632472004-02-1337:452
Experimental tests of non-perturbative pion wave functions
Ashery, D.
Pauli, H.C.
expertsonly
We use the transverse-momentum dependence of the cross section for the diffractive dissociation of high energy pions to two jets to study some non-perturbative light-cone wave functions of the pion. We compare the predictions for this distribution by Gaussian and Coulomb wave functions as well as the wave function derived from a solution of the light-cone Hamiltonian in the singlet model. We conclude that this experimentally measured information provides a powerful tool for these studies.
© Società Italiana di Fisica, Springer-Verlag 2003
2003
Article
http://edoc.mpg.de/63247
European Physical Journal C, v.28, 329-333 (2003)
en
oai:edoc.mpg.de:632612004-02-1337:452
Renormalization of an effective model Hamiltonian by a counterterm
expertsonly
An ill-defined integral equation for modeling the mass-spectrum of mesons is regulated with an additional but unphysical parameter. This parameter dependance is removed by renormalization. Illustrative graphical examples are given.
Published by Elsevier Science B.V
Copyright © 2002 Published by Elsevier Science B.V.
Conference-Paper
http://edoc.mpg.de/63261
Nuclear Physics B - Proceedings Supplements, 239-241
6. Effective Hamiltonians, Published by Elsevier Science B.V, 239-241
en
oai:edoc.mpg.de:632622004-02-1337:452
Renormalized QCD-inspired model for the pion and mesons
expertsonly
We apply the subtraction method to an effective QCD-inspired model, which includes the Coulomb plus a zero-range hyperfine interactions, to define a renormalized Hamiltonian for mesons. The spectrum of the renormalized Hamiltonian agrees with the one obtained with a smeared hyperfine interaction. The masses of the low-lying pseudoscalar and vector mesons are reasonably described within the model.
Published by Elsevier Science B.V
Copyright © 2002 Published by Elsevier Science B.V.
2002
Conference-Paper
http://edoc.mpg.de/63262
Nuclear Physics B - Proceedings Supplements, 234-238 (2002)
6. Effective Hamiltonians, Published by Elsevier Science B.V, 234-238 (2002)
en
oai:edoc.mpg.de:632632004-02-1337:452
On helicity and spin on the light cone
expertsonly
Starting from a one--body front--form equation with Lepage-Brodsky spinors we show, with a fair amount of new technology, how an integral equation in standard momentum space with Bjørken-Drell spinors can be obtained. The integral equation decouples for singlets and triplets.
Published by Elsevier Science B.V.
Copyright © 2002 Published by Elsevier Science B.V.
2002
Conference-Paper
http://edoc.mpg.de/63263
Nuclear Physics B - Proceedings Supplements, 251-255 (2002)
6. Effective Hamiltonians, Published by Elsevier Science B.V., 251-255 (2002)
en
oai:edoc.mpg.de:632642010-10-0237:452
Bayesian analysis of level-spacing distributions for chaotic systems with broken symmetry
expertsonly
Bayesian inference is applied to the nearest-neighbor and next-nearest-neighbor spacing distributions of levels of coupled superconducting microwave billiards. The weakly coupled resonators are equivalent to a quantum system with a partially broken symmetry. The coupling parameters are obtained with help from Bayes's theorem. This procedure does not require the introduction of a set of bins. The results are more accurate than those obtained from other bin-independent procedures.
©2002 The American Physical Society
2002
Article
http://edoc.mpg.de/63264
Physical Review e (Statistical, Nonlinear, and Soft Matter Physics), v.65, 056221-1-056221-9 (2002)
en
oai:edoc.mpg.de:632662004-02-2437:452
Observation of a Chiral State in a Microwave Cavity
Dembowski, C.
Dietz, B.
Gräf, H.-D.
Harney, H. L.
Heine, A.
Heiss, W. D.
Richter, A.
expertsonly
A microwave experiment has been realized to measure the phase difference of the oscillating electric field at two points inside the cavity. The technique has been applied to a dissipative resonator which exhibits a singularity-called exceptional point-in its eigenvalue and eigenvector spectrum. At the singularity, two modes coalesce with a phase difference of π/2. We conclude that the state excited at the singularity has a definitive chirality.
©2003 The American Physical Society
2003
Article
http://edoc.mpg.de/63266
Physical Review Letters, v.90, 034101-034101 (2003)
en
oai:edoc.mpg.de:632782004-12-3037:452
Time Reversal and Exceptional Points
Harney, H.L.
Heiss, W.D.
expertsonly
Eigenvectors of decaying quantum systems are studied at exceptional points of the Hamiltonian. Special attention is paid to the properties of the system under time reversal symmetry breaking.
At the exceptional point the chiral character of the system ---found for time reversal symmetry --- generically persists. It is,however, no longer circular but rather elliptic.
2004
Article
http://edoc.mpg.de/63278
The European Physical Journal D, v.29, 429-432 (2004)
en
oai:edoc.mpg.de:632832004-02-2437:452
Statistics of 2+ levels in even-even nuclei
Abul-Magd, A. Y.
Harney, H. L.
Weidenmüller, H. A.
expertsonly
Using all the available empirical information, we analyze the spacing distributions of low-lying 2+ levels of even-even nuclei. To obtain statistically relevant samples, the nuclei are grouped into classes defined by the ratio R4/2 of the excitation energies of the first 4+ and 2+ levels. This ratio serves as a measure of collectivity in nuclei. With the help of Bayesian inference, we determine the chaoticity parameter for each class. This parameter is found to vary strongly with R4/2 and takes particularly small values in nuclei that have one of the dynamical symmetries of the interacting boson model.
Copyright © 2003 Published by Elsevier Science B.V.
2004
Article
http://edoc.mpg.de/63283
Physics Letters B, v.579, 278-284 (2004)
en
oai:edoc.mpg.de:632852004-12-3037:452
Encircling an Exceptional Point
Dembowski, C.
Dietz, B.
Gräf, H.D.
Harney, H.L.
Heine, A.
Heiss, W.D.
Richter, A.
expertsonly
We calculate analytically the geometric phases that
the eigenvectors of a parametric dissipative two-state system described by a
complex symmetric Hamiltonian pick up
when an exceptional point (EP) is encircled. An EP is a parameter
setting where the two eigenvalues and the corresponding eigenvectors of
the Hamiltonian coalesce. We show that it can be
encircled on a path along which the eigenvectors remain approximately
real and discuss a microwave cavity experiment, where such an encircling of
an EP was realized. Since the wavefunctions remain
approximately real, they could be reconstructed
from the nodal lines of the recorded spatial intensity distributions
of the electric fields inside the resonator. We measured the geometric
phases that occur when an EP is encircled four times and thus confirmed
that for our system an EP is a branch point of fourth order.
2004
Article
http://edoc.mpg.de/63285
Physical Review E, v.69 (2004)
en
oai:edoc.mpg.de:632882004-06-1137:452
Bayesian Inference : Parameter Estimation and Decisions
Harney, Hanns Ludwig
expertsonly
The book provides a generalization of Gaussian error intervals ti situations where the data follow non-Gaussian distributions. This usually occurs in frontier science, where the observed parameter is just above background or the histogram of multiparametric data contains empty bins. Then the validity of a theory cannot be decided by the chi-squared-criterion, but this long-
Springer
Springer Verlag
2003
Book
http://edoc.mpg.de/63288
en
oai:edoc.mpg.de:633402004-03-0537:452
Statistics in 2+ levels in even-even nuclei
Abul-Magd, A. Y.
Harney, H.L.
Simbel, M.H.
Weidenmüller, H.A.
expertsonly
Elsevier
2004
Article
http://edoc.mpg.de/63340
Physics Letters B, v.579, 278-284 (2004)
en
oai:edoc.mpg.de:2076982005-02-0937:452
Observation of a Chiral State in a Microwave Cavitiy
Dembowski, C.
Dietz, B.
Gräf, H.-D.
Harney, H. L.
Heine, A.
Heiss, W. D.
Richter, A.
A microwave experiment has been realized to measure the phase difference of the oscillating electric field at two points inside the cavity. The technique has been applied to a dissipative resonator which exhibits a singularity—called exceptional point—in its eigenvalue and eigenvector spectrum. At the singularity, two modes coalesce with a phase difference of /2. We conclude that the state excited at the singularity has a definitive chirality.
©2003 The American Physical Society
2003
Article
http://edoc.mpg.de/207698
info:doi/10.1103/PhysRevLett.90.034101
Physical Review Letters, v.90, 1-4 (2003)
oai:edoc.mpg.de:2077092005-02-0837:452
Bayesian inference : parameter estimation and decisions ; with numerous examples, and 79 problems with solutions
Harney, H. L.
expertsonly
Springer Verlag
2003
Book
http://edoc.mpg.de/207709
urn:ISBN:3-540-00397-5
en
oai:edoc.mpg.de:2077102005-02-0937:452
Regularity and chaos in low-lying 2+ states of even-even nuclei
Abul-Magd, A. Y.
Harney, H. L.
Simbel, M. H.
Weidenmüller, H. A.
expertsonly
World Scientific
2004
Conference-Paper
http://edoc.mpg.de/207710
urn:ISBN:981-238-812-5
Andrea Vitturi and Richard F. Casten: Proceedings of the Highly Specialized Seminar on Symmetries in Nuclear Structure, World Scientific, 398-405 (2004)
en
oai:edoc.mpg.de:2077922005-07-0837:452
Encircling an exceptional point
Dembowski, C.
Dietz, B.
Gräf, H.-D.
Harney, H. L.
Heine, A.
Heiss, W. D.
Richter, A.
expertsonly
We calculate analytically the geometric phases that the eigenvectors of a parametric dissipative two-state system described by a complex symmetric Hamiltonian pick up when an exceptional point (EP) is encircled. An EP is a parameter setting where the two eigenvalues and the corresponding eigenvectors of the Hamiltonian coalesce. We show that it can be encircled on a path along which the eigenvectors remain approximately real and discuss a microwave cavity experiment, where such an encircling of an EP was realized. Since the wave functions remain approximately real, they could be reconstructed from the nodal lines of the recorded spatial intensity distributions of the electric fields inside the resonator. We measured the geometric phases that occur when an EP is encircled four times and thus confirmed that for our system an EP is a branch point of fourth order.
©2004 The American Physical Society
2004
Article
http://edoc.mpg.de/207792
info:doi/10.1103/PhysRevE.69.056216
Physical Review E, v.69, 1-7 (2004)
oai:edoc.mpg.de:2078042005-02-0937:452
Power-law wave functions and generalized parton distributions for the pion
Mukherjee, A.
Musatov, I. V.
Pauli, H. C.
Radyushkin, A. V.
We propose a model for generalized parton distributions of the pion based on the power-law Ansatz for the effective light-cone wave function.
©2003 The American Physical Society
2003
Article
http://edoc.mpg.de/207804
info:doi/10.1103/PhysRevD.67.073014
Physical Review D, v.67, 1-19 (2003)
oai:edoc.mpg.de:2078052005-07-0837:452
S wave meson spectra from the light cone harmonic oscillator model with a consistent hyperfine interaction
Zhou, S. G.
Pauli, H. C.
expertsonly
We use a light cone harmonic oscillator model to study S wave meson spectra, namely, the pseudoscalar and vector mesons. The model Hamiltonian is a mass squared operator consisting of a central potential (a harmonic oscillator potential) from which a hyperfine interaction is derived. The hyperfine interaction is responsible for the splitting in the pseudoscalar–vector spectra. With four parameters for the masses of up/down, strange, charm and bottom quarks, two for the harmonic oscillator potential and one for the hyperfine interaction, the model presents a reasonably good agreement with the data.
IOP PUBLISHING LTD
2004
Article
http://edoc.mpg.de/207805
info:doi/10.1088/0954-3899/30/9/003
Journal of Physics G-Nuclear & Particle Physics, v.30, 983-988 (2004)
oai:edoc.mpg.de:2078092005-02-0937:452
Experimental tests of non-perturbative pion wave functions
Ashery, D.
Pauli, H. C.
expertsonly
We use the transverse-momentum dependence of the cross section for the diffractive dissociation of high energy pions to two jets to study some non-perturbative light-cone wave functions of the pion. We compare the predictions for this distribution by Gaussian and Coulomb wave functions as well as the wave function derived from a solution of the light-cone Hamiltonian in the singlet model. We conclude that this experimentally measured information provides a powerful tool for these studies.
© Società Italiana di Fisica, Springer-Verlag 2003
2003
Article
http://edoc.mpg.de/207809
info:doi/10.1140/epjc/s2003-01187-3
European Physical Journal C, v.28, 329-333 (2003)
en
oai:edoc.mpg.de:2078102005-07-0837:452
Succesful renormalization of a QCD-inspired Hamiltonian
Pauli, H. C.
expertsonly
2004
Article
http://edoc.mpg.de/207810
European Physical Journal A, v.19, 15-22 (2004)
en
oai:edoc.mpg.de:2857062007-09-1837:452
Nuclear masses, chaos, and the residual interaction
Molinari, A.
Weidenmüller, Hans A.
expertsonly
We interpret the discrepancy between semiempirical nuclear mass formulas and actual nuclear masses in terms of the residual interaction. We show that correlations exist among all binding energies and all separation energies throughout the valley of stability. We relate our approach to chaotic motion in nuclei.
© 2006 Elsevier B.V.
2006
Article
http://edoc.mpg.de/285706
info:doi/10.1016/j.physletb.2006.04.025
Physics Letters B, v.637, 48-52 (2006)
en
oai:edoc.mpg.de:2857082007-09-1937:452
Statistical analysis of composite spectra
Abul-Magd, A. Y.
Harney, Hanns-Ludwig
Simbel, M. H.
Weidenmüller, Hans A.
expertsonly
We consider nearest-neighbor spacing distributions of composite ensembles of levels. These are obtained by combining independently unfolded sequences of levels containing only few levels each. Two problems arise in the spectral analysis of such data. One problem lies in fitting the nearest-neighbor spacing distribution to the histogram of level spacings obtained from the data. We show that the method of Bayesian inference is superior to this procedure. The second problem occurs when one unfolds such short sequences. We show that the unfolding procedure generically leads to an overestimate of the chaoticity parameter. This trend is absent in the presence of long-range level correlations. Thus, composite ensembles of levels from a system with long-range spectral stiffness yield reliable information about the chaotic behavior of the system.
© 2005 Elsevier Inc.
2006
Article
http://edoc.mpg.de/285708
info:doi/10.1016/j.aop.2005.04.005
Annals of Physics, v.321, 560-580 (2006)
en
oai:edoc.mpg.de:2857122007-09-1937:452
Two-body random ensemble in nuclei
Papenbrock, T.
Weidenmüller, Hans A.
expertsonly
Combining analytical and numerical methods, we investigate properties of the two-body random ensemble (TBRE). We compare the TBRE with the Gaussian orthogonal ensemble of random matrices. Using the geometric properties of the nuclear shell model, we discuss the information content of nuclear spectra and gain insight in the difficulties encountered when fitting the effective interaction. We exhibit the existence of correlations between spectral widths pertaining to different quantum numbers. Using these results, we deduce the preponderance of zero-spin ground states in the TBRE. We demonstrate the existence of correlations between spectra with different quantum numbers and/or in different nuclei.
©2006 The American Physical Society
2006
Article
http://edoc.mpg.de/285712
info:doi/10.1103/PhysRevC.73.014311
Physical Review C, v.73 (2006)
en
oai:edoc.mpg.de:2857292006-08-1837:452
Origin of chaos in the spherical nuclear shell model: Role of symmetries
Papenbrock, T.
Weidenmüller, Hans A.
expertsonly
To elucidate the mechanism by which chaos is generated in the shell model, we compare three random-matrix ensembles: the Gaussian orthogonal ensemble, French's two-body embedded ensemble, and the two-body random ensemble (TBRE) of the shell model. Of these, the last two take account of the two-body nature of the residual interaction, and only the last, of the existence of conserved quantum numbers like spin, isospin, and parity. While the number of independent random variables decreases drastically as we follow this sequence, the complexity of the (fixed) matrices which support the random variables, increases even more. In that sense we can say that in the TBRE, chaos is largely due to the existence of (an incomplete set of) symmetries.
© 2005 Elsevier B.V.
2005
Article
http://edoc.mpg.de/285729
info:doi/10.1016/j.nuclphysa.2005.04.018
Nuclear Physics A, v.757, 422-438 (2005)
en
oai:edoc.mpg.de:2857312006-08-1837:452
Disordered mesoscopic systems with interactions: Induced two-body ensembles and the Hartree-Fock approach
Alhassid, Y.
Weidenmüller, Hans A.
Wobst, A.
expertsonly
We introduce a generic approach to study interaction effects in diffusive or chaotic quantum dots in the Coulomb blockade regime. The randomness of the single-particle wave functions induces randomness in the two-body interaction matrix elements. We classify the possible induced two-body ensembles, both in the presence and absence of spin degrees of freedom. The ensembles depend on the underlying space-time symmetries as well as on features of the two-body interaction. Confining ourselves to spinless electrons, we then use the Hartree-Fock (HF) approximation to calculate HF single-particle energies and HF wave functions for many realizations of the ensemble. We study the statistical properties of the resulting one-body HF ensemble for a fixed number of electrons. In particular, we determine the statistics of the interaction matrix elements in the HF basis, of the HF single-particle energies (including the HF gap between the last occupied and the first empty HF level), and of the HF single-particle wave functions. We also study the addition of electrons, and in particular the distribution of the distance between successive conductance peaks and of the conductance peak heights.
Institut für Physik, Universität Augsburg, 86135 Augsburg, Germany
2005
Article
http://edoc.mpg.de/285731
info:doi/10.1103/PhysRevB.72.045318
Physical Review A, v.72 (2005)
en
oai:edoc.mpg.de:2857322006-08-1837:452
Parametric level correlations in random-matrix models
Weidenmüller, Hans A.
expertsonly
We show that parametric level correlations in random-matrix theories are closely related to a breaking of the symmetry between the advanced and the retarded Green functions. The form of the parametric level correlation function is the same as for the disordered case considered earlier by Simons and Altshuler and is given by the graded trace of the commutator of the saddle-point solution with the particular matrix that describes the symmetry breaking in the actual case of interest. The strength factor differs from the case of disorder. It is determined solely by the Goldstone mode. It is essentially given by the number of levels that are strongly mixed as the external parameter changes. The factor can easily be estimated in applications.
© Institute of Physics and IOP Publishing Limited 2006
2005
Article
http://edoc.mpg.de/285732
info:doi/10.1088/0953-8984/17/20/015
Journal of Physics: Condensed Matter, v.17, S1881-S1887 (2005)
en
oai:edoc.mpg.de:2857332006-08-1837:452
Kondo temperature for a quantum dot in an Aharonov-Bohm ring
Lewenkopf, C. H.
Weidenmüller, Hans A.
expertsonly
We study the Kondo temperature of a quantum dot embedded into one arm of an Aharonov-Bohm interferometer. The topology of a disordered or chaotic Aharonov-Bohm ring leads to a stochastic term in the scaling equation and in the renormalization procedure. As a result, the Kondo temperature displays significant fluctuations as a function of magnetic flux.
©2005 The American Physical Society
2005
Article
http://edoc.mpg.de/285733
info:doi/10.1103/PhysRevB.71.121309
Physical Review B, v.71 (2005)
en
oai:edoc.mpg.de:2857342006-08-1837:452
Persistent currents in n-fold twisted Moebius strips
Martins Ferreira, E. H.
Nemes, M. C.
Sampaio, M. D.
Weidenmüller, Hans A.
expertsonly
We investigate the influence of the topology on generic features of the persistent current in n-fold twisted Moebius strips formed of quasi one-dimensional mesoscopic rings, both for free electrons and in the weakly disordered regime. We find that there is no generic difference between the persistent current for untwisted rings and for Moebius strips with an arbitrary number of twists.
© 2004 Elsevier B.V.
2004
Article
http://edoc.mpg.de/285734
info:doi/10.1016/j.physleta.2004.10.026
Physics Letters A, v.333, 146-151 (2004)
en
oai:edoc.mpg.de:2857352006-08-1837:452
Statistical fluctuations of ground-state energies and binding energies in nuclei
Molinari, A.
Weidenmüller, Hans A.
expertsonly
The statistical fluctuations of the ground-state energy and of the binding energy of nuclei are investigated using both perturbation theory and supersymmetry. The fluctuations are induced by the experimentally observed stochastic behavior of levels in the vicinity of neutron threshold. The results are compared with a recent analysis of binding-energy fluctuations by Bohigas and Leboeuf, and with theoretical work by Feshbach et al.
© 2004 Elsevier B.V.
2004
Article
http://edoc.mpg.de/285735
info:doi/10.1016/j.physletb.2004.09.042
Physics Letters B, v.601, 119-124 (2004)
en
oai:edoc.mpg.de:2857362006-08-1837:452
Distribution of Spectral Widths and Preponderance of Spin-0 Ground States in Nuclei
Papenbrock, T.
Weidenmüller, Hans A.
expertsonly
We use a single j-shell model with random two-body interactions to derive closed expressions for the distribution of and the correlations between spectral widths of different spins. This task is facilitated by introducing two-body operators whose squared spectral widths sum up to the squared spectral width of the random Hamiltonian. The spin-0 width is characterized by a relatively large average value and small fluctuations, while the width of maximum spin has the largest average and the largest fluctuations. The approximate proportionality between widths and spectral radii explains the preponderance of spin-0 ground states.
©2004 The American Physical Society
2004
Article
http://edoc.mpg.de/285736
info:doi/10.1103/PhysRevLett.93.132503
Physical Review Letters, v.93 (2004)
en
oai:edoc.mpg.de:3416082010-09-2937:452
Interaction of regular and chaotic states
De Pace, A.
Molinari, A.
Weidenmüller, Hans A.
expertsonly
2007
Article
http://edoc.mpg.de/341608
urn:ISSN:0003-4916
Annals of Physics, v.322, 2446-2468 (2007)
en
oai:edoc.mpg.de:3416122010-09-2937:452
Colloquium: Random matrices and chaos in nuclear spectra
Papenbrock, T.
Weidenmüller, Hans A.
notspecified
2007
Article
http://edoc.mpg.de/341612
urn:ISSN:0034-6861
Reviews of Modern Physics, v.79, 997-1013 (2007)
en
oai:edoc.mpg.de:3416172008-03-1537:452
Induced time-reversal symmetry breaking observed in microwave billiards
Dietz, B.
Friedrich, T.
Harney, H. L.
Miski-Oglu, M.
Richter, A.
Schafer, F.
Weidenmüller, H. A.
expertsonly
2007
Article
http://edoc.mpg.de/341617
urn:ISSN:0031-9007
Physical Review Letters, v.98 (2007)
en
oai:edoc.mpg.de:3944792008-11-2937:452
Scrambling of Hartree-Fock levels as a universal Brownian-motion process
Alhassid, Y.
Weidenmüller, H. A.
Wobst, A.
expertsonly
2007
Article
http://edoc.mpg.de/394479
urn:ISSN:1098-0121
Physical Review B, v.76 (2007)
en
oai:edoc.mpg.de:3944802011-05-1337:452
Statistical theory of compound-nuclear reactions
Weidenmüller, H. A.
expertsonly
American Institute of Physics
2008
Conference-Paper
http://edoc.mpg.de/394480
urn:ISSN:0094-243X
COMPOUND-NUCLEAR REACTIONS AND RELATED TOPICS: Proceedings of the 2007 International Workshop on Compound-Nuclear Reactions and Related Topics - CNR* 2007, American Institute of Physics, 3-9 (2008)
en
ResultSet_0S2KIDGO24c_range_100-112