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 Institute: MPI für Physik     Collection: MPI für Physik     Display Documents

ID: 544632.0, MPI für Physik / MPI für Physik
Parton Energy Loss in Heavy-Ion Collisions via Direct-Photon and Charged-Particle Azimuthal Correlations
Authors:
Date of Publication (YYYY-MM-DD):2010
Title of Journal:Physical Review C
Journal Abbrev.:Phys.Rev.C
Issue / Number:82
Start Page:034909
Audience:Not Specified
Intended Educational Use:No
Abstract / Description:Charged-particle spectra associated with direct photon ($\gamma_{dir}$) and $\pi^0$ are measured in $p$+$p$ and Au+Au collisions at center-of-mass energy $\sqrt{s_{_{NN}}}=200$ GeV with the STAR detector at RHIC. A hower-shape analysis is used to partially discriminate between $\gamma_{dir}$ and $\pi^0$. Assuming no associated charged particles in the $\gamma_{dir}$ direction (near side) and small contribution from fragmentation photons ($\gamma_{frag}$), the associated charged-particle yields opposite to $\gamma_{dir}$ (away side) are extracted. At mid-rapidity ($|\eta|<0.9$) in central Au+Au collisions, charged-particle yields associated with $\gamma_{dir}$ and $\pi^0$ at high transverse momentum ($8< p_{T}^{trig}<16$ GeV/$c$) are suppressed by a factor of 3-5 compared with $p$ + $p$ collisions. The observed suppression of the associated charged particles, in the kinematic range $|\eta|<1$ and $3< p_{T}^{assoc} < 16$ GeV/$c$, is similar for $\gamma_{dir}$ and $\pi^0$, and independent of the $\gamma_{dir}$ energy within uncertainties. These measurements indicate that the parton energy loss, in the covered kinematic range, is insensitive to the parton path length.
Classification / Thesaurus:STAR
Comment of the Author/Creator:submitted to Phys. Rev. Lett, 6 pages, 4 figures
External Publication Status:published
Document Type:Article
Communicated by:N.N.
Affiliations:
Identifiers:
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