Parton energy loss in heavy-ion collisions via direct-photon and charged-particle azimuthal correlations
Author(s)Balewski, Jan T.; Betancourt, Michael Joseph; Corliss, Ross Cameron; Hoffman, A. M.; Jones, Christopher LaDon; Kocoloski, Adam Philip; Leight, William Axel; Milner, Richard G.; Redwine, Robert P.; Sakuma, Tai; Surrow, Bernd; van Nieuwenhuizen, Gerrit Jan; Walker, Matthew H.; ... Show more Show less
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Charged-particle spectra associated with direct photon (γdir) and pi0 are measured in p+p and Au+Au collisions at center-of-mass energy [sqrt]sNN=200 GeV with the STAR detector at the Relativistic Heavy Ion Collider. A shower-shape analysis is used to partially discriminate between γdir and pi0. Assuming no associated charged particles in the γdir direction (near side) and small contribution from fragmentation photons (γfrag), the associated charged-particle yields opposite to γdir (away side) are extracted. In central Au+Au collisions, the charged-particle yields at midrapidity (|η|<1) and high transverse momentum (3<pT[superscript assoc]<16 GeV/c) associated with γdir and pi0 (|η|<0.9, 8<pT[superscript 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 is similar for γdir and pi0 and independent of the γdir energy within uncertainties. These measurements indicate that, in the kinematic range covered and within our current experimental uncertainties, the parton energy loss shows no sensitivity to the parton initial energy, path length, or color charge.
DepartmentMassachusetts Institute of Technology. Department of Physics; Massachusetts Institute of Technology. Laboratory for Nuclear Science
Physical Review C
American Physical Society
STAR Collaboration et al. “Parton energy loss in heavy-ion collisions via direct-photon and charged-particle azimuthal correlations.” Physical Review C 82.3 (2010): 034909. © 2010 The American Physical Society.
Final published version