Parton energy loss in heavy-ion collisions via direct-photon and charged-particle azimuthal correlations
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. Ass...
| Main Authors: | , , , , , , , , , , , , |
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| Other Authors: | |
| Format: | Article |
| Language: | en_US |
| Published: |
American Physical Society
2011
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| Online Access: | http://hdl.handle.net/1721.1/60666 https://orcid.org/0000-0002-5515-4563 https://orcid.org/0000-0001-5839-707X https://orcid.org/0000-0002-0031-1963 https://orcid.org/0000-0002-9107-6312 |
| Summary: | 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. |
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