skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Photon-hadron jet correlations in p+p and Au+Au collisions at {radical}(s{sub NN})=200 GeV

Abstract

We report the observation at the Relativistic Heavy Ion Collider of suppression of back-to-back correlations in the direct photon+jet channel in Au+Au relative to p+p collisions. Two-particle correlations of direct photon triggers with associated hadrons are obtained by statistical subtraction of the decay photon-hadron ({gamma}-h) background. The initial momentum of the away-side parton is tightly constrained, because the parton-photon pair exactly balance in momentum at leading order in perturbative quantum chromodynamics, making such correlations a powerful probe of the in-medium parton energy loss. The away-side nuclear suppression factor, I{sub AA}, in central Au+Au collisions, is 0.32{+-}0.12{sup stat}{+-}0.09{sup syst} for hadrons of 3<p{sub T}{sup h}<5 in coincidence with photons of 5<p{sub T}{sup {gamma}}<15 GeV/c. The suppression is comparable to that observed for high-p{sub T} single hadrons and dihadrons. The direct photon associated yields in p+p collisions scale approximately with the momentum balance, z{sub T}{identical_to}p{sub T}{sup h}/p{sub T}{sup {gamma}}, as expected for a measurement of the away-side parton fragmentation function. We compare to Au+Au collisions for which the momentum balance dependence of the nuclear modification should be sensitive to the path-length dependence of parton energy loss.

Authors:
; ; ; ; ; ; ; ;  [1]; ; ; ; ; ; ;  [2];  [3]; ; ;  [4]
  1. University of Colorado, Boulder, Colorado 80309 (United States)
  2. Joint Institute for Nuclear Research, RU-141980 Dubna, Moscow Region (Russian Federation)
  3. Columbia University, New York, NY 10027 and Nevis Laboratories, Irvington, New York 10533 (United States)
  4. Chemistry Department, Stony Brook University, Stony Brook, SUNY, New York 11794-3400 (United States)
Publication Date:
OSTI Identifier:
21290077
Resource Type:
Journal Article
Journal Name:
Physical Review. C, Nuclear Physics
Additional Journal Information:
Journal Volume: 80; Journal Issue: 2; Other Information: DOI: 10.1103/PhysRevC.80.024908; (c) 2009 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0556-2813
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; ATOM-ATOM COLLISIONS; BALANCES; BROOKHAVEN RHIC; COLLISIONS; COMPARATIVE EVALUATIONS; CORRELATIONS; ENERGY LOSSES; FRAGMENTATION; GEV RANGE; GOLD; HADRONS; MODIFICATIONS; NUCLEAR DECAY; PHOTONS; PROTON-PROTON INTERACTIONS; QUANTUM CHROMODYNAMICS

Citation Formats

Adare, A, Bickley, A A, Ellinghaus, F, Kelly, S, Kinney, E, Kiriluk, K, Nagle, J L, Seele, J, Wysocki, M, Afanasiev, S, Isupov, A, Litvinenko, A, Malakhov, A, Peresedov, V, Rukoyatkin, P, Zolin, L, Aidala, C, Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003-9337, Ajitanand, N N, Alexander, J, and Chung, P. Photon-hadron jet correlations in p+p and Au+Au collisions at {radical}(s{sub NN})=200 GeV. United States: N. p., 2009. Web. doi:10.1103/PHYSREVC.80.024908.
Adare, A, Bickley, A A, Ellinghaus, F, Kelly, S, Kinney, E, Kiriluk, K, Nagle, J L, Seele, J, Wysocki, M, Afanasiev, S, Isupov, A, Litvinenko, A, Malakhov, A, Peresedov, V, Rukoyatkin, P, Zolin, L, Aidala, C, Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003-9337, Ajitanand, N N, Alexander, J, & Chung, P. Photon-hadron jet correlations in p+p and Au+Au collisions at {radical}(s{sub NN})=200 GeV. United States. https://doi.org/10.1103/PHYSREVC.80.024908
Adare, A, Bickley, A A, Ellinghaus, F, Kelly, S, Kinney, E, Kiriluk, K, Nagle, J L, Seele, J, Wysocki, M, Afanasiev, S, Isupov, A, Litvinenko, A, Malakhov, A, Peresedov, V, Rukoyatkin, P, Zolin, L, Aidala, C, Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003-9337, Ajitanand, N N, Alexander, J, and Chung, P. Sat . "Photon-hadron jet correlations in p+p and Au+Au collisions at {radical}(s{sub NN})=200 GeV". United States. https://doi.org/10.1103/PHYSREVC.80.024908.
@article{osti_21290077,
title = {Photon-hadron jet correlations in p+p and Au+Au collisions at {radical}(s{sub NN})=200 GeV},
author = {Adare, A and Bickley, A A and Ellinghaus, F and Kelly, S and Kinney, E and Kiriluk, K and Nagle, J L and Seele, J and Wysocki, M and Afanasiev, S and Isupov, A and Litvinenko, A and Malakhov, A and Peresedov, V and Rukoyatkin, P and Zolin, L and Aidala, C and Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003-9337 and Ajitanand, N N and Alexander, J and Chung, P},
abstractNote = {We report the observation at the Relativistic Heavy Ion Collider of suppression of back-to-back correlations in the direct photon+jet channel in Au+Au relative to p+p collisions. Two-particle correlations of direct photon triggers with associated hadrons are obtained by statistical subtraction of the decay photon-hadron ({gamma}-h) background. The initial momentum of the away-side parton is tightly constrained, because the parton-photon pair exactly balance in momentum at leading order in perturbative quantum chromodynamics, making such correlations a powerful probe of the in-medium parton energy loss. The away-side nuclear suppression factor, I{sub AA}, in central Au+Au collisions, is 0.32{+-}0.12{sup stat}{+-}0.09{sup syst} for hadrons of 3<p{sub T}{sup h}<5 in coincidence with photons of 5<p{sub T}{sup {gamma}}<15 GeV/c. The suppression is comparable to that observed for high-p{sub T} single hadrons and dihadrons. The direct photon associated yields in p+p collisions scale approximately with the momentum balance, z{sub T}{identical_to}p{sub T}{sup h}/p{sub T}{sup {gamma}}, as expected for a measurement of the away-side parton fragmentation function. We compare to Au+Au collisions for which the momentum balance dependence of the nuclear modification should be sensitive to the path-length dependence of parton energy loss.},
doi = {10.1103/PHYSREVC.80.024908},
url = {https://www.osti.gov/biblio/21290077}, journal = {Physical Review. C, Nuclear Physics},
issn = {0556-2813},
number = 2,
volume = 80,
place = {United States},
year = {2009},
month = {8}
}