Measurement of direct photons in Au+Au collisions at √s NN=200GeV

S. Afanasiev, C. Aidala, N. N. Ajitanand, Y. Akiba, A. Al-Jamel, J. Alexander, K. Aoki, L. Aphecetche, R. Armendariz, S. H. Aronson, R. Averbeck, T. C. Awes, B. Azmoun, V. Babintsev, A. Baldisseri, K. N. Barish, P. D. Barnes, B. Bassalleck, S. Bathe, Awadhesh Kumar DubeyMihael Makek, Alexander Milov, Deepali Sharma, Itzhak Tserruya

Research output: Contribution to journalArticlepeer-review

Abstract

We report the measurement of direct photons at midrapidity in Au+Au collisions at √s NN=200GeV. The direct photon signal was extracted for the transverse momentum range of 4GeV/c<p T<22GeV/ c, using a statistical method to subtract decay photons from the inclusive photon sample. The direct photon nuclear modification factor R AA was calculated as a function of p T for different Au+Au collision centralities using the measured p+p direct photon spectrum and compared to theoretical predictions. R AA was found to be consistent with unity for all centralities over the entire measured p T range. Theoretical models that account for modifications of initial direct photon production due to modified parton distribution functions in Au and the different isospin composition of the nuclei predict a modest change of R AA from unity. They are consistent with the data. Models with compensating effects of the quark-gluon plasma on high-energy photons, such as suppression of jet-fragmentation photons and induced-photon bremsstrahlung from partons traversing the medium, are also consistent with this measurement.

Original languageEnglish
Article number152302
JournalPhysical review letters
Volume109
Issue number15
DOIs
StatePublished - 9 Oct 2012

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy

Fingerprint

Dive into the research topics of 'Measurement of direct photons in Au+Au collisions at √s NN=200GeV'. Together they form a unique fingerprint.

Cite this