The production of isolated photons in PbPb and pp collisions at sNN$$ \sqrt{s_{\mathrm{NN}}} $$ = 5.02 TeV
Author(s)
Sirunyan, A. M; Tumasyan, A.; Adam, W.; Ambrogi, F.; Bergauer, T.; Dragicevic, M.; Erö, J.; Escalante Del Valle, A.; Flechl, M.; Frühwirth, R.; Jeitler, M.; Krammer, N.; Krätschmer, I.; Liko, D.; Madlener, T.; Mikulec, I.; Rad, N.; ... Show more Show less
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Abstract
The transverse energy (
E
T
γ
$$ {E}_{\mathrm{T}}^{\upgamma} $$
) spectra of photons isolated from other particles are measured using proton-proton (pp) and lead-lead (PbPb) collisions at the LHC at
s
NN
$$ \sqrt{s_{\mathrm{NN}}} $$
= 5.02 TeV with integrated luminosities of 27.4 pb−1 and 404 μb−1 for pp and PbPb data, respectively. The results are presented for photons with 25 <
E
T
γ
$$ {E}_{\mathrm{T}}^{\upgamma} $$
< 200 GeV in the pseudorapidity range |η| < 1.44, and for different centrality intervals for PbPb collisions. Photon production in PbPb collisions is consistent with that in pp collisions scaled by the number of binary nucleon-nucleon collisions, demonstrating that photons do not interact with the quark-gluon plasma. Therefore, isolated photons can provide information about the initial energy of the associated parton in photon+jet measurements. The results are compared with predictions from the next-to-leading-order jetphox generator for different parton distribution functions (PDFs) and nuclear PDFs (nPDFs). The comparisons can help to constrain the nPDFs global fits.
Date issued
2020-07-17Department
Massachusetts Institute of Technology. Department of PhysicsPublisher
Springer Berlin Heidelberg
Citation
Journal of High Energy Physics. 2020 Jul 17;2020(7):116
Version: Final published version