Comparison of inclusive and photon-tagged jet suppression in 5.02 TeV Pb+Pb collisions with ATLAS

ATLAS Publications, J.F. Allen, D. Duda, J.M. Gargan, R.Y. Gonzalez Andana, A. Hasib, V.A. Parrish, E.A. Pender, N. Themistokleous, E.M. Villhauer, Z. Xu, E. Zaid

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

Parton energy loss in the quark–gluon plasma (QGP) is studied with a measurement of photon-tagged jet production in 1.7 nb−1 of Pb+Pb data and 260 pb−1 of pp data, both at √sNN = 5.02 TeV, with the ATLAS detector. The process pp → γ +jet+X and its analogue in Pb+Pb collisions is measured in
events containing an isolated photon with transverse momentum (pT ) above 50 GeV and reported as a function of jet pT . This selection results in a sample of jets with a steeply falling pT distribution that are mostly initiated by the showering of quarks. The pp and Pb+Pb measurements are used to report the
nuclear modification factor, RAA , and the fractional energy loss, Sloss , for photon-tagged jets. In addition, the results are compared with the analogous ones for inclusive jets, which have a significantly smaller quark-initiated fraction. The RAA and Sloss values are found to be significantly different between those for photon-tagged jets and inclusive jets, demonstrating that energy loss in the QGP is sensitive to the colour-charge of the initiating parton. The results are also compared with a variety of theoretical models of colour-charge-dependent energy loss.
Original languageEnglish
Article number138154
Pages (from-to)1-27
Number of pages27
JournalPhysics Letters B
Early online date29 Aug 2023
Publication statusPublished - 10 Nov 2023


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