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

Abstract

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 $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV, with the ATLAS detector. The process $pp\to \gamma$+jet+$X$ and its analogue in Pb+Pb collisions is measured in events containing an isolated photon with transverse momentum ($p_{\mathrm{T}}$) above $50$ GeV and reported as a function of jet $p_{\mathrm{T}}$. This selection results in a sample of jets with a steeply falling $p_{\mathrm{T}}$ distribution that are mostly initiated by the showering of quarks. The $pp$ and Pb+Pb measurements are used to report the nuclear modification factor, $R_{\mathrm{AA}}$, and the fractional energy loss, $S_{\mathrm{loss}}$, 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 $R_{\mathrm{AA}}$ and $S_{\mathrm{loss}}$ 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.

42 pages in total, author list starting page 25, 9 figures, published in Phys. Lett. B. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2022-14/

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Cited by in corpus (6)

• Overview of high-density QCD studies with the CMS experiment at the LHC
• Search for the jet-induced diffusion wake in the quark-gluon plasma via measurements of jet-track correlations in photon-jet events in Pb+Pb collisions at $\sqrt{{\mathrm{s}}_{\mathrm{NN}}}$ = 5.02 TeV with the ATLAS detector
• Flavor and path-length dependence of jet quenching from inclusive jet and γ-jet suppression
• Deriving a parton shower for jet thermalization in QCD plasmas
• Constraining color-charge effects of partonic energy loss with jet axis-based inclusive jet substructure measurement
• Contrasting Features of Parton Energy Loss in Heavy-ion Collisions at RHIC and the LHC