Measurement of the nuclear modification factor for inclusive jets in Pb+Pb collisions at $\sqrt{s_\mathrm{NN}}=5.02$ TeV with the ATLAS detector

TL;DR

This paper measures how jet production is suppressed in lead-lead collisions at 5.02 TeV compared to proton-proton collisions, revealing the effects of quark-gluon plasma on high-energy jets.

Contribution

It provides the first detailed measurement of the nuclear modification factor for inclusive jets at 5.02 TeV with ATLAS, across various momenta and rapidities.

Findings

Jet suppression increases with transverse momentum, reaching about 0.6 at 1 TeV in central collisions.

Suppression is less in peripheral collisions, indicating medium effects.

R_AA is independent of rapidity at low momenta but decreases at high momenta with increasing rapidity.

Abstract

Measurements of the yield and nuclear modification factor, $R_\mathrm{ AA}$, for inclusive jet production are performed using 0.49 nb$^{-1}$ of Pb+Pb data at $\sqrt{s_\mathrm{NN}} = 5.02$ TeV and 25 pb$^{-1}$ of $pp$ data at $\sqrt{s}=5.02$ TeV with the ATLAS detector at the LHC. Jets are reconstructed with the anti-$k_t$ algorithm with radius parameter $R=0.4$ and are measured over the transverse momentum range of 40-1000 GeV in six rapidity intervals covering $|y|<2.8$. The magnitude of $R_\mathrm{ AA}$ increases with increasing jet transverse momentum, reaching a value of approximately 0.6 at 1 TeV in the most central collisions. The magnitude of $R_\mathrm{ AA}$ also increases towards peripheral collisions. The value of $R_\mathrm{ AA}$ is independent of rapidity at low jet transverse momenta, but it is observed to decrease with increasing rapidity at high transverse momenta.