Dergi makalesi Açık Erişim

Measurement of the nuclear modification factor of b-jets in 5.02 TeV Pb+Pb collisions with the ATLAS detector

2023    CERN İşbirliği

This paper presents a measurement of b-jet production in Pb+Pb and pp collisions at $\sqrt{{s}_{{}_{\text{NN}}}}=5.02$ TeV with the ATLAS detector at the LHC. The measurement uses 260 ${\text{pb}}^{-1}$ of pp collisions collected in 2017 and 1.4 ${\text{nb}}^{-1}$ of Pb+Pb collisions collected in 2018. In both collision systems, jets are reconstructed via the anti- ${k}_{t}$ algorithm. The b-jets are identified from a sample of jets containing muons from the semileptonic decay of b-quarks using template fits of the muon momentum relative to the jet axis. In pp collisions, b-jets are reconstructed for radius parameters $R=0.2$ and $R=0.4$ , and only $R=0.2$ jets are used in Pb+Pb collisions. For comparison, inclusive $R=0.2$ jets are also measured using 1.7 ${\text{nb}}^{-1}$ of Pb+Pb collisions collected in 2018 and the same pp collision data as the b-jet measurement. The nuclear modification factor, ${R}_{\text{AA}}$ , is calculated for both b-jets and inclusive jets with $R=0.2$ over the transverse momentum range of 80–290 GeV. The nuclear modification factor for b-jets decreases from peripheral to central collisions. The ratio of the b-jet ${R}_{\text{AA}}$ to inclusive jet ${R}_{\text{AA}}$ is also presented and suggests that the ${R}_{\text{AA}}$ for b-jets is larger than that for inclusive jets in central Pb+Pb collisions. The measurements are compared with theoretical calculations and suggest a role for mass and colour-charge effects in partonic energy loss in heavy-ion collisions.