This paper presents a measurement of b-jet production in Pb+Pb and pp collisions at √sNN = 5.02 TeV with the ATLAS detector at the LHC. The measurement uses 260 pb−1 of pp collisions collected in 2017 and 1.4 nb−1 of Pb+Pb collisions collected in 2018. In both collision systems, jets are reconstructed via the anti-kt 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 nb−1 of Pb+Pb collisions collected in 2018 and the same pp collision data as the b-jet measurement. The nuclear modification factor, RAA, 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 RAA to inclusive jet RAA is also presented and suggests that the RAA 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.

Aad G., Abbott B., Abbott D.C., Abeling K., Abidi S.H., Aboulhorma A., et al. (2023). Measurement of the nuclear modification factor of b-jets in 5.02 TeV Pb+Pb collisions with the ATLAS detector. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS, 83(5), 1-32 [10.1140/epjc/s10052-023-11427-9].

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

Alberghi G. L.;Alfonsi F.;Bindi M.;Boscherini D.;Cabras G.;Carratta G.;Clissa L.;De Castro S.;Fabbri F.;Fabbri L.;Franchini M.;Gabrielli A.;Massa L.;Polini A.;