Measurements of jet quenching using semi-inclusive hadron+jet distributions in pp and central Pb-Pb collisions at sNN =5.02 TeV

Abstract

The ALICE Collaboration reports measurements of the semi-inclusive distribution of charged-particle jets recoiling from a high transverse momentum (high p T ) charged hadron, in p p and central Pb-Pb collisions at center-of-mass energy per nucleon–nucleon collision s NN = 5.02 TeV. The large uncorrelated background in central Pb-Pb collisions is corrected using a data-driven statistical approach which enables precise measurement of recoil jet distributions over a broad range in p T , ch jet and jet resolution parameter R . Recoil jet yields are reported for R = 0.2 , 0.4, and 0.5 in the range 7 p T , ch jet 140 GeV / c and π / 2 Δ φ π , where Δ φ is the azimuthal angular separation between hadron trigger and recoil jet. The low- p T , ch jet reach of the measurement explores unique phase space for studying jet quenching, the interaction of jets with the quark–gluon plasma generated in high-energy nuclear collisions. Comparison of p T , ch jet distributions from p p and central Pb-Pb collisions probes medium-induced jet energy loss and intra-jet broadening, while comparison of their acoplanarity distributions explores in-medium jet scattering and medium response. The measurements are compared to theoretical calculations incorporating jet quenching. ©2024 CERN, for the ALICE Collaboration 2024 CERN