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 𝑝T) charged hadron, in 𝑝⁢𝑝 and central Pb-Pb collisions at center-of-mass energy per nucleon–nucleon collision √𝑠NN=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 𝑝T,chjet and jet resolution parameter 𝑅. Recoil jet yields are reported for 𝑅=0.2, 0.4, and 0.5 in the range 7<𝑝T,chjet<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-𝑝T,chjet 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 𝑝T,chjet 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.