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 pp 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,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 < pT,ch jet < 140 GeV/c and π/2 < φ < π, where φ is the
azimuthal angular separation between hadron trigger and recoil jet. The low-pT,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 pT,ch jet distributions from pp and central Pb-Pb
collisions probes medium-induced jet energy loss and intra-jet broadening, while comparison of their acopla-
narity distributions explores in-medium jet scattering and medium response. The measurements are compared to
theoretical calculations incorporating jet quenching.
