Event activity-dependence of jet production in p-Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV measured with semi-inclusive hadron+jet correlations by ALICE

Abstract

We report measurement of the semi-inclusive distribution of charged-particle jets recoiling from a high transverse momentum ($p_{\rm T}$) hadron trigger, for p-Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV, in p-Pb events classified by event activity. This observable has been measured in pp and Pb-Pb collisions at the LHC, providing a new probe to measure quenching. Jets are reconstructed from charged particle tracks using anti-$k_{\rm t}$ with $R = 0.4$ and low IR cutoff of jet constituents ($p_{\rm T,track} > 0.15$ GeV/$c$). The complex uncorrelated jet background is corrected by a data-driven approach. Recoil jet distributions are reported for $15 < p_{\rm T,jet}^{\rm ch} < 50$ GeV/$c$. Events are classified by signal in the ALICE V0A detector, which measures forward multiplicity, and ZNA, which measures the number of neutrons at zero degrees. This self-normalized observable does not require scaling of reference distributions by $T_{\rm pA}$ , thereby avoiding the need for geometric modeling. We compare the trigger-normalized recoil jet yield for p-Pb collisions with different event activity to measure the effects of jet quenching in small systems at the LHC.