Constraints on jet quenching in p\u2013Pb collisions at 1asNN = 5.02\u2009TeV measured by the event-activity dependence of semi-inclusive hadron-jet distributions
The ALICE Collaboration reports the measurement of semi-inclusive distributions of charged-particle jets recoiling from a high-transverse momentum trigger hadron in p\u2013Pb collisions at 1asNN = 5.02 TeV. Jets are reconstructed from charged-particle tracks using the anti-kT algorithm with resolution parameter R = 0.2 and 0.4. A data-driven statistical approach is used to correct the uncorrelated background jet yield. Recoil jet distributions are reported for jet transverse momentum 15 < pch < 50 GeV/c and are compared in T,jet various intervals of p\u2013Pb event activity, based on charged-particle multiplicity and zero-degree neutral energy in the forward (Pb-going) direction. The semi-inclusive observable is self-normalized and such comparisons do not require the interpretation of p\u2013Pb event activity in terms of collision geometry, in contrast to inclusive jet observables. These measurements provide new constraints on the magnitude of jet quenching in small systems at the LHC. In p\u2013Pb collisions with high event activity, the average
medium-induced out-of-cone energy transport for jets with R = 0.4 and 15 < pch < 50 GeV/c is T,jet measured to be less than 0.4 GeV/c at 90% confidence, which is over an order of magnitude smaller than a similar measurement for central Pb\u2013Pb collisions at 1asNN =2.76TeV. Comparison is made to theoretical calculations of jet quenching in small systems, and to inclusive jet measurements in p\u2013Pb collisions selected by event activity at the LHC and in d\u2013Au collisions at RHIC
