Interplaying mechanisms behind inclusive jet $R_{AA}$ and extraction of jet energy loss distributions

Abstract

The observed inclusive jet suppression in heavy-ion collisions at LHC has a very weak $p_{T}$ dependence over a large range of $p_{T}$ = 50-1000 GeV and is almost independent of the colliding energy, though the initial energy density of the bulk medium has increased from $\sqrt{s}$ = 2.76 to 5.02 TeV by about 20%. This interesting phenomenon is investigated in the linear Boltzmann transport (LBT) model for jet propagation in an event-by-event 3+1D hydro background. We show that the $p_{T}$ dependence of jet $R_{AA}$ is determined by the initial spectrum in $p+p$ collisions and $ p_{T} $ dependence of jet energy loss. Furthermore, jet energy loss distributions for inclusive jet and $ γ-$jet at both LHC energies are extracted directly from experimental data through the state-of-art Bayesian analysis. The averaged jet energy loss has a weak $p_{T}$ dependence and the scaled jet energy loss distributions have a large width, both of which are consistent with the LBT simulations and indicate that jet quenching is caused by only a few out-of-cone jet medium scatterings.