Near-side jet peak broadening in Pb–Pb collisions at [formula omitted

Abstract

Two-particle angular correlation measurements are sensitive probes of the interactions of particles with the medium formed in heavy-ion collisions. Such measurements are done by determining the distribution of the relative pseudo-rapidity (Δη) and azimuthal angle (Δϕ) of particles with respect to a higher pT trigger particle (1<pT,trig<8 GeV/c). The near-side peak is fitted with a function, which includes both the near-side jet peak and also accounts for the Δη-independent long-range correlations. The centrality evolution of the width (variance) of the fitted distribution is investigated. In Pb–Pb collisions a significant broadening of the near-side peak in the Δη direction is observed from peripheral to central collisions, while in the Δφ direction the peak is almost independent of centrality. For the 10% most central events, a departure from the Gaussian shape is also observed at low transverse momentum (1<pT,assoc<2 GeV/c,1<pT,trig<3 GeV/c). In this contribution the results obtained by the ALICE experiment in Pb–Pb and pp collisions at sNN=2.76 TeV are shown, and they are interpreted in terms of radial and elliptic flow by comparing them to AMPT model simulations.