Event by event di-hadron correlations in Pb-Pb 2.76 TeV collisions from the ALICE experiment

Abstract

The large multiplicities at the LHC may permit flow harmonics to be determined on an event by event basis in Pb-Pb collisions. We extract these harmonics from event by event di-hadron correlations. Within a fine centrality bin, we find the correlation function varies substantially on an event by event basis, indicating large fluctuations in the initial conditions for a given impact parameter. Such large fluctuations lead to some events being highly triangular or highly elliptical, where the angular correlation function is completely dominated by the respective second and third Fourier harmonics. We will show unfolded $v_{2}$ distributions for various centralities, and implications for our understanding of the initial conditions.