Speaker
Prof.
Jean-Yves Ollitrault
(IPhT Saclay)
Description
The ATLAS collaboration has analyzed event-to-event fluctuations of the transverse momentum per particle as a function of the particle multiplicity. In the most central collisions, the variance of fluctuations decreases steeply. I show that this can be explained simply, provided that one takes into account two combined effects: First, for a fixed collision multiplicity, the impact parameter spans a range of values. Second, still for fixed multiplicity, the momentum per particle increases as a function of impact parameter. Based on this analysis, I derive accurate predictions for the increase of the mean transverse momentum in ultracentral collisions, which is yet unobserved.
