Fluctuations in relativistic heavy-ion collisions from the Glauber models

TL;DR

This paper investigates how initial state fluctuations and nucleon correlations affect observable signatures in relativistic heavy-ion collisions, showing that size fluctuations significantly influence transverse momentum fluctuations.

Contribution

It demonstrates that initial size fluctuations can explain the observed event-by-event transverse momentum fluctuations in heavy-ion collisions.

Findings

Nucleon-nucleon correlations affect particle number fluctuations.

Size fluctuations lead to transverse flow velocity fluctuations.

Transverse momentum fluctuations can be explained by initial size variations.

Abstract

In the first part of the talk we discuss the role of the two-body nucleon-nucleon correlations on signatures of the heavy-ion collisions which are a priori expected to be sensitive to these effects. We find that while the fluctuations of the number of produced particles are indeed affected, other quantities (v_2 fluctuations, size fluctuations) are insensitive to the presence of the NN correlations in the nucleon distributions. In the second part we show that the fluctuations of the transverse size of the initial source cause, after a suitable hydrodynamic evolution, fluctuations of the transverse flow velocity at hadronic freeze-out. This in turn yields the event-by-event fluctuations of the transverse momentum of the produced particles, p_T. Our results demonstrate that practically all of the observed event-by-event p_T fluctuations may be explained this way.