A unified description of the reaction dynamics from pp to pA to AA collisions

TL;DR

This paper proposes a unified hydrodynamic framework to describe the reaction dynamics across pp, pA, and AA collisions, suggesting plasma formation even in small systems like p-p collisions, based on experimental azimuthal anisotropy and spectra data.

Contribution

It introduces a unified description of collision systems from small to large, highlighting the possibility of Quark Gluon Plasma formation in tiny systems.

Findings

Similar azimuthal anisotropies observed in p-p, p-A, and A-A collisions.

Hydrodynamic models compatible with experimental spectra across systems.

Evidence supporting plasma formation in small collision systems.

Abstract

There is little doubt that in heavy ion collisions at the LHC and RHIC, we observe a hydrodynamically expanding system, providing strong evidence for the formation of a Quark Gluon Plasma (QGP) in the early stage of such collisions. These observations are mainly based on results on azimuthal anisotropies, but also on particle spectra of identified particles, perfectly compatible with a hydrodynamic evolution. Surprisingly, in p-Pb collisions one observes a very similar behavior, and to some extent even in p-p. We take these experimental observations as a strong support for a unified approach to describe proton-proton (p-p), proton-nucleus (p-A), and nucleus-nucleus (A-A) collisions, with a plasma formation even in tiny systems as in p-p scatterings.