Enhancement of strange baryons in high-multiplicity proton-proton and proton-nucleus collisions

TL;DR

This study models the enhancement of strange baryons in high-multiplicity collisions at the LHC, showing that quark-gluon plasma formation partly occurs even in small systems like p+p and p+Pb, with yields saturating at high multiplicities.

Contribution

It introduces a dynamical core-corona model that combines hydrodynamics and string fragmentation to explain strange baryon enhancement in small collision systems.

Findings

Strange baryon to pion ratio increases with multiplicity.

QGP formation occurs partly in small systems at high multiplicity.

The ratio saturates at high multiplicity, indicating partial QGP creation.

Abstract

We investigate the enhancement of yields of strange and multi-strange baryons in proton-proton (p+p), proton-lead (p+Pb) and lead-lead (Pb+Pb) collisions at the Large Hadron Collider (LHC) energies from a dynamical core-corona initialization model. We first generate partons just after the collisions by using event generators. These partons dynamically generate the quark gluon plasma (QGP) fluids through the source terms in the hydrodynamic equations. According to the core-corona picture, this process tends to happen where the density of generated partons is high and their transverse momentum is low. Some partons do not fully participate in this process when they are in dilute regions or their transverse momentum is high and subsequently fragment into hadrons through string fragmentation. In this framework, the final hadrons come from either chemically equilibrated fluids as in the conventional hydrodynamic models or string fragmentation. We calculate the ratio of strange baryons to charged pions as a function of multiplicity and find that it monotonically increases up to $dN_{\mathrm{ch}}/d\eta \sim 100$ and then saturates above. This suggests that the QGP fluids are \textit{partly} created and that their fraction increases with multiplicity in p+p and p+Pb collisions at LHC energies.