A transport model study of multiparticle cumulants in $p+p$ collisions at 13 TeV

TL;DR

This study uses the AMPT model to investigate multiparticle cumulants in high-energy proton-proton collisions, revealing the significance of sub-nucleon geometry and parton cross section in reproducing flow-like signals.

Contribution

It demonstrates that incorporating sub-nucleon geometry in the AMPT model improves the description of multiparticle cumulants in small collision systems.

Findings

Negative $c_{2}\{4\}$ values at high multiplicities

Non-monotonous dependence of $c_{2}\{4\}$ on parton cross section

Sub-nucleon geometry enhances model agreement with data

Abstract

Flow-like signals including the ridge structure observed in small collision systems that are similar to those in large collision systems have led to questions about the onset of collectivity in nuclear collisions. In this study, we use the string melting version of a multi-phase transport (AMPT) model with or without the sub-nucleon geometry for the proton to study multiparticle cumulants in $p+p$ collisions at 13 TeV. Both versions of the model produce negative $c_{2}\{4 \}$ values at high multiplicities. In addition, the dependence of $c_{2}\{4 \}$ on the parton cross section is non-monotonous, where only a range of parton cross section values leads to negative $c_{2} \{4 \}$. Furthermore, the AMPT model with sub-nucleon geometry better describes the multiplicity dependence of $c_{2} \{4 \}$, demonstrating the importance of incorporating the sub-nucleon geometry in studies of small collision systems.