Exploring hadronic rescattering effects on resonance productions in pp and p-Pb collisions with PYTHIA8

TL;DR

This study investigates how hadronic rescattering affects resonance production in small collision systems like pp and p-Pb at high energies, using PYTHIA8 simulations to analyze yield ratios and hadronic phase lifetimes.

Contribution

It introduces a novel analysis of hadronic rescattering effects in small systems using PYTHIA8, highlighting differences between pp and p-Pb collisions.

Findings

Rescattering causes suppression of resonance yields at low transverse momentum.

Double ratios reveal a decreasing rescattering effect with increasing multiplicity.

Lower bounds of hadronic phase lifetimes grow with multiplicity, differing between pp and p-Pb.

Abstract

In relativistic heavy-ion collisions, the quark-gluon plasma is created, and as the medium cools down, the system transitions into a hadronic phase. While such interactions are well established for large systems, such as Pb-Pb collisions, their relevance in smaller collision systems remains unclear. Consequently, hadronic interactions during the hadronic phase are studied in pp collisions at $\sqrt{s}=13$ TeV and p-Pb collisions at $\sqrt{s_{\rm{NN}}}=5.02$ TeV with the PYTHIA8 event generator. The interaction is studied via the yield ratios between resonances and stable particles with similar quark contents, which are obtained as a function of transverse momentum ($p_{\rm{T}}$) using $\mathrm{\rho(770)^0}$, $\mathrm{K^*(892)^0}$, and $\mathrm{\phi(1020)}$ mesons and their stable particles, $\mathrm{\pi^\pm}$ and $\mathrm{K^\pm}$ at midrapidity ($|\rm{y}|<0.5$). Yield ratios are calculated in five multiplicity classes for pp and six for p-Pb collisions, using the 60-100% multiplicity class in pp as a reference. Although rescattering leads to stronger suppression at low $p_{\rm{T}} < 2$ GeV/$c$, a visible suppression remains even when rescattering is turned off. To isolate the rescattering effect, double ratios between the rescattering on and off configurations are obtained. These are then integrated in the full $p_{\rm{T}}$ range ($0<p_{\rm{T}}<6.0$ GeV/$c$). The normalized double ratios show a decreasing trend with increasing multiplicity, independent of the collision system. The lower limit of the hadronic phase lifetimes extracted in the integrated-$p_{\rm{T}}$ region increases with multiplicity in both systems, but with a notable discrepancy between pp and p-Pb collisions.