Signatures of collective flow in high multiplicity pp collisions

TL;DR

This study models high-multiplicity proton-proton collisions at the LHC using a blast-wave approach to explore signatures of collective flow, highlighting the impact of resonance decays and proposing a new observable for detecting flow effects.

Contribution

It introduces a detailed blast-wave model including resonance decays to analyze collective flow signatures in high-multiplicity pp collisions, proposing the R^E_out/R^G_side ratio as a sensitive flow probe.

Findings

Resonance decays amplify flow effects in correlation functions.

The R^E_out/R^G_side ratio effectively indicates the presence of collective flow.

Model scenarios show distinguishable signatures for small and large radial flow.

Abstract

A blast-wave parametrization, including a full set of hadronic resonances, is used to model a small system, with total particle multiplicity comparable to the one measured in the high-multiplicity pp collisions at the LHC. Calculations are preformed for three cases: with negligible, regular and strong radial flow on the blast-wave hypersurface. We investigate the effects of flow on inclusive p_T spectra as well as on 1D and 3D femtoscopic radii for pions. Special emphasis is put on the role of pions from resonance decays. In particular we show that they magnify the flow effects present in the blast-wave stage and significantly influence the shape of the correlation functions. A specific observable, the R^E_out/R^G_side ratio is proposed as a sensitive probe of the collective effects. Model results for the high multiplicity pp collisions, for scenarios with small and large radial flow are compared.