A two-component model for identified-hadron $\bf p_t$ spectra from 5 TeV p-Pb collisions

TL;DR

This paper introduces a two-component model to analyze identified-hadron transverse momentum spectra from 5 TeV p-Pb collisions, challenging claims of hydrodynamic flow and QGP formation in small systems by showing jet formation remains unchanged.

Contribution

The study presents a two-component (soft + hard) model that accurately describes pT spectra and suggests jet formation is unaffected in p-Pb collisions, questioning the interpretation of QGP signals.

Findings

pT spectra are well described by the TCM within uncertainties

Jet formation remains unchanged across p-Pb centralities

Radial-flow contributions are negligible in p-Pb spectra

Abstract

In preparation for the heavy ion program at the relativistic heavy ion collider (RHIC) $d$-Au collisions were designated as a control experiment for possible discovery of a quark-gluon plasma (QGP) in more-central Au-Au collisions, and contrasting results from the two systems seemed to support such a discovery. In contrast, recent results ($p_t$-spectrum and angular-correlation features) from $p$-Pb collisions at the large hadron collider (LHC) have been interpreted to support claims of hydrodynamic flows and QGP formation even in small collision systems. The present study addresses such claims via a two-component (soft + hard) model (TCM) of identified-hadron (PID) $p_t$ spectra from 5 TeV $p$-Pb collisions. $p$-Pb centrality is adopted from a previous study of ensemble-mean $\bar p_t$ data from the same system. $p$-Pb $p_t$ spectra for pions, kaons, protons and Lambdas are described by the TCM within their point-to-point uncertainties. Invariance of the TCM hard component vs $p$-Pb centrality indicates that jet formation remains unchanged in $p$-Pb collisions relative to $p$-$p$ collisions, and radial-flow contributions to spectra are negligible. These $p$-Pb TCM results have implications for interpretation of similar data features from A-A collisions in terms of QGP formation.