Overview of ALICE results on hadronic resonance production

Angela Badalà

doi:10.1051/epjconf/201714201004

Abstract

The measurement of hadronic resonance production in heavy-ion collisions is a valuable tool to study the properties of the hadronic phase. In addition, these measurements contribute to the study of particle production mechanisms, such as recombination and statistical hadronization, and can give information on the parton energy loss in the hot QCD medium. Measurement of a wide set of resonances with different lifetimes is useful to better characterize the hadronic phase and the time span between chemical and thermal freezeout. Proton-proton (pp) collisions have been used extensively as a reference for the study of larger colliding systems, but recent measurements performed in high-multiplicity pp and proton-lead (p–Pb) collisions at the LHC have shown features that are reminiscent of those observed in lead-lead (Pb–Pb) collisions. Resonance measurements in small systems serve as a reference for heavy-ion collisions and contribute to searches for collective effects. An overview of recent results on hadronic resonance production measured in ALICE will be presented. Transverse momentum ( p T ) spectra, ratios of yield to that of long-lived hadrons of the K*(892) 0 and ϕ (1020) mesons in pp, p–Pb, and Pb–Pb collisions at LHC energies will be discussed. The most recent results include the measurement of resonance production in pp collisions at 7 TeV as a function of the charged-particle multiplicity, that will be compared to the results for other light hadrons as pions, kaons, protons, K S 0 , Λ, Ξ − , Ω − . In addition, the p T spectra and yields of the ρ (770) 0 meson in pp and Pb–Pb collisions at √ s NN = 2.76 TeV and of Σ(1385) ± and Ξ(1530) 0 baryons in p–Pb collisions at √ s NN = 5.02 TeV will be presented.

Highlights

Hadronic resonances, along with stable hadrons, allow the study of properties of heavy-ion collisions, both in the early and late stage of their evolution
The presented. Transverse momentum (pT) spectra and the yields of the K∗0 and φ have been measured in pp, p–Pb and Pb–Pb collisions at the various energies studied at LHC both in inclusive and in different multiplicity or centrality intervals
In particular results on K∗(892)0 and φ(1020) in pp, p–Pb and Pb–Pb collisions at the various energies studied at LHC both in inclusive and in different multiplicity or centrality intervals, o√nsNtNhe=ρ2(.77760T)0eVmaenadsuorne√dthien Σp(p13a8n5d)±Pabn–dPΞb (1co5l3l0is)i0onmseaa-t saut r√edsNinN

Summary

Introduction

Along with stable hadrons, allow the study of properties of heavy-ion collisions, both in the early (quark-gluon plasma) and late (hadronic) stage of their evolution. Resonances with different lifetimes are good candidates to probe the interplay of particle rescattering and regeneration in the hadronic phase Comparison of such measurements to theoretical models [1, 2] allows for an estimation of the timescale between chemical and kinetic freeeze-out. In high-multiplicity pp and p–Pb collisions LHC experiments have observed features tradionally associated to the formation of a strongly-interacting quark-gluon medium and hinting at the presence of collective phenomena [11,12,13] This has triggered the investigation of collectivity-driven features in small systems and the study of strangeness production as a function of the multiplicity in p–Pb and pp collisions [14,15,16,17]. 2.76 TeV TeV in the (upper panel) and in Pb–Pb collisions centrality range 0-20% (middle panel) and 60-80% (lower panel)

Resonance identification in ALICE

Findings

Conclusions