Production of Σ(1385)± and Ξ(1530)0 measured by ALICE in pp, p–Pb and Pb–Pb collisions at the LHC

Jihye Song

doi:10.1016/j.nuclphysa.2017.05.061

Abstract

The measurement of resonances in ultra-relativistic heavy-ion collisions allows one to study the properties of the hadronic medium. Resonances with short lifetimes compared to the duration of the time span between chemical and kinetic freeze out are good candidates to probe the interplay of particle re-scattering and regeneration in the hadronic phase, which result in a modification of their measured yields. Measurements of Σ(1385)± and Ξ(1530)0 have been performed with the ALICE detector in pp, p–Pb and Pb–Pb collisions at LHC energies. We report on pT-integrated yield ratios as function of charged-particle multiplicity density, 〈dNch/dηlab〉, which is used as a proxy for the size of collision system. These results complement the information derived from the measurement of other resonances such as K⁎(892)0 and ϕ(1020). The system size dependence of the yield ratio of short-lived resonances to longer-lived particles with the same strangeness content is discussed and compared to predictions from pQCD-inspired models, statistical hadronization models and EPOS.

Highlights

The expectations from a thermal model calculation with chemical freeze-out temperature of 156 MeV for the most central collisions are shown
These baryonic resonances are studied by reconstructing their hadronic decay daughters
The yield ratios of excited to stable hyperon with the same strangeness content are presented in Fig. 3 together with predictions from commonly used Monte Carlo generators, PYTHIA8 for pp and DPMJET for pPb, and thermal model predictions for Pb-Pb collisions [12, 13, 14]

Summary

Introduction

The expectations from a thermal model calculation with chemical freeze-out temperature of 156 MeV for the most central collisions are shown. Σ∗± and Ξ∗0 in addition, production in p–Pb collisions at the Ξ∗0 has been measured in Pb–Pb collisions at h√asvNeNb=een2.r7e6ceTnetVly. These baryonic resonances are studied by reconstructing their hadronic decay daughters. 0-80% (x16) 0-10% (x1) 10-40% (x1/4) 40-80% (x1/8) Boltzmann fit EPOS v3.107 Uncertainties: stat.(bars), syst.(boxes)

Results

Conclusion