Long-range two-particle correlations of strange hadrons with charged particles in pPb and PbPb collisions at LHC energies

TL;DR

This study measures two-particle correlations involving strange hadrons in pPb and PbPb collisions at LHC, revealing particle species dependence of flow harmonics and their scaling with quark content.

Contribution

It provides the first detailed comparison of azimuthal anisotropies for strange hadrons in pPb and PbPb collisions at similar multiplicities, highlighting species-dependent flow effects.

Findings

K0S v2 and v3 are larger than Lambda/anti-Lambda at low pT in high-multiplicity pPb events.

The particle species dependence of flow harmonics is stronger in pPb than in PbPb collisions.

Flow harmonics scaled by constituent quarks are consistent across species at the same transverse kinetic energy.

Abstract

Measurements of two-particle angular correlations between an identified strange hadron (K0S or Lambda/anti-Lambda) and a charged particle, emitted in pPb collisions, are presented over a wide range in pseudorapidity and full azimuth. The data, corresponding to an integrated luminosity of approximately 35 inverse nanobarns, were collected at a nucleon-nucleon center-of-mass energy (sqrt(s[NN])) of 5.02 TeV with the CMS detector at the LHC. The results are compared to semi-peripheral PbPb collision data at sqrt(s[NN]) = 2.76 TeV, covering similar charged-particle multiplicities in the events. The observed azimuthal correlations at large relative pseudorapidity are used to extract the second-order (v[2]) and third-order (v[3]) anisotropy harmonics of K0S and Lambda/anti-Lambda particles. These quantities are studied as a function of the charged-particle multiplicity in the event and the transverse momentum of the particles. For high-multiplicity pPb events, a clear particle species dependence of v[2] and v[3] is observed. For pt < 2 GeV, the v[2] and v[3] values of K0S particles are larger than those of Lambda/anti-Lambda particles at the same pt. This splitting effect between two particle species is found to be stronger in pPb than in PbPb collisions in the same multiplicity range. When divided by the number of constituent quarks and compared at the same transverse kinetic energy per quark, both v[2] and v[3] for K0S particles are observed to be consistent with those for Lambda/anti-Lambda particles at the 10% level in pPb collisions. This consistency extends over a wide range of particle transverse kinetic energy and event multiplicities.