Neutral to charged kaon yield fluctuations in Pb$-$Pb collisions at $\sqrt{s_{\rm NN}}$ = 2.76TeV

TL;DR

This paper reports the first measurement of event-by-event kaon yield fluctuations in Pb-Pb collisions at 2.76 TeV, revealing different scaling behaviors for charged and neutral kaon correlations and exploring implications for chiral condensate production.

Contribution

It introduces the first measurement of kaon fluctuation correlators in heavy-ion collisions at LHC energies, providing new insights into particle production mechanisms and chiral symmetry restoration.

Findings

$ u_{ m dyn}[ m K^+, m K^-]$ scales inversely with multiplicity

$ u_{ m dyn}[ m K_S^0, m K^{ m \pm}]$ deviates from simple scaling

Results are consistent with certain theoretical models and suggest possible chiral condensate effects.

Abstract

We present the first measurement of event-by-event fluctuations in the kaon sector in Pb-Pb collisions at $\sqrt {s_{\rm NN}}=$ 2.76 TeV with the ALICE detector at the LHC. The robust fluctuation correlator $\nu_{\rm dyn}$ is used to evaluate the magnitude of fluctuations of the relative yields of neutral and charged kaons, as well as the relative yields of charged kaons, as a function of collision centrality and selected kinematic ranges. While the correlator $\nu_{\rm dyn}[\rm K^+,\rm K^-]$ exhibits a scaling approximately in inverse proportion of the charged particle multiplicity, $\nu_{\rm dyn}[\rm K_S^0,\rm K^{\pm}]$ features a significant deviation from such scaling. Within uncertainties, the value of $\nu_{\rm dyn}[\rm K_S^0,\rm K^{\pm}]$ is independent of the selected transverse momentum interval, while it exhibits a pseudorapidity dependence. The results are compared with HIJING, AMPT and EPOS-LHC predictions, and are further discussed in the context of the possible production of disoriented chiral condensates in central Pb-Pb collisions.