Abstract
Anomalous event-by-event fluctuations of the relative yields of neutral (K$^0_s$) and charged kaon (K$^\pm$) have been predicted to yield a signature for the formation of Disoriented Chiral Condensate (DCC) in relativistic heavy-ion collisions. In this work, we model the production and decay of DCCs in the context of heavy-ion collisions at the Large Hadron Collider, and estimate the sensitivity of large acceptance detectors, such as the ALICE detector, towards the identification of such anomalous decays. Our study is based on the robust statistical observable, $\nu_{\rm dyn}$, known for its sensitivity to dynamical fluctuations. We first present simulations without DCCs, based on the HIJING and AMPT models, in order to establish an approximate reference for the magnitude of $\nu_{\rm dyn}({\rm K}^{\pm},{\rm K}^{0}_{s})$ and its centrality evolution in Pb--Pb collisions at the TeV energy scale. We next introduce simple phenomenological models of K$^0_s$ vs. K$^\pm$ event-by-event yield fluctuations, which we use to study the feasibility and sensitivity of detection of the production of DCCs in heavy-ion collisions. Although the precision of models such as HIJING and AMPT limit their use as absolute references and thus render anomalous fluctuations difficult to define precisely, our studies demonstrate that the magnitude of $\nu_{\rm dyn}({\rm K}^{\pm},{\rm K}^{0}_{s})$ is in fact very sensitive to the presence of small admixture of DCCs in normal non-DCC events. Consequently, while large values of $\nu_{\rm dyn}({\rm K}^{\pm},{\rm K}^{0}_{s})$ may not be sufficient to identify the existence of DCCs, nonetheless they constitute a first and necessary condition to signal their possible production in heavy-ion collisions.
Highlights
Ultrarelativistic heavy-ion collisions at CERN Large Hadron Collider (LHC) energies produce matter consisting of quarks and gluons in a deconfined state
2.76 TeV for various collision centralities. The estimates from these models are relevant to the ongoing experimental search of disoriented chiral condensate (DCC)-like signals in heavy-ion collisions at LHC and BNL
Relativistic Heavy Ion Collider (RHIC) as these models do not include the dynamics of DCC physics
Summary
Ultrarelativistic heavy-ion collisions at CERN Large Hadron Collider (LHC) energies produce matter consisting of quarks and gluons in a deconfined state. We study strangeness isospin fluctuations based on measurements of the relative yield of charged and neutral kaons evaluated with the robust correlator νdyn(K±, Ks0) [10]. Within the context of the SU(3) linear σ model, DCC domains relax by radiating pions, kaons, and η mesons The relaxation of these disoriented domains is predicted to produce widely fluctuating neutral pion and kaon yields relative to those of charged pions and kaons in a given fiducial acceptance. It is clear that the fraction fK might fluctuate for a number of reasons having little to do with the existence and production of DCCs. One needs a fluctuation observable that is sensitive to the relative yields of produced charged and neutral kaons and robust against losses associated with the production (by mixing) and detection of Ks0. Note that the individual terms Rαβ shall vanish in the absence of pair correlations, i.e., for Poissonian particle production, and their magnitude is expected to approximately scale in inverse proportion of the total multiplicity of heavyion collisions [10]
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