Abstract
A Monte Carlo study of identified particle ratio fluctuations at LHC energies is carried out in the framework of HIJING model using the fluctuation variable ν dyn . The simulated events for Pb-Pb collisions at s N N = 2.76 and 5.02 TeV and Xe-Xe collisions at s N N = 5.44 TeV are analyzed. From this study, it is observed that the values of π , K , p , K , and π , p follow the similar trends of energy dependence as observed in the most central collision data by NA49, STAR, and ALICE experiments. It is also observed that ν dyn for all the three combinations of particles for semicentral and central collisions, the model predicted values of ν dyn A , B for Pb-Pb collisions at s N N = 2.76 TeV agree fairly well with those observed in the ALICE experiment. For peripheral collisions, however, the model predicted values of ν dyn π , K are somewhat smaller, whereas for p , K and π , p it predicts larger values as compared to the corresponding experimental values. The possible reasons for the observed differences are discussed. The ν dyn values scaled with charged particle density when plotted against N part exhibit a flat behaviour, as expected from the independent particle emission sources. For p , K and π , p combinations, a departure from the flat trend is, however, observed in central collisions in the case of low p T window when the effect of jet quenching or resonances is considered. Furthermore, the study of ν dyn A , B dependence on particle density for various collision systems (including proton-proton collisions) suggests that at LHC energies ν dyn values for a given particle pair are simply a function of charged particle density, irrespective of system size, beam energy, and collision centrality.
Highlights
Fluctuations associated to a physical quantity measured in an experiment, in general, depend on the property of the system and are expected to provide useful clue about the nature of the system under study [1,2,3]
Correlations and ebe fluctuations of dynamical nature are believed to be associated with the critical phenomena of phase transition and their studies would lead to the local and global differences between the events produced under similar initial conditions [11]. ebe fluctuations in hadronic and heavy-ion collisions have been investigated at widely different energies using several different approaches, for example, normalized factorial moments [12,13,14,15], multifractals [16, 17], k-order rapidity spacing [18,19,20], erraticity [21,22,23], and intensive and strongly intensive quantities [24,25,26]
On the basis of the findings of the present work, the following conclusions may be arrived at: (1) For most central collisions (0–5%), HIJING predicted values of νdyn for the three particle pairs follow the same trend as exhibited by the experimental data from STAR and ALICE experiments
Summary
Fluctuations associated to a physical quantity measured in an experiment, in general, depend on the property of the system and are expected to provide useful clue about the nature of the system under study [1,2,3]. At LHC energies, the particle ratio fluctuatiopnsffiffi have been investigated by the ALICE experiment at sNN = 2:76 TeV only [43,44,45] It has been reported [43] that νdyn for 1⁄2π, K and 1⁄2p, K combinations acquires positive values irrespective of the centrality class, whereas, for 1⁄2π, p combination, the variable changes sign from positive to negative toward more peripheral collisions, indicating the difference in the production mechanisms involved of these pairs. It has been pointed out [43] that further investigations involving fluctuations with charge and species specific pairs are carried out to characterize the production dynamics and understand the observed sign changes It was, considered to undertake the study of particle raptioffiffi fluctuations by analyzing the data on Pb-Pb collpisiffiffions at sNN = 2:76 and 5.02 TeV and Xe-Xe collisions at sNN = 5:44 TeV in the framework of HIJING model. Using the HIJING, the effect of jet quenching and resonance production can be looked into
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