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Event-by-Event Multiplicity Fluctuations in Heavy-Ion Collisions Using Modified HIJING Monte Carlo Generator

Y. A. Rusak, L. F. Babichev

Abstract

This work presents an analysis of event-by-event multiplicity fluctuations as a sensitive tool for diagnosing the state of matter produced in relativistic heavy-ion collisions. Using a modified version of the HIJING Monte Carlo generator, which integrates various models of partonic energy loss in hot (quark-gluon plasma) and cold media, the connection between fluctuation dynamics and system properties is investigated. It is shown that the nature and magnitude of fluctuations allow for the identification of the created medium type (hot or cold), the testing of the adequacy of energy loss models, and the detection of signatures of a first-order phase transition in different kinematic regions. The results obtained are important for interpreting the data from experiments aimed at mapping the QCD phase diagram and searching for the critical point.

Event-by-Event Multiplicity Fluctuations in Heavy-Ion Collisions Using Modified HIJING Monte Carlo Generator

Abstract

This work presents an analysis of event-by-event multiplicity fluctuations as a sensitive tool for diagnosing the state of matter produced in relativistic heavy-ion collisions. Using a modified version of the HIJING Monte Carlo generator, which integrates various models of partonic energy loss in hot (quark-gluon plasma) and cold media, the connection between fluctuation dynamics and system properties is investigated. It is shown that the nature and magnitude of fluctuations allow for the identification of the created medium type (hot or cold), the testing of the adequacy of energy loss models, and the detection of signatures of a first-order phase transition in different kinematic regions. The results obtained are important for interpreting the data from experiments aimed at mapping the QCD phase diagram and searching for the critical point.
Paper Structure (4 sections, 9 equations, 5 figures)

This paper contains 4 sections, 9 equations, 5 figures.

Table of Contents

  1. Introduction
  2. Generator modification
  3. Results
  4. Summary

Figures (5)

  • Figure 1: Example of the probability distribution of first order phase transition in event-by-event collisions versus $\sqrt{s_{NN}}$. The parameters of the distribution are: $(\sqrt{s_{NN}})_{b}=120$ GeV, $\sigma^2=30$ GeV.
  • Figure 2: The ratio of the 2nd to 1st cumulant of charged hadron multiplicity vs $\sqrt{S_{NN}}$ for different models of parton energy loss in medium: inf.+finite –- full energy loss model according to Eq. \ref{['eq:2']}; cold –- cold matter Mueller96; BDMPS –- BDMPS model only; 2 GeV/fm –- unmodified HIJING with a parton energy loss parameter of 2 (default); 1PT –- presence of a first-order phase transition at the binodal point where the probability of phase transition from cold matter to hot matter equals 50 %. ; no effects –- no medium formation effects (no quenching). The kinematic cuts are: $|y|<0.5$; $0.2<p_{T}<2.0$ GeV/c.
  • Figure 3: The ratio of the 3rd to 2nd cumulant of charged hadron multiplicity vs $\sqrt{S_{NN}}$ for different models of parton energy loss in medium: inf.+finite -– full energy loss model according to Eq. \ref{['eq:2']}; cold –- cold matter Mueller96; BDMPS –- BDMPS model only; 2 GeV/fm –- unmodified HIJING with a parton energy loss parameter of 2 (default); 1PT -– presence of a first-order phase transition at the binodal point where the probability of phase transition from cold matter to hot matter equals 50 %. ; no effects –- no medium formation effects (no quenching). The kinematic cuts are: $|y|<0.5$; $0.2<p_{T}<2.0$ GeV/c.
  • Figure 4: The ratio of the 2nd to 1st cumulant of charged hadron multiplicity vs $\sqrt{S_{NN}}$ in different kinematic regions (1 -- $|y|<0.5$, $0.2<p_{T}<2.0$ GeV/c; 2 -- $|y|<1.0$; $0.2<p_{T}<2.0$ GeV/c; 3 -- $|y|<1.0$; $0<p_{T}<2.0$ GeV/c.) using probability distribution of 1st order phase transition. The parameters of this distribution are: $(\sqrt{s_{NN}})_{b}=120$ GeV, $\sigma^2=20$ GeV.
  • Figure 5: The ratio of the 3rd to 2nd cumulant of charged hadron multiplicity vs $\sqrt{S_{NN}}$ in different kinematic regions (1 -- $|y|<0.5$, $0.2<p_{T}<2.0$ GeV/c; 2 -- $|y|<1.0$; $0.2<p_{T}<2.0$ GeV/c; 3 -- $|y|<1.0$; $0<p_{T}<2.0$ GeV/c.) using probability distribution of 1st order phase transition. The parameters of this distribution are: $(\sqrt{s_{NN}})_{b}=120$ GeV, $\sigma^2=20$ GeV.