Browsing by Author "Anuj Chandra"

Now showing 1 - 3 of 3

Event-by-event analysis of high-multiplicity events produced in 158 A GeV/c 208Pb-208Pb collisions
(Institute of Physics Publishing, 2015) Shakeel Ahmad; Anuj Chandra; Ashwini Kumar; O.S.K. Chaturvedi; A. Ahmad; M. Zafar; M. Irfan; B.K. Singh
An extensive analysis of individual high-multiplicity events produced in208Pb-208Pb collisions is carried out by adopting different methods to examine the anomalous behavior of these rare events. A method of selecting the events with densely populated narrow regions or spikes out of a given sample of collision events is discussed. Employing this approach two events with large spikes in their η- and φ-distributions are selected for further analysis. For the sake of comparison, another two events which do not exhibit such spikes are simultaneously analyzed. The findings suggest that systematic studies of particle density fluctuations in one- and two-dimensional phase spaces and a comparison with those obtained from the studies of correlation-free Monte Carlo events, would be useful for identifying the events with large dynamical fluctuations. Formation of clusters or jet-like phenomena in multihadronic final states in individual events is also discussed and the experimental findings are compared with the independent particle emission hypothesis by carrying out Monte Carlo simulations. © CopyrightEPLA, 2015.
Multifractal analysis of heavy-ion collisions at RHIC and LHC energies
(Elsevier B.V., 2025) Anuj Chandra; Ashwini Kumar; Sweta K. Singh; Shakeel Ahmad; Bhartendu Kumar Singh
An extensive analysis of HYDJET++ generated heavy-ion collision data at collider energies is carried out using Takagi moment method based multifractal analysis approach, to search for the presence of local density fluctuations. We report first analysis on multifractality in Au-Au collisions for the RHIC energies, sNN=14.5 to 200 GeV and in Pb-Pb collisions at LHC energies, sNN=2.76 to 5.02 TeV in two-dimensional (η−ϕ) phase-space. The generalized dimension Dq for different orders q at different centralities have been calculated using the methodology proposed by Takagi. The calculated Dq values are found to exhibit collision energy as well as centrality dependent behaviour and analysis suggests the multifractal behaviour of charged particle spectra at collider energies. The linear dependence of the Dq values as a function of lnq(q−1) favours the multifractal Bernoulli representation and the values of multifractal specific heat, c, have been extracted from the Dq values to perform a comparative analysis with the available experimental data and other model results at collider energies. A slowly decreasing trend of the c values with increasing beam energy is observed for nuclear collisions at collider energies. In addition to this, the centrality dependent behaviour of the HYDJET++ calculated ’c’ values is observed for A-A collisions at collider energies. Further, Ginzberg-Landau (GL) theory framework is utilised here to analyse the dynamics of the HYDJET++ simulated A-A collisions at considered RHIC and LHC energies. A comparative analysis of the HYDJET++ calculated value of the critical exponent ’ ν ’, with other model calculations and with the reported experimental measurements is also presented. The ’ ν ’ values calculated in the present analysis exhibit approximately a constant value less than the value predicted by GL thoery for the considered RHIC and LHC energies, whereas it is quite close to 1 at LHC energies, agreeing well with the value predicted by 2D Ising model. © 2025 The Authors.
Scaling properties of particle density fluctuations at LHC energies
(Institute of Physics, 2024) Arpit Singh; Ashwini Kumar; Anuj Chandra; Sweta Singh; Shakeel Ahmad; B.K. Singh
The availability of high-multiplicity events at LHC energies provides a unique opportunity to examine the nature of phase-transition (PT) in heavy-ion collisions. Within the framework of HYDJET++ model, a systematic study of particle density fluctuations in narrow phase-space bins in Pb-Pb collisions at and 5.02 TeV energies is performed using the method of scaled factorial moments (SFM). The findings reveal the presence of intermittency in the 2-dimensional (2D) phase space distribution of charged particles at the LHC energies. The anomalous fractal dimensions, d q , are observed to increase with the order of the moments q, suggesting the multifractal nature of the charged particle production. The parameter λ q is found to exhibit a monotonically decreasing trend with the order of the moments but with no clear minima in λ q values. Furthermore, the value of the critical exponent is estimated and compared with those predicted by other models reported at RHIC and LHC energies. The value of the critical exponent, ν, obtained in the present study, shows significant departure from the value ∼1.304, as expected for the Ginzberg-Landau (GL) type second-order PT but exhibits a good level of agreement with the results obtained by other models at LHC energies. Copyright © 2024 EPLA.