Soumya Sarkar

Wavelet Analysis of Shower Track Distribution in High-Energy Nucleus-Nucleus Collisions

A continuous wavelet analysis is performed for pattern recognition of charged particle emission data in 28Si-Ag/Br interaction at 14.5A GeV and in 32S-Ag/Br interaction at 200A GeV. Making use of the event-wise local maxima present in the scalograms, we try to identify the collective behavior in multiparticle production, if there is any. For the first time, the wavelet results are compared with a model prediction based on the ultrarelativistic quantum molecular dynamics (UrQMD), where we adopt a charge reassignment algorithm to modify the UrQMD events to mimic the Bose-Einstein type of correlation among identical mesons—a feature known to be the most dominating factor responsible for local cluster formation. Statistically significant deviations between the experiment and the simulation are interpreted in terms of nontrivial dynamics of multiparticle production.

Azimuthal anisotropy in particle distribution in a multiphase transport model

Anisotropic flow of hadronic matter is considered as a sensitive tool to detect the early stage dynamics of high-energy heavy-ion collisions. Taking the event by event fluctuations of the collision geometry into account, the elliptic flow parameter and the triangular flow parameter derived from the azimuthal distribution of produced hadrons, are investigated within the framework of a multiphase transport (AMPT) model, at a collision energy that in near future will typically be available at the Facility for Antiproton and Ion Research. The dependence of elliptic and triangular flow parameters on initial fluctuations, on parton scattering cross-sections, their mass ordering on different hadron species and on the constituent quark number scaling are examined. The AMPT simulation can not exactly match the elliptic flow results on Pb + Pb collision at 40A GeV of the NA49 experiment. The simulation results presented in this work are expected to provide us with an insight to study flow properties at high baryonic density but moderate temperature, and also with an opportunity to compare similar results available from RHIC and LHC experiments.

Azimuthal structure of charged particle emission in

Presence of unusual azimuthal structures in the particle emission data obtained from the 28Si–Ag/Br interaction at 14.5A GeV and from the 32S–Ag/Br interaction at 200A GeV, are investigated in the framework of the Cherenkov gluon emission and/or Mach shock wave formation in nuclear/partonic medium. Nuclear photographic emulsion technique is used to collect the experimental data. The experiment is compared with the predictions of two simulations, namely (i) the Relativistic Quantum Molecular Dynamics (RQMD) and (ii) the Ultra-relativistic Quantum Molecular Dynamics (UrQMD). A charge reassignment algorithm is implemented over the outputs of the simulations to mimic the Bose–Einstein correlation (BEC) effect. Our analysis confirms presence of jet-like structures in both experiments beyond statistical noise. Such structures are more pronounced in the 32S data than in the 28Si data.

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Azimuthal distributions of radial velocities of charged hadrons produced in nucleus-nucleus collisions are compared with the corresponding azimuthal distribution of charged hadron multiplicity in the framework of a multiphase transport (AMPT) model at two different collision energies. The mean radial velocity seems to be a good probe for studying radial expansion. While the anisotropic parts of the distributions indicate a kind of collective nature in the radial expansion of the intermediate “fireball,” their isotropic parts characterize a thermal motion. The present investigation is carried out keeping the upcoming Compressed Baryonic Matter (CBM) experiment to be held at the Facility for Antiproton and Ion Research (FAIR) in mind. As far as high-energy heavy-ion interactions are concerned, CBM will supplement the Relativistic Heavy-Ion Collider (RHIC) and Large Hadron Collider (LHC) experiments. In this context our simulation results at high baryochemical potential would be interesting, when scrutinized from the perspective of an almost baryon-free environment achieved at RHIC and LHC.

Si-Ag/Br interaction at 14.5A GeV and

Centrality and system geometry dependence of azimuthal anisotropy of charged hadrons measured in terms of the elliptic flow parameter are investigated using Au+Au event samples at incident beam energy

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S-Ag/Br interaction at 200A GeV

A GeV and

Radial Flow in a Multiphase Transport Model at FAIR Energies

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Simulation study of elliptic flow of charged hadrons produced in Au+Au collisions at energies available at the Facility for Antiproton and Ion Research

A GeV generated by Ultrarelativistic Quantum Molecular Dynamics and A Multiphase Transport models. The Monte Carlo Glauber model is employed to estimate the eccentricity of the overlapping zone at an early stage of the collisions. Anisotropies present both in the particle multiplicity distribution and in the kinetic radial expansion are examined by using standard statistical and phenomenological methods. In the context of upcoming Compressed Baryonic Matter experiment to be held at the Facility for Antiproton and Ion Research, the present set of simulated results provide us not only with an opportunity to examine the expected collective behavior of hadronic matter at high baryon density and moderate temperature environment, but when compared with similar results obtained from Relativistic Heavy Ion Collider and Large Hadron Collider experiments, they also allow us to investigate how anisotropy of hadronic matter may differ or agree with its low baryon density and high temperature counterpart.

Azimuthal correlation and collective behavior in nucleus-nucleus collisions

Various flow effects of nuclear and hadronic origin are investigated in nucleus-nucleus collisions. Nuclear emulsion data collected from 84Kr + Ag/Br interaction at an incident energy of 1.52 GeV per nucleon and from 28Si + Ag/Br interaction at an incident energy of 14.5 GeV per nucleon are used in the investigation. The transverse momentum distribution and the flow angle analysis show that collective behavior, like a bounce-off effect of the projectile spectators and a sidesplash effect of the target spectators, are present in our event samples. From an azimuthal angle analysis of the data we also see a direct flow of the projectile fragments and of the produced charged particles. On the other hand, for both data samples the target fragments exhibit a reverse flow, while the projectile fragments exhibit an elliptic flow. Relevant flow parameters are measured.