arXiv subjects

Partha Pratim Bhaduri

Publications and source records attributed to Partha Pratim Bhaduri.

At least 19 recordsLinked to original sources

arXiv2026

Charmonium suppression in fixed target proton-nucleus collisions

In this article, we perform a systematic investigation of the cold nuclear matter (CNM) effects, operative on charmonium ($J/ψ$, $ψ(2S)$) production, in fixed target proton-nucleus (p+A) collisions. Influence on charmonium production cross section due to the interplay of three different plausible CNM effects namely the initial-state parton energy loss, nuclear shadowing, and final-state absorption of the resonant states, are evaluated in detail. The available data on charmonium production in fixed target p+A collision experiments from SPS, Fermilab and HERA-B are examined for this purpose. The beam energy dependence of the observed $J/ψ$ production patterns are utilized to anticipate level of "normal" absorption in the upcoming proton induced collisions by the NA60+ experiment at CERN SPS and the CBM experiment at FAIR SIS100 accelerator facilities.

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arXiv2026

Charmonium production in low energy nuclear collisions at SPS and FAIR: achievements $\&$ prospects

In this article, we review the status of the charmonium production in low energy fixed target proton-nucleus (p-A) and nucleus-nucleus (A-A) collisions as measured by different experimental collaborations at CERN-SPS, Fermilab and HERA accelerator facilities. The interplay of different cold and hot medium effects influencing the production of these $c\bar{c}$ bound states at low collision energies is discussed in detail. Prospect for upcoming charmonium measurements close to kinematic production threshold, in the CBM experiment at FAIR SIS100 and NA60+ experiment at CERN-SPS facilities are also investigated.

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arXiv2026

Analysis of quarkonium polarization in proton-proton (p-p) collisions at LHC using PYTHIA model

The measurement of polarization serves as an important probe to investigate the production mechanism of quarkonia, the bound state of heavy quark anti-quark (charm or bottom) pairs, in hadronic collisions. In experimental invesigations, the polarization is usually measured by analyzing the anisotropies in the angular distribution of the muons originating from the decay of the quarkonium state. In the present article, we study the charmonia ($J/ψ$) and bottomonia ($Υ(1S)$) polarization at $\sqrt{s} =7 $ and 13 TeV in proton-proton(p-p) collisions at LHC using Monte Carlo (MC) event generator model PYTHIA8, which is based on perturbative QCD. The transverse momentum ($p_{T}$) differential distribution has been calculated at forward rapidity ($2.5 < y_{μμ} < 4.0$) and the polarization parameters are estimated in Helicity and Collins-Sooper reference frames. In addition, to mimic realistic experimental conditions, we have incorporated, in PYTHIA simulations, effects like detector inefficiencies and muon momentum smearing. These contributions alter the polarization parameters, introducing an artificial degree of polarization, if not properly corrected for. The simulation results have been compared with the recent ALICE measurements for quarkonia polarization in p-p collisions at LHC energy regime.

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arXiv2025

Thermo-coalescence model for Light Nuclei production in Relativistic Heavy-Ion Collisions

We employ a hybrid approach to describe the light nuclei production mechanism where the nucleons are assumed to be thermally produced, and are allowed to form light nuclei using a coalescence prescription. In this approach, we first fit transverse momentum ($p_{T}$) distribution of nucleons using hydro-inspired boost-invariant blast-wave model. The extracted parameters are then used to describe the deuteron $p_{T}$ spectra, along with two additional parameters that characterize the coalescence prescription employed in this study. We refer this combined approach as ``thermo-coalescence model'' and it is designed to study the deuteron production and describe the experimental measurements. In this work, we analyze the measured $p_{T}$ distribution of protons and deuterons from Pb-Pb collisions at the ALICE Collaboration at LHC. We also evaluate the $p_{T}$-integrated deuteron yields using this approach and compare with experimental measurements. A Bayesian inference framework is employed to determine the best-fit parameters of the thermo-coalescence model. Finally, we estimate the traditionally used experimental coalescence parameter ($B_{A}$) within our framework in order to establish a connection between our model and the conventional coalescence approach commonly used to relate experimental data with theoretical descriptions of light nuclei production.

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arXiv2025

Reexamination of eccentricity scaling of elliptic flow and incomplete thermalization scenario in heavy-ion collisions at energies available at CERN Large Hadron Collider

In this article, we reexamine the formulation for extraction of Knudsen number ($K$), the ratio of shear viscosity to entropy density ($η/s$), within the incomplete thermalization scenario, using eccentricity scaling of elliptic flow ($v_{2}$) of final state hadrons. Data on centrality dependence of charged hadron $v_{2}$ in Xe-Xe and Pb-Pb collisions, measured by ALICE and CMS collaborations at LHC are analyzed for this purpose. Results have been compared using two different models of collision namely Glauber Monte Carlo and TRENTO. The measured $v_{2}$, even for $\sqrt{s_{NN}}=5.02$ TeV most central Pb-Pb collisions is found to be below the ideal hydrodynamic limit by at least $15 \%$. Extracted $η/s$ of the medium exhibit heavy dependence on the employed initial conditions. Impact of the Pade approximants based alternative formulation of the functional relation between $v_{2}$ and $K$ are also investigated in detail. Our studies reconfirm the importance of clarifying the initial state configuration as well as the inbuilt ambiguities in employing the transport approach based on incomplete equilibrium in a strongly coupled regime at LHC.

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arXiv2025

A systematic study of initial state quark energy loss in fixed target proton nucleus collision

In this article, we investigate parton energy loss in cold nuclear matter by studying the ratio of Drell-Yan production cross sections in fixed-target proton-nucleus (p + A) collisions. We analyze Drell-Yan production cross-section data from the Fermilab E866 and E906 experiments using two different quark energy loss parametrization models and various parton distribution functions for 800 GeV and 120 GeV proton beams incident on light and heavy nuclear targets. The sensitivity of the energy loss parameter on the employed parton distribution function has been thoroughly investigated. Our results have been used to predict the target mass dependence of Drell-Yan production in upcoming proton-induced collisions at SPS and FAIR.

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arXiv2024

Dynamics of Hot QCD Matter 2024 -- Hard Probes

The hot and dense QCD matter, known as the Quark-Gluon Plasma (QGP), is explored through heavy-ion collision experiments at the LHC and RHIC. Jets and heavy flavors, produced from the initial hard scattering, are used as hard probes to study the properties of the QGP. Recent experimental observations on jet quenching and heavy-flavor suppression have strengthened our understanding, allowing for fine-tuning of theoretical models in hard probes. The second conference, HOT QCD Matter 2024, was organized to bring the community together for discussions on key topics in the field. This article comprises 15 sections, each addressing various aspects of hard probes in relativistic heavy-ion collisions, offering a snapshot of current experimental observations and theoretical advancements. The article begins with a discussion on memory effects in the quantum evolution of quarkonia in the quark-gluon plasma, followed by an experimental review, new insights on jet quenching at RHIC and LHC, and concludes with a machine learning approach to heavy flavor production at the Large Hadron Collider.

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arXiv2024

$c {\bar c}$ and $b {\bar b}$ suppression in Glasma

This study investigates the evolution and dissociation dynamics of $c\bar{c}$ and $b\bar{b}$ pairs within the pre-equilibrium, gluon-dominated stage of high energy nuclear collisions. An attractive potential made of a perturbative Coulomb-like term and of a confining term is used to simulate the attractive strong force in the pairs. Besides, we implement the interaction of the pairs with the evolving Glasma fields by virtue of the Wong equations. The interaction with the classical color fields dominates the dynamics, causing an increase in pair separation and subsequent dissociation. The observed finite probability of dissociation for these states reveals the intricate interplay between QCD dynamics and the suppression of $c\bar{c}$ and $b\bar{b}$ states during the pre-equilibrium stage. The research highlights differences between $c\bar{c}$ and $b\bar{b}$ pairs, revealing the role of quark flavor in the dissociation process. Dissociation spectra analysis indicates a peak shift towards higher momentum, reflecting a slight energy gain by the pairs. This investigation provides valuable insights into the complex dynamics of $c\bar{c}$ and $b\bar{b}$ pairs in the Glasma, which may help in better interpretation of experimental results on further integration with subsequent phases of the created matter.

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arXiv2023

Flow fluctuations and kinetic freeze-out of identified hadrons at energies available at the CERN Super Proton Synchrotron

We investigate the effect of flow fluctuations, incorporated in non boost-invariant blast-wave model, on kinetic freeze-out parameters of identified hadrons in low energy relativistic heavy-ion collisions. For the purpose of this study, we use the transverse momentum spectra of the identified hadrons produced in central Pb--Pb collisions, at SPS energies ranging from $\rm E_{Lab}=20A-158A $ GeV, and analyze them within a modified non boost-invariant blast wave model. We perform simultaneous fits of the transverse momentum spectra for light hadrons ($π^{-}$, $K^{\pm}$, $p$) and heavy strange hadrons ($Λ$, $\barΛ$, $ϕ$, $Ξ^{\pm}$, $Ω^{\pm}$) seperately. We also fit the transverse momentum spectra of charmonia ($J/Ψ$, $Ψ'$) at $\rm E_{Lab}=158A $ GeV. Our findings suggest that the inclusion of flow fluctuations enhances kinetic freeze-out temperature in case of light and heavy strange hadrons and reduces the corresponding transverse flow velocities. Moreover, we find that the kinetic freeze-out parameters of the charmonia at $\rm E_{Lab}=158A $ GeV are least affected by inclusion of flow fluctuations. Based on this, we make predictions which can provide further insights on the role of flow fluctuations in relativistic heavy-ion collisions.

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arXiv2023

Examination of thermalization of quarkonia at energies available at the CERN Large Hadron Collider

We analyze the relative yields of different bottomonia and charmonia states produced in Pb-Pb, p-Pb and high multiplicity p-p collisions at LHC, within a semi-classical grand canonical ensemble approach. The underlying assumption is the early thermalization and subsequent freezeout of these heavy hadrons resulting in their chemical freezeout at a temperature of approximately $230$~MeV, significantly higher than that of light and strange hadrons. The systematic dependence of the freezeout temperature on the collision centrality is also investigated in details.

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arXiv2022

Dynamics of Hot QCD Matter -- Current Status and Developments

The discovery and characterization of hot and dense QCD matter, known as Quark Gluon Plasma (QGP), remains the most international collaborative effort and synergy between theorists and experimentalists in modern nuclear physics to date. The experimentalists around the world not only collect an unprecedented amount of data in heavy-ion collisions, at Relativistic Heavy Ion Collider (RHIC), at Brookhaven National Laboratory (BNL) in New York, USA, and the Large Hadron Collider (LHC), at CERN in Geneva, Switzerland but also analyze these data to unravel the mystery of this new phase of matter that filled a few microseconds old universe, just after the Big Bang. In the meantime, advancements in theoretical works and computing capability extend our wisdom about the hot-dense QCD matter and its dynamics through mathematical equations. The exchange of ideas between experimentalists and theoreticians is crucial for the progress of our knowledge. The motivation of this first conference named "HOT QCD Matter 2022" is to bring the community together to have a discourse on this topic. In this article, there are 36 sections discussing various topics in the field of relativistic heavy-ion collisions and related phenomena that cover a snapshot of the current experimental observations and theoretical progress. This article begins with the theoretical overview of relativistic spin-hydrodynamics in the presence of the external magnetic field, followed by the Lattice QCD results on heavy quarks in QGP, and finally, it ends with an overview of experiment results.

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arXiv2022

Effect of various particlization scenarios on anisotropic flow and particle production using UrQMD hybrid model

We discuss the effect of various particlization scenarios available in the hybrid ultrarelativistic quantum molecular dynamics (UrQMD) event generator on different observables in non-central ($b$ $=$ 5--9 $fm$) Au + Au collisions in the beam energy range 1A-158A GeV. Particlization models switch fluid dynamic description to the transport description using various hypersurface criteria. In addition to particlization models, various equations-of-state (EoS) provided by the UrQMD hybrid model were employed. The observables examined in this paper include the excitation function of anisotropic coefficients such as directed ($v_{1}$) and elliptic flow ($v_{2}$), particle ratios of the species, and the shape of net-proton rapidity spectra at mid-rapidity. The results obtained here can help predict and compare the measurements provided by future experiments at the Facility for Antiproton and Ion Research (FAIR) and the Nuclotron-based Ion Collider fAcility (NICA) once the data becomes available. We also study the most suitable combination of the particlization model and EoS, which best describes the experimental measurements.

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arXiv2021

Dependence on beam energy and nuclear equation of state dependence of anisotropic flow and particle production in low-energy heavy-ion collisions

We analyse various flow coefficients of anisotropic momentum distribution of final state particles in mid-central ($b$ $=$ 5--9 $fm$) Au + Au collisions in the beam energy range $\rm E_{\rm Lab}$ $=$ $1A -158A$ GeV. Different variants of the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) model, namely the pure transport (cascade) mode and the hybrid mode, are employed for this investigation. In the hybrid UrQMD model, the ideal hydrodynamical evolution is integrated with the pure transport calculation for description of the evolution of the fireball. We opt for the different available equations of state (EoS) replicating the hadronic as well as partonic degrees of freedom together with possible phase transitions, viz. hadron gas, chiral + deconfinement EoS and bag model EoS, to investigate their effect on the properties of the final state particles. We also attempt to gain insights about the dynamics of the medium by studying different features of particle production such as particle ratios and net-proton rapidity distribution. The results and conclusions drawn here would be useful to understand the response of various observables to the underlying physics of the model as well as to make comparisons with the upcoming measurements of the future experiments at Facility for Antiproton and Ion Research (FAIR) and Nuclotron-based Ion Collider fAcility (NICA).

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arXiv2021

Fireball tomography from bottomonia elliptic flow in relativistic heavy-ion collisions

We calculate the elliptic flow of bottomonia produced in Pb$\,+\,$Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV. We consider temperature-dependent decay widths for the anisotropic escape of various bottomonium states and observe that the transverse momentum dependence of bottomonia elliptic flow provides a tomographic information about the QGP fireball at different stages of its evolution. For the space-time evolution of the fireball, we employ simulation results from the 3+1D quasiparticle anisotropic hydrodynamic model. We find that our results for transverse momentum dependence of bottomonia elliptic flow are in reasonable agreement with experimental results from the ALICE and CMS collaborations.

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arXiv2020

Hierarchy of kinetic freeze-out parameters in low energy heavy-ion collisions

We study the mass dependent hierarchy of kinetic freeze-out parameters of hadrons in low energy heavy-ion collisions. For this purpose, the transverse momentum and rapidity spectra of the identified hadrons produced in central Pb+Pb collisions, available at SPS energies ranging from $\rm E_{Lab}=20A-158A $ GeV, are analyzed within a generalized non boost-invariant blast wave model. We consider separate simultaneous fits for light hadrons ($π^{-}$, $K^{\pm}$) and heavy strange hadrons ($Λ$, $\barΛ$, $ϕ$, $Ξ^{\pm}$, $Ω^{\pm}$), for which the transverse momentum spectra as well as rapidity spectra are available. We also perform a separate fit to transverse momentum spectra of charmonia ($J/Ψ$, $Ψ'$) at $158A $ GeV collisions. We find a clear mass dependent hierarchy in the fitted kinetic freeze-out parameters. Further, we study the rapidity spectra using analytical Landau flow solution for non-conformal systems. We find that the fitted value of sound velocity in the medium also shows a similar hierarchy.

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arXiv2019

Anisotropic flow of charged and identified hadrons at FAIR energies and its dependence on the nuclear equation of state

In this article, we examine the equation of state (EoS) dependence of the anisotropic flow parameters ($v_{1}$, $v_{2}$ and $v_{4}$) of charged and identified hadrons, as a function of transverse momentum ($p_{\rm T}$), rapidity ($y_{c.m.}$) and the incident beam energy ($\rm E_{\rm Lab}$) in mid-central Au + Au collisions in the energy range $\rm E_{\rm Lab} = 6 -25$ A GeV. Simulations are carried out by employing different variants of the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) model, namely the pure transport (cascade) mode and the hybrid mode. In the hybrid mode, transport calculations are coupled with the ideal hydrodynamical evolution. Within the hydrodynamic scenario, two different equations of state (EoS) viz. Hadron gas and Chiral + deconfinement EoS have been employed separately to possibly mimic the hadronic and partonic scenarios, respectively. It is observed that the flow parameters are sensitive to the onset of hydrodynamic expansion of the fireball in comparison to the pure transport approach. The results would be useful as predictions for the upcoming low energy experiments at Facility for Antiproton and Ion Research (FAIR) and Nuclotron-based Ion Collider fAcility (NICA).

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arXiv2019

Anisotropic escape mechanism and elliptic flow of bottomonia

We study the role of anisotropic escape in generating the elliptic flow of bottomonia produced in ultrarelativistic heavy-ion collisions. We implement temperature-dependent decay widths for the various bottomonium states, to calculate their survival probability when traversing through the anisotropic hot medium formed in non-central collisions. We employ the recently developed 3+1d quasiparticle anisotropic hydrodynamic simulation to model the space-time evolution of the quark-gluon plasma. We provide a quantitative prediction for transverse momentum dependence of bottomonium elliptic flow and nuclear modification factor for Pb$\,+\,$Pb collisions in $\sqrt{s_{\rm NN}}=2.76$ TeV at the Large Hadron Collider.

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arXiv2018

$Ψ(2s)$ production in $p+A$ collisions

We have analyzed the data on $ψ'$ production in proton-nucleus ($p+A$) collisions, available from the NA50 Collaboration in the SPS energy domain. The investigated data sets include the absolute production cross sections as well as $ψ'$-to-Drell Yan (DY) cross section ratios. An adapted version of two component QVZ model has been employed to calculate $ψ'$ production cross sections. For both $ψ'$ and DY production, nuclear modifications to the free nucleon structure functions are taken into account. For $ψ'$, final state interaction of the produced $c\bar{c}$ pairs with the nuclear medium is also taken into account, in accordance with the previously analyzed $J/ψ$ data. A satisfactory description of the data in $p+A$ collisions is obtained. Model calculations are extrapolated to low energy regime to predict the $ψ'$ suppression in proton induced collisions at near threshold energies.

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