arXiv subjects

Sudipan De

Publications and source records attributed to Sudipan De.

16 recordsLinked to original sources

arXiv2025

Effect of Coriolis Force on Diffusion of D Meson

We have attempted to calculate and estimate the spatial diffusion coefficients of D meson through rotating hadron resonance gas, which can be produced in the late stage of peripheral heavy ion collisions. Employing the framework of kinetic theory in relaxation time approximation, and using Einstein's diffusion relation, one can express the spatial diffusion coefficients of D meson as a ratio of its conductivity to its susceptibility. Here, we have tuned D meson relaxation time from the knowledge of earlier works on its spatial diffusion estimations, and then we have extended the framework for the finite rotation picture of hadronic matter, where only the effect of Coriolis force is considered. Our study also revealed the anisotropic nature of diffusion in the presence of rotation with future possibilities of phenomenological signature.

hep-ph↗

arXiv2024

Empirical determination of the energy loss of heavy quarks in nuclear collisions at RHIC and LHC energies

Heavy quarks produced in the heavy ion collisions loose energy while propagting in the hot partonic matter which finally fragment to heavy ($D$ or $B$) mesons. The energy loss suffered by the heavy quarks is imprinted in the nuclear modification factor as a function of transverse momenta ($p_T$) of these heavy mesons. An alternate measure of in-medium energy loss comes through the effective shift in transverse momentum spectra of hadrons recorded in nucleus-nucleus collisions when it is compared to the same in proton-proton collisions. We start by parametrizing invariant momentum yields of heavy mesons in p+p collisions. The fit function from p+p collisions and measured nuclear modification factor in heavy ion collisions are then utilised to obtain the shift in the transeverse mass $Δm_T$ of heavy mesons produced at the RHIC and LHC experiments.The energy loss $Δm_T$ so obtained is found to scale with the transverse mass ($m_T$) of heavy mesons through a power law at different energies and centralities of collisions. We have also calculated using theoretical formalism, the total energy loss suffered by a charm quark in quark-gluon plasma produced in Pb~+~Pb collisions at the LHC energies. The evolution of the plasma is described by (2+1) dimensional longitudinal boost-invariant ideal hydrodynamics. It is found that the total energy loss of charm quarks scales with the transverse mass of charm quarks through a similar power law which supports our empirical analysis of energy loss.

hep-ph↗

arXiv2023

Spatial diffusion of heavy quarks in background magnetic field

The ratio of shear viscosity to entropy density shows a valley-shaped pattern well-known in the community of heavy-ion physics. Diffusion coefficients of heavy quark and meson shows the similar structure, and both sketches have become quite popular in the community. Present work has attempted a finite magnetic field extension of the diffusion coefficients of heavy quark and meson. Using Einstein's diffusion relation, we calculated heavy quark and heavy meson diffusion by the ratio of conductivity to susceptibility in the kinetic theory framework of relaxation time approximation. The relaxation time of heavy quark and meson are tuned from the knowledge of earlier works on spatial diffusion estimations, and then we have extended the framework for a finite magnetic field, where our outcomes have revealed two aspects - anisotropic and quantum aspects of diffusion with future possibilities of phenomenological signature.

hep-ph↗

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.

nucl-th↗

arXiv2020

Centrality dependence of nuclear suppression of D mesons in $p$+Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV

In this paper we have shown theoretical model comparisons with ALICE results for average D mesons (D$^0$, D$^+$, D$^{*+}$ and $D^+_s$) in $p$+Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV for various centralities. Transport calculations of AMPT and calculations from heavy quark pQCD model, NLO(MNR) have been used for the study of $p_T$ dependent nuclear modification factors in terms of collision centrality ($\displaystyle{Q_{pPb}}$) and the central-to-peripheral ratios ($\displaystyle{Q_{cp}}$) of D mesons. It is found that NLO model with its parametrized $\displaystyle{k_T}$ broadening scheme produces results those closely match with the published D-meson data of $p$+Pb collisions from ALICE. Likewise AMPT transport calculation shows a strong centrality dependence in results but underestimates the experimental data. The differences of both models with experimental data have been discussed.

hep-ph↗

arXiv2020

Multiplicity Dependence of J/$ψ$ Production and QCD Dynamics in $p+p$ Collisions at $\sqrt{s}$ = 13 TeV

In inelastic $p+p$ collisions, the interacting objects are quarks and gluons (partons). It is believed that there are multiple interactions between the partons in a single $p+p$ event. Recent studies of multiplicity dependence of particle production in $p+p$ collisions have gathered considerable interest in the scientific community. According to several theoretical calculations, multiple gluon participation in hadronic collisions is the cause of high-multiplicity events. If the interaction is hard enough (large $p_{\rm T}$ transfer), the semi-hard processes of multiple interactions of partons might also lead to production of heavy particles like J/$ψ$. At the LHC, an approximately linear increase of the relative J/$ψ$ yield with charged particle multiplicity is observed in $p+p$ collisions. In the present work, we have studied the contribution of quarks and gluons to the multiplicity dependence of J/$ψ$ production using pQCD inspired event generator, PYTHIA8 tune 4C, in $p+p$ collisions at $\sqrt{s} =$13 TeV by investigating relative J/$ψ$ yield and relative $\langle p_{\rm T} \rangle$ of J/$ψ$ as a function of charged particle multiplicity for different hard-QCD processes. We have estimated a newly defined ratio, $r_{pp} = {\langle p_{\rm T}^{2} \rangle}_{i}/{\langle p_{\rm T}^{2} \rangle}_{\rm MB}$, to understand J/$ψ$ production in high-multiplicity $p+p$ collisions. For the first time we attempt to study the nuclear modification factor like observables ($R_{\rm pp}$ and $R_{\rm cp}$) to understand the QCD medium formed in high-multiplicity $p+p$ collisions.

hep-ph↗

arXiv2019

Identified particle production in Xe+Xe collisions at $\sqrt{s_{\rm{NN}}}$ = 5.44 TeV using a multiphase transport model

Xe+Xe collisions at relativistic energies provide us with an opportunity to study a possible system with deconfined quarks and gluons, whose size is in between those produced by p+p and Pb+Pb collisions. In the present work, we have used AMPT transport model with nuclear deformation to study the identified particle production such as ($π^{+}+π^{-}$), (K$^{+}$+K$^{-}$), $\rm{K}_{s}^0$, (p+$\bar{\rm{p}}$), $ϕ$ and ($Λ+ \barΛ$) in Xe+Xe collisions at $\sqrt{s_{\rm NN}}$=5.44 TeV. We study the $p\rm{_T}$-spectra, integrated yield, $p\rm{_T}$-differential and $p\rm{_T}$-integrated particle ratios to ($π^{+}+π^{-}$) and (K$^{+}$+K$^{-}$) as a function of collision centrality. The particle ratios are focused on strange to non-strange ratios and baryon to meson ratios. The effect of deformations has also been highlighted by comparing our results to non-deformation case. We have also compared the results from AMPT string melting and AMPT default version to explore possible effects of coalescence mechanism. We observe that the differential particle ratios show strong dependence with centrality while the integrated particle ratios show no centrality dependence.We give thermal model estimation of chemical freeze-out temperature and the Boltzmann-Gibbs Blast Wave analysis of kinetic freeze-out temperature and collective radial flow in Xe+Xe collisions at $\sqrt{s_{\rm{NN}}}$ = 5.44 TeV.

hep-ph↗

arXiv2019

Thermodynamic and transport properties in Au + Au collisions at RHIC energies from the clustering of color strings

In this work, we have extracted the initial tempearture from the transverse momentum spectra of charged particles in $Au+Au$ collisions using STAR data at RHIC energies from $\sqrt{s_{NN}}$ = 7.7 to 200 GeV. The initial energy density ($\varepsilon$), shear viscosity to entropy density ratio ($η/s$), trace anomaly ($Δ$), the squared speed of sound ($C_s^2$), entropy density, and bulk viscosity to entropy density ratio ($ζ/s$) are obtained and compared with the lattice QCD calculations for (2+1) flavor. The initial temperatures obtained are compared with various hadronization and chemical freeze-out temperatures. The analysis of the data shows that the deconfinement to confinement transition possibly takes place between $\sqrt{s_{NN}}$ = 11.5 and 19.6 GeV.

hep-ph↗

arXiv2018

Predictions for azimuthal anisotropy in Xe+Xe collisions at $\sqrt{s_{NN}}$ = 5.44 TeV using a multiphase transport model

Xe+Xe collision at relativistic energies may provide us with a partonic system whose size is approximately in between those produced by p+p and Pb+Pb collisions. The experimental results on anisotropic flow in Xe+Xe and Pb+Pb collisions should provide us with an opportunity to study system size dependence of $v_2$. In the present work, we have used AMPT transport model to calculate charged particles' $v_2$ for Xe+Xe collisions at $\sqrt{s_{NN}}$=5.44 TeV. We have also tried to demonstrate the no. of constituent quark, $N_q$, and $m_T$ scaling of the elliptic flow. We find that $n_q$ scaling of $v_2$ is not observed for the identified hadrons. The $v_2$ results from Xe+Xe collisions have also been compared to Pb+Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV. We find that flow of charged particles in (50-60)\% central collisions for Xenon nuclei is almost 30\% less than particle flow developed in lead ion collisions, implying the important role the system size play in development of particle collective motion in relativistic heavy ion collisions.

hep-ph↗

arXiv2018

Insight into Multiple Partonic Interactions and Production of Charmonia in p+p Collisions at the LHC energies

At the LHC energies, the underlying observables are of major topic of interest in high multiplicity $p+p$ collisions. Multiple Parton Interactions (MPI) is one of them, in which several interactions occur in a single $p+p$ collision. It is believed that MPI is the main reason behind the high multiplicity in $p+p$ collisions at the LHC. It was believed that MPI has only effect to the soft particle production, but recent ALICE result reveals that it can also affect the hard-particle production. In such case, the self normalized yield of heavy particle like $\rm J/ψ$ shows an increasing trend with event multiplicity. In the present contribution, we discuss the energy and multiplicity dependence of charmonium production to understand the effects of MPI on charmonium production.

hep-ph↗

arXiv2018

Energy and Centrality Dependent Study of Deconfinement Phase Transition in a Color String Percolation Approach at RHIC Energies

We take the experimental data for transverse momentum spectra of identified charged hadrons in different centrality classes for nucleus-nucleus (A+A) collisions at various Relativistic Heavy-Ion Collider (RHIC) energies measured by the STAR collaboration. We analyse these data in the framework of color string percolation model (CSPM) in order to extract various percolation parameters at different centralities at RHIC energies to study the effect of collision geometry and collision energy. We use these parameters to study the centrality dependent behaviour of initial temperature of the percolation cluster, energy density, average transverse momentum, shear viscosity to entropy density ratio ($η/s$) and trace anomaly for different energies at RHIC from $\sqrt{s_{\rm NN}}$ = 19.6 to 200 GeV. These observables are found to strongly depend on centrality at various collision energies. The critical percolation density, which is related to the deconfinement phase transition is achieved in the most central nucleus-nucleus collisions, while it fails in the peripheral collisions. A universal scaling is observed in color suppression factor and initial temperatures when studied as a function of charged particle pseudorapidity distribution scaled by nuclear overlap area at RHIC energies. The minimum of $η/s$ is observed in the most central collisions at $\sqrt{s_{\rm NN}}$ = 130 and 200 GeV.

hep-ph↗

arXiv2018

Role of Multi-Parton Interactions on $J/ψ$ production in $p+p$ collisions at LHC Energies

The production mechanism of quarkonia states in hadronic collisions is still to be understood by the scientific community. In high-multiplicity $p+p$ collisions, Underlying Event (UE) observables are of major interest. The Multi-Parton Interactions (MPI) is a UE observable, where several interactions occur at the partonic level in a single $p+p$ event. This leads to dependence of particle production on event multiplicity. If the MPI occurs in a harder scale, there will be a correlation between the yield of quarkonia and total charged particle multiplicity. The ALICE experiment at the Large Hadron Collider (LHC) in $p+p$ collisions at $\sqrt{s}$ = 7 and 13 TeV has observed an approximate linear increase of relative $J/ψ$ yield ($\frac{dN_{J/ψ}/dy}{ }$) with relative charged particle multiplicity density ($\frac{dN_{ch}/dy}{ }$). In our present work we have performed a comprehensive study of the production of charmonia as a function of charged particle multiplicity in $p+p$ collisions at LHC energies using pQCD-inspired multiparton interaction model, PYTHIA8 tune 4C, with and without Color Reconnection (CR) scheme. A detail multiplicity and energy dependent study is performed to understand the effects of MPI on $J/ψ$ production. The ratio of $ψ(2S)$ to $J/ψ$ is also studied as a function of charged particle multiplicity at LHC energies.

hep-ph↗

arXiv2016

Thermalization of dense hadronic matter in Au + Au collisions at the energies available at FAIR

The conditions of local thermodynamic equilibrium of baryons (non-strange, strange) and mesons (strange) are presented for central Au + Au collisions at FAIR energies using the microscopic transport model UrQMD. The net particle density, longitudinal-to-transverse pressure anisotropy and inverse slope parameters of the energy spectra of non-strange and strange hadrons are calculated inside a cell in the central region within rapidity window $|y| < 1.0$ at different time steps after the collision. We observed that the strangeness content is dominated by baryons at all energies, however contribution from mesons become significant at higher energies. The time scale obtained from local pressure (momentum) isotropization and thermalization of energy spectra are nearly equal and found to decrease with increase in laboratory energy. The equilibrium thermodynamic properties of the system are obtained with statistical thermal model. The time evolution of the entropy densities at FAIR energies are found very similar with the ideal hydrodynamic behaviour at top RHIC energy.

nucl-th↗

arXiv2016

Measurements of open heavy-flavour production with ALICE at the LHC

In ALICE, open heavy-flavour production is studied through the measurements of the leptons (electrons and muons) from heavy-flavour hadron decays at central and forward rapidity and via the reconstruction of D-meson hadronic decays at mid-rapidity. An overview of the open heavy-flavour production with ALICE in pp ($\sqrt{s}$ = 2.76 TeV and 7 TeV), p--Pb ($\sqrt {s_{\rm NN}}$ = 5.02 TeV) and Pb--Pb ($\sqrt {s_{\rm NN}}$ = 2.76 TeV) collisions will be presented. We will discuss the production cross sections, modifications of the transverse momentum distributions, azimuthal anisotropic emissions and correlations with hadrons in comparison with various theoretical predictions.

nucl-ex↗

arXiv2013

Method for the Analysis of Forward-Backward Multiplicity Correlations in Heavy-Ion Collisions

In heavy-ion ({\it A-A}) collisions, the correlations among the particles produced across wide range in rapidity, probe the early stages of the reaction. The analyses of forward-backward multiplicity correlations in these collisions are complicated by several effects, which are absent or minimized in hadron-hadron collisions. This includes effects, such as the centrality selection in the {\it A-A} collisions, which interfere with the measurement of the dynamical correlations. A method, which takes into account the fluctuations in centrality selection, has been utilized to determine the forward-backward correlation strength {$b_{\rm corr}$} in {\itA-A} collisions. This method has been validated by using the HIJING event generator in case of Au-Au collisions at $\sqrt{s_{NN}}$= 200 GeV and Pb-Pb collisions at $\sqrt{s_{NN}}$= 2.76 TeV. It is shown that the effect of impact parameter fluctuations is to be considered properly in order to obtain meaningful results.

nucl-ex↗

arXiv2013

Baseline study for higher moments of net-charge distribution at RHIC energies

Lattice QCD models predict the presence of a critical point in the QCD phase diagram where the first order phase transition between the hadron gas and Quark-Gluon Plasma ceases to exist. Higher moments of conserved quantities, such as net-charge, net-baryon number and net-strangeness, are proposed to be sensitive probes for locating the critical point. The moments of net-charge distributions have been studied as a function of centrality for {Au+Au} collisions at $\sqrt{s_{\rm NN}}$ = 7.7 to 200 GeV using three event generators, {\it viz.}, UrQMD, HIJING, and THERMINATOR-2. The effect of centrality selection, resonance production, as well as contributions from particle species to the net-charge moments and their products have been studied. It is observed that mean of the net-charge distributions are dominated by net-protons, whereas standard deviation, skewness and kurtosis closely follow net-pion distributions. These results, along with the predictions from Hadron Resonance Gas (HRG) model, are presented.

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