395 research outputs found
Jet Transport Coefficient at the Large Hadron Collider Energies in a Color String Percolation Approach
Within the color string percolation model (CSPM), jet transport coefficient,
, is calculated for various multiplicity classes in proton-proton and
for centrality classes in nucleus-nucleus collisions at the Large Hadron
Collider energies for a better understanding of the matter formed in
ultra-relativistic collisions. is studied as a function of final
state charged particle multiplicity, initial state percolation temperature and
energy density. The CSPM results are then compared with different theoretical
calculations from the JET collaboration those incorporate particle energy loss
in the medium. A good agreement is found between CSPM results and the JET
collaboration calculations.Comment: 8 pages and 7 figures, Submitted for publicatio
Diffusion and fluctuations of open charmed hadrons in an interacting hadronic medium
Heavy quarks are excellent probes to understand the hot and dense medium
formed in ultra-relativistic collisions. In a hadronic medium, studying the
transport properties, e.g. the drag (), momentum diffusion (),
and spatial diffusion () coefficients of open charmed hadrons can
provide useful information about the medium. Moreover, the fluctuations of
charmed hadrons can help us to locate the onset of their deconfinement. In this
work, we incorporate attractive and repulsive interactions in the
well-established van der Waals hadron resonance gas model (VDWHRG) and study
the diffusion and fluctuations of charmed hadrons. This study helps us
understand the importance of interactions in the system, which significantly
affect both the diffusion and fluctuations of charmed hadrons.Comment: 11 pages and 8 captioned figures. Submitted for publicatio
Formation of a Perfect Fluid in , -Pb, Xe-Xe and Pb-Pb Collisions at the Large Hadron Collider Energies
Isothermal compressibility () is an important thermodynamic
observable which gives information about the deviation of a fluid from a
perfect fluid. In this work, for the first time we have estimated the
isothermal compressibility of QCD matter formed in high energy hadronic and
nuclear collisions using color string percolation model (CSPM), where we
investigate the change in as a function of final state charged
particle multiplicity across various collision species. We have also estimated
the initial percolation temperature for different collision systems at
different collision energies, which helps us to have a better understanding of
the system at the initial phase of evolution. The comparison of the CSPM
results for isothermal compressibility with that for the well known fluids,
indicates that the matter formed in heavy-ion collisions might be the {\it
closest perfect fluid} found in nature. This estimation complements the
well-known observation of minimum shear viscosity to entropy density ratio for
a possible QGP medium created in heavy-ion collision experiments. Also, a
threshold of pseudorapidity density of charged particles, is found for a possible QGP formation at the LHC energies.Comment: Xe-Xe data are added to this versio
Proton number cumulants in a modified van der Waals hadron resonance gas
An estimate of the proton number cumulants in the hadronic matter is
presented considering a van der Waals-type interaction between the constituent
particles. We argue that the attractive and repulsive parameters in the VDW
hadron resonance gas (VDWHRG) model change as functions of baryochemical
potential () and temperature (). This, in turn, affects the
estimation of thermodynamic properties and, consequently, the conserved charge
fluctuations. We employ a simple parametrization to bring in the center-of-mass
energy () dependence on temperature and baryochemical
potential and then estimate the proton number cumulants with the modified
approach. The modified van der Waals hadron resonance gas model (MVDWHRG)
explains the existing experimental data very well.Comment: 9-pages and 6-captioned figures, Submitted for publicatio
and (2S) polarization in proton-proton collisions at the LHC energies using PYTHIA8
The production mechanisms of charmonium states in both hadronic and heavy-ion
collisions hold great significance for investigating the hot and dense QCD
matter. Studying charmonium polarization in ultra-relativistic collisions can
also provide insights into the underlying production mechanisms. With this
motivation, we explore the and (2S) polarization in
proton+proton collisions at = 7, 8, and 13 TeV using a pQCD-inspired
Monte-Carlo event generator called PYTHIA8. This work considers reconstructed
quarkonia through their dimuons decay channel in the ALICE forward rapidity
acceptance range of . Further, we calculate the
polarization parameters , , from the polar and azimuthal angular distributions of the dimuons in
helicity and Collins-Soper frames. This study presents a comprehensive
measurement of the polarization parameters as a function of transverse
momentum, charged-particle multiplicity, and rapidity at the LHC energies. Our
findings of charmonium polarization are in qualitative agreement with the
corresponding experimental data.Comment: 10 pages and 5-captioned figures. Submitted for publicatio
Impact of vorticity and viscosity on the hydrodynamic evolution of hot QCD medium
The strongly interacting transient quark-gluon plasma (QGP) medium created in
ultra-relativistic collisions survive for a duration of a few fm/c. The
spacetime evolution of QGP crucially depends on the equation of state (EoS),
vorticity, viscosity, magnetic field, etc. In the present study, we obtain the
QGP lifetime considering it as a 1+1-dimensionally (1+1) D expanding fluid by
using second-order viscous hydrodynamics. We observe that the coupling of
vorticity and viscosity significantly increases the lifetime of rotating QGP.
Incorporating a static magnetic field along with vorticity and viscosity makes
the evolution slower. However, for a non-rotating medium, the static magnetic
field slightly decreases the QGP lifetime by accelerating the evolution
process. We also report the rate of change of vorticity in the QGP medium,
which can be helpful in studying the medium behavior in detail.Comment: 16 pages and 20 captioned figures. Submitted for publicatio
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.Comment: Compilation of the contributions (148 pages) as presented in the `Hot
QCD Matter 2022 conference', held from May 12 to 14, 2022, jointly organized
by IIT Goa & Goa University, Goa, Indi
Characterizing Proton-Proton Collisions at the Large Hadron Collider with Thermal Properties
High-multiplicity proton-proton (pp) collisions at the Large Hadron Collider (LHC) energies have created a new domain of research to look for a possible formation of quark–gluon plasma in these events. In this paper, we estimate various thermal properties of the matter formed in pp collisions at the LHC energies, such as mean free path, isobaric expansivity, thermal pressure, and heat capacity using a thermodynamically consistent Tsallis distribution function. Particle species-dependent mean free path and isobaric expansivity are studied as functions of final state charged particle multiplicity for pp collisions at the center-of-mass energy s = 7 TeV. The effects of degree of non-extensivity, baryochemical potential, and temperature on these thermal properties are studied. The findings are compared with the theoretical expectations
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