scholarly journals Centrality Dependence of Chemical Freeze-Out Parameters and Strangeness Equilibration in RHIC and LHC Energies

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Deeptak Biswas
Keyword(s):  
Hadron Collider ◽  
Heavy Ion ◽  
Strange Particle ◽  
Relativistic Heavy Ion Collider ◽  
Yield Data ◽  
Central Collisions ◽  
Chemical Potentials ◽  
Beam Energy Scan ◽  
Chemical Freeze ◽  
Freeze Out

We have estimated centrality variation of chemical freeze-out parameters from yield data at midrapidity of π ± , K ± and p , p ¯ for collision energies of RHIC (Relativistic Heavy Ion Collider), Beam Energy Scan (RHIC-BES) program, and LHC (Large Hadron Collider). We have considered a simple hadron resonance gas model and employed a formalism involving conserved charges ( B , Q , S ) of QCD for parameterization. Along with temperature and three chemical potentials ( T , μ B , μ Q , μ S ), a strangeness undersaturation factor ( γ S ) has been used to incorporate the partial equilibration in the strange sector. Our obtained freeze-out temperature does not vary much with centrality, whereas chemical potentials and γ S seem to have a significant dependence. The strange hadrons are found to deviate from a complete chemical equilibrium at freeze-out at the peripheral collisions. This deviation appears to be more prominent as the collision energy decreases at lower RHIC-BES energies. We have also shown that this departure from equilibrium reduces towards central collisions, and strange particle equilibration may happen after a threshold number of participants in A - A collision.

Strange particle effective temperatures in relativistic nuclear collisions

2020 ◽  
Vol 29 (02) ◽  
pp. 2050009
Author(s):  
Oana Ristea ◽  
Catalin Ristea ◽  
Alexandru Jipa
Keyword(s):  
Energy Dependence ◽  
Sudden Change ◽  
Heavy Ion ◽  
Strange Particle ◽  
Relativistic Heavy Ion Collider ◽  
Nuclear Collisions ◽  
Effective Temperatures ◽  
Relativistic Nuclear Collisions ◽  
Onset Of Deconfinement ◽  
Beam Energy Scan

The energy dependence of the effective temperatures of charged kaons, [Formula: see text] and [Formula: see text] produced in Au[Formula: see text]Au collisions at the Relativistic Heavy Ion Collider (RHIC) Beam Energy Scan (BES) energies are presented. At energies around [Formula: see text][Formula: see text]GeV, there is a sudden change in the energy dependence of [Formula: see text] and [Formula: see text] effective temperatures, while at higher energies a slower, continuous rise up to [Formula: see text][Formula: see text]TeV is observed. This behavior is similar with previous SPS results and could indicate the onset of deconfinement in this energy range. The [Formula: see text] effective temperatures increase with energy and no plateau-like behavior is evidenced by the data.

scholarly journals Dependence of Temperatures and Kinetic Freeze-Out Volume on Centrality in Au-Au and Pb-Pb Collisions at High Energy

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Muhammad Waqas ◽  
Fu-Hu Liu ◽  
Zafar Wazir
Keyword(s):  
Transverse Momentum ◽  
Hadron Collider ◽  
Heavy Ion ◽  
High Energy ◽  
Relativistic Heavy Ion Collider ◽  
Event Centrality ◽  
Momentum Spectra ◽  
Standard Distribution ◽  
Transverse Momentum Spectra ◽  
Freeze Out

Centrality-dependent double-differential transverse momentum spectra of negatively charged particles (π−, K−, and p¯) at the mid(pseudo)rapidity interval in nuclear collisions are analyzed by the standard distribution in terms of multicomponent. The experimental data measured in gold-gold (Au-Au) collisions by the PHENIX Collaboration at the Relativistic Heavy Ion Collider (RHIC) and in lead-lead (Pb-Pb) collisions by the ALICE Collaboration at the Large Hadron Collider (LHC) are studied. The effective temperature, initial temperature, kinetic freeze-out temperature, transverse flow velocity, and kinetic freeze-out volume are extracted from the fitting to transverse momentum spectra. We observed that the mentioned five quantities increase with the increase of event centrality due to the fact that the average transverse momentum increases with the increase of event centrality. This renders that larger momentum (energy) transfer and further multiple scattering had happened in central centrality.

scholarly journals Kinetic Freeze-Out Temperature and Transverse Flow Velocity in Au-Au Collisions at RHIC-BES Energies

2020 ◽  
Vol 2020 ◽  
pp. 1-14 ◽  
Author(s):  
Muhammad Waqas ◽  
Bao-Chun Li
Keyword(s):  
Transverse Momentum ◽  
Flow Velocity ◽  
Star Collaboration ◽  
Wave Model ◽  
Heavy Ion ◽  
Transverse Flow ◽  
Relativistic Heavy Ion Collider ◽  
Beam Energy Scan ◽  
Transverse Flow Velocity ◽  
Freeze Out

By using the method of data-driven reanalysis, the midrapidity transverse momentum pT spectra of charged hadrons (π+, K+, and p) produced in central and peripheral gold-gold (Au-Au) collisions from the Beam Energy Scan (BES) program at the Relativistic Heavy Ion Collider (RHIC) are fitted by using the blast-wave model with the Boltzmann-Gibbs statistics. The model results are in agreement with the experimental data measured by the STAR Collaboration at the RHIC-BES energies. We observe that the kinetic freeze-out temperature T0, transverse flow velocity βT, mean transverse momentum pT, and initial temperature Ti increase with collision energy as well as with event centrality.

scholarly journals CENTRAL RAPIDITY DENSITIES OF CHARGED PARTICLES AT RHIC AND LHC

2000 ◽  
Vol 15 (14) ◽  
pp. 2019-2051 ◽  
Author(s):  
N. ARMESTO ◽  
C. PAJARES
Keyword(s):  
Large Hadron Collider ◽  
Hadron Collider ◽  
Charged Particles ◽  
Heavy Ion ◽  
Physical Basis ◽  
Relativistic Heavy Ion Collider ◽  
Central Collisions ◽  
Central Rapidity

Predictions on central rapidity densities of charged particles at energies of the relativistic heavy ion collider and the large hadron collider, for central collisions between the largest nuclei that will be available at these accelerators, are reviewed. Differences among the results of the existing models are discussed in relation with their underlying physical basis and with the possibilities to discriminate them.

scholarly journals Excitation Functions of Related Parameters from Transverse Momentum (Mass) Spectra in High-Energy Collisions

2020 ◽  
Vol 2020 ◽  
pp. 1-21
Author(s):  
Li-Li Li ◽  
Fu-Hu Liu ◽  
Muhammad Waqas ◽  
Rasha Al-Yusufi ◽  
Altaf Mujear
Keyword(s):  
Transverse Momentum ◽  
Mass Spectra ◽  
Hadron Collider ◽  
Heavy Ion ◽  
High Energy ◽  
Relativistic Heavy Ion Collider ◽  
Excitation Functions ◽  
Charged Pions ◽  
Standard Distribution ◽  
Freeze Out

Transverse momentum (mass) spectra of positively and negatively charged pions and of positively and negatively charged kaons, protons, and antiprotons produced at mid-(pseudo)rapidity in various collisions at high energies are analyzed in this work. The experimental data measured in central gold-gold, central lead-lead, and inelastic proton-proton collisions by several international collaborations are studied. The (two-component) standard distribution is used to fit the data and extract the excitation function of effective temperature. Then, the excitation functions of kinetic freeze-out temperature, transverse flow velocity, and initial temperature are obtained. In the considered collisions, the four parameters increase with the increase of collision energy in general, and the kinetic freeze-out temperature appears at the trend of saturation at the top Relativistic Heavy Ion Collider and the Large Hadron Collider.

scholarly journals Elliptic Flow of Hadrons via Quark Coalescence Mechanism Using the Boltzmann Transport Equation for Pb+Pb Collision at sNN=2.76 TeV

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Mohammed Younus ◽  
Sushanta Tripathy ◽  
Swatantra Kumar Tiwari ◽  
Raghunath Sahoo
Keyword(s):  
Transport Equation ◽  
Hadron Collider ◽  
Boltzmann Transport Equation ◽  
Elliptic Flow ◽  
Heavy Ion ◽  
Vital Role ◽  
Boltzmann Transport ◽  
Relativistic Heavy Ion Collider ◽  
Equilibrium Function ◽  
Freeze Out

Elliptic flow of hadrons observed at relativistic heavy ion collision experiments at relativistic heavy ion collider (RHIC) and large hadron collider (LHC) provides us an important signature of possible deconfinement transition from the hadronic phase to partonic phase. However, hadronization processes of deconfined partons back into final hadrons are found to play a vital role in the observed hadronic flow. In the present work, we use a coalescence mechanism also known as recombination (ReCo) to combine quarks into hadrons. To get there, we have used the Boltzmann transport equation in relaxation time approximation to transport the quarks into equilibration and finally to freeze-out the surface, before coalescence takes place. A Boltzmann-Gibbs blast wave (BGBW) function is taken as an equilibrium function to get the final distribution and a power-like function to describe the initial distributions of partons produced in heavy ion collisions. In the present work, we try to estimate the elliptic flow of identified hadrons such as π, K, and p, produced in Pb+Pb collisions at sNN=2.76 TeV at the LHC for different centralities. The elliptic flow (v2) of identified hadrons seems to be described quite well in the available pT range. After the evolution of quarks until freeze-out time has been calculated using BTE-RTA, the approach used in this paper consists of combining two or more quarks to explain the produced hadrons at intermediate momenta regions. The formalism is found to describe the elliptic flow of hadrons produced in Pb+Pb collisions to a large extent.

scholarly journals Quark Number Susceptibilities and Equation of State in QCD at Finite μB

Proceedings ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 5
Author(s):  
Saumen Datta ◽  
Rajiv Gavai ◽  
Sourendu Gupta
Keyword(s):  
Equation Of State ◽  
Taylor Series ◽  
Chemical Potential ◽  
Baryon Number ◽  
Heavy Ion ◽  
Relativistic Heavy Ion Collider ◽  
Quark Number ◽  
Monte Carlo Studies ◽  
Essential Input ◽  
Beam Energy Scan

One of the main goals of the cold baryonic matter (CBM) experiment at FAIR is to explore the phases of strongly interacting matter at finite temperature and baryon chemical potential μ B . The equation of state of quantum chromodynamics (QCD) at μ B > 0 is an essential input for the CBM experiment, as well as for the beam energy scan in the Relativistic Heavy Ion Collider(RHIC) experiment. Unfortunately, it is highly nontrivial to calculate the equation of state directly from QCD: numerical Monte Carlo studies on lattice are not useful at finite μ B . Using the method of Taylor expansion in chemical potential, we estimate the equation of state, namely the baryon number density and its contribution to the pressure, for two-flavor QCD at moderate μ B . We also study the quark number susceptibilities. We examine the technicalities associated with summing the Taylor series, and explore a Pade resummation. An examination of the Taylor series can be used to get an estimate of the location of the critical point in μ B , T plane.

scholarly journals Small System Collectivity in Relativistic Hadronic and Nuclear Collisions

2018 ◽  
Vol 68 (1) ◽  
pp. 211-235 ◽  
Author(s):  
James L. Nagle ◽  
William A. Zajc
Keyword(s):  
Large Hadron Collider ◽  
Nuclear Matter ◽  
Hadron Collider ◽  
Heavy Ion ◽  
Relativistic Heavy Ion Collider ◽  
Small System ◽  
Nuclear Collisions ◽  
Ion Collisions ◽  
Bulk Motion ◽  
Inviscid Hydrodynamics

The bulk motion of nuclear matter at the ultrahigh temperatures created in heavy ion collisions at the Relativistic Heavy Ion Collider and the Large Hadron Collider is well described in terms of nearly inviscid hydrodynamics, thereby establishing this system of quarks and gluons as the most perfect fluid in nature. A revolution in the field is under way, spearheaded by the discovery of similar collective, fluid-like phenomena in much smaller systems including p+ p, p+ A, d+Au, and3He+Au collisions. We review these exciting new observations and their profound implications for hydrodynamic descriptions of small and/or out-of-equilibrium systems.

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