Kinetic freeze-out temperature and flow velocity extracted from transverse momentum spectra of final-state light flavor particles produced in collisions at RHIC and LHC

The transverse momentum spectra of different types of particles, π±, K±, p and p¯, produced at mid-(pseudo)rapidity in different centrality lead–lead (Pb–Pb) collisions at 2.76 TeV; proton–lead (p–Pb) collisions at 5.02 TeV; xenon–xenon (Xe–Xe) collisions at 5.44 TeV; and proton–proton (p–p) collisions at 0.9, 2.76, 5.02, 7 and 13 TeV, were analyzed by the blast-wave model with fluctuations. With the experimental data measured by the ALICE and CMS Collaborations at the Large Hadron Collider (LHC), the kinetic freeze-out temperature, transverse flow velocity and proper time were extracted from fitting the transverse momentum spectra. In nucleus–nucleus (A–A) and proton–nucleus (p–A) collisions, the three parameters decrease with the decrease of event centrality from central to peripheral, indicating higher degrees of excitation, quicker expansion velocities and longer evolution times for central collisions. In p–p collisions, the kinetic freeze-out temperature is nearly invariant with the increase of energy, though the transverse flow velocity and proper time increase slightly, in the considered energy range.

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Study of Proton, Deuteron, and Triton at 54.4 GeV

Advances in High Energy Physics ◽

10.1155/2021/6674470 ◽

2021 ◽

Vol 2021 ◽

pp. 1-9

Author(s):

M. Waqas ◽

G. X. Peng

Keyword(s):

Transverse Momentum ◽

Flow Velocity ◽

Star Collaboration ◽

Wave Model ◽

Transverse Flow ◽

Peripheral Collisions ◽

Momentum Spectra ◽

Transverse Momentum Spectra ◽

Transverse Flow Velocity ◽

Freeze Out

Transverse momentum spectra of proton, deuteron, and triton in gold-gold (Au-Au) collisions at 54.4 GeV are analyzed in different centrality bins by the blast wave model with Tsallis statistics. The model results are approximately in agreement with the experimental data measured by STAR Collaboration in special transverse momentum ranges. We extracted the kinetic freeze-out temperature, transverse flow velocity, and freeze-out volume from the transverse momentum spectra of the particles. It is observed that the kinetic freeze-out temperature is increasing from the central to peripheral collisions. However, the transverse flow velocity and freeze-out volume decrease from the central to peripheral collisions. The present work reveals the mass dependent kinetic freeze-out scenario and volume differential freeze-out scenario in collisions at STAR Collaboration. In addition, parameter q characterizes the degree of nonequilibrium of the produced system, and it increases from the central to peripheral collisions and increases with mass .

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Study of Dependence of Kinetic Freezeout Temperature on the Production Cross-Section of Particles in Various Centrality Intervals in Au–Au and Pb–Pb Collisions at High Energies

Entropy ◽

10.3390/e23040488 ◽

2021 ◽

Vol 23 (4) ◽

pp. 488

Author(s):

Muhammad Waqas ◽

Guang-Xiong Peng

Keyword(s):

Transverse Momentum ◽

Flow Velocity ◽

Production Cross ◽

Center Of Mass ◽

Wave Model ◽

Transverse Flow ◽

Peripheral Collisions ◽

Momentum Spectra ◽

Transverse Momentum Spectra ◽

Transverse Flow Velocity

Transverse momentum spectra of π+, p, Λ, Ξ or Ξ¯+, Ω or Ω¯+ and deuteron (d) in different centrality intervals in nucleus–nucleus collisions at the center of mass energy are analyzed by the blast wave model with Boltzmann Gibbs statistics. We extracted the kinetic freezeout temperature, transverse flow velocity and kinetic freezeout volume from the transverse momentum spectra of the particles. It is observed that the non-strange and strange (multi-strange) particles freezeout separately due to different reaction cross-sections. While the freezeout volume and transverse flow velocity are mass dependent, they decrease with the resting mass of the particles. The present work reveals the scenario of a double kinetic freezeout in nucleus–nucleus collisions. Furthermore, the kinetic freezeout temperature and freezeout volume are larger in central collisions than peripheral collisions. However, the transverse flow velocity remains almost unchanged from central to peripheral collisions.

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Initial, effective, and kinetic freeze-out temperatures from transverse momentum spectra in high-energy proton(deuteron)–nucleus and nucleus–nucleus collisions

The European Physical Journal Plus ◽

10.1140/epjp/s13360-020-00213-1 ◽

2020 ◽

Vol 135 (2) ◽

Cited By ~ 2

Author(s):

Muhammad Waqas ◽

Fu-Hu Liu

Keyword(s):

Transverse Momentum ◽

High Energy ◽

High Energy Proton ◽

Energy Proton ◽

Momentum Spectra ◽

Transverse Momentum Spectra ◽

Freeze Out

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Combined analysis of midrapidity transverse momentum spectra of the charged pions and kaons, protons and antiprotons in p+p and Pb+Pb collisions at (snn)1/2 = 2.76 and 5.02 TeV at the LHC

Modern Physics Letters A ◽

10.1142/s0217732320502375 ◽

2020 ◽

Vol 35 (29) ◽

pp. 2050237

Author(s):

Khusniddin K. Olimov ◽

Shakhnoza Z. Kanokova ◽

Alisher K. Olimov ◽

Kobil I. Umarov ◽

Boburbek J. Tukhtaev ◽

...

Keyword(s):

Transverse Momentum ◽

Center Of Mass ◽

Heavy Ion ◽

Transverse Flow ◽

Alice Collaboration ◽

Momentum Spectra ◽

Charged Pions ◽

Transverse Momentum Spectra ◽

Tsallis Distribution ◽

Freeze Out

The experimental transverse momentum spectra of the charged pions and kaons, protons and antiprotons, produced at midrapidity in [Formula: see text] collisions at [Formula: see text] and 5.02 TeV, central (0–5%) and peripheral (60–80%) Pb[Formula: see text]+[Formula: see text]Pb collisions at [Formula: see text] TeV, central (0–5%), semicentral (40–50%) and peripheral (80–90%) Pb[Formula: see text]+[Formula: see text]Pb collisions at [Formula: see text] TeV, measured by ALICE collaboration, were analyzed using the Tsallis distribution function as well as Hagedorn formula with the embedded transverse flow. To exclude the influence (on the results) of different available fitting [Formula: see text] ranges in the analyzed collisions, we compare the results obtained from combined (simultaneous) fits of midrapidity spectra of the charged pions and kaons, protons and antiprotons with the above theoretical model functions using the identical fitting [Formula: see text] ranges in [Formula: see text] as well as Pb[Formula: see text]+[Formula: see text]Pb collisions at [Formula: see text] and 5.02 TeV. Using the combined fits with the thermodynamically consistent Tsallis distribution as well as the simple Tsallis distribution without thermodynamical description, it is obtained that the global temperature [Formula: see text] and non-extensivity parameter [Formula: see text] slightly increase (consistently for all the particle types) with an increase in center-of-mass (c.m.) energy [Formula: see text] of [Formula: see text] collisions from 2.76 TeV to 5.02 TeV, indicating that the more violent and faster [Formula: see text] collisions at [Formula: see text] TeV result in a smaller degree of thermalization (higher degree of non-equilibrium) compared to that in [Formula: see text] collisions at [Formula: see text] TeV. The [Formula: see text] values for pions and kaons proved to be very close to each other, whereas [Formula: see text] for protons and antiprotons proved to be significantly lower than that for pions and kaons, that is [Formula: see text]. The results of the combined fits using Hagedorn formula with the embedded transverse flow are consistent with practically no (zero) transverse (radial) flow in [Formula: see text] collisions at [Formula: see text] and 5.02 TeV. Using Hagedorn formula with the embedded transverse flow, it is obtained that the value of the (average) transverse flow velocity increases and the temperature [Formula: see text] decreases with an increase in collision centrality in Pb[Formula: see text]+[Formula: see text]Pb collisions at [Formula: see text] and 5.02 TeV, which is in good agreement with the results of the combined Boltzmann–Gibbs blast-wave fits to the particle spectra in Pb[Formula: see text]+[Formula: see text]Pb collisions at [Formula: see text] and 5.02 TeV in recent works of ALICE collaboration. The temperature [Formula: see text] parameter, which approximates the kinetic freeze-out temperature, was shown to coincide in central (0–5%) Pb[Formula: see text]+[Formula: see text]Pb collisions at [Formula: see text] and 5.02 TeV, which implies, taking into account the results of our previous analysis, that kinetic freeze-out temperature stays practically constant in central heavy-ion collisions in [Formula: see text] GeV energy range.

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

Advances in High Energy Physics ◽

10.1155/2020/8198126 ◽

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.

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Excitation Functions of Tsallis-Like Parameters in High-Energy Nucleus–Nucleus Collisions

Entropy ◽

10.3390/e23040478 ◽

2021 ◽

Vol 23 (4) ◽

pp. 478

Author(s):

Li-Li Li ◽

Fu-Hu Liu ◽

Khusniddin K. Olimov

Keyword(s):

Transverse Momentum ◽

High Energy ◽

Central Nucleus ◽

Excitation Functions ◽

Momentum Spectra ◽

Charged Pions ◽

Transverse Momentum Spectra ◽

Two Parameters ◽

Freeze Out ◽

Aa Collisions

The transverse momentum spectra of charged pions, kaons, and protons produced at mid-rapidity in central nucleus–nucleus (AA) collisions at high energies are analyzed by considering particles to be created from two participant partons, which are assumed to be contributors from the collision system. Each participant (contributor) parton is assumed to contribute to the transverse momentum by a Tsallis-like function. The contributions of the two participant partons are regarded as the two components of transverse momentum of the identified particle. The experimental data measured in high-energy AA collisions by international collaborations are studied. The excitation functions of kinetic freeze-out temperature and transverse flow velocity are extracted. The two parameters increase quickly from ≈3 to ≈10 GeV (exactly from 2.7 to 7.7 GeV) and then slowly at above 10 GeV with the increase of collision energy. In particular, there is a plateau from near 10 GeV to 200 GeV in the excitation function of kinetic freeze-out temperature.

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Effects of coalescence and isospin symmetry on the freezeout of light nuclei and their anti-particles

Scientific Reports ◽

10.1038/s41598-021-99455-x ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

M. Waqas ◽

G. X. Peng ◽

Fu-Hu Liu ◽

Z. Wazir

Keyword(s):

Transverse Momentum ◽

Flow Velocity ◽

Wave Model ◽

Transverse Flow ◽

Light Nuclei ◽

Isospin Symmetry ◽

Proton Proton ◽

Momentum Spectra ◽

Transverse Momentum Spectra ◽

Transverse Flow Velocity

AbstractThe transverse momentum spectra of light nuclei (deuteron, triton and helion) produced in various centrality intervals in Gold–Gold (Au–Au), Lead–Lead (Pb–Pb) and proton–Lead (p–Pb) collisions, as well as in inelastic (INEL) proton–proton (p–p) collisions are analyzed by the blast wave model with Boltzmann Gibbs statistics. The model results are nearly in agreement with the experimental data measured by STAR and ALICE Collaborations in special transverse momentum ranges. We extracted the bulk properties in terms of kinetic freezeout temperature, transverse flow velocity and freezeout volume. It is observed that deuteron and anti-deuteron freezeout later than triton and helion as well as their anti-particles due to its smaller mass, while helion and triton, and anti-helion and anti-triton freezeout at the same time due to isospin symmetry at higher energies. It is also observed that light nuclei freezeout earlier than their anti-nuclei due to the large coalescence of nucleons for light nuclei compared to their anti-nuclei. The kinetic freezeout temperature, transverse flow velocity and kinetic freezeout volume decrease from central to peripheral collisions. Furthermore, the transverse flow velocity depends on mass of the particle which decreases with increasing the mass of the particle.

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Squeezed spectra of bosons and antibosons with different in-medium masses

International Journal of Modern Physics E ◽

10.1142/s0218301321500439 ◽

2021 ◽

pp. 2150043

Author(s):

Yong Zhang ◽

Hui-Qiang Ding ◽

Shi-Yao Wang

Keyword(s):

Transverse Momentum ◽

Mass Difference ◽

Mass Region ◽

Transverse Mass ◽

Medium Mass ◽

Momentum Spectra ◽

Transverse Momentum Spectra ◽

The Difference ◽

Increasing Temperature ◽

Freeze Out

In this paper, we study the influence of the in-medium mass difference between boson and antiboson on their spectra. The in-medium mass difference may lead to a difference between the transverse momentum spectra of boson and antiboson. This effect increases with the increasing in-medium mass difference between boson and antiboson. The difference between the transverse momentum spectra of boson and antiboson increases with the increasing expanding velocity of the source and decreases with the increasing transverse momentum in large transverse mass region ([Formula: see text][Formula: see text]GeV). The interactions between the hadron and the medium may increase with the increasing temperature of the medium and the higher freeze-out temperature may lead to a larger mass difference between boson and antiboson, and may give rise to a larger difference between the transverse momentum spectra of boson and antiboson for higher freeze-out temperature.

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