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 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.

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

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.

scholarly journals Comparing Standard Distribution and Its Tsallis Form of Transverse Momenta in High Energy Collisions

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Rui-Fang Si ◽  
Hui-Ling Li ◽  
Fu-Hu Liu
Keyword(s):  
Hadron Collider ◽  
Simulated Data ◽  
Heavy Ion ◽  
High Energy ◽  
Central Nucleus ◽  
Quantum Molecular Dynamics ◽  
Relativistic Heavy Ion Collider ◽  
Two Component ◽  
Standard Distribution ◽  
Effective Temperatures

The experimental (simulated) transverse momentum spectra of negatively charged pions produced at midrapidity in central nucleus-nucleus collisions at the Heavy-Ion Synchrotron (SIS), Relativistic Heavy-Ion Collider (RHIC), and Large Hadron Collider (LHC) energies obtained by different collaborations are selected by us to investigate, where a few simulated data are taken from the results of FOPI Collaboration which uses the IQMD transport code based on Quantum Molecular Dynamics. A two-component standard distribution and the Tsallis form of standard distribution are used to fit these data in the framework of a multisource thermal model. The excitation functions of main parameters in the two distributions are analyzed. In particular, the effective temperatures extracted from the two-component standard distribution and the Tsallis form of standard distribution are obtained, and the relation between the two types of effective temperatures is studied.

scholarly journals Transverse Momentum Distributions of Final-State Particles Produced in Soft Excitation Process in High Energy Collisions

2013 ◽  
Vol 2013 ◽  
pp. 1-15 ◽  
Author(s):  
Fu-Hu Liu ◽  
Ya-Hui Chen ◽  
Hua-Rong Wei ◽  
Bao-Chun Li
Keyword(s):  
Transverse Momentum ◽  
Quantum Effect ◽  
Hadron Collider ◽  
Heavy Ion ◽  
High Energy ◽  
Ideal Gas ◽  
Relativistic Heavy Ion Collider ◽  
Final State ◽  
Momentum Distributions ◽  
High Energy Collisions

Transverse momentum distributions of final-state particles produced in soft process in proton-proton (pp) and nucleus-nucleus (AA) collisions at Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) energies are studied by using a multisource thermal model. Each source in the model is treated as a relativistic and quantum ideal gas. Because the quantum effect can be neglected in investigation on the transverse momentum distribution in high energy collisions, we consider only the relativistic effect. The concerned distribution is finally described by the Boltzmann or two-component Boltzmann distribution. Our modeling results are in agreement with available experimental data.

scholarly journals The transverse momentum spectrum of low mass Drell–Yan production at next-to-leading order in the parton branching method

2020 ◽  
Vol 80 (7) ◽  
Author(s):  
A. Bermudez Martinez ◽  
P. L. S. Connor ◽  
D. Dominguez Damiani ◽  
L. I. Estevez Banos ◽  
F. Hautmann ◽  
...  
Keyword(s):  
Transverse Momentum ◽  
Hadron Collider ◽  
Center Of Mass ◽  
High Energy ◽  
Leading Order ◽  
Collinear Factorization ◽  
Transverse Momentum Dependent ◽  
Momentum Spectra ◽  
Transverse Momentum Spectra ◽  
Low Mass

Abstract It has been observed in the literature that measurements of low-mass Drell–Yan (DY) transverse momentum spectra at low center-of-mass energies $$\sqrt{s}$$s are not well described by perturbative QCD calculations in collinear factorization in the region where transverse momenta are comparable with the DY mass. We examine this issue from the standpoint of the Parton Branching (PB) method, combining next-to-leading-order (NLO) calculations of the hard process with the evolution of transverse momentum dependent (TMD) parton distributions. We compare our predictions with experimental measurements at low DY mass, and find very good agreement. In addition we use the low mass DY measurements at low $$\sqrt{s}$$s to determine the width $$q_s$$qs of the intrinsic Gauss distribution of the PB-TMDs at low evolution scales. We find values close to what has earlier been used in applications of PB-TMDs to high-energy processes at the Large Hadron Collider (LHC) and HERA. We find that at low DY mass and low $$\sqrt{s}$$s even in the region of $$p_\mathrm{T}/m_\mathrm{DY}\sim 1$$pT/mDY∼1 the contribution of multiple soft gluon emissions (included in the PB-TMDs) is essential to describe the measurements, while at larger masses ($$m_\mathrm{DY}\sim m_{{\mathrm{Z}}}$$mDY∼mZ) and LHC energies the contribution from soft gluons in the region of $$p_\mathrm{T}/m_\mathrm{DY}\sim 1$$pT/mDY∼1 is small.

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

Entropy ◽  
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.

scholarly journals Centrality Dependence of Deuteron Production in PbPb Collisions at 2.76 TeV via Hydrodynamics and Hadronic Afterburner +

Proceedings ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 6
Author(s):  
Dmytro Oliinychenko ◽  
Long-Gang Pang ◽  
Hannah Elfner ◽  
Volker Koch
Keyword(s):  
Transverse Momentum ◽  
Good Description ◽  
Hybrid Approach ◽  
Heavy Ion ◽  
High Energy ◽  
Central Collisions ◽  
Ion Collisions ◽  
Momentum Spectra ◽  
Transverse Momentum Spectra ◽  
Deuteron Production

The deuteron binding energy is only 2.2 MeV. At the same time, its yield in Pb+Pb collisionsatpsNN = 2.76 TeV corresponds to a thermal yield at the temperature around 155 MeV, which is toohot to keep deuterons bound. This puzzle is not completely resolved yet. In general, the mechanism oflight nuclei production in ultra-high energy heavy ion collisions remains under debate. In a previouswork we suggest a microscopic explanation of the deuteron production in central ultra-relativisticPb+Pb collisions, the main mechanism being ppn $ pd reactions in the hadronic phase of thecollision. We use a state-of-the-art hybrid approach, combining relativistic hydrodynamics for the hotand dense stage and hadronic transport for a later, more dilute stage. Deuteron rescattering in thehadronic stage is implemented explicitly, using its experimentally measured vacuum cross-sections.In these proceedings we extend our previous work to non-central collisions, keeping exactly thesame methodology and parameters. We find that our approach leads to a good description of themeasured deuteron transverse momentum spectra at centralities up to 40%, and underestimatesthe amount of deuterons at low transverse momentum at higher centralities. Nevertheless, thecoalescence parameter B2, measured by ALICE collaboration, is reproduced well in our approacheven for peripheral collisions.

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