scholarly journals Centrality dependence of thermal freeze-out conditions at LHC in Pb+Pb collisions at sNN = 2.76TeV

2015 ◽  
Vol 30 (33) ◽  
pp. 1550167 ◽  
Author(s):  
Saeed Uddin ◽  
Inam-ul Bashir ◽  
Riyaz Ahmed Bhat ◽  
Waseem Bashir
Keyword(s):  
Experimental Data ◽  
Chemical Potential ◽  
Heavy Ion ◽  
Collective Flow ◽  
Flow Profile ◽  
Alice Experiment ◽  
Ion Collisions ◽  
Momentum Spectra ◽  
Transverse Momentum Spectra ◽  
Freeze Out

We have analyzed the available midrapidity [Formula: see text] transverse momentum spectra of identified particles such as protons [Formula: see text], kaons [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] for different centralities of Pb+Pb collisions at the LHC energy [Formula: see text]. We have used our earlier proposed unified statistical thermal freeze-out model. The model incorporates the effect of nuclear transparency in such energetic collisions and the resulting asymmetry in the collective-flow profile along the longitudinal and the transverse directions. Our calculated results are found to be in good agreement with the experimental data measured by the ALICE experiment. The model calculation fits the experimental data for different particle species which provide thermal freeze-out conditions in terms of temperature and collective-flow parameters. The analysis shows a rise in the thermal freeze-out temperature and a mild decrease in the transverse collective-flow velocity as we go from central to the peripheral collisions. The baryon chemical potential is assumed to be nearly zero for the bulk of the matter [Formula: see text], a situation expected in the heavy ion collisions at LHC energies in the Bjorken approach owing to nearly complete nuclear transparency. The contributions from the decay of the heavier resonances are also taken into account in our calculations.

scholarly journals Transverse Momentum Distributions of Hadrons Produced in Pb-Pb Collisions at LHC EnergysNN=2.76TeV

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Saeed Uddin ◽  
Inam-ul Bashir ◽  
Riyaz Ahmed Bhat
Keyword(s):  
Experimental Data ◽  
Transverse Momentum ◽  
Chemical Potential ◽  
Particle Density ◽  
Strong Increase ◽  
Collective Flow ◽  
Alice Experiment ◽  
Particle Species ◽  
Transverse Momentum Spectra ◽  
Freeze Out

The transverse momentum spectra of several types of hadrons,p,p̅,K+,K-,Ks0,Λ,Ω,Ω̅,Ξ-, andΞ̅produced in most central Pb-Pb collisions at LHC energysNN=2.76 TeV have been studied at midrapidity (|y|<0.5) using an earlier proposed unified statistical thermal freeze-out model. The calculated results are found to be in good agreement with the experimental data measured by the ALICE experiment at LHC. The model calculation fits provide the thermal freeze-out conditions in terms of the temperature and collective flow effect parameters for different particle species. Interestingly the model parameter fits to the experimental data reveal stronger collective flow in the system and lesser freeze-out temperatures of the different particle species as compared to Au-Au collisions at RHIC. The strong increase of the collective flow appears to be a consequence of the increasing particle density at LHC. The model used incorporates a longitudinal as well as transverse hydrodynamic flow. The chemical potential has been assumed to be nearly equal to zero for the bulk of the matter owing to high degree of nuclear transparency effect at such collision energies. The contributions from heavier decay resonances are also taken into account.

scholarly journals Energy and multiplicity dependence of hadronic resonance production with ALICE at the LHC

2020 ◽  
Vol 1643 (1) ◽  
pp. 012007
Author(s):  
Angela Badalà
Keyword(s):  
Transverse Momentum ◽  
Heavy Ion Collisions ◽  
Heavy Ion ◽  
Pp Collisions ◽  
Alice Experiment ◽  
Ion Collisions ◽  
Scattering Effects ◽  
Momentum Spectra ◽  
Transverse Momentum Spectra ◽  
Hadronic Resonances

Abstract The study of hadronic resonances plays an important role both in pp and in heavy-ion collisions. Since the lifetimes of short-lived resonances are comparable with the lifetime of the fireball formed in heavy-ion collisions, regeneration and re-scattering effects can modify the measured yields, especially at low transverse momentum. Measurements in pp collisions at different energies constitute a baseline for studies in heavy-ion collisions and provide constraints for tuning QCD-inspired event generators. Furthermore, high multiplicity pp collisions, where the density and the volume of the system are expected to be larger compared to minimum bias pp collisions, can help in the search for the onset of collective phenomena. Here we present recent results on short-lived hadronic resonances obtained by the ALICE experiment at LHC energies in different collision systems (pp, p–Pb and Pb–Pb) including new results obtained in Xe–Xe collisions. The ALICE results on transverse momentum spectra, yields and their ratios to long-lived particles will be discussed.

scholarly journals PRODUCTIONS OF HEAVY FLAVORED MESONS IN RELATIVISTIC HEAVY ION COLLISIONS IN THE RECOMBINATION MODEL

2011 ◽  
Vol 20 (05) ◽  
pp. 1213-1226 ◽  
Author(s):  
R. PENG ◽  
C. B. YANG
Keyword(s):  
Experimental Data ◽  
Transverse Momentum ◽  
Heavy Quark ◽  
Heavy Ion ◽  
Relativistic Heavy Ion Collisions ◽  
Recombination Model ◽  
Ion Collisions ◽  
Momentum Spectra ◽  
Transverse Momentum Spectra ◽  
Fragmentation Functions

We find the distributions of shower partons initiated by heavy quarks c and b by studying the fragmentation functions in the framework of the recombination model. The transverse momentum spectra of heavy flavored mesons are predicted with these distributions. We find that the contribution from the recombination of thermal-shower partons is an important part in the total spectrum for the mesons. We predict the heavy flavored meson productions for different centralities with the heavy quark fugacities fitted by the experimental data of J/ψ transverse momentum spectra in Au+Au collisions.

scholarly journals Measurement of the Hadronic Resonance Production with ALICE at the CERN LHC

Universe ◽  
2018 ◽  
Vol 5 (1) ◽  
pp. 6
Author(s):  
Maria Vasileiou On behalf of the ALICE Collaboration
Keyword(s):  
Heavy Ion Collisions ◽  
Hadron Collider ◽  
Theoretical Models ◽  
Heavy Ion ◽  
Resonance Production ◽  
Ion Collisions ◽  
Momentum Spectra ◽  
Transverse Momentum Spectra ◽  
Hadronic Resonances ◽  
Freeze Out

We present a comprehensive study of hadronic resonance production in pp, p-Pb and Pb-Pb collisions at different Large Hadron Collider (LHC) energies. In particular, the production of hadronic resonances, such as ρ(770)0, Κ*(892)0, φ(1020), Σ(1385)±, Λ(1520) and Ξ(1530)0 will be discussed in detail. In heavy-ion collisions, hadronic resonances are sensitive to the re-scattering and regeneration processes occurring between chemical freeze-out and kinetic freeze-out due to their short lifetimes. The measurements in pp and p-Pb collisions are used as a reference for heavy-ion collisions and to search for the onset of collective phenomena. We will report on the transverse momentum spectra, integrated yields, mean transverse momenta, particle ratios and nuclear modification factors of hadronic resonances. The results will be compared to those of other experiments, and to theoretical models and Monte Carlo generators.

scholarly journals Production of Kaon andΛin Nucleus-Nucleus Collisions at Ultrarelativistic Energy from a Blast-Wave Model

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
S. Zhang ◽  
Y. G. Ma ◽  
J. H. Chen ◽  
C. Zhong
Keyword(s):  
Blast Wave ◽  
Particle Production ◽  
Wave Model ◽  
Heavy Ion ◽  
Relativistic Energy ◽  
Ion Collisions ◽  
Momentum Spectra ◽  
Transverse Momentum Spectra ◽  
Good Agreement ◽  
Freeze Out

The particle production of Kaon andΛis studied in nucleus-nucleus collisions at relativistic energy based on a chemical equilibrium blast-wave model. The transverse momentum spectra of Kaon andΛat the kinetic freeze-out stage from our model are in good agreement with the experimental results. The kinetic freeze-out parameters of temperatureTkinand radial flow parameterρ0are presented for the FOPI, RHIC, and LHC energies. And the resonance decay effect is also discussed. The systematic study for beam energy dependence of the strangeness particle production will help us to better understand the properties of the matter created in heavy-ion collisions at the kinetic freeze-out stage.

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 Strangeness production in Pb-Pb collisions at LHC energies with ALICE

2018 ◽  
Vol 171 ◽  
pp. 13007 ◽  
Author(s):  
Michal Šefčík
Keyword(s):  
Heavy Ion ◽  
Hadronic Decay ◽  
Particle Identification ◽  
Strangeness Production ◽  
Ion Collisions ◽  
Decay Products ◽  
Central Rapidity ◽  
Momentum Spectra ◽  
Strangeness Enhancement ◽  
Transverse Momentum Spectra

The results on the production of strange and multi-strange hadrons (K0S, Λ, Ξ and Ω) measured with ALICE in Pb-Pb collisions at the top LHC energy of [see formula in PDF] = 5.02 TeV are reported. Thanks to its excellent tracking and particle identification capabilities, ALICE is able to measure weakly decaying particles through the topological reconstruction of the identified hadronic decay products. Results are presented as a function of centrality and include transverse momentum spectra measured at central rapidity, pT-dependent Λ/K0S ratios and integrated yields. A systematic study of strangeness production is of fundamental importance for determining the thermal properties of the system created in ultrarelativistic heavy ion collisions. In order to study strangeness enhancement, the yields of studied particles are normalised to the corresponding measurement of pion production in the various centrality classes. The results are compared to measurements performed at lower energies, as well as to different systems and to predictions from statistical hadronization models.

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