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Z. Wazir

Publications and source records attributed to Z. Wazir.

13 recordsLinked to original sources

Extraction of different temperatures and kinetic freeze-out volume in high energy collisions

We analyze the transverse momentum ($p_T$) spectra, $1/N_{ev}$[(1/2$π$$p_T$) $d^2$$N$/$dyd$$p_T$], of kaon, proton, deuteron and triton in different centrality events in gold-gold (Au-Au) collisions at Relativistic Heavy Ion Collisions (RHIC) by Hagedorn thermal model and extracted the excitation function of effective temperature, kinetic freeze-out volume, initial temperature and kinetic freeze-out temperature. We perceived that the effective temperature, initial temperature and kinetic freeze-out temperature sharply increases from 7.7 GeV to 14.5 GeV and then remain static from 14.5-39 GeV, and this consistency may disclose that the onset energy of the phase transition of partial deconfinement and the whole deconfinement are 14.5 and 39 GeV respectively. The kinetic freeze-out volume and mean transverse momentum grows with the rise of collision energy. Furthermore, the different extracted temperatures are observed in the order of time evolution of the interacting system, and they (as well as kinetic freeze-out volume) have an increasing trend from peripheral to central collisions. We also observed the mass dependence of the effective temperature and kinetic freeze-out volume where former increases while the later decreases for heavier particles, which indicates the early freeze-out of the heavier particles.

nucl-th

Decoupling of non-strange, strange and multi-strange particles from the system in Cu-Cu, Au-Au and Pb-Pb collisions at high energies

Transverse momentum spectra of the non-strange, strange and multi-strange particles in central and peripheral Copper-Copper, Gold-Gold and Lead-Lead collisions are analyzed by the blast wave model with Boltzmann Gibbs statistics. The model results are approximately in agreement with the experimental data measured by BRAHMS, STAR, SPS, NA 49 and WA 97 Collaborations in special transverse momentum ranges. Bulk properties in terms of kinetic freeze out temperature, transverse flow velocity and freezeout volume are extracted from the transverse momentum spectra of the particles. Separate freeze out temperatures are observed for the non-strange, strange and multi-strange particles which maybe due to different reaction cross-sections of the interacting particles and it reveals the triple kinetic freezeout scenario in collisions at BRAHMS, STAR, SPS, NA 49 and WA 97 Collaborations, however the transverse flow velocity and freezeout volume are mass dependent and they decrease with the increasing the rest mass of the particles. Furthermore, the kinetic freezeout temperature, transverse flow velocity and kinetic freezeout volume in central nucleus-nucleus collisions are larger than those in peripheral collisions. Besides, the larger kinetic freezeout temperature and freezeout volume are observed in the most heaviest nuclei collisions, indicating their dependence on the size of interacting system

hep-ph

Analysis of kinetic freeze out temperature and transverse flow velocity in nucleus-nucleus and proton-proton collisions at same center of mass energy

Transverse momentum spectra of different types of identified charged particles in central Gold-Gold (Au-Au) collisions, and inelastic (INEL) or non-single-diffrative (NSD) proton-proton (pp) collisions at the Relativistic Heavy Ion Collider (RHIC), as well as in central and peripheral Lead-Lead (Pb-Pb) collisions, and INEL or NSD pp collisions at the Large Hadron Collider (LHC) are analyzed by the blast wave model with Tsallis statistics. The model results are approximately in agreement with the experimental data measured by STAR, PHENIX and ALICE Collaborations in special transverse momentum ranges. Kinetic freeze out temperature and transverse flow velocity are extracted from the transverse momentum spectra of the particles. It is shown that kinetic freeze out temperature of the emission source depends on mass of the particles, which reveals the mass differential kinetic freeze out scenario in collisions at RHIC and LHC. Furthermore, the kinetic freeze out temperature and transverse flow velocity in central nucleus-nucleus (AA) collisions are larger than in peripheral collisions, and both of them are slightly larger in peripheral nucleus-nucleus collisions or almost equivalent to that in pp proton-proton collisions at the same center of mass energy which shows their similar thermodynamic nature.

hep-ph

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

The 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 (pp) 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.

hep-ph

Nuclear Transparency Effect in the Strongly Interacting Matter

We discuss that the results of study of the nuclear transparency effect in nuclear-nuclear collisions at relativistic and ultrarelativistic energies could help to extract the information on new phases of the strongly interacting matter as well as the QCD critical point. The results could provide further confirmation of the existence of the "horn" effect which had initially been obtained for the ratio of average values of K+ to pi+ -mesons' multiplicity as a function of the initial energies in the NA49 SPS CERN experiment. To observe the "horn" as a function of centrality, the new more enriched experimental data are required. The data which are expected from NICA/MPD JINR and CBM GSI setups could fulfill the requirement.

nucl-ex

Pseudorapidity spectra of relativistic particles emitted in the Au and Pb induced reactions at high energies

The structure of the pseudorapidity spectra of charged relativistic particles with beta > 0.7 measured in Au+Em and Pb+Em collisions at AGS and SPS energies are analyzed using Fourier transformation method and maximum entropy one. The dependences of these spectra on the number of fast target protons (g-particles) are studied. They show visually some plateau and "shoulder" which are at least three selected points on the distributions. The plateau seems wider in Pb+Em reactions. The existing of plateau is expected for the parton models. The maximum entropy method confirms the existence of the plateau and the shoulder of the distributions.

nucl-ex

Search for a Signal on Phase Transitions of Strongly Interacting Matter using the Nuclear Transparency Effect

We discuss that the results coming from the central experiments confirm the results which had been obtained for the behavior of the K+-meson's temperature behavior as a function of the energy in SPS energy range. To see the "horn" for the behavior of the ratio for average values of K+- to pi+- mesons as a function of centrality the new more rich experimental data are required. The data can be obtained with NICA/MPD setup. The existing of the QCD critical point could be identified by using the nuclear transparency effect as a function of the centrality.

nucl-ex

Comparison of experimental and theoretical results to define centrality of heavy ion collisions

Using the simulation data coming from the cascade model, we have studied the behavior of event number as a function of impact parameter-b and a number of all charged particles- Nch for light and heavy nuclei at different energies. We have seen that for light nuclei, a number of all charged particles-Nch could be used to fix the centrality. But for heavy nuclei we have got strong initial energy and mass dependences and the results for impact parameter factor dependences and ones for a number of all charged particles differ. So for heavy nuclei, a number of charged particles-Nch could not be use to fix the centrality. Key words: cascade model; centrality, light nuclei, heavy nuclei

nucl-ex

Some properties of the central heavy ion collisions

Some experimental results are discussed in connection with the properties of the central heavy ion collisions. These experiments indicate the regime changes and saturation at some values of the centrality. This phenomenon is considered to be a signal of the percolation cluster formation in heavy ion collisions at high energies. Keywords: heavy ion collisions, theoretical models, centrality, phase transition.

nucl-ex

Light nuclei production in heavy ion collisions

Light nuclei production as a result of nuclear coalescence effect can give some signals on final state of Quark Gluon Plasma formation. We are studying the behavior of nuclear modification factor as a function of different variables using the simulated data coming from the FASTMC generator. This data is necessary to extract information on coalescence mechanism from experimental data on high energy nuclear-nuclear interactions.

nucl-ex

Study of the behavior of the nuclear modification factor in freeze-out state

We have studied the behaviour of the nuclear modification factor as a function of centrality, chemical baryon potential and thermal freeze out temperature using the data coming from the Fast Hadron Freezeout Generator. Considering two ways of NMF definition, namely the ratio of meson yields and ratio of baryons yield, we considered two associates effects (for percolation cluster formation) to identify it; appearance of the anomalous nuclear transparency and light nuclei production. In this paper we have used the behaviour of nuclear modification factor as a function of different physical parameters to get the information of the behavior of nuclear transparency effect and the nuclear coalescence in freezeout state. We have chosen different generators for this purpose. Here we have used the simulated data for Au-Au collisions at RHIC energies coming from the FASTMC Model. This model is very good in freezeout state.

nucl-ex

Some Properties of the Central pi--Meson Carbon Interactions at 40 Gev/C

We discuss some properties of the central pi--meson carbon reactions at 40 GeV/c. While these results were obtained many years ago they have not been explained completely. We attempt to interpret following: results regime change on the behavior of some characteristics of the events as a function of the centrality; anomaly peak on the angular distributions of the slow protons emitted in these reactions; charge asymmetry on the pi--mesons production in the back hemisphere in lcs. Understanding of the results could help to explain the new ones coming from the modern central experiments at high and ultrarelativistic energies.

hep-ex