59499966
On Descriptions of Particle Transverse Momentum Spectra in High Energy Collisions
The transverse momentum spectra obtained in the frame of an isotropic emission source are compared in terms of Tsallis, Boltzmann, Fermi-Dirac, and Bose-Einstein distributions and the Tsallis forms of the latter three standard distributions. It 
is obtained that, at a given set of parameters, the standard distributions show a narrower shape than their Tsallis forms which result in wide and/or multicomponent spectra with the Tsallis distribution in between. A comparison among the temperatures obtained from the distributions is made with a possible relation to the Boltzmann temperature. An example of the angular distributions of projectile fragments in nuclear collisions is given.
56154903
Transverse Momentum Distributions of Final-State Particles Produced in Soft Excitation Process in 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.
54930891
Chemical Potentials of Quarks Extracted from Particle Transverse Momentum Distributions in Heavy Ion Collisions at RHIC Energies
In the framework of a multisource thermal model, the transverse momentum distributions of charged particles produced in nucleus-nucleus (A-A) and deuteron-nucleus (d-A) collisions at relativistic heavy ion collider (RHIC) energies are investigated by a two-component revised Boltzmann distribution. The calculated results are in agreement with the PHENIX experimental data. It is found that the source temperature increases obviously with increase of the particle mass and incident energy, but it does not show an obvious change with the collision centrality. Then, the values of chemical potentials for up, down, and strange quarks can be obtained from the antiparticle to particle yield ratios in a wide transverse momentum range. The relationship between the chemical potentials of quarks and the transverse momentum with different centralities is investigated, too.
121546377
Dependences of charged particle pseudorapidity distributions on impact parameter and center-of-mass energy in nucleus–nucleus collisions at relativistic energies
The centrality and rapidity dependence of charged particles over a wide range of center-of-mass energy are analyzed. In this framework of participant-spectator model, the interacting system of nucleus–nucleus collisions at relativistic energies is divided into four parts (sources): target spectator, target participant, projectile participant and projectile spectator. Each source is treated by using a revised Landau model. The pseudorapidity distributions calculated by four-component Landau model are found to be in agreement with experimental data of the PHOBOS and ALICE collaborations. The distribution height is mainly determined by effective nucleon number and center-of-mass energy; and the distribution width being measured by the revised width in the Landau model and the sources rapidity shifts. Furthermore, we have found two empirical relations for projectile-participant and projectile-spectator (pseudo)rapidity as functions of the center-of-mass energy.
124273608
Strange Quark Matter and Strangelets in a Strong Magnetic Field
We study the stability properties of magnetized strange quark matter and strangelets under a strong magnetic field in the MIT bag model. The free energy per baryon of strange quark matter feels a great influence from the magnetic held. At the held strength about 1017 G, the magnetized strange quark matter becomes more stable. Considering the finite size effect, the magnetic influence on strangelets becomes complicated. For a given magnetic held, there exists a critical baryon number, below which the magnetized strangelets have lower energy than the non-magnetized strangelets. For the held strength of 5 × 1017 G, the critical baryon number is Ac ~ 100. Generally, the critical baryon number increases with the decreasing external magnetic held. When the held strength is smaller than 1017 G, the critical baryon number goes up to Ac ~ 105. The stable radius, electric charge, and quark flavor fractions of magnetized strangelets are shown.
120288217
Comparing two-Boltzmann distribution and Tsallis statistics of particle transverse momentums in collisions at LHC energies
The transverse momentum distributions of final-state particles produced in collisions at energies available at the Large Hadron Collider (LHC) are studied by using the two-Boltzmann distribution and Tsallis statistics. Experimental distributions described by the two-Boltzmann distribution can be described by the Tsallis statistics. The two-temperature emission described by the two-Boltzmann distribution reflects temperature fluctuation of interacting system. The Tsallis statistics can describe the temperature fluctuation and the degree of non-equilibrium. The results calculated by the two-Boltzmann distribution and the Tsallis statistics are in agreement with the experimental data available at the LHC energies. In some cases, the two-Boltzmann distribution degenerates to (single) Boltzmann distribution.
120712528
Alpha emission in krypton–emulsion collisions at 1.7A GeV
Abstract The multiplicity and transverse momentum distributions of alpha projectile fragments emitted in nucleus–nucleus collisions at high energies are investigated. The results calculated by the two-source model are in agreement with the experimental data of krypton–emulsion collisions at 1.7 A  GeV.
119211238
Directed flow of transported and non-transported protons in Au+Au collisions from UrQMD model
The directed flow of inclusive, transported and non-transported (including produced) protons, as well as antiprotons, has been studied in the framework of Ultra-Relativistic Quantum Molecular Dynamics approach (UrQMD model) for Au+Au collisions at √ sNN =7.7, 11.5, 19.6, 27, 39, 62.4 and 200 GeV. The rapidity, centrality and energy dependence of directed flow for various proton groups are presented. It is found that the integrated directed flow decreases monotonically as a function of collision energy for √ sNN =11.5 GeV and beyond. However, the sign-change of directed flow of inclusive protons, seen in experimental data as a function of centrality and collision energy, can be explained by the competing effect of directed flow between transported and non-transported protons. Similarly the difference in directed flow between protons and antiprotons can be explained. Our study offers a conventional explanation on the cause of the v1 sign-change other than the antiflow component of protons alone which is argued to be linked to a phase transition.
117946057
Final-state energy spectrum in relativistic nuclear electromagnetic dissociation
The final-state energy spectrum in the electromagnetic dissociation is calculated by a simple method. The final-state energy curves obtained from the calculation are in agreement with the experimental data of Si-28 into p + Al-27 at an energy of 14.6 GeV/N.
117754834
Emission of Relativistic Light Fragments in Nucleus-Emulsion Collisions at High Energy
The transverse momentum, emission angle and pseudorapidity distributions of relativistic ® fragments produced in nucleus-emulsion collisions have been analysed using a two-temperature emission picture. The two emission sources are the projectile spectator contact layer (hot spectator) with high temperature and the other part (cold spectator) with low temperature. The transverse momentum distributions of relativistic proton fragments produced in nucleus-emulsion collisions at high energy have been analysed by a three-temperature emission picture. The three emission sources are the projectile participant local region that emits the leading protons, the projectile spectator contact layer (hot spectator) and the other part (cold spectator), respectively. The calculated results are in agreement with the experimental data of nucleus-emulsion collisions in the present accelerator energy region. The temperatures of the emission sources can be obtained from one of the transverse momentum, emission angle and pseudorapidity distributions. For a heavy projectile at high energy (for example 208Pb at 160A GeV), the temperatures of the hot spectator and the cold spectator obtained from the pseudorapidity distribution of relativistic ® fragments are 120 and 40 MeV, respectively.
119498788
MULTIPLICITY DISTRIBUTION OF NUCLEAR FRAGMENTS IN ULTRARELATIVISTIC NUCLEUS-NUCLEUS COLLISIONS