Thermodynamics Of Particle-production Mechanism In High-energy Nuclear Collisions

High energy nuclear collision is an important topic in particle and nuclear physics.It mainly investigates the matter evolution and particle-production mechanism in the collision process.Physicists predicted that the quark matter at a high temperature and high density is produced in the initial stage of the collision.This quark matter is called quark-gluon-plasma(QGP).The high energy nuclear collision experiment can provide sufficient energy to melt nuclei.As the incident energy increases,the QGP may be formed.Since the QGP exists only for a short period of time in the collision,it can not be observed directly.The signal of QCD phase transition can be obtained indirectly by the study of final-state particles produced in the collision.In the experiment,scientists built some accelerators,such as the Large Hadron Collider(LHC)at European Organization for Nuclear Research(CERN)and the Relativistic Heavy Ion Collider(RHIC)at Brookhaven National Laboratory(BNL).With high and ultra-high energy nuclear collisions running,more and more data are measured.These data are analyzed by theory models to obtain the information of matter evolution in collision systems.The final-state product is a multi-particle system.Statistical methods can extract the information of system evolution and particle production.In this work,we use the improved multi-source thermal model to study the distributions of final state particles in LHC energies.The paper is made up of two parts.Firstly,the multi-source thermal model is used to analyze the dihadron azimuthal correlation in p-p collisions at (?)=7TeV and p-Pb collisions at (?)=5.02 TeV.The model results are in good agreement with the experimental data,The expansion and translation of the emission source in the momentum space are obtained.The results show that the expansion and translation of the source are the cause of the azimuthal anisotropy of final-state hadrons.Secondly,we apply Tsallis statistics to study the transverse momentum spectra of J/y mesons in p-p collisions at (?)=7,8,13 TeV and in p-Pb collisions at (?)=5 TeV.For comparison,we also discuss the transverse momentum distribution of ? mesons in p-p collisions at (?)=TeV in the framework of multi-source thermal model.In order to test the validity of the calculation,we consider different energies,different collisions,and different particles.The model can well describe the transverse momentum spectra of the final state particles in these collisions systems.It is found that the temperature of the emission source decreases with the increase of rapidity interval.The non-equilibrium degree q of the reaction system does not change significantly.