Research On The Final State Particle Spectrum Of High-energy Heavy Ion Collisions Based On The TBW Model

The high-energy heavy ion collision experiment provides the possibility to understand the production and evolution of matter after the explosion of the universe.The transverse momentum(pT)spectrum of the identified particles is one of the important observables in high-energy heavy ion collision experiments.The study of pT spectrum is useful to understand the formation mechanism of the particles production.The Boltzmann blast-wave model is widely used to study the spectra of identified particles.In this model,the shape of the spectra depends on two physical parameters:the dynamic freeze-out temperature T and the mean transverse velocity.However,this model has some limitations.In the low pT range,the transverse momentum spectra of particles can be reproduced well,while in the high pT region,the model deviates greatly from the experimental data.The Boltzmann blast-wave model assumes that the initial state of evolution is in equilibrium,but there is a certain fluctuation in reality.In order to take the initial state fluctuation into account,the distribution of particle emission sources is changed from the Boltzmann distribution to the Tsallis distribution,in which the non-extensive parameter q describes the degree of deviation for the system from equilibrium.It has been found that the Tsallis blast-wave model(TBW)can well describe the spectra of the identified particles at the Au-Au collisions at RHIC up to 3 GeV/c.In this paper,the TBW model is used to investigate the pT spectra of light hadrons in Pb-Pb(Pb-Pb,Xe-Xe,p-Pb)collisions at 2.76(5.02,5.44,5.02)TeV.Two types of transverse velocity profiles are considered:one is the linear velocity profile,in which the transverse velocity linearly depends on the radius of the emitting source.The other one is the constant velocity profile,whose transverse velocity does not rely on the radius of the source.It is found that the TBW model with both profiles can describe the spectra of the identified particles to 3GeV/c well.The transverse average velocity increases with the collision centrality,while the non-extensive parameter shows an opposite trend.In addition,in central collisions,the transverse velocity and non-extensive parameter(Tsallis temperature T)from the fit with the linear profile are smaller(large)than those with the constant profile.In peripheral collisions,the parameters from the TBW model with both profiles are consistent within the error.In order to investigate whether the light nuclei freeze out earlier than light hadrons,the transverse momentum spectrum of the light nuclei in central Pb-Pb(p-Pb)collisions at 2.76(5.02)TeV is studied in order to investigate freeze-out picture of the light nuclei and the light hadrons.In addition,in order to check whether a scenario of an early freeze-out of strange particles at the LHC exists,the particle spectra are investigated by grouping them into strange and non-strange hadrons.Finally,the TBW model with the constant velocity profle is used to explore the spectra of final state particles in Au-Au collisons at the center-of-mass energy ranging from 7.7 to 39 GeV.This study can help us to reveal the effects of the collision energy and the size of the collision system on the particles production.