Particle Transverse Momentum Distributions in p-p Collisions at √sNN=0.9 TeV

Inam-Ul Bashir,Riyaz Ahmed Bhat,Saeed Uddin,Rameez Ahmad Parra

doi:10.1155/2019/8219567

Abstract

The midrapidity transverse momentum spectra of hadrons (p, K+, Ks0, ϕ, Λ, and (Ξ-+Ξ--)) and the available rapidity distributions of the strange hadrons (Ks0, (Λ+Λ-), (Ξ-+Ξ--)) produced in p-p collisions at LHC energy √sNN = 0.9 TeV have been studied using a Unified Statistical Thermal Freeze-out Model (USTFM). The calculated results are found to be in good agreement with the experimental data. The theoretical fits of the transverse momentum spectra using the model calculations provide the thermal freeze-out conditions in terms of the temperature and collective flow parameters for different hadronic species. The study reveals the presence of a significant collective flow and a well-defined temperature in the system thus indicating the formation of a thermally equilibrated hydrodynamic system in p-p collisions at LHC. Moreover, the fits to the available experimental rapidity distributions data of strange hadrons show the effect of almost complete transparency in p-p collisions at LHC. The model incorporates longitudinal as well as a transverse hydrodynamic flow. The contributions from heavier decay resonances have also been taken into account. We have also imposed the criteria of exact strangeness conservation in the system.

Highlights

Within the framework of the statistical hadronization model it is assumed that initially a fireball, i.e., a hot and dense matter of the partons, is formed over an extended region after the collision
The quarks and gluons in the fireball may be nearly free due to the ultraviolet freedom, i.e., in a quark gluon plasma (QGP) phase. This fireball undergoes a collective expansion accompanied by further particle production processes through the secondary collisions of quarks and gluons which leads to a decrease in its temperature
The expansion reaches a point where quarks and gluons start interacting nonperturbatively leading to the confinement of quarks and gluons through the formation of hadrons, i.e., the so called hadronization process. In this hot matter which is in the form of a gas of hadronic resonances at high temperature and density, the hadrons continue to interact thereby producing more hadrons and the bulk matter expands further due to a collective hydrodynamic flow developed in the system

Summary

Introduction

Within the framework of the statistical hadronization model it is assumed that initially a fireball, i.e., a hot and dense matter of the partons (quarks and gluons), is formed over an extended region after the collision. The expansion reaches a point where quarks and gluons start interacting nonperturbatively leading to the confinement of quarks and gluons through the formation of hadrons, i.e., the so called hadronization process In this hot matter which is in the form of a gas of hadronic resonances at high temperature and density, the hadrons continue to interact thereby producing more hadrons and the bulk matter expands further due to a collective hydrodynamic flow developed in the system. Within the framework of the statistical model, the system formed out of a heavy-ion collision is assumed to be in Advances in High Energy Physics thermal and chemical equilibrium at the final freeze-out stage. We have employed the strangeness conservation criteria such that the net strangeness in the system is zero

Rapidity Spectra

Transverse Momentum Spectra

Summary and Conclusion