Spectral temperature of π− mesons in proton–carbon interactions at 4.2 GeV/c in the framework of UrQMD model

Transverse momentum [Formula: see text] spectra of [Formula: see text] mesons calculated using ultra-relativistic quantum molecular dynamic (UrQMD) model (Latest version 3.3-p2) simulations have been compared with [Formula: see text] spectra of [Formula: see text] mesons, obtained experimentally in interactions of protons beam with carbon nuclei (propane as target) at momentum of 4.2 GeV/c. Spectral temperatures of negative pions obtained in experimental and UrQMD model simulated interactions of protons beam with carbon nuclei have been calculated by fitting both spectra with four different fitting functions, i.e. Hagedorn thermodynamic, Boltzmann distribution, Gaussian and exponential functions. These functions are used commonly for describing hadron spectra and their spectral temperatures. Hagedorn thermodynamic function has been recommended as the most suitable function to extract the temperature of negative pions at above momentum among these four functions.

Rapidity Distribution of Charged Pions From Pb+Pb and Au+Au Central Collisions

Rapidity distributions for charged pions produced from central collisions Pb+Pb and Au+Au at (b ≤ 3.4 fm.) in range of energy 2 GeV up to  = 200 GeV are investigated. The experimental results are studied  in terms of the Ultra-relativistic Quantum Molecular Dynamic Model Ur-QMD. In general, the model can give suitable predictions of rapidity distributions for production of charged pions from interactions with energies below 160 A GeV. This model is supported the assumption that the onset of de-confinement is located at low energies. It treats the initial nucleon-nucleon interactions within a string-hadronic framework. In addition, it includes effects such as string-string interactions and hadronic re-scattering that expected to be relevant in A+A collisions. There is a kind of similarity for mechanism responsible for production of the two charge states of pions and it can extended to other hadrons. Ultra-relativistic quantum molecular dynamic model give good description on energy dependence for charged pion productions and points of maximum rapidity.Â