Statistical Approaches to High Energy Physics: Chemical and Thermal Freeze-Outs

We present an overview of a proposal in relativistic proton-proton (pp) collisions emphasizing the thermal or kinetic freeze-out stage in the framework of the Tsallis distribution. In this paper we take into account the chemical potential present in the Tsallis distribution by following a two step procedure. In the first step we used the redudancy present in the variables such as the system temperature, T, volume, V, Tsallis exponent, q, chemical potential, &mu
and performed all fits by effectively setting to zero the chemical potential. In the second step the value q is kept fixed at the value determined in the first step. This way the complete set of variables T,q,V and &mu
can be determined. The final results show almost no (or at best a very weak) energy dependence in pp collisions at the centre-of-mass energy s=20 TeV to 13 TeV. The chemical potential &mu
at kinetic freeze-out shows a steep increase with beam energy. This considerably simplifies the description of the thermal freeze-out stage in pp collisions as the values of T and of the freeze-out radius R remain constant to a good approximation over a wide range of beam energies.