Abstract
The transverse momentum distributions measured in $p-p$ collisions at the LHC
determine the kinetic freeze-out stage of the collision. The parameters deduced
from these distributions differ from those determined at chemical freeze-out.
The present investigation focuses on the chemical potentials at kinetic
freeze-out, these are not necessarily zero as they are at chemical freeze-out,
the only constraint is that they should be equal for particles and
antiparticles at LHC energies. The thermodynamic variables are determined in
the framework of the Tsallis distribution. The chemical potentials in the
Tsallis distribution analysis of $p-p$ collisions at four different LHC
energies have correctly been taken into account. This leads to a much more
satisfactory analysis of the various parameters and confirms the usefulness of
the Tsallis distribution in high-energy collisions. In particular we find that
the temperature $T$ and the volume $V$ at each beam energy are the same for all
particle types considered (pions, kaons and protons). The chemical potentials
for these particles are however very different. Hence we conclude that there is
evidence for thermal equilibrium at kinetic freeze-out, albeit in the sense of
the Tsallis distribution and there is no evidence for chemical equilibrium at
the final stage of the collision.
Citation
ID:
281886
Ref Key:
paradza2020determination