  We consider thermodynamic properties of a quark-gluon plasma related to
quasiparticles having the internal structure. For this purpose, we employ a
possible analogy between quantum chromodynamics and non-Abelian
Proca-Dirac-Higgs theory. The influence of characteristic sizes of the
quasiparticles on such thermodynamic properties of the quark-gluon plasma like
the internal energy and pressure is studied. Sizes of the quasiparticles are
taken into account in the spirit of the van der Waals equation but we take into
consideration that the quasiparticles have different sizes, and the average
value of these sizes depends on temperature. It is shown that this results in a
change in the internal energy and pressure of the quark-gluon plasma. Also, we
show that, when the temperature increases, the average value of characteristic
sizes of the quasiparticles increases as well. This leads to the occurrence of
a phase transition at the temperature at which the volume occupied by the
quasiparticles is compared with the volume occupied by the plasma.

High Energy Physics - Phenomenology;High Energy Physics - Theory