Equation of state of a relativistic interacting nucleon-antinucleon system

In the framework of the S-matrix formulation of statistical mechanics of Dashen, Ma and Bernstein the contribution of strong interaction to the thermodynamic potential of the NN-system is obtained by using a Regge-type two-particle interaction amplitude. It is shown that the forces due to the exchange of f, ω reggeons result in a negative contribution to the pressure at a temperature of order 10 GeV. The contribution to the pressure due to the pomeron exchange dominates when the temperature exceeds 100 GeV. Owing to the fact that the negative contribution to the pressure becomes large in absolute value at some temperatures, there appears a temperature region where the system is thermodynamically unstable