DIBARYONS IN NUCLEAR-MATTER

The possibility for the occurrence of a Bose condensate of dibaryons i n nuclear matter is investigated within the framework of the Walecka m odel in the mean-field approximation. The effect of sigma- and pi-meso n exchange current contributions on the sigma-dibaryon coupling consta nt is discussed. The mean-field solutions of the model are constructed . The effective nucleon mass m(N) vanishes when the density of dibary ons approaches a critical value rho(DV)(c,max)approximate to 0.15 fm(- 3). The Green functions of the equilibrium binary mixture of nucleons and dibaryons are constructed by solving the Gorkov-Dyson system of eq uations in the no-loop approximation. We find that when the square of the sound velocity is positive, the dispersion laws for ail elementary excitations of the system are real functions.