SPONTANEOUS SYMMETRY-BREAKING AND THE DISSIPATION OF NUCLEAR COLLECTIVE DEGREES OF FREEDOM AT FINITE-TEMPERATURE

The critical temperature for the dissipation of the collective degrees of freedom has been determined in a quantum field theoretical descrip tion of the Elliott model in which the U(3) symmetry is spontaneously broken in such a manner that rotational invariance is preserved. Resul ts for Ne-20, with a reasonable choice of parameters, seem to indicate that this critical temperature lies below the liquid-to-gas critical temperature but above the temperature of deformed-to-spherical shape t ransitions which have been observed in finite temperature mean field c alculations.