The spontaneous agitation of collective modes in unstable nuclear matter is addressed with an extended Boltzmann-Langevin (BL) theory that incorporates a memory time in the stochastic force. The growth of the modes is then governed by effective diffusion coefficients which are renormalized by time-dependent factors, relative to the standard treatment. These correction factors deviate significantly from unity in the most unstable domain of the density-temperature phase plane, indicating the importance of including a memory time in numerical BL simulations of nuclear dynamics.

• Received 13 July 1994

DOI:https://doi.org/10.1103/PhysRevC.50.2947