Dilaton and off-shell (non-critical string) effects in Boltzmann   equation for species abundances
  In this work we derive the modifications to the Boltzmann equation governing the cosmic evolution of relic abundances induced by dilaton dissipative-source and non-critical-string terms in dilaton-driven non-equilibrium string Cosmologies. We also discuss briefly the most important phenomenological consequences, including modifications of the constraints on the available parameter space of cosmologically appealing particle physics models, imposed by recent precision data of astrophysical measurements. 
A.B. Lahanas, N.E. Mavromatos and D.V. Nanopoulos