Rate of particle production in gravitational fields

Zel'dovich Ya.B. , Starobinskii A.A.

The local rate of production of massless particles is calculated in a weakly anisotropic homogeneous cosmological model, and also in a weak inhomogeneous gravitational field, in which the condition *q%> *0 is satisfied for the wave vectors of the nonzero Fourier components in second-order perturbation theory. The rate turns out to be proportional to the local values of the invariants of the curvature tensor.