Stochastic semiclassical cosmological models

ANTONIO CAMPOS; ENRIC VERDAGUER; ESTEBAN CALZETTA

PHYSICAL REVIEW D - PARTICLE AND FILDS

APS

Año: 1997 vol. 56 p. 2163 - 2172

0556-2821

We consider the classical stochastic fluctuations of spacetime geometry induced by quantum fluctuations of massless nonconformal matter fields in the early Universe. To this end, we supplement the stress-energy tensorof these fields with a stochastic part, which is computed along the lines of the Feynman-Vernon and Schwinger-Keldysh techniques; the Einstein equation is therefore upgraded to a so-called Einstein-Langevinequation. We consider in some detail the conformal fluctuations of flat spacetime and the fluctuations of the scale factor in a simple cosmological model introduced by Hartle, which consists of a spatially flat isotropic cosmology driven by radiation and dust.