Multiple Fields in Stochastic Inflation

摘要: Stochastic effects in multi-field inflationary scenarios are investigated. A hierarchy of diffusion equations is derived, the solutions which yield moments numbers e-folds. Solving resulting partial differential multi-dimensional field space more challenging than single-field case. few tractable examples discussed, show that number fields is, general, a critical parameter. When two present for instance, probability to explore arbitrarily large-field regions potential, otherwise inaccessible dynamics, becomes non-zero. In some configurations, this gives rise an infinite mean e-folds, regardless initial conditions. Another difference with respect stochastic can be large even at sub-Planckian energy. This opens interesting new possibilities probing quantum since e-folds used calculate distribution primordial density perturbations stochastic-δ N formalism.