Nonperturbative effects of vacuum energy on the recent expansion of the universe

摘要: We show that the vacuum energy of a free quantized field very low mass can significantly alter recent expansion universe. The effective action theory is obtained from non-perturbative sum scalar curvature terms in propagator. numerically investigate semiclassical Einstein equations derived it. As result quantum effects, matter-dominated universe stops decreasing and approaches constant value. our model evolves an open epoch to mildly inflating de Sitter expansion. Hubble during present epoch, as well time at which transition occurs expansion, are determined by matter density. provides theoretical explanation observed acceleration universe, gives good fit data high-redshift Type Ia supernovae, with about 10^{-33} eV, current ratio density critical density, Omega_0 <0.4 . age then follows no further parameters theory, turns out be greater than 13 Gyr. spatially consistent possibility inflation early Furthermore, arises standard renormalizable curved spacetime, does not require cosmological or associated fine-tuning.