2 research outputs found
Consistent modified gravity: dark energy, acceleration and the absence of cosmic doomsday
We discuss the modified gravity which includes negative and positive powers
of the curvature and which provides the gravitational dark energy. It is shown
that in GR plus the term containing negative power of the curvature the cosmic
speed-up may be achieved, while the effective phantom phase (with less than
-1) follows when such term contains the fractional positive power of the
curvature. The minimal coupling with matter makes the situation more
interesting: even 1/R theory coupled with the usual ideal fliud may describe
the (effective phantom) dark energy. The account of term (consistent
modified gravity) may help to escape of cosmic doomsday.Comment: LaTeX file, 9 pages, based on the talk given by S.D. Odintsov (Int.
Conference Mathematical Methods in Physics, Rio de Janeiro, Augest, 2004), to
appear in CQG, Letter
One-loop f(R) gravity in de Sitter universe
Motivated by the dark energy issue, the one-loop quantization approach for a
family of relativistic cosmological theories is discussed in some detail.
Specifically, general gravity at the one-loop level in a de Sitter
universe is investigated, extending a similar program developed for the case of
pure Einstein gravity. Using generalized zeta regularization, the one-loop
effective action is explicitly obtained off-shell, what allows to study in
detail the possibility of (de)stabilization of the de Sitter background by
quantum effects. The one-loop effective action maybe useful also for the study
of constant curvature black hole nucleation rate and it provides the plausible
way of resolving the cosmological constant problem.Comment: 25 pages, Latex file. Discussion enlarged, new references added.
Version accepted in JCA