Revisiting Cosmic No-Hair Theorem for Inflationary Settings
  In this work we revisit Wald's cosmic no-hair theorem in the context of
accelerating Bianchi cosmologies for a generic cosmic fluid with non-vanishing
anisotropic stress tensor and when the fluid energy momentum tensor is of the
form of a cosmological constant term plus a piece which does not respect strong
or dominant energy conditions. Such a fluid is the one appearing in
inflationary models. We show that for such a system anisotropy may grow, in
contrast to the cosmic no-hair conjecture. In particular, for a generic
inflationary model we show that there is an upper bound on the growth of
anisotropy. For slow-roll inflationary models our analysis can be refined
further and the upper bound is found to be of the order of slow-roll
parameters. We examine our general discussions and our extension of Wald's
theorem for three classes of slow-roll inflationary models, generic
multi-scalar field driven models, anisotropic models involving U(1) gauge
fields and the gauge-flation scenario.
