Super-acceleration from massless, minimally coupled phi(4)


Onemli V. K. , WOODARD R.

CLASSICAL AND QUANTUM GRAVITY, vol.19, no.17, pp.4607-4626, 2002 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 19 Issue: 17
  • Publication Date: 2002
  • Doi Number: 10.1088/0264-9381/19/17/311
  • Title of Journal : CLASSICAL AND QUANTUM GRAVITY
  • Page Numbers: pp.4607-4626

Abstract

We derive a simple form for the propagator of a massless, minimally coupled scalar in a locally de Sitter geometry of arbitrary spacetime dimension. We then employ it to compute the fully renormalized stress tensor at one- and two-loop orders for a massless, minimally coupled phi(4) theory which is released in Bunch-Davies vacuum at t = 0 in co-moving coordinates. In this system, the uncertainty principle elevates the scalar above the minimum of its potential, resulting in a phase of super-acceleration. With the non-derivative self-interaction the scalar's breaking of de Sitter invariance becomes observable. It is also worth noting that the weak-energy condition is violated on cosmological scales. An interesting subsidiary result is that cancelling overlapping divergences in the stress tensor requires a conformal counterterm which has no effect on purely scalar diagrams.