Monday, March 5, 2012

1109.4892 (Hiroyuki Kitamoto et al.)

Infra-red effects of Non-linear sigma model in de Sitter space    [PDF]

Hiroyuki Kitamoto, Yoshihisa Kitazawa
We extend our investigation on a possible de Sitter symmetry breaking mechanism in non-linear sigma models. The scale invariance of the quantum fluctuations could make the cosmological constant time dependent signaling the de Sitter symmetry breaking. To understand such a symmetry breaking mechanism, we investigate the energy-momentum tensor. We show that the leading infra-red logarithms cancel to all orders in perturbation theory in a generic non-linear sigma model. When the target space is an N sphere, the de Sitter symmetry is preserved in the large N limit. For a less symmetric target space, the infra-red logarithms appear at the three loop level. However there is a counter term to precisely cancel it. The leading infra-red logarithms do not cancel for higher derivative interactions. We investigate such a model in which the infra-red logarithms first appear at the three loop level. A nonperturbative investigation in the large N limit shows that they eventually grow as large as the one loop effect.
View original: http://arxiv.org/abs/1109.4892

No comments:

Post a Comment