5 research outputs found
Nonequilibrium dynamics in scalar hybrid models
We study by numerical simulations the transition from the metastable "false
vacuum" to the broken symmetry phase in the preheating stage after cosmic
inflation in a scalar hybrid model. We take quantum fluctuations and their back
reaction into account by applying a one-loop bubble-resummation.Comment: 5 pages, 4 figures, contribution to the conference Strong and
Electroweak Matter (SEWM2004), Helsinki, Finland, 16-19 June 200
Scalar O(N) Model at Finite Temperature -- 2PI Effective Potential in Different Approximations
We calculate the two-particle irreducible (2PI) effective potential of the
O(N) linear sigma model in 1+1 dimensions. The approximations we use are the
next-to-leading order of a 1/N expansion (for arbitrary N) and a kind of
"resummed loop approximation" for N=1. We show that the effective potential of
the 1/N expansion is convex for N=4 and N=10 whereas it is not for the "loop"
expansion and the case N=1 of the 1/N expansion.Comment: LaTeX, 5 pages. Contribution to the Proceedings of 6th Conference on
Strong and Electroweak Matter 2004 (SEWM04), Helsinki, Finland, 16-19 Jun
200
One-loop corrections to the Nielsen-Olesen vortex: collective oscillations
We connect the translation modes of the instanton in the two-dimensional
Abelian Higgs model with local translations of the vortex of the related model
in (3+1) dimensions, the Nielsen-Olesen vortex. In this context these modes
describe collective oscillations of the string. We construct the wave function
of this mode and we derive, via a virial theorem, an effective action for these
oscillations, which is consistent with the action constructed by Nielsen and
Olesen using general arguments. We discuss some aspects of renormalization,
based on a recent computation of one loop corrections to string tension of the
vortex.Comment: 18 pages, 1 figur