Vacuum fluctuations in a supersymmetric model in FRW spacetime

TL;DR

This paper investigates vacuum fluctuations in a supersymmetric model within an expanding FRW universe, linking soft supersymmetry breaking to vacuum energy and cosmological constant, and deriving an effective equation of state.

Contribution

It introduces a selfconsistent approach to relate vacuum fluctuations, supersymmetry breaking, and dark energy without fine tuning.

Findings

Vacuum energy density is comparable to the observed cosmological constant.

Effective equation of state depends on the cutoff choice but requires no fine tuning.

Soft supersymmetry breaking induces a nonzero vacuum energy contribution.

Abstract

We study a noninteracting supersymmetric model in an expanding FRW spacetime. A soft supersymmetry breaking induces a nonzero contribution to the vacuum energy density. A short distance cutoff of the order of Planck length provides a scale for the vacuum energy density comparable with the observed cosmological constant. Assuming the presence of a dark energy substance in addition to the vacuum fluctuations of the field an effective equation of state is derived in a selfconsistent approach. The effective equation of state is sensitive to the choice of the cut-off but no fine tuning is needed.