Vacuum polarization by a global monopole with finite core

TL;DR

This paper studies how a finite-sized global monopole core influences quantum scalar fields, deriving formulas for vacuum expectation values and analyzing their behavior in various regimes, including strong gravitational fields.

Contribution

It provides new analytical expressions for vacuum densities around a finite core monopole and examines their asymptotic behaviors, including a specific flower-pot core model.

Findings

Vacuum densities differ significantly near the core and at large distances.

Behavior varies drastically between minimally and non-minimally coupled fields.

Explicit inside-core expectation values are calculated for the flower-pot model.

Abstract

We investigate the effects of a $(D+1)$-dimensional global monopole core on the behavior of a quantum massive scalar field with general curvature coupling parameter. In the general case of the spherically symmetric static core, formulae are derived for the Wightman function, for the vacuum expectation values of the field square and the energy-momentum tensor in the exterior region. These expectation values are presented as the sum of point-like global monopole part and the core induced one. The asymptotic behavior of the core induced vacuum densities is investigated at large distances from the core, near the core and for small values of the solid angle corresponding to strong gravitational fields. In particular, in the latter case we show that the behavior of the vacuum densities is drastically different for minimally and non-minimally coupled fields. As an application of general results the flower-pot model for the monopole's core is considered and the expectation values inside the core are evaluated.