Vacuum polarization by a composite topological defect

TL;DR

This paper investigates quantum effects of a scalar field caused by a combined topological defect involving a cosmic string and a global monopole, analyzing vacuum polarization in higher-dimensional spacetime.

Contribution

It provides a detailed analysis of one-loop quantum effects induced by a composite topological defect in higher dimensions, including explicit Green function construction.

Findings

Green function expressed as a sum of bulk and defect-induced terms

Finite vacuum expectation values away from defect cores

Quantitative insights into vacuum polarization effects in complex topological backgrounds

Abstract

In this paper we analyze one-loop quantum effects of a scalar field induced by a composite topological defect consisting a cosmic string on a p-dimensional brane and a (m+1)-dimensional global monopole in the transverse extra dimensions. The corresponding Green function is presented as a sum of two terms. The first one corresponds to the bulk where the cosmic string is absent and the second one is induced by the presence of the string. For the points away from the cores of the topological defects the latter is finite in the coincidence limit and is used for the evaluation of the vacuum expectation values of the field square and energy-momentum tensor.