Quantum Fluctuations of Scalar Field in Conical Space

TL;DR

This paper investigates the quantum fluctuations of a scalar field around a cosmic string and demonstrates that semiclassical gravity calculations may be invalid in certain regions due to large fluctuations.

Contribution

It provides an analysis of quantum fluctuations in conical space and highlights limitations of semiclassical gravity in this context.

Findings

Quantum fluctuations are large near the cosmic string.

Semiclassical gravity may not be valid in regions with significant quantum fluctuations.

The study emphasizes the need for alternative approaches in such regions.

Abstract

We consider vacuum polarization effect of a conformally coupled massless scalar field in the background produced by an idealized straight cosmic string. Using previous criterion we show the calculation of back reaction of the field to the metric in the context of semiclassical gravity theory is not valid , in some regions due to large quantum fluctuations in the conical space.