Fluctuations in the current and energy densities around a magnetic flux carrying cosmic string

TL;DR

This paper investigates quantum fluctuations in current and energy densities around a magnetic flux-carrying cosmic string, revealing that these fluctuations are generally large and significant for understanding cosmic string physics.

Contribution

It provides detailed calculations of fluctuations in current and energy densities for a quantized scalar field around cosmic strings, including finite temperature effects and arbitrary flux.

Findings

Fluctuations are of order unity relative to mean values.

Large fluctuations suggest significant quantum effects near cosmic strings.

Finite temperature effects analyzed for specific flux and deficit angle cases.

Abstract

We calculate the fluctuations in the current and energy densities for the case of a quantized, minimally coupled, massless, complex scalar field around a straight and infinitesimally thin cosmic string carrying magnetic flux. At zero temperature, we evaluate the fluctuations in the current and energy densities for arbitrary flux and deficit angle. At a finite temperature, we evaluate the fluctuations in the energy density for the special case wherein the flux is absent and the deficit angle equals $\pi$. We find that, quite generically, the dimensionless ratio of the variance to the mean-squared values of the current and energy densities are of order unity which suggests that the fluctuations around cosmic strings can be considered to be large.