Abelian cosmic string in the Starobinsky model of gravity

TL;DR

This paper numerically investigates Abelian cosmic strings within the Starobinsky gravity model, highlighting how the quadratic term influences spacetime properties and comparing results with Einstein gravity.

Contribution

It introduces a numerical analysis of Abelian strings in the Starobinsky model, emphasizing the impact of the quadratic R^2 term on spacetime structure.

Findings

Angular deficit decreases as the parameter η increases.

Spacetime remains well-behaved for a wide range of symmetry-breaking scales.

Comparison with Einstein gravity shows notable differences in string properties.

Abstract

In this paper, I analyze numerically the behaviour of the solutions corresponding to an Abelian string in the framework of the Starobinsky model. The role played by the quadratic term in the Lagrangian density $f(R) = R + \eta R^2$ of this model is emphasized and the results are compared with the corresponding ones obtained in the framework of Einstein's theory of gravity. I have found that the angular deficit generated by the string is lowered as the $\eta$ parameter increases, allowing a well-behaved spacetime for a large range of values of the symmetry-breaking scale.