Cosmic adventures in stringland: Scattering of bosonic and fermionic fields in gravitating cosmic string spacetimes

TL;DR

This paper develops a modified partial-wave approach to analyze scalar, fermionic, and bosonic field scattering in gravitating cosmic string spacetimes, revealing oscillatory cross-section behaviors due to spacetime structure.

Contribution

It introduces a new asymptotic ansatz for scattering in conical spacetimes and applies it to various fields, providing explicit formulas and insights into oscillatory cross-sections.

Findings

Standard partial-wave scattering amplitude is singular in cosmic string spacetimes.

Modified asymptotic ansatz resolves divergence issues.

Cross-sections exhibit damped oscillations linked to spacetime structure.

Abstract

We show that when considering a scalar field scattering in a gravitating cosmic string spacetime, the standard partial-wave approach's scattering amplitude is singular. In order to avoid the divergence caused by the spacetime asymptotically conical structure, we propose a modification of the asymptotic ansatz in the partial-wave formalism and find the corrections in the phase-shift and total scattering cross-section. We also developed a toy model for the spacetime metric of a cosmic string and showed how local interaction with the vortex gauge field affects the scalar field total cross-section. Then we apply this formalism to a Dirac field and show the explicit formula for the fermionic total cross-section. Finally, we study the scattering of bosonic and fermionic fields in the spacetime of an abelian and a nonabelian gravitating cosmic strings and show that the cross-sections have damped oscillations. In order to understand the origin of this behavior, we used the aforementioned toy model to show that the spacetime particular asymptotical structure causes the observed oscillations.