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

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.