Theoretical constraints on brane inflation and cosmic superstring radiation

TL;DR

This paper examines the theoretical constraints on brane inflation models that produce cosmic superstrings and analyzes the limitations on their possible radiation, highlighting differences from field theory analogues.

Contribution

It provides a detailed analysis of supergravity constraints on brane inflation models and explores the allowed radiation mechanisms of cosmic superstrings in warped backgrounds.

Findings

D3/D7 and D3/anti-D3 inflation models can satisfy supergravity constraints.

Certain radiation channels for cosmic superstrings are forbidden or ill-defined in warped backgrounds.

Constraints differ significantly from those of field theoretical cosmic strings.

Abstract

We analyze theoretical constraints on the consistency of brane inflation leading to cosmic superstring formation and on the subsequent radiation of these cosmic superstrings. We first investigate the implications of recently elucidated supergravity constraints on models of brane inflation. We show that both D3/D7 and D3/anti-D3 brane inflation are subject to non-trivial constraints. Both models can be shown to satisfy those constraints, but for the case of D3/D7 there may be important consequences for the inflationary mechanism. We then analyze the strong theoretical constraints on the types of allowed radiation by cosmic superstrings, should they be formed; such constraints do not apply to their field theoretical analogues. We argue that in a warped background where one might expect axionic radiation to be enhanced relative to gravitational radiation, neithe F-strings nor D-strings can emit axionic radiation, while FD-strings cannot give rise to Neveu-Schwarz--Neveu-Schwarz particle emission, and their Ramond-Ramond particle emission is not well-defined.