Extended Inflation from Strings

TL;DR

This paper explores the potential for extended inflation within string-inspired models, highlighting how supersymmetry breaking mechanisms influence inflation dynamics and bubble formation.

Contribution

It demonstrates that the $$-problem in extended inflation can be resolved through small bubble production, and identifies conditions for the inflaton's origin in string spectra.

Findings

Small bubble production solves the -problem.

Inflaton can originate from untwisted or twisted sectors.

Supersymmetry breaking impacts inflation viability.

Abstract

We study the possibility of extended inflation in the effective theory of gravity from strings compactified to four dimensions and find that it strongly depends on the mechanism of supersymmetry breaking. We consider a general class of string--inspired models which are good candidates for successful extended inflation. In particular, the $\omega$--problem of ordinary extended inflation is automatically solved by the production of only very small bubbles until the end of inflation. We find that the inflaton field could belong either to the untwisted or to the twisted massless sectors of the string spectrum, depending on the supersymmetry breaking superpotential.