Reheating in a Brane Monodromy Inflation Model

TL;DR

<3-5 sentence high-level summary> The paper analyzes reheating in a string-theory realization of brane monodromy inflation, where a D4-brane unwinds on a twisted torus and a D6-brane hosts Standard Model fields. It shows that repeated D4–D6 collisions during inflation do not trap the inflaton, and that reheating is governed by the final collision, yielding a high reheat temperature even after accounting for possible wound-string effects. Using a two-regime inflaton potential and an effective field theory of brane collisions, the authors quantify energy transfer to open-string modes and radiation, concluding that reheating is efficient and largely insensitive to earlier encounters. A concrete numerical example demonstrates that the final reheating scale remains near the grand unification/string scales, with only modest corrections from string production. The results support the viability of monodromy inflation scenarios and provide a framework for evaluating reheating in similar brane-based models.

Abstract

We study reheating in a recently proposed brane "monodromy inflation" model in which the inflaton is the position of a D4 brane on a "twisted torus". Specifically, we study the repeated collisions between the D4 brane and a D6 brane (on which the Standard Model fields are assumed to be localized) at a fixed position along the monodromy direction as the D4 brane rolls down its potential. We find that there is no trapping of the rolling D4 brane until it reaches the bottom of its potential, and that reheating is entirely described by the last brane encounter. Previous collisions have negligible effect on the brane velocity and hence on the reheat temperature. In the context of our setup, reheating is efficient and the reheat temperature is therefore high.