Braneworld inflation

TL;DR

The paper addresses how to realize four-dimensional braneworld inflation within warped string-theory throats by treating the inflaton as the radial position of a $D_p$ probe brane. It develops and analyzes local de-Sitter deformed throat geometries, focusing on $D3$-brane and wrapped $D5$-brane scenarios, and employs a five-dimensional gauged supergravity framework with ten-dimensional uplifts to study slow-roll conditions. The main finding is that slow-roll inflation with small $\eta$ is achievable in de-Sitter deformed ${\cal N}=2^*$ throats for certain IR data, while wrapped MN and GKMW backgrounds fail to produce viable slow-roll ($\eta \ge 1$). The results highlight the role of conformal-symmetry breaking scales $\mu$ and potential cosmological phase transitions in throat geometries, informing which warped-throat embeddings are viable for brane inflation.

Abstract

We discuss various realizations of the four dimensional braneworld inflation in warped geometries of string theory. In all models the inflaton field is represented by a Dp probe brane scalar specifying its position in the warped throat of the compactification manifold. We study existing inflationary throat local geometries, and construct a new example. The inflationary brane is either a D3- or a D5-brane of type IIB string theory. In the latter case the inflationary brane is wrapping a two-cycle of the compactification manifold. We discuss some phenomenological aspects of the model where slow-roll conditions are under computational control.

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