Tribrid Inflation in Supergravity

TL;DR

This paper introduces a new class of supergravity-based tribrid inflation models that resolve the eta-problem using symmetries, featuring a third 'driving' field and quantum corrections that align with observational data.

Contribution

It presents a novel tribrid inflation framework in supergravity with symmetry-based eta-problem resolution and a unique three-field setup, including a 'driving' field, with quantum corrections producing realistic spectral tilt.

Findings

The model resolves the eta-problem using Heisenberg or shift symmetry.

Quantum corrections generate a spectral tilt consistent with WMAP.

The inflationary superpotential vanishes during inflation, simplifying dynamics.

Abstract

We propose a novel class of F-term hybrid inflation models in supergravity (SUGRA) where the $\eta$-problem is resolved using either a Heisenberg symmetry or a shift symmetry of the Kaehler potential. In addition to the inflaton and the waterfall field, this class (referred to as tribrid inflation) contains a third 'driving' field which contributes the large vacuum energy during inflation by its F-term. In contrast to the ''standard'' hybrid scenario, it has several attractive features due to the property of vanishing inflationary superpotential (W_inf=0) during inflation. While the symmetries of the Kaehler potential ensure a flat inflaton potential at tree-level, quantum corrections induced by symmetry breaking terms in the superpotential generate a slope of the potential and lead to a spectral tilt consistent with recent WMAP observations.