GUT-Scale Smooth Hybrid Inflation with a Stabilized Modulus in Light of ACT and SPT Data

TL;DR

This paper develops a generalized smooth hybrid inflation model within the MSSM framework, addressing the eta problem and aligning with recent ACT and SPT data through specific supergravity constructions.

Contribution

It introduces two supergravity-based implementations of smooth F-term hybrid inflation that solve the eta problem and are compatible with current cosmological data.

Findings

Model aligns with ACT and SPT data

Uses shift-symmetric and hyperbolic Kähler potentials

Ensures monotonic inflationary potential

Abstract

We analyze a generalized framework of smooth F-term hybrid inflation (smFHI) consistent with gauge coupling unification within the Minimal Supersymmetric Standard Model (MSSM). The embedding of the model in two specific Supergravity settings addresses at the same time the $\eta$ problem and the compatibility with the recent ACT or SPT data. The one relies on the choice of a shift-symmetric K\"ahler potential for the inflaton which revitalizes the SUSY predictions of smFHI, whereas the other employs a K\"ahler potential associated with an hyperbolic K\"ahler manifold. An essential role in both our constructions is played by a decoupled superheavy field without superpotential and Kaehler potential inspired by string- and D-brane--based models. Our proposal can be realized for a variety of representations for the Higgs fields involved in smFHI and assures monotonic inflationary potential.