Gravity Waves and Gravitino Dark Matter in $\mu$-Hybrid Inflation

TL;DR

This paper introduces a new supersymmetric hybrid inflation model that addresses the $$ problem, predicts a lower bound on the tensor-to-scalar ratio, and explores gravitino dark matter within specific symmetry breaking scales.

Contribution

It presents a novel reformulation of $$-hybrid inflation using a specific Kahler potential, linking inflationary predictions with dark matter and symmetry breaking scales.

Findings

Lower bound on tensor-to-scalar ratio $r \,\gtrsim\, 0.004$

U(1) symmetry breaking scale between $10^8$ and $10^{12}$ GeV

Viable gravitino dark matter scenario with mass a few GeV

Abstract

We propose a novel reformulation of supersymmetric (more precisely $\mu$-) hybrid inflation based on a local U(1) or any suitable extension of the minimal supersymmetric standard model (MSSM) which also resolves the $\mu$ problem. We employ a suitable Kahler potential which effectively yields quartic inflation with non-minimal coupling to gravity. Imposing the gravitino Big Bang Nucleosynthesis (BBN) constraint on the reheat temperature ($T_r \lesssim 10^6$ GeV) and requiring a neutralino LSP, the tensor to scalar ratio ($r$) has a lower bound $r \gtrsim 0.004$. The U(1) symmetry breaking scale lies between $10^8$ and $10^{12}$ GeV. We also discuss a scenario with gravitino dark matter whose mass is a few GeV.