Supersymmetric Hybrid Inflation Redux

TL;DR

This paper explores how a soft supersymmetry breaking term in hybrid inflation models influences predictions, enabling alignment with observational data and addressing the MSSM mu problem, while predicting very small tensor-to-scalar ratios.

Contribution

It demonstrates that including a specific soft supersymmetry breaking term allows hybrid inflation models to match observed spectral index values and resolve the MSSM mu problem.

Findings

The soft term adjusts the spectral index to match WMAP5 data.

Without the soft term, n_s >= 0.985, inconsistent with observations.

Tensor-to-scalar ratio r is predicted to be very small, r <= 10^{-5}.

Abstract

We discuss the important role played during inflation by one of the soft supersymmetry breaking terms in the inflationary potential of supersymmetric hybrid inflation models. With minimal Kaehler potential, the inclusion of this term allows the prediction for the scalar spectral index to agree with the value n_s = 0.963^{+0.014}_{-0.015} found by WMAP5. In the absence of this soft term, and by taking into account only radiative and supergravity corrections, it is well known that n_s >= 0.985. This same soft term has previously been shown to play a key role in resolving the MSSM mu problem. The tensor to scalar ratio r is quite small in these models, taking on values r <= 10^{-5} in the WMAP5 2-sigma range of n_s.