Moduli/Inflaton Mixing with Supersymmetry Breaking Field

TL;DR

Heavy scalar fields such as moduli or inflatons generically mix with the SUSY-breaking field, altering their decays into gravitinos, SM particles, and hidden-sector states. The authors develop a mass-eigenstate formalism to map the model basis to the physical basis and derive decay rates for gravity- and gauge-mediated SUSY breaking, including the effects of the messenger sector in GMSB. They show that modulus decays often encounter gravitino overproduction and stringent BBN constraints, while inflaton decays can force a high reheating temperature via mixing-induced visible-sector decays, particularly in models with large inflaton mass or VEV; decays into the SUSY-breaking sector further complicate cosmology. The results highlight the need for symmetries that suppress φ–z mixing or alternative mediation schemes to maintain cosmological consistency, providing guidance for high-energy model building and inflation scenarios.

Abstract

A heavy scalar field such as moduli or an inflaton generally mixes with a field responsible for the supersymmetry breaking. We study the scalar decay into the standard model particles and their superpartners, gravitinos, and the supersymmetry breaking sector, particularly paying attention to decay modes that proceed via the mixing between the scalar and the supersymmetry breaking field. The impacts of the new decay processes on cosmological scenarios are also discussed; the modulus field generically produces too much gravitinos, and most of the inflation models tend to result in too high reheating temperature and/or gravitino overproduction.