Thermal Inflation with Flaton Chemical Potential

TL;DR

This paper explores a thermal inflation model driven by a flaton field with a chemical potential, allowing for higher reheating temperatures that enable thermal leptogenesis, thus addressing the cosmological moduli problem more effectively.

Contribution

It introduces a flaton chemical potential into thermal inflation models, identifying parameter regions that solve the moduli problem and permit higher reheating temperatures for leptogenesis.

Findings

Negative flaton mass squared naturally arises with chemical potential.

Allowed parameter space for chemical potential and self-coupling is identified.

Reheating temperature can be sufficiently high for thermal leptogenesis.

Abstract

Thermal inflation driven by a scalar field called "flaton" is a possible scenario to solve the cosmological moduli problem. We study a model of thermal inflation with a flaton chemical potential. In the presence of the chemical potential, a negative mass squared of the flaton, which is necessary to terminate the thermal inflation, is naturally induced. We identify the allowed parameter region for the chemical potential ($\mu$) and the flaton self-coupling constant to solve the cosmological moduli problem and satisfy theoretical consistencies. In general, the chemical potential is a free parameter and it can be taken to be much larger than the typical scale of soft supersymmetry breaking parameters of $\mathcal{O} (1)$ TeV. For $\mu \gtrsim 10^8$ GeV, we find that the reheating temperature after the thermal inflation can be high enough for the thermal leptogenesis scenario to be operative. This is in sharp contrast to the standard thermal inflation scenario, in which the reheating temperature is quite low and a special mechanism is necessary for generating sufficient amount of baryon asymmetry in the Universe after thermal inflation.