Resonant decay of flat directions

Abstract

We study preheating, i.e., non-perturbative and resonant decay, of flatdirection fields, concentrating on MSSM flat directions and the right-handed sneutrino. The difference between inflaton preheating andflaton preheating is that the potential is more constrained in thelatter case. The effects of a complex driving field, quartic couplingsin the potential, and the presence of a thermal bath are important andcannot be neglected. Preheating of MSSM flat directions is typicallydelayed due to out-of-phase oscillations of the real and imaginarycomponents and may be preceded by perturbative decay or Q-ballformation. Particle production due to the violation of adiabaticityis expected to be inefficient due to backreaction effects. For asmall initial sneutrino VEV, ⟨N⟩≲mN/h withmN the mass of the right-handed sneutrino and h a Yukawacoupling, there are tachyonic instabilities. The D-term quarticcouplings do not generate an effective mass for the tachyonic modes,making it an efficient decay channel. It is unclear how thermalscattering affects the resonance.