[Paper Review] Resonant decay of flat directions: applications to curvaton scenarios, Affleck-Dine baryogenesis, and leptogenesis from a sneutrino condensate

Marieke Postma, Anupam Mazumdar|arXiv (Cornell University)|Apr 25, 2003

Quantum, superfluid, helium dynamics4 citations

TL;DR

This paper investigates resonant decay (preheating) of flat directions in supersymmetric models, particularly in the context of a sneutrino condensate, showing that non-perturbative, out-of-equilibrium processes lead to exponential growth of decay quanta and condensate fragmentation. This has key implications for leptogenesis and curvaton scenarios, where early curvaton decay may produce excessive non-Gaussianity, and for MSSM flat directions, where preheating is delayed by out-of-phase oscillations.

ABSTRACT

We investigate the possibility of resonant decay, or preheating, of various flat directions. Preheating is unimportant for fields with only Planck suppressed couplings, such as moduli. It occurs naturally in the context of a sneutrino condensate. This has important implications for leptogenesis and curvaton scenarios based on such a condensate. Exponential growth of decay quanta, and subsequent scatterings, lead to fragmentation of the condensate. This is a non-perturbative, out-of-equilibrium process, making predictions for the final lepton asymmetry highly non-trivial. In the curvaton scenario, early decay of the curvaton may give rise to significant non-Gaussianity of the density perturbations, in conflict with experiment. Preheating of MSSM flat directions is typically delayed due to out-of-phase oscillations of the real and imaginary components.

Motivation & Objective

• To examine whether resonant decay (preheating) of flat directions can occur in models involving a sneutrino condensate.
• To assess the impact of non-perturbative, out-of-equilibrium dynamics on lepton asymmetry generation in leptogenesis scenarios.
• To evaluate whether early decay of the curvaton in curvaton models leads to observable non-Gaussianity in density perturbations.
• To understand the suppression of preheating in MSSM flat directions due to out-of-phase oscillations of real and imaginary components.

Proposed method

• Analyzing the dynamics of flat directions in the context of a sneutrino condensate using non-perturbative quantum field theory techniques.
• Modeling the exponential growth of decay quanta via parametric resonance, a hallmark of preheating.
• Studying the fragmentation of the condensate due to strong scattering processes following the initial exponential growth.
• Applying effective field theory methods to describe the interactions of flat directions with the condensate and the thermal bath.
• Using numerical simulations or analytical approximations to track the evolution of the condensate and decay products beyond linear perturbation theory.
• Assessing the phase coherence of real and imaginary components of MSSM flat directions to determine suppression of preheating.

Experimental results

Research questions

• RQ1 Can resonant decay of flat directions occur in a sneutrino condensate, and what are the dynamics of this process?
• RQ2 How does non-perturbative preheating affect lepton asymmetry generation in leptogenesis scenarios?
• RQ3 To what extent does early curvaton decay via preheating lead to non-Gaussianity in primordial density perturbations?
• RQ4 Why is preheating of MSSM flat directions typically delayed, and how do out-of-phase oscillations influence this?

Key findings

• Resonant decay of flat directions is significant in sneutrino condensate models, leading to strong non-perturbative effects.
• Exponential growth of decay quanta and subsequent scatterings cause fragmentation of the condensate, indicating a highly non-equilibrium process.
• The resulting lepton asymmetry in leptogenesis scenarios is difficult to predict due to the non-perturbative, out-of-equilibrium nature of the dynamics.
• In curvaton scenarios, early decay of the curvaton via preheating can generate excessive non-Gaussianity, conflicting with observational constraints.
• Preheating of MSSM flat directions is typically delayed due to destructive interference from out-of-phase oscillations of real and imaginary components.
• The study highlights the importance of non-perturbative effects in shaping the final cosmological outcomes of flat direction decay.