Double sneutrino inflation and its phenomenologies

TL;DR

This paper explores a double sneutrino inflation model within the supersymmetric seesaw framework, showing it better explains CMB observations and constrains leptogenesis and lepton flavor violation processes.

Contribution

It introduces a double sneutrino inflation model with specific mass ratios that improves CMB predictions and analyzes its implications on reheating, leptogenesis, and lepton flavor violation.

Findings

Predicted suppression of primordial scalar spectrum at large scales.

Reheating temperature constrains seesaw parameters.

Branching ratio of μ→eγ near current experimental limits.

Abstract

In this paper we study double scalar neutrino inflation in the minimal supersymmetric seesaw model in light of WMAP. Inflation in this model is firstly driven by the heavier sneutrino field $\tilde{N}_2$ and then the lighter field $\tilde{N}_1$. we will show that with the mass ratio $6\lesssim M_2/M_1 \lesssim 10$ the model predicts a suppressed primordial scalar spectrum around the largest scales and the predicted CMB TT quadrupole is much better suppressed than the single sneutrino model. So this model is more favored than the single sneutrino inflation model. We then consider the implications of the model on the reheating temperature, leptogenesis and lepton flavor violation. Our results show that the seesaw parameters are constrained strongly by the reheating temperature, together with the requirement by a successful inflation. The mixing between the first generation and the other two generations in the right-handed neutrino sector is tiny. The rates of lepton flavor violating processes in our scenario depend on only 4 unknown seesaw parameters through a 'reduced' seesaw formula, besides $U_{e3}$ and the supersymmetric parameters. We find that the branching ratio of $\mu \to e \gamma$ is generally near the present experimental limit, while ${\rm Br}(\tau \to \mu \gamma)$ is around $\mathcal{O}(10^{-10} - 10^{-9})$.