Leptogenesis in the Exceptional Supersymmetric Standard Model: flavour dependent lepton asymmetries

TL;DR

This paper explores how the $E_6$ inspired Supersymmetric Standard Model can generate significant flavour-dependent lepton asymmetries at relatively low right-handed neutrino masses, impacting leptogenesis theories.

Contribution

It calculates flavour-dependent lepton asymmetries within the $E_6$SSM, highlighting the role of extra particles and the potential for large CP asymmetries at low neutrino masses.

Findings

CP asymmetries can be large even for neutrino masses as low as 10^6 GeV

Extra Higgs, leptons, and leptoquarks contribute to decay asymmetries

The model supports viable leptogenesis at lower energy scales

Abstract

We calculate flavour dependent lepton asymmetries within the $E_6$ inspired Supersymmetric Standard Model ($\rm E_6SSM$), which has an extra $U(1)_N$ symmetry. In this model, the right-handed neutrino doesn't participate in gauge interactions, allowing it to be used for both the see--saw mechanism and leptogenesis. Extra Higgs, leptons and leptoquarks predicted by the E$_6$SSM contribute to the ordinary lepton CP asymmetries induced by the decays of the lightest right--handed neutrino (and sneutrino) and give rise to a set of extra decay asymmetries. We find that the CP asymmetries can be relatively large, even when the lightest right--handed neutrino is as light as $10^6 {GeV}$.