The $eejj$ Excess Signal at the LHC and Constraints on Leptogenesis

TL;DR

This paper investigates whether non-supersymmetric Left-Right Symmetric Models and $E_6$-based models can simultaneously explain the CMS $eejj$ excess and leptogenesis, concluding they cannot do both at once.

Contribution

It provides a comprehensive analysis of various models, demonstrating the incompatibility of explaining the $eejj$ excess and leptogenesis simultaneously within these frameworks.

Findings

$W_R$ decay explains the $eejj$ excess in some LRSM variants.

High-scale leptogenesis cannot be accommodated in these models.

$E_6$ inspired models also fail to explain both phenomena together.

Abstract

We review the non-supersymmetric (Extended) Left-Right Symmetric Models (LRSM) and low energy $E_6$-based models to investigate if they can explain both the recently detected excess $eejj$ signal at CMS and leptogenesis. The $eejj$ excess can be explained from the decay of the right-handed gauge bosons ($W_R$) with mass $\sim \rm{TeV}$ in certain variants of the LRSM (with $g_{L}\neq g_{R}$). However such scenarios can not accommodate high-scale leptogenesis. Other attempts have been made to explain leptogenesis while keeping the $W_{R}$ mass almost within the reach of the LHC by considering the resonant leptogenesis scenario in the context of the LRSM for relatively large Yukawa couplings. However this may not be feasible due to washout of the lepton asymmetry by certain processes. Therefore we consider three effective low energy subgroups of the superstring inspired $E_{6}$ model having a number of additional exotic fermions which provides a rich phenomenology to be explored. We however find that these three effective low energy subgroups of $E_6$ too cannot explain both the $eejj$ excess signal and leptogenesis simultaneously.