The eejj excess signal at the LHC and constraints on leptogenesis

We review the non-supersymmetric (Extended) Left-Right Symmetric Models (LRSM) and low energy E<inf>6</inf>-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<inf>R</inf>) with mass ∼ TeV in certain variants of the LRSM (with g<inf>L</inf> g<inf>R</inf>). However such scenarios can not accommodate high-scale leptogenesis. Other attempts have been made to explain leptogenesis while keeping the W<inf>R</inf> 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, certain lepton number violating scattering processes involving the right-handed Higgs triplet and the right-handed neutrinos can stay in equilibrium till the electroweak phase transition and can washout the lepton asymmetry generated in the resonant leptogenesis scenario for mass range of W<inf>R</inf> as indicated by the CMS excess signal. Thus in such a scenario one needs to invoke post-sphaleron baryogenesis to explain the observed baryon asymmetry of the universe. Next, we consider three effective low energy subgroups of the superstring inspired E<inf>6</inf> 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<inf>6</inf> too cannot explain both the eejj excess signal and leptogenesis simultaneously.