Alternative framework for the left-right symmetric model including vector-like fermions

A

bstract

We extend the left-right symmetric model with an additional non-abelian SU (2) gauge symmetry. The particle content is augmented by one generation of vector-like fermions transforming under the fundamental representation of this new gauge group. Consequently, new self-dual scalar fields have been introduced to break the symmetry and induce the mixing of vector-like fermions with chiral fermions. This model explains the smallness of the neutrinos masses, showing that the first and second generation neutrinos masses are governed by the seesaw relation of the left-right symmetric model, while the third generation neutrino mass is controlled by a new seesaw relation arising from the mixing between the vector-like leptons and the third-generation chiral lepton doublets. We investigated the production of a resonant extra charged gauge boson which decays into vector-like quarks in association with third generation quarks or into heavy Majorana neutrinos. We exploited the run II LHC data to set lower limits on the mass of W ^′ , and consequentially on the Z ^′ . We find that the most restrictive constraints come from the decay of the W ^′ to the second generation heavy Majorana neutrinos. We also investigate the single production of the top vector-like quark with t and b quarks at the LHC, presenting several differential distributions at leading order, where parton-shower is taken into account.