“…Here, L T = (ν L , L ) is the ordinary lepton doublet, g and g are the SU(2) L and U(1) Y gauge couplings and W W W µν , B µν are the field strength tensor of the corresponding gauge fields respectively; τ τ τ are the Pauli matrices and Y is the hypercharge, f and f are dimensionless couplings and are expected (and assumed) to be of order unity. Excited states interacting with the SM sector through the model Lagrangians (1.1)-(1.2) and (1.3) have been extensively searched for at high-energy collider facilities and their phenomenology has also been discussed in a series of recent papers [24,25,26,27,28,29,30,31,32,33]. The current strongest bounds are due to the recent LHC experiments.…”