Production and decay rates of excited leptons in a left-right symmetric scenario

Abstract

We merge two leading Beyond Standard Model scenarios, namely compositeness and left-right symmetry, and probe the resulting collider signatures in the leptonic case. The constraints on composite models for fermions leave open the possibility of vector like excitations of Standard Model (SM) fermions. Here we consider the possibility of low scale left-right gauge symmetry $SU(2)_{R} \times SU(2)_{L} \times U(1)_ {B-L}$, with the simplifying assumption that the right like excited sector of fermions is significantly heavier than the excitations of the left chiral fermions. It is found that the right handed currents still contribute to observable processes, and alter the existing bounds on the scale of compositeness. The cross section times branching ratio of the photon decay channel is strongly depressed, bringing down the exclusion limit of the mass of excited electrons from about 2 TeV to below 1 TeV. On the other hand, cross section times branching ratio of the Z decay channel is significantly enhanced and remains greater than that of the photon channel. We thus propose analyzing the Z decay channel in existing collider data in order to search for signature of left-right symmetry as well as excited leptons with masses above 1 TeV.