Exploring Scalar and Vector Bileptons at the LHC

Abstract

We present an analysis on the production of two same-sign lepton pairs at the LHC, mediated by bileptons in the $SU(3)_c\times SU(3)_L\times U(1)_X$ theory, the so-called 331 model. Compared to other 331 scenarios, in this model the embedding of the hypercharge is obtained with the addition of 3 exotic quarks and doubly-charged vector gauge bosons with lepton numbers $\pm 2$ in the spectrum ($Y^{\pm\pm}$), which can mediate the production of four-lepton final states. Furthermore, a complete description of the model requires the introduction of a Higgs scalar sector, which is a sextet of $SU(3)_L$, necessary in order to correctly account for the lepton masses. As a result of this, new doubly-charged scalar states $H^{\pm\pm}$ are part of the spectrum as well and can in principle compete with the vector bileptons in giving rise to four-lepton final states. We investigate both channels and study several observables at the LHC, for both signal and Standard Model $ZZ$ background. With respect to previous work on vector- and scalar-bilepton production, we use the most updated exclusion limits at the LHC and implement the 331 model in a full Monte Carlo simulation code, capable of being interfaced with any analysis framework. Our result is that the 331 signal can be discriminated from the background with a significance of 6-9 standard deviations, depending on the LHC luminosity, with the vector bileptons dominating over the scalar ones.