Exploring Scalar and Vector Bileptons at the LHC

TL;DR

This paper analyzes the production of same-sign lepton pairs mediated by bileptons in the 331 model at the LHC, demonstrating that the signal can be distinguished from background with high significance, especially for vector bileptons.

Contribution

It provides the first comprehensive simulation of both scalar and vector bilepton signals in the 331 model at the LHC, including updated exclusion limits and detailed observables.

Findings

Vector bileptons dominate scalar contributions in four-lepton signals.

Signal can be detected with 6-9 sigma significance depending on luminosity.

The model is implemented in a Monte Carlo framework for future analyses.

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.