# LHC sensitivity to singly-charged scalars decaying into electrons and muons

## TL;DR

This paper explores the potential for the LHC to detect singly-charged scalars decaying into electrons and muons, proposing new search strategies that could exclude masses up to 500 GeV in upcoming high-luminosity runs.

## Contribution

It introduces novel search strategies for singly-charged scalars decaying into light leptons, extending sensitivity beyond traditional third-generation focus in Two-Higgs-Doublet models.

## Key findings

- Most of the parameter space up to 500 GeV can be excluded at 95% CL.
- Dedicated searches for light lepton decay modes can improve detection prospects.
- Sensitivity depends on the Yukawa coupling strength and production mechanism.

## Abstract

Current LHC searches for non-supersymmetric singly-charged scalars, based on Two-Higgs-Doublet models, in general focus the analysis on third-generation fermions in the final state. However, singly-charged scalars in alternative extensions of the scalar sector involve Yukawa couplings not proportional to the mass of the fermions. Assuming the scalar decays into electrons and muons, it can manifest cleaner experimental signatures. In this paper we suggest that a singly-charged scalar singlet, with electroweak production, can start to be probed in the near future with dedicated search strategies. Depending on the strength of the Yukawa couplings, two independent scenarios are considered: direct pair-production (small couplings) and single-production via virtual neutrino exchange (large couplings). We show that, up to a mass as large as 500 GeV, most of the parameter space could be excluded at the 95% C.L. in a high-luminosity phase of the LHC. Our results also apply to other frameworks, provided the singly-charged scalar exhibits similar production patterns and dominant decay modes.