# Signatures of the Type-I 2HDM at the LHC

## TL;DR

This paper explores how certain parameter choices in the Type-I 2HDM can lead to dominant electroweak pair-production of neutral and charged Higgs bosons at the LHC, suggesting new signatures for discovery.

## Contribution

It identifies parameter regions where electroweak Higgs pair-production surpasses QCD processes in the Type-I 2HDM, providing new avenues for experimental searches.

## Key findings

- Electroweak pair-production can dominate over QCD in certain parameter regions.
- Charged and neutral Higgs pair-production can have substantial cross sections.
- Specific di-Higgs signatures are proposed for LHC detection.

## Abstract

One of the simplest extensions of the Standard Model (SM) is the two-Higgs-doublet model (2HDM), which contains two neutral Higgs bosons, in addition to a 125 GeV one, and a charged pair. At the Large Hadron Collider (LHC), gluon-induced processes are generally the most important modes for the resonant production of the SM-like Higgs boson as well as its pair-production, and it is generally considered to be the case also for an additional neutral Higgs boson possibly existing in nature. We show that for certain parameter configurations in the Type-I 2HDM, electroweak pair-production of the neutral Higgs states can dominate over the QCD-initiated production. Moreover, it is possible for the pair-production of the charged Higgs state along with a neutral one, which can only take place electroweakly, to have a substantial cross section. We delineate such 2HDM parameter space regions through its comprehensive numerical scanning, requiring their consistency with the most relevant theoretical and experimental constraints. We also highlight some specific di-Higgs signatures that can be probed at the LHC in order to establish the Type-I 2HDM as the underlying new physics model.