At the Large Hadron Collider (LHC), both the ATLAS and CMS Collaborations have been searching for light charged Higgs bosons via top (anti)quark production and decays channels, like pp → t $$ \overline{t} $$t ¯ with one top (anti)quark decaying into a charged Higgs boson and a b (anti)quark, when the decay is kinematically open (i.e., when $$ {m}_{H^{\pm }} $$m H ± ≲ m_t). In this paper, we propose new searches at the LHC involving light charged Higgs bosons via their pair production channels like pp → H^±h/A and pp → H⁺H⁻ in the 2-Higgs Doublet Model (2HDM) Type-I and -X scenarios. By focusing on the case where the heavy H state plays the role of the Standard Model (SM)-like Higgs boson with a mass near 125 GeV, we study the aforementioned Higgs boson pair production channels and investigate their bosonic decays, such as H^± → W^±h and/or H^± → W^±A. We demonstrate that for a light charged Higgs boson state, with $$ {m}_{H^{\pm }} $$m H ± ≲ m_t, at the LHC, such di-Higgs production and decay channels can give rise to signatures with event rates much larger than those emerging from pp → t $$ \overline{t} $$t ¯ → t $$ \overline{b} $$b ¯ H⁻ + c.c. We specifically study h/A → b $$ \overline{b} $$b ¯ and τ⁺τ⁻ decays. We, therefore, claim that the discussed combination of new production and decay modes can result in an alternative discovery channel for charged Higgs bosons lighter than the top (anti)quark at the LHC within the above two 2HDM Types. Finally, in order to motivate experimentalists in ATLAS and CMS to search for such signatures, we propose 16 Benchmark Points (BPs) which are compatible with both theoretical and experimental constraints.

We analyse a light charged Higgs boson in the 2-Higgs Doublet Model (2HDM) Type-I, when its mass satisfies the condition M_H±< M_t + M_b and the parameter space is consistent with theoretical requirements of self-consistency as well as the latest experimental constraints from Large Hadron Collider (LHC) and other data. Over such a parameter space, wherein the Standard Model (SM)-like state discovered at the LHC in 2012 is the heaviest CP-even state of the 2HDM, it is found that the decay modes of the charged Higgs boson are dominated by H^±→ W^±(∗)h. Furthermore, the light neutral Higgs boson h dominantly decays into two photons. Under these conditions, we find that the production and decay process pp → H^±h → W^±(∗)hh → ℓν_ℓ + 4γ (ℓ = e, μ) is essentially background free. However, since the W^±(∗) could be largely off-shell and the h state is very light, so that both the lepton coming from the former and the photons coming from the latter could be rather soft, we perform here a full Monte Carlo (MC) analysis at the detector level demonstrating that such a W^± + 4γ signal is very promising, as it would be yielding significant excesses at the LHC with an integrated luminosity of L = 300 fb⁻¹ at both $$ \sqrt{s} $$s = 13 and 14 TeV.

Charged Higgs bosons are common predictions in most extensions of the Standard Model Higgs sector. Therefore, their observation would elucidate the nature of the Higgs sector. Motivated by the ATLAS collaboration’s latest analysis performed with 139 fb⁻¹ of Run 2 data intended to search for charged Higgs boson, produced in top quark decay and subsequently decaying via H ^± → cb, where an excess with a local significance of 3σ is observed at m H ± = 130 GeV , we discuss here the possibility of explaining such excess in the context of the general Two-Higgs Doublet Model (2HDM type-III), after satisfying all theoretical and up-to-date experimental constraints. We also propose phenomenological scenarios to further explore the mass region around 130 GeV in the four Yukawa types of the 2HDM type-III and suggest alternative decay channel H ^± → cs and/or H ^± → W ^±∗ h to probe the nature of the observed excess (if it is not a statistical fluctuation). Future searches for H ^± will be critical in confirming or refuting the first hint of a light charged Higgs boson at the large hadron collider.

A light charged Higgs boson has been searched for at the Large Hadron Collider (LHC) via top (anti)quark decay, i.e., $t\to b{H}^{+}$, if kinematically allowed. In this contribution, we propose new channels for light charged Higgs boson searches via the pair productions $pp\to H^{\pm }h/A$ and $pp\to H^{+}{H}^{-}$ at the LHC in the context of the Two-Higgs Doublet Model (2HDM) Type-I. By focusing on a case where the heavy H state is the Standard Model (SM)-like one already observed, we investigate the production of the aforementioned charged Higgs bosons and their bosonic decay channels, namely, $H^{\pm }\to W^{\pm }h$ and/or $H^{\pm }\to W^{\pm }A$. We demonstrate that such production and decay channels can yield substantial alternative discovery channels for $H^{\pm }$ bosons at the LHC. Finally, we propose eight benchmark points (BPs) to motivate the search for such signatures.

We study the discovery prospects for a charged Higgs boson via the $bg\to c{H}^{-}\to c\overline{t}b$ process at the Large Hadron Collider (LHC). Focusing on the general two Higgs doublet model (G2HDM) that possesses extra Yukawa couplings, the process is controlled by extra top couplings ${\rho }_{tc}$ and ${\rho }_{tt}$, which can drive electroweak baryogenesis (EWBG) to account for the baryon asymmetry of the Universe (BAU). We propose benchmark points (BPs) and demonstrate that evidence could emerge at 14 TeV LHC and luminosity of $300{\mathrm{fb}}^{-1}$, with discovery potential at $600{\mathrm{fb}}^{-1}$.

We investigate the phenomenology of the charged Higgs boson at the International Linear Collider (ILC) within the framework of the type-X Two-Higgs Doublet Model, where a light charged Higgs boson, with a mass around 200 GeV or even smaller than top quark mass, is still being consistent with flavor physics data as well as with collider experimental data. In the theoretically and experimentally allowed parameter space, the e + e − → H ± W ∓ S (with S = H , A ) production processes can yield signatures with event rates larger than those from e + e − → H + H − and offer sensitivity to the Higgs mixing parameter sin ( β − α ) . We consider the bosonic H ± → W ± S decays, where the neutral scalar S further decays into a pair of tau leptons. We show, through a detector-level Monte Carlo analysis, that the resulting [ τ τ ] [ τ τ ] W W final state could be seen at the ILC with at least 500 GeV center-of-mass energy and 500 fb − 1 of luminosity.