Abstract
We analyse a light charged Higgs boson in the 2-Higgs Doublet Model (2HDM) Type-I, when its mass satisfies the condition MH±< Mt + Mb 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 → ℓνℓ + 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} = 13 and 14 TeV.
Highlights
In a recent study [1], it was found that in the Type-I scenario of the 2-Higgs Doublet Model (2HDM), the decay mode H± → W ±(∗)h could become the dominant one, in the so-called fermiophobic limit of the 2HDM Type-I
At the same time, when the h state is fermiophobic, its decay modes into Standard Model (SM) fermions could be highly suppressed, which results into a large Branching Ratio (BR) for the mode h → γγ. in [1], it was found that the associated production process pp → H±h could lead to a potentially detectable W ± + 4γ final state
Before moving on to compute the significances of our signal for the Benchmark Points (BPs) introduced, we present table 4 for the purpose of confirming the statement made in ref. [1], that none of the backgrounds is really observable for any realistic Large Hadron Collider (LHC) and High-Luminosity LHC (HL-LHC) luminosity. (Results are shown here for TeV, but the conclusion is the same for TeV.) We present the predicted cross sections for the signals emerging from the BPs after taking into account the cuts and the detector acceptance efficiency in tables 5 and 6, where we have considered √
Summary
The scalar sector of the 2HDM contains two complex SU(2) doublets with hypercharge Y = +1, Φa. Potential involving two Higgs doublets can be written as [4]:. We will work with a CP-conserving scalar potential by choosing m212 and λ5,6,7 to be real. Like in [1], we choose to focus on Type-I, where only one doublet Φ2 couples to all fermions and the Higgs-fermion couplings are flavour diagonal in the fermion mass basis and depend only on two angles, α (parameterising the mixing between h and H) and β (which tangent is given by the ratio of the two VEVs), as shown in table 1
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