Abstract
The two-Higgs Doublet Model (2HDM) is the most minimal extension of the Standard Model (SM) containing extra Higgs doublet fields. Given the multiplicity of Higgs states in a 2HDM, its Higgs potential is significantly more involved than the SM one. Importantly, it contains a multitude of Higgs triple self-couplings, unlike the SM, which only has one. These interactions are key to understanding the phenomenology of the 2HDM, as they uniquely determine the form of the potential. Several studies analysing the prospects of measuring these couplings at the Large Hadron Collider (LHC) have found them to be quite low generally. However, such studies have largely concentrated on Higgs pair-production induced by gluon-gluon scattering, either via direct annihilation or followed by their splitting into b-(anti)quark pairs, which in turn annihilate leaving behind spectator b-(anti)quarks. Both of these channels are therefore governed by QCD dynamics. We compare here the yields of such channels to those initiated by (primarily) valence quarks, which involve Electro-Weak (EW) interactions only, for neutral multi-Higgs final states. We find that EW production can be dominant over QCD production for certain final state combinations. We also illustrate that charged final states, which can only be produced via EW modes, could serve as important probes of some H^pm triple couplings, that are inaccessible in QCD-induced processes, during Run 2 and 3 of the LHC. Our analysis covers regions of the parameter space of the Type-I 2HDM that have escaped the most up-to-date experimental constraints coming from EW precision data, LHC measurements of the 125 GeV Higgs boson properties, searches for additional Higgs states, and flavour physics.
Highlights
The 2012 discovery of a neutral Higgs boson [1,2], Hobs, with a mass near 125 GeV, is strong evidence for gauge boson masses being induced by the Higgs mechanism of Electroweak Symmetry Breaking (EWSB)
While a full analysis would take into account all the contributions, including the interference effects among different channels, to the production of a given 3BFS simultaneously, we consider the contribution of each channel separately here
This entails measuring experimentally the triple-Higgs couplings, which can only be achieved if scattering processes yielding two or more Higgs bosons can be isolated in the detector
Summary
The 2012 discovery of a neutral Higgs boson [1,2], Hobs, with a mass near 125 GeV, is strong evidence for gauge boson masses being induced by the Higgs mechanism of Electroweak Symmetry Breaking (EWSB). In the 2HDM Higgs sector, five physical states emerge after EWSB: three neutral, of which two are scalars (h and H , with mh < m H ) and one a pseudoscalar ( A), plus a charged pair (H ±) The theory of this scenario is well-understood (see, e.g., [13,14]), but its phenomenological investigation is far from complete at present. In order to remedy this, we study here double and triple Higgs boson production in qq( )-induced EW interactions, where q represents predominantly a valence u, d, in the Type-I 2HDM. This theoretical scenario has been shown to yield spectacular signals involving light neutral Higgs states, with a mass smaller than that of Hobs, that are potentially accessible at the LHC, see Refs.
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