Measurements of a Higgs boson at the Large Hadron Collider (LHC) have become increasingly consistent with the predictions of the Standard Model (SM). This fact puts severe constraints on many potential low-energy extensions of the Higgs sector of the SM. In the well-known two-Higgs-doublet model (2HDM), an “alignment limit” of parameters readily furnishes one SM-like scalar and can be achieved naturally through an underlying symmetry. Among the other physical states of the 2HDM, a charged scalar <math><mrow><msup><mrow><mi>H</mi></mrow><mrow><mo>±</mo></mrow></msup></mrow></math> would provide striking evidence of new physics if observed. We propose a novel technique for the observation of the process <math><mrow><mi>p</mi><mi>p</mi><mo>→</mo><mi>t</mi><mi>b</mi><msup><mrow><mi>H</mi></mrow><mrow><mo>±</mo></mrow></msup><mo>→</mo><mi>t</mi><mover><mrow><mi>t</mi></mrow><mrow><mo>¯</mo></mrow></mover><mi>b</mi><mover><mrow><mi>b</mi></mrow><mrow><mo>¯</mo></mrow></mover></mrow></math> in the dileptonic decay channel at the LHC. The reconstruction of events in this channel is complicated by multiple <math><mi>b</mi></math> jets and unobserved neutrinos in the final state. To determine the neutrino momenta, we implement a neutrino weighting procedure to study, for the first time, the <math><mi>t</mi><mover><mi>t</mi><mo>¯</mo></mover><mi>b</mi><mover><mi>b</mi><mo>¯</mo></mover></math> signature. We further train a pair of boosted decision trees to reconstruct and classify signal events. We determine the resulting reach within the context of naturally aligned 2HDMs, such as the maximally symmetric two-Higgs-doublet model (MS2HDM). By testing at the integrated luminosity of <math><mrow><mn>150</mn><mtext> </mtext><mtext> </mtext><msup><mrow><mi>fb</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math> achieved in run 2 of the LHC, we find that this channel may restrict the parameter space of a type-II MS2HDM with charged Higgs masses as high as 680 GeV.

United Kingdom

Emily Hanson

William Klemm

Germany

Roger Naranjo

Yvonne Peters

Apostolos Pilaftsis

Charged Higgs bosons in naturally aligned two-Higgs-doublet models at the LHC

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 $$H^\pm $$ <math><msup><mi>H</mi><mo>±</mo></msup></math>  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.

Sweden

Rikard Enberg

Stefano Moretti

South Korea

Rwanda

Shoaib Munir

Electroweak production of multiple (pseudo)scalars in the 2HDM

We analyse the phenomenological implications of a light Higgs boson, h , within the CP-conserving 2-Higgs Doublet Model (2HDM) Type-I, for the detection prospects of the charged HÂ± state at Run II of the Large Hadron Collider (LHC), assuming s=13 TeV as energy and O(100Â fbâ1) as luminosity. When sufficiently light, this h state can open up the bosonic decay channel HÂ±âWÂ±(â)h , which may have a branching ratio significantly exceeding those of the HÂ±âÏÎ½ and HÂ±âcs channels. We perform a broad scan of the 2HDM Type-I parameter space, assuming the heavier of the two CP-even Higgs bosons, H , to be the observed SM-like state with a mass near 125 GeV. Through these scans we highlight regions in which mHÂ±&lt;mt+mb that are still consistent with the most recent limits from experimental searches. We find in these regions that, when the HÂ±âWÂ±(â)h decay mode is the dominant one, the h can be highly fermiophobic, with a considerably large decay rate in the Î³Î³ channel. This can result in the total cross section of the Ï(ppâHÂ±hâWÂ±(â)+4Î³) process reaching up to O(100Â fb) . We therefore investigate the possibility of observing this spectacular signal at the LHC Run II.

Morocco

Abdesslam Arhrib

Rachid Benbrik

Identifying a light charged Higgs boson at the LHC Run II

In models with extended Higgs sectors, it is possible that the Higgs boson discovered at the LHC is not the lightest one. We show that in a realistic model (the Type I 2-Higgs Doublet Model), when the sum of the masses of a light scalar and a pseudoscalar ( h and A ) is smaller than the Z boson mass, the Electroweak (EW) production of an hA pair can dominate over QCD production by orders of magnitude, a fact not previously highlighted. This is because in the gg -initiated process, hA production via a resonant Z in the s -channel is prohibited according to the Landau–Yang theorem, which is not the case for the qq¯ -initiated process. We explore the parameter space of the model to highlight regions giving such hA solutions while being consistent with all constraints from collider searches, b -physics and EW precision data. We also single out a few benchmark points to discuss their salient features, including the hA search channels that can be exploited at Run II of the LHC.

Electroweak production of light scalar–pseudoscalar pairs from extended Higgs sectors

In light of the recent discovery of a neutral Higgs boson, Hobs , with a mass near 125Â GeV , we reassess the LHC discovery potential of a charged Higgs boson, HÂ± , in the WÂ±Hobs decay channel. This decay channel can be particularly important for a HÂ± heavier than the top quark, when it is produced through the ppâtHÂ± process. The knowledge of the mass of Hobs provides an additional handle in the kinematic selection when reconstructing a BreitâWigner resonance in the HobsâbbÂ¯ decay channel. We consider some extensions of the Standard Model Higgs sector, with and without supersymmetry, and perform a dedicated signal-to-background analysis to test the scope of this channel for the LHC running at the design energy (14 TeV), for 300Â fbâ1 (standard) and 3000Â fbâ1 (high) integrated luminosities. We find that, while this channel does not show much promise for a supersymmetric HÂ± state, significant portions of the parameter spaces of several two-Higgs doublet models are testable.

Glenn Wouda

Charged Higgs boson in the W± Higgs channel at the Large Hadron Collider