Possible models of Yukawa interaction are discussed in the two Higgs doublet model (THDM) under the discrete symmetry imposed to avoid the flavor changing neutral current at the leading order. It is known that there are four types of such models corresponding to the possible different assignment of charges for the discrete symmetry on quarks and leptons. We first examine decay properties of Higgs bosons in each type model, and summarize constraints on the models from current experimental data. We then shed light on the differences among these models in collider phenomenology. In particular, we mainly discuss the so-called type-II THDM and type-X THDM.The type-II THDM corresponds to the model with the same Yukawa interaction as the minimal supersymmetric standard model. On the other hand, in the type-X THDM, additional Higgs bosons can predominantly decay into leptons. This scenario may be interesting because of the motivation for a light charged Higgs boson scenario such as in the TeV scale model of neutrino, dark matter and baryogenesis. We study how we can distinguish the type-X THDM from the minimal supersymmetric standard model at the Large Hadron Collider and the International Linear Collider.

After the discovery of the standard-model-like Higgs boson at the LHC, the structure of the Higgs sector remains unknown. We discuss how it can be determined by the combination of direct and indirect searches for additional Higgs bosons at future collider experiments. First of all, we evaluate expected excluded regions for the mass of additional neutral Higgs bosons from direct searches at the LHC with the 14 TeV collision energy in the two Higgs doublet models with a softly-broken Z 2 symmetry. Second, precision measurements of the Higgs boson couplings at future experiments can be used for the indirect search of extended Higgs sectors if measured coupling constant with the gauge boson slightly deviates from the standard model value.In particular, in the two Higgs doublet model with the softly-broken discrete symmetry, there are four types of Yukawa interactions, so that they can be discriminated by measuring the pattern of deviations in Yukawa coupling constants. Furthermore, we can fingerprint various extended Higgs sectors with future precision data by detecting the pattern of deviations in the coupling constants of the standard-model-like Higgs boson.We demonstrate how the pattern of deviations can be different among various Higgs sectors which predict the electroweak rho parameter to be unity; such as models with additional an isospin singlet, a doublet, triplets or a septet. We conclude that as long as the gauge coupling constant of the Higgs boson slightly differs from the standard model prediction but is enough to be detected at the LHC and its high-luminosity run or at the International Linear Collider, we can identify the non-minimal Higgs sector even without direct discovery of additional Higgs bosons at the LHC.

We calculate radiative corrections to a full set of coupling constants for the 125 GeV Higgs boson at the one-loop level in two Higgs doublet models with four types of Yukawa interaction under the softly-broken discrete Z 2 symmetry. The renormalization calculations are performed in the on-shell scheme, in which the gauge dependence in the mixing parameter which appears in the previous calculation is consistently avoided. We first show the details of our renormalization scheme, and present the complete set of the analytic formulae of the renormalized couplings. We then numerically demonstrate how the inner parameters of the model can be extracted by the future precision measurements of these couplings at the high luminosity LHC and the International Linear Collider.

In general, there can be mass differences among scalar bosons of the Higgs triplet field with the hypercharge of Y = 1. In the Higgs triplet model, when the vacuum expectation value v∆ of the triplet field is much smaller than that v (≃ 246 GeV) of the Higgs doublet field as required by the electroweak precision data, a characteristic mass spectrum m 2where m H ++ , m H + , m φ 0 are the masses of the doubly-charged (H ++ ), the singly-charged (H + ) and the neutral (φ 0 = H 0 or A 0 ) scalar bosons, respectively. It should be emphasized that phenomenology with ξ = 0 is drastically different from that in the case with ξ = 0 where the doublycharged scalar boson decays into the same sign dilepton ℓ + ℓ + or the diboson W + W + depending on the size of v∆. We find that, in the case of ξ > 0, where H ++ is the heaviest, H ++ can be identified via the cascade decays such as H ++ → H + W +( * ) → φ 0 W +( * ) W +( * ) → bbℓ + νℓ + ν. We outline how the Higgs triplet model can be explored in such a case at the LHC. By the determination of the mass spectrum, the model can be tested and further can be distinguished from the other models with doubly-charged scalar bosons.

Abstract:We discuss the Type-X (lepton-specific) two Higgs doublet model as a solution of the anomaly of the muon g − 2. We consider various experimental constraints on the parameter space such as direct searches for extra Higgs bosons at the LEP II and the LHC Run-I, electroweak precision observables, the decay of B s → µ + µ − , and the leptonic decay of the tau lepton. We find that the measurement of the tau decay provides the most important constraint, which excludes the parameter region that can explain the muon g − 2 anomaly at the 1σ level. We then discuss the phenomenology of extra Higgs bosons and the standard model-like Higgs boson (h) to probe the scenario favored by the g − 2 data at the collider experiments. We find that the 4τ , 3τ and 4τ + W/Z signatures are expected as the main signal of the extra Higgs bosons at the LHC. In addition, we clarify that the value of the hτ τ coupling is predicted to be the standard model value times about −1.6 to −1.0, and the branching fraction of the h → γγ mode deviates from the standard model prediction by −30% to −15%. Furthermore, we find that the exotic decay mode, h decaying into the Z boson and a light CP-odd scalar boson, is allowed, and its branching fraction can be a few percent. These deviations in the property of h will be tested by the precision measurements at future collider experiments.

We calculate renormalized Higgs boson couplings with gauge bosons and fermions at the one-loop level in the model with an additional isospin singlet real scalar field. These coupling constants can deviate from the predictions in the standard model due to tree-level mixing effects and one-loop contributions of the extra neutral scalar boson. We investigate how they can be significant under the theoretical constraints from perturbative unitarity and vacuum stability and also the condition of avoiding the wrong vacuum. Furthermore, comparing with the predictions in the Type I two Higgs doublet model, we numerically demonstrate how the singlet extension model can be distinguished and identified by using precision measurements of the Higgs boson couplings at future collider experiments.

The goal of this report is to summarize the current situation and discuss possible search strategies for charged scalars, in non-supersymmetric extensions of the Standard Model at the LHC. Such scalars appear in Multi-HiggsDoublet models, in particular in the popular Two-HiggsDoublet model, allowing for charged and additional neutral Higgs bosons. These models have the attractive property that electroweak precision observables are automatically in agreement with the Standard Model at the tree level. For the most popular version of this framework, Model II, a discovery of a charged Higgs boson remains challenging, since the parameter space is becoming very constrained, and the QCD background is very high. We also briefly comment on models with dark matter which constrain the corresponding charged a e-mail: Maria.Krawczyk@fuw.edu.pl b e-mail: Per.Osland@uib.no scalars that occur in these models. The stakes of a possible discovery of an extended scalar sector are very high, and these searches should be pursued in all conceivable channels, at the LHC and at future colliders.

We identify the parameter regions of the phenomenological minimal supersymmetric standard model (pMSSM) with the minimal possible fine-tuning. We show that the fine-tuning of the pMSSM is not large, nor under pressure by LHC searches. Low sbottom, stop and gluino masses turn out to be less relevant for low fine-tuning than commonly assumed. We show a link between low fine-tuning and the dark matter relic density. Fine-tuning arguments point to models with a dark matter candidate yielding the correct dark matter relic density: a bino-higgsino particle with a mass of 35-155 GeV. Some of these candidates are compatible with recent hints seen in astrophysics experiments such as Fermi-LAT and AMS-02. We argue that upcoming direct search experiments, such as XENON1T, will test all of the most natural solutions in the next few years due to the sensitivity of these experiments on the spin-dependent WIMP-nucleon cross section.