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We study the influence of a charged-Higgs on the excess of branching fraction ratio,, in a generic twoHiggs-doublet model. In order to investigate the lepton polarization, the detailed decay amplitudes with lepton helicity are given. When the charged-Higgs is used to resolve excesses, it is found that two independent Yukawa couplings are needed to explain the R D and R D * anomalies. We show that when

Doubly charged Higgs bosons are predicted in many new physics models with an extended Higgs sector that contains a Higgs triplet field. Current experimental searches have been focusing mainly on the scenario in which the same-sign dilepton decay modes are the dominant ones. We study the scenario where the vacuum expectation value of the triplet field is sufficiently large so that the associated charged Higgs bosons decay dominantly to a pair of weak gauge bosons instead. A detailed simulation of the signal and the backgrounds is performed for the CERN Large Hadron Collider at the collision energy of 8 TeV and 14 TeV. We find that different cuts should be imposed for the events, depending on whether the doubly charged Higgs boson mass is greater than about 200 GeV. In the higher mass region, the forward jet tagging proves to be useful in enhancing the signal significance. We show the discovery reach of the LHC running at 8 and 14 TeV, with two benchmark triplet vacuum expectation values. With an integrated luminosity of 10 fb −1 at 8 TeV, the doubly charged Higgs boson with a mass of ∼ 180 GeV can be tested at 5σ level in such a scenario.

In this study, we investigate muon g − 2, R K ( * ) , and R D ( * ) anomalies in a specific model with one doublet, one triplet, and one singlet scalar leptoquark (LQ). When the strict limits from the ℓ ′ → ℓγ, ∆B = 2, B s → µ + µ − , and B + → K + νν processes are considered, it is difficult to use one scalar LQ to explain all of the anomalies due to the strong correlations among the constraints and observables. After ignoring the constraints and small couplings, the muon g −2 can be explained by the doublet LQ alone due to the m t enhancement, whereas the measured and unexpected smaller R K ( * ) requires the combined effects of the doublet and triplet LQs, and the R D and R D * excesses depend on the singlet LQ through scalar-and tensor-type interactions.

We propose a new Universal Extra Dimensional model that is defined on a sixdimensional spacetime which has a two-sphere orbifold S 2 /Z 2 as an extra-space. We specify our model by choosing the gauge symmetry as SU(3)×SU(2)×U(1) Y ×U(1) X , introducing field contents in six-dimensions as their zero modes correspond to the Standard model particles, and determining a boundary condition of these fields on orbifold S 2 /Z 2 . A background gauge field that belongs to U(1) X is introduced there, which is necessary to obtain massless chiral fermions in four-dimensional spacetime. We then analyze Kaluza-Klein(KK) mode expansion of the fields in our model and derive the mass spectrum of the KK particles. We find that the lightest KK particles are the 1st KK particle of massless gauge bosons at tree level. We also discuss the KK parity of the KK modes in our model and confirm the stability of the lightest KK particle which is important for dark matter physics.

We propose a model with radiatively induced neutrino mass at two-loop level, applying modular A 4 symmetry. The neutrino mass matrix is formulated where the structure of associated couplings are restricted by the symmetry. Then we show several predictions in the lepton sector, satisfying lepton flavor violations as well as neutrino oscillation data. We also discuss muon anomalous magnetic moment and briefly comment on dark matter candidate.

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