Narrow Results

Decays of B mesons into final states containing a τ lepton are sensitive to new charged current interactions that break lepton-flavor universality. These decays have been studied only at e⁺e^- colliders, where the low-background environment and well-known initial state make it possible to observe small signals with undetectable neutrinos. In particular, the large data samples of the B factories and recent advances in techniques for full-event reconstruction have led to evidence for the decay B⁺→τ⁺ ν_τ and unambiguous observation of the decays . These results exclude large regions of the parameter space for a variety of new physics models. Furthermore, the branching fraction for has been measured to be higher than the Standard Model expectation by more than three standard deviations, making this an interesting topic for further research. This paper reviews the theoretical and experimental status of this topic, summarizing the results at this time and outlining the path for further improvements.

In this work, we study the radiative leptonic decays of $B^{-}$ and $D^{-}$ mesons in the Standard Model (SM) and two-Higgs-doublet-model (2HDM) Type II. The results are obtained using the factorization procedure, and the contribution of the order $O({\mathrm{\Lambda }}_{\mathrm{\text{QCD}}}/m_Q)$ is included. The numerical results are calculated using the wave function obtained in relativistic potential model. As a result, the decay mode $B\to \gamma \tau {\nu }_{\tau }$ is found to be sensitive to the effect of the charged Higgs boson. Using the constraint on the free parameters of 2HDM given in previous works, we find the contribution of the charged Higgs boson in the decay mode $B\to \gamma \tau {\nu }_{\tau }$ can be as large as about 13%.

Different production processes involving the Higgs boson, such as annihilation and W/Z boson fusion, will be observed in the International Linear Collider (ILC). The ILC operates at a center-of-mass (CM) energy of $\sqrt{s}=200$–1000GeV. The study reveals that the production cross-section can either be enhanced or reduced depending on the CM energy and the specific combination used, which has implications for selecting appropriate production processes. Additionally, this investigation highlights that by polarizing beams, the number of measurable observables increases. These observables, such as left–right asymmetry, detailed effective polarization, and adequate effective luminosity, are crucial to ascertain contemporary physical parameters in physics models absurdly the Standard Model (SM).

We present the results of a search for charged Higgs in the decay products of at the CDF II detector at the Tevatron. The search is based on the cross section measurements of production in three exclusive decay channels: dilepton, lepton + jets and lepton + hadronic tau. Assuming the charged Higgs decays only via , and , and , limits in the MSSM (m_Higgs, tan(β)) plane are obtained at tree level. A model-independent analysis is introduced in which the results are independent of Higgs branching ratios. This analysis results in BR(t→Hb)<0.7 at 95%CL for 80 GeV<m_Higgs<150 GeV.

The top-seesaw assisted technicolor (TC) model, which was proposed recently to accommodate the 126 GeV Higgs mass discovered by the Large Hadron Colliders (LHC), predicts light and heavy charged Higgs bosons in addition to the neutral Higgses. In this paper, we will study the pair productions of the charged Higgs, proceeding through gluon–gluon fusion and quark–antiquark annihilation, at the LHC in the frame of the top-seesaw assisted TC model. We find that in a large part of parameter space the production cross-sections of the light charged Higgs pair at the LHC can be quite large compared with the low standard model backgrounds, while it is impossible for the pair production of the heavy ones to be detected with the strong final mass suppression. Therefore, the light charged Higgs pair production may be served as a probe of this new TC model at the LHC.

At the Large Hadron Collider (LHC), ATLAS and CMS collaborations observed various decay modes of the light charged Higgs bosons produced by top (anti)quark decays. In this paper, we are interested in the subsequent decay of the light charged Higgs boson into a charm and a strange quark–antiquark pair and into a tau and a tau–neutrino pair, separately, in the context of the Georgi–Machacek model, which offers a large triplet vacuum expectation value (VEV) preserving custodial symmetry. We show that these experimental observations constrain the triplet VEV from above. We explore the model parameter space consistent with the theoretical constraints, the latest Higgs data and the experimental data for light charged Higgs decaying to $cs$ and $\tau {\nu }_{\tau }$.

The paper discusses selected recent results from B factories, precision measurements of the unitarity triangle, studies of rare B decays, and results in spectroscopy of charmonium-like and bottomonium-like states. We then review the physics case for a super B factory and discuss the effort to construct such a facility at KEK.