Charged Higgs Contribution Research Articles

The forgotten channels: charged Higgs boson decays to a W\xb1 and a non-SM-like Higgs boson

The presence of charged Higgs bosons is a generic prediction of multiplet extensions of the Standard Model (SM) Higgs sector. Focusing on the Two-Higgs-Doublet-Model (2HDM) with type I and lepton-specific Yukawa sectors, we discuss the charged Higgs boson collider phenomenology in the theoretically and experimentally viable parameter space. While almost all existing experimental searches at the LHC target the fermionic decays of charged Higgs bosons, we point out that the bosonic decay channels — especially the decay into a non-SM-like Higgs boson and a W boson — often dominate over the fermionic channels. Moreover, we revisit two genuine BSM effects on the properties of the discovered Higgs boson — the charged Higgs contribution to the diphoton rate and the Higgs decay to two light Higgs bosons — and their implication for the charged Higgs boson phenomenology. As main result of the present paper, we propose five two-dimensional benchmark scenarios with distinct phenomenological features in order to facilitate the design of dedicated LHC searches for charged Higgs bosons decaying into a W boson and a light, non-SM-like Higgs boson.

Charged Higgs contribution on Bc → (Ds, Ds*) l+l−

AbstractIn this paper, we study rare semileptonic decays of the $B_c$ meson in the context of type-I, II, and III two Higgs doublet models. We follow the relativistic quark model for parameterizing the form factors used in matrix elements of weak transitions between the corresponding meson states. We investigate observables such as branching ratio, lepton polarization asymmetry, forward–backward asymmetry, etc. and analyze the dependence of these quantities on the model parameters. We have found that there is noticeable sensitivity to these observables for the charged Higgs boson, which may provide a powerful probe to the standard model and new physics beyond it.

Re(\u03f5K\u2032/\u03f5K) and Kto pi nu overline{nu} in a two-Higgs doublet model

The Kaon direct CP violation Re(ϵK′/ϵK) below the experimental data of a 2σ in the standard model, which is calculated using the RBC-UKQCD lattice and a large Nc dual QCD, indicates the necessity of a new physics effect. In order to resolve the insufficient Re(ϵK′/ϵK), we study the charged-Higgs contributions in a generic two-Higgs-doublet model. If we assume that the origin of the CP-violation phase is uniquely from the Kobayashi-Maskawa (KM) phase when the constraints from the B- and K-meson mixings, B → Xsγ, and Kaon indirect CP violating parameter ϵK are simultaneously taken into account, it is found that the Kaon direct CP violation through the charged-Higgs effects can reach Re(ϵK′/ϵK)H ± ∼ 8 × 10− 4. Moreover, with the constrained values of the parameters, the branching ratios of the rare Kto pi nu overline{nu} decays can be BRleft({K}^{+}to {pi}^{+}nu overline{nu}right)sim 13 times 1{0}^{-11} and BRleft({K}_Lto {pi}^0nu overline{nu}right)sim 3.6times 1{0}^{-11} , where the results can be tested through the NA62 experiment at CERN and the KOTO experiment at J-PARC, respectively.

Observability of Charged Higgs Contribution in t-channel Single Top at LHC

In this paper, the t-channel charged Higgs production at LHC is studied. Production process is a t-channel single top event with charged Higgs exchange. Therefore the signal is similar with Standard Model single top production in terms of the final state. In the first step, the signal cross section is calculated and compared to the other main production processes which are used for a heavy charged Higgs search at LHC, i.e., pp -> tbH- and pp -> H+ -> tb. In the next step, an event generation and analysis is applied on signal and background events, in order to estimate the signal significance. The signal cross section is typically smaller than the associated production (tbH-) and resonance production (tb) by a factor of 10-3 and ranges from 10 fb to 1 fb for charged Higgs mass from 200 to 500 GeV at tanbeta = 50. Due to the small cross section of signal events and large SM background, the signal significance is small even after a dedicated kinematic analysis and selection of events, however, tanbeta values above 120 can be excluded at an integrated luminosity of 3000 fb-1.

Charged Higgs contribution to0ν2βdecay

The singly charged Higgs boson contribution to $0\nu2\beta$ is neglected on grounds of couplings involving small masses and small nuclear matrix elements. We reconsider such contributions, but now in the light of QCD corrections and renormalization group evolution. It is found that the charged Higgs contribution is generically as large as (and at times significantly larger than) the other contributions and there can be large cancellations between contributions coming from different sources. This observation will have an important impact on the phenomenology.

Charged Higgs contribution to [formula omitted] and [formula omitted

We study the decay modes B¯s→ϕπ0 and B¯s→ϕρ0 within the frameworks of two-Higgs doublet models type-II and type-III. We adopt in our study Soft Collinear Effective Theory as a framework for the calculation of the amplitudes. We derive the contributions of the charged Higgs mediation to the weak effective Hamiltonian governing the decay processes in both models. Moreover, we analyze the effect of the charged Higgs mediation on the Wilson coefficients of the electroweak penguins and on the branching ratios of B¯s→ϕπ0 and B¯s→ϕρ0 decays. We show that within two-Higgs doublet models type-II and type-III the Wilson coefficients corresponding to the electroweak penguins can be enhanced due to the contributions from the charged Higgs mediation leading into enhancement in the branching ratios of B¯s→ϕπ0 and B¯s→ϕρ0 decays. We find that, within two-Higgs doublet models type-II, the enhancement in the branching ratio of B¯s→ϕπ0 cannot exceed 18% with respect to the SM predictions. For the branching ratio of B¯s→ϕρ0, we find that the charged Higgs contribution in this case is small where the branching ratio of B¯s→ϕρ0 can be enhanced or reduced by about 4% with respect to the SM predictions. For the case of the two-Higgs doublet models type-III we show that the branching ratio of B¯s→ϕπ0 can be enhanced by about a factor 2 of its value within two-Higgs doublet models type-II. However, no sizeable enhancement with respect to the SM predictions can be obtained for both B¯s→ϕπ0 and B¯s→ϕρ0 decays.

Higgcision in the two-Higgs doublet models

We perform global fits to general two-Higgs doublet models (2HDMs) with generalized couplings using the most updated data from ATLAS, CMS, and Tevatron. We include both scenarios with CP-conserving and CP-violating couplings. By relaxing the requirement on the discrete symmetries that are often imposed on the Yukawa couplings, we try to see which of the 2HDMs is preferred. We found that (i) Higgcision in 2HDMs can be performed efficiently by using only 4 parameters including the charged Higgs contributions to the Higgs couplings to two photons, (ii) the differences among various types of 2HDMs are very small with respect to the chi-square fits, (iii) tan β is constrained to be small, (iv) the p-values for various fits in 2HDMs are worse than that of the standard model. Finally, we put emphasis on our findings that future precision measurements of the Higgs coupling to the scalar top-quark bilinear $ \left( {C_u^S} \right) $ and tan β may endow us with the discriminating power among various types of 2HDMs especially when $ C_u^S $ deviates from its SM value 1.

$ \overline{B}\ \to {X_s}\gamma $ in the Two Higgs Doublet Model up to next-to-next-to-leading order in QCD

Abstract We compute three-loop matching corrections to the Wilson coefficients C 7 and C 8 in the Two Higgs Doublet Model by applying expansions for small, intermediate and large charged Higgs boson masses. The results are used to evaluate the branching ratio of $ \overline{B}\ \to {X_s}\gamma $ to next-to-next-to leading order accuracy, and to determine an updated lower limit on the charged Higgs boson mass. We find M H+ ≥ 380GeV at 95% confidence level when the recently completed BABAR data analysis is taken into account. Our results for the charged Higgs contribution to the branching ratio exhibit considerably weaker sensitivity to the matching scale μ 0, as compared to previous calculations.

Charged Higgs Boson Contribution to $\overline{\nu}_{e}-e$ Scattering from Low to Ultrahigh Energy in Higgs Triplet Model

We study the $\overline{\nu}_{e}-e$ scattering from low to ultrahigh energy in the framework of Higgs Triplet Model (HTM). We add the contribution of charged Higgs boson exchange to the total cross section of the scattering. We obtain the upper bound $h_{ee}/M_{H^{\pm}}\lesssim2.8\times10^{-3}~\mbox{GeV}^{-1}$ in this process from low energy experiment. We show that by using the upper bound obtained, the charged Higgs contribution can give enhancements to the total cross section with respect to the SM prediction up to 5.16 % at E≤1014 eV and maximum at $s\approx M_{H^{\pm}}^{2}$ and would help to determine the feasibility experiments to discriminate between SM and HTM at current available facilities.

H→γγin the inert Higgs doublet model

Motivated by the recent results from LHC on the di-photon search for a standard model (SM) Higgs-like boson, in this work we discuss the implications of this signal in the framework of the inert Higgs doublet model. Our analysis takes account of the previous limits from Higgs searches at LEP, the Tevatron, and the LHC. We have also considered the bounds coming from perturbativity, unitarity, vacuum stability, and electroweak precision tests. We show that the charged Higgs contributions can interfere constructively or destructively with the W gauge bosons' loops leading to enhancement or suppression of the di-photon rate with respect to the SM rate. We show also that the invisible decay of the Higgs, if open, could affect the total width of the SM Higgs boson and therefore suppress the di-photon rate.

LHC diphoton Higgs signal and top quark forward-backward asymmetry in quasi-inert Higgs doublet model

In the quasi-inert Higgs doublet model, we study the LHC diphoton rate for a standard model-like Higgs boson and the top quark forward-backward asymmetry at Tevatron. Taking into account the constraints from the vacuum stability, unitarity, electroweak precision tests, flavor physics and the related experimental data of top quark, we find that compared with the standard model prediction, the diphoton rate of Higgs boson at LHC can be enhanced due to the light charged Higgs contributions, while the measurement of the top quark forward-backward asymmetry at Tevatron can be explained to within $1\sigma$ due to the non-standard model neutral Higgs bosons contributions. Finally, the correlations between the two observables are discussed.

Two Higgs doublet model of type II facing flavor physics data

We discuss tests of the charged Higgs sector of the Two Higgs Doublet Model (2HDM) of Type II in the light of recent flavour physics data. Particular attention is paid to recent measurement of purely leptonic decays of heavy-light mesons, which depart more or less significantly from the Standard Model (SM) predictions. We derive constraints on the parameters of the 2HDM type II from leptonic and semileptonic $\Delta F=1$ decays as well as loop processes ($b \to s \gamma$, $B\bar{B}$ mixing or $Z\to\bar{b}b$) sensitive to charged Higgs contributions. The outcome of this work is that while 2HDM Type II can fit individual observable through fine-tuning schemes, in a combined analysis it does not perform better than the SM by favouring a decoupling solution. Assuming that 2HDM Type II is realized in Nature, constraints on its parameters ($m_{H^+}$ and $\tan \beta$) are derived. A limit on the charged Higgs mass $m_{H^+} > 316 \; {\rm GeV}$ at $95\%$~CL is obtained irrespective of the value of $\tan \beta$. This limit is dominated by the $b\rightarrow s \gamma$ branching ratio measurement. All results have been obtained with the \ckmfitter\ analysis package, featuring the frequentist statistical approach \rfit\ to handle theoretical uncertainties.

Charged-Higgs-boson effects in theB→Dτντdifferential decay distribution

We show that the decay mode $B\ensuremath{\rightarrow}D\ensuremath{\tau}{\ensuremath{\nu}}_{\ensuremath{\tau}}$ is competitive with and complementary to $B\ensuremath{\rightarrow}\ensuremath{\tau}{\ensuremath{\nu}}_{\ensuremath{\tau}}$ in the search for charged-Higgs effects. Updating the relevant form factors, we find that the differential distribution in the decay chain $\overline{B}\ensuremath{\rightarrow}D{\overline{\ensuremath{\nu}}}_{\ensuremath{\tau}}{\ensuremath{\tau}}^{\ensuremath{-}}[\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\nu}}_{\ensuremath{\tau}}]$ excellently discriminates between standard model and charged-Higgs contributions. By measuring the $D$ and ${\ensuremath{\pi}}^{\ensuremath{-}}$ energies and the angle between the $D$ and ${\ensuremath{\pi}}^{\ensuremath{-}}$ three-momenta, one can determine the effective charged-Higgs coupling including a possible $CP$-violating phase.

Angular distribution asymmetry inτ−→π−π0ντdecay in the two-Higgs-doublet model with largetanβ

We study possible scalar type interactions in tau^- -->pi^- pi^0 nu_tau decay. One finds that an angular distribution asymmetry, A(s), can be induced from the interference between the scalar part and vector part amplitudes in this decay. Our analysis shows that, in the two-Higgs-doublet model of type II with large tan beta, the charged Higgs contribution could make A(s) up to 10^{-3} without conflict with present experimental constraints. Thus in the future precise experiments in tau-charm factories, this angular distribution asymmetry may be an interesting observable either to be helpful in searching for the signal of the charged Higgs boson or to impose the significant bound on it.

Comparative study of CP asymmetries in supersymmetric models

We systematically analyze the supersymmetric contributions to the mixing CP asymmetries and branching ratios of B → ϕ K S and B → η ′ K S processes. We consider both gluino and chargino exchanges in a model independent way by using the mass insertion approximation method. While we adopt the QCD factorization approach for evaluating the corresponding hadronic matrix elements, a critical comparison with predictions in naive factorization one is also provided. We find that pure chargino contributions cannot accommodate the current experimental results on CP asymmetries, mainly due to b → s γ constraints. We show that charged Higgs contributions can relax these constraints making chargino responsible for large asymmetries. On the other hand, pure gluino exchanges can easily saturate both the constraints on B → ϕ K S and B → η ′ K S CP asymmetries. Moreover, we also find that the simultaneous contributions from gluino and chargino exchanges could easily account for the present experimental results on the mentioned asymmetries. Remarkably, large experimentally allowed enhancements of B → η ′ K S branching ratio can easily be achieved by the contribution of two mass insertions in gluino exchanges. Finally, we analyze the correlations between the CP asymmetries of these processes and the direct CP asymmetry in b → s γ decay. When all experimental constraints are satisfied, supersymmetry favors large and positive values of b → s γ asymmetry.

DirectCPviolation in radiativebdecays in and beyond the standard model

We consider the partial rate asymmetry in the inclusive decay modes b to s gamma and b to d gamma, concentrating on non-standard models with new charged Higgs interactions. We find that the charged Higgs contribution to the asymmetry for b to s gamma is small in such models due to a universal cancellation mechanism. The asymmetry is therefore difficult to distinguish experimentally from the Standard Model (SM) value, which is also small. The cancellation mechanism is found to be rendered inoperative in supersymmetry due to the presence of chargino loops. Unlike b to s gamma, the rate asymmetry for b to d gamma in Higgs models can be quite different from its SM value, generally ranging from -20% to +20%. Specific model calculations are performed for the Three-Higgs Doublet Model and the ``Top'' Two-Higgs Doublet Model to serve as illustrations. We also offer some suggestions that may be helpful to experimentalists in the detection of the inclusive mode b to d gamma.

The contribution of Bc mesons to the search for B+ → τ+ ντ decays at LEP

Abstract We study the contribution of Bc mesons to the search for B → τντ decays. We find that at LEP the contributions from Bu and Bc mesons can be comparable. This observation can have a relevant impact on the extraction of constraints on new physics (such as charged-Higgs contributions) from current LEP limits on B → τν final states. Inclusion of the Bc contribution can reduce the current L3 limit on tan β M H from 0.38 GeV−1 (90% CL) down to 0.27 GeV−1 (90% CL).

SUSY and the mass difference of B0d – B̄ 0d

We present an overview of the loop corrections to the mass difference $\Delta m_{B_d^0}/ m_{B_d^0}$ within the minimal supersymmetric standard model. We include the complete mixing matrices of the charginos and neutralinos as well as of the scalar partners of the left and right handed third generation quarks. We show that the SUSY contribution to the mass difference in the $B_d^0$ system is comparable to the Standard Model one and can be even larger for the charged Higgs contribution and for a certain supersymmetric parameter space.

K +→π + vv andK L 0 →μ + μ − decays within the Minimal Supersymmetric Standard Model

We present a detailed calculation of the contributions of charginos, scalar quarks, and charged Higgs boson to theK +→π + vv andK L 0 →μ + μ − decays. We include mixings: that of charginos and that of the scalar partners of the left and right handed top quark. We find that the box contribution to the amplitudes is much smaller than the penguin contribution, which can be ∼10% of the Standard Model contribution, even for relatively large SUSY masses. The charged Higgs contribution can be as large as 25% of the SM contribution in the first decay and as much as 40% of the SM contribution in the second decay.

QCD corrections to charged Higgs-mediated b → cτν decay

We calculate the O( α s ) corrections to the charged Higgs mediated inclusive semi-tauonic B decay. By working in the Landau gauge, we demonstrate how to obtain the charged Higgs contributions (both direct and interference terms) from the known QCD corrections to t → bH +. Combining our results with O( 1 m b 2 ) corrections to the spectator model and comparing the theoretical prediction with the recent experimental measurements, we find a model-independent 2σ upper bound on the ratio of Higgs vacuum expectation values, tan β < 0.52( m H 1 GeV) .