scholarly journals Invisible KL decays in the SM extensions

2016 ◽  
Vol 31 (25) ◽  
pp. 1650142 ◽  
Author(s):  
S. N. Gninenko ◽  
N. V. Krasnikov
Keyword(s):  
Standard Model ◽  
Branching Ratio ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Higgs Doublet ◽  
New Physics ◽  
Doublet Model ◽  
Strong Motivation ◽  
Two Higgs Doublet Model ◽  
Near Future

In the Standard Model (SM), the branching ratio for the decay [Formula: see text] is helicity suppressed and predicted to be very small [Formula: see text]. We consider two natural extensions of the SM as the two-Higgs-doublet model (2HDM) and the neutrino minimal Standard Model ([Formula: see text]MSM) with additional singlet scalar, whose main feature is that they can lead to an enhanced [Formula: see text]. In the 2HDM, the smallness of the neutrino mass is explained due to the smallness of the second Higgs doublet vacuum expectation value. Moreover, the [Formula: see text]MSM extension with additional singlet field can explain the [Formula: see text] anomaly. The considered models demonstrate that the [Formula: see text] decay is a clean probe of new physics scale well above 100 TeV, that is complementary to rare [Formula: see text] decay, and provide a strong motivation for its sensitive search in a near future low-energy experiment.

ONE LOOP-INDUCED WZH COUPLING IN THE TWO HIGGS DOUBLET MODEL

1989 ◽  
Vol 04 (28) ◽  
pp. 2757-2766 ◽  
Author(s):  
THOMAS G. RIZZO
Keyword(s):  
Standard Model ◽  
Higgs Doublet ◽  
New Physics ◽  
Tree Level ◽  
Beyond The Standard Model ◽  
The Standard Model ◽  
Charged Higgs ◽  
Doublet Model ◽  
The One ◽  
Two Higgs Doublet Model

Although absent at the tree level in models with only doublet and singlet Higgs representations, the WZH coupling can be induced at the one-loop level. We examine the size of this induced coupling in the two Higgs doublet model due to fermion as well as Higgs/gauge boson loops. Such couplings could provide a new mechanism for charged Higgs production at colliders and are ‘backgrounds’ to new physics beyond the Standard Model. We find, however, that these couplings are very weak for all regions of the parameter space explored.

scholarly journals THE EXCLUSIVE $\bar B \to\pi e^+ e^-$ AND $\bar B\to \rho e^+ e^-$ DECAYS IN THE TWO HIGGS DOUBLET MODEL WITH FLAVOR CHANGING NEUTRAL CURRENTS

1999 ◽  
Vol 14 (27) ◽  
pp. 4365-4393 ◽  
Author(s):  
E. O. ILTAN
Keyword(s):  
Branching Ratio ◽  
Higgs Doublet ◽  
Branching Ratios ◽  
New Physics ◽  
Tree Level ◽  
Efficient Tool ◽  
Flavor Changing ◽  
The Matrix ◽  
Doublet Model ◽  
Two Higgs Doublet Model

We present the leading logarithmic QCD corrections to the matrix element of the decay b→de+e- in the two Higgs doublet model with tree level flavor changing currents (model III). We continue studying the differential branching ratio and the CP-violating asymmetry for the exclusive decays B→πe+e- and B→ρe+e- and analysing the dependencies of these quantities on the selected model III parameters, ξU,D, including the leading logarithmic QCD corrections. Further, we present the forward–backward asymmetry of dileptons for the decay B→ρe+e- and discuss the dependencies to the model III parameters. We observe that there is a possibility to enhance the branching ratios and suppress the CP-violating effects for both decays in the framework of the model III. Therefore, the measurements of these quantities will be an efficient tool to search the new physics beyond the SM.

scholarly journals Direct CP violation in $$D^+ \rightarrow K^0({\bar{K}}^0) \pi ^+$$ decays as a probe for new physics

2020 ◽  
Vol 80 (7) ◽  
Author(s):  
David Delepine ◽  
Gaber Faisel ◽  
Carlos A. Ramirez
Keyword(s):  
Cp Violation ◽  
Standard Model ◽  
Parameter Space ◽  
Higgs Doublet ◽  
New Physics ◽  
Cp Asymmetry ◽  
The Standard Model ◽  
Doublet Model ◽  
Two Higgs Doublet Model ◽  
Cp Asymmetries

Abstract In this paper we investigate CP violation in charged decays of D meson. Particularly, we study the direct CP asymmetry of the Cabibbo favored non-leptonic $$D^+ \rightarrow {\bar{K}}^0 \pi ^+$$D+→K¯0π+ and the doubly Cabibbo-suppressed decay mode $$D^+ \rightarrow K^0 \pi ^+$$D+→K0π+ within standard model, two Higgs doublet model with generic Yukawa structure and left right symmetric models. In the standard model, we first derive the contributions from box and di-penguin diagrams contributing to their amplitudes which are relevant to the generation of the weak phases essential for non-vanishing direct CP violation. Then, we show that the generated phases are so tiny leading to null direct CP asymmetries of both decay modes. Regarding the two Higgs doublet model with generic Yukawa structure, after taking into account all constraints on the parameter space of the model, we show that the weak phases of the amplitudes can be enhanced compared to the standard model ones. However, the enhancement is still not enough to have sizable direct CP asymmetries. Finally, within left right symmetric models, we find that $$|A^{SM+LR}_{CP} (D^+ \rightarrow {\bar{K}}^0 \pi ^+)|\lesssim \mathcal {O}(10^{-3})$$|ACPSM+LR(D+→K¯0π+)|≲O(10-3) after respecting all relevant constraints on the parameter space of the model.

Dark energy from nondegenerate Higgs-vacuum

2019 ◽  
Vol 28 (16) ◽  
pp. 2040008
Author(s):  
Muhammad Usman ◽  
Asghar Qadir
Keyword(s):  
Dark Energy ◽  
Higgs Field ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Scalar Fields ◽  
Higgs Doublet ◽  
Late Time ◽  
True Vacuum ◽  
Doublet Model ◽  
Two Higgs Doublet Model

Scalar fields are favorite among the possible candidates for the dark energy. Most frequently discussed are those with degenerate minima at [Formula: see text]. In this paper, a slightly modified two-Higgs doublet model is taken to contain the Higgs field(s) as the dark energy candidate(s). The model considered has two nondegenerate minima at [Formula: see text], instead of one degenerate minimum at [Formula: see text]. The component fields of one SU(2) doublet ([Formula: see text]) act as the standard model (SM) Higgs, while the component fields of the second doublet ([Formula: see text]) are taken to be the dark energy candidates (lying in the true vacuum). It is found that one can arrange for late time acceleration (dark energy) by using an SU(2) Higgs doublet, whose vacuum expectation value is zero, in the quintessential regime.

scholarly journals Finger printing the presence of extra scalars in the h → Vff′ forward-backward asymmetry

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Victor Ilisie
Keyword(s):  
Cp Violation ◽  
Standard Model ◽  
Standard Model Prediction ◽  
Higgs Doublet ◽  
New Physics ◽  
The Standard Model ◽  
Model Predictions ◽  
Finger Printing ◽  
Doublet Model ◽  
Two Higgs Doublet Model

Abstract In this work we analyse the forward-backward asymmetry of the h → V f f′ decay in the Aligned two-Higgs Doublet Model. The Standard Model prediction for this asymmetry for V = W is small, as it suffers from Yukawa suppression and is absent for V = Z. This does not necessarily have to hold true in the Aligned model where these contributions can in principle be re-enhanced through the independent alignment factors ςf. In this analysis we conclude that, due to the additional contributions corresponding to the Aligned two-Higgs Doublet Model together with extra sources of CP-violation for the V = Z channel, the Standard Model predictions can be significantly modified in a great region of the parameter space. These deviations, that could be potentially measured at the High Luminosity LHC or future Higgs factories, would be a clear signal of new physics, and would shed new light on the possible extensions of the Standard Model and new sources of CP-violation.

scholarly journals Interplay of New Physics effects in (g − 2)ℓ and h → ℓ+ℓ− — lessons from SMEFT

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Svjetlana Fajfer ◽  
Jernej F. Kamenik ◽  
M. Tammaro
Keyword(s):  
Closed Operator ◽  
Higgs Doublet ◽  
New Physics ◽  
Effective Field ◽  
Tree Level ◽  
Electroweak Symmetry ◽  
Scalar Leptoquark ◽  
Doublet Model ◽  
The One ◽  
Two Higgs Doublet Model

Abstract We explore the interplay of New Physics (NP) effects in (g− 2)ℓ and h→ℓ+ℓ− within the Standard Model Effective Field Theory (SMEFT) framework, including one-loop Renormalization Group (RG) evolution of the Wilson coefficients as well as matching to the observables below the electroweak symmetry breaking scale. We include both the leading dimension six chirality flipping operators including a Higgs and SU(2)L gauge bosons as well as four-fermion scalar and tensor operators, forming a closed operator set under the SMEFT RG equations. We compare present and future experimental sensitivity to different representative benchmark scenarios. We also consider two simple UV completions, a Two Higgs Doublet Model and a single scalar LeptoQuark extension of the SM, and show how tree level matching to SMEFT followed by the one-loop RG evolution down to the electroweak scale can reproduce with high accuracy the (g−2)ℓ and h→ℓ+ℓ− contributions obtained by the complete one- and even two-loop calculations in the full models.

scholarly journals THE EFFECTS OF NON-UNIVERSAL EXTRA DIMENSIONS ON THE $\tau\rightarrow\mu\bar\nu_i\nu_i$ DECAY

2005 ◽  
Vol 20 (24) ◽  
pp. 1845-1857 ◽  
Author(s):  
E. O. ILTAN
Keyword(s):  
Extra Dimension ◽  
Extra Dimensions ◽  
Branching Ratio ◽  
Higgs Doublet ◽  
Doublet Model ◽  
Two Higgs Doublet Model

We study [Formula: see text], i = e, μ, τ decays in the two-Higgs doublet model, with the inclusion of one and two spatial non-universal extra dimensions. We observe that the branching ratio is sensitive to two extra dimensions in contrary to a single extra dimension.

scholarly journals Detailed study of the Λb → Λcτν̄τ decay

2018 ◽  
Vol 33 (29) ◽  
pp. 1850169 ◽  
Author(s):  
E. Di Salvo ◽  
F. Fontanelli ◽  
Z. J. Ajaltouni
Keyword(s):  
Standard Model ◽  
Semileptonic Decay ◽  
Form Factors ◽  
Higgs Doublet ◽  
New Physics ◽  
Beyond The Standard Model ◽  
Left Handed ◽  
The Standard Model ◽  
Analogous Formula ◽  
Two Higgs Doublet Model

We examine in detail the semileptonic decay [Formula: see text], which may confirm previous hints, from the analogous [Formula: see text] decay, of a new physics beyond the Standard Model. First of all, starting from rather general assumptions, we predict the partial width of the decay. Then we analyze the effects of five possible new physics interactions, adopting in each case five different form factors. In particular, for each term beyond the Standard Model, we find some constraints on the strength and phase of the coupling, which we combine with those found by other authors in analyzing the analogous semileptonic decays of [Formula: see text]. Our analysis involves some dimensionless quantities, substantially independent of the form factor, but which, owing to the constraints, turn out to be strongly sensitive to the kind of nonstandard interaction. We also introduce a criterion thanks to which one can discriminate among the various new physics terms: the left-handed current and the two-Higgs-doublet model appear privileged, with a neat preference for the former interaction. Finally, we suggest a differential observable that could, in principle, help to distinguish between the two cases.

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