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 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.

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 Phenomenology of the partially aligned 2HDM with leptonic meson decays

2019 ◽  
Vol 34 (30) ◽  
pp. 1950198 ◽  
Author(s):  
A. Carrillo-Monteverde ◽  
S. Gómez-Ávila ◽  
R. Gómez-Rosas ◽  
L. López-Lozano ◽  
A. Rosado
Keyword(s):  
Higgs Doublet ◽  
New Physics ◽  
Tree Level ◽  
Flavor Symmetry ◽  
Leptonic Decays ◽  
Quark Sector ◽  
Leptonic Sector ◽  
Doublet Model ◽  
Free Parameters ◽  
Two Higgs Doublet Model

In this paper we present a phenomenological analysis of the Partially Aligned Two Higgs Doublet Model (PA-2HDM) by using leptonic decays of mesons and [Formula: see text]–[Formula: see text] mixing. We focus our attention in a scenario where the leading contribution to FCNC is given by the tree-level interaction with the light pseudoscalar [Formula: see text] ([Formula: see text] GeV). We show how an underlying flavor symmetry controls FCNC in the quark and lepton couplings with the pseudoscalar, without alignment between Yukawa matrices. Upper bounds on the free parameters are calculated in the context of the leptonic decays [Formula: see text] and [Formula: see text] and [Formula: see text] mixing. Also, our assumptions imply that bounds on New Physics contribution in the quark sector coming from [Formula: see text] mixing impose an upper bound on the parameters for the leptonic sector. Finally we give predictions of branching ratios for leptonic decay of mesons with FCNC and LFV.

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.

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 SCALAR DARK MATTER EFFECTS IN HIGGS AND TOP QUARK DECAYS

2007 ◽  
Vol 22 (25n28) ◽  
pp. 2121-2129 ◽  
Author(s):  
XIAO-GANG HE ◽  
HO-CHIN TSAI ◽  
TONG LI ◽  
XUE-QIAN LI
Keyword(s):  
Dark Matter ◽  
Top Quark ◽  
Neutral Current ◽  
Higgs Doublet ◽  
Tree Level ◽  
Flavor Changing ◽  
Higgs Decay ◽  
Dark Matter Relic Density ◽  
Flavor Changing Neutral Current ◽  
Two Higgs Doublet Model

We study possible observational effects of scalar dark matter, the darkon D, in Higgs h and top quark t decay processes, h → DD and t → cDD in the minimal Standard Model (SM) and its two Higgs doublet model (THDM) extension supplemented with a SM singlet darkon scalar field D. We find that the darkon D can have a mass in the range of sub-GeV to several tens of GeV, interesting for LHC and ILC colliders, to produce the required dark matter relic density. In the SM with a darkon, t → cDD only occurs at loop level giving a very small rate, while the rate for Higgs decay h → DD can be large. In THDM III with a darkon, where tree level flavor changing neutral current (FCNC) interaction exists, a sizable rate for t → cDD is also possible.

scholarly journals IMPLICATIONS OF THE RECENT TOP QUARK DISCOVERY ON TWO-HIGGS DOUBLET MODEL

1995 ◽  
Vol 10 (12) ◽  
pp. 967-972 ◽  
Author(s):  
GYE T. PARK
Keyword(s):  
Top Quark ◽  
Branching Ratio ◽  
Higgs Doublet ◽  
Recent Measurement ◽  
Model Predictions ◽  
Charged Higgs ◽  
Doublet Model ◽  
Two Higgs Doublet Model ◽  
The Impact ◽  
Top Mass

Concentrating on the impact of the very recent top quark discovery, we perform a combined analysis of two strongest constraints on the two-Higgs doublet model, one coming from the recent measurement by CLEO on the inclusive branching ratio of b→sγ decay and the other from the recent LEP data on [Formula: see text] decay. We have included the model predictions for one-loop vertex corrections to [Formula: see text] through εb. We find that the εb constraint excludes most of the less appealing window: tan β≲1 at 95% C.L. for the measured top mass mt=176±8±10 GeV from CDF. Moreover, it excludes tan β≲2 at 95% C.L. for mt≳176 GeV; combined with the b→sγ constraint, only very heavy charged Higgs (≳670 GeV) is allowed by the measured mt from CDF.

scholarly journals STUDY OF CP VIOLATION IN $\Lambda_c^+$ DECAY

2011 ◽  
Vol 26 (15) ◽  
pp. 2523-2535 ◽  
Author(s):  
XIAN-WEI KANG ◽  
HAI-BO LI ◽  
GONG-RU LU ◽  
ALAKABHA DATTA
Keyword(s):  
Angular Distribution ◽  
Cp Violation ◽  
Vector Meson ◽  
Higgs Doublet ◽  
New Physics ◽  
Angular Analysis ◽  
The Standard Model ◽  
Helicity Amplitudes ◽  
Doublet Model ◽  
Two Higgs Doublet Model

In this paper, we study CP violation in [Formula: see text] and [Formula: see text] decays, where B, P and V denote a light spin-½ baryon, pseudoscalar and a vector meson respectively. In these processes the T odd CP violating triple-product (TP) correlations are examined. The genuine CP violating observables which are composed of the helicity amplitudes occurring in the angular distribution are constructed. Experimentally, by performing a full angular analysis it is shown how one may extract the helicity amplitudes and then obtain the TP asymmetries. We estimate the TP asymmetries in [Formula: see text] decays to be negligible in the Standard Model making these processes an excellent place to look for new physics. Taking a two-Higgs doublet model, as an example of new physics, we show that large TP asymmetries are possible in these decays. Finally, we discuss how BES-III and super τ-charm experiments will be sensitive to these CP violating signals in [Formula: see text] decays.

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