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

2020 ◽  
Vol 2020 (5) ◽  
Author(s):  
P Maji ◽  
S Biswas ◽  
P Nayek ◽  
S Sahoo
Keyword(s):  
Branching Ratio ◽  
Form Factors ◽  
Higgs Doublet ◽  
New Physics ◽  
Model Parameters ◽  
Type I ◽  
The Standard Model ◽  
Charged Higgs ◽  
Lepton Polarization ◽  
Meson States

Abstract In 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.

Study of Λb → Λℓ+ℓ− (ℓ = e,μ,τ) decays in the G(221) model

2016 ◽  
Vol 31 (36) ◽  
pp. 1650197
Author(s):  
Shuai-Wei Wang
Keyword(s):  
Sum Rules ◽  
Branching Ratio ◽  
Form Factors ◽  
New Physics ◽  
Tree Level ◽  
Decay Channels ◽  
Flavor Changing ◽  
The Standard Model ◽  
Lepton Polarization ◽  
Text Model

We study respectively the baryonic semilepton decays [Formula: see text][Formula: see text] in the [Formula: see text] model, which includes the tree-level flavor-changing-neutral-currents (FCNCs) induced by [Formula: see text] and [Formula: see text] bosons and modifies the Wilson coefficients [Formula: see text] and [Formula: see text]. For the form factors, we use the results of QCD light-cone sum rules (LCSR) in the low [Formula: see text] region and lattice QCD in the high [Formula: see text] region, respectively. We consider the effects of this new physics (NP) model on some measured physical observables, like the differential branching ratio, the longitudinal polarization of the dilepton system, the lepton-side forward–backward asymmetry and the baryon-side forward–backward asymmetry, and find, obvious differences occur in some observables between the Standard Model (SM) and this NP model. Meanwhile, we also discuss the double lepton polarization asymmetries of these decay channels, and find, [Formula: see text], [Formula: see text] and [Formula: see text] of these decay channels are sensitive to the contribution of this NP model.

scholarly journals O(αs) CORRECTIONS TO B→ Xse+e-DECAY IN THE 2HDM

2001 ◽  
Vol 16 (33) ◽  
pp. 2151-2167 ◽  
Author(s):  
G. K. YEGHIYAN
Keyword(s):  
Branching Ratio ◽  
Resonance Region ◽  
Higgs Doublet ◽  
New Physics ◽  
Energy Scale ◽  
Order Effects ◽  
Renormalization Scale ◽  
Dilepton Invariant Mass ◽  
The Standard Model ◽  
Higher Order Effects

O(αs) QCD corrections to the inclusive B→Xse+e-decay are investigated within the two-Higgs doublet extension of the standard model (2HDM). The analysis is performed in the so-called off-resonance region; the dependence of the obtained results on the choice of the renormalization scale is examined in details. It is shown that O(αs) corrections can suppress the B→Xse+e-decay width up to 1.5–3 times (depending on the choice of the dilepton invariant mass s and the low-energy scale μ). As a result, in the experimentally allowed range of the parameter space, the relations between the B→Xse+e-branching ratio and the new physics parameters are strongly affected. It is also found that though the renormalization scale dependence of the B→Xse+e-branching is significantly reduced, higher order effects in the perturbation theory can still be non-negligible.

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 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.

scholarly journals Fingerprinting the contribution of colored scalars to the $$H^+ W^- Z(\gamma )$$ vertex

2020 ◽  
Vol 80 (12) ◽  
Author(s):  
Nabarun Chakrabarty ◽  
Indrani Chakraborty ◽  
Dilip Kumar Ghosh
Keyword(s):  
Scalar Potential ◽  
Form Factors ◽  
Higgs Doublet ◽  
New Physics ◽  
Model Parameters ◽  
Minimal Flavour Violation ◽  
Color Octet ◽  
Flavour Violation ◽  
Doublet Model ◽  
Two Higgs Doublet Model

AbstractColor-octet scalars arise in various Grand Unification scenarios and also in other models of new physics. They are also postulated for minimal flavour violation. Purely phenomenological imprints of such scalars are therefore worth looking at. Motivated by this, we perform a complete one-loop calculation of the $$H^+ \rightarrow W^+ Z (\gamma )$$ H + → W + Z ( γ ) decay in a two Higgs doublet model augmented by a color-octet $$SU(2)_L$$ S U ( 2 ) L scalar doublet. The computation is conveniently segregated into colorless and colored components. The color-octet part of the amplitude, being scaled by the color-factor, provides an overall enhancement to the form factors. Crucial constraints from perturbative unitarity, positivity of the scalar potential, oblique parameters, Higgs signal strengths and direct search of a charged Higgs and color-octet scalars are folded-in into the analysis. Sensitivity of the loop-induced $$H^+ \rightarrow W^+ Z (\gamma )$$ H + → W + Z ( γ ) vertex to other model parameters is elucidated. Finally, the prospect of observing a loop-induced $$H^+ \rightarrow W^+ Z (\gamma )$$ H + → W + Z ( γ ) interaction at the future hadronic collisions is also discussed.

scholarly journals Type-I 2HDM under the Higgs and electroweak precision measurements

2020 ◽  
Vol 2020 (8) ◽  
Author(s):  
Ning Chen ◽  
Tao Han ◽  
Shuailong Li ◽  
Shufang Su ◽  
Wei Su ◽  
...  
Keyword(s):  
Standard Model ◽  
Higgs Doublet ◽  
New Physics ◽  
Higgs Bosons ◽  
Precision Measurements ◽  
Tree Level ◽  
Type I ◽  
Loop Level ◽  
The Standard Model ◽  
Parameter Ranges

Abstract We explore the extent to which future precision measurements of the Standard Model (SM) observables at the proposed Z-factories and Higgs factories may have impacts on new physics beyond the Standard Model, as illustrated by studying the Type-I Two-Higgs-doublet model (Type-I 2HDM). We include the contributions from the heavy Higgs bosons at the tree-level and at the one-loop level in a full model-parameter space. While only small tan β region is strongly constrained at tree level, the large tan β region gets constrained at loop level due to tan β enhanced tri-Higgs couplings. We perform a multiple variable χ2 fit with non-alignment and non-degenerate masses. We find that the allowed parameter ranges could be tightly constrained by the future Higgs precision measurements, especially for small and large values of tan β. Indirect limits on the masses of heavy Higgs bosons can be obtained, which can be complementary to the direct searches of the heavy Higgs bosons at hadron colliders. We also find that the expected accuracies at the Z-pole and at a Higgs factory are quite complementary in constraining mass splittings of heavy Higgs bosons. The typical results are | cos(β − α)| < 0.05, |∆mΦ| < 200 GeV, and tan β ≳ 0.3. The reaches from CEPC, Fcc-ee and ILC are also compared, for both Higgs and Z-pole precision measurements. Comparing to the Type-II 2HDM, the 95% C.L. allowed range of cos(β − α) is larger, especially for large values of tan β.

scholarly journals Analysis of W± + 4γ in the 2HDM Type-I at the LHC

2021 ◽  
Vol 2021 (12) ◽  
Author(s):  
Yan Wang ◽  
A. Arhrib ◽  
R. Benbrik ◽  
M. Krab ◽  
B. Manaut ◽  
...  
Keyword(s):  
Higgs Boson ◽  
Parameter Space ◽  
Hadron Collider ◽  
Higgs Doublet ◽  
Charged Higgs Boson ◽  
Type I ◽  
Decay Modes ◽  
The Standard Model ◽  
Charged Higgs ◽  
Doublet Model

Abstract We analyse a light charged Higgs boson in the 2-Higgs Doublet Model (2HDM) Type-I, when its mass satisfies the condition MH±< Mt + Mb and the parameter space is consistent with theoretical requirements of self-consistency as well as the latest experimental constraints from Large Hadron Collider (LHC) and other data. Over such a parameter space, wherein the Standard Model (SM)-like state discovered at the LHC in 2012 is the heaviest CP-even state of the 2HDM, it is found that the decay modes of the charged Higgs boson are dominated by H±→ W±(∗)h. Furthermore, the light neutral Higgs boson h dominantly decays into two photons. Under these conditions, we find that the production and decay process pp → H±h → W±(∗)hh → ℓνℓ + 4γ (ℓ = e, μ) is essentially background free. However, since the W±(∗) could be largely off-shell and the h state is very light, so that both the lepton coming from the former and the photons coming from the latter could be rather soft, we perform here a full Monte Carlo (MC) analysis at the detector level demonstrating that such a W± + 4γ signal is very promising, as it would be yielding significant excesses at the LHC with an integrated luminosity of L = 300 fb−1 at both $$ \sqrt{s} $$ s = 13 and 14 TeV.

scholarly journals RareBs→γνν-Decay in Family NonuniversalZ′Model

2015 ◽  
Vol 2015 ◽  
pp. 1-5
Author(s):  
Berin Belma Şirvanlı
Keyword(s):  
Standard Model ◽  
Branching Ratio ◽  
New Physics ◽  
Model Parameters ◽  
Photon Polarization ◽  
Polarization Asymmetry ◽  
The Standard Model

The rareBs→γνν-decay with polarized photon is studied in the framework of a family nonuniversalZ′model. The branching ratio and photon polarization asymmetry to the model parameters are calculated and compared with the Standard Model. Deviations from the Standard Model will indicate the presence of new physics.

scholarly journals Disentangling QCD and new physics in D → πℓ+ℓ−

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Aoife Bharucha ◽  
Diogo Boito ◽  
Cédric Méaux
Keyword(s):  
Standard Model ◽  
Branching Ratio ◽  
Branching Ratios ◽  
New Physics ◽  
Operator Product ◽  
Beyond The Standard Model ◽  
Spectral Functions ◽  
The Standard Model ◽  
Model Independent ◽  
Weak Annihilation

Abstract In this paper we consider the decay D+ → π+ℓ+ℓ−, addressing in particular the resonance contributions as well as the relatively large contributions from the weak annihilation diagrams. For the weak annihilation diagrams we include known results from QCD factorisation at low q2 and at high q2, adapting the existing calculation for B decays in the Operator Product Expansion. The hadronic resonance contributions are obtained through a dispersion relation, modelling the spectral functions as towers of Regge-like resonances in each channel, as suggested by Shifman, imposing the partonic behaviour in the deep Euclidean. The parameters of the model are extracted using e+e− → (hadrons) and τ → (hadrons) + ντ data as well as the branching ratios for the resonant decays D+ → π+R(R → ℓ+ℓ−), with R = ρ, ω, and ϕ. We perform a thorough error analysis, and present our results for the Standard Model differential branching ratio as a function of q2. Focusing then on the observables FH and AFB, we consider the sensitivity of this channel to effects of physics beyond the Standard Model, both in a model independent way and for the case of leptoquarks.

scholarly journals NEW PHYSICS UPPER BOUND ON THE BRANCHING RATIO OF Bs → l+l-γ

2007 ◽  
Vol 22 (18) ◽  
pp. 1319-1328 ◽  
Author(s):  
ASHUTOSH KUMAR ALOK ◽  
S. UMA SANKAR
Keyword(s):  
Upper Bound ◽  
Axial Vector ◽  
Branching Ratio ◽  
New Physics ◽  
Large Contribution ◽  
Beyond The Standard Model ◽  
Standard Model Expectation ◽  
Model Expectation ◽  
The Standard Model ◽  
Large Enhancement

We consider the effect of new physics on the branching ratio of Bs → l+l-γ where l = e, μ. If the new physics is of the form scalar/pseudoscalar, then it makes no contribution to Bs → l+l-γ, unlike in the case of Bs → l+l-, where it can potentially make a very large contribution. If the new physics is in the form of vector/axial-vector operators, then the present data on B → (K, K*) l+l- does not allow a large enhancement for B(Bs → l+l- γ). If the new physics is in the form of tensor/pseudotensor operators, then the data on B → (K, K*) l+l- gives no useful constraint but the data on B → K* γ does. Here again, a large enhancement of B(Bs → l+l-γ), much beyond the Standard Model expectation, is not possible. Hence, we conclude that the present data on b → s transitions allow a large boost in B(Bs → l+l-) but not in B(Bs → l+l-γ).

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