scholarly journals One-loop Form Factors for \(H\rightarrow \gamma^*\gamma^*\) in \(R_{\xi}\) Gauge

2021 ◽  
Vol 32 ◽  
Author(s):  
Khiem Hong Phan ◽  
Dzung Tri Tran
Keyword(s):  
Standard Model ◽  
Form Factors ◽  
Numerical Results ◽  
Good Stability ◽  
Charged Scalar ◽  
Scalar Particles ◽  
Standard Models ◽  
Loop Form

In this paper, we present general one-loop form factors for \(H\rightarrow \gamma^* \gamma^*\) in \(R_{\xi}\) gauge, considering all cases of two on-shell, one on-shell and two off-shell for final photons. The calculations are performed in standard model and in arbitrary beyond the standard models which charged scalar particles may be exchanged in one-loop diagrams. Analytic results for the form factors are shown in general forms which are expressed in terms of the Passarino-Veltman functions. We also confirm the results in previous computations which are available for the case of two on-shell photons. The \(\xi\)-independent of the result is also discussed. We find that numerical results are good stability with varying \(\xi=0,1\) and $\xi\rightarrow \infty\).

scholarly journals Doubly Charged Higgs Bosons and Spontaneous Symmetry Breaking at eV and TeV Scales

Symmetry ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 153
Author(s):  
Janusz Gluza ◽  
Magdalena Kordiaczyńska ◽  
Tripurari Srivastava
Keyword(s):  
Gauge Group ◽  
Vacuum Expectation ◽  
Higgs Bosons ◽  
Symmetric Model ◽  
Charged Scalar ◽  
Scalar Particles ◽  
Lepton Flavor ◽  
Triplet Model ◽  
Standard Models ◽  
Doubly Charged

In this paper, beyond standard models are considered with additional scalar triplets without modification of the gauge group (Higgs Triplet Model—HTM) and with an extended gauge group S U ( 2 ) R ⊗ S U ( 2 ) L ⊗ U ( 1 ) (Left–Right Symmetric Model—LRSM). These models differ drastically in possible triplet vacuum expectation values (VEV). Within the HTM, we needed to keep the triplet VEV at most within the range of GeV to keep the electroweak ρ parameter strictly close to 1, down to electronvolts due to the low energy constraints on lepton flavor-violating processes and neutrino oscillation parameters. For LRSM, the scale connected with the S U ( 2 ) R triplet is relevant, and to provide proper masses of non-standard gauge bosons, VEV should at least be at the TeV level. Both models predict the existence of doubly charged scalar particles. In this paper, their production in the e + e − collider is examined for making a distinction in the s- and t- channels between the two models in scenarios when masses of doubly charged scalars are the same.

scholarly journals Analytic results for massless three-loop form factors

2010 ◽  
Vol 2010 (4) ◽  
Author(s):  
R. N. Lee ◽  
A. V. Smirnov ◽  
V. A. Smirnov
Keyword(s):  
Form Factors ◽  
Loop Form

scholarly journals Three loop form factors of a massive spin-2 particle with nonuniversal coupling

2017 ◽  
Vol 95 (3) ◽  
Author(s):  
Taushif Ahmed ◽  
Pulak Banerjee ◽  
Prasanna K. Dhani ◽  
Prakash Mathews ◽  
Narayan Rana ◽  
...  
Keyword(s):  
Form Factors ◽  
Massive Spin ◽  
Loop Form

scholarly journals Model-independent investigation of the RJ/ψ,ηc and ratios of decay widths of semileptonic Bc decays into a P-wave charmonium

2019 ◽  
Vol 34 (31) ◽  
pp. 1950195 ◽  
Author(s):  
Wei Wang ◽  
Ruilin Zhu
Keyword(s):  
Branching Fractions ◽  
Form Factors ◽  
P Wave ◽  
Experimental Measurements ◽  
Complementary Information ◽  
Independent Investigation ◽  
Lepton Flavor ◽  
Decay Widths ◽  
Model Independent ◽  
Standard Models

Experimental measurements of decay branching fractions of semitaunic and semimuonic [Formula: see text] into [Formula: see text] have challenged the lepton flavor universality in standard models with about two standard deviations. In this paper, we first investigate the unitary constraint on form factors of [Formula: see text] meson into [Formula: see text]-wave and [Formula: see text]-wave charmonium. Such constraint leads to the exploration of the [Formula: see text] and other ratios [Formula: see text], [Formula: see text], and [Formula: see text] in a model-independent way. These results together with future experimental measurements can be used to explore the lepton flavor universality in a more systematic way. In addition, we point out that the helicity-dependent ratios [Formula: see text] and [Formula: see text] can also provide complementary information.

scholarly journals Hypergeometric presentation for one-loop contributing to H → Z γ

2020 ◽  
Vol 2020 (5) ◽  
Author(s):  
Khiem Hong Phan ◽  
Dzung Tri Tran
Keyword(s):  
Hypergeometric Functions ◽  
Decay Channel ◽  
Form Factors ◽  
Space Time ◽  
Decay Process ◽  
Time Dimension ◽  
Higgs Decay ◽  
Arbitrary Space ◽  
First Time ◽  
Loop Form

Abstract In this paper, new analytic formulas for one-loop contributing to Higgs decay channel $H \rightarrow Z\gamma$ are presented in terms of hypergeometric functions. The calculations are performed by following the technique for tensor one-loop reduction developed in [A. I. Davydychev, Phys. Lett. B 263 (1991) 107]. For the first time, one-loop form factors for the decay process are shown which are valid at arbitrary space–time dimension $d$.

scholarly journals D → Klv semileptonic decay using lattice QCD with HISQ at physical pion masses

2018 ◽  
Vol 175 ◽  
pp. 13027 ◽  
Author(s):  
Bipasha Chakraborty ◽  
Christine Davies ◽  
Jonna Koponen ◽  
G Peter Lepage
Keyword(s):  
Standard Model ◽  
Lattice Qcd ◽  
Semileptonic Decay ◽  
Light Quark ◽  
Form Factors ◽  
New Physics ◽  
Ckm Matrix ◽  
Quark Masses ◽  
The Standard Model ◽  
Fertile Ground

he quark flavor sector of the Standard Model is a fertile ground to look for new physics effects through a unitarity test of the Cabbibo-Kobayashi-Maskawa (CKM) matrix. We present a lattice QCD calculation of the scalar and the vector form factors (over a large q2 region including q2 = 0) associated with the D→ Klv semi-leptonic decay. This calculation will then allow us to determine the central CKM matrix element, Vcs in the Standard Model, by comparing the lattice QCD results for the form factors and the experimental decay rate. This form factor calculation has been performed on the Nf = 2 + 1 + 1 MILC HISQ ensembles with the physical light quark masses.

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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