scholarly journals IMPLICATION OF sin 2β FROM GLOBAL FIT AND B→J/ψKS

2001 ◽  
Vol 16 (28) ◽  
pp. 4547-4565 ◽  
Author(s):  
YUE-LIANG WU ◽  
YU-FENG ZHOU
Keyword(s):  
Standard Model ◽  
Higgs Doublet ◽  
New Physics ◽  
Current Data ◽  
Beyond The Standard Model ◽  
Flavor Violation ◽  
Flavor Changing ◽  
The Standard Model ◽  
Global Fit ◽  
The One

The measurement of sin 2β is discussed within and beyond the standard model. In the presence of new physics, the angle β extracted from the global fit (denoted by [Formula: see text]) and the one extracted from B→J/ψKS(denoted by βJ/ψ) are in general all different from the "true" angle β which is the weak phase of CKM matrix element [Formula: see text]. Possible new physics effects on the ratio [Formula: see text] is studied and parametrized in a most general form. It is shown that the ratio Rβmay provide a useful tool in probing new physics. The experimental value of Rβis obtained through an update of the global fit of the unitarity triangle with the latest data and found to be less than unity at 1σ level. The new physics effects on Rβfrom the models with minimum flavor violation (MFV) and the standard model with two-Higgs-doublet (S2HDM) are studied in detail. It is found that the MFV models seem to give a relative large value Rβ≥1. With the current data, this may indicate that this kind of new physics may be disfavored and alternative new physics with additional phases appears more relevant. As an illustration for models with additional phase beyond CKM phase, the S2HDM effects on Rβare studied and found to be easily coincide with the data due to the flavor changing neutral Higgs interaction.

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 DETERMINING αs FROM MEASUREMENTS AT Z: HOW NATURE PROMPTS US ABOUT NEW PHYSICS

1995 ◽  
Vol 10 (07) ◽  
pp. 605-613 ◽  
Author(s):  
M. SHIFMAN
Keyword(s):  
Standard Model ◽  
New Physics ◽  
Low Energy ◽  
Beyond The Standard Model ◽  
The Standard Model ◽  
Standard Deviations ◽  
The One

The value of αs (Mz) emerging from the so-called global fits based mainly on the data at the Z peak (and assuming the standard model) is three standard deviations higher than the one stemming from the low-energy phenomenology. The corresponding value of Λ QCD is very large, ~500 MeV, and is incompatible with crucial features of QCD. If persists, the discrepancy should be interpreted as due to contributions to the Z-quark-antiquark vertices which go beyond the standard model.

scholarly journals Quark-flavor-changing Higgs decays from a universal extra dimension

2020 ◽  
Vol 35 (24) ◽  
pp. 2050141
Author(s):  
Carlos M. Farrera ◽  
Alejandro Granados-González ◽  
Héctor Novales-Sánchez ◽  
J. Jesús Toscano
Keyword(s):  
Standard Model ◽  
Extra Dimension ◽  
New Physics ◽  
Tree Level ◽  
Universal Extra Dimension ◽  
Loop Level ◽  
Flavor Changing ◽  
The Standard Model ◽  
The One ◽  
Kaluza Klein

Kaluza–Klein fields characterizing, from a four-dimensional viewpoint, the presence of compact universal extra dimensions would alter low-energy observables through effects determined by some compactification scale, [Formula: see text], since the one-loop level, thus being particularly relevant for physical phenomena forbidden at tree level by the Standard Model. This paper explores, for the case of one universal extra dimension, such new-physics contributions to Higgs decays [Formula: see text], into pairs of quarks with different flavors, a sort of decay process which, in the Standard Model, strictly occurs at the loop level. Finite results, decoupling as [Formula: see text], are calculated. Approximate short expressions, valid for large compactification scales, are provided. We estimate that Kaluza–Klein contributions lie below predictions from the Standard Model, being about 2 to 3 orders of magnitude smaller for compactification scales within [Formula: see text].

scholarly journals CP violating effects in 210Fr and prospects for new physics beyond the Standard Model

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Nanako Shitara ◽  
Nodoka Yamanaka ◽  
Bijaya Kumar Sahoo ◽  
Toshio Watanabe ◽  
Bhanu Pratap Das
Keyword(s):  
Standard Model ◽  
Higgs Sector ◽  
Higgs Doublet ◽  
New Physics ◽  
Beyond The Standard Model ◽  
Internal Electric Field ◽  
Many Body ◽  
The Standard Model ◽  
The Many ◽  
Two Higgs Doublet Model

Abstract We report theoretical results of the electric dipole moment (EDM) of 210Fr which arises from the interaction of the EDM of an electron with the internal electric field in an atom and the scalar-pseudoscalar electron-nucleus interaction; the two dominant sources of CP violation in this atom. Employing the relativistic coupled-cluster theory, we evaluate the enhancement factors for these two CP violating interactions to an accuracy of about 3% and analyze the contributions of the many-body effects. These two quantities in combination with the projected sensitivity of the 210Fr EDM experiment provide constraints on new physics beyond the Standard Model. Particularly, we demonstrate that their precise values are necessary to account for the effect of the bottom quark in models in which the Higgs sector is augmented by nonstandard Yukawa interactions such as the two-Higgs doublet model.

scholarly journals Lepton Flavor Violation at muon-electron colliders

2020 ◽  
Vol 2020 (10) ◽  
Author(s):  
Fabio Bossi ◽  
Paolo Ciafaloni
Keyword(s):  
Gauge Symmetry ◽  
Standard Model ◽  
Z Boson ◽  
New Physics ◽  
Beyond The Standard Model ◽  
Lepton Flavor Violation ◽  
Foreseeable Future ◽  
Lepton Flavor ◽  
Flavor Violation ◽  
The Standard Model

Abstract Lepton Flavor Violating (LFV) processes are clear signals of physics beyond the Standard Model. We investigate the possibility of measuring this kind of processes at present and foreseeable future muon-electron colliders, taking into account present day bounds from existing experiments. As a model of new physics we consider a Z’ boson with a Ut(1) gauge symmetry and generic couplings. Processes that violate lepton flavor by two units seem to be particularly promising.

scholarly journals EFFECT OF BOTH Z AND Z′ MEDIATED FLAVOR-CHANGING NEUTRAL CURRENTS ON THE BARYONIC RARE DECAY Λb→Λℓ+ℓ-

2009 ◽  
Vol 24 (32) ◽  
pp. 6223-6235 ◽  
Author(s):  
S. SAHOO ◽  
C. K. DAS ◽  
L. MAHARANA
Keyword(s):  
Standard Model ◽  
Z Boson ◽  
Rare Decay ◽  
Branching Ratio ◽  
New Physics ◽  
Beyond The Standard Model ◽  
Neutral Currents ◽  
Flavor Changing ◽  
The Standard Model ◽  
Flavor Changing Neutral Currents

We study the effect of both Z and Z′ mediated flavor-changing neutral currents (FCNCs) on the Λb→Λℓ+ℓ-(ℓ = μ, τ) rare decay. We find the branching ratio is reasonably enhanced from its Standard Model value due to the effect of both Z and Z′ mediated FCNCs, and gives the possibility of new physics beyond the Standard Model. The contribution of Z′ boson depends upon the precise value of MZ′.

CP ASYMMETRIES IN B0DECAYS BEYOND THE STANDARD MODEL

1991 ◽  
Vol 06 (08) ◽  
pp. 1253-1266 ◽  
Author(s):  
CLAUDIO O. DIB ◽  
DAVID LONDON ◽  
YOSEF NIR
Keyword(s):  
Standard Model ◽  
New Physics ◽  
The Other ◽  
Beyond The Standard Model ◽  
Neutral Currents ◽  
Flavor Changing ◽  
The Standard Model ◽  
Model Predictions ◽  
The Many ◽  
Cp Asymmetries

Of the many ingredients of the Standard Model that are relevant to the analysis of CP asymmetries in B0 decays, some are likely to hold even beyond the Standard Model while others are sensitive to new physics. Consequently, certain predictions are maintained while others may show dramatic deviations from the Standard Model. Many classes of models may show clear signatures when the asymmetries are measured: four quark generations, Z-mediated flavor-changing neutral currents, supersymmetry and “real superweak” models. On the other hand, models of left-right symmetry and multi-Higgs sectors with natural flavor conservation are unlikely to modify the Standard Model predictions.

scholarly journals New physics explanations of aμ in light of the FNAL muon g − 2 measurement

2021 ◽  
Vol 2021 (9) ◽  
Author(s):  
Peter Athron ◽  
Csaba Balázs ◽  
Douglas H. J. Jacob ◽  
Wojciech Kotlarski ◽  
Dominik Stöckinger ◽  
...  
Keyword(s):  
Dark Matter ◽  
Standard Model ◽  
Higgs Doublet ◽  
New Physics ◽  
Beyond The Standard Model ◽  
Average Deviation ◽  
Dark Matter Relic Density ◽  
Wide Range ◽  
The Standard Model ◽  
Parameter Ranges

Abstract The Fermilab Muon g −2 experiment recently reported its first measurement of the anomalous magnetic moment $$ {a}_{\mu}^{\mathrm{FNAL}} $$ a μ FNAL , which is in full agreement with the previous BNL measurement and pushes the world average deviation $$ \Delta {a}_{\mu}^{2021} $$ ∆ a μ 2021 from the Standard Model to a significance of 4.2σ. Here we provide an extensive survey of its impact on beyond the Standard Model physics. We use state-of-the-art calculations and a sophisticated set of tools to make predictions for aμ, dark matter and LHC searches in a wide range of simple models with up to three new fields, that represent some of the few ways that large ∆aμ can be explained. In addition for the particularly well motivated Minimal Supersymmetric Standard Model, we exhaustively cover the scenarios where large ∆aμ can be explained while simultaneously satisfying all relevant data from other experiments. Generally, the aμ result can only be explained by rather small masses and/or large couplings and enhanced chirality flips, which can lead to conflicts with limits from LHC and dark matter experiments. Our results show that the new measurement excludes a large number of models and provides crucial constraints on others. Two-Higgs doublet and leptoquark models provide viable explanations of aμ only in specific versions and in specific parameter ranges. Among all models with up to three fields, only models with chirality enhancements can accommodate aμ and dark matter simultaneously. The MSSM can simultaneously explain aμ and dark matter for Bino-like LSP in several coannihilation regions. Allowing under abundance of the dark matter relic density, the Higgsino- and particularly Wino-like LSP scenarios become promising explanations of the aμ result.

The long journey to the Higgs boson and beyond at the LHC: Emphasis on CMS

2016 ◽  
Vol 31 (32) ◽  
pp. 1630058
Author(s):  
Tejinder Singh Virdee
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Hadron Collider ◽  
Heavy Particle ◽  
New Physics ◽  
Beyond The Standard Model ◽  
Cms Experiment ◽  
The Standard Model ◽  
Electroweak Sector ◽  
The One

Since 2010 there has been a rich harvest of results on standard model physics by the ATLAS and CMS experiments operating on the Large Hadron Collider. In the summer of 2012, a spectacular discovery was made by these experiments of a new, heavy particle. All the subsequently analysed data point strongly to the properties of this particle as those expected for the Higgs boson associated with the Brout–Englert–Higgs mechanism postulated to explain the spontaneous symmetry breaking in the electroweak sector, thereby explaining how elementary particles acquire mass. This article focuses on the CMS experiment, the technological challenges encountered in its construction, describing some of the physics results obtained so far, including the discovery of the Higgs boson, and searches for the widely anticipated new physics beyond the standard model, and peer into the future involving the high-luminosity phase of the LHC. This article is complementary to the one by Peter Jenni4 that focuses on the ATLAS experiment.

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