CP-ASYMMETRIES IN NEUTRAL B-MESON DECAYS IN A CLASS OF LEFT-RIGHT SYMMETRIC MODELS

1996 ◽  
Vol 11 (04) ◽  
pp. 299-306
Author(s):  
W.K. SZE ◽  
HERNG YAO
Keyword(s):  
Standard Model ◽  
B Mesons ◽  
B Meson ◽  
Standard Model Prediction ◽  
Boson Mass ◽  
Neutral B Meson ◽  
The Standard Model ◽  
Mixing Matrix ◽  
Gauge Boson Mass ◽  
Cp Asymmetries

In left-right symmetric models with a general right-handed quark mixing matrix VR, CP-asymmetries of neutral B-mesons can deviate appreciably from the standard model prediction. By assuming a Gronau-Wakaizumi (GW) form of VR, we calculate asymmetries of B0 decays to two-body CP-eigenstates for various possible right-handed gauge boson mass MR. It is found that these CP-asymmetries show a sharp transition from the GW results to the standard model ones in the neighborhood of MR≃800 GeV .

scholarly journals Flipped U(1) extended standard model and Majorana dark matter

2020 ◽  
Vol 80 (12) ◽  
Author(s):  
Cao H. Nam
Keyword(s):  
Dark Matter ◽  
Standard Model ◽  
Boson Mass ◽  
Type I ◽  
Seesaw Mechanism ◽  
Gauge Symmetries ◽  
The Standard Model ◽  
Gauge Boson Mass ◽  
The Right ◽  
Relic Abundance

AbstractWe propose a general flavor-independent extension of the Standard Model (SM) with the minimal particle content, based on the symmetry $$SU(3)_C\times SU(2)_L\times U(1)_{Y'}\times U(1)_X\times Z_2$$ S U ( 3 ) C × S U ( 2 ) L × U ( 1 ) Y ′ × U ( 1 ) X × Z 2 . In this scenario, the charge operator is identified in terms of the charges of two U(1) gauge symmetries. The light neutrino masses are generated via Type-I seesaw mechanism only with two heavy right-handed neutrinos acquiring their Majorana masses through the $$U(1)_{Y'}\times U(1)_X$$ U ( 1 ) Y ′ × U ( 1 ) X symmetry breaking. We study various experimental constraints on the parameters of the model and investigate the phenomenology of the right-handed neutrino dark matter (DM) candidate assigned a $$Z_2$$ Z 2 -odd parity. We find that the most important constraints are the observed DM relic abundance, the current LHC limits, and the ambiguity of the SM neutral gauge boson mass.

CP Violation

2019 ◽  
pp. 295-312
Author(s):  
Michael E. Peskin
Keyword(s):  
Cp Violation ◽  
Standard Model ◽  
B Meson ◽  
Experimental Tests ◽  
K Meson ◽  
Neutral B Meson ◽  
The Standard Model ◽  
T Violation

This chapter describes particle reactions that violate CP and T symmetry, the decay of the neutral K meson and the neutral B meson. It presents the Kobayashi-Maskawa model that explains how the Standard Model can provide a theory of CP and T violation and describes experimental tests of that model.

scholarly journals Z-DECAYS TO b QUARKS AND THE HIGGS BOSON MASS

1999 ◽  
Vol 14 (26) ◽  
pp. 1815-1827 ◽  
Author(s):  
J. H. FIELD
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Top Quark ◽  
Standard Model Prediction ◽  
Strong Dependence ◽  
Boson Mass ◽  
Higgs Boson Mass ◽  
The Standard Model ◽  
200 Gev ◽  
B Quark

A model independent analysis of the most recent averages of precision electroweak data from LEP and SLD finds a 3σ deviation of the parameter Ab from the standard model prediction. The fitted value of mH shows a strong dependence on the inclusion or exclusion of b quark data, and the standard model fits have poor confidence levels of a few percent when the latter are included. The good fits obtained to lepton data, c quark data and the directly measured top quark mass, give [Formula: see text] and indicate that the Higgs boson mass is most likely less than 200 GeV.

scholarly journals Muon (g − 2) in the B-LSSM

2021 ◽  
Vol 2021 (8) ◽  
Author(s):  
Jin-Lei Yang ◽  
Hai-Bin Zhang ◽  
Chang-Xin Liu ◽  
Xing-Xing Dong ◽  
Tai-Fu Feng
Keyword(s):  
Dipole Moment ◽  
Higgs Boson ◽  
Standard Model ◽  
Magnetic Dipole ◽  
Magnetic Dipole Moment ◽  
Standard Model Prediction ◽  
Boson Mass ◽  
Experimental Result ◽  
Supersymmetric Model ◽  
The Standard Model

Abstract The difference between the updated experimental result on the muon anomalous magnetic dipole moment and the corresponding theoretical prediction of the standard model on that is about 4.2 standard deviations. In this work, we calculate the muon anomalous MDM at the two-loop level in the supersymmetric B − L extension of the standard model. Considering the experimental constraints on the lightest Higgs boson mass, Higgs boson decay modes h → γγ, WW, ZZ, $$ b\overline{b} $$ b b ¯ , $$ \tau \overline{\tau} $$ τ τ ¯ , B rare decay $$ \overline{B} $$ B ¯ → Xsγ, and the transition magnetic moments of Majorana neutrinos, we analyze the theoretical predictions of the muon anomalous magnetic dipole moment in the B − L supersymmetric model. The numerical analyses indicate that the tension between the experimental measurement and the standard model prediction is remedied in the B − L supersymmetric model.

scholarly journals Search for dark photons in Higgs boson production via vector boson fusion in proton-proton collisions at $$ \sqrt{s} $$ = 13 TeV

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
A. M. Sirunyan ◽  
◽  
A. Tumasyan ◽  
W. Adam ◽  
T. Bergauer ◽  
...  
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Confidence Level ◽  
Branching Fraction ◽  
Vector Boson ◽  
Boson Mass ◽  
Higgs Boson Mass ◽  
Vector Boson Fusion ◽  
Upper Limit ◽  
The Standard Model

Abstract A search is presented for a Higgs boson that is produced via vector boson fusion and that decays to an undetected particle and an isolated photon. The search is performed by the CMS collaboration at the LHC, using a data set corresponding to an integrated luminosity of 130 fb−1, recorded at a center-of-mass energy of 13 TeV in 2016–2018. No significant excess of events above the expectation from the standard model background is found. The results are interpreted in the context of a theoretical model in which the undetected particle is a massless dark photon. An upper limit is set on the product of the cross section for production via vector boson fusion and the branching fraction for such a Higgs boson decay, as a function of the Higgs boson mass. For a Higgs boson mass of 125 GeV, assuming the standard model production rates, the observed (expected) 95% confidence level upper limit on the branching fraction is 3.5 (2.8)%. This is the first search for such decays in the vector boson fusion channel. Combination with a previous search for Higgs bosons produced in association with a Z boson results in an observed (expected) upper limit on the branching fraction of 2.9 (2.1)% at 95% confidence level.

scholarly journals Standard Model prediction of the Bc lifetime

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Jason Aebischer ◽  
Benjamín Grinstein
Keyword(s):  
Standard Model ◽  
Model Prediction ◽  
Strange Quark ◽  
Standard Model Prediction ◽  
New Physics ◽  
Operator Product ◽  
Special Focus ◽  
Third Order ◽  
Clear Cut ◽  
The Standard Model

Abstract Applying an operator product expansion approach we update the Standard Model prediction of the Bc lifetime from over 20 years ago. The non-perturbative velocity expansion is carried out up to third order in the relative velocity of the heavy quarks. The scheme dependence is studied using three different mass schemes for the $$ \overline{b} $$ b ¯ and c quarks, resulting in three different values consistent with each other and with experiment. Special focus has been laid on renormalon cancellation in the computation. Uncertainties resulting from scale dependence, neglecting the strange quark mass, non-perturbative matrix elements and parametric uncertainties are discussed in detail. The resulting uncertainties are still rather large compared to the experimental ones, and therefore do not allow for clear-cut conclusions concerning New Physics effects in the Bc decay.

A Clifford algebra-based grand unification program of gravity and the Standard Model: a review study

2014 ◽  
Vol 92 (12) ◽  
pp. 1501-1527 ◽  
Author(s):  
Carlos Castro
Keyword(s):  
Standard Model ◽  
Geometric Probability ◽  
Coupling Constants ◽  
Grand Unified Theory ◽  
Neutrino Mixing ◽  
Yang Mills ◽  
Bounded Complex ◽  
The Standard Model ◽  
Mixing Matrix ◽  
Homogeneous Domains

A Clifford Cl(5, C) unified gauge field theory formulation of conformal gravity and U(4) × U(4) × U(4) Yang–Mills in 4D, is reviewed along with its implications for the Pati–Salam (PS) group SU(4) × SU(2)L × SU(2)R, and trinification grand unified theory models of three fermion generations based on the group SU(3)C × SU(3)L × SU(3)R. We proceed with a brief review of a unification program of 4D gravity and SU(3) × SU(2) × U(1) Yang–Mills emerging from 8D pure quaternionic gravity. A realization of E8 in terms of the Cl(16) = Cl(8) ⊗ Cl(8) generators follows, as a preamble to F. Smith’s E8 and Cl(16) = Cl(8) ⊗ Cl(8) unification model in 8D. The study of chiral fermions and instanton backgrounds in CP2 and CP3 related to the problem of obtaining three fermion generations is thoroughly studied. We continue with the evaluation of the coupling constants and particle masses based on the geometry of bounded complex homogeneous domains and geometric probability theory. An analysis of neutrino masses, Cabbibo–Kobayashi–Maskawa quark-mixing matrix parameters, and neutrino-mixing matrix parameters follows. We finalize with some concluding remarks about other proposals for the unification of gravity and the Standard Model, like string, M, and F theories and noncommutative and nonassociative geometry.

scholarly journals Flavor physics: Precision as an avenue to discovery

2020 ◽  
Vol 35 (01) ◽  
pp. 1930018
Author(s):  
Diego Guadagnoli
Keyword(s):  
Cp Violation ◽  
Standard Model ◽  
Flavor Physics ◽  
Standard Model Prediction ◽  
New Physics ◽  
Effective Theory ◽  
Theory Approach ◽  
Long Distance ◽  
The Standard Model ◽  
The Impact

This paper describes the work pursued in the years 2008–2013 on improving the Standard Model prediction of selected flavor-physics observables. The latter includes: (1) [Formula: see text], that quantifies indirect CP violation in the [Formula: see text] system and (2) the very rare decay [Formula: see text], recently measured at the LHC. Concerning point (1), the paper describes our reappraisal of the long-distance contributions to [Formula: see text],[Formula: see text] that have permitted to unveil a potential tension between CP violation in the [Formula: see text]- and [Formula: see text]-system. Concerning point (2), the paper gives a detailed account of various systematic effects pointed out in Ref. 4 and affecting the Standard Model [Formula: see text] decay rate at the level of 10% — hence large enough to be potentially misinterpreted as nonstandard physics, if not properly included. The paper further describes the multifaceted importance of the [Formula: see text] decays as new physics probes, for instance how they compare with [Formula: see text]-peak observables at LEP, following the effective-theory approach of Ref. 5. Both cases (1) and (2) offer clear examples in which the pursuit of precision in Standard Model predictions offered potential avenues to discovery. Finally, this paper describes the impact of the above results on the literature, and what is the further progress to be expected on these and related observables.

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