scholarly journals THE DYNAMICAL MODELS AND THE $Z \rightarrow b\bar{b}$ ASYMMETRY

2002 ◽  
Vol 17 (05) ◽  
pp. 261-268 ◽  
Author(s):  
CHONGXING YUE ◽  
YUANBEN DAI ◽  
HONG LI
Keyword(s):  
Experimental Data ◽  
Standard Model ◽  
New Physics ◽  
Dynamical Models ◽  
Effective Lagrangian ◽  
The Standard Model ◽  
Free Parameters

Motivated by the 3.2σ(1.4σ) deviations between the recent experimental value for [Formula: see text] and the standard model (SM) prediction, we examine the effect of new physics (NP) on the [Formula: see text] couplings [Formula: see text] and [Formula: see text]. First we focus our attention on the dynamical models. Then, using effective Lagrangian techniques, we discuss the corrections of NP to [Formula: see text] and [Formula: see text]. We find some kinds of NP which might explain the recently experimental data about Rb and [Formula: see text]. However, the free parameters of these kinds of NP must be severely constrained.

CAN WE RELATE TIME-REVERSAL VIOLATION TO NEW PHYSICS PROCESSES IN WEAK HADRONIC DECAYS?

2013 ◽  
Vol 22 (03) ◽  
pp. 1330006 ◽  
Author(s):  
Z. J. AJALTOUNI ◽  
E. DI SALVO
Keyword(s):  
Experimental Data ◽  
Cp Violation ◽  
Standard Model ◽  
Time Reversal ◽  
Review Paper ◽  
New Physics ◽  
Hadronic Decays ◽  
Beyond The Standard Model ◽  
Weak Decays ◽  
The Standard Model

This review paper stresses the possible connection between time-reversal violation and new physics processes beyond the standard model. In particular, this violation is proposed as an alternative to CP violation in the search for such unkown processes. Emphasis is put on the weak decays of heavy hadrons, especially beauty ones. Specific methods for extracting useful parameters from experimental data are elaborated in order to test TR symmetry. These methods could be used successfully in the analysis of the LHC data.

New physics through interference of nonstandard interactions with Standard Model in rare decays of Bc+ meson

2018 ◽  
Vol 33 (30) ◽  
pp. 1850171
Author(s):  
Shakeel Mahmood ◽  
Farida Tahir ◽  
Azeem Mir
Keyword(s):  
Experimental Data ◽  
Standard Model ◽  
Rare Decays ◽  
New Physics ◽  
Final State ◽  
Neutrino Interactions ◽  
Bc Meson ◽  
Free Parameters

We investigate the nonstandard neutrino interactions (NSI) in the rare decays of [Formula: see text] mesons involving neutrinos in the final state. It is suggested that the interference between Standard Model and nonstandard interaction can provide sizeable contribution. We calculate the limits on NSI free parameters ([Formula: see text], [Formula: see text]) and compare them with experimental data.

scholarly journals D * Polarization as an Additional Constraint on New Physics in the b → cτ ν ¯ τ Transition

Particles ◽  
2020 ◽  
Vol 3 (1) ◽  
pp. 193-207
Author(s):  
Mikhail A. Ivanov ◽  
Jürgen G. Körner ◽  
Pietro Santorelli ◽  
Chien-Thang Tran
Keyword(s):  
Experimental Data ◽  
Standard Model ◽  
Branching Fractions ◽  
Experimental Studies ◽  
Form Factors ◽  
Unknown Origin ◽  
New Physics ◽  
Constituent Quark Model ◽  
Tensor Operator ◽  
The Standard Model

Measurements of the branching fractions of the semileptonic decays B → D ( * ) τ ν ¯ τ and B c → J / ψ τ ν ¯ τ systematically exceed the Standard Model predictions, pointing to possible signals of new physics that can violate lepton flavor universality. The unknown origin of new physics realized in these channels can be probed using a general effective Hamiltonian constructed from four-fermion operators and the corresponding Wilson coefficients. Previously, constraints on these Wilson coefficients were obtained mainly from the experimental data for the branching fractions. Meanwhile, polarization observables were only theoretically studied. The situation has changed with more experimental data having become available, particularly those regarding the polarization of the tau and the D * meson. In this study, we discuss the implications of the new data on the overall picture. We then include them in an updated fit of the Wilson coefficients using all hadronic form factors from our covariant constituent quark model. The use of our form factors provides an analysis independent of those in the literature. Several new-physics scenarios are studied with the corresponding theoretical predictions provided, which are useful for future experimental studies. In particular, we find that under the one-dominant-operator assumption, no operator survives at 1 σ . Moreover, the scalar operators O S L and O S R are ruled out at 2 σ if one uses the constraint B ( B c → τ ν τ ) ≤ 10 % , while the more relaxed constraint B ( B c → τ ν τ ) ≤ 30 % still allows these operators at 2 σ , but only minimally. The inclusion of the new data for the D * polarization fraction F L D * reduces the likelihood of the right-handed vector operator O V R and significantly constrains the tensor operator O T L . Specifically, the F L D * alone rules out O T L at 1 σ . Finally, we show that the longitudinal polarization P L τ of the tau in the decays B → D * τ ν ¯ τ and B c → J / ψ τ ν ¯ τ is extremely sensitive to the tensor operator. Within the 2 σ allowed region, the best-fit value T L = 0.04 + i 0.17 predicts P L τ ( D * ) = − 0.33 and P L τ ( J / ψ ) = − 0.34 , which are at about 33% larger than the Standard Model (SM) prediction P L τ ( D * ) = − 0.50 and P L τ ( J / ψ ) = − 0.51 .

scholarly journals ANOMALOUS HIGGS COUPLINGS

1999 ◽  
Vol 14 (20) ◽  
pp. 3121-3156 ◽  
Author(s):  
M. C. GONZALEZ-GARCIA
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Higgs Doublet ◽  
New Physics ◽  
Boson Production ◽  
Gauge Bosons ◽  
Effective Interactions ◽  
Decay Modes ◽  
Effective Lagrangian ◽  
The Standard Model

We review the effects of new effective interactions on Higgs-boson phenomenology. New physics in the electroweak bosonic sector is expected to induce additional interactions between the Higgs doublet field and the electroweak gauge bosons, leading to anomalous Higgs couplings as well as anomalous gauge-boson self-interactions. Using a linearly realized SU (2)L× U (1)Y invariant effective Lagrangian to describe the bosonic sector of the Standard Model, we review the effects of the new effective interactions on the Higgs-boson production rates and decay modes. We summarize the results from searches for the new Higgs signatures induced by the anomalous interactions in order to constrain the scale of new physics, in particular at CERN LEP and Fermilab Tevatron colliders.

scholarly journals $\bar{B}\rightarrow X_s\gamma$ in the μνSSM

2014 ◽  
Vol 29 (38) ◽  
pp. 1450196 ◽  
Author(s):  
Hai-Bin Zhang ◽  
Guo-Hui Luo ◽  
Tai-Fu Feng ◽  
Shu-Min Zhao ◽  
Tie-Jun Gao ◽  
...  
Keyword(s):  
Experimental Data ◽  
Standard Model ◽  
Rare Decay ◽  
New Physics ◽  
Majorana Neutrino ◽  
Decay Process ◽  
Neutrino Masses ◽  
Beyond The Standard Model ◽  
Seesaw Mechanism ◽  
The Standard Model

The μνSSM, one of supersymmetric extensions beyond the Standard Model, introduces three singlet right-handed neutrino superfields to solve the μ problem and can generate three tiny Majorana neutrino masses through the seesaw mechanism. In this paper, we investigate the rare decay process [Formula: see text] in the μνSSM, under a minimal flavor violating assumption for the soft breaking terms. Constrained by the SM-like Higgs with mass around 125 GeV, the numerical results show that the new physics can fit the experimental data for [Formula: see text] and further constrain the parameter space.

THE STANDARD MODEL WITH THREE GENERATIONS: CLOSING IN ON THE TOP QUARK MASS

1989 ◽  
Vol 04 (04) ◽  
pp. 753-768 ◽  
Author(s):  
F. HALZEN ◽  
C. S. KIM ◽  
S. PAKVASA
Keyword(s):  
Experimental Data ◽  
Standard Model ◽  
Top Quark ◽  
Quark Mass ◽  
New Physics ◽  
Experimental Information ◽  
Beyond The Standard Model ◽  
Top Quark Mass ◽  
Three Generations ◽  
The Standard Model

Within the standard model with three generations we fit the top quark mass mt by combining experimental information of [Formula: see text] and [Formula: see text] mixing, CP-violation in K decay and the ratio Γ(W)/Γ(Z) extracted from [Formula: see text] collider data. We conclude that [Formula: see text] where the "systematic error" associated with theoretical ambiguities in performing the calculations is likely to be significantly larger than the quoted 10 GeV error associated with input parameters and experimental data. The anticipated value essentially guarantees the discovery of the top quark by existing experiments. Failure to discover it should force us to reconsider generally accepted calculational procedures before it signals new physics beyond the standard model. We discuss this in some detail.

scholarly journals Relativistic calculations of R(D(∗)), R(Ds(∗)), R(ηc) and R(J/ψ)

2020 ◽  
Vol 35 (17) ◽  
pp. 2050076
Author(s):  
Tian Zhou ◽  
Tianhong Wang ◽  
Yue Jiang ◽  
Xiao-Ze Tan ◽  
Geng Li ◽  
...  
Keyword(s):  
Experimental Data ◽  
Standard Model ◽  
Semileptonic Decay ◽  
Form Factors ◽  
Relativistic Correction ◽  
New Physics ◽  
Decay Rates ◽  
The Standard Model ◽  
Model Predictions

Recently, the deviation of the ratios [Formula: see text], [Formula: see text] and [Formula: see text] have been found between experimental data and the Standard Model predictions, which may be the hint of new physics. In this work, we calculate these ratios within the Standard Model by using the improved instantaneous Bethe–Salpeter method. The emphasis is pad to the relativistic correction of the form factors. The results are [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text], which are consistent with predictions of other models and the experimental data. The semileptonic decay rates and corresponding form factors at zero recoil are also given.

scholarly journals Survival of new physics: Anomaly-free neutral gauge boson at the LHC

2014 ◽  
Vol 29 (08) ◽  
pp. 1450046
Author(s):  
Ying Zhang ◽  
Qing Wang
Keyword(s):  
Standard Model ◽  
Direct Detection ◽  
Decay Channel ◽  
Hadron Collider ◽  
New Physics ◽  
Beyond The Standard Model ◽  
Effective Lagrangian ◽  
Charge Assignment ◽  
Electron Positron ◽  
The Standard Model

An anomaly-free U(1)′ effective Lagrangian as a benchmark of new physics beyond the standard model is proposed to survey the maximal parameter space constrained by the precise electroweak measurements at the Large Electron-Positron Collider (LEP) and direct detection of the dilepton decay channel at [Formula: see text] at the Large Hadron Collider (LHC). By the global fit of the effective couplings of the Z boson to the Standard Model fermions, parameters Δ11, Δ21 and g′′Δ31 related to mixings and r related to the U(1)′ charge assignment are bounded. The allowed areas are plotted not only in the r–g′′ plane, but also in the mZ′–g′′ plane. They show that a sub-TeV Z′ is still permissible as long as the coupling g′′ is of order ~0.01. The results hint at possible new physics beyond the standard model. A prediction of the possible signal for the dilepton decay channel at [Formula: see text] at LHC is also provided.

scholarly journals Impacts of multi-Higgs on the ρ parameter, decays of a neutral Higgs to WW and ZZ, and a charged Higgs to WZ

2018 ◽  
Vol 33 (26) ◽  
pp. 1850152 ◽  
Author(s):  
Jian-Yong Cen ◽  
Jung-Hsin Chen ◽  
Xiao-Gang He ◽  
Jhih-Ying Su
Keyword(s):  
Experimental Data ◽  
Standard Model ◽  
New Physics ◽  
Tree Level ◽  
The Standard Model ◽  
Charged Higgs ◽  
Crucial Information ◽  
Custodial Symmetry

In the Standard Model (SM), the [Formula: see text] parameter is equal to 1 and the ratio [Formula: see text] of Higgs [Formula: see text] and Higgs [Formula: see text] is also equal to 1 at the tree level. When going beyond the SM with more than one type of Higgs representations, these quantities may be different from the SM predictions which can provide crucial information about new physics. There may also exist a certain charged Higgs [Formula: see text] decays into a [Formula: see text] and a [Formula: see text]. Imposing a custodial symmetry can force the parameter [Formula: see text] to be equal to 1 with certain predictions for [Formula: see text] and [Formula: see text]. However, imposing [Formula: see text] without custodial symmetry may have different predictions. We show how differences arise and how to use experimental data to obtain information about the underlying physics in a model with the SM, plus a real and a complex [Formula: see text] triplet.

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