scholarly journals Naturalising the third family hypercharge model for neutral current $$B{-}\hbox {anomalies}$$

2019 ◽  
Vol 79 (11) ◽  
Author(s):  
B. C. Allanach ◽  
Joe Davighi
Keyword(s):  
Gauge Symmetry ◽  
Standard Model ◽  
Neutral Current ◽  
Beyond The Standard Model ◽  
Yukawa Couplings ◽  
The Third ◽  
Standard Model Contribution ◽  
The Standard Model ◽  
Model Predictions ◽  
Flavour Violation

Abstract We consider a deformation of the Third Family Hypercharge Model, which arguably makes the model more natural. Additional non-zero charges of the spontaneously broken, family-dependent $$U(1)_F$$U(1)F gauge symmetry are assigned to the second family leptons, and the third family leptons’ charges are deformed away from their hypercharges in such a way that the $$U(1)_F$$U(1)F gauge symmetry remains anomaly-free. Second family $$U(1)_F$$U(1)F lepton charges allow a $$Z^\prime $$Z′ coupling to muons without having to assume large charged lepton mixing, which risks violating tight lepton flavour violation bounds. In this deformed version, only the bottom and top Yukawa couplings are generated at the renormalisable level, whereas the tauon Yukawa coupling is absent. The $$Z^\prime $$Z′ mediates a beyond the Standard Model contribution to an effective $$({\bar{b}} s) (\bar{\mu }\mu )$$(b¯s)(μ¯μ) vertex in the combination $$C_9=-9C_{10}$$C9=-9C10 and is able to fit the apparent discrepancy between Standard Model predictions in flavour changing neutral-current $$B-$$B-meson decays and their measurements, whilst simultaneously avoiding current constraints from direct $$Z^\prime $$Z′ searches and other measurements, when $$0.8~\text {TeV}< M_{Z^\prime } < 12.5 ~\text {TeV}$$0.8TeV<MZ′<12.5TeV.

scholarly journals B decay anomalies at LHCb

2018 ◽  
Vol 175 ◽  
pp. 01004
Author(s):  
Arantza Oyanguren
Keyword(s):  
Standard Model ◽  
B Meson ◽  
Neutral Current ◽  
New Physics ◽  
Lhcb Collaboration ◽  
Beyond The Standard Model ◽  
Clear Tendency ◽  
The Standard Model ◽  
Model Predictions ◽  
Lepton Flavour

The LHCb collaboration has provided a plethora of precise measurements of flavour observables in the last years. In the B meson sector some of these results show consistent deviations from Standard Model predictions with a clear tendency to specific New Physics scenarios. B decay anomalies are found in particular related to lepton flavour universality tests and angular observables in Flavour-Changing-Neutral-Current transitions. I review here the LHCb measurements and their experimental caveats. Results from Lattice are crucial in the coming years to verify if these anomalies are explained by QCD effects or if they are unambiguous hints of physics beyond the Standard Model.

scholarly journals RARE DECAYS AND CP VIOLATION BEYOND THE STANDARD MODEL

2006 ◽  
Vol 21 (08n09) ◽  
pp. 1738-1749 ◽  
Author(s):  
LUCA SILVESTRINI
Keyword(s):  
Cp Violation ◽  
Standard Model ◽  
Rare Decays ◽  
New Physics ◽  
Beyond The Standard Model ◽  
Unitarity Triangle ◽  
Minimal Flavour Violation ◽  
The Standard Model ◽  
The Status ◽  
Flavour Violation

We review the status of rare decays and CP violation in extensions of the Standard Model. We analyze the determination of the unitarity triangle and the model-independent constraints on new physics that can be derived from this analysis. We find stringent bounds on new contributions to [Formula: see text] and [Formula: see text] mixing, pointing either to models of minimal flavour violation or to models with new sources of flavour and CP violation in b → s transitions. We discuss the status of the universal unitarity triangle in minimal flavour violation, and study rare decays in this class of models. We then turn to supersymmetric models with nontrivial mixing between second and third generation squarks, discuss the present constraints on this mixing and analyze the possible effects on CP violation in b → s nonleptonic decays and on [Formula: see text] mixing. We conclude presenting an outlook on Lepton-Photon 2009.

scholarly journals Studies of Missing Energy Decays at Belle II

2018 ◽  
Vol 46 ◽  
pp. 1860072
Author(s):  
Yinghui Guan
Keyword(s):  
Standard Model ◽  
Rare Decays ◽  
Neutral Current ◽  
Beyond The Standard Model ◽  
Missing Energy ◽  
Final State ◽  
Full Reconstruction ◽  
The Standard Model ◽  
Belle Ii ◽  
The Spectator

The Belle II experiment at the SuperKEKB collider is a major upgrade of the KEK “B factory” facility in Tsukuba, Japan. The machine is designed for an instantaneous luminosity of [Formula: see text], and the experiment is expected to accumulate a data sample of about 50 ab[Formula: see text]. With this amount of data, decays sensitive to physics beyond the Standard Model can be studied with unprecedented precision. One promising set of modes are physics processes with missing energy such as [Formula: see text], [Formula: see text], and [Formula: see text] decays. The [Formula: see text] decay provides one of the cleanest experimental probes of the flavour-changing neutral current process [Formula: see text], which is sensitive to physics beyond the Standard Model. However, the missing energies of the neutrinos in the final state makes the measurement challenging and requires full reconstruction of the spectator [Formula: see text] meson in [Formula: see text] events. This report discusses the expected sensitivities of Belle II for these rare decays.

scholarly journals Search for Charged Lepton Flavour Violation at CMS

2018 ◽  
Vol 182 ◽  
pp. 02090
Author(s):  
Swagata Mukherjee
Keyword(s):  
Gauge Symmetry ◽  
Standard Model ◽  
Particle Physics ◽  
Charged Lepton ◽  
New Physics ◽  
Lepton Sector ◽  
Lepton Flavour Violation ◽  
The Standard Model ◽  
Flavour Violation ◽  
Lepton Flavour

Lepton flavour is a conserved quantity in the standard model of particle physics, but it does not follow from an underlying gauge symmetry. After the discovery of neutrino oscillation, it has been established that lepton flavour is not conserved in the neutral sector. Thus the lepton sector is an excellent place to look for New Physics, and in this perspective the Charged Lepton Flavour Violation is interesting. Various extensions of the standard model predict lepton flavour violating decays that can be observed at LHC. This report summarises several searches for lepton flavour violation with data collected by the CMS detector.

scholarly journals Dark photon from light scalar boson decays at FASER

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
T. Araki ◽  
K. Asai ◽  
H. Otono ◽  
T. Shimomura ◽  
Y. Takubo
Keyword(s):  
Gauge Symmetry ◽  
Standard Model ◽  
Parameter Space ◽  
Beyond The Standard Model ◽  
Scalar Boson ◽  
Dark Photon ◽  
The Standard Model ◽  
Light Scalar ◽  
Sizable Number

Abstract FASER is one of the promising experiments which search for long-lived particles beyond the Standard Model. In this paper, we focus on dark photon associating with an additional U(1) gauge symmetry, and also a scalar boson breaking this U(1) gauge symmetry. We study the sensitivity to the dark photon originated from U(1)-breaking scalar decays. We find that a sizable number of dark photon signatures can be expected in wider parameter space than previous studies.

scholarly journals A model-independent analysis of $$b{\rightarrow }s\mu ^{+}\mu ^{-}$$transitions with GAMBIT ’s FlavBit

2021 ◽  
Vol 81 (12) ◽  
Author(s):  
Jihyun Bhom ◽  
Marcin Chrzaszcz ◽  
Farvah Mahmoudi ◽  
Markus T. Prim ◽  
Pat Scott ◽  
...  
Keyword(s):  
Standard Model ◽  
Neutral Current ◽  
Current Data ◽  
Operator Product ◽  
Beyond The Standard Model ◽  
Vector Coupling ◽  
Independent Analysis ◽  
The Standard Model ◽  
Model Independent ◽  
Best Fit

AbstractThe search for flavour-changing neutral current effects in B-meson decays is a powerful probe of physics beyond the Standard Model. Deviations from SM behaviour are often quantified by extracting the preferred values of the Wilson coefficients of an operator product expansion. We use the module of the package to perform a simultaneous global fit of the Wilson coefficients $$C_7$$ C 7 , $$C_9$$ C 9 , and $$C_{10}$$ C 10 using a combination of all current data on $$b{\rightarrow }s\mu ^{+}\mu ^{-}$$ b → s μ + μ -  transitions. We further extend previous analyses by accounting for the correlated theoretical uncertainties at each point in the Wilson coefficient parameter space, rather than deriving the uncertainties from a Standard Model calculation. We find that the best fit deviates from the SM value with a significance of 6.6$$\sigma $$ σ . The largest deviation is associated with a vector coupling of muons to b and s quarks.

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 RARE FCNC-B DECAYS AT HADRON MACHINES

1993 ◽  
Vol 08 (36) ◽  
pp. 3397-3411 ◽  
Author(s):  
DAVID B. CLINE
Keyword(s):  
Standard Model ◽  
Neutral Current ◽  
Cherenkov Light ◽  
Beyond The Standard Model ◽  
B Decays ◽  
Future Prospects ◽  
Novel Technique ◽  
Flavor Changing ◽  
The Standard Model ◽  
Flavor Changing Neutral Current

We review the current studies and future prospects for studies of Flavor Changing Neutral Current (FCNC) processes, emphasizing rare B decays. These experiments will be very sensitive to physics beyond the standard model. A key problem in these studies is the method to trigger the detector. We discuss a novel technique that uses an optical-Cherenkov light trigger to select events with significant impact parameters.

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.

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