scholarly journals Theoretical and experimental status of rare charm decays

2021 ◽  
Vol 36 (04) ◽  
pp. 2130002
Author(s):  
Hector Gisbert ◽  
Marcel Golz ◽  
Dominik Stefan Mitzel
Keyword(s):  
Standard Model ◽  
New Physics ◽  
Charm Decays ◽  
Approximate Symmetries ◽  
Experimental Status ◽  
Lepton Flavor ◽  
Energy Dynamics ◽  
Flavor Changing ◽  
The Standard Model ◽  
Rare Charm

Rare charm decays offer the unique possibility to explore flavor-changing neutral-currents in the up-sector within the Standard Model and beyond. Due to the lack of effective methods to reliably describe its low energy dynamics, rare charm decays have been considered as less promising for long. However, this lack does not exclude the possibility to perform promising searches for New Physics per se, but a different philosophy of work is required. Exact or approximate symmetries of the Standard Model allow to construct clean null-test observables, yielding an excellent road to the discovery of New Physics, complementing the existing studies in the down-sector. In this review, we summarize the theoretical and experimental status of rare charm [Formula: see text] transitions, as well as opportunities for current and future experiments such as LHCb, Belle II, BES III, the FCC-ee and proposed tau-charm factories. We also use the most recent experimental results to report updated limits on lepton-flavor conserving and lepton-flavor violating Wilson coefficients.

Lepton flavor violating decays in model

2019 ◽  
Vol 97 (12) ◽  
pp. 1270-1276
Author(s):  
P. Nayek ◽  
P. Maji ◽  
S. Sahoo
Keyword(s):  
Standard Model ◽  
Neutral Current ◽  
Branching Ratios ◽  
New Physics ◽  
Beyond The Standard Model ◽  
Lepton Flavor ◽  
Flavor Changing ◽  
The Standard Model ◽  
Flavor Changing Neutral Current ◽  
Text Model

Motivated by the hints of lepton flavor violating (LFV) decays, we study Bd,s → μτ, Bs,d → τe, and τ– → e– + e+ + e– decays in [Formula: see text] model. These LFV decays present interesting patterns that may reveal the shape of new physics beyond the standard model. Considering the effect of both Z- and [Formula: see text]-mediated flavor-changing neutral current we calculate the branching ratios for these decays. We find the branching ratios [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text].

scholarly journals Probing for new physics with rare charm baryon (Λc, Ξc, Ωc) decays

2021 ◽  
Vol 2021 (9) ◽  
Author(s):  
Marcel Golz ◽  
Gudrun Hiller ◽  
Tom Magorsch
Keyword(s):  
Standard Model ◽  
Branching Ratios ◽  
New Physics ◽  
Cp Asymmetry ◽  
Vector Coupling ◽  
Lepton Flavor ◽  
The Standard Model ◽  
Charm Baryon ◽  
Order Of Magnitude ◽  
Rare Charm

Abstract We analyze rare charm baryon decays within the standard model and beyond. We identify all null test observables in unpolarized Λc→ pℓ+ℓ−, ℓ = e, μ decays, and study the new physics sensitivities. We find that the longitudinal dilepton polarization fraction FL is sensitive to electromagnetic dipole couplings $$ {C}_7^{\left(\prime \right)} $$ C 7 ′ , and to the right-handed 4-fermion vector coupling $$ {C}_9^{\left(\prime \right)} $$ C 9 ′ . The forward-backward asymmetry, AFB, due to the GIM-suppression a standard model null test already, probes the left-handed axialvector 4-fermion coupling C10; its CP–asymmetry, $$ {A}_{\mathrm{FB}}^{\mathrm{CP}} $$ A FB CP probes CP-violating phases in C10. Physics beyond the standard model can induce branching ratios of dineutrino modes Λc→ pν$$ \overline{\nu} $$ ν ¯ up to a few times 10−5, and one order of magnitude smaller if lepton flavor universality is assumed, while standard model rates are negligible. Charged lepton flavor violation allows for striking signals into e±μ∓ final states, up to 10−6 branching ratios model-independently, and up to order 10−8 in leptoquark models. Related three-body baryon decays Ξc→ Σℓℓ, Ξc→ Λℓℓ and Ωc→ Ξℓℓ offer similar opportunities to test the standard model with |∆c| = |∆u| = 1 transitions.

scholarly journals One Loop Corrections to Decay \(\tau\rightarrow \mu\gamma\) in Economical 3-3-1 Model

2015 ◽  
Vol 25 (2) ◽  
pp. 113
Author(s):  
Truong Trong Thuc ◽  
Le Tho Hue ◽  
Dinh Phan Khoi ◽  
Nguyen Thanh Phong
Keyword(s):  
Standard Model ◽  
New Physics ◽  
Beyond The Standard Model ◽  
Lepton Flavor ◽  
Unitary Gauge ◽  
The Standard Model ◽  
Charged Leptons

Lepton flavor violating (cLFV) decays of charged leptons such as \(\tau\rightarrow \mu\gamma\), \(\tau\rightarrow e\gamma\), \(\mu\rightarrow e\gamma\),..., are now the subjects of experiments as signals of new Physics beyond the Standard Model (SM). In the limit of the unitary gauge, we prove that contributions from one loop corrections to the above decays are very small in the framework of the economical 3-3-1 model.

Study of the semileptonic Bc → ηcτ−v̄τ decay in W′ model

2021 ◽  
Author(s):  
S. Mahata ◽  
P. Maji ◽  
S. Biswas ◽  
S. Sahoo
Keyword(s):  
Standard Model ◽  
Branching Ratio ◽  
New Physics ◽  
Experimental Results ◽  
Lepton Flavor ◽  
The Standard Model ◽  
Text Model

Recently, many discrepancies between the Standard Model (SM) predictions and experimental results have been found in [Formula: see text] quark transitions. Motivated by these discrepancies, we investigated the semileptonic [Formula: see text] decay in [Formula: see text] model. In this paper, we have estimated different decay observables such as branching ratio, lepton flavor universality (LFU) ratio [Formula: see text] and forward–backward asymmetry in the SM as well as in the [Formula: see text] model. In [Formula: see text] model, we find significant deviations from the SM for the observables except for the forward–backward asymmetry. This deviation gives us a possible indication of new physics (NP).

Flavons and LFV decays and productions of pseudoscalar mesons

2019 ◽  
Vol 34 (35) ◽  
pp. 1950288
Author(s):  
Tian-Qi Li ◽  
Chong-Xing Yue
Keyword(s):  
Standard Model ◽  
Symmetry Breaking ◽  
Flavor Symmetry ◽  
Lepton Flavor ◽  
Flavor Changing ◽  
Pseudoscalar Mesons ◽  
The Standard Model

Flavons are the dynamic agent of flavor symmetry breaking and have flavor changing couplings to the Standard Model (SM) fermions. We consider their contributions to the lepton flavor violating (LFV) decays [Formula: see text] and [Formula: see text] with [Formula: see text], [Formula: see text] or [Formula: see text] and [Formula: see text] in the simplest flavon model without Higgs-flavon mixing. We find that flavons can produce significant contributions to some of these LFV decay processes.

CHARM MIXING AND CP VIOLATION AT B-FACTORIES

2014 ◽  
Vol 35 ◽  
pp. 1460413
Author(s):  
GIANLUIGI CIBINETTO ◽  
Keyword(s):  
Cp Violation ◽  
Standard Model ◽  
New Physics ◽  
Ratio Analysis ◽  
Charm Meson ◽  
Final State ◽  
Charm Decays ◽  
Decay Modes ◽  
The Standard Model ◽  
Model Predictions

CP violation in charm decays is expected to be very small in the Standard Model, at the level of 0.1% or less. A sizable excess of CP violation with respect to the Standard Model predictions could be a signature of new physics. We report on recent searches for CP violation in charm meson decays at BABAR and Belle experiments. In particular we report a lifetime ratio analysis of D0 → K+K−, π+π− with respect to D0 → K−π+ decays, which is sensitive to [Formula: see text] mixing and CP violation. We report also on searches for CPV in the 3-body D+ → K+K−π+ decay and for decay modes with a [Formula: see text] in the final state, such as [Formula: see text].

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 Lepton Flavor Violation beyond the MSSM

2015 ◽  
Vol 2015 ◽  
pp. 1-22 ◽  
Author(s):  
A. Vicente
Keyword(s):  
Standard Model ◽  
Parity Violation ◽  
New Physics ◽  
Lepton Flavor Violation ◽  
Lepton Sector ◽  
Lepton Flavor ◽  
Flavor Violation ◽  
The Standard Model ◽  
Supersymmetric Models ◽  
Characteristic Features

Most extensions of the Standard Model lepton sector predict large lepton flavor violating rates. Given the promising experimental perspectives for lepton flavor violation in the next few years, this generic expectation might offer a powerful indirect probe to look for new physics. In this review we will cover several aspects of lepton flavor violation in supersymmetric models beyond the Minimal Supersymmetric Standard Model. In particular, we will concentrate on three different scenarios: high-scale and low-scale seesaw models as well as models withR-parity violation. We will see that in some cases the LFV phenomenology can have characteristic features for specific scenarios, implying that dedicated studies must be performed in order to correctly understand the phenomenology in nonminimal supersymmetric models.

scholarly journals Experimental Review on Lepton Universality and Lepton Flavour Violation tests in B decays

2020 ◽  
Vol 234 ◽  
pp. 01004 ◽  
Author(s):  
P. de Simone
Keyword(s):  
Standard Model ◽  
Theoretical Models ◽  
New Physics ◽  
B Decays ◽  
Experimental Status ◽  
Lepton Flavour Violation ◽  
Lepton Universality ◽  
The Standard Model ◽  
Flavour Violation ◽  
Lepton Flavour

Tests of lepton flavour universality in B decays offer an excellent opportunity to test the Standard Model, and show hints of new physics in analyses performed by the LHCb, Belle and BaBar experiments. Several theoretical models proposed to explain possible violation of lepton flavour universality claim a connection with lepton flavour violation in B decays. These proceedings review the experimental status of the tests of lepton flavour universality and the searches of lepton flavour violation in B decays.

CHARM DECAYS WITHIN THE STANDARD MODEL AND BEYOND

2006 ◽  
Vol 21 (08n09) ◽  
pp. 1697-1709 ◽  
Author(s):  
MARINA ARTUSO
Keyword(s):  
Standard Model ◽  
Charm Quark ◽  
New Physics ◽  
Charm Physics ◽  
Experimental Information ◽  
Charm Decays ◽  
Mixing Parameters ◽  
The Standard Model ◽  
The Status ◽  
Good Agreement

The charm quark has unique properties that make it a very important probe of many facets of the Standard Model. New experimental information on charm decays is becoming available from dedicated experiments at charm factories, and through charm physics programs at the b-factories and hadron machines. In parallel, theorists are working on matrix element calculations based on unquenched lattice QCD, that can be validated by experimental measurements and affect our ultimate knowledge of the quark mixing parameters. Recent predictions are compared with corresponding experimental data and good agreement is found. Charm decays can also provide unique new physics signatures; the status of present searches is reviewed. Finally, charm data relevant for improving beauty decay measurements are presented.

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