scholarly journals Search for lepton-flavor-violating tau-lepton decays to ℓγ at Belle

2021 ◽  
Vol 2021 (10) ◽  
Author(s):  
◽  
K. Uno ◽  
K. Hayasaka ◽  
K. Inami ◽  
I. Adachi ◽  
...  
Keyword(s):  
Standard Model ◽  
Charged Lepton ◽  
Branching Fractions ◽  
New Physics ◽  
Lepton Flavor Violation ◽  
Full Data ◽  
Lepton Flavor ◽  
Flavor Violation ◽  
The Standard Model ◽  
Lepton Decays

Abstract Charged lepton flavor violation is forbidden in the Standard Model but possible in several new physics scenarios. In many of these models, the radiative decays τ± → ℓ±γ (ℓ = e, μ) are predicted to have a sizeable probability, making them particularly interesting channels to search at various experiments. An updated search via τ± → ℓ±γ using full data of the Belle experiment, corresponding to an integrated luminosity of 988 fb−1, is reported for charged lepton flavor violation. No significant excess over background predictions from the Standard Model is observed, and the upper limits on the branching fractions, $$ \mathcal{B} $$ B (τ± → μ±γ) ≤ 4.2 × 10−8 and $$ \mathcal{B} $$ B (τ± → e±γ) ≤ 5.6 × 10−8, are set at 90% confidence level.

scholarly journals Lepton Flavor Violating μ- - e- Conversion: An Overview

2021 ◽  
Vol 13 (3) ◽  
pp. 1057-1074
Author(s):  
P. Verma ◽  
- Vivekanand ◽  
K. Chaturvedi
Keyword(s):  
Standard Model ◽  
New Physics ◽  
Beyond The Standard Model ◽  
Lepton Flavor Violation ◽  
Lepton Flavor ◽  
Flavor Violation ◽  
Highly Sensitive ◽  
The Standard Model ◽  
Discovery Potential ◽  
Lepton Decays

The search for lepton flavor violation in charged lepton decays is a highly sensitive tool to look for physics beyond the Standard Model. Among the possible processes, µ-decays are considered to have the largest discovery potential in most of the standard model extensions. Many searches have been performed in the past, but no evidence has been found so far. In this paper, we have reviewed the current theoretical and experimental status of the field of muon to electron decay and its potential to search for new physics beyond the Standard Model. Future prospects of experiments for further progress in this field are also discussed.

scholarly journals Searching for charged lepton flavor violation at ep colliders

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Stefan Antusch ◽  
A. Hammad ◽  
Ahmed Rashed
Keyword(s):  
Standard Model ◽  
Charged Lepton ◽  
Neutral Current ◽  
Effective Theory ◽  
Theory Approach ◽  
Lepton Flavor Violation ◽  
Lepton Flavor ◽  
Flavor Violation ◽  
The Standard Model ◽  
Order Of Magnitude

Abstract We investigate the sensitivity of electron-proton (ep) colliders for charged lepton flavor violation (cLFV) in an effective theory approach, considering a general effective Lagrangian for the conversion of an electron into a muon or a tau via the effective coupling to a neutral gauge boson or a neutral scalar field. For the photon, the Z boson and the Higgs particle of the Standard Model, we present the sensitivities of the LHeC for the coefficients of the effective operators, calculated from an analysis at the reconstructed level. As an example model where such flavor changing neutral current (FCNC) operators are generated at loop level, we consider the extension of the Standard Model by sterile neutrinos. We show that the LHeC could already probe the LFV conversion of an electron into a muon beyond the current experimental bounds, and could reach more than an order of magnitude higher sensitivity than the present limits for LFV conversion of an electron into a tau. We discuss that the high sensitivities are possible because the converted charged lepton is dominantly emitted in the backward direction, enabling an efficient separation of the signal from the background.

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 Lepton flavor violation and collider searches in a type I + II seesaw model

2019 ◽  
Vol 79 (11) ◽  
Author(s):  
Manoel M. Ferreira ◽  
Tessio B. de Melo ◽  
Sergey Kovalenko ◽  
Paulo R. D. Pinheiro ◽  
Farinaldo S. Queiroz
Keyword(s):  
Standard Model ◽  
New Physics ◽  
Neutrino Masses ◽  
Type I ◽  
Lepton Flavor Violation ◽  
Charged Scalar ◽  
Lepton Flavor ◽  
Flavor Violation ◽  
The Standard Model ◽  
Doubly Charged

AbstractNeutrinos are massless in the Standard Model. The most popular mechanism to generate neutrino masses are the type I and type II seesaw, where right-handed neutrinos and a scalar triplet are augmented to the Standard Model, respectively. In this work, we discuss a model where a type I + II seesaw mechanism naturally arises via spontaneous symmetry breaking of an enlarged gauge group. Lepton flavor violation is a common feature in such setup and for this reason, we compute the model contribution to the $$\mu \rightarrow e\gamma $$μ→eγ and $$\mu \rightarrow 3e$$μ→3e decays. Moreover, we explore the connection between the neutrino mass ordering and lepton flavor violation in perspective with the LHC, HL-LHC and HE-LHC sensitivities to the doubly charged scalar stemming from the Higgs triplet. Our results explicitly show the importance of searching for signs of lepton flavor violation in collider and muon decays. The conclusion about which probe yields stronger bounds depends strongly on the mass ordering adopted, the absolute neutrino masses and which much decay one considers. In the 1–5 TeV mass region of the doubly charged scalar, lepton flavor violation experiments and colliders offer orthogonal and complementary probes. Thus if a signal is observed in one of the two new physics searches, the other will be able to assess whether it stems from a seesaw framework.

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 A search for charged lepton flavor violation in the Mu2e experiment

2020 ◽  
Vol 35 (19) ◽  
pp. 2030007
Author(s):  
Manolis Kargiantoulakis
Keyword(s):  
Charged Lepton ◽  
New Physics ◽  
Muon Beam ◽  
Integrated System ◽  
Beyond The Standard Model ◽  
Lepton Flavor Violation ◽  
Lepton Flavor ◽  
Flavor Violation ◽  
Wide Range ◽  
Discovery Potential

The Mu2e experiment will search for the neutrino-less conversion of a muon into an electron in the field of an aluminum nucleus. An observation would be the first signal of charged lepton flavor violation and de facto evidence for new physics beyond the Standard Model. The clean signature of the conversion process offers an opportunity for a powerful search: Mu2e will probe four orders of magnitude beyond current limits, with real discovery potential over a wide range of well-motivated new physics models. This goal requires an integrated system of solenoids that will create the most intense muon beam in the world, and suppression of all possible background sources. The Mu2e components are currently being constructed, with the experiment planned to begin operations in the Fermilab Muon Campus within the next few years.

Supersymmetric Lepton Flavor Violation, the Muon Anomalous Magnetic Moment, and e- e- Colliders

2003 ◽  
Vol 18 (16) ◽  
pp. 2769-2778
Author(s):  
Graham D. Kribs
Keyword(s):  
Standard Model ◽  
Magnetic Moment ◽  
Anomalous Magnetic Moment ◽  
International Workshop ◽  
Lepton Flavor Violation ◽  
Muon Anomalous Magnetic Moment ◽  
Lepton Flavor ◽  
Flavor Violation ◽  
Central Value ◽  
The Standard Model

I explain the theoretical connection between lepton flavor violation and muon g - 2 in supersymmetry1. Given any central value deviation of muon g - 2 from the standard model that is assumed to be due to weak scale supersymmetry, I show that stringent bounds on lepton flavor violating scalar masses can be extracted. These bounds are essentially independent of supersymmetric parameter space. I then briefly compare this indirect handle on supersymmetric lepton flavor violation with direct observation at a future lepton collider operating in the e- e- mode. This is a summary of a talk given at e- e-01: 4th International Workshop on Electron-Electron Interactions at TeV Energies.

scholarly journals THEORETICAL OVERVIEW ON TAU PHYSICS

2006 ◽  
Vol 21 (27) ◽  
pp. 5652-5659 ◽  
Author(s):  
ANTONIO PICH
Keyword(s):  
Standard Model ◽  
Present Status ◽  
Model Structure ◽  
Lepton Flavor Violation ◽  
Lepton Flavor ◽  
Flavor Violation ◽  
Lepton Universality ◽  
The Standard Model ◽  
Theoretical Overview

Precise measurements of the τ lepton properties provide stringent tests of the Standard Model structure and accurate determinations of its parameters. We overview the present status of a few selected topics: lepton universality, QCD tests and the determination of αs, msand |Vus| from hadronic τ decays, and lepton flavor violation phenomena.

scholarly journals The LFV decays Bd,s0 → eμ(eτ,μτ) with one neutral singlet scalar

2018 ◽  
Vol 33 (36) ◽  
pp. 1850214
Author(s):  
Ke-Sheng Sun ◽  
Xiu-Yi Yang
Keyword(s):  
Standard Model ◽  
Theoretical Prediction ◽  
Numerical Results ◽  
Minimal Extension ◽  
Lepton Flavor Violation ◽  
Lepton Flavor ◽  
Flavor Violation ◽  
The Standard Model

Taking account of the constraint from radiative two-body decays [Formula: see text], we investigate the lepton flavor violation decays [Formula: see text] in the framework of the minimal extension of the Standard Model with one neutral singlet scalar. The couplings [Formula: see text], [Formula: see text] and [Formula: see text] between the different generation leptons and scalar [Formula: see text] are constrained by the current bounds of [Formula: see text]. The numerical results show that the theoretical prediction of [Formula: see text] strongly depends on the couplings [Formula: see text] ([Formula: see text] or [Formula: see text]) between down-type quarks and new scalar. The contributions from couplings [Formula: see text], [Formula: see text] and [Formula: see text] between up-type quark and new scalar are less dominant.

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