scholarly journals LEPTON FLAVOR VIOLATION IN INVERSE SEESAW MODEL

2013 ◽  
Vol 28 (38) ◽  
pp. 1350151 ◽  
Author(s):  
KE-SHENG SUN ◽  
TAI-FU FENG ◽  
GUO-HUI LUO ◽  
XIU-YI YANG ◽  
JIAN-BIN CHEN
Keyword(s):  
Large Scale ◽  
Branching Ratio ◽  
Mass Term ◽  
Lepton Flavor Violation ◽  
Neutrino Mixing ◽  
Lepton Flavor ◽  
Flavor Violation ◽  
Conversion Rates ◽  
Upper Limits ◽  
Wide Range

We analyze the lepton flavor violation processes μ-e conversion, li→ljγ and li→3lj in framework of the Standard Model (SM) extended with inverse seesaw mechanism, as a function of [Formula: see text] that parametrizes the departure from unitary of the light neutrino mixing sub-matrix [Formula: see text]. In a wide range of [Formula: see text], the predictions on the μ-e conversion rates and the branching ratio of μ→eγ are sizeable to be compatible with the experimental upper limits or future experimental sensitivities. For large scale of [Formula: see text], the predictions on branching ratios of other lepton flavor processes can also reach the experimental upper limits or future experimental sensitivities. The value of [Formula: see text] depends on the determinant of the Majorana mass term Mμ. Finally, searching for lepton flavor violation processes in experiment provides us more opportunities for the searches of seesaw nature of the neutrino masses.

scholarly journals Two-loop radiative seesaw, muon g − 2, and τ-lepton-flavor violation with DM constraints

2021 ◽  
Vol 2021 (9) ◽  
Author(s):  
Chuan-Hung Chen ◽  
Takaaki Nomura
Keyword(s):  
Cross Sections ◽  
Branching Ratio ◽  
Scalar Coupling ◽  
Lepton Flavor Violation ◽  
Gauge Bosons ◽  
Lepton Flavor ◽  
Flavor Violation ◽  
Upper Limits ◽  
Relic Density ◽  
Scattering Cross Sections

Abstract The quartic scalar coupling λ5 term, which violates the lepton-number by two units in the Ma-model, is phenomenologically small when the model is applied to the lepton-flavor violation (LFV) processes. In order to dynamically generate the λ5 parameter through quantum loop effects and retain the dark matter (DM) candidate, we extend the Ma-model by adding a Z2-odd vector-like lepton doublet and a Z2-even Majorana singlet. With the new couplings to the Higgs and gauge bosons, the observed DM relic density can be explained when the upper limits from the DM-nucleon scattering cross sections are satisfied. In addition to the neutrino data and LFV constraints, it is found that the DM relic density can significantly exclude the free parameter space. Nevertheless, the resulting muon g − 2 mediated by the inert charged-Higgs can fit the 4.2σ deviation between the experimental measurement and the SM result, and the branching ratio for τ → μγ can be as large as the current upper limit when the rare μ → (eγ, 3e) decays are suppressed. In addition, it is found that the resulting BR(τ → μρ) can reach the sensitivity of Belle II with an integrated luminosity of 50 ab−1.

scholarly journals LEPTON FLAVOR VIOLATING li→ljγγ DECAYS INDUCED BY SCALAR UNPARTICLE

2008 ◽  
Vol 23 (39) ◽  
pp. 3331-3339 ◽  
Author(s):  
E. O. ILTAN
Keyword(s):  
Branching Ratio ◽  
The Other ◽  
Radiative Decays ◽  
Lepton Flavor Violation ◽  
Lepton Flavor ◽  
Flavor Violation ◽  
Upper Limit ◽  
Upper Limits ◽  
Scaling Dimension ◽  
Photon Coupling

We study the radiative lepton flavor violating li→ljγγ decays in the case that the lepton flavor violation is induced by the scalar unparticle mediation. We restrict the scaling dimension du and the scalar unparticle–photon–photon coupling by using the experimental upper limit of the branching ratio of the decay μ→eγγ. Furthermore, we predict the BRs of the other radiative decays by using the restrictions we get. We observe that the measurements of upper limits of BRs of these decays ensure considerable information for testing the possible signals coming from unparticle physics.

LEPTON FLAVOR VIOLATION, LEPTOGENESIS AND NEUTRINO MIXING IN QUARK-LEPTON COMPLEMENTARITY SCENARIOS

2007 ◽  
Vol 22 (31) ◽  
pp. 5875-5888 ◽  
Author(s):  
WERNER RODEJOHANN ◽  
KATHRIN A. HOCHMUTH
Keyword(s):  
Detailed Analysis ◽  
Beta Decay ◽  
Neutrinoless Double Beta Decay ◽  
Double Beta Decay ◽  
Lepton Flavor Violation ◽  
Neutrino Mixing ◽  
Lepton Flavor ◽  
Flavor Violation

We conduct a detailed analysis of the phenomenology of two predictive see-saw scenarios which lead to the Quark-Lepton Complementarity relation θ12+θC = π/4. The neutrino mixing observables and their correlations, neutrinoless double beta decay, lepton flavor violating decays such as μ → eγ and leptogenesis are discussed. The features which allow to distinguish the scenarios are identified.

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.

scholarly journals Search for lepton flavor violation at future lepton colliders

2017 ◽  
Vol 32 (24) ◽  
pp. 1750127 ◽  
Author(s):  
Gi-Chol Cho ◽  
Hanako Shimo
Keyword(s):  
Electron Beam ◽  
Linear Collider ◽  
International Linear Collider ◽  
Lepton Flavor Violation ◽  
Lepton Flavor ◽  
Flavor Violation ◽  
Upper Limits ◽  
Lepton Colliders ◽  
Order Of Magnitude ◽  
Fermi Contact

Lepton flavor violating (LFV) processes, [Formula: see text] and [Formula: see text] ([Formula: see text] or [Formula: see text]), via four-Fermi contact interactions at future International Linear Collider (ILC) are studied. Taking account of previous experimental results of LFV processes [Formula: see text] and [Formula: see text], we find that the upper limits on the LFV parameters for [Formula: see text] could be improved at the ILC experiment using the polarized electron beam. The improvement of the upper limits could be nearly an order of magnitude as compared to previous ones.

scholarly journals Test of lepton flavor universality and search for lepton flavor violation in B → Kℓℓ decays

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
S. Choudhury ◽  
◽  
S. Sandilya ◽  
K. Trabelsi ◽  
A. Giri ◽  
...  
Keyword(s):  
Branching Fraction ◽  
Branching Fractions ◽  
Final States ◽  
Lepton Flavor Violation ◽  
Dilepton Invariant Mass ◽  
Lepton Flavor ◽  
Flavor Violation ◽  
Belle Detector ◽  
Upper Limits ◽  
Theoretical Predictions

Abstract We present measurements of the branching fractions for the decays B → Kμ+μ− and B → Ke+e−, and their ratio (RK), using a data sample of 711 fb−1 that contains 772 × 106$$ B\overline{B} $$ B B ¯ events. The data were collected at the ϒ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider. The ratio RK is measured in five bins of dilepton invariant-mass-squared (q2): q2 ∈ (0.1, 4.0), (4.00, 8.12), (1.0, 6.0), (10.2, 12.8) and (> 14.18) GeV2/c4, along with the whole q2 region. The RK value for q2 ∈ (1.0, 6.0) GeV2/c4 is $$ {1.03}_{-0.24}^{+0.28} $$ 1.03 − 0.24 + 0.28 ± 0.01. The first and second uncertainties listed are statistical and systematic, respectively. All results for RK are consistent with Standard Model predictions. We also measure CP-averaged isospin asymmetries in the same q2 bins. The results are consistent with a null asymmetry, with the largest difference of 2.6 standard deviations occurring for the q2 ∈ (1.0, 6.0) GeV2/c4 bin in the mode with muon final states. The measured differential branching fractions, $$ d\mathrm{\mathcal{B}} $$ d ℬ /dq2, are consistent with theoretical predictions for charged B decays, while the corresponding values are below the expectations for neutral B decays. We have also searched for lepton-flavor-violating B → Kμ±e∓ decays and set 90% confidence-level upper limits on the branching fraction in the range of 10−8 for B+ → K+μ±e∓, and B0 → K0μ±e∓ modes.

scholarly journals A SEARCH FOR LEPTON FLAVOR VIOLATION IN TAU DECAYS ATBABAR

2005 ◽  
Vol 20 (15) ◽  
pp. 3343-3345
Author(s):  
◽  
OLGA IGONKINA
Keyword(s):  
Background Level ◽  
Lepton Flavor Violation ◽  
Tau Decays ◽  
Lepton Flavor ◽  
Flavor Violation ◽  
Upper Limit ◽  
Upper Limits

We present a recent BABAR search for lepton flavor violation in tau decays. The search for τ → ℓℓℓ(ℓ = e, μ) decays is based on a data sample of 91.6 fb-1. No signal is found in any of six channels and 90% CL upper limits are set in the range of (1 - 3) × 10-7. The search for τ → μγ decay is done with a 63 fb-1data sample. The number of observed events is consistent with expected background level and a preliminary upper limit is set at 2 × 10-6at 90% CL.

Discriminating Majorana neutrino phases in the light of lepton flavor violation and leptogenesis in type I+II seesaw models

2015 ◽  
Vol 30 (22) ◽  
pp. 1550130 ◽  
Author(s):  
Rupam Kalita ◽  
Debasish Borah
Keyword(s):  
Mass Matrix ◽  
Majorana Neutrino ◽  
Neutrino Masses ◽  
Type I ◽  
Type Ii ◽  
Lepton Flavor Violation ◽  
Neutrino Mixing ◽  
Lepton Flavor ◽  
Flavor Violation ◽  
Best Fit

We study the effects of Majorana neutrino phases in lepton flavor violation and the origin of matter–antimatter asymmetry through the mechanism of leptogenesis within the framework of a model where both type I and type II seesaw mechanisms can contribute to tiny neutrino masses. We parametrize the type I seesaw mass matrix by assuming it to give rise to a tri-bimaximal (TBM) type neutrino mixing which predicts [Formula: see text]. The type II seesaw mass matrix is then constructed in such a way that the necessary deviation from TBM mixing and the best fit values of neutrino parameters can be obtained when both type I and type II seesaw contributions are taken into account. Considering both subleading as well as equally dominating type II seesaw term, we first constrain the Majorana CP phases from the requirement of producing correct baryon asymmetry through leptogenesis and then incorporating the experimental bounds on lepton flavor violating decays [Formula: see text] and [Formula: see text].

scholarly journals Lepton flavor changing Higgs decays in the littlest Higgs model with T-parity

2017 ◽  
Vol 2017 (8) ◽  
Author(s):  
Francisco del Aguila ◽  
Lluis Ametller ◽  
Jose Ignacio Illana ◽  
Jose Santiago ◽  
Pere Talavera ◽  
...  
Keyword(s):  
Higgs Mass ◽  
Branching Ratio ◽  
Finite Amplitude ◽  
Higgs Model ◽  
Lepton Flavor Violation ◽  
Lepton Flavor ◽  
Flavor Violation ◽  
Flavor Changing ◽  
Phenomenological Studies ◽  
The Right

Abstract We calculate loop induced lepton flavor violating Higgs decays in the Littlest Higgs model with T-parity. We find that a finite amplitude is obtained only when all contributions from the T-odd lepton sector are included. This is in contrast to lepton flavor violating processes mediated by gauge bosons where the partners of the right-handed mirror leptons can be decoupled from the spectrum. These partners are necessary to cancel the divergence in the Higgs mass introduced by the mirror leptons but are otherwise unnecessary and assumed to be decoupled in previous phenomenological studies. Further-more, as we emphasize, including the partner leptons in the spectrum also introduces a new source of lepton flavor violation via their couplings to the physical pseudo-Goldstone electroweak triplet scalar. Although this extra source also affects lepton flavor changing gauge transitions, it decouples from these amplitudes in the limit of heavy mass for the partner leptons. We find that the corresponding Higgs branching ratio into taus and muons can be as large as ∼ 0.2 × 10−6 for T-odd masses of the order a few TeV, a demanding challenge even for the high luminosity LHC.

scholarly journals Charged lepton flavor violation at the EIC

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Vincenzo Cirigliano ◽  
Kaori Fuyuto ◽  
Christopher Lee ◽  
Emanuele Mereghetti ◽  
Bin Yan
Keyword(s):  
Cross Sections ◽  
Charged Lepton ◽  
Hadron Collider ◽  
Effective Field ◽  
Background Suppression ◽  
Lepton Flavor Violation ◽  
Final State ◽  
Lepton Flavor ◽  
Flavor Violation ◽  
Discovery Potential

Abstract We present a comprehensive analysis of the potential sensitivity of the Electron-Ion Collider (EIC) to charged lepton flavor violation (CLFV) in the channel ep→τX, within the model-independent framework of the Standard Model Effective Field Theory (SMEFT). We compute the relevant cross sections to leading order in QCD and electroweak corrections and perform simulations of signal and SM background events in various τ decay channels, suggesting simple cuts to enhance the associated estimated efficiencies. To assess the discovery potential of the EIC in τ-e transitions, we study the sensitivity of other probes of this physics across a broad range of energy scales, from pp→eτX at the Large Hadron Collider to decays of B mesons and τ leptons, such as τ→eγ, τ→eℓ+ℓ−, and crucially the hadronic modes τ→eY with Y∈π, K, ππ, Kπ, …. We find that electroweak dipole and four-fermion semi-leptonic operators involving light quarks are already strongly constrained by τ decays, while operators involving the c and b quarks present more promising discovery potential for the EIC. An analysis of three models of leptoquarks confirms the expectations based on the SMEFT results. We also identify future directions needed to maximize the reach of the EIC in CLFV searches: these include an optimization of the τ tagger in hadronic channels, an exploration of background suppression through tagging b and c jets in the final state, and a global fit by turning on all SMEFT couplings, which will likely reveal new discovery windows for the EIC.

Sign in / Sign up

Export Citation Format

Share Document