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We study nuclear mu-e conversion in the general framework of an effective Lagrangian approach without referring to any specific realization of the physics beyond the standard model (SM) responsible for lepton flavor violation (LFV). We show…

High Energy Physics - Phenomenology · Physics 2014-11-17 Amand Faessler , Th. Gutsche , Sergey Kovalenko , V. E. Lyubovitskij , Ivan Schmidt , F. Simkovic

We consider the extended electroweak gauge group SU(2)_1 \times SU(2)_2 \times U(1)_Y where the first and second families of fermions couple to SU(2)_1 while the third family couples to SU(2)_2. Bounds based an precision electroweak…

High Energy Physics - Phenomenology · Physics 2007-05-23 David J. Muller , Satya Nandi

We extend the Zee model by introducing a vector-like lepton doublet and a flavor dependent global $U(1)$ symmetry. Flavor changing neutral currents in the quark sector can be naturally forbidden at tree level due to the $U(1)$ symmetry,…

High Energy Physics - Phenomenology · Physics 2021-09-15 Toshinori Matsui , Takaaki Nomura , Kei Yagyu

Lorentz invariance is one of the basic ingredients of quantum field theories and violations of it are stringently constrained experimentally. Therefore, the possibility of Lorentz violation (LV) is usually realized at very high energy…

High Energy Physics - Phenomenology · Physics 2021-05-17 Andreas Crivellin , Fiona Kirk , Marco Schreck

We examine the decays $t\rightarrow c\gamma$ and $c Z^0$ in the Standard Model with an extra scalar doublet and no discrete symmetry preventing tree-level flavour changing neutral currents. The Yukawa couplings of the new scalars are…

High Energy Physics - Phenomenology · Physics 2009-10-22 Michael Luke , Martin J. Savage

Neutrino masses imply the violation of lepton flavour and new physics beyond the Standard Model. However, flavour change has only been observed in oscillations. In analogy with the quark sector, we could deduce the existence of a principle…

High Energy Physics - Phenomenology · Physics 2008-11-26 Sacha Davidson , Federica Palorini

Sources of Flavor Changed Neutral Currents (FCNC) naturally emerge from a well motivated framework called 3-3-1 with right-handed neutrinos model, $331_{RHN}$ for short, mediated by an extra neutral gauge boson $Z^{\prime}$. Following…

High Energy Physics - Phenomenology · Physics 2012-06-26 D. Cogollo , A. Vital de Andrade , F. S. Queiroz , P. R. Teles

We show that, unlike mass matrices, the fermionic gauge currents of the Standard Model exhibit, at the quantum level, remarkable SU(2)_f flavor properties at the observed values of the mixing angles. They accommodate all measured mixing for…

High Energy Physics - Phenomenology · Physics 2012-03-28 Bruno Machet

We summarize the potential charged lepton flavor violation (LFV) from neutrino mass relevant models, for instance the seesaw mechanisms. In particular, we study, in a model-dependent way, the LFV signals at the high-energy hadron and lepton…

High Energy Physics - Phenomenology · Physics 2022-03-17 Yongchao Zhang

Current constraints on flavor-changing neutral currents (FCNCs) strongly indicate that any new physics emerging at the 1-10 TeV scale must adhere to the Minimal Flavor Violation (MFV) principle, where Yukawa couplings are the sole sources…

High Energy Physics - Phenomenology · Physics 2025-01-08 A. Carrillo-Monteverde , R. Escorcia Ramírez , S. Gómez-Ávila , L. Lopez-Lozano

The Minimal Lepton Flavour Violation (MLFV) framework is discussed after the recent indication for CP violation in the leptonic sector. Among the three distinct versions of MLFV, the one with degenerate right-handed neutrinos will be…

High Energy Physics - Phenomenology · Physics 2017-09-13 D. N. Dinh , L. Merlo , S. T. Petcov , R. Vega-Alvarez

We study charged lepton flavour violation in a scenario in which light neutrino masses are generated via the inverse seesaw mechanism with 3+3 gauge singlet fermions, Ni and Sj, i,j=1,2,3. Lepton mixing is predicted with the help of the…

High Energy Physics - Phenomenology · Physics 2025-07-18 F. P. Di Meglio , C. Hagedorn

By extending the electroweak gauge group to $SU(3)_L\times U(1)_Y$, the 331 model incorporates dilepton gauge bosons $Y$ which do not respect individual lepton family number. We point out that, in addition to family diagonal couplings such…

High Energy Physics - Phenomenology · Physics 2010-11-01 James T. Liu , Daniel Ng

Some interpretations of $R_{D^{(*)}}$ anomaly in $B$ meson decay using leptoquark (LQ) models can also generate top quark decays through Flavor Changing Neutral Current (FCNC). In this work we focus on two LQs, i.e. scalar $S_1$ and vector…

High Energy Physics - Phenomenology · Physics 2020-01-08 Tae Jeong Kim , Pyungwon Ko , Jinmian Li , Jiwon Park , Peiwen Wu

We have investigated a flavour model [1] which inspired by small squared-mass difference measured in solar neutrino oscillation experiments and observability in neutrinoless double beta decay experiments. In our model, the $1^{\rm st.}$ and…

High Energy Physics - Phenomenology · Physics 2017-08-23 Hiroyuki Ishida

We discuss a model in which the third generation fermions undergo a different $SU(2)$ weak interaction from the first two generation fermions. In general, a flavor changing neutral current interaction is expected. Constrained by the…

High Energy Physics - Phenomenology · Physics 2008-11-26 Ehab Malkawi , Tim Tait , C. --P. Yuan

We study flavour issues in nonsupersymmetric intersecting brane models. Specifically, the purpose of the present paper is twofold: (i) to determine whether realistic flavour structures can be obtained in these models, and (ii) to establish…

High Energy Physics - Phenomenology · Physics 2009-11-10 S. Abel , O. Lebedev , J. Santiago

We study the effects of lepton flavour violation (LFV) on the production processes e+e- --> \chi+_i \chi-_j at a linear collider with longitudinal e+ and e- beam polarizations. In the case of LFV the sneutrino mass eigenstates have no…

High Energy Physics - Phenomenology · Physics 2009-11-13 Karl Hohenwarter-Sodek , Thomas Kernreiter

A properly defined and suitably broken $U(2)$ flavour symmetry leads to successful quantitative relations between quark mass ratios and CKM angles. At the same time the intrinsic distinction introduced by $U(2)$ between the third and the…

High Energy Physics - Phenomenology · Physics 2019-07-24 Riccardo Barbieri , Robert Ziegler

In the Standard Model (SM), charged lepton flavor-violating (LFV) processes are strictly forbidden, and thus observation of LFV would signal the presence of new physics. Recently, the Muon $g{-}2$ collaboration at Fermilab reported their…

High Energy Physics - Phenomenology · Physics 2025-09-25 Zhao-Yang Zhang
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