Related papers: Probing $\mu e \gamma \gamma$ contact interactions…

The calculation of the $\mu$ decay is performed in V-A theory taking into account that, in agreement with the observation of the oscillations, the neutrinos must be massive. Provided that the masses of the electron and muon neutrinos are…

We studied the radiative muon decay $\mu^+ \to e^+\nu\bar{\nu}\gamma$ by using for the first time an almost fully polarized muon source. We identified a large sample (~13000) of these decays in a total sample of 1.8x10^14 positive muon…

Exploring the leptonic sector in frontier experiments is more of importance nowadays, since the conservation of lepton flavor and total lepton number are not guaranteed anymore in the Standard Model after the discovery of neutrino…

We study electron-electron contact-interaction searches in the process e^+e^-\to e^+e^- at a future e^+e^- Linear Collider with both beams longitudinally polarized. We evaluate the model-independent constraints on the coupling constants,…

Experiments are planned to improve the sensitivity of mu-e conversion from the current ~ 10^{-12} to 10^{-16} - 10^{-18}. If the muon (bound to the nucleus) could be polarised, a spin asymmetry of the final state electron is sensitive to CP…

The experimental search for coherent neutrinoless conversion of muon to electron in the presence of a nucleus, aims to probe the possibility of charged lepton flavour violation. The COMET experiment at J-PARC is one such setup offering…

Within the frameworks of the light-front quark model (LFQM) and chiral perturbation theory (ChPT) of $O(p^6)$, we reevaluate the form factors of the $K^+ \to \gamma$ transition. We use these form factors to study the decay of $K^+ \to e^+…

I describe the new generation of muon-to-electron conversion experiments, COMET and Mu2e, being constructed to make use of new high power pulsed muon beams a J-PARC and Fermilab respectively. A brief overview of the physics explored by the…

We have performed a global analysis of muon decay measurements to establish model-independent limits on the space-time structure of the muon decay matrix element. We find limits on the scalar, vector and tensor coupling of right- and…

We study the exotic muon decays with five charged tracks in the final state. First, we investigate the Standard Model rate for $\mu^+ \to 3e^+\,2e^-\,2\nu$ ($B = 4.0\times 10^{-10})$ and find that the Mu3e experiment should have tens to…

Nucleon decays put extremely stringent bounds on baryon-number-violating interactions. However, in case the corresponding operators involve only $\tau$ leptons, the direct two-body decays, e.g., $p\to\pi^0 \tau^+$, are kinematically not…

While the muon $g-2$ anomaly can be successfully explained by some new physics models, most of them are severely constrained by the $\mu \to e \gamma$ bound. This tension is more transparent from the effective field theory perspective, in…

Searches for neutrinoless-double beta decay rates are crucial in addressing questions within fundamental symmetries and neutrino physics. The rates of these decays depend not only on unknown parameters associated with neutrinos, but also on…

We consider the process $\mu \to \nu_{e}e\bar{\nu}_{\mu} $in the framework of a two Higgs doublet model with flavor changing neutral currents (FCNC). Since FCNC generates in turn flavor changing charged currents in the lepton sector, this…

Numerous accidental near-degeneracies exist between the $2\nu_2$ and $\nu_4$ rotation-vibration energy levels of ammonia. Transitions between these two states possess significantly enhanced sensitivity to a possible variation of the…

The $e^+e^-$ pair production in collisions of muon with atoms is considered to all orders in the parameter $Z\alpha$. We obtain energy distribution of $e^+$ and $e^-$ as well as energy loss of muon passing through matter with heavy atoms.…

In the framework of the seesaw models with triplets of fermions, we evaluate the decay rates of $\mu \to e \gamma$ and $\tau \to l \gamma$ transitions. We show that although, due to neutrino mass constraints, those rates are in general…

Searches for new physics using muons are reviewed. Particular attention is paid to muon number non-conserving processes, like the decay muon-->e+gamma and muon-electron conversion in muonic atoms. Also, experimental determinations and…

The low-energy two neutrino-two photon interactions in the presence of homogeneous magnetic field are studied. The cross sections in external magnetic field are shown to be larger than in vacuum by factor $\sim (m_W /m_e) ^4(B/B_c) ^2$. The…

We examine commonly used approaches to deal with the scattering of electrons from a bound nucleon. Several prescriptions are shown to be related by gauge transformations. Nevertheless, due to current non-conservation, they yield different…