Related papers: Lepton number violation in tau lepton decays
We search for lepton-flavor-violating tau decays into a lepton (electron or muon) and an f0(980) meson using 671 fb-1 of data collected with the Belle detector at the KEKB asymmetric-energy e+e- collider. No events are observed and we set…
We study possible contributions of heavy sterile neutrinos $\nu_h$ to the decays $\tau^-\to e^{\pm}(\mu^{\pm})\pi^{\mp}\pi^-$. From the experimental upper bounds on their rates we derive new constraints on the $\nu_h-\nu_{\tau}$ mixing in…
We have searched for the lepton flavor violating decays $\tau^-\to \ell^-\ks$ ($\ell = e {or} \mu$), using a data sample of 281 fb$^{-1}$ collected with the Belle detector at the KEKB $e^+e^-$ asymmetric-energy collider. No evidence for a…
The effective Majorana mass which determines the rate of the neutrinoless double beta decay, |<m>|, is considered in the case of three-neutrino mixing and massive Majorana neutrinos. Assuming a rather precise determination of the parameters…
We study the possibility of future $e^{+}e^{-}$ colliders to disentangle different new physics contributions to the production of heavy sterile Majorana neutrinos in the lepton number violating channel $e^{+}e^{-}\rightarrow l^{+} l^{+}+ 4…
We report results of a search for tau lepton decays strongly suppressed in the Standard Model based on the world-largest data sample accumulated with the Belle detector at the KEKB asymmetric-energy e+e- collider. The decays include: lepton…
We confront the indications of lepton flavor universality (LFU) violation observed in semi-tauonic $B$ meson decays with new physics (NP) searches using high $p_T$ tau leptons at the LHC. Using effective field theory arguments we correlate…
We investigate the rare electromagnetic decays of neutral vector mesons (exemplified by $J/\psi$, $\Upsilon$, $\rho^0$, $\omega,\phi$, \ldots) into four charged leptons ($2(e^+e^-)$, $2(\mu^+\mu^-)$, $2(\tau^+\tau^-)$, $e^+e^-\mu^+\mu^-$,…
We analyse the effects of Dirac and Majorana neutrinos on leptonic decays of muon and tau leptons using the most general four-lepton effective interaction Hamiltonian of dimension six. We calculate the specific energy and angular…
In this work, we study the lepton number violating W boson and top quark decays via intermediate on-shell Majorana neutrinos Nj into three charged leptons and a light neutrino. We discuss the neutrino oscillation effects present in the…
We calculate the rates for the charged lepton flavour violating (LFV) decays l_i -> l_j gamma, tau -> l pi, tau -> l eta('), mu^- -> e^-e^+e^-, the six three-body leptonic decays tau^- -> l_i^- l_j^+ l_k^- and the rate for mu-e conversion…
We present a search for the decay B+ -> tau+ nu using 288 inverse femtobarns of data collected at the Upsilon(4S) resonance with the BaBar detector at the SLAC PEP-II B-Factory. A sample of events with one reconstructed semileptonic B decay…
It is well known that there exist many mechanisms that may contribute to neutrinoless double beta decay (0nbb-decay). By exploiting the fact that the associated nuclear matrix elements are target dependent we show that, given definite…
We derive the upper bounds on certain products of R-parity- and lepton-flavor-violating couplings from $B^\pm \to l^\pm \nu$ decays. These modes of B-meson decays can constrain the product combinations of the couplings with one or more…
We search for the lepton flavor-violating "tau -> mu gamma" decay using 29.7 million tau pairs accumulated by the Belle experiment. The main background sources are found to be tau pairs with "tau -> mu nu nu" decay and radiative dimuon…
We study a new supersymmetric mechanism for lepton flavour violation in muon and tau decays and muon -> e conversion in nuclei, within a minimal extension of the MSSM with low-mass heavy singlet neutrinos and sneutrinos. We find that the…
In the Standard Model of particle physics, lepton flavour and lepton number are conserved quantities although no fundamental symmetry demands their conservation. I present recent results of searches for lepton flavour and lepton number…
We have searched for the tau lepton flavor violating decays tau- -> l-K0s (l = e or mu), using a data sample of 281 fb^-1 collected with the Belle detector at the KEKB e+e- asymmetric-energy collider. No evidence for a signal was found in…
The most sensitive experiment to date to search for the muon and electron lepton number violating decay $K^0_L \to \mu^\pm e^\mp$ has detected no events consistent with this process. Based on this result, the 90% confidence level upper…
In the context of TeV-scale lepton number violating (LNV) interactions, we illustrate the interplay between leptogenesis, neutrinoless double beta ($0\nu\beta\beta$) decay, and LNV searches at proton-proton colliders. Using a concrete model…