Related papers: The tau leptons theory and experimental data: Mont…
We make predictions and propose tests for the semi-leptonic decays $B\to D^{(*)} l \bar{\nu}_l$ and $\Lambda_b\to \Lambda_c l \bar{\nu}_l$, with $l$ = $e$, $\mu$ and $\tau$. Preliminarily, we study such processes according to the $\ell-s$…
The inclusive tau lepton hadronic decay is studied within Dispersive approach to QCD. The significance of effects due to hadronization is convincingly demonstrated. The approach on hand proves to be capable of describing experimental data…
We apply an analytic description to the inclusive decay of the $\tau$ lepton. We argue that this method gives not only a self-consistent description of the process both in the timelike region by using the initial expression for $R_\tau$ and…
We study the $L\to l l' l' \nu_l \nu_L$ decays ($L=\tau,\mu$; $l,l'=\mu,e$) in the Standard Model (SM) and in the effective field theory (EFT) description of the weak charged current at low energy, both for polarized and unpolarized $L$,…
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…
Dark particles with lepton-flavor-violating couplings to the tau lepton can induce rare neutrinoless $\tau$ decays with large final state multiplicities. We study models where transitions of the type $\tau^\pm\to \ell^\pm\,\phi$, with…
We present a study of Michel parameters in leptonic $\tau$ decays using experimental information collected at the Belle detector. Michel parameters are extracted in the unbinned maximum likelihood fit of the…
We have measured branching fractions of hadronic $\tau$ decays involving an $\eta$ meson using 485 fb^{-1} of data collected with the Belle detector at the KEKB asymmetric-energy e^+e^- collider. We obtain the following branching fractions:…
The evaluation, systematic analysis and numerical study of the semileptonic $\tau$-lepton decays with two mesons in the final state has been made in the frame of the standard model extended by right handed neutrinos. In the analysis,…
Belle II is an experiment designed to study billions of $\tau$-lepton, $b$- and $c$-quark decays observed with low background in asymmetric-energy electron-positron collisions at the SuperKEKB $B$-factory. In March 2019, the newly completed…
Predictions for semi-leptonic decay rates of the tau lepton into two and three meson final states with one or two kaons are derived, including a discussion of K_S pi- K_S, K_L pi- K_L and K_S pi- K_L. The hadronic matrix elements are…
A search for the neutrinoless, lepton-flavor violating decay of the tau lepton into three charged leptons has been performed using 376 fb^{-1} of data collected at an e^+e^- center-of-mass energy around 10.58 GeV with the BaBar detector at…
We extend the effective theory of Minimal Lepton Flavor Violation (MLFV) by including four-lepton operators. We compute the rates for mu -> 3 e and tau -> 3 ell decays and point out several new ways to test the hypothesis of MLFV. We also…
This thesis describes a new a measurement of the tau lepton polarization and its forward-backward asymmetry at the Z resonance using the OPAL detector. This measurement is based on analyses of the tau->electron, muon and pion (Kaon) decays…
Tau lepton decays with open strangeness in the final state are measured with the OPAL detector at LEP to determine the strange hadronic spectral function of the tau lepton. The decays T- ->(Kpi)-nu tau, (Kpipi)-nu tau and (Kpipipi) -nu tau…
A search for the lepton-flavor-violating decay of the tau into three charged leptons has been performed using $91.5 \mathrm{fb}^{-1}$ of data collected at an $e^+e^-$ center-of-mass energy of 10.58 GeV with the BaBar detector at the PEP-II…
We report on the recent results of searches for lepton-flavor-violating tau decays as well as lepton-number-violating B decays with the world-highest data samples accumulated at the Belle.
Semileptonic decays of $B$ mesons to the tau lepton, despite of experimental difficulties, are of great importance. In particular they are sensitive probes of models with extended Higgs sectors. The results of studies of semitauonic B…
We present the first observation of tau lepton decays to hadronic final states with a phi-meson. This analysis is based on 401 fb^-1 of data accumulated at the Belle experiment. The branching fraction obtained is B(tau- -> phi K- nu) =…
We have searched for tau lepton decays, tau- -> Lambda-bar pi- and tau- -> Lambda pi-, that simultaneously violate the conservation of the lepton and baryon number using a data sample of 154 fb^{-1} collected with the Belle detector at the…