Related papers: Study of Lepton Universality at Belle
The Belle experiment at the KEKB asymmetric energy e+e- collider recorded large data sets of both, B and Bs decays. Semileptonic decays B(s) -> X l nu (l = electron or muon) constitute approximately one fifth of the total decay width of…
Several measurements of tree- and loop-level b-hadron decays performed in the recent years hint at a possible violation of Lepton Universality. This article presents an experimental and theoretical overview of the current status of the…
This report introduces two recent measurements of semileptonic $b$-hadron decays at the LHCb experiment, including a test of Lepton Flavour Universality (LFU) using $\bar{B}^0 \to D^{(*)+} l^- \bar{\nu}_l$ decays where $l\in\{\mu,\tau\}$,…
This proceeding summarises recent studies on semileptonic and leptonic $B$ decays, which provide stringent tests of lepton flavour universality as well as key experimental inputs to ultimately increase the precision of inclusive $|V_{ub}|$…
We report on recent results obtained by the Belle II experiment related to searches for beyond-the-standard-model physics. The $B$ meson decay data sample used corresponds to an integrated luminosity of $L = 189$ fb$^{-1}$. In recent years,…
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 study the flavor universality of the lepton couplings with the W and Z bosons. Currently, it is constrained by the electroweak precision observables. We focus on the leptonic decay of the pion. It is shown that the decay is expected to…
We present an overview of searches fo violation of lepton flavor universality with focus on low energy precision probes using pions, kaons, tau leptons, and nuclear beta decays. The current experimental results are reviewed, the theoretical…
We have searched for neutrinoless $\tau$ lepton decays into $\ell$ and $V^0$, where $\ell$ stands for an electron or muon, and $V^0$ for a vector meson ($\phi$, $\omega$, $K^{*0}$ or $\bar{K}^{*0}$), using 543 fb$^{-1}$ of data collected…
The Standard Model (SM) is lepton flavor universal, and the recent measurements of lepton flavor universality in $B \to (K,K^*)\ell^{+}\ell^{-}$, for $\ell = \mu, \; e$, decays now lie close to the SM predictions. However, this is not the…
We report on the measurement of the decay $B\to K^{\star}\gamma$, lepton-flavor dependent angular analysis of the decay $B\to K^{\star}\ell\ell$, and search for the decays $B\to h\nu\nu$. All these analyses are performed on the 711…
Some important aspects of hadronic tau decays are reviewed: the determination of alpha_s from the inclusive tau hadronic width, the measurement of |V_{us}| through the Cabibbo-suppressed decays of the tau, and the theoretical description of…
Results are presented from the CLEO, BaBar and Belle collaborations on searches for lepton-number-violating B decays.
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.
We report the result for a search for the leptonic decay of $B^+ \to \mu^+ \, \nu_{\mu}$ using the full Belle data set of 711 fb${}^{-1}$ of integrated luminosity at the $\Upsilon(4S)$ resonance. In the Standard Model leptonic $B$-meson…
We update our search for the lepton flavor violating tau -> mu gamma and tau -> e gamma decays based on 535/fb of data accumulated at the Belle experiment. No signal is found and we set preliminary 90% confidence level upper limits: B(tau…
We report on a search for the lepton flavor violating tau- -> mu- gamma and tau- -> e- gamma decays based on 535/fb of data accumulated at the Belle experiment. No signal is found and we set 90% confidence level upper limits on the…
Recent BABAR and Belle results on rare B decays involving photons or lepton pairs are reviewed. New preliminary limits from both experiments for B-->rho gamma and B-->omega gamma, and from BABAR for B --> K nu nu and B --> tau nu are…
We revisit the experimental and theoretical status of $B \to \rho l \bar{\nu}$ and $B \to \omega l \bar{\nu}$ decays. We perform a combined fit of averaged spectra from Belle and Babar measurements with prior light cone sum rule…
We report the measurements of the leptonic decays B->lnu obtained at the Belle experiment. The results are consistent with the Standard Model expectations, and provide stringent constraints on new physics models including charged Higgs…