Related papers: Towards the (Mexican) discovery of second class cu…

Observation of $\tau^-\to\eta^{(\prime)}\pi^-\nu_\tau $ decays at Belle-II would indicate either a manifestation of isospin symmetry breaking or genuine second class currents (SCC) effects. The corresponding radiative…

We analyze the second-class current decays $\tau^{-}\to\pi^{-}\eta^{(\prime)}\nu_{\tau}$ in the framework of Chiral Perturbation Theory with resonances. Taking into account $\pi^{0}$-$\eta$-$\eta^{\prime}$ mixing, the…

We consider the ``second-class current'' decay $\tau^-\to\pi^-\eta\nu_\tau$ from several points of view. We first focus on the decay rate as expected within standard weak interaction and QCD due to isospin violation. The decay contributions…

This note describes the rediscovery of $B\to\eta' K$ decays in Belle II data, both in the charged and neutral final state: $B_0\to\eta' K_S$ and $B^\pm\to\eta' K^\pm$. The $\eta'$ is searched for in two decay modes: $\eta'\to\eta\pi^+\pi^-$…

We measure the branching fraction of the decay $B^0 \to J/\psi \omega$ using data collected with the Belle II detector at the SuperKEKB collider. The data contain $(387 \pm 6) \times 10^6$ $B\overline{B}$ meson pairs produced in…

We present new precision predictions for semitauonic decays involving $\rho$ and $\omega$ final state mesons. These decay channels offer an interesting orthogonal probe to study the existing B anomalies in semitauonic transitions and are…

The Belle II experiment recently observed the decay $B^+ \to K^+ \nu \nu$ for the first time, with a measured value for the branching ratio of $ (2.3 \pm 0.7) \times 10^{-5}$. This result exhibits a $\sim 3\sigma$ deviation from the…

We report a study of $B \to J/\psi(\ell^{+}\ell^{-})K$ decays, where $\ell$ represents an electron or a muon, using $e^{+}e^{-}$ collisions at the $\Upsilon(4S)$ resonance. The data were collected by the Belle II experiment at the SuperKEKB…

It is experimentally observed that ratios of branching fractions for semitauonic and semileptonic $B$ decays, known as the $R(D^{(*)})$, are higher than Standard Model (SM) predictions. The $B \to \bar{D}^{(*)} \tau^{+} \nu_{\tau}$ decays,…

The decay tau- -> 2pi- pi+ 3pi0 nu_tau has been studied with the CLEO II detector at the Cornell Electron Storage Ring (CESR). The branching fraction is measured to be (2.85 +/- 0.56 +/- 0.51) x 10^(-4). The result is in good agreement with…

An excess in the branching fraction for $B^+ \to K^+ \nu\nu$ recently measured at Belle II may be a hint of new physics. We perform thorough likelihood analyses for different new physics scenarios such as $B \to KX$ with a new invisible…

Belle II measurement of the branching fraction for $B^{+} \to K^{+} \nu \bar{\nu}$ shows a $2.7\sigma$ excess over the Standard Model prediction and motivates new-physics explanations such as axion-like particles, Higgs-like scalars, or…

We report measurements of the branching fractions and direct $\it{CP}$ asymmetries of the decays $B^0 \to K^+ \pi^-$, $B^+ \to K^+ \pi^0$, $B^+ \to K^0 \pi^+$, and $B^0 \to K^0 \pi^0$, and use these for testing the standard model through an…

We measure the branching fractions for the decays $\bar{B}^0 \to D^{*+} e^{-} \bar{\nu}_e$ and $\bar{B}^0 \to D^{*+} \mu^{-} \bar{\nu}_\mu$ using $8.70 \pm 0.09~{\rm fb}^{-1}$ of data collected by the Belle II experiment at the SuperKEKB…

We present an assessment of the standard model expectations for the branching ratio of the isotopic spin and G-parity violating decay tau --> eta' pi nu_tau. The estimate is based on a vector and scalar meson dominance parametrization of…

We present a feasibility study to probe quantum entanglement and Belle inequality violation in the process $\textrm{e}^{+}\textrm{e}^{-} \rightarrow \tau^{+}\tau^{-}$ at a center-of-mass energy of $\sqrt{s} = 10.579$ GeV. The sensitivity of…

The Belle II experiment at the SuperKEKB energy-asymmetric electron-positron collider is a substantial upgrade of the B factory facility at the Japanese KEK laboratory. Belle II collected a sample of $362~\mathrm{fb}^{-1}$ at the…

We present measurements of the branching fractions of eight $\overline B{}^0\to D^{(*)+} K^- K^{(*)0}_{(S)}$, $B^{-}\to D^{(*)0} K^- K^{(*)0}_{(S)}$ decay channels. The results are based on data from SuperKEKB electron-positron collisions…

Recent experimental results for the ratios of the branching fractions of the decays $\bar{B} \to D^{(*)} \tau \bar\nu$ and $\bar{B} \to D^{(*)} \mu \bar\nu$ came as a surprise and lead to a discussion of possibility of testing New Physics…

The Belle II experiment aims to record 50 ab$^{-1}$ data with the high luminosity to be provided by the SuperKEKB asymmetric-energy electron-positron collider. The anticipated high statistics data enables us to perform studies of $B$ decays…