Related papers: Hadronic $B$ decay reconstruction in early Belle I…

Results on a number of rare hadronic B decays are presented. A data sample of $29.1 {\rm fb}^{-1}$ accumulated using the Belle detector at the KEKB asymmetric $e^+e^-$ collider operating at the $\Upsilon(4S)$ resonance is used.

We present results on the semileptonic decays $B^0 \to \rho^- \ell^+ \nu_\ell$ and $B^+ \to \rho^0 \ell^+ \nu_\ell$ in a sample corresponding to 189.9/fb of Belle II data at the SuperKEKB $e^- e^+$ collider. Signal decays are identified…

We report a search for the rare decay $B^{+} \rightarrow K^{+} \tau^{+} \tau^{-}$ using $1.2 \times 10^9$ $\Upsilon(4S)$ mesons produced near threshold in electron-positron collisions and collected by the Belle and Belle~II experiments. We…

We present a search for the rare flavor-changing neutral-current decay $B^0 \to K^{\ast 0} \tau^+ \tau^-$ with data collected by the Belle II experiment at the SuperKEKB electron-positron collider. The analysis uses a 365 fb$^{-1}$ data…

The Belle II / SuperKEKB experiment is an $e^+e^-$ collider running at the $\Upsilon(4S)$ resonance energy to produce B meson pairs. As an upgrade of the Belle / KEKB experiment, it will start physics data taking from 2018 and with $\sim…

We utilize a sample of 34.6 fb$^{-1}$, collected by the Belle II experiment at the SuperKEKB asymmetric energy $e^+e^-$ collider, to search for the $B^+ \to \phi K^+$, $B^+ \to \phi K^{*+}$, $B^0 \to \phi K^0_S$, and $B^0 \to \phi K^{*0}$…

We present the first evidence of the decay B- --> tau- nu_tau-bar using 414 fb^-1 of data collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. Events are tagged by fully reconstructing…

We report on a Belle II measurement of the branching fraction ($\mathcal{B}$), longitudinal polarization fraction ($f_L$), and CP asymmetry ($\mathcal{A}_{CP}$) of $B^+\to \rho^+\rho^0$ decays. We reconstruct $B^+\to \rho^+(\to…

Neutral-current semileptonic $B$ decays are plagued by hadronic resonances across the dilepton invariant-mass squared spectrum, $q^2$. For light leptons, $\ell=e,\mu$, these resonances can be avoided with suitable $q^2$ cuts. This strategy…

In 2018 the Belle II experiment, aimed at detailed studies of B-mesons, started operation at the electron-positron collider SuperKEKB at KEK (Japan). This was preceded by a long and quite successful work of the B-factories of previous…

The Belle II experiment at the SuperKEKB collider is a major upgrade of the KEK "$B$ factory" facility in Tsukuba, Japan. The machine is designed for an instantaneous luminosity of $8\times 10^{35}$~cm$^{-2}$\,s$^{-1}$, and the experiment…

We report on the first Belle II measurement of the branching fraction ($\mathcal{B}$) and longitudinal polarization fraction ($f_L$) of $B^+\to \rho^+\rho^0$ decays. We reconstruct $B^+\to \rho^+(\to \pi^+\pi^0(\to \gamma\gamma))\rho^0(\to…

Belle II is an upcoming experiment at the next generation SuperKEKB e+e- collider. It will record about 50 ab-1 of data mostly at the Y(4S) resonance. The high statistics will allow precision measurements for rare decays, which can be then…

We present a study of hadronic tau decays, especially decay into three-hadron final states with kaon(s), using more than 500fb^-1 of data collected with the Belle detector at the KEKB asymmetric-energy e+e- collider. We measure the…

We present a reconstruction of the semileptonic decays $B^0 \to \pi^- e^+ \nu_e$ and $B^+ \to \pi^0 e^+ \nu_e$ in a sample corresponding to 189.3 fb$^{-1}$ of Belle II data, using events where the partner $B$-meson is reconstructed from a…

We present the measurements, performed by the Belle II experiment, related to the B and D meson decays. These results are based on 63 fb$^{-1}$ and 9 fb$^{-1}$ of $e^+e^-$ collision data recorded by the Belle II detector at a center-of-mass…

We report a preliminary study of the branching fractions and $q^2$ distributions of exclusive charmless semileptonic B decays, using events tagged by fully reconstructing one of the $B$ mesons in a hadronic decay mode. These results are…

The $b\to s(d)$ quark-level transitions are flavor-changing neutral current processes, which are not allowed at tree level in the standard model. These processes are very rare and constitute a potential probe for new physics. Belle II at…

Belle II is a major upgrade of the Belle experiment and operates at the $B$-factory SuperKEKB in Japan. Since the SuperKEKB collider has a design luminosity of 8$\;\times\;$10$^{35}$ cm$^{-2}$s$^{-1}$, about 40 times larger than that of…

We report a search for lepton-flavor-violating decays $\tau^- \to \ell^- \phi$ ($\ell^- =e^-,\mu^-$) at the Belle II experiment, using a sample of electron-positron data produced at the SuperKEKB collider in 2019-2021 and corresponding to…