A distinct peak is observed in the ${\pi }^{\pm }{\psi }^{\prime }$ invariant mass distribution near 4.43 GeV in $B\to K{\pi }^{\pm }{\psi }^{\prime }$ decays. A fit using a Breit-Wigner resonance shape yields a peak mass and width of $M=4433\pm 4(\mathrm{stat})\pm 2(\mathrm{syst})\mathrm{MeV}$ and $\Gamma ={45}_{-13}^{+18}(\mathrm{stat}{)}_{-13}^{+30}(\mathrm{syst})\mathrm{MeV}$. The product branching fraction is determined to be $\mathcal{B}\mathbf{(}{B}^0\to K^{\mp }{Z}^{\pm }(4430)\mathbf{)}\times \mathcal{B}\mathbf{(}{Z}^{\pm }(4430)\to {\pi }^{\pm }{\psi }^{\prime }\mathbf{)}=(4.1\pm 1.0(\mathrm{stat})\pm 1.4(\mathrm{syst}))\times {10}^{-5}$, where $Z^{\pm }(4430)$ is used to denote the observed structure. The statistical significance of the observed peak is $6.5\sigma$. These results are obtained from a $605{\mathrm{fb}}^{-1}$ data sample that contains $657\times {10}^6$ $B\overline{B}$ pairs collected near the ${\rm Y}(4S)$ resonance with the Belle detector at the KEKB asymmetric energy $e^{+}{e}^{-}$ collider.

With the full data sample of $772\times {10}^{6}B\overline{B}$ pairs recorded by the Belle detector at the KEKB electron-positron collider, the decay $\overline{B}\to D^{*}{\tau }^{-}{\overline{\nu }}_{\tau }$ is studied with the hadronic $\tau$ decays ${\tau }^{-}\to {\pi }^{-}{\nu }_{\tau }$ and ${\tau }^{-}\to {\rho }^{-}{\nu }_{\tau }$. The $\tau$ polarization $P_{\tau }(D^{*})$ in two-body hadronic $\tau$ decays is measured, as well as the ratio of the branching fractions $R(D^{*})=\mathcal{B}(\overline{B}\to D^{*}{\tau }^{-}{\overline{\nu }}_{\tau })/\mathcal{B}(\overline{B}\to D^{*}{\ell }^{-}{\overline{\nu }}_{\ell })$, where ${\ell }^{-}$ denotes an electron or a muon. Our results, $P_{\tau }(D^{*})=-0.38\pm 0.51{(\text{stat})}_{-0.16}^{+0.21}(\text{syst})$ and $R(D^{*})=0.270\pm 0.035{(\text{stat})}_{-0.025}^{+0.028}(\text{syst})$, are consistent with the theoretical predictions of the standard model. The polarization values of $P_{\tau }(D^{*})>+0.5$ are excluded at the 90% confidence level.

We search for the rare decay $B^{+}\to K^{+}\nu \overline{\nu }$ in a $362{\mathrm{fb}}^{-1}$ sample of electron-positron collisions at the $\mathrm{\Upsilon }(4S)$ resonance collected with the Belle II detector at the SuperKEKB collider. We use the inclusive properties of the accompanying $B$ meson in $\mathrm{\Upsilon }(4S)\to B\overline{B}$ events to suppress background from other decays of the signal $B$ candidate and light-quark pair production. We validate the measurement with an auxiliary analysis based on a conventional hadronic reconstruction of the accompanying $B$ meson. For background suppression, we exploit distinct signal features using machine learning methods tuned with simulated data. The signal-reconstruction efficiency and background suppression are validated through various control channels. The branching fraction is extracted in a maximum likelihood fit. Our inclusive and hadronic analyses yield consistent results for the $B^{+}\to K^{+}\nu \overline{\nu }$ branching fraction of $[2.7\pm 0.5(\mathrm{stat})\pm 0.5(\mathrm{syst})]\times {10}^{-5}$ and $[{1.1}_{-0.8}^{+0.9}(\mathrm{stat}{)}_{-0.5}^{+0.8}(\mathrm{syst})]\times {10}^{-5}$, respectively. Combining the results, we determine the branching fraction of the decay $B^{+}\to K^{+}\nu \overline{\nu }$ to be $[2.3\pm 0.5(\mathrm{stat}{)}_{-0.4}^{+0.5}(\mathrm{syst})]\times {10}^{-5}$, providing the first evidence for this decay at 3.5 standard deviations. The combined result is 2.7 standard deviations above the standard model expectation.

Using data recorded with the Belle detector, we observe a new excited hyperon, an ${\mathrm{\Omega }}^{*-}$ candidate decaying into ${\mathrm{\Xi }}^0{K}^{-}$ and ${\mathrm{\Xi }}^{-}{K}_S^0$ with a mass of $2012.4\pm 0.7(\text{stat})\pm 0.6(\text{syst})\mathrm{MeV}/c^2$ and a width of $\mathrm{\Gamma }=6.4_{-2.0}^{+2.5}(\mathrm{stat})\pm 1.6(\mathrm{syst})\mathrm{MeV}$. The ${\mathrm{\Omega }}^{*-}$ is seen primarily in $\mathrm{\Upsilon }(1S),\mathrm{\Upsilon }(2S)$, and $\mathrm{\Upsilon }(3S)$ decays.

We present a measurement of the differential shapes of exclusive $B\to D^{*}\ell {\overline{\nu }}_{\ell }$ ($B=B^{-},{\overline{B}}^0$ and $\ell =e$, $\mu$) decays with hadronic tag-side reconstruction for the full $711{\mathrm{fb}}^{-1}$ Belle dataset. We extract the Caprini-Lellouch-Neubert (CLN) and Boyd-Grinstein-Lebed (BGL) form factor parameters and use an external input for the absolute branching fractions to determine the Cabibbo-Kobayashi-Maskawa matrix element and find $|V_{cb}{|}_{\mathrm{CLN}}=(40.2\pm 0.9)\times {10}^{-3}$ and $|V_{cb}{|}_{\mathrm{BGL}}=(40.7\pm 1.0)\times {10}^{-3}$ with the zero-recoil lattice QCD point $\mathcal{F}(1)=0.906\pm 0.013$. We also perform a study of the impact of beyond zero-recoil lattice QCD calculations on the $|V_{cb}|$ determinations. Additionally, we present the lepton-flavor universality ratio $R_{e\mu }=\mathcal{B}(B\to D^{*}e{\overline{\nu }}_e)/\mathcal{B}(B\to D^{*}\mu {\overline{\nu }}_{\mu })=0.993\pm 0.023\pm 0.023$, the electron and muon forward-backward asymmetry and their difference $\mathrm{\Delta }{A}_{FB}=0.028\pm 0.028\pm 0.008$, and the electron and muon $D^{*}$ longitudinal polarization fraction and their difference $\mathrm{\Delta }{F}_L^{D^{*}}=0.030\pm 0.025\pm 0.007$. The uncertainties quoted correspond to the statistical and systematic uncertainties, respectively.

We report a new measurement of thee⁺e⁻→ϒ(nS)π⁺π⁻(n= 1,2,3) cross sections at energies from 10.52 to 11.02 GeV using data collected with the Belle detector at the KEKB asymmetric-energye⁺e⁻collider. We observe a new structure in the energy dependence of the cross sections; if described by a Breit-Wigner function its mass and width are found to be $$ M=\left(10752.7\pm {5.9}_{-1.1}^{+0.7}\right)\mathrm{MeV}/{c}^2 $$M=10752.7±5.9−1.1+0.7MeV/c2 and $$ \Gamma =\left({35.5}_{-11.3\kern0.5em -3.3}^{+17.6+3.9}\right) $$Γ=35.5−11.3−3.3+17.6+3.9 MeV, where the first error is statistical and the second is systematic. The global significance of the new structure including systematic uncertainty is 5.2 standard deviations. We also find evidence for thee⁺e⁻→ϒ (1S)π⁺π⁻process at the energy 10.52 GeV, which is below theB $$ \overline{B} $$B¯ threshold.