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A<sc>bstract</sc> Using the data samples of 102 million Υ(1S) and 158 million Υ(2S) events collected by the Belle detector, we search for a pentaquark state in thepJ/ψfinal state from Υ(1,2S) inclusive decays. Here, the charge-conjugate$$\overline{p }J/\psi $$is included. We observe clearpJ/ψproduction in Υ(1,2S) decays and measure the branching fractions to be$$\mathcal{B}[\Upsilon (1S)\to pJ/\psi +anything]=[8.1\pm 0.6(stat.)\pm 0.5(syst.)]\times {10}^{-5}$$and$$\mathcal{B}[\Upsilon (2S)\to pJ/\psi +anything]=[4.3\pm 0.5(stat.)\pm 0.4(syst.)]\times {10}^{-5}$$. We also measure the cross section of inclusivepJ/ψproduction ine⁺e⁻annihilation to beσ(e⁺e⁻→pJ/ψ+anything) = [108 ± 11(stat.) ± 6(syst.)] fb at$$\sqrt{s}=10.52$$GeV using an 89.5 fb⁻¹continuum data sample. There is no significantP_c(4312)⁺,P_c(4440)⁺orP_c(4457)⁺signal found in thepJ/ψfinal states in Υ(1,2S) inclusive decays. We determine the upper limits of$$\mathcal{B}\left[\Upsilon \left({1},{2}S\right)\to {P}_{c}^{+}+anything\right]\cdot \mathcal{B}\left({P}_{c}^{+}\to pJ/\psi \right)$$to be at the 10⁻⁶level. 

We perform an angular analysis of the $B\to K^{*}{e}^{+}{e}^{-}$ decay for the dielectron mass squared, $q^2$ , range of $0.0008–1.1200{\mathrm{GeV}}^2/c^4$ using the full Belle dataset in the $K^{*0}\to K^{+}{\pi }^{-}$ and $K^{*+}\to K_S^0{\pi }^{+}$ channels, incorporating new methods of electron identification to improve the statistical power of the dataset. This analysis is sensitive to contributions from right-handed currents from physics beyond the Standard Model by constraining the Wilson coefficients ${\mathcal{C}}_7^{(\prime )}$ . We perform a fit to the $B\to K^{*}{e}^{+}{e}^{-}$ differential decay rate and measure the imaginary component of the transversality amplitude to be $A_T^{\mathrm{Im}}=-1.27\pm 0.52\pm 0.12$ , and the $K^{*}$ transverse asymmetry to be $A_T^{\left(2\right)}=0.52\pm 0.53\pm 0.11$ , with $F_L$ and $A_T^{\mathrm{Re}}$ fixed to the Standard Model values. The resulting constraints on the value of ${\mathcal{C}}_7^{\prime }$ are consistent with the Standard Model within a $2\sigma$ confidence interval. Published by the American Physical Society2024 

We measure the complete set of angular coefficients $J_i$ for exclusive $\overline{B}\to D^{*}\ell {\overline{\nu }}_{\ell }$ decays ( $\ell =e$ , $\mu$ ). Our analysis uses the full $711{\mathrm{fb}}^{-1}$ Belle dataset with hadronic tag-side reconstruction. The results allow us to extract the form factors describing the $\overline{B}\to D^{*}$ transition and the Cabibbo-Kobayashi-Maskawa matrix element $\left|V_{\mathrm{cb}}\right|$ . Using recent lattice QCD calculations for the hadronic form factors, we find $\left|V_{\mathrm{cb}}\right|=(40.7\pm 0.7)\times {10}^{-3}$ using the Boyd-Grinstein-Lebed parametrization, compatible with determinations from inclusive semileptonic decays. We search for lepton flavor universality violation as a function of the hadronic recoil parameter $w$ and investigate the differences of the electron and muon angular distributions. We find no deviation from standard model expectations. Published by the American Physical Society2024 

We report the results of the first search for $B^{-}$ decays to the ${\overline{\mathrm{\Xi }}}_c^0{\overline{\mathrm{\Lambda }}}_c^{-}$ final state using $711{\mathrm{fb}}^{-1}$ of data collected at the $\mathrm{\Upsilon }\left(4S\right)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. The results are interpreted in terms of both direct baryon-number-violating $B^{-}$ decay and ${\mathrm{\Xi }}_c^0-{\overline{\mathrm{\Xi }}}_c^0$ oscillations which follow the standard model decay $B^{-}\to {\mathrm{\Xi }}_c^0{\overline{\mathrm{\Lambda }}}_c^{-}$ . We observe no evidence for baryon number violation and set the 95% confidence-level upper limits on the ratio of baryon-number-violating and standard model branching fractions $\mathcal{B}(B^{-}\to {\overline{\mathrm{\Xi }}}_c^0{\overline{\mathrm{\Lambda }}}_c^{-})/\mathcal{B}(B^{-}\to {\mathrm{\Xi }}_c^0{\overline{\mathrm{\Lambda }}}_c^{-})$ to be $<2.7\%$ and on the effective angular frequency of mixing $\omega$ in ${\mathrm{\Xi }}_c^0-{\overline{\mathrm{\Xi }}}_c^0$ oscillations to be $<0.76{\mathrm{ps}}^{-1}$ (equivalent to ${\tau }_{\mathrm{mix}}>1.3\mathrm{ps}$ ). Published by the American Physical Society2024 

We present a comprehensive study of $B^0\to \omega \omega$ decays using $772\times {10}^{6}B\overline{B}$ pairs collected with the Belle detector at the KEKB $e^{+}{e}^{-}$ collider. This process is a suppressed charmless decay into two vector mesons and can exhibit interesting polarization and $CP$ violation. The decay is observed for the first time with a significance of 7.9 standard deviations. We measure a branching fraction $\mathcal{B}=(1.53\pm 0.29\pm 0.17)\times {10}^{-6}$ , a fraction of longitudinal polarization $f_L=0.87\pm 0.13\pm 0.13$ , and a time-integrated $CP$ asymmetry $A_{CP}=-0.44\pm 0.43\pm 0.11$ , where the first uncertainties listed are statistical and the second are systematic. This is the first observation of $B^0\to \omega \omega$ and the first measurements of $f_L$ and $A_{CP}$ for this decay. Published by the American Physical Society2024 

A<sc>bstract</sc> We report a search for the charged-lepton flavor violation in Υ(2S) →ℓ^∓τ^±(ℓ=e, μ) decays using a 25 fb⁻¹Υ(2S) sample collected by the Belle detector at the KEKBe⁺e⁻asymmetric-energy collider. We find no evidence for a signal and set upper limits on the branching fractions ($$ \mathcal{B} $$ $B$ ) at 90% confidence level. We obtain the most stringent upper limits:$$ \mathcal{B} $$ $B$ (Υ(2S)→ μ^∓τ^±)<0.23×10⁻⁶and$$ \mathcal{B} $$ $B$ (Υ(2S)→ e^∓τ^±)<1.12×10⁻⁶. 

A<sc>bstract</sc> We report measurements of the absolute branching fractions$$\mathcal{B}\left({B}_{s}^{0}\to {D}_{s}^{\pm }X\right)$$,$$\mathcal{B}\left({B}_{s}^{0}\to {D}^{0}/{\overline{D} }^{0}X\right)$$, and$$\mathcal{B}\left({B}_{s}^{0}\to {D}^{\pm }X\right)$$, where the latter is measured for the first time. The results are based on a 121.4 fb⁻¹data sample collected at the Υ(10860) resonance by the Belle detector at the KEKB asymmetric-energye⁺e⁻collider. We reconstruct one$${B}_{s}^{0}$$meson in$${e}^{+}{e}^{-}\to \Upsilon\left(10860\right)\to {B}_{s}^{*}{\overline{B} }_{s}^{*}$$events and measure yields of$${D}_{s}^{+}$$,D⁰, andD⁺mesons in the rest of the event. We obtain$$\mathcal{B}\left({B}_{s}^{0}\to {D}_{s}^{\pm }X\right)=\left(68.6\pm 7.2\pm 4.0\right)\%$$,$$\mathcal{B}\left({B}_{s}^{0}\to {D}^{0}/{\overline{D} }^{0}X\right)=\left(21.5\pm 6.1\pm 1.8\right)\%$$, and$$\mathcal{B}\left({B}_{s}^{0}\to {D}^{\pm }X\right)=\left(12.6\pm 4.6\pm 1.3\right)\%$$, where the first uncertainty is statistical and the second is systematic. Averaging with previous Belle measurements gives$$\mathcal{B}\left({B}_{s}^{0}\to {D}_{s}^{\pm }X\right)=\left(63.4\pm 4.5\pm 2.2\right)\%$$and$$\mathcal{B}\left({B}_{s}^{0}\to {D}^{0}/{\overline{D} }^{0}X\right)=\left(23.9\pm 4.1\pm 1.8\right)\%$$. For the$${B}_{s}^{0}$$production fraction at the Υ(10860), we find$${f}_{s}=\left({21.4}_{-1.7}^{+1.5}\right)\%$$. 

We report measurements of time-dependent $CP$ asymmetries in $B^0\to K_S^0{\pi }^0\gamma$ decays based on a data sample of $(388\pm 6)\times {10}^{6}B\overline{B}$ events collected at the $\mathrm{\Upsilon }\left(4S\right)$ resonance with the Belle II detector. The Belle II experiment operates at the SuperKEKB asymmetric-energy $e^{+}{e}^{-}$ collider. We measure decay-time distributions to determine $CP$ -violating parameters $S$ and $C$ . We determine these parameters for two ranges of $K_S^0{\pi }^0$ invariant mass: $m\left(K_S^0{\pi }^0\right)\in (0.8,1.0)\mathrm{GeV}/c^2$ , which is dominated by $B^0\to K^{*0}(\to K_S^0{\pi }^0)\gamma$ decays, and a complementary region $m\left(K_S^0{\pi }^0\right)\in (0.6,0.8)\cup (1.0,1.8)\mathrm{GeV}/c^2$ . Our results have improved precision as compared to previous measurements and are consistent with theory predictions. Published by the American Physical Society2025