Measurement of D0-D0 mixing and search for CP violation in D0→K+K-,π+π- decays with the full Belle data set

We report an improved measurement of D0 – D‾0 mixing and a search for CP violation in D0 decays to CP -even final states K+K− and π+π− . The measurement is based on the final Belle data sample of 976 fb −1 . The results are yCP=(1.11±0.22±0.09)% and AΓ=(−0.03±0.20±0.07)% , where the first uncertainty is statistical and the second is systematic

Evidence for Bˉs0→Λc+Λˉπ−\it{\bar{B}_s^{0}} \to \Lambda_c^{+} \bar{\Lambda} \pi^{-}

Using 121.4 fb^{-1} of data collected with the Belle detector at the Y(5S) resonance at the KEKB asymmetric-energy e^+e^- collider, we report evidence for the B_s^0 -> Lambda_c^+ Lambda-bar pi^- decay mode with a measured branching fraction (3.6 +- 1.1[stat.] {+0.3 -0.5}[syst.] +- 0.9[Lambda_c^+] +- 0.7[N_{Bs}]) * 10^{-4} and a significance of 4.4 standard deviations. This is the first evidence for a baryonic B_s^0 decay

Measurements of branching fractions and direct CP-violating asymmetries in B+→K+π0B^+ \to K^+ \pi^0 and π+π0\pi^+ \pi^0 decays using 2019 and 2020 Belle II data

We report measurements of branching fractions ($\mathcal B$) and direct ${\it CP}$-violating asymmetries ($\mathcal A_{\it CP}$) for the decays $B^+\to K^+\pi^0$ and $B^+ \to \pi^+\pi^0$ reconstructed with the Belle II detector in a sample of asymmetric-energy electron-positron collisions at the $\Upsilon(4S)$ resonance corresponding to 62.8 $\text{fb}^{-1}$ of integrated luminosity. The results are $\mathcal{B}(B^+ \to K^+\pi^0) = [11.9 ^{+1.1}_{-1.0} (\rm stat)\pm 1.6(\rm syst)]\times 10^{-6}$, $\mathcal{B}(B^+ \to \pi^+\pi^0) = [5.5 ^{+1.0}_{-0.9} (\rm stat)\pm 0.7(\rm syst)]\times 10^{-6}$, $\mathcal A_{\it CP}(B^+ \to K^+\pi^0) = -0.09 \pm 0.09 (\rm stat)\pm 0.03(\rm syst)$, and $\mathcal A_{\it CP}(B^+ \to \pi^+\pi^0) = -0.04 \pm 0.17 (\rm stat)\pm 0.06(\rm syst)$. The results are consistent with previous measurements and show a detector performance comparable with early Belle performance

τ\tau lepton mass measurement at Belle II

The reconstruction of tau-pair production, $e^{+}e^{-} \to \tau^{+}\tau^{-}$, from the subsequent 3-prong ($\tau^{+} \rightarrow \pi^{+} \pi^{-} \pi^{+} \bar{\nu}_{\tau}$) and 1-prong ($\tau^{-} \to \ell^{-} \bar{\nu}_{\ell} \nu_{\tau}$, $\tau^{-} \to h^{-} \nu_{\tau}$ or $\tau^{-} \to \pi^{-} \pi^0 \nu_{\tau}$) decays, is presented using 8.8 fb$^{-1}$ of $e^{+}e^{-}$ collision data of Belle II at the center-of-mass energy $\sqrt{s} = m_{\Upsilon(4S)}$. The pseudomass technique developed by the ARGUS experiment is used to measure the $\tau$-lepton mass $m_{\tau}$ in the 3-prong $\tau^{+} \to \pi^{+} \pi^{-} \pi^{+} \bar{\nu}_{\tau}$ decay, resulting in $m_{\tau} = 1777.28 \pm 0.75~{\rm (stat.)} \pm 0.33 ~{\rm (sys.)}~{\rm{MeV}/\rm{c}^2}$

Energy scan of the e+e−→hb(nP)π+π−e^+e^- \to h_b(nP)\pi^+\pi^- (n=1,2)(n=1,2) cross sections and evidence for the Υ(11020)\Upsilon(11020) decays into charged bottomonium-like states

Using data collected with the Belle detector in the energy region of the $\Upsilon(10860)$ and $\Upsilon(11020)$ resonances we measure the $e^+e^- \to h_b(nP)\pi^+\pi^-$ $(n=1,2)$ cross sections. Their energy dependences show clear $\Upsilon(10860)$ and $\Upsilon(11020)$ peaks with a small or no non-resonant contribution. We study resonant structure of the $\Upsilon(11020) \to h_b(nP)\pi^+\pi^-$ transitions and find evidence that they proceed entirely via intermediate charged bottomonium-like states $Z_b(10610)$ and/or $Z_b(10650)$ (with current statistics we can not discriminate hypotheses of one or two intermediate states).Using data collected with the Belle detector at the KEKB asymmetric-energy e+e- collider, we measure the energy dependence of the e+e-→hb(nP)π+π- (n=1, 2) cross sections from thresholds up to 11.02 GeV. We find clear ϒ(10860) and ϒ(11020) peaks with little or no continuum contribution. We study the resonant substructure of the ϒ(11020)→hb(nP)π+π- transitions and find evidence that they proceed entirely via the intermediate isovector states Zb(10610) and Zb(10650). The relative fraction of these states is loosely constrained by the current data: The hypothesis that only Zb(10610) is produced is excluded at the level of 3.3 standard deviations, while the hypothesis that only Zb(10650) is produced is not excluded at a significant level.Using data collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider, we measure the energy dependence of the $e^+e^- \to h_b(nP)\pi^+\pi^-$ $(n=1,2)$ cross sections from thresholds up to $11.02\,$GeV. We find clear $\Upsilon(10860)$ and $\Upsilon(11020)$ peaks with little or no continuum contribution. We study the resonant substructure of the $\Upsilon(11020) \to h_b(nP)\pi^+\pi^-$ transitions and find evidence that they proceed entirely via the intermediate isovector states $Z_b(10610)$ and $Z_b(10650)$. The relative fraction of these states is loosely constrained by the current data: the hypothesis that only $Z_b(10610)$ is produced is excluded at the level of 3.3 standard deviations, while the hypothesis that only $Z_b(10650)$ is produced is not excluded at a significant level

Measurements of branching fraction and CPCP asymmetry of the Bˉ0(B0)→KS0K∓π±\bar{B}^{0}(B^{0})\to K^{0}_{S}K^{\mp}\pi^{\pm} decay at Belle

International audienceWe report the measurement of the branching fraction and $CP$ asymmetry for the $\bar{B}^{0}(B^{0})\to K^{0}_{S}K^{\mp}\pi^{\pm}$ decay. The analysis is performed on a data sample of 711 $\rm{fb}^{-1}$ collected at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}e^{-}$ collider. We obtain a branching fraction of $(3.60\pm0.33\pm0.15)\times10^{-6}$ and an $\mathcal{A}_{CP}$ of $(-8.5\pm8.9\pm0.2)\%$, where the first uncertainties are statistical and the second are systematic. Hints of peaking structures are also observed in the differential branching fraction as functions of Dalitz variables

Measurement of the BB−^{-} →\rightarrow DD0^{0}ℓ\ell−^{-}νˉ\bar{\nu}ℓ_{\ell} Branching Fraction in 62.8 fb−1^{-1} of Belle II data

We report a measurement of the branching fraction of the semileptonic decay $B$$^{-}$ $\rightarrow$ $D$$^{0}$$\ell$$^{-}$$\bar{\nu}$$_{\ell}$ (and its charge conjugate) using 62.8 fb$^{-1}$ of $\Upsilon$(4$S$) $\rightarrow$ $B$$\bar{B}$ data recorded by the Belle II experiment at the SuperKEKB asymmetric-energy $e$$^{+}$ $e$$^{-}$ collider. The neutral charm meson is searched for in the decay mode $D$$^{0}$ $\rightarrow$ $K$$^{-}$ $\pi$$^{+}$ and combined with a properly charged identified lepton (electron or muon) to reconstruct this decay. No reconstruction of the second $B$ meson in the $\Upsilon$(4$S$) event is performed. We obtain $B$($D$$^{0}$$\ell$$^{-}$$\bar{\nu}$$_{\ell}$) = (2.29 $\pm$ 0.05 $_{stat}$ $\pm$ 0.08$_{syst}$, in agreement with the world average of this decay. We also determine the ratio of the electron to muon branching fractions to be $R$($e$/$\mu$) = 1.04 $\pm$ 0.05$_{stat}$ $\pm$ 0.03$_{syst}$ and observe no deviation from lepton universality

Measurement of the BB−^{-} →\rightarrow DD0^{0}ℓ\ell−^{-}νˉ\bar{\nu}ℓ_{\ell} Branching Fraction in 62.8 fb−1^{-1} of Belle II data

We report a measurement of the branching fraction of the semileptonic decay $B$$^{-}$ $\rightarrow$ $D$$^{0}$$\ell$$^{-}$$\bar{\nu}$$_{\ell}$ (and its charge conjugate) using 62.8 fb$^{-1}$ of $\Upsilon$(4$S$) $\rightarrow$ $B$$\bar{B}$ data recorded by the Belle II experiment at the SuperKEKB asymmetric-energy $e$$^{+}$ $e$$^{-}$ collider. The neutral charm meson is searched for in the decay mode $D$$^{0}$ $\rightarrow$ $K$$^{-}$ $\pi$$^{+}$ and combined with a properly charged identified lepton (electron or muon) to reconstruct this decay. No reconstruction of the second $B$ meson in the $\Upsilon$(4$S$) event is performed. We obtain $B$($D$$^{0}$$\ell$$^{-}$$\bar{\nu}$$_{\ell}$) = (2.29 $\pm$ 0.05 $_{stat}$ $\pm$ 0.08$_{syst}$, in agreement with the world average of this decay. We also determine the ratio of the electron to muon branching fractions to be $R$($e$/$\mu$) = 1.04 $\pm$ 0.05$_{stat}$ $\pm$ 0.03$_{syst}$ and observe no deviation from lepton universality