We observe evidence for CP violation in the decay \(D^+\rightarrow K^0_S\pi^+\) using a data sample with an integrated luminosity of 977 fb\(^{-1}\) collected by the Belle detector at the KEKB ...\(e^+e^-\) asymmetric-energy collider. The CP asymmetry in the decay is measured to be \((-0.363\pm0.094\pm0.067)%\), which is 3.2 standard deviations away from zero, and is consistent with the expected CP violation due to the neutral kaon in the final state.
We report a search for \(B^{0}\) decays into invisible final states using a data sample of \(657 \times 10^{6}\) \(B\bar{B}\) pairs collected at the \(\Upsilon(4S)\) resonance with the Belle detector ...at the KEKB \(e^{+}e^{-}\) collider. The signal is identified by fully reconstructing a hadronic decay of the accompanying \(B\) meson and requiring no other particles in the event. No significant signal is observed, and we obtain an upper limit of \(1.3 \times 10^{-4}\) at the 90% confidence level for the branching fraction of invisible \(B^{0}\) decay.
Using samples of 102 million \(\Upsilon(1S)\) and 158 million \(\Upsilon(2S)\) events collected with the Belle detector, we study exclusive hadronic decays of these two bottomonium resonances to the ...three-body final states \(\phi K^+ K^-\), \(\omega \pi^+ \pi^-\) and \(K^{\ast 0}(892) K^- \pi^+ \), and to the two-body Vector-Tensor (\(\phi f_2'(1525)\), \(\omega f_2(1270)\), \(\rho a_2(1320)\) and \(K^{\ast 0}(892) \bar{K}_2^{\ast 0}(1430) \)) and Axial-vector-Pseudoscalar (\(K_1(1270)^+ K^-\), \(K_1(1400)^+ K^- \) and \(b_1(1235)^+ \pi^- \)) pairs. Signals are observed for the first time in the \(\Upsilon(1S) \to \phi K^+ K^-\), \(\omega \pi^+ \pi^-\), \(K^{\ast 0} K^- \pi^+\), \(K^{\ast0} K_2^{\ast 0}\) and \(\Upsilon(2S) \to \phi K^+ K^-\), \(K^{\ast 0} K^- \pi^+\) decay modes. Branching fractions are determined for all the processes, while 90% confidence level upper limits are established on the branching fractions for the modes with a statistical significance less than \(3\sigma\). The ratios of the branching fractions of \(\Upsilon(2S)\) and \(\Upsilon(1S)\) decays into the same final state are used to test a perturbative QCD prediction for OZI suppressed bottomonium decays.
We report a study of the decay \(B^0\rightarrow D K^+\pi^-\) followed by \(D\rightarrow K^-\pi^+\), where \(D\) indicates \(D^0\) or \(\bar{D}^0\). We reconstruct the \(D K^+\pi^-\) state in a phase ...space corresponding to \(D K^{*}(892)^0\). The CP-violating angle \(\phi_3\) affects its decay rate via the interference between \(b\rightarrow u\) and \(b\rightarrow c\) transitions. The result is obtained from a 711 \({\rm fb}^{-1}\) data sample that contains 772 \(\times 10^6 B\bar{B}\) pairs collected at the \(\Upsilon(4S)\) resonance with the Belle detector at the KEKB asymmetric-energy \(e^+ e^-\) collider. We measure the ratio \({\cal R}_{DK^{*0}} \equiv \Gamma(B^0\rightarrow K^-\pi^+_DK^+\pi^-)/\Gamma(B^0\rightarrow K^+\pi^-_DK^+\pi^-)\) to be \((4.1 ^{+ 5.6 + 2.8}_{- 5.0 - 1.8}) \times 10^{-2}\), and set an upper limit of \({\cal R}_{DK^{*0}} < 0.16\) at the 95% confidence level.
We report measurements of branching fractions and time-dependent CP asymmetries in \(B^{0} \to D^{+}D^{-}\) and \(B^{0} \to D^{*\pm}D^{\mp}\) decays using a data sample that contains \((772 \pm ...11)\times 10^6 B\bar{B}\) pairs collected at the \(\Upsilon(4S)\) resonance with the Belle detector at the KEKB asymmetric-energy \(e^+ e^-\) collider. We determine the branching fractions to be \(\mathcal{B}(B^{0} \to D^{+}D^{-})=(2.12 \pm 0.16 \pm 0.18)\times 10^{-4}\) and \(\mathcal{B}(B^{0} \to D^{*\pm}D^{\mp}=(6.14 \pm 0.29 \pm 0.50)\times 10^{-4}\). We measure CP asymmetry parameters \(\mathcal{S}_{D^{+}D^{-}} = -1.06_{-0.14}^{+0.21} \pm 0.08\) and \(\mathcal{C}_{D^{+}D^{-}} = -0.43 \pm 0.16 \pm 0.05\) in \(B^{0} \to D^{+}D^{-}\) and \(\mathcal{A}_{D^{*}D} = +0.06 \pm 0.05 \pm 0.02\), \(\mathcal{S}_{D^{*}D} = -0.78 \pm 0.15 \pm 0.05\), \(\mathcal{C}_{D^{*}D} = -0.01 \pm 0.11 \pm 0.04\), \(\Delta\mathcal{S}_{D^{*}D} = -0.13 \pm 0.15 \pm 0.04\) and \(\Delta\mathcal{C}_{D^{*}D} = +0.12 \pm 0.11 \pm 0.03\) in \(B^{0} \to D^{*\pm}D^{\mp}\), where the first uncertainty is statistical and the second is systematic. We exclude the conservation of CP symmetry in both decays at equal to or greater than \(4\sigma\) significance.
We measure the branching fractions of \(B^{0} \to J/\psi \eta^{(}{}'{}^{)}\) decays with the complete Belle data sample of \(772 \times 10^{6}\) \(B\bar{B}\) events collected at the \(\Upsilon(4S)\) ...resonance with the Belle detector at the KEKB asymmetric-energy \(e^+ e^-\) collider. The results for the branching fractions are: \({\cal B}(B^{0} \to J/\psi \eta)=(12.3 \pm ^{1.8}_{1.7} \pm 0.7) \times 10^{-6}\) and \({\cal B}(B^{0} \to J/\psi\eta') < 7.4 \times 10^{-6}\) at 90% confidence level. The \(\eta-\eta'\) mixing angle is constrained to be less than \( 42.2^{\circ}\) at 90% confidence level.
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