We report a search for the charmless hadronic decay $B^0toeta pi^0$ with a data sample corresponding to an integrated luminosity of 694 $rm fb^{-1}$ containing $753times10^6$ $Bbar{B}$ pairs. The data were collected by the Belle experiment running on the $Upsilon(4S)$ resonance at the KEKB $e^+e^-$ collider. We measure a branching fraction $mathcal{B}(B^0toetapi^0)=(4.1^{+1.7+0.5}_{-1.5-0.7})times 10^{-7}$, where the first uncertainty is statistical and the second is systematic. Our measurement gives an upper limit of $mathcal{B}(B^0toetapi^0)<6.5times 10^{-7}$ at 90% confidence level. The signal has a significance of $3.0$ standard deviations and constitutes the first evidence for this decay mode.
We report a search for $B^{0}to eta eta $ with a data sample corresponding to an integrated luminosity of $698 ,{rm fb}^{-1}$ containing $753 times 10^{6}$ $Bbar{B}$ pairs collected at the $Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}e^{-}$ collider. The branching fraction is measured to be $mathcal{B}(B^{0} to eta eta ) = (7.6^{+2.7 +1.4}_{-2.3 -1.6}) times 10^{-7}$ at the level of 3.3 standard deviations above zero, which provides the first evidence for the decay $B^{0} to eta eta$.
An experimental study of the $etato pi^0pi^0eta to 6gamma$ decay has been conducted with the best up-to-date statistical accuracy, by measuring $eta$ mesons produced in the $gamma p to eta p$ reaction with the A2 tagged-photon facility at the Mainz Microtron, MAMI. The results obtained for the standard parametrization of the $etato pi^0pi^0eta$ matrix element are consistent with the most recent results for $etatopipieta$ decays, but have smaller uncertainties. The available statistics and experimental resolution allowed, for the first time, an observation of a structure below the $pi^+pi^-$ mass threshold, the magnitude and sign of which, checked within the framework of the nonrelativistic effective-field theory, demonstrated good agreement with the cusp that was predicted based on the $pipi$ scattering length combination, $a_0-a_2$, extracted from $K to 3pi$ decays.
We report a study of the suppressed decay B^- -> DK^-, D -> K^+pi^-pi^0, where D denotes either a D^0 or a bar{D}^0 meson. The decay is sensitive to the CP-violating parameter phi_3. Using a data sample of 772 x 10^6 Bbar{B} pairs collected at the Upsilon(4S) resonance with the Belle detector, we measure the ratio of branching fractions of the above suppressed decay to the favored decay B^- -> DK^-, D -> K^-pi^+pi^0. Our result is R_{DK} = [1.98 +/- 0.62(stat.) +/- 0.24(syst.)] x 10^{-2}, which indicates the first evidence of the signal for this suppressed decay with a significance of 3.2 standard deviations. We measure the direct CP asymmetry between the suppressed B^- and B^+ decays to be A_{DK} = 0.41 +/- 0.30 (stat.) +/- 0.05 (syst.). We also report measurements for the analogous quantities R_{Dpi} and A_{Dpi} for the decay B^- -> Dpi^-, D -> K^+pi^-pi^0.
We report a search for the charmless baryonic decay $B^0to pbar{p}pi^0$ with a data sample corresponding to an integrated luminosity of 711~$rm fb^{-1}$ containing $(772pm 10)times 10^6$ $B^0bar{B}^0$ pairs. The data was collected by the Belle experiment running on the $Upsilon(4S)$ resonance at the KEKB $e^+e^-$ collider. We measure a branching fraction $mathcal{B}(B^0to pbar{p}pi^0)= (5.0pm1.8pm0.6 )times 10^{-7}$, where the first uncertainty is statistical and the second is systematic. The signal has a significance of 3.1 standard deviations and constitutes the first evidence for this decay mode. We also search for the intermediate two-body decays $B^{0}toDelta^+bar{p}$ and $B^0tobar{Delta}^-p$, and set an upper limit on the branching fraction: $mathcal{B}(B^0to Delta^+bar{p})+mathcal{B}(B^0tobar{Delta}^-p)<1.6times10^{-6}$ at 90% confidence level.
We report a search for charmless hadronic decays of neutral B mesons to the final state K+K-pi0. The results are based on a 711 fb^-1 data sample that contains 772x10^6 BB-bar pairs, and was collected at the Y(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. We find the first evidence for this decay with a significance of 3.5 standard deviations and measure its branching fraction as BF(B0 --> K+K-pi0) = [2.17 +/- 0.60(stat) +/- 0.24 (syst)]x10^-6.