Search for the h_c meson in B^+- ->h_c K^+-

We report a search for the $h_c$ meson via the decay chain $B^{\pm}\to h_c K^{\pm}$, \etac \gamma with $\eta_c \to K_S^0 K^{\pm} \pi^{\mp}$ and $p\bar{p}$. No significant signals are observed. We obtain upper limits on the branching fractions for $B^{\pm} \to \eta_c\gamma K^{\pm}$ in bins of the $\eta_c\gamma$ invariant mass. The results are based on an analysis of 253 fb$^{-1}$ of data collected by the Belle detector at the KEKB $e^+e^-$ collider.Comment: 12 pages, 6 figures, submitted to Phys. Rev.

Search for B^0-> p p-bar, Lambda Lambda-bar and B^+ -> p Lambda-bar at Belle

We report on a new search for two-body baryonic decays of the B meson. Improved sensitivity compared to previous Belle results is obtained from 414 fb^-1 of data that corresponds to 449 million B B-bar pairs, which were taken on the Upsilon(4S) resonance and collected with the Belle detector at the KEKB e^+e^- collider. No significant signals are observed and we set the 90% confidence level upper limits: Br(B^0-> p pbar) Lambda Lambda-bar) p Lambda-bar) < 3.2X10^-7.Comment: 5 pages, 2 figures, submitted to PR

Observation of a near-threshold omega-J/psi mass enhancement in exclusive B-->K omega J/psi decays

We report the observation of a near-threshold enhancement in the omega-J/psi invariant mass distribution for exclusive B-->K omega J/psi decays. The results are obtained from a 253 fb-1 data sample that contains 275 million BB-bar meson pairs that were collected near the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric energy e+e- collider. The statistical significance of the omega-J/psi mass enhancement is estimated to be greater than 8 sigma.Comment: 12 pages, 4 figures, submitted to Physical Review Letter

Observation of B0->pi0pi0

We report the first observation of the decay B0->pi0pi0, using a 253/fb data sample collected at the Upsilon(4S) resonance with the Belle detector at the KEKB e+e- collider. The measured branching fraction is BF(B0->pi0pi0) = {2.32 +0.4-0.5(stat) +0.2-0.3(syst)} x 10^-6, with a significance of 5.8 standard deviations including systematic uncertainties. We also make the first measurement of the direct CP violating asymmetry in this mode.Comment: 6 pages, 2 figures, submitted to ICHEP04, Beijing and Physical Review Letters. v2: a possible pile-up background is checked and a systematic error for it is include

Improved measurement of CP-violating parameters in rho+rho- decays

We present a measurement of the CP-violating asymmetry in rho+rho- decays using 535 million BBbar pairs collected with the Belle detector at the KEKB e+e- collider. We measure CP-violating coefficients A = 0.16 +- 0.21(stat) +- 0.07 (syst) and S = 0.19 +- 0.30(stat) +- 0.07 (syst}. These values are used to determine the unitarity triangle angle phi_2 using an isospin analysis; the solution consistent with Standard Model lies in the range 53 < phi_2 < 114 deg. at 90 C.L.Comment: 6 pages, 4 figures, presented at JPS/DPF 2006 (Added KEK, BELLE preprint numbers, submitted to PRD(RC)

Observation of B+ -> proton Lambdabar gamma

We report the first observation of the radiative hyperonic B decay B+ -> proton Lambdabar gamma, using a 140 fb-1 data sample recorded on the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric energy e+e- collider. The measured branching fraction is B(B+ -> proton Lambdabar gamma) = (2.16 ^{+0.58}_{-0.53} +- 0.20) times 10^{-6}. A search for B+ -> proton Sigmabar gamma yields no significant signal, so we set a 90% confidence-level upper limit on the branching fraction of B(B+ -> proton Sigmabar gamma) < 3.3 times 10^{-6}.Comment: 12 pages, 4 figures, submitted to ICHEP2004, Beijing, Chin

Observation of B+->Lambda_c+Lambda_c-K+ and B0->Lambda_c+Lambda_c^-K0 decays

We report first measurements of the doubly charmed baryonic B decays B->Lambda_c+Lambda_c-K. The B+->Lambda_c+Lambda_c-K+ decay is observed with a branching fraction of (6.5+1.0-0.9+-1.1+-3.4)x10^{-4} and a statistical significance of 15.4sigma. The B0->Lambda_c+Lambda_c-K0 decay is observed with a branching fraction of (7.9+2.9-2.3+-1.2+-4.2)x10^{-4} and a statistical significance of 6.6sigma. The branching fraction errors are statistical, systematic, and the error resulting from the uncertainty of Lambda_c+->pK-pi+ decay branching fraction. The analysis is based on 357fb-1 of data accumulated at the Y(4S) resonance with the Belle detector at the KEKB asymmetric e+e- collider.Comment: 10 pages, 3 figure

Search for B+ -> D*+ pi0 decay

We report on a search for the doubly Cabibbo suppressed decay B+ -> D*+ pi0, based on a data sample of 657 million BBbar pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric energy e+ e- collider. We find no significant signal and set an upper limit of Br(B+ -> D*+ pi0) < 3.6 x 10^-6 at the 90% confidence level. This limit can be used to constrain the ratio between suppressed and favored B -> D* pi decay amplitudes, r < 0.051, at the 90% confidence level.Comment: 5pages, 2figures, submitted to PRL (v1); PRL published version (v2: minor corrections in the text

Charge Asymmetry of Same-Sign Dileptons in B0B^0-Bˉ0\bar{B}^0 Mixing

We report a measurement of the charge asymmetry for same-sign dileptons in $B^0$-$\bar{B}^0$ mixing, $A_{\rm sl}$. The data were collected with the Belle detector at KEKB. Using a data sample of 78 fb$^{-1}$ recorded at the $\Upsilon(4S)$ resonance and 9 fb$^{-1}$ recorded at an energy 60 MeV below the resonance, we measure $A_{\rm sl} = (-1.1 \pm 7.9(\text{stat}) \pm 7.0(\text{sys}))\times 10^{-3}$.Comment: 21 pages, 9 figures, 3 tables, submitted to Physical Review

Measurement of Time-Dependent CP-Violating Parameters in B0 -> K0S K0S decays

We report a measurement of the CP-violating parameters in B0->K0S K0S decays based on a data sample of 657 million BBbar pairs collected at the Y(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. In this study, one neutral B meson is fully reconstructed in the B0->K0S K0S decay mode, and the flavor of the accompanying B meson is identified by its decay products. The CP-violating parameters are measured from the asymmetry in the distributions of the proper-time interval between the two B decays: S = -0.38 +0.69-0.77(stat) +-0.09(syst) and A = -0.38 +-0.38(stat) +-0.05(syst).Comment: 5pages, 2figures, submitted to PR