Evidence for CP Violation in B0 -> D+D- Decays

We report measurements of the branching fraction and CP violation parameters in B0 -> D+D- decays. The results are based on a data sample that contains 535 x 10^6 BBbar pairs collected at the Upsilon(4S) resonance, with the Belle detector at the KEKB asymmetric-energy e+e- collider. We obtain [1.97 +- 0.20 (stat) +- 0.20 (syst)] x 10^(-4) for the branching fraction of B0 -> D+D-. The measured values of the CP violation parameters are: S = -1.13 +- 0.37 +- 0.09, A = 0.91 +- 0.23 +- 0.06, where the first error is statistical and the second is systematic. We find evidence of CP violation in B0 -> D+D- at the 4.1 sigma confidence level. While the value of S is consistent with expectations from other measurements, the value of the parameter A favors large direct CP violation at the 3.2 sigma confidence level, in contradiction to Standard Model expectations.Comment: 12 pages, 3 figures, submitted to PR

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.

Improved measurement of time-dependent CP violation in B0 -> J/Psi pi0 decays

We report improved measurements of time-dependent CP violation parameters for $B^0(\bar{B}^0) \to J/\psi \pi^0$ decay. This analysis is based on 535 million $B\bar{B}$ pairs accumulated at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy e^+e^- collider. From the distribution of proper time intervals between the two B decays, we obtain the following CP violation parameters $\mathcal{S}_{J/\psi \pi^0} = -0.65\pm0.21 (\rm{stat})\pm0.05 (\rm{syst})$ and $\mathcal{A}_{J/\psi \pi^0} = +0.08\pm0.16 (\rm{stat})\pm0.05 (\rm{syst})$, which are consistent with Standard Model expectations.Comment: Resubmitted to PRD(RC), including 4 figures, 6pages Revision has been made according to communication with PRD referee

Evidence of the Purely Leptonic Decay B- --> tau- nu_tau-bar

We present the first evidence of the decay B- --> tau- nu_tau-bar using 414 fb^-1 of data collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. Events are tagged by fully reconstructing one of the B mesons in hadronic modes. We detect the signal with a significance of 3.5 standard deviations including systematics, and measure the branching fraction to be Br(B- --> tau- nu_tau-bar) = (1.79 +0.56-0.49(stat) +0.46-0.51(syst))*10^-4. This implies that f_B = 0.229 +0.036-0.031(stat) +0.034-0.037(syst) GeV and is the first direct measurement of this quantity.Comment: 6 pages, 3 figures, to appear in Physical Review Letter

Measurement of CP Asymmetries and Branching Fractions in a Time-Dependent Dalitz Analysis of B^0-->(rho pi)^0 and a Constraint on the Quark Mixing Angle phi_2

We present the results of a time-dependent Dalitz plot analysis of B0 --> pi+ pi- pi0 decays based on a 414/fb data sample that contains 449 x 10^6 BB pairs. The data was collected on the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric energy e+e- collider. Combining our analysis with information on charged B decay modes, we perform a full Dalitz and isospin analysis and obtain a constraint on the quark mixing angle phi_2, 68deg. < phi_2 < 95deg. at the 68.3% confidence level for the phi_2 solution consistent with the standard model (SM). A large SM-disfavored region also remains. The branching fractions for the decay processes of B0 --> rho+-(770) pi-+ and B0 --> rho0(770) pi0 are measured to be (22.6 +- 1.1[stat.] +- 4.4 [syst.]) x 10^{-6} and (3.0 +- 0.5 [stat.] +- 0.7 [syst.]) x 10^{-6}, respectively. These are the first branching fraction measurements of the process B0 --> rho(770)pi with the lowest resonance rho(770) explicitly separated from the radial excitations.Comment: 26 pages, 12 figures, to be submitted to Phys. Rev. D; Revision to Phys. Rev. D published versio

Time-Dependent CP Asymmetries in B0 -> Ks pi0 gamma transitions

We report measurements of CP violation parameters in B0->Ks pi0 gamma transitions based on a data sample of 535x10^6 BB pairs collected with the Belle detector at the KEKB asymmetric-energy e+ e- collider. One neutral B meson is fully reconstructed in the B0->Ks pi0 gamma mode. The flavor of the accompanying B meson is identified from its decay products. For a Ks pi0 invariant mass up to 1.8 GeV/c^2, we obtain S = -0.10 +- 0.31 +- 0.07 and A = -0.20 +- 0.20 +- 0.06. For a Ks pi0 invariant mass near the K*0(892) resonance, we obtain S = -0.32 +0.36-0.33 +-0.05 and A=-0.20 +-0.24 +-0.05.Comment: 6 pages, 3 figures, accepted by PR

Measurement of the decay B0→π−ℓ+νB^0\to\pi^-\ell^+\nu and determination of ∣Vub∣|V_{ub}|

We present a measurement of the charmless semileptonic decay $B^0\to\pi^-\ell^+\nu$ using a data sample containing 657$\times 10^6$ $B\bar{B}$ events collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider operating near the $\Upsilon(4S)$ resonance. We determine the total branching fraction of the decay, $\mathcal{B}(B^0\to\pi^-\ell^+\nu)=(1.49\pm 0.04{(\mathrm{stat})}\pm 0.07{(\mathrm{syst})})\times 10^{-4}$. We also report a new precise measurement of the differential decay rate, and extract the Cabibbo-Kobayashi-Maskawa matrix element $|V_{ub}|$ using model-independent and -dependent approaches. From a simultaneous fit to the measured differential decay rate and lattice QCD results, we obtain $|V_{ub}|=(3.43\pm 0.33)\times 10^{-3}$, where the error includes both statistical and systematic uncertainties.Comment: 8 pages, 3 figures, Submitted to PRD(RC

Search for CP Violation in the Decays D0→KS0P0D^0\rightarrow K^0_S P^0

We have searched for CP violation in the decays $D^0\rightarrow K^0_S P^0$ where $P^0$ denotes a neutral pseudo-scalar meson which is either a $\pi^0$, $\eta$, or $\eta'$ using KEKB asymmetric-energy $e^+e^-$ collision data corresponding to an integrated luminosity of 791 fb$^{-1}$ collected with the Belle detector. No evidence of significant CP violation is observed. We report the most precise CP asymmetry measurement in the decay $D^0\rightarrow K^0_S\pi^0$ to date: $A_{CP}^{D^0\rightarrow K^0_S\pi^0}=(-0.28\pm0.19\pm0.10)$. We also report the first measurements of CP asymmetries in the decays $D^0\rightarrow K^0_S\eta$ and $D^0\rightarrow K^0_S\eta'$: $A_{CP}^{D^0\rightarrow K^0_S\eta}=(+0.54\pm0.51\pm0.16)$ and $A_{CP}^{D^0\rightarrow K^0_S\eta'}=(+0.98\pm0.67\pm0.14)$, respectively