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.

Study of the Baryon-Antibaryon Low-Mass Enhancements in Charmless Three-body Baryonic B Decays

The angular distributions of the baryon-antibaryon low-mass enhancements seen in the charmless three-body baryonic B decays B+ -> p pbar K+, B0 -> p pbar Ks, and B0 -> p Lambdabar pi- are reported. A quark fragmentation interpretation is supported, while the gluonic resonance picture is disfavored. Searches for the Theta+ and Theta++ pentaquarks in the relevant decay modes and possible glueball states G with 2.2 GeV/c2 < M-ppbar < 2.4 GeV/c2 in the ppbar systems give null results. We set upper limits on the products of branching fractions, B(B0 -> Theta+ p)\times B(Theta+ -> p Ks) Theta++ pbar) \times B(Theta++ -> p K+) G K+) \times B(G -> p pbar) < 4.1 \times 10^{-7} at the 90% confidence level. The analysis is based on a 140 fb^{-1} data sample recorded on the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider.Comment: 14 pages, 13 figure files, update of hep-ex/0409010 for journal submisssio

Improved Measurement of the Partial-Rate CP Asymmetry in B+ -> K0pi+ and B- -> K0bar pi- Decays

We report an improved measurement of the partial-rate CP asymmetry in B+ => K0pi+ and B- => K0bar pi- decays. The analysis is based on a data sample of 85 million BBbar pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB e+ e- storage ring. We measure Acp(K0pi+-) = 0.07^{+0.09 +0.01}_{-0.08 -0.03}, where the first and second errors are statistical and systematic, respectively; the corresponding 90% confidence-level interval is -0.10 < Acp(K0pi+-) < 0.22 .Comment: 7 pages, 8 figures, submitted to Phys. Rev.

Study of B meson decays to three-body charmless hadronic final states

We report results of a study of charmless B meson decays to three-body KPiPi, KKPi and KKK final states. Measurements of branching fractions for B decays to K+0Pi+Pi-, K+K+K-, K0K+K-, KsKsK+ and KsKsKs final states are presented. The decays B0=>K0K+K-, B+=>KsKsK+ and B0=>KsKsKs are observed for the first time. We also report evidence for B+=>K+K-Pi+ decay. For the three-body final states K0K+K-, KsKsPi+, K+K+Pi- and K-Pi+Pi+ 90% confidence level upper limits are reported. Finally, we discuss the possibility of using the three-body B0=>KsK+K- decay for CP violation studies. The results are obtained with a 78 fb^-1 data sample collected at the Y(4S) resonance by the Belle detector operating at the KEKB asymmetric energy e+e- collider.Comment: 15 pages, 6 figures. To be submitted to PR

Evidence for CP-Violating Asymmetries in B0->pi+pi- Decays and Constraints on the CKM Angle phi2

We present an improved measurement of CP-violating asymmetries in B0 -> pi+ pi- decays based on a 78 fb^-1 data sample collected at the Y(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. We reconstruct one neutral B meson as a B0 -> pi+ pi- CP eigenstate and identify the flavor of the accompanying B meson from inclusive properties of its decay products. We apply an unbinned maximum likelihood fit to the distribution of the time intervals between the two B meson decay points. The fit yields the CP-violating asymmetry amplitudes Apipi = +0.77+/-0.27(stat)+/-0.08(syst) and Spipi = -1.23+/-0.41(stat)+0.08/-0.07(syst), where the statistical uncertainties are determined from Monte Carlo pseudo-experiments. We obtain confidence intervals for CP-violating asymmetry parameters Apipi and Spipi based on a frequentist approach. We rule out the CP-conserving case, Apipi=Spipi=0, at the 99.93% confidence level. We discuss how these results constrain the value of the CKM angle phi2.Comment: 26 pages, 13 figures, submitted to Phys. Rev.

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

Charmless Hadronic Two-Body B Meson Decays

We report the results of a study of two-body B meson decays to the complete set of K pi, pi pi, and K K final states. The study is performed on a data sample of 31.7 +/- 0.3 million B B-bar events recorded on the Upsilon(4S) resonance by the Belle experiment at KEKB. We observe significant signals in all K pi final states and in the pi+ pi- and pi+ pi0 final states. We set limits on the pi0 pi0 and K K final states. A search is performed for partial-rate asymmetries between conjugate states for flavor-specific final states.Comment: Submitted to PR

Study of B -> \rho \pi decays at Belle

This paper describes a study of B meson decays to the pseudoscalar-vector final state \rho\pi using 31.9\times 10^6 B\bar{B} events collected with the Belle detector at KEKB. The branching fractions B(B^+ \to \rho^0\pi^+) = (8.0^{+2.3+0.7}_{-2.0-0.7}) \times 10^{-6} and B(B^0 -> \rho^{+-} \pi^{-+}) = (20.8^{+6.0+2.8}_{-6.3-3.1}) \times 10^{-6} are obtained. In addition, a 90% confidence level upper limit of B(B^0 \to \rho^0\pi^0) < 5.3 \times 10^{-6}is reported.Comment: 14 pages, 3 figures, to be submitted to Phys. Lett.

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