Measurement of D0-D0bar mixing and search for CP violation in D0 -> K+K-, pi+pi- decays with the full Belle data set

We report an improved measurement of D0-D0bar mixing and a search for CP violation in D0 decays to CP-even final states K+K- and pi+pi-. The measurement is based on the final Belle data sample of 976/fb. The results are y_CP=(1.11 +- 0.22 +- 0.09)% and A_Gamma=(-0.03 +- 0.20 +- 0.07)%, where the first uncertainty is statistical and the second is systematic.Comment: 8 pages, 5 figures; submitted to Phys. Lett.

Study of X(3872) in BB meson decays

We present results on the X(3872), produced in $B^+ \to X(3872) K^+$ and $B^0 \to X(3872) K^0_S$ decays where $X(3872) \to J/\psi \pi^+ \pi^-$. We report the first statistically significant observation of $B^0 \to X(3872) K^0_S$ and measure the ratio of branching fractions to be $\frac{{\cal B}(B^0 \to X(3872)K^0)} {{\cal B}(B^+ \to X(3872)K^+)} = 0.82 \pm 0.22 \pm 0.05$, consistent with unity. The mass difference between the X(3872) states produced in $B^+$ and $B^0$ decay is found to be $\delta M \equiv M_{XK^+} - M_{XK^0} = (+0.18 \pm 0.89 \pm 0.26)$ MeV/$c^2$, consistent with zero. In addition, we search for the X(3872) in the decay $B^0 \to X(3872)K^+\pi^-$, $X(3872) \to J/\psi \pi^+ \pi^-$. We measure ${\cal B}(B^0 \to X(3872) (K^+ \pi^-)_{NR}) \times {\cal B}(X(3872) \to J/\psi \pi^+ \pi^-) = (8.1 \pm 2.0 ^{+1.1}_{-1.4})\times 10^{-6}$ and we set the 90% C.L. limit, ${\cal B}(B^0 \to X(3872)K^{*}(892)^0) \times {\cal B}(X(3872) \to J/\psi \pi^+ \pi^-) < 3.4 \times 10^{-6}$. The analysis is based on a 605 fb$^{-1}$ data sample collected at the $\Upsilon(4S)$ with the Belle detector at the KEKB collider.Comment: 10 pages, 5 figures, Contributed to the 34th International Conference On High Energy Physics (ICHEP 2008

Hadronic Mass Moments in B -> X_c l nu Decays

We report measurements of the first and second moments of the hadronic invariant mass squared distribution, and )^2>, in B -> X_c l nu decays for minimum lepton momenta ranging from 0.7 to 1.5 GeV/c in the B meson rest frame. The measurement uses BBbar events in which the hadronic decay of one B meson is fully reconstructed and the semileptonic decay of the other B is inferred from the presence of an identified lepton. These results are obtained from a 140 fb^-1 data sample collected near the Y(4S) resonance with the Belle detector at the KEKB asymmetric energy e^+e^- collider.Comment: 9 pages, 2 figures, 4 tables, contributed to Lepton Photon and EPS 200

Measurement of the angle \phi_3 with Dalitz analysis of three-body D^0 decay from B\to D^0 K process

A new method to measure the angle $\phi_3$ of the CKM unitarity triangle using a Dalitz analysis of the three-body decay of the $D^0$ meson from the $B\to D^0 K$ process has been introduced recently. The method employs the interference between $D^0$ and $\bar{D^0}$ to extract both the weak and strong phases. We present a study of statistical and systematic errors of this method using Monte Carlo simulation. A fit of the $D^0$ Dalitz distribution has been performed based on a 140 fb$^{-1}$ sample collected by the Belle detector. We observe the indication of a CP asymmetry with the significance of 2.4 standard deviations. The 90% confidence interval obtained for the $\phi_3$ value is $61^{\circ}<\phi_3<142^{\circ}$.Comment: 25 pages, 14 figures, contributed paper at Lepton Photon 200

Moments of the Electron Energy Spectrum in B --> X_c l \nu decays at Belle

We report a measurement of the inclusive electron energy spectrum for charmed semileptonic decays of B mesons in a 140 fb^-1 data sample collected on the Upsilon(4S) resonance, with the Belle detector at the KEKB asymmetric energy e^+ e^- collider. We determine the first, second and third moments of the electron energy spectrum for threshold values of the electron energy between 0.4 and 1.5 GeV.Comment: 13 pages, 3 figures, 6 tables, contributed to HEP2005 International Europhysics Conference on High Energy Physic

Measurement of D0 -> pilnu (Klnu) and their form factors

Using a data sample of 282 1/fb collected by the Belle experiment at the KEKB e+e- collider, we study D0 -> pilnu and D0 -> Klnu decays (l = mu,e) in e+e- annihilation. We identify D* -> D0pi decays by using the mass of the system recoiling against a fully reconstructed tag-side D* or D meson, allowing for additional primary mesons from fragmentation. Using a novel global reconstruction method that provides very good resolution in neutrino momentum and in q^2 = (p_l+p_nu)^2, we reconstructed D0 -> pilnu and D0 -> Klnu decays. From these events we measured the branching fraction ratios BR(D0 -> pienu)/BR(D0 -> Kenu) = 0.0809 +- 0.0080 +- 0.0032$ and BR(D0 -> pimunu)/BR(D0 -> Kmunu) = 0.0677 +- 0.0078 +- 0.0047, and the semileptonic form factor ratio f+(D0 -> pilnu})^2/f+(D0 -> Klnu})^2|Vcd|^2/|Vcs|^2|_{q^2=0} = 0.041 +- 0.003 +- 0.004, where the errors are statistical and systematic, respectively.Comment: 20 pages, 8 figures; corrected form factor rati

Moments of the Hadronic Mass Spectrum in Inclusive Semileptonic B Decays at Belle

We report a measurement of the first and second moment of the hadronic mass distribution M_X in B -> X_c l nu decays for lepton threshold momenta ranging from 0.9 to 1.6 GeV/c in the center of mass frame. The measurement uses B Bbar events in which the hadronic decay of one B meson is fully reconstructed and a charged lepton from the decay of the other B meson is identified. These results are obtained from a 140 fb^-1 data sample collected near the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric energy e^+ e^- collider.Comment: 9 pages, 3 figures, submitted to ICHEP2004, Beijing, Chin

Observation of h_b(1P)->eta_b(1S)gamma

We report the first observation of the radiative transition h_b(1P)->eta_b(1S)gamma, where the h_b(1P) is produced in Upsilon(5S)->h_b(1P)pi+pi- dipion transitions. We measure the eta_b(1S) mass to be (9401.0+-1.9+1.4-2.4)MeV/c^2 with a width of (12.4+5.5-4.6+11.5-3.4)MeV and a decay branching fraction of BF[h_b(1P)->eta_b(1S)gamma]=(49.8+-6.8+10.9-5.2)%. The measured eta_b(1S) mass corresponds to a hyperfine splitting of (59.3+-1.9+2.4-1.4)MeV/c^2. This value deviates significantly from the current world average obtained from measurements of Upsilon(3S)->eta_b(1S)gamma and Upsilon(2S)->eta_b(1S)gamma reactions. We also report updated results for the h_b(1P) mass (9899.0+-0.4+-1.0)MeV/c^2 and its hyperfine splitting (0.8+-1.1)MeV/c^2. These measurements are performed using a 121.4fb^-1 data sample collected at the peak of the Upsilon(5S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider.Comment: Prepared for International Workshop on Heavy Quarkonium 2011 (QWG 2011), GSI, Darmstadt, Germany, 4-7 Oct 201

Measurement of the branching fractions for B0→Ds∗+π−B^0 \to D_s^{*+}\pi^- and B0→Ds∗−K+B^0 \to D_s^{*-}K^+ decays

We present a study of $B^0 \to D_s^{*+}\pi^-$ and $B^0 \to D_s^{*-}K^+$ decays based on a sample of $657 \times 10^6$ $B\bar{B}$ events collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. We measure the branching fractions to be $\mathcal{B}(B^0 \to D_s^{*+} \pi^-) = (1.75 \pm 0.34 \pm 0.17 \pm 0.11) \times 10^{-5}$ and $\mathcal{B}(B^0 \to D_s^{*-} K^+) = (2.02 \pm 0.33 \pm 0.18 \pm 0.13) \times 10^{-5}, with significances of 6.1 and 8.0 standard deviations, respectively. The first uncertainty is statistical, the second is due to the experimental systematics, and the third is from uncertainties in the$D_s^+$decay branching fractions. From our measurements, we obtain the most precise determination so far of$R_{D^*\pi}$, where$R_{D^*\pi}$is the ratio between amplitudes of the doubly Cabibbo-suppressed decay$B^0 \to D^{*+}\pi^-$and the Cabibbo favored$B^0 \to D^{*-}\pi^+$ decay.Comment: 6 pages, 2 figures, 2 tables. Submitted to PRD (RC

Updated Measurement of phi_3 with a Dalitz Plot Analysis of B->D(*)K Decay

We present an updated measurement of the unitarity triangle angle phi_3 using a Dalitz plot analysis of the K^0_S pi+ pi- decay of the neutral D meson produced in B+- ->D(*)K+- decays. The method exploits the interference between D^0 and Dbar^0 to extract the angle phi_3, strong phase delta and the ratio r of suppressed and allowed amplitudes. We apply this method to a 605 fb-1 data sample collected by the Belle experiment. The analysis uses two modes: B+- -> DK+-, and B+- -> D*K+- with D* -> D pi0, as well as the corresponding charge-conjugate modes. From a combined maximum likelihood fit to the two modes, we obtain phi_3=76+12-13(stat)+-4(syst)+-9(model). The statistical significance of CP violation (phi_3\neq 0) in our measurement is (1-5.5*10^{-4}), or 3.5 standard deviations. These results are preliminary.Comment: 8 pages, 4 figures, 4 tables. Contributed to Rencontres de Moriond EW 200