Measurements of exclusive B_s^0 decays at the Y(5S) resonance

Several exclusive $B_s^0$ decays are studied using a 1.86 fb-1 data sample collected at the Y(5S) resonance with the Belle detector at the KEKB asymmetric energy e^+ e^- collider. In the $B_s^0 \to D_s^- \pi^+$ decay mode we find 10 $B_s^0$ candidates and measure the corresponding branching fraction. Combining the B_s^0 -> D_s^{(*)-} \pi^+, B_s^0 -> D_s^{(*)-} \rho^+, B_s^0 -> J/\psi \phi and B_s^0 -> J/\psi \eta decay modes, a significant $B_s^0$ signal is observed. The ratio \sigma (e^+ e^- -> B_s^* \bar{B}_s^*) / \sigma (e^+ e^- -> B_s^{(*)} \bar{B}_s^{(*)}) = (93^{+7}_{-9} \pm 1)% is obtained at the Y(5S) energy, indicating that $B_s^0$ meson production proceeds predominantly through the creation of $B^*_s \bar{B}^*_s$ pairs. The $B_s^0$ and $B_s^*$ meson masses are measured to be M(B_s^0)=(5370 \pm 1 \pm 3)MeV/c^2 and M(B_s^*)=(5418 \pm 1 \pm 3)MeV/c^2. Upper limits on the B_s^0 -> \gamma \gamma, B_s^0 -> \phi \gamma, B_s^0 -> K^+ K^- and B_s^0 -> D_s^{(*)+} D_s^{(*)-} branching fractions are also reported.Comment: 9 pages, 5 figures, published in Phys. Rev. D76, 012002 (2007

Measurement of the near-threshold e+e−→DDˉe^+e^- \to D \bar D cross section using initial-state radiation

We report measurements of the exclusive cross section for $e^+e^- \to D \bar D$, where $D=D^0$ or $D^+$, in the center-of-mass energy range from the $D \bar D$ threshold to $5\mathrm{GeV}/c^2$ with initial-state radiation. The analysis is based on a data sample collected with the Belle detector with an integrated luminosity of 673 $\mathrm{fb}^{-1}$.Comment: Presented at EPS07 and LP07 conferences, published in PRD(RC

Search for Resonant B±→K±h→K±γγB^{\pm}\to K^{\pm} h \to K^{\pm} \gamma \gamma Decays at Belle

We report measurements and searches for resonant $B^{\pm} \to K^{\pm} h \to K^{\pm} \gamma \gamma$ decays where $h$ is a $\eta,\eta^{\prime},\eta_{c},\eta_{c}(2S),\chi_{c0},\chi_{c2},J/\psi$ meson or the X(3872) particle.Comment: accepted by Physics Letters

Study of charmonia in four-meson final states produced in two-photon collisions

We report measurements of charmonia produced in two-photon collisions and decaying to four-meson final states, where the meson is either a charged pion or a charged kaon. The analysis is based on a 395fb^{-1} data sample accumulated with the Belle detector at the KEKB electron-positron collider. We observe signals for the three C-even charmonia eta_c(1S), chi_{c0}(1P) and chi_{c2}(1P) in the pi^+pi^-pi^+pi^-, K^+K^-pi^+pi^- and K^+K^-K^+K^- decay modes. No clear signals for eta_c(2S) production are found in these decay modes. We have also studied resonant structures in charmonium decays to two-body intermediate meson resonances. We report the products of the two-photon decay width and the branching fractions, Gamma_{gamma gamma}B, for each of the charmonium decay modes.Comment: 22 pages, 12 figure

Observation of the ϕ(1680)\phi(1680) and the Y(2175) in e+e−→ϕπ+π−e^+ e^- \to \phi\pi^+\pi^-

The cross sections for $e^+ e^- \to \phi\pi^+\pi^-$ and e^+ e^- \to \phi \fzero are measured from threshold to $\sqrt{s}=3.0$ $\hbox{GeV}$ using initial state radiation. The analysis is based on a data sample of 673 fb$^{-1}$ collected on and below the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. First measurements are reported for the resonance parameters of the $\phi(1680)$ in the $\phi\pi^+\pi^-$ mode: $m=(1689\pm 7\pm 10)$ MeV/$c^2$ and $\Gamma=(211\pm 14\pm 19)$ MeV/$c^2$. A structure at $\sqrt{s}=2.1 \hbox{GeV}/c^2$, corresponding to the so called Y(2175), is observed; its mass and width are determined to be $2079\pm13^{+79}_{-28}$ MeV/$c^2$ and $192\pm23^{+25}_{-61} \hbox{MeV}/c^2$, respectively.Comment: 11 pages, 6 figures. Add one plot. Accepted by Phys.Rev.D(RC

Moments of the Hadronic Invariant Mass Spectrum in B --> X_c l nu Decays at Belle

We present a measurement of the hadronic invariant mass squared (M^2_X) spectrum in charmed semileptonic B meson decays B --> X_c l nu based on 140 fb^-1 of Belle data collected near the Y(4S) resonance. We determine the first, the second central and the second non-central moments of this spectrum for lepton energy thresholds ranging between 0.7 and 1.9 GeV. Full correlations between these measurements are evaluated.Comment: published version of the paper (one figure added, minor changes in the text); 16 pages, 3 figures, 10 table

Observation of Ds1(2536)+ -> D+pi-K+ and angular decomposition of Ds1(2536)+ -> D*+K0S

Using 462/fb of e+e- annihilation data recorded by the Belle detector, we report the first observation of the decay Ds1(2536)+ -> D+pi-K+. The ratio of branching fractions B(Ds1+ -> D+pi-K+)/B(Ds1+ -> D*+K0) is measured to be (3.27+-0.18+-0.37)%. We also study the angular distributions in the Ds1(2536)+ -> D*+K0S decay and measure the ratio of D- and S-wave amplitudes. The S-wave dominates, with a partial width of Gamma_S/Gamma_total=0.72+-0.05+-0.01.Comment: Submitted to Phys.Rev.D 16 pages, 6 figures, 3 table

Search for new charmonium states in the processes e+ e- --> J/psi D(*) D(*) at sqrt{s} ~ 10.6 GeV

We present a study of the X(3940) state in the process e+e- -> J/psi D* Dbar. The X(3940) mass and width are measured to be (3942 +7 -6 +- 6)MeV/c^2 and Gamma=(37 + 26 - 15 +- 8 MeV. In the process e+e- -> J/psi D* D*bar we have observed another charmonium-like state, which we denote as X(4160), in the spectrum of invariant masses of D*+ D*- combinations. The X(4160) parameters are M= 4156 + 25 - 20 +- 15 MeV/c^2 and Gamma = 139 + 111 -61 +- 21 MeV. The analysis is based on a data sample with an integrated luminosity of 693 /fb recorded near the Upsilon(4S) resonance with the Belle detector at the KEKB e+ e- asymmetric-energy collider.Comment: 7 pages, 2 figures Contribution paper for conferences EPS2007 and Lepton Photon 2007, Belle-Conference-070

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)

Measurement of CP asymmetry in Cabibbo suppressed D0 decays

We measure the CP-violating asymmetries in decays to the D0 -> K+K- and D0 -> pi+pi- CP eigenstates using 540 fb^{-1} of data collected with the Belle detector at or near the Upsilon(4S) resonance. Cabibbo-favored D0 -> K-pi+ decays are used to correct for systematic detector effects. The results, A_{CP}^{KK} = (-0.43 +- 0.30 +- 0.11)% and A_{CP}^{pipi} = (+0.43 +- 0.52 +- 0.12)%, are consistent with no CP violation.Comment: Submitted to Phys. Lett.