Search for Z′ →μ+μ- in the Lμ-Lτ gauge-symmetric model at Belle

We search for a new gauge boson Z′ that couples only to heavy leptons and their corresponding neutrinos in the process e+e-→Z′(→μ+μ-)μ+μ-, using a 643 fb-1 data sample collected by the Belle experiment at or near the ϒ(1S,2S,3S,4S,5S) resonances at the KEKB collider. While previous searches for Z′ performed a data-based estimation of the initial state radiation effect, our search for the Z′ is the first to include effects due to initial state radiation in the signal simulated samples that were used in estimating the detection efficiency. No signal is observed in the Z′ mass range of 0.212-10 GeV/c2, and we set an upper limit on the coupling strength, g′, constraining the possible Z′ contribution to the anomalous magnetic dipole moment of the muon

Evidence for Isospin Violation and Measurement of CPCP Asymmetries in B→K∗(892)γB \to K^{\ast}(892) \gamma

We report the first evidence for isospin violation in $B \to K^* \gamma$ and the first measurement of difference of $CP$ asymmetries between $B^+ \to K^{*+} \gamma$ and $B^0 \to K^{*0} \gamma$. This analysis is based on the data sample containing $772 \times 10^6 B\bar{B}$ pairs that was collected with the Belle detector at the KEKB energy-asymmetric $e^+ e^-$ collider. We find evidence for the isospin violation with a significance of 3.1$\sigma$, $\Delta_{0+} = (+6.2 \pm 1.5 ({\rm stat.}) \pm 0.6 ({\rm syst.}) \pm 1.2 (f_{+-}/f_{00}))$\%, where the third uncertainty is due to the uncertainty on the fraction of $B^+B^-$ to $B^0\bar{B}^0$ production in $\Upsilon(4S)$ decays. The measured value is consistent with predictions of the SM. The result for the difference of $CP$ asymmetries is $\Delta A_{CP} = (+2.4 \pm 2.8({\rm stat.}) \pm 0.5({\rm syst.}))$\%, consistent with zero. The measured branching fractions and $CP$ asymmetries for charged and neutral $B$ meson decays are the most precise to date. We also calculate the ratio of branching fractions of $B^0 \to K^{*0} \gamma$ to $B_s^0 \to \phi \gamma$.Comment: 11 pages, 7 figures. shown at FPCP2017. accepted by PR

Inclusive study of bottomonium production in association with an η\eta meson in e+e−e^+e^- annihilations near Υ(5S)\Upsilon(5S)

We study bottomonium production in association with an $\eta$ meson in $e^+e^-$ annihilations near the $\Upsilon(5S)$, at a center of mass energy of $\sqrt{s}=10.866\,$GeV. The results are based on the $121.4\,$fb$^{-1}$ data sample collected by the Belle experiment at the asymmetric energy KEKB collider. Only the $\eta$ meson is reconstructed and the missing-mass spectrum of $\eta$ candidates is investigated. We observe the $e^+e^-\to\eta\Upsilon_J(1D)$ process and find evidence for the $e^+e^-\to\eta\Upsilon(2S)$ process, while no significant signals of $\Upsilon(1S)$, $h_b(1P)$, nor $h_b(2P)$ are found. Cross sections for the studied processes are reported.Comment: Submitted to EPJ-

Measurement of Branching Fractions of Hadronic Decays of the Ωc0\Omega_c^0 Baryon

Using a data sample of 980 ${\rm fb}^{-1}$ of $e^+e^-$ annihilation data taken with the Belle detector operating at the KEKB asymmetric-energy $e^+e^-$ collider, we report the results of a study of the decays of the $\Omega_c^0$ charmed baryon into hadronic final states. We report the most precise measurements to date of the relative branching fractions of the $\Omega_c^0$ into $\Omega^-\pi^+\pi^0$, $\Omega^-\pi^+\pi^-\pi^+$, $\Xi^-K^-\pi^+\pi^+$, and $\Xi^0K^-\pi^+$, as well as the first measurements of the branching fractions of the $\Omega_c^0$ into $\Xi^-\bar{K}^0\pi^+$, $\Xi^0\bar{K}^0$, and $\Lambda \bar{K}^0\bar{K}^0$, all with respect to the $\Omega^-\pi^+$ decay. In addition, we investigate the resonant substructure of these modes. Finally, we present a limit on the branching fraction for the decay $\Omega_c^0\to\Sigma^+K^-K^-\pi^+$

Measurement of the τ\tau lepton polarization and R(D∗)R(D^*) in the decay Bˉ→D∗τ−νˉτ\bar{B} \rightarrow D^* \tau^- \bar{\nu}_\tau with one-prong hadronic τ\tau decays at Belle

With the full data sample of $772 \times 10^6$ $B{\bar B}$ pairs recorded by the Belle detector at the KEKB electron-positron collider, the decay $\bar{B} \rightarrow D^* \tau^- \bar{\nu}_\tau$ is studied with the hadronic $\tau$ decays $\tau^- \rightarrow \pi^- \nu_\tau$ and $\tau^- \rightarrow \rho^- \nu_\tau$. The $\tau$ polarization $P_\tau(D^*)$ in two-body hadronic $\tau$ decays is measured, as well as the ratio of the branching fractions $R(D^{*}) = \mathcal{B}(\bar {B} \rightarrow D^* \tau^- \bar{\nu}_\tau) / \mathcal{B}(\bar{B} \rightarrow D^* \ell^- \bar{\nu}_\ell)$, where $\ell^-$ denotes an electron or a muon. Our results, $P_\tau(D^*) = -0.38 \pm 0.51 {\rm (stat)} ^{+0.21}_{-0.16} {\rm (syst)}$ and $R(D^*) = 0.270 \pm 0.035{\rm (stat)} ^{+0.028}_{-0.025}{\rm (syst)}$, are consistent with the theoretical predictions of the Standard Model. The polarization values of $P_\tau(D^*) > +0.5$ are excluded at the 90\% confidence level.Comment: 17 pages, 11 figures, submitted to Physical Review

Measurement of eta_c(1S), eta_c(2S) and non-resonant eta' pi+ pi- production via two-photon collisions

We report the measurement of gamma gamma to eta_c(1S), eta_c(2S) to eta' pi+ pi- with eta' decays to gamma rho and eta pi+ pi- using 941 fb^{-1} of data collected with the Belle detector at the KEKB asymmetric-energy e+e- collider. The eta_c(1S) mass and width are measured to be M = [2984.6\pm0.7 (stat.)\pm2.2 (syst.)] MeV/c^{2} and \Gamma = [30.8^{+2.3}_{-2.2}~(stat.) \pm 2.5~(syst.)] MeV, respectively. First observation of eta_c(2S) to eta' pi+ pi- with a significance of 5.5sigma including systematic error is obtained, and the eta_c(2S) mass is measured to be M = [3635.1\pm3.7~(stat.)\pm2.9~(syst.)] MeV/c^{2}. The products of the two-photon decay width and branching fraction (B) of decays to eta'pi+ pi- are determined to be \Gamma_{gamma gamma}B = [65.4\pm2.6~(stat.)\pm6.9~(syst.)] eV for eta_c(1S) and [5.6^{+1.2}_{-1.1}~(stat.)\pm1.1~(syst.)] eV for eta_c(2S). A new decay mode for the eta_c(1S) to eta'f_0(2080) with f_0(2080) to pi+ pi- is observed with a statistical significance of 20sigma. The f_0(2080) mass and width are determined to be M = [2083^{+63}_{-66}~(stat.)\pm 32~(syst.)] MeV/c^{2} and \Gamma = [178^{+60}_{-178}~(stat.) \pm 55~(syst.)] MeV. The cross sections for gamma gamma to eta' pi+ pi- and eta'f_{2}(1270) are measured for the first time.Comment: 19 pages, 14 figure

Measurements of the absolute branching fractions of B+→XccˉK+B^{+} \to X_{c\bar{c}} K^{+} and B+→Dˉ(∗)0π+B^{+} \to \bar{D}^{(\ast) 0} \pi^{+} at Belle

We present the measurement of the absolute branching fractions of $B^{+} \to X_{c\bar{c}} K^{+}$ and $B^{+} \to \bar{D}^{(\ast) 0} \pi^{+}$ decays, using a data sample of $772\times10^{6}$ $B\bar{B}$ pairs collected at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}e^{-}$ collider. Here, $X_{c\bar{c}}$ denotes $\eta_{c}$, $J/\psi$, $\chi_{c0}$, $\chi_{c1}$, $\eta_{c}(2S)$, $\psi(2S)$, $\psi(3770)$, $X(3872)$, and $X(3915)$. We do not observe significant signals for $X(3872)$ nor $X(3915)$, and set the 90$\%$ confidence level upper limits: ${\cal B}(B^{+} \to X(3872) K^{+} )<2.7 \times 10^{-4}$ and ${\cal B}(B^{+} \to X(3915) K^{+} )<2.9 \times 10^{-4}$. These represent the most stringent upper limit for ${\cal B}(B^{+} \to X(3872) K^{+} )$ to date and the first measurement for ${\cal B}(B^{+} \to X(3915) K^{+} )$. The measured branching fractions for $\eta_{c}$ and $\eta_{c}(2S)$ are the most precise to date: ${\cal B}(B^{+} \to \eta_{c} K^{+} )=(12.3\pm0.8\pm0.7) \times 10^{-4}$ and ${\cal B}(B^{+} \to \eta_{c}(2S)K^{+}) =(4.9\pm1.1\pm0.3) \times 10^{-4}$ , where the first and second uncertainties are statistical and systematic, respectively.Comment: 10 pages, 3 figure

New Zealand Blackcurrant Extract Improves Cycling Performance and Fat Oxidation in Cyclists

PURPOSE: Blackcurrant intake increases peripheral blood flow in humans, potentially by anthocyanin-induced vasodilation which may affect substrate delivery and exercise performance. We examined the effects of New Zealand blackcurrant (NZBC) extract on substrate oxidation, cycling time-trial performance and plasma lactate responses following the time-trial in trained cyclists. METHODS: Using a randomized, double-blind, crossover design, fourteen healthy men (age: 38 ± 13 years, height: 178 ± 4 cm, body mass: 77 ± 9 kg, V?O2max: 53 ± 6 ml·kg-1·min-1, mean ± SD) ingested NZBC extract (300 mg?day-1 CurraNZ™ containing 105 mg anthocyanin) or placebo (PL, 300 mg microcrystalline cellulose M102) for 7-days (washout 14-days). On day 7, participants performed 30 min of cycling (3x10 min at 45, 55 and 65% V?O2max), followed by a 16.1 km time-trial with lactate sampling during a 20-minute passive recovery. RESULTS: NZBC extract increased fat oxidation at 65% V?O2max by 27% (P < 0.05) and improved 16.1 km time-trial performance by 2.4% (NZBC: 1678 ± 108 s, PL: 1722 ± 131 s, P < 0.05). Plasma lactate was higher with NZBC extract immediately following the time-trial (NZBC: 7.06 ± 1.73 mmol?L-1, PL: 5.92 ± 1.58 mmol?L-1 P < 0.01). CONCLUSIONS: Seven days intake of New Zealand blackcurrant extract improves 16.1 km cycling time-trial performance and increases fat oxidation during moderate intensity cycling