Phys. Rev. Lett. 116, 161801 (2016) We measure the decay $B_s^0\rightarrow K^0\overline{K}^0$ using data
collected at the $\Upsilon(5S)$ resonance with the Belle detector at the KEKB
$e^+e^-$ ...collider. The data sample used corresponds to an integrated luminosity
of 121.4 ${\rm fb^{-1}}$. We measure a branching fraction
$\mathcal{B}(B_s^0\rightarrow K^0\overline{K}^0) = 19.6\,^{+5.8}_{-5.1}({\rm
stat.})\,\pm1.0({\rm sys.})\,\pm 2.0(N^{}_{B_s^0\overline{B}_s^0})\times
10^{-6}$ with a significance of 5.1 standard deviations. This measurement
constitutes the first observation of this decay.
We report the first double differential cross sections of two charged pions
and kaons ($e^+e^- \rightarrow hhX$) in electron-positron annihilation as a
function of the fractional energies of the two ...hadrons for any charge and
hadron combination. The dependence of these di-hadron cross sections on the
topology (same, opposite-hemisphere or anywhere) is also studied with the help
of the event shape variable thrust and its axis. The ratios of these di-hadron
cross sections for different charges and hadron combinations directly shed
light on the contributing fragmentation functions. For example, we find that
the ratio of same-sign pion pairs over opposite-sign pion pairs drops toward
higher fractional energies where disfavored fragmentation is expected to be
suppressed. These di-hadron results are obtained from a $655\,{\rm fb}^{-1}$
data sample collected near the $\Upsilon(4S)$ resonance with the Belle detector
at the KEKB asymmetric-energy $e^+ e^-$ collider. Extending the previously
published single-pion and single-kaon cross sections, single-proton ($e^+e^-
\rightarrow pX$) cross sections are extracted from a $159\,{\rm fb}^{-1}$ data
sub-sample.
Phys. Rev. Lett. 117, 142001 (2016) Using data collected with the Belle detector at the KEKB asymmetric-energy
$e^+e^-$ collider, we measure the energy dependence of the $e^+e^- \to
...h_b(nP)\pi^+\pi^-$ $(n=1,2)$ cross sections from thresholds up to $11.02\,$GeV.
We find clear $\Upsilon(10860)$ and $\Upsilon(11020)$ peaks with little or no
continuum contribution. We study the resonant substructure of the
$\Upsilon(11020) \to h_b(nP)\pi^+\pi^-$ transitions and find evidence that they
proceed entirely via the intermediate isovector states $Z_b(10610)$ and
$Z_b(10650)$. The relative fraction of these states is loosely constrained by
the current data: the hypothesis that only $Z_b(10610)$ is produced is excluded
at the level of 3.3 standard deviations, while the hypothesis that only
$Z_b(10650)$ is produced is not excluded at a significant level.
Phys. Rev. D 93, 032007 (2016) We search for the process $B^0 \to \pi^- \tau^+ \nu_\tau$ using the full
Belle data set of $711\,{\rm fb}^{-1}$, corresponding to $772 \times 10^6
B\bar{B}$ pairs, ...collected at the $\Upsilon(4S)$ resonance with the Belle
detector at the KEKB asymmetric-energy $e^+ e^-$ collider. We reconstruct one
$B$ meson in a hadronic decay and search for the $B^0 \to \pi^- \tau^+
\nu_\tau$ process in the remainder of the event. No significant signal is
observed and an upper limit of $\mathcal{B}(B^0 \to \pi^- \tau^+ \nu_\tau) <
2.5 \times 10^{-4}$ is obtained at the $90\%$ confidence level.
Phys. Rev. D 93, 032006 (2016) We present a determination of the magnitude of the Cabibbo-Kobayashi-Maskawa
matrix element $|V_{cb}|$ using the decay $B\to D\ell\nu_\ell$ ($\ell=e,\mu$)
based on 711 ...fb$^{-1}$ of $e^+e^-\to \Upsilon(4S)$ data recorded by the Belle
detector and containing $772 \times 10^6$ $B\bar{B}$ pairs. One $B$ meson in
the event is fully reconstructed in a hadronic decay mode while the other, on
the signal side, is partially reconstructed from a charged lepton and either a
$D^+$ or $D^0$ meson in a total of 23 hadronic decay modes. The
isospin-averaged branching fraction of the decay $B\to D\ell\nu_\ell$ is found
to be $\mathcal{B}(B^0 \to D^- \ell^+ \nu_{\ell})=(2.31\pm
0.03(\mathrm{stat})\pm 0.11(\mathrm{syst}))\%$. Analyzing the differential
decay rate as a function of the hadronic recoil with the parameterization of
Caprini, Lelouch and Neubert and using the form-factor prediction
$\mathcal{G}(1)=1.0541\pm 0.0083$ calculated by FNAL/MILC, we obtain
$\eta_\mathrm{EW}|V_{cb}|=(40.12\pm 1.34)\times 10^{-3}$, where
$\eta_\mathrm{EW}$ is the electroweak correction factor. Alternatively,
assuming the model-independent form-factor parameterization of Boyd, Grinstein
and Lebed and using lattice QCD data from the FNAL/MILC and HPQCD
collaborations, we find $\eta_\mathrm{EW}|V_{cb}|=(41.10 \pm 1.14)\times
10^{-3}$.
We report a measurement of the branching fraction of B^+ -> tau^+ nu_tau decays using a data sample of 772 x 10^6 BBbar pairs, collected at the Y(4S) resonance with the Belle detector at the KEKB ...asymmetric-energy e^+e^- collider. We reconstruct the accompanying B meson in a semileptonic decay and detect the recoiling B candidate in the decay channel B^+ -> tau^+ nu_tau. We obtain a branching fraction of BR(B^+ -> tau^+ nu_tau) = 1.25 +- 0.28 (stat.) +- 0.27 (syst.) x 10^-4. This result is in good agreement with previous measurements and the expectation from the calculation based on the Standard Model.
Phys. Rev. D 93, 032010 (2016) We present a measurement of the branching fraction and the longitudinal
polarization fraction of $B^{0}\rightarrow\rho^+\rho^-$ decays, as well as the
time-dependent ...$CP$ violating parameters in decays into longitudinally
polarized $\rho^{+}\rho^{-}$ pairs with Belle's final data set of $772\times
10^6$ $B\bar{B}$ pairs, at the $\Upsilon(4S)$ resonance, collected at the
asymmetric-energy $e^+ e^-$ collider KEKB. We obtain ${\cal B}(B^0 \rightarrow
\rho^+ \rho^-)=(28.3\pm 1.5\;(\rm stat) \pm 1.5\;(\rm syst))\times 10^{-6}$,
$f_L = 0.988\pm 0.012\;(\rm stat ) \pm0.023\;(\rm syst)$, ${\cal A}_{CP} =
0.00\pm0.10\;(\rm stat ) \pm0.06\;(\rm syst)$, ${\cal S}_{CP} =
-0.13\pm0.15\;(\rm stat ) \pm0.05\;(\rm syst).$ We perform an isospin analysis
to constrain the CKM angle $\phi_2$ and obtain two solutions with
\begin{eqnarray} \phi_{2} = (93.7\pm10.6)^{\circ},\nonumber \end{eqnarray}
being most compatible with other Standard-Model based fits to the data.
Phys. Rev. D 92, 072014 (2015) We report a measurement of the branching fraction ratios R(D(*)) of Bbar ->
D(*) tau- nubar_tau relative to Bbar -> D()* l- nubar_l (where l = e or mu)
using the full ...Belle data sample of 772 x 10^6 BBbar pairs collected at the
Y(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e-
collider. The measured values are R(D)= 0.375 +- 0.064(stat.) +- 0.026(syst.)
and R(D*) = 0.293 +- 0.038(stat.) +- 0.015(syst.). The analysis uses hadronic
reconstruction of the tag-side B meson and purely leptonic tau decays. The
results are consistent with earlier measurements and do not show a significant
deviation from the standard model prediction.
Phys. Rev. Lett. 115, 221803 (2015) We report the first observation of the decays $B^0 \rightarrow p\bar{\Lambda}
D^{(*)-}$. The data sample of $711$ fb$^{-1}$ used in this analysis corresponds
to ...$772$ million $B\bar{B}$ pairs, collected at the $\Upsilon(4S)$ resonance by
the Belle detector at the KEKB asymmetric-energy $e^{+}e^{-}$ collider. We
observe $19.8\sigma$ and $10.8\sigma$ excesses of events for the two decay
modes and measure the branching fractions of $B^0 \rightarrow p\bar{\Lambda}
D^{-}$ and $B^0 \rightarrow p\bar{\Lambda} D^{*-}$ to be
$(25.1\pm2.6\pm3.5)\times10^{-6}$ and $(33.6\pm6.3\pm4.4)\times10^{-6}$,
respectively, where the first uncertainties are statistical and the second are
systematic. These results are not compatible with the predictions based on the
generalized factorization approach. In addition, a threshold enhancement in the
di-baryon ($p\bar{\Lambda}$) system is observed, consistent with that observed
in similar $B$ decays.
We report a measurement of the amplitude ratio $r_S$ of $B^0 \to D^0K^{*0}$
and $B^0 \to \bar{D^0}K^{*0}$ decays with a Dalitz analysis of $D\to
K_S^0\pi^+\pi^-$ decays, for the first time using a ...model-independent method.
We set an upper limit $r_S < 0.87$ at the 68\% confidence level, using the full
data sample of $772\times10^6$ $B\bar{B}$ pairs collected at the $\Upsilon(4S)$
resonance with the Belle detector at the KEKB $e^+e^-$ collider. This result is
obtained from observables $x_- = +0.4 ^{+1.0 +0.0}_{-0.6 -0.1} \pm0.0$, $y_- =
-0.6 ^{+0.8 +0.1}_{-1.0 -0.0} \pm0.1$, $x_+ = +0.1 ^{+0.7 +0.0}_{-0.4 -0.1}
\pm0.1$ and $y_+ = +0.3 ^{+0.5 +0.0}_{-0.8 -0.1} \pm0.1$, where $x_\pm = r_S
\cos(\delta_S \pm \phi_3)$, $y_\pm = r_S \sin(\delta_S \pm \phi_3)$ and
$\phi_3~(\delta_S)$ is the weak (strong) phase difference between $B^0 \to
D^0K^{*0}$ and $B^0 \to \bar{D^0}K^{*0}$.
