Phys. Rev. D 93, 112013 (2016) The branching fractions of the $\Upsilon(1S)$ inclusive decays into final
states with a $J/\psi$ or a $\psi(2S)$ are measured with improved precision to
be ...$\BR(\Upsilon(1S)\to J/\psi + {\rm anything})=(5.25\pm
0.13(\mathrm{stat.})\pm 0.25(\mathrm{syst.}))\times 10^{-4}$ and
$\BR(\Upsilon(1S)\to \psi(2S) + {\rm anything})=(1.23\pm
0.17(\mathrm{stat.})\pm 0.11(\mathrm{syst.}))\times 10^{-4}$. The first search
for $\Upsilon(1S)$ decays into $XYZ$ states that decay into a $J/\psi$ or a
$\psi(2S)$ plus one or two charged tracks yields no significant signals for
$XYZ$ states in any of the examined decay modes, and upper limits on their
production rates in $\Upsilon(1S)$ inclusive decays are determined.
We have searched for the decay B0 -> phi gamma using the full Belle data set of 772 x 10^6 BBbar pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB e+e- collider. No ...signal is observed, and we set an upper limit on the branching fraction of B(B0 -> phi gamma) < 1.0 x 10^{-7} at 90% confidence level. This is the most stringent limit on this decay mode to date.
We report the discovery of $\Xi_{c}(3055)^{0}$, observed by its decay into
the final state $\Lambda D^{0}$, and present the first observation and evidence
of the decays of $\Xi_c(3055)^{+}$ and ...$\Xi_c(3080)^{+}$ into $\Lambda D^{+}$.
We also perform a combined analysis of the $\Lambda D^{+}$ with the
$\Sigma_{c}^{++}K^{-}$ and $\Sigma_{c}^{\ast ++}K^{-}$ decay modes to measure
the ratios of branching fractions, masses and widths with improved accuracy. We
measure the ratios of branching fractions ${\cal B}(\Xi_{c}(3055)^{+} \to
\Lambda D^{+})/{\cal B}(\Xi_{c}(3055)^{+} \to
\Sigma_{c}^{++}K^{-})=5.09\pm1.01\pm0.76$, ${\cal B}(\Xi_{c}(3080)^{+} \to
\Lambda D^{+})/{\cal B}(\Xi_{c}(3080)^{+} \to
\Sigma_{c}^{++}K^{-})=1.29\pm0.30\pm0.15$, and ${\cal B}(\Xi_{c}(3080)^{+} \to
\Sigma_{c}^{\ast ++}K^{-})/{\cal B}(\Xi_{c}(3080)^{+} \to
\Sigma_{c}^{++}K^{-})=1.07\pm0.27\pm0.01$, where the uncertainties are
statistical and systematic. The analysis is performed using a 980 fb$^{-1}$
data sample collected with the Belle detector at the KEKB asymmetric-energy
$e^{+}e^{-}$ collider.
Phys. Rev. D 93, 112017 (2016) The process $\gamma \gamma \to p \bar{p} K^+ K^-$ and its intermediate
processes are measured for the first time using a 980~fb$^{-1}$ data sample
collected with the ...Belle detector at the KEKB asymmetric-energy $e^+e^-$
collider. The production of $p \bar{p} K^+ K^-$ and a
$\Lambda(1520)^0~(\bar{\Lambda}(1520)^0)$ signal in the $pK^-$~($\bar{p} K^+$)
invariant mass spectrum are clearly observed. However, no evidence for an
exotic baryon near 1540~MeV/$c^2$, denoted as
$\Theta(1540)^0$~($\bar{\Theta}~(1540)^0$) or
$\Theta(1540)^{++}$~($\Theta(1540)^{--}$), is seen in the $p
K^-$~($\bar{p}K^+$) or $pK^+$~($\bar{p} K^-$) invariant mass spectra. Cross
sections for $\gamma \gamma \to p \bar{p} K^+ K^-$, $\Lambda(1520)^0 \bar{p}
K^+ +c.c.$ and the products $\sigma(\gamma \gamma \to \Theta(1540)^0 \bar{p}
K^+ +c.c.)\BR(\Theta(1540)^0 \to p K^{-})$ and $\sigma(\gamma \gamma \to
\Theta(1540)^{++} \bar{p} K^- +c.c.)\BR(\Theta(1540)^{++}\to p K^{+})$ are
measured. We also determine upper limits on the products of the $\chi_{c0}$ and
$\chi_{c2}$ two-photon decay widths and their branching fractions to $p \bar{p}
K^+ K^-$ at the 90\% credibility level.
We report a measurement of the amplitude ratio
$r_S$
of
$B^0 \to D^0K^{\ast 0}$
and
$B^0 \to \bar {D^0}K^{\ast 0}$
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
$711\,{\rm fb}^{-1}$
corresponding to
$772\times 10^6$
$B\bar {B}$
pairs collected at the
$\Upsilon (4S)$
resonance with the Belle detector at the KEKB
$e^+e^-$
collider. This result is obtained from observables
$x_- = +0.4 ^{+1.0 +0.0}_{-0.6 -0.1} \pm 0.0$
,
$y_- = -0.6 ^{+0.8 +0.1}_{-1.0 -0.0} \pm 0.1$
,
$x_+ = +0.1 ^{+0.7 +0.0}_{-0.4 -0.1} \pm 0.1$
, and
$y_+ = +0.3 ^{+0.5 +0.0}_{-0.8 -0.1} \pm 0.1$
, 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
$B^0 \to D^0K^{\ast 0}$
and
$B^0 \to \bar {D^0}K^{\ast 0}$
.
Phys. Rev. D 93, 052016 (2016) We report inclusive and exclusive measurements for $\chi_{c1}$ and
$\chi_{c2}$ production in $B$ decays. We measure $\mathcal{B}(B \to \chi_{c1}
X)$= $(3.03 \pm ...0.05(\mbox{stat}) \pm 0.24(\mbox{syst})) \times 10^{-3}$ and
$\mathcal{B}(B \to \chi_{c2} X)$= $(0.70 \pm 0.06(\mbox{stat}) \pm
0.10(\mbox{syst})) \times 10^{-3}$. For the first time, $\chi_{c2}$ production
in exclusive $B$ decays in the modes $B^0 \to \chi_{c2}\pi^- K^+$ and $B^+ \to
\chi_{c2} \pi^+ \pi^- K^+$ has been observed, along with first evidence for the
$B^+ \to \chi_{c2} \pi^+ K_S^0$ decay mode. For $\chi_{c1}$ production, we
report the first observation in the $B^+ \to \chi_{c1} \pi^+ \pi^- K^+$, $B^0
\to \chi_{c1} \pi^+ \pi^- K_S^0$ and $B^0 \to \chi_{c1} \pi^0 \pi^- K^+$ decay
modes. Using these decay modes, we observe a difference in the production
mechanism of $\chi_{c2}$ in comparison to $\chi_{c1}$ in $B$ decays. In
addition, we report searches for $X(3872)$ and $\chi_{c1}(2P)$ in the $B^+ \to
(\chi_{c1} \pi^+ \pi^-) K^+$ decay mode. The reported results use $772 \times
10^{6}$ $B\overline{B}$ events collected at the $\Upsilon(4S)$ resonance with
the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider.
Phys. Rev. Lett. 117, 011801 (2016) We report the first observation of the decay $\Lambda^{+}_{c} \rightarrow p
K^{+} \pi^{-}$ using a 980 $\mathrm{fb^{-1}}$ data sample collected by the
Belle ...detector at the KEKB asymmetric-energy $e^{+}e^{-}$ collider. This is the
first doubly Cabibbo-suppressed decay of a charmed baryon to be observed. We
measure the branching ratio of this decay with respect to its Cabibbo-favored
counterpart to be $\mathcal{B}(\Lambda^{+}_{c} \rightarrow p K^{+}
\pi^{-})/\mathcal{B}(\Lambda^{+}_{c} \rightarrow p K^{-}
\pi^{+})=(2.35\pm0.27\pm0.21)\times10^{-3}$, where the uncertainties are
statistical and systematic, respectively.
We report the analysis of the three-body e+e- => B B-bar pi, B B*-bar pi, and B* B*-bar pi processes, including the first observation of the Zb+-(10610) =>B B*-bar+c.c.+- and Zb+-(10650) => ...B*B*-bar+- transitions. We measure visible cross sections for the three-body production of sigma_vis(e+e- => B B*-bar+c.c.+-pi-+=(11.2+-1.0(stat.)+-1.2(syst.)) pb and sigma_vis(e+e- => B*B*-bar+-pi-+)=(5.61+-0.73(stat.)+-0.66(syst.)) pb and set a 90% C.L. upper limit of sigma_vis(e+e- => BB-bar+-pi-+)<2.1 pb. The results are based on a 121.4 1/fb data sample collected with the Belle detector at a center-of-mass energy near the Y(5S) peak.
We report a measurement of the \(B^0\rightarrow\psi(2S)\pi^0\) branching fraction based on the full \(\Upsilon(4S)\) data set of \(772\times10^{6}\) \(B\bar{B}\) pairs collected by the Belle detector ...at the KEKB asymmetric-energy \(e^+e^-\) collider. We obtain \(B(B^0\rightarrow\psi(2S)\pi^0) = (1.17\pm0.17\text{(stat)}\pm0.08\text{(syst)})\times10^{-5}\). The result has a significance of 7.2 standard deviations and is the first observation of the decay \(B^0\rightarrow\psi(2S)\pi^0\).
Phys. Rev. D 93, 051102 (2016) We search for the rare radiative decay $D^0\to\gamma\gamma$ using a data
sample with an integrated luminosity of $832{\rm fb^{-1}}$ recorded by the
Belle detector at ...the KEKB $e^+e^-$ asymmetric-energy collider. We find no
statistically significant signal and set an upper limit on the branching
fraction of ${\cal B}(D^0\to\gamma\gamma)<8.5\times10^{-7}$ at $90\%$
confidence level. This is the most restrictive limit on the decay channel to
date.
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