Phys. Rev. D 92, 012011 (2015) The process $e^+e^- \to \gamma\chi_{cJ}$ ($J$=1, 2) is studied via initial
state radiation using 980 fb$^{-1}$ of data at and around the $\Upsilon(nS)$
($n$=1, 2, 3, 4, ...5) resonances collected with the Belle detector at the KEKB
asymmetric-energy $e^+e^-$ collider. No significant signal is observed except
from $\psi(2S)$ decays. Upper limits on the cross sections between
$\sqrt{s}=3.80$ and $5.56~{\rm GeV}$ are determined at the 90% credibility
level, which range from few pb to a few tens of pb. We also set upper limits on
the decay rate of the vector charmonium $\psi(4040$), $\psi(4160)$, and
$\psi(4415)$ and charmoniumlike $Y(4260)$, $Y(4360)$, and $Y(4660)$ states
to $\gamma\chi_{cJ}$.
Using data samples of \(e^+e^-\) collisions collected at the \(\Upsilon(1S)\), \(\Upsilon(2S)\), and \(\Upsilon(3S)\) resonances with the Belle detector, we search for the three-body decay of the ...\(\Omega(2012)\) baryon to \(K\pi\Xi\). This decay is predicted to dominate for models describing the \(\Omega(2012)\) as a \(K\Xi(1530)\) molecule. No significant \(\Omega(2012)\) signals are observed in the studied channels, and 90\% credibility level upper limits on the ratios of the branching fractions relative to \(K \Xi\) decay modes are obtained.
We report a search for \(X(3872)\) and \(X(3915)\) in \(B^+ \to \chi_{c1} \pi^0 K^+\) decays. We set an upper limit of \(\mathcal{B}(B^+ \to X(3872) K^+) \times \mathcal{B}(X(3872) \to \chi_{c1} ...\pi^0)\) \( < 8.1 \times 10^{-6}\) and \(\mathcal{B}(B^+ \to X(3915) K^+) \times \mathcal{B}(X(3915) \to \chi_{c1} \pi^0)\) \( < 3.8 \times 10^{-5}\) at 90\% confidence level. We also measure \(\mathcal{B}(X(3872) \to \chi_{c1} \pi^0)/\mathcal{B}(X(3872) \to J/\psi \pi^+ \pi^-) < 0.97\) at 90\% confidence level. The results reported here are obtained from \(772 \times 10^{6}\) \(B\overline{B}\) events collected at the \(\Upsilon(4S)\) resonance with the Belle detector at the KEKB asymmetric-energy \(e^+e^-\) collider.
We search for the decay B+ -> l+ nu gamma with l+ = e+ or mu+ using the full Belle data set 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 one B meson in a hadronic decay mode and search for the B+ -> l+ nu gamma decay in the remainder of the event. We observe no significant signal within the phase space of E_gamma^sig > 1 GeV and obtain upper limits of BR(B+ -> e+ nu gamma) < 6.1 x 10^-6, BR(B+ -> mu+ nu gamma) < 3.4 x 10^-6, and BR(B+ -> l+ nu gamma) < 3.5 x 10^-6 at 90 % credibility level.
We report results of a study of charmless B meson decays to three-body KPiPi, KKPi and KKK final states. Measurements of branching fractions for B decays to K+0Pi+Pi-, K+K+K-, K0K+K-, KsKsK+ and ...KsKsKs final states are presented. The decays B0=>K0K+K-, B+=>KsKsK+ and B0=>KsKsKs are observed for the first time. We also report evidence for B+=>K+K-Pi+ decay. For the three-body final states K0K+K-, KsKsPi+, K+K+Pi- and K-Pi+Pi+ 90% confidence level upper limits are reported. Finally, we discuss the possibility of using the three-body B0=>KsK+K- decay for CP violation studies. The results are obtained with a 78 fb^-1 data sample collected at the Y(4S) resonance by the Belle detector operating at the KEKB asymmetric energy e+e- collider.
Phys. Rev. D 91, 071101 (2015) We report a search for the rare charmless decay
$B^+\rightarrow\overline{K}{}^{*0}K^{*+}$ 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. No
statistically significant signal is found and a 90% confidence-level upper
limit is set on the decay branching fraction as $
\mathcal{B}(B^+\rightarrow\overline{K}{}^{*0}K^{*+}) <1.31\times 10^{-6}$.
Phys. Rev. D 93, 011101 (2016) We report new measurements of the total cross sections for $e^+e^-\to
\Upsilon(n{\rm S})\pi^+\pi^-$ ($n$ = 1, 2, 3) and $e^+e^-\to b\bar b$ from a
high-luminosity fine ...scan of the region $\sqrt{s} = 10.63$-$11.05$ GeV with the
Belle detector. We observe that the $\Upsilon(n{\rm S})\pi^+\pi^-$ spectra have
little or no non-resonant component and extract from them the masses and widths
of $\Upsilon(10860)$ and $\Upsilon(11020)$ and their relative phase. We find
$M_{10860}=(10891.1\pm3.2^{+0.6}_{-1.7})$ MeV/$c^2$ and
$\Gamma_{10860}=(53.7^{+7.1}_{-5.6}\,^{+1.3}_{-5.4})$ MeV and report first
measurements $M_{11020}=(10987.5^{+6.4}_{-2.5}\,^{+9.0}_{-2.1})$ MeV/$c^2$,
$\Gamma_{11020}=(61^{+9}_{-19}\,^{+2}_{-20})$ MeV, and $\phi_{\rm
11020}-\phi_{\rm 10860} = (-1.0\pm0.4\,^{+1.4}_{-0.1})$ rad.
We report a new measurement of the e+e−→ ϒ(nS)π+π− (n = 1, 2, 3) cross sections at energies from 10.52 to 11.02 GeV using data collected with the Belle detector at the KEKB asymmetric-energy e+e− ...collider. We observe a new structure in the energy dependence of the cross sections; if described by a Breit-Wigner function its mass and width are found to be M=(10752.7±5.9+0.7−1.1)MeV/c2 and Γ=(35.5+17.6+3.9−11.3−3.3)MeV, where the first error is statistical and the second is systematic. The global significance of the new structure including systematic uncertainty is 5.2 standard deviations. We also find evidence for the e+e−→ ϒ (1S)π+π− process at the energy 10.52 GeV, which is below the BB¯¯¯¯ threshold.
We report the first observation of the doubly-strange baryon $\Xi(1620)^0$ in its decay to $\Xi^-\pi^+$ via $\Xi_c^+ \rightarrow \Xi^- \pi^+ \pi^+$ decays based on a $980\,{\rm fb}^{-1}$ data sample ...collected with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. The mass and width are measured to be 1610.4 $\pm$ 6.0 (stat) $^{+5.9}_{-3.5}$ (syst)~MeV$/c^2$ and 59.9 $\pm$ 4.8 (stat) $^{+2.8}_{-3.0}$ (syst)~MeV, respectively. We obtain 4.0$\sigma$ evidence of the $\Xi(1690)^0$ with the same data sample. These results shed light on the structure of hyperon resonances with strangeness $S=-2$.
The paper is a script of a lecture given at the ISAPP-Baikal summer school in 2018. The lecture gives an overview of the Tunka Advanced Instrument for cosmic rays and Gamma Astronomy (TAIGA) facility ...including historical introduction, description of existing and future setups, and outreach and open data activities.
