We report the observation of Υ(2S) → γηb(1S) decay based on analysis of the inclusive photon spectrum of 24.7 fb-1 of e+e- collisions at the Υ(2S) center-of-mass energy collected with the Belle ...detector at the KEKB asymmetric-energy e+e- collider. We measure a branching fraction of B(Υ(2S) → γηb (1S) = (6.1$+0.6+0.9\atop{-0.7-0.6}$) × 10-4, and derive an ηb (1S) mass of 9394.8$+2.7+4.5\atop{-3.1-2.7}$ MeV/c2, where the uncertainties are statistical and systematic, respectively. The significance of our measurement is greater than 7 standard deviations, constituting the first observation of this decay mode.
The first search for double charged charmoniumlike state production in (1S) and (2S) decays and in e+e− annihilation at s=10.52, 10.58, and 10.867 GeV is conducted using data collected with the Belle ...detector at the KEKB asymmetric energy electron-positron collider. No significant signals are observed in any of the studied modes, and the 90% credibility level upper limits on their product branching fractions in (1S) and (2S) decays B((1S,2S)→Zc+Zc(′)−)×B(Zc+→π++cc¯) (cc¯=J/ψ, χc1(1P), ψ(2S)) and the product of Born cross section and branching fraction for e+e−→Zc+Zc(′)− (σ(e+e−→Zc+Zc(′)−)×B(Zc+→π++cc¯)) at s=10.52, 10.58, and 10.867 GeV are determined. Here, Zc refers to the Zc(3900) and Zc(4200) observed in the πJ/ψ final state, the Zc1(4050) and Zc2(4250) in the πχc1(1P) final state, and the Zc(4050) and Zc(4430) in the πψ(2S) final state.
We present a measurement of angular observables and a test of lepton flavor universality in the B→K^{*}ℓ^{+}ℓ^{-} decay, where ℓ is either e or μ. The analysis is performed on a data sample ...corresponding to an integrated luminosity of 711 fb^{-1} containing 772×10^{6} BBover ¯ pairs, collected at the ϒ(4S) resonance with the Belle detector at the asymmetric-energy e^{+}e^{-} collider KEKB. The result is consistent with standard model (SM) expectations, where the largest discrepancy from a SM prediction is observed in the muon modes with a local significance of 2.6σ.
We present the first measurements of absolute branching fractions of Ξ c0 decays into Ξ -π+ , Λ K-π+ , and pK-K-π+ final states. The measurements are made using a dataset comprising ( 772±11 ) ×106 B ...B ¯ pairs collected at the Υ ( 4S ) resonance with the Belle detector at the KEKB e+e- collider. We first measure the absolute branching fraction for B- → Λ ¯ c- Ξ c0 using a missing-mass technique; the result is B ( B- → Λ ¯ c- Ξ c0 ) = ( 9.51±2.10±0.88 ) ×10-4 . We subsequently measure the product branching fractions B ( B- → Λ ¯ c- Ξ c0 ) B ( Ξ c0 → Ξ -π+ ) , B ( B- → Λ ¯ c- Ξ c0 ) B ( Ξ c0 → Λ K-π+ ) , and B ( B- → Λ ¯ c- Ξ c0 ) B ( Ξ c0 → pK-K-π+ ) with improved precision. Dividing these product branching fractions by the result for B- → Λ ¯ c- Ξ c0 yields the following branching fractions: B ( Ξ c0 → Ξ -π+ ) = ( 1.80±0.50±0.14 ) % , B ( Ξ c0 → Λ K-π+ ) = ( 1.17±0.37±0.09 ) % , and B ( Ξ c0 → pK-K-π+ ) = ( 0.58±0.23±0.05 ) % . For the above branching fractions, the first uncertainties are statistical and the second are systematic. Our result for B ( Ξ c0 → Ξ -π+ ) can be combined with Ξ c0 branching fractions measured relative to Ξ c0 → Ξ -π+ to yield other absolute Ξ c0 branching fractions.
We report measurements of isospin asymmetry ${\mathrm{{\Delta}}}_{0{-}}$ and difference of direct $CP$ asymmetries $\mathrm{{\Delta}}{A}_{CP}$ between charged and neutral ...$B{\rightarrow}{X}_{s}{\gamma}$ decays. This analysis is based on the data sample containing $772\times{}{10}^{6}B\overline{B}$ pairs that was collected with the Belle detector at the KEKB energy-asymmetric ${e}^{+}{e}^{{-}}$ collider. Using a sum-of-exclusive technique with invariant ${X}_{s}$ mass up to $2.8\text{ }\text{ }\mathrm{GeV}/{c}^{2}$, we obtain ${\mathrm{{\Delta}}}_{0{-}}={-}0.48\pm{}1.49(\mathrm{stat})\pm{}0.97(\mathrm{syst})\pm{}1.15({f}_{+{-}}/{f}_{00})$% and $\mathrm{{\Delta}}{A}_{CP}=+3.69\pm{}2.65(\mathrm{stat})\pm{}0.76(\mathrm{syst})$%, where the last uncertainty for ${\mathrm{{\Delta}}}_{0{-}}$ is due to the uncertainty on the production ratio of ${B}^{+}{B}^{{-}}$ to ${B}^{0}{\overline{B}}^{0}$ in $\mathrm{{\Upsilon}}(4S)$ decays. The measured value of ${\mathrm{{\Delta}}}_{0{-}}$ is consistent with zero, allowing us to constrain the resolved photon contribution in the $B{\rightarrow}{X}_{s}{\gamma}$, and improve the branching fraction prediction. The result for $\mathrm{{\Delta}}{A}_{CP}$ is consistent with the prediction of the SM. We also measure the direct $CP$ asymmetries for charged and neutral $B{\rightarrow}{X}_{s}{\gamma}$ decays. All the measurements are the most precise to date.
We report searches for the processes e+ e- → π+ π- π0χbJ and e+ e- → ΦχbJ (J = 1,2) based on data samples collected by the Belle experiment at the KEKB collider. We report the first observation of ...the process e+ e-- → ( π+ π- π0) non - ω χ b1 and first evidence for e+ e- → ωχbJ in the vicinity of the Υ(11020 ) resonance, with center-of-mass energies from 10.96 to 11.05 GeV. The significances for ( π + π - π 0 ) non - ω χ b 1 and ω χ b J are greater than 5.3 σ and 4.0 σ , respectively. We also investigate the energy dependence of the e+ e-→ π+ π- π0 χbJ cross section, but we cannot determine whether the contributions are from the Υ (10860) and Υ (11020) resonances or nonresonant continuum processes. The signals for e+ e- → ΦχbJ are not significant, and the upper limits of the Born cross sections at the 90% confidence level are 0.7 and 1.0 pb for e+ e- → Φχb1 and Φχb2, respectively, for center-of-mass energies from 10.96 to 11.05 GeV.
Flexible bronchoscopy (FB) is commonly performed by respiratory physicians for diagnostic as well as therapeutic purposes. However, bronchoscopy practices vary widely across India and worldwide. The ...three major respiratory organizations of the country supported a national-level expert group that formulated a comprehensive guideline document for FB based on a detailed appraisal of available evidence. These guidelines are an attempt to provide the bronchoscopist with the most scientifically sound as well as practical approach of bronchoscopy. It involved framing appropriate questions, review and critical appraisal of the relevant literature and reaching a recommendation by the expert groups. The guidelines cover major areas in basic bronchoscopy including (but not limited to), indications for procedure, patient preparation, various sampling procedures, bronchoscopy in the ICU setting, equipment care, and training issues. The target audience is respiratory physicians working in India and well as other parts of the world. It is hoped that this document would serve as a complete reference guide for all pulmonary physicians performing or desiring to learn the technique of flexible bronchoscopy.
Here, we report on the first Belle search for a light CP-odd Higgs boson, A0, that decays into low mass dark matter, χ, in final states with a single photon and missing energy. We search for events ...produced via the dipion transition Υ(2S)→Υ(1S)π+π-, followed by the on-shell process Υ(1S)→γA0 with A0→χχ, or by the off-shell process Υ(1S)→γχχ. Utilizing a data sample of 157.3×106 Υ(2S) decays, we find no evidence for a signal. We set limits on the branching fractions of such processes in the mass ranges MA0 <8.97 GeV/c2 and Mχ<4.44 GeV/c2. We then use the limits on the off-shell process to set competitive limits on WIMP-nucleon scattering in the WIMP mass range below 5 GeV/c2.
Using data samples of 89.5 fb-1, 711.0 fb-1, and 121.4 fb-1 collected with the Belle detector at the KEKB asymmetric-energy e+e- collider at center-of-mass energies 10.52 GeV, 10.58 GeV,and 10.867 ...GeV, respectively, we study the exclusive reactions e+e- → γχcj (J = 0, 1, 2) and e+e-→ γηc. A significant γχc1 signal is observed for the first time at cJ s = 10.58 GeV with a significance of 5.1σ including systematic uncertainties. No significant excesses for γχc0, γχc2, and γηc final states are found, and we set 90% credibility level upper limits on the Born cross sections (σB) at 10.52 GeV, 10.58 GeV, and 10.867 GeV. Together with cross sections measured by BESIII-+at lower center-of-mass energies, the energy dependency of σB(e+ e- → γχc1 ) is obtained.
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