We present the first measurements of absolute branching fractions of Ξ_{c}^{0} decays into Ξ^{-}π^{+}, ΛK^{-}π^{+}, and pK^{-}K^{-}π^{+} final states. The measurements are made using a dataset ...comprising (772±11)×10^{6} BBover ¯ 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^{-}→Λover ¯_{c}^{-}Ξ_{c}^{0} using a missing-mass technique; the result is B(B^{-}→Λover ¯_{c}^{-}Ξ_{c}^{0})=(9.51±2.10±0.88)×10^{-4}. We subsequently measure the product branching fractions B(B^{-}→Λover ¯_{c}^{-}Ξ_{c}^{0})B(Ξ_{c}^{0}→Ξ^{-}π^{+}), B(B^{-}→Λover ¯_{c}^{-}Ξ_{c}^{0})B(Ξ_{c}^{0}→ΛK^{-}π^{+}), and B(B^{-}→Λover ¯_{c}^{-}Ξ_{c}^{0})B(Ξ_{c}^{0}→pK^{-}K^{-}π^{+}) with improved precision. Dividing these product branching fractions by the result for B^{-}→Λover ¯_{c}^{-}Ξ_{c}^{0} yields the following branching fractions: B(Ξ_{c}^{0}→Ξ^{-}π^{+})=(1.80±0.50±0.14)%, B(Ξ_{c}^{0}→ΛK^{-}π^{+})=(1.17±0.37±0.09)%, and B(Ξ_{c}^{0}→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_{c}^{0}→Ξ^{-}π^{+}) can be combined with Ξ_{c}^{0} branching fractions measured relative to Ξ_{c}^{0}→Ξ^{-}π^{+} to yield other absolute Ξ_{c}^{0} branching fractions.
We report the analysis of the three-body e^{+}e^{-}→BBover ¯π^{±}, BBover ¯^{*}π^{±}, and B^{*}Bover ¯^{*}π^{±} processes, including the first observations of the Z_{b}^{±}(10610)→BBover ...¯^{*}+c.c.^{±} and Z_{b}^{±}(10650)→B^{*}Bover ¯^{*}^{±} transitions that are found to dominate the corresponding final states. We measure Born cross sections for the three-body production of σ(e^{+}e^{-}→BBover ¯^{*}+c.c.^{±}π^{∓})=17.4±1.6(stat)±1.9(syst) pb and σ(e^{+}e^{-}→B^{*}Bover ¯^{*}^{±}π^{∓})=8.75±1.15(stat)±1.04(syst) pb and set a 90% C.L. upper limit of σ(e^{+}e^{-}→BBover ¯^{±}π^{∓})<2.9 pb. The results are based on a 121.4 fb^{-1} data sample collected with the Belle detector at a center-of-mass energy near the ϒ(10860) peak.
This paper presents a search for the rare flavor-changing neutral current process B0 → K*0τ+τ- using data taken with the Belle detector at the KEKB asymmetric energy e+e- collider. The analysis is ...based on the entire ϒ ( 4S ) resonance data sample of 711 fb-1 , corresponding to 772×106B B ¯ pairs. In our search we fully reconstruct the companion B meson produced in the process e+e- → ϒ ( 4S ) → B B ¯ from its hadronic decay modes, and look for the decay B0 → K*0τ+τ- in the rest of the event. No evidence for a signal is found. We report an upper limit on the branching fraction B ( B0 → K*0τ+τ- ) <3.1×10-3 at 90% confidence level. This is the first direct limit on B ( B0 → K*0τ+τ- ) .
We perform a full amplitude analysis of the process e+e−→J/ψDD¯, where D refers to either D0 or D+. A new charmoniumlike state X*(3860) that decays to DD¯ is observed with a significance of 6.5σ. Its ...mass is (3862−32+26 −13+40) MeV/c2, and its width is (201−67+154 −82+88) MeV. The JPC=0++ hypothesis is favored over the 2++ hypothesis at the level of 2.5σ. The analysis is based on the 980 fb−1 data sample collected by the Belle detector at the asymmetric-energy e+e− collider KEKB.
We present the first measurements of absolute branching fractions of Ξc0 decays into Ξ−π+, ΛK−π+, and pK−K−π+ final states. The measurements are made using a dataset comprising (772±11)×106 BB¯ 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−Ξc0 using a missing-mass technique; the result is B(B−→Λ¯c−Ξc0)=(9.51±2.10±0.88)×10−4. We subsequently measure the product branching fractions B(B−→Λ¯c−Ξc0)B(Ξc0→Ξ−π+), B(B−→Λ¯c−Ξc0)B(Ξc0→ΛK−π+), and B(B−→Λ¯c−Ξc0)B(Ξc0→pK−K−π+) with improved precision. Dividing these product branching fractions by the result for B−→Λ¯c−Ξc0 yields the following branching fractions: B(Ξc0→Ξ−π+)=(1.80±0.50±0.14)%, B(Ξc0→ΛK−π+)=(1.17±0.37±0.09)%, and B(Ξc0→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(Ξc0→Ξ−π+) can be combined with Ξc0 branching fractions measured relative to Ξc0→Ξ−π+ to yield other absolute Ξc0 branching fractions.
We report the first observation of the double strange baryon Ξ(1620)^{0} in its decay to Ξ^{-}π^{+} via Ξ_{c}^{+}→Ξ^{-}π^{+}π^{+} decays based on a 980 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±6.0(stat)_{-4.2}^{+6.1} (syst) MeV/c^{2} and 59.9±4.8(stat)_{-7.1}^{+2.8}(syst) MeV, respectively. We obtain 4.0σ evidence of the Ξ(1690)^{0} with the same data sample. These results shed light on the structure of hyperon resonances with strangeness S=-2.
Using a data sample of 980 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 excited Ξc states ...that decay, via the emission of photons and/or charged pions, into Ξc0 or Ξc+ ground state charmed-strange baryons. We present new measurements of the masses of all members of the Ξc′, Ξc(2645), Ξc(2790), Ξc(2815), and Ξc(2980) isodoublets, measurements of the intrinsic widths of those that decay strongly, and evidence of previously unknown transitions.
Using a data sample of 921.9 fb-1 collected with the Belle detector, we study the process of $e^+e^- → D^+_s D_{s1}(2536)^-+c.c.$ via initial-state radiation. We report the first observation of a ...vector charmoniumlike state decaying to $D^+_s D_{s1}(2536)^-+c.c.$ with a significance of $5.9σ$, including systematic uncertainties. The measured mass and width are $(4625.9^{+6.2}_{-6.0}$(stat)$±0.4$(syst)) MeV/$c_2$ and ($49.8^{+13.9}_{-11.5}$(stat)$±4.0$(syst)) MeV, respectively. The product of the $e^+e^- → D^+_s D_{s1}(2536)^-+c.c.$ cross section and the branching fraction of $D_{s1}(2536)^- → \bar{D}^{*0}K^-$ is measured from the $D_s \bar{D}_{s1}(2536)$ threshold to $5.59$ GeV.
Using a sample of 771.6×10(6) ϒϒ(4S) decays collected by the Belle experiment at the KEKB e(+)e(-) collider, we observe, for the first time, the transition ϒ(4S)→ηh(b)(1P) with the branching fraction ...Bϒ(4S)→ηh(b)(1P)=(2.18±0.11±0.18)×10(-3) and we measure the h(b)(1P) mass M(h(b)(1P))=(9899.3±0.4±1.0) MeV/c(2), corresponding to the hyperfine (HF) splitting ΔM(HF)(1P)=(0.6±0.4±1.0) MeV/c(2). Using the transition h(b)(1P)→γη(b)(1S), we measure the η(b)(1S) mass M(η(b)(1S))=(9400.7±1.7±1.6) MeV/c(2), corresponding to ΔM(HF)(1S)=(59.6±1.7±1.6) MeV/c(2), the η(b)(1S) width Γ(η(b)(1S))=(8(-5)(+6)±5) MeV/c(2) and the branching fraction Bh(b)(1P)→γη(b)(1S)=(56±8±4)%.
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