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A<sc>bstract</sc> We measure the cross section ofe+e−→ηcJ/ψat the Υ(nS)(n= 1–5) on-resonance and 10.52 GeV off-resonance energy points using the full data sample collected by the Belle detector with an integrated luminosity of 955 fb−1. We also search for double charmonium production ine+e−→ηcJ/ψvia initial state radiation near theηcJ/ψthreshold. No evident signal of the double charmonium state is found, but evidence for thee+e−→ ηcJ/ψprocess is found with a statistical significance greater than 3.3σnear theηcJ/ψthreshold. The average cross section near the threshold is measured and upper limits of cross sections are set for other regions.more » « less
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A<sc>bstract</sc> We present a search for the lepton-flavor-violating decays$$ {B}_s^0 $$ →ℓ∓τ±, whereℓ=e, μ, using the full data sample of 121 fb−1collected at the Υ(5S) resonance with the Belle detector at the KEKB asymmetric-energye+e−collider. We use$$ {B}_s^0{\overline{B}}_s^0 $$ events in which one$$ {B}_s^0 $$ meson is reconstructed in a semileptonic decay mode and the other in the signal mode. We find no evidence for$$ {B}_s^0 $$ → ℓ∓τ±decays and set upper limits on their branching fractions at 90% confidence level as$$ \mathcal{B} $$ ($$ {B}_s^0 $$ → e∓τ±)<14×10−4and$$ \mathcal{B} $$ ($$ {B}_s^0 $$ → μ∓τ±)<7.3×10−4. Our result represents the first upper limit on the$$ {B}_s^0 $$ → e∓τ±decay rate.more » « less
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A<sc>bstract</sc> We report the first measurement of the inclusivee+e−→$$ b\overline{b} $$ →$$ {D}_s^{\pm } $$ Xande+e−→$$ b\overline{b} $$ → D0/$$ {\overline{D}}^0 $$ Xcross sections in the energy range from 10.63 to 11.02 GeV. Based on these results, we determineσ(e+e−→$$ {B}_s^0{\overline{B}}_s^0 $$ X) andσ(e+e−→$$ B\overline{B} $$ X) in the same energy range. We measure the fraction of$$ {B}_s^0 $$ events at Υ(10860) to befs= ($$ {22.0}_{-2.1}^{+2.0} $$ )%. We determine also the ratio of the$$ {B}_s^0 $$ inclusive branching fractions$$ \mathcal{B} $$ ($$ {B}_s^0 $$ → D0/$$ {\overline{D}}^0 $$ X)/$$ \mathcal{B} $$ ($$ {B}_s^0 $$ →$$ {D}_s^{\pm } $$ X) = 0.416 ± 0.018 ± 0.092. The results are obtained using the data collected with the Belle detector at the KEKB asymmetric-energye+e−collider.more » « less
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A bstract Charged-lepton-flavor-violation is predicted in several new physics scenarios. We update the analysis of τ lepton decays into a light charged lepton ( ℓ = e ± or μ ± ) and a vector meson ( V 0 = ρ 0 , ϕ , ω , K *0 , or $$ \overline{K} $$ K ¯ *0 ) using 980 fb − 1 of data collected with the Belle detector at the KEKB collider. No significant excess of such signal events is observed, and thus 90% credibility level upper limits are set on the τ → ℓV 0 branching fractions in the range of (1.7–4 . 3) × 10 − 8 . These limits are improved by 30% on average from the previous results.more » « less
