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Creators/Authors contains: "Konno, T"

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  1. A<sc>bstract</sc> We report a search for the charged-lepton flavor violation in Υ(2S) →ℓτ±(ℓ=e, μ) decays using a 25 fb−1Υ(2S) sample collected by the Belle detector at the KEKBe+easymmetric-energy collider. We find no evidence for a signal and set upper limits on the branching fractions ($$ \mathcal{B} $$ B ) at 90% confidence level. We obtain the most stringent upper limits:$$ \mathcal{B} $$ B (Υ(2S)→ μτ±)<0.23×10−6and$$ \mathcal{B} $$ B (Υ(2S)→ eτ±)<1.12×10−6
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  2. We measure the branching fraction of the decay B D 0 ρ ( 770 ) using data collected with the Belle II detector. The data contain 387 million B B ¯ pairs produced in e + e collisions at the ϒ ( 4 S ) resonance. We reconstruct 8360 ± 180 decays from an analysis of the distributions of the B energy and the ρ ( 770 ) helicity angle. We determine the branching fraction to be ( 0.939 ± 0.021 ( stat ) ± 0.050 ( syst ) ) % , in agreement with previous results. Our measurement improves the relative precision of the world average by more than a factor of two. Published by the American Physical Society2024 
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  3. A<sc>bstract</sc> We present a search for the lepton-flavor-violating decays$$ {B}_s^0 $$ B s 0 →ℓτ±, 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+ecollider. We use$$ {B}_s^0{\overline{B}}_s^0 $$ B s 0 B ¯ s 0 events in which one$$ {B}_s^0 $$ B s 0 meson is reconstructed in a semileptonic decay mode and the other in the signal mode. We find no evidence for$$ {B}_s^0 $$ B s 0 → ℓτ±decays and set upper limits on their branching fractions at 90% confidence level as$$ \mathcal{B} $$ B ($$ {B}_s^0 $$ B s 0 → eτ±)<14×10−4and$$ \mathcal{B} $$ B ($$ {B}_s^0 $$ B s 0 → μτ±)<7.3×10−4. Our result represents the first upper limit on the$$ {B}_s^0 $$ B s 0 → eτ±decay rate. 
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  4. 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. 
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