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  1. ; ; ; ; ; ; ; ; ; ; et al (, Physical Review Letters)
    We report measurements of time-dependent C P asymmetries in B 0 → K S 0 π 0 γ decays based on a data sample of ( 388 ± 6 ) × 10 6     B B ¯ events collected at the ϒ ( 4 S ) resonance with the Belle II detector. The Belle II experiment operates at the SuperKEKB asymmetric-energy e + e − collider. We measure decay-time distributions to determine C P -violating parameters S and C . We determine these parameters for two ranges of K S 0 π 0 invariant mass: m ( K S 0 π 0 ) ∈ ( 0.8 , 1.0 )     GeV / c 2 , which is dominated by B 0 → K * 0 ( → K S 0 π 0 ) γ decays, and a complementary region m ( K S 0 π 0 ) ∈ ( 0.6 , 0.8 ) ∪ ( 1.0 , 1.8 )     GeV / c 2 . Our results have improved precision as compared to previous measurements and are consistent with theory predictions. Published by the American Physical Society2025 
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    Free, publicly-accessible full text available January 1, 2026
  2. ; ; ; ; ; ; ; ; ; ; et al (, Physical Review Letters)
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  3. ; ; ; ; ; ; ; ; ; ; et al (, Physical Review D)
    The ratio of branching fractions R ( D * ) = B ( B ¯ → D * τ − ν ¯ τ ) / B ( B ¯ → D * ℓ − ν ¯ ℓ ) , where ℓ is an electron or muon, is measured using a Belle II data sample with an integrated luminosity of 189     fb − 1 at the SuperKEKB asymmetric-energy e + e − collider. Data is collected at the ϒ ( 4 S ) resonance, and one B meson in the ϒ ( 4 S ) → B B ¯ decay is fully reconstructed in hadronic decay modes. The accompanying signal B meson is reconstructed as B ¯ → D * τ − ν ¯ τ using leptonic τ decays. The normalization decay, B ¯ → D * ℓ − ν ¯ ℓ , produces the same observable final-state particles. The ratio of branching fractions is extracted in a simultaneous fit to two signal-discriminating variables in both channels and yields R ( D * ) = 0.262 − 0.039 + 0.041 ( stat ) − 0.032 + 0.035 ( syst ) . This result is consistent with the current world average and with Standard Model predictions. Published by the American Physical Society2024 
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  4. ; ; ; ; ; ; ; ; ; ; et al (, Journal of High Energy Physics)
    A<sc>bstract</sc> We report measurements of thee+e−→$$ B\overline{B} $$ B B ¯ ,$$ B{\overline{B}}^{\ast } $$ B B ¯ ∗ , and$$ {B}^{\ast }{\overline{B}}^{\ast } $$ B ∗ B ¯ ∗ cross sections at four energies, 10653, 10701, 10746 and 10805 MeV, using data collected by the Belle II experiment. We reconstruct oneBmeson in a large number of hadronic final states and use its momentum to identify the production process. In the first 2 – 5 MeV above$$ {B}^{\ast }{\overline{B}}^{\ast } $$ B ∗ B ¯ ∗ threshold, thee+e−→$$ {B}^{\ast }{\overline{B}}^{\ast } $$ B ∗ B ¯ ∗ cross section increases rapidly. This may indicate the presence of a pole close to the threshold. 
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  5. ; ; ; ; ; ; ; ; ; ; et al (, Journal of High Energy Physics)
    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. 
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  6. ; ; ; ; ; ; ; ; ; ; et al (, Physical Review Letters)
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  7. ; ; ; ; ; ; ; ; ; ; et al (, Physical Review D)
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  8. ; ; ; ; ; ; ; ; ; ; et al (, Journal of High Energy Physics)
    A<sc>bstract</sc> We present a search for the lepton-flavor-violating decays$$ {B}_s^0 $$ 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$$ {B}_s^0{\overline{B}}_s^0 $$ 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 → ℓ∓τ±decays and set upper limits on their branching fractions at 90% confidence level as$$ \mathcal{B} $$ B ($$ {B}_s^0 $$ B s 0 → e∓τ±)<14×10−4and$$ \mathcal{B} $$ B ($$ {B}_s^0 $$ B s 0 → μ∓τ±)<7.3×10−4. Our result represents the first upper limit on the$$ {B}_s^0 $$ B s 0 → e∓τ±decay rate. 
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  9. ; ; ; ; ; ; ; ; ; ; et al (, Journal of High Energy Physics)
    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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  10. ; ; ; ; ; ; ; ; ; ; et al (, Physical Review Letters)
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