skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.


Search for: All records

Creators/Authors contains: "Dossett, D."

Note: When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external site maintained by the publisher. Some full text articles may not yet be available without a charge during the embargo (administrative interval).
What is a DOI Number?

Some links on this page may take you to non-federal websites. Their policies may differ from this site.

  1. 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 
    more » « less
  2. 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. 
    more » « less
  3. 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
  4. We search for the rare decay B + K + ν ν ¯ in a 362 fb 1 sample of electron-positron collisions at the ϒ ( 4 S ) resonance collected with the Belle II detector at the SuperKEKB collider. We use the inclusive properties of the accompanying B meson in ϒ ( 4 S ) B B ¯ events to suppress background from other decays of the signal B candidate and light-quark pair production. We validate the measurement with an auxiliary analysis based on a conventional hadronic reconstruction of the accompanying B meson. For background suppression, we exploit distinct signal features using machine learning methods tuned with simulated data. The signal-reconstruction efficiency and background suppression are validated through various control channels. The branching fraction is extracted in a maximum likelihood fit. Our inclusive and hadronic analyses yield consistent results for the B + K + ν ν ¯ branching fraction of [ 2.7 ± 0.5 ( stat ) ± 0.5 ( syst ) ] × 10 5 and [ 1.1 0.8 + 0.9 ( stat ) 0.5 + 0.8 ( syst ) ] × 10 5 , respectively. Combining the results, we determine the branching fraction of the decay B + K + ν ν ¯ to be [ 2.3 ± 0.5 ( stat ) 0.4 + 0.5 ( syst ) ] × 10 5 , providing the first evidence for this decay at 3.5 standard deviations. The combined result is 2.7 standard deviations above the standard model expectation. Published by the American Physical Society2024 
    more » « less
  5. We report a measurement of decay-time-dependent charge-parity ( C P ) asymmetries in B 0 K S 0 K S 0 K S 0 decays. We use 387 × 10 6 B B ¯ pairs collected at the ϒ ( 4 S ) resonance with the Belle II detector at the SuperKEKB asymmetric-energy electron-positron collider. We reconstruct 220 signal events and extract the C P -violating parameters S and C from a fit to the distribution of the decay-time difference between the two B mesons. The resulting confidence region is consistent with previous measurements in B 0 K S 0 K S 0 K S 0 and B 0 ( c c ¯ ) K 0 decays and with predictions based on the standard model. Published by the American Physical Society2024 
    more » « less
  6. A<sc>bstract</sc> We report results from a study ofB±→ DK±decays followed byDdecaying to theCP-even final stateK+Kand CP-odd final state$$ {K}_S^0{\pi}^0 $$ K S 0 π 0 , whereDis an admixture ofD0and$$ {\overline{D}}^0 $$ D ¯ 0 states. These decays are sensitive to the Cabibbo-Kobayashi-Maskawa unitarity-triangle angleϕ3. The results are based on a combined analysis of the final data set of 772×106$$ B\overline{B} $$ B B ¯ pairs collected by the Belle experiment and a data set of 198×106$$ B\overline{B} $$ B B ¯ pairs collected by the Belle II experiment, both in electron-positron collisions at the Υ(4S) resonance. We measure the CP asymmetries to be$$ \mathcal{A} $$ A CP+= (+12.5±5.8±1.4)% and$$ \mathcal{A} $$ A CP−= (−16.7±5.7±0.6)%, and the ratios of branching fractions to be$$ \mathcal{R} $$ R CP+= 1.164±0.081±0.036 and$$ \mathcal{R} $$ R CP−= 1.151±0.074±0.019. The first contribution to the uncertainties is statistical, and the second is systematic. The asymmetries$$ \mathcal{A} $$ A CP+and$$ \mathcal{A} $$ A CP−have similar magnitudes and opposite signs; their difference corresponds to 3.5 standard deviations. From these values we calculate 68.3% confidence intervals of (8.5°3< 16.5°) or (84.5°3< 95.5°) or (163.3°3< 171.5°) and 0.321 <rB< 0.465. 
    more » « less