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Levit, D. (ORCID:0000000157896205)

Publications and source records attributed to Levit, D. (ORCID:0000000157896205).

10 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Evidence of h b ( 2 P ) → ϒ ( 1 S ) η Decay and Search for h b ( 1 P , 2 P ) → ϒ ( 1 S ) π 0 with the Belle Detector

We report the first evidence for the h b ( 2 P ) → ϒ ( 1 S ) η transition with a significance of 3.5 standard deviations. The decay branching fraction is measured to be B [ h b ( 2 P ) → ϒ ( 1 S ) η ] = ( 7.1 − 3.2 + 3.7 ± 0.8 ) × 10 − 3 , which is noticeably smaller than expected. We also set upper limits on π 0 transitions of B [ h b ( 2 P ) → ϒ ( 1 S ) π 0 ] < 1.8 × 10 − 3 , and B [ h b ( 1 P ) → ϒ ( 1 S ) π 0 ] < 1.8 × 10 − 3 , at the 90% confidence level. These results are obtained with a 131.4 fb − 1 data sample collected near the ϒ ( 5 S ) resonance with the Belle detector at the KEKB asymmetric-energy e + e − collider. Published by the American Physical Society 2024

Kovalenko, E. (ORCID:0000000180841931)↗
DOE OSTI2024

Angular analysis of B → K * e + e − in the low- q 2 region with new electron identification at Belle

We perform an angular analysis of the B → K * e + e − decay for the dielectron mass squared, q 2 , range of 0.0008 – 1.1200 GeV 2 / c 4 using the full Belle dataset in the K * 0 → K + π − and K * + → K S 0 π + channels, incorporating new methods of electron identification to improve the statistical power of the dataset. This analysis is sensitive to contributions from right-handed currents from physics beyond the Standard Model by constraining the Wilson coefficients C 7 ( ′ ) . We perform a fit to the B → K * e + e − differential decay rate and measure the imaginary component of the transversality amplitude to be A T Im = − 1.27 ± 0.52 ± 0.12 , and the K * transverse asymmetry to be A T ( 2 ) = 0.52 ± 0.53 ± 0.11 , with F L and A T Re fixed to the Standard Model values. The resulting constraints on the value of C 7 ′ are consistent with the Standard Model within a 2 σ confidence interval. Published by the American Physical Society 2024

Ferlewicz, D. (ORCID:0000000243741234)↗
DOE OSTI2024

Measurements of the Branching Fraction, Polarization, and C P Asymmetry for the Decay B 0 → ω ω

We present a comprehensive study of B 0 → ω ω decays using 772 × 10 6 B B ¯ pairs collected with the Belle detector at the KEKB e + e − collider. This process is a suppressed charmless decay into two vector mesons and can exhibit interesting polarization and C P violation. The decay is observed for the first time with a significance of 7.9 standard deviations. We measure a branching fraction B = ( 1.53 ± 0.29 ± 0.17 ) × 10 − 6 , a fraction of longitudinal polarization f L = 0.87 ± 0.13 ± 0.13 , and a time-integrated C P asymmetry A C P = − 0.44 ± 0.43 ± 0.11 , where the first uncertainties listed are statistical and the second are systematic. This is the first observation of B 0 → ω ω and the first measurements of f L and A C P for this decay. Published by the American Physical Society 2024

Physics↗
DOE OSTI2024

Search for Baryon-Number-Violating Processes in B − Decays to the Ξ ¯ c 0 Λ ¯ c − Final State

We report the results of the first search for B − decays to the Ξ ¯ c 0 Λ ¯ c − final state using 711 fb − 1 of data collected at the ϒ ( 4 S ) resonance with the Belle detector at the KEKB asymmetric-energy e + e − collider. The results are interpreted in terms of both direct baryon-number-violating B − decay and Ξ c 0 − Ξ ¯ c 0 oscillations which follow the standard model decay B − → Ξ c 0 Λ ¯ c − . We observe no evidence for baryon number violation and set the 95% confidence-level upper limits on the ratio of baryon-number-violating and standard model branching fractions B ( B − → Ξ ¯ c 0 Λ ¯ c − ) / B ( B − → Ξ c 0 Λ ¯ c − ) to be < 2.7 % and on the effective angular frequency of mixing ω in Ξ c 0 − Ξ ¯ c 0 oscillations to be < 0.76 ps − 1 (equivalent to τ mix > 1.3 ps ). Published by the American Physical Society 2024

Physics↗
DOE OSTI2024

Search for the decay B s 0 → J / ψ π 0 at Belle experiment

We have analyzed 121.4 fb − 1 of data collected at the ϒ ( 5 S ) resonance by the Belle experiment using the KEKB asymmetric-energy e + e − collider to search for the decay B s 0 → J / ψ π 0 . We observe no signal and report an upper limit on the branching fraction B ( B s 0 → J / ψ π 0 ) of 1.21 × 10 − 5 at 90% confidence level. This result is the most stringent, improving the previous bound by 2 orders of magnitude. Published by the American Physical Society 2024

Astronomy & Astrophysics↗
DOE OSTI2024

Search for a dark leptophilic scalar produced in association with τ + τ − pair in e + e − annihilation at center-of-mass energies near 10.58 GeV

A dark leptophilic scalar ( ϕ L ) is a hypothetical particle that couples only to leptons rather than quarks. We report on a search for ϕ L in the e + e − → τ + τ − ϕ L , ϕ L → ℓ + ℓ − ( ℓ = e , μ ) process using 626 fb − 1 of data collected by the Belle experiment near the ϒ ( 4 S ) resonance. We validate the backgrounds with multiple control regions in data, using a novel multiclass multivariate event classifier. In absence of a signal, we quote upper limits at the 90% confidence level on the coupling between ϕ L and leptons. Our bounds, obtained in a blinded approach, are 19% more constraining than the previous limits, averaged over the mass range 0.04 ≤ m ϕ L ≤ 6.5 GeV . We exclude the parameter space below 4 GeV favored by measurement of the anomalous magnetic moment of the muon. Published by the American Physical Society 2024

Biswas, D. (ORCID:0000000275433471)↗
DOE OSTI2024

Search for baryon and lepton number violating decays D → p ℓ

We search for the baryon and lepton number violating charm decays, D → p ℓ , where D is either a D 0 or a D ¯ 0 and ℓ is a muon or an electron, using a data sample of 921 fb − 1 collected by the Belle detector at the KEKB asymmetric energy e + e − collider. In the absence of significant signals, we set upper limits on the branching fractions in the range ( 5 – 8 ) × 10 − 7 at a 90% confidence level, depending on the decay mode. Published by the American Physical Society 2024

Astronomy & Astrophysics↗
DOE OSTI2023

Measurement of the e + e - → $ {B}_s^0{\overline{B}}_s^0X $ cross section in the energy range from 10.63 to 11.02 GeV using inclusive $ {D}_s^{+} $ and D 0 production

We report the first measurement of the inclusive e + e - → $b\bar{b}$ → D$^±_s$ X and e + e - → $b\bar{b}$ → D 0 / $\overline{D}^0$ X cross sections in the energy range from 10.63 to 11.02 GeV. Based on these results, we determine σ(e + e - → ${B}_s^0{\overline{B}}_s^0$ X) and σ(e + e - → $B\overline{B}$ X) in the same energy range. We measure the fraction of ${B}_s^0$ events at Υ(10860) to be f s = (${22.0}_{-2.1}^{+2.0}$)%. We determine also the ratio of the ${B}_s^0$ inclusive branching fractions $\mathcal{B}$(${B}_s^0$ → D 0 / $\overline{D}^0$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-energy e + e - collider.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Measurement of the mass and width of the Λ c ⁢(2625) + charmed baryon and the branching ratios of Λ c ⁢(2625) + → Σ$^{0}_{c}$π + and Λ c ⁢(2625) + → Σ$^{++}_{c}$π -

Using the entire data sample of 980 fb -1 collected at or near the Y⁡(4⁢S) resonance with the Belle detector operating at the KEKB asymmetric-energy e + ⁢e - collider, we report the measurement of the mass, width, and the branching ratios of the Λ c (2625) + charmed baryon. The mass difference between Λ c ⁢(2625) + and Λ$^{+}_{c}$ is measured to be M⁡(Λ c ⁢(2625) + )-M⁡(Λ$^{+}_{c}$)=341.518±0.006±0.049 MeV/c 2 . The upper limit on the width is measured to be Γ⁡(Λ c ⁢(2625) + )<0.52 MeV/c 2 at 90% confidence level. Based on a full Dalitz plot fit, branching ratios with respect to the mode Λ c⁢ (2625) + →Λ$^{+}_{c}$π + ⁢π - are measured to be $\frac{\mathscr{B}⁡(Λ_c(2625)^+ → Σ^{0}_{c}π^+)} {\mathscr{B}⁡(Λ_c(2625)^+ → ^{+}_{c}⁢π^+⁢π^-)}$ = (5.19±0.23±0.40)% and $\frac{\mathscr{B}(Λ_c (2625)^+ → Σ{_c^+}^+ π^-)}{\mathscr{B}(Λ_c (2625)^+ → Λ{_c^+} π^+π^-)}$ = (5.13±0.26±0.32)%, where the first and second uncertainties are statistical and systematic, respectively. These measurements can be used to further constrain the parameters of the underlying theoretical models.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗