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Kang, K. H. (ORCID:0000000268160751)

Publications and source records attributed to Kang, K. H. (ORCID:0000000268160751).

24 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Measurement of the branching fractions for Cabibbo-suppressed decays D + → K + K - π + π 0 and D ( s ) + → K + π - π + π 0 at Belle

We present measurements of the branching fractions for the singly Cabibbo-suppressed decays and , and the doubly Cabibbo-suppressed decay , based on of data recorded by the Belle experiment at the KEKB e + ⁢e - collider. We measure these modes relative to the Cabibbo-favored modes D + → K - ⁢π + ⁢π + ⁢π 0 and D$^{+}_{s}$ → K + ⁢K -⁢ π + ⁢π 0 . Our results for the ratios of branching fractions are $\mathscr{B}$⁡(D + →K + ⁢K -⁢ π + ⁢π 0 )/$\mathscr{B}$⁡(D + → K - ⁢π + ⁢π + ⁢π 0 ) =(11.32±0.13±0.26)%, $\mathscr{B}$⁡(D + →K + π - ⁢π + ⁢π 0 )/$\mathscr{B}$(D + →K -⁢ π + ⁢π + ⁢π 0 ) =(1.68±0.11±0.03)%, and $\mathscr{B}$⁡(D$^{+}_{s}$ → K + ⁢π - π + ⁢π 0 )/$\mathscr{B}$⁡(D$^{+}_{s}$ → K + ⁢K - π + π 0 ) =(17.13±0.62±0.51)%, where the uncertainties are statistical and systematic, respectively. The second value corresponds to (5.83 ±0.42) ×tan 4 ⁡θ C , where θ C is the Cabibbo angle; this value is larger than other measured ratios of branching fractions for a doubly Cabibbo-suppressed charm decay to a Cabibbo-favored decay. Multiplying these results by world average values for $\mathscr{B}$⁡(D + → K - ⁢π + ⁢π + ⁢π 0 ) and $\mathscr{B}$⁡(D$^{+}_{s}$ → K + ⁢K - π + π 0 ) yields $\mathscr{B}$( + →K + ⁢K -⁢ π + ⁢π 0 ) = (7.08±0.08±0.16±0.20)×10 -3 , $\mathscr{B}$⁡(D + → K +⁢ π - π + ⁢π 0 ) =(1.05±0.07±0.02±0.03)×10 -3 , and $\mathscr{B}$⁡(D$^{+}_{s}$ → K + ⁢π - π + ⁢π 0 ) =(9.44±0.34±0.28±0.32)×10 -3 , where the third uncertainty is due to the branching fraction of the normalization mode. The first two results are consistent with, but more precise than, the current world averages. The last result is the first measurement of this branching fraction.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

First search for the weak radiative decays Λ$^+_c$ → Σ + γ and Ξ$^0_c$ → Ξ 0 γ

We present the first search for the weak radiative decays Λ$^+_c$ → Σ + γ and Ξ$^0_c$ → Ξ 0 γ using a data sample of 980 fb -1 collected by the Belle detector operating at the KEKB asymmetric-energy e + e - collider. There are no evident Λ$^+_c$ → Σ + γ or Ξ$^0_c$ → Ξ 0 γ signals. Taking the decays Λ$^+_c$ → pK - π + and Ξ$^0_c$ → Ξ - π + as normalization channels, the upper limits at 90% credibility level on the ratios of branching fractions $\mathcal{B}$(Λ$^+_c$ → Σ + γ)/$\mathcal{B}$(Λ$^+_c$ → pK - π + ) < 4.0 x 10 -3 and $\mathcal{B}$(Ξ$^0_c$ → Ξ 0 γ)/$\mathcal{B}$(Ξ$^0_c$ → Ξ - π + ) < 1.2 x 10 -2 are determined. We obtain the upper limits at 90% credibility level on the absolute branching fractions $\mathcal{B}$(Λ$^+_c$ → Σ + γ) < 2.6 x 10 -4 and $\mathcal{B}$(Ξ$^0_c$ → Ξ 0 γ) < 1.8 x 10 -4 .

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2023

Study of e + e - → η Φ via initial state radiation at Belle

Using 980 fb -1 of data collected on and around the (n = 1, 2, 3, 4, 5) resonances with the Belle detector at the KEKB collider, we measure the cross section of e + ⁢e - → η⁢Φ from threshold to 3.95 GeV via initial state radiation. There are clear Φ⁡(1680) and J/ψ signals but no significant Φ⁡(2170) signal in the ηΦ final state. The branching fraction $\mathscr{B}$⁡[J/ψ →η⁢Φ] is measured to be (7.2 ±0.8 ±0.5) ×10 -4 . The resonant parameters of Φ⁡(1680) are determined to be m Φ(1680) = (1696±8±10) MeV/c 2 (statistical and systematic errors, respectively), Γ Φ⁡(1680) =(175±13±16) MeV and, depending on the possible presence of predominantly constructive or destructive interference between Φ⁡(1680) and continuum production, Γ$^{e^+e^-}_{Φ⁡(1680)}$·$\mathscr{B}$⁡[Φ⁡(1680)→ηΦ] and $\mathscr{B}$⁡[Φ(1680)→η⁢Φ] are determined to be (75 ±10 ±11) eV and (25±12±2)% or (207±16±20) eV and (23 ±10 ±2)%, respectively. The upper limit for Γ$^{e^+e^-}_{Φ⁡(2170)}$·$\mathscr{B}$⁡[Φ⁡(2170) → ηΦ] is determined to be either 0.17 or 18.6 eV at the 90% confidence level.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Measurements of the branching fractions B ( B ¯ 0 → D * + π - ) and B ( B ¯ 0 → D * + K - ) and tests of QCD factorization

Using (771.6 ± 10.6) × 10 6 $B\overline{B}$ meson pairs recorded by the Belle experiment at the KEKB e + e - collider, we report the branching fractions $\mathscr{B}$($\overline{B}$ 0 → D* + π - ) = (2.62 ± 0.02 ± 0.09 X 10 -3 and $\mathscr{B}$($\overline{B}$ 0 → D* + K - ) = (2.22 ± 0.06 ± 0.08) × 10 -4 ; the quoted uncertainties are statistical and systematic, respectively. A measurement of the ratio of these branching fractions is also presented, R K/π = $\mathscr{B}$($\overline{B}$ → D* + K - )/ $\mathscr{B}$($\overline{B}$ → D* + π - ) = (8.41 ± 0.24 ± 0.13) × 10 -2 , where systematic uncertainties due to the D* + meson reconstruction cancel out. Furthermore, we report a new QCD factorization test based on the measured ratios for $\overline{B}$ → D* + h - and $\overline{B}$ → D* + ℓ - $v$ decays at squared momentum transfer values equivalent to the mass of the h = π or K hadron. The parameters |a 1 (h)| are measured to be |a 1 (π)| = 0.884 ± 0.004 ± 0.003 ± 0.016 and |a 1 (K)| = 0.913 ± 0.019 ± 0.008 ± 0.013, where the last uncertainties account for all external inputs. These values are approximately 15% lower than those expected from theoretical predictions. Subsequently, flavor SU(3) symmetry is tested by measuring the ratios for pions and kaons, |a 1 (K)| 2 /|a 1 (π) 2 | = 1.066 ± 0.042 ± 0.018 ± 0.023, as well as for different particle species. The ratio is consistent with unity and therefore no evidence for SU(3) symmetry breaking effects is found at the 5% precision level.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗