Engineering topics

Behera, P. (ORCID:0000000215272266)

Publications and source records attributed to Behera, P. (ORCID:0000000215272266).

43 records · Page 3

DOE OSTI2023

Measurement of branching fractions of Λ$^+_c$ → p⁢K$^0_S$K$^0_S$ and Λ$^+_c$ → p⁢K$^0_S$⁢η at Belle

We present a study of a singly Cabibbo-suppressed decay Λ$^+_c$ → p⁢K$^0_S$K$^0_S$ and a Cabibbo-favored decay Λ$^+_c$ → p⁢K$^0_S$⁢η based on 980 fb -1 of data collected by the Belle detector, operating at the KEKB energy-asymmetric e + ⁢e - collider. We measure their branching fractions relative to Λ$^+_c$ → p⁢K$^0_S$: $\mathscr{B}$(Λ$^+_c$ → p⁢K$^0_S$K$^0_S$)/$\mathscr{B}$(Λ$^+_c$ → p⁢K$^0_S$) = (1.48 ± 0.08 ± 0.04) × 10 -2 and $\mathscr{B}$(Λ$^+_c$ → p⁢K$^0_S$η)/$\mathscr{B}$(Λ$^+_c$ → p⁢K$^0_S$) = (2.73 ± 0.06 ± 0.13) × 10 -1 . Combining with the world average $\mathscr{B}$(Λ$^+_c$ → p⁢K$^0_S$), we have the absolute branching fractions, $\mathscr{B}$(Λ$^+_c$ → p⁢K$^0_S$K$^0_S$) = (2.35 ± 0.12 ± 0.07 ± 0.12) × 10 -4 and $\mathscr{B}$(Λ$^+_c$ → p⁢K$^0_S$η) = (4.35 ± 0.10 ± 0.20 ± 0.22) × 10 -3 . The first and second uncertainties are statistical and systematic, respectively, while the third ones arise from the uncertainty on $\mathscr{B}$(Λ$^+_c$ → p⁢K$^0_S$). The mode Λ$^+_c$ → p⁢K$^0_S$K$^0_S$ is observed for the first time and has a statistical significance of >10σ. The branching fraction of Λ$^+_c$ → p⁢K$^0_S$η has been measured with a threefold improvement in precision over previous results and is found to be consistent with the world average.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2023

Measurement of the branching fraction of Ξ c 0 → Λ c + π - at Belle

Based on a data sample of 983 fb -1 collected with the Belle detector at the KEKB asymmetric-energy e + ⁢e - collider, we present the study of the heavy-flavor-conserving decay Ξ$^{0}_{c}$ → Λ$^{+}_{c}$⁢π - with Λ$^{+}_{c}$ reconstructed via its p⁢K - π + decay mode. The branching fraction ratio $\mathscr{B}$⁡(Ξ$^{0}_{c}$ → Λ$^{+}_{c}$⁢π - )/$\mathscr{B}$⁡(Ξ$^{0}_{c}$ → Ξ - π + ) is measured to be 0.38 ±0.04 ±0.04. Combining with the world average value of $\mathscr{B}$(Ξ$^{0}_{c}$ → Ξ - π + ), the branching fraction $\mathscr{B}$⁡(Ξ$^{0}_{c}$ → Λ$^{+}_{c}$⁢π - ) is deduced to be (0.54 ±0.05 ±0.05 ±0.12)%. Here, the uncertainties above are statistical, systematic, and from $\mathscr{B}$⁡(Ξ$^{0}_{c}$ → Ξ - π + ), respectively.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

Measurements of branching fractions of Λ$^{+}_{c}$ → Σ + ⁢η and Λ$^{+}_{c}$ → Σ + ⁢η' and asymmetry parameters of Λ$^{+}_{c}$ → Σ + ⁢π 0 , Λ$^{+}_{c}$ → Σ + ⁢η, and Λ$^{+}_{c}$ → Σ + ⁢η'

We report a study of Λ c + → Σ + π 0 , Λ c + → Σ + η , and Λ c + → Σ + η ' using the data sample corresponding to an integrated luminosity of 980 fb - 1 collected with the Belle detector at the KEKB asymmetric-energy e + e - collider. The branching fractions relative to Λ c + → Σ + π 0 are measured as B Λ c + → Σ + η / B Λ c + → Σ + π 0 = 0.25 ± 0.03 ± 0.01 and B Λ c + → Σ + η ' / B Λ c + → Σ + π 0 = 0.33 ± 0.06 ± 0.02 . Using B Λ c + → Σ + π 0 = ( 1.25 ± 0.10 ) % , we obtain B Λ c + → Σ + η = ( 3.14 ± 0.35 ± 0.17 ± 0.25 ) × 10 - 3 and B Λ c + → Σ + η ' = ( 4.16 ± 0.75 ± 0.25 ± 0.33 ) × 10 - 3 . Here the uncertainties are statistical, systematic, and from B Λ c + → Σ + π 0 , respectively. The ratio of the branching fraction of Λ c + → Σ + η ' with respect to that of Λ c + → Σ + η is measured to be B Λ c + → Σ + η ' / B Λ c + → Σ + η = 1.34 ± 0.28 ± 0.08 . We update the asymmetry parameter of Λ c + → Σ + π 0 , α Σ + π 0 = - 0.48 ± 0.02 ± 0.02 , with a considerably improved precision. The asymmetry parameters of Λ c + → Σ + η and Λ c + → Σ + η ' are measured to be α Σ + η = - 0.99 ± 0.03 ± 0.05 and α Σ + η ' = - 0.46 ± 0.06 ± 0.03 for the first time.

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↗

DOE OSTI2023

Evidence of a New Excited Charmed Baryon Decaying to Σ c ( 2455 ) 0 , + + π ±

We present the study of $\overline{B}$ 0 →Σ c ⁢(2455) 0,++ ⁢π ± $\overline{p}$ decays based on 772×10 6 B$\overline{B}$ events collected with the Belle detector at the KEKB asymmetric-energy e + ⁢e - collider. The Σ c⁢ (2455) 0,++ candidates are reconstructed via their decay to Λ$^{+}_{c}$π ∓ and Λ$^{+}_{c}$ decays to pK ⁢- π + , pK$^{0}_{S}$, and Λ⁢π + final states. The corresponding branching fractions are measured to be $\mathscr{B}$⁡($\overline{B}$ 0 →Σ c ⁢(2455) 0⁢ π + $\overline{p}$)=(1.09±0.06±0.07)×10 -4 and $\mathscr{B}$⁡($\overline{B}$ 0 →Σ c ⁢(2455) ++ ⁢π - ⁢$\overline{p}$)=(1.84±0.11±0.12)×10 -4 , which are consistent with the world average values with improved precision. A new structure is found in the M Σ c (2455) 0,++⁢π± spectrum with a significance of 4.2⁢σ including systematic uncertainty. The structure is possibly an excited Λ$^{+}_{c}$ and is tentatively named Λ c ⁢(2910) + . Its mass and width are measured to be (2913.8±5.6±3.8) MeV/c 2 and (51.8±20.0±18.8) MeV, respectively. The products of branching fractions for the Λ c ⁢(2910) + are measured to be $\mathscr{B}$⁡($\overline{B}$ 0 →Λ c (2910) + $\overline{p}$) × $\mathscr{B}$⁡(Λ c ⁢(2910) + →Σ c ⁢(2455) 0 π + )=(9.5±3.6±1.6) x 10 -6 and $\mathscr{B}$($\overline{B}$ 0 →Λ c ⁢(2910) + ⁢ $\overline{p}$) × $\mathscr{B}$⁡(Λ c (2910) + →Σ c (2455 )++ π - )=(1.24±0.35±0.10)×10 -5 . Here, the first and second uncertainties are statistical and systematic, respectively.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗