Engineering topics

Kovalenko, E. (ORCID:0000000180841931)

Publications and source records attributed to Kovalenko, E. (ORCID:0000000180841931).

At least 37 records · Page 2

DOE OSTI2023

Study of the lineshape of X ( 3872 ) using B decays to D 0 D ¯ * 0 K

We present a study of the X⁡(3872) lineshape in the decay B →X(3872)⁢K →D 0 $\overline{D}$ *0 ⁢K using a data sample of 772 ×10 6 B$\overline{B}$ pairs collected at the Y⁡(4⁢S) resonance with the Belle detector at the KEKB asymmetric-energy e +⁢ e - collider. The peak near the threshold in the D 0 $\overline{D}$ *0 invariant mass spectrum is fitted using a relativistic Breit-Wigner lineshape. We determine the mass and width parameters to be m BW =3873.7⁢1$^{+0.56}_{-0.50⁢}$(stat) ±0.13⁢(syst) MeV/c 2 and Γ BW =5.2$^{+2.2}_{-1.5}$⁢(stat) ±0.4⁢(syst) MeV, respectively. The branching fraction is found to be $\mathscr{B}$⁡(B + → X⁡(3872)⁢K + ) × $\mathscr{B}$⁡(X⁡(3872) → D 0 $\overline{D}$ *0 ) = (0.9⁢7$^{+0.21}_{-0.18}$⁢(stat) ± 0.10⁢(syst)) ×10 -4 . The signal from B 0 decays is observed for the first time with 5.2σ significance, and the ratio of branching fractions between charged and neutral B decays is measured to be $\mathscr{B}$(B 0 → X⁡(3872)⁢K 0 )/$\mathscr{B}$⁡(B + →X⁡(3872)⁢K + ) =1.34$^{+0.47}_{-0.40}$⁢(stat) $^{+0.10}_{-0.12}$⁢(syst). The peak is also studied using a Flatté lineshape. We determine the lower limit on the D 0 $\overline{D}$ * coupling constant g to be 0.075 at 95% credibility in the parameter region where the ratio of g to the mass difference from the D 0 $\overline{D}$ *0 threshold is equal to -15.11 GeV -1 , as measured by LHCb.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

Search for the Lepton Flavor Violating Decays B + → K + τ ± ℓ ∓ ( ℓ = e , μ ) at Belle

We present a search for the lepton flavor violating decays B + → K + ⁢$\tau$ ±⁢ ℓ ∓ , with ℓ = (e,μ), using the full data sample of 772×10 6 B$\overline{B}$ pairs recorded by the Belle detector at the KEKB asymmetric-energy e + ⁢e - collider. We use events in which one B meson is fully reconstructed in a hadronic decay mode. We find no evidence for B ± → K ±⁢ $\tau$⁢ℓ decays and set upper limits on their branching fractions at the 90% confidence level in the (1 - 3) × 10 -5 range. The obtained limits are the world’s best results.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

First observation of B → $\bar{D}$ 1 (→ $\bar{D}$ π + π - ) $\ell$ + ν $\ell$ and measurement of the B → $\bar{D}$ () π$\ell$ + ν $\ell$ and B → $\bar{D}$ () π + π - $\ell$+ ν $\ell$ branching fractions with hadronic tagging at Belle

We report measurements of the ratios of branching fractions for B → $\bar{D}$(*) π$\ell$+ v $\ell$ and B → $\bar{D}$(*)π + π - $\ell$ + v $\ell$ relative to B → $\bar{D}$*$\ell$ + v $\ell$ decays with $\ell$ = e, μ. These results are obtained from a data sample that contains 772 × 10 6 $B\bar{B}$ pairs collected near the $\Upsilon$(4S) resonance with the Belle detector at the KEKB asymmetric energy e + e - collider.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2023

First Measurement of the B + → π + π 0 π 0 Branching Fraction and C P Asymmetry

We study B + → π + π 0 π 0 using 711 fb -1 of data collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e + e - collider. Here we measure an inclusive branching fraction of (19.0 ±1.5 ±1.4)×10 -6 and an inclusive CP asymmetry of (9.2 ±6.8 ±0.7)%, where the first uncertainties are statistical and the second are systematic, and a B + → ρ(770) + π 0 branching fraction of (11.2 ± 1.1 ± 0.9 $^{+0.8}_{-1.6}$)× 10 -6 , where the third uncertainty is due to possible interference with B + → ρ(1450) + π 0 . We present the first observation of a structure around 1 GeV/c 2 in the π 0 π 0 mass spectrum, with a significance of 6.4σ, and measure a branching fraction to be (6.9 ±0.9 ±0.6) × 10 -6 . We also report a measurement of local CP asymmetry in this structure.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

Study of e + e - → Σ 0 Σ ¯ 0 and Σ + Σ ¯ - by initial state radiation method at Belle

The processes e + ⁢e - →Σ 0 ⁢$\overline{Σ}$ 0 and e + ⁢e - →Σ + ⁢$\overline{Σ}$ - are studied using initial-state-radiation events in a sample of 980 fb -1 collected with the Belle detector at the KEKB asymmetric-energy e + ⁢e - collider. The cross sections from the mass threshold to 3 GeV/c 2 and the effective form factors of Σ 0 and Σ + are measured. In the charmonium region, we observe the decays J/ψ →Σ 0 ⁢$\overline{Σ}$ 0 and J/ψ →Σ + ⁢$\overline{Σ}$ - and determine the respective branching fractions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

First Observation of Λπ + and Λπ - Signals near the $\bar{K}$N⁡(I=1) Mass Threshold in Λ$^+_c$ → Λ⁢π + ⁢π + π - Decay

Using the data sample of 980 fb -1 collected with the Belle detector operating at the KEKB asymmetric-energy e + ⁢e - collider, we present the results of an investigation of the Λ⁢π + and Λ⁢π - invariant mass distributions looking for substructure in the decay Λ$^+_c$ → Λ⁢π + π + π - . We find a significant signal in each mass distribution. When interpreted as resonances, we find for the Λπ + (Λ⁢π - ) combination a mass of 1434.3 ± 0.6⁢(stat) ± 0.9⁢(syst) MeV/c 2 [1438.5 ± 0.9⁢(stat) ± 2.5⁢(syst) MeV/c 2 ], an intrinsic width of 11.5 ± 2.8⁢(stat) ± 5.3⁢(syst) MeV/c 2 [33.0 ± 7.5⁢(stat) ± 23.6⁢(syst) MeV/c 2 ] with a significance of 7.5⁢σ (6.2⁢σ). As these two signals are very close to the $\bar{K}N$ threshold, we also investigate the possibility of a $\bar{K}N$ cusp, and find that we cannot discriminate between these two interpretations due to the limited size of the data sample.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

Search for X ( 3872 ) → π + π - π 0 at Belle

We present a search for the decay X⁡(3872) → π + ⁢π -⁢ π 0 in the (772 ±11) ×10 6 Y⁡(4⁢S)→B⁢$\overline{B}$ data sample collected at the Belle detector, where the X⁡(3872) is produced in B ± → K ± X⁢⁡(3872) and B 0 →K$^{0}_{S}$X(3872) decays. We do not observe a signal, and set 90% credible upper limits for two different models of the decay processes: if the decay products are distributed uniformly in phase space, $\mathscr{B}$⁡(X⁡(3872) → π + ⁢π -⁢ π 0 )<1.3%, and if M⁡(π + ⁢π - ) is concentrated near the mass of the D 0 ⁢$\overline{D}$ 0 pair in the process X⁡(3872) → D 0 ⁢$\overline{D}$ *0 + c.c. → D 0 ⁢$\overline{D}$ 0 ⁢π 0 → π + ⁢π - π 0 , $\mathscr{B}$⁡⁡(X⁡(3872) → π + ⁢π -⁢ π 0 )<1.2×10 -3 .

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

Measurement of the branching fraction and search for CP violation in D 0 → K $^{0}_{S}$ K $^{0}_{S}$ ⁢π + ⁢π - decays at Belle

We measure the branching fraction for the Cabibbo-suppressed decay D 0 → K $^{0}_{S}$ K $^{0}_{S}$ ⁢π + ⁢π - and search for CP violation via a measurement of the CP asymmetry A CP as well as the T-odd triple-product asymmetry a$^{T}_{CP}$. We use 922 fb -1 of data recorded by the Belle experiment, which ran at the KEKB asymmetric-energy e + ⁢e - collider. The branching fraction is measured relative to the Cabibbo-favored normalization channel D 0 → K $^{0}_{S}$ ⁢π + ⁢π - ; the result is $\mathscr{B}$⁡( D 0 → K $^{0}_{S}$ K $^{0}_{S}$ ⁢π + ⁢π - )=[4.79±0.08⁢(stat)±0.10⁢(syst)±0.31⁢(norm)]×10 -4 , where the first uncertainty is statistical, the second is systematic, and the third is from uncertainty in the normalization channel. We also measure A CP =[-2.51±1.44⁢(stat)$^{+0.11}_{-0.10}$⁢(syst)]%, and a$^{T}_{CP}$=[-1.95±1.42⁢(stat)$^{+0.14}_{-0.12}⁢$(syst)]%. These results show no evidence of CP violation.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

Angular analysis of the low K + K – invariant mass enhancement in B + →K + K – π + decays

We study the decay B + →K + K – π + and investigate the angular distribution of K + K – pairs with invariant mass below 1.1 GeV / c 2 . This region exhibits both a strong enhancement in signal and very large direct CP violation. We construct a coherent sum model for the angular distribution of the S- and P-wave, and report the ratio of their amplitudes, the relative phase and the forward-backward asymmetry. We also report absolute differential branching fractions and direct CP asymmetry for the decay in bins of M K+K– and the differential branching fractions in bins of M K+π– . The results are based on a data sample that contains 772 × 10 6 $B\bar{B}$ pairs collected at the $Υ$(4S) resonance with the Belle detector at the KEKB asymmetric-energy e + e – collider. The result favors the presence of S- and D-waves in low M K+K– region to the detriment of a P-wave.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

Measurement of the B + /B 0 production ratio in e + e - collisions at the $\Upsilon$ (4S) resonance using B → J/Ψ($\ell\ell$)K decays at Belle

We measure the ratio of branching fractions for the $\Upsilon$ (4S) decays to B + B - and B 0 $\bar{B}$ 0 using B + → J/Ψ($\ell\ell$)K + and B 0 → J/Ψ($\ell\ell$)K 0 samples, where J/Ψ($\ell\ell$) stands for J/Ψ → $\ell$ + $\ell$ - ($\ell$ = e or μ), with 711 fb -1 of data collected at the $\Upsilon$ (4S) resonance with the Belle detector. We find the decay rate ratio of $\Upsilon$ (4S) → B + B - over $\Upsilon$ (4S) → B 0 $\bar{B}$ 0 to be 1.065 ± 0.012 ± 0.019 ± 0.047, which is the most precise measurement to date. The first and second uncertainties are statistical and systematic, respectively, and the third uncertainty is due to the assumption of isospin symmetry in B → J/Ψ($\ell\ell$) K.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2023

Search for CP violation and measurement of branching fractions and decay asymmetry parameters for Λ$^+_c$ → Λ h + and Λ$^+_c$ → Σ 0 h + ( h = K, π )

Here, we report a study of Λ$^+_c$ → Λ h + and Λ$^+_c$ → Σ 0 h + ( h = K, π ) decays based on a data sample of 980 fb -1 collected with the Belle detector at the KEKB energy-asymmetric e + e - collider. The first results of direct CP asymmetry in two-body singly Cabibbo-suppressed (SCS) decays of charmed baryons are measured, A$^{dir}_{CP}(Λ^+_{c} → ΛK^{+})$ = +0.021 ± 0.026 ± 0.001 and A$^{dir}_{CP}(Λ^+_{c} → Σ^{0}K^{+})$ = +0.025 ± 0.054 ± 0.004. We also make the most precise measurement of the decay asymmetry parameters (α) for the four modes of interest and search for CP violation via the α-induced CP asymmetry (A$^α_{CP}$ ). We measure A$^α_{CP}$ ($Λ^+_{c} → ΛK^{+}$) = -0.023 ± 0.086 ± 0.071 and A$^α_{CP}$ ($Λ^+_{c} → Σ^{0}K^{+}$) = +0.08 ± 0.35 ± 0.14, which are the first A$^α_{CP}$ results for SCS decays of charmed baryons. We search for Λ -hyperon CP violation in $Λ^+_{c}$ → (Λ, Σ 0 )π + and find A$^α_{CP}$(Λ → pπ - ) = +0.013 ± 0.007 ± 0.011 . This is the first time that hyperon CP violation has been measured via Cabibbo-favored charm decays. No evidence of baryon CP violation is found. We also obtain the most precise branching fractions for two SCS Λ$^+_c$ decays, $\mathscr{B}$($Λ^+_{c} → ΛK^{+}$) = (6.57 ± 0.17 ± 0.11 ± 0.35) x 10 -4 and $\mathscr{B}$($Λ^+_{c} → Σ^{0}K^{+}$) = (3.58 ± 0.19 ±0.06 ±0.19) x 10 -4 . The first uncertainties are statistical and the second systematic, while the third uncertainties come from the uncertainties on the world average branching fractions of $Λ^+_{c}$ → (Λ, Σ 0 )π + .

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↗

DOE OSTI2023

Search for rare decays B + → D s ( * ) + η , D s ( * ) + K ¯ 0 , D + η , and D + K 0

We present a study of rare decay modes B + → D$^{+}_{s}$ℎ 0 , B + → D$^{*}_{s}$⁢ + ℎ 0 , and B + → D + ⁢ℎ 0 , where ℎ 0 denotes the neutral meson η or K 0 , using a data sample of (772 ±10) ×10 6 B$\overline{B}$ events produced at the Υ⁡(4⁢S) resonance. The data were collected by the Belle detector operating at the asymmetric-energy KEKB collider. We find no evidence for these decays, so we set upper limits at the 90% confidence level on the branching fractions of , , and D + ⁢ℎ 0 decay modes. Along with these rare decay modes, we report improved measurements of the color-suppressed decay branching fractions $\mathscr{B}$⁡($\overline{B}$ 0 →D 0 ⁢η) =(26.6 ±1.2 ±2.1) ×10 -5 and $\mathscr{B}$⁡($\overline{B}$) 0 →D 0 ⁢ $\overline{K}$ 0 ) =(5.6 ±0.5 ±0.2) ×10 -5 . The first and second quoted uncertainties are statistical and systematic, respectively.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

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

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 .

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