Engineering topics

Fu, C. D.

Publications and source records attributed to Fu, C. D..

31 records · Page 2

DOE OSTI2025

Measurement of the branching fractions of the decays Λ c + → Λ K S 0 K + , Λ c + → Λ K S 0 π + , and Λ c + → Λ K * +

Studies are performed of the Cabibbo-favored decay Λ c + → Λ K S 0 K + and the singly Cabibbo-suppressed decay Λ c + → Λ K S 0 π + , based on a sample of e + e − collision data, corresponding to an integrated luminosity of 4.5 fb − 1 , accumulated at center-of-mass energies between 4599.53 MeV and 4698.82 MeV with the BESIII detector. The decay Λ c + → Λ K S 0 π + is observed for the first time. The branching fractions of Λ c + → Λ K S 0 K + and Λ c + → Λ K S 0 π + are measured to be ( 3.04 ± 0.30 ± 0.16 ) × 10 − 3 and ( 1.73 ± 0.27 ± 0.10 ) × 10 − 3 , respectively, where the first uncertainties are statistical and the second are systematic. These results correspond to the most precise measurement of these quantities for both decays. Evidence of a K * + contribution in the Λ c + → Λ K S 0 π + decay is found with a statistical significance of 4.71 σ . The branching fraction of Λ c + → Λ K * + is calculated under three possible interference scenarios, with the significance increasing to 5.03 σ when interference is taken into account. Published by the American Physical Society 2025

Ablikim, M.↗

DOE OSTI2025

Search for a massless dark photon in c → u γ ′ decays

Using 7.9 f b − 1 of e + e − collision data collected at s = 3.773 GeV with the BESIII detector at the BEPCII collider, we search for the massless dark photon with the flavor-changing neutral current processes D 0 → ω γ ′ and D 0 → γ γ ′ for the first time. No significant signals are observed, and the upper limits at the 90% confidence level on the massless dark photon branching fraction are set to be 1.1 × 10 − 5 and 2.0 × 10 − 6 for D 0 → ω γ ′ and D 0 → γ γ ′ , respectively. These results provide the most stringent constraint on the new physics energy scale associated with c u γ ′ coupling in the world, with the new physics energy scale related parameter | C | 2 + | C 5 | 2 < 8.2 × 10 − 17 GeV − 2 at the 90% confidence level. Published by the American Physical Society 2025

Ablikim, M.↗

DOE OSTI2025

Study of D s + → f 0 ( 980 ) ρ + and ϕ π + Decays through D s + → π + π + π − π 0

We perform the first amplitude analysis of D s + → π + π + π − π 0 decays based on data samples of electron-positron collisions recorded with the BESIII detector at center-of-mass energies between 4.128 and 4.226 GeV, corresponding to an integrated luminosity of 7.33 fb − 1 . We report the observation of D s + → f 0 ( 980 ) ρ ( 770 ) + with a statistical significance greater than 10 σ and determine the branching fractions B ( D s + → π + π + π − π 0 | non − η ) = ( 2.04 ± 0.0 8 stat ± 0.0 5 syst ) % and B ( D s + → η π + ) = ( 1.56 ± 0.0 9 stat ± 0.0 4 syst ) % . Moreover, we measure the relative branching fraction between ϕ → π + π − π 0 and ϕ → K + K − to be [ B ( ϕ ( 1020 ) → π + π − π 0 ) / B ( ϕ ( 1020 ) → K + K − ) ] = 0.230 ± 0.01 4 stat ± 0.01 0 syst ., which deviates from the world average value by more than 4 σ . Published by the American Physical Society 2025

Ablikim, M.↗

DOE OSTI2024

Study of the decay D 0 → ρ ( 770 ) − e + ν e

We present a study of the semileptonic decay D 0 → π − π 0 e + ν e using an e + e − annihilation data sample of 7.93 fb − 1 collected at the center-of-mass energy of 3.773 GeV with the BESIII detector. The branching fraction of D 0 → ρ ( 770 ) − e + ν e is measured to be ( 1.439 ± 0.033 ( stat ) ± 0.027 ( syst ) ) × 10 − 3 , which is a factor 1.6 more precise than previous measurements. By performing an amplitude analysis, we measure the hadronic form-factor ratios of D 0 → ρ ( 770 ) − e + ν e at q 2 = 0 assuming the single-pole-dominance parametrization: r V = V ( 0 ) / A 1 ( 0 ) = 1.548 ± 0.079 ( stat ) ± 0.041 ( syst ) and r 2 = A 2 ( 0 ) / A 1 ( 0 ) = 0.823 ± 0.056 ( stat ) ± 0.026 ( syst ) . Published by the American Physical Society 2024

Ablikim, M.↗

DOE OSTI2024

Observation of D → a 0 ( 980 ) π in the decays D 0 → π + π − η and D + → π + π 0 η

We report the first amplitude analyses of the decays D 0 → π + π − η and D + → π + π 0 η using a data sample taken with the BESIII detector at the center-of-mass energy of 3773 MeV, corresponding to an integrated luminosity of 7.9 fb − 1 . The contribution from the process D 0 ( + ) → a 0 ( 980 ) + π − ( 0 ) is significantly larger than the D 0 ( + ) → a 0 ( 980 ) − ( 0 ) π + contribution. The ratios B ( D 0 → a 0 ( 980 ) + π − ) / B ( D 0 → a 0 ( 980 ) − π + ) and B ( D + → a 0 ( 980 ) + π 0 ) / B ( D + → a 0 ( 980 ) 0 π + ) are measured to be 7.5 − 0.8 stat + 2.5 ± 1.7 syst and 2.6 ± 0.6 stat ± 0.3 syst , respectively. The measured D 0 ratio disagrees with the theoretical predictions by orders of magnitudes, thus implying a substantial contribution from final-state interactions. Published by the American Physical Society 2024

Ablikim, M.↗

DOE OSTI2024

Precise Measurement of the e + e − → D s + D s − Cross Section at Center-of-Mass Energies from Threshold to 4.95 GeV

Using the e + e − collision data collected with the BESIII detector operating at the BEPCII collider, at center-of-mass energies from the threshold to 4.95 GeV, we present precise measurements of the cross section for the process e + e − → D s + D s − using a single-tag method. The resulting cross section line shape exhibits several new structures, thereby offering an input for a future coupled-channel analysis and model tests, which are critical to understand vector charmonium-like states with masses between 4 and 5 GeV. Published by the American Physical Society 2024

Ablikim, M.↗

DOE OSTI2024

Study of the decay J / ψ → ϕ π 0 η

Based on ( 10.09 ± 0.04 ) × 10 9 J / ψ events collected with the BESIII detector operating at the BEPCII collider, a partial wave analysis of the decay J / ψ → ϕ π 0 η is performed. We observe for the first time two new structures on the ϕ η invariant mass distribution, with significances exceeding 27 σ and 13 σ ; the first with J PC = 1 + − , mass M = ( 1908 ± 6 ( stat ) − 4 + 8 ( sys ) ) MeV / c 2 , and width Γ = ( 175 ± 13 ( stat ) − 16 + 7 ( sys ) ) MeV , the second with J PC = 1 − − , mass M = ( 1992 ± 12 ( stat ) − 6 + 15 ( sys ) ) MeV / c 2 , and width Γ = ( 132 ± 22 ( stat ) − 4 + 17 ( sys ) ) MeV . These measurements provide important input for the strangeonium spectrum. In addition, the f 0 ( 980 ) − a 0 ( 980 ) 0 mixing signal in J / ψ → ϕ f 0 ( 980 ) → ϕ a 0 ( 980 ) 0 and the corresponding electromagnetic decay J / ψ → ϕ a 0 ( 980 ) 0 are measured with improved precision, providing crucial information to understand the nature of a 0 ( 980 ) 0 and f 0 ( 980 ) . Published by the American Physical Society 2024

Ablikim, M.↗

DOE OSTI2024

Observation of χ c 0 → Σ + Σ ¯ − η and evidence for χ c 1 , 2 → Σ + Σ ¯ − η

Using ( 27.12 ± 0.14 ) × 10 8 ψ ( 3686 ) events collected with the BESIII detector, the decay χ c 0 → Σ + Σ ¯ − η is observed for the first time with a signal significance of 7.0 σ , and evidence for χ c 1 → Σ + Σ ¯ − η and χ c 2 → Σ + Σ ¯ − η is found with signal significances of 4.3 σ and 4.6 σ , respectively. The branching fractions are determined to be B ( χ c 0 → Σ + Σ ¯ − η ) = ( 1.26 ± 0.20 ± 0.13 ) × 10 − 4 , B ( χ c 1 → Σ + Σ ¯ − η ) = ( 5.10 ± 1.21 ± 0.67 ) × 10 − 5 , and B ( χ c 2 → Σ + Σ ¯ − η ) = ( 5.46 ± 1.18 ± 0.50 ) × 10 − 5 , where the first uncertainties are statistical, and the second ones are systematic. Published by the American Physical Society 2024

Ablikim, M.↗

DOE OSTI2024

Observation of χ c J → p p ¯ K S 0 K − π + + c . c .

By analyzing ( 27.12 ± 0.14 ) × 10 8 ψ ( 3686 ) events collected with the BESIII detector operating at the BEPCII collider, the decays χ c J → p p ¯ K S 0 K − π + + c . c . ( J = 0 , 1 , 2 ) are observed for the first time with statistical significances greater than 10 σ . The branching fractions of these decays are determined to be B ( χ c 0 → p p ¯ K S 0 K − π + + c . c . ) = ( 2.61 ± 0.27 ± 0.32 ) × 10 − 5 , B ( χ c 1 → p p ¯ K S 0 K − π + + c . c . ) = ( 4.16 ± 0.24 ± 0.46 ) × 10 − 5 , and B ( χ c 2 → p p ¯ K S 0 K − π + + c . c . ) = ( 5.63 ± 0.28 ± 0.46 ) × 10 − 5 , respectively. The processes χ c 1 , 2 → p ¯ Λ ( 1520 ) K S 0 π + + c . c . are also observed, with statistical significances of 5.7 σ and 7.0 σ , respectively. Evidence for χ c 0 → p ¯ Λ ( 1520 ) K S 0 π + + c . c . is found with statistical significances of 3.3 σ . The corresponding branching fractions are determined to be B ( χ c 0 → p ¯ Λ ( 1520 ) K S 0 π + + c . c . ) = ( 1.6 1 − 0.64 + 0.68 ± 0.23 ) × 10 − 5 , B ( χ c 1 → p ¯ Λ ( 1520 ) K S 0 π + + c . c . ) = ( 4.06 − 0.76 + 0.80 ± 0.52 ) × 10 − 5 , and B ( χ c 2 → p ¯ Λ ( 1520 ) K S 0 π + + c . c . ) = ( 4.0 9 − 0.84 + 0.87 ± 0.42 ) × 10 − 5 . Here, the first uncertainties are statistical and the second ones are systematic. Published by the American Physical Society 2024

Ablikim, M.↗

DOE OSTI2024

Search for h c → π + π − J / ψ via ψ ( 3686 ) → π 0 h c

Using ( 2712.4 ± 14.3 ) × 10 6 ψ ( 3686 ) events collected with the BESIII detector operating at the BEPCII collider, we search for the hadronic transition h c → π + π − J / ψ via ψ ( 3686 ) → π 0 h c . No significant signal is observed. We set the most stringent upper limits to date on the branching fractions B ( ψ ( 3686 ) → π 0 h c ) × B ( h c → π + π − J / ψ ) and B ( h c → π + π − J / ψ ) at the 90% confidence level, which are determined to be 6.7 × 10 − 7 and 9.4 × 10 − 4 , respectively. Published by the American Physical Society 2024

Ablikim, M.↗

DOE OSTI2024

R ( 3780 ) Resonance Interpreted as the 1 D 1 3 -Wave Dominant State of Charmonium from Precise Measurements of the Cross Section of e + e − → Hadrons

We report the precise measurements of the cross section of e + e − → hadrons at center-of-mass energies from 3.645 to 3.871 GeV. We thereby perform the most precise study of the cross sections and find a complex system composed of three resonances of R ( 3760 ) , R ( 3780 ) , and R ( 3810 ) . For the first time, we measure the R ( 3810 ) electronic width to be ( 19.4 ± 7.4 ± 12.1 ) eV . For the R ( 3760 ) resonance, we measure the mass to be ( 3751.9 ± 3.8 ± 2.8 ) MeV / c 2 , the total width to be ( 32.8 ± 5.8 ± 8.7 ) MeV , and the electronic width to be ( 184 ± 75 ± 86 ) eV . For the R ( 3780 ) resonance, we measure its mass to be ( 3778.7 ± 0.5 ± 0.3 ) MeV / c 2 , total width to be ( 20.3 ± 0.8 ± 1.7 ) MeV , and electronic width to be ( 265 ± 67 ± 83 ) eV . Forty-seven years ago, the ψ ( 3770 ) resonance was discovered, and was subsequently interpreted as the 1 D 1 3 -wave dominant state of charmonium. However, our analysis of the total-hadron cross sections indicates that the ψ ( 3770 ) is not a single state, but a complex system composed of the R ( 3760 ) , R ( 3780 ) , and R ( 3810 ) resonances. Among these, we interpret the R ( 3780 ) is a resonance dominated by the 1 D 1 3 charmonium state. Published by the American Physical Society 2024

Ablikim, M.↗

DOE OSTI2024

Model-independent determination of the strong-phase difference between D 0 and D ¯ 0 → π + π − π + π − decays

Measurements of the strong-phase difference between D 0 and D ¯ 0 → π + π − π + π − are performed in bins of phase space. The study exploits a sample of quantum-correlated D D ¯ mesons collected by the BESIII experiment in e + e − collisions at a center-of-mass energy of 3.773 GeV, corresponding to an integrated luminosity of 2.93 fb − 1 . Here, D denotes a neutral charm meson in a superposition of flavor eigenstates. The reported results are valuable for measurements of the C P -violating phase γ (also denoted ϕ 3 ) in B ± → D K ± , D → π + π − π + π − decays, and the binning schemes are designed to provide good statistical sensitivity to this parameter. The expected uncertainty on γ arising from the precision of the strong-phase measurements, when applied to very large samples of B -meson decays, is around 1.5° or 2°, depending on the binning scheme. The binned strong-phase parameters are combined to give a value of F + 4 π = 0.746 ± 0.010 ± 0.004 for the C P -even fraction of D 0 → π + π − π + π − decays, which is around 30% more precise than the previous best measurement of this quantity. Published by the American Physical Society 2024

Ablikim, M.↗

DOE OSTI2024

Search for D 0 → K − η e + ν e , D + → K S 0 η e + ν e and D + → η η e + ν e decays

By analyzing e + e − annihilation data corresponding to an integrated luminosity of 7.93 fb − 1 , collected at the center-of-mass energy of 3.773 GeV with the BESIII detector, we search for the semileptonic decays D 0 → K − η e + ν e , D + → K S 0 η e + ν e and D + → η η e + ν e for the first time. We present evidence for D 0 → K − η e + ν e with a significance of 3.3 σ . The branching fraction of D 0 → K − η e + ν e is measured to be ( 0.8 4 − 0.34 + 0.29 ± 0.22 ) × 10 − 4 . No significant signals are observed for the decays D + → K S 0 η e + ν e and D + → η η e + ν e and we set the upper limits on their branching fractions. Published by the American Physical Society 2024

Ablikim, M.↗