Engineering topics

Chen, H. Y.

Publications and source records attributed to Chen, H. Y..

At least 55 records · Page 3

DOE OSTI2024

Search for e + e − → η ′ ψ ( 2 S ) at center-of-mass energies from 4.66 to 4.95 GeV

Using data samples with an integrated luminosity of 4.67 fb − 1 collected by the BESIII detector operating at the BEPCII Collider, we search for the process e + e − → η ′ ψ ( 2 S ) at center-of-mass energies from 4.66 to 4.95 GeV. No significant signal is observed, and upper limits for the Born cross sections σ B ( e + e − → η ′ ψ ( 2 S ) ) at the 90% confidence level are determined. Published by the American Physical Society 2024

Astronomy & Astrophysics↗

DOE OSTI2024

Measurement of the e + e − → p p ¯ π 0 cross section at s = 2.1000 − 3.0800 GeV

The process e + e − → p p ¯ π 0 is studied at 20 center-of-mass energies ranging from 2.1000 to 3.0800 GeV using 636.8 pb − 1 of data collected with the BESIII detector operating at the BEPCII collider. The Born cross sections for e + e − → p p ¯ π 0 are measured with high precision. Since the lowest center-of-mass energy, 2.1000 GeV, is less than 90 MeV above the p p ¯ π 0 energy threshold, we can probe the threshold behavior for this reaction. However, no anomalous threshold enhancement is found in the cross sections for e + e − → p p ¯ π 0 . Published by the American Physical Society 2024

Astronomy & Astrophysics↗

DOE OSTI2024

Search for X ( 1870 ) via the decay J / ψ → ω K + K − η

Using a sample of ( 10087 ± 44 ) × 10 6 J / ψ events collected by the BESIII detector at the BEPCII collider, we search for the decay X ( 1870 ) → K + K − η via the J / ψ → ω K + K − η process for the first time. No significant X ( 1870 ) signal is observed. The upper limit on the branching fraction of the decay J / ψ → ω X ( 1870 ) → ω K + K − η is determined to be 9.55 × 10 − 7 at the 90% confidence level. In addition, the branching faction B ( J / ψ → ω K + K − η ) is measured to be ( 3.33 ± 0.02 ( stat ) ± 0.12 ( syst ) ) × 10 − 4 . Published by the American Physical Society 2024

Astronomy & Astrophysics↗

DOE OSTI2024

Measurement of the branching fraction of D s + → ℓ + ν ℓ via e + e − → D s * + D s * −

Based on 10.64 fb − 1 of e + e − collision data taken at center-of-mass energies between 4.237 and 4.699 GeV with the BESIII detector, we study the leptonic D s + decays using the e + e − → D s * + D s * − process. The branching fractions of D s + → ℓ + ν ℓ ( ℓ = μ , τ ) are measured to be B D s + → μ + ν μ = ( 0.547 ± 0.02 6 stat ± 0.01 6 syst ) % and B D s + → τ + ν τ = ( 5.60 ± 0.1 6 stat ± 0.2 0 syst ) % , respectively. The product of the decay constant and Cabibbo-Kobayashi-Maskawa matrix element | V c s | is determined to be f D s + | V c s | = ( 246.5 ± 5.9 stat ± 3.6 syst ± 0.5 input ) μ ν and f D s + | V c s | = ( 252.7 ± 3.6 stat ± 4.5 syst ± 0.6 input ) τ ν MeV , respectively. Taking the value of | V c s | from a global fit in the Standard Model, we obtain f D s + = ( 253.2 ± 6.0 stat ± 3.7 syst ± 0.6 input ) μ ν and f D s + = ( 259.6 ± 3.7 stat ± 4.6 syst ± 0.6 input ) τ ν MeV , respectively. Conversely, taking the value for f D s + from the latest lattice quantum chromodynamics calculation, we obtain | V c s | = ( 0.986 ± 0.02 3 stat ± 0.01 4 syst ± 0.00 3 input ) μ ν and | V c s | = ( 1.011 ± 0.01 4 stat ± 0.01 8 syst ± 0.00 3 input ) τ ν , respectively. Published by the American Physical Society 2024

Astronomy & Astrophysics↗

DOE OSTI2024

Strong and Weak C P Tests in Sequential Decays of Polarized Σ 0 Hyperons

The J / ψ , ψ ( 3686 ) → Σ 0 Σ ¯ 0 processes and subsequent decays are studied using the world’s largest J / ψ and ψ ( 3686 ) data samples collected with the BESIII detector. The parity-violating decay parameters of the decays Σ 0 → Λ γ and Σ ¯ 0 → Λ ¯ γ , α Σ 0 = − 0.0017 ± 0.0021 ± 0.0018 and α ¯ Σ 0 = 0.0021 ± 0.0020 ± 0.0022 , are measured for the first time. The strong C P symmetry is tested in the decays of the Σ 0 hyperons for the first time by measuring the asymmetry A C P Σ = α Σ 0 + α ¯ Σ 0 = ( 0.4 ± 2.9 ± 1.3 ) × 10 − 3 . The weak C P test is performed in the subsequent decays of their daughter particles Λ and Λ ¯ . Also for the first time, the transverse polarizations of the Σ 0 hyperons in J / ψ and ψ ( 3686 ) decays are observed with opposite directions, and the ratios between the S -wave and D -wave contributions of the J / ψ , ψ ( 3686 ) → Σ 0 Σ ¯ 0 decays are obtained. These results are crucial to understand the decay dynamics of the charmonium states and the production mechanism of the Σ 0 − Σ ¯ 0 pairs. Published by the American Physical Society 2024

Physics↗

DOE OSTI2024

Measurements of the branching fractions of the P -wave charmonium spin-singlet state h c ( P 1 1 ) → h + h − π 0 / η

Based on ( 2712.4 ± 14.3 ) × 10 6 ψ ( 3686 ) events, we investigate four hadronic decay modes of the P -wave charmonium spin-singlet state h c ( 1 P 1 ) → h + h − π 0 / η ( h = π or K ) via the process ψ ( 3686 ) → π 0 h c at BESIII. The h c → π + π − π 0 decay is observed with a significance of 9.6 σ after taking into account systematic uncertainties. Evidences for h c → K + K − π 0 and h c → K + K − η are found with significances of 3.5 σ and 3.3 σ , respectively, after considering the systematic uncertainties. The branching fractions of these decays are measured to be B ( h c → π + π − π 0 ) = ( 1.36 ± 0.16 ± 0.14 ) × 10 − 3 , B ( h c → K + K − π 0 ) = ( 3.26 ± 0.84 ± 0.36 ) × 10 − 4 , and B ( h c → K + K − η ) = ( 3.13 ± 1.08 ± 0.38 ) × 10 − 4 , where the first uncertainties are statistical and the second are systematic. No significant signal of h c → π + π − η is found, and the upper limit of its decay branching fraction is determined to be B ( h c → π + π − η ) < 4.0 × 10 − 4 at the 90% confidence level. Published by the American Physical Society 2024

Astronomy & Astrophysics↗

DOE OSTI2024

Study of the decays χ c J → Λ Λ ¯ ω

Using ( 27.12 ± 0.14 ) × 10 8 ψ ( 3686 ) events collected with the BESIII detector, we present the first observation of the decays χ c J → Λ Λ ¯ ω , where J = 0 , 1, 2, with statistical significances of 11.7 σ , 11.2 σ , and 11.8 σ . The branching fractions of these decays are determined to be B ( χ c 0 → Λ Λ ¯ ω ) = ( 2.37 ± 0.22 ± 0.25 ) × 10 − 4 , B ( χ c 1 → Λ Λ ¯ ω ) = ( 1.01 ± 0.10 ± 0.11 ) × 10 − 4 , and B ( χ c 2 → Λ Λ ¯ ω ) = ( 1.40 ± 0.13 ± 0.17 ) × 10 − 4 , where the first uncertainties are statistical and the second are systematic. We observe no clear intermediate structures. Published by the American Physical Society 2024

Astronomy & Astrophysics↗

DOE OSTI2024

Search for C -even states decaying to D s ± D s * ∓ with masses between 4.08 and 4.32 GeV / c 2

Six C -even states, denoted as X , with quantum numbers J P C = 0 − + , 1 ± + , or 2 ± + , are searched for via the e + e − → γ D s ± D s * ∓ process using ( 1667.39 ± 8.84 ) pb − 1 of e + e − collision data collected with the BESIII detector operating at the BEPCII storage ring at center-of-mass energy of s = ( 4681.92 ± 0.30 ) MeV . No statistically significant signal is observed in the mass range from 4.08 GeV / c 2 to 4.32 GeV / c 2 . The upper limits of σ [ e + e − → γ X ] · B [ X → D s ± D s * ∓ ] at a 90% confidence level are determined. Published by the American Physical Society 2024

Astronomy & Astrophysics↗

DOE OSTI2024

Study of the decays χ c J → Λ Λ ¯ ϕ

Based on ( 2712.4 ± 14.3 ) × 10 6 e + e − → ψ ( 3686 ) events collected with the BESIII detector operating at the BEPCII Collider, we report the first evidence of χ c 0 → Λ Λ ¯ ϕ decays and the first observation of χ c 1 , 2 → Λ Λ ¯ ϕ decays, with significances of 4.1 σ , 11.3 σ and 13.0 σ , respectively. The decay branching fractions of χ c 0 , 1 , 2 → Λ Λ ¯ ϕ are measured to be ( 2.99 ± 1.24 ± 0.19 ) × 10 − 5 , ( 6.01 ± 0.90 ± 0.40 ) × 10 − 5 , and ( 7.13 ± 0.81 ± 0.36 ) × 10 − 5 , where the first uncertainties are statistical and the second systematic. No obvious enhancement near the Λ Λ ¯ production threshold or excited Λ state is found in the Λ ϕ (or Λ ¯ ϕ ) system. Published by the American Physical Society 2024

Astronomy & Astrophysics↗

DOE OSTI2024

Search for the e + e − → ϕ χ c 1 ( 3872 ) process at BESIII

Based on 368.5 p b − 1 of e + e − collision data collected at center-of-mass energies 4.914 and 4.946 GeV by the BESIII detector, the e + e − → ϕ χ c 1 ( 3872 ) process is searched for the first time. No significant signal is observed and the upper limits at the 90% confidence level on the product of the Born cross section σ ( e + e − → ϕ χ c 1 ( 3872 ) ) and the branching fraction B [ χ c 1 ( 3872 ) → π + π − J / ψ ] at 4.914 and 4.946 GeV are set to be 0.85 and 0.96 pb, respectively. These measurements provide useful information for the production of the χ c 1 ( 3872 ) at e + e − colliders and deepen our understanding about the nature of this particle. Published by the American Physical Society 2024

Astronomy & Astrophysics↗

DOE OSTI2024

Search for a Sub-eV Sterile Neutrino Using Daya Bay’s Full Dataset

This Letter presents results of a search for the mixing of a sub-eV sterile neutrino with three active neutrinos based on the full data sample of the Daya Bay Reactor Neutrino Experiment, collected during 3158 days of detector operation, which contains 5.55 × 106 reactor $\overline{v}$ e candidates identified as inverse beta-decay interactions followed by neutron capture on gadolinium. The analysis benefits from a doubling of the statistics of our previous result and from improvements of several important systematic uncertainties. No significant oscillation due to mixing of a sub-eV sterile neutrino with active neutrinos was found. Exclusion limits are set by both Feldman-Cousins and CLs methods. Light sterile neutrino mixing with sin 2⁡ 2⁢θ 14 ≳ 0.01 can be excluded at 95% confidence level in the region of 0.01 eV 2 ≲ |Δ⁢$m$$^{2}_{41}$| ≲ 0.1 eV 2 . This result represents the world-leading constraints in the region of 2 × 10 –4 eV 2 ≲ |Δ⁢$m$$^{2}_{41}$| ≲ 0.2 eV 2 .

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2024

Search for the radiative transition χ c 1 ( 3872 ) → γ ψ 2 ( 3823 )

Using 9.0 f b − 1 of e + e − collision data collected at center-of-mass energies from 4.178 to 4.278 GeV with the BESIII detector at the BEPCII collider, we perform the first search for the radiative transition χ c 1 ( 3872 ) → γ ψ 2 ( 3823 ) . No signal is observed and the upper limit on the ratio of branching fractions B ( χ c 1 ( 3872 ) → γ ψ 2 ( 3823 ) , ψ 2 ( 3823 ) → γ χ c 1 ) / B ( χ c 1 ( 3872 ) → π + π − J / ψ ) is set at 0.075 at the 90% confidence level. Our result contradicts theoretical predictions under the assumption that the χ c 1 ( 3872 ) is the pure charmonium state χ c 1 ( 2 P ) . Published by the American Physical Society 2024

Astronomy & Astrophysics↗

DOE OSTI2024

First measurement of the yield of 8 He isotopes produced in liquid scintillator by cosmic-ray muons at Daya Bay

Here, Daya Bay presents the first measurement of cosmogenic 8 He isotope production in liquid scintillator, using an innovative method for identifying cascade decays of 8 He and its child isotope, 8 Li. We also measure the production yield of 9 Li isotopes using well-established methodology. The results, in units of 10 –8 μ –1 ⁢g –1 cm 2 , are 0.307 ± 0.042, 0.341 ± 0.040, and 0.546 ± 0.076 for 8 He, and 6.73 ± 0.73, 6.75 ± 0.70, and 13.74 ± 0.82 for 9 Li at average muon energies of 63.9 GeV, 64.7 GeV, and 143.0 GeV, respectively. The measured production rate of 8 He isotopes is more than an order of magnitude lower than any other measurement of cosmogenic isotope production. It replaces the results of previous attempts to determine the ratio of 8 He to 9 Li production that yielded a wide range of limits from 0% to 30%. The results provide future liquid-scintillator-based experiments with improved ability to predict cosmogenic backgrounds.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2024

Evidence of the h c → K S 0 K + π − + c . c . decay

Based on ( 2.712 ± 0.014 ) × 10 9 ψ ( 3686 ) events collected by the BESIII Collaboration, evidence of the hadronic decay h c → K S 0 K + π − + c . c . is found with a significance of 4.3 σ in the ψ ( 3686 ) → π 0 h c process. The branching fraction of h c → K S 0 K + π − + c . c . is measured to be ( 7.3 ± 1.8 ± 0.8 ) × 10 − 4 , where the first and second uncertainties are statistical and systematic, respectively. Combining with the exclusive decay width of η c → K K ¯ π , our result indicates inconsistencies with both pQCD and NRQCD predictions. Published by the American Physical Society 2024

Ablikim, M.↗

DOE OSTI2024

Study of e + e − → ω X ( 3872 ) and γ X ( 3872 ) from 4.66 to 4.95 GeV

Using data samples with an integrated luminosity of 4.5 fb − 1 collected by the BESIII detector at center-of-mass energies ranging from 4.66 GeV to 4.95 GeV, we study the processes of e + e − → ω X ( 3872 ) and e + e − → γ X ( 3872 ) . With the e + e − → ω X ( 3872 ) process, the branching fraction ratio R ≡ B ( X ( 3872 ) → γ J / ψ ) B ( X ( 3872 ) → π + π − J / ψ ) is measured to be 0.38 ± 0.2 0 stat ± 0.0 1 syst ( R < 0.83 at 90% confidence level). In addition, we measure the ratio of the average cross section of e + e − → ω X ( 3872 ) to e + e − → ω χ c 1 ( ω χ c 2 ) to be σ ω X ( 3872 ) / σ ω χ c 1 ( σ ω X ( 3872 ) / σ ω χ c 2 ) = 5.2 ± 1.0 stat ± 1.9 syst ( 5.5 ± 1.1 stat ± 2.4 syst ) . Finally, we search for the process of e + e − → γ X ( 3872 ) , and no obvious signal is observed. The upper limit on the ratio of the average cross section of e + e − → γ X ( 3872 ) to e + e − → ω X ( 3872 ) is set as σ γ X ( 3872 ) / σ ω X ( 3872 ) < 0.23 at 90% confidence level. Published by the American Physical Society 2024

Astronomy & Astrophysics↗

DOE OSTI2024

Measurements of Normalized Differential Cross Sections of Inclusive η Production in e + e − Annihilation at Energy from 2.0000 to 3.6710 GeV

Using data samples collected with the BESIII detector operating at the BEPCII storage ring, the cross section of the inclusive process e + e − → η + X , normalized by the total cross section of e + e − → hadrons , is measured at eight center-of-mass energy points from 2.0000 to 3.6710 GeV. These are the first measurements with momentum dependence in this energy region. Our measurement shows a significant discrepancy compared to the existing fragmentation functions. To address this discrepancy, a new QCD analysis is performed at the next-to-next-to-leading order with hadron mass corrections and higher twist effects, which can explain both the established high-energy data and our measurements reasonably well. Published by the American Physical Society 2024

Physics↗

DOE OSTI2024

Cross section measurement of e + e − → η ψ ( 2 S ) and search for e + e − → η X ˜ ( 3872 )

The energy-dependent cross section for e + e − → η ψ ( 2 S ) is measured at 18 center of mass energies from 4.288 to 4.951 GeV using the BESIII detector. Using the same data samples, we also perform the first search for the reaction e + e − → η X ˜ ( 3872 ) , but no evidence is found for the X ˜ ( 3872 ) in the π + π − J / ψ mass distribution. At each of the 18 center of mass energies, upper limits at the 90% confidence level on the cross section for e + e − → η ψ ( 2 S ) and on the product of the e + e − → η X ˜ ( 3872 ) cross section with the branching fraction of X ˜ ( 3872 ) → π + π − J / ψ are reported. Published by the American Physical Society 2024

Astronomy & Astrophysics↗

DOE OSTI2024

First Study of Antihyperon-Nucleon Scattering Λ ¯ p → Λ ¯ p and Measurement of Λ p → Λ p Cross Section

Using ( 10.087 ± 0.044 ) × 10 9 J / ψ events collected with the BESIII detector at the BEPCII storage ring, the processes Λ p → Λ p and Λ ¯ p → Λ ¯ p are studied, where the Λ / Λ ¯ baryons are produced in the process J / ψ → Λ Λ ¯ and the protons are the hydrogen nuclei in the cooling oil of the beam pipe. Clear signals are observed for the two reactions. The cross sections in − 0.9 ≤ cos θ Λ / Λ ¯ ≤ 0.9 are measured to be σ ( Λ p → Λ p ) = ( 12.2 ± 1.6 stat ± 1.1 syst ) and σ ( Λ ¯ p → Λ ¯ p ) = ( 17.5 ± 2.1 stat ± 1.6 syst ) mb at the Λ / Λ ¯ momentum of 1.074 GeV / c within a range of ± 0.017 GeV / c , where the θ Λ / Λ ¯ are the scattering angles of the Λ / Λ ¯ in the Λ p / Λ ¯ p rest frames. Furthermore, the differential cross sections of the two reactions are also measured, where there is a slight tendency of forward scattering for Λ p → Λ p , and a strong forward peak for Λ ¯ p → Λ ¯ p . We present an approach to extract the total elastic cross sections by extrapolation. The study of Λ ¯ p → Λ ¯ p represents the first study of antihyperon-nucleon scattering, and these new measurements will serve as important inputs for the theoretical understanding of the (anti)hyperon-nucleon interaction. Published by the American Physical Society 2024

Physics↗