Engineering topics

Fang, Y.

Publications and source records attributed to Fang, Y..

At least 73 records · Page 4

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 J / ψ weak decays containing a D meson

Using a sample of about 10 billion J / ψ events with the BESIII detector, we search for the weak decays of J / ψ → D ¯ 0 π 0 + c . c . , J / ψ → D ¯ 0 η + c . c . , J / ψ → D ¯ 0 ρ 0 + c . c . , J / ψ → D − π + + c . c . , and J / ψ → D − ρ + + c . c . . Since no significant signal is observed, we set the upper limits of the branching fractions of these decays to be B ( J / ψ → D ¯ 0 π 0 + c . c . ) < 4.7 × 10 − 7 , B ( J / ψ → D ¯ 0 η + c . c . ) < 6.8 × 10 − 7 , B ( J / ψ → D ¯ 0 ρ 0 + c . c . ) < 5.2 × 10 − 7 , B ( J / ψ → D − π + + c . c . ) < 7.0 × 10 − 8 , and B ( J / ψ → D − ρ + + c . c . ) < 6.0 × 10 − 7 at the 90% confidence level. Published by the American Physical Society 2024

Astronomy & Astrophysics↗

DOE OSTI2024

Precise Measurement of Born Cross Sections for e + e − → D D ¯ at s = 3.80 − 4.95 GeV

Using data samples collected with the BESIII detector at the BEPCII collider at center-of-mass energies ranging from 3.80 to 4.95 GeV, corresponding to an integrated luminosity of 20 fb − 1 , a measurement of Born cross sections for the e + e − → D 0 D ¯ 0 and D + D − processes is presented with unprecedented precision. Many clear peaks in the line shape of e + e − → D 0 D ¯ 0 and D + D − around the mass range of G ( 3900 ) , ψ ( 4040 ) , ψ ( 4160 ) , Y ( 4260 ) , and ψ ( 4415 ) , etc., are foreseen. These results offer crucial experimental insights into the nature of hadron production in the open-charm region. Published by the American Physical Society 2024

Physics↗

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

Precision measurement of the branching fraction of J / ψ → K + K − via ψ ( 2 S ) → π + π − J / ψ

Using a sample of 448.1 × 10 6 ψ ( 2 S ) events collected with the BESIII detector, we perform a study of the decay J / ψ → K + K − via ψ ( 2 S ) → π + π − J / ψ . The branching fraction of J / ψ → K + K − is determined to be B K + K − = ( 3.072 ± 0.023 ( stat ) ± 0.050 ( syst ) ) × 10 − 4 , which is consistent with previous measurements but with significantly improved precision. Published by the American Physical Society 2024

Astronomy & Astrophysics↗

DOE OSTI2024

Study of e + e − → π + π − π 0 at s from 2.00 to 3.08 GeV at BESIII

With the data samples taken at center-of-mass energies from 2.00 to 3.08 GeV with the BESIII detector at the BEPCII collider, a partial wave analysis on the e + e − → π + π − π 0 process is performed. The Born cross sections for e + e − → π + π − π 0 and its intermediate processes e + e − → ρ π and ρ ( 1450 ) π are measured as functions of s . The results for e + e − → π + π − π 0 are consistent with previous results measured with the initial state radiation method within one standard deviation, and improve the uncertainty by a factor of ten. By fitting the line shapes of the Born cross sections for the e + e − → ρ π and e + e − → ρ ( 1450 ) π , a structure with mass M = 2119 ± 11 ± 15 MeV / c 2 and width Γ = 69 ± 30 ± 5 MeV is observed with a significance of 5.9 σ , where the first uncertainties are statistical and the second ones are systematic. This structure can be interpreted as an excited ω state. Published by the American Physical Society 2024

Astronomy & Astrophysics↗

DOE OSTI2024

Search for diphoton decays of an axionlike particle in radiative J / ψ decays

We search for the diphoton decay of a light pseudoscalar axionlike particle, a , in radiative J / ψ decays, using 10 10 J / ψ events collected with the BESIII detector. We find no evidence of a signal and set upper limits at the 95% confidence level on the product branching fraction B ( J / ψ → γ a ) × B ( a → γ γ ) and the axionlike particle photon coupling constant g a γ γ in the ranges of ( 3.7 – 48.5 ) × 10 − 8 and ( 2.2 – 101.8 ) × 10 − 4 GeV − 1 , respectively, for 0.18 ≤ m a ≤ 2.85 GeV / c 2 . These are the most stringent limits to date in this mass region. Published by the American Physical Society 2024

Astronomy & Astrophysics↗

DOE OSTI2024

Improved measurement of the branching fraction of hc → γη′/η and search for hc → γπ0

Abstract The processesh c → γP(P=η′, η, π 0 ) are studied with a sample of (27.12±0.14)×10 8 ψ(3686) events collected by the BESIII detector at the BEPCII collider. The decayh c → γηis observed for the first time with the significance of 9.0σ, and the branching fraction is determined to be (3.77±0.55±0.13±0.26)×10 −4 , while$$ \mathcal{B} $$ B (h c → γη′) is measured to be (1.40±0.11±0.04±0.10)×10 −3 , where the first uncertainties are statistical, the second systematic, and the third from the branching fraction ofψ(3686)→ π 0 h c . The combination of these results allows for a precise determination of$$ {R}_{h_c}=\frac{\mathcal{B}\left({h}_c\to {\pi}^0\gamma \eta \right)}{\mathcal{B}\left({h}_c\to {\pi}^0\gamma {\eta}^{\prime}\right)}, $$ R h c = B h c → γη B h c → γ η ′ , which is calculated to be (27.0±4.4±1.0)%. The results are valuable for gaining a deeper understanding ofη − η′ mixing, and its manifestation within quantum chromodynamics. No significant signal is found for the decayh c →γπ 0 , and an upper limit is placed on its branching fraction of$$ \mathcal{B} $$ B (h c →γπ 0 )<5.0×10 −5 , at the 90% confidence level.

Physics↗

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

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

Search for the leptonic decays D * + → e + ν e and D * + → μ + ν μ

We present the first search for the leptonic decays D * + → e + ν e and D * + → μ + ν μ by analyzing a data sample of electron-positron collisions recorded with the BESIII detector at center-of-mass energies between 4.178 and 4.226 GeV, corresponding to an integrated luminosity of 6.32 fb − 1 . No significant signal is observed. The upper limits on the branching fractions for D * + → e + ν e and D * + → μ + ν μ are set to be 1.1 × 10 − 5 and 4.3 × 10 − 6 at 90% confidence level, respectively. 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

Measurement of e+e− → ωη′ cross sections at $$ \sqrt{s} $$ = 2.000 to 3.080 GeV

Abstract We measured the Born cross sections for the processe + e − →ωη′ at 22 center-of-mass energies from 2.000 to 3.080 GeV with the BESIII detector at the BEPCII collider. We observed a resonant structure with a statistical significance of 9.6σ. A Breit-Wigner fit determines its mass to beM R = (2153±30±31) MeV/c 2 and its width to be Γ R = (167±77±7) MeV, where the first uncertainties are statistical and the second are systematic.

Physics↗

DOE OSTI2024

Study of η′ → π+π−l+l− decays at BESIII

Abstract With a sample of (10087±44)×10 6 J/ψevents accumulated with the BESIII detector, we analyze the decaysη′→ π + π − l + l − (l=e, μ) via the processJ/ψ → γη′. The branching fractions are measured to be$$ \mathcal{B} $$ B (η′→ π + π − e + e − ) = (2.45±0.02(stat.)±0.08(syst.))×10 −3 and$$ \mathcal{B} $$ B (η′→ π + π − μ + μ − ) = (2.16±0.12(stat.)±0.06(syst.))×10 −5 , and the ratio is$$ \frac{\mathcal{B}\left({\eta}^{\prime}\to {\pi}^{+}{\pi}^{-}{e}^{+}{e}^{-}\right)}{\mathcal{B}\left({\eta}^{\prime}\to {\pi}^{+}{\pi}^{-}{\mu}^{+}{\mu}^{-}\right)}=113.4\pm 0.9\left(\textrm{stat}.\right)\pm 3.7\left(\textrm{syst}.\right) $$ B η ′ → π + π − e + e − B η ′ → π + π − μ + μ − = 113.4 ± 0.9 stat . ± 3.7 syst . . In addition, by combining theη′ →π + π − e + e − andη′ →π + π − μ + μ − decays, the slope parameter of the electromagnetic transition form factor is measured to beb η′ = 1.30 ± 0.19 (GeV/c 2 ) −2 , which is consistent with previous measurements from BESIII and theoretical predictions from the VMD model. The asymmetry in the angle between theπ + π − andl + l − decay planes, which has the potential to reveal theCP-violation originating from an unconventional electric dipole transition, is also investigated. The asymmetry parameters are determined to be$$ {\mathcal{A}}_{CP}\left({\eta}^{\prime}\to {\pi}^{+}{\pi}^{-}{e}^{+}{e}^{-}\right)=\left(-0.21\pm 0.73\left(\textrm{stat}.\right)\pm 0.01\left(\textrm{syst}.\right)\right)\% $$ A CP η ′ → π + π − e + e − = − 0.21 ± 0.73 stat . ± 0.01 syst . % and$$ {\mathcal{A}}_{CP}\left({\eta}^{\prime}\to {\pi}^{+}{\pi}^{-}{\mu}^{+}{\mu}^{-}\right)=\left(0.62\pm 4.71\left(\textrm{stat}.\right)\pm 0.08\left(\textrm{syst}.\right)\right)\% $$ A CP η ′ → π + π − μ + μ − = 0.62 ± 4.71 stat . ± 0.08 syst . % , implying that no evidence ofCP-violation is observed at the present statistics. Finally, an axion-like particle is searched for via the decayη′ →π + π − a, a→e + e − , and upper limits of the branching fractions are presented for the mass assumptions of the axion-like particle in the range of 0−500 MeV/c 2 .

Physics↗