Engineering topics

Choi, S. K.

Publications and source records attributed to Choi, S. K..

At least 109 records · Page 6

DOE OSTI2024

Measurements of Σ electromagnetic form factors in the timelike region using the untagged initial-state radiation technique

The process e + e − → Σ + Σ ¯ − is studied from threshold up to 3.04 GeV / c 2 via the initial-state radiation technique using data with an integrated luminosity of 12.0 fb − 1 , collected at center-of-mass energies between 3.773 and 4.258 GeV with the BESIII detector at the BEPCII collider. The pair production cross sections and the effective form factors of Σ are measured in eleven Σ + Σ ¯ − invariant mass intervals from threshold to 3.04 GeV / c 2 . The results are consistent with the previous results from Belle and BESIII. Furthermore, the branching fractions of the decays J / ψ → Σ + Σ ¯ − and ψ ( 3686 ) → Σ + Σ ¯ − are determined and the obtained results are consistent with the previous results of BESIII. Published by the American Physical Society 2024

Astronomy & Astrophysics↗

DOE OSTI2024

Observation of D s + → η ′ μ + ν μ , Precision Test of Lepton Flavor Universality with D s + → η ( ′ ) l + ν l , and First Measurements of D s + → η ( ′ ) μ + ν μ Decay Dynamics

By analyzing 7.33 fb − 1 of e + e − annihilation data collected at center-of-mass energies between 4.128 and 4.226 GeV with the BESIII detector, we report the observation of the semileptonic decay D s + → η ′ μ + ν μ , with a statistical significance larger than 10 σ , and the measurements of the D s + → η μ + ν μ and D s + → η ′ μ + ν μ decay dynamics for the first time. The branching fractions of D s + → η μ + ν μ and D s + → η ′ μ + ν μ are determined to be ( 2.235 ± 0.05 1 stat ± 0.05 2 syst ) % and ( 0.801 ± 0.05 5 stat ± 0.02 8 syst ) % , respectively, with precision improved by factors of 6.0 and 6.6 compared to the previous best measurements. Combined with the results for the decays D s + → η e + ν e and D s + → η ′ e + ν e , the ratios of the decay widths are examined both inclusively and in several ℓ + ν ℓ four-momentum transfer ranges. No evidence for lepton flavor universality violation is found within the current statistics. The products of the hadronic form factors f + , 0 η ( ′ ) ( 0 ) and the c → s Cabibbo-Kobayashi-Maskawa matrix element | V c s | are determined. The results based on the two-parameter series expansion are f + , 0 η ( 0 ) | V c s | = 0.452 ± 0.01 0 stat ± 0.00 7 syst and f + , 0 η ′ ( 0 ) | V c s | = 0.504 ± 0.03 7 stat ± 0.01 2 syst , which help to constrain present models on f + , 0 η ( ′ ) ( 0 ) . The forward-backward asymmetries are determined to be ⟨ A FB η ⟩ = − 0.059 ± 0.03 1 stat ± 0.00 5 syst and ⟨ A FB η ′ ⟩ = − 0.064 ± 0.07 9 stat ± 0.00 6 syst for the first time, which are consistent with the theoretical calculation. Published by the American Physical Society 2024

Physics↗

DOE OSTI2024

Study of the doubly Cabibbo-suppressed decays D s + → K + K + π − and D s + → K + K + π − π 0

Based on 7.33 fb − 1 of e + e − collision data collected at center-of-mass energies between 4.128 and 4.226 GeV with the BESIII detector, the experimental studies of the doubly Cabibbo-suppressed decays D s + → K + K + π − and D s + → K + K + π − π 0 are reported. We determine the absolute branching fraction of D s + → K + K + π − to be ( 1.2 4 − 0.26 + 0.28 ( stat ) ± 0.06 ( syst ) ) × 10 − 4 . No significant signal of D s + → K + K + π − π 0 is observed and the upper limit on its decay branching fraction at 90% confidence level is set to be 1.7 × 10 − 4 . Published by the American Physical Society 2024

Astronomy & Astrophysics↗

DOE OSTI2024

Determination of the Σ + Timelike Electromagnetic Form Factors

Based on data samples collected with the BESIII detector at the BEPCII collider, the process e + e − → Σ + Σ ¯ − is studied at center-of-mass energies s = 2.3960 , 2.6454, and 2.9000 GeV. Using a fully differential angular description of the final state particles, both the relative magnitude and phase information of the Σ + electromagnetic form factors in the timelike region are extracted. The relative phase between the electric and magnetic form factors is determined to be sin Δ Φ = − 0.67 ± 0.29 ( stat ) ± 0.18 ( syst ) at s = 2.3960 GeV , Δ Φ = 55 ° ± 19 ° ( stat ) ± 14 ° ( syst ) at s = 2.6454 GeV , and 78 ° ± 22 ° ( stat ) ± 9 ° ( syst ) at s = 2.9000 GeV . For the first time, the phase of the hyperon electromagnetic form factors is explored in a wide range of four-momentum transfer. The evolution of the phase along with four-momentum transfer is an important input for understanding its asymptotic behavior and the dynamics of baryons. Published by the American Physical Society 2024

Physics↗

DOE OSTI2024

Improved measurement of the decays η ′ → π + π − π + ( 0 ) π − ( 0 ) and search for the rare decay η ′ → 4 π 0

Using a sample of 10 billion J / ψ events collected with the BESIII detector, the decays η ′ → π + π − π + π − , η ′ → π + π − π 0 π 0 and η ′ → 4 π 0 are studied via the process J / ψ → γ η ′ . The branching fractions of η ′ → π + π − π + π − and η ′ → π + π − π 0 π 0 are measured to be ( 8.56 ± 0.25 ( stat ) ± 0.23 ( syst ) ) × 10 − 5 and ( 2.12 ± 0.12 ( stat ) ± 0.10 ( syst ) ) × 10 − 4 , respectively, which are consistent with previous measurements but with improved precision. No significant η ′ → 4 π 0 signal is observed, and the upper limit on the branching fraction of this decay is determined to be less than 1.24 × 10 − 5 at the 90% confidence level. In addition, an amplitude analysis of η ′ → π + π − π + π − is performed to extract the doubly virtual isovector form factor α for the first time. The measured value of α = 1.22 ± 0.33 ( stat ) ± 0.04 ( syst ) , is in agreement with the prediction of the vector meson dominance model. Published by the American Physical Society 2024

Astronomy & Astrophysics↗

DOE OSTI2024

Search for a muonphilic scalar X 0 or vector X 1 via J / ψ → μ + μ − + invisible decays at BESIII

A light scalar X 0 or vector X 1 particles have been introduced as a possible explanation for the ( g − 2 ) μ anomaly and dark matter phenomena. Using ( 8.998 ± 0.039 ) × 10 9 J / ψ events collected by the BESIII detector, we search for a light muon philic scalar X 0 or vector X 1 in the processes J / ψ → μ + μ − X 0 , 1 with X 0 , 1 invisible decays. No obvious signal is found, and the upper limits on the coupling g 0 , 1 ′ between the muon and the X 0 , 1 particles are set to be between 1.1 × 10 − 3 and 1.0 × 10 − 2 for the X 0 , 1 mass in the range of 1 < M ( X 0 , 1 ) < 1000 MeV / c 2 at 90% credibility level. Published by the American Physical Society 2024

Astronomy & Astrophysics↗

DOE OSTI2024

Updated measurements of the M1 transition ψ ( 3686 ) → γ η c ( 2 S ) with η c ( 2 S ) → K K ¯ π

Based on a data sample of ( 2712.4 ± 14.3 ) × 10 6 ψ ( 3686 ) events collected with the BESIII detector at the BEPCII collider, the M1 transition ψ ( 3686 ) → γ η c ( 2 S ) with η c ( 2 S ) → K K ¯ π is studied, where K K ¯ π is K + K − π 0 or K S 0 K ± π ∓ . The mass and width of the η c ( 2 S ) are measured to be ( 3637.8 ± 0.8 ( stat ) ± 0.2 ( syst ) ) MeV / c 2 and ( 10.5 ± 1.7 ( stat ) ± 3.5 ( syst ) ) MeV , respectively. The product branching fraction B ( ψ ( 3686 ) → γ η c ( 2 S ) ) × B ( η c ( 2 S ) → K K ¯ π ) is determined to be ( 0.97 ± 0.06 ( stat ) ± 0.09 ( syst ) ) × 10 − 5 . Using B ( η c ( 2 S ) → K K ¯ π ) = ( 1.8 6 − 0.49 + 0.68 ) % , we obtain the branching fraction of the radiative transition to be B ( ψ ( 3686 ) → γ η c ( 2 S ) ) = ( 5.2 ± 0.3 ( stat ) ± 0.5 ( syst ) − 1.4 + 1.9 ( extr ) ) × 10 − 4 , where the third uncertainty is due to the quoted B ( η c ( 2 S ) → K K ¯ π ) . Published by the American Physical Society 2024

Astronomy & Astrophysics↗

DOE OSTI2024

First observation of Λ c + → Λ K + π 0 and evidence of Λ c + → Λ K + π + π −

We present the first observation of the singly Cabibbo-suppressed decay Λ c + → Λ K + π 0 with a significance of 5.7 σ and the first evidence of Λ c + → Λ K + π + π − decay with a significance of 3.1 σ , based on e + e − annihilation data recorded by the BESIII detector at the BEPCII collider. The data correspond to an integrated luminosity of 6.4 fb − 1 , in the center-of-mass energy range from 4.600 to 4.950 GeV. We determine the branching fractions of Λ c + → Λ K + π 0 and Λ c + → Λ K + π + π − relative to their Cabibbo-favored counterparts to be B ( Λ c + → Λ K + π 0 ) B ( Λ c + → Λ π + π 0 ) = ( 2.09 ± 0.3 9 stat ± 0.0 7 syst ) × 10 − 2 and B ( Λ c + → Λ K + π + π − ) B ( Λ c + → Λ π + π + π − ) = ( 1.13 ± 0.4 1 stat ± 0.0 6 syst ) × 10 − 2 , respectively. Moreover, by combining our measured result with the world average of B ( Λ c + → Λ π + π 0 ) , we obtain the branching fraction B ( Λ c + → Λ K + π 0 ) = ( 1.49 ± 0.2 7 stat ± 0.0 5 syst ± 0.0 8 ref ) × 10 − 3 . This result significantly departs from theoretical predictions based on quark S U ( 3 ) flavor symmetry, which is underpinned by the presumption of meson pair S -wave amplitude dominance. Published by the American Physical Society 2024

Astronomy & Astrophysics↗

DOE OSTI2024

Search for the light hadron decay χ c 1 ( 3872 ) → π + π − η

With a data sample corresponding to an integrated luminosity of 11.5 fb − 1 collected with the BESIII detector operating at the BEPCII storage ring, for the first time the light hadron decay χ c 1 ( 3872 ) → π + π − η is searched for. While no significant signal is observed, the upper limits at the 90% confidence level for σ [ e + e − → γ χ c 1 ( 3872 ) ] B [ χ c 1 ( 3872 ) → π + π − η ] at center of mass energies from 4.13 GeV to 4.34 GeV are determined. By normalizing to the χ c 1 ( 3872 ) → π + π − J / ψ decay channel, a 90% confidence level upper limit for the branching fraction ratio R = B [ χ c 1 ( 3872 ) → π + π − η ] / B [ χ c 1 ( 3872 ) → π + π − J / ψ ] < 0.12 is given. These measurements provide important inputs for understanding the internal structure of the χ c 1 ( 3872 ) resonance. Published by the American Physical Society 2024

Astronomy & Astrophysics↗

DOE OSTI2024

Cosmology from cross-correlation of ACT-DR4 CMB lensing and DES-Y3 cosmic shear

Cross-correlation between weak lensing of the Cosmic Microwave Background (CMB) and weak lensing of galaxies offers a way to place robust constraints on cosmological and astrophysical parameters with reduced sensitivity to certain systematic effects affecting individual surveys. We measure the angular cross-power spectrum between the Atacama Cosmology Telescope (ACT) DR4 CMB lensing and the galaxy weak lensing measured by the Dark Energy Survey (DES) Y3 data. Our baseline analysis uses the CMB convergence map derived from ACT-DR4 and Planck data, where most of the contamination due to the thermal Sunyaev Zel’dovich effect is removed, thus avoiding important systematics in the cross-correlation. In our modelling, we consider the nuisance parameters of the photometric uncertainty, multiplicative shear bias and intrinsic alignment of galaxies. The resulting cross-power spectrum has a signal-to-noise ratio = 7.1 and passes a set of null tests. We use it to infer the amplitude of the fluctuations in the matter distribution (S_8 ≡ σ_8(Ω_m/0.3)^0.5 = 0.782 ± 0.059) with informative but well-motivated priors on the nuisance parameters. We also investigate the validity of these priors by significantly relaxing them and checking the consistency of the resulting posteriors, finding them consistent, albeit only with relatively weak constraints. This cross-correlation measurement will improve significantly with the new ACT-DR6 lensing map and form a key component of the joint 6×2pt analysis between DES and ACT.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2024

First Measurement of the Decay Asymmetry in the Pure W -Boson-Exchange Decay Λ c + → Ξ 0 K +

Based on 4.4 fb − 1 of e + e − annihilation data collected at the center-of-mass energies between 4.60 and 4.70 GeV with the BESIII detector at the BEPCII collider, the pure W -boson-exchange decay Λ c + → Ξ 0 K + is studied with a full angular analysis. The corresponding decay asymmetry is measured for the first time to be α Ξ 0 K + = 0.01 ± 0.16 ( stat ) ± 0.03 ( syst ) . This result reflects the noninterference effect between the S - and P -wave amplitudes. The phase shift between S - and P -wave amplitudes has two solutions, which are δ p − δ s = − 1.55 ± 0.25 ( stat ) ± 0.05 ( syst ) rad or 1.59 ± 0.25 ( stat ) ± 0.05 ( syst ) rad . Published by the American Physical Society 2024

Physics↗

DOE OSTI2024

Observation and branching fraction measurement of the decay J / ψ → p ¯ Σ + K S 0 + c . c .

The first observation of the decays J / ψ → p ¯ Σ + K S 0 and J / ψ → p Σ ¯ − K S 0 is reported using ( 10087 ± 44 ) × 10 6 J / ψ events recorded by the BESIII detector at the BEPCII storage ring. The branching fractions of each channel are determined to be B ( J / ψ → p ¯ Σ + K S 0 ) = ( 1.361 ± 0.006 ± 0.025 ) × 10 − 4 , and B ( J / ψ → p Σ ¯ − K S 0 ) = ( 1.352 ± 0.006 ± 0.025 ) × 10 − 4 . The combined result is B ( J / ψ → p ¯ Σ + K S 0 + c . c . ) = ( 2.725 ± 0.009 ± 0.050 ) × 10 − 4 , where the first uncertainty is statistical and the second systematic. The results presented are in good agreement with the branching fractions of the isospin partner decay J / ψ → p K − Σ ¯ 0 + c . c . Published by the American Physical Society 2024

Astronomy & Astrophysics↗

DOE OSTI2024

Observation of the decay J / ψ → e + e − η ( 1405 ) with η ( 1405 ) → π 0 f 0 ( 980 )

Using a data sample of ( 10087 ± 44 ) × 10 6 J / ψ events collected by the BESIII detector in 2009, 2012, 2018 and 2019, the electromagnetic Dalitz process J / ψ → e + e − η ( 1405 ) is observed via the decay η ( 1405 ) → π 0 f 0 ( 980 ) , f 0 ( 980 ) → π + π − , with a significance of about 9.8 σ . The branching fraction of this decay is measured to be B ( J / ψ → e + e − η ( 1405 ) → e + e − π 0 f 0 ( 980 ) → e + e − π 0 π + π − ) = ( 2.04 ± 0.20 ( stat ) ± 0.08 ( syst ) ) × 10 − 7 . The branching fraction ratio B ( J / ψ → e + e − η ( 1405 ) ) / B ( J / ψ → γ η ( 1405 ) ) is determined to be ( 1.36 ± 0.17 ( stat ) ± 0.06 ( syst ) ) × 10 − 2 . Furthermore, an e + e − invariant mass dependent transition form factor of J / ψ → e + e − η ( 1405 ) is presented for the first time. The obtained result provides input for different theoretical models and is valuable for the improved understanding the intrinsic structure of the η ( 1405 ) meson. Published by the American Physical Society 2024

Astronomy & Astrophysics↗

DOE OSTI2024

Measurement of the e + e − → Λ Σ ¯ 0 + c . c . cross sections at s from 2.3094 to 3.0800 GeV

The Born cross sections and effective form factors of the process e + e − → Λ Σ ¯ 0 + c . c . are measured at 14 center-of-mass energy points from 2.3094 to 3.0800 GeV, based on data corresponding to an integrated luminosity of ( 478.5 ± 4.8 ) pb − 1 collected with the BESIII detector. A nonzero Born cross section is observed at the center-of-mass energy of 2.3094 GeV with a statistical significance of more than five standard deviations, and the cross sections at other energies are obtained with improved precision compared to earlier measurements from the Collaboration. The Born cross-section line shape is described better by a shape considering the strong-interaction effects than by a pQCD motivated functional form. Published by the American Physical Society 2024

Astronomy & Astrophysics↗

DOE OSTI2023