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An, Q.

Publications and source records attributed to An, Q..

At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

First Observation of a Three-Resonance Structure in e + e − → Nonopen Charm Hadrons

We report the measurement of the inclusive cross sections for e + e − → nOCH (where nOCH denotes non-open charm hadrons) with improved precision at center-of-mass (c.m.) energies from 3.645 to 3.871 GeV. We observe three resonances: R ( 3760 ) , R ( 3780 ) , and R ( 3810 ) with significances of 8.1 σ , 13.7 σ , and 8.8 σ , respectively. The R ( 3810 ) state is observed for the first time, while the R ( 3760 ) and R ( 3780 ) states are observed for the first time in the nOCH cross sections. Two sets of resonance parameters describe the energy-dependent line shape of the cross sections well. In set I [set II], the R ( 3810 ) state has mass ( 3805.7 ± 1.1 ± 2.7 ) [ ( 3805.7 ± 1.1 ± 2.7 ) ] MeV / c 2 , total width ( 11.6 ± 2.9 ± 1.9 ) [ ( 11.5 ± 2.8 ± 1.9 ) ] MeV , and an electronic width multiplied by the nOCH decay branching fraction of ( 10.9 ± 3.8 ± 2.5 ) [ ( 11.0 ± 3.4 ± 2.5 ) ] eV . In addition, we measure the branching fractions B [ R ( 3760 ) → nOCH ] = ( 25.2 ± 16.1 ± 30.4 ) % [ ( 6.4 ± 4.8 ± 7.7 ) % ] and B [ R ( 3780 ) → nOCH ] = ( 12.3 ± 6.6 ± 8.3 ) % [ ( 10.4 ± 4.8 ± 7.0 ) % ] for the first time. The R ( 3760 ) state can be interpreted as an open-charm (OC) molecular state, but containing a simple four-quark state component. The R ( 3810 ) state can be interpreted as a hadrocharmonium state. Published by the American Physical Society 2024

Physics↗
DOE OSTI2024

Determination of Spin-Parity Quantum Numbers of X ( 2370 ) as 0 − + from J / ψ → γ K S 0 K S 0 η ′

Based on ( 10 087 ± 44 ) × 10 6 J / ψ events collected with the BESIII detector, a partial wave analysis of the decay J / ψ → γ K S 0 K S 0 η ′ is performed. The mass and width of the X ( 2370 ) are measured to be 2395 ± 11 ( stat ) − 94 + 26 ( syst ) MeV / c 2 and 188 − 17 + 18 ( stat ) − 33 + 124 ( syst ) MeV , respectively. The corresponding product branching fraction is B [ J / ψ → γ X ( 2370 ) ] × B [ X ( 2370 ) → f 0 ( 980 ) η ′ ] × B [ f 0 ( 980 ) → K S 0 K S 0 ] = ( 1.31 ± 0.22 ( stat ) − 0.84 + 2.85 ( syst ) ) × 10 − 5 . The statistical significance of the X ( 2370 ) is greater than 11.7 σ and the spin parity is determined to be 0 − + for the first time. The measured mass and spin parity of the X ( 2370 ) are consistent with the predictions of the lightest pseudoscalar glueball. Published by the American Physical Society 2024

Physics↗
DOE OSTI2024

Measurement of Born cross section of $$ {e}^{+}{e}^{-}\to {\Sigma}^{+}{\overline{\Sigma}}^{-} $$ at center-of-mass energies between 3.510 and 4.951 GeV

Abstract Using 24.1 fb −1 ofe + e − collision data collected with the BESIII detector at the BEPCII collider, the Born cross sections and effective form factors of the$$ {e}^{+}{e}^{-}\to {\Sigma}^{+}{\overline{\Sigma}}^{-} $$ e + e − → Σ + Σ ¯ − reaction are measured. The measurements are performed at center-of-mass energies ranging from 3.510 to 4.951 GeV. No significant evidence for the decay of the charmonium(-like) states,ψ(3770),ψ(4040),ψ(4160),Y(4230),Y(4360),ψ(4415), andY(4660), into a$$ {\Sigma}^{+}{\overline{\Sigma}}^{-} $$ Σ + Σ ¯ − final state is observed. Consequently, upper limits for the products of the branching fractions and the electronic partial widths at the 90% confidence level are reported for these decays.

Physics↗
DOE OSTI2024

Search for ∆S = 2 nonleptonic hyperon decays Ω− → Σ0π− and Ω− → nK−

Abstract Using (27.12 ± 0.14) × 10 8 ψ(3686) events collected by the BESIII detector at the center-of-mass energy of$$ \sqrt{s} $$ s = 3.686 GeV, we search for the first time for two nonleptonic hyperon decays that change strangeness by two units, Ω − → Σ 0 π − and Ω − →nK − . No significant signal is observed. The upper limits on their decay branching fractions are determined to be$$ \mathcal{B} $$ B (Ω − → Σ 0 π − )<5.4 × 10 −4 and$$ \mathcal{B} $$ B (Ω − →nK − )<2.4 × 10 −4 at the 90% confidence level.

Physics↗
DOE OSTI2024

Measurement of absolute branching fractions of $$ {\textrm{D}}_{\textrm{s}}^{+} $$ hadronic decays

Abstract Usinge + e − collision data collected at 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 determine the absolute branching fractions of fifteen hadronic$$ {D}_s^{+} $$ D s + decays with a double-tag technique. In particular, we make precise measurements of the branching fractions$$ \mathcal{B}\left({D}_s^{+}\to {K}^{+}{K}^{-}{\pi}^{+}\right)=\left(5.49\pm 0.04\pm 0.07\right)\% $$ B D s + → K + K − π + = 5.49 ± 0.04 ± 0.07 % ,$$ \mathcal{B}\left({D}_s^{+}\to {K}_S^0{K}^{+}\right)=\left(1.50\pm 0.01\pm 0.01\right)\% $$ B D s + → K S 0 K + = 1.50 ± 0.01 ± 0.01 % and$$ \mathcal{B}\left({D}_s^{+}\to {K}^{+}{K}^{-}{\pi}^{+}{\pi}^0\right)=\left(5.50\pm 0.05\pm 0.11\right)\% $$ B D s + → K + K − π + π 0 = 5.50 ± 0.05 ± 0.11 % , where the first uncertainties are statistical and the second ones are systematic. TheCPasymmetries in these decays are also measured and all are found to be compatible with zero.

Physics↗
DOE OSTI2024

Study of h c → 3 ( π + π − ) π 0 , h c → 2 ( π + π − ) ω , h c → 2 ( π + π − ) π 0 η , h c → 2 ( π + π − ) η , and h c → p p ¯

Based on ( 2712.4 ± 14.1 ) × 10 6 ψ ( 3686 ) events collected with the BESIII detector, we study the decays h c → 3 ( π + π − ) π 0 , h c → 2 ( π + π − ) ω , h c → 2 ( π + π − ) π 0 η , h c → 2 ( π + π − ) η , and h c → p p ¯ via ψ ( 3686 ) → π 0 h c . The decay channel h c → 3 ( π + π − ) π 0 is observed for the first time, and its branching fraction is determined to be ( 9.28 ± 1.14 ± 0.77 ) × 10 − 3 , where the first uncertainty is statistical and the second is systematic. In addition, first evidence is found for the modes h c → 2 ( π + π − ) π 0 η and h c → 2 ( π + π − ) ω with significances of 4.8 σ and 4.7 σ , and their branching fractions are determined to be ( 7.55 ± 1.51 ± 0.77 ) × 10 − 3 and ( 4.00 ± 0.86 ± 0.35 ) × 10 − 3 , respectively. No significant signals of h c → 2 ( π + π − ) η and h c → p p ¯ are observed, and the upper limits of the branching fractions of these decays are determined to be < 6.19 × 10 − 4 and < 4.40 × 10 − 5 at the 90% confidence level, respectively. Published by the American Physical Society 2024

Astronomy & Astrophysics↗
DOE OSTI2024

Observation of the singly Cabibbo-suppressed decay Λ c + → Σ − K + π +

The singly Cabibbo-suppressed decay Λ c + → Σ − K + π + is observed for the first time with a statistical significance of 5.4 σ by using 4.5 fb − 1 of e + e − collision data collected at center-of-mass energies between 4.600 and 4.699 GeV with the BESIII detector at BEPCII. The absolute branching fraction of Λ c + → Σ − K + π + is measured to be ( 3.8 ± 1.2 stat ± 0.2 syst ) × 10 − 4 in a model-independent approach. This is the first observation of a Cabibbo-suppressed Λ c + decay involving Σ − in the final state. The ratio of branching fractions between Λ c + → Σ − K + π + and the Cabibbo-favored decay Λ c + → Σ − π + π + is observed to be ( 0.4 ± 0.1 ) s c 2 , where s c ≡ sin θ c = 0.2248 with θ c the Cabibbo mixing angle. Published by the American Physical Society 2024

Astronomy & Astrophysics↗
DOE OSTI2024

Measurements of Born cross sections for e + e − → Λ c + Λ ¯ c ( 2595 ) − + c . c . and e + e − → Λ c + Λ ¯ c ( 2625 ) − + c . c . at s = 4918.0 and 4950.9 MeV

Using e + e − collision data collected with the BESIII detector operating at the BEPCII collider, the Born cross sections of e + e − → Λ c + Λ ¯ c ( 2595 ) − + c . c . and e + e − → Λ c + Λ ¯ c ( 2625 ) − + c . c . are measured for the first time at center-of-mass energies of s = 4918.0 and 4950.9 MeV. Nonzero cross sections are observed very close to the production threshold. The measured Born cross sections of e + e − → Λ c + Λ ¯ c ( 2625 ) − + c . c . are about 2–3 times greater than those of e + e − → Λ c + Λ ¯ c ( 2595 ) − + c . c . , providing the similar behavior as semileptonic decays of Λ b 0 , but different behavior from that in the hadronic decays of Λ b 0 . The Born cross sections are 15.6 ± 3.1 ± 0.9 pb and 29.4 ± 3.7 ± 2.7 pb for e + e − → Λ c + Λ ¯ c ( 2595 ) − + c . c . , and are 43.4 ± 4.0 ± 4.1 pb and 76.8 ± 6.5 ± 4.2 pb for e + e − → Λ c + Λ ¯ c ( 2625 ) − + c . c . at s = 4918.0 and 4950.9 MeV, respectively. Based on the polar angle distributions of the Λ ¯ c ( 2625 ) − and Λ c ( 2625 ) + , the form-factor ratios | G E | 2 + 3 | G M | 2 / | G C | are determined for e + e − → Λ c + Λ ¯ c ( 2625 ) − + c . c . for the first time, which are 5.95 ± 4.07 ± 0.15 and 0.94 ± 0.32 ± 0.02 at s = 4918.0 and 4950.9 MeV, respectively. All of these first uncertainties are statistical and second systematic. Published by the American Physical Society 2024

Astronomy & Astrophysics↗
DOE OSTI2024

Observation of χ c J → 3 ( K + K − )

By analyzing ( 27.12 ± 0.14 ) × 10 8 ψ ( 3686 ) events collected with the BESIII detector operating at the BEPCII collider, the decay processes χ c J → 3 ( K + K − ) ( J = 0 , 1, 2) are observed for the first time with statistical significances of 8.2 σ , 8.1 σ , and 12.4 σ , respectively. The product branching fractions of ψ ( 3686 ) → γ χ c J , χ c J → 3 ( K + K − ) are presented and the branching fractions of χ c J → 3 ( K + K − ) decays are determined to be B χ c 0 → 3 ( K + K − ) = ( 10.7 ± 1.8 ± 1.1 ) × 10 − 6 , B χ c 1 → 3 ( K + K − ) = ( 4.2 ± 0.9 ± 0.5 ) × 10 − 6 , and B χ c 2 → 3 ( K + K − ) = ( 7.2 ± 1.1 ± 0.8 ) × 10 − 6 , where the first uncertainties are statistical and the second are systematic. Published by the American Physical Society 2024

Astronomy & Astrophysics↗
DOE OSTI2024

Search for η c ( 2 S ) → π + π − η c and η c ( 2 S ) → π + π − K S 0 K ± π ∓ decays

Based on ( 27.12 ± 0.14 ) × 10 8 ψ ( 2 S ) events collected by the BESIII detector, we search for the decay η c ( 2 S ) → π + π − η c via ψ ( 2 S ) → γ η c ( 2 S ) . No significant signal is observed, and the upper limit on the product branching fraction B ( ψ ( 2 S ) → γ η c ( 2 S ) ) × B ( η c ( 2 S ) → π + π − η c ) is determined to be 2.21 × 10 − 5 at the 90% confidence level. In addition, the η c ( 2 S ) → π + π − K S 0 K ± π ∓ decay is studied via ψ ( 2 S ) → γ η c ( 2 S ) and is observed with a statistical significance of 10 σ for the first time. The branching fraction of η c ( 2 S ) → π + π − K S 0 K ± π ∓ is determined to be ( 1.33 ± 0.11 ± 0.40 ± 0.95 ) × 10 − 2 , where the first uncertainty is statistical, the second is systematic, and the third uncertainty is due to the quoted B ( ψ ( 2 S ) → γ η c ( 2 S ) ) . Published by the American Physical Society 2024

Astronomy & Astrophysics↗
DOE OSTI2024

Observation of ψ ( 3686 ) → 3 ϕ

Using ( 2.712 ± 0.014 ) × 10 9 ψ ( 3686 ) events collected by the BESIII detector operating at the BEPCII collider, we report the first observation of ψ ( 3686 ) → 3 ϕ decay with a significance larger than 10 σ . The branching fraction of this decay is determined to be ( 1.46 ± 0.05 ± 0.17 ) × 10 − 5 , where the first uncertainty is statistical and the second is systematic. No significant structure is observed in the ϕ ϕ invariant mass spectra. Published by the American Physical Society 2024

Astronomy & Astrophysics↗
DOE OSTI2024

Observation of Structures in the Processes e + e − → ω χ c 1 and ω χ c 2

We present measurements of the Born cross sections for the processes e + e − → ω χ c 1 and ω χ c 2 at center-of-mass energies s from 4.308 to 4.951 GeV. The measurements are performed with data samples corresponding to an integrated luminosity of 11.0 fb − 1 collected with the BESIII detector operating at the Beijing Electron Positron Collider storage ring. Assuming the e + e − → ω χ c 2 signals come from a single resonance, the mass and width are determined to be M = ( 4413.6 ± 9.0 ± 0.8 ) MeV / c 2 and Γ = ( 110.5 ± 15.0 ± 2.9 ) MeV , respectively, which is consistent with the parameters of the well-established resonance ψ ( 4415 ) . In addition, we also use one single resonance to describe the e + e − → ω χ c 1 line shape and determine the mass and width to be M = ( 4544.2 ± 18.7 ± 1.7 ) MeV / c 2 and Γ = ( 116.1 ± 33.5 ± 1.7 ) MeV , respectively. The structure of this line shape, observed for the first time, requires further understanding. Published by the American Physical Society 2024

Physics↗
DOE OSTI2024

Study of excited Ξ states in ψ ( 3686 ) → K − Λ Ξ ¯ + + c . c .

Based on a sample of ( 448.1 ± 2.9 ) × 10 6 ψ ( 3686 ) events collected with the BESIII detector at BEPCII, the decays of ψ ( 3686 ) → K − Λ Ξ ¯ + + c . c . with Ξ ¯ + → Λ ¯ π + , Λ ¯ → p ¯ π + are studied. We investigate the two excited resonances, Ξ ( 1690 ) − and Ξ ( 1820 ) − , which are each observed with large significance ( ≫ 10 σ ) in the K − Λ invariant mass distributions. A partial wave analysis is performed, and the spin-parities of Ξ ( 1690 ) − and Ξ ( 1820 ) − are measured to be 1 2 − and 3 2 − , respectively. The masses, widths, and product branching fractions of Ξ ( 1690 ) − and Ξ ( 1820 ) − are also measured. Published by the American Physical Society 2024

Astronomy & Astrophysics↗
DOE OSTI2024

Measurement of branching fractions for Λ c + → n K S 0 π + and Λ c + → n K S 0 K +

Based on 4.5 fb − 1 of e + e − collision data accumulated at center-of-mass energies between 4599.53 and 4698.82 MeV with the BESIII detector, we measure the absolute branching fraction of the Cabibbo-favored decay Λ c + → n K S 0 π + with the precision improved by a factor of 2.8 and report the first evidence for the singly-Cabibbo-suppressed decay Λ c + → n K S 0 K + . The branching fractions for Λ c + → n K S 0 π + and Λ c + → n K S 0 K + are determined to be ( 1.86 ± 0.08 ± 0.04 ) × 10 − 2 and ( 3. 9 − 1.4 + 1.7 ± 0.3 ) × 1 0 − 4 , respectively, where the first uncertainties are statistical and the second ones are systematic. Published by the American Physical Society 2024

Astronomy & Astrophysics↗
DOE OSTI2024

Coupled-Channel Analysis of the χ c 1 ( 3872 ) Line Shape with BESIII Data

We perform a study of the χ c 1 ( 3872 ) line shape using the data samples of e + e − → γ χ c 1 ( 3872 ) , χ c 1 ( 3872 ) → D 0 D ¯ 0 π 0 , and π + π − J / ψ collected with the BESIII detector. The effects of the coupled channels and the off-shell D * 0 are included in the parametrization of the line shape. The line shape mass parameter is obtained to be M X = ( 3871.63 ± 0.1 3 − 0.05 + 0.06 ) MeV . Two poles are found on the first and second Riemann sheets corresponding to the D * 0 D ¯ 0 branch cut. The pole location on the first sheet is much closer to the D * 0 D ¯ 0 threshold than the other, and is determined to be 7.04 ± 0.1 5 − 0.08 + 0.07 MeV above the D 0 D ¯ 0 π 0 threshold with an imaginary part − 0.19 ± 0.0 8 − 0.19 + 0.14 MeV . Published by the American Physical Society 2024

Physics↗
DOE OSTI2024

Observation of the Anomalous Shape of X ( 1840 ) in J / ψ → γ 3 ( π + π − ) Indicating a Second Resonance Near p p ¯ Threshold

Using a sample of ( 10087 ± 44 ) × 10 6 J / ψ events, which is about 45 times larger than that was previously analyzed, a further investigation on the J / ψ → γ 3 ( π + π − ) decay is performed. A significant distortion at 1.84 GeV / c 2 in the line shape of the 3 ( π + π − ) invariant mass spectrum is observed for the first time, which could be resolved by two overlapping resonant structures, X ( 1840 ) and X ( 1880 ) . The new state X ( 1880 ) is observed with a statistical significance larger than 10 σ . The mass and width of X ( 1880 ) are determined to be 1882.1 ± 1.7 ± 0.7 MeV / c 2 and 30.7 ± 5.5 ± 2.4 MeV , respectively, which indicates the existence of a p p ¯ bound state. Published by the American Physical Society 2024

Physics↗