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At least 325 records · Page 18

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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

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 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

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

Measurement of e + e − → η J / ψ cross section from s = 3.808 GeV to 4.951 GeV

Using data samples with an integrated luminosity of 22.42 fb − 1 collected by the BESIII detector operating at the BEPCII storage ring, we measure the cross sections of the e + e − → η J / ψ process at center-of-mass energies from 3.808 to 4.951 GeV. Three structures are observed in the line shape of the measured cross sections. A maximum-likelihood fit with ψ ( 4040 ) , two additional resonances, and a nonresonant component are performed. The mass and width of the first additional state are ( 4219.7 ± 2.5 ± 4.5 ) MeV / c 2 and ( 80.7 ± 4.4 ± 1.4 ) MeV , respectively, consistent with the ψ ( 4230 ) . For the second state, the mass and width are ( 4386 ± 13 ± 17 ) MeV / c 2 and ( 177 ± 32 ± 13 ) MeV , respectively, consistent with the ψ ( 4360 ) . The first uncertainties are statistical, and the second ones are systematic. The statistical significance of ψ ( 4040 ) is 8.0 σ and those for ψ ( 4230 ) and ψ ( 4360 ) are more than 10.0 σ . Published by the American Physical Society 2024

Ablikim, M.↗

DOE OSTI2024

Search for the production of deuterons and antideuterons in e + e − annihilation at center-of-mass energies between 4.13 and 4.70 GeV

Using a data sample of e + e − collision data corresponding to an integrated luminosity of 19 fb − 1 collected with the BESIII detector at the BEPCII collider, we search for the production of deuterons and antideuterons via e + e − → p p π − d ¯ + c . c . for the first time at center-of-mass energies between 4.13 and 4.70 GeV. No significant signal is observed and the upper limit of the e + e − → p p π − d ¯ + c . c . cross section is determined to be from 9.0 to 145 fb depending on the center-of-mass energy at the 90% confidence level. Published by the American Physical Society 2024

Ablikim, M.↗

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 measurements of the absolute branching fraction of Λ c ( 2625 ) + → Λ c + π + π − and upper limit on Λ c ( 2595 ) + → Λ c + π + π −

The absolute branching fraction of the decay Λ c ( 2625 ) + → Λ c + π + π − is measured for the first time to be ( 50.2 ± 5.7 stat ± 3.5 syst ) % with 368.48 pb − 1 of e + e − collision data collected by the BESIII detector at the center-of-mass energies of s = 4.918 and 4.950 GeV. Although the central value of the result is lower than the theoretical prediction of 67%, obtained from isospin symmetry, they are consistent taking the uncertainties into account. This is the first absolute branching fraction measurement for Λ c ( 2625 ) + since it was found. This measurement is necessary to obtain the coupling constants for the transitions between s -wave and p -wave charmed baryons in heavy hadron chiral perturbation theory. In addition, we search for the decay Λ c ( 2595 ) + → Λ c + π + π − . No significant signal is observed, and the upper limit on its branching fraction is determined to be 85.0% at the 90% confidence level. Published by the American Physical Society 2024

Astronomy & Astrophysics↗

DOE OSTI2024

Search for e + e − → K + K − ψ ( 3770 ) at center-of-mass energies from 4.84 to 4.95 GeV

Using e + e − collision data, corresponding to an integrated luminosity of 892 pb − 1 collected at center-of-mass energies from 4.84 to 4.95 GeV with the BESIII detector, we search for the process e + e − → K + K − ψ ( 3770 ) by reconstructing two charged kaons and one D meson from ψ ( 3770 ) . No significant signal of e + e − → K + K − ψ ( 3770 ) is found and the upper limits of the Born cross sections are reported at 90% confidence level. 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

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

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

Using a data sample corresponding to an integrated luminosity of 10.9 fb − 1 collected at center-of-mass energies from 4.16 to 4.34 GeV with the BESIII detector, we search for the decay χ c 1 ( 3872 ) → π + π − χ c 1 in the radiative production e + e − → γ χ c 1 ( 3872 ) . No significant signal is observed, and the ratio for the branching fraction of χ c 1 ( 3872 ) → π + π − χ c 1 to χ c 1 ( 3872 ) → π + π − J / ψ is measured as R ≡ B [ χ c 1 ( 3872 ) → π + π − χ c 1 ] B [ χ c 1 ( 3872 ) → π + π − J / ψ ] < 0.18 at 90% confidence level. An upper limit on the product of the cross section σ [ e + e − → γ χ c 1 ( 3872 ) ] and the branching fraction B [ χ c 1 ( 3872 ) → π + π − χ c 1 ] at each center-of-mass energy is also given. These measurements favor the nonconventional charmonium nature of the χ c 1 ( 3872 ) state. 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

Evidence of the singly Cabibbo suppressed decay Λ c + → p π 0

Evidence for the singly Cabibbo suppressed decay Λ c + → p π 0 is reported for the first time with a statistical significance of 3.7 σ based on 6.0 fb − 1 of e + e − collision data collected at center-of-mass energies between 4.600 and 4.843 GeV with the BESIII detector at the BEPCII collider. The absolute branching fraction of Λ c + → p π 0 is measured to be ( 1.5 6 − 0.58 + 0.72 ± 0.20 ) × 10 − 4 . Combining with the branching fraction of Λ c + → n π + , ( 6.6 ± 1.3 ) × 10 − 4 , the ratio of the branching fractions of Λ c + → n π + and Λ c + → p π 0 is calculated to be 3.2 − 1.2 + 2.2 . As an important input for the theoretical models describing the decay mechanisms of charmed baryons, our result indicates that the nonfactorizable contributions play an essential role and their interference with the factorizable contributions should not be significant. In addition, the absolute branching fraction of Λ c + → p η is measured to be ( 1.63 ± 0.3 1 stat ± 0.1 1 syst ) × 10 − 3 . 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

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↗