Using a sample of 14 × 10 ⁶ ψ(2S) events accumulated with the BES II detector, evidence for f 0 (980)f 0 (980) production in χ c0 decays is obtained for the first time; the branching ratio is determined to be B[χ c0 → f 0 (980)f 0 (980) → π ⁺ π ^- π ⁺ π ^- ] = [7.6 ± 1.9 (stat) ± 1.6 (syst)] × 10 ⁴ . The significance of the f 0 (980) signal is about 4.6σ.

Ablikim M.;Bai J. Z.;Bian J. G.;Cai X.;Chang J. F.;Chen H. S.;Chen H. X.;Chen J. C.;Chen Jin;Chen M. L.;Chen Y. B.;Chu Y. P.

Physical Review D Particles Fields Gravitation and Cosmology

2004

The decays of J / ψ and ψ (2 S) to n K S⁰ over(Λ, ̄) + c.c. are observed and measured for the first time, and the perturbative QCD "12%" rule is tested, based on 5.8 × 10 ⁷ J / ψ and 1.4 × 10 ⁷ ψ (2 S) events collected with BESII detector at the Beijing Electron-Positron Collider. No obvious enhancement near n over(Λ, ̄) threshold in J / ψ → n K S⁰ over(Λ, ̄) + c.c. is observed, and the upper limit on the branching ratio of J / ψ → K S⁰ X, X → n over(Λ, ̄) is determined. © 2007 Elsevier B.V. All rights reserved.

Ablikim M.;Bai J. Z.;Cai X.;Chen H. S.;Chen H. X.;Chen J. C.;Chen Jin;Chen Y. B.;Chu Y. P.;Deng Z. Y.;Du S. X.;Fang J.

Physics Letters Section B Nuclear Elementary Particle and High Energy Physics

2008

Using 5.8 × 10 ⁷ J / ψ events collected in the BESII detector, the radiative decay J / ψ → γ φ{symbol} φ{symbol} → γ K ⁺ K ^- K S⁰ K L⁰ is studied. The φ{symbol}φ{symbol} invariant mass distribution exhibits a near-threshold enhancement that peaks around 2.24 GeV/ c ² . A partial wave analysis shows that the structure is dominated by a 0 ^{- +} state (η (2225)) with a mass of 2.24 -0.02^+0.03-0.02^+0.03 GeV / c ² and a width of 0.19 ± 0.03 -0.04^+0.06 GeV / c ² . The product branching fraction is: Br (J / ψ → γ η (2225)) ṡ Br (η (2225) → φ{symbol} φ{symbol}) = (4.4 ± 0.4 ± 0.8) × 10 ^-4 . © 2008 Elsevier B.V. All rights reserved.

Ablikim M.;Bai J. Z.;Bai Y.;Cai X.;Chen H. S.;Chen H. X.;Chen J. C.;Chen Jin;Chen Y. B.;Chu Y. P.;Deng Z. Y.;Du S. X.

Physics Letters Section B Nuclear Elementary Particle and High Energy Physics

2008

The polarization of the χ c2 produced in ψ(2S) decays into γχ c2 is measured using a sample of 14 × 10 ⁶ ψ(2S) events collected by the BESII detector at the BEPC storage ring. A fit to the χ c2 production and decay angular distributions in ψ(2S) → γχ c2 , χ c2 → π ⁺ π ^- and K ⁺ K ^- yields values x = A 1 /A 0 = 2.08 ± 0.44 and y = A 2 /A 0 = 3.03 ± 0.66, with a correlation ρ= 0.92 between them, where A 0,1,2 are the χ c2 helicity amplitudes. The measurement agrees with a pure E1 transition, and M2 and E3 contributions do not differ significantly from zero.

Ablikim M.;Bai J. Z.;Bian J. G.;Cai X.;Chang J. F.;Chen H. S.;Chen H. X.;Chen J. C.;Chen Jin;Chen M. L.;Chen Y. B.;Chu Y. P.

Physical Review D Particles Fields Gravitation and Cosmology

2004

K*(892) ⁰ K̄*(892) ⁰ signals from χ cJ (J = 0, 1, 2) decays are observed for the first time using a data sample of 14 million ψ(2S) events accumulated in the BES II detector. The branching fractions B[χ cJ → K*(892) ⁰ K̄*(892) ⁰ ] (J = 0, 1, 2) are determined to be (1.78 ± 0.34 ± 0.34) × 10 ^-3 , (1.67 ± 0.32 ± 0.31) × 10 ^-3 , and (4.86 ± 0.56 ± 0.88) × 10 ^-3 for the χ c0 , χ c1 , and χ c2 decays, respectively, where the first errors are statistical and the second are systematic. The significances of these signals are about 4.7σ, 4.5σ, and 7.6σ, respectively.

Ablikim M.;Bai J. Z.;Bian J. G.;Cai X.;Chang J. F.;Chen H. S.;Chen H. X.;Chen J. C.;Chen Jin;Chen M. L.;Chen Y. B.;Chu Y. P.

Physical Review D Particles Fields Gravitation and Cosmology

2004

Using 58 million J/ψ and 14 million ψ(2S) decays obtained by the BES II experiment, the branching fraction of J/ψ→π ⁺ π ^- π ⁰ is determined. The result is (2.10±0.12) X10 ^-2 , which is significantly higher than previous measurements.

Bai J. Z.;Bian J. G.;Cai X.;Chang J. F.;Chen H. S.;Chen H. X.;Chen J.;Chen J. C.;Chen M. L.;Chen Y. B.;Chu Y. P.;Cui X. Z.

Physical Review D Particles Fields Gravitation and Cosmology

2004

Decays of the ψ(2S) into vector plus pseudoscalar meson final states have been studied with 14 × 10 ⁶ ψ(2S) events collected with the BESII detector. Branching fractions of ψ(2S) → Φη, Φη′, and ωη′, and upper limits of ψ(2S) → Φπ ⁰ and ωη are obtained: B(ψ(2S) → Φη) = (3.3 ± 1.1 ± 0.5) × 10 ^-5 , B(ψ(2S) → Φη′) = (3.1 ± 1.4 ± 0.7) × 10 ^-5 , and B(ψ-(2S) → ωη′) = (3.2 -2.0^+2.4 ± 0.7) × 10 ^-5 ; and B(ψ(2S) → Φπ ⁰ ) < 0.40 × 10 ^-5 , and B(ψ(2S) → ωη) < 3.1 × 10 ^-5 at the 90% C.L. These results are used to test the perturbative QCD "12% rule".

Ablikim M.;Bai J. Z.;Bian J. G.;Cai X.;Chang J. F.;Chen H. S.;Chen H. X.;Chen J. C.;Chen Jin;Chen M. L.;Chen Y. B.;Chu Y. P.

Physical Review D Particles Fields Gravitation and Cosmology

2004

Cross sections and form factors for e ⁺ e ^- → ωπ ⁰ , ρη, and ρη′ at center of mass energies of 3.650, 3.686, and 3.773 GeV are measured using data samples collected with the BESII detector at the BEPC. Also, the branching fractions of ψ(2S) → ωπ ⁰ , ρη, and ρη′ are determined to be (1.87 ^+0.68-0.62 ± 0.28) × 10 ^-5 , (1.78 ^+0.67-0.62 ± 0.17) × 10 ^-5 , and (1.87 ^+1.64-1.11 ± 0.33) × 10 ^-5 , respectively.

Ablikim M.;Bai J. Z.;Bian J. G.;Cai X.;Chang J. F.;Chen H. S.;Chen H. X.;Chen J. C.;Chen Jin;Chen M. L.;Chen Y. B.;Chu Y. P.

Physical Review D Particles Fields Gravitation and Cosmology

2004

Rare decay modes J / ψ → D s^- π ⁺ + c.c., J / ψ → D ^- π ⁺ + c.c., and J / ψ → over(D, ̄) ⁰ over(K, ̄) ⁰ + c.c. are searched for using 5.77 × 10 ⁷ J / ψ events collected with the BESII detector at the BEPC. No signal above background is observed. We present upper limits on the branching fractions of B (J / ψ → D s^- π ⁺ ) < 1.3 × 10 ^-4 , B (J / ψ → D ^- π ⁺ ) < 7.5 × 10 ^-5 , and B (J / ψ → over(D, ̄) ⁰ over(K, ̄) ⁰ ) < 1.7 × 10 ^-4 at the 90% confidence level. © 2008 Elsevier B.V. All rights reserved.

Ablikim M.;Bai J. Z.;Cai X.;Chen H. S.;Chen H. X.;Chen J. C.;Chen Jin;Chen Y. B.;Chu Y. P.;Deng Z. Y.;Du S. X.;Fang J.

Physics Letters Section B Nuclear Elementary Particle and High Energy Physics

2008

By analyzing approximately 33 pb ^-1 of sample data collected at and around 3.773 GeV with the BES-II detector at the BEPC collider, we directly measured the branching fractions for the neutral and charged D inclusive semimuonic decays to be BF (D ⁰ → μ ⁺ X) = (6.8 ± 1.5 ± 0.8) % and BF (D ⁺ → μ ⁺ X) = (17.6 ± 2.7 ± 1.8) %, and determined the ratio of the two branching fractions to be frac(BF (D ⁺ → μ ⁺ X), BF (D ⁰ → μ ⁺ X)) = 2.59 ± 0.70 ± 0.25. © 2008 Elsevier B.V. All rights reserved.

Ablikim M.;Bai J. Z.;Bai Y.;Cai X.;Chen H. S.;Chen H. X.;Chen J. C.;Chen Jin;Chen Y. B.;Chu Y. P.;Deng Z. Y.;Du S. X.

Physics Letters Section B Nuclear Elementary Particle and High Energy Physics

2008