Results are presented on J / ψ radiative decays to π ⁺ π ^- and π ⁰ π ⁰ based on a sample of 58M J / ψ events taken with the BES II detector. Partial wave analyses are carried out using the relativistic covariant tensor amplitude method in the 1.0 to 2.3 GeV / c ² π π mass range. There are conspicuous peaks due to the f 2 (1270) and two 0 ^{+ +} states in the 1.45 and 1.75 GeV/ c ² mass regions. The first 0 ^{+ +} state has a mass of 1466 ± 6 ± 20 MeV / c ² , a width of 108 -11⁺¹⁴ ± 25 MeV / c ² , and a branching fraction B (J / ψ → γ f 0 (1500) → γ π ⁺ π ^- ) = (0.67 ± 0.02 ± 0.30) × 10 ^-4 . Spin 0 is strongly preferred over spin 2. The second 0 ^{+ +} state peaks at 1765 -3⁺⁴ ± 13 MeV / c ² with a width of 145 ± 8 ± 69 MeV / c ² . If this 0 ^{+ +} is interpreted as coming from f 0 (1710), the ratio of its branching fractions to ππ and K over(K, ̄) is 0.41 -0.17^+0.11 . © 2006 Elsevier B.V. All rights reserved.

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

Physics Letters Section B Nuclear Elementary Particle and High Energy Physics

2006

Using the data sample of about 33 pb ^-1 collected at and around 3.773 GeV with the BES-II detector at the BEPC collider, we have studied inclusive over(K, ̄) ⁰ / K ⁰ and K ^* (892) ^∓ decays of D ⁰ and D ⁺ mesons. The branching fractions for the inclusive over(K, ̄) ⁰ / K ⁰ and K ^* (892) ^- decays are measured to be BF (D ⁰ → over(K, ̄) ⁰ / K ⁰ X) = (47.6 ± 4.8 ± 3.0) %, BF (D ⁺ → over(K, ̄) ⁰ / K ⁰ X) = (60.5 ± 5.5 ± 3.3) %, BF (D ⁰ → K ^{* -} X) = (15.3 ± 8.3 ± 1.9) % and BF (D ⁺ → K ^{* -} X) = (5.7 ± 5.2 ± 0.7) %. The upper limits of the branching fractions for the inclusive K ^* (892) ⁺ decays are set to be BF (D ⁰ → K ^{* +} X) < 3.6 % and BF (D ⁺ → K ^{* +} X) < 20.3 % at 90% confidence level. © 2006 Elsevier B.V. All rights reserved.

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

Physics Letters Section B Nuclear Elementary Particle and High Energy Physics

2006

The absolute branching fraction for the decay D ⁺ → over(K, ̄) ⁰ μ ⁺ ν μ is determined using 5321 ± 149 ± 160 singly tagged D ^- sample from the data collected around sqrt(s) = 3.773  GeV with the BESII detector at the BEPC collider. In the system recoiling against the singly tagged D ^- mesons, 28.7 ± 6.4 events for D ⁺ → over(K, ̄) ⁰ μ ⁺ ν μ are observed. These yield the absolute branching fraction to be BF (D ⁺ → over(K, ̄) ⁰ μ ⁺ ν μ ) = (10.3 ± 2.3 ± 0.8) %. The ratio of the two partial widths for the decays D ⁰ → K ^- μ ⁺ ν μ and D ⁺ → over(K, ̄) ⁰ μ ⁺ ν μ is determined to be Γ (D ⁰ → K ^- μ ⁺ ν μ ) / Γ (D ⁺ → over(K, ̄) ⁰ μ ⁺ ν μ ) = 0.87 ± 0.24 ± 0.15. © 2006 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

2007

Using 14M ψ (2 S) events accumulated by BESII at the BEPC, a covariant helicity amplitude analysis is performed for ψ (2 S) → π ⁺ π ^- J / ψ, J / ψ → μ ⁺ μ ^- . The π ⁺ π ^- mass spectrum, distinctly different from phase space, suggests σ production in this process. Two different theoretical schemes are used in the global fit to the data. The results are consistent with the existence of the σ. The σ pole position is determined to be (552 -106^{+   84} ) - i (232 -72⁺⁸¹ )  MeV / c ² . © 2006 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.;Cui X. Z.;Deng Z. Y.;Du S. X.

Physics Letters Section B Nuclear Elementary Particle and High Energy Physics

2007

Using the data sets of 17.3 pb ^-1 collected at sqrt(s) = 3.773   GeV and 6.5 pb ^-1 collected at sqrt(s) = 3.650   GeV with the BESII detector at the BEPC collider, we have measured the observed cross sections for 18 exclusive light hadron final states produced in e ⁺ e ^- annihilation at the two energy points. © 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

2007

By analyzing the R values measured at 68 energy points in the energy region between 3.650 and 3.872 GeV reported in our previous paper, we have precisely measured the mass, the total width and the leptonic width of the ψ (3770) resonance to be M ψ (3770) = 3772.4 ± 0.4 ± 0.3   MeV, Γ ψ (3770)^tot = 28.5 ± 1.2 ± 0.2   MeV and Γ ψ (3770)^{e e} = 277 ± 11 ± 13   eV, respectively. We have measured the leptonic branching fraction of the ψ (3770) decays and the ψ (3770) production cross section at its peak to be B [ψ (3770) → e ⁺ e ^- ] = (0.97 ± 0.03 ± 0.05) × 10 ^-5 and σ ^prd [e ⁺ e ^- → ψ (3770)] = 10.0 ± 0.3 ± 0.5  nb, respectively. The latter one results in the corresponding observed cross section of σ ^obs [e ⁺ e ^- → ψ (3770)] = 7.2 ± 0.2 ± 0.4  nb. We have also measured R uds = 2.121 ± 0.023 ± 0.084 for the continuum light hadron production in the region from 3.650 to 3.872 GeV. © 2007 Elsevier B.V. All rights reserved.

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

Physics Letters Section B Nuclear Elementary Particle and High Energy Physics

2007

By analyzing the data sets of 17.3 pb ^-1 taken at sqrt(s) = 3.773  GeV and 6.5 pb ^-1 taken at sqrt(s) = 3.650  GeV with the BESII detector at the BEPC collider, we have measured the observed cross sections for 12 exclusive light hadron final states produced in e ⁺ e ^- annihilation at the two energy points. We have also set the upper limits on the observed cross sections and the branching fractions for ψ (3770) decay to these final states at 90% C.L. © 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

2007

We report measurements of the observed cross sections for e ⁺ e ^- → ωπ ⁺ π ^- , ωK ⁺ K ^- , ωpp̄, K ⁺ K ^- ρ ⁰ π ⁰ , K ⁺ K ^- ρ ⁺ π ^- +c.c., K ^*0 K ^- π ⁺ π ⁰ +c.c., K ^*+ K ^- π ⁺ π ^- +c.c., φπ ⁺ π ^- π ⁰ and ΛΛ̄π ⁰ at √s = 3.773 and 3.650 GeV. Upper limits (90% C.L.) are given for observed cross sections and for ψ(3770) decay branching fractions for production of these final states. These measurements are made by analyzing the data sets of 17.3 pb ^-1 collected at √s = 3.773 GeV and 6.5 pb ^-1 collected at √s = 3.650 GeV with the BES-II detector at the BEPC collider. © 2007 Springer-Verlag / Società Italiana di Fisica.

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.

European Physical Journal C

2007

With singly-tagged over(D, ̄) samples selected from the data collected at and around 3.773 GeV with the BESII detector at the BEPC collider, we have measured the branching fractions for the inclusive K ^± decays of D ⁺ and D ⁰ mesons, which are BF (D ⁺ → K ^- X) = (24.7 ± 1.3 ± 1.2) %, BF (D ⁺ → K ⁺ X) = (6.1 ± 0.9 ± 0.4) %, BF (D ⁰ → K ^- X) = (57.8 ± 1.6 ± 3.2) % and BF (D ⁰ → K ⁺ X) = (3.5 ± 0.7 ± 0.3) %, respectively. We have also measured the branching fractions for the inclusive semileptonic decays of D ⁺ and D ⁰ mesons to be BF (D ⁺ → e ⁺ X) = (15.2 ± 0.9 ± 0.8) % and BF (D ⁰ → e ⁺ X) = (6.3 ± 0.7 ± 0.4) %. These yield the ratio of their partial widths to be Γ (D ⁺ → e ⁺ X) / Γ (D ⁰ → e ⁺ X) = 0.95 ± 0.12 ± 0.07. © 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

2007

By tagging the largest energy of the assumed kaon in the final states of e ⁺ e ^- → hadrons, we measured the cross sections for e ⁺ e ^- → hadrons | non- D over(D, ̄) in the range from 3.65 to 3.87 GeV. Analyzing these cross sections yields the branching fraction for the decay ψ (3770) → non- D over(D, ̄) to be BF [ψ (3770) → non- D over(D, ̄)] = (15.1 ± 5.6 ± 1.8) %, and the observed non-D over(D, ̄) and D over(D, ̄) cross sections to be σ had-non- D over(D, ̄)^obs = (1.08 ± 0.40 ± 0.15)  nb and σ D over(D, ̄)^obs = (6.07 ± 0.40 ± 0.35)  nb, respectively, at the center-of-mass energy E cm = 3.7724  GeV. © 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