Observation of chi(cJ) -> Lambda(Lambda)over-bar(eta)

By analyzing (448.1 +/- 2.9) x 10(6) psi(3686) events collected with the BESIII detector operating at the BEPCII collider, the decays of chi(cJ) -> Lambda(Lambda) over bar (eta) (J = 0, 1, and 2) are observed for the first time with statistical significances of 13.9 sigma, 6.7 sigma, and 8.2 sigma, respectively. The product branching fractions of psi(3686) -> gamma chi(cJ) and chi(cJ) -> Lambda(Lambda) over bar (eta) are measured. Dividing by the world averages of the branching fractions of psi(3686) -> gamma chi(cJ), the branching fractions of chi(cJ) -> Lambda(Lambda) over bar (eta) decays are determined to be (2.31 +/- 0.30 +/- 0.21) x 10(-4), (5.86 +/- 1.38 +/- 0.68) x 10(-5), and (1.05 +/- 0.21 +/- 0.15) x 10(-4) for J = 0, 1 and 2, respectively, where the first uncertainties are statistical and the second systematic

Measurement of the e(+) e(-) -> omega pi(0)pi(0) cross section at center-of-mass energies from 2.0 to 3.08 GeV

The cross section of the process e(+)e(-) -> omega pi(0)pi(0) is measured at nineteen center-of-mass energies from 2.0 to 3.08 GeV using data collected with the BESIII detector at the BEPCII storage ring. A resonant structure around 2.20 GeV is observed with statistical significance larger than 5 sigma. Using a coherent fit to the cross section line shape, the mass and width are determined to be M = 2222 +/- 7 +/- 2 MeV/c(2) and Gamma = 59 +/- 30 +/- 6 MeV, respectively, where the first uncertainties are statistical and the second ones are systematic

Study of the resonance structures in the process e(+) e(-) -> pi(+) pi(-) J/psi

Using about 23 fb(-1) of data collected with the BESIII detector operating at the BEPCII storage ring, a precise measurement of the e(+) e(-) -> pi(+) pi(-) J/psi Born cross section is performed at center-of-mass energies from 3.7730 to 4.7008 GeV. Two structures, identified as the Y(4220) and the Y(4320) states, are observed in the energy-dependent cross section with a significance larger than 10 sigma. The masses and widths of the two structures are determined to be (M,(sic)) = (4221.4 +/- 1.5 +/- 2.0 MeV=c(2); 41.8 +/- 2.9 +/- 2.7 MeV) and (M,(sic)) = (4298 +/- 12 +/- 26 MeV=c(2); 127 +/- 17 +/- 10 MeV)respectively. A small enhancement around 4.5 GeV with a significance about 3s, compatible with the psi(4415), might also indicate the presence of an additional resonance in the spectrum. The inclusion of this additional contribution in the fit to the cross section affects the resonance parameters of the Y(4320) state

Measurement of A baryon polarization in e(+) e(-) -> Lambda(Lambda)over-bar at root s=3.773 GeV

Using a data sample of psi(3770) events collected with the BESIII detector at BEPCII corresponding to an integrated luminosity of 2.9 fb-1, we report a measurement of A spin polarization in e+ e- -> Lambda(Lambda) over bar at = root s = 3.773 GeV. The significance of polarization is found to be 2 sigma including the systematic uncertainty, which implies a zero phase between the transition amplitudes of the Lambda(Lambda) over bar helicity states. This phase can be interpreted in terms of psionic form factors, and is determined to be Delta Phi(Psi) = Phi(Psi)(E) - Phi(Psi)(M) = (71(-46)(+66) +/- 5)degrees. Similarly, the ratio between the form factors is found to be R-psi = vertical bar G(E)(Psi)/G(M)(Psi)vertical bar = 0.48(-0.35)(+0.21) +/- 0.03. The first uncertainties are statistical and the second systematic