The decay $Z_c(3900)^pmtoomegapi^pm$ is searched for using data samples collected with the BESIII detector operating at the BEPCII storage ring at center-of-mass energies $sqrt{s}=4.23$ and $4.26$~GeV. No significant signal for the $Z_c(3900)^pm$ is
found, and upper limits at the 90% confidence level on the Born cross section for the process $e^+e^-to Z_c(3900)^pmpi^mptoomegapi^+pi^-$ are determined to be $0.26$ and $0.18$ pb at $sqrt{s}=4.23$ and 4.26 GeV, respectively.
The BESIII experiment in Beijing takes data in $tau$-charm domain since 2009. For the moment the world largest samples of $J/psi$, $psi(3686)$, $psi(3770)$ and $psi(4040)$ data have been collected. Hadron spectroscopy is a unique way to access QCD, w
hich is one of the most important physics goals of BESIII. Experimental search of new forms of hadrons and subsequent investigation of their properties would provide validation of and valuable input to the quantitative understanding of QCD. The key to success lies in high levels of precision during the measurement and high statistics in the recorded data set complemented with sophisticated analysis methods. Partial wave analysis (PWA) is a powerful tool to study the hadron spectroscopy, that allows one to extract the resonances spin-parity, mass, width and decay properties with high sensitivity and accuracy. In this poster, we present the working PWA framework of BESIII -- GPUPWA and the recent results of PWA of $J/psitogammaetaeta$. GPUPWA is a PWA framework for high statistics partial wave analyses harnessing the GPU parallel computing.
Using samples of 2.25*10^8 J/psi events and 1.06*10^8 psi events collected with the BES III detector, we study the f0(980) to a0(980) and a0(980) to f0(980) transitions in the processes J/psi --> phi f0(980) --> phi a0(980) and chi_c1 --> pi^0 a0(980
) --> pi^0 f0(980), respectively. Evidence for f0(980) --> a0(980) is found with a significance of 3.4 sigma, while in the case of a0(980) --> f0(980) transition, the significance is 1.9 sigma. Measurements and upper limits of both branching ratios and mixing intensities are determined.
Recent BES results on light scalars are reported in this talk, including the observation of a charged kappa decaying to K pi0 with 5.8 * 10^7 J/psi data at BES II and the direct measurements of a0(980)-f0(980) mixing in the processes J/psi --> phi f0
(980) --> phi a0(980) --> phi eta pi0 and chi_c1 --> pi0 a0(980) --> pi0 f0(980) --> pi0 pi+ pi- with 2.26 * 10^8 J/psi data and 1.06 * 10^8 psi data at BES III.
Using a sample of 1.06 times 10^8 psi^{prime} decays collected by the BESIII detector, chi_{c0} and chi_{c2} decays into pi^0pi^0 and etaeta are studied. The branching fraction results are Br(chi_{c0}topi^0pi^0)=(3.23pm 0.03pm0.23 pm 0.14)times 10^{-
3}, Br(chi_{c2}topi^0pi^0)=(8.8pm 0.2pm 0.6pm0.4)times 10^{-4}, Br(chi_{c0}toetaeta)=(3.44pm 0.10pm0.24 pm0.2)times 10^{-3}, and Br(chi_{c2}toetaeta)=(6.5pm 0.4pm 0.5pm 0.3)times 10^{-4}, where the uncertainties are statistical, systematic due to this measurement, and systematic due to the branching fractions of psi^{prime}togammachi_{cJ}, respectively. The results provide information on the decay mechanism of chi_c states into pseudoscalars.
Using $5.8 times 10^7 J/psi$ events collected in the BESII detector, the radiative decay $J/psi to gamma phi phi to gamma K^+ K^- K^0_S K^0_L$ is studied. The $phiphi$ invariant mass distribution exhibits a near-threshold enhancement that peaks aroun
d 2.24 GeV/$c^{2}$. A partial wave analysis shows that the structure is dominated by a $0^{-+}$ state ($eta(2225)$) with a mass of $2.24^{+0.03}_{-0.02}{}^{+0.03}_{-0.02}$ GeV/$c^{2}$ and a width of $0.19 pm 0.03^{+0.06}_{-0.04}$ GeV/$c^{2}$. The product branching fraction is: $Br(J/psi to gamma eta(2225))cdot Br(eta(2225)to phiphi) = (4.4 pm 0.4 pm 0.8)times 10^{-4}$.
The decay $J/psi to omega p bar p$ is studied using a $5.8 times 10^7$ $J/psi$ event sample accumulated with the BES II detector at the Beijing electron-positron collider. The decay branching fraction is measured to be $B(J/psi to omega p bar p)=(9.8
pm 0.3pm 1.4)times 10^{-4}$. No significant enhancement near the $pbar p$ mass threshold is observed, and an upper limit of $B(J/psi to omega X(1860))B(X(1860)to pbar p)$$ $$< 1.5 times 10^{-5}$ is determined at the 95% confidence level, where X(1860) designates the near-threshold enhancement seen in the $pbar p$ mass spectrum in $J/psi to gamma p bar p$ decays.
