Study of Scalar Mesons at BES

Abstract

Partial wave analyses have been performed on BES data to study scalar mesons. There is evidence for the $\kappa$ near the $K\pi$ threshold and the pole position is $(760\sim 840)-$i$(310\sim 420)$ MeV. The $\sigma$ peak is seen in $\omega {\pi }^{+}{\pi }^{-}$ and gives an accurate pole position, $(541\pm 39)-$i$(252\pm 42)$ MeV. The $f_0(980)$ is seen in both $\varphi {\pi }^{+}{\pi }^{-}$ and $\varphi K^{+}{K}^{-}$ data. Parameters of the Flatt\' e formula for $f_0(980)$ are: $M=965\pm 8(sta)\pm 6(sys)$ MeV, $g_1=165\pm 10(sta)\pm 15(sys)$ MeV, $g_2/g_1=4.21\pm 0.25(sta)\pm 0.21(sys)$. The $J/\psi \to \varphi {\pi }^{+}{\pi }^{-}$ data require $f_0(1790)\to {\pi }^{+}{\pi }^{-}$, distinct from $f_0(1710)\to K^{+}{K}^{-}$. Also $f_0(1370)$ is seen clearly in $\varphi {\pi }^{+}{\pi }^{-}$ data.

arXiv commentParallel Talk presented at ICHEP04. 4 pages and 6 figures