Recent Results on $psi(3770)$ Physics at BES

There are about 33, 6.5 and 1.0 pb$^{-1}$ of $e^+e^-$ annihilation data have been taken around the center-of-mass energies of $sqrt s=$ 3.773 GeV, at $sqrt s=$ 3.650 GeV and at $sqrt s=$ 3.6648 GeV, respectively, with the BES-II detector at the BEPC collider. By analyzing these data sets, we have measured the branching fraction for $psi(3770)to$ non-$Dbar D$ by several different methods; and have observed an anomalous line shape of $sigma^{e^+e^-to{rm hadrons}}$ in energy region from 3.65 to 3.87 GeV; and have measured the line shapes of the $D^+D^-$, $D^0bar D^0$ and $Dbar D$ production and together with the ratios of the production rates of $D^+D^-$ and $D^0bar D^0$ in $e^+e^-$ annihilation around the $psi(3770)$ resonance.

Experimental studies of the $pi^+pi^-pi^+pi^-pi^0$, $K^+K^-pi^+pi^-pi^0$ and $pbar ppi^+pi^-pi^0$ final states produced in $e^+e^-$ annihilation at $sqrt{s}=$ 3.773 and 3.650 GeV

We report measurements of the observed cross sections for $e^+e^-toomega pi^+pi^-$, $omega K^+K^-$, $omega pbar p$, $K^+K^-rho^0pi^0$, $K^+K^-rho^+pi^-+c.c.$, $K^{*0}K^-pi^+pi^0+c.c.$, $K^{*+}K^-pi^+pi^-+c.c.$, $phipi^+pi^-pi^0$ and $Lambda bar Lambda pi^0$ at $sqrt s=$ 3.773 and 3.650 GeV. Upper limits (90% C.L.) are given for observed cross sections and for $psi(3770)$ 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 $sqrt{s}=3.773$ GeV and 6.5 pb$^{-1}$ collected at $sqrt{s}=3.650$ GeV with the BES-II detector at the BEPC collider.