Measurements of σ(e+e- → hadrons) and B(ψ(3770) → D(D)over-bar, non-D(D)over-bar)

Precision measurements of R values (R = sigma(B)(had)/sigma(B)(mu+mu-), where sigma(B)(had) and sigma(B)(mu+mu-) are Born order cross sections for inclusive hadron production and for muon pair production in e+e- annihilation, respectively.) at low energy region are important for precise test of the Standard Model [1]. On the other hand, the measurements of the R values at the center-of-mass energies around 3.6574 and at 3.773 GeV can be used to determine the branching fractions for psi(3770) -> D-0(D) over bar (0),D+D-,D (D) over bar), and for psi(3770) -> non-D (D) over bar. In this paper, we present a more precision measurement of the R values at the center-of-mass energies of 3.650, 3.6648 and 3.773 GeV, and measurements of the branching fractions for psi(3770) -> D-0,(D) over bar (0), D+D-, D (D) over bar, and for psi(3770) -> non-D (D) over bar with the data taken with the BES-II detector at the BEPC Collider.