Measurement of absolute hadronic branching fractions of D̅ mesons and e⁺e^-→DD̅ cross sections at the ψ(3770)

Using 281  pb^-1 of e⁺e^- collisions recorded at the ψ(3770) resonance with the CLEO-c detector at CESR (Cornell Electron Storage Ring), we determine absolute hadronic branching fractions of charged and neutral D mesons using a double tag technique. Among measurements for three D⁰ and six D⁺ modes, we obtain reference branching fractions B(D⁰→K^-π⁺)=(3.891±0.035±0.059±0.035)% and B(D⁺→K^-π⁺π⁺)=(9.14±0.10±0.16±0.07)%, where the first uncertainty is statistical, the second is all systematic errors other than final-state radiation (FSR), and the third is the systematic uncertainty due to FSR. We include FSR in these branching fractions by allowing for additional unobserved photons in the final state. Using an independent determination of the integrated luminosity, we also extract the cross sections σ(e⁺e^-→D⁰D̅ ⁰)=(3.66±0.03±0.06)  nb and σ(e⁺e^-→D⁺D^-)=(2.91±0.03±0.05)  nb at a center-of-mass energy, E_cm=3774±1  MeV.