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Register a new userMeasurement of Absolute Hadronic Branching Fractions of D Mesons and e^+ e^- --> D D-bar Cross Sections at the psi(3770)
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Using 281 /pb of e^+ e^- collisions recorded at the psi(3770) resonance with the CLEO-c detector at CESR, we determine absolute hadronic branching fractions of charged and neutral D mesons using a double tag technique. Among measurements for three D^0 and six D^+ modes, we obtain reference branching fractions B(D^0 --> K^-pi^+) = (3.891 +- 0.035 +- 0.059 +- 0.035)% and B(D^+ --> K^-pi^+pi^+) = (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 sigma(e+e- --> D^0 D^0-bar) = (3.66+- 0.03 +- 0.06) nb and sigma(e+e- --> D^+ D^-) = (2.91+- 0.03 +- 0.05) nb at a center of mass energy, E_cm = 3774 +- 1 MeV.
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We report new measurements of the cross sections for the production of D Dbar final states at the psi(3770) resonance. Our data sample consists of an integrated luminosity of 2.93/fb of e+e- annihilation data produced by the BEPCII collider and colle
cted and analyzed with the BESIII detector. We exclusively reconstruct three D0 and six D+ hadronic decay modes and use the ratio of the yield of fully reconstructed D Dbar events (double tags) to the yield of all reconstructed D or Dbar mesons (single tags) to determine the number of D0 D0bar and D+D- events, benefiting from the cancellation of many systematic uncertainties. Combining these yields with an independent determination of the integrated luminosity of the data sample, we find the cross sections to be sigma(e+e- --> D0 D0bar)=(3.615 +- 0.010 +- 0.038) nb and sigma(e+e- --> D+D-)=(2.830 +- 0.011 +- 0.026) nb, where the uncertainties are statistical and systematic, respectively.
We report first measurements of e+e- -> D(*)+D(*)- processes far above threshold. The cross-sections for e+e- -> DT*+DL*- and e+e- -> D+D*T- at sqrt{s}=10.58 GeV/c2 are measured to be 0.55 +- 0.03 +- 0.05 pb and 0.62 +- 0.03 +- 0.06 pb, respectively. We set upper limits on the cross-sections for e+e- -> DT*+DT*-, e+e- -> DL*+DL*-, e+e- -> D+D*L- and e+e- -> D+D- processes. The analysis is based on 88.9 fb-1 of data collected by the Belle experiment at the KEKB e+e- asymmetric collider.
Utilizing the full CLEO-c data sample of 818 pb$^{-1}$ of $e^+e^-$ data taken at the $psi(3770)$ resonance, we update our measurements of absolute hadronic branching fractions of charged and neutral $D$ mesons. We previously reportedresults from subsets of these data. Using a double tag technique we obtain branching fractions for three $D^0$ and six $D^+$ modes, including the reference branching fractions $mathcal{B} (D^0to K^-pi^+)=(3.934 pm 0.021 pm 0.061)%$ and $mathcal{B} (D^+ to K^- pi^+pi^+)=(9.224 pm 0.059 pm 0.157)%$. The uncertainties are statistical and systematic, respectively. In these measurements we include the effects of final-state radiation by allowing for additional unobserved photons in the final state, and the systematic errors include our estimates of the uncertainties of these effects. Furthermore, using an independent measurement of the luminosity, we obtain the cross sections $sigma(e^+e^-to D^0overline{D}{}^0)=(3.607pm 0.017 pm 0.056) mathrm{nb}$ and $sigma(e^+e^-to D^+D^-)=(2.882pm 0.018 pm 0.042) mathrm{nb}$ at a center of mass energy, $E_mathrm{cm} = 3774 pm 1$ MeV.
Using 2.93 fb$^{-1}$ of $e^+e^-$ collision data collected with the BESIII detector at a center-of-mass energy of 3.773 GeV, we measure the absolute branching fractions of the decays $D^0to K^-e^+ u_e$ and $D^+to bar K^0 e^+ u_e$ to be $(3.567pm0.031_{rm stat}pm 0.025_{rm syst})%$ and $(8.68pm0.14_{rm stat}pm 0.16_{rm syst})%$, respectively. Starting with the process $e^+e^-to Dbar{D}$, a new reconstruction method is employed to select events that contain candidates for both $Dto bar Ke^+ u_e$ and $bar Dto Ke^-bar u_e$ decays. The branching fractions reported in this work are consistent within uncertainties with previous BESIII measurements that selected events containing $Dto bar Ke^+ u_e$ and hadronic $bar D$ decays. Combining our results with the lifetimes of the $D^0$ and $D^+$ mesons and the previous BESIII measurements leads to a ratio of the two decay partial widths of $frac{bar Gamma_{D^0to K^{-}e^+ u_{e}}}{bar Gamma_{D^{+}to bar K^{0}e^+ u_{e}}}=1.039pm0.021$. This ratio supports isospin symmetry in the $D^0to K^-e^+ u_e$ and $D^+to bar K^0 e^+ u_e$ decays within $1.9sigma$.
Several intermediate states of the reaction channels $e^{+}e^{-} rightarrow pi^{+} pi^{-} D^{0} bar{D}^{0}$ and $e^{+}e^{-} rightarrow pi^{+} pi^{-} D^{+}D^{-}$ are studied using the data samples collected with the BESIII detector at center-of-mass energies above 4.08 GeV. For the first time in this final state, a $psi(3770)$ signal is seen in the $Dbar{D}$ invariant mass spectrum, with a statistical significance of $5.2sigma$ at $sqrt{s} = 4.42$ GeV. There is also evidence for this resonance at $sqrt{s}$ = 4.26 and 4.36 GeV with statistical significance of 3.2$sigma$ and 3.3$sigma$, respectively. In addition, the Born cross section of $e^{+}e^{-}to pi^{+}pi^{-}psi(3770)$ is measured. The proposed heavy-quark-spin-symmetry partner of the $X(3872)$, the state $X_{2}(4013)$, is also searched for in the $Dbar{D}$ invariant mass spectra. No obvious signal is found. The upper limit of the Born cross section of the process $e^{+}e^{-}to rho^{0}X_{2}(4013)$ combined with the branching fraction is measured. Also, the processes $e^{+}e^{-}to D_{1}(2420)bar{D} + c.c.$ are investigated. The neutral mode with $D_{1}(2420)^{0}to D^{0}pi^{+}pi^{-}$ is reported with statistical significance of 7.4$sigma$ at $sqrt{s} = 4.42$ GeV for the first time, and evidence with statistical significance of 3.2$sigma$ and 3.3$sigma$ at $sqrt{s}$ = 4.36 and 4.60 GeV is seen, respectively. No evident signal for the process $e^{+}e^{-}to D_{1}(2420)^{0}bar{D}^{0} + c.c., D_{1}(2420)^{0}to D^{*+}pi^{-}$ is reported. Evidence for $e^{+}e^{-}to D_{1}(2420)^{+}D^{-} +~c.c., D_{1}(2420)^{+}to D^{+}pi^{+}pi^{-}$ is reported with statistical significance of 3.1$sigma$ and 3.0$sigma$ at $sqrt{s}$ = 4.36 and 4.42 GeV, respectively.
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