اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدMeasurement of the e+e- -> D(*)+D(*)- cross-sections
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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.
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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.
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.
Using 2.92 fb$^{-1}$ of electron-positron annihilation data collected at a center-of-mass energy of $sqrt{s}= 3.773$ GeV with the BESIII detector, we present an improved measurement of the branching fraction $mathcal{B}(D^+ to omega e^+ u_{e}) = (1.
63pm0.11pm0.08)times 10^{-3}$. The parameters defining the corresponding hadronic form factor ratios at zero momentum transfer are determined for the first time, we measure them to be $r_V = 1.24pm0.09pm0.06$ and $r_2 = 1.06pm0.15 pm 0.05$. The first and second uncertainties are statistical and systematic, respectively. We also search for the decay $D^+ to phi e^+ u_{e}$. An improved upper limit $mathcal{B}(D^+ to phi e^+ u_{e}) < 1.3 times 10^{-5}$ is set at 90% confidence level.
Using 1.8 million DDbar pairs and a neutrino reconstruction technique, we have studied the decays D^0 -> K^- e^+ nu_e, D^0 -> pi^- e^+ nu_e, D^+ -> Kbar^0 e^+ nu_e, and D^+ -> pi^0 e^+ nu_e. We find B(D^0 -> pi^- e^+ nu_e) = 0.299(11)(9)%, B(D^+ -> p
i^0 e^+ nu_e) = 0.373(22)(13)%, B(D^0 -> K^- e^+ nu_e) = 3.56(3)(9)%, and B(D^+ -> Kbar^0 e^+ nu_e) = 8.53(13)(23)%. In addition, form factors are studied through fits to the partial branching fractions obtained in five q^2 ranges. By combining our results with recent unquenched lattice calculations, we obtain |Vcd| = 0.217(9)(4)(23) and |Vcs| = 1.015(10)(11)(106).
A simultaneous fit is performed to the $e^+e^-to Lambda_c^+Lambda_c^-$ cross section data measured by Belle and BESIII from threshold up to 5.4 GeV. In order to accommodate both the BESIII measurement near threshold and the Belle observation of a res
onance $Y(4630)$, we build a composite PDF with a Breit-Wigner resonance and a continuum contribution to model the full cross section line shape of $e^+e^-to Lambda_c^+Lambda_c^-$. The fit gives a mass of $M=[4636.1_{-7.2}^{+9.8} ($stat$)pm 8.0($syst$)]$~MeV/$c^2$, a width of $Gamma_{rm tot}=[34.5_{-16.2}^{+21.0} ($stat$)pm 5.6($syst$)]$~MeV, and $Gamma_{e^+ e^-}mathcal{B}[Y(4630)toLambda_c^+Lambda_c^-]=[18.3_{-6.1}^{+8.8} ($stat$)pm 1.1($syst$)]$~eV/$c^2$ for the resonance. The width of $Y(4630)$ from our study is narrower than the previous Belle fit. The mass and width of $Y(4630)$ also show good agreement with a vector resonance $Y(4626)$ recently observed in $D_s^+D_{s1}(2536)^-$ by Belle.
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