Using the CLEO-c detector at the Cornell Electron Storage Ring, we have measured inclusive and exclusive cross sections for the production of D+, D0 and Ds+ mesons in e+e- annihilations at thirteen center-of-mass energies between 3.97 and 4.26 GeV. Exclusive cross sections are presented for final states consisting of two charm mesons (DD, D*D, D*D*, Ds+Ds-, Ds*+Ds-, and Ds*+Ds*-) and for processes in which the charm-meson pair is accompanied by a pion. No enhancement in any final state is observed at the energy of the Y(4260).
Exclusive cross section for two body neutral non-strange charm mesons.
Exclusive cross section for two body charged non-strange charm mesons.
Exclusive cross section for two body strange charm mesons.
Using the CLEO III detector, we measure absolute cross sections for e+e- --> hadrons at seven center-of-mass energies between 6.964 and 10.538 GeV. The values of R, the ratio of hadronic and muon pair production cross sections, are determined within 2% total r.m.s. uncertainty.
Measured values of R as a function of CM energy. The first DSYS error is the correlated uncertainty and the second is the uncorrelated.
We have updated our measurement of the cross section for e^+e^- -> psi(3770) -> hadrons, our publication "Measurement of sigma(e^+e^- -> psi(3770) -> hadrons) at E_{c.m.} = 3773 MeV", arXiv:hep-ex/0512038, Phys.Rev.Lett.96, 092002 (2006). Simultaneous with this arXiv update, we have published an erratum in Phys.Rev.Lett.104, 159901 (2010). There, and in this update, we have corrected a mistake in the computation of the error on the difference of the cross sections for e^+e^- -> psi(3770) -> hadrons and e^+e^- -> psi(3770) -> DDbar. We have also used a more recent CLEO measurement of cross section for e^+e^- -> psi(3770) -> DDbar. From this, we obtain an upper limit on the branching fraction for psi(3770) -> non-DDbar of 9% at 90% confidence level.
Measured cross section for the process E+ E- --> PSI(3770) --> hadrons.
The CLEO experiment at the CESR collider has used 13.7 fb$^{-1}$ of data to search for the production of the $\Omega_c^0$ (css-ground state) in $e^{+}e^{-}$ collisions at $\sqrt{s} \simeq 10.6$ {\rm GeV}. The modes used to study the $\Omega_c^0$ are $\Omega^- \pi^+$, $\Omega^- \pi^+ \pi^0$, $\Xi^- K^- pi^+ \pi^+$, $\Xi^0 K^- pi^+$, and $\Omega^- \pi^+ \pi^- \pi^+$. We observe a signal of 40.4$\pm$9.0(stat) events at a mass of 2694.6$\pm$2.6(stat)$\pm$1.9(syst) {\rm MeV/$c^2$}, for all modes combined.
Cross section times branching ratio.
We describe a search for psi(3770) decay to two-body non-DDbar final states in e+e- data produced by the CESR collider and analyzed with the CLEO-c detector. Vector-pseudoscalar production of Rho0Pi0, Rho+Pi-, OmegaPi0, PhiPi0, RhoEta, OmegaEta, PhiEta, RhoEtaPrime, OmegaEtaPrime, PhiEtaPrime, Kstar0 K0bar, and Kstar+K- is studied along with that of BOnePi (BOne0Pi0 and BOne+Pi-) and Pi+Pi-Pi0. A statistically significant signal is found for PhiEta, at an excess cross section of (2.4 +- 0.6) pb [Gamma_{PhiEta} (psi(3770)) =(74 +- 16)Mev], and a suggestive suppression of Pi+Pi-Pi0 and RhoPi. We conclude with form factor determinations for OmegaPi0, RhoEta, and RhoEtaPrime.
Cross sections at 3.671 and 3.773 GeV.
First results of the study of the process e+e- \to 4\pi by the CMD-2 collaboration at VEPP-2M are presented for the energy range 1.05--1.38 GeV. Using an integrated luminosity of 5.8 pb^{-1}, energy dependence of the processes e+e- \to \pi^+\pi^- 2\pi^0 and e+e- \to 2\pi^+ 2\pi^- has been measured. Analysis of the differential distributions demonstrates the dominance of the a_1\pi and \omega\pi intermediate states. Upper limits for the contributions of other alternative mechanisms are also placed.
Energy dependence of the cross section for the 2PI+ 2PI- final state. Statistical errors only.
Energy dependence of the cross section for the PI+ PI- 2PI0 final state. Statistical errors only.
Energy dependence of the cross section for the OMEGA PI0 final state. Statistical errors only.
In experiments with the CMD-2 detector at the VEPP-2M electron-positron collider at Novosibirsk about 150000 $e^+e^-\to\pi^+\pi^-$ events were recorded in the center-of-mass energy range from 0.61 up to 0.96 GeV. The result of the pion form factor measurement with a 1.4% systematic error is presented. The following values of the $\rho$-meson and $\rho-\omega$ interference parameters were found: $M_\rho=(775.28\pm 0.61\pm 0.20) MeV, \Gamma_\rho=(147.70\pm 1.29 \pm 0.40) MeV, \Gamma(\rho\to e^+e^-)=(6.93\pm 0.11\pm 0.10) keV, Br(\omega\to\pi^+\pi^-) = (1.32\pm 0.23)%$.
No description provided.
The process e+ e- -> phi -> K+ K- has been studied with the CMD-2 detector using about 542 000 events detected in the center-of-mass energy range from 1.01 to 1.034 GeV. The systematic error of the cross section is estimated to be 2.2%. The phi(1020) meson parameters in the phi -> K+K- decay channel have been measured: sigma_0(phi-> K+K-) = 2016 +- 8 +- 44 nb, m(phi) = 1019.441 +- 0.008 +- 0.080 MeV/c2, Gamma(phi) = 4.24 +- 0.02 +- 0.03 MeV, B(e+e-)B(K+K-) = (14.27 +- 0.05 +- 0.31)*10(-5).
Cross section measurement from the first energy scan.
Cross section measurement from the second energy scan.
The cross section of the process e+ e- ---> eta gamma has been measured in the 600-1380 MeV c.m. energy range with the CMD-2 detector. The following branching ratios have been determined: B(rho ---> eta gamma) = (3.28 +- 0.37 +- 0.23) 10^{-4}, B(omega ---> eta gamma) = (5.10 +- 0.72 +- 0.34) 10^{-4}, B(phi --> eta gamma) = (1.287 +- 0.013 +- 0.063) 10^{-2}. Evidence for the rho'(1450) ---> eta gamma decay has been obtained for the first time.
The measured Born cross section for the ETA GAMMA final state.
Using 3.07 ${pb}^{-1}$ of data collected in the energy range 0.60-0.97 GeV by CMD-2, about 150 events of the process $\epm \to \pch$ have been selected. The energy dependence of the cross section agrees with the assumption of the $a_1(1260) \pi$ intermediate state which is dominant above 1 GeV. For the first time \fourpi events are observed at the $\rho$ meson energy. Under the assumption that all these events come from the $\rho$ meson decay, the value of the cross section at the $\rho$ meson peak corresponds to the following decay width: \Gamma(\rho^0 \to \fourpi) = (2.8 \pm 1.4 \pm 0.5) {keV} or to the branching ratio B(\rho^0 \to \fourpi) = (1.8 \pm 0.9 \pm 0.3) \cdot 10 ^{-5}.
Measured cross section.