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Register a new userMeasurement of Charm Production Cross Sections in e+e- Annihilation at Energies between 3.97 and 4.26 GeV
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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).
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The $e^+e^-togammachi_{cJ}$ ($J=0,1,2$) processes are studied at center-of-mass energies ranging from 3.773 to 4.600~GeV, using a total integrated luminosity of 19.3~fb$^{-1}$ $e^+e^-$ annihilation data accumulated with the BESIII detector at BEPCII. We observe for the first time $e^+e^-togamma chi_{c1,c2}$ signals at $sqrt{s}=$ 4.180~GeV with statistical significances of 7.6$sigma$ and 6.0$sigma$, respectively. The production cross section of $e^+e^-togamma chi_{c1,c2}$ at each center-of-mass energy is also measured. We find that the line shape of the $e^+e^-togamma chi_{c1}$ cross section can be described with conventional charmonium states $psi(3686)$, $psi(3770)$, $psi(4040)$, $psi(4160)$. Compared with this, for the $e^+e^-togamma chi_{c2}$ channel, one more additional resonance is added to describe the cross section line shape. Its mass and width are measured to be $M=4371.7pm7.5pm1.8$~MeV/$c^2$ and $Gamma^{tot}=51.1pm17.6pm1.9$~MeV, where the first uncertainties are statistical and the second systematic. The significance of this resonance is estimated to be 5.8$sigma$, and its parameters agree with the $Y(4360)$ resonance previously reported in $e^+e^-topi^+pi^-psi(3686)$, and the $Y(4390)$ in $e^+e^-topi^+pi^-h_c$ within uncertainties. No significant signal for the $e^+e^-togamma chi_{c0}$ process is observed, and the upper limits of Born cross sections $sigma_{B}(e^+e^-togamma chi_{c0})$ at 90% confidence level are reported.
We measure the inclusive production cross sections of hyperons and charmed baryons from $e^+e^-$ annihilation using a 800 fb$^{-1}$ data sample taken near the $Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. The feed-down contributions from heavy particles are subtracted using our data, and the direct production cross sections are presented for the first time. The production cross sections divided by the number of spin states for $S=-1$ hyperons follow an exponential function with a single slope parameter except for the $Sigma(1385)^+$ resonance. Suppression for $Sigma(1385)^+$ and $Xi(1530)^0$ hyperons is observed. Among the production cross sections of charmed baryons, a factor of three difference for $Lambda_c^+$ states over $Sigma_c$ states is observed. This observation suggests a diquark structure for these baryons.
The Born cross sections for the process $e^+e^- to eta^prime pi^{+}pi^{-}$ at different center-of-mass energies between $2.00$ and $3.08$~GeV are reported with improved precision from an analysis of data samples collected with the BESIII detector operating at the BEPCII storage ring. An obvious structure is observed in the Born cross section line shape. Fit as a Breit-Wigner resonance, it has a statistical significance of $6.3sigma$ and a mass and width of $M=(2108pm46pm25)$~MeV/$c^2$ and $Gamma=(138pm36pm30)$~MeV, where the uncertainties are statistical and systematic, respectively. These measured resonance parameters agree with the measurements of BABAR in $e^+e^- to eta^prime pi^{+}pi^{-}$ and BESIII in $e^+e^- to omegapi^0$ within two standard deviations.
Using data samples collected with the BESIII detector at the BEPCII collider at six center-of-mass energies between 4.008 and 4.600 GeV, we observe the processes $e^+e^-rightarrow phiphiomega$ and $e^+e^-rightarrow phiphiphi$. The Born cross sections are measured and the ratio of the cross sections $sigma(e^+e^-rightarrow phiphiomega)/sigma(e^+e^-rightarrow phiphiphi)$ is estimated to be $1.75pm0.22pm0.19$ averaged over six energy points, where the first uncertainty is statistical and the second is systematic. The results represent first measurements of these interactions.
Based on $14.7~textrm{fb}^{-1}$ of $e^+e^-$ annihilation data collected with the BESIII detector at the BEPCII collider at 17 different center-of-mass energies between $3.7730~textrm{GeV}$ and $4.5995~textrm{GeV}$, Born cross sections of the two processes $e^+e^- to pbar{p}eta$ and $e^+e^- to pbar{p}omega$ are measured for the first time. No indication of resonant production through a vector state $V$ is observed, and upper limits on the Born cross sections of $e^+e^- to V to pbar{p}eta$ and $e^+e^- to V to pbar{p}omega$ at the $90%$ confidence level are calculated for a large parameter space in resonance masses and widths. For the current world average parameters of the $psi(4230)$ of $m=4.2187~textrm{GeV}/c^{2}$ and $Gamma=44~textrm{MeV}$, we find upper limits on resonant production of the $pbar{p}eta$ and $pbar{p}omega$ final states of $7.5~textrm{pb}$ and $10.4~textrm{pb}$ at the $90%$ CL, respectively.
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