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Register a new userStudy of $e^+e^- rightarrow pbar{p}$ in the vicinity of $psi(3770)$
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BESIII Collaboration: M. Ablikim
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Using 2917 $rm{pb}^{-1}$ of data accumulated at 3.773~$rm{GeV}$, 44.5~$rm{pb}^{-1}$ of data accumulated at 3.65~$rm{GeV}$ and data accumulated during a $psi(3770)$ line-shape scan with the BESIII detector, the reaction $e^+e^-rightarrow pbar{p}$ is studied considering a possible interference between resonant and continuum amplitudes. The cross section of $e^+e^-rightarrowpsi(3770)rightarrow pbar{p}$, $sigma(e^+e^-rightarrowpsi(3770)rightarrow pbar{p})$, is found to have two solutions, determined to be ($0.059pm0.032pm0.012$) pb with the phase angle $phi = (255.8pm37.9pm4.8)^circ$ ($<$0.11 pb at the 90% confidence level), or $sigma(e^+e^-rightarrowpsi(3770)rightarrow pbar{p}) = (2.57pm0.12pm0.12$) pb with $phi = (266.9pm6.1pm0.9)^circ$ both of which agree with a destructive interference. Using the obtained cross section of $psi(3770)rightarrow pbar{p}$, the cross section of $pbar{p}rightarrow psi(3770)$, which is useful information for the future PANDA experiment, is estimated to be either ($9.8pm5.7$) nb ($<17.2$ nb at 90% C.L.) or $(425.6pm42.9)$ nb.
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The process $e^+e^-rightarrow poverline{p}pi^0$ has been studied by analyzing data collected at $sqrt{s}=3.773$ GeV, at $sqrt{s}=3.650$ GeV, and during a $psi(3770)$ line shape scan with the BESIII detector at the BEPCII collider. The Born cross section of $p overline{p} pi^0$ in the vicinity of the $psi(3770)$ is measured and the Born cross section of $psi(3770)rightarrow p overline{p} pi^0$ is extracted considering interference between resonant and continuum production amplitudes. Two solutions with the same probability and a significance of 1.5$sigma$ are found, and the Born cross section of $psi(3770)rightarrow p overline{p} pi^0$ is determined to be less than 0.22 pb at 90% confidence level and $33.8pm1.8pm2.1$ pb, respectively. Using the estimated cross section and a constant decay amplitude approximation, the cross section $sigma(poverline{p} rightarrow psi(3770) pi^0)$ is calculated for the kinematic situation of the planned $overline{text{P}}text{ANDA}$ experiment. The maximum cross section corresponding to the two solutions is expected to be less than $0.79$ nb at 90% confidence level and $122pm10$ nb at a center of mass energy of 5.26 GeV.
Using data samples collected with the BESIII detector at the BEPCII collider, we measure the Born cross section of $e^{+}e^{-}rightarrow pbar{p}$ at 12 center-of-mass energies from 2232.4 to 3671.0 MeV. The corresponding effective electromagnetic form factor of the proton is deduced under the assumption that the electric and magnetic form factors are equal $(|G_{E}|= |G_{M}|)$. In addition, the ratio of electric to magnetic form factors, $|G_{E}/G_{M}|$, and $|G_{M}|$ are extracted by fitting the polar angle distribution of the proton for the data samples with larger statistics, namely at $sqrt{s}=$ 2232.4 and 2400.0 MeV and a combined sample at $sqrt{s}$ = 3050.0, 3060.0 and 3080.0 MeV, respectively. The measured cross sections are in agreement with recent results from BaBar, improving the overall uncertainty by about 30%. The $|G_{E}/G_{M}|$ ratios are close to unity and consistent with BaBar results in the same $q^{2}$ region, which indicates the data are consistent with the assumption that $|G_{E}|=|G_{M}|$ within uncertainties.
Using $4.479 times 10^{8}$ $psi(3686)$ events collected with the BESIII detector, we search for the decays $psi(3686) rightarrow e^{+}e^{-}chi_{c0,1,2}$ and $chi_{c0,1,2} rightarrow e^{+}e^{-}J/psi$. The decays $psi(3686) rightarrow e^{+}e^{-}chi_{c0,1,2}$ and $chi_{c0,1,2} rightarrow e^{+}e^{-}J/psi$ are observed for the first time. The measured branching fractions are $mathcal{B}(psi(3686) rightarrow e^{+}e^{-}chi_{c0,1,2}) = (11.7 pm 2.5 pm 1.0)times10^{-4}$, $(8.6 pm 0.3 pm 0.6)times10^{-4}$, $(6.9 pm 0.5 pm 0.6)times10^{-4}$, and $mathcal{B}(chi_{c0,1,2} rightarrow e^{+}e^{-}J/psi) = (1.51 pm 0.30 pm 0.13)times10^{-4}$, $(3.73 pm 0.09 pm 0.25)times10^{-3}$, $(2.48 pm 0.08 pm 0.16)times10^{-3}$. The ratios of the branching fractions $frac{mathcal{B}(psi(3686) rightarrow e^{+}e^{-}chi_{c0,1,2})}{mathcal{B}(psi(3686) rightarrow gammachi_{c0,1,2})}$ and $frac{mathcal{B}(chi_{c0,1,2} rightarrow e^{+}e^{-}J/psi)}{mathcal{B}(chi_{c0,1,2} rightarrow gamma J/psi)}$ are also reported.
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.
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.
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