اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدStudy of $e^+e^- rightarrow pbar{p}$ in the vicinity of $psi(3770)$
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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 sect
ion 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 for
m 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.
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,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.
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