ﻻ يوجد ملخص باللغة العربية
Under the aegis of isospin conservation, the amplitudes in Born approximation, i.e., considering the only one-photon-exchange mechanism, of the decay $psito Lambda overline Sigma{}^0+{rm c.c.}$, where $psi$ is a vector charmonium, and of the reaction $e^+e^- to Lambda overline Sigma{}^0+{rm c.c.}$ at the $psi$ mass, are parametrized by the same electromagnetic coupling. It follows that, the modulus of such a coupling can be extracted the data on the two observables: the decay branching fraction and the annihilation cross section. By considering the first two vector charmonia, $J/psi$ and $psi(2S)$, it is found that, especially in the case of $psi(2S)$, there is a substantial discrepancy between the values of the modulus of the same electromagnetic coupling extracted from the branching ratio and the cross section. We propose, as a possible explanation for such a disagreement, the presence in the decay amplitude of an isospin-violating contribution driven by a mechanism based on physical (on-shell) intermediate states, that, due to their own nature, should be more effective in the $psi(2S)$ decay than in that of the $J/psi$.
Using the data samples of $(1310.6pm7.2 )times 10^{6}$ $J/psi$ events and $(448.1pm2.9)times 10^{6}$ $psi(3686)$ events collected with the BESIII detector, we search for the rare decays $J/psi to D^{0} e^{+}e^{-} +c.c.$ and $psi(3686) to D^{0} e^{+}e
We analyze the mixing between $Sigma^0$ and $Lambda^0$ based on the baryon masses. We distinguish the contributions from QCD and QED in the baryon mass splittings. We find that the mixing angle between $Sigma^0$ and $Lambda^0$ is $(2.07pm 0.03)times
Using a sample of $(225.2pm 2.8)times 10^6$ $J/psi$ events collected with the BESIII detector, we present results of a study of $J/psirightarrow gammaLambdabar{Lambda}$ and report the first observation of the isospin violating decay $J/psirightarrowL
Based on $4.481times10^8$ $psi(3686)$ events collected with the BESIII detector at BEPCII, the branching fraction of the isospin violating decay $psi(3686)rightarrowbar{Sigma}^{0}Lambda+c.c.$ is measured to be $(1.60 pm 0.31 pm 0.13~pm~0.58) times 10
The decays $chi_{cJ}toSigma^{0}bar{p}K^{+}+{rm c.c.}~(J = 0, 1, 2)$ are studied via the radiative transition $psi(3686)togammachi_{cJ}$ based on a data sample of $(448.1 pm 2.9)times10^{6}$ $psi(3686)$ events collected with the BESIII detector. The b