Book ; Online: The cross section of $e^+e^- \to \Lambda \overline \Sigma{}^0+{\rm c.c.}$ as a litmus test of isospin violation in the decays of vector charmonia into $\Lambda \overline \Sigma{}^0+{\rm c.c.}$
2020
Abstract: Under the aegis of isospin conservation, the amplitudes in Born approximation, i.e., considering the only one-photon-exchange mechanism, of the decay $\psi\to \Lambda \overline \Sigma{}^0+{\rm c.c.}$, where $\psi$ is a vector charmonium, and of the ... ...
| Abstract | Under the aegis of isospin conservation, the amplitudes in Born approximation, i.e., considering the only one-photon-exchange mechanism, of the decay $\psi\to \Lambda \overline \Sigma{}^0+{\rm c.c.}$, 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 $J/\psi$. Comment: 8 pages, 4 figures |
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| Keywords | High Energy Physics - Phenomenology ; 81V25 |
| Subject code | 612 ; 515 |
| Publishing date | 2020-07-24 |
| Publishing country | us |
| Document type | Book ; Online |
| Database | BASE - Bielefeld Academic Search Engine (life sciences selection) |
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