The J/ψ meson has negative G parity so that, in the limit of isospin conservation, its decay into π+π- should be purely electromagnetic. However, the measured branching fraction B(J/ψ→π+π-) exceeds by more than 4.5 standard deviations the expectation computed according to BABAR data on the e+e-→π+π- cross section. The possibility that the two-gluon plus one-photon decay mechanism is not suppressed by G-parity conservation is discussed, even by considering other multipion decay channels. As also obtained by phenomenological computation, such a decay mechanism could be responsible for the observed discrepancy. Finally, we notice that the BESIII experiment, having the potential to perform an accurate measurement of the e+e-→π+π- cross section in the J/ψ mass energy region, can definitely prove or disprove this strong G-parity-violating mechanism by confirming or confuting the BABAR data.
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|Titolo:||New G-parity violating amplitude in the J/Psi decay?|
|Data di pubblicazione:||2017|
|Appare nelle tipologie:||03.1 Articolo su rivista|