Observation of $J/\psi$ Electromagnetic Dalitz Decays to $X(1835)$, $X(2120)$ and $X(2370)$

BESIII Collaboration, M. Ablikim, M. N. Achasov +543

Using a sample of about 10 billion $J/\psi$ events collected at a center-of-mass energy $\sqrt{s}=3.097$ GeV with the BESIII detector, the electromagnetic Dalitz decays $J/ψ\to e^+e^…