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

Le résumé fourni par la source

Using a sample of about ${10}^{10}\text{ }\text{ }J/\ensuremath{\psi}$ events collected at a center-of-mass energy $\sqrt{s}=3.097\text{ }\text{ }\mathrm{GeV}$ with the BESIII detector, the electromagnetic Dalitz decays $J/\ensuremath{\psi}\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\eta}}^{\ensuremath{'}}$, with ${\ensuremath{\eta}}^{\ensuremath{'}}\ensuremath{\rightarrow}\ensuremath{\gamma}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ and ${\ensuremath{\eta}}^{\ensuremath{'}}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}\ensuremath{\eta}$, have been studied. The decay $J/\ensuremath{\psi}\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}}X(1835)$ is observed with a significance of $15\ensuremath{\sigma}$, and also an ${e}^{+}{e}^{\ensuremath{-}}$ invariant-mass dependent transition form factor of $J/\ensuremath{\psi}\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}}X(1835)$ is presented for the first time. The intermediate states $X(2120)$ and $X(2370)$ are also observed in the ${\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\eta}}^{\ensuremath{'}}$ invariant-mass spectrum with significances of $5.3\ensuremath{\sigma}$ and $7.3\ensuremath{\sigma}$. The corresponding product branching fractions for $J/\ensuremath{\psi}\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}}X$, $X\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\eta}}^{\ensuremath{'}}$ [$X=X(1835)$, $X(2120)$, and $X(2370)]$ are reported.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.