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

Abstract

Using a sample of about 1010 J/ψ events collected at a center-of-mass energy s=3.097 GeV with the BESIII detector, the electromagnetic Dalitz decays J/ψ→e+e-π+π-η′, with η′→γπ+π- and η′→π+π-η, have been studied. The decay J/ψ→e+e-X(1835) is observed with a significance of 15σ, and also an e+e- invariant-mass dependent transition form factor of J/ψ→e+e-X(1835) is presented for the first time. The intermediate states X(2120) and X(2370) are also observed in the π+π-η′ invariant-mass spectrum with significances of 5.3σ and 7.3σ. The corresponding product branching fractions for J/ψ→e+e-X, X→π+π-η′ [X=X(1835), X(2120), and X(2370)] are reported. © 2022 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/"Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3.