@article{295e16dd3a6b48dabbb84c057c307163,
title = "Measurement of B (J /ψ →η′e+e-) and search for a dark photon",
abstract = "Using a data sample of (1310.6±7.0)×106 J/ψ decay events collected with the BESIII detector at BEPCII, we study the electromagnetic Dalitz decay J/ψ→η′e+e- with two dominant η′ decay modes, η′→γπ+π- and η′→π+π-η. The branching fraction is determined to be B(J/ψ→η′e+e-)=(6.59±0.07±0.17)×10-5, which improves in precision by a factor of 2 over the previous BESIII measurement. A search for the dark photon (γ′) is performed via J/ψ→η′γ′, γ′→e+e-. Excluding the ω and φ mass regions, no significant signal is observed in the mass range from 0.1 to 2.1 GeV/c2. We set upper limits at the 90% confidence level on B(J/ψ→η′γ′)×B(γ′→e+e-), B(J/ψ→η′γ′) and the mixing strength as a function of dark photon mass. This is among the first searches for dark photons in charmonium decays.",
author = "{(BESIII Collaboration)} and M. Ablikim and Achasov, {M. N.} and S. Ahmed and M. Albrecht and M. Alekseev and A. Amoroso and An, {F. F.} and Q. An and Bai, {J. Z.} and Y. Bai and O. Bakina and {Baldini Ferroli}, R. and Y. Ban and K. Begzsuren and Bennett, {D. W.} and Bennett, {J. V.} and N. Berger and M. Bertani and D. Bettoni and F. Bianchi and E. Boger and I. Boyko and Briere, {R. A.} and H. Cai and X. Cai and O. Cakir and A. Calcaterra and Cao, {G. F.} and Cetin, {S. A.} and J. Chai and Chang, {J. F.} and G. Chelkov and G. Chen and Chen, {H. S.} and Chen, {J. C.} and Chen, {M. L.} and Chen, {P. L.} and Chen, {S. J.} and Chen, {X. R.} and Chen, {Y. B.} and Chu, {X. K.} and G. Cibinetto and F. Cossio and Dai, {H. L.} and Dai, {J. P.} and A. Dbeyssi and D. Dedovich and Deng, {Z. Y.} and A. Denig and I. Denysenko",
note = "Publisher Copyright: {\textcopyright} 2019 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 SCOAP.",
year = "2019",
month = jan,
day = "1",
doi = "10.1103/PhysRevD.99.012013",
language = "English",
volume = "99",
journal = "Physical Review D",
issn = "2470-0010",
publisher = "American Physical Society",
number = "1",
}