Observation of the Y(4230) and evidence for a new vector charmoniumlike state Y(4710) in e+ e- → K0SK0SJ/ψ

作者：Ablikim, M.; Achasov, M. N.; Adlarson, P.; Albrecht, M.; Aliberti, R.; Amoroso, A.; An, M. R.; An, Q.; Bai, X. H.; Bai, Y.; Bakina, O.; Ferroli, R. Baldini; Balossino, I.; Ban, Y.; Batozskaya, V.; Becker, D.; Begzsuren, K.; Berger, N.; Bertani, M.; Bettoni, D.; Bianchi, F.; Bloms, J.; Bortone, A.; Boyko, I; Briere, R. A.; Brueggemann, A.; Cai, H.; Cai, X.; Calcaterra, A.; Cao, G. F.; Cao, N.; Cetin, S. A.; Chang, J. F.; Chang, W. L.; Chelkov, G.; Chen, C.; Chen, Chao; Chen, G.; Chen, H. S.

来源：Physical Review D, 2023, 107(9): 092005.

DOI：10.1103/PhysRevD.107.092005

• DECAY

Cross sections for the process e thorn e- & RARR; K0SK0SJ=& psi; at center-of-mass energies from 4.128 to 4.950 GeV are measured using data samples with a total integrated luminosity of 21.2 fb-1 collected by the BESIII detector operating at the BEPCII storage ring. The Yo4230 thorn state is observed in the energy dependence of the e thorn e- & RARR; K0SK0 SJ=& psi; cross section for the first time with a statistical significance of 26.0 & sigma;. In addition, an enhancement around 4.710 GeV, labeled as the Yo4710 thorn , is seen with a statistical significance of 4.2 & sigma;. There is no clear structure around 4.484 GeV. Using a fit with a coherent sum of three Breit-Wigner functions, we determine the mass and width of the Yo4230 thorn state to be 4226.9 ? 6.6 ? 22.0 MeV=c2 and 71.7 ? 16.2 ? 32.8 MeV, respectively, and the mass and width of the Yo4710 thorn state to be 4704.0 ? 52.3 ? 69.5 MeV=c2 and 183.2 ? 114.0 ? 96.1 MeV, respectively, where the first uncertainties are statistical and the second are systematic. In addition, the average Born cross section ratio & sigma;Bornoe thorn e-& RARR;K thorn K-J=& psi; thorn is measured to be 0.388 thorn 0.035 & sigma;Bornoe thorn e-& RARR;K0 SK0 SJ=& psi; thorn -0.028 ?0.016, or 0.426 thorn 0.038 -0.031 ? 0.018 if three-body phase space is considered.