Observation ofe+e−→η′J/ψ

Abstract

The process e + e − → η ′ J/ψ is observed for the first time with a statistical significance of 8.6σ at center-of-mass energy √ s = 4.226 GeV and 7.3σ at √ s = 4.258 GeV using data samples collected with the BESIII detector. The Born cross sections are measured to be (3.7 ± 0.7 ± 0.3) and (3.9 ± 0.8 ± 0.3) pb at √ s = 4.226 and 4.258 GeV, respectively, where the first errors are statistical and the second systematic. Upper limits at the 90% confidence level of the Born cross sections are also reported at other 12 energy points.

Spectroscopy including XYZ states at BESIII

“…5 (left), which are consistent with previous Belle result [23]. The process e + e − → η ′ J/ψ was observed for the first time [24] and the measured Born cross section is shown in Fig. 5 (right) which indicates ψ(4160) → η ′ J/ψ.…”

Hadronic molecules

“…In addition, the ground state in the tetraquark picture (Esposito et al, 2015b), Y (4008), is not confirmed by the recent high-statistics data from BESIII (Ablikim et al, 2017c). Meanwhile, the cross sections for e + e − → ψ ππ (Aubert et al, 2007;Wang et al, 2007), η J/ψ (Ablikim et al, 2016b) and ηJ/ψ and 8 In this context it is interesting to note that also the hybrid picture predicts a large coupling of Y (4260) to D 1 (2420)D (Barnes et al, 1995;Close and Page, 2005;Kou and Pene, 2005), which could be interpreted as the necessity of considering D 1D as a component. π 0 J/ψ (Ablikim et al, 2015b) do not show any structure around the Y (4260) energy region.…”

Form factors for semileptonic Bc decays into η , η′ and glueballs

“…Thus the form factors of the B c meson into the light meson π 0 will only depend on a small Isospin symmetry breaking effect, which is very similar to the case where the cross sections of e + e − → J/ψη(η ) are around pb while there is no signal for e + e − → J/ψπ 0 [17,18].…”