Measurement of e+e- → π++π-Ψ(2S) via initial state radiation at Belle.

We report measurement of the cross section of e+e- → π+π-Ψ(2S) between 4.0 and 5.5 GeV, based on an analysis of initial state radiation events in a 980 fb-1 data sample recorded with the Belle detector. The properties of the Y(4360) and Y(4660) states are determined. Fitting the mass spectrum of π+π-Ψ(2S) with two coherent Breit-Wigner functions, we find two solutions with identical mass and width but different couplings to electron-positron pairs: MY(4360) = (4347±6 ±3) MeV/c2, ΓY(4360) = (103±9±5) MeV, MY(4660) = (4652±10±8) MeV/c2, ΓY(4660) = (68±11±1) MeV; and B[Y(4360) → π+π-Ψ(2S)] · ΓY(4360)e+e- = (10.9±0.6±0.7) eV and B[Y(4660)→ π+π-Ψ(2S)] · ΓY(4660)e+e- = (8.1±1.1±0.5) eV for one solution; or B[Y(4360) → π+π-Ψ(2S)] · ΓY(4360)e+e- = (9.2±0.6±0.6) eV and B[Y(4660) → π+π-Ψ(2S)] · ΓY(4660)e+e- = (2.0±0.3±0.2) eV for the other. Here, the first errors are statistical and the second systematic. Evidence for a charged charmoniumlike structure at 4.05 GeV/c2 is observed in the π±Ψ(2S) intermediate state in the Y(4360) decays. [ABSTRACT FROM AUTHOR]