No abstract

The cross section for e(+)e(-)-->pi(+)pi(-)J/psi between 3.8 and 5.5 GeV/c(2) is measured using a 548 fb(-1) data sample collected on or near the Upsilon(4S) resonance with the Belle detector at KEKB. A peak near 4.25 GeV/c(2), corresponding to the so called Y(4260), is observed. In addition, there is another cluster of events at around 4.05 GeV/c(2). A fit using two interfering Breit-Wigner shapes describes the data better than one that uses only the Y(4260), especially for the lower-mass side of the 4.25 GeV enhancement.

A distinct peak is observed in the π ± ψ ′ invariant mass distribution near 4.43 GeV in B → Kπ ± ψ ′ decays. A fit using a Breit-Wigner resonance shape yields a peak mass and width of M = 4433 ± 4 (stat) ± 2 (syst) MeV and Γ = 45 +18 −13 (stat) +30 −13 (syst) MeV. The product branching fraction is determined to be B(B 0 → K ∓ Z ± (4430)) × B(Z ± (4430) → π ± ψ ′ ) = (4.1 ± 1.0(stat) ± 1.4(syst)) × 10 −5 , where Z ± (4430) is used to denote the observed structure. The statistical significance of the observed peak is 6.5σ. These results are obtained from a 605 fb −1 data sample that contains 657 million B B pairs collected near the Υ(4S) resonance with the Belle detector at the KEKB asymmetric energy e + e − collider.

The cross section for e + e − → π + π − ψ(2S) between threshold and √ s = 5.5 GeV is measured using 673 fb −1 of data on and off the Υ(4S) resonance collected with the Belle detector at KEKB. Two resonant structures are observed in the π + π − ψ(2S) invariant mass distribution, one at 4361 ± 9 ± 9 MeV/c 2 with a width of 74 ± 15 ± 10 MeV/c 2 , and another at 4664 ± 11 ± 5 MeV/c 2 with a width of 48 ± 15 ± 3 MeV/c 2 , if the mass spectrum is parameterized with the coherent sum of two Breit-Wigner functions. These values do not match those of any of the known charmonium states.

We perform a full amplitude analysis of B 0 → ψ ′ K + π − decays, with ψ ′ → µ + µ − or e + e − , to constrain the spin and parity of the Z(4430) −. The J P = 1 + hypothesis is favored over the 0 − , 1 − , 2 − and 2 + hypotheses at the levels of 3.4σ, 3.7σ, 4.7σ and 5.1σ, respectively. The analysis is based on a 711 fb −1 data sample that contains 772 × 10 6 BB pairs collected at the Υ(4S) resonance by the Belle detector at the asymmetric-energy e + e − collider KEKB.