Heavy quarkonium PP transitions and effects of κ and a possible bb̄qq̄ state

Abstract

Heavy quarkonium PP decays are studied with the final state interaction in the framework of Chiral Unitary Approach (ChUA). It is found that Υ(nS) and ψ(2S) ππ decay data, especially the Υ(3S) → Υ(1S)π+π− decay data, can be well‐explained by introducing an additional intermediate state with JP = 1+, I = 1, M = 10.08GeV and Γ = 0.655GeV, which could be a bbqq state. By using dimensional regularization method, the singularity in the loop integration in ChUA can be avoid and S‐wave Kπ scattering in the energies less than 1.2GeV can be well‐reproduced by simply employing a lowest order Lagrangian (O(p2)) in ChPA with one adjustable parameter only. As a result, the mass and width of κ are estimated to be Mκ = 757 ± 33MeV and Γκ = 558 ± 82MeV, respectively. It is shown that κ is very important in explaining the broad bump below 1.1GeV in the K+π− invariant mass spectrum of the J/ψ → K*0(892)K+π− process.