Search

Abstract: The reaction is a very good isospin 3/2 filter for studying decaying to . With an effective Lagrangian approach, contributions from a previous ignored sub--threshold resonance are fully included in addition to those already considered in previous calculations. It is found that the resonance gives an overwhelmingly dominant contribution for energies very close to threshold, with a very important contribution from the t-channel ρ exchange. This solves the problem that all previous calculations seriously underestimate the near-threshold cross section by order(s) of magnitude. Many important implications of the results are discussed. [Copyright &y& Elsevier]

The primary objective of this study is to investigate hadronic molecules of K ⁎ K ¯ 1 (1270) using a one-boson-exchange model, which incorporates exchanges of vector and pseudoscalar mesons in the t -channel, as well as the pion exchange in the u -channel. Additionally, careful consideration is given to the three-body effects resulting from the on-shell pion originating from K 1 (1270) → K ⁎ π. Then the BESIII data of the J / ψ → ϕ η η ′ process is fitted using the K ⁎ K ¯ 1 (1270) scattering amplitude with J P C = 0 − − or 1 − −. The analysis reveals that both the J P C = 0 − − and 1 − − assumptions for K ⁎ K ¯ 1 (1270) scattering provide good descriptions of the data, with similar fit qualities. Notably, the parameters obtained from the best fits indicate the existence of K ⁎ K ¯ 1 (1270) bound states, denoted by ϕ (2100) and ϕ 0 (2100) for the 1 − − and 0 − − states, respectively. The current experimental data, including the η polar angular distribution, cannot distinguish which K ⁎ K ¯ 1 (1270) bound state contributes to the J / ψ → ϕ η η ′ process, or if both are involved. Therefore, we propose further explorations of this process, as well as other processes, in upcoming experiments with many more J / ψ events to disentangle the different possibilities. [ABSTRACT FROM AUTHOR]