Investigation on Virtual State Contribution to Gauge Invariant Cross Section of e⁺e^-→J/ψ+η_c in Bethe-Salpeter Framework

Abstract

It is shown that the virtual states and relative momentum of the constituents of the bound states are very important for the cross section of the process e + e - →J/ψ+η c with the help of the Bethe-Salpeter wave function description of the bound states. The gauge invariance of the cross section is demonstrated. The numerical results can explain the experimental data.