Radiative decays of heavy quarkonia into two vector mesons. Spin properties of amplitudes and angular distributions of linearly polarized photons

Abstract

Angular distributions of photons with definite linear polarizations relative to the plane spanned by the momentum of initial electron and the total momentum of the V1V1 pair in the reaction e+e− → V → γ X (JP) → γV1V1 (V = J/ψ,ψ′,…, Υ(1S), Υ,… and V1 = ρ,ω,ϕ,…) are calculated. It is shown that the sign of asymmetry of the distributions of photons polarized in the above plane and orthogonal to it correlates with the signature P(−1)J of the X resonance with given spin-parity JP = 0±, 1±, 2± so it may help to establish this quantum number in a way which does not depend on the specific model of the X(JP) → V1V1 amplitude.