Characteristics of unnatural parity meson exchange term, and nonevasive component

The characteristics of scattering amplitude, which were found from the amplitude analysis of π (K)N scattering, are as follows. The Regge pole model of natural parity mesons is good for s dependence. The behavior of the imaginary part of the amplitude is stipulated by Δn(s channel net helicity flip). The phase is in agreement with Regge phase for Δn=1, but deviates for Δn=0. EXD is almost good except tensor meson exchange part. Relations such as Isub(t)=1 in case of /f sub(Δn=1)/>>/f sub(Δn=0)/, and Isub(t)=0 in case of /f sub(Δn=0)/>>/f sub(Δn=1)/ exist between the magnitudes of t channel exchanged quantum number and residue. The consistent theory for two body scattering amplitude has not yet been obtained. As examples, the processes Psub(s)B → VB (or Δ) and γN → Psub(s)B (or Δ) were analyzed, The s dependence and the t dependence of the cross section were investigated. The resonance amplitude for γN → Psub(s)B (or Δ) has been studied with resonance parameters. The position of dip and the coupling strength were found. These data resulted from the separation of natural parity meson exchange and unnatural parity meson exchange. The matching with the model amplitude in photo - π production process was examined. Construction of the model amplitude and the remaining problems are introduced and discussed. (Kato, T.)