The 14N(γ, π+)14Cg.s. reaction through the delta resonance region

Abstract The pion angular distribution for 14 N( γ , π + ) 14 C g.s. has been measured at a photon energy of 400 MeV. The energy dependence of the cross section through the delta region, and the apparent strength of the resonance contribution, as determined by the present measurement together with earlier lower energy measurements, cannot be accounted for by any current theory. Calculations which use the delta-hole model in the resonance channel overestimate the present results by a factor of over two.