A model for the Δ(1600) resonance and γΝ → Δ(1600) transition

Abstract

A covariant spectator constituent quark model is applied to study the γN→Δ(1600) transition. Two processes are important in the transition: a photon couples to the individual quarks of the Δ(1600) core (quark core), and a photon couples to the intermediate pion-baryon states (pion cloud). While the quark core contributions are estimated assuming Δ(1600) as the first radial excitation of Δ(1232), the pion cloud contributions are estimated based on an analogy with the γN→Δ(1232) transition. To estimate the pion cloud contributions in the γN→Δ(1600) transition, we include the relevant intermediate states, πN, πΔ, πN(1440) and πΔ(1600). Dependence on the four-momentum transfer squared, Q2, is predicted for the magnetic dipole transition form factor, GM*(Q2), as well as the helicity amplitudes, A1/2(Q2) and A3/2(Q2). The results at Q2=0 are compared with the existing data.