A model for the Delta(1600) resonance and gamma N -> Delta(1600) transition

TL;DR

This paper models the gamma N -> Delta(1600) transition using a covariant spectator quark approach, incorporating quark core and pion cloud effects, and predicts Q2 dependence of transition form factors and amplitudes.

Contribution

It introduces a combined quark core and pion cloud model for the Delta(1600) resonance transition, extending previous models to include intermediate states and Q2 dependence predictions.

Findings

Predicted Q2 dependence of GM*(Q2), A_1/2(Q2), A_3/2(Q2).

Estimated pion cloud contributions based on analogies with Delta(1232).

Compared model results with existing data at Q2=0.

Abstract

A covariant spectator constituent quark model is applied to study the gamma N -> Delta(1600) transition. Two processes are important in the transition: a photon couples to the individual quarks of the Delta(1600) core (quark core), and a photon couples to the intermediate pion-baryon states (pion cloud). While the quark core contributions are estimated assuming Delta(1600) as the first radial excitation of Delta(1232), the pion cloud contributions are estimated based on an analogy with the gamma N -> Delta(1232) transition. To estimate the pion cloud contributions in the gamma N -> Delta(1600) transition, we include the relevant intermediate states, pi-N, pi-Delta, pi-N(1440) and pi-Delta(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, A_1/2(Q2) and A_3/2(Q2). The results at Q2=0 are compared with the existing data.