A relativistic light-front quark model is used to describe both the elastic nucleon and nucleon-Roper transition form factors in a large Q2 range, up to 35 GeV 2 for the elastic and up to 12 GeV 2 for the resonance case. Relativistic three-quark configurations satisfying the Pauli exclusion principle on the light-front are used for the derivation of the current matrix elements. The Roper resonance is considered as a mixed state of a three-quark core configuration and a molecular N+ σ hadron component. Based on this ansatz we obtain a realistic description of both processes, elastic and inelastic, in the sector of positive parity and show that existing experimental data are indicative of a composite structure of the Roper resonance. A useful generalization of this technique is suggested for description of negative parity nucleon resonances 1/2-,3/2-,5/2-.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics