Study of $N(1520)$ and $N(1535)$ structures via ${\gamma }^{\ast }p\to N^{\ast }$ transitions

Abstract

The helicity amplitudes of the $N(1520)$ and $N(1535)$ resonances in the ${\gamma }^{\ast }p\to N^{\ast }$ electromagnetic transition are studied in the constituent quark model using the impulse approximation, with the proton and resonances assumed to be in three-quark configurations. The comparison of theoretical results and experimental data on the helicity amplitudes $A_{1/2}$, $A_{3/2}$, and $S_{1/2}$ indicates that the $N(1520)$ and $N(1535)$ resonances are primarily composed of three-quark $L=1$ states but may contain additional components. However, it is improbable that contributions from meson clouds will be dominant at low $Q^2$.

Comments: 6 pages, 3 figures