${\gamma }^{\ast }N\to N^{\ast }(1520)$ transition form factors in light cone QCD

Abstract

The ${\gamma }^{\ast }N\to N^{\ast }(1520)$ reaction is studied in framework of the light cone QCD sum rules method. The sum rules for the multipole form factors, namely, for the magnetic dipole $G_M(Q^2)$, electric quadrupole $G_E(Q^2)$, and Coulomb quadrupole $G_C(Q^2)$, form factors responsible for for the ${\gamma }^{\ast }N\to N^{\ast }(1520)$ transition are derived. Using these sum rules, the helicity amplitudes are presented as the combinations of these multipole form factors, and their $Q^2$ dependences are studied. We compare our results on the helicity amplitudes with those of the spectator model predictions, and with the existing experimental data.

Comments: 18 pages, 3 figures, LaTeX formatted