Electromagnetic \(N+\gamma ^{*}\rightarrow N^{*}\) transition form factors of nucleons from the hard-wall AdS/QCD model

The electromagnetic transition form factors for the \(N+\gamma ^{*}\rightarrow N^{*}\) $N+\gamma _{}^{\ast }\to N_{}^{\ast }$ transition between the ground and excited states of nucleons is studied in the framework of the hard-wall model of AdS/QCD. The 5-dimensional equation of motion was solved for the fermion and vector fields. The profile function of the spinor field and bulk-to-boundary propagator of the vector field are presented. The interaction Lagrangian includes other kinds of terms in addition to the minimal coupling term. Using the AdS/CFT correspondence between the generating functions in the bulk and boundary theories, an expression for the transition form factors is obtained from the bulk action for the interaction between the photon and nucleon fields. We consider the \(N^{*}(1440,1535,1710)\rightarrow N\) $N_{}^{\ast }(1440,1535,1710)\to N$ transitions and plot the Dirac, Pauli and electric, magnetic form factors dependencies on momentum transfer. Also, plots for the helicity amplitudes have been presented and compared to experimental data. The transition radii obtained within the soft-wall model are close to the experimental data for the radii of the nucleons at ground states.