Electroproduction of Roper Resonance in a Meson Cloud Model

The Q~2 dependencies of Roper resonance (N~* (1440)) helicity amplitudes have been discussed based on twoassumptions:(i) the Roper resonance is an excitation of one of the three quarks,and (ii) the quarks are surrounded bya pion-meson cloud.Our study shows that the mixing of the ground state in the Roper wavefunction caused by the pionmeson cloud together with the pion meson cloud itself is crucial for the predictions of the photoproduction amplitudesof the Roper resonance.It is found that our model can give a good description for the helicity amplitudes of the Roperresonance comparing with the experimental measurement.