A meson-exchange model of the associated photoproduction of vector   mesons and N*(1440) resonances
  We discuss the photoproduction of omega- and rho0-mesons off protons in the particular channel where the target proton is excited to a Roper resonance N*(1440). We propose a simple meson-exchange model for these processes in order to evaluate their cross sections near threshold and at low momentum transfers. It is suggested in particular that the differential cross section for the associated photoproduction of a rho0-meson and a Roper resonance in these kinematic conditions could provide direct information on the strength of the scalar-isoscalar excitation of the N*(1440) and hence on the magnitude of an effective sigma N N*(1440) coupling. The latter quantity is poorly known and of much interest for the nuclear many-body problem. 
Madeleine Soyeur