Associative Photoproduction of Roper Resonance and ω-Meson

Associative photoproduction of ω-meson and N∗(1440) on nucleons, γ + N → ω + N∗(1440), in the near threshold region is investigated in a framework employing effective Lagrangians. Besides π-exchange in t-channel, baryon exchanges, i.e. Nand N∗-exchanges, in the sand u-channels are also taken into account in calculations of differential cross-section and beam asymmetry. Important inputs of this model are the vector and tensor coupling constants of ωNN∗(1440)-vertex, which are assumed to be equal to the values of these couplings for ωNN vertex. Using our previous estimation of ωNN coupling constants obtained from a fit to available experimental data on photoproduction of ω meson in the near threshold region, we produce the necessary numerical predictions for different observables in γ+N → ω+N∗(1440). Numerical results shows that at low |t| dominant contribution comes from tchannel π-exchange while effects of nucleon and N∗(1440) pole terms can be seen at large |t|. Our predictions for the differential cross section and beam asymmetry for the processes γ +N → ω +N∗(1440), where N is proton and neutron at Eγ = 2.5 GeV are presented with zero width approximation and also with the inclusion of width effects of N∗(1440).