Associative photoproduction of Roper resonance and ω meson
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Date
2003
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Abstract
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 the t channel, baryon exchanges, i.e., N and N* exchanges, in the s and 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 show that at low |t| dominant contribution comes from t channel π exchange while the 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).