η meson production in $\mathrm{NN}$ collisions

$\eta$ meson production in both proton-proton and proton-neutron collisions is investigated within a relativistic meson exchange model of hadronic interactions. It is found that the available cross section data can be described equally well by either the vector or pseudoscalar meson exchange mechanism for exciting the $S_{11}\mathrm{}\left(1535\right)\mathrm{}$ resonance. It is shown that the analyzing power data can potentially be very useful in distinguishing these two scenarios for the excitaion of the $S_{11}\mathrm{}\left(1535\right)\mathrm{}$ resonance.