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We study the production amplitude for the reaction $NNto NNpi$ up to next-to-leading order in chiral perturbation theory. We show that the irreducible chiral loops at this order exactly cancel those terms that arise from the off-shell parts of the $pi N$ rescattering vertex. This cancellation is required for formal consistency of the whole scheme. The net effect of the inclusion of all next-to-leading order loops is to enhance the leading rescattering amplitude by a factor of 4/3 compared to phenomenological studies, bringing its contribution to the cross section for $ppto dpi^+$ close to the experimental value.
The production of $eta$ mesons in the reactions $ppto ppeta$ and $pnto pneta $ at threshold-near energies is analyzed within a covariant effective meson-nucleon theory. The description of cross section and angular distributions of the available data
The production of eta and eta-prime mesons in nucleon-nucleon collisions near thresholds is considered within a one-boson exchange model. We show the feasibility of an experimental access to transition formfactors.
Heavy baryon chiral perturbation theory ($chi$PT), where the $Delta$ resonance is included, is used in order to examine the axial charged-current component of the weak interaction process at low neutrino energies. At leading chiral order the Adler th
A comparison of the close-to-threshold total cross section for the eta prime production in pp --> pp eta prime and pn --> pn eta prime reactions constitutes a tool to investigate the eta prime meson structure and the reaction mechanism in the channel
The contribution of the low-lying nucleon resonances $P_{33}(1232)$, $P_{11}(1440)$ $D_{13}(1520)$ and $S_{11}(1535)$ to the invariant mass spectra of di-electrons stemming from the exclusive processes $ppto pp e^+e^-$ and $pnto pn e^+e^-$ is investi