Lambda-nucleon scattering in baryon chiral perturbation theory

摘要

We calculate the Lambda-nucleon scattering phase shifts and mixing angles by applying time-ordered perturbation theory to the manifestly Lorentz-invariant formulation of SU(3) baryon chiral perturbation theory. Scattering amplitudes are obtained by solving the corresponding coupled-channel integral equations that have a milder ultraviolet behavior compared to their nonrelativistic analogs. This allows us to consider the removed cutoff limit in our leading-order calculations also in the P-3(0) and P-3(1) partial waves. We find that, in the framework we are using, at least some part of the higher-order contributions to the baryon-baryon potential in these channels needs to be treated nonperturbatively, and we demonstrate how this can be achieved in a way consistent with quantum field theoretical renormalization for the leading contact interactions. We compare our results with the ones of the nonrelativistic approach and lattice QCD phase shifts obtained for non-physical pion masses.