πK scattering in chiral perturbation theory to one loop

We evaluate the πK scattering amplitude at next-to-leading order in the framework of chiral perturbation theory. All low-energy constants appearing in the effective lagrangian of the pseudoscalars have previously been determined. We calculate the scattering lengths of the S- and P-waves as well as the expansion parameters around the point v ≡ (s - u)/4M_K = t = 0 in the unphysical region. Furthermore, phase-shifts of the low partial waves are presented and compared to the data. In most cases, the chiral predictions are comparable to the trends set by the empirical information. For a precise comparison, however, more accurate experimental determinations of the πK scattering process at low and moderate energies would be necessary. We urge the experimenters to perform these.