Meson-baryon scattering to one-loop order in heavy baryon chiral perturbation theory

摘要

We calculate the T-matrices of pseudoscalar meson octet-baryon scattering toone-loop order in SU(3) heavy baryon chiral perturbation theory. The pertinentcombinations of low-energy constants are determined by fitting to phase shiftsof $\pi N$ and $K N$ scattering and the corresponding data. By using theselow-energy constants, we obtain the strong phase shift difference of $\pi\Lambda$ scattering at the $\Xi$ mass, $\delta_P-\delta_S=(8.8 \pm 0.2)$degrees, in agreement with experimental results. We find that the phase shiftsin the $S_{01}$($\pi \Sigma$), $S_{01}$($K \Xi$), $S_{01}$($\overline{K} N$),and $S_{11}$($\overline{K} \Sigma$) waves are so strong that resonances may begenerated dynamically in all these channels. We also predict the scatteringlengths and make comparisons with the results obtained from the thresholdT-matrices in heavy baryon chiral perturbation theory and the method ofcovariant infrared regularization. The issue of convergence is also discussedin detail.