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

Abstract

We calculate the T-matrices of pseudoscalar meson octet-baryon scattering to one-loop order in SU(3) heavy baryon chiral perturbation theory. The pertinent combinations of low-energy constants are determined by fitting to phase shifts of πN and KN scattering and the corresponding data. By using these low-energy constants, we obtain the strong phase shift difference of πΛ scattering at the Ξ mass, δP-δS=(8.8±0.2) degrees, in agreement with experimental results. We find that the phase shifts in the S01(πΣ), S01(KΞ), S01(K̄N), and S11(K̄Σ) waves are so strong that resonances may be generated dynamically in all these channels. We also predict the scattering lengths and make comparisons with the results obtained from the threshold T-matrices in heavy baryon chiral perturbation theory and the method of covariant infrared regularization. The issue of convergence is also discussed in detail.