Chiral Prediction for the $πN$ Scattering Length $a^-$ to Order ${\cal O}(M_π^4)$

Bernard, V.; Kaiser, N.; Meißner, Ulf-G.

Chiral Prediction for the $πN$ Scattering Length $a^-$ to Order ${\cal O}(M_π^4)$

Authors

Bernard, V.

Kaiser, N.

Meißner, Ulf-G.

Description

We evaluate the S-wave pion--nucleon scattering length $a^-$ in the framework of heavy baryon chiral perturbation theory up--to--and--including terms of order $M_π^4$. We show that the order $M_π^4$ piece of the isovector amplitude at threshold, $T^-_{\rm thr}$, vanishes exactly. We predict for the isovector scattering length, $0.088 \, M_{π^+}^{-1} \le a^- \le 0.096 \, M_{π^+}^{-1}$.
5 pp, LaTeX file, 2 figures (appended as separate compressed tar file, amin.uu)