Sigma-term physics in the perturbative chiral quark model

We apply the perturbative chiral quark model at one loop to analyze meson-baryon sigma terms. Analytic expressions for these quantities are obtained in terms of fundamental parameters of low-energy pion-nucleon physics (weak pion decay constant, axial nucléon coupling, strong pion-nucleon form factor) and of only one model parameter (radius of the nucleonic three-quark core). Our result for the πN sigma term σ_πN ≈45 MeV is in good agreement with the value deduced by Gasser, Leutwyler, and Sainio using dispersionrelation techniques and exploiting the chiral symmetry constraints.