The pion-nucleon Sigma-term in a chiral quark model

The pion-nucleon Sigma -term is calculated in a linear sigma -model based o n the U(3) x U(3) quark effective Lagrangian. The importance of the pole di agram with the scalar meson f(0) (400 - 1200) is demonstrated. For the mass of this meson the value 400 MeV was chosen, which corresponds to the theor etical predictions taking into account singlet-octet mixing of scalar isosc alar mesons and glueball on the one hand and to recent experimental data on the other. The resulting value sigma = 75 MeV is in agreement with the lat est analysis of experimental data on the pi -N scattering. It is shown that the hypothesis of the content of strange quarks in the valence structure o f a nucleon is not necessary to reach agreement with experimental data.