Structure functions of pseudoscalar mesons in the SU(3) NJL model

We compute the structure functions of the pion, kaon and η mesons using a SU(3) version of the NJL model with scalar and pseudoscalar couplings. By considering the absorptive part of the forward Compton scattering amplitude, the regularization can be treated without ambiguities and gauge invariance is preserved at every stage of the calculation. Using Pauli-Villars regularization, the structure functions scale and have proper normalization in the Bjorken limit. In the chiral limit, the simple result q(x) = q(x) = θ(x)θ(1 − x) is obtained for the structure functions. The results are evolved to higher momentum using the Altarelli-Parisi equations for three flavours, and good agreement with the experimental data for the pion structure function is found.