Meson properties in the 1/N-c-corrected NJL model

Properties of mesons are investigated within the Nambu-Jona-Lasinio model. We include meson-loop corrections, which are generated via a systematic 1/N -c-expansion in next-to-leading order. We show that our scheme is consisten t with chiral symmetry, in particular with the Goldstone theorem and the Ge ll-Mann-Oakes-Renner relation. The numerical part focuses on the pion and t he rho-meson sector. For the latter the 1/N-c-corrections are crucial in or der to include the dominant rho --> pi pi-decay channel, while the leading- order approximation only contains unphysical q (q) over bar-decay channels. We show that a satisfactory description of the pion electromagnetic form f actor can be obtained. Similarities and differences to hadronic models are discussed. (C) 2000 Elsevier Science B.V. All rights reserved.