Nature of the axial-vector mesons from their Nc behavior within the chiral unitary approach.

By describing within the chiral unitary approach the s -wave interaction of the vector meson nonet with the octet of pseudoscalar Goldstone bosons, we find that the main component of the axial-vector mesons -- b1(1235) , h1(1170) , h1(1380) , a1(1260) , f1(1285) and the two states associated to the K1(1270) -- does not follow the QCD dependence on the number of colors for ordinary q $ \bar{{q}}$ mesons. [ABSTRACT FROM AUTHOR]