Radially Excited Axial-Vector Mesons in the extended Nambu--Jona-Lasinio model

The first radial excitations of axial-vector mesons are considered in the framework of the extended $U(3)\times U(3)$ Nambu–Jona-Lasinio model. We calculate the mass spectrum of $a_1$, $f_1$, and also strange axial-vector mesons. For description of radially excited states we used the form factors of polynomial type of the second order in transverse quark momentum. For the ground- and the excited-state mesons consisting of light quarks we have calculated the widths of a number of strong and radiative decays. We got satisfactory agreement with experimental data for the ground states. A set of predictions for the excited states of mesons is given.