R. Friedrich et H. Reinhardt, RHO-OMEGA MIXING AND THE PION ELECTROMAGNETIC FORM-FACTOR IN THE NAMBU-JONA-LASINIO MODEL, Nuclear physics. A, 594(4), 1995, pp. 406-418
The rho omega mixing generated by the isospin breaking of the current
quark masses m(u) not equal m(d) is studied within the bosonized NJL m
odel in the gradient expansion. The resulting effective meson Lagrangi
an naturally embodies vector meson dominance. By including pion loops
an excellent description of both the pion electromagnetic form Factor
and of the pi(+)pi(-) phase shifts in the vector-isovector channel is
obtained.