LAUSR

An additional kaon-field renormalization dictated by transitions between pseudoscalar and axial-vector fields is derived in the Nambu–Jona-Lasinio model framework. Possible mixings between the $${{K}_{{1A}}}$$ and $${{K}_{{1B}}}$$ axial-vector fields with quantum numbers of $${{J}^{{PC}}} = {{1}^{{ + + }}}$$ and $${{J}^{{PC}}} = {{1}^{{ + - }}}$$, respectively, are taken into account. We demonstrate that the $${{a}_{1}}(1260)$$ and $${{b}_{1}}(1235)$$ do not mix within the SU(2) $$ \times $$ SU(2) chiral scheme. However, a nonzero mixing between the $${{K}_{{1A}}}$$ and $${{K}_{{1B}}}$$ strange axial-vector mesons arises as soon as the strange-quark mass is not equal to those of the u and d quarks, whereby the chiral symmetry is essentially violated. As a result, the $${{K}_{1}}(1270)$$ and $${{K}_{1}}(1400)$$ mesons emerge as physical states. These are taken into account when formulating the additional renormalization of the kaon field.