Revisiting K₁(1270) - K₁(1400) mixing with QCD sum rules

We investigate the K-1(1270) - K-1(1400 ) mixing induced by the flavor SUo3 thorn symmetry breaking. The mixing angle is calculated ina purely theoretical manner, where it is expressed by a K-1A -> K-1B transition matrix element of the operators that break flavor SU(3) symmetry. The QCD contribution to this matrix element is assumed to be dominated and calculated with QCD sum rules. A three-point correlation function is defined and handled both at the hadron and quark-gluon levels. The quark-gluon level calculation is based on operator product expansion up to dimension-five condensates. A detailed numerical analysis is performed to determine the Borel parameters, and the obtained mixing angle is theta(K1) = 21.4 degrees +/- 9 degrees or theta(K1) = 68.6 degrees +/- 9 degrees.