Revisiting K1(1270)−K1(1400)

Abstract

We investigate the K1(1270)−K1(1400) mixing induced by the flavor SU(3) symmetry breaking. The mixing angle is calculated in a purely theoretical manner, where it is expressed by a K1A→K1B 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 θK1=21.4°±9° or θK1=68.6°±9°. Published by the American Physical Society 2024