Revisiting axial-vector meson mixing

Various phenomenological studies indicate that the mixing angle theta(K1) of K-1A and K-1B, the strange partners of the axial-vector mesons a(1)(1260) and b(1)(1235), respectively, lies in the vicinity of 35 degrees or 55 degrees, but whether this angle is larger or smaller than 45 degrees still remains controversial. When the f(1)(1285)-f(1)(1420) mixing angle theta(3P1) and the h(1)(1170)-h(1)(1380) mixing angle theta(1P1) pi are determined from the mass relations, they depend on the masses of K-1A and K-1B, which in turn depend on the mixing angle theta(K1). We show that the approximate decoupling of the light q (q) over bar state from the heavier s (s) over bar state, which is empirically valid for vector, tensor and 3(--) mesons, when applied to isoscalar axial-vector mesons, will enable us to discriminate different solutions of theta(3P1) and theta(1P1) and pick up theta(K1)similar to 35 degrees. Indeed, for theta(K1)similar to 55 degrees, the predicted theta(1P1) disagrees sharply with the recent lattice calculation and the implied large s (s) over bar content of h(1)(1170) and q (q) over bar component of h(1)(1380) cannot explain the observation of their strong decays. We conclude that theta(K1), is smaller than 45 degrees. (C) 2011 Elsevier B.V. All rights reserved.