Trajectory mixing scheme for the eta and eta' mesons

A possible trajectory mixing scheme for the eta and eta' mesons is proposed based on the picture that the 0- mesons form an ideal nonet in the dual planar theory and deviate from it through non-planar diagrams. First, we present a general argument for the trajectory mixing picture which is then applied to the specific problem of eta and eta' mixing. From this approach emerges a novel feature that we need two mixing angles and two renormalization factors, each defined on the mass shells of the eta and eta'. However, it is shown that the mixing angles THETAsub(eta) and THETAsub(eta') can be expressed solely in terms of the bare (planar) trajectories on the mass shells of the eta and eta' and therefore can be estimated from the known masses of the 0- mesons. With these new values of mixing angles (THETAsub(eta) not equal THETAsub(eta')), various SU(3) sum rules among cross-sections of high energy reactions involving the eta and eta' are analyzed and compared with recent experiments. The conventional mass mixing scheme applied to eta and eta' mixing with independent octet and singlet couplings is shown to be inadequate for describing charge exchange two-body reactions with the eta and eta' in the final state. (auth.)