We make a theoretical study of the s-wave interaction of the nonet of vector mesons with the octet of pseudoscalar mesons starting from a chiral invariant Lagrangian and implementing unitarity in coupled channels. By looking for poles in the unphysical Riemann sheets of the unitarized scattering amplitudes, we get two octets and one singlet of axial-vector dynamically generated resonances. The poles found can be associated to most of the low lying axial-vector resonances quoted in the Particle Data Book: b 1 (1235), h 1 (1170), h 1 (1380), a 1 (1260), f 1 (1285) and two poles to the K 1 (1270) resonance. We evaluate the couplings of the resonances to the V P states and the partial decay widths in order to reinforce the arguments in the discussion.

The magnetic moment of the A hyperon is calculated using the QCD sum-rule approach of Ioffe and Smilga. It is shown that p,, has the structure p,,= f ( e , + e d +4e, ) ( e f i / 2 M A c ) ( 1 +6,,), where S,, is small. In deriving the sum rules special attention is paid to the strange-quark massdependent terms and to several additional terms not considered in earlier works. These terms are now appropriately incorporated. The sum rule is analyzed using the ratio method. Using the external-field-induced susceptibilities determined earlier, we find that the calculated value of p h is in agreement with experiment.

Correlators of singlet and octet axial currents, as well as anomaly and pseudoscalar densities have been studied using QCD sum rules. Several of these sum rules are used to determine the couplings 8 0 8 ' , , f f f η η η and 0 'f η . We find mutually consistent values which are also in agreement with phenomenological values obtained from data on various decay and production rates. While most of the sum rules studied by us are independent of the contributions of direct instantons and screening correction, the singlet-singlet current correlator and the anomaly-anomaly correlator improve by their inclusion.

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We make a theoretical study of the s-wave interaction of the nonet of vector mesons with the octet of pseudoscalar mesons starting from a chiral invariant Lagrangian and implementing unitarity in coupled channels. By looking for poles in the unphysical Riemann sheets of the unitarized scattering amplitudes, we get two octets and one singlet of axial-vector dynamically generated resonances. The poles found can be associated to most of the low lying axial-vector resonances quoted in the Particle Data Book: b 1 (1235), h 1 (1170), h 1 (1380), a 1 (1260), f 1 (1285) and two poles to the K 1 (1270) resonance. We evaluate the couplings of the resonances to the V P states and the partial decay widths in order to reinforce the arguments in the discussion.