Baryon-Meson Couplings in the $q\bar{q}$ Pair-Creation Quark Model. II

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Abstract
Characteristic features of baryon-meson couplings for P-wave baryons are studied in a quark model in which q q pair-creation processes inherent in the quark-gluon interaction Lagrangian are explicitly incorporated. The transition amplitudes for decays to the lowest S-wave 3q and q q configurations are transformed to the standard vertex functions for meson emission with the flavor dependence explicitly shown in the operator formalism. These vertex functions consist of two independent flavor amplitudes \mathscrA(k) and \mathscrB(k) evaluated at the decaying momentum k, which mainly contribute to S-wave and D-wave decays, respectively. The pseudo-scalar meson decays of P-wave baryons are successfully described in the SU6 model where \mathscrA(k) and \mathscrB(k) are separately assumed to follow the exact SU6 rules with respect to the spin and flavor degrees of freedom. A detailed analysis of model predictions for \mathscrA(k) and \mathscrB(k) by the use of the present pair-creation interaction shows that \mathscrB(k) follows the approximate SU6 rules, while the dominant S-wave amplitude \mathscrA(k) has rather irregular behavior in magnitude with respect to the pseudo-scalar meson couplings, and the electric- and magnetic-type vector meson ones. For correct description of the experimental data for pseudo-scalar meson decays, some mechanism seems to be needed to reduce the relative importance of \mathscrA(k) to \mathscrB(k) in the present model. A possible modification of the pair-creation interaction is discussed.

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