Instanton Effects in the Decay of Scalar Mesons

We show that instanton effects may play a crucial role in the decay of scalar mesons into two pseudoscalars. Particularly the branching ratios of two meson decays of the $f_0(1500)$, which is considered as a glue-ball candidate, are then compatible with an ordinary $q \bar{q}$-structure of this resonance and a small positive SU(3) mixing angle, close to a result recently calculated with the same instanton-induced force.Comment: 9 pages, uuencoded latex including two figure

A Bethe-Salpeter model for light mesons: spectra and decays

The spectra and electroweak decay properties of light mesons are analyzed within the framework of the instantaneous Bethe-Salpeter equation. The interaction kernel comprises alternative spin-structures for a parameterization of confinement and a residual quark-antiquark interaction based on instanton effects. It is shown that only with a vector confinement the parameters can be chosen such as to yield an excellent description of the light pseudoscalar and vector mesons including weak and two photon decays. However it is found that it is not possible to reconcile this with the Regge behavior of higher lying meson states with the same parameter set.Comment: 12 pages, RevTeX, TK-93-1

Analysis of the instantaneous Bethe-Salpeter equation for qqˉq\bar{q}-bound-states

We investigate the structure of the instantaneous Bethe-Salpeter equation for $q\bar{q}$-bound states in the general case of unequal quark masses and develop a numerical scheme for the calculation of mass spectra and Bethe-Salpeter amplitudes. In order to appreciate the merits of the various competing models beyond the reproduction of the mass spectra we present explicit formulas to calculate electroweak decays. The results for an explicit quark model will be compared to experimental data in a subsequent paperComment: 11 pages, RevTeX, TK-93-1

Scalar Mesons in a Relativistic Quark Model with Instanton-Induced Forces

In a relativistic quark model with linear confinement and an instanton-induced interaction which solves the $\eta$-$\eta'$ puzzle, scalar mesons are found as almost pure SU(3) flavor states. This suggests a new interpretation of the scalar nonet: We propose that the recently discovered $f_0(1500)$ is not a glueball but the scalar (mainly)--octet meson for which the $K\bar{K}$ decay mode is suppressed. The mainly--singlet state is tentatively identified with the $f_0(980)$. The isovector and isodoublet states correspond to the $a_0(1450)$ and $K^{\ast}(1430)$, respectively.Comment: 10 pages including 2 uuencoded figures, RevTe