Structural Vertices of Extended SU(3)-Chiral Lagrangians in the Large-N_c Approach

The main goal of this paper is to elaborate the model-framework parametrization of effective coupling constants of the extended chiral lagrangian which is suitable for the description of the low-energy matrix elements of vector, axial-vector, scalar and pseudoscalar currents as well as of the matrix elements of the pseudoscalar gluon density. We establish the connection between the structural coupling constants of the phenomenological chiral lagrangian and the coefficients of effective lagrangians obtained in the QCD-bosonization models by means of the derivative expansion. The large-N_c relations for corresponding structural constants are elaborated. On this way we find the new set of OZI rules. In particular, one of them predicts the branching ratio of the decays $\psi' \rightarrow J/\psi + \pi$ or $\eta$.Comment: 7 pages, LaTeX, Preprint SPbU-IP-94-1, Talk at the Workshop on Chiral Perturbation Theory and Other Effective Theories (Karreb{\ae}ksminde, Denmark, Sept.1993

Scalar mesons and glueball in a quark model allowing for gluon anomalies

This paper is a sequel of a previous one (Scalar mesons in a chiral quark model with glueball, Eur. Phys. J. A 8, 567 (2000)) where an attempt to construct an effective $U(3)\times U(3)$-symmetric meson Lagrangian with a scalar glueball was made. The glueball was introduced by using the dilaton model on the base of scale invariance. The scale invariance breaking because of current quark masses and the scale anomaly of QCD, reproduced by the dilaton potential, was taken into account. However, in the previous paper, the scale invariance breaking because of the terms like $h_{\phi}\phi_0^2$ and $h_{\sigma}\bar\sigma_0^2$, where $\phi_0$ and $\bar\sigma_0$ are the pseudoscalar and scalar isosinglets, was not taken into account. These terms are produced by the part of the 't Hooft interaction that is connected with gluon anomalies. Allowing for the scale invariance breaking by these terms has a decisive effect on the quarkonium-glueball mixing and noticeably changes the widths of glueball strong decays. Taking account of this additional source of the scale invariance breaking and its implications are the subject of the present work. It is also shown that in the decay of a glueball into four pions, the channel with two $\rho$-resonances dominates

Ground and excited scalar isoscalar meson states in a U(3)×U(3)\bf{U(3)\times U(3)} quark model with a glueball

Ground and first radially excited scalar isoscalar meson states and a scalar glueball are described in a nonlocal $U(3)\times U(3)$ quark model. The glueball is introduced into the effective meson Lagrangian by means of the dilaton model on the base of the scale invariance of the meson Lagrangian. The scale invariance breaking by current quark masses and gluon anomalies is taken into account. The glueball anomalies turn out to be important for the description of the glueball-quarkonia mixing. The masses of five scalar isoscalar meson states and their strong decay widths are calculated. The state $f_0(1500)$ is shown to be composed mostly of the scalar glueball