Bernard C. Metsch

Learn More
In a relativistic quark model with linear confinement and an instanton-induced interaction which solves the η-η ′ 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 glue-ball but the scalar (mainly)–octet meson for which the K(More)
We present a relativistic quark model for baryons, based on the Bethe–Salpeter equation in instantaneous approximation. Confinement is implemented by an interaction kernel which essentially is a linearly rising potential with a spin-dependence chosen such as to minimize spin-orbit effects. The fine structure of the baryon spectrum follows from an effective(More)
On the basis of the Bethe–Salpeter Equation we developed a covariant constituent quark model, with confinement implemented by a linear potential and an instanton induced interaction explaining mass splittings and mixing of pseudoscalar mesons. In addition this interaction yields a scalar (essentially) flavour singlet state at approximately 1 GeV,(More)
In this contribution I will try to give an overview of what has been achieved in constituent quark models of mesons and baryons by a comparison of some selected results from various ansätze with experimental data. In particular I will address the role of relativistic covariance, the nature of the effective quark forces, the status of results on(More)
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 f0(1500), which is considered as a glue-ball candidate, are then compatible with an ordinary qq̄-structure of this resonance and a small positive SU(3) mixing angle, close to a result(More)
We present a covariant scheme to calculate mesonic transitions in the framework of the Salpeter equation for q ¯ q-states. The full Bethe Salpeter amplitudes are reconstructed from equal time amplitudes which were obtained in a previous paper [1] by solving the Salpeter equation for a confining plus an instanton induced interaction. This method is applied(More)
It is the purpose of this paper to present the results of an attempt to compute the spectrum of a lattice gauge field theory within the Hamiltonian formulation. Our computational framework is the coupled cluster method which has been presented and discussed in detail in Ref. [14]. We have applied our method to the lattice version of the SU(2) Yang-Mills(More)
• For every isovector state there is energetically degenerate an isoscalar partner. The best known example is of course ρ(770) and ω(782), but also h1(1170) and b1(1235) and many other pairs, up to a6(2450) and f6(2510). This is of course nothing but the well known fact that the inter-quark forces are flavor symmetric. Note however, that this rule does not(More)
We calculate semileptonic decays of light and heavy baryons in a relativistically covariant constituent quark model. The model is based on the Bethe-Salpeter-equation in instantaneous approximation. It generates satisfactory mass spectra for mesons and baryons up to the highest observable energies. Without introducing additional free parameters we compute(More)