Our contribution to the Eta’05 workshop on “Production and Decay of η and η Mesons” (1518.9.2005, Cracow, Poland) is summarized. First we discuss open questions in the theoretical treatment of Coulomb-interaction in the context of reaction processes like pp → ppη. Then we review η-η and σ(600)-f0(980) mixing in the U(3)×U(3) Linear Sigma Model and extract information on η-η mixing and the K 0 (...

From an estimate of the meson-meson inelastic scattering at 5 GeV it is concluded that a typical strong phase in B decays to two mesons is of order of 20◦. For a particular final state an estimate of the phase depends on whether that state is more or less probable as a final state compared to those states to which it is connected by the strong interaction S matrix. PACS numbers: 13.25.Gv, 11.30...

We study whether light scalar meson nonet can survive in large values of Nc through observing how scattering amplitudes behave as Nc increases from 3 within a unitarized chiral approach. We obtain the result that vector mesons such as ρ and K∗ survive as narrow width resonances, but all of the scalar meson nonet below 1 GeV fade out as Nc exceeds a rather small number about 6.

The hadronic decays η → πππ, η ′ → πππ and η ′ → ηππ are investigated within a U (3) chiral unitary approach. Final state interactions are included by deriving the effective s-wave potentials for meson meson scattering from the chiral effective Lagrangian and iterating them in a Bethe-Salpeter equation. With only a small set of parameters we are able to explain both rates and spectral shapes of...

The early onset of nuclear shadowing in photoabsorption at low photon energies (∼ 1 GeV) has recently been interpreted as a possible signature of a decrease of the ρ meson mass in nuclei. We show that one can understand this early onset within simple Glauber theory if one takes the negative real part of the ρN scattering amplitudes into account, corresponding to a higher effective mass of the ρ...

We study real-time meson-meson scattering processes in ($1+1$)-dimensional QED by means of tensor networks. prepare initial meson wave packets with given momentum and position introducing an approximation based on the free fermions model. Then, we compute dynamics two initially separated colliding mesons, observing a rich phenomenology as interaction strength states are varied weak intermediate...

Up to the present much work on meson theory has. been done by considering it as a field theory, and the equation of meson as a field equation. This situation has its origin in the fact that the meson was found originally as a field of the heavy particles. However, if we restrict ourselves to the problems of the interaction between the meson and the electromagnetic field, it seems more adequate ...

It is shown that meson radii can be extracted from diffractive scattering experiments of the type: m + p → m + X, where p stands for the target proton, and m for the incident charged meson π, π, K, or K. The basis of the method used to perform this extraction is the QCD-based SOC-picture for inelastic diffraction in high-energy hadron-hadron and lepton-hadron collisions proposed in a recent Let...

Interactions in coupled channels ππ, KK̄ and an effective 2π2π in scalar-isoscalar wave have been analysed. Influence of interchannel couplings on analytical structure of multichannel interaction amplitudes has been studied. Interplay of S-matrix zeroes and poles and their relation with parameters of scalar resonances has been investigated. PACS numbers: 11.80.Gw, 13.60.Le, 13.75.Lb, 14.40.Cs St...

Measurements of vector mesons at HERA allow a detailed study of diffractive and non-diffractive production mechanisms, fragmentation and decay branching ratios. Results are presented on hadronic resonance measurements. In addition, the first observation of two meson states at masses around 1500 MeV and 1700 MeV are reported using inclusive K 0 s K 0 s production in deep inelastic ep scattering ...