As has been confirmed meanwhile by lattice-QCD calculations (see e.g. Ref. [1]), the confinement spectrum of non-exotic quark-antiquark systems has its ground state for scalar mesons well above 1 GeV in the Resonance Spectrum Expansion (RSE). For instance, in the S-wave Kπ RSE amplitude, a broad resonance was predicted slightly above 1.4 GeV [2], which is confirmed by experiment as the K 0 (143...

Chiral eeective lagrangians may diier in their prediction of meson-nucleon scattering amplitudes oo-meson-mass-shell, but must yield identical S-matrix elements. We argue that the eeective meson mass in nuclear matter obtained from chiral eeective lagrangians is also unique. OO-mass-shell amplitudes obtained using the PCAC choice of pion eld must therefore not be viewed as fundamental constrain...

Because of their large masses, one expects charm mesons to be mostly produced in the initial preequilibrium stage of relativistic heavy ion collisions. They have thus been suggested as possible probes of the initial dynamics in these collisions. Previous studies have been concentrated on the production of charm quarks from the preequilibrium partonic matter [1]. For charm meson production from ...

Differently from the parton–parton scattering amplitudes, which are known to be affected by infrared (IR) divergences, the elastic scattering amplitude of two colourless states in gauge theories, e.g., two qq̄ meson states, is expected to be an IR–finite physical quantity. It was shown in Refs. [1,2,3] that the high–energy meson–meson elastic scattering amplitude can be approximately reconstruct...

Differently from the parton–parton scattering amplitudes, which are known to be affected by infrared (IR) divergences, the elastic scattering amplitude of two colourless states in gauge theories, e.g., two qq̄ meson states, is expected to be an IR–finite physical quantity. It was shown in Refs. 1,2,3 that the high–energy meson–meson elastic scattering amplitude can be approximately reconstructed...

Dispersive approaches provide model independent description of meson-meson scattering. We first review here the use of dispersion relations to obtain a model independent unitarization of Chiral Perturbation Theory amplitudes, that establish the existence of light scalar mesons and whose leading 1/Nc behavior suggest they ahve a non q̄q dominant component. We also review the forward dispersion re...

We review the theory of hadronic atoms in QCD + QED, based on a non–relativistic effective Lagrangian framework. We first provide an introduction to the theory, and then describe several applications: meson– meson, meson–nucleon atoms and meson–deuteron compounds. Finally, we compare the quantum field theory framework used here with the traditional approach, which is based on quantum–mechanical...

Dispersive approaches provide model independent description of meson-meson scattering. We first review here the use of dispersion relations to obtain a model independent unitarization of Chiral Perturbation Theory amplitudes, that establish the existence of light scalar mesons and whose leading 1/Nc behavior suggest they ahve a non q̄q dominant component. We also review the forward dispersion re...