I discuss recent progress in the theory of exclusive meson production and Compton scattering, focusing on hard-scattering factorization and on the dipole formalism.

The process of a light neutral vector meson electroproduction is studied in the framework of QCD factorization in which the amplitude factorizes in a convolution of the nonperturbative meson distribution amplitude and the generalized parton densities with the perturbatively calculable hard-scattering amplitudes. We derive a complete set of hard-scattering amplitudes at next-to-leading order (NL...

Eta meson production in the proton-proton scattering is dominated by the low-mass meson exchange. We present a brief study on how the type of the exchanged mesons within coupled-channel and multi-resonance model influences the scattering observables. We show under which circumstances the eta exchange may explain the shape of the observed cross sections, and present a few selected results: total...

We review two previous approaches to studying pseudoscalar meson-meson scattering amplitudes to beyond 1 GeV using non-linear and linear chiral Lagrangians. In these approaches we use two different unitarisation techniques a generalised Breit Wigner prescription and K-matrix unitarization respectively. We also report some preliminary findings on K-matrix unitarisation of the I=J=0 ππ scattering...

We calculate the S-wave scattering lengths for charmed mesons scattering off Goldstone bosons and explore their quark mass dependence using chiral perturbation theory up to next-to-leading order as well as a unitarized version of it. The quark mass dependence of all scattering lengths determined in a recent lattice calculation can be reproduced by the unitarized version. We also discuss signals...

A procedure is proposed which accounts for final state interaction corrections for near threshold meson production in nucleon-nucleon scattering. In analogy with the Watson-Migdal approximation, it is shown that in the limit of extremely strong final state effects, the amplitude factorizes into a primary production amplitude and an elastic scattering amplitude describing a 3 → 3 transition. Thi...

I review the lattice simulations of light scalar mesons with q̄q and tetraquark interpolating fields. Several difficulties which complicate the extraction of scalar meson masses from the scalar correlators are pointed out. One of the major difficulties is the presence of the twopseudoscalar scattering states, which often dominate the correlator at light quark masses. In the simulations with unph...