Ambiguities in the partial-wave analysis of pseudoscalar-meson photoproduction Abstract Ambiguities in pseudoscalar-meson photoproduction, arising from incomplete experimental data, have analogs in pion-nucleon scattering. Amplitude ambiguities have important implications for the problems of amplitude extraction and resonance identification in partial-wave analysis. The effect of these ambiguit...

We shall discuss how some relevant analyticity and crossing-symmetry properties of the “eikonal scattering amplitudes” of two Wilson loops in QCD, when going from Euclidean to Minkowskian theory, can be related to the still unsolved problem of the asymptotic s–dependence of the hadron–hadron total cross–sections. In particular, we critically discuss the question if (and how) a pomeron–like beha...

A systematic multiple scattering formalism for vector meson electroproduction from nuclei is developed, with emphasis on the formation, propagation and hadronization scales for quark-gluon fluctuations of the virtual high-energy photon. The theory is compared to HERMES measurements of ρ electroproduction on 14 N. The nuclear transparency as a function of the vector meson propagation length is w...

An effective residual interaction for a meson-meson system is computed in lattice QCD. We describe the theoretical framework and present its application to the I = 2 channel S-wave interaction of the π–π system. Scattering phase shifts are also computed and compared to experimental results.

We study the η ′ g * g * vertex for arbitrary gluon virtualities in the time-like and space-like regions, using the perturbative QCD hard scattering approach and an input wave-function of the η ′-meson consistent with the measured η ′ γ * γ transition form factor. The contribution of the gluonic content of the η ′-meson is taken into account, enhancing the form factor over the entire virtuality...

Neither quantum field theory nor S-Matrix theory have a well defined procedure for going over to an approximation that can be reliably used in non-relativistic models for nuclear physics. We meet the problem here by constructing a finite particle number relativistic scattering theory for (scalar) particles and mesons using integral equations of the Faddeev-Yakubovsky type. Restricted to N parti...

We study qqq̄q̄-type four-quark (4Q) systems in SU(3)c anisotropic quenched lattice QCD, using the O(a)-improved Wilson (clover) fermion at β = 5.75 on 12 × 96 with renormalized anisotropy as/at = 4. For comparison, we first investigate the lowest qq̄ scalar meson from the connected diagram and find its large mass of about 1.32GeV after chiral extrapolation, and thus the lowest qq̄ scalar meson cor...

In the framework of model motivated by perturbative calculations in QCD we estimate the differential and total cross sections for both the photoproduction of vector D *-mesons and their yield in deep inelastic scattering at the HERA collider. The offered model allows us to take into account higher twists over the transverse momentum of meson at p T ∼ m c and correctly to approach the dominance ...

Inclusion of multi-meson operators allows lattice QCD calculations to extract energies of resonances above two-meson thresholds, as well as to study two-meson scattering. Previously, temporal correlations involving multi-hadron operators were difficult to evaluate due to contributions from quark propagators which begin and end on the same time slice. The stochastic LapH method allows for effici...