We consider the covariant Spectator equation with a One Boson Exchange (OBE) kernel, and apply it to the NN system. Relativistic effects such as retardation and negative-energy state components are included in that equation. We develop a method, based on the Padé method, to solve the Spectator equation without partial wave decomposition. The convergence of the partial wave decomposition series ...

In the framework of the recently proposed QCD based parton model for the cumulative phenomena in the interactions with nuclei two mechanisms for particle production, direct and spectator ones, are analysed. It is shown that due to final state interactions the leading terms of the direct mechanism contribution are cancelled and the spectator mechanism is the dominant one. It leads to a smaller s...

To know and understand form factors of hadronic currents is of decisive importance for analysing exclusive weak decays. The ratios of different form factors of a given process depend on the relativistic spin structure of initial and final particles. It is shown — assuming simple properties of the spectator particle — that these ratios can entirely be expresssed in terms of particle and quark ma...

In this paper the relevance of non-spectator decays of charm particles is analysed and some crucial tests for it are suggested.