We discuss electromagnetic currents in the point-form formulation of relativistic quantum mechanics. The construction is along a spectator model and implies that only one quark is explicitly coupled to the photon, but nevertheless many-body contributions are present in the current operator. Such effects are unavoidable in relativistic constructions and resulting ambiguities are notably reduced ...

Abstract Form-factors investigation of $$\rho ^{\pm }$$ ρ ± –mesons was carried out within the framework relativistic quark model, based on point form Poincaré-invariant quantum mechanics taking into account internal structure constituent quarks. It is shown that parame...

forests of iran located on the southern border of the caspian sea cover 1.9 million hectares. the caspian forests are divided into four separate forestry areas. one of these being guilan influx area with total area of 565000 hectares. about 30 to 40 percent of guilan province forests are suitable to short rotation forestry for afforestation. slash pine (pinus elliottii) is one of the main exoti...