Remarks on the discretization of physical momenta in lattice QCD
  The calculation on the lattice of cross--sections, form--factors and decay rates associated to phenomenologically relevant physical processes is complicated by the spatial momenta quantization rule arising from the introduction of limited box sizes in numerical simulations. A method to overcome this problem, based on the adoption of two distinct boundary conditions for two fermions species on a finite lattice, is here discussed and numerical results supporting the physical significance of this procedure are shown. 
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