Surpassing Wigner's causality bound in relativistic scattering with   zero-range interaction
  It is shown that the relativistic zero-range potential scattering surpasses Wigner's causality bound, while being consistent with causality. The relativistic theory shows in addition a richer analytic structure, such as a $K$-matrix pole necessarily accompanying the bound-state solution. Implications of these results for the effective-field theory of nuclear forces are briefly considered. 
Vladimir Pascalutsa (KPH PRISMA, Mainz U.)
nucl-th hep-ph quant-ph