Generalized Unitarity for Pions
Abstract
Generalized (or offshell) unitarity is applied to the twopion system below its inelastic threshold. The exact relativistic result reproduces the known result of potentialscattering theory for the partialwave amplitude κe^{iδ}(κ,δ real) in any given isospinangularmomentum channel: If one incoming pion is off the mass shell, then δ, as a function of the centerofmass energy, is correctly given by its massshell value.
 Publication:

Physical Review
 Pub Date:
 June 1967
 DOI:
 10.1103/PhysRev.158.1620
 Bibcode:
 1967PhRv..158.1620W