Results on the Analyticity of Many - Body Scattering Amplitudes in Perturbation Theory
نویسنده
چکیده
The problem of analytic continuation of the many-body scattering amplitude associated with a perturbation-theory diagram under the rotation of the final momenta from real to complex momenta, k -.. (1 + iO)k, is studied. It is shown that the contour of integration over internal momenta can be distorted avoiding singularities of the integrand, as 0 varies for small enough O. If the diagram is connected enough, the potentials are Yukawa-type, Re E > 0, and 1m E < O. The rotation angle can be picked independently of 1m E.
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