On causality, unitarity and perturbative expansions

Abstract

We present a pedagogical case study how to combine micro-causality and unitarity based on a perturbative approach. The method we advocate constructs an analytic extrapolation of partial-wave scattering amplitudes that is constrained by the unitarity condition. Suitably constructed conformal mappings help to arrive at a systematic approximation of the scattering amplitude. The technique is illustrated at hand of a Yukawa interaction. The typical case of a superposition of strong short-range and weak long-range forces is investigated.

12 pages, 12 figures

References in corpus (2)

• Photon- and pion-nucleon interactions in a unitary and causal effective field theory based on the chiral Lagrangian
• Effective chiral theory of nucleon-nucleon scattering

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