Replacing the Breit-Wigner amplitude by the complex delta function to describe resonances

Whenever the Breit-Wigner amplitude appears in a calculation,there are many instances (e.g., Fermi's two-level system and the Weisskopf-Wigner approximation) where energy integrations are extended from the scattering spectrum of the Hamiltonian to the whole real line. Such extensions are perfor...

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Bibliographic Details
Published in:arXiv.org 2010-05
Main Author: de la Madrid, R
Format: Article
Language:English
Subjects:
Amplitudes
Delta function
Scattering
Online Access:Get full text
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Summary:Whenever the Breit-Wigner amplitude appears in a calculation,there are many instances (e.g., Fermi's two-level system and the Weisskopf-Wigner approximation) where energy integrations are extended from the scattering spectrum of the Hamiltonian to the whole real line. Such extensions are performed in order to obtain a desirable, causal result. In this paper, we recall several of those instances and show that substituting the Breit-Wigner amplitude by the complex delta function allows us to recover such desirable results without having to extend energy integrations outside of the scattering spectrum.
ISSN:2331-8422
DOI:10.48550/arxiv.1005.1290