Effective Field Theory for Two-Body Systems with Shallow S-Wave Resonances

J. Balal Habashi, S. Fleming, S. Sen, U. van Kolck

Research output: Contribution to journalArticlepeer-review


Resonances are of particular importance to the scattering of composite particles in quantum mechanics. We build an effective field theory for two-body scattering which includes a low-energy S-wave resonance. Our starting point is the most general Lagrangian with short-range interactions. We demonstrate that these interactions can be organized into various orders so as to generate a systematic expansion for an S matrix with two low-energy poles. The pole positions are restricted by renormalization at leading order, where the common feature is a non-positive effective range. We carry out the expansion explicitly to next-to-leading order and illustrate how it systematically accounts for the results of a toy model — a spherical well with a delta shell at its border.

Original languageEnglish (US)
JournalUnknown Journal
StatePublished - Jul 14 2020

ASJC Scopus subject areas

  • General

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