The self-energy of Friedrichs–Lee models and its application to bound states and resonances
Dipartimento di Fisica and MECENAS, Università di Bari, I-70126, Bari, Italy
2 INFN, Sezione di Bari, I-70126, Bari, Italy
Accepted: 4 April 2022
Published online: 21 April 2022
A system composed of two-level systems interacting with a single excitation of a one-dimensional boson field with continuous spectrum, described by a Friedrichs (or Friedrichs–Lee) model, can exhibit bound states and resonances; the latter can be characterized by computing the so-called self-energy of the model. We evaluate an analytic expression, valid for a large class of dispersion relations and coupling functions, for the self-energy of such models. Afterwards, we focus on the case of identical two-level systems, and we refine our analysis by distinguishing between dominant and suppressed contributions to the associated self-energy; we finally examine the phenomenology of bound states in the presence of a single dominant contribution.
© The Author(s) 2022
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