Scattering Resonance

A complex pole of the meromorphically continued resolvent or scattering matrix (or the analytic continuation of the Green's function) that represents quasi-bound or long-lived oscillatory modes associated with an obstacle, potential, or boundary; resonances generalize eigenvalues to open systems and encode decay rates and oscillation frequencies.

A complex pole of the meromorphically continued resolvent or scattering matrix that represents a metastable or quasi‑bound state in a scattering problem; its real part gives the oscillation frequency and its imaginary part the decay rate.