Absorption-edge singularities for a nonequilibrium Fermi sea. III. Determinantal nonperturbative theory.

Abstract

The nonperturbative solution to the problem of threshold singularities for a (${\mathrm{\ensuremath{\mu}}}_{1}$,${\mathrm{\ensuremath{\mu}}}_{2}$) nonequilibrium Fermi sea is obtained using the determinantal method of Ohtaka and Tanabe. The critical exponents of the absorption power-law behavior we find agree with those estimated from the perturbative treatment of the problem given in papers I and II. A family of possibly diverging singularities is found at energies ${\mathrm{\ensuremath{\mu}}}_{2}$+n(${\mathrm{\ensuremath{\mu}}}_{1}$-${\mathrm{\ensuremath{\mu}}}_{2}$), for n\ensuremath{\ge}1.