Controlled atomic limit and analytic density of states in a strongly attractive random Kronig-Penney model

Abstract

We study the negative-energy density of states of a one-dimensional random Kronig-Penney model with independent and identically distributed attractive delta interactions. Each isolated interaction of strength $q<0$ has a bound state of energy $-q^2/4$. Using the inverse coupling $V=-1/q$, the Krein resolvent formula reduces the continuum problem to a lattice operator with random diagonal entries and energy-dependent hopping. Under a local analyticity assumption on the coupling density, we prove a controlled atomic limit. After energy is divided by the square of the attraction strength, the scaled density of states approaches the density of isolated binding energies with an exponentially small error on compact interior intervals. An explicit strong-attraction condition also gives real-analyticity of the density of states and the integrated density of states on the corresponding negative-energy interval. A support condition ensures that this interval belongs to the almost-sure spectrum. For a uniform coupling law, we obtain a concrete sufficient threshold and illustrate the spectral profile with finite-volume calculations based on the exact point-interaction recurrence.

22 pages, 2 figures