Coulomb Scattering in the Massless Nelson Model III: Ground State Wave Functions and Non-commutative Recurrence Relations

Abstract

Let H P,σ be the single-electron fiber Hamiltonians of the massless Nelson model at total momentum P and infrared cut-off σ > 0. We establish detailed regularity properties of the corresponding n-particle ground state wave functions f n P,σ as functions of P and σ. In particular, we show thatwhere c is a numerical constant, λ 0 → δ λ 0 is a positive function of the maximal admissible coupling constant which satisfies lim λ 0 →0 δ λ 0 = 0 and χ [σ,κ) is the (approximate) characteristic function of the energy region between the infrared cut-off σ and the ultraviolet cut-off κ. While the analysis of the first derivative is relatively straightforward, the second derivative requires a new strategy. By solving a non-commutative recurrence relation we derive a novel formula for f n P,σ with improved infrared properties. In this representation ∂ P j ′ ∂ P j f n P,σ is amenable to sharp estimates obtained by iterative analytic perturbation theory in part II of this series of papers. The bounds stated above are instrumental for scattering theory of two electrons in the Nelson model, as explained in part I of this series.

Non-Fock Ground States in the Translation-Invariant Nelson Model Revisited Non-Perturbatively

“…He was then able to construct asymptotic scattering states from these in [Piz05]. In recent years, Dybalski and Pizzo used this approach to study Coulomb scattering in Nelson's model in a series of papers [DP14b,DP18,DP19,DP22]. It is also noteworthy, that a novel construction of scattering states without an infrared limiting procedure was developed in the recent article [BDG21].…”

Differential Equations of Quantum Mechanics

“…Schlein ( [101,141,142,143,144,200,279]) as well as those from the n-particle scattering theory discussed above. For further developments [108,109,111,110,36,169] and review [264].…”