Moment Problems and Spectral Functions

Abstract

Nevanlinna-Pick interpolation and moment problems use the analytic structures provided by causality in order to provide rigorous bounds on smeared spectral functions. This proceedings discusses Nevanlinna-Pick interpolation and moment problems and reviews some useful results, including a simple proof that the space of causal data in Nevanlinna--Pick interpolation is convex.

Comments: 7 pages, Contribution to the 42nd International Symposium on Lattice Field Theory (LATTICE2025), 2-8 November 2025, Tata Institute of Fundamental Research, Mumbai, India