Fermion sign problem and the structure of Lee-Yang zeros. II. Finite temperature results for a model system without interactions (opens in new tab)

Beyond the analysis of the Lee-Yang (LY) zero of $\xi$ at $0$ K presented by our previous work [He et. al. Phys. Rev. E 113, 24115 (2026)], it is important but intricate to understand how these zeros evolve with temperature ($T$). Here, we use an analytically solvable noninteracting one-dimensional particle-on-a-ring model to address this. We determine the trajectories of these zeros and analyze how their evolution with $T$ reshapes the analytic...