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arXiv · 2608.08862

Chemical Potential and Analytic Continuation for Non-Hermitian Lattice Fermions

Chen-Te Ma·Hui Zhang
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Abstract

We introduce a chemical potential for non-Hermitian lattice fermions and show that, for even flavors with degenerate masses and paired chemical potentials $(\mu,-\mu)$ or $(i\mu,i\mu)$, the Hybrid Monte Carlo algorithm is free of the sign problem. For one-dimensional free fermions, we demonstrate that the sign problem is a numerical rather than physical obstruction and derive the exact propagator, which is analytic at finite lattice spacing away from its poles but becomes non-analytic in the continuum limit. Finally, we use AI-assisted fitting to perform analytic continuation from imaginary to real chemical potentials.

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Chen-Te Ma, Hui Zhang. 2026-08-09. Chemical Potential and Analytic Continuation for Non-Hermitian Lattice Fermions. https://arxiv.org/abs/2608.08862

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