2025/09/16 by Anosh Joseph, Joseph, Anosh, Arpith Kumar +1
Physics and Astronomy · #Advanced Thermodynamics and Statistical Mechanics #FOS: Physical sciences #High Energy Physics - Lattice (hep-lat) #High Energy Physics - Theory (hep-th) #Statistical Mechanics and Entropy #Theoretical and Computational Physics
paper · pdf · doi:10.48550/arxiv.2509.13314
openalex publication_date 2025/09/16 · openalex created_date 2025/10/18 · openalex updated_date 2026/07/28
We investigate the applicability of complex Langevin dynamics to the three-dimensional XY model at finite chemical potential. To assess correctness, we introduce a new diagnostic based on the configurational temperature (or configurational coupling) estimator, recently proposed as a thermodynamic consistency check. We compare this criterion with the established Nagata-Nishimura-Shimasaki drift-decay test across a range of couplings and chemical potentials. Our results show that complex Langevin dynamics yields reliable results in the ordered phase (large β), but fails in the disordered phase (small β), even when the sign problem is mild. The configurational estimator provides a clear and physics-driven reliability test that complements drift-based diagnostics. These findings establish the estimator as a practical tool for identifying incorrect convergence, and highlight its potential for broader applications in lattice field theories with complex actions.