Complex Langevin and boundary terms
Abstract
As is well known the Complex Langevin (CL) method sometimes fails to converge or converges to the wrong limit. We identified one reason for this long ago: insufficient decay of the probability density either near infinity or near poles of the drift, leading to boundary terms that spoil the formal argument for correctness. To gain a deeper understanding of this phenomenon, we analyze the emergence of such boundary terms thoroughly in a simple model, where analytic results can be compared with numerics. We also show how some simple modification stabilizes the CL process in such a way that it can produce results agreeing with direct integration. Besides explicitly demonstrating the connection between boundary terms and correct convergence our analysis also suggests a correctness criterion which could be applied in realistic lattice simulations.
Cite
@article{arxiv.1808.05187,
title = {Complex Langevin and boundary terms},
author = {Manuel Scherzer and Erhard Seiler and Dénes Sexty and Ion-Olimpiu Stamatescu},
journal= {arXiv preprint arXiv:1808.05187},
year = {2019}
}
Comments
15 pages, 13 figures v2: changed format to two columns for journal submission, added references and a few comments on an old criterion for correctness v3: Added some plots and discussion on the criterion from citation [13]