Some remarks on Lefschetz thimbles and complex Langevin dynamics

Understand

Lefschetz thimbles and complex Langevin dynamics both provide a means to tackle the numerical sign problem prevalent in theories with a complex weight in the partition function, e.g.

• due to nonzero chemical potential.
• Here we collect some findings for the quartic model, and for U(1) and SU(2) models in the presence of a determinant, which have some features not discussed before, due to a singular drift.
• We find evidence for a relation between classical runaways and stable thimbles, and give an example of a degenerate fixed point.