Adaptive stepsize and instabilities in complex Langevin dynamics

Understand

Stochastic quantization offers the opportunity to simulate field theories with a complex action.

• In some theories unstable trajectories are prevalent when a constant stepsize is employed.
• We construct algorithms for generating an adaptive stepsize in complex Langevin simulations and find that unstable trajectories are completely eliminated.
• To illustrate the generality of the approach, we apply it to the three-dimensional XY model at nonzero chemical potential and the heavy dense limit of QCD.