PoS - Proceedings of Science
Volume 334 - The 36th Annual International Symposium on Lattice Field Theory (LATTICE2018) - Nonzero Temperature and Density
Complex Langevin for Lattice QCD
D.K. Sinclair,* J.B. Kogut
*corresponding author
Full text: pdf
Published on: May 29, 2019
We simulate lattice QCD at finite quark-number chemical potential, $\mu$, using the complex-Langevin equation (CLE) with gauge-cooling and adaptive updating to prevent instabilities. The CLE is used because QCD at finite $\mu$ has a complex fermion determinant which precludes the use of standard simulation methods based on importance sampling. Since, even when CLE simulations converge, they are not guaranteed to produce correct results except under very stringent conditions, which lattice QCD at finite $\mu$ does not obey, we need extensive testing to determine under what conditions it produces reliable results. We performed simulations at $\beta=6/g^2=5.6$ and $\beta=5.7$, both at $m=0.025$. For small $\mu$ and $\mu$ large enough to produce saturation, measured observables appear to be approaching their correct values as the coupling is decreased. However, for intermediate $\mu$ values, these simulations predict a transition from hadronic to nuclear matter at a $\mu$ which is far too small. Since there is evidence that for CLE simulations to produce correct results the trajectories should remain close to the $SU(3)$ manifold (at least for small $\mu$), we explore the parameter space to see where this is true. We find that the distance from this manifold decreases as the coupling decreases and as the quark mass (in lattice units) decreases, i.e. as we approach the continuum limit. This indicates that we need to simulate at smaller couplings and quark masses (requiring larger lattices) to see if these can produce the correct physics.
DOI: https://doi.org/10.22323/1.334.0143
How to cite

Metadata are provided both in "article" format (very similar to INSPIRE) as this helps creating very compact bibliographies which can be beneficial to authors and readers, and in "proceeding" format which is more detailed and complete.

Open Access
Creative Commons LicenseCopyright owned by the author(s) under the term of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.