Scalar QCD at nonzero density

TL;DR

This paper investigates scalar QCD at finite density in the strong coupling limit, demonstrating a dual formulation that eliminates the sign problem and proposing a hybrid update algorithm for simulations.

Contribution

It introduces a dual variable representation for scalar QCD at nonzero density that removes the sign problem and suggests an efficient hybrid update method.

Findings

Dual variables remove the sign problem.

At least 3 flavors needed for nontrivial chemical potential dependence.

Proposed hybrid update approach combining local and worm algorithms.

Abstract

We study scalar QCD at nonzero density in the strong coupling limit. It has a sign problem which looks structurally similar to the one in QCD. We show first data for the reweighting factor. After introducing dual variables by integrating out the SU(3) gauge links, we find that at least 3 flavors are needed for a nontrivial dependence on the chemical potential. In this dual representation there is no sign problem remaining. The dual variables are partially constrained, thus we propose to use a hybrid approach for the updates: For unconstrained variables local updates can be used, while for constrained variables using updates based on the worm algorithm is more promising.