New algorithms and new results for strong coupling LQCD

TL;DR

This paper introduces and compares novel algorithms for strong coupling lattice QCD with staggered fermions, utilizing a Hamiltonian approach that eliminates the sign problem and enables studies at finite baryon density.

Contribution

The paper presents new algorithms based on a Hamiltonian formulation for strong coupling lattice QCD, demonstrating their effectiveness and absence of the sign problem.

Findings

Sign problem is completely absent at zero and non-zero baryon density.

Comparison shows performance differences between worm and SSE algorithms.

First exploratory study of two-flavor strong coupling lattice QCD using SSE.

Abstract

We present and compare new types of algorithms for lattice QCD with staggered fermions in the limit of infinite gauge coupling. These algorithms are formulated on a discrete spatial lattice but with continuous Euclidean time. They make use of the exact Hamiltonian, with the inverse temperature beta as the only input parameter. This formulation turns out to be analogous to that of a quantum spin system. The sign problem is completely absent, at zero and non-zero baryon density. We compare the performance of a continuous-time worm algorithm and of a Stochastic Series Expansion algorithm (SSE), which operates on equivalence classes of time-ordered interactions. Finally, we apply the SSE algorithm to a first exploratory study of two-flavor strong coupling lattice QCD, which is manageable in the Hamiltonian formulation because the sign problem can be controlled.