Functional Fit Approach (FFA) for Density of States method: SU(3) spin system and SU(3) lattice gauge theory with static color sources

TL;DR

This paper applies the Functional Fit Approach, a variant of the Density of States method, to SU(3) models to address the complex action problem at finite density, demonstrating its effectiveness through comparison with dual Monte Carlo results.

Contribution

The paper introduces the application of the DoS FFA to SU(3) spin and gauge models, providing a new computational approach for finite density QCD-related systems.

Findings

Good agreement with dual Monte Carlo results for the SU(3) spin model

First results for particle number dependence on coupling and chemical potential in SU(3) gauge theory

Demonstrates the feasibility of DoS FFA in complex action systems

Abstract

We apply a recently developed variant of the Density of States (DoS) method, the so-called Functional Fit Approach (FFA) to two different models: the SU(3) spin model and SU(3) lattice gauge theory with static color sources. Both models can be derived from QCD and inherit the complex action problem at finite density. We discuss the implementation of DoS FFA in the two models and compute observables related to the particle density. For the SU(3) spin model we show that the results are in good agreement with the results from a Monte Carlo simulation in the dual formulation, which is free of the complex action problem. For the case of SU(3) lattice gauge theory with static color sources we present first results for the particle number as a function of the coupling for different values of the chemical potential.