Simulation of dynamical fermions with smeared links

TL;DR

This paper introduces a new algorithm for simulating dynamical fermions with smeared links, improving efficiency and chiral properties in lattice QCD simulations, and demonstrating its effectiveness with four-flavor staggered fermions.

Contribution

A novel algorithm utilizing smeared links for efficient simulation of dynamical fermions, applicable to complex chiral fermionic actions.

Findings

Simulation cost is 2-8 times higher than standard HMC on 10 fm^4 volumes.

HYP smeared links improve chiral properties and allow coarser lattices.

Potential applicability to overlap and perfect fermion actions.

Abstract

Smearing the gauge links of dynamical configurations removes small scale unphysical vacuum fluctuations und thus improves the chiral properties of lattice fermions. We present a new algorithm for the simulation of dynamical fermions coupled via smeared links based on the standard pure gauge overrelaxation and heatbath updatings. Smeared links play a fundamental role in making this algorithm effective. At fixed lattice spacing the computational cost of the algorithm has an extra volume factor due to the finite volume of the lattice region which can be updated. As the continuum limit is approached the physical volume of the updated region remains constant. We simulated four flavors of staggered fermions coupled via hypercubic (HYP) smeared links. The simulation cost of the new algorithm on 10 fm^4 volumes is a factor 2-8 larger than with the standard Hybrid Monte Carlo but the improved properties of the HYP action allow to gain a factor 2 in the lattice spacing. The new algorithm could be applicable to simulations of more complicated chiral fermionic actions, like overlap or perfect actions.