Preparing for N_f=2 simulations at small lattice spacings

TL;DR

This paper examines large effects of dynamical fermions in lattice QCD, focusing on cutoff effects and multi-pion contributions, and prepares for small lattice spacing simulations to study discretization errors.

Contribution

It presents a plan for simulations at very small lattice spacings to analyze O(a^2) effects in the O(a)-improved theory, using Schrödinger functional coupling.

Findings

Identification of cutoff effects and multi-pion contributions.

Preparation for simulations at a≈0.04fm.

Determination of lattice spacing dependence on bare coupling.

Abstract

We discuss some large effects of dynamical fermions. One is a cutoff effect, others concern the contribution of multi-pion states to correlation functions and are expected to survive the continuum limit. We then turn to the preparation for simulations at small lattice spacings which we are planning down to around a=0.04fm in order to understand the size of O(a^2)-effects of the standard O(a)-improved theory. The dependence of the lattice spacing on the bare coupling is determined through the Schr"odinger functional renormalized coupling.