Comments on staggered fermions / Panel discussion

TL;DR

This paper critiques the use of the rooting procedure with staggered fermions, highlighting its non-perturbative limitations and potential systematic errors, especially for flavor singlet phenomena like the eta prime meson.

Contribution

It provides a critical analysis of the rooting procedure's validity in capturing non-perturbative effects in lattice QCD simulations.

Findings

Rooted staggered fermions may introduce uncontrolled systematic errors.

The method is an approximation and not a first principles approach.

Non-perturbative effects related to gauge topology are not correctly treated.

Abstract

The rooting procedure commonly used with staggered fermions does not correctly treat non-perturbative effects associated with gauge field topology. In practice these effects are small for the physics of flavor non-singlet particles. However large uncontrolled systematic errors are expected for flavor singlet issues, such as the mass of the eta prime meson. While the relative speed of the algorithm in large scale simulations may justify its use, the method is an approximation and should not be promoted as a first principles approach to the strong interactions.