Rooted staggered fermions: good, bad or ugly?

Abstract

I give a status report on the validity of the so-called ``fourth-root trick'', i.e. the procedure of representing the determinant for a single fermion by the fourth root of the staggered fermion determinant. This has been used by the MILC collaboration to create a large ensemble of lattices using which many quantities of physical interest have been and are being calculated. It is also used extensively in studies of QCD thermodynamics. The main question is whether the theory so defined has the correct continuum limit. There has been significant recent progress towards answering this question. After recalling the issue, and putting it into a broader context of results from statistical mechanics, I critically review the new work. I also address the related issue of the impact of treating valence and sea quarks differently in rooted simulations, discuss whether rooted simulations at finite temperature and density are subject to additional concerns, and briefly update results for quark masses using the MILC configurations. An answer to the question in the title is proposed in the summary.

Plenary talk at Lattice 2006 (42 pages, 6 figures, 2 appendices)

References in corpus (14)

• Staggered Chiral Perturbation Theory and the Fourth-Root Trick
• Observations on staggered fermions at non-zero lattice spacing
• Renormalization-group analysis of the validity of staggered-fermion QCD with the fourth-root recipe
• Breakdown of staggered fermions at nonzero chemical potential
• Lattice fermions with complex mass
• Validity of the Rooted Staggered Determinant in the continuum limit
• Estimating the Unquenched Strange Quark Mass from the Lattice Axial Ward Identity
• Applications of Chiral Perturbation theory to lattice QCD
• Power-counting theorem for staggered fermions
• Flavor extrapolations and staggered fermions
• Diseases with rooted staggered quarks
• The one-flavor quark condensate and related problems
• Why (staggered fermions)^{1/4} fail at finite density
• The rooted staggered determinant in the Schwinger model

Cited by in corpus (14)

• Full nonperturbative QCD simulations with 2+1 flavors of improved staggered quarks
• The density of states method at non-zero chemical potential
• Lattice QCD at finite temperature and density
• Thermodynamics of strong-interaction matter from Lattice QCD
• eta' meson From Two Flavor Dynamical Domain Wall Fermions
• Progress in Kaon Physics on the Lattice
• Lattice QCD at Finite Density
• Nonperturbative determination of $\beta$ functions for SU(3) gauge theories with 10 and 12 fundamental flavors using domain wall fermions
• Towards the N_f=2 deconfinement transition temperature with O(a) improved Wilson fermions
• Exploring the QCD phase diagram
• Progress in kaon physics on the lattice
• Light dynamical fermions on the lattice: toward the chiral regime of QCD
• Equation of State from Lattice QCD Calculations
• Universality and Scaling at the chiral transition in two-flavor QCD at finite temperature