2005/12/11 by Kit Yan Wong, Howard D. Trottier, R. M. Woloshyn · 8 citations
Mathematics · Physics and Astronomy · #Mathematics #Monte Carlo method #Particle physics #Physics #Quantum Chromodynamics and Particle Interactions #Quantum chaos and dynamical systems #Statistical physics #Statistics #Theoretical and Computational Physics #hep-lat
paper · pdf · doi:10.1103/physrevd.73.094512
published in Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D. Particles and fields 73(9) (American Physical Society) · 14 pages, 8 figures
arxiv created 2005/12/11 · openalex publication_date 2006/05/31 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Perturbative expansions of several small Wilson loops are computed through next-to-next-to-leading order in unquenched lattice QCD, from Monte Carlo simulations at weak couplings. This approach provides a much simpler alternative to conventional diagrammatic perturbation theory, and is applied here for the first time to full QCD. Two different sets of lattice actions are considered: one set uses the unimproved plaquette gluon action together with the unimproved-staggered-quark action; the other set uses the one-loop-improved Symanzik gauge-field action together with the so-called asqtad improved-staggered-quark action. Simulations are also done with different numbers of dynamical fermions. An extensive study of the systematic uncertainties is presented, which demonstrates that the small third-order perturbative component of the observables can be reliably extracted from simulation data. We also investigate the use of the rational hybrid Monte Carlo algorithm for unquenched simulations with unimproved-staggered fermions. Our results are in excellent agreement with diagrammatic perturbation theory, and provide an important cross-check of the perturbation theory input to a recent determination of the strong coupling \ensuremathα_MS(MZ) by the HPQCD collaboration.