Perturbative Wilson loops from unquenched Monte Carlo simulations at weak couplings

Journal Article · Mon May 01 04:00:00 EDT 2006 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.73.094512· OSTI ID:20783014

Wong, Kit Yan; Trottier, Howard D; Woloshyn, R M ^[1]

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1. Simon Fraser University, Department of Physics, 8888 University Drive, Burnaby, British Columbia, V5A 1S6 (Canada) and Department of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ (United Kingdom)

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 {alpha}{sub MS}(M{sub Z}) by the HPQCD collaboration.

• OSTI ID: 20783014
• Journal Information: Physical Review. D, Particles Fields, Journal Name: Physical Review. D, Particles Fields Journal Issue: 9 Vol. 73; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ALGORITHMS
COMPUTERIZED SIMULATION
GLUONS
MONTE CARLO METHOD
PERTURBATION THEORY
QUANTUM CHROMODYNAMICS
QUARKS
STRONG-COUPLING MODEL
WILSON LOOP