2018/11/13 by Luigi Del Debbio, Del Debbio, Luigi, Francesco Di Renzo +3
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Lattice (hep-lat) #High-Energy Particle Collisions Research #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions
paper · pdf · doi:10.48550/arxiv.1811.05427
openalex publication_date 2018/11/13 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Numerical Stochastic Perturbation Theory (NSPT) enables very high order\ncomputations in Lattice Gauge Theories. We report on the determination of the\ngluon condensate from lattice QCD measurements of the basic plaquette. This is\na long standing problem, which was eventually solved a few years ago in pure\ngauge. In this context NSPT is crucial: it is actually the only tool enabling\nthe subtraction of the power divergent contribution associated to the identity\noperator in the OPE for the plaquette. This subtraction is actually a delicate\nissue, since the perturbative expansion of the plaquette is on general ground\nexpected to be an asymptotic one, due to renormalons. This in turn results in\nambiguities and the separation of scales in the OPE does not correspond to a\nseparation of perturbative and non-perturbative contributions. All in all, one\nneeds to absorb the ambiguities attached to the perturbative series into the\ndefinition of the condensate itself, i.e. one needs a prescription. A possible\none amounts to summing the perturbative series up to its minimal term, which\nmeans computing up to orders which only NSPT can aim at. Our computation is the\nfirst one in QCD, with massless staggered fermions. In order to remove the\nzero-mode of the gauge field, twisted boundary conditions are adopted for the\nlatter, consistently coupled to fermions in the fundamental representation\nsupplemented with smell degrees of freedom.\n