Lessons from two-dimensional QCD (N→∞): Vacuum structure, asymptotic series, instantons, and all that
نویسندگان
چکیده
منابع مشابه
Qcd Instantons in Vacuum and Matter
The singlet coupling to the topological charge density in the instanton vacuum, causes the instantons and antiinstantons to be screened over distances of the order of 1/2 fm. Dilute instanton systems behave as a free gas, while dense instanton systems behave as a plasma. The free gas behaviour is favored by a density of 1 fm −4. Owing to the Higgs mechanism, the η' mass is heavy (1100 MeV). The...
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We discuss two dimensional QCD(Nc → ∞) with fermions in the fundamental as well as adjoint representation. We find factorial growth ∼ (gNcπ) (2k)!(−1) k−1 (2π)2k in the coefficients of the large order perturbative expansion. We argue that this behavior is related to classical solutions of the theory, instantons, thus it has nonperturbative origin. Phenomenologically such a growth is related to ...
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Recently, we have pointed out that sign-coherent 4-dimensional structures can not dominate topological charge fluctuations in QCD vacuum at all scales. Here we show that an enhanced lower-dimensional coherence is possible. In pure SU(3) lattice gauge theory we find that in a typical equilibrium configuration about 80% of space-time points are covered by two oppositely-charged connected structur...
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The impact of dynamical fermions on the vacuum structure of QCD is explored. Of particular interest is the topological charge correlator, 〈q(x)q(0)〉, where negative values at small x reveal a sign-alternating layered structure to the topological-charge density of the QCD vacuum. We consider large 283×96 lattices from the MILC collaboration, and develop a new gluonic definition of the topologica...
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We present some generic arguments demonstrating that an effective Lagrangian Leff which, by definition, contains operators O n of arbitrary dimensionality in general is not convergent, but rather an asymptotic series. It means that the behavior of the far distant terms has a specific factorial dependence Leff ∼ ∑ n cnO Mn , cn ∼ n!, n ≫ 1. We discuss a few apparently different problems, which h...
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ژورنال
عنوان ژورنال: Physical Review D
سال: 1996
ISSN: 0556-2821,1089-4918
DOI: 10.1103/physrevd.53.5821