Instanton dominance over $$a_s$$ at low momenta from lattice QCD simulations at $$N_f=0$$, $$N_f=2+1$$ and $$N_f=2+1+1$$

Conference · Sun Apr 01 00:00:00 EDT 2018 · EPJ Web of Conferences

DOI:https://doi.org/10.1051/epjconf/201817512011· OSTI ID:1434241

Athenodorou, Andreas ^[1]; Boucaud, Philippe ^[2]; de Soto, Feliciano ^[3]; Rodriguez-Quintero, Jose ^[4]; Zafeiropoulos, Savvas ^[5]

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1. Cyprus Institute, Nicosia, Cyprus
2. Univ. Paris-Sud, Orsay (France)
3. Univ. Pablo de Olavide, 41013 Sevilla; Spain; Univ. of Granada (Spain)
4. Universidad de Huelva, 21071 Huelva; Spain; Univ. of Granada (Spain)
5. College of William and Mary, Williamsburg, VA (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Heidelberg Univ. (Germany). Inst. for Theoretische Physik

We report on an instanton-based analysis of the gluon Green functions in the Landau gauge for low momenta; in particular we use lattice results for αs in the symmetric momentum subtraction scheme (MOM) for large-volume lattice simulations. We have exploited quenched gauge field configurations, Nf = 0, with both Wilson and tree-level Symanzik improved actions, and unquenched ones with Nf = 2 + 1 and Nf = 2 + 1 + 1 dynamical flavors (domain wall and twisted-mass fermions, respectively).We show that the dominance of instanton correlations on the low-momenta gluon Green functions can be applied to the determination of phenomenological parameters of the instanton liquid and, eventually, to a determination of the lattice spacing.We furthermore apply the Gradient Flow to remove short-distance fluctuations. The Gradient Flow gets rid of the QCD scale, ΛQCD, and reveals that the instanton prediction extents to large momenta. For those gauge field configurations free of quantum fluctuations, the direct study of topological charge density shows the appearance of large-scale lumps that can be identified as instantons, giving access to a direct study of the instanton density and size distribution that is compatible with those extracted from the analysis of the Green functions.

• Research Organization: Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Nuclear Physics (NP)
• DOE Contract Number: AC05-06OR23177
• OSTI ID: 1434241
• Report Number(s): JLAB-THY-18-2689; DOE/OR/23177-4421; arXiv:1802.01342
• Journal Information: EPJ Web of Conferences, Vol. 175; Conference: Lattice 2017, 35th International Symposium on Lattice Field Theory, 18-24 Jun 2017. Granada, Spain
• Country of Publication: United States
• Language: English