Date: Thu, 29 Oct 15 00:20:30 GMT Subject: hep-lat daily 4 new + crosses received by eprepget ------------------------------------------------------------------------------ ------------------------------------------------------------------------------ Send any comments regarding submissions directly to submitter. ------------------------------------------------------------------------------ Archives at http://arxiv.org/ To unsubscribe, e-mail To: hep-lat@arXiv.org, Subject: cancel ------------------------------------------------------------------------------ received by eprepget from Tue 27 Oct 15 20:00:00 GMT to Wed 28 Oct 15 20:00:00 GMT ------------------------------------------------------------------------------ \\ arXiv:1510.08208 Date: Wed, 28 Oct 2015 06:57:10 GMT (360kb) Title: The Yang-Mills gradient flow and lattice effective action Authors: Ryo Yamamura Categories: hep-lat hep-th Comments: 16 pages, 3 figures Report-no: OU-HET-877 \\ Recently, the Yang-Mills gradient flow is found to be a useful concept not only in lattice simulations but also in continuous field theories. Since its smearing property is similar to the Wilsoninan "block spin transformation", there might be deeper connection between them. In this work, we define the "effective action" which generates configurations at a finite flow time and derive the exact differential equation to investigate the flow time dependence of the action. Then Yang-Mills gradient flow can be regarded as the flow of the effective action. We also propose the flow time dependent gradient, where the differential equation becomes similar to the renormalization group equation. We discuss a possibility to regard the time evolution of the effective action as the Wilsonian renormalization group flow. \\ ( http://arxiv.org/abs/1510.08208 , 360kb) ------------------------------------------------------------------------------ \\ arXiv:1510.08360 Date: Wed, 28 Oct 2015 15:57:11 GMT (94kb,D) Title: (Dimensional) twisted reduction in large N gauge theories Authors: Liam Keegan and Alberto Ramos Categories: hep-lat Comments: Proceedings of the 33rd International Symposium on Lattice Field Theory Report-no: CERN-PH-TH-2015-254 \\ We show that the spontaneous breaking of center symmetry can be avoided on a $L^2\times 1^2$ lattice with the appropriate choice of twisted boundary conditions. In order for this to work it is crucial that the twisted boundary conditions are chosen in the reduced plane. This suggests that the choice of twist tensor can influence the directions in which color and space degrees of freedom become indistinguishable. We also present some preliminary quantitative data comparing the value of the plaquette for different forms of reduction. \\ ( http://arxiv.org/abs/1510.08360 , 94kb) ------------------------------------------------------------------------------ \\ arXiv:1510.08384 Date: Wed, 28 Oct 2015 17:27:58 GMT (467kb,D) Title: Direct calculation of hadronic light-by-light scattering Authors: Jeremy Green, Nils Asmussen, Oleksii Gryniuk, Georg von Hippel, Harvey B. Meyer, Andreas Nyffeler, and Vladimir Pascalutsa Categories: hep-lat hep-ph nucl-th Comments: 7 pages, 4 figures. Talk presented at the 33rd International Symposium on Lattice Field Theory (Lattice 2015), 14-18 July 2015, Kobe International Conference Center, Kobe, Japan Report-no: INT-PUB-15-062 \\ We report calculations of hadronic light-by-light scattering amplitudes via lattice QCD evaluation of Euclidean four-point functions of vector currents. These initial results include only the fully quark-connected contribution. Particular attention is given to the case of forward scattering, which can be related via dispersion relations to the $\gamma^* \gamma^* \to$ hadrons cross section, and thus allows lattice data to be compared with phenomenology. We also present a strategy for computing the hadronic light-by-light contribution to the muon anomalous magnetic moment. \\ ( http://arxiv.org/abs/1510.08384 , 467kb) ------------------------------------------------------------------------------ \\ arXiv:1510.08407 Date: Wed, 28 Oct 2015 18:38:29 GMT (2157kb) Title: More on the properties of the first Gribov region in Landau gauge Authors: Axel Maas Categories: hep-lat hep-ph hep-th Comments: 42 pages, 23 figures, 1 table \\ Complete gauge-fixing beyond perturbation theory in non-Abelian gauge theories is a non-trivial problem. This is particularly evident in covariant gauges, where the Gribov-Singer ambiguity gives an explicit formulation of the problem. In practice, this is a problem if gauge-dependent quantities between different methods, especially lattice and continuum methods, should be compared: Only when treating the Gribov-Singer ambiguity in the same way is the comparison meaningful. To provide a better basis for such a comparison the structure of the first Gribov region in Landau gauge, a subset of all possible gauge copies satisfying the perturbative Landau gauge condition, will be investigated. To this end, lattice gauge theory will be used to investigate a two-dimensional projection of the region for SU(2) Yang-Mills theory in two, three, and four dimensions for a wide range of volumes and discretizations. \\ ( http://arxiv.org/abs/1510.08407 , 2157kb) %-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%- %%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%% %%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%--- For subscribe options to combined physics archives, e-mail To: physics@arxiv.org, Subject: subscribe ----------------------------------------------------------------------------- For help on viewing and making submissions, see http://arxiv.org/help/