8,804 research outputs found
The Yang-Mills gradient flow and renormalization
In this proceedings contribution we will review the main ideas behind the
many recent works that apply the gradient flow to the determination of the
renormalized coupling and the renormalization of composite operators. We will
pay special attention to the continuum extrapolation of flow quantities.Comment: 17 pages. Proceedings of the 32nd International Symposium on Lattice
Field Theor
(Dimensional) twisted reduction in large N gauge theories
We show that the spontaneous breaking of center symmetry can be avoided on a
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.Comment: Proceedings of the 33rd International Symposium on Lattice Field
Theory. References update
The Yang-Mills gradient flow and SU(3) gauge theory with 12 massless fundamental fermions in a colour-twisted box
We perform the step-scaling investigation of the running coupling constant,
using the gradient-flow scheme, in SU(3) gauge theory with twelve massless
fermions in the fundamental representation. The Wilson plaquette gauge action
and massless unimproved staggered fermions are used in the simulations. Our
lattice data are prepared at high accuracy, such that the statistical error for
the renormalised coupling, g_GF, is at the subpercentage level. To investigate
the reliability of the continuum extrapolation, we employ two different lattice
discretisations to obtain g_GF. For our simulation setting, the corresponding
gauge-field averaging radius in the gradient flow has to be almost half of the
lattice size, in order to have this extrapolation under control. We can
determine the renormalisation group evolution of the coupling up to g^2_GF ~ 6,
before the onset of the bulk phase structure. In this infrared regime, the
running of the coupling is significantly slower than the two-loop perturbative
prediction, although we cannot draw definite conclusion regarding possible
infrared conformality of this theory. Furthermore, we comment on the issue
regarding the continuum extrapolation near an infrared fixed point. In addition
to adopting the fit ansatz a'la Symanzik for performing this task, we discuss a
possible alternative procedure inspired by properties derived from low-energy
scale invariance at strong coupling. Based on this procedure, we propose a
finite-size scaling method for the renormalised coupling as a means to search
for infrared fixed point. Using this method, it can be shown that the behaviour
of the theory around g^2_GF ~ 6 is still not governed by possible infrared
conformality.Comment: 24 pages, 6 figures; Published version; Appendix A added for
tabulating data; One reference included; Typos correcte
Darwin's Geological Research in Argentina
On the occasion of the 200th. anniversary of Charles Darwin´s birth, the Asociación Geológica Argentina decided to prepare a special issue devoted to the geological research undertaken by Darwin in Argentina. As it is well known, during his journeys on board HMS Beagle under the command of Captain Robert FitzRoy, he had the opportunity to survey overland different areas of South America. Darwin spent nearly three years - between August 1832 and April 1835 - visiting and studying different regions of our country. The aim of this special issue is to analyze his important geological observations and to emphasize the validity of many of his ideas under a 21st Century perspective. In order to accomplish this aim, several key localities that Darwin examined from a geological point of view during his voyage were selected. Such an analysis was carried out by several geologists and paleontologists well acquainted with the diverse problems that Darwin faced along his journeys in Argentina.Fil: Ramos, Victor Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentin
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