arXiv subjects

Antonio González-Arroyo

Publications and source records attributed to Antonio González-Arroyo.

44 records · Page 3Linked to original sources

arXiv2013

Confinement in large N gauge theories

We report some recent results obtained for large N gauge theories which support the idea of volume reduction. Results for the string tension of the Twisted Eguchi-Kawai model match with those obtained from extrapolation from finite N. Determination of other observables is currently under way. Application of the twisted reduction idea to the case of 1 or 2 flavours of quarks in the adjoint representation of the group offers promising results. Preliminary results for the string tension point towards a very different behaviour for 1 and 2 flavours. While the string tension remains finite for 1 flavour at the critical massless quark limit, it seems to vanish with a large anomalous dimension for the $N_f=2$ case. This is consistent with the predicted Infrared fixed point expected in the latter case.

hep-lat↗

arXiv2013

The string tension from smeared Wilson loops at large N

We present the results of a high statistics analysis of smeared Wilson loops in 4 dimensional SU(N) Yang-Mills theory for various values of N. The data is used to analyze the behaviour of smeared Creutz ratios, extracting from them the value of the string tension and other asymptotic parameters. A scaling analysis allows us to extrapolate to the continuum limit for N=3,5,6 and 8. The results are consistent with a $1/N^2$ approach towards the large N limit. The same analysis is done for the TEK model (one-point lattice) for N=841 and a non-minimal symmetric twist with flux of $k=9$. The results match perfectly with the extrapolated large N values, confirming the validity of the reduction idea for this range of parameters.

hep-th↗

arXiv2012

The string tension for Large N gauge theory from smeared Wilson loops

Using smeared Creutz ratios we extract the string tension for SU(N) pure gauge theory and $N$=3,4,5,6,8. We employ these results to extrapolate to large N. The same methodology is applied to the single-site Twisted Eguchi Kawai model. The corresponding string tension matches perfectly within errors with the extrapolated one, providing strong evidence in favour of the twisted reduction framework. Interesting results are also obtained on the behaviour of Creutz ratios for large sizes.

hep-lat↗

arXiv2012

Twisted reduction in large N QCD with two adjoint Wilson fermions

The twisted reduced model of large $N$ QCD with two adjoint Wilson fermions is studied numerically using the Hybrid Monte Carlo method. This is the one-site model, whose large $N$ limit (large volume limit) is expected to be conformal or nearly conformal. The symmetric twist boundary condition with flux $k$ is used. $k$=0 corresponds to periodic boundary conditions. It is shown that the quark mass and $N$ dependencies of the model with non-vanishing $k$ differ significantly from those of the $k$=0 model. A preliminary result for the string tension calculated at $N$=289 is presented. The string tension seems to vanish as the physical quark mass decreases to zero in a way consistent with the theory being governed by an infrared fixed point with $γ_* = 0.8 \sim 1.2$.

hep-lat↗

arXiv2012

Real-time Quantum evolution in the Classical approximation and beyond

With the goal in mind of deriving a method to compute quantum corrections for the real-time evolution in quantum field theory, we analyze the problem from the perspective of the Wigner function. We argue that this provides the most natural way to justify and extend the classical approximation. A simple proposal is presented that can allow to give systematic quantum corrections to the evolution of expectation values and/or an estimate of the errors committed when using the classical approximation. The method is applied to the case of a few degrees of freedom and compared with other methods and with the exact quantum results. An analysis of the dependence of the numerical effort involved as a function of the number of variables is given, which allow us to be optimistic about its applicability in a quantum field theoretical context.

math-ph↗

arXiv2010

Probing the Yang-Mills vacuum with adjoint zero-modes

For the non-perturbative analysis of the topological content of Yang-Mills theories, it is essential to disentangle long-range structures from short-range fluctuations. Some time ago, one of us proposed to use the adjoint modes of the Dirac operator for this purpose. In this talk we analyse an implementation of this idea that associates two Weyl fermionic modes in the adjoint representation to every gauge field configuration. The densities of these modes provide a filtered image of the self-dual and anti self-dual parts of the gauge action density. We present successful tests on the performance of this proposal on a set of initial gauge field configurations.

hep-lat↗

arXiv2010

Large $N$ reduction with the Twisted Eguchi-Kawai model

We examine the breaking of $Z_N$ symmetry recently reported for the Twisted Eguchi-Kawai model (TEK). We analyse the origin of this behaviour and propose simple modifications of twist and lattice action that could avoid the problem. Our results show no sign of symmetry breaking and allow us to obtain values of the large $N$ infinite volume string tension in agreement with extrapolations from results based upon straightforward methods.

hep-th↗

arXiv2009

Adjoint fermion zero-modes for SU(N) calorons

We derive analytic formulas for the zero-modes of the Dirac equation in the adjoint representation in the background field of Q=1 SU(N) calorons. Solutions with various boundary conditions are obtained, including the physically most relevant cases of periodic and antiperiodic ones. The latter are essential ingredients in a semiclassical treatment of finite temperature supersymmetric Yang-Mills theory. A detailed discussion of adjoint zero-modes in several other contexts is also presented.

hep-th↗