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Search Results: 1 - 10 of 5708 matches for " Pilar Hernandez "
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La interfaz del objeto de aprendizaje/ The interface of the Learning Object
Pilar Hernandez
Revista Q , 2007,
Abstract: Este artículo hace parte del proceso de investigación documental y teórico, que se realizó en el marco de la investigación mencionada, con el fin de dar soporte conceptual a los importantes aportes que hace el dise o gráfico al proceso de construcción de objetos de aprendizaje. Se presenta a continuación un breve recorrido por las diferentes concepciones de los conceptos de interfaz y usabilidad, en tanto fundamentales en el logro, en primera instancia, de la comunicación y, en segunda instancia, la potenciación de los aprendizajes. This article is a part of the documental and theoretical process of investigation, of the project mention before, this has as a purpose to give a conceptual support to the important contributions from the graphic design to the process of construction of learning objects. In this is presented a brief journey about the different conceptions of the notion of interface and usability, as well as they are fundamental to consolidate of, in first place, the communication and, in second place, the promotion of the learning process.
A Lattice Construction of Chiral Gauge Theories
Pilar Hernandez,Raman Sundrum
Physics , 1995, DOI: 10.1016/0550-3213(95)00456-3
Abstract: We formulate chiral gauge theories non-perturbatively, using two different cuttoffs for the fermions and gauge bosons. We use a lattice with spacing $b$ to regulate the gauge fields in standard fashion, while computing the chiral fermion determinant on a finer lattice with spacing $f << b$. This determinant is computed in the background of $f$-lattice gauge fields, obtained by gauge-covariantly interpolating $b$-lattice gauge fields. The notorious doublers that plague lattice theories containing fermions are decoupled by the addition of a Wilson term. In chiral theories such a term breaks gauge invariance explicitly. However, the advantage of the two-cutoff regulator is that gauge invariance can be restored to $O(f^2/b^2)$ by a {\it one-loop} subtraction of calculable local gauge field counterterms. We show that the only obstruction to this procedure is the presence of an uncancelled gauge anomaly among the fermion representations. We conclude that for practical purposes, it suffices to choose $f/b \sim b/L$, where $L^4$ is the physical volume of the system. In our construction it is simple to prove the Adler-Bardeen theorem for anomalies in global currents to all orders. The related subject of fermion number violation is also studied. Finally, we discuss the prospects for improving the efficiency of our algorithm.
A New Lattice Action for Studying Topological Charge
Pilar Hernandez,Raman Sundrum
Physics , 1996, DOI: 10.1016/S0920-5632(96)00719-0
Abstract: We review our recent proposal for a new lattice action for non-abelian gauge theories which reduces short-range lattice artifacts in the computation of the topological susceptibility. The standard Wilson action is replaced by the Wilson action of a gauge covariant interpolation of the original fields to a finer lattice. We illustrate the improved behavior of a same-philosophy new lattice action in the $O(3)$ $\sigma$-model in two dimensions.
Lattice Gauge Field Interpolation for Chiral Gauge Theories
Pilar Hernandez,Raman Sundrum
Physics , 1996, DOI: 10.1016/S0920-5632(96)00745-1
Abstract: The importance of lattice gauge field interpolation for our recent non-perturbative formulation of chiral gauge theory is emphasized. We illustrate how the requisite properties are satisfied by our recent four-dimensional non-abelian interpolation scheme, by going through the simpler case of U(1) gauge fields in two dimensions.
A New Lattice Action for Studying Topological Charge
Pilar Hernandez,Raman Sundrum
Physics , 1996, DOI: 10.1016/0370-2693(96)00838-6
Abstract: We propose a new lattice action for non-abelian gauge theories, which will reduce short-range lattice artifacts in the computation of the topological susceptibility. The standard Wilson action is replaced by the Wilson action of a gauge covariant interpolation of the original fields to a finer lattice. If the latter is fine enough, the action of all configurations with non-zero topological charge will satisfy the continuum bound. As a simpler example we consider the $O(3)$ $\sigma$-model in two dimensions, where a numerical analysis of discretized continuum instantons indicates that a finer lattice with half the lattice spacing of the original is enough to satisfy the continuum bound.
Interpolation of Non-abelian Lattice Gauge Fields
Pilar Hernandez,Raman Sundrum
Physics , 1996, DOI: 10.1016/0550-3213(96)00215-5
Abstract: We propose a method for interpolating non-abelian lattice gauge fields to the continuum, or to a finer lattice, which satisfies the properties of (i) transverse continuity, (ii) (lattice) rotation and translation covariance, (iii) gauge covariance, (iv) locality. These are the properties required for use in our earlier proposal for non-perturbative formulation and simulation of chiral gauge theories.
Lattice Chiral Gauge Theory with Finely-Grained Fermions
Pilar Hernandez,Raman Sundrum
Physics , 1995,
Abstract: We discuss the problem of formulating the continuum limit of chiral gauge theories ($\chi$GT) in the absence of an explicitly gauge-invariant regulator for the fermions. A solution is proposed which is independent of the details of the regulator, wherein one considers two cutoff scales, $\Lambda_f >> \Lambda_b$, for the fermions and the gauge bosons respectively. Our recent non-perturbative lattice construction in which the fermions live on a finer lattice than do the gauge bosons, is seen to be an example of such a scheme, providing a finite algorithm for simulating $\chi$GT. The essential difference with previous (one-cutoff) lattice schemes is clarified: in our formulation the breakage of gauge invariance is small, $O(\Lambda^2_b/\Lambda^2_f)$, and vanishes in the continuum limit. Finally, we argue against 2-D models being significant testing grounds for 4-D regulators of $\chi$GT.
Probing the Neutrino Mass Hierarchy with Super-Kamiokande
Sanjib Kumar Agarwalla,Pilar Hernandez
Physics , 2012, DOI: 10.1007/JHEP10(2012)086
Abstract: We show that for recently discovered large values of theta(13), a superbeam with an average neutrino energy of ~ 5 GeV, such as those being proposed at CERN, if pointing to Super-Kamiokande (L = 8770 km), could reveal the neutrino mass hierarchy at 5 sigma in less than two years irrespective of the true hierarchy and CP phase. The measurement relies on the near resonant matter effect in the numu to nue oscillation channel, and can be done counting the total number of appearance events with just a neutrino beam.
A non-perturbative study of massive gauge theories
Michele Della Morte,Pilar Hernandez
Physics , 2013, DOI: 10.1007/JHEP11(2013)213
Abstract: We consider a non-perturbative formulation of an SU(2) massive gauge theory on a space-time lattice, which is also a discretised gauged non-linear chiral model. The lattice model is shown to have an exactly conserved global SU(2) symmetry. If a scaling region for the lattice model exists and the lightest degrees of freedom are spin one vector particles with the same quantum numbers as the conserved current, we argue that the most general effective theory describing their low-energy dynamics must be a massive gauge theory. We present results of a exploratory numerical simulation of the model and find indications for the presence of a scaling region where both a triplet vector and a scalar remain light.
From enemies to friends: chiral symmetry on the lattice
Pilar Hernandez,Karl Jansen,Laurent Lellouch
Physics , 2002,
Abstract: The physics of strong interactions is invariant under the exchange of left-handed and right-handed quarks, at least in the massless limit. This invariance is reflected in the chiral symmetry of quantum chromodynamics. Surprisingly, it has become clear only recently how to implement this important symmetry in lattice formulations of quantum field theories. We will discuss realizations of exact lattice chiral symmetry and give an example of the computation of a physical observable in quantum chromodynamics where chiral symmetry is important. This calculation is performed by relying on finite size scaling methods as predicted by chiral perturbation theory.
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