scholarly journals Instability and chaos in spatially homogeneous field theories

1999 ◽  
Vol 40 (9) ◽  
pp. 4429-4443 ◽  
Author(s):  
Luca Salasnich
Keyword(s):  
Field Theories ◽  
Homogeneous Field ◽  
Spatially Homogeneous

Some Tests of the Marr-Ullman Model of Movement Detection

Perception ◽  
1986 ◽  
Vol 15 (2) ◽  
pp. 139-155 ◽  
Author(s):  
Bernard Moulden ◽  
Helena Begg
Keyword(s):  
Sudden Onset ◽  
Homogeneous Field ◽  
Movement Detection ◽  
Contrast Polarity ◽  
Apparent Direction ◽  
Direction Of Movement ◽  
Spatially Homogeneous ◽  
The Moment ◽  
Sawtooth Waveform

Several psychophysical experiments are described which test and uphold predictions derived from the Marr–Ullman model of movement detection. First, we demonstrate the existence of adaptation which is specific not merely to the direction of movement of an edge, but also to its contrast polarity. Second, it is shown that adaptation to a spatially homogeneous field whose luminance is modulated according to a temporal sawtooth waveform produces predictable changes in sensitivity to the movement of an edge; these changes, too, are specific to particular conjunctions of direction and edge polarity. Third, similar changes in sensitivity are demonstrated to occur when the luminance of an edge is physically perturbed at the moment of its displacement. Finally, it is shown that, as predicted, the sudden onset of an edge can itself give rise to a momentary impression of movement, the apparent direction of which depends upon the change in luminance that accompanies the onset of the edge.

Beyond the Standard Model

2017 ◽  
Author(s):  
Laurent Baulieu ◽  
John Iliopoulos ◽  
Roland Sénéor
Keyword(s):  
Field Theory ◽  
General Relativity ◽  
Supergravity Models ◽  
Standard Model ◽  
Field Theories ◽  
Beyond The Standard Model ◽  
Super Symmetry ◽  
The Standard Model ◽  
Topological Field ◽  
Supersymmetric Theories

The motivation for supersymmetry. The algebra, the superspace, and the representations. Field theory models and the non-renormalisation theorems. Spontaneous and explicit breaking of super-symmetry. The generalisation of the Montonen–Olive duality conjecture in supersymmetric theories. The remarkable properties of extended supersymmetric theories. A brief discussion of twisted supersymmetry in connection with topological field theories. Attempts to build a supersymmetric extention of the standard model and its experimental consequences. The property of gauge supersymmetry to include general relativity and the supergravity models.

Introduction

2018 ◽  
Author(s):  
Marjorie Levinson
Keyword(s):  
Modern Philosophy ◽  
Early Modern ◽  
Martin Heidegger ◽  
Conceptual Structure ◽  
Field Theories ◽  
Self Organization ◽  
Physical Sciences ◽  
Early Modern Philosophy

The Introduction explains the combination of a narrative arc and conceptual structure in the organization of the book. The former, primarily diachronic, discussion is concerned with the development of the field of Romanticism since the 1980s, presented through both a review of scholarship and exemplary readings of well-known lyric poems. The latter, predominantly synchronic, presentation entails an argument for the analytical value of field theories of form—that is, frameworks drawn from early modern philosophy (Spinoza) and postclassical life- and physical sciences, especially models of self-organization. As an alternative to the external, retrospective perspective provided by, for example, Rita Felski in The Limits of Critique, it draws on the work of Martin Heidegger, Pierre Macherey, and the poet-critic J. H. Prynne to offer a conjunctural approach.

Gauge Field Theory in Natural Geometric Language

2020 ◽  
Author(s):  
Daniel Canarutto
Keyword(s):  
Particle Physics ◽  
Quantum Physics ◽  
Brst Symmetry ◽  
Natural Extension ◽  
Integrated Approach ◽  
Arbitrary Spin ◽  
Field Theories ◽  
Quantum Field Theories ◽  
Standard View ◽  
Spinor Bundle

This monograph addresses the need to clarify basic mathematical concepts at the crossroad between gravitation and quantum physics. Selected mathematical and theoretical topics are exposed within a not-too-short, integrated approach that exploits standard and non-standard notions in natural geometric language. The role of structure groups can be regarded as secondary even in the treatment of the gauge fields themselves. Two-spinors yield a partly original ‘minimal geometric data’ approach to Einstein-Cartan-Maxwell-Dirac fields. The gravitational field is jointly represented by a spinor connection and by a soldering form (a ‘tetrad’) valued in a vector bundle naturally constructed from the assumed 2-spinor bundle. We give a presentation of electroweak theory that dispenses with group-related notions, and we introduce a non-standard, natural extension of it. Also within the 2-spinor approach we present: a non-standard view of gauge freedom; a first-order Lagrangian theory of fields with arbitrary spin; an original treatment of Lie derivatives of spinors and spinor connections. Furthermore we introduce an original formulation of Lagrangian field theories based on covariant differentials, which works in the classical and quantum field theories alike and simplifies calculations. We offer a precise mathematical approach to quantum bundles and quantum fields, including ghosts, BRST symmetry and anti-fields, treating the geometry of quantum bundles and their jet prolongations in terms Frölicher's notion of smoothness. We propose an approach to quantum particle physics based on the notion of detector, and illustrate the basic scattering computations in that context.

scholarly journals Cosmic Analogues of Classic Variational Problems

Universe ◽  
2020 ◽  
Vol 6 (6) ◽  
pp. 71 ◽  
Author(s):  
Valerio Faraoni
Keyword(s):  
Relativistic Particle ◽  
Friedmann Equation ◽  
Variational Calculus ◽  
Variational Problems ◽  
Particle Mechanics ◽  
One Dimensional ◽  
Spatially Homogeneous

Several classic one-dimensional problems of variational calculus originating in non-relativistic particle mechanics have solutions that are analogues of spatially homogeneous and isotropic universes. They are ruled by an equation which is formally a Friedmann equation for a suitable cosmic fluid. These problems are revisited and their cosmic analogues are pointed out. Some correspond to the main solutions of cosmology, while others are analogous to exotic cosmologies with phantom fluids and finite future singularities.

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