Artículos con la etiqueta ‘High Energy Physics – Theory (hep-th)’

Wilson’s renormalization group: a paradigmatic shift

Por • 17 feb, 2014 • Category: Leyes

A personal and subjective recollection, concerning mainly Wilson’s lectures delivered over the spring of 1972 at Princeton University (summary of a talk at Cornell University on November 16, 2013 at the occasion of the memorial Kenneth G. Wilson conference).

The Last 50 Years of General Relativity and Gravitation: From GR3 to GR20 Warsaw Conferences

Por • 28 dic, 2013 • Category: Leyes

This article has a dual purpose: i) to provide a flavor of the scientific highlights of the landmark conference, GR3, held in July 1962 at Jablonna, near Warsaw; and, ii) to present a bird’s eye view of the tremendous advances that have occurred over the half century that separates GR3 and GR20, which was again held in Warsaw in July 2013.

Relative information at the foundation of physics

Por • 9 nov, 2013 • Category: Filosofía

Shannon’s notion of relative information between two physical systems can function as foundation for statistical mechanics and quantum mechanics, without referring to subjectivism or idealism. It can also represent a key missing element in the foundation of the naturalistic picture of the world, providing the conceptual tool for dealing with its apparent limitations. I comment on the relation between these ideas and Democritus.

A Critical History of Renormalization

Por • 22 oct, 2013 • Category: Crítica

The history of renormalization is reviewed with a critical eye, starting with Lorentz’s theory of radiation damping, through perturbative QED with Dyson, Gell-Mann & Low, and others, to Wilson’s formulation and Polchinski’s functional equation, and applications to «triviality», and dark energy in cosmology.

On first attempts to reconcile quantum principles with gravity

Por • 2 oct, 2013 • Category: Leyes

In his 1916’s first paper on gravitational waves Einstein began to speculate on interactions between the principles of the old quantum theory and his theory of gravitation. With this contribution Einstein has stimulated a lot of similar speculations, during the dawn and the development of Quantum Mechanics. These speculations have culminated with the first attempt to quantize the gravitational field, that was provided by Rosenfeld in 1930. In this paper we briefly explain why this period (1916-1930) should be inserted into the history of Quantum Gravity and then we focus on Klein’s approach to the problem of reconciling Wave Mechanics with gravity, during the two-years period 1926-1927. His attempt should be looked as the prehistory of Quantum Field Theory in a curved background.

The High-Energy Interpretation of Quantum Mechanics

Por • 13 sep, 2013 • Category: Crítica

We address the issue of the interpretation of quantum mechanics by asking why the issue never arises in the description of high-energy interactions. We argue that several tenets of quantum mechanics, specifically the collapse of the wave function, follow directly once one accepts the essential randomness of fundamental interaction events. We then show that scale separation of fundamental interactions ensures that decoherent measurement can be unambiguously separated from the random quantum events. Finally, we argue that the fundamental symmetries of space and time guarantee the existence of a unique preferred basis. We argue that this set of ideas might lead to an interpretation of quantum mechanics, or rather, show in which sense an «interpretation» is (or is not) necessary.

QED Second Order Corrections on the Speed of Light at Low Temperature

Por • 24 ago, 2013 • Category: Crítica

We want to study thermal corrections on the speed of light at low temperature considering temperature dependence of photon vacuum polarization tensor at two-loop level in the standard QED. It is found that the heat bath behaves as a dispersive medium to the propagation of light and reduces its speed proprtional to the second order of temperature. Similiraties and differences with already known calculations which are based on Euler-Heisenberg Lagrangian and/or those using temperature dependent electromagnetic properties of the medium are discussed.

The Legacy of Ken Wilson

Por • 11 ago, 2013 • Category: Ambiente

This is a brief account of the legacy of Ken Wilson in statistical physics, high energy physics, computing and education.


Por • 30 jul, 2013 • Category: Leyes

Valid ideas that physical reality is vastly larger than human perception of it, and that the perceived part may not be representative of the whole, exist on many levels and have a long history. After a brief general inventory of those ideas and their implications, I consider the cosmological «multiverse» much discussed in recent scientific literature. I review its theoretical and (broadly) empirical motivations, and its disruptive implications for the traditional program of fundamental physics. I discuss the inflationary axion cosmology, which provides an example where firmly rooted, plausible ideas from microphysics lead to a well-characterized «mini-multiverse» scenario, with testable phenomenological consequences.

Generalized gravitational entropy

Por • 9 jul, 2013 • Category: Ciencia y tecnología

We consider classical Euclidean gravity solutions with a boundary. The boundary contains a non-contractible circle. These solutions can be interpreted as computing the trace of a density matrix in the full quantum gravity theory, in the classical approximation. When the circle is contractible in the bulk, we argue that the entropy of this density matrix is given by the area of a minimal surface. This is a generalization of the usual black hole entropy formula to euclidean solutions without a Killing vector.
A particular example of this set up appears in the computation of the entanglement entropy of a subregion of a field theory with a gravity dual. In this context, the minimal area prescription was proposed by Ryu and Takayanagi. Our arguments explain their conjecture.