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Articles 31 - 38 of 38

Full-Text Articles in Elementary Particles and Fields and String Theory

Rainich-Type Conditions For Null Electrovacuum Spacetimes Ii, Charles G. Torre Oct 2013

Rainich-Type Conditions For Null Electrovacuum Spacetimes Ii, Charles G. Torre

Research Vignettes

In this second of two worksheets I continue describing local Rainich-type conditions which are necessary and sufficient for the metric to define a null electrovacuum. In other words, these conditions, which I will call the null electrovacuum conditions, guarantee the existence of a null electromagnetic field such that the metric and electromagnetic field satisfy the Einstein-Maxwell equations. When it exists, the electromagnetic field is easily constructed from the metric. In this worksheet I consider the null electrovacuum conditions which apply when a certain null geodesic congruence determined by the metric is twisting. I shall illustrate the these conditions using a …


The Spacetime Geometry Of A Null Electromagnetic Field, Charles G. Torre Jul 2013

The Spacetime Geometry Of A Null Electromagnetic Field, Charles G. Torre

Presentations and Publications

We give a set of local geometric conditions on a spacetime metric which are necessary and sufficient for it to be a null electrovacuum, that is, the metric is part of a solution to the Einstein-Maxwell equations with a null electromagnetic field. These conditions are restrictions on a null congruence canonically constructed from the spacetime metric, and can involve up to five derivatives of the metric. The null electrovacuum conditions are counterparts of the Rainich conditions, which geometrically characterize non-null electrovacua. Given a spacetime satisfying the conditions for a null electrovacuum, a straightforward procedure builds the null electromagnetic field from …


How To Find Killing Vectors, Charles G. Torre Mar 2013

How To Find Killing Vectors, Charles G. Torre

How to... in 10 minutes or less

We show how to compute the Lie algebra of Killing vector fields of a metric in Maple using the commands KillingVectors and LieAlgebraData. A Maple worksheet and a PDF version can be found below.


Semiclassical Partition Functions For Gravity With Cosmic Strings, Christopher L. Duston Jan 2013

Semiclassical Partition Functions For Gravity With Cosmic Strings, Christopher L. Duston

Physics Faculty Publications

In this paper we describe an approach to construct semiclassical partition functions in gravity which are complete in the sense that they contain a complete description of the differentiable structures of the underlying 4-manifold. In addition, we find our construction naturally includes cosmic strings. We prove that the mass density of these strings uniquely specifies the topology of the leaves of a dimension 2 foliation, and conjecture that spacetime topology emerges as a result of the symmetry breaking of the fundamental fields. We discuss some possible applications of the partition functions in the fields of both quantum gravity and topological …


Black Holes In The Conical Ensemble, Robert A. Mcnees Iv, Daniel Grumiller Oct 2012

Black Holes In The Conical Ensemble, Robert A. Mcnees Iv, Daniel Grumiller

Physics: Faculty Publications and Other Works

We consider black holes in an “unsuitable box”: a finite cavity coupled to a thermal reservoir at a temperature different than the black hole’s Hawking temperature. These black holes are described by metrics that are continuous but not differentiable due to a conical singularity at the horizon. We include them in the Euclidean path integral sum over configurations, and analyze the effect this has on black hole thermodynamics in the canonical ensemble. Black holes with a small deficit (or surplus) angle may have a smaller internal energy or larger density of states than the nearby smooth black hole, but they …


Light Vs. Quantum Gravity, Irving Martinez^* Apr 2012

Light Vs. Quantum Gravity, Irving Martinez^*

COURI Symposium Abstracts, Spring 2012

No abstract provided.


Holographic Renormalization Of Asymptotically Lifshitz Spacetimes, Robert A. Mcnees Iv, Robert Mann Oct 2011

Holographic Renormalization Of Asymptotically Lifshitz Spacetimes, Robert A. Mcnees Iv, Robert Mann

Physics: Faculty Publications and Other Works

A variational formulation is given for a theory of gravity coupled to a massive vector in four dimensions, with Asymptotically Lifshitz boundary conditions on the fields. For theories with critical exponent z=2 we obtain a well-defined variational principle by explicitly constructing two actions with local boundary counterterms. As part of our analysis we obtain solutions of these theories on a neighborhood of spatial infinity, study the asymptotic symmetries, and consider different definitions of the boundary stress tensor and associated charges. A constraint on the boundary data for the fields figures prominently in one of our formulations, and in that case …


Complex Multiplication Symmetry Of Black Hole Attractors, Monika Lynker, Vipul Periwal, Rolf Schimmrigk Sep 2003

Complex Multiplication Symmetry Of Black Hole Attractors, Monika Lynker, Vipul Periwal, Rolf Schimmrigk

Faculty Articles

We show how Moore’s observation, in the context of toroidal compactifications in type IIB string theory, concerning the complex multiplication structure of black hole attractor varieties, can be generalized to Calabi-Yau compactifications with finite fundamental groups. This generalization leads to an alternative general framework in terms of motives associated to a Calabi-Yau variety in which it is possible to address the arithmetic nature of the attractor varieties in a universal way via Deligne’s period conjecture.