Concept

Metric tensor (general relativity)

Related publications (38)

4d Lorentzian Holst action with topological terms

We study the Hamiltonian formulation of the general first order action of general relativity compatible with local Lorentz invariance and background independence. The most general simplectic structure (compatible with diffeomorphism invariance and local Lo ...

2009

Finsler Conformal Lichnerowicz-Obata conjecture

Marc Troyanov

We prove the Finsler analog of the conformal Lichnerowicz-Obata conjecture showing that a complete and essential conformal vector field on a non-Riemannian Finsler manifold is a homothetic vector field of a Minkowski metric. ...

2009

Differential geometry applied to crystallography

Philippe Kocian

The mathematical facet of modern crystallography is essentially based on analytical geometry, linear algebra as well as group theory. This study endeavours to approach the geometry and symmetry of crystals using the tools furnished by differential geometry ...

EPFL2009

Non-metric coordinates for predicting network proximity

Dan-Cristian Tomozei

We consider the problem of determining the “closest”, or best Internet host to connect to, from a list of candidate servers. Most existing approaches rely on the use of metric, or more specifically Euclidean coordinates to infer network proximity. This is ...

IEEE2008

Classical big-bounce cosmology: dynamical analysis of a homogeneous and irrotational Weyssenhoff fluid

Sylvain Bréchet

A dynamical analysis of an effective homogeneous and irrotational Weyssenhoff fluid in general relativity is performed using the 1 + 3 covariant approach that enables the dynamics of the fluid to be determined without assuming any particular form for the s ...

Institute of Physics2008

Eikonal approximation in AdS/CFT: resumming the gravitational loop expansion

We derive an eikonal approximation to high energy interactions in Anti-de Sitter spacetime, by generalizing a position space derivation of the eikonal amplitude in flat space. We are able to resum, in terms of a generalized phase shift, ladder and cross la ...

Springer2007

Eikonal approximation in Ads/CFT: from shock waves to four-point functions

We initiate a program to generalize the standard eikonal approximation to compute amplitudes in Anti-de Sitter spacetimes. Inspired by the shock wave derivation of the eikonal amplitude in flat space, we study the two-point function epsilon similar to < O1 ...

Springer2007

Femtosecond holography in lithium niobate crystals

Demetri Psaltis

Spatial gratings are recorded holographically by two femtosecond pump pulses at 388 nm in lithium niobate (LiNbO3) crystals and read out by a Bragg-matched, temporally delayed probe pulse at 776 nm. We claim, to our knowledge, the first holographic pump-pr ...

2005

Enhanced temporal resolution in femtosecond dynamic-grating experiments

Demetri Psaltis

Recording of gratings by interference of two pump pulses and diffraction of a third probe pulse is useful for investigating ultrafast material phenomena. We demonstrate, in theory and experiment, that the temporal resolution in such configurations does not ...

2005

Multi-resolution SLAM for Real World Navigation

Roland Siegwart, Adriana Tapus, Kai Oliver Arras

In this paper a hierarchical multi-resolution approach allowing for high precision and distinctiveness is presented. The method combines topological and metric paradigm. The metric approach, based on the Kalman Filter, uses a new concept to avoid the probl ...

2003

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