Korte reis naar Kopenhagen

Van 23 tot en met 27 januari was het weer zover: de korte reis der B.I.L. Dit keer ging de B.I.L. op bezoek in Kopenhagen. Hieronder vertelt Elmar van Holten, lid van de commissie Buitenland, wat de B.I.L. allemaal heeft beleefd in Kopenhagen

Cosmological Higgs fields

We present a time-dependent solution to the coupled Einstein-Higgs equations for general Higgs-type potentials in the context of flat FRW cosmological models. Possible implications are discussed.Comment: 5 pages, no figures. Version to be published in Phys. Rev. Lett. Changes: references and citations added; introduction partly modified; expanded discussion of relations between parameters in the Higgs potentia

Considerations on Super Poincare Algebras and their Extensions to Simple Superalgebras

We consider simple superalgebras which are a supersymmetric extension of \fspin(s,t) in the cases where the number of odd generators does not exceed 64. All of them contain a super Poincar\'e algebra as a contraction and another as a subalgebra. Because of the contraction property, some of these algebras can be interpreted as de Sitter or anti de Sitter superalgebras. However, the number of odd generators present in the contraction is not always minimal due to the different splitting properties of the spinor representations under a subalgebra. We consider the general case, with arbitrary dimension and signature, and examine in detail particular examples with physical implications in dimensions $d=10$ and $d=4$.Comment: 16 pages, AMS-LaTeX. Version to appear in the Reviews in Mathematical Physic

Quantum Mechanics of Yano tensors: Dirac equation in curved spacetime

In spacetimes admitting Yano tensors the classical theory of the spinning particle possesses enhanced worldline supersymmetry. Quantum mechanically generators of extra supersymmetries correspond to operators that in the classical limit commute with the Dirac operator and generate conserved quantities. We show that the result is preserved in the full quantum theory, that is, Yano symmetries are not anomalous. This was known for Yano tensors of rank two, but our main result is to show that it extends to Yano tensors of arbitrary rank. We also describe the conformal Yano equation and show that is invariant under Hodge duality. There is a natural relationship between Yano tensors and supergravity theories. As the simplest possible example, we show that when the spacetime admits a Killing spinor then this generates Yano and conformal Yano tensors. As an application, we construct Yano tensors on maximally symmetric spaces: they are spanned by tensor products of Killing vectors.Comment: 1+32 pages, no figures. Accepted for publication on Classical and Quantum Gravity. New title and abstract. Some material has been moved to the Appendix. Concrete formulas for Yano tensors on some special holonomy manifolds have been provided. Some corrections included, bibliography enlarge

Supersymmetry on AdS3 and AdS4

We consider a supersymmetric extension of the algebra associated with three and four dimensional Anti de Sitter space. A representation of the supersymmetry operators in superspace is given. Supersymmetry invariant models are constructed for the superspace associated with AdS3.Comment: 14 pages, no figures. Final published version. Now includes a discussion of the relation of our approach to previous work on supersymmetry in AdS space

Geodesic Deviation in Kaluza-Klein Theories

We study in detail the equations of the geodesic deviation in multidimensional theories of Kaluza-Klein type. We show that their 4-dimensional space-time projections are identical with the equations obtained by direct variation of the usual geodesic equation in the presence of the Lorentz force, provided that the fifth component of the deviation vector satisfies an extra constraint derived here.Comment: 5 pages, Revtex, 1 figure. To appear in Phys. Rev. D (Brief Report

Dynamics of (SUSY) AdS Space Isometry Breaking

Actions governing the dynamics of the Nambu-Goldstone modes resulting from the spontaneous breaking of the SO(4,2) and $SU(2,2|1)$ isometries of five dimensional anti-de Sitter space ($AdS_{5}$) and SUSY $AdS_{5}\times S_1$ spaces respectively due to a restriction of the motion to embedded four dimensional $AdS_{4}$ space and four dimensional Minkowski space ($M_4$) probe branes are presented. The dilatonic Nambu-Goldstone mode governing the motion of the $M_4$ space probe brane into the covolume of the SUSY $AdS_5\times S_1$ space is found to be unstable. No such instablility appears in the other cases. Gauging these symmetries leads to an Einstein-Hilbert action containing, in addition to the gravitational vierbein, a massive Abelian vector field coupled to gravity.Comment: 6 pages, 0 figures, to appear in Proceedings of IRGAC 2006: 2nd International Conference on Quantum Theories and Renormalization Group in Gravity and Cosmology, Barcelon

Constrained Dynamics of an Anomalous (g/neq2)(g/neq 2) Relativistic Spinning Particle in Electromagnetic Background

In this paper we have considered the dynamics of an anomalous ($g\neq 2$) charged relativistic spinning particle in the presence of an external electromagnetic field. The constraint analysis is done and the complete set of Dirac brackets are provided that generate the canonical Lorentz algebra and dynamics through Hamiltonian equations of motion. The spin-induced effective curvature of spacetime and its possible connection with Analogue Gravity models are commented upon.Comment: 10 pages Latex, minor corrections and changes in ref., slightly enlarged version, to appear in EPJ

Nonrelativistic Chern-Simons Vortices on the Torus

A classification of all periodic self-dual static vortex solutions of the Jackiw-Pi model is given. Physically acceptable solutions of the Liouville equation are related to a class of functions which we term Omega-quasi-elliptic. This class includes, in particular, the elliptic functions and also contains a function previously investigated by Olesen. Some examples of solutions are studied numerically and we point out a peculiar phenomenon of lost vortex charge in the limit where the period lengths tend to infinity, that is, in the planar limit.Comment: 25 pages, 2+3 figures; improved exposition, corrected typos, added one referenc