546 research outputs found
The Riemann-Lovelock Curvature Tensor
In order to study the properties of Lovelock gravity theories in low
dimensions, we define the kth-order Riemann-Lovelock tensor as a certain
quantity having a total 4k-indices, which is kth-order in the Riemann curvature
tensor and shares its basic algebraic and differential properties. We show that
the kth-order Riemann-Lovelock tensor is determined by its traces in dimensions
2k \le D <4k. In D=2k+1 this identity implies that all solutions of pure
kth-order Lovelock gravity are `Riemann-Lovelock' flat. It is verified that the
static, spherically symmetric solutions of these theories, which are missing
solid angle space times, indeed satisfy this flatness property. This
generalizes results from Einstein gravity in D=3, which corresponds to the k=1
case. We speculate about some possible further consequences of Riemann-Lovelock
curvature.Comment: 12 page
Radiation reaction in 2+1 electrodynamics
A self-action problem for a pointlike charged particle arbitrarily moving in
flat spacetime of three dimensions is considered. Outgoing waves carry
energy-momentum and angular momentum; the radiation removes energy and angular
momentum from the source which then undergoes a radiation reaction. We
decompose Noether quantities carried by electromagnetic field into bound and
radiative components. The bound terms are absorbed by individual particle's
characteristics within the renormalization procedure. Radiative terms together
with already renormalized 3-momentum and angular momentum of pointlike charge
constitute the total conserved quantities of our particle plus field system.
Their differential consequences yield the effective equation of motion of
radiating charge in an external electromagnetic field. In this
integrodifferential equation the radiation reaction is determined by Lorentz
force of pointlike charge acting upon itself plus nonlocal term which provides
finiteness of the self-action.Comment: 46 pages, 6 figure
Surface holonomy and gauge 2-group
Just as point objects are parallel transported along curves, giving
holonomies, string-like objects are parallel transported along surfaces, giving
surface holonomies. Composition of these surfaces correspond to products in a
category theoretic generalization of the gauge group, called a 2-group. I
consider two different ways of constructing surface holonomies, one by using a
pair of one and two form connections, and another by using a pair of one-form
connections. Both procedures result in the structure of a 2-group.Comment: 8pp, RevTeX4, Submitted upon invitation to IJGMM
Decay of the Cosmological Constant. Equivalence of Quantum Tunneling and Thermal Activation in Two Spacetime Dimensions
We study the decay of the cosmological constant in two spacetime dimensions
through production of pairs. We show that the same nucleation process looks as
quantum mechanical tunneling (instanton) to one Killing observer and as thermal
activation (thermalon) to another. Thus, we find another striking example of
the deep interplay between gravity, thermodynamics and quantum mechanics which
becomes apparent in presence of horizons.Comment: 11 pages, 6 figure
Electric-Magnetic Black Hole Duality
We generalize duality invariance for the free Maxwell action in an arbitrary
background geometry to include the presence of electric and magnetic charges.
In particular, it follows that the actions of equally charged electric and
magnetic black holes are equal
p-Brane Dyons and Electric-magnetic Duality
We discuss dyons, charge quantization and electric-magnetic duality for
self-interacting, abelian, p-form theories in the spacetime dimensions D=2(p+1)
where dyons can be present. The corresponding quantization conditions and
duality properties are strikingly different depending on whether p is odd or
even. If p is odd one has the familiar eg'-ge'= 2nh, whereas for even p one
finds the opposite relative sign, eg'+ge'= 2nh. These conditions are obtained
by introducing Dirac strings and taking due account of the multiple
connectedness of the configuration space of the strings and the dyons. A
two-potential formulation of the theory that treats the electric and magnetic
sources on the same footing is also given.
Our results hold for arbitrary gauge invariant self-interaction of the fields
and are valid irrespective of their duality properties.Comment: 33 pages, 1 figur
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