12,509 research outputs found
A Local Description of Dark Energy in Terms of Classical Two-Component Massive Spin-One Uncharged Fields on Spacetimes with Torsionful Affinities
It is assumed that the two-component spinor formalisms for curved spacetimes
that are endowed with torsionful affine connexions can supply a local
description of dark energy in terms of classical massive spin-one uncharged
fields. The relevant wave functions are related to torsional affine potentials
which bear invariance under the action of the generalized Weyl gauge group.
Such potentials are thus taken to carry an observable character and emerge from
contracted spin affinities whose patterns are chosen in a suitable way. New
covariant calculational techniques are then developed towards deriving
explicitly the wave equations that supposedly control the propagation in
spacetime of the dark energy background. What immediately comes out of this
derivation is a presumably natural display of interactions between the fields
and both spin torsion and curvatures. The physical properties that may arise
directly from the solutions to the wave equations are not brought out.Comment: About 10 pages, 47 reference
New gravitational solutions via a Riemann-Hilbert approach
We consider the Riemann-Hilbert factorization approach to solving the field
equations of dimensionally reduced gravity theories. First we prove that
functions belonging to a certain class possess a canonical factorization due to
properties of the underlying spectral curve. Then we use this result, together
with appropriate matricial decompositions, to study the canonical factorization
of non-meromorphic monodromy matrices that describe deformations of seed
monodromy matrices associated with known solutions. This results in new
solutions, with unusual features, to the field equations.Comment: 29 pages, 2 figures; v2: reference added, matches published versio
Wave Equations for Classical Two-Component Proca Fields in Curved Spacetimes with Torsionless Affinities
The world formulation of the full theory of classical Proca fields in
generally relativistic spacetimes is concisely reviewed and the entire set of
pertinent field equations is transcribed in a straightforward way into the
framework of one of the Infeld-van der Waerden formalisms. Some well-known
calculational techniques are then utilized for deriving the wave equations that
control the propagation of the fields allowed for. It appears that no
interaction couplings between such fields and electromagnetic curvatures are
carried by the wave equations at issue. What results is, in effect, that the
only interactions which ultimately occur in the theoretical context under
consideration involve strictly Proca fields and wave functions for gravitons.Comment: Many improvements on the paper have still been made. In particular,
its title has been modified so as to conform further to one of its main aim
On Quantum Special Kaehler Geometry
We compute the effective black hole potential V of the most general N=2, d=4
(local) special Kaehler geometry with quantum perturbative corrections,
consistent with axion-shift Peccei-Quinn symmetry and with cubic leading order
behavior. We determine the charge configurations supporting axion-free
attractors, and explain the differences among various configurations in
relations to the presence of ``flat'' directions of V at its critical points.
Furthermore, we elucidate the role of the sectional curvature at the
non-supersymmetric critical points of V, and compute the Riemann tensor (and
related quantities), as well as the so-called E-tensor. The latter expresses
the non-symmetricity of the considered quantum perturbative special Kaehler
geometry.Comment: 1+43 pages; v2: typo corrected in the curvature of Jordan symmetric
sequence at page 2
Pseudo-Supersymmetry and the Domain-Wall/Cosmology Correspondence
The correspondence between domain-wall and cosmological solutions of gravity
coupled to scalar fields is explained. Any domain wall solution that admits a
Killing spinor is shown to correspond to a cosmology that admits a
pseudo-Killing spinor: whereas the Killing spinor obeys a Dirac-type equation
with hermitian `mass'-matrix, the corresponding pseudo-Killing spinor obeys a
Dirac-type equation with a anti-hermitian `mass'-matrix. We comment on some
implications of (pseudo)supersymmetry.Comment: 11 pages, contribution to the proceedings of IRGAC 2006;v3: minor
change
Partition functions and elliptic genera from supergravity
We develop the spacetime aspects of the computation of partition functions
for string/M-theory on AdS(3) xM. Subleading corrections to the semi-classical
result are included systematically, laying the groundwork for comparison with
CFT partition functions via the AdS(3)/CFT(2) correspondence. This leads to a
better understanding of the "Farey tail" expansion of Dijkgraaf et. al. from
the point of view of bulk physics. Besides clarifying various issues, we also
extend the analysis to the N=2 setting with higher derivative effects included.Comment: 34 page
- …