2,895 research outputs found
All the timelike supersymmetric solutions of all ungauged d=4 supergravities
We determine the form of all timelike supersymmetric solutions of all N
greater or equal than 2, d=4 ungauged supergravities, for N less or equal than
4 coupled to vector supermultiplets, using the $Usp(n+1,n+1)-symmetric
formulation of Andrianopoli, D'Auria and Ferrara and the spinor-bilinears
method, while preserving the global symmetries of the theories all the way. As
previously conjectured in the literature, the supersymmetric solutions are
always associated to a truncation to an N=2 theory that may include
hypermultiplets, although fields which are eliminated in the truncations can
have non-trivial values, as is required by the preservation of the global
symmetry of the theories. The solutions are determined by a number of
independent functions, harmonic in transverse space, which is twice the number
of vector fields of the theory (n+1). The transverse space is flat if an only
if the would-be hyperscalars of the associated N=2 truncation are trivial.Comment: v3: Some changes in the introduction. Version to be published in JHE
Quarkonium Spectroscopy at Babar
The Babar experiment at the high luminosity storage ring PEP-II offers excellent opportunities in quarkonium spectroscopy. Recent Babar results obtained in this field are reported
On the influence of the cosmological constant on gravitational lensing in small systems
The cosmological constant Lambda affects gravitational lensing phenomena. The
contribution of Lambda to the observable angular positions of multiple images
and to their amplification and time delay is here computed through a study in
the weak deflection limit of the equations of motion in the Schwarzschild-de
Sitter metric. Due to Lambda the unresolved images are slightly demagnified,
the radius of the Einstein ring decreases and the time delay increases. The
effect is however negligible for near lenses. In the case of null cosmological
constant, we provide some updated results on lensing by a Schwarzschild black
hole.Comment: 8 pages, 1 figure; v2: extended discussion on the lens equation,
references added, results unchanged, in press on PR
Chaotic inflation in Jordan frame supergravity
We consider the inflationary scenario with non-minimal coupling in 4D Jordan
frame supergravity. We find that there occurs a tachyonic instability along the
direction of the accompanying non-inflaton field in generic Jordan frame
supergravity models. We propose a higher order correction to the Jordan frame
function for solving the tachyonic mass problem and show that the necessary
correction can be naturally generated by the heavy thresholds without spoiling
the slow-roll conditions. We discuss the implication of the result on the Higgs
inflation in NMSSM.Comment: 16 pages, no figures, version to be published in JCA
Colliding Axion-Dilaton Plane Waves from Black Holes
The colliding plane wave metric discovered by Ferrari and Iba\~{n}ez to be
locally isometric to the interior of a Schwarzschild black hole is extended to
the case of general axion-dilaton black holes. Because the transformation maps
either black hole horizon to the focal plane of the colliding waves, this
entire class of colliding plane wave spacetimes only suffers from the formation
of spacetime singularities in the limits where the inner horizon itself is
singular, which occur in the Schwarzschild and dilaton black hole limits. The
supersymmetric limit corresponding to the extreme axion-dilaton black hole
yields the Bertotti-Robinson metric with the axion and dilaton fields flowing
to fixed constant values. The maximal analytic extension of this metric across
the Cauchy horizon yields a spacetime in which two sandwich waves in a
cylindrical universe collide to produce a semi-infinite chain of
Reissner-Nordstrom-like wormholes. The focussing of particle and string
geodesics in this spacetime is explored.Comment: 19 pages, 6 figure
Instantons in the Double-Tensor Multiplet
The double-tensor multiplet naturally appears in type IIB superstring
compactifications on Calabi-Yau threefolds, and is dual to the universal
hypermultiplet. We revisit the calculation of instanton corrections to the
low-energy effective action, in the supergravity approximation. We derive a
Bogomolny'i bound for the double-tensor multiplet and find new instanton
solutions saturating the bound. They are characterized by the topological
charges and the asymptotic values of the scalar fields in the double-tensor
multiplet.Comment: 17 pages, LaTeX2e with amsmath.sty; v2: minor change
N=2 Supersymmetric Scalar-Tensor Couplings
We determine the general coupling of a system of scalars and antisymmetric
tensors, with at most two derivatives and undeformed gauge transformations, for
both rigid and local N=2 supersymmetry in four-dimensional spacetime. Our
results cover interactions of hyper, tensor and double-tensor multiplets and
apply among others to Calabi-Yau threefold compactifications of Type II
supergravities. As an example, we give the complete Lagrangian and
supersymmetry transformation rules of the double-tensor multiplet dual to the
universal hypermultiplet.Comment: 23 pages, LaTeX2e with amsmath.sty; v2: corrected typos and added
referenc
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