9,226 research outputs found
New supersymmetric higher-derivative couplings: Full N=2 superspace does not count!
An extended class of N=2 locally supersymmetric invariants with
higher-derivative couplings based on full superspace integrals, is constructed.
These invariants may depend on unrestricted chiral supermultiplets, on vector
supermultiplets and on the Weyl supermultiplet. Supersymmetry is realized
off-shell. A non-renormalization theorem is proven according to which none of
these invariants can contribute to the entropy and electric charges of BPS
black holes. Some of these invariants may be relevant for topological string
deformations.Comment: 24 pages, v2: version published in JHEP, one reference added and
typos corrected, v3: reference adde
Covariant Quantization of D-branes
We have found that kappa-symmetry allows a covariant quantization provided
the ground state of the theory is strictly massive. For D-p-branes a
Hamiltonian analysis is performed to explain the existence of a manifestly
supersymmetric and Lorentz covariant description of the BPS states of the
theory. The covariant quantization of the D-0-brane is presented as an example.Comment: 16 pages, no figure
STU Black Holes and String Triality
We find double-extreme black holes associated with the special geometry of
the Calabi-Yau moduli space with the prepotential F=STU. The area formula is
STU-moduli independent and has symmetry in space of charges.
The dual version of this theory without prepotential treats the dilaton S
asymmetric versus T,U-moduli. We display the dual relation between new (STU)
black holes and stringy (S|TU) black holes using particular Sp(8, Z)
transformation. The area formula of one theory equals that of the dual theory
when expressed in terms of dual charges. We analyse the relation between (STU)
black holes to string triality of black holes: (S|TU), (T|US), (U|ST)
solutions. In the democratic STU-symmetric version we find that all three S and
T and U duality symmetries are non-perturbative and mix electric and magnetic
charges.Comment: 12 pages, 2 Postscript figures, ref.added, minor corrections, version
to appear in Phys. Rev.
Supersymmetric N=2 Einstein-Yang-Mills monopoles and covariant attractors
We present two generic classes of supersymmetric solutions of N=2, d=4
supergravity coupled to non-Abelian vector supermultiplets with a gauge group
that includes an SU(2) factor. The first class consists of embeddings of the 't
Hooft-Polyakov monopole and in the examples considered it has a fully regular,
asymptotically flat space-time metric without event horizons. The other class
of solutions consists of regular non-Abelian extreme black holes. There is a
covariant attractor at the horizon of these non-Abelian black holes.Comment: 14 pages, Late
Stable de Sitter Vacua in 4 Dimensional Supergravity Originating from 5 Dimensions
The five dimensional stable de Sitter ground states in N=2 supergravity
obtained by gauging SO(1,1) symmetry of the real symmetric scalar manifold (in
particular a generic Jordan family manifold of the vector multiplets)
simultaneously with a subgroup R_s of the R-symmetry group descend to four
dimensional de Sitter ground states under certain conditions. First, the
holomorphic section in four dimensions has to be chosen carefully by using the
symplectic freedom in four dimensions; and second, a group contraction is
necessary to bring the potential into a desired form. Under these conditions,
stable de Sitter vacua can be obtained in dimensionally reduced theories (from
5D to 4D) if the semi-direct product of SO(1,1) with R^(1,1) together with a
simultaneous R_s is gauged. We review the stable de Sitter vacua in four
dimensions found in earlier literature for N=2 Yang-Mills Einstein supergravity
with SO(2,1) x R_s gauge group in a symplectic basis that comes naturally after
dimensional reduction. Although this particular gauge group does not descend
directly from five dimensions, we show that, its contraction does. Hence, two
different theories overlap in certain limits. Examples of stable de Sitter
vacua are given for the cases: (i) R_s=U(1)_R, (ii) R_s=SU(2)_R, (iii) N=2
Yang-Mills/Einstein Supergravity theory coupled to a universal hypermultiplet.
We conclude with a discussion regarding the extension of our results to
supergravity theories with more general homogeneous scalar manifolds.Comment: 54 page
Hyperbolic Kac Moody Algebras and Einstein Billiards
We identify the hyperbolic Kac Moody algebras for which there exists a
Lagrangian of gravity, dilatons and -forms which produces a billiard that
can be identified with their fundamental Weyl chamber. Because of the
invariance of the billiard upon toroidal dimensional reduction, the list of
admissible algebras is determined by the existence of a Lagrangian in three
space-time dimensions, where a systematic analysis can be carried out since
only zero-forms are involved. We provide all highest dimensional parent
Lagrangians with their full spectrum of -forms and dilaton couplings. We
confirm, in particular, that for the rank 10 hyperbolic algebra, , also known as the dual of , the
maximally oxidized Lagrangian is 9 dimensional and involves besides gravity, 2
dilatons, a 2-form, a 1-form and a 0-form.Comment: 33 page
N=2 Conformal Superspace in Four Dimensions
We develop the geometry of four dimensional N=2 superspace where the entire
conformal algebra of SU(2,2|2) is realized linearly in the structure group
rather than just the SL(2,C) x U(2)_R subgroup of Lorentz and R-symmetries,
extending to N=2 our prior result for N=1 superspace. This formulation
explicitly lifts to superspace the existing methods of the N=2 superconformal
tensor calculus; at the same time the geometry, when degauged to SL(2,C) x
U(2)_R, reproduces the existing formulation of N=2 conformal supergravity
constructed by Howe.Comment: 43 pages; v2 references added, acknowledgments update
The Tensor Hierarchies of Pure N=2,d=4,5,6 Supergravities
We study the supersymmetric tensor hierarchy of pure (gauged) N=2,d=4,5,6
supergravity and compare them with those of the pure, ungauged, theories
(worked out by Gomis and Roest for d=5) and the predictions of the Kac-Moody
approach made by Kleinschmidt and Roest. We find complete agreement in the
ungauged case but we also find that, after gauging, new Stueckelberg symmetries
reduce the number of independent "physical" top-forms. The analysis has to be
performed to all orders in fermion fields.
We discuss the construction of the worldvolume effective actions for the
p-branes which are charged with respect to the (p+1)-form potentials and the
relations between the tensor hierarchies and p-branes upon dimensional
reduction.Comment: LaTeX2e file, 20 pages, 1 figure Results refined by extension of the
analysis to all orders in fermion
On BPS bounds in D=4 N=2 gauged supergravity II: general matter couplings and black hole masses
We continue the analysis of BPS bounds started in arXiv:1110.2688, extending
it to the full class of N=2 gauged supergravity theories with arbitrary vector
and hypermultiplets. We derive the general form of the asymptotic charges for
asymptotically flat (M_4), anti-de Sitter (AdS_4), and magnetic anti-de Sitter
(mAdS_4) spacetimes. Some particular examples from black hole physics are given
to explicitly demonstrate how AdS and mAdS masses differ when solutions with
non-trivial scalar profiles are considered.Comment: 21 pages; v2 added reference, published version; v3 minor correction
An active asteroid belt causing the UX Ori phenomenon in RZ Psc
We report the discovery of mid-infrared excess emission in the young object
RZ Psc. The excess constitutes ~8% of its Lbol, and is well fit by a single
500K black-body implying a dust free region within 0.7AU for optically thick
dust. The object displays dust obscuration events (UXOR behaviour) with a
time-scale that suggests dusty material on orbits of 0.5AU. We also report a
12.4 year cyclical photometric variability which can be interpreted as due to
perturbations in the dust distribution. The system is characterized by a high
inclination, marginal extinction (during bright photometric states), a single
temperature for the warm dust, and an age estimate which puts the star beyond
the formation stage. We propose that the dust occultation events present a
dynamical view of an active asteroid belt whose collisional products
sporadically obscure the central star.Comment: Accepted for A&A letter
- …