8,885 research outputs found
Deformations of special geometry: in search of the topological string
The topological string captures certain superstring amplitudes which are also
encoded in the underlying string effective action. However, unlike the
topological string free energy, the effective action that comprises
higher-order derivative couplings is not defined in terms of duality covariant
variables. This puzzle is resolved in the context of real special geometry by
introducing the so-called Hesse potential, which is defined in terms of duality
covariant variables and is related by a Legendre transformation to the function
that encodes the effective action. It is demonstrated that the Hesse potential
contains a unique subsector that possesses all the characteristic properties of
a topological string free energy. Genus contributions are constructed
explicitly for a general class of effective actions associated with a
special-K\"ahler target space and are shown to satisfy the holomorphic anomaly
equation of perturbative type-II topological string theory. This identification
of a topological string free energy from an effective action is primarily based
on conceptual arguments and does not involve any of its more specific
properties. It is fully consistent with known results. A general theorem is
presented that captures some characteristic features of the equivalence, which
demonstrates at the same time that non-holomorphic deformations of special
geometry can be dealt with consistently.Comment: 44 pages, LaTex; v2, v3: minor text improvement
Comments on the global constraints in light-cone string and membrane theories
In the light-cone closed string and toroidal membrane theories, we associate
the global constraints with gauge symmetries. In the closed string case, we
show that the physical states defined by the BRS charge satisfy the
level-matching condition. In the toroidal membrane case, we show that the
Faddeev-Popov ghost and anti-ghost corresponding to the global constraints are
essentially free even if we adopt any gauge fixing condition for the local
constraint. We discuss the quantum double-dimensional reduction of the wrapped
supermembrane with the global constraints.Comment: 12 pages, typos corrected, to appear in JHE
M Theory As A Matrix Model: A Conjecture
We suggest and motivate a precise equivalence between uncompactified eleven
dimensional M-theory and the N = infinity limit of the supersymmetric matrix
quantum mechanics describing D0-branes. The evidence for the conjecture
consists of several correspondences between the two theories. As a consequence
of supersymmetry the simple matrix model is rich enough to describe the
properties of the entire Fock space of massless well separated particles of the
supergravity theory. In one particular kinematic situation the leading large
distance interaction of these particles is exactly described by supergravity .
The model appears to be a nonperturbative realization of the holographic
principle. The membrane states required by M-theory are contained as
excitations of the matrix model. The membrane world volume is a noncommutative
geometry embedded in a noncommutative spacetime.Comment: Typo and tex error corrected. 41 pages, harvma
Electric and magnetic charges in N=2 conformal supergravity theories
General Lagrangians are constructed for N=2 conformal supergravity theories
in four space-time dimensions involving gauge groups with abelian and/or
non-abelian electric and magnetic charges. The charges are encoded in the gauge
group embedding tensor. The scalar potential induced by the gauge interactions
is quadratic in this tensor, and, when the embedding tensor is treated as a
spurionic quantity, it is formally covariant with respect to electric/magnetic
duality. This work establishes a general framework for studying any deformation
induced by gauge interactions of matter-coupled N=2 supergravity theories. As
an application, full and residual supersymmetry realizations in maximally
symmetric space-times are reviewed. Furthermore, a general classification is
presented of supersymmetric solutions in
space-times. As it turns out, these solutions allow either eight or four
supersymmetries. With four supersymmetries, the spinorial parameters are
Killing spinors of that are constant on , so that they
carry no spin, while the bosonic background is rotationally invariant.Comment: 49 pages, typos correcte
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
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.
N=2 Supergravity Lagrangian Coupled to Tensor Multiplets with Electric and Magnetic Fluxes
We derive the full N=2 supergravity Lagrangian which contains a symplectic
invariant scalar potential in terms of electric and magnetic charges. As shown
in reference [1], the appearance of magnetic charges is allowed only if tensor
multiplets are present and a suitable Fayet-Iliopoulos term is included in the
fermion transformation laws. We generalize the procedure in the quoted
reference by adding further a Fayet-Iliopoulos term which allows the
introduction of electric charges in such a way that the potential and the
equations of motion of the theory are symplectic invariant. The theory is
further generalized to include an ordinary electric gauging and the form of the
resulting scalar potential is given.Comment: 1+34 pages LaTeX, correction of a typo in the ungauged scalar
potentia
The Hypermultiplet with Heisenberg Isometry in N=2 Global and Local Supersymmetry
The string coupling of N=2 supersymmetric compactifications of type II string
theory on a Calabi-Yau manifold belongs to the so-called universal dilaton
hypermultiplet, that has four real scalars living on a quaternion-Kaehler
manifold. Requiring Heisenberg symmetry, which is a maximal subgroup of
perturbative isometries, reduces the possible manifolds to a one-parameter
family that describes the tree-level effective action deformed by the only
possible perturbative correction arising at one-loop level. A similar argument
can be made at the level of global supersymmetry where the scalar manifold is
hyper-Kaehler. In this work, the connection between global and local
supersymmetry is explicitly constructed, providing a non-trivial gravity
decoupled limit of type II strings already in perturbation theory.Comment: 24 page
Probing discs around massive young stellar objects with CO first overtone emission
We present high resolution (R~50,000) spectroastrometry over the CO 1st
overtone bandhead of a sample of seven intermediate/massive young stellar
objects. These are primarily drawn from the red MSX source (RMS) survey, a
systematic search for young massive stars which has returned a large, well
selected sample of such objects. The mean luminosity of the sample is
approximately 5 times 10^4 L_\odot, indicating the objects typically have a
mass of ~15 solar masses. We fit the observed bandhead profiles with a model of
a circumstellar disc, and find good agreement between the models and
observations for all but one object. We compare the high angular precision
(0.2-0.8 mas) spectroastrometric data to the spatial distribution of the
emitting material in the best-fitting models. No spatial signatures of discs
are detected, which is entirely consistent with the properties of the
best-fitting models. Therefore, the observations suggest that the CO bandhead
emission of massive young stellar objects originates in small-scale disks, in
agreement with previous work. This provides further evidence that massive stars
form via disc accretion, as suggested by recent simulations.Comment: Accepted for publication in MNRA
- âŠ