6,126 research outputs found
Orbits of Exceptional Groups, Duality and BPS States in String Theory
We give an invariant classification of orbits of the fundamental
representations of exceptional groups and which classify
BPS states in string and M theories toroidally compactified to d=4 and d=5. The
exceptional Jordan algebra and the exceptional Freudenthal triple system and
their cubic and quartic invariants play a major role in this classification.
The cubic and quartic invariants correspond to the black hole entropy in d=5
and d=4, respectively. The classification of BPS states preserving different
numbers of supersymmetries is in close parallel to the classification of the
little groups and the orbits of timelike, lightlike and space-like vectors in
Minkowski space. The orbits of BPS black holes in N=2 Maxwell-Einstein
supergravity theories in d=4 and d=5 with symmetric space geometries are also
classified including the exceptional N=2 theory that has and
as its symmety in the respective dimensions.Comment: New references and two tables added, a new section on the orbits of
N=2 Maxwell-Einstein supergravity theories in d=4 and d=5 included and some
minor changes were made in other sections. 17 pages. Latex fil
One-loop renormalisation of N=1/2 supersymmetric gauge theory with a superpotential
We construct a superpotential for the general N=1/2 supersymmetric gauge
theory coupled to chiral matter in the fundamental and adjoint representations,
and investigate the one-loop renormalisability of the theories.Comment: 67 pages, including 17 figures. Plain TeX. Uses Harvmac and epsf.
Combined and condensed version of hep-th/0607194 and hep-th/0607195 with some
added material including in particular a generalisation of the Lunin-Rey
classification of potentially divergent operator
Duality Symmetries in N=2 Heterotic Superstring
We review the derivation and the basic properties of the perturbative
prepotential in N=2 compactifications of the heterotic superstring. We discuss
the structure of the perturbative monodromy group and the embedding of rigidly
supersymmetric monodromies associated with enhanced gauge groups, at both
perturbative and non-perturbative level.Comment: Based on talks presented at several conferences. 12 pages, LaTe
Spontaneous Breaking of N=2 Global Supersymmetry
We study spontaneous supersymmetry breaking in N=2 globally supersymmetric
theories describing a system of abelian vector multiplets. We find that the
most general form of the action admits, in addition to the usual
Fayet-Iliopoulos term, a magnetic Fayet-Iliopoulos term for the auxiliary
components of dual vector multiplets. In a generic case, N=2 supersymmetry is
broken down spontaneously to N=1. In some cases however, the scalar potential
can drive the theory towards a N=2 supersymmetric ground state where massless
dyons condense in the vacuum.Comment: 12 pages, LaTe
Supersymmetric Sum Rules for Electromagnetic Multipoles
We derive model independent, non-perturbative supersymmetric sum rules for
the magnetic and electric multipole moments of any theory with N=1
supersymmetry. We find that in any irreducible N=1 supermultiplet the diagonal
matrix elements of the l-multipole moments are completely fixed in terms of
their off-diagonal matrix elements and the diagonal (l-1)-multipole moments.Comment: 10 pages, plain Te
External leg amputation in conformal invariant three-point function
Amputation of external legs is carried out explicitly for the conformal
invariant three-point function involving two spinors and one vector field. Our
results are consistent with the general result that amputing an external leg in
a conformal invariant Green function replaces a field by its conformal partner
in the Green function. A new star-triangle relation, involving two spinors and
one vector field, is derived and used for the calculation.Comment: 16 pages; last paragraph added in Sec. 10, presentation improved, to
appear in Eur. Phys. J.
On Symmetries of Extremal Black Holes with One and Two Centers
After a brief introduction to the Attractor Mechanism, we review the
appearance of groups of type E7 as generalized electric-magnetic duality
symmetries in locally supersymmetric theories of gravity, with particular
emphasis on the symplectic structure of fluxes in the background of extremal
black hole solutions, with one or two centers. In the latter case, the role of
an "horizontal" symmetry SL(2,R) is elucidated by presenting a set of
two-centered relations governing the structure of two-centered invariant
polynomials.Comment: 1+13 pages, 2 Tables. Based on Lectures given by SF and AM at the
School "Black Objects in Supergravity" (BOSS 2011), INFN - LNF, Rome, Italy,
May 9-13 201
Matrix Norms, BPS Bounds and Marginal Stability in N=8 Supergravity
We study the conditions of marginal stability for two-center extremal black
holes in N-extended supergravity in four dimensions, with particular emphasis
on the N=8 case. This is achieved by exploiting triangle inequalities satisfied
by matrix norms. Using different norms and relative bounds among them, we
establish the existence of marginal stability and split attractor flows both
for BPS and some non-BPS solutions. Our results are in agreement with previous
analysis based on explicit construction of multi-center solutions.Comment: 1+15 pages; v2: some new formulas added and misprints corrected; v3:
typos fixed, various refinements, Sec. 2.4 rewritten; to appear on JHE
R^4 Couplings in M and Type II Theories
We discuss several implications of R^4 couplings in M theory when
compactified on Calabi-Yau (CY) manifolds. In particular, these couplings can
be predicted by supersymmetry from the mixed gauge-gravitational Chern-Simons
couplings in five dimensions and are related to the one-loop holomorphic
anomaly in four-dimensional N=2 theories. We find a new contribution to the
Einstein term in five dimensions proportional to the Euler number of the
internal CY threefold, which corresponds to a one-loop correction of the
hypermultiplet geometry. This correction is reproduced by a direct computation
in type II string theories. Finally, we discuss a universal non-perturbative
correction to the type IIB hyper-metric.Comment: 21 pages, harvmac, misprints corrected, version to appear in Nuclear
Physics
Duality covariant non-BPS first order systems
We study extremal black hole solutions to four dimensional N=2 supergravity
based on a cubic symmetric scalar manifold. Using the coset construction
available for these models, we define the first order flow equations implied by
the corresponding nilpotency conditions on the three-dimensional scalar momenta
for the composite non-BPS class of multi-centre black holes. As an application,
we directly solve these equations for the single-centre subclass, and write the
general solution in a manifestly duality covariant form. This includes all
single-centre under-rotating non-BPS solutions, as well as their
non-interacting multi-centre generalisations.Comment: 31 pages, v2: Discussion of the quadratic constraint clarified,
references added, typos corrected, published versio
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