9,084 research outputs found
Four curious supergravities
We consider four supergravities with 16+16, 32+32, 64+64, 128+128 degrees of
freedom displaying some curious properties: (1) They exhibit minimal
supersymmetry (N=1, 2, 2, 1) but maximal rank (r=7, 6, 4, 0) of the scalar
coset in D=4, 5, 7, 11. (2) They couple naturally to supermembranes and admit
these membranes as solutions. (3) Although the D=4, 5, 7 supergravities follow
from truncating the maximally supersymmetric ones, there nevertheless exist
M-theory compactifications with G2, SU(3), SU(2) holonomy having these
supergravities as their massless sectors. (4) They reduce to N=1, 2, 4, 8
theories all with maximum rank 7 in D=4 which (5) correspond to 0, 1, 3, 7
lines of the Fano plane and hence admit a division algebra (R,C,H,O)
interpretation consistent with the black-hole/qubit correspondence, (6) are
generalized self-mirror and hence (7) have vanishing on-shell trace anomaly.Comment: 16 pages late
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
Flat Symplectic Bundles of N-Extended Supergravities, Central Charges and Black-Hole Entropy
In these lectures we give a geometrical formulation of N-extended
supergravities which generalizes N=2 special geometry of N=2 theories. In all
these theories duality symmetries are related to the notion of "flat symplectic
bundles" and central charges may be defined as "sections" over these bundles.
Attractor points giving rise to "fixed scalars" of the horizon geometry and
Bekenstein-Hawking entropy formula for extremal black-holes are discussed in
some details.Comment: Based on lectures given by S. Ferrara at the 5th Winter School on
Mathematical Physics held at the Asia Pacific Center for Theoretical Physics,
Seul (Korea), February 199
D3-branes dynamics and black holes
Using the D3-brane as the fundamental tool, we adress two aspects of D-branes
physics. The first regards the interaction between two electromagnetic dual
D-branes in 10 dimensions. In particular, we give a meaning to {\it both} even
and odd spin structure contributions, the latter being non vanishing for non
zero relative velocity (and encoding the Lorentz-like contribution). The
second aspect regards the D-brane/black holes correspondence. We show how the 4
dimensional configuration corresponding to a {\it single} D3-brane wrapped on
the orbifold T^6/Z_3 represents a regular Reissner-Nordstrom solution of d=4
N=2 supergravityComment: 8 pages, latex, 1 eps figure. Talk presented by M. Bertolini at the
conference "Quantum aspects of gauge theories, supergravity and unification"
in Corfu`; to appear in the proceeding
Cosmological Conductive/Cooling Fronts as Lyman Alpha Forest Clouds
We propose a simple model for the origin and evolution of \lya clouds based
on cosmological conductive/cooling fronts. In this model the \lya arises in the
interfaces between the IGM and cold clouds that could be tentatively identified
with protogalaxies. Most of the properties of the \lya absorbers are reproduced
with a very restricted number of assumptions. Among these are the correct range
of HI column density, cloud sizes and redshift and HI column density
distributions for the absorbers. Several predictions and implications of the
model are briefly discussed.Comment: 9 pages, plain TeX, 3 figures; ApJ Letters, accepte
Freudenthal Dual Lagrangians
The global U-dualities of extended supergravity have played a central role in
differentiating the distinct classes of extremal black hole solutions. When the
U-duality group satisfies certain algebraic conditions, as is the case for a
broad class of supergravities, the extremal black holes enjoy a further
symmetry known as Freudenthal duality (F-duality), which although distinct from
U-duality preserves the Bekenstein-Hawking entropy. Here it is shown that, by
adopting the doubled Lagrangian formalism, F-duality, defined on the doubled
field strengths, is not only a symmetry of the black hole solutions, but also
of the equations of motion themselves. A further role for F-duality is
introduced in the context of world-sheet actions. The Nambu-Goto world-sheet
action in any (t, s) signature spacetime can be written in terms of the F-dual.
The corresponding field equations and Bianchi identities are then related by
F-duality allowing for an F-dual formulation of Gaillard-Zumino duality on the
world-sheet. An equivalent polynomial "Polyakov- type" action is introduced
using the so-called black hole potential. Such a construction allows for
actions invariant under all groups of type E7, including E7 itself, although in
this case the stringy interpretation is less clear.Comment: 1+16 pages, 1 Table, updated to match published versio
Supersymmetry and Dual String Solitons
We present new classes of string-like soliton solutions in (; ),
(; ) and (; ) heterotic string theory. Connections are made
between the solution-generating subgroup of the -duality group of the
compactification and the number of spacetime supersymmetries broken. Analogous
solutions are also noted in (; ) compactifications, where a
different form of supersymmetry breaking arises.Comment: 13 pages, harvmac, (missing references added
Generalized mirror symmetry and trace anomalies
We consider compactification of M-theory on X7 with betti numbers (b_0, b_1,
b_2, b_3, b_3, b_2, b_1, b_0) and define a generalized mirror symmetry (b_0,
b_1, b_2, b_3) goes to (b_0, b_1, b_2 -rho/2, b_3+rho/2)$ under which rho =
7b_0-5b_1+3b_2 -b_3 changes sign. Generalized self-mirror theories with rho=0
have massless sectors with vanishing trace anomaly (before dualization).
Examples include pure supergravity with N \geq 4 and supergravity plus matter
with N \leq 4.Comment: 19 pages late
E_7 and the tripartite entanglement of seven qubits
In quantum information theory, it is well known that the tripartite
entanglement of three qubits is described by the group [SL(2,C)]^3 and that the
entanglement measure is given by Cayley's hyperdeterminant. This has provided
an analogy with certain N=2 supersymmetric black holes in string theory, whose
entropy is also given by the hyperdeterminant. In this paper, we extend the
analogy to N=8. We propose that a particular tripartite entanglement of seven
qubits, encoded in the Fano plane, is described by the exceptional group E_7(C)
and that the entanglement measure is given by Cartan's quartic E_7 invariant.Comment: Minor improvements. 15 page late
Microscopic Entropy of N=2 Extremal Black Holes
String theory is used to compute the microscopic entropy for several examples
of black holes in compactifications with supersymmetry. Agreement with
the Bekenstein-Hawking entropy and the moduli-independent area formula is
found in all cases.Comment: 9 pages, no figures, uses harvma
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