1,667 research outputs found
Black Hole Attractors in Extended Supergravity
We review some aspects of the attractor mechanism for extremal black holes of
(not necessarily supersymmetric) theories coupling Einstein gravity to scalars
and Maxwell vector fields. Thence, we consider N=2 and N=8, d=4 supergravities,
reporting some recent advances on the moduli spaces associated to BPS and
non-BPS attractor solutions supported by charge orbits with non-compact
stabilizers.Comment: 1+12 pages, 2 figures, Contribution to the Proceedings of PASCOS
2007,13th International Symposium on Particles, Strings and Cosmology,2-7
July 2007, Imperial College, London, UK, to be published online by the
American Institute of Physics; v2: minor improvements, typos fixed, Ref.
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Configurations of Rank-40r Extremal Even Unimodular Lattices (r=1,2,3)
We show that if L is an extremal even unimodular lattice of rank 40r with
r=1,2,3 then L is generated by its vectors of norms 4r and 4r+2. Our result is
an extension of Ozeki's result for the case r=1.Comment: 5 pages. To appear, Journal de Theorie des Nombres de Bordeau
Attractors with Vanishing Central Charge
We consider the Attractor Equations of particular , d=4
supergravity models whose vector multiplets' scalar manifold is endowed with
homogeneous symmetric cubic special K\"{a}hler geometry, namely of the
so-called and models. In this framework, we derive explicit
expressions for the critical moduli corresponding to non-BPS attractors with
vanishing central charge. Such formul\ae hold for a generic
black hole charge configuration, and they are obtained without formulating any
\textit{ad hoc} simplifying assumption. We find that such attractors are
related to the 1/2-BPS ones by complex conjugation of some moduli. By uplifting
to , d=4 supergravity, we give an interpretation of such a
relation as an exchange of two of the four eigenvalues of the
central charge matrix . We also consider non-BPS attractors with
non-vanishing ; for peculiar charge configurations, we derive
solutions violating the Ansatz usually formulated in literature. Finally, by
group-theoretical considerations we relate Cayley's hyperdeterminant (the
invariant of the stu model) to the invariants of the st^{2} and of the
so-called t^{3} model.Comment: 17 pages, LaTeX fil
Non-BPS Attractors in 5d and 6d Extended Supergravity
We connect the attractor equations of a certain class of N=2, d=5
supergravities with their (1,0), d=6 counterparts, by relating the moduli space
of non-BPS d=5 black hole/black string attractors to the moduli space of
extremal dyonic black string d=6 non-BPS attractors. For d = 5 real special
symmetric spaces and for N = 4,6,8 theories, we explicitly compute the flat
directions of the black object potential corresponding to vanishing eigenvalues
of its Hessian matrix. In the case N = 4, we study the relation to the (2,0),
d=6 theory. We finally describe the embedding of the N=2, d=5 magic models in
N=8, d=5 supergravity as well as the interconnection among the corresponding
charge orbits.Comment: 1+27 page
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