6 research outputs found
New Torsional Deformations of Locally AdS Space
We consider general torsion components in three-dimensional Einstein-Cartan
gravity, providing a geometrical interpretation for matter, and find new
solutions of the corresponding equations for the Riemann curvature and torsion.
These geometries involve a peculiar interplay between the vector
and the singlet irreducible components of the torsion which, under
general conditions, feature a formal analogy with the equation for a Beltrami
fluid. Interestingly, we find that the local AdS geometry is now deformed
by effect of the "Beltrami-torsion" . Some of these new solutions
describe deformations of the BTZ black hole due to the presence of torsion. The
latter acts as a geometric flux which, in some cases, removes the causal
singularity.Comment: 24 pages, 5 figure
The Seiberg-Witten Map for a Time-dependent Background
In this paper the Seiberg-Witten map for a time-dependent background related
to a null-brane orbifold is studied. The commutation relations of the
coordinates are linear, i.e. it is an example of the Lie algebra type. The
equivalence map between the Kontsevich star product for this background and the
Weyl-Moyal star product for a background with constant noncommutativity
parameter is also studied.Comment: latex, 13 pages, references added and some misprints correcte
The Role of PSL(2, 7) in M‐theory: M2‐Branes, Englert Equation and the Septuples
3noReconsidering the M2-brane solutions of (Formula presented.) supergravity with a transverse Englert flux introduced by one of us in 2016, we present a new purely group theoretical algorithm to solve Englert equation based on a specific embedding of the PSL(2, 7) group into (Formula presented.). The aforementioned embedding is singled out by the identification of PSL(2, 7) with the automorphism group of the Fano plane. Relying on the revealed intrinsic PSL(2, 7) symmetry of Englert equation and on the new algorithm we present an exhaustive classification of Englert fluxes. The residual supersymmetries of the corresponding M2-brane solutions associated with the first of the 8 classes into which we have partitioned Englert fluxes are exhaustively analyzed and we show that all residual (Formula presented.) supersymmetries with (Formula presented.) are available. Our constructions correspond to a particular case in the category of M2-brane solutions with transverse self-dual fluxes.partially_openopenCerchiai B.L.; Fre P.; Trigiante M.Cerchiai, B. L.; Fre, P.; Trigiante, M
ADAMS-IWASAWA BLACK HOLES
We study some of the properties of the geometry of the exceptional Lie group
E7(7), which describes the U-duality of the N=8, d=4 supergravity. In
particular, based on a symplectic construction of the Lie algebra e7(7) due to
Adams, we compute the Iwasawa decomposition of the symmetric space
M=E7(7)/(SU(8)/Z_2), which gives the vector multiplets' scalar manifold of the
corresponding supergravity theory.
The explicit expression of the Lie algebra is then used to analyze the origin
of M as scalar configuration of the "large" 1/8-BPS extremal black hole
attractors. In this framework it turns out that the U(1) symmetry spanning such
attractors is broken down to a discrete subgroup Z_4, spoiling their dyonic
nature near the origin of the scalar manifold.
This is a consequence of the fact that the maximal manifest off-shell
symmetry of the Iwasawa parametrization is determined by a completely
non-compact Cartan subalgebra of the maximal subgroup SL(8,R) of E7(7), which
breaks down the maximal possible covariance SL(8,R) to a smaller SL(7,R)
subgroup. These results are compared with the ones obtained in other known
bases, such as the Sezgin-van Nieuwenhuizen and the Cremmer-Julia /de
Wit-Nicolai frames.Comment: 11 pages, 1 figure, 1 table, Contribution to the Proceedings of the
'JW2011 Workshop on the Scientific and Human Legacy of Julius Wess', held
August 27 - 28, 2011 in Donji Milanovac, Serbi
Squaring the Magic
21 pages, 1 figure, 20 tables; reference adde