83 research outputs found
On the Opening of Branes
We relate, in 10 and 11 dimensional supergravities, configurations of
intersecting closed branes with vanishing binding energy to configurations
where one of the branes opens and has its boundaries attached to the other.
These boundaries are charged with respect to fields living on the closed brane.
The latter hosts electric and magnetic charges stemming from dual pairs of open
branes terminating on it. We show that charge conservation, gauge invariance
and supersymmetry entirely determine these charges and these fields, which can
be seen as Goldstone fields of broken supersymmetry. Open brane boundary
charges can annihilate, restoring the zero binding energy configuration. This
suggests emission of closed branes by branes, a generalization of closed string
emission by D-branes. We comment on the relation of the Goldstone fields to
matrix models approaches to M-theory.Comment: 13 pages, LaTeX, no figure
New record of <i>Typhinellus labiatus</i> (Cristofori & Jan, 1832) (Gastropoda: Muricidae) from São Tomé and Principe and discussion about its classification and geographical distribution
Supersymmetry and Gravitational Duality
We study how the supersymmetry algebra copes with gravitational duality. As a
playground, we consider a charged Taub-NUT solution of D=4, N=2 supergravity.
We find explicitly its Killing spinors, and the projection they obey provides
evidence that the dual magnetic momenta necessarily have to appear in the
supersymmetry algebra. The existence of such a modification is further
supported using an approach based on the Nester form. In the process, we find
new expressions for the dual magnetic momenta, including the NUT charge. The
same expressions are then rederived using gravitational duality.Comment: 23 pages, no figures; v2: sign typos fixed in Section 6; v3: version
to appear in PRD. Improved discussion in section 5 (on the surface NUT
charges) and in section 6 (on the superalgebra
Hidden Symmetries and Dirac Fermions
In this paper, two things are done. First, we analyze the compatibility of
Dirac fermions with the hidden duality symmetries which appear in the toroidal
compactification of gravitational theories down to three spacetime dimensions.
We show that the Pauli couplings to the p-forms can be adjusted, for all simple
(split) groups, so that the fermions transform in a representation of the
maximal compact subgroup of the duality group G in three dimensions. Second, we
investigate how the Dirac fermions fit in the conjectured hidden overextended
symmetry G++. We show compatibility with this symmetry up to the same level as
in the pure bosonic case. We also investigate the BKL behaviour of the
Einstein-Dirac-p-form systems and provide a group theoretical interpretation of
the Belinskii-Khalatnikov result that the Dirac field removes chaos.Comment: 30 page
G+++ Invariant Formulation of Gravity and M-Theories: Exact BPS Solutions
We present a tentative formulation of theories of gravity with suitable
matter content, including in particular pure gravity in D dimensions, the
bosonic effective actions of M-theory and of the bosonic string, in terms of
actions invariant under very-extended Kac-Moody algebras G+++. We conjecture
that they host additional degrees of freedom not contained in the conventional
theories. The actions are constructed in a recursive way from a level expansion
for all very-extended algebras G+++. They constitute non-linear realisations on
cosets, a priori unrelated to space-time, obtained from a modified Chevalley
involution. Exact solutions are found for all G+++. They describe the algebraic
properties of BPS extremal branes, Kaluza-Klein waves and Kaluza-Klein
monopoles. They illustrate the generalisation to all G+++ invariant theories of
the well-known duality properties of string theories by expressing duality as
Weyl invariance in G+++. Space-time is expected to be generated dynamically. In
the level decomposition of E8+++ = E11, one may indeed select an A10
representation of generators Pa which appears to engender space-time
translations by inducing infinite towers of fields interpretable as field
derivatives in space and time.Comment: Latex 45 pages, 1 figure. Discussion on pages 19 and 20 altered.
Appendix B amplified. 4 footnotes added. 2 references added. Acknowledgments
updated. Additional minor correction
An M-theory solution from null roots in E11
We find a purely gravitational classical solution of
M-theory/eleven-dimensional supergravity which corresponds to a solution of the
E10 brane sigma-model involving a null root. This solution is not
supersymmetric and is regularly embedded into E11.Comment: 10 page
Counting supersymmetric branes
Maximal supergravity solutions are revisited and classified, with particular
emphasis on objects of co-dimension at most two. This class of solutions
includes branes whose tension scales with g_s^{-\sigma} for \sigma>2. We
present a group theory derivation of the counting of these objects based on the
corresponding tensor hierarchies derived from E11 and discrete T- and U-duality
transformations. This provides a rationale for the wrapping rules that were
recently discussed for \sigma<4 in the literature and extends them. Explicit
supergravity solutions that give rise to co-dimension two branes are
constructed and analysed.Comment: 1+33 pages. To the memory of Laurent Houart. v2: Published version
with added reference
An E9 multiplet of BPS states
We construct an infinite E9 multiplet of BPS states for 11D supergravity. For
each positive real root of E9 we obtain a BPS solution of 11D supergravity, or
of its exotic counterparts, depending on two non-compact transverse space
variables. All these solutions are related by U-dualities realised via E9 Weyl
transformations in the regular embedding of E9 in E10, E10 in E11. In this way
we recover the basic BPS solutions, namely the KK-wave, the M2 brane, the M5
brane and the KK6-monopole, as well as other solutions admitting eight
longitudinal space dimensions. A novel technique of combining Weyl reflexions
with compensating transformations allows the construction of many new BPS
solutions, each of which can be mapped to a solution of a dual effective action
of gravity coupled to a certain higher rank tensor field. For real roots of E10
which are not roots of E9, we obtain additional BPS solutions transcending 11D
supergravity (as exemplified by the lowest level solution corresponding to the
M9 brane). The relation between the dual formulation and the one in terms of
the original 11D supergravity fields has significance beyond the realm of BPS
solutions. We establish the link with the Geroch group of general relativity,
and explain how the E9 duality transformations generalize the standard Hodge
dualities to an infinite set of `non-closing dualities'.Comment: 76 pages, 6 figure
A Remark on the Renormalization Group Equation for the Penner Model
It is possible to extract values for critical couplings and gamma_string in
matrix models by deriving a renormalization group equation for the variation of
the of the free energy as the size N of the matrices in the theory is varied.
In this paper we derive a ``renormalization group equation'' for the Penner
model by direct differentiation of the partition function and show that it
reproduces the correct values of the critical coupling and gamma_string and is
consistent with the logarithmic corrections present for g=0,1.Comment: LaTeX, 5 pages, LPTHE-Orsay-94-5
G2 Dualities in D=5 Supergravity and Black Strings
Five dimensional minimal supergravity dimensionally reduced on two commuting
Killing directions gives rise to a G2 coset model. The symmetry group of the
coset model can be used to generate new solutions by applying group
transformations on a seed solution. We show that on a general solution the
generators belonging to the Cartan and nilpotent subalgebras of G2 act as
scaling and gauge transformations, respectively. The remaining generators of G2
form a sl(2,R)+sl(2,R) subalgebra that can be used to generate non-trivial
charges. We use these generators to generalize the five dimensional Kerr string
in a number of ways. In particular, we construct the spinning electric and
spinning magnetic black strings of five dimensional minimal supergravity. We
analyze physical properties of these black strings and study their
thermodynamics. We also explore their relation to black rings.Comment: typos corrected (26 pages + appendices, 2 figures
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