SL(2,R)-invariant IIB Brane Actions

We give a universal SL(2,R)-invariant expression for all IIB p-brane actions with p=-1,1,3,5,7,9. The Wess-Zumino terms in the brane actions are determined by requiring (i) target space gauge invariance and (ii) the presence of a single Born-Infeld vector. We find that for p=7 (p=9) brane actions with these properties only exist for orbits that contain the standard D7-brane (D9-brane). We comment about the actions for the other orbits.Comment: 15 pages, additional references and remarks in subsection on 3-branes, accepted for publication in JHE

Kappa-symmetric SL(2,R) covariant D-brane actions

A superspace formulation of IIB supergravity which includes the field strengths of the duals of the usual physical one, three and five-form field strengths as well as the eleven-form field strength is given. The superembedding formalism is used to construct kappa-symmetric SL(2,R) covariant D-brane actions in an arbitrary supergravity background.Comment: 20 pages. Minor clarification in text. References adde

Q-instantons

We construct the half-supersymmetric instanton solutions that are electric-magnetically dual to the recently discussed half-supersymmetric Q7-branes. We call these instantons `Q-instantons'. Whereas the D-instanton is most conveniently described using the RR axion \chi and the dilaton \phi, the Q-instanton is most conveniently described using a different set of fields \chi' and T, where \chi' is an axionic scalar. The real part of the Q-instanton on-shell action is a function of T and the imaginary part is linear in \chi'. Discrete shifts of the axion \chi' correspond to PSL(2,Z) transformations that are of finite order. These are e.g. pure S-duality transformations relating weak and strongly coupled regimes. We argue that near each orbifold point of the quantum axion-dilaton moduli space PSL(2,Z)\PSL(2,R)/SO(2) the higher order R^4 terms in the string effective action contain contributions from an infinite sum of single multiply-charged instantons with the Q-instantons corresponding to the orbifold points \tau=i,\rho where \tau is the complex axion-dilaton field.Comment: 29 pages, 1 figur

Q7-branes and their coupling to IIB supergravity

We show how, by making use of a new basis of the IIB supergravity axion-dilaton coset, SL(2,R)/SO(2), 7-branes that belong to different conjugacy classes of the duality group SL(2,R) naturally couple to IIB supergravity with appropriate source terms characterized by an SL(2,R) charge matrix Q. The conjugacy classes are determined by the value of the determinant of Q. The (p,q) 7-branes are the branes in the conjugacy class detQ = 0. The 7-branes in the conjugacy class detQ > 0 are labelled by three numbers (p,q,r) which parameterize the matrix Q and will be called Q7-branes. We construct the full bosonic Wess--Zumino term for the Q7-branes. In order to realize a gauge invariant coupling of the Q7-brane to the gauge fields of IIB supergravity it is necessary to introduce an SL(2,R) doublet of two distinct Born--Infeld fields on the Q7-brane world-volume.Comment: 31 pages, Latex fil

Non-propagating degrees of freedom in supergravity and very extended G_2

Recently a correspondence between non-propagating degrees of freedom in maximal supergravity and the very extended algebra E_11 has been found. We perform a similar analysis for a supergravity theory with eight supercharges and very extended G_2. In particular, in the context of d=5 minimal supergravity, we study whether supersymmetry can be realised on higher-rank tensors with no propagating degrees of freedom. We find that in this case the very extended algebra fails to capture these possibilities.Comment: 12 pages, 1 figure. v2: transformation properties of higher-rank tensors under SU(2) R-symmetry analysed and refs added. v3: improved discussion, published versio

Seven-branes and Supersymmetry

We re-investigate the construction of half-supersymmetric 7-brane solutions of IIB supergravity. Our method is based on the requirement of having globally well-defined Killing spinors and the inclusion of SL(2,Z)-invariant source terms. In addition to the well-known solutions going back to Greene, Shapere, Vafa and Yau we find new supersymmetric configurations, containing objects whose monodromies are not related to the monodromy of a D7-brane by an SL(2,Z) transformation.Comment: 31 pages, 3 figure

Stringy cosmic strings in matter coupled N=2, d=4 supergravity

We extend the system of ungauged N=2, d=4 supergravity coupled to vector multiplets and hypermultiplets with 2-form potentials. The maximal number of 2-form potentials that one may introduce is equal to the number of isometries of either the special Kaehler or quaternionic Kaehler sigma model. We show that the local supersymmetry algebra can be realized on the 2-form potentials. These 2-forms couple electrically to strings which we refer to as stringy cosmic strings. The 1/2 BPS bosonic world-sheet actions for these strings are constructed and we discuss the properties of the 1/2 BPS stringy cosmic string solutions.Comment: 36 pages, added references, corrected typos, modificated Appendix

IIA Ten-forms and the Gauge Algebras of Maximal Supergravity Theories

We show that IIA supergravity can be extended with two independent 10-form potentials. These give rise to a single BPS IIA 9-brane. We investigate the bosonic gauge algebra of both IIA and IIB supergravity in the presence of 10-form potentials and point out an intriguing relation with the symmetry algebra $E_{11}$, which has been conjectured to be the underlying symmetry of string theory/M-theory.Comment: 18 pages, section on IIA 9-branes added, references added; version to be publishe

The supersymmetric tensor hierarchy of N=1,d=4 supergravity

In this paper we construct the supersymmetric tensor hierarchy of N=1, d=4 supergravity. We find some differences with the general bosonic construction of 4-dimensional gauged supergravities. The global symmetry group of N=1,d=4 supergravity consists of three factors: the scalar manifold isometry group, the invariance group of the complex vector kinetic matrix and the U(1) R-symmetry group. In contrast to (half)-maximal supergravities, the latter two symmetries are not embedded into the isometry group of the scalar manifold. We identify some components of the embedding tensor with Fayet-Iliopoulos terms and we find that supersymmetry implies that the inclusion of R-symmetry as a factor of the global symmetry group requires a non-trivial extension of the standard p-form hierarchy. This extension involves additional 3- and 4-forms. One additional 3-form is dual to the superpotential (seen as a deformation of the simplest theory). We study the closure of the supersymmetry algebra on all the bosonic p-form fields of the hierarchy up to duality relations. In order to close the supersymmetry algebra without the use of duality relations one must construct the hierarchy in terms of supermultiplets. Such a construction requires fermionic duality relations among the hierarchy's fermions and these turn out to be local.Comment: Latex2e, 42 pages, no figures Improved version to be published in JEH

The E_{11} origin of all maximal supergravities

Starting from the eleven dimensional E_{11} non-linear realisation of M-theory we compute all possible forms, that is objects with totally antisymmetrised indices, that occur in four dimensions and above as well as all the 1-forms and 2-forms in three dimensions. In any dimension D, the D-1-forms lead to maximal supergravity theories with cosmological constants and they are in precise agreement with the patterns of gauging found in any dimension using supersymmetry. The D-forms correspond to the presence of space-filling branes which are crucial for the consistency of orientifold models and have not been derived from an alternative approach, with the exception of the 10-dimensional case. It follows that the gaugings of supergravities and the spacetime-filling branes possess an eleven dimensional origin within the E_{11} formulation of M-theory. This and previous results very strongly suggest that all the fields in the adjoint representation of E_{11} have a physical interpretation.Comment: 54 page