arXiv subjects
Publications and source records attributed to E. Sezgin.
We examine the curvature expansion of a the field equations of a four-dimensional higher spin gauge theory extension of anti-de Sitter gravity. The theory contains massless particles of spin 0,2,4,... that arise in the symmetric product of two spin 0 singletons. We cast the curvature expansion into manifestly covariant form and elucidate the structure of the equations and observe a significant simplification.
We couple n copies of N=(2,0) scalar multiplets to a gauged N=(2,0) supergravity in 2+1 dimensions which admits AdS_3 as a vacuum. The scalar fields are charged under the gauged R-symmetry group U(1) and parametrize certain Kahler manifolds with compact or non-compact isometries. The radii of these manifolds are quantized in the compact case, but arbitrary otherwise. In the compact case, we find half-supersymmetry preserving and asymptotically Minkowskian black string solutions. For a particular value of the scalar manifold radius, the solution coincides with that of Horne and Horowitz found in the context of a string theory in 2+1 dimensions. In the non-compact case, we find half-supersymmetry preserving and asymptotically AdS_3 string solutions which have naked singularities. We also obtain two distinct AdS_3 supergravities coupled to n copies of N=(1,0) scalar multiplets either by the truncation of the (2,0) model or by a direct construction.
We study codimension one branes, i.e. p-branes in (p+2)-dimensions, in the superembedding approach for the cases where the worldvolume superspace is embedded in a minimal target superspace with half supersymmetry breaking. This singles out the cases p=1,2,3,5,9. For p=3,5,9 the superembedding geometry naturally involves a fundamental super 2-form potential on the worldvolume whose generalised field strength obeys a constraint deducible from considering an open supermembrane ending on the p-brane. This constraint, together with the embedding constraint, puts the system on-shell for p=5 but overconstrains the 9-brane in D=11 such that the Goldstone superfield is frozen. For p=3 these two constraints give rise to an off-shell linear multiplet on the worldvolume. An alternative formulation of this case is given in which the linear multiplet is dualised to an off-shell scalar multiplet. Actions are constructed for both cases and are shown to give equivalent equations of motion. After gauge fixing a local Sp(1) symmetry associated with shifts in the Sp(1)_R Goldstone modes, we find that the auxiliary fields in the scalar multiplet parametrise a two-sphere. For completeness we also discuss briefly the cases p=1,2 where the equations of motion (for off-shell multiplets) are obtained from an action principle.
We review the basic structure of the higher spin extension of D=4, N=8 AdS supergravity. The theory is obtained by gauging the higher spin superalgebra shs^E(8|4) by a procedure pioneered by Vasiliev. The algebra shs^E(8|4) is a subalgebra of the enveloping algebra of OSp(8|4). The physical states of the theory are in one to one correspondence with the symmetric product of two OSp(8|4) singletons. This singleton theory, which may be viewed in a certain limit as the supermembrane theory on AdS_4 x S^7, is expected to describe the dynamics of the higher spin theory. Thus, the higher spin N=8 supergravity on AdS_4 is conjectured to describe the field theory limit of M-theory on AdS_4 x S^7.
The kappa symmetry of an open M2-brane ending on an M5-brane requires geometrical constraints on the embedding of the system in target superspace. These constraints lead to the M5-brane equations of motion, which we review both in superspace and in component (i.e. in Green-Schwarz) formalism. We also describe the embedding of the chiral M5-brane theory in a non-chiral theory where the equations of motion follow from an action that involves a non-chiral 2-form potential, upon the imposition of a non-linear self-duality condition. In this formulation, we find a simplified form of the second order field equation for the worldvolume 2-form potential, and we derive the nonlinear holomorphicity condition on the partition function of the chiral M5-brane.
We give a brief history of the passage from strings to branes and we review some aspects of the following topics in M-theory: (a) an extended brane scan, (b) superembedding approach to the dynamics of superbranes and (c) supermembranes in anti de Sitter space, singletons and massless higher spin field theories.
The product of two N=8 supersingletons yields an infinite tower of massless states of higher spin in four dimensional anti de Sitter space. All the states with spin s > 1/2 correspond to generators of Vasiliev's super higher spin algebra shs^E (8|4) which contains the D=4, N=8 anti de Sitter superalgebra OSp(8|4). Gauging the higher spin algebra and introducing a matter multiplet in a quasi-adjoint representation leads to a consistent and fully nonlinear equations of motion as shown sometime ago by Vasiliev. We show the embedding of the N=8 AdS supergravity equations of motion in the full system at the linearized level and discuss the implications for the embedding of the interacting theory. We furthermore speculate that the boundary N=8 singleton field theory yields the dynamics of the N=8 AdS supergravity in the bulk, including all higher spin massless fields, in an unbroken phase of M-theory.
The superembedding approach to $p$-branes is used to study a class of $p$-branes which have linear multiplets on the worldvolume. We refer to these branes as L-branes. Although linear multiplets are related to scalar multiplets (with 4 or 8 supersymmetries) by dualising one of the scalars of the latter to a $p$-form field strength, in many geometrical situations it is the linear multiplet version which arises naturally. Furthermore, in the case of 8 supersymmetries, the linear multiplet is off-shell in contrast to the scalar multiplet. The dynamics of the L-branes are obtained by using a systematic procedure for constructing the Green-Schwarz action from the superembedding formalism. This action has a Dirac-Born-Infeld type structure for the $p$-form. In addition, a set of equations of motion is postulated directly in superspace, and is shown to agree with the Green-Schwarz equations of motion.
Nonlinear sigma models arise in supergravity theories with or without matter couplings in various dimensions and they are important in understanding the duality symmetries of M-theory. With this motivation in mind, we review the salient features of gauged and ungauged nonlinear sigma models with or without Wess-Zumino terms for general target spaces in a minimal as well as lifted formulation. Relevant to the question of finding interesting vacua of gauged supergravity theories is the highly constrained potential which arises naturally in these theories. Motivated by this fact, we derive a general and simple formula for a gauge invariant potential of this kind.
We consider the (1,0) supersymmetric Yang-Mills multiplet coupled to a self-dual tensor multiplet in six dimensions. It is shown that the counterterm required to cancel the one-loop gauge anomaly modifies the classical equations of motion previously obtained by Bergshoeff, Sezgin and Sokatchev (BSS). We discuss the supermultiplet structure of the anomalies exhibited in the resulting equations of motion. The anomaly corrected field equations agree with the global limit, recently obtained by Duff, Liu, Lu and Pope, of a matter coupled supergravity theory in six dimensions. We also obtain the dual formulation of the BSS model in which the tensor multiplet is free while the field equations of the Yang-Mills multiplet contain the fields of the tensor multiplet at the classical level.
The complete spectrum of D=6, N=4b supergravity with n tensor multiplets compactified on AdS_3 x S^3 is determined. The D=6 theory obtained from the K_3 compactification of Type IIB string requires that n=21, but we let n be arbitrary. The superalgebra that underlies the symmetry of the resulting supergravity theory in AdS_3 coupled to matter is SU(1,1|2)_L x SU(1,1|2)_R. The theory also has an unbroken global SO(4)_R x SO(n) symmetry inherited from D=6. The spectrum of states arranges itself into a tower of spin-2 supermultiplets, a tower of spin-1, SO(n) singlet supermultiplets, a tower of spin-1 supermultiplets in the vector representation of SO(n) and a special spin-1/2 supermultiplet also in the vector representation of SO(n). The SU(2)_L x SU(2)_R Yang-Mills states reside in the second level of the spin-2 tower and the lowest level of the spin-1, SO(n) singlet tower and the associated field theory exhibits interesting properties.
Actions for branes, with or without worldsurface gauge fields, are discussed in a unified framework. A simple algorithm is given for constructing the component Green-Schwarz actions. Superspace actions are also discussed. Three examples are given to illustrate the general procedure: the membrane in D=11 and the D2-brane, which both have on-shell worldsurface supermultiplets, and the membrane in D=4, which has an off-shell multiplet.
Open branes ending on other branes, which may be referred to as the host branes, are studied in the superembedding formalism. The open brane, host brane and the target space in which they are both embedded are all taken to be supermanifolds. It is shown that the superspace constraints satisfied by the open brane are sufficient to determine the corresponding superspace constraints for the host branes, whose dynamics are determined by these constraints. As a byproduct, one also obtains information about the boundary of the open brane propagating in the host brane.
Actions for two-superparticle system in (10,2) dimensions and three-superparticle systems in (11,3) dimensions are constructed. These actions have worldline bosonic and fermionic local symmetries, and target space global supersymmety generalizing the reparametrization, kappa-symmetry and Poincare supersymmetry of the usual superparticle. With the second particle, or the second and third particles on-shell, they describe a superparticle propagating in the background of a second superparticle in (10,2) dimensions, or two other superparticles in (11,3) dimensions. Symmetries of the action are shown to exist in presence of super Yang-Mills background as well.
A model for $n$ superparticles in $(d-n,n)$ dimensions is studied. The target space supersymmetry involves a product of $n$ momentum generators, and the action has $n(n+1)/2$ local bosonic symmetries and $n$ local fermionic symmetries. The precise relation between the symmetries presented here and those existing in the literature is explained. A new model is proposed for superparticles in arbitrary dimensions where coordinates are associated with all the $p$-form charges occuring in the superalgebra. The model naturally gives rise to the BPS condition for the charges.
The covariant field equations of ten-dimensional super D-branes are obtained by considering fundamental strings whose ends lie in the superworldsurface of the D-brane. By considering in a similar fashion Dp-branes ending on D(p+2)-branes we derive equations describing D-branes with dual potentials, as well as the vector potentials.
Spacetime superalgebras with 64 or less number of real supercharges, containing the type IIB Poincare superalgebra in (9,1) dimensions and the N=1 Poincare superalgebra in (10,1) are considered. The restriction D<14, and two distinct possibilities arise: The N=(1,0) superalgebra in (11,3) dimensions, and the N=(2,0) superalgebra in (10,2) dimensions. Emphasizing the former, we describe superparticle and super Yang-Mills systems in (11,3) dimensions. We also propose an N=(2,1) superstring theory in (n,n) dimensions as a possible origin of super Yang-Mills in (8+n,n) dimensions.
Covariant field equations of M-fivebrane in eleven dimensional curved superspace are obtained from the requirement of kappa-symmetry of an open supermembrane ending on a fivebrane. The worldvolume of the latter is a (6|16) dimensional supermanifold embedded in the (11|32) dimensional target superspace. The kappa-symmetry of the system imposes a constraint on this embedding, and a constraint on a modified super 3-form field strength on the fivebrane worldvolume. These constraints govern the dynamics of the M-fivebrane.