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Papers by George Papadopoulos

Communications in Mathematical Physics, 1999

We investigate the solutions of Nambu–Goto-type actions associated with calibrations. We determin... more We investigate the solutions of Nambu–Goto-type actions associated with calibrations. We determine the supersymmetry preserved by these solutions using the contact set of the calibration and examine their bulk interpretation as intersecting branes. We show that the supersymmetry preserved by such solutions is closely related to the spinor singlets of the subgroup G of Spin (9,1) or Spin (10,1) that rotates the tangent spaces of the brane. We find that the supersymmetry projections of the worldvolume solutions are precisely those of the associated bulk configurations. We also investigate the supersymmetric solutions of a Born–Infeld action. We show that in some cases this problem again reduces to counting spinor singlets of a subgroup of Spin (9,1) acting on the associated spinor representations. We also find new worldvolume solutions which preserve 1/8 of the supersymmetry of the bulk and give their bulk interpretation.

Nuclear Physics B, 1996

We present dyonic multi-membrane solutions of the N=2 D=8 supergravity theory that serves as the ... more We present dyonic multi-membrane solutions of the N=2 D=8 supergravity theory that serves as the effective field theory of the T 2 -compactified type II superstring theory. The 'electric' charge is fractional for generic asymptotic values of an axion field, as for D=4 dyons. These membrane solutions are supersymmetric, saturate a Bogomolnyi bound, fill out orbits of an Sl(2; Z) subgroup of the type II D=8 T-duality group, and are non-singular when considered as solutions of T 3 -compactified D=11 supergravity. On K 3 compactification to D=4, the conjectured type II/heterotic equivalence allows the Sl(2; Z) group to be reinterpreted as the S-duality group of the toroidally compactified heterotic string and the dyonic membranes wrapped around homology two-cycles of K 3 as S-duals of perturbative heterotic string states.

Physical Review D, 1999

A static minimal energy configuration of a super p-brane in a supersymmetric (n+1)-dimensional sp... more A static minimal energy configuration of a super p-brane in a supersymmetric (n+1)-dimensional spacetime is shown to be a `generalized calibrated' submanifold. Calibrations in bE(1,n)\bE^{(1,n)}bE(1,n) and AdSn+1AdS_{n+1}AdSn+1 are special cases. We present several M-brane examples.

Physics Letters B, 1996

We present the magnetic duals of Güven's electric-type solutions of D=11 supergravity preserving ... more We present the magnetic duals of Güven's electric-type solutions of D=11 supergravity preserving 1/4 or 1/8 of the D=11 supersymmetry. We interpret the electric solutions as n orthogonal intersecting membranes and the magnetic solutions as n orthogonal intersecting 5-branes, with n = 2, 3; these cases obey the general rule that p-branes can self-intersect on (p − 2)-branes. On reduction to D = 4 these solutions become electric or magnetic dilaton black holes with dilaton coupling constant a = 1 (for n = 2) or a = 1/ √ 3 (for n = 3). We also discuss the reduction to D=10.

Nuclear Physics B, 1996

We present a version of ten-dimensional IIA supergravity containing a 9-form potential for which ... more We present a version of ten-dimensional IIA supergravity containing a 9-form potential for which the field equations are equivalent to those of the standard, massless, IIA theory for vanishing 10-form field strength, FH. and to those of the 'massive' IIA theory for non-vanishing F~0. We present a multi 8-brane solution of these equations that generalizes the 8-brane of Polchinski and Wittcn. We show that this solution is T-dual to a new multi 7-brane solution of S l compactified lib supergravity, and that the latter is T-dual to the IIA 6-brane. When combined with the S/(2; Z) U-duality of the type-liB superstring, the 7"-duality between type-ll 7-branes and 8-branes implies a quantization of the cosmological constant of type-IIA superstring theory. These results are made possible by the construction of a new massive N = 2 D = 9 supergravity theory. We also discuss thc 1 l-dimensional interpretation of these type-ll p-branes.

Physics Letters B, 1995

We investigate the compactification of D=11 supergravity to D=5,4,3, on compact manifolds of holo... more We investigate the compactification of D=11 supergravity to D=5,4,3, on compact manifolds of holonomy SU(3) (Calabi-Yau), G 2 , and Spin , respectively, making use of examples of the latter two cases found recently by Joyce. In each case the lower dimensional theory is a Maxwell/Einstein supergravity theory.

Nuclear Physics B, 1997

Generalized membrane solutions of D=11 supergravity, for which the transverse space is a toric hy... more Generalized membrane solutions of D=11 supergravity, for which the transverse space is a toric hyper-Kähler manifold, are shown to have IIB duals representing the intersection of parallel 3-branes with 5-branes whose orientations are determined by their Sl(2; Z) charge vectors. These IIB solutions, which generically preserve 3/16 of the supersymmetry, can be further mapped to solutions of D=11 supergravity representing the intersection of parallel membranes with any number of fivebranes at arbitrary angles. Alternatively, a subclass (corresponding to nonsingular D=11 solutions) can be mapped to solutions representing the intersection on a string of any number of D-5-branes at arbitrary angles, again preserving 3/16 supersymmetry, as we verify in a special case by a quaternionic extension of the analysis of Berkooz, Douglas and Leigh. We also use similar methods to find new 1/8 supersymmetric solutions of orthogonally intersecting branes.

Communications in Mathematical Physics, 1999

We investigate the solutions of Nambu–Goto-type actions associated with calibrations. We determin... more We investigate the solutions of Nambu–Goto-type actions associated with calibrations. We determine the supersymmetry preserved by these solutions using the contact set of the calibration and examine their bulk interpretation as intersecting branes. We show that the supersymmetry preserved by such solutions is closely related to the spinor singlets of the subgroup G of Spin (9,1) or Spin (10,1) that rotates the tangent spaces of the brane. We find that the supersymmetry projections of the worldvolume solutions are precisely those of the associated bulk configurations. We also investigate the supersymmetric solutions of a Born–Infeld action. We show that in some cases this problem again reduces to counting spinor singlets of a subgroup of Spin (9,1) acting on the associated spinor representations. We also find new worldvolume solutions which preserve 1/8 of the supersymmetry of the bulk and give their bulk interpretation.

Nuclear Physics B, 1996

We present dyonic multi-membrane solutions of the N=2 D=8 supergravity theory that serves as the ... more We present dyonic multi-membrane solutions of the N=2 D=8 supergravity theory that serves as the effective field theory of the T 2 -compactified type II superstring theory. The 'electric' charge is fractional for generic asymptotic values of an axion field, as for D=4 dyons. These membrane solutions are supersymmetric, saturate a Bogomolnyi bound, fill out orbits of an Sl(2; Z) subgroup of the type II D=8 T-duality group, and are non-singular when considered as solutions of T 3 -compactified D=11 supergravity. On K 3 compactification to D=4, the conjectured type II/heterotic equivalence allows the Sl(2; Z) group to be reinterpreted as the S-duality group of the toroidally compactified heterotic string and the dyonic membranes wrapped around homology two-cycles of K 3 as S-duals of perturbative heterotic string states.

Physical Review D, 1999

A static minimal energy configuration of a super p-brane in a supersymmetric (n+1)-dimensional sp... more A static minimal energy configuration of a super p-brane in a supersymmetric (n+1)-dimensional spacetime is shown to be a `generalized calibrated' submanifold. Calibrations in bE(1,n)\bE^{(1,n)}bE(1,n) and AdSn+1AdS_{n+1}AdSn+1 are special cases. We present several M-brane examples.

Physics Letters B, 1996

We present the magnetic duals of Güven's electric-type solutions of D=11 supergravity preserving ... more We present the magnetic duals of Güven's electric-type solutions of D=11 supergravity preserving 1/4 or 1/8 of the D=11 supersymmetry. We interpret the electric solutions as n orthogonal intersecting membranes and the magnetic solutions as n orthogonal intersecting 5-branes, with n = 2, 3; these cases obey the general rule that p-branes can self-intersect on (p − 2)-branes. On reduction to D = 4 these solutions become electric or magnetic dilaton black holes with dilaton coupling constant a = 1 (for n = 2) or a = 1/ √ 3 (for n = 3). We also discuss the reduction to D=10.

Nuclear Physics B, 1996

We present a version of ten-dimensional IIA supergravity containing a 9-form potential for which ... more We present a version of ten-dimensional IIA supergravity containing a 9-form potential for which the field equations are equivalent to those of the standard, massless, IIA theory for vanishing 10-form field strength, FH. and to those of the 'massive' IIA theory for non-vanishing F~0. We present a multi 8-brane solution of these equations that generalizes the 8-brane of Polchinski and Wittcn. We show that this solution is T-dual to a new multi 7-brane solution of S l compactified lib supergravity, and that the latter is T-dual to the IIA 6-brane. When combined with the S/(2; Z) U-duality of the type-liB superstring, the 7"-duality between type-ll 7-branes and 8-branes implies a quantization of the cosmological constant of type-IIA superstring theory. These results are made possible by the construction of a new massive N = 2 D = 9 supergravity theory. We also discuss thc 1 l-dimensional interpretation of these type-ll p-branes.

Physics Letters B, 1995

We investigate the compactification of D=11 supergravity to D=5,4,3, on compact manifolds of holo... more We investigate the compactification of D=11 supergravity to D=5,4,3, on compact manifolds of holonomy SU(3) (Calabi-Yau), G 2 , and Spin , respectively, making use of examples of the latter two cases found recently by Joyce. In each case the lower dimensional theory is a Maxwell/Einstein supergravity theory.

Nuclear Physics B, 1997

Generalized membrane solutions of D=11 supergravity, for which the transverse space is a toric hy... more Generalized membrane solutions of D=11 supergravity, for which the transverse space is a toric hyper-Kähler manifold, are shown to have IIB duals representing the intersection of parallel 3-branes with 5-branes whose orientations are determined by their Sl(2; Z) charge vectors. These IIB solutions, which generically preserve 3/16 of the supersymmetry, can be further mapped to solutions of D=11 supergravity representing the intersection of parallel membranes with any number of fivebranes at arbitrary angles. Alternatively, a subclass (corresponding to nonsingular D=11 solutions) can be mapped to solutions representing the intersection on a string of any number of D-5-branes at arbitrary angles, again preserving 3/16 supersymmetry, as we verify in a special case by a quaternionic extension of the analysis of Berkooz, Douglas and Leigh. We also use similar methods to find new 1/8 supersymmetric solutions of orthogonally intersecting branes.