29,161 research outputs found

    Macroscopic superstrings as interpolating solitons

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    It is known that, in string sigma-model metric, the `extreme' fivebrane solution of D=10 supergravity interpolates between D=10 Minkowski spacetime and a supersymmetric S3S^3 compactification to a linear dilaton vacuum. We show here that, in {\it fivebrane} sigma-model metric, the extreme string solution of D=10 supergravity interpolates between Minkowski spacetime and a hitherto unknown supersymmetric S7S^7 compactification of d=10 supergravity to a three-dimensional anti-de Sitter generalization of the linear dilaton vacuum, which may be invariantly characterized in terms of conformal Killing vectors. The dilaton field diverges near the string core but this divergence may be eliminated by re-interpreting the string solution as the extreme membrane solution of 11-dimensional supergravity. We show that the latter has an analytic extension through a regular degenerate event horizon to an interior region containing a curvature singularity. We obtain analogous results for other extended object solutions of supergravity theories.Comment: 12 page

    String and Fivebrane Solitons: Singular or Non-singular?

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    We ask whether the recently discovered superstring and superfivebrane solutions of D=10 supergravity admit the interpretation of non-singular solitons even though, in the absence of Yang-Mills fields, they exhibit curvature singularities at the origin. We answer the question using a test probe/source approach, and find that the nature of the singularity is probe-dependent. If the test probe and source are both superstrings or both superfivebranes, one falls into the other in a finite proper time and the singularity is real, whereas if one is a superstring and the other a superfivebrane it takes an infinite proper time (the force is repulsive!) and the singularity is harmless. Black strings and fivebranes, on the other hand, always display real singularities.Comment: 15 page

    Hodge Duality on the Brane

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    It has been claimed that whereas scalars can be bound to a Randall-Sundrum brane, higher p-form potentials cannot, in contradiction with the Hodge duality between 0-form and 3-form potentials in the five-dimensional bulk. Here we show that a 3-form in the bulk correctly yields a 2-form on the brane, in complete agreement with both bulk and brane duality. We also emphasize that the phenomenon of photon screening in the Randall-Sundrum geometry is ruled out by the bulk Einstein equation.Comment: 6 pages, Latex. We emphasize that the phenomenon of photon screening in the Randall-Sundrum geometry is ruled out by the bulk Einstein equatio

    On the determination of the dilaton-antisymmetric tensor couplings in supergravity theories

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    A new approach is provided to determine the dilaton--antisymmetric tensor coupling in a supergravity theory by considering the static supersymmetric field configuration around a super extended object, which is consistently formulated in a curved superspace. By this, the corresponding SUSY transformation rules can also be determined for vanishing fermionic fields as well as bosonic fields other than those in the determined coupling. Therefore, we can, in turn, use this determined part of the supergravity theory to study all the related vacuum-like solutions. We have determined the dilaton--antisymmetric tensor couplings, in which each of the antisymmetric tensors is a singlet of the automorphism group of the corresponding superalgebra, for every supergravity multiplet. This actually happens only for N≀2N \leq 2 supergravity theories, which agrees completely with the spin-content analysis and the classified N≀2N \leq 2 super pp-branes, therefore giving more support to the existence of the fundamental Type II pp-branes. A prediction is made of the D=9,N=2D = 9, N = 2 supergravity which has not yet been written down so far.Comment: 23 pages, harvmac, CERN-TH.6691/9

    Four Dimensional String/String/String Triality

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    In six spacetime dimensions, the heterotic string is dual to a Type IIAIIA string. On further toroidal compactification to four spacetime dimensions, the heterotic string acquires an SL(2,\BbbZ)_S strong/weak coupling duality and an SL(2,\BbbZ)_T \times SL(2,\BbbZ)_U target space duality acting on the dilaton/axion, complex Kahler form and the complex structure fields S,T,US,T,U respectively. Strong/weak duality in D=6D=6 interchanges the roles of SS and TT in D=4D=4 yielding a Type IIAIIA string with fields T,S,UT,S,U. This suggests the existence of a third string (whose six-dimensional interpretation is more obscure) that interchanges the roles of SS and UU. It corresponds in fact to a Type IIBIIB string with fields U,T,SU,T,S leading to a four-dimensional string/string/string triality. Since SL(2,\BbbZ)_S is perturbative for the Type IIBIIB string, this D=4D=4 triality implies SS-duality for the heterotic string and thus fills a gap left by D=6D=6 duality. For all three strings the total symmetry is SL(2,\BbbZ)_S \times O(6,22;\BbbZ)_{TU}. The O(6,22;\BbbZ) is {\it perturbative} for the heterotic string but contains the conjectured {\it non-perturbative} SL(2,\BbbZ)_X, where XX is the complex scalar of the D=10D=10 Type IIBIIB string. Thus four-dimensional triality also provides a (post-compactification) justification for this conjecture. We interpret the N=4N=4 Bogomol'nyi spectrum from all three points of view. In particular we generalize the Sen-Schwarz formula for short multiplets to include intermediate multiplets also and discuss the corresponding black hole spectrum both for the N=4N=4 theory and for a truncated SS--TT--UU symmetric N=2N=2 theory. Just as the first two strings are described by the four-dimensional {\it elementary} and {\it dual solitonic} solutions, so theComment: 36 pages, Latex, 2 figures, some references changed, minor changes in formulas and tables; to appear in Nucl. Phys.

    g=1 for Dirichlet 0-branes

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    Dirichlet 0-branes, considered as extreme Type IIA black holes with spin carried by fermionic hair, are shown to have the anomalous gyromagnetic ratio g=1, consistent with their interpretation as Kaluza-Klein modes.Comment: 13 pages, Late

    The Coupling of Yang-Mills to Extended Objects

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    The coupling of Yang-Mills fields to the heterotic string in bosonic formulation is generalized to extended objects of higher dimension (p-branes). For odd p, the Bianchi identities obeyed by the field strengths of the (p+1)-forms receive Chern-Simons corrections which, in the case of the 5-brane, are consistent with an earlier conjecture based on string/5-brane duality.Comment: 14 Page

    Evidence for Heterotic/Heterotic Duality

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    We re-examine the question of heterotic - heterotic string duality in six dimensions and argue that the E8×E8E_8\times E_8 heterotic string, compactified on K3K3 with equal instanton numbers in the two E8E_8's, has a self-duality that inverts the coupling, dualizes the antisymmetric tensor, acts non-trivially on the hypermultiplets, and exchanges gauge fields that can be seen in perturbation theory with gauge fields of a non-perturbative origin. The special role of the symmetric embedding of the anomaly in the two E8E_8's can be seen from field theory considerations or from an eleven-dimensional point of view. The duality can be deduced by looking in two different ways at eleven-dimensional MM-theory compactified on K3×S1/Z2K3\times {\bf S}^1/\Z_2.Comment: 36 pages, LaTe

    The Octonionic Membrane

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    We generalize the supermembrane solution of D=11 supergravity by permitting the 4-form GG to be either self-dual or anti-self-dual in the eight dimensions transverse to the membrane. After analyzing the supergravity field equations directly, and also discussing necessary conditions for unbroken supersymmetry, we focus on two specific, related solutions. The self-dual solution is not asymptotically flat. The anti-self-dual solution is asymptotically flat, has finite mass per unit area and saturates the same mass=charge Bogomolnyi bound as the usual supermembrane. Nevertheless, neither solution preserves any supersymmetry. Both solutions involve the octonionic structure constants but, perhaps surprisingly, they are unrelated to the octonionic instanton 2-form FF, for which TrF∧FTrF \wedge F is neither self-dual nor anti-self-dual.Comment: 17 pages, Latex; enhanced discussion on supersymmetry, some references adde

    Anti-de Sitter Black Holes in Gauged N=8 Supergravity

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    We present new anti-de Sitter black hole solutions of gauged N=8, SO(8) supergravity, which is the massless sector of the AdS_4\times S^7 vacuum of M-theory. By focusing on the U(1)^4 Cartan subgroup, we find non-extremal 1, 2, 3 and 4 charge solutions. In the extremal limit, they may preserve up to 1/2, 1/4, 1/8 and 1/8 of the supersymmetry, respectively. In the limit of vanishing SO(8) coupling constant, the solutions reduce to the familiar black holes of the M_4\times T^7 vacuum, but have very different interpretation since there are no winding states on S^7 and no U-duality. In contrast to the T^7 compactification, moreover, we find no static multi-center solutions. Also in contrast, the S^7 fields appear "already dualized" so that the 4 charges may be all electric or all magnetic rather than 2 electric and 2 magnetic. Curiously, however, the magnetic solutions preserve no supersymmetries. We conjecture that a subset of the extreme electric black holes preserving 1/2 the supersymmetry may be identified with the S^7 Kaluza-Klein spectrum, with the non-abelian SO(8) quantum numbers provided by the fermionic zero modes.Comment: 18 pages, Latex, minor notation improvements and references adde
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