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14
A nogo theorem for string warped compactifications
, 2000
"... We give necessary conditions for the existence of perturbative heterotic and type II string warped compactifications preserving eight and four supersymmetries to four spacetime dimensions, respectively. In particular, we find that the only compactifications of heterotic string with the spin connecti ..."
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We give necessary conditions for the existence of perturbative heterotic and type II string warped compactifications preserving eight and four supersymmetries to four spacetime dimensions, respectively. In particular, we find that the only compactifications of heterotic string with the spin connection embedded in the gauge connection and type II strings are those on CalabiYau manifolds with constant dilaton. We obtain similar results for compactifications to six and to two dimensions.
Brane Solutions in Time Dependent Backgrounds in D =11 Supergravity and in Type II String Theories
, 2007
"... We obtain explicit time dependent brane solutions in Mtheory as well as in string theory by solving the reduced equations of motion (which follow, as in [1], from 11d supergravity) for a class of brane solutions in curved backgrounds. The behaviour of our solutions in both asymptotic and nearhori ..."
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We obtain explicit time dependent brane solutions in Mtheory as well as in string theory by solving the reduced equations of motion (which follow, as in [1], from 11d supergravity) for a class of brane solutions in curved backgrounds. The behaviour of our solutions in both asymptotic and nearhorizon limits are studied. It is shown that our time dependent solutions serve as explicit examples of branes in singular, cosmological backgrounds. In some special cases the asymptotic and the boundary AdS solutions can be identified as Milne × R n spacetime.
MCTP0014 OHSTPYHEPT01001
, 2001
"... We study supergravity solutions representing D3branes with transverse 6space having R×S 2 ×S 3 topology. We consider regular and fractional D3branes on a natural oneparameter extensions of the standard CalabiYau metrics on the singular and resolved conifolds. After imposing a Z2 identification ..."
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We study supergravity solutions representing D3branes with transverse 6space having R×S 2 ×S 3 topology. We consider regular and fractional D3branes on a natural oneparameter extensions of the standard CalabiYau metrics on the singular and resolved conifolds. After imposing a Z2 identification on an angular coordinate these generalized “6d conifolds ” are nonsingular spaces. The backreaction of D3branes creates a curvature singularity that coincides with a horizon. In the presence of fractional D3branes the solutions are similar to the original ones in hepth/0002159, hepth/0010088: the metric has a naked repulsontype singularity located behind the radius where the 5form flux vanishes. The semiclassical behavior of the Wilson loop suggests that the corresponding gauge theory duals are confining. One fruitful approach to generalize the original AdS/CFT correspondence [1] to more “realistic ” gauge theories with less supersymmetries is based on considering D3branes
AdS in Warped Spacetimes
, 2000
"... We obtain a large class of AdS spacetimes warped with certain internal spaces in elevendimensional and type IIA/IIB supergravities. The warp factors depend only on the internal coordinates. These solutions arise as the nearhorizon geometries of more general semilocalised multiintersections of pbr ..."
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We obtain a large class of AdS spacetimes warped with certain internal spaces in elevendimensional and type IIA/IIB supergravities. The warp factors depend only on the internal coordinates. These solutions arise as the nearhorizon geometries of more general semilocalised multiintersections of pbranes. We achieve this by noting that any sphere (or AdS spacetime) of dimension greater than 3 can be viewed as a foliation involving S3 (or AdS3). Then the S3 (or AdS3) can be replaced by a threedimensional lens space (or a BTZ black hole), which arises naturally from the introduction of a NUT (or a ppwave) to the Mbranes or the D3brane. We then obtain multiintersections by performing a KaluzaKlein reduction or Hopf Tduality transformation on the fibre coordinate of the lens space (or the BTZ black hole). These geometries provide further possible examples of the AdS/CFT correspondence and of consistent embeddings of lowerdimensional gauged supergravities in D = 11 or D = 10.
UM–TH/0024 OHSTPYHEPT00019 3Branes on Resolved Conifold
, 2000
"... The type IIB supergravity solution describing a collection of regular and fractional D3 branes on the conifold (hepth/0002159) was recently generalized to the case of the deformed conifold (hepth/0007191). Here we present another generalization – when the conifold is replaced by the resolved conif ..."
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The type IIB supergravity solution describing a collection of regular and fractional D3 branes on the conifold (hepth/0002159) was recently generalized to the case of the deformed conifold (hepth/0007191). Here we present another generalization – when the conifold is replaced by the resolved conifold. This solution can be found in two different ways: (i) by first explicitly constructing the Ricciflat Kähler metric on resolved conifold and then solving the supergravity equations for the D3brane ansatz with constant dilaton and (selfdual) 3form fluxes; (ii) by generalizing the “conifold ” ansatz of hepth/0002159 in a natural “asymmetric ” way so that the 1d action describing radial evolution still admits a superpotential and then solving the resulting 1st order system. The superpotentials corresponding to the “resolved ” and “deformed ” cases turn out to have essentially the same simple structure. The solution for the resolved conifold case has the same asymptotic UV behaviour as in the conifold case, but unlike the deformed conifold case is still singular in the IR. The naked singularity is of repulson type and may have a brane resolution.