Non-spherical horizons, I

We formulate an extension of Maldacena’s AdS/CFT conjectures to the case of branes located at singular points in the ambient transverse space. For singularities which occur at finite distance in the moduli space of M or F theory models with spacetime-filling branes, the conjectures identify the worldvolume theory on the p-branes with a compactification of M or IIB theory on AdSp+2 × HD−p−2. We show how the singularity determines the horizon H, and demonstrate the relationship between global symmetries on the worldvolume and gauge symmetries in the AdS model. As a first application, we study some singularities relevant to the D3-branes required in four-dimensional F -theory. For these we are able to explicitly derive the low-energy field theory on the worldvolume and compare its properties to predictions from the dual AdS model. In particular, we examine the baryon spectra of the models and the fate of the Abelian factors in the gauge group. October 1998 ∗ On leave from Department of Particle Physics, Weizmann Institute of Science, Rehovot, Israel Spacetime-filling branes have emerged as an essential feature of string and M-theory compactifications in at least three contexts: (1) new branches of the heterotic string in six dimensions with “extra” tensor multiplets, which can be represented by a Hořava– Witten-type compactification of M-theory on (S/Z2) × K3 but with extra spacetimefilling M5-branes representing the extra tensor multiplets [1,2,3]; (2) F -theory models in four dimensions (which can be regarded as compactifications of the IIB string with D7branes included) which in general require spacetime-filling D3-branes to cancel a tadpole anomaly [4]; and (3) M-theory models in three dimensions, which require spacetime-filling M2-branes to cancel a similar tadpole anomaly [4]. In each of these cases, the spacetimefilling brane meets the compactifying space at a single point, and the string or M-theory remains finite near the brane. Remarkably, this short list of branes (M5, D3, and M2) is precisely the list of branes for which a certain scaling limit is expected to lead to a “boundary” conformal field theory in the recent AdS/CFT conjectures [5,6,7]. In fact, the scaling limit can be taken even when the space transverse to the branes is curved, as in the compactification scenarios above. The details of the metric far from the location y0 of the brane in the transverse space become irrelevant; for the purposes of studying the scaling limit, the metric on the compactifying space can be approximated by some metric on its tangent space Ty0 at y0. In the scaling limit, the rescaled supergravity metric approaches a metric of the form AdSp+2 × S in which the anti-de Sitter space has been formed out of the worldvolume of the brane and the radial direction within Ty0 , and S k is the unit sphere within Ty0 . Maldacena’s conjecture proposes that the M or string theory on this space AdSp+2 × S, with N units of flux of the supergravity k-form field strength through S, is dual to a specific conformal field theory on the boundary of AdSp+2. The conjecture applies to the large N limit when a large number of these branes have been brought together; in the compactification context, fairly large values of N can be obtained by bringing together all available branes in a given model. Virtually all points in the compactifying space have identical behavior in this scaling limit. That situation changes, however, if we consider a compactifying space which itself 1 This last requirement excludes consideration of F -theory models in eight dimensions with the D7-brane being spacetime-filling. 2 The exception is the four-dimensional F -theory models, where points located along the D7branes behave differently; in particular, the string coupling becomes infinite at such points. The behavior of D3-branes at such points has recently been determined [8,9,10], and we will not