Browsing by Author "O'Loughlin, Martin"

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    1/8 BPS States in Ads/CFT
    (2006-11-09T11:36:47Z) Gava, Edi; Milanesi, Giuseppe; Narain, Kumar S.; O'Loughlin, Martin; Physics; Elementary Particle Theory
    We study a class of exact supersymmetric solutions of type IIB Supergravity. They have an SO(4) x SU(2) x U(1) isometry and preserve generically 4 of the 32 supersymmetries of the theory. Asymptotically AdS_5 x S^5 solutions in this class are dual to 1/8 BPS chiral operators which preserve the same symmetries in the N=4 SYM theory. They are parametrized by a set of four functions that satisfy certain differential equations. We analyze the solutions to these equations in a large radius asymptotic expansion: they carry charges with respect to two U(1) KK gauge fields and their mass saturates the expected BPS bound.
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    Singularities and Closed Timelike Curves in type IIB 1/2 BPS Geometries
    (2005) Milanesi, Giuseppe; O'Loughlin, Martin; Physics; Elementary Particle Theory
    We study in detail the moduli space of solutions discovered in LLM relaxing the constraint that guarantees the absence of singularities. The solutions fall into three classes, non-singular, null-singular and time machines with a time-like naked singularity. We study the general features of these metrics and prove that there are actually just two generic classes of space-times - those with null singularities are in the same class as the non-singular metrics. AdS/CFT seems to provide a dual description only for the first of these two types of space-time in terms of a unitary CFT indicating the possible existence of a chronology protection mechanism for this class of geometries.