Melvin Twists of global AdS_5 \times S_5 and their Non-Commutative Field Theory Dual

We consider the Melvin Twist of AdS_5 \times S_5 under U(1) \times U(1) isometry of the boundary S_3 of the global AdS_5 geometry and identify its field theory dual. We also study the thermodynamics of the Melvin deformed theory.Comment: 17 pages, references adde

Minimal Simple de Sitter Solutions

We show that the minimal set of necessary ingredients to construct explicit, four-dimensional de Sitter solutions from IIA string theory at tree-level are O6-planes, non-zero Romans mass parameter, form fluxes, and negative internal curvature. To illustrate our general results, we construct such minimal simple de Sitter solutions from an orientifold compactification of compact hyperbolic spaces. In this case there are only two moduli and we demonstrate that they are stabilized to a sufficiently weakly coupled and large volume regime. We also discuss generalizations of the scenario to more general metric flux constructions.Comment: 12 pages, 2 figures, important error in v1 corrected but main result unaltered; v3 sent to PRD; v4 version published in PRD, minor modifications for clarificatio

Non-commutativity and Open Strings Dynamics in Melvin Universes

We compute the Moyal phase factor for open strings ending on D3-branes wrapping a NSNS Melvin universe in a decoupling limit explicitly using world sheet formalism in cylindrical coordinates.Comment: 12 pages, 1 figure, references adde

Mass-spin relation for quark anti-quark bound states in non-commutative Yang-Mills theory

We investigate the relationship between mass and spin of quark anti-quark bound state in non-commutative gauge theory with N=4 supersymmetry. In the large N and large 't Hooft coupling limit, these bound states correspond to rotating open strings ending on a D-brane embedded into the supergravity background dual of the non-commutative field theory. Although the physical configuration of the open strings are drastically deformed by the non-commutativity, we find that the relation between the energy and the angular momentum of the bound state is unaffected by the non-commutativity parameter. We also clarify the holographic interpretation of quark anti-quark potential in non-commutative gauge theories.Comment: 22 pages, 9 figures, v2: references added, note added. v3: Major revision. New material (section 4) added. Title and abstract edite