New Supersymmetric Solutions in N=2 Matter Coupled AdS_3 Supergravities

We construct new 1/2 supersymmetric solutions in D=3, N=2, matter coupled, U(1) gauged supergravities and study some of their properties. We do this by employing a quite general supersymmetry breaking condition, from which we also redrive some of the already known solutions. Among the new solutions, we have an explicit non-topological soliton for the non-compact sigma model, a locally flat solution for the compact sigma model and a string-like solution for both types of sigma models. The last one is smooth for the compact scalar manifold.Comment: 1+21 pages, 2 figures, LaTeX2e, JHEP style; v2: added one reference + made minor changes and added a few comments to clarify the presentatio

AdS pp-waves

We obtain the pp-waves of D=5 and D=4 gauged supergravities supported by $U(1)^3$ and $U(1)^4$ gauge field strengths respectively. We show that generically these solutions preserve 1/4 of the supersymmetry, but supernumerary supersymmetry can arise for appropriately constrained harmonic functions associated with the pp-waves. In particular it implies that the solutions are independent of the light-cone coordinate $x^+$. We also obtain the pp-waves in the Freedman-Schwarz model.Comment: Latex, 19 pages, minor changes, to appear in JHE

Supergravity Duals to the Noncommutative N=4 SYM theory in the Infinite Momentum Frame

In this work the construction of supergravity duals to the noncommutative ${\cal N}=4$ SYM theory in the infinite momentum frame but with constant momentum density is attempted. In the absence of the content of noncommutativity, it has been known for some time that the previous $AdS_{5}/CFT_{4}$ correspondence should be replaced by the $K_{5}/CFT_{4}$ (with $K_{(p+2)}$ denoting the generalized Kaigorodov spacetime) correspondence with the pp-wave propagating on the BPS brane worldvolume. Interestingly enough, putting together the two contents, i.e., the introduction of noncommutativity and at the same time that of the pp-wave along the brane worldvolume, leads to quite nontrivial consequences such as the emergence of ``time-space'' noncommutativity in addition to the ``space-space'' noncommutativity in the manifold on which the dual gauge theory is defined. Taking the gravity decoupling limit, it has been realized that for small $u$, the solutions all reduce to $K_{5}\times S^5$ geometry confirming our expectation that the IR dynamics of the dual gauge theory should be unaffected by the noncommutativity while as $u\to \infty$, the solutions start to deviate significantly from $K_{5}\times S^5$ limit indicating that the UV dynamics of the dual gauge theory would be heavily distorted by the effect of noncommutativity.Comment: 21 pages, Latex, One expression changed, a reference added, to appear in Phys. Rev.