相关论文: Superstrings in Graviphoton Background and N=1/2+3…
We study various aspects of N=(4,4) type IIA GS superstring theory in the pp-wave background, which arises as the compactification of maximally supersymmetric eleven-dimensional pp-wave geometry along the spacelike isometry direction. We…
We study open string amplitudes with the D3-branes in type IIB superstring theory compactified on C^2/Z_2. We introduce constant graviphoton background along the branes and calculate disk amplitudes using the NSR formalism. We take the zero…
We deform the standard four dimensional $\N=1$ superspace by making the odd coordinates $\theta$ not anticommuting, but satisfying a Clifford algebra. Consistency determines the other commutation relations of the coordinates. In particular,…
We discuss how to incorporate non-supersymmetric branes in compactifications of type II string theories. We particularly focus on flux compactifications on $SU(3)\times SU(3)$ structure manifolds to four dimensions, so that a linear…
In this article we summarise the brane solutions (instantons, black holes and strings) in 4 dimensions when embedded in N=2 supergravity. Like in 10 dimensions these solutions are related by duality transformations (T-duality, c-map). For…
We consider the field theory on non-commutative superspace and non-commutative spacetime that arises on D-branes in Type II superstring theory with a constant self-dual graviphoton and NS-NS $B$ field background. $\N=1$ supersymmetric field…
We study a class of type I string models with supersymmetry broken on the world-volume of some D-branes and vanishing tree-level potential. Despite the non-supersymmetric spectrum, supersymmetry is non-linearly realized on these D-branes,…
We construct supergravity theories in twelve and thirteen dimensions with the respective signatures (10,2) and (11,2) with some technical details. Starting with N=1 supergravity in 10+2 dimensions coupled to Green-Schwarz superstring, we…
A supersymmetric Randall-Sundrum brane-world demands that not merely the graviton but the entire supergravity multiplet be trapped on the brane. To demonstrate this, we present a complete ansatz for the reduction of (D=5,N=4) gauged…
Four dimensional supergravities may be the right framework to describe particle physics at low energies. Its connection to the underlying string theory can be implemented through higher dimensional supergravities which bear special…
In a given 4d spacetime bakcground, one can often construct not one but a family of distinct N=2 string theories. This is due to the multiple ways N=2 superconformal algebra can be embedded in a given worldsheet theory. We formulate the…
In this paper we obtain supersymmetric brane-like configurations in the vacuum of N=4 gauged $SU(2)\times SU(2)$ supergravity theory in four spacetime dimensions. Almost all of these vacuum solutions preserve either half or one quarter of…
The recent developments in superstring theory prompted the study of non-commutative structures in superspace. Considering bosonic and fermionic strings in a constant antisymmetric tensor background yields a non-vanishing commutator between…
We perform a systematic analysis of the D-brane charges associated with string theory realizations of d=3 gauge theories, focusing on the examples of the N=4 supersymmetric U(N)xU(N+M) Yang-Mills theory and the N=3 supersymmetric…
A correspondence between type IIB string theory with N D7-branes on R^{1,3} x C^1/Z_2 x T^2/Z_2 x T^2/Z_2 and pure N=1 SU(N) gauge theory in four dimensions is proposed and argued. First the supergravity background of unwrapped and flat…
We discuss flat compactifications of supergravities in diverse dimensions in the presence of branes. The compactification is induced by the scalar fields of supergravity and it is such that there is no relic cosmological constant on the…
We embed the supersymmetry breaking mechanism in N=1 SQCD of hep-th/0602239 in a smooth superstring theory using D-branes in the background R^4 \times SL(2)_{k=1}/U(1) which smoothly captures the throat region of an intersecting NS5-brane…
We investigate the holographic correspondence between (p+1)-dimensional ($0\le p\le 4$) SYM theories with 16 supercharges and superstring theories on the near-horizon limit of Dp-brane backgrounds. Following an approach based on the…
We review in a pedagogical manner some of the efforts aiming to extend the gauge/gravity correspondence to non-conformal supersymmetric gauge theories in four dimensions. After giving a general overview, we discuss in detail two specific…
In this thesis we discuss non-perturbative phenomena emerging in gauge and in string/supergravity theories. We compute the partition function of 5D minimal supersymmetric U(1) gauge theory with extra adjoint matter in general…