Diffeomorphism, kappa transformations and the theory of non-linear realisations

We will show how the theory of non-linear realisations can be used to naturally incorporate world line diffeomorphisms and kappa transformations for the point particle and superpoint particle respectively. Similar results also hold for a general p-brane and super p-brane, however, we must in these cases include an additional Lorentz transformation.Comment: 19pages, no figure. References are added and typos are correcte

A Note on Unitarity of Non-Relativistic Non-Commutative Theories

We analyze the unitarity of a non-relativistic non-commutative scalar field theory. We show that electric backgrounds spoil unitarity while magnetic ones do not. Furthermore, unlike its relativistic counterparts, unitarity can not be restored (at least at the level of one-to-one scattering amplitude) by adding new states to the theory. This is a signal that the model cannot be embedded in a natural way in string theory.Comment: 6 pages, 2 figures. References adde

Schwarzschild Black Hole in Noncommutative Spaces

We study the effects of noncommutative spaces on the horizon, the area spectrum and Hawking temperature of a Schwarzschild black hole. The results show deviations from the usual horizon, area spectrum and the Hawking temperature. The deviations depend on the parameter of space-space noncommutativity.Comment: 4 pages, accepted for publication in Gen.Rel.Gra

A prediction for bubbling geometries

We study the supersymmetric circular Wilson loops in N=4 Yang-Mills theory. Their vacuum expectation values are computed in the parameter region that admits smooth bubbling geometry duals. The results are a prediction for the supergravity action evaluated on the bubbling geometries for Wilson loops.Comment: 21 pages, latex; v.2 reference added; v.3 minor correction

BIons in topological string theory

When many fundamental strings are stacked together, they puff up into D-branes. BIons and giant gravitons are the examples of such D-brane configurations that arise from coincident strings. We propose and demonstrate analogous transitions in topological string theory. Such transitions can also be understood in terms of the Fourier transform of D-brane amplitudes.Comment: 21 pages; v.2 references added; v.3 reference added; v.4 minor corrections; v.5 substantial rewritin

Noether's theorem and gauge transformations. Application to the bosonic string and CP(2,n-1) model

New results on the theory of constrained systems are applied to characterize the generators of Noethers symmetry transformations. As a byproduct, an algorithm to construct gauge transformations in Hamiltonian formalism is derived. This is illustrated with two relevant examples

The Gauge Dual of Gauged N=8 Supergravity Theory

The most general SU(3)-singlet space of gauged N=8 supergravity in four-dimensions is studied recently. The SU(3)-invariant six scalar fields are realized by six real four-forms. A family of holographic N=1 supersymmetric RG flows on M2-branes in three-dimensions is described. This family of flows is driven by three independent mass parameters from the N=8 SO(8) theory and is controlled by two IR fixed points, N=1 G_2-invariant one and N=2 SU(3) x U(1)-invariant one. The generic flow with arbitrary mass parameters is N=1 supersymmetric and reaches to the N=2 SU(3) x U(1) fixed point where the three masses become identical. A particular N=1 supersymmetric SU(3)-preserving RG flow from the N=1 G_2-invariant fixed point to the N=2 SU(3) x U(1)-invariant fixed point is also discussed.Comment: 19pp; added the footnote 1, improved the conclusion and to appear in IJMP

A Superspace Formulation for the Master Equation

It is shown that the quantum master equation of the Field Antifield quantization method at one loop order can be translated into the requirement of a superfield structure for the action. The Pauli Villars regularization is implemented in this BRST superspace and the case of anomalous gauge theories is investigated. The quantum action, including Wess Zumino terms, shows up as one of the components of a superfield that includes the BRST anomalies in the other component. The example of W2 quantum gravity is also discussed.Comment: The constrained nature of standard BRST superfields and the importance of using Alfaro and Damgaard's collective fields in the superspace approach to avoid undefined superfield derivatives was emphasized. To appear in Phys. Rev. D. Latex file, 20 page

M2-Branes and Background Fields

We discuss the coupling of multiple M2-branes to the background 3-form and 6-form gauge fields of eleven-dimensional supergravity, including the coupling of the Fermions. In particular we show in detail how a natural generalization of the Myers flux-terms, along with the resulting curvature of the background metric, leads to mass terms in the effective field theory.Comment: 19 page

D-branes as a Bubbling Calabi-Yau

We prove that the open topological string partition function on a D-brane configuration in a Calabi-Yau manifold X takes the form of a closed topological string partition function on a different Calabi-Yau manifold X_b. This identification shows that the physics of D-branes in an arbitrary background X of topological string theory can be described either by open+closed string theory in X or by closed string theory in X_b. The physical interpretation of the ''bubbling'' Calabi-Yau X_b is as the space obtained by letting the D-branes in X undergo a geometric transition. This implies, in particular, that the partition function of closed topological string theory on certain bubbling Calabi-Yau manifolds are invariants of knots in the three-sphere.Comment: 32 pages; v.2 reference adde