Aspects of Puff Field Theory

We describe some features of the recently constructed "Puff Field Theory," and present arguments in favor of it being a field theory decoupled from gravity. We construct its supergravity dual and calculate the entropy of this theory in the limit of large 't Hooft coupling. We also determine the leading irrelevant operator that governs its deviation from N=4 super Yang-Mills theory.Comment: 31 pages, 1 figur

Holographic Nuclei : Supersymmetric Examples

We provide a dual gravity description of a supersymmetric heavy nucleus, following the idea of our previous paper arXiv:0809.3141. The supersymmetric nucleus consists of a merginal bound state of $A$ baryons distributed over a ball in 3 dimensions. In the gauge/string duality, the baryon in N=4 super Yang-Mills (SYM) theory corresponds to a D5-brane wrapping S^5 of the AdS_5 x S^5 spacetime, so the nucleus corresponds to a collection of $A$ D5-branes. We take a large $A$ and a near horizon limits of a back-reacted geometry generated by the wrapped $A$ D5-branes, where we find a gap in the supergravity fluctuation spectrum. This spectrum is a gravity dual of giant resonances of heavy nuclei, in the supersymmetric toy example of QCD.Comment: 9 pages, 6 figures; v2:a refernce adde

Non-commutative gauge theory on D-branes in Melvin Universes

Non-commutative gauge theory with a non-constant non-commutativity parameter can be formulated as a decoupling limit of open strings ending on D3-branes wrapping a Melvin universe. We construct the action explicitly and discuss various physical features of this theory. The decoupled field theory is not supersymmetric. Nonetheless, the Coulomb branch appears to remain flat at least in the large N and large 't Hooft coupling limit. We also find the analogue of Prasad-Sommerfield monopoles whose size scales with the non-commutativity parameter and is therefore position dependent.Comment: 15 pages, 1 figure, reference adde

Gibbons-Hawking M-branes

We present new M2 and M5-brane solutions in M-theory based on transverse Gibbons-Hawking spaces. These solutions provide realizations of fully localized type IIA D2/D6 and NS5/D6 brane intersections. One novel feature of these solutions is that the metric functions depend on more than two transverse coordinates (unlike all the other previous known solutions). All the solutions have eight preserved supersymmetries and the world-volume theories of the NS5-branes are new non-local, non-gravitational, six dimensional, T-dual little string theories with eight supersymmetries. We discuss the limits in which the dynamics of the D2 and NS5-branes decouple from the bulk for these solutions.Comment: 32 pages, 7 figures, few sentences added, a couple of typos corrected, to appear in JHE

Computing topological invariants with one and two-matrix models

A generalization of the Kontsevich Airy-model allows one to compute the intersection numbers of the moduli space of p-spin curves. These models are deduced from averages of characteristic polynomials over Gaussian ensembles of random matrices in an external matrix source. After use of a duality, and of an appropriate tuning of the source, we obtain in a double scaling limit these intersection numbers as polynomials in p. One can then take the limit p to -1 which yields a matrix model for orbifold Euler characteristics. The generalization to a time-dependent matrix model, which is equivalent to a two-matrix model, may be treated along the same lines ; it also yields a logarithmic potential with additional vertices for general p.Comment: 30 pages, added references, changed conten

M-Theory Giant Gravitons with C field

We find giant graviton configurations of an M5-brane probe in the D=11 supergravity background generated by a stack of non-threshold (M2,M5) bound states. The M5-brane probe shares three directions with the background and wraps a two-sphere transverse to the bound states. For a particular value of the worldvolume gauge field of the PST formalism, there exist solutions of the equations of motion for which the M5-brane probe behaves as a wave propagating in the (M2,M5) background. We have checked that the probe breaks the supersymmetry of the background exactly as a massless particle moving along the trajectory of its center of mass.Comment: 11 pages, LaTeX; v2: references adde

D-brane Bound States from Charged Macroscopic Strings

We construct new D-brane bound states using charged macroscopic type IIB string solutions.A generic bound state solution, when dimensionally reduced, carries multiple gauge charges. Starting with D=9 charged macroscopic strings, we obtain solutions in D=10, which are interpreted as carrying (F, D0, D2) charges as well as nonzero momenta. The masses and charges are also explicitly shown to satisfy the non-threshold bound of 1/2 BPS objects. Our solutions reduce to the known D-brane bound state solutions with appropriate restrictions in the parameter space. We further generalize the results to (Dp- D(p+2)) bound state in IIA/B theories, giving an explicit example with p=1.Comment: 21 pages, latex, few references added: minor modification

Noncritical String Correlators, Finite-N Matrix Models and the Vortex Condensate

We carry out a systematic study of correlation functions of momentum modes in the Euclidean c=1 string, as a function of the radius and to all orders in perturbation theory. We obtain simple explicit expressions for several classes of correlators in terms of special functions. The Normal Matrix Model is found to be a powerful calculational tool that computes c=1 string correlators even at finite N. This enables us to obtain a simple combinatoric formula for the 2n-point function of unit momentum modes, which after T-duality determines the vortex condensate. We comment on possible applications of our results to T-duality at c=1 and to the 2d black hole/vortex condensate problem.Comment: 38 pages, LaTe

Adding flavor to the gravity dual of non-commutative gauge theories

We study the addition of flavor degrees of freedom to the supergravity dual of the non-commutative deformation of the maximally supersymmetric gauge theories. By considering D7 flavor branes in the probe approximation and studying their fluctuations we extract the spectrum of scalar and vector mesons as a function of the non-commutativity. We find that the spectrum for very large non-commutative parameter is equal to the one in the commutative theory, while for some intermediate values of the non-commutativity some of the modes disappear from the discrete spectrum. We also study the semiclassical dynamics of rotating open strings attached to the D7-brane, which correspond to mesons with large spin. Under the effect of the non-commutativity the open strings get tilted. However, at small(large) distances they display the same Regge-like (Coulombic) behaviour as in the commutative theory. We also consider the addition of D5-flavor branes to the non-commutative deformation of the N=1 supersymmetric Maldacena-Nunez background.Comment: 50 pages, 9 figures, LaTeX; v2: minor improvements, references added; v3: typos correcte

Holographic QCD and Pion Mass

To realize massive pions, we study variations of the holographic model of massless QCD using the D4/D8/anti-D8 brane configuration proposed by Sakai and Sugimoto. We propose deformations which break the chiral symmetry explicitly and compute the mass of the pions and vector mesons. The observed value of the pion mass can be obtained. We also argue a chiral perturbation corresponding to our deformation.Comment: 23pages, minor changes, references adde