Gravity duals of 2d supersymmetric gauge theories

We find new supergravity solutions generated by D5-branes wrapping a four-cycle and preserving four and two supersymmetries. We first consider the configuration in which the fivebranes wrap a four-cycle in a Calabi-Yau threefold, which preserves four supersymmetries and is a gravity dual to the Coulomb branch of two-dimensional gauge theories with N=(2,2) supersymmetry. We also study the case of fivebranes wrapping a co-associative four-cycle in a manifold of G_2-holonomy, which provides a gravity dual of N=(1,1) supersymmetric Yang-Mills theory in two dimensions. We also discuss the addition of unquenched fundamental matter fields to these backgrounds and find the corresponding gravity solutions with flavor brane sources.Comment: 34 pages + appendices; v2: minor improvement

D-brane probes on L^{abc} Superconformal Field Theories

We study supersymmetric embeddings of D-brane probes of different dimensionality in the AdS_5xL^{abc} background of type IIB string theory. In the case of D3-branes, we recover the known three-cycles dual to the dibaryonic operators of the gauge theory and we also find a new family of supersymmetric embeddings. Supersymmetric configurations of D5-branes, representing fractional branes, and of spacetime filling D7-branes (which can be used to add flavor) are also found. Stable non supersymmetric configurations corresponding to fat strings and domain walls are found as well.Comment: 20 pages, LaTeX;v2: minor improvements, references adde

Mesons in marginally deformed AdS/CFT

We study the embedding of spacetime filling D7-branes in beta-deformed backgrounds which, according to the AdS/CFT dictionary, corresponds to flavoring beta-deformed N=4 super Yang-Mills. We consider supersymmetric and more general non-supersymmetric three parameter deformations. The equations of motion for quadratic fluctuations of a probe D7-brane wrapped on a deformed three-sphere exhibit a non-trivial coupling between scalar and vector modes induced by the deformation. Nevertheless, we manage to solve them analytically and find that the mesonic mass spectrum is discrete, with a mass gap and a Zeeman-like splitting occurs. Finally we propose the action for the dual field theory as obtained by star-product deformation of super Yang-Mills with fundamental matter.Comment: LaTex, 42 pages, 3 figures, uses JHEP

On the geometry of string duals with backreacting flavors

Making use of generalized calibrated geometry and G-structures we put the problem of finding string-duals with smeared backreacting flavor branes in a more mathematical setting. This more formal treatment of the problem allows us to easily smear branes without good coordinate representations, establish constraints on the smearing form and identify a topological central charge in the SUSY algebra. After exhibiting our methods for a series of well known examples, we apply them to the problem of flavoring a supergravity-dual to a d=2+1 dimensional N=2 super Yang-Mills-like theory. We find new solutions to both the flavored and unflavored systems. Interpretating these turns out to be difficult.Comment: 38 pages - Typos corrected and references added - As published in JHE

Calibrated Surfaces and Supersymmetric Wilson Loops

We study the dual gravity description of supersymmetric Wilson loops whose expectation value is unity. They are described by calibrated surfaces that end on the boundary of anti de-Sitter space and are pseudo-holomorphic with respect to an almost complex structure on an eight-dimensional slice of AdS_5 x S^5. The regularized area of these surfaces vanishes, in agreement with field theory non-renormalization theorems for the corresponding operators.Comment: 28 pages, 2 figure

Holographic duals of SQCD models in low dimensions

We obtain gravity duals to supersymmetric gauge theories in two and three spacetime dimensions with unquenched flavor. The supergravity solutions are generated by a set of color branes wrapping a compact cycle in a Calabi-Yau threefold, together with another set of flavor branes extended along the directions orthogonal to the cycle wrapped by the color branes. We construct supergravity backgrounds which include the backreaction induced by a smeared set of flavor branes, which act as delocalized dynamical sources of the different supergravity fields.Comment: 42 pages, 5 figures;v2: typos correcte

Open string modes at brane intersections

We study systematically the open string modes of a general class of BPS intersections of branes. We work in the approximation in which one of the branes is considered as a probe embedded in the near-horizon geometry generated by the other type of branes. We mostly concentrate on the D3-D5 and D3-D3 intersections, which are dual to defect theories with a massive hypermultiplet confined to the defect. In these cases we are able to obtain analytical expressions for the fluctuation modes of the probe and to compute the corresponding mass spectra of the dual operators in closed form. Other BPS intersections are also studied and their fluctuation modes and spectra are found numerically.Comment: 58 pages, 3 figures, LaTeX;v2: typos correcte

Long-term ecological research of aquatic ecosystem at Guadalquivir estuary (1997-2014): community structure and food web

A long term ecological research program (LTER) is developed monthly at the Guadalquivir estuary since 1997. Inter- and intra-specific euryhalinity differences both in prey and predators seem to determine spatial species distribution at this important nursery area: the less euryhaline species (marine recruits) tends to occur at physiologically more favourable salinities (lower osmotic stress and mortality risk); whereas most euryhaline species (estuarine species) occurred at ecologically more favourable salinities (lower inter-specific competition and predation). Likewise, inter-specific differences in spawning periods cause certain temporal segregation of those marine recruits using the estuary. High spatiotemporal coincidence of prey (mainly mysids and copepods) density peaks with that of their predators suggests food availability as a key factor in the estuarine nursery function. According to their distribution, the estuarine stretch situated seaward from the 5 isohaline position is mainly used as a nursery ground, principally during warm period (T > 15 °C). Thus, human management of the freshwater input to the estuary (from a 110 km upstream dam) modifies the nursery ground extent due to seaward/upstream displacements of the estuarine salinity gradient. During droughts, this freshwater control may also lead to a partial loss of the estuarine nursery function due to a decrease of prey availability linked to extremely high-turbidity events

On the M-theory description of supersymmetric gluodynamics

We study the stringy description of N=1 supersymmetric SU(N) gauge theory on R^{1,2} X S^1. Our description is based on the known Klebanov-Strassler and Maldacena-Nunez solutions, properly modified to account for the compact dimension. The presence of this circle turns out to be a non trivial modification and it leads us to consider the up-lifted eleven dimensional solution. We discuss some of its properties. Perhaps the most interesting one is that extra BPS M-branes are present. These generate a non-perturbative superpotential that we explicitly compute. Our findings, besides their interest in the gauge-string correspondence, may also have applications in the cosmological KKLT and KKLMMT scenarios.Comment: 24 pages; typos corrected and references adde

Supersymmetric defects in the Maldacena-Nunez background

We find supersymmmetric configurations of a D5-brane probe in the Maldacena-Nunez background which are extended along one or two of the spatial directions of the gauge theory. These embeddings are worldvolume solitons which behave as codimension two or one defects in the gauge theory and preserve two of the four supersymmetries of the background.Comment: 37 pages, 2 figures, LaTeX; v2: references adde