51 research outputs found
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
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