1,283 research outputs found
ABJM Dibaryon Spectroscopy
We extend the proposal for a detailed map between wrapped D-branes in Anti-de
Sitter space and baryon-like operators in the associated dual conformal field
theory provided in hep-th/0202150 to the recently formulated AdS_4 \times
CP^3/ABJM correspondence. In this example, the role of the dibaryon operator of
the 3-dimensional CFT is played by a D4-brane wrapping a CP^2 \subset CP^3.
This topologically stable D-brane in the AdS_4 \times CP^3 is nothing but
one-half of the maximal giant graviton on CP^3.Comment: 26 page
From counting to construction of BPS states in N=4 SYM
We describe a universal element in the group algebra of symmetric groups,
whose characters provides the counting of quarter and eighth BPS states at weak
coupling in N=4 SYM, refined according to representations of the global
symmetry group. A related projector acting on the Hilbert space of the free
theory is used to construct the matrix of two-point functions of the states
annihilated by the one-loop dilatation operator, at finite N or in the large N
limit. The matrix is given simply in terms of Clebsch-Gordan coefficients of
symmetric groups and dimensions of U(N) representations. It is expected, by
non-renormalization theorems, to contain observables at strong coupling. Using
the stringy exclusion principle, we interpret a class of its eigenvalues and
eigenvectors in terms of giant gravitons. We also give a formula for the action
of the one-loop dilatation operator on the orthogonal basis of the free theory,
which is manifestly covariant under the global symmetry.Comment: 41 pages + Appendices, 4 figures; v2 - refs and acknowledgments adde
Flavour singlets in gauge theory as permutations
50 pages, v2: typos corrected, v3: to appear in JHEPJHEP is an open-access journal funded by SCOAP3 and licensed under CC BY 4.
Gauge invariant perturbation theory and non-critical string models of Yang-Mills theories
We carry out a gauge invariant analysis of certain perturbations of
-branes solutions of low energy string theories. We get generically a
system of second order coupled differential equations, and show that only in
very particular cases it is possible to reduce it to just one differential
equation. Later, we apply it to a multi-parameter, generically singular family
of constant dilaton solutions of non-critical string theories in
dimensions, a generalization of that recently found in arXiv:0709.0471[hep-th].
According to arguments coming from the holographic gauge theory-gravity
correspondence, and at least in some region of the parameters space, we obtain
glue-ball spectra of Yang-Mills theories in diverse dimensions, putting special
emphasis in the scalar metric perturbations not considered previously in the
literature in the non critical setup. We compare our numerical results to those
studied previously and to lattice results, finding qualitative and in some
cases, tuning properly the parameters, quantitative agreement. These results
seem to show some kind of universality of the models, as well as an irrelevance
of the singular character of the solutions. We also develop the analysis for
the T-dual, non trivial dilaton family of solutions, showing perfect agreement
between them.Comment: A new reference added
The transcriptional response of Caenorhabditis elegans to ivermectin exposure identifies novel genes involved in the response to reduced food intake
We have examined the transcriptional response of Caenorhabditis elegans following exposure to the anthelmintic drug ivermectin (IVM) using whole genome microarrays and real-time QPCR. Our original aim was to identify candidate molecules involved in IVM metabolism and/or excretion. For this reason the IVM tolerant strain, DA1316, was used to minimise transcriptomic changes related to the phenotype of drug exposure. However, unlike equivalent work with benzimidazole drugs, very few of the induced genes were members of xenobiotic metabolising enzyme families. Instead, the transcriptional response was dominated by genes associated with fat mobilization and fatty acid metabolism including catalase, esterase, and fatty acid CoA synthetase genes. This is consistent with the reduction in pharyngeal pumping, and consequential reduction in food intake, upon exposure of DA1316 worms to IVM. Genes with the highest fold change in response to IVM exposure, cyp-37B1, mtl-1 and scl-2, were comparably up-regulated in response to shortβterm food withdrawal (4 hr) independent of IVM exposure, and GFP reporter constructs confirm their expression in tissues associated with fat storage (intestine and hypodermis). These experiments have serendipitously identified novel genes involved in an early response of C. elegans to reduced food intake and may provide insight into similar processes in higher organisms
Conservation laws and tachyon potentials in the sliver frame
Conservation laws have provided an elegant and efficient tool to evaluate the
open string field theory interaction vertex, they have been originally
implemented in the case where the string field is expanded in the Virasoro
basis. In this work we derive conservation laws in the case where the string
field is expanded in the so-called sliver -basis. As an
application of these conservation laws derived in the sliver frame, we compute
the open string field action relevant to the tachyon condensation and in order
to present not only an illustration but also an additional information, we
evaluate the action without imposing a gauge choice.Comment: 26 pages, some typos fixed, comments added, references adde
Noradrenergic Control of Gene Expression and Long-Term Neuronal Adaptation Evoked by Learned Vocalizations in Songbirds
Norepinephrine (NE) is thought to play important roles in the consolidation and retrieval of long-term memories, but its role in the processing and memorization of complex acoustic signals used for vocal communication has yet to be determined. We have used a combination of gene expression analysis, electrophysiological recordings and pharmacological manipulations in zebra finches to examine the role of noradrenergic transmission in the brainβs response to birdsong, a learned vocal behavior that shares important features with human speech. We show that noradrenergic transmission is required for both the expression of activity-dependent genes and the long-term maintenance of stimulus-specific electrophysiological adaptation that are induced in central auditory neurons by stimulation with birdsong. Specifically, we show that the caudomedial nidopallium (NCM), an area directly involved in the auditory processing and memorization of birdsong, receives strong noradrenergic innervation. Song-responsive neurons in this area express Ξ±-adrenergic receptors and are in close proximity to noradrenergic terminals. We further show that local Ξ±-adrenergic antagonism interferes with song-induced gene expression, without affecting spontaneous or evoked electrophysiological activity, thus dissociating the molecular and electrophysiological responses to song. Moreover, Ξ±-adrenergic antagonism disrupts the maintenance but not the acquisition of the adapted physiological state. We suggest that the noradrenergic system regulates long-term changes in song-responsive neurons by modulating the gene expression response that is associated with the electrophysiological activation triggered by song. We also suggest that this mechanism may be an important contributor to long-term auditory memories of learned vocalizations
Giant Graviton Oscillators
We study the action of the dilatation operator on restricted Schur
polynomials labeled by Young diagrams with p long columns or p long rows. A new
version of Schur-Weyl duality provides a powerful approach to the computation
and manipulation of the symmetric group operators appearing in the restricted
Schur polynomials. Using this new technology, we are able to evaluate the
action of the one loop dilatation operator. The result has a direct and natural
connection to the Gauss Law constraint for branes with a compact world volume.
We find considerable evidence that the dilatation operator reduces to a
decoupled set of harmonic oscillators. This strongly suggests that
integrability in N=4 super Yang-Mills theory is not just a feature of the
planar limit, but extends to other large N but non-planar limits.Comment: 72 page
Lessons from giant gravitons on
We implement Mikhailov's holomorphic curve construction to explore various
properties of giant gravitons in type IIB string theory on . By coloring the D-brane worldvolume, we are able to show how, in the
string theory, the giant graviton factorizes at its maximal size into two
dibaryons - topologically stable D-branes wrapping non-contractible cycles in
the . This is related to the structure of the symmetry group of the
emergent Klebanov-Witten gauge theory being a product -
instead of the canonical . Finally, we complete this study with a
systematic and detailed construction of the spectrum of small fluctuations
about the giant graviton configuration. Curiously, we find that the fluctuation
spectrum depends on the size of the giant. The similarity of the operator
structures in the Klebanov-Witten and ABJM theories leads us to believe that
the D4-brane giant graviton in type IIA string theory on factorizes into two dibaryons in a
qualitatively similar way.Comment: 39 pages; abstract reworded slightly; additional comments included in
subsection 3.3; section 5 revised with the addition of subsection 5.3; added
reference
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