3,027 research outputs found
Toric Duality Is Seiberg Duality
We study four N=1 SU(N)^6 gauge theories, with bi-fundamental chiral matter
and a superpotential. In the infrared, these gauge theories all realize the
low-energy world-volume description of N coincident D3-branes transverse to the
complex cone over a del Pezzo surface dP_3 which is the blowup of P^2 at three
generic points. Therefore, the four gauge theories are expected to fall into
the same universality class--an example of a phenomenon that has been termed
"toric duality." However, little independent evidence has been given that such
theories are infrared-equivalent.
In fact, we show that the four gauge theories are related by the N=1 duality
of Seiberg, vindicating this expectation. We also study holographic aspects of
these gauge theories. In particular we relate the spectrum of chiral operators
in the gauge theories to wrapped D3-brane states in the AdS dual description.
We finally demonstrate that the other known examples of toric duality are
related by N=1 duality, a fact which we conjecture holds generally.Comment: 46 pages, 2 figures, harvma
Perspectives on Pfaffians of Heterotic World-sheet Instantons
To fix the bundle moduli of a heterotic compactification one has to
understand the Pfaffian one-loop prefactor of the classical instanton
contribution. For compactifications on elliptically fibered Calabi-Yau spaces X
this can be made explicit for spectral bundles and world-sheet instantons
supported on rational base curves b: one can express the Pfaffian in a closed
algebraic form as a polynomial, or it may be understood as a theta-function
expression. We elucidate the connection between these two points of view via
the respective perception of the relevant spectral curve, related to its
extrinsic geometry in the ambient space (the elliptic surface in X over b) or
to its intrinsic geometry as abstract Riemann surface. We identify, within a
conceptual description, general vanishing loci of the Pfaffian, and derive
bounds on the vanishing order, relevant to solutions of W=dW=0.Comment: 40 pages; minor changes, discussion section 1.1 adde
Equivariant Symplectic Geometry of Gauge Fixing in Yang-Mills Theory
The Faddeev-Popov gauge fixing in Yang-Mills theory is interpreted as
equivariant localization. It is shown that the Faddeev-Popov procedure amounts
to a construction of a symplectic manifold with a Hamiltonian group action. The
BRST cohomology is shown to be equivalent to the equivariant cohomology based
on this symplectic manifold with Hamiltonian group action. The ghost operator
is interpreted as a (pre)symplectic form and the gauge condition as the moment
map corresponding to the Hamiltonian group action. This results in the
identification of the gauge fixing action as a closed equivariant form, the sum
of an equivariant symplectic form and a certain closed equivariant 4-form which
ensures convergence. An almost complex structure compatible with the symplectic
form is constructed. The equivariant localization principle is used to localize
the path integrals onto the gauge slice. The Gribov problem is also discussed
in the context of equivariant localization principle. As a simple illustration
of the methods developed in the paper, the partition function of N=2
supersymmetric quantum mechanics is calculated by equivariant localizationComment: 46 pages, added remarks, typos and references correcte
The F-Landscape: Dynamically Determining the Multiverse
We evolve our Multiverse Blueprints to characterize our local neighborhood of
the String Landscape and the Multiverse of plausible string, M- and F-theory
vacua. Building upon the tripodal foundations of i) the Flipped SU(5) Grand
Unified Theory (GUT), ii) extra TeV-Scale vector-like multiplets derived out of
F-theory, and iii) the dynamics of No-Scale Supergravity, together dubbed
No-Scale F-SU(5), we demonstrate the existence of a continuous family of
solutions which might adeptly describe the dynamics of distinctive universes.
This Multiverse landscape of F-SU(5) solutions, which we shall refer to as the
F-Landscape, accommodates a subset of universes compatible with the presently
known experimental uncertainties of our own universe. We show that by
secondarily minimizing the minimum of the scalar Higgs potential of each
solution within the F-Landscape, a continuous hypervolume of distinct minimum
minimorum can be engineered which comprise a regional dominion of universes,
with our own universe cast as the bellwether. We conjecture that an
experimental signal at the LHC of the No-Scale F-SU(5) framework's
applicability to our own universe might sensibly be extrapolated as
corroborating evidence for the role of string, M- and F-theory as a master
theory of the Multiverse, with No-Scale supergravity as a crucial and pervasive
reinforcing structure.Comment: 15 Pages, 7 Figures, 1 Tabl
Mutation of L-2,3-diaminopropionic acid synthase genes blocks staphyloferrin B synthesis in Staphylococcus aureus
BACKGROUND: Staphylococcus aureus synthesizes two siderophores, staphyloferrin A and staphyloferrin B, that promote iron-restricted growth. Previous work on the biosynthesis of staphyloferrin B has focused on the role of the synthetase enzymes, encoded from within the sbnA-I operon, which build the siderophore from the precursor molecules citrate, alpha-ketoglutarate and L-2,3-diaminopropionic acid. However, no information yet exists on several other enzymes, expressed from the biosynthetic cluster, that are thought to be involved in the synthesis of the precursors (or synthetase substrates) themselves.
RESULTS: Using mutants carrying insertions in sbnA and sbnB, we show that these two genes are essential for the synthesis of staphyloferrin B, and that supplementation of the growth medium with L-2,3-diaminopropionic acid can bypass the block in staphyloferrin B synthesis displayed by the mutants. Several mechanisms are proposed for how the enzymes SbnA, with similarity to cysteine synthase enzymes, and SbnB, with similarity to amino acid dehydrogenases and ornithine cyclodeaminases, function together in the synthesis of this unusual nonproteinogenic amino acid L-2,3-diaminopropionic acid.
CONCLUSIONS: Mutation of either sbnA or sbnB result in abrogation of synthesis of staphyloferrin B, a siderophore that contributes to iron-restricted growth of S. aureus. The loss of staphyloferrin B synthesis is due to an inability to synthesize the unusual amino acid L-2,3-diaminopropionic acid which is an important, iron-liganding component of the siderophore structure. It is proposed that SbnA and SbnB function together as an L-Dap synthase in the S. aureus cell
Non-Abelian Localization for Supersymmetric Yang-Mills-Chern-Simons Theories on Seifert Manifold
We derive non-Abelian localization formulae for supersymmetric
Yang-Mills-Chern-Simons theory with matters on a Seifert manifold M, which is
the three-dimensional space of a circle bundle over a two-dimensional Riemann
surface \Sigma, by using the cohomological approach introduced by Kallen. We
find that the partition function and the vev of the supersymmetric Wilson loop
reduces to a finite dimensional integral and summation over classical flux
configurations labeled by discrete integers. We also find the partition
function reduces further to just a discrete sum over integers in some cases,
and evaluate the supersymmetric index (Witten index) exactly on S^1x\Sigma. The
index completely agrees with the previous prediction from field theory and
branes. We discuss a vacuum structure of the ABJM theory deduced from the
localization.Comment: 50 pages, 3 figures, typos corrected, references adde
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