2,259 research outputs found
Stringy Instantons in SU(N) N=2 Non-Conformal Gauge Theories
In this paper we explicitly obtain the leading corrections to the SU(N) N=2
prepotential due to stringy instantons both in flat space-time and in the
presence of a non-trivial graviphoton background field. We show that the
stringy corrections to the prepotential are expressible in terms of the
elementary symmetric polynomials. For N>2 the theory is not conformal; we
discuss the introduction of an explicit dependence on the string scale \alpha'
in the low-energy effective action through the stringy non-perturbative sector.Comment: 22 pages, 1 figur
GLSMs for non-Kahler Geometries
We identify a simple mechanism by which H-flux satisfying the modified
Bianchi identity arises in garden-variety (0,2) gauged linear sigma models.
Taking suitable limits leads to effective gauged linear sigma models with
Green-Schwarz anomaly cancellation. We test the quantum-consistency of a class
of such effective theories by constructing an off-shell superconformal algebra,
providing evidence that these models run to good CFTs in the deep IR.Comment: 37 pages, Minor updates for v
Positive tension 3-branes in an bulk
In this work, we review and extend the so-called consistency conditions for
the existence of a braneworld scenario in arbitrary dimensions in the
Brans-Dicke (BD) gravitational theory. After that, we consider the particular
case of a five-dimensional scenario which seems to have phenomenological
interesting implications. We show that, in the BD framework, it is possible to
achieve necessary conditions pointing to the possibility of accommodating
branes with positive tensions in an AdS bulk by the presence of the additional
BD scalar field, avoiding in this way the necessity of including unstable
objects in the compactification scheme. Furthermore, in the context of time
variable brane tension, it is shown that the brane tension may change its sign,
following the bulk cosmological constant sign.Comment: 15 pages, new version to appear in JHE
The hidden burden of adult allergic rhinitis : UK healthcare resource utilisation survey
Funding Funding for this survey was provided by Meda Pharma.Peer reviewedPublisher PD
Charge Lattices and Consistency of 6D Supergravity
We extend the known consistency conditions on the low-energy theory of
six-dimensional N = 1 supergravity. We review some facts about the theory of
two-form gauge fields and conclude that the charge lattice Gamma for such a
theory has to be self-dual. The Green-Schwarz anomaly cancellation conditions
in the supergravity theory determine a sublattice of Gamma. The condition that
this sublattice can be extended to a self-dual lattice Gamma leads to a strong
constraint on theories that otherwise appear to be self-consistent.Comment: 15 pages. v2: minor changes; references, additional example added;
v3: minor corrections and clarifications added, JHEP versio
Stringy instanton corrections to N=2 gauge couplings
We discuss a string model where a conformal four-dimensional N=2 gauge theory
receives corrections to its gauge kinetic functions from "stringy" instantons.
These contributions are explicitly evaluated by exploiting the localization
properties of the integral over the stringy instanton moduli space. The model
we consider corresponds to a setup with D7/D3-branes in type I' theory
compactified on T4/Z2 x T2, and possesses a perturbatively computable heterotic
dual. In the heteoric side the corrections to the quadratic gauge couplings are
provided by a 1-loop threshold computation and, under the duality map, match
precisely the first few stringy instanton effects in the type I' setup. This
agreement represents a very non-trivial test of our approach to the exotic
instanton calculus.Comment: 63 pages, 5 figures. V2: final version with minor corrections
published on JHEP05(2010)10
Time preferences and risk aversion: tests on domain differences
The design and evaluation of environmental policy requires the incorporation of time and risk elements as many environmental outcomes extend over long time periods and involve a large degree of uncertainty. Understanding how individuals discount and evaluate risks with respect to environmental outcomes is a prime component in designing effective environmental policy to address issues of environmental sustainability, such as climate change. Our objective in this study is to investigate whether subjects' time preferences and risk aversion across the monetary domain and the environmental domain differ. Crucially, our experimental design is incentivized: in the monetary domain, time preferences and risk aversion are elicited with real monetary payoffs, whereas in the environmental domain, we elicit time preferences and risk aversion using real (bee-friendly) plants. We find that subjects' time preferences are not significantly different across the monetary and environmental domains. In contrast, subjects' risk aversion is significantly different across the two domains. More specifically, subjects (men and women) exhibit a higher degree of risk aversion in the environmental domain relative to the monetary domain. Finally, we corroborate earlier results, which document that women are more risk averse than men in the monetary domain. We show this finding to, also, hold in the environmental domain
Non-perturbative gauge/gravity correspondence in N=2 theories
We derive the exact supergravity profile for the twisted scalar field emitted
by a system of fractional D3 branes at a Z2 orbifold singularity supporting N=2
quiver gauge theories with unitary groups and bifundamental matter. At the
perturbative level this twisted field is "dual" to the gauge coupling but it is
corrected non-perturbatively by an infinite tower of fractional D-instantons.
The explicit microscopic description allows to derive the gravity profile from
disk amplitudes computing the emission rate of the twisted scalar field in
terms of chiral correlators in the dual gauge theory. We compute these quantum
correlators using multi-instanton localization techniques and/or Seiberg-Witten
analysis. Finally, we discuss a non-perturbative relation between the twisted
scalar and the effective coupling of the gauge theory for some simple choices
of the brane set ups.Comment: 42 pages. 3 figures, PDFLaTe
Static Charges in the Low-Energy Theory of the S-Duality Twist
We continue the study of the low-energy limit of N=4 super Yang-Mills theory
compactified on a circle with S-duality and R-symmetry twists that preserve N=6
supersymmetry in 2+1D. We introduce external static supersymmetric quark and
anti-quark sources into the theory and calculate the Witten Index of the
resulting Hilbert space of ground states on a torus. Using these results we
compute the action of simple Wilson loops on the Hilbert space of ground states
without sources. In some cases we find disagreement between our results for the
Wilson loop eigenvalues and previous conjectures about a connection with
Chern-Simons theory.Comment: 73 pages, two paragraphs added, one to the introduction and one to
the discussio
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