23 research outputs found
On the Poisson-Lie T-plurality of boundary conditions
Conditions for the gluing matrix defining consistent boundary conditions of
two-dimensional nonlinear sigma-models are analyzed and reformulated.
Transformation properties of the right-invariant fields under Poisson-Lie
T-plurality are used to derive a formula for the transformation of the boundary
conditions. Examples of transformation of D-branes in two and three dimensions
are presented. We investigate obstacles arising in this procedure and propose
possible solutions.Comment: 25 pages, LaTeX; major revision, discussion of boundary fields added;
author's version of the published pape
N=1 supersymmetric sigma model with boundaries, I
We study an N=1 two-dimensional non-linear sigma model with boundaries
representing, e.g., a gauge fixed open string. We describe the full set of
boundary conditions compatible with N=1 superconformal symmetry. The problem is
analyzed in two different ways: by studying requirements for invariance of the
action, and by studying the conserved supercurrent. We present the target space
interpretation of these results, and identify the appearance of partially
integrable almost product structures.Comment: 24 pages, LaTeX. v2: minor clarification in section 3.2, reference
added. v3: section added on N=2 supersymmetry. v4: typos corrected, published
versio
E8 Quiver Gauge Theory and Mirror Symmetry
We show that the Higgs branch of a four-dimensional Yang-Mills theory, with
gauge and matter content summarised by an E_8 quiver diagram, is identical to
the generalised Coulomb branch of a four-dimensional superconformal strongly
coupled gauge theory with E_8 global symmetry. This is the final step in
showing that there is a Higgs-Coulomb identity of this kind for each of the
cases {0}, A_1, A_2, D_4, E_6, E_7 and E_8. This series of equivalences
suggests the existence of a mirror symmetry between the quiver theories and the
strongly coupled theories. We also discuss how to interpret the parameters of
the quiver gauge theory in terms of the Hanany-Witten picture.Comment: 19 pages, 3 figures, references adde
Worldsheet boundary conditions in Poisson-Lie T-duality
We apply canonical Poisson-Lie T-duality transformations to bosonic open
string worldsheet boundary conditions, showing that the form of these
conditions is invariant at the classical level, and therefore they are
compatible with Poisson-Lie T-duality. In particular the conditions for
conformal invariance are automatically preserved, rendering also the dual model
conformal. The boundary conditions are defined in terms of a gluing matrix
which encodes the properties of D-branes, and we derive the duality map for
this matrix. We demonstrate explicitly the implications of this map for
D-branes in two non-Abelian Drinfel'd doubles.Comment: 20 pages, Latex; v2: typos and wording corrected, references added;
v3: three-dimensional example added, reference added, discussion clarified,
published versio
D-branes and doubled geometry
We define the open string version of the nonlinear sigma model on doubled geometry introduced by Hull and Reid-Edwards, and derive its boundary conditions. These conditions include the restriction of D-branes to maximally isotropic submanifolds as well as a compatibility condition with the Lie algebra structure on the doubled space. We demonstrate a systematic method to derive and classify D-branes from the boundary conditions, in terms of embeddings both in the doubled geometry and in the physical target space. We apply it to the doubled three-torus with constant H-flux and find D0-, D1-, and D2-branes, which we verify transform consistently under T-dualities mapping the system to f-, Q- and R-flux backgrounds
T-duality for the sigma model with boundaries
We derive the most general local boundary conditions necessary for T-duality
to be compatible with superconformal invariance of the two-dimensional N=1
supersymmetric nonlinear sigma model with boundaries. To this end, we construct
a consistent gauge invariant parent action by gauging a U(1) isometry, with and
without boundary interactions. We investigate the behaviour of the boundary
conditions under T-duality, and interpret the results in terms of D-branes.Comment: 48 pages, LaTeX, v2: typos corrected, references adde
A Genome-Wide Pharmacogenetic Study of Growth Hormone Responsiveness
Individual patients vary in their response to growth hormone (GH). No large-scale genome-wide studies have looked for genetic predictors of GH responsiveness. To identify genetic variants associated with GH responsiveness. Genome-wide association study (GWAS). Cohorts from multiple academic centers and a clinical trial. A total of 614 individuals from 5 short stature cohorts receiving GH: 297 with idiopathic short stature, 276 with isolated GH deficiency, and 65 born small for gestational age. Association of more than 2 million variants was tested. Primary analysis: individual single nucleotide polymorphism (SNP) association with first-year change in height standard deviation scores. Secondary analyses: SNP associations in clinical subgroups adjusted for clinical variables; association of polygenic score calculated from 697 genome-wide significant height SNPs with GH responsiveness. No common variant associations reached genome-wide significance in the primary analysis. The strongest suggestive signals were found near the B4GALT4 and TBCE genes. After meta-analysis including replication data, signals at several loci reached or retained genome-wide significance in secondary analyses, including variants near ST3GAL6. There was no significant association with variants previously reported to be associated with GH response nor with a polygenic predicted height score. We performed the largest GWAS of GH responsiveness to date. We identified 2 loci with a suggestive effect on GH responsiveness in our primary analysis and several genome-wide significant associations in secondary analyses that require further replication. Our results are consistent with a polygenic component to GH responsiveness, likely distinct from the genetic regulators of adult height
Double Field Theory for Double D-branes
We consider Hull's doubled formalism for open strings on D-branes in flat
space and construct the corresponding effective double field theory. We show
that the worldsheet boundary conditions of the doubled formalism describe in a
unified way a T-dual pair of D-branes, which we call double D-branes. We
evaluate the one-loop beta function for the boundary gauge coupling and then
obtain the effective field theory for the double D-branes. The effective field
theory is described by a DBI action of double fields. The T-duality covariant
form of this DBI action is thus a kind of "master" action, which describes all
the double D-brane configurations related by T-duality transformations. We
discuss a number of aspects of this effective theory.Comment: Latex, 1+33 pages. v2 with minor corrections, a new reference added.
v3 a typo correcte