591 research outputs found
Homotopy transfer and effective field theory I: tree-level
We use the dictionary between general field theories and strongly homotopyalgebras to provide an algebraic formulation of the procedure of integratingout of degrees of freedom in terms of homotopy transfer. This includes moregeneral effective theories in which some massive modes are kept while othermodes of a comparable mass scale are integrated out, as first explored by Senin the context of closed string field theory. We treatL∞-algebras both in termsof a nilpotent coderivation and, on the dual space, in terms of a nilpotentderivation (corresponding to the BRST charge of the field theory) and provideexplicit formulas for homotopy transfer. These are then shown to govern theintegrating out of degrees of freedom at tree level, while the generalization toloop level will be explored in a sequel to this paper
Membrane Sigma-Models and Quantization of Non-Geometric Flux Backgrounds
We develop quantization techniques for describing the nonassociative geometry
probed by closed strings in flat non-geometric R-flux backgrounds M. Starting
from a suitable Courant sigma-model on an open membrane with target space M,
regarded as a topological sector of closed string dynamics in R-space, we
derive a twisted Poisson sigma-model on the boundary of the membrane whose
target space is the cotangent bundle T^*M and whose quasi-Poisson structure
coincides with those previously proposed. We argue that from the membrane
perspective the path integral over multivalued closed string fields in Q-space
is equivalent to integrating over open strings in R-space. The corresponding
boundary correlation functions reproduce Kontsevich's deformation quantization
formula for the twisted Poisson manifolds. For constant R-flux, we derive
closed formulas for the corresponding nonassociative star product and its
associator, and compare them with previous proposals for a 3-product of fields
on R-space. We develop various versions of the Seiberg-Witten map which relate
our nonassociative star products to associative ones and add fluctuations to
the R-flux background. We show that the Kontsevich formula coincides with the
star product obtained by quantizing the dual of a Lie 2-algebra via convolution
in an integrating Lie 2-group associated to the T-dual doubled geometry, and
hence clarify the relation to the twisted convolution products for topological
nonassociative torus bundles. We further demonstrate how our approach leads to
a consistent quantization of Nambu-Poisson 3-brackets.Comment: 52 pages; v2: references adde
Geometry and Dynamics of a Coupled 4D-2D Quantum Field Theory
Geometric and dynamical aspects of a coupled 4D-2D interacting quantum field
theory - the gauged nonAbelian vortex - are investigated. The fluctuations of
the internal 2D nonAbelian vortex zeromodes excite the massless 4D Yang-Mills
modes and in general give rise to divergent energies. This means that the
well-known 2D CP(N-1) zeromodes associated with a nonAbelian vortex become
nonnormalizable. Moreover, all sorts of global, topological 4D effects such as
the nonAbelian Aharonov-Bohm effect come into play. These topological global
features and the dynamical properties associated with the fluctuation of the 2D
vortex moduli modes are intimately correlated, as shown concretely here in a
U(1) x SU(N) x SU(N) model with scalar fields in a bifundamental representation
of the two SU(N) factor gauge groups.Comment: Latex, 39 pages, 5 figure
On "New Massive" 4D Gravity
We construct a four-dimensional (4D) gauge theory that propagates, unitarily,
the five polarization modes of a massive spin-2 particle. These modes are
described by a "dual" graviton gauge potential and the Lagrangian is 4th-order
in derivatives. As the construction mimics that of 3D "new massive gravity", we
call this 4D model (linearized) "new massive dual gravity". We analyse its
massless limit, and discuss similarities to the Eddington-Schroedinger model.Comment: 17 pages, v2 : version published in JHE
Parent formulation at the Lagrangian level
The recently proposed first-order parent formalism at the level of equations
of motion is specialized to the case of Lagrangian systems. It is shown that
for diffeomorphism-invariant theories the parent formulation takes the form of
an AKSZ-type sigma model. The proposed formulation can be also seen as a
Lagrangian version of the BV-BRST extension of the Vasiliev unfolded approach.
We also discuss its possible interpretation as a multidimensional
generalization of the Hamiltonian BFV--BRST formalism. The general construction
is illustrated by examples of (parametrized) mechanics, relativistic particle,
Yang--Mills theory, and gravity.Comment: 26 pages, discussion of the truncation extended, typos corrected,
references adde
Abnormal function of the vasopressin-cyclic-AMP-aquaporin2 axis during urine concentrating and diluting in patients with reduced renal function. A case control study
<p>Abstract</p> <p>Background</p> <p>The kidneys ability to concentrate and dilute urine is deteriorated during progressive renal insufficiency. We wanted to test the hypothesis that these phenomena could be attributed to an abnormal function of the principal cells in the distal part of the nephron.</p> <p>Methods</p> <p>Healthy control subjects and patients with chronic kidney diseases were studied. Group 1 comprised healthy subjects, n = 10. Groups 2-4 comprised patients with chronic kidney disease (Group 2, n = 14, e-GFR ? 90 m1/min; Group 3, n = 11, 60 m1/min ? e-GFR < 90 ml/min; and Group 4, n = 16, 15 ml/min ? e-GFR < 60 ml/min). The subjects collected urine during 24 hours. A urine concentrating test was done by thirsting during the following 12 hours. Thereafter, a urine diluting test was performed with a water load of 20 ml/kg body weight. The effect variables were urinary excretions of aquaporin2 (u-AQP2), cyclic-AMP (u-c-AMP), urine volume (UV), free water clearance (C<sub>H2O</sub>), urine osmolarity (u-Osm), and plasma arginine vasopressin (p-AVP).</p> <p>Results</p> <p>After fluid deprivation, u-Osm increased. In all groups, UV and C<sub>H2O </sub>decreased and u-AQP2 and u-c-AMP increased in Groups 1 and 2, but were unchanged in Group 3 and 4. P-AVP was significantly higher in Group 4 than in the other groups. During urine diluting, UV and C<sub>H2O </sub>reached significantly higher levels in Groups 1-3 than Group 4. Both before and after water loading, u-AQP2 and p-AVP were significantly higher and u-c-AMP was significantly lower in Group 4 than the other groups. Estimated-GFR was correlated negatively to p-AVP and positively to u-c-AMP.</p> <p>Conclusions</p> <p>Patients with moderately severe chronic kidney disease have a reduced renal concentrating and diluting capacity compared to both patients with milder chronic kidney disease and healthy control subjects. These phenomena can be attributed, at least partly, to an abnormally decreased response in the AVP-c-AMP-AQP2 axis.</p> <p>ClinicalTrials.Gov Identifier: NCT00313430</p
First order parent formulation for generic gauge field theories
We show how a generic gauge field theory described by a BRST differential can
systematically be reformulated as a first order parent system whose spacetime
part is determined by the de Rham differential. In the spirit of Vasiliev's
unfolded approach, this is done by extending the original space of fields so as
to include their derivatives as new independent fields together with associated
form fields. Through the inclusion of the antifield dependent part of the BRST
differential, the parent formulation can be used both for on and off-shell
formulations. For diffeomorphism invariant models, the parent formulation can
be reformulated as an AKSZ-type sigma model. Several examples, such as the
relativistic particle, parametrized theories, Yang-Mills theory, general
relativity and the two dimensional sigma model are worked out in details.Comment: 36 pages, additional sections and minor correction
N = 2 supersymmetric sigma-models and duality
For two families of four-dimensional off-shell N = 2 supersymmetric nonlinear
sigma-models constructed originally in projective superspace, we develop their
formulation in terms of N = 1 chiral superfields. Specifically, these theories
are: (i) sigma-models on cotangent bundles T*M of arbitrary real analytic
Kaehler manifolds M; (ii) general superconformal sigma-models described by
weight-one polar supermultiplets. Using superspace techniques, we obtain a
universal expression for the holomorphic symplectic two-form \omega^{(2,0)}
which determines the second supersymmetry transformation and is associated with
the two complex structures of the hyperkaehler space T*M that are complimentary
to the one induced from M. This two-form is shown to coincide with the
canonical holomorphic symplectic structure. In the case (ii), we demonstrate
that \omega^{(2,0)} and the homothetic conformal Killing vector determine the
explicit form of the superconformal transformations. At the heart of our
construction is the duality (generalized Legendre transform) between off-shell
N = 2 supersymmetric nonlinear sigma-models and their on-shell N = 1 chiral
realizations. We finally present the most general N = 2 superconformal
nonlinear sigma-model formulated in terms of N = 1 chiral superfields. The
approach developed can naturally be generalized in order to describe 5D and 6D
superconformal nonlinear sigma-models in 4D N = 1 superspace.Comment: 31 pages, no figures; V2: reference and comments added, typos
corrected; V3: more typos corrected, published versio
Off-Diagonal Deformations of Kerr Metrics and Black Ellipsoids in Heterotic Supergravity
Geometric methods for constructing exact solutions of motion equations with
first order corrections to the heterotic supergravity action
implying a non-trivial Yang-Mills sector and six dimensional, 6-d,
almost-K\"ahler internal spaces are studied. In 10-d spacetimes, general
parametrizations for generic off-diagonal metrics, nonlinear and linear
connections and matter sources, when the equations of motion decouple in very
general forms are considered. This allows us to construct a variety of exact
solutions when the coefficients of fundamental geometric/physical objects
depend on all higher dimensional spacetime coordinates via corresponding
classes of generating and integration functions, generalized effective sources
and integration constants. Such generalized solutions are determined by generic
off-diagonal metrics and nonlinear and/or linear connections. In particular, as
configurations which are warped/compactified to lower dimensions and for
Levi-Civita connections. The corresponding metrics can have (non) Killing
and/or Lie algebra symmetries and/or describe (1+2)-d and/or (1+3)-d domain
wall configurations, with possible warping nearly almost-K\"ahler manifolds,
with gravitational and gauge instantons for nonlinear vacuum configurations and
effective polarizations of cosmological and interaction constants encoding
string gravity effects. A series of examples of exact solutions describing
generic off-diagonal supergravity modifications to black hole/ ellipsoid and
solitonic configurations are provided and analyzed. We prove that it is
possible to reproduce the Kerr and other type black solutions in general
relativity (with certain types of string corrections) in 4-d and to generalize
the solutions to non-vacuum configurations in (super) gravity/ string theories.Comment: latex2e, 44 pages with table of content, v2 accepted to EJPC with
minor typos modifications requested by editor and referee and up-dated
reference
On duality symmetry in perturbative quantum theory
Non-compact symmetries of extended 4d supergravities involve duality
rotations of vectors and thus are not manifest off-shell invariances in
standard "second-order" formulation. To study how such symmetries are realised
in the quantum theory we consider examples in 2 dimensions where vector-vector
duality is replaced by scalar-scalar one. Using a "doubled" formulation, where
fields and their momenta are treated on an equal footing and the duality
becomes a manifest symmetry of the action (at the expense of Lorentz symmetry),
we argue that the corresponding on-shell quantum effective action or S-matrix
are duality symmetric as well as Lorentz invariant. The simplest case of
discrete Z_2 duality corresponds to a symmetry of the S-matrix under flipping
the sign of the negative-chirality scalars in 2 dimensions or phase rotations
of chiral (definite-helicity) parts of vectors in 4 dimensions. We also briefly
discuss some 4d models and comment on implications of our analysis for extended
supergravities.Comment: 21 pages, Latex v2: comments and references added v3: references and
minor comments adde
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