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48 results for Ward identities

Derives stress-energy identities in Liouville theory on compact surfaces.

problem Stress-energy tensor correlation functions on compact Riemann surfaces.
method Varying correlation functions with respect to background metric, treating different types of variations separately.
result Stress-energy correlation functions expressed as differential operators acting on primary field correlation functions.

Simplified geometric derivation of quantum A-polynomials for knots.

problem Deriving quantum A-polynomials for knots in a simple geometric way.
method Geometric derivation using Ward identities in Chern-Simons theory, contact geometry, and Kauffman calculus.
result Simplified presentation of quantum A-polynomials, making them accessible to a broader audience.

The Ward equation, also called the modified 2+1 chiral model, is obtained by a dimension reduction and a gauge fixing from the self-dual Yang-Mills field equation on R2,2R^{2,2}. It has a Lax pair and is an integrable system. Ward constructed solitons whose extended solutions have distinct simple poles. He also used a li…

2004-05-19abs ↗pdf ↗

Conditions for Penrose-Ward transformation on specific manifolds.

problem Conditions for Penrose-Ward transformation on almost G2G_2-manifolds with almost twistorial structures.
method Necessary and sufficient conditions derived through Penrose-Ward transformation.
result Conditions for Penrose-Ward transformation on almost G2G_2-manifolds with almost twistorial structures.

The moduli space of static finite energy solutions to Ward's integrable chiral model is the space MNM_N of based rational maps from $\CP^1$ to itself with degree NN. The Lagrangian of Ward's model gives rise to a Kähler metric and a magnetic vector potential on this space. However, the magnetic field strength vanishes…

2004-11-05abs ↗pdf ↗

Using the `Riemann Problem with zeros' method, Ward has constructed exact solutions to a (2+1)-dimensional integrable Chiral Model, which exhibit solitons with nontrivial scattering. We give a correspondence between what we conjecture to be all pure soliton solutions and certain holomorphic vector bundles on a compact …

1997-07-14abs ↗pdf ↗

We show that, in quaternionic geometry, the Ward transform is a manifestation of the functoriality of the basic correspondence between the ρρ-quaternionic manifolds and their twistor spaces. We apply this fact, together with the Penrose transform, to obtain existence results for hypercomplex manifolds and for harmonic…

2015-02-23abs ↗pdf ↗

The space-time monopole equation is obtained from a dimension reduction of the anti-self dual Yang-Mills equation on R2,2\R^{2,2}. A family of Ward equations is obtained by gauge fixing from the monopole equation. In this paper, we give an introduction and a survey of the space-time monopole equation. Included are altern…

2006-02-27abs ↗pdf ↗

In the first part of this paper we provide a short introduction to the AdS/CFT correspondence and to holographic renormalization. We discuss how QFT correlation functions, Ward identities and anomalies are encoded in the bulk geometry. In the second part we develop a Hamiltonian approach to the method of holographic re…

2004-04-23abs ↗pdf ↗

The Kac-Ward formula allows to compute the Ising partition function on a planar graph G with straight edges from the determinant of a matrix of size 2N, where N denotes the number of edges of G. In this paper, we extend this formula to any finite graph: the partition function can be written as an alternating sum of the…

2010-04-19abs ↗pdf ↗

We use the compactified twistor correspondence for the (2+1)-dimensional integrable chiral model to prove a conjecture of Ward. In particular, we construct the correspondence space of a compactified twistor fibration and use it to prove that the second Chern numbers of the holomorphic vector bundles, corresponding to t…

2015-04-23abs ↗pdf ↗

We formulate a 4-dimensional higher gauge theoretic Chern-Simons theory. Its symmetry is encoded in a semistrict Lie 2-algebra equipped with an invariant non singular bilinear form. We analyze the gauge invariance of the theory and show that action is invariant under a higher gauge transformation up to a higher winding…

2014-06-09abs ↗pdf ↗

Improves hierarchical clustering in Euclidean space using autoencoders.

problem Lack of unsupervised methods for learning hierarchical structure in Euclidean space.
method Variational autoencoder with Gaussian mixture prior, rescaling latent space, and Ward's linkage.
result Improved dendrogram purity and Moseley-Wang cost function results.

We present a proxy dataset of vital signs with class labels indicating patient transitions from the ward to intensive care units called Ward2ICU. Patient privacy is protected using a Wasserstein Generative Adversarial Network to implicitly learn an approximation of the data distribution, allowing us to sample synthetic…

2019-10-02abs ↗pdf ↗

We introduce and study the Wilson loops in a general 3D topological field theories (TFTs), and show that the expectation value of Wilson loops also gives knot invariants as in Chern-Simons theory. We study the TFTs within the Batalin-Vilkovisky (BV) and Alexandrov-Kontsevich-Schwarz-Zaboronsky (AKSZ) framework, and the…

2010-06-07abs ↗pdf ↗

New framework estimates staged tree models using hierarchical clustering on the probability simplex.

problem Estimating staged tree models with context-specific dependencies.
method Hierarchical clustering on the probability simplex, using simplex-based divergences and linkage methods.
result Total Variation divergence with Ward.D2 linkage produces staged trees with better model fit, structure recovery, and computational efficiency.

We study the 2k2k-Hitchin equations introduced by Ward \cite{Ward 2} from the geometric viewpoint of Higgs bundles. After an introduction on Higgs bundles and 2k2k-Hitchin's equations, we review some elementary facts on complex geometry and Yang-Mills theory. Then we study some properties of holomorphic vector bundles …

2019-11-29abs ↗pdf ↗

The Kac-Ward formula allows to compute the Ising partition function on any finite graph G from the determinant of 2^{2g} matrices, where g is the genus of a surface in which G embeds. We show that in the case of isoradially embedded graphs with critical weights, these determinants have quite remarkable properties. Firs…

2011-01-28abs ↗pdf ↗

Geometric method captures rare topics and temporal alignment in co-author networks.

problem Missing rare topics and smooth temporal alignment in topic modeling.
method Integrates multimodal text and co-author network data using Hellinger distances and Ward's linkage.
result Effective identification of rare topics and visualization of topic drift over time.

The paper defines ASD connections and constructs families over a 5D Heisenberg group.

problem Defining and constructing ASD connections over a 5D Heisenberg group.
method Geometric approach using twistor spaces and Atiyah-Ward ansätz.
result Construction of families of ASD connections and their relation to vector bundles.

Study on type-D metrics aligned with Einstein-Maxwell equations, deriving solutions.

problem Understanding metrics with specific Weyl tensor types and their properties.
method Reinterpretation of Araneda's results using Toda field equation and application of Ward's method.
result Metrics can be expressed using solutions of the SU()SU(\infty)-Toda field equation and axisymmetric solutions of the Laplacian.

We review the twistorial structures by providing a setting under which the corresponding (differential) geometry can be described, by involving the ρρ-connections. This applies, for example, to give new proofs of the existence of the relevant connections for the projective and the quaternionic geometries. Along the wa…

2016-12-22abs ↗pdf ↗

We show that a twistor construction of Hitchin and Ward can be adapted to study unitons (harmonic spheres in a unitary group). Specifically, we show that unitons are equivalent to holomorphic bundles with extra structure over a rational ruled surface with energy given by Chern class. This equivalence allows us to confi…

1995-08-23abs ↗pdf ↗

Wilson-loop averages in Chern-Simons theory (HOMFLY polynomials) can be evaluated in different ways -- the most difficult, but most interesting of them is the hypercube calculus, the only one applicable to virtual knots and used also for categorification (higher-dimensional extension) of the theory. We continue the stu…

2015-06-24abs ↗pdf ↗

We establish a Penrose-Ward transform yielding a bijection between holomorphic principal 2-bundles over a twistor space and non-Abelian self-dual tensor fields on six-dimensional flat space-time. Extending the twistor space to supertwistor space, we derive sets of manifestly N=(1,0) and N=(2,0) supersymmetric non-Abeli…

2012-05-14abs ↗pdf ↗

Our approach to define monopoles is twistorial and we start by developing the twistor theory of R^5, which is an analogue of the twistor theory for R^3 developed by Hitchin. Using this, we describe a Hitchin-Ward transform for R^5, that gives monopoles. In order for us to construct monopoles we make use of spectral cur…

2016-10-03abs ↗pdf ↗

The Lax formulation of the hyper-Hermiticity condition in four dimensions is used to derive a potential that generalises Plebanski's second heavenly equation for hyper-Kahler 4-manifolds. A class of examples of hyper-Hermitian metrics which depend on two arbitrary functions of two complex variables is given. The twisto…

1998-08-31abs ↗pdf ↗

I show that solutions of the SU(infinity) Toda field equation generating a fixed Einstein-Weyl space are governed by a linear equation on the Einstein-Weyl space. From this, obstructions to the existence of Toda solutions generating a given Einstein-Weyl space are found. I also give a classification of Einstein-Weyl sp…

1999-08-30abs ↗pdf ↗

Let l be a link of d components. For every finite-index lattice in Z^d there is an associated finite abelian cover of S^3 branched over l. We show that the order of the torsion subgroup of the first homology of these covers has exponential growth rate equal to the logarithmic Mahler measure of the Alexander polynomial …

2000-03-21abs ↗pdf ↗

We construct a Teichmueller curve uniformized by the Fuchsian triangle group (m,n,\infty) for every m<n. Our construction includes the Teichmueller curves constructed by Veech and Ward as special cases. The construction essentially relies on properties of hypergeometric differential operators. For small m, we find Bill…

2005-11-30abs ↗pdf ↗

Paper addresses limitations of traditional hierarchical clustering methods.

problem Traditional hierarchical clustering methods face limitations in binary trees and ultrametrics.
method Introduces the notion of a valid hierarchy and a two-step algorithm to construct a binary tree and prune it to enforce validity.
result Proposes a method to recover the finest valid hierarchy, which is not constrained to binary structures.

The two-sphere valued wave map flow on a Lorentzian domain R x Sigma, where Sigma is any flat two-torus, is studied. The Cauchy problem with initial data tangent to the moduli space of holomorphic maps Sigma -> S^2 is considered, in the limit of small initial velocity. It is proved that wave maps, in this limit, conver…

2012-07-18abs ↗pdf ↗

Machine learning improves early detection of patient deterioration in Brazilian hospitals.

problem Challenges in recognizing clinical deterioration in hospital settings.
method Application of machine learning to analyze EHR data from multiple hospitals.
result Machine learning models outperformed traditional protocols by 25 percentage points in AUC.

In recent years, a rapidly growing literature has focussed on the construction of wavelet systems to analyze functions defined on the sphere. Our purpose in this paper is to generalize these constructions to situations where sections of line bundles, rather than ordinary scalar-valued functions, are considered. In part…

2008-11-18abs ↗pdf ↗

The variational calculus for the Faddeev-Hopf model on a general Riemannian domain, with general Kaehler target space, is studied in the strong coupling limit. In this limit, the model has key similarities with pure Yang-Mills theory, namely conformal invariance in dimension 4 and an infinite dimensional symmetry group…

2006-05-18abs ↗pdf ↗

Study the geometry of twistor spaces with rotating circle action.

problem Holomorphic symplectic geometry of twistor spaces.
method Interpreting Hitchin's meromorphic connection and studying critical points of moment maps.
result Residue of Hitchin's meromorphic connection serves as a moment map for the circle action.

This paper discovers new identities linking geodesic and orthogeodesic lengths on hyperbolic surfaces.

problem Understanding relationships between geodesic and orthogeodesic lengths on hyperbolic surfaces.
method Investigates a broad family of identities involving lengths of all closed geodesics and orthogeodesics.
result Introduces new identities that include lengths of all closed geodesics, contrasting with previous identities.