arXiv subjects

N. P. Warner

Publications and source records attributed to N. P. Warner.

32 records · Page 2Linked to original sources

arXiv1995

Supersymmetry in Boundary Integrable Models

Quantum integrable models that possess $N=2$ supersymmetry are investigated on the half-space. Conformal perturbation theory is used to identify some $N=2$ supersymmetric boundary integrable models, and the effective boundary Landau-Ginzburg formulations are constructed. It is found that $N=2$ supersymmetry largely determines the boundary action in terms of the bulk, and in particular, the boundary bosonic potential is $|W|^2$, where $W$ is the bulk superpotential. Supersymmetry is also investigated using the affine quantum group symmetry of exact scattering matrices, and the affine quantum group symmetry of boundary reflection matrices is analyzed both for supersymmetric and more general models. Some $N=2$ supersymmetry preserving boundary reflection matrices are given, and their connection with the boundary Landau-Ginzburg actions is discussed.

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arXiv1994

The Refined Elliptic Genus and Coulomb Gas Formulations of $N=2$ Superconformal Coset Models

We describe, in some detail, a number of different Coulomb gas formulations of $N=2$ superconformal coset models. We also give the mappings between these formulations. The ultimate purpose of this is to show how the Landau-Ginzburg structure of these models can be used to extract the $W$-generators, and to show how the computation of the elliptic genus can be refined so as to extract very detailed information about the characters of component parts of the model.

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arXiv1994

On the Algebraic Structure of Gravitational Descendants in CP(n-1) Coset Models

We investigate how specific free-field realizations of twisted N=2 supersymmetric coset models give rise to natural extensions of the ``matter'' Hilbert spaces in such a manner as to incorporate the various gravitational excitations. In particular, we show that adopting a particular screening prescription is equivalent to imposing the requisite equivariance condition on cohomology. We find a simple algebraic characterization of the $W_n$-gravitational ground ring spectra of these theories in terms of affine-$SU(n)$ highest weights..

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arXiv1994

The boundary sine-Gordon theory: classical and semi-classical analysis

We consider the sine-Gordon model on a half-line, with an additional potential term of the form $-M\cos{β\over 2}(φ-φ_0)$ at the boundary. We compute the classical time delay for general values of $M$, $β$ and $φ_0$ using $τ$-function methods and show that in the classical limit, the method of images still works, despite the non-linearity of the problem. We also perform a semi-classical analysis, and find agreement with the exact quantum S-matrix conjectured by Ghoshal and Zamolodchikov.

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arXiv1994

Exact solution of a massless scalar field with a relevant boundary interaction

We solve exactly the "boundary sine-Gordon" system of a massless scalar field ϕwith a \cos[βϕ/2] potential at a boundary. This model has appeared in several contexts, including tunneling between quantum-Hall edge states and in dissipative quantum mechanics. For β^2 < 8π, this system exhibits a boundary renormalization-group flow from Neumann to Dirichlet boundary conditions. By taking the massless limit of the sine-Gordon model with boundary potential, we find the exact S matrix for particles scattering off the boundary. Using the thermodynamic Bethe ansatz, we calculate the boundary entropy along the entire flow. We show how these particles correspond to wave packets in the classical Klein-Gordon equation, thus giving a more precise explanation of scattering in a massless theory.

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arXiv1994

Refining the Elliptic Genus

We show how special forms of an $N=2$ Landau-Ginzburg potential directly imply the presence of an $N=2$ super-$W$ algebra. If the Landau-Ginzburg model has a super-$W$ algebra, we show how the elliptic genus can be refined so as to give much more complete information about the structure of the model. We study the super-$W_3$ model in some detail, and present some results and conjectures about more general models.

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arXiv1993

Lattice models and $N=2$ supersymmetry

We review the construction of exactly solvable lattice models whose continuum limits are $N=2$ supersymmetric models. Both critical and off-critical models are discussed. The approach we take is to first find lattice models with natural topological sectors, and then identify the continuum limits of these sectors with topologically twisted $N=2$ supersymmetric field theories. From this, we then describe how to recover the complete lattice versions of the $N=2$ supersymmetric field theories. We discuss a number of simple physical examples and we describe how to construct a broad class of models. We also give a brief review of the scattering matrices for the excitations of these models. (Contribution to the procedings of the Cargese meeting on ``String Theory, Conformal Models and Topological Field Theories'', May 12-21, 1993.)

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arXiv1993

Off-Critical Lattice Analogues of $N=2$ Supersymmetric Quantum Integrable Models

We obtain off-critical (elliptic) Boltzmann weights for lattice models whose continuum limits correspond to massive, $N=2$ supersymmetric, quantum integrable field theories. We also compute the free energies of these models and show that they are analytic in the region of parameter space where we believe that the supersymmetry is unbroken. While the supersymmetry is not directly realized on the lattice, there is still a very close connection between the models described here and topological lattice models. A simple example is discussed in detail and some corner transfer matrix computations are also presented.

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arXiv1993

$N=2$ Supersymmetric Integrable Models and Topological Field Theories

These lectures review some of the basic properties of $N=2$ superconformal field theories and the corresponding topological field theories. One of my basic aims is to show how the techniques of topological field theory can be used to compute effective \LG potentials for perturbed $N=2$ superconformal field theories. In particular, I will briefly discuss the application of these ideas to $N=2$ supersymmetric quantum integrable models. (Lectures given at the Summer School on High Energy Physics and Cosmology, Trieste, Italy, June 15th -- July 3rd, 1992. To appear in the proceedings.)

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arXiv1992

Extended N=2 Superconformal Structure of Gravity and W-Gravity Coupled to Matter

We show that almost all string theories, including the bosonic string, the superstring and $W$-string theories, possess a twisted N=2 superconformal symmetry. This enables us to establish a connection between topological gravity and the field theoretical description of matter coupled to gravity. We also show how the \brs operators of the $W_n$-string can be obtained by hamiltonian reduction of $SL(n|n-1)$. The tachyonic and ground ring states of $W$-strings are described in the light of the N=2 superconformal structure, and the ground ring generators for the non-critical $W_3$-string are explicitly constructed. The relationship to $G/G$ models and quantum integrable systems is also briefly described.

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arXiv1992

A BRST Operator for non-critical W-Strings

We construct the BRST operator for non-critical $W_3$-strings and discuss the tachyon-like spectrum. For $N$-punctured spheres with $N \leq 5$ we briefly describe a formal definition of the integral over $W_3$-moduli space.

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arXiv1992

S-matrices for Perturbed N=2 Superconformal Field Theory from quantum groups

S-matrices for integrable perturbations of $N=2$ superconformal field theories are studied. The models we consider correspond to perturbations of the coset theory $G_k \times H_{g-h} /H_{k+g-h} $. The perturbed models are closely related to $\hat G$-affine Toda theories with a background charge tuned to $H$. Using the quantum group restriction of the affine Toda theories we derive the S-matrix.

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arXiv1992

Lattice Analogues of $N=2$ Superconformal Models via Quantum Group Truncation

We obtain lattice models whose continuum limits correspond to $N=2$ superconformal coset models. This is done by taking the well known vertex model whose continuum limit is the $G \times G/G$ conformal field theory, and twisting the transfer matrix and modifying the quantum group truncation. We find that the natural order parameters of the new models are precisely the chiral primary fields. The integrable perturbations of the conformal field theory limit also have natural counterparts in the lattice formulation, and these can be incorporated into an affine quantum group structure. The topological, twisted $N=2$ superconformal models also have lattice analogues, and these emerge as an intermediate part of our analysis.

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arXiv1991

Topological Matter, Integrable Models and Fusion Rings

We show how topological $G_k/G_k$ models can be embedded into the topological matter models that are obtained by perturbing the twisted $N=2$ supersymmetric, hermitian symmetric, coset models. In particular, this leads to an embedding of the fusion ring of $G$ as a sub-ring of the perturbed, chiral primary ring. The perturbation of the twisted $N=2$ model that leads to the fusion ring is also shown to lead to an integrable $N=2$ supersymmetric field theory when the untwisted $N=2$ superconformal field theory is perturbed by the same operator and its hermitian conjugate.

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