Minimal Supersymmetric CPN Models

Supersymmetric CPN models based on underlying bosonic Kahler manifolds have not been thought to arise directly from constrained linear ones. A counterexample for N=4 is presented using improved understanding of membranes in superstring theories leading to crucial central terms modifying the algebra of supercharge densities. The example has an immediate extension to all higher N

Gauged supersymmetric \gs--models and soft breaking terms

Supersymmetric non--linear \gs--models in four dimensions with a $D$--term potentials can sometimes have singular kinetic metric terms. As the kinetic terms of scalar fields and their chiral fermionic partners are determine by this metric, it follow that their kinetic energy vanishes in the vacuum. In previous work, it has been shown in a simple model that soft supersymmetry breaking terms can lift the degenerate the sigma-model metric and provide a consistent mass-spectra. In this letter I introduce soft breaking terms in a more realistic models based on SO(10) and $E_6$ and compute the resulting mass spectrum.Comment: Latex 6 pages, added references, typos corrected; final published versio

Avoiding the theorem of Lerche and Shore

Supersymmetric $\sigma$-models obtained by constraining linear supersymmetric field theories are ill defined. Well defined subsectors parametrising Kahler manifolds exist but are not believed to arise directly from constrained linear ones. A counterexample is offered using improved understanding of membranes in superstring theories leading to crucial central terms modifying the algebra of supercharge densitie

ANVIL: a system for the retrieval of captioned images using NLP techniques

ANVIL is a system designed for the retrieval of images annotated with short captions. It uses NLP techniques to extract dependency structures from captions and queries, and then applies a robust matching algorithm to recursively explore and compare them. There are currently two main interfaces to ANVIL: a list-based display and a 2D spatial layout that allows users to interact with and navigate between similar images. ANVIL was designed to operate as part of a publicly accessible, WWW-based image retrieval server. Consequently, product-level engineering standards were required. This paper examines both the research aspects of the system and also looks at some of the design and evaluation issues.

Line bundles in supersymmetric coset models

The scalars of an N = 1 supersymmetric sigma-model in 4 dimensions parameterize a Kaehler manifold. The transformations of their fermionic superpartners under the isometries are often anomalous. These anomalies can be canceled by introducing additional chiral multiplets with appropriate charges. To obtain the right charges a non-trivial singlet compensating multiplet can be used. However when the topology of the underlying Kaehler manifold is non-trivial, the consistency of this multiplet requires that its charge is quantized. This singlet can be interpreted as a section of a line bundle. We determine the Kaehler potentials corresponding to the minimal non-trivial singlet chiral superfields for any compact Kaehlerian coset space G/H. The quantization condition may be in conflict with the requirement of anomaly cancelation. To illustrate this, we discuss the consistency of anomaly free models based on the coset spaces E_6/SO(10)xU(1) and SU(5)/SU(2)xU(1)xSU(3).Comment: 10 pages, LaTeX, no figure

A Supersymmetric Effective Chiral Lagrangian

We construct in a manifestly supersymmetric form the leading and subleading terms in momentum for an effective supersymmetric chiral Lagrangian in terms of complex pions and their superpartners. A soft supersymmetry breaking term is included and below the supersymmetry breaking scale the Lagrangian reduces to the usual bosonic chiral Lagrangian in terms of real pions.Comment: University of Southampton preprint no. SHEP 93/94-12 LATE

New Symmetries of Supersymmetric Effective Lagrangians

We consider the structure of effective lagrangians describing the low-energy dynamics of supersymmetric theories in which a global symmetry $G$ is spontaneously broken to a subgroup $H$ while supersymmetry is unbroken. In accordance with the supersymmetric Goldstone theorem, these lagrangians contain Nambu--Goldstone superfields associated with a coset space $G^c / \hat{H}$, where $G^c$ is the complexification of $G$ and $\hat{H}$ is the largest subgroup of $G^c$ that leaves the order parameter invariant. The lagrangian may also contain additional light matter fields. To analyze the effective lagrangian for the matter fields, we first consider the case where the effective lagrangian is obtained by integrating out heavy modes at weak coupling (but including non-perturbative effects such as instantons). We show that the superpotential of the matter fields is $\hat{H}$ invariant, which can give rise to non-trivial relations among independent $H$-invariants in the superpotential. We also show that the Kahler potential of the matter fields can be restricted by a remnant of $\hat{H}$ symmetry. These results are non-perturbative and have a simple group-theoretic interpretation. When we relax the weak-coupling constraint, there appear to be additional possibilities for the action of $\hat{H}$ on the matter fields, hinting that the constraints imposed by $\hat{H}$ may be even richer in strongly coupled theories.Comment: 23 pages, plain Te

Consistent sigma-models in N=1 supergravity

A consistent N=1 supersymmetric $\sigma$-model can be constructed, given a K\"ahler manifold by adding chiral matter multiplets. Their scalar components are covariant tensors on the underlying K\"ahler manifold. The K\"ahler U(1)-charges can be adjusted such that the anomalies cancel, using the holomorphic functions in which the K\"ahler potential transforms. The arbitrariness of the U(1)-charges of matter multiplets is related to their Weyl-weights in superconformal gravity, before it is reduced to supergravity. The covariance of the K\"ahler potential forces the superpotential to be covariant as well. This relates the cut-off, the Planck scale and the matter charges to each other. A non-vanishing VEV of the covariant superpotential breaks the K\"ahler U(1) spontaneously. If this VEV vanishes, the gravitino is massless and depending on the above mentioned parameters there may be additional internal symmetry breaking. The separation of the different representations of chiral multiplets can be achieved by covariantizations of derivatives and fermions. Using non-holomorphic transformations, the full K\"ahler metric can be block-diagonalized and the necessary covariantizations come out naturally. Various aspects are illustrated by applying them to Grassmannian coset models. In particular a consistent model of coset $SU(5)/SU(2)\times U(1) \times SU(3)$ with the field content of the standard model is constructed. The phenomenology of this model is analyzed.Comment: 39 pages, LaTeX, no figure