54 research outputs found
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 --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 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 -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
Implant-Tolerant Orthopaedic Measurements for Post-Operative Radiographs of the Lower Limbs
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 is
spontaneously broken to a subgroup while supersymmetry is unbroken. In
accordance with the supersymmetric Goldstone theorem, these lagrangians contain
Nambu--Goldstone superfields associated with a coset space ,
where is the complexification of and is the largest
subgroup of 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 invariant, which can
give rise to non-trivial relations among independent -invariants in the
superpotential. We also show that the Kahler potential of the matter fields can
be restricted by a remnant of 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 on the matter fields, hinting that the constraints
imposed by 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 -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
with the field content of the standard
model is constructed. The phenomenology of this model is analyzed.Comment: 39 pages, LaTeX, no figure
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