1,396 research outputs found
Supersymmetric multi-Higgs doublet model with non-linear electroweak symmetry breaking
The electroweak symmetry is nonlinearly realized in an extension of the
minimal supersymmetric standard model (MSSM) through an additional pair of
constrained Higgs doublet superfields. The superpotential couplings of this
constrained Higgs doublet pair to the MSSM Higgs doublet pair catalyze their
vacuum expectation values. The Higgs and Higgsino-gaugino mass spectrum is
presented for several choices of supersymmetry (SUSY) breaking and Higgs
superpotential mass parameters. The additional vacuum expectation values
provided by the constrained fields can produce a phenomenology quite different
than that of the MSSM .Comment: 41 pages, 16 figure
Oscillating p-Branes
Coset methods are used to construct the action describing the dynamics
associated with the spontaneous breaking of the Poincare symmetries of D
dimensional space-time due to the embedding of a p-brane with codimension
N=D-p-1. The resulting world volume action is an ISO(1,p+N) invariant
generalization of the Nambu-Goto action in d=p+1 dimensional space-time.
Analogous results are obtained for an AdS p-brane with codimension N embedded
in D dimensional AdS space, yielding an SO(2,p+N) invariant version of the
Nambu-Goto action in d=p+1 dimensional space-time. Attention is focused on a
supersymmetric extension of the D=6 Minkowski space case with an embedded p=3
brane; a particular realization of which is provided by a non-BPS vortex. Here
both the Nambu-Goto-Akulov-Volkov action and its dual tensor form are
presented.Comment: 25 pages, no figure
Brane Vector Phenomenology
Local oscillations of the brane world are manifested as masssive vector
fields. Their coupling to the Standard Model can be obtained using the method
of nonlinear realizations of the spontaneously broken higher dimensional
space-time symmetries, and to an extent, are model independent.
Phenomenological limits on these vector field parameters are obtained using LEP
collider data and dark matter constraints.Comment: 3 pages, 2 figures, late
Higgs Decays and Brane Gravi-vectors
Higgs boson decays in flexible brane world models with stable, massive
gravi-vectors are considered. Such vectors couple bilinearly to the Standard
Model fields through either the Standard Model energy-momentum tensor, the weak
hypercharge field strength or the Higgs scalar. The role of the coupling
involving the extrinsic curvature is highlighted. It is found that within the
presently allowed parameter space, the decay rate of the Higgs into two
gravi-vectors (which would appear as an invisible Higgs decay) can be
comparable to the rate for any of the Standard Model decay modes.Comment: 5 pages, 11 figures, revte
Nonlinear realization of local symmetries of AdS space
Coset methods are used to construct the action describing the dynamics
associated with the spontaneous breaking of the local symmetries of AdS_{d+1}
space due to the embedding of an AdS_d brane. The resulting action is an
SO(2,d) invariant AdS form of the Einstein-Hilbert action, which in addition to
the AdS_d gravitational vielbein, also includes a massive vector field
localized on the brane. Its long wavelength dynamics is the same as a massive
Abelian vector field coupled to gravity in AdS_d space.Comment: 17 page
Fixed FAR Vote Fusion of regional Facial Classifiers
Holistic face recognition methods like PCA and LDA have the disadvantage that they are very sensitive to expression, hair and illumination variations. This is one of the main reasons they are no longer competitive in the major benchmarks like FRGC and FRVT. In this paper we present an LDA based approach that combines many overlapping regional classifiers (experts) using what we call a Fixed FAR Voting Fusion (FFVF) strategy. The combination by voting of regional classifiers means that if there are sufficient regional classifiers unaffected by the expression, illumination or hair variations, the fused classifier will still correctly recognise the face. The FFVF approach has two interesting properties: it allows robust fusion of dependent classifiers and it only requires a single parameter to be tuned to obtain weights for fusion of different classifiers. We show the potential of the FFVF of regional classifiers using the standard benchmarks experiments 1 and 4 on FRGCv2 data. The multiregion FFVF classifier has a FRR of 4% at FAR=0.1% for controlled and 38% for uncontrolled data compared to 7% and\ud
56% for the best single region classifier
Investigating the KNDy hypothesis in humans by co-administration of kisspeptin, neurokinin B and naltrexone in men
Context: A subpopulation of hypothalamic neurons co-localise three neuropeptides namely kisspeptin, neurokinin B (NKB) and dynorphin collectively termed KNDy neurons. Animal studies suggest they interact to affect pulsatile GnRH release (KNDy hypothesis); kisspeptin stimulates, NKB modulates and dynorphin (an opioid) inhibits. Objective: To investigate the KNDy hypothesis in humans, we assessed for the first time the effects of co-administration of kisspeptin-54, NKB and an opioid receptor antagonist, naltrexone on LH pulsatility (surrogate marker for GnRH pulsatility) and gonadotropin release. Design, setting and participants: Ethically approved prospective, single-blinded placebo-controlled study. Healthy male volunteers (n=5/group) attended our research facility for 8 study visits. Intervention and main outcome measure: After 1h baseline blood sampling, participants received a different intervention at each visit: oral 50mg naltrexone (NAL), 8h intravenous infusions of vehicle, 2.56nmol/kg/h NKB (NKB), 0.1nmol/kg/h kissspeptin-54 (KP) alone and in combination. Frequent blood sampling to measure plasma gonadotropins and sex steroids was conducted and LH pulsatility was determined using blinded deconvolution analysis. Results: All kisspeptin and naltrexone containing groups potently increased LH and LH pulsatility (p<0.001 vs vehicle). NKB alone did not affect gonadotropins. NKB+KP had significantly lower increases in gonadotropins compared with kisspeptin alone (p<0.01). NAL+KP was the only group to significantly increase LH pulse amplitude (p<0.001 vs vehicle). Conclusions: Our results suggest significant interactions between the KNDy neuropeptides on LH pulsatility and gonadotropin release in humans. This has important implications for improving our understanding of GnRH pulse generation in humans
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