1,388 research outputs found
Homomorphisms of quantum groups
In this article, we study several equivalent notions of homomorphism between locally compact quantum groups compatible with duality. In particular, we show that our homomorphisms are equivalent to functors between the respective categories of coactions. We lift the reduced bicharacter to universal quantum groups for any locally compact quantum group defined by a modular multiplicative unitary, without assuming Haar weights. We work in the general setting of modular multiplicative unitaries
Measurement of the Higgs Boson Mass with a Linear e+e- Collider
The potential of a linear e+e- collider operated at a centre-of-mass energy
of 350 GeV is studied for the measurement of the Higgs boson mass. An
integrated luminosity of 500 fb-1 is assumed. For Higgs boson masses of 120,
150 and 180 GeV the uncertainty on the Higgs boson mass measurement is
estimated to be 40, 65 and 70 MeV, respectively. The effects of beam related
systematics, namely a bias in the beam energy measurement, the beam energy
spread and the luminosity spectrum due to beamstrahlung, on the precision of
the Higgs boson mass measurement are investigated. In order to keep the
systematic uncertainty on the Higgs boson mass well below the level of the
statistical error, the beam energy measurement must be controlled with a
relative precision better than 10-4.Comment: 19 pages, 10 Figure
Localisation and mass generation for non-Abelian gauge fields
It has been suggested recently that in the presence of suitably "warped"
extra dimensions, the low-energy limit of pure gauge field theory may contain
massive elementary vector bosons localised on a "brane", but no elementary
Higgs scalars. We provide non-perturbative evidence in favour of this
conjecture through numerical lattice measurements of the static quark-antiquark
force of pure SU(2) gauge theory in three dimensions, of which one is warped.
We consider also warpings leading to massless localised vector bosons, and
again find evidence supporting the perturbative prediction, even though the
gauge coupling diverges far from the brane in this case.Comment: 27 pages; small clarifications adde
Equivariant comparison of quantum homogeneous spaces
We prove the deformation invariance of the quantum homogeneous spaces of the
q-deformation of simply connected simple compact Lie groups over the
Poisson-Lie quantum subgroups, in the equivariant KK-theory with respect to the
translation action by maximal tori. This extends a result of Neshveyev-Tuset to
the equivariant setting. As applications, we prove the ring isomorphism of the
K-group of Gq with respect to the coproduct of C(Gq), and an analogue of the
Borsuk-Ulam theorem for quantum spheres.Comment: 21 page
Quantum teardrops
Algebras of functions on quantum weighted projective spaces are introduced,
and the structure of quantum weighted projective lines or quantum teardrops are
described in detail. In particular the presentation of the coordinate algebra
of the quantum teardrop in terms of generators and relations and classification
of irreducible *-representations are derived. The algebras are then analysed
from the point of view of Hopf-Galois theory or the theory of quantum principal
bundles. Fredholm modules and associated traces are constructed. C*-algebras of
continuous functions on quantum weighted projective lines are described and
their K-groups computed.Comment: 18 page
Signals that stop the rot : regulation of secondary metabolite defences in cereals
Plants accumulate a vast arsenal of chemically diverse secondary metabolites for defence against pathogens. This review will focus on the signal transduction and regulation of defence secondary metabolite production in five food security cereal crops: maize, rice, wheat, sorghum and oats. Recent research advances in this field have revealed novel processes and chemistry in these monocots that make this a rich field for future research.The National Research Foundation (NRF) and the Genomics Research Institute at the University of Pretoria (UP), South Africa.http://www.elsevier.com/locate/pmpp2017-04-30hb2016Forestry and Agricultural Biotechnology Institute (FABI)Plant Scienc
Effective gauge theories on domain walls via bulk confinement?
We study with lattice techniques the localisation of gauge fields on domain
wall defects in 2+1 dimensions, following a scenario originally proposed by
Dvali and Shifman for 3+1 dimensions, based on confining dynamics in the bulk.
We find that a localised gauge zero-mode does exist, if the domain wall is wide
enough compared with the confinement scale in the bulk. The range of
applicability of the corresponding low-energy effective theory is determined by
the mass gap to the higher modes. For a wide domain wall, this mass gap is set
by ``Kaluza--Klein modes'' as determined by the width. It is pointed out that
in this regime the dynamical energy scales generated by the interactions of the
localised zero-modes are in fact higher than the mass gap. Therefore, at least
in 2+1 dimensions, the zero-modes alone do not form a low-energy effective
gauge theory of a traditional type. Finally, we discuss how the situation is
expected to change in going to 3+1 dimensions.Comment: 24 pages. v2: published versio
Geometric Strategy for the Optimal Quantum Search
We explore quantum search from the geometric viewpoint of a complex
projective space , a space of rays. First, we show that the optimal quantum
search can be geometrically identified with the shortest path along the
geodesic joining a target state, an element of the computational basis, and
such an initial state as overlaps equally, up to phases, with all the elements
of the computational basis. Second, we calculate the entanglement through the
algorithm for any number of qubits as the minimum Fubini-Study distance to
the submanifold formed by separable states in Segre embedding, and find that
entanglement is used almost maximally for large . The computational time
seems to be optimized by the dynamics as the geodesic, running across entangled
states away from the submanifold of separable states, rather than the amount of
entanglement itself.Comment: revtex, 10 pages, 7 eps figures, uses psfrag packag
An evaluation of the endophytic colonies present in pathogenic and non-pathogenic Vanguerieae using electron microscopy
Fadogia homblei, Pavetta harborii, Pavetta schumanniana, Vangueria pygmaea (=Pachystigma pygmaeum),
Vangueria latifolia (=Pachystigma latifolium) and Vangueria thamnus (=Pachystigma thamnus) all induce
one of the most important cardiotoxicoses of domestic ruminants in southern Africa, causing the sickness
gousiekte. All the plants which cause gousiekte have previously been shown to contain bacterial endophytes.
However, in this study other plants within the Vanguerieae tribe that have not been reported to cause
gousiekte; namely Vangueria infausta, Vangueria macrocalyx and Vangueria madagascariensis, have now
been shown to also contain endophytes within the inter-cellular spaces of the leaves. The disease gousiekte
is difficult to characterise due to fluctuations in plant toxicity. The majority of reported cases of gousiekte
poisoning are at the beginning of the growing season; and thus the plants are thought to be more toxic at
this time. By using both transmission and scanning electron microscopy the endophytes within these
Vanguerieae plants were compared visually. Using the plant reported most often for gousiekte poisoning,
V. pygmaea, a basic seasonal comparison of the presence of endophytes was done. It was found that the
bacterial endophyte colonies were most abundant during the spring season.The National Research Foundation of South
Africa and Professor T. Coutinho.http:// www.elsevier.com/ locate/sajbam201
Transport Properties of the Quark-Gluon Plasma -- A Lattice QCD Perspective
Transport properties of a thermal medium determine how its conserved charge
densities (for instance the electric charge, energy or momentum) evolve as a
function of time and eventually relax back to their equilibrium values. Here
the transport properties of the quark-gluon plasma are reviewed from a
theoretical perspective. The latter play a key role in the description of
heavy-ion collisions, and are an important ingredient in constraining particle
production processes in the early universe. We place particular emphasis on
lattice QCD calculations of conserved current correlators. These Euclidean
correlators are related by an integral transform to spectral functions, whose
small-frequency form determines the transport properties via Kubo formulae. The
universal hydrodynamic predictions for the small-frequency pole structure of
spectral functions are summarized. The viability of a quasiparticle description
implies the presence of additional characteristic features in the spectral
functions. These features are in stark contrast with the functional form that
is found in strongly coupled plasmas via the gauge/gravity duality. A central
goal is therefore to determine which of these dynamical regimes the quark-gluon
plasma is qualitatively closer to as a function of temperature. We review the
analysis of lattice correlators in relation to transport properties, and
tentatively estimate what computational effort is required to make decisive
progress in this field.Comment: 54 pages, 37 figures, review written for EPJA and APPN; one parag.
added end of section 3.4, and one at the end of section 3.2.2; some Refs.
added, and some other minor change
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