1,495 research outputs found
On Electric Fields in Low Temperature Superconductors
The manifestly Lorentz covariant Landau-Ginzburg equations coupled to
Maxwell's equations are considered as a possible framework for the effective
description of the interactions between low temperature superconductors and
magnetic as well as electric fields. A specific experimental set-up, involving
a nanoscopic superconductor and only static applied fields whose geometry is
crucial however, is described, which should allow to confirm or invalidate the
covariant model through the determination of the temperature dependency of the
critical magnetic-electric field phase diagram and the identification of some
distinctive features it should display.Comment: 14 pages (Latex) + 2 postscript figure
Dynamics of N=2 Supersymmetric Gauge Theories in Three Dimensions
We study the structure of the moduli spaces of vacua and superpotentials of
N=2 supersymmetric gauge theories in three dimensions. By analyzing the
instanton corrections, we compute the exact superpotentials and determine the
quantum Coulomb and Higgs branches of the theories in the weak coupling
regions. We find candidates for non-trivial N=2 superconformal field theories
at the singularities of the moduli spaces. The analysis is carried out
explicitly for gauge groups U(N_c) and SU(N_c) with N_f flavors. We show that
the field theory results are in complete agreement with the intersecting branes
picture. We also compute the exact superpotentials for arbitrary gauge groups
and arbitrary matter content.Comment: 33 pages, Latex, 6 figure
Chiral Dynamics beyond the Standard Model
The SM Lagrangian without physical scalars is rewritten as the LO of a
Low-Energy Effective Theory invariant under a higher non linear symmetry
S_{nat} \supset SU(2)_W \times U(1)_Y. Soft breaking of S_{nat} defines a
hierarchy of non standard effects dominated by universal couplings of
right-handed quarks to W. The interface of corresponding EW tests with non
perturbative QCD aspects is briefly discussed.Comment: 6 pages, Tallk given at QCD06 Conference, Montpellier, France, 3-7
July 2006, to appear in the Proceeding
Annular Vortex Solutions to the Landau-Ginzburg Equations in Mesoscopic Superconductors
New vortex solutions to the Landau-Ginzburg equations are described. These
configurations, which extend the well known Abrikosov and giant magnetic vortex
ones, consist of a succession of ring-like supercurrent vortices organised in a
concentric pattern, possibly bound to a giant magnetic vortex then lying at
their center. The dynamical and thermodynamic stability of these annular
vortices is an important open issue on which hinges the direct experimental
observation of such configurations. Nevertheless, annular vortices should
affect indirectly specific dynamic properties of mesoscopic superconducting
devices amenable to physical observation.Comment: 12 pages, LaTeX, 2 Postscript figure
Supercharges, Quantum States and Angular Momentum for N=4 Supersymmetric Monopoles
We revisit the moduli space approximation to the quantum mechanics of
monopoles in N=4 supersymmetric Yang-Mills-Higgs theory with maximal symmetry
breaking. Starting with the observation that the set of fermionic zero-modes in
N=4 supersymmetric Yang-Mills-Higgs theory can be viewed as two copies of the
set of fermionic zero-modes in the N=2 version, we build a model to describe
the quantum mechanics of N=4 supersymmetric monopoles, based on our previous
paper [1] on the N=2 case, in which this doubling of fermionic zero-modes is
manifest throughout. Our final picture extends the familiar result that quantum
states are described by differential forms on the moduli space and that the
Hamiltonian operator is the Laplacian acting on forms. In particular, we derive
a general expression for the total angular momentum operator on the moduli
space which differs from the naive candidate by the adjoint action of the
complex structures. We also express all the supercharges in terms of (twisted)
Dolbeault operators and illustrate our results by discussing, in some detail,
the N=4 supersymmetric quantum dynamics of monopoles in a theory with gauge
group SU(3) broken to U(1) x U(1).Comment: Updated references, included a derivation of the angular momentum
operator, 32 page
On a modified-Lorentz-transformation based gravity model confirming basic GRT experiments
Implementing Poincar\'e's `geometric conventionalism' a scalar
Lorentz-covariant gravity model is obtained based on gravitationally modified
Lorentz transformations (or GMLT). The modification essentially consists of an
appropriate space-time and momentum-energy scaling ("normalization") relative
to a nondynamical flat background geometry according to an isotropic,
nonsingular gravitational `affecting' function Phi(r). Elimination of the
gravitationally `unaffected' S_0 perspective by local composition of space-time
GMLT recovers the local Minkowskian metric and thus preserves the invariance of
the locally observed velocity of light. The associated energy-momentum GMLT
provides a covariant Hamiltonian description for test particles and photons
which, in a static gravitational field configuration, endorses the four `basic'
experiments for testing General Relativity Theory: gravitational i) deflection
of light, ii) precession of perihelia, iii) delay of radar echo, iv) shift of
spectral lines. The model recovers the Lagrangian of the Lorentz-Poincar\'e
gravity model by Torgny Sj\"odin and integrates elements of the precursor
gravitational theories, with spatially Variable Speed of Light (VSL) by
Einstein and Abraham, and gravitationally variable mass by Nordstr\"om.Comment: v1: 14 pages, extended version of conf. paper PIRT VIII, London,
2002. v2: section added on effective tensorial rank, references added,
appendix added, WEP issue deleted, abstract and other parts rewritten, same
results (to appear in Found. Phys.
A Minimal Length from the Cutoff Modes in Asymptotically Safe Quantum Gravity
Within asymptotically safe Quantum Einstein Gravity (QEG), the quantum
4-sphere is discussed as a specific example of a fractal spacetime manifold.
The relation between the infrared cutoff built into the effective average
action and the corresponding coarse graining scale is investigated. Analyzing
the properties of the pertinent cutoff modes, the possibility that QEG
generates a minimal length scale dynamically is explored. While there exists no
minimal proper length, the QEG sphere appears to be "fuzzy" in the sense that
there is a minimal angular separation below which two points cannot be resolved
by the cutoff modes.Comment: 26 pages, 1 figur
Quantum Gravity, Dynamical Triangulation and Higer Derivative Regularization
We consider a discrete model of euclidean quantum gravity in four dimensions
based on a summation over random simplicial manifolds. The action used is the
Einstein-Hilbert action plus an -term. The phase diagram as a function of
the bare coupling constants is studied in the search for a sensible continuum
limit. For small values of the coupling constant of the term the model
seems to belong to the same universality class as the model with pure
Einstein-Hilbert action and exhibits the same phase transition. The order of
the transition may be second or higher. The average curvature is positive at
the phase transition, which makes it difficult to understand the possible
scaling relations of the model.Comment: 27 pages (Latex), figures not included. Post script file containing
15 figures (1000 blocks) available from [email protected]
The Mont-Blanc Project: First Phase Successfully Finished
Running from October 2011 to June 2015, the aim of the European project
Mont-Blanc has been to develop an approach to Exascale computing based on
embedded power-efficient technology. The main goals of the project were to i)
build an HPC prototype using currently available energy-efficient embedded
technology, ii) design a Next Generation system to overcome the limitations of
the built prototype and iii) port a set of representative Exascale applications
to the system. This article summarises the contributions from the Leibniz
Supercomputing Centre (LRZ) and the Juelich Supercomputing Centre (JSC),
Germany, to the Mont-Blanc project.Comment: 5 pages, 3 figure
A Lorentz-Poincar\'e type interpretation of the Weak Equivalence Principle
The validity of the Weak Equivalence Principle relative to a local inertial
frame is detailed in a scalar-vector gravitation model with Lorentz-Poincar\'e
type interpretation. Given the previously established first Post-Newtonian
concordance of dynamics with General Relativity, the principle is to this order
compatible with GRT. The gravitationally modified Lorentz transformations, on
which the observations in physical coordinates depend, are shown to provide a
physical interpretation of \emph{parallel transport}. A development of
``geodesic'' deviation in terms of the present model is given as well.Comment: v1: 9 pages, 2 figures, v2: version to appear in International
Journal of Theoretical Physic
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