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Metal Parts Generation by Three Dimensional Printing
Mechanical Engineerin
Electron-Electron Bound States in Maxwell-Chern-Simons-Proca QED3
We start from a parity-breaking MCS QED model with spontaneous breaking
of the gauge symmetry as a framework for evaluation of the electron-electron
interaction potential and for attainment of numerical values for the e-e bound
state. Three expressions are obtained for the potential according to the
polarization state of the scattered electrons. In an energy scale compatible
with Condensed Matter electronic excitations, these three potentials become
degenerated. The resulting potential is implemented in the Schrodinger equation
and the variational method is applied to carry out the electronic binding
energy. The resulting binding energies in the scale of 10-100 meV and a
correlation length in the scale of 10-30 Angs. are possible indications that
the MCS-QED model adopted may be suitable to address an eventual case of
e-e pairing in the presence of parity-symmetry breakdown. The data analyzed
here suggest an energy scale of 10-100 meV to fix the breaking of the
U(1)-symmetry.
PACS numbers: 11.10.Kk 11.15.Ex 74.20.-z 74.72.-h ICEN-PS-01/17Comment: 13 pages, style revtex, revised versio
Scaling of transverse nuclear magnetic relaxation due to magnetic nanoparticle aggregation
The aggregation of superparamagnetic iron oxide (SPIO) nanoparticles
decreases the transverse nuclear magnetic resonance (NMR) relaxation time T2 of
adjacent water molecules measured by a Carr-Purcell-Meiboom-Gill (CPMG)
pulse-echo sequence. This effect is commonly used to measure the concentrations
of a variety of small molecules. We perform extensive Monte Carlo simulations
of water diffusing around SPIO nanoparticle aggregates to determine the
relationship between T2 and details of the aggregate. We find that in the
motional averaging regime T2 scales as a power law with the number N of
nanoparticles in an aggregate. The specific scaling is dependent on the fractal
dimension d of the aggregates. We find T2 N^{-0.44} for aggregates with d=2.2,
a value typical of diffusion limited aggregation. We also find that in
two-nanoparticle systems, T2 is strongly dependent on the orientation of the
two nanoparticles relative to the external magnetic field, which implies that
it may be possible to sense the orientation of a two-nanoparticle aggregate. To
optimize the sensitivity of SPIO nanoparticle sensors, we propose that it is
best to have aggregates with few nanoparticles, close together, measured with
long pulse-echo times.Comment: 20 pages, 3 figures, submitted to Journal of Magnetism and Magnetic
Material
Algebraic Renormalization of Parity-Preserving QED_3 Coupled to Scalar Matter II: Broken Case
In this letter the algebraic renormalization method, which is independent of
any kind of regularization scheme, is presented for the parity-preserving QED_3
coupled to scalar matter in the broken regime, where the scalar assumes a
finite vacuum expectation value, . The model shows to be stable
under radiative corrections and anomaly free.Comment: 9 pages, latex, no figure
An algebraic proof on the finiteness of Yang-Mills-Chern-Simons theory in D=3
A rigorous algebraic proof of the full finiteness in all orders of
perturbation theory is given for the Yang-Mills-Chern-Simons theory in a
general three-dimensional Riemannian manifold. We show the validity of a trace
identity, playing the role of a local form of the Callan-Symanzik equation, in
all loop orders, which yields the vanishing of the beta-functions associated to
the topological mass and gauge coupling constant as well as the anomalous
dimensions of the fields.Comment: 5 pages, revte
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