19,601 research outputs found
Electric Dipole Moments in the Generic Supersymmetric Standard Model
The generic supersymmetric standard model is a model built from a
supersymmetrized standard model field spectrum the gauge symmetries only. The
popular minimal supersymmetric standard model differs from the generic version
in having R-parity imposed by hand. We review an efficient formulation of the
model and some of the recently obtained interesting phenomenological features,
focusing on one-loop contributions to fermion electric dipole moments.Comment: 1+7 pages Revtex 3 figures incoporated; talk at NANP'0
Helical Structures in Vertically Aligned Dust Particle Chains in a Complex Plasma
Self-assembly of structures from vertically aligned, charged dust particle
bundles within a glass box placed on the lower, powered electrode of a RF GEC
cell were produced and examined experimentally. Self-organized formation of
one-dimensional vertical chains, two-dimensional zigzag structures and
three-dimensional helical structures of triangular, quadrangular, pentagonal,
hexagonal, and heptagonal symmetries are shown to occur. System evolution is
shown to progress from a one-dimensional chain structure, through a zigzag
transition to a two-dimensional, spindle-like structure and then to various
three-dimensional, helical structures exhibiting multiple symmetries. Stable
configurations are found to be dependent upon the system confinement, (where
are the horizontal and vertical dust resonance frequencies), the total number
of particles within a bundle and the RF power. For clusters having fixed
numbers of particles, the RF power at which structural transitions occur is
repeatable and exhibits no observable hysteresis. The critical conditions for
these structural transitions as well as the basic symmetry exhibited by the
one-, two- and three-dimensional structures that subsequently develop are in
good agreement with the theoretically predicted configurations of minimum
energy determined employing molecular dynamics simulations for charged dust
particles confined in a prolate, spheroidal potential as presented
theoretically by Kamimura and Ishihara [10]
Analytical theory for dark soliton interaction in nonlocal nonlinear materials with arbitrary degree of nonlocality
We investigate theoretically the interaction of dark solitons in materials
with a spatially nonlocal nonlinearity. In particular we do this analytically
and for arbitrary degree of nonlocality. We employ the variational technique to
show that nonlocality induces an attractive force in the otherwise repulsive
soliton interaction.Comment: submitted for publicatio
Correlations and fluctuations of a confined electron gas
The grand potential and the response of a phase-coherent confined noninteracting electron gas depend
sensitively on chemical potential or external parameter . We compute
their autocorrelation as a function of , and temperature. The result
is related to the short-time dynamics of the corresponding classical system,
implying in general the absence of a universal regime. Chaotic, diffusive and
integrable motions are investigated, and illustrated numerically. The
autocorrelation of the persistent current of a disordered mesoscopic ring is
also computed.Comment: 12 pages, 1 figure, to appear in Phys. Rev.
Long-term influence of physical aging processes in epoxy matrix composites
Selected mechanical properties of (plus or minus 45 degree sub 4s) graphite/epoxy composites were found to be affected by sub T sub g annealing. Postcured specimens of Thornel 300 graphite/Narmco 5208 epoxy were sub T sub G annealed at 413 K (140 C) for ca. 10 to the first through 10 to the fifth powers min., with a prior quenching from above T sub g. The ultimate tensile strength, strain-to-break, and toughness of the composite were found to decrease as a function of sub T sub g annealing time. The time-dependent change in properties can be explained on the basis of physical aging which is related to free volume changes in the non-equilibrium glassy state of network epoxies. The results imply possible changes in composite properties with service time
Physical aging in graphite epoxy composites
The matrix dominated mechanical behavior of a graphite epoxy composite was found to be affected by sub Tg annealing. Postcured + or - 45 deg 4S specimens of Thornel 300 graphite/Narmco 5208 epoxy were quenched from above Tg and given a sub Tg annealing at 140 C for times up to 10 to the 5th power min. The ultimate tensile strength, strain to break, and toughness of the composite material were found to decrease as functions of sub Tg annealing time. No weight loss was observed during the sub Tg annealing. The time dependent change in mechanical behavior is explained on the basis of free volume changes that are related to the physical aging of the nonequilibrium glassy network epoxy. The results imply possible changes in composite properties with service time
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