7,808 research outputs found
Chiral Symmetry and Neutrino Pion Production off the Nucleon
The neutrino pion production off the nucleon is traditionally described in
the literature by means of the weak excitation of the Delta(1232) resonance and
its subsequent decay into N pi. Here, we present results from a model that
includes also some background terms required by chiral symmetry. We show that
the contribution of these terms is sizeable and leads to significant effects in
total and partially integrated pion production cross sections at intermediate
energies of interest for neutrino oscillation experiments. Finally, we discuss
parity-violating contributions to the pion angular differential cross section
induced by the interference of these non-resonant terms with the Delta piece.Comment: To appear in the proceedings of 9th International Workshop On
Neutrino Factories, Superbeams and Betabeams (NuFact07) August 6-11, 2007,
Okayama University, Japa
D6 Family Symmetry and Cold Dark Matter at LHC
We consider a non-supersymmetric extension of the standard model with a
family symmetry based on D6 Z2 Z2, where one of Z2's is exactly conserved. This
Z2 forbids the tree-level neutrino masses and simultaneously ensures the
stability of cold dark matter candidates. From the assumption that cold dark
matter is fermionic we can single out the D6 singlet right-handed neutrino as
the best cold dark mater candidate. We find that an inert charged Higgs with a
mass between 300 and 750 GeV decays mostly into an electron (or a positron)
with a large missing energy, where the missing energy is carried away by the
cold dark matter candidate. This will be a clean signal at LHC.Comment: 20 pages, 7 figure
The Effect Of Plasma-deposited Polymers On The Nucleate Boiling Behavior Of Copper Heat Transfer Surfaces
The effect of plasma deposited polymers on the nucleate boiling behavior of copper heat transfer surfaces, using water as the boiling liquid, was determined. The monomers used were tetrafluoroethylene (TFE) and methane. It was found that an 18 nm thick coating of TFE enhanced the nucleate boiling, while a 150 nm thick coating reduced the nucleate boiling. Both 15 nm and 150 nm thick coatings of methane reduced the nucleate boiling, with the effect being more pronounced with the thicker coating. A surface energy effect is postulated to explain the enhanced boiling observed. © 1981
Neel Temperature of Quasi-Low-Dimensional Heisenberg Antiferromagnets
The N\'eel temperature, , of quasi-one- and quasi-two-dimensional
antiferromagnetic Heisenberg models on a cubic lattice is calculated by Monte
Carlo simulations as a function of inter-chain (inter-layer) to intra-chain
(intra-layer) coupling down to . We find that
obeys a modified random-phase approximation-like relation for small
with an effective universal renormalized coordination number,
independent of the size of the spin. Empirical formulae describing
for a wide range of and useful for the analysis of experimental
measurements are presented.Comment: 4 pages, 4 figures, to be published in Phys. Rev. Let
Nonpolar resistance switching of metal/binary-transition-metal oxides/metal sandwiches: homogeneous/inhomogeneous transition of current distribution
Exotic features of a metal/oxide/metal (MOM) sandwich, which will be the
basis for a drastically innovative nonvolatile memory device, is brought to
light from a physical point of view. Here the insulator is one of the
ubiquitous and classic binary-transition-metal oxides (TMO), such as Fe2O3,
NiO, and CoO. The sandwich exhibits a resistance that reversibly switches
between two states: one is a highly resistive off-state and the other is a
conductive on-state. Several distinct features were universally observed in
these binary TMO sandwiches: namely, nonpolar switching, non-volatile threshold
switching, and current--voltage duality. From the systematic sample-size
dependence of the resistance in on- and off-states, we conclude that the
resistance switching is due to the homogeneous/inhomogeneous transition of the
current distribution at the interface.Comment: 7 pages, 5 figures, REVTeX4, submitted to Phys. Rev. B (Feb. 23,
2007). If you can't download a PDF file of this manscript, an alternative one
can be found on the author's website: http://staff.aist.go.jp/i.inoue
Line nodes in the superconducting gap function of noncentrosymmetric CePt_3Si
The superconducting gap structure of recently discovered heavy fermion
CePt_3Si without spatial inversion symmetry was investigated by thermal
transport measurements down to 40 mK. In zero field a residual T-linear term
was clearly resolved as T-> 0, with a magnitude in good agreement with the
value expected for a residual normal fluid with a nodal gap structure, together
with a T^2-dependence at high temperatures. With an applied magnetic fields,
the thermal conductivity grows rapidly, in dramatic contrast to fully gapped
superconductors, and exhibits one-parameter scaling with T/sqrt{H}. These
results place an important constraint on the order parameter symmetry, that is
CePt_3Si is most likely to have line nodes.Comment: 5pages, 3figures, accpted for publication in Phys. Rev. Let
Thermal Decomposition Kinetics Of Iodine‐doped Polyacetylene In Vacuum
The thermal stability of iodine‐doped polyacetylene films, (CHIy)x, has been studied by means of electrical conductivity measurements, measurements on weight loss, and mass spectrometric analysis of desorbing species. When heated between room temperature and 125°C in vacuum, these films proved to be of poor thermal stability, being unstable at temperatures above 20°C. During the thermal treatments, molecular iodine desorbs from the films, resulting in an appreciable dopant weight loss with accompanying decrease in the electrical conductivity. The decomposition process does not follow simple kinetics. Copyright © 1983 John Wiley & Sons, Inc
Multiscale modeling and simulation for polymer melt flows between parallel plates
The flow behaviors of polymer melt composed of short chains with ten beads
between parallel plates are simulated by using a hybrid method of molecular
dynamics and computational fluid dynamics. Three problems are solved: creep
motion under a constant shear stress and its recovery motion after removing the
stress, pressure-driven flows, and the flows in rapidly oscillating plates. In
the creep/recovery problem, the delayed elastic deformation in the creep motion
and evident elastic behavior in the recovery motion are demonstrated. The
velocity profiles of the melt in pressure-driven flows are quite different from
those of Newtonian fluid due to shear thinning. Velocity gradients of the melt
become steeper near the plates and flatter at the middle between the plates as
the pressure gradient increases and the temperature decreases. In the rapidly
oscillating plates, the viscous boundary layer of the melt is much thinner than
that of Newtonian fluid due to the shear thinning of the melt. Three different
rheological regimes, i.e., the viscous fluid, visco-elastic liquid, and
visco-elastic solid regimes, form over the oscillating plate according to the
local Deborah numbers. The melt behaves as a viscous fluid in a region for
, and the crossover between the liquid-like and
solid-like regime takes place around (where
is the angular frequency of the plate and and
are Rouse and relaxation time, respectively).Comment: 13pages, 12figure
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