4,397 research outputs found
Maximally Realistic Causal Quantum Mechanics
We recently constructed a causal quantum mechanics in 2 dim. phase space
which is more realistic than the de Broglie-Bohm mechanics as it reproduces not
just the position but also the momentum probability density of ordinary quantum
theory. Here we present an even more ambitious construction in 2n dim. phase
space. We conjecture that the causal Hamiltonian quantum mechanics presented
here is `maximally realistic'. The positive definite phase space density
reproduces as marginals the correct quantum probability densities of
different complete commuting sets of observables (e.g. , and
other sets). In general the particle velocities do not coincide with the
de Broglie-Bohm velocities.Comment: Published versio
A study of the porosity of nuclear graphite using small-angle neutron scattering
Small angle neutron scattering (SANS) measures porosity in nuclear graphites, including both open pores, caused by escaping decomposition gases, and internal cracks (in coke particles) generated by anisotropic thermal contraction along the c-direction (Mrozowski Cracks). Porosity changes on the length scale observable by SANS must control the development of internal stresses and hence of cracking in AGR graphite due to irradiation (both fast neutron displacements of carbon atoms and radiolytic corrosion by CO2). Such cracking may cause premature reactor shutdown. SANS measurements show that porosity is fractal on a length scale between ~0.2-300 nm, presumably due to Mrozowski cracks – because the fractal index of the SANS signal depends only on the porosity of the graphitic filler. We report here two novel uses of the SANS technique as applied to reactor graphite – contrast matching with D-toluene (to measure the fraction of the porosity open to the surface) and the temperature dependence of the scattering (to measure pore width changes up to 2000 °C). These results provide important new information on AGR graphite porosity and its evolution during irradiation
The effect of SU-8 patterned surfaces on the response of the quartz crystal microbalance
In this work we present data showing the effect of patterning layers of SU-8 photoresist on a quartz crystal microbalance (QCM) and subsequent chemical treatment to increase their hydrophobicity. Patterns with 5 mu m diameter pillars spaced every 10 mu m have been fabricated with heights of 3, 5 and 10 mu m in addition to equivalent thickness flat layers. Contact angle measurements have been made before and after the hydrophobic chemical treatment. The change in resonant frequency of the QCM has been investigated as the surfaces were submerged in solutions of water/PEG with changing viscosity-density product
Probing Intermediate Mass Higgs Interactions at the CERN Large Hadron Collider
We analyze the potentiality of the CERN Large Hadron Collider to probe the
Higgs boson couplings to the electroweak gauge bosons. We parametrize the
possible deviations of these couplings due to new physics in a model
independent way, using the most general dimension--six effective lagrangian
where the SU(2)_L x U(1)_Y is realized linearly. For intermediate Higgs masses,
the decay channel into two photons is the most important one for Higgs searches
at the LHC. We study the effects of these new interactions on the Higgs
production mechanism and its subsequent decay into two photons. We show that
the LHC will be sensitive to new physics scales beyond the present limits
extracted from the LEP and Tevatron physics.Comment: 13 pages, 1 figure included using epsfig, RevTe
Visible Sector Supersymmetry Breaking Revisited
We revisit the possibility of "visible sector" SUSY models: models which are
straightforward renormalizable extensions of the Minimal Supersymmetric
Standard Model (MSSM), where SUSY is broken at tree level. Models of this type
were abandoned twenty years ago due to phenomenological problems, which we
review. We then demonstrate that it is possible to construct simple
phenomenologically viable visible sector SUSY models. Such models are indeed
very constrained, and have some inelegant features. They also have interesting
and distinctive phenomenology. Our models predict light gauginos and very heavy
squarks and sleptons. The squarks and sleptons may not be observable at the
LHC. The LSP is a stable very light gravitino with a significant Higgsino
admixture. The NLSP is mostly Bino. The Higgs boson is naturally heavy. Proton
decay is sufficently and naturally suppressed, even for a cutoff scale as low
as 10^8 GeV. The lightest particle of the O'Raifeartaigh sector (the LOP) is
stable, and is an interesting cold dark matter candidate.Comment: 23 pages, 3 figures, LaTe
A Novel Triterpene Saponin from Gypsophila capillaris
A novel C-28 tetraglycoside of quillaic acid (1) has been isolated from Gypsophila capillaris. The structure was elucidated by 1 D NMR (NOE difference, DEPT, selective13C{1H} INEPT), 2D NMR (1H,1H and1H,13C COSY,1H,1H,1H RELAY, ROESY and TOCSY) and other spectroscopic and chromatographic evidences. Conformational dynamics within the tetrasaccharide part were estimated from NOE responses and ROESY peaks. © 1995 Verlag der Zeitschrift für Naturforschung. All rights reserved
Charge and Current Sum Rules in Quantum Media Coupled to Radiation
This paper concerns the equilibrium bulk charge and current density
correlation functions in quantum media, conductors and dielectrics, fully
coupled to the radiation (the retarded regime). A sequence of static and
time-dependent sum rules, which fix the values of certain moments of the charge
and current density correlation functions, is obtained by using Rytov's
fluctuational electrodynamics. A technique is developed to extract the
classical and purely quantum-mechanical parts of these sum rules. The sum rules
are critically tested in the classical limit and on the jellium model. A
comparison is made with microscopic approaches to systems of particles
interacting through Coulomb forces only (the non-retarded regime). In contrast
with microscopic results, the current-current correlation function is found to
be integrable in space, in both classical and quantum regimes.Comment: 19 pages, 1 figur
Bell Inequalities in Phase Space and their Violation in Quantum Mechanics
We derive ``Bell inequalities'' in four dimensional phase space and prove the
following ``three marginal theorem'' for phase space densities
, thus settling a long standing
conjecture : ``there exist quantum states for which more than three of the
quantum probability distributions for , , and
cannot be reproduced as marginals of a positive
''. We also construct the most
general positive which reproduces
any three of the above quantum probability densities for arbitrary quantum
states. This is crucial for the construction of a maximally realistic quantum
theory.Comment: 11 pages, latex, no figure
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