16,384 research outputs found
Fermionic Field Theory and Gauge Interactions on Random Lattices
Random-lattice fermions have been shown to be free of the doubling problem if
there are no interactions or interactions of a non-gauge nature. However, gauge
interactions impose stringent constraints as expressed by the Ward-Takahashi
identities which could revive the free-field suppressed doubler modes in loop
diagrams. After introducing a formulation for fermions on a new kind of random
lattice, we compare random, naive and Wilson fermions in two dimensional
Abelian background gauge theory. We show that the doublers are revived for
random lattices in the continuum limit, while demonstrating that gauge
invariance plays the critical role in this revival. Some implications of the
persistent doubling phenomenon on random lattices are also discussed.Comment: 16 A4 pages, UM-P-93/0
Simulations with Complex Measures
Towards a solution to the sign problem in the simulations of systems having
indefinite or complex-valued measures, we propose a new approach which yields
statistical errors smaller than the crude Monte Carlo using absolute values of
the original measures. The 1D complex-coupling Ising model is employed as an
illustration.Comment: 3 pages, postcript (95K), contribution to LAT93, UM-P-93/10
Research and development in CdS photovoltaic film cells Third quarterly progress report, 1 Dec. 1962 - 28 Feb. 1963
Large cadmium sulfide thin film photovoltaic cell
Development of cadmium sulfide photovoltaic film cells Final report
Controlled carrier concentrations and improved cell conversion efficiencies in cadmium sulfide photovoltaic film cel
Research and development in cds photovoltaic film cells third quarterly report, nov. 19, 1964 - feb. 19, 1965
Cadmium sulfide photovoltaic film cell
Research and development in cds photovoltaic film cells final report
Fabrication of lightweight, flexible, high efficiency, low cost, thin film, cadmium sulfide solar cells to operate for long periods in space without appreciable degradatio
Formation of Protoplanets from Massive Planetesimals in Binary Systems
More than half of stars reside in binary or multiple star systems and many
planets have been found in binary systems. From theoretical point of view,
however, whether or not the planetary formation proceeds in a binary system is
a very complex problem, because secular perturbation from the companion star
can easily stir up the eccentricity of the planetesimals and cause
high-velocity, destructive collisions between planetesimals. Early stage of
planetary formation process in binary systems has been studied by restricted
three-body approach with gas drag and it is commonly accepted that accretion of
planetesimals can proceed due to orbital phasing by gas drag. However, the gas
drag becomes less effective as the planetesimals become massive. Therefore it
is still uncertain whether the collision velocity remains small and planetary
accretion can proceed, once the planetesimals become massive. We performed {\it
N}-body simulations of planetary formation in binary systems starting from
massive planetesimals whose size is about 100-500 km. We found that the
eccentricity vectors of planetesimals quickly converge to the forced
eccentricity due to the coupling of the perturbation of the companion and the
mutual interaction of planetesimals if the initial disk model is sufficiently
wide in radial distribution. This convergence decreases the collision velocity
and as a result accretion can proceed much in the same way as in isolated
systems. The basic processes of the planetary formation, such as runaway growth
and oligarchic growth and final configuration of the protoplanets are
essentially the same in binary systems and single star systems, at least in the
late stage where the effect of gas drag is small.Comment: 26pages, 11 figures. ApJ accepte
Research and development in CdS photovoltaic cells Third quarterly report, 29 Dec. 1965 - 29 Mar. 1966
Barrier formation studies of copper sulfide and cadmium sulfide in photovoltaic cell
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