13,225 research outputs found
M-Theory on the Orbifold C^2/Z_N
We construct M-theory on the orbifold C^2/Z_N by coupling 11-dimensional
supergravity to a seven-dimensional Yang-Mills theory located on the orbifold
fixed plane. It is shown that the resulting action is supersymmetric to leading
non-trivial order in the 11-dimensional Newton constant. This action provides
the starting point for a reduction of M-theory on G_2 spaces with co-dimension
four singularities.Comment: 33 pages, Late
Monad Bundles in Heterotic String Compactifications
In this paper, we study positive monad vector bundles on complete
intersection Calabi-Yau manifolds in the context of E8 x E8 heterotic string
compactifications. We show that the class of such bundles, subject to the
heterotic anomaly condition, is finite and consists of about 7000 models. We
explain how to compute the complete particle spectrum for these models. In
particular, we prove the absence of vector-like family anti-family pairs in all
cases. We also verify a set of highly non-trivial necessary conditions for the
stability of the bundles. A full stability proof will appear in a companion
paper. A scan over all models shows that even a few rudimentary physical
constraints reduces the number of viable models drastically.Comment: 35 pages, 4 figure
Dams and Large Scale Irrigation on the Senegal River. Impacts on Man and the Environment
human development, water, sanitation
Inequivalent classes of closed three-level systems
We show here that the and V configurations of three-level atomic
systems, while they have recently been shown to be equivalent for many
important physical quantities when driven with classical fields [M. B. Plenio,
Phys. Rev. A \textbf{62}, 015802 (2000)], are no longer equivalent when coupled
via a quantum field. We analyze the physical origin of such behavior and show
how the equivalence between these two configurations emerges in the
semiclassical limit.Comment: 4 pages, 1 figure. To appear as Brief Report in Physical Review
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