271,610 research outputs found
String Unification and Leptophobic in Flipped SU(5)
We summarize recent developments in the prediction for ,
self-consistent string unification and the dynamical determination of mass
scales, and leptophobic gauge bosons in the context of stringy flipped
SU(5). [To appear in Proceedings of Fourth International Conference on
Supersymmetry (SUSY96), University of Maryland (May 1996).]Comment: 5 pages, LaTeX (uses espcrc2.sty), 5 figures (included
Vanishing Str M^2 in the presence of anomalous U_A(1)
We show that the presence of an anomalous factor in the gauge
group of string-derived models may have the new and important phenomenological
consequence of allowing the vanishing of in the
``shifted" vacuum, that results in the process of cancelling the anomalous . The feasibility of this effect seems to be enhanced by a vanishing
vacuum energy, and by a ``small" value of in the
original vacuum. In the class of free-fermionic models with vanishing vacuum
energy that we focus on, a necessary condition for this mechanism to be
effective is that in the original vacuum. A vanishing
ameliorates the cosmological constant problem and is a
necessary element in the stability of the no-scale mechanism.Comment: 7 pages, no figures, LaTe
Light dynamics in glass-vanadium dioxide nanocomposite waveguides with thermal nonlinearity
We address the propagation of laser beams in Si02-VO2 nanocomposite
waveguides with thermo-optical nonlinearity. We show that the large
modifications of the absorption coefficient as well as notable changes of
refractive index of VO2 nanoparticles embedded into the SiO2 host media that
accompany the semiconductor-to-metal phase transition may lead to optical
limiting in the near-infrared wave range.Comment: 13 pages, 3 figures, to appear in Optics Letter
The Impact of Imports on Price-Cost Margins: An Empirical Illustration
This article decomposes the impact of imports on domestic price-cost margins into separate price and cost effects. Using data from 24 food-processing industries, the empirical results show that although the direct impact of imports on prices is always negative, a positive net impact on price-cost margins occurs in industries characterized by low own-price elasticity of demand and diseconomies of scale. Further results show that the disciplining effect of imports is more preponderant the lower the degree of domestic competition.Market power, imports, market structure, international trade, food industry, Agribusiness, Demand and Price Analysis, International Relations/Trade,
Direct detection of dark matter in SU(5)xU(1) supergravity
We compute the scattering rates for the lightest neutralino in the
forthcoming germanium detector and a proposed
lead detector , within the framework of
supergravity. We find that in only a small portion (\lsim10\%) of the
parameter spaces of this class of models, are the rates in the germanium
detector above the expected initial experimental sensitivity of 0.1
events/kg/day. However, a much larger portion (\lsim40\%) of the parameter
spaces could be probed with an improved background rejection capability (0.01
events/kg/day) and/or a more sensitive detector .Comment: 10 pages, Latex, 4 figures included (uuencoded
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