19,078 research outputs found

    Update on the Pyramid Scheme

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    We summarize recent work in which we attempt to make a consistent model of LHC physics, from the Pyramid Scheme. The models share much with the NMSSM, in particular, enhanced tree level contributions to the Higgs mass and a preference for small tan {\beta}. There are 3 different singlet fields, and a new strongly coupled gauge theory, so the constraints of perturbative unification are quite different. We outline our general approach to the model, which contains a Kahler potential for three of the low energy fields, which is hard to calculate. Detailed calculations, based on approximations to the Kahler potential, will be presented in a future publication.Comment: LaTeX 2e/ 9 page

    UK household portfolios

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    This paper presents a detailed analysis of the composition of household portfolios, usingboth aggregate and micro-data. Among the key findings are that:• Most household wealth is held in the form of housing and pensions. Over time, there hasbeen a shift away from housing towards financial assets, driven largely by the growth inlife and pension funds.• Liquid financial wealth (excluding life and pension funds) is not predominantly held inrisky form. By far the most commonly held asset is an interest-bearing account at a bankor building society account. Of people with positive (liquid) financial wealth, more thanhalf is held in savings accounts.• The importance of risky assets in an individual’s portfolio varies according to theircharacteristics. The unconditional portfolio share held in risky assets (i.e. averagedacross those with and without any risky assets) rises with both age and total financialwealth. However, most of the variation in unconditional portfolio shares is due todifferences in ownership rates as opposed to the proportion of the portfolio held in riskyassets. Looking only at the people within each wealth decile who have risky assets, theconditional portfolio share is relatively constant across wealth, suggesting a possible rolefor entry costs or other fixed costs in explaining portfolio holdings. Multivariate analysisshows that the conditional portfolio share in risky assets actually falls with age asclassical portfolio theory would predict.• Finally, the tax treatment of savings products has an effect on portfolio choice. Separateprobit regressions for the ownership of tax-favoured assets and similar assets without thetax exemption, show that, controlling for other factors, marginal tax rates are important in determining asset ownership. These results are in accordance with those found by Poterba in the US

    A dynamic model of democratic elections in multidimensional policy spaces

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    We propose a general model of repeated elections. In each period, a challenger is chosen from the electorate to run against an incumbent politician in a majority-rule election, and the winner then selects a policy from a multidimensional policy space. Individual policy preferences are private information, whereas policy choices are publicly observable. We prove existence and continuity of equilibria in "simple" voting and policy strategies; we provide examples to show the variety of possible equilibrium patterns in multiple dimensions; we analyze the effects of patience and office-holding benefits on the persistence of policies over time; and we identify relationships between equilibrium policies and the core of the underlying voting game. As a byproduct of our analysis, we show how equilibrium incentives maylead elected representatives to make policy compromises, even when binding commitments are unavailable. We provide an informational story for incumbency advantage. Finally, we give an asymptotic version of the median voter theorem for the one-dimensional model as voters become-arbitrarily patient

    A Stringy Correspondence Principle in Cosmology

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    We study a d-dimensional FRW universe, containing a perfect fluid with p = w \rho and \frac{1} {d - 1} \le w \le 1, and find a correspondence principle similar to that of Horowitz and Polchinski in the black hole case. This principle follows quite generally from thermodynamics and the conservation of energy momentum tensor, and can be stated along similar lines as in the black hole case: ``When the temperature T of the universe becomes of order string scale the universe state becomes a highly excited string state. At the transition, the entropies and energies of the universe and strings differ by factors of {\cal O}(1).'' Such a matching is absent for w \ne 1 if the transition is assumed to be when the curvature or the horizon length is of order string scale.Comment: 14 pages. V2: More references added and some minor textual modifications mad

    A General Bargaining Model of Legislative Policy-making

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    We present a general model of legislative bargaining in which the status quo is an arbitrary point in a multidimensional policy space. In contrast to other bargaining models, the status quo is not assumed to be bad for all legislators, and delay may be Pareto efficient. We prove existence of stationary equilibria. We show that if all legislators are risk averse or if even limited transfers are possible, then delay is only possible if the status quo lies in the core. Thus, we expect immediate agreement in multidimensional models, where the core is typically empty. In one dimension, delay is possible if and only if the status quo lies in the core of the voting rule, and then it is the only possible outcome. Our comparative statics analysis yield two noteworthy insights: moderate status quos imply moderate policy outcomes, and legislative patience implies policy moderation

    Ion thruster accelerator system Patent

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    Development and characteristics of ion thruster accelerator with single glass coated grid to provide increased ion extraction capability and larger diameter accelerator syste

    Making Sense Of The New Cosmology

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    Over the past three years we have determined the basic features of the Universe -- spatially flat; accelerating; comprised of 1/3 a new form of matter, 2/3 a new form of energy, with some ordinary matter and a dash of massive neutrinos; and apparently born from a burst of rapid expansion during which quantum noise was stretched to astrophysical size seeding cosmic structure. The New Cosmology greatly extends the highly successful hot big-bang model. Now we have to make sense of all this: What is the dark matter particle? What is the nature of the dark energy? Why this mixture? How did the matter -- antimatter asymmetry arise? What is the underlying cause of inflation (if it indeed occurred)?Comment: 17 pages Latex (sprocl.sty). To appear in the Proceedings of 2001: A Spacetime Odyssey (U. Michigan, May 2001, World Scientific

    A Pyramid Scheme for Particle Physics

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    We introduce a new model, the Pyramid Scheme, of direct mediation of SUSY breaking, which is compatible with the idea of Cosmological SUSY Breaking (CSB). It uses the trinification scheme of grand unification and avoids problems with Landau poles in standard model gauge couplings. It also avoids problems, which have recently come to light, associated with rapid stellar cooling due to emission of the pseudo Nambu-Goldstone Boson (PNGB) of spontaneously broken hidden sector baryon number. With a certain pattern of R-symmetry breaking masses, a pattern more or less required by CSB, the Pyramid Scheme leads to a dark matter candidate that decays predominantly into leptons, with cross sections compatible with a variety of recent observations. The dark matter particle is not a thermal WIMP but a particle with new strong interactions, produced in the late decay of some other scalar, perhaps the superpartner of the QCD axion, with a reheat temperature in the TeV range. This is compatible with a variety of scenarios for baryogenesis, including some novel ones which exploit specific features of the Pyramid Scheme.Comment: JHEP Latex, 32 pages, 1 figur
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