21,559 research outputs found

    Electroweak Limits on Non-Universal Z' Bosons

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    Many types of physics beyond the standard model include an extended electroweak gauge group. If these extensions are associated with flavor symmetry breaking, the gauge interactions will not be flavor-universal. In this note we update the bounds placed by electroweak data on the existence of flavor non-universal extensions to the standard model in the context of topcolor assisted technicolor (TC2), noncommuting extended technicolor (NCETC), and the ununified standard model (UUM). In the first two cases the extended gauge interactions couple to the third generation fermions differently than to the light fermions, while in the ununified standard model the gauge interactions couple differently to quarks and leptons. The extra SU(2) triplet of gauge bosons in NCETC and UUM models must be heavier than about 3 TeV, while the extra Z boson in TC2 models must be heavier than about 1 TeV.Comment: 17 pages, 5 figures; added references; updated figure

    Diophantine approximation in Banach spaces

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    In this paper, we extend the theory of simultaneous Diophantine approximation to infinite dimensions. Moreover, we discuss Dirichlet-type theorems in a very general framework and define what it means for such a theorem to be optimal. We show that optimality is implied by but does not imply the existence of badly approximable points

    Testing Extended Technicolor With RbR_b

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    We review the connection between mtm_t and the ZbbˉZb\bar b vertex in ETC models and demonstrate the power of the resulting experimental constraint on models with weak-singlet ETC bosons. Some efforts to bring ETC models into agreement with experimental data on the ZbbˉZb\bar b vertex are mentioned, and the most promising one (non-commuting ETC) is discussed in detail.Comment: Talk given by E.H. Simmons at the Yukawa International Seminar `95 in Kyoto, 21-26 August, 1995 and at the International Symposium on Heavy Flavor and Electroweak Theory in Beijing, 17-19 August, 1995. Latex (uses PTPTeX.sty and epsf). 9 pages. 1 figure. Full postscript version available at http://smyrd.bu.edu/ . (minor typos corrected

    Debt and Risk Preference: A Household Level Analysis

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    We explore the relationship between risk preference and the level of unsecured debt at the household level within the context of a two period theoretical framework, which predicts that debt is a function of risk aversion. We test the predictions of our theoretical framework for a sample of households drawn from the U.S. Panel Study of Income Dynamics (PSID) and the U.S. Survey of Consumer Finances (SCF). Using a sequence of questions from the 1996 PSID and the 1989 to 2004 SCF, we construct measures of risk preference allowing us to explore the implications of interpersonal differences in risk preference for the accumulation of unsecured debt at the household level. Our empirical findings, which accord with our theoretical priors, suggest that risk preference is an important determinant of the level of unsecured debt acquired at the household level with risk aversion serving to reduce the level of unsecured debt accumulated by households

    Geology of the Mohon Mountain volcanic field, Yavapai and Mohave Counties, Arizona: A preliminary report

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    Field mapping has produced a preliminary picture of Mohon Mountain as a composite volcano, in which pyroclastic ash and larger tephra erupted alternately with flows of rhyodacite and dacite. An analog study which uses imagery of lunar and Martian features will compare the overall shape of the vent complex, including its breached southern flank and satellite vents, to similar landforms found on Mars and the Moon which are believed to have formed similar processes. Ash flow sheets were hypothesized to comprise the outer slopes of Olympus Mons suggesting that explosive eruptions which are more volatile-rich than those which produce basalt flows are not confined to terrestrial settings but may also be found on bodies such as Mars, which have a thicker crust and deeper magma source in the mantle. The analog study will explore further evidence for explosive eruptions on Mars and the Moon

    An electric quadrupole transition in the A1pi - X1sigma system of CO

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    Electric quadrupole transition in carbon monoxid

    Condensate Enhancement and D-Meson Mixing in Technicolor Theories

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    Since the pioneering work of Eichten and Lane it has been known that the scale of the interactions responsible for the generation of the strange-quark mass in extended technicolor theories must, absent any "GIM-like" mechanism for suppressing flavor-changing neutral currents, be greater than of order 1000 TeV. In this note we point out that the constraint from the neutral D-meson system is now equally strong, implying that the charm quark mass must also arise from flavor dynamics at a scale this high. We then quantify the degree to which the technicolor condensate must be enhanced in order to yield the observed quark masses, if the extended technicolor scale is of order 1000 TeV. Our results are intended to provide a framework in which to interpret and apply the results of lattice studies of conformal strongly interacting gauge theories, and the corresponding numerical measurements of the anomalous dimension of the mass operator in candidate theories of "walking" technicolor.Comment: 6 pages, references added and re-ordere
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