32,269 research outputs found

    On Extended Electroweak Symmetries

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    We discuss extensions of the Standard Model through extending the electroweak gauge symmetry. An extended electroweak symmetry requires a list of extra fermionic and scalar states. The former is necessary to maintain cancellation of gauge anomalies, and largely fixed by the symmetry embedding itself. The latter is usually considered quite arbitrary, so long as a vacuum structure admitting the symmetry breaking is allowed. Anomaly cancellation may be used to link the three families of quarks and leptons together, given a perspective on flavor physics. It is illustrated lately that the kind of models may also have the so-called little Higgs mechanism incorporated. This more or less fixes the scalar sector and take care of the hierarchy problem, making such models of extended electroweak symmetries quite appealing candidates as TeV scale effective field theories.Comment: 1+8 pages of latex with ws-procs9x6.cls; talk presented at Coral Gables Conference 200

    A Carrot-and-Stick Approach to Environmental Improvement: Marrying Agri-Environmental Payments and Water Quality Regulations

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    Agri-environmental programs, such as the Environmental Quality Incentives Program, provide payments to livestock and crop producers to generate broadly defined environmental benefits and to help them comply with federal water quality regulations, such as those that require manure nutrients generated on large animal feeding operations to be spread on cropland at no greater than agronomic rates. We couch these policy options in terms of agri-environmental "carrots" and regulatory "sticks," respectively. The U.S. agricultural sector is likely to respond to these policies in a variety of ways. Simulation analysis suggests that meeting nutrient standards would result in decreased levels of animal production, increased prices for livestock and poultry products, increased levels of crop production, and water quality improvements. However, estimated impacts are not homogeneous across regions. In regions with relatively less cropland per ton of manure produced, the impacts of these policies are more pronounced.Environmental Economics and Policy,

    WHEN THE !%$? HITS THE LAND: IMPLICATIONS FOR US AGRICULTURE AND ENVIRONMENT WHEN LAND APPLICATION OF MANURE IS CONSTRAINED

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    Confined animal production in the U.S. and its associated discharge of manure nutrients into area waters is considered a leading contributor to current water quality impairments. A common option to mitigate these impairments is to limit land application of manure. This paper evaluates the implications of alternative land application constraints for U.S. agriculture and the environment at the regional and sector level. The results suggest that when these constraints are particularly binding, due to minimal acceptance of manure as a substitute for commercial fertilizer, potentially large and unanticipated changes in returns to agricultural production and water quality may occur. Furthermore, we find that some of the cost of meeting the land application constraints will be passed on to consumers through higher prices and to a portion of rural economies through lower production rates and labor expenditures.Environmental Economics and Policy, Livestock Production/Industries,

    The Delta-Delta Intermediate State in 1S0 Nucleon-Nucleon Scattering From Effective Field Theory

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    We examine the role of the Delta-Delta intermediate state in low energy NN scattering using effective field theory. Theories both with and without pions are discussed. They are regulated with dimensional regularization and MSbar subtraction. We find that the leading effects of the Delta-Delta state can be absorbed by a redefinition of the contact terms in a theory with nucleons only. It does not remove the requirement of a higher dimension operator to reproduce data out to moderate momentum. The explicit decoupling of the Delta-Delta state is shown for the theory without pions.Comment: 16 pages, 3 figures, uses harvma

    CP Violation from a Higher Dimensional Model

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    It is shown that Randall-Sundrum model has the EDM term which violates the CP-symmetry. The comparison with the case of Kaluza-Klein theory is done. The chiral property, localization, anomaly phenomena are examined. We evaluate the bulk quantum effect using the method of the induced effective action. This is a new origin of the CP-violation.Comment: 15pages, Proc. of Int. Workshop on "Neutrino Masses and Mixings"(Dec.17-19,2006,Univ.of Shizuoka,Japan

    Inequalities for low-energy symmetric nuclear matter

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    Using effective field theory we prove inequalities for the correlations of two-nucleon operators in low-energy symmetric nuclear matter. For physical values of operator coefficients in the effective Lagrangian, the S = 1, I = 0 channel correlations must have the lowest energy and longest correlation length in the two-nucleon sector. This result is valid at nonzero density and temperature.Comment: 9 page

    A New Experiment to Study Hyperon CP Violation and the Charmonium System

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    Fermilab operates the world's most intense antiproton source, now exclusively dedicated to serving the needs of the Tevatron Collider. The anticipated 2009 shutdown of the Tevatron presents the opportunity for a world-leading low- and medium-energy antiproton program. We summarize the status of the Fermilab antiproton facility and review physics topics for which a future experiment could make the world's best measurements.Comment: 16 pages, 3 figures, to appear in Proceedings of CTP symposium on Supersymmetry at LHC: Theoretical and Experimental Perspectives, The British University in Egypt, Cairo, Egypt, 11-14 March 200

    The Long and Short of Nuclear Effective Field Theory Expansions

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    Nonperturbative effective field theory calculations for NN scattering seem to break down at rather low momenta. By examining several toy models, we clarify how effective field theory expansions can in general be used to properly separate long- and short-range effects. We find that one-pion exchange has a large effect on the scattering phase shift near poles in the amplitude, but otherwise can be treated perturbatively. Analysis of a toy model that reproduces 1S0 NN scattering data rather well suggests that failures of effective field theories for momenta above the pion mass can be due to short-range physics rather than the treatment of pion exchange. We discuss the implications this has for extending the applicability of effective field theories.Comment: 22 pages, 9 figures, references corrected, minor modification

    The Influence of Thermal Pressure on Equilibrium Models of Hypermassive Neutron Star Merger Remnants

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    The merger of two neutron stars leaves behind a rapidly spinning hypermassive object whose survival is believed to depend on the maximum mass supported by the nuclear equation of state, angular momentum redistribution by (magneto-)rotational instabilities, and spindown by gravitational waves. The high temperatures (~5-40 MeV) prevailing in the merger remnant may provide thermal pressure support that could increase its maximum mass and, thus, its life on a neutrino-cooling timescale. We investigate the role of thermal pressure support in hypermassive merger remnants by computing sequences of spherically-symmetric and axisymmetric uniformly and differentially rotating equilibrium solutions to the general-relativistic stellar structure equations. Using a set of finite-temperature nuclear equations of state, we find that hot maximum-mass critically spinning configurations generally do not support larger baryonic masses than their cold counterparts. However, subcritically spinning configurations with mean density of less than a few times nuclear saturation density yield a significantly thermally enhanced mass. Even without decreasing the maximum mass, cooling and other forms of energy loss can drive the remnant to an unstable state. We infer secular instability by identifying approximate energy turning points in equilibrium sequences of constant baryonic mass parametrized by maximum density. Energy loss carries the remnant along the direction of decreasing gravitational mass and higher density until instability triggers collapse. Since configurations with more thermal pressure support are less compact and thus begin their evolution at a lower maximum density, they remain stable for longer periods after merger.Comment: 20 pages, 12 figures. Accepted for publication in Ap
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