3,683 research outputs found

    A Superfield for Every Dash-Chromotopology

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    The recent classification scheme of so-called adinkraic off-shell supermultiplets of N-extended worldline supersymmetry without central charges finds a combinatorial explosion. Completing our earlier efforts, we now complete the constructive proof that all of these trillions or more of supermultiplets have a superfield representation. While different as superfields and supermultiplets, these are still super-differentially related to a much more modest number of minimal supermultiplets, which we construct herein.Comment: 13 pages, integrated illustration

    On Graph-Theoretic Identifications of Adinkras, Supersymmetry Representations and Superfields

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    In this paper we discuss off-shell representations of N-extended supersymmetry in one dimension, ie, N-extended supersymmetric quantum mechanics, and following earlier work on the subject codify them in terms of certain graphs, called Adinkras. This framework provides a method of generating all Adinkras with the same topology, and so also all the corresponding irreducible supersymmetric multiplets. We develop some graph theoretic techniques to understand these diagrams in terms of a relatively small amount of information, namely, at what heights various vertices of the graph should be "hung". We then show how Adinkras that are the graphs of N-dimensional cubes can be obtained as the Adinkra for superfields satisfying constraints that involve superderivatives. This dramatically widens the range of supermultiplets that can be described using the superspace formalism and organizes them. Other topologies for Adinkras are possible, and we show that it is reasonable that these are also the result of constraining superfields using superderivatives. The family of Adinkras with an N-cubical topology, and so also the sequence of corresponding irreducible supersymmetric multiplets, are arranged in a cyclical sequence called the main sequence. We produce the N=1 and N=2 main sequences in detail, and indicate some aspects of the situation for higher N.Comment: LaTeX, 58 pages, 52 illustrations in color; minor typos correcte

    New massive supergravity multiplets

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    We present new off-shell formulations for the massive superspin-3/2 multiplet. In the massless limit, they reduce respectively to the old minimal (n=-1/3) and non-minimal (n1/3,0n\neq -1/3, 0) linearized formulations for 4D N=1 supergravity. Duality transformations, which relate the models constructed, are derived.Comment: 18 pages, LaTeX; v2: minor changes, references adde

    The Real Anatomy of Complex Linear Superfields

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    Recent work on classicication of off-shell representations of N-extended worldline supersymmetry without central charges has uncovered an unexpectedly vast number--trillions of even just (chromo)topology types--of so called adinkraic supermultiplets. Herein, we show by explicit analysis that a long-known but rarely used representation, the complex linear supermultiplet, is not adinkraic, cannot be decomposed locally, but may be reduced by means of a Wess-Zumino type gauge. This then indicates that the already unexpectedly vast number of adinkraic off-shell supersymmetry representations is but the proverbial tip of the iceberg.Comment: 21 pages, 4 figure

    Seasonal variability of Indonesian rainfall in ECHAM4 simulations and in the reanalyses: The role of ENSO

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    A study on the skill of the atmospheric general circulation model ECHAM version 4 and two reanalyses in simulating the Indonesian rainfall is presented with comparisons to 30 years of rain gauge data. The reanalyses are those performed by the European Centre for Medium-Range Weather Forecasts and of the National Centers for Environmental Predic- tion jointly with National Center for Atmospheric Research. This study investigates the skill of the reanalyses and ECHAM4 with regard to regional, annual and interannual variability of rainfall and its responses to El Ni˜ no-Southern Oscillation (ENSO) events. The study is conducted at two resolutions, T42 and T106. A new regionalization method called the double correlation method is introduced. With this method, the Maritime Continent is divided into three climate regions, the south mon- soonal, the northwest semi-monsoonal and the Molucca anti-monsoonal region. Except over Molucca, the reanalyses and ECHAM4 simulate these annual rainfall patterns quite well. The three regions are used to study the variability of Indonesian rainfall and to mea- sure the skills of the reanalyses and ECHAM4. The skill of rainfall simulations in Indonesia depends on the region, month and season, and the distribution of land and sea. Higher sim- ulation skills are confined to years with ENSO events. Except for the region of northwest Indonesia, the rainfall from June (Molucca) and July (south Indonesia) to November is in- fluenced by ENSO, and it is more sensitive to El Ni˜ no than La Ni˜ na events. The observations show that the Moluccan region is more sensitive to ENSO, receives a longer ENSO impact and receives the earliest ENSO impact in June. The ENSO impact will diminish in Decem- ber. It is found that the reanalyses and the climate model simulate the seasonal variability better than the monthly one. The seasonal skill is the highest in June/July/August, followed by September/October/November, December/January/February and March/April/May. The correlations usually break down in April (for monthly analysis) or in spring (for seasonal analysis). In general the performance of ECHAM4 is poor, but in ENSO sensitive regions and during ENSO events, it is comparable to the reanalyses. The introduction of a higher resolution land-sea mask improves the model performance. Besides rainfall variability, signatures of the ENSO impact, the spring correlation breakdown and annual cycles are better represented by the higher resolution model

    Unimodular cosmology and the weight of energy

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    Some models are presented in which the strength of the gravitational coupling of the potential energy relative to the same coupling for the kinetic energy is, in a precise sense, adjustable. The gauge symmetry of these models consists of those coordinate changes with unit jacobian.Comment: LaTeX, 23 pages, conclusions expanded. Two paragraphs and a new reference adde

    Embedding (R+R^2)-Inflation into Supergravity

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    We find the natural embedding of the (R+R^2)-inflationary model into the recently constructed N=1 F(\cal R)-supergravity. It gives a simple and viable realization of chaotic inflation in supergravity. The only requirement for a slow-roll inflation is the existence of the (\cal R)^3-term with an anomalously large coefficient in Taylor expansion of the F(\cal R) function, where \cal R is the covariantly-chiral scalar supercurvature superfield.Comment: 4 pages, revtex, no figures (very minor additions, a reference added

    Effective Symmetries of the Minimal Supermultiplet of N = 8 Extended Worldline Supersymmetry

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    A minimal representation of the N = 8 extended worldline supersymmetry, known as the `ultra-multiplet', is closely related to a family of supermultiplets with the same, E(8) chromotopology. We catalogue their effective symmetries and find a Spin(4) x Z(2) subgroup common to them all, which explains the particular basis used in the original construction. We specify a constrained superfield representation of the supermultiplets in the ultra-multiplet family, and show that such a superfield representation in fact exists for all adinkraic supermultiplets. We also exhibit the correspondences between these supermultiplets, their Adinkras and the E(8) root lattice bases. Finally, we construct quadratic Lagrangians that provide the standard kinetic terms and afford a mixing of an even number of such supermultiplets controlled by a coupling to an external 2-form of fluxes.Comment: 13 Figure

    Genetic Improvement of Bermudagrass for Hay Producers

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    Bermudagrass (Cynodon spp.) is considered the most valuable warm-season perennial grass for hay producers in the Southeastern United States. Bermudagrass genotypes have overall good forage quality, high yields, and store well. However, there are challenges to producing good hay for the market. First, early green-up in the spring is needed to allow for four to five productive clippings during the summer. When first establishing production fields, quick emergence and cover are important for reducing weeds. Forage bermudagrass is somewhat tolerant to drought, however, low rainfall substantially reduces yields. If rainfall is too abundant, it is difficult to have timely curing in the field for baling. This is especially true for the higher quality thick-stemmed cultivars such as Tifton 85. More recently, the bermudagrass stem maggot (BSM, Atherigona reversura) has caused yield reductions and reduced net income for hay producers. Plant breeding has attempted to address all these issues. This talk will highlight some areas of research that has been done over the past few decades to improve bermudagrass for hay production
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