2,739 research outputs found

    Lorentz Violating Inflation

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    We explore the impact of Lorentz violation on the inflationary scenario. More precisely, we study the inflationary scenario in the scalar-vector-tensor theory where the vector is constrained to be unit and time like. It turns out that the Lorentz violating vector affects the dynamics of the chaotic inflationary model and divides the inflationary stage into two parts; the Lorentz violating stage and the standard slow roll stage. We show that the universe is expanding as an exact de Sitter spacetime in the Lorentz violating stage although the inflaton field is rolling down the potential. Much more interestingly, we find exact Lorentz violating inflationary solutions in the absence of the inflaton potential. In this case, the inflation is completely associated with the Lorentz violation. We also mention some consequences of Lorentz violating inflation which can be tested by observations.Comment: 7 pages, 1 figur

    Macdonald operators and homological invariants of the colored Hopf link

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    Using a power sum (boson) realization for the Macdonald operators, we investigate the Gukov, Iqbal, Kozcaz and Vafa (GIKV) proposal for the homological invariants of the colored Hopf link, which include Khovanov-Rozansky homology as a special case. We prove the polynomiality of the invariants obtained by GIKV's proposal for arbitrary representations. We derive a closed formula of the invariants of the colored Hopf link for antisymmetric representations. We argue that a little amendment of GIKV's proposal is required to make all the coefficients of the polynomial non-negative integers.Comment: 31 pages. Published version with an additional appendi

    Mineral Acquisition and Utilization Strategy of Three Tropical Forages at Different Phosphorus and Nitrogen Supply

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    A glasshouse experiment was conducted to examine mineral acquisition and utilization strategies of Brachiaria decumbens (BD), Brachiaria brizantha (BB) and Panicum maximum (PM). The plants were grown under nine treatments resulted from the combination of three levels of phosphorus (0, 25 and 50 kgP/ha) and three levels of nitrogen (25, 150 and 300 kgN/ha). BD showed the lowest value of root weight and root length per pot, but the highest efficiency of P and N uptake (P and N uptake mg / unit root weight g). On the other hand, PM showed lower mineral uptake efficiency, but the highest mineral use efficiency (dry matter production g / absorbed P and N mg). Moreover, total P and N uptake in BB was the highest, and this seems to be achieved by the multiplicative effect of moderate mineral uptake efficiency and the moderate size of the root system

    Effects of Fertilization and Legume Introduction on the Forage Production of \u3ci\u3eBrachiaria decumbens\u3c/i\u3e Pastures

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    A grazing experiment was conducted to examine the effects of P and K fertilization and legume introduction on the forage production of Brachiaria decumbens (BD) pastures. Amount of biomass, dry matter production and forage quality were evaluated on BD pastures where three treatments were applied: without maintenance fertilizer (BD-N), with maintenance fertilizer (BD-F), and BD and Stylosanthes guianensis cv. Mineirao (SG) mixture with maintenance fertilizer (BD-FL). The fertilizer application increased an annual average of biomass and the contents of P and K in the leaves. On the other hand, the legume introduction had a positive influence on crude protein and digestibility, and the effect was obvious in the rainy season. The introduction of legume also increased litter decomposition constants, although the difference in the constants among the treatments was not significant

    Issues on Generating Primordial Anisotropies at the End of Inflation

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    We revisit the idea of generating primordial anisotropies at the end of inflation in models of inflation with gauge fields. To be specific we consider the charged hybrid inflation model where the waterfall field is charged under a U(1) gauge field so the surface of end of inflation is controlled both by inflaton and the gauge fields. Using delta N formalism properly we find that the anisotropies generated at the end of inflation from the gauge field fluctuations are exponentially suppressed on cosmological scales. This is because the gauge field evolves exponentially during inflation while in order to generate appreciable anisotropies at the end of inflation the spectator gauge field has to be frozen and scale invariant. We argue that this is a generic feature, that is, one can not generate observable anisotropies at the end of inflation within an FRW background.Comment: V3: new references added, JCAP published versio

    A Note on Gauss-Bonnet Holographic Superconductors

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    We present an analytic treatment near the phase transition for the critical temperature of (3+1)-dimensional holographic superconductors in Einstein-Gauss-Bonnet gravity with backreaction. We find that the backreaction makes the critical temperature of the superconductor decrease and condensation harder. This is consistent with previous numerical results.Comment: 6 pages, typos corrected, references added, published versio

    Symmetries and Observables for BF-theories in Superspace

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    The supersymmetric version of a topological quantum field theory describing flat connections, the super BF-theory, is studied in the superspace formalism. A set of observables related to topological invariants is derived from the curvature of the superspace. Analogously to the non-supersymmetric versions, the theory exhibits a vector-like supersymmetry. The role of the vector supersymmetry and an additional new symmetry of the action in the construction of observables is explained.Comment: 11 pages, LaTe

    Pressure Dependence of Fragile-to-Strong Transition and a Possible Second Critical Point in Supercooled Confined Water

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    By confining water in nano-pores of silica glass, we can bypass the crystallization and study the pressure effect on the dynamical behavior in deeply supercooled state using neutron scattering. We observe a clear evidence of a cusp-like fragile-to-strong (F-S) dynamic transition. Here we show that the transition temperature decreases steadily with an increasing pressure, until it intersects the homogenous nucleation temperature line of bulk water at a pressure of 1600 bar. Above this pressure, it is no longer possible to discern the characteristic feature of the F-S transition. Identification of this end point with the possible second critical point is discussed.Comment: 4 pages, 3 figure

    Forage Productivity of \u3ci\u3ePanicum maximum\u3c/i\u3e Pastures in Two Different Agropastoral Systems

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    Forage productivity was evaluated for Panicum maximum pastures established after 4 years of soybean cultivation in the summer (PM-SO), and 4 years of rotation of soybeans in the summer and millet for winter grazing (PM-MI). In the PM-MI pasture, biomass and dry matter production were much lower than in the PM-SO, and the amount of copper and nitrogen in the top part of the plants in PM-MI were significantly lower than that in PM-SO. Thus, it was considered that the shortage of copper and nitrogen restricted photosynthesis and forage production in PM-MI

    Noncommutative models in patch cosmology

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    We consider several classes of noncommutative inflationary models within an extended version of patch cosmological braneworlds, starting from a maximally invariant generalization of the action for scalar and tensor perturbations to a noncommutative brane embedded in a commutative bulk. Slow-roll expressions and consistency relations for the cosmological observables are provided, both in the UV and IR region of the spectrum; the inflaton field is assumed to be either an ordinary scalar field or a Born-Infeld tachyon. The effects of noncommutativity are then analyzed in a number of ways and energy regimes.Comment: 13 pages, 8 figures. Figures 1 and 2 are included in the text, Figs. 3-8 are in a low-resolution jpeg format. These and other high-resolution figures are available upon request to the author ([email protected]). v3: corrected misprint
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