14 research outputs found
Regularization Independent Analysis of the Origin of Two Loop Contributions to N=1 Super Yang-Mills Beta Function
We present a both ultraviolet and infrared regularization independent
analysis in a symmetry preserving framework for the N=1 Super Yang-Mills beta
function to two loop order. We show explicitly that off-shell infrared
divergences as well as the overall two loop ultraviolet divergence cancel out
whilst the beta function receives contributions of infrared modes.Comment: 7 pages, 2 figures, typos correcte
Supersymmetric Regularization, Two-Loop QCD Amplitudes and Coupling Shifts
We present a definition of the four-dimensional helicity (FDH) regularization
scheme valid for two or more loops. This scheme was previously defined and
utilized at one loop. It amounts to a variation on the standard 't
Hooft-Veltman scheme and is designed to be compatible with the use of helicity
states for "observed" particles. It is similar to dimensional reduction in that
it maintains an equal number of bosonic and fermionic states, as required for
preserving supersymmetry. Supersymmetry Ward identities relate different
helicity amplitudes in supersymmetric theories. As a check that the FDH scheme
preserves supersymmetry, at least through two loops, we explicitly verify a
number of these identities for gluon-gluon scattering (gg to gg) in
supersymmetric QCD. These results also cross-check recent non-trivial two-loop
calculations in ordinary QCD. Finally, we compute the two-loop shift between
the FDH coupling and the standard MS-bar coupling, alpha_s. The FDH shift is
identical to the one for dimensional reduction. The two-loop coupling shifts
are then used to obtain the three-loop QCD beta function in the FDH and
dimensional reduction schemes.Comment: 44 pages, minor corrections and clarifications include
Factorization of integrals, defining the beta-function, into integrals of total derivatives in N=1 SQED, regularized by higher derivatives
Some calculations in supersymmetric theories, made with the higher derivative
regularization, show that the beta-function is given by integrals of total
derivatives. This is qualitatively explained for the N=1 supersymmetric
electrodynamics in all orders.Comment: 14 page
Drivers of local extinction risk in alpine plants under warming climate
The scarcity of local plant extinctions following recent climate change has been explained by demographic inertia and lags in the displacement of resident species by novel species, generating an ‘extinction debt’. We established a transplant experiment to disentangle the contribution of these processes to the local extinction risk of four alpine plants in the Swiss Alps. Projected population growth (λ) derived from integral projection models was reduced by 0.07/°C of warming on average, whereas novel species additionally decreased λ by 0.15 across warming levels. Effects of novel species on predicted extinction time were greatest at warming < 2 °C for two species. Projected population declines under both warming and with novel species were primarily driven by increased mortality. Our results suggest that extinction debt can be explained by a combination of demographic inertia and lags in novel species establishment, with the latter being particularly important for some species under low levels of warming.ISSN:1461-023XISSN:1461-024
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Consumo, digestibilidade e balanço de nitrogênio em novilhos alimentados com cama de frango e suplemento à base de microbiota ruminal liofilizada Intake, digestibility and nitrogen balance of steers fed broiler litter and supplement based on lyophilized ruminal microbiota
Este experimento foi realizado para avaliar o efeito de dois nÃveis de cama de frango (15,0 e 30,0%), associada ou não a um suplemento à base de microbiota ruminal liofilizada de bovinos adultos (0 e 10 g/animal•dia), na alimentação de novilhos Holandês/Zebu. Quatro novilhos fistulados no rúmen e abomaso foram distribuÃdos em um quadrado latino 4 x 4 em arranjo fatorial e alimentados individualmente à vontade. O consumo e as digestibilidades totais e parciais dos nutrientes foram avaliados. Não houve efeito do nÃvel de cama de frango sobre o consumo e os coeficientes de digestibilidade da matéria seca (MS), matéria orgânica (MO) e fibra em detergente neutro (FDN). O aumento do nÃvel de cama de frango na dieta elevou o coeficiente de digestibilidade intestinal e total da proteÃna bruta (PB), porém, quando se adicionou o suplemento à dieta com 15,0% de cama de frango, a digestibilidade intestinal aumentou e à quela contendo 30,0% diminuiu. Quando se adicionou o suplemento à dieta com 15,0% de cama de frango, o coeficiente de digestibilidade total não sofreu efeito, mas diminuiu para a dieta com 30%. A ingestão diária de 10 g do suplemento, por animal, não alterou o consumo e os coeficientes de digestibilidade da MS, MO e FDN.<br>This experiment was conducted to evaluate the effect of two levels of broiler litter (15.0 and 30.0%), associated or not to a supplement based on bovine lyophilized ruminal microbiota (0 and 10 g/animal•day), in the Holstein Zebu steers feeding. Four steers with ruminal and abomasal fistulae were allotted to a 4 x 4 latin square in a factorial arrangement and individually fullfed. The intake and total and partial digestibilities were evaluated. There was no effect of broiler litter level on the intake and coefficients of digestibilities of dry matter (DM), organic matter (OM) and neutral detergent fiber (NDF). The increase of the level of broiler litter in the diet increased the total and intestinal crude protein (CP) digestibility coefficient, however, when the supplement was added to the diet containing 15.0% of broiler litter, the intestinal digestibility increased, and that of 30.0% decreased. When the supplement was added to the diet containing 15.0% broiler litter, the total digestibility coefficient did not show effect, but decreased for the diet with 30.0%. The daily intake of 10 g of supplement per animal did not affect the intake and the coefficient of digestibilities of DM, OM and NDF