Remarks on some vacuum solutions of scalar-tensor cosmological models

We present a class of exact vacuum solutions corresponding to de Sitter and warm inflation models in the framework of scalar-tensor cosmologies. We show that in both cases the field equations reduce to planar dynamical systems with constraints. Then, we carry out a qualitative analysis of the models by examining the phase diagrams of the solutions near the equilibrium points.Comment: 12 pages, 4 figures. To be published in the Brazilian Journal of Physic

Missing Transverse-Doppler Effect in Time-Dilation Experiments with High-Speed Ions

Recent experiments with high-speed ions have investigated potential deviations from the time-dilation predicted by special relativity (SR). The main contribution of this article is to show that the SR predictions are matched by the experimental results only when the transverse Doppler effect in the observed emissions from the ions are neglected in the analysis. However, the Doppler effect in the emission cannot be neglected because it is similar to the time dilation effect. Thus, the article highlights the need to consider Doppler emission effects when validating SR time dilation using high-speed ion experiments.Comment: 3 pages, 3 figure

Performance of Dairy Goats to Alfalfa Silage Based Diets Supplemented with Different Sources of Carbohydrates

Lactating Saanen dairy goats fed alfalfa silage (AS) based diets in four 4x4 Latin Square designed experiment were studied for the effects of supplementation of three different type of carbohydrates (wheat grain, (W); sorghum grain, (SG) and dry citrus pulp, (DCP)) on milk yield, composition and chewing activities. Sixteen does (45± 10 DIM and 2.016 kg ± 0.48 4% FCM) housed indoors in individual pens in a four 4x4 experiment were fed four diets 1) AS (33.9%DM, 19.9%CP, 44.01%NDF); 2) ASW (52.4%DM, 19.8%CP, 33.7%NDF); 3) ASSG (50.9%DM, 17.9%CP, 37%NDF), 4) ASDCP (52.5%DM, 16.12%CP, 39.1%NDF) with forage-to-concentrate ratios of 100:0 or 65:35, 67:33 and 64:36 respectively. Intake of AS DM (2.78%BW) was different (P\u3c 0.05) from the other treatments (average 3.53 ±0.07 %BW). Chewing efficiency (min/g NDF per kg BW 0.75) decrease (P\u3c 0.05) as a result of AS substitution or concentrate supplementation without effect (P\u3e 0.05) of carbohydrate type or dietary level of NDF. Milk, 4%FCM and fat-protein-corrected milk yield was affected (P\u3c 0.05) by concentrate supplementation. Either milk protein content (g/l) or yield (g/day) were not affected by treatments. Body weight changes appeared related to concentrate supplementation. Supplementation increase total DM intake, decrease forage DM intake and chewing efficiency and increase producing performance without changing milk composition

Gauge and Supersymmetric Invariance of a Boundary Bagger-Lambert-Gustavsson Theory

In this paper we will discuss the effect of a having a boundary on the supersymmetric invariance and gauge invariance of the Bagger-Lambert-Gustavsson (BLG) Theory. We will show that even though the supersymmetry and gauge invariance of the original BLG theory is broken due to the presence of a boundary, it restored by the addition of suitable boundary terms. In fact, to achieve the gauge invariance of this theory, we will have to introduce new boundary degrees of freedom. The boundary theory obeyed by these new boundary degrees of freedom will be shown to be a generalization of the gauged Wess-Zumino-Witten model, with the generators of the Lie algebra replaced by the generators of the Lie 3-algebra. The gauge and supersymmetry variations of the boundary theory will exactly cancel the boundary terms generated by the gauge and supersymmetric variations of the bulk theory.Comment: 15 pages, 0 figures, accepted for publication in JHE

Noncommutative geometry induced by spin effects

In this paper we study the nonlocal effects of noncommutative spacetime on simple physical systems. Our main point is the assumption that the noncommutative effects are consequences of a background field which generates a local spin structure. So, we reformulate some simple electrostatic models in the presence of a spin-deformation contribution to the geometry of the motion, and we obtain an interesting correlation amongst the deformed area vector, the 3D noncommutative effects and the usual spin vector given in quantum mechanics framework. Remarkably we can observe that a spin-orbit coupling term comes to light on the spatial sector of a potential wrote in terms of noncommutative coordinates what indicates that bound states are particular cases in this procedure. Concerning to confined or bounded particles in this noncommutative domain we verify that the kinetic energy is modified by a deformation factor. Finally, we discuss about perspectives.Comment: 14 pages, 1 figur

Renormalization of the N=1 Abelian Super-Chern-Simons Theory Coupled to Parity-Preserving Matter

We analyse the renormalizability of an Abelian N=1 super-Chern-Simons model coupled to parity-preserving matter on the light of the regularization independent algebraic method. The model shows to be stable under radiative corrections and to be gauge anomaly free.Comment: Latex, 7 pages, no figure

Lorentz Violation in Warped Extra Dimensions

Higher dimensional theories which address some of the problematic issues of the Standard Model(SM) naturally involve some form of $D=4+n$-dimensional Lorentz invariance violation (LIV). In such models the fundamental physics which leads to, e.g., field localization, orbifolding, the existence of brane terms and the compactification process all can introduce LIV in the higher dimensional theory while still preserving 4-d Lorentz invariance. In this paper, attempting to capture some of this physics, we extend our previous analysis of LIV in 5-d UED-type models to those with 5-d warped extra dimensions. To be specific, we employ the 5-d analog of the SM Extension of Kostelecky et. al. ~which incorporates a complete set of operators arising from spontaneous LIV. We show that while the response of the bulk scalar, fermion and gauge fields to the addition of LIV operators in warped models is qualitatively similar to what happens in the flat 5-d UED case, the gravity sector of these models reacts very differently than in flat space. Specifically, we show that LIV in this warped case leads to a non-zero bulk mass for the 5-d graviton and so the would-be zero mode, which we identify as the usual 4-d graviton, must necessarily become massive. The origin of this mass term is the simultaneous existence of the constant non-zero $AdS_5$ curvature and the loss of general co-ordinate invariance via LIV in the 5-d theory. Thus warped 5-d models with LIV in the gravity sector are not phenomenologically viable.Comment: 14 pages, 4 figs; discussion added, algebra repaire