1,169 research outputs found
The Standard Model and its Generalizations in Epstein-Glaser Approach to Renormalization Theory II: the Fermion Sector and the Axial Anomaly
We complete our study of non-Abelian gauge theories in the framework of
Epstein-Glaser approach to renormalization theory including in the model an
arbitrary number of Dirac Fermions. We consider the consistency of the model up
to the third order of the perturbation theory. In the second order we obtain
pure group theoretical relations expressing a representation property of the
numerical coefficients appearing in the left and right handed components of the
interaction Lagrangian. In the third order of the perturbation theory we obtain
the the condition of cancellation of the axial anomaly.Comment: 38 pages, LATEX 2e, extensive rewritting, some errors eliminate
The Interaction of Quantum Gravity with Matter
The interaction of (linearized) gravitation with matter is studied in the
causal approach up to the second order of perturbation theory. We consider the
generic case and prove that gravitation is universal in the sense that the
existence of the interaction with gravitation does not put new constraints on
the Lagrangian for lower spin fields. We use the formalism of quantum off-shell
fields which makes our computation more straightforward and simpler.Comment: 25 page
EXPERIMENTAL RESEARCH ON DETERMINATION OF DEFORMATIONS IN THE CUTTING PROCESS IN WET SANDY SOILS
The active parts of tillage equipment must be checked for wear resistance, under different conditions working with the soil, so that the average life span should be determined wear resistance, to ensure timely changes of parts. Research in the field has shown that there are at least two main forces acting on the active parts: impact and friction, the action of these forces causes wear. In order to test the tillage knives in laboratory conditions, was used a stand made by INMA Bucharest. With the help of this stand, the deformations in the cutting process were determined in different working conditions: at a certain working speed and at a certain humidity of the sandy soil
Properties of the Scalar Universal Equations
The variational properties of the scalar so--called ``Universal'' equations
are reviewed and generalised. In particular, we note that contrary to earlier
claims, each member of the Euler hierarchy may have an explicit field
dependence. The Euler hierarchy itself is given a new interpretation in terms
of the formal complex of variational calculus, and is shown to be related to
the algebra of distinguished symmetries of the first source form.Comment: 15 pages, LaTeX articl
Self-Phase-Matched Second-Harmonic and White-Light Generation in a Biaxial Zinc Tungstate Single Crystal
Second-order nonlinear optical materials are used to generate new frequencies by exploiting second-harmonic generation (SHG), a phenomenon where a nonlinear material generates light at double the optical frequency of the input beam. Maximum SHG is achieved when the pump and the generated waves are in phase, for example through birefringence in uniaxial crystals. However, applying these materials usually requires a complicated cutting procedure to yield a crystal with a particular orientation. Here we demonstrate the first example of phase matching under the normal incidence of SHG in a biaxial monoclinic single crystal of zinc tungstate. The crystal was grown by the micro-pulling-down method with the (102) plane perpendicular to the growth direction. Additionally, at the same time white light was generated as a result of stimulated Raman scattering and multiphoton luminescence induced by higher-order effects such as three-photon luminescence enhanced by cascaded third-harmonic generation. The annealed crystal offers SHG intensities approximately four times larger than the as grown one; optimized growth and annealing conditions may lead to much higher SHG intensities
Growth performance, carcass traits, and blood biochemistry of broiler chicks fed with low-fibre sunflower meal and phytase
This study was designed to evaluate the impact of graded replacements of soybean meal (SBM) with low-fibre sunflower meal (LF-SFM), with and without phytase supplementation, on growth performance, carcass traits, and plasma profile of broilers. A total of 800 mixed sex one-day-old broiler chicks (Cobb 500) were randomly assigned to eight dietary treatment groups (five replicates each) in a 4 × 2 factorial arrangement, including four levels of LF-SFM (0%, 25%, 50%, and 75% to replace SBM) and two levels of microbial phytase (0 or 0.2 g/kg diet). Feed conversion ratio (FCR), and bodyweight gain (BWG) were decreased significantly if LF-SFM replaced more than 25% SBM. There was no significant effect between the interaction of the main factors (LF-SFM × phytase) on growth performance during the starter, grower, finisher and the overall period. The addition of phytase had no beneficial effects on performance traits. Carcass traits were not influenced by feeding LF-SFM or enzyme addition. However, increasing the level of LF-SFM (50% and 75%, respectively) in diets reduced the abdominal fat, whereas the weight of the small intestine was increased. Plasma metabolic profile was not affected by LF-SFM levels in broiler diets, except for high-density lipoproteins cholesterol (HDL-C) and total cholesterol (T-Cho), which were not affected by the dietary enzyme. It is concluded that the diets with LF-SFM levels up to 25% generated growth performance and carcass traits comparable with the diet that contained SBM.Keywords: Cobb 500, digestive organs, enzyme, growth traits, low-fibre sunflower meal, plasma profil
Anyon wave equations and the noncommutative plane
The ``Jackiw-Nair'' non-relativistic limit of the relativistic anyon
equations provides us with infinite-component wave equations of the
Dirac-Majorana-Levy-Leblond type for the ``exotic'' particle, associated with
the two-fold central extension of the planar Galilei group. An infinite
dimensional representation of the Galilei group is found. The velocity operator
is studied, and the observable coordinates describing a noncommutative plane
are identified.Comment: 11 pages, typos correcte
g-engineering in hybrid rotaxanes to create AB and AB2 electron spin systems: EPR spectroscopic studies of weak interactions between dissimilar electron spin qubits
Hybrid [2]rotaxanes and pseudorotaxanes are reported where the magnetic interaction between dissimilar spins is controlled to create AB and AB2 electron spin systems,allowing independent control of weakly interacting S =1=2 centers
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