Optimal renormalization and the extraction of the strange quark mass from moments of the τ\tau-decay spectral function

We introduce an optimal renormalization group analysis pertinent to the analysis of polarization functions associated with the $s$-quark mass relevant in $\tau$-decay. The technique is based on the renormalization group invariance constraints which lead to closed form summation of all the leading and next-to-leading logarithms at each order in perturbation theory. The new perturbation series exhibits reduced sensitivity to the renormalization scale and improved behavior in the complex plane along the integration contour. Using improved experimental and theory inputs, we have extracted the value of the strange quark mass $m_s(2{\rm GeV}) = 106.70 \pm 9.36~{\rm MeV}$ and $m_s(2{\rm GeV}) = 74.47 \pm 7.77~{\rm MeV}$ from presently available ALEPH and OPAL data respectively. These determinations are in agreement with the determinations in other phenomenological methods and from the lattice.Comment: 12 pages, 4 tables, 7 figures, v2 corresponds to version to appear in Physical Review

Electromagnetic charge radius of the pion at high precision

We present a determination of the pion charge radius from high precision data on the pion vector form factor from both timelike and spacelike regions, using a novel formalism based on analyticity and unitarity. At low energies, instead of the poorly known modulus of the form factor, we use its phase, known with high accuracy from Roy equations for $\pi\pi$ elastic scattering via the Fermi-Watson theorem. We use also the values of the modulus at several higher timelike energies, where the data from $e^+e^-$-annihilation and $\tau$-decay are mutually consistent, as well as the most recent measurements at spacelike momenta. The experimental uncertainties are implemented by Monte-Carlo simulations. The results, which do not rely on a specific parametrization, are optimal for the given input information and do not depend on the unknown phase of the form factor above the first inelastic threshold. Our prediction for the charge radius of the pion is r_\pi=(0.657 \pm 0.003) \fm , which amounts to an increase in precision by a factor of about 2.7 compared to the PDG average.Comment: 6 pages, 2 figures, typos corrected, citations added, version accepted for publication in Physical Review Letter

Parametrization-free determination of the shape parameters for the pion electromagnetic form factor

Recent data from high statistics experiments that have measured the modulus of the pion electromagnetic form factor from threshold to relatively high energies are used as input in a suitable mathematical framework of analytic continuation to find stringent constraints on the shape parameters of the form factor at $t=0$. The method uses also as input a precise description of the phase of the form factor in the elastic region based on Fermi-Watson theorem and the analysis of the $\pi\pi$ scattering amplitude with dispersive Roy equations, and some information on the spacelike region coming from recent high precision experiments. Our analysis confirms the inconsistencies of several data on the modulus, especially from low energies, with analyticity and the input phase, noted in our earlier work. Using the data on the modulus from energies above $0.65 \,{\rm GeV}$, we obtain, with no specific parametrization, the prediction for the charge radius. The same formalism leads also to very narrow allowed ranges for the higher-order shape parameters at $t=0$, with a strong correlation among them.Comment: v2 is 11 pages long using EPJ style files, and has 8 figures; Compared to v1, number of figures has been reduced, discussion has been improved significantly, minor errors have been corrected, references have added, and the manuscript has been significantly revised; this version has been accepted for publication in EPJ

Synthesis and Characterization of Modified Magnetic Nanoparticles for Removal of Dispersed Oil in Water

This paper proposes the synthesis of materials capable of sorption oil dispersed in water. From the production of magnetic iron oxide nanoparticles, more specifically magnetite, inorganic modifications were performed using quartz and silicaalumina, in order to identify their properties and sorption capabilities of oil. The produced materials were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS), x-ray diffraction (XRD), sorption and magnetic force tests. At the end of the characterizations and tests, it was concluded that the magnetic nanoparticles were successfully modified. Regarding magnetite, the sorption capacity was outstanding, while the modifications had the same sorption capacity. And the statistical calculations obtained by ANOVA and Tukey's method, proved the difference in the sorption of the samples. In addition, it was evidenced that the higher the magnetic force, the greater is the ability to collect the spot/nanoparticle using a magnet

Biodiesel Production Using Residual Vegetable Oil and Activated by Geopolymer Matrixes with Magnetic Particles

The cooking oil, when reused in frying, undergoes a thermal degradation process that changes its physical and chemical characteristics. After repeated use of the oil, it becomes viscous and increasingly dark, it has high acidity and unpleasant odor, being inconvenient to use for new fried food because it gives unpleasant odor and taste to food and also harmful chemical characteristics to health. When these residues become unusable usually they are dumped into the sewage system and have a negative environmental impact, for example, in rainwater and sanitary sewage systems the oil mixes with the organic matter and obstructs grease boxes and pipes. Therefore, the recycling of residual vegetable oil is necessary and very useful, because it transforms the oil for other applications, for example, in this work the use of porous geopolymer with magnetic particles in the concentrations of 1%, 2%, and 3% were studied for act on the activation of the biodiesel reaction from the used cooking oil. The geopolymers with and without magnetic particles were studied using Fourrier Transform Infrared (FT-IR) and X-Ray Diffraction (XRD). The density, the kinematic viscosity, and yield of the biodiesel formation reaction were investigated. The results, calculated using analysis of variance (ANOVA) with a 95% confidence limit, indicate that all the biodiesel samples analyzed are in accordance with the kinematic viscosity value established by the Agência Nacional do Petróleo, Gás Natural e Biocombustíveis (ANP) but only samples with 0% and 1% magnetic particles have density according to the stipulated parameters

Production of Portland Cement Loaded with Polyaniline and Evaluation of Sulphidric Gas Sorption Capacity

Cements are materials based on clay and limestone. Its origin was about 4500 years ago and it is believed that they were the basis for the construction of the pyramids in Egypt. As time went by, limestone was calcined, giving origin to the Portland Cement most used today. Its applications are diverse, ranging from the construction industry to the production of sustainable materials. In this sense, this work aims to produce composites of cement loaded with polyaniline and exposure to hydrogen sulfide gas to assess the sorption capacity of this contaminant, present mainly in sewage treatment. The composites were analyzed by resistivity analysis, in order to investigate the influence of PAni in the geopolymer matrix and its ability to conduct electrical energy, after H2S sorption and gravimetry, aiming to observe the increase in mass (g) during the sorption process. All tests were performed in triplicate and the mean, standard deviation and confidence limit were calculated to obtain the reliability of the results