Tensor interactions and τ\tau decays

We study the effects of charged tensor weak currents on the strangeness-changing decays of the $\tau$ lepton. First, we use the available information on the $K^+_{e3}$ form factors to obtain BR$(\tau^- \rightarrow K^-\pi^0 \nu_{\tau})\sim {\cal O}(10^{-4})$ when the $K\pi$ system is produced in an antisymmetric tensor configuration. Then, we propose a mechanism for the direct production of the $K_2^*(1430)$ in $\tau$ decays. Using the current upper limit on this decay we set a bound on the symmetric tensor interactions.Comment: 13 pages, Late

Non-Gaussian numerical errors versus mass hierarchy

We probe the numerical errors made in renormalization group calculations by varying slightly the rescaling factor of the fields and rescaling back in order to get the same (if there were no round-off errors) zero momentum 2-point function (magnetic susceptibility). The actual calculations were performed with Dyson's hierarchical model and a simplified version of it. We compare the distributions of numerical values obtained from a large sample of rescaling factors with the (Gaussian by design) distribution of a random number generator and find significant departures from the Gaussian behavior. In addition, the average value differ (robustly) from the exact answer by a quantity which is of the same order as the standard deviation. We provide a simple model in which the errors made at shorter distance have a larger weight than those made at larger distance. This model explains in part the non-Gaussian features and why the central-limit theorem does not apply.Comment: 26 pages, 7 figures, uses Revte

Accurate Checks of Universality for Dyson's Hierarchical Model

Using recently developed methods, we perform high-accuracy calculations of the susceptibility near beta_c for the D=3 version of Dyson's hierarchical model. Using linear fits, we estimate the leading gamma and subleading Delta exponents. Independent estimates are obtained by calculating the first two eigenvalues of the linearized renormalization group transformation. We found gamma = 1.29914073 (with an estimated error of 10^{-8}) and, Delta=0.4259469 (with an estimated error of 10^{-7}) independently of the choice of local integration measure (Ising or Landau-Ginzburg). After a suitable rescaling, the approximate fixed points for a large class of local measure coincide accurately with a fixed point constructed by Koch and Wittwer.Comment: 9 pages, Revtex, 1 figur

High-accuracy critical exponents of O(N) hierarchical sigma models

We perform high-accuracy calculations of the critical exponent gamma and its subleading exponent for the 3D O(N) Dyson's hierarchical model, for N up to 20. We calculate the critical temperatures for the nonlinear sigma model measure. We discuss the possibility of extracting the first coefficients of the 1/N expansion from our numerical data. We show that the leading and subleading exponents agreewith Polchinski equation and the equivalent Litim equation, in the local potential approximation, with at least 4 significant digits.Comment: 4 pages, 2 Figs., uses revte

T-violation in Kμ3K_{\mu3} decay in a general two-Higgs doublet model

We calculate the transverse muon polarization in the $K^+_{\mu3}$ process arising from the Yukawa couplings of charged Higgs boson in a general two-Higgs doublet model where spontaneous violation of CP is presentComment: 6 pages, latex, accepted for publication in Phys. Rev.

A LCA and LCC analysis of pure subtractive manufacturing, wire arc additive manufacturing, and selective laser melting approaches

Funding Information: João Pedro Oliveira acknowledges funding by national funds from FCT - Fundação para a Ciência e a Tecnologia , I.P., in the scope of the projects LA/P/0037/2020. This activity has received funding from the European Institute of Innovation and Technology (EIT) – Project Smart WAAM: Microstructural Engineering and Integrated Non-Destructive Testing. This body of the European Union receives support from the European Union's Horizon 2020 - Research and Innovation Framework Programme . Publisher Copyright: © 2023 The AuthorsThe development of sustainable manufacturing solutions is gaining attention in the manufacturing sector due to increased awareness about climate change and the formulation of stricter environmental legislation. Sustainable manufacturing involves the development of solutions that are environmentally friendly and cost-effective at the same time. Considering the opportunities and limitations of metal subtractive and additive manufacturing approaches from a sustainability perspective, this study aims to compare the environmental impact and production costs associated with the manufacture of a marine propeller using pure subtractive CNC milling along with additive Wire arc additive manufacturing (WAAM) and Selective Laser Melting (SLM) approaches. Life Cycle Assessment (LCA) and Life Cycle Costing (LCC) are used to quantify the environmental and economic impacts, respectively for each manufacturing approach. Based on the LCA and LCC models formulated, and the input data collected, the WAAM approach is observed to be the most environmentally and cost-efficient approach for the marine propeller analyzed. WAAM shows an environmental impact about 2.5 times and 3.4 times lower than pure CNC milling and SLM approaches, respectively mainly due to its better material and energy efficiencies. The effect of key variables on the environmental impact and production cost such as raw material, electricity, and post-processing parameters like a material allowance for finish machining and cutting velocity is also studied to suggest the parameters ensuring sustainable performance for a particular approach. WAAM is seen to be the most economical and ecological option for a post-processing material allowance under 4 mm and the finish machining velocities below 96 m/min. Additionally, an uncertainty assessment using the Monte Carlo analysis method is also performed to give a probabilistic range of environmental impacts and production costs considering the input data uncertainties for each approach. The methodology used in this study can be applied to other additive manufacturing processes. This study can be of potential help to AM practitioners in decision-making on selecting the most sustainable approach for manufacturing their products.publishersversionpublishe