Search results for "Sigma"

Dispersion relation bounds forππscattering

2008

Axiomatic principles such as analyticity, unitarity, and crossing symmetry constrain the second derivative of the $\ensuremath{\pi}\ensuremath{\pi}$ scattering amplitudes in some channels to be positive in a region of the Mandelstam plane. Since this region lies in the domain of validity of chiral perturbation theory, we can use these positivity conditions to bound linear combinations of ${\overline{l}}_{1}$ and ${\overline{l}}_{2}$. We compare our predictions with those derived previously in the literature using similar methods. We compute the one-loop $\ensuremath{\pi}\ensuremath{\pi}$ scattering amplitude in the linear sigma model (LSM) using the $\overline{\mathrm{MS}}$ scheme, a result…

The complete experiment for photoproduction of pseudoscalar mesons in a truncated partial wave analysis

2013

The complete experiment problem in the truncated partial wave analysis of pseudoscalar meson photoproduction with suppressed t-channel exchanges is investigated. The focus is set to ambiguities of the group S observables with the unpolarized differential cross section, $\sigma_0$, and the three single-spin observables, $\Sigma$, $T$ and $P$. For this purpose, the approach and formalism already worked out by Omelaenko in 1981 is revisited in this work. A numerical study using multipoles of the PWA solution MAID2007 shows how only one additional double polarization observable can resolve all ambiguities. Therefore, the possibility emerges to perform a complete experiment with only five observ…

Measurement of theb-hadron production cross section using decays toμ−D0Xfinal states inpp¯collisions ats=1.96  TeV

2009

We report a measurement of the production cross section for b hadrons in p{bar p} collisions at {radical}s = 1.96 TeV. Using a data sample derived from an integrated luminosity 83 pb{sup -1} collected with the upgraded Collider Detector (CDF II) at the Fermilab Tevatron, we analyze b hadrons, H{sub b}, partially reconstructed in the semileptonic decay mode H{sub b} {yields} {mu}{sup -} D{sup 0} X. Our measurement of the inclusive production cross section for b hadrons with transverse momentum p{sub T} > 9 GeV/c and rapidity |y| < 0.6 is {sigma} = 1.30 {micro}b {+-} 0.05 {micro}b(stat) {+-} 0.14 {micro}b(syst) {+-} 0.07 {micro}b({Beta}), where the uncertainties are statistical, systematic, a…

Weak quasielastic production of hyperons

2006

The quasielastic weak production of $\Lambda$ and $\Sigma$ hyperons from nucleons and nuclei induced by antineutrinos is studied in the energy region of some ongoing neutrino oscillation experiments in the intermediate energy region. The hyperon nucleon transition form factors determined from neutrino nucleon scattering and an analysis of high precision data on semileptonic decays of neutron and hyperons using SU(3) symmetry have been used. The nuclear effects due to Fermi motion and final state interaction effects due to hyperon nucleon scattering have also been studied. The numerical results for differential and total cross sections have been presented.

Implementation of Six Sigma in SMEs. A Case Study in Swedish Industry

2012

Many big companies today have already solid Six Sigma infrastructures. However, all over the world SMEs are only now approaching the methodology. In this presentation we expose an industrial application of a Six Sigma Black Belt project. It shows how Six Sigma was introduced and successfully implemented in a Swedish small-medium sized company. The project was carried out within the Six Sigma Black Belt course run at Chalmers University of Technology in Gothenburg. This case study is included in the book “Statistical and Managerial Techniques for Six Sigma Methodology, Theory and Application” (Wiley, 2012). The company is Structo Hydraulics AB, a manufacturing firm, located in Storfors, whic…

Statistical and managerial techniques for Six Sigma methodology. Theory and Application

2012

Application of Mathematical Models in Analysis of Heat Losses in the Buildings

2006

Physical model of heat balance for separate living room is discussed, which allows to analyse the distributions of the flow of air and temperature depending on the physical conditions and geometry. The model enables to choose the optimal surface area of building elements and their properties in order to decrease the heat losses and improve the conditions of thermal comfort. Room with bounding constructions and real dimensions is modelled that helps to understand the peculiarities of heat transfer process in the room as well as distribution of various characteristic quantities and their dependence on the different conditions. Multiple parameters are varied in 2D calculations and their influe…

The classical two-dimensional Heisenberg model revisited: An $SU(2)$-symmetric tensor network study

2021

The classical Heisenberg model in two spatial dimensions constitutes one of the most paradigmatic spin models, taking an important role in statistical and condensed matter physics to understand magnetism. Still, despite its paradigmatic character and the widely accepted ban of a (continuous) spontaneous symmetry breaking, controversies remain whether the model exhibits a phase transition at finite temperature. Importantly, the model can be interpreted as a lattice discretization of the $O(3)$ non-linear sigma model in $1+1$ dimensions, one of the simplest quantum field theories encompassing crucial features of celebrated higher-dimensional ones (like quantum chromodynamics in $3+1$ dimensio…

A New Model for Sigma-Delta Modulator Oriented to Digitally Controlled DC/DC Converter

2007

Recent research activities have shown the feasibility and advantages of using digital controller ICs specifically developed for high-frequency switching converters, highlighting a challenging future trend in Switched-mode power supplies (SMPS) applications. Up to a few years ago, the application of digital control for SMPS was impractical due to the high cost and low performance of DSP and microcontroller systems, even if the advantages that digital controllers offer were well known, such as immunity to analog component variations and ability to implement sophisticated control schemes and system diagnostics. Digital controller ICs potentially offer other advantages from the integrated desig…

Non-degenerate 1,2-silyl shift in silyl substituted alkyltrimethylcyclopentadienes

2005

Abstract The five new silanes C5Me3RSiMenCl3 − n (n = 3, R = i-Pr (5); n = 2, R = i-Pr (6); n = 2, R = s-Bu (7); n = 2, R = cyclohexyl (8); and n = 3, R = t-Bu (9)) were synthesized by reaction of 1-alkyl-2,3,4-trimethylcyclopentadienyl lithium salts with appropriate chlorosilane and characterized by NMR, MS, and IR spectra. At elevated temperatures (250–360 K), all the silanes undergo a non-degenerate sigmatropic silyl rearrangement, which generates non-equivalent structures a and b. The presence of minor structure c was observed in compounds 5 and 7 only. The Diels–Alder cycloaddition of 5 with strong dienophiles tetracyanoethylene (TCNE), and dimethylacetylenedicarboxylate (DMAD) provide…