| 1. |
- Schael, S, et al.
(author)
-
Precision electroweak measurements on the Z resonance
- 2006
-
In: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 427:5-6, s. 257-454
-
Research review (peer-reviewed)abstract
- We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron-positron colliders SLC and LEP. The data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLID experiment using a polarised beam at SLC. The measurements include cross-sections, forward-backward asymmetries and polarised asymmetries. The mass and width of the Z boson, m(Z) and Gamma(Z), and its couplings to fermions, for example the p parameter and the effective electroweak mixing angle for leptons, are precisely measured: m(Z) = 91.1875 +/- 0.0021 GeV, Gamma(Z) = 2.4952 +/- 0.0023 GeV, rho(l) = 1.0050 +/- 0.0010, sin(2)theta(eff)(lept) = 0.23153 +/- 0.00016. The number of light neutrino species is determined to be 2.9840 +/- 0.0082, in agreement with the three observed generations of fundamental fermions. The results are compared to the predictions of the Standard Model (SM). At the Z-pole, electroweak radiative corrections beyond the running of the QED and QCD coupling constants are observed with a significance of five standard deviations, and in agreement with the Standard Model. Of the many Z-pole measurements, the forward-backward asymmetry in b-quark production shows the largest difference with respect to its SM expectation, at the level of 2.8 standard deviations. Through radiative corrections evaluated in the framework of the Standard Model, the Z-pole data are also used to predict the mass of the top quark, m(t) = 173(+10)(+13) GeV, and the mass of the W boson, m(W) = 80.363 +/- 0.032 GeV. These indirect constraints are compared to the direct measurements, providing a stringent test of the SM. Using in addition the direct measurements of m(t) and m(W), the mass of the as yet unobserved SM Higgs boson is predicted with a relative uncertainty of about 50% and found to be less than 285 GeV at 95% confidence level. (c) 2006 Elsevier B.V. All rights reserved.
|
|
| 2. |
- Abreu, P., et al.
(author)
-
Measurement of the gluon fragmentation function and a comparison of the scaling violation in gluon and quark jets
- 2000
-
In: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 13:4, s. 573-589
-
Journal article (peer-reviewed)abstract
- The fragmentation functions of quarks and gluons are measured in various three-jet topologies in Z decays from the full data set collected with the DELPHI detector at the Z resonance between 1992 and 995. The results at different values of transverse momentum-like scales are compared. A parameterization of the quark and gluon fragmentation functions at a fixed reference scale is given. The quark and gluon fragmentation functions show the predicted pattern of scaling violations. The scaling violation for quark jets as a function of a transverse momentum-like scale is in a good agreement with that observed in lower energy e+e- annihilation experiments. For gluon jets it appears to be significantly stronger. The scale dependences of the gluon and quark fragmentation functions agree with the prediction of the DGLAP evolution equations from which the colour factor ratio CA/CF is measured to be: CA/CF = 2.26 ± 0.09stat. ± 0.06sys. ± 0.12clus.,scale..
|
|
| 3. |
- Abreu, P., et al.
(author)
-
Study of dimuon production in photon-photon collisions and measurement of QED photon structure functions at LEP
- 2001
-
In: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 19:1, s. 15-28
-
Journal article (peer-reviewed)abstract
- Muon pair production in the process e+e- → e+e- μ+μ- is studied using the data taken at LEP1 (√s ≃ mz) with the DELPHI detector during the years 1992-1995. The corresponding integrated luminosity is 138.5 pb-1. The QED predictions have been tested over the whole Q2 range accessible at LEP1 (from several GeV2/c4 to several hundred GeV2/c4) by comparing experimental distributions with distributions resulting from Monte Carlo simulations using various generators. Selected events are used to extract the leptonic photon structure function Fγ 2. Azimuthal correlations are used to obtain information on additional structure functions, Fγ A and Fγ B, which originate from interference terms of the scattering amplitudes. The measured ratios Fγ A/Fγ 2 and FγB/Fγ 2 are significantly different from zero and consistent with QED predictions.
|
|
| 4. |
- Hertzman, S., et al.
(author)
-
Nitrogen Solubility in Alloy Systems Relevant to Stainless Steels
- 2021
-
In: Metallurgical and Materials Transactions. A. - : Springer Nature. - 1073-5623 .- 1543-1940. ; 52:9, s. 3811-3820
-
Journal article (peer-reviewed)abstract
- High-performance stainless steels are alloyed with nitrogen for several different reasons. For the austenitic grades, the kinetics of deleterious phase transformations are delayed, the strength is increased, and the corrosion resistance is improved. For duplex steels, the weldability and corrosion resistance depend directly on their nitrogen contents. Reliable databases are crucial for the development of new stainless steels and their processing. In order to calibrate the existing thermodynamic data, a series of experiments was undertaken. Several laboratory alloys in Fe–Cr–X systems, where X = Ni, Mn, Cu, were reacted with nitrogen gas at nitrogen activities 0.5 and 1 in the temperature range from 1050 °C to 1350 °C and subsequently analyzed for nitrogen solubility and phase constitution. A novel, simplified experimental technique was used, providing a dew point that is low enough to allow for fast nitrogen transport through the specimen surface, ensuring equilibrium conditions. The results are compared to thermodynamic equilibrium calculations.
|
|
| 5. |
- Larsson, Henrik, et al.
(author)
-
Oxidation of iron at 600 degrees C - experiments and simulations
- 2016
-
In: Materials and corrosion - Werkstoffe und Korrosion. - : Wiley-Blackwell. - 0947-5117 .- 1521-4176.
-
Journal article (peer-reviewed)abstract
- Pure iron has been oxidized at 600°C and 1bar in dry O2 (oxygen partial pressure 0.05, bal. N2) and the mass gain as well as the thicknesses of the individual oxide phases have been measured. The oxidation process has been simulated using a modified version of the homogenization model as implemented in Dictra; this has helped to rationalize the kinetics of oxide scale formation and in particular the evolution of the hematite (Fe2O3), magnetite (Fe3O4), and wustite (FeO) which form. Independently assessed thermodynamic and kinetic Calphad databases are needed for the calculations; details of these are given. Reasonable agreement between simulation results and experimental data is obtained, though it is concluded that the large influence of grain boundary diffusion on the oxidation rate needs further consideration.
|
|
| 6. |
- Bigdeli, Sedigheh, 1984, et al.
(author)
-
Strategies for High-Temperature Corrosion Simulations of Fe-Based Alloys Using the Calphad Approach : Part I
- 2021
-
In: Journal of Phase Equilibria and Diffusion. - : Springer Nature. - 1547-7037 .- 1863-7345. ; 42:3, s. 403-418
-
Journal article (peer-reviewed)abstract
- The environmental degradation of materials at high temperatures limits the useful life of different industrial components and hinders the development of more economical and environmentally friendly processes for the energy production. Despite the importance of this phenomena, a model to predict lifetime of materials that degrade due to high-temperature corrosion has up till now been lacking due to limitations of the computational possibilities and the complex nature of oxidation. In the present work we develop some strategies to model high-temperature corrosion in Fe-based alloys using the Calphad (Calculation of Phase Diagrams) approach. It is proposed that kinetic-based simulations for oxidation of Al and Cr can accurately represent the lifetime of the protective layers in FeCrAl and FeCr alloys at different temperatures in air. The oxide systems are in addition investigated by equilibrium calculations. The corrosion mechanisms of FeCr and FeCrAl alloys are discussed based on theoretical and experimental knowledge.
|
|
