| 1. |
- Schael, S, et al.
(författare)
-
Precision electroweak measurements on the Z resonance
- 2006
-
Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 427:5-6, s. 257-454
-
Forskningsöversikt (refereegranskat)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. |
|
|
| 3. |
|
|
| 4. |
- Abreu, P., et al.
(författare)
-
Search for sleptons in e+e- collisions at √s = 183 to 189 GeV
- 2001
-
Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 19:1, s. 29-42
-
Tidskriftsartikel (refereegranskat)abstract
- Data taken by the DELPHI experiment at centre-of-mass energies of 183 GeV and 189 GeV with a total integrated luminosity of 212 pb-1 have been used to search for the supersymmetric partners of the electrons, muons, and taus in the context of the Minimal Supersymmetric Standard Model (MSSM). The decay topologies searched for were the direct decay (ℓ̃ → ℓx̃), producing acoplanar lepton pairs plus missing energy, and the cascade decay (ℓ → ℓx̃0 2 → ℓγx̃0 1), producing acoplanar lepton and photon pairs plus missing energy. The observed number of events is in agreement with Standard Model predictions. The 95% CL excluded mass limits for selectrons, smuons and staus are mẽ ≤ 87 GeV/c2, mμ̃ ≤ 80 GeV/c2 and mτ̃ 75 GeV/c2, respectively, for values of μ=-200 GeV/c2 and tanβ=1.5.
|
|
| 5. |
- Abreu, P., et al.
(författare)
-
Study of dimuon production in photon-photon collisions and measurement of QED photon structure functions at LEP
- 2001
-
Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 19:1, s. 15-28
-
Tidskriftsartikel (refereegranskat)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.
|
|
| 6. |
- Abreu, P., et al.
(författare)
-
Measurement of the gluon fragmentation function and a comparison of the scaling violation in gluon and quark jets
- 2000
-
Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 13:4, s. 573-589
-
Tidskriftsartikel (refereegranskat)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..
|
|
| 7. |
|
|
| 8. |
- Purgel, M., et al.
(författare)
-
Glyphosate complexation to aluminium(III). An equilibrium and structural study in solution using potentiometry, multinuclear NMR, ATR-FTIR, ESI-MS and DFT calculations
- 2009
-
Ingår i: Journal of Inorganic Biochemistry. - 0162-0134. ; 103:11, s. 1426-1438
-
Tidskriftsartikel (refereegranskat)abstract
- The stoichiometries and stability constants of a series of Al3+-N-phosponomethyl glycine (PMG/H3L) complexes have been determined in acidic aqueous solution using a combination of precise potentiometric titration data, quantitative Al-27 and P-31 NMR spectra, ATR-FTIR spectrum and ESI-MS measurements (0.6 M NaCl, 25 degrees C). Besides the mononuclear AlH2L2+, Al(H2L)(HL), Al(HL)(2)(-) and Al(HL)L2-, dimeric Al-2(HL)L+ and trinuclear Al3H5L42+ complexes have been postulated. H-1 and P-31 NMR data show that different isomers co-exist in solution and the isomerization reactions are slow on the P-31 NMR time scale. The geometries of monomeric and dimeric complexes likely double hydroxo bridged and double phosphonate bridged isomers have been optimized using DFT ab initio calculations starting from rational structural proposals. Energy calculations using the PCM solvation method also support the co-existence of isomers in solutions. (C) 2009 Elsevier Inc. All rights reserved.
|
|
| 9. |
|
|
| 10. |
- Brodin, N., et al.
(författare)
-
Coaching patients with early rheumatoid arthritis to healthy physical activity : A multicenter, randomized, controlled study
- 2008
-
Ingår i: Arthritis and Rheumatism. - Hoboken, NJ : Wiley. - 0004-3591 .- 1529-0131. ; 59:3, s. 325-331
-
Tidskriftsartikel (refereegranskat)abstract
- Objective. To investigate the effect of a 1-year coaching program for healthy physical activity on perceived health status, body function, and activity limitation in patients with early rheumatoid arthritis. Methods. A total of 228 patients (169 women, 59 men, mean age 55 years, mean time since diagnosis 21 months) were randomized to 2 groups after assessments with the EuroQol visual analog scale (VAS), Grippit, Timed-Stands Test, Escola Paulista de Medicina Range of Motion scale, walking in a figure-of-8, a visual analog scale for pain, the Health Assessment Questionnaire disability index, a self-reported physical activity questionnaire, and the Disease Activity Score in 28 joints. All patients were regularly seen by rheumatologists and underwent rehabilitation as prescribed. Those in the intervention group were further individually coached by a physical therapist to reach or maintain healthy physical activity (=30 minutes, moderately intensive activity, most days of the week). Results. The retention rates after 1 year were 82% in the intervention group and 85% in the control group. The percentages of individuals in the intervention and control groups fulfilling the requirements for healthy physical activity were similar before (47% versus 51%, P > 0.05) and after (54% versus 44%, P > 0.05) the intervention. Analyses of outcome variables indicated improvements in the intervention group over the control group in the EuroQol VAS (P = 0.025) and muscle strength (Timed-Stands Test, P = 0.000) (Grippit, P = 0.003), but not in any other variables assessed. Conclusion. A 1-year coaching program for healthy physical activity resulted in improved perceived health status and muscle strength, but the mechanisms remain unclear, as self-reported physical activity at healthy level did not change. © 2008, American College of Rheumatology.
|
|
