1,207 research outputs found

    A study of radiative lepton decays of the Z boson

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    This thesis is devoted to the analysis of the data collected by the ALEPH detector at the large electron-positron (LEP) particle accelerator at CERN which studies the production and decay of the Z boson. The data was collected between 1990 and 1993 and corresponds to the production of about 1,422,000 Z events. Such a large data sample enables a detailed study of Z -> l+ l- + n photons (n>=1) events to be undertaken, where the aim is to observe physics beyond the standard model which enhances the number of events with an l+ l- + n gamma final states, e.g. compositeness. The thesis focuses on Z -> mu+ mu- + m gamma (m=1 or 2) and Z -> tau+ tau- gamma decays. The analysis of the former decay involves comparing the data with a number of electroweak theoretical predictions. Any discrepancies would indicate the presence of physics beyond the standard model. The latter decay is used to obtain a limit for the anomalous magnetic moment of the tau. The analysis of Z -> mu+ mu- + m gamma events indicates that the Monte Carlo has some inadequacies; it overpredicts the number of events with either low energy photons or photons close to the muons. The data has a small excess in the region of phase space in which physics beyond the standard model is most likely to be observed. This excess is, however, more likely due to the deficiencies of the Monte Carlo. The other theoretical predictions are generally in good agreement with the data and show the necessity of including initial state radiation and s channel photon exchange when considering final states with a detected photon. The standard model prediction for the value of the anomalous magnetic moment of the tau, denoted by F^tau_2(0), is 11773(3)*10^-7. The current experimental limit of F^tau_2(0) tau+ tau- gamma events produces the limit F^tau_2(0)<0.051. Whilst this result is worse than the current limit it is based on simpler theoretical assumptions

    Self-management of rheumatic diseases: State of the art and future perspectives

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    Self-management interventions are patient-centred and designed to foster active participation of patients in order to promote well-being and to manage symptoms. Over the past two decades, the role of self-management in chronic diseases has gained momentum. Self-management programmes are now acknowledged as a key element of quality care. New modes of delivery allow greater access to information and are tailored to address patient needs. This systematic review presents data from clinical studies of self-management over the past decade, summarises the evidence for programme effectiveness, and suggests future research directions

    {S-Benzyl 3-[(6-methyl­pyridin-2-yl-κN)methyl­idene]dithio­carbazato-κ2 N 3,S}zinc

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    The title compound, [Zn(C15H14N3S2)2], contains two chemically equivalent Schiff base anions that are coordinated to the ZnII ion as tridentate N,N′,S-chelating ligands, creating a distorted octa­hedral environment [the smallest angle being 75.40 (6)° and the widest angle being 162.87 (6)°], with the two S atoms in cis positions. The dihedral angle between the mean planes of the two coordinating ligands is 85.65 (5)°. Weak C—H⋯S hydrogen bonds are also observed
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