A study of radiative lepton decays of the Z boson

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

Nitrogen Leaching from Cattle, Sheep and Deer Grazed Pastures in New Zealand

The impacts of intensified grazing in New Zealand are being reflected in declining quality of groundwater, streams and lake water. Manipulation of ratios of grazing animal species may be one way farmers can reduce nitrogen (N) emissions to ground water. The present research quantifies nitrate and ammonium leaching losses from rotationally grazed sheep, cattle and deer pastures in a common environment

Differing predictive relationships between baseline LDL-C, systolic blood pressure, and cardiovascular outcomes

Funded by Pfizer

Novel GPU Approach In Predicting The Directional Trend Of The S&P 500

Our goal is development of an algorithm capable of predicting the directional trend of the Standard and Poor’s 500 index (S&P 500). Extensive research has been published attempting to predict different financial markets using historical data testing on an in-sample and trend basis, with many authors employing excessively complex mathematical techniques. In reviewing and evaluating these in-sample methodologies, it became evident that this approach was unable to achieve sufficiently reliable prediction performance for commercial exploitation. For these reasons, we moved to an out-of-sample strategy based on linear regression analysis of an extensive set of financial data correlated with historical closing prices of the S&P 500. We are pleased to report a directional trend accuracy of greater than 55% for tomorrow (t+1) in predicting the S&P 500

Observations of velocities, sand concentrations, and fluxes under velocity-asymmetric oscillatory flows

Peer reviewedPublisher PD

Reductions in all-cause, cancer, and coronary mortality in statin-treated patients with heterozygous familial hypercholesterolaemia: a prospective registry study

AIMS: To examine the changes in coronary, all-cause, and cancer mortality in patients with heterozygous familial hypercholesterolaemia (FH) before and after lipid-lowering therapy with statins. METHODS AND RESULTS: A total of 3382 patients (1650 men) aged &lt;80 years were recruited from 21 lipid clinics in the United Kingdom and followed prospectively between 1980 and 2006 for 46 580 person-years. There were 370 deaths, including 190 from coronary heart disease (CHD) and 90 from cancer. The standardized mortality ratio (compared with the population in England and Wales) was calculated before and from 1 January 1992. In patients aged 20-79 years, CHD mortality fell significantly by 37% (95% CI = 7-56) from 3.4- to 2.1-fold excess. Primary prevention resulted in a 48% reduction in CHD mortality from 2.0-fold excess to none, with a smaller reduction of nearly 25% in patients with established disease. Coronary mortality was reduced more in women than in men. In patients without known CHD at registration, all-cause mortality from 1992 was 33% (21-43), lower than in the general population, mainly due to a 37% (21-50) lower risk of fatal cancer. CONCLUSION: The results emphasize the importance of early identification of FH and treatment with statins

Search for CP Violation in the Decay Z -> b (b bar) g

About three million hadronic decays of the Z collected by ALEPH in the years 1991-1994 are used to search for anomalous CP violation beyond the Standard Model in the decay Z -> b \bar{b} g. The study is performed by analyzing angular correlations between the two quarks and the gluon in three-jet events and by measuring the differential two-jet rate. No signal of CP violation is found. For the combinations of anomalous CP violating couplings, ${\hat{h}}_b = {\hat{h}}_{Ab}g_{Vb}-{\hat{h}}_{Vb}g_{Ab}$ and $h^{\ast}_b = \sqrt{\hat{h}_{Vb}^{2}+\hat{h}_{Ab}^{2}}$, limits of \hat{h}_b < 0.59$and$h^{\ast}_{b} < 3.02$ are given at 95\% CL.Comment: 8 pages, 1 postscript figure, uses here.sty, epsfig.st