New precise measurements of the ratio of leptonic decays of K+ and K- mesons

The present PhD thesis concludes an experimental work of three years in the field of particle physics under the supervision of Prof. I. Mannelli. This work has been developed within the NA48/2 international collaboration and is part of the research of the collaboration, which, recently, terminated its second year of data taking at the SPS CERN site. The plan of the paper is the following: In the first Chapter an introduction to the relevant topics will be presented; in the second Chapter the theoretical motivation and the presently published experimental results will be briefly exposed; Chapter 3 will present the NA48/2 experimental apparatus, while Chapter 4 will focus on the methods employed in order to achieve the goals of the measurement; starting from Chapter 5 the details of the analysis will be presented. The final Chapter will conclude the thesis comparing the results obtained by the candidate with the theoretical predictions and the experimental results presently available.