Observation of CP Violation in B± ¿ DK± Decays

CP
violation is a well-established phenomenon in particle physics, but until 2001 it was only observed in kaons. In the last decade, several matter-antimatter asymmetries have been observed in neutral B mesons in line with the expectations of the Standard Model of the weak interaction.  Direct
CP
violation is also expected in the decay rates of charged
B+
mesons versus that of
B-
mesons, though the greatest effects are present in a decay that occurs just twice in 10 million decays. Such rarity requires huge samples to study and this is exactly what the LHC, and its dedicated
B-
physics experiment LHCb provide. This thesis presents an analysis of the first two years of LHCb data. The author describes the first observation of the rare decay,
B- ? DK-, D ? p-K+
and the first observation of direct
CP
violation in this
B
decay. The work constitutes essential information on the experiment’s measurement of a fundamental parameter of the theory and stands as a benchmark against which subsequent analyses of this type will be compared.