In the Standard Model of particle physics, the Cabibbo-Kobayashi-Maskawa (CKM) mechanism describes the quark mixing effect. The CKM gamma angle is one of the parameters of the Standard Model that are known less accurately. Direct measurements give an uncertainty of around 15º, large with respect to the uncertainty on the value extracted from global fits, of 3º. In order to test the Standard Model consistency, the gamma angle needs to be measured precisely. This can be done using processes at the tree-level, where only Standard Model contributions are expected, or using processes involving loop diagrams, which can be sensitive to physics beyond the Standard Model. Differences in the gamma measurement from tree and loop diagrams would be an indication of new physics. This thesis presents the first measurement of the CP observables in the B0 -> DK0 decay. Sensitivity to gamma arises from the interference of the b -> u mediated amplitude with the b -> c one, at the tree-level. The CP asymmetry of the B0 -> D(K+K-)K0 mode and the partial width ratio of this channel with respect to B0 -> D(K+pi-)K0 are measured using 1 /fb of data collected by the LHCb experiment in 2011,A_KK_d = -0.452 +/- 0.230 +/- 0.025 = A_CP+,R_KK_d = 1.360 +/- 0.366 +/- 0.075 = R_CP+. The CP asymmetry of the suppressed B0 -> D(K-pi+)K0 mode and the partial width ratio with respect to the favoured B0 -> D(K+pi-)K*0 are measured using the total 3 /fb of data collected in 2011 and 2012,A_sup_d = -0.094 +/- 0.318 = A_ADS,R_d = 0.075 +/- 0.023 = R_ADS. In addition, the studies performed on the hardware hadronic trigger of the LHCb experiment are also presented.
