LHCb is a precision heavy-flavour experiment at the Large Hadron Collider and in 2011 collected just over 1 fb-1 of data at a centre-of-mass energy of √s = 7 TeV. The Ring Imaging Cherenkov (RICH) detectors allow LHCb to identify charged hadrons by measuring their velocity. The system uses Hybrid Photon Detectors to detect rings of single photons emitted by particles travelling through the RICH radiators. The performance-monitoring of these photon detectors whilst data-taking is presented and discussed. LHCb aims to perform precise measurements of Charge-Parity violation in B and D mesons. The final state of B0 → J/Ψ(→μ=μ-)K*(→K=π-) is an admixture of parity-odd and parity-even final states, which are either longitudinally or transversely polarized. These contributions can be separated by performing an angular analysis. The polarization amplitudes and phases of the final state are measured. No difference is observed between the B0 and B0 flavour eigenstates which indicates that Charge-Parity symmetry has been conserved. The ambiguity in the measurement of the strong phase has been resolved by studying the P-wave and S-wave interference in the K/π mass system. The deviation from zero or π in the measurement of the strong phases indicates that final state interactions have occurred. In addition, the prediction that the polarization amplitudes should be similar to those of B0s→ J/Ψo is confirmed.

The study of flavour physics allows for the Standard Model (SM) to be tested to higher energies than can be accessed through direct searches. The SM is known not to provide enough of a difference between matter and anti-matter, termed CP violation, to explain the dominance of matter in our universe. One of the main purposes of the LHCb experiment is to search for new sources of CP violation in the decays of B mesons. Flavour changing neutral current (FCNC) interactions are forbidden at tree level in the SM, and can therefore only be accessed through quantum loops. In New Physics scenarios such as Supersymmetry, new particles could appear in those loops introducing new sources of CP violation. The Bos→ØØ decay proceeds via the b → sss FCNC transition. Triple products provide a method of exploiting the angular distributions of P → V V decays to create T-odd observables. Asymmetries of these T-odd observables, averaged over the initial flavour of the Bos meson provide a measure of T violation. Assuming CPT conservation, violation of time reversal infers CP violation. The CP-violating weak phase in the interference between Bos mixing and the decay to two Ø mesons is predicted to be close to zero in the SM. The measurements of the triple product asymmetries and the CP-violating weak phase have been performed using 1.0 fb-1 of LHCb data. Events where kaon pairs originate from a spin-0 or non-resonant state are accounted for with the associated angular distributions. Triple product asymmetries are measured to be AU = -0:055 ± 0:036(stat) ± 0:018(syst) and Av = 0:010 ± 0:036(stat) ± 0:018(syst). The CP-violating phase is found to be in the interval [-2:46,-0:76] rad at 68% confidence level. The p-value for the hypothesis of zero radians is found to be 16 %. These results represent the most accurate measurements of the triple product asymmetries and the first measurement of the CP-violating weak phase.

This thesis documents studies of CP violation in B^± to [K_S⁰h⁺h⁻]_DK^±, (h = π/K) decays using data taken by the LHCb experiment during 2011, and the first measurement of γ to be made at the Large Hadron Collider (LHC), γ = (45+43-38) degrees. Also included is a study of D⁰ to K_S⁰K^∓π^± decays using CLEO III and CLEO-c data, resulting in the first amplitude models to be published for these decays and a measurement of the ratio of their branching fractions.

Two analyses are performed using data collected by the LHCb experiment during 2011. Both consider decays of charged B mesons reconstructed in the π±μ+μ− final state. Decays involving dimuons provide an experimentally clean signature, even in the high-background environment of the √s = 7 TeV proton-proton collisions at the LHC. The first analysis measures the CP asymmetry of B±→Ψπ± decays using 0.37 fb-1 of data, where the dimuon decays of two resonances are considered, J/ψ→μ+μ− and ψ(2S)→μ+μ−. The branching fraction is measured relative to the Cabibbo favoured B±→ΨK± mode. The second analysis uses 1 fb-1 of data to make the first observation of the non-resonant B±→π±μ+μ− decay. The branching fraction is measured relative to that of B±→K±μ+μ−, and measurements of the CP asymmetry and the ratio of CKM matrix elements Vtd/Vts are obtained. The branching fractions of the decays of interest are found to be B(B±→J/ψ π±) = (3.88 ± 0.11 ± 0.15) x 10-5, B(B±→ψ(2S) π±) = (2.52 ± 0.26 ± 0.15) x 10-5 and B(B±→π±μ+μ−) = (2.48 + 0.57 −0.52 ± 0.17) x 10-8, where the first uncertainty is related to the statistical size of the sample and the second quantifies systematic effects. The measured CP asymmetries in these modes are A CP (J/ψ π) = 0.005 ± 0.027 ± 0.011, A CP (ψ(2S) π) = 0.048 ± 0.090 ± 0.011 and A CP (μμπ) = -0.045 ± 0.220 ± 0.066, with no evidence of direct CP violation seen. The ratio of matrix elements is measured as Vtd/Vts = 0.274 + 0.031 − 0.028 ± 0.008, which is in agreement with previous results.