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The discovery of neutrino mixing provides the possibility of a non vanishing CP violating phase in the neutrino mixing matrix. CP violation in the leptonic sector can be large enough to explain the matter-antimatter asymmetry in the universe. An indirect probe of CP violation is the experimental measurement of Electric Dipole Moment (EDM). CP violation has been discovered in the quark sector,but it contributes to lepton EDM at the 3-loop level. Neutrino masses can be generated in the standard model via the see-saw mechanism where heavy right-handed neutrinos mix with the weak-basis states. The Majorana nature of the seesaw type neutrinos generates new 2-loop diagrams that lead to a non-vanishing lepton EDM. Only estimates of the resulting EDM have been done in the literature. A full calculation of the 2-loop diagrams and the exact result is presented. / Ph. D.

An alternative approach to the problem of CP-violation is presented. It is based on the possibility of spontaneous CP-breakdown in models with two Higgs doublets. General features of the phenomenon such as stability of the vacuum and the existence of a light axion are discussed. We investigate the feasibility of spontaneously broken CP in the minimal supersymmetric models - the MSSM and NMSSM. The latter is shown to be experimentally viable. The phenomenological implications of the model such as CP-violating effects in the kaon systems and a nonzero neutron electric dipole moment are studied. / Ph. D.

Decays of neutral D mesons to final states containing K + π's could provide evidence for CP-violation from a source not accounted for in the Standard Model. Due to the interference between Cabibbo-favored and Cabibbo-suppressed transitions, a decay rate asymmetry of D0 → K0S π0 compared to D0 → K0Lπ0 has been predicted to be non-zero. If New Physics interferes in doubly Cabibbo-suppressed D decays, the measurement of this asymmetry would differ from the predicted value and may provide evidence for CP-violation beyond the CKM mechanism. I present an analysis method to measure this branching fraction asymmetry, R(D0) ≡ B(D0→K0S π0)−B(D0→K0L π0)/(B(D0→K0Sπ0)+B(D0→K0Lπ0)), utilizing e+e− → cc events in the Belle dataset. / Doctor of Philosophy / The Universe appears to be made almost entirely of matter rather than antimatter; however, matter and antimatter should have been created in equal amounts in the Big Bang. We do not know exactly why we observe so much more matter as compared to antimatter. The Standard Model (SM) of particle physics accounts for some of the asymmetry through Charge-Parity (CP) symmetry violation, which explains how particles behave differently than their corresponding antiparticles. In the current state of the SM, some CP-violation is allowed in decays via the weak force, but the theory does not account for enough CP violation to explain the amount of matter-antimatter asymmetry observed in the Universe. Decays of a D meson to a kaon (K meson) plus one or more pions (π mesons) via a new mechanism beyond the weak force could provide evidence of a new source of CP-violation. In this analysis, I present a method for analyzing the decays of neutral D mesons to a neutral kaon and a neutral pion in the Belle dataset to test the SM.

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.

LHCb est l'une des quatre grandes expériences installées sur l'anneau du LHC. Le détecteur a pour but la mesure précise de la violation de CP et de canaux rares de désintégration dans le secteur des mésons B. Le calorimètre de l'expérience est un ensemble de quatre sous-systèmes : le détecteur de pied de gerbe, le ''preshower'' et les calorimètres électromagnétique (ECAL) et hadronique (HCAL). Il est essentiel pour la reconstruction des événements, pour le déclenchement de l'expérience et pour l'identification des électrons et des photons. Après une revue du détecteur LHCb, l'électronique des calorimètres est décrite dans la première partie de ce mémoire. Dans un premier temps l'électronique de lecture des voies des photomultiplicateurs des ECAL et HCAL est présentée en mettant l'accent sur ses performances, puis la carte de contrôle de l'ensemble du système calorimétrique de l'expérience est détaillée. Les chapitres trois et quatre concernent les programmes de test de cette électronique, les choix technologiques permettant de la rendre suffisamment tolérante aux radiations et les mesures quantifiant cette tolérance. La seconde partie de ce mémoire porte d'abord sur l'identification des photons avec les calorimètres de LHCb. La méthode est présentée avec ses performances. Enfin, l'étalonnage absolu en énergie des PRS et ECAL, basée sur les données enregistrées avec le détecteur en 2010, est décrite dans le dernier chapitre de cette même seconde partie.

A central goal of flavour physics is a precise determination of the elements of the CKM matrix, which quantifies the strength of charged-current weak interactions between quarks. Of particular interest is the angle γ in the 'b-d' unitarity triangle parameterisation of the CKM matrix. One of the most promising methods to determine γ directly is to measure CP violation in interfering B±->DK± decays, where D indicates a coherent superposition of D0 and D0bar, both of which decay to the same final state. When using this method it is essential to determine the hadronic decay parameters of the D precisely in order to reduce the systematic uncertainties on the measurement of γ. One such parameter is the strong-phase difference between D0 and D0bar decays, which must be accurately known across the entire kinematic phase space. In this thesis we present measurements related to the determination of γ at both the CLEO-c experiment at Cornell University and the LHCb experiment at CERN. Firstly, we describe a model-independent determination of the D->KsKK strong-phase difference using 818pb-1 of quantum-correlated D0-D0bar data collected by CLEO-c at the ψ(3770) resonance. We reconstruct D->KsKK decays tagged with a variety of final states. By studying these decays we determine the weighted cosine and sine of the strong-phase difference in bins across the Dalitz plane. We run simulations to estimate the impact of these measurements on a determination of γ using B±->D(KsKK)K± decays. The resulting uncertainty on γ due to the CLEO-c inputs is between 3.2° and 3.9°, depending on how the Dalitz plane is binned. Furthermore, we present a model-independent measurement of the CP content of the decay D0->KsKK in the kinematic region of the φ->KK resonance. The fraction of CP-odd events in this region is 0.76 or higher at the 90% C.L. We also present an analysis of data recorded by LHCb in 2010, corresponding to an integrated luminosity of 36.5pb-1. We reconstruct the decays B±->D(Kπ)h± and B±->D(KK)h±, where h± indicates either K± or π±. Although there are not enough events in this dataset to measure γ, we are able to measure other observables related to CP violation in the B±->Dh± system. We measure B(DK,Fav)/B(Dπ,Fav), the ratio of the branching fraction of B±->D(Kπ)K± to that of B±->D(Kπ)π±, to be 0.066 ± 0.005 ± 0.004, and B(DK,CP)/B(Dπ,CP), the ratio of the branching fraction of B±->D(KK)K± to that of B±->D(KK)π±, to be 0.093 ± 0.019 ± 0.005. We determine several CP asymmetries: A(CP+,DK), the CP asymmetry in B±->D(KK)K± decays, is measured as 0.06 ± 0.17 ± 0.07; A(CP+,Dπ), the CP asymmetry in B±->D(KK)π± decays, is found to be 0.009 ± 0.042 ± 0.011; and A(Fav,DK), the CP asymmetry in B±->D(Kπ)K± decays, is measured as -0.109 ± 0.085 ± 0.019. Finally we calculate R(CP+), the ratio of the branching fraction of B±->D(KK)K± to that of B±->D(Kπ)K±, to be 1.41 ± 0.31 ± 0.11. These results indicate that LHCb is in a strong position to make a world-leading measurement of γ with a larger data sample.

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.

The Large Hadron Collider started operation this year, 2008. LHCb is a precision heavy-flavour experiment at this collider. The precision of LHCb is greatly aided by the LHCb Ring Imaging Cherenkov system for the separation and identification of charged hadrons. This system uses pixel Hybrid Photon Detectors, an innovative new technology for single photon imaging. The simulation and testing of these photon detectors are reported and discussed. The photodetectors were measured to have reached or exceeded the specifications in key areas. In particular, the detector quantum efficiencies far exceed expectations, by a relative 27 %. The precision of LHCb will be used to examine CP-violation and rare decays of B-mesons. A key part of the physics programme will be a measurement of the CP-violating flavour specific asymmetry in neutral B-meson mixing. This asymmetry is expected to be very small in the Standard Model, of order 10-4, however it is very sensitive to new physics, which can increase the asymmetry dramatically. We present an improved event selection and a novel method to control systematics. This will enable us to make a world-leading measurement of this parameter in one nominal year of data taking (2 fb-1).

The angle γ, with an uncertainty of approximately 10° is the least well constrained angle of the unitary triangle. Better experimental constraints on this parameter are required in order to provide a consistency check on the standard model description of CP violation. A promising strategy for measuring γ involves exploiting interference effects present in B^± → DK^± decays where the D subsequently decays to a three or four body final state. The three body decay D → K_S ⁰p⁺p^- and the four body decay D⁰ → K⁺K^-p⁺p^- are suitable candidates for making such a measurement. However independent knowledge of the decay structure of these decays is required. The impact of the model, used to describe the p⁺p^- S wave, in the D⁰ → K⁺K^-p⁺p^- decay, on the uncertainty in the measurement of γ is estimated via a simulation study. It is determined that the uncertainty on a gamma measurement would be compromised by this model uncertainty within one year of LHCb data running. The four body decay D⁰ → K⁺K^-p⁺p^- also provides a candidate for making a γ measurement. This decay is expected to display a rich resonant structure. An understanding of this decay may also provide an insight into low energy QCD in addition to allowing a search for CP violation. Only one previous amplitude analysis has been performed on this decay. Using data collected at the CLEO-II.V, CLEO-III and CLEO-c experiments an amplitude model is developed for the D⁰ → K⁺K^-p⁺p^- decay. This model is qualitatively similar to that produced in the previous analysis although the model presented in this thesis considers higher orbital angular momentum states and distinguishes between conjugate states that the previous model did not. A search for CP violation is also carried out using the D⁰ → K⁺K^-p⁺p^- decay data. A positive confirmation of CP violation at the level of sensitivity provided by this decay data would provide evidence for a level of CP violation which could not be accounted for within the standard model. No significant evidence for CP violation is observed in this decay. A toy MC study was carried out in order to determine the sensitivity to γ which may be achieved using this decay. In this study, sets of 1000 B⁺ and B^- events are generated and the decay model developed for the D → K⁺K^-p⁺p^- decay is used to describe the D decay. The sensitivity to γ determined in this study is 11°.