The LHCb experiment at the Large Hadron Collider (LHC) at CERN is designed to make precise measurements of processes including B and D mesons to test the Standard Model (SM) predictions for CP violation, and to search for new physics. From its inception one of the key aims of the LHCb collaboration has been to precisely measure the CP violating phase ϕs, the weak phase due to the interference between B⁰/s -B¯⁰/s mixing and decay. Having collected 3 fb-1 of data in Run 1, the combined results of LHCb measurements of ϕs from various decay modes are in agreement with SM predictions. The aim now is to improve the precision of the LHCb measurement to be sensitive to any small deviation from the SM prediction of ϕs. One strategy to achieve this, in addition to collecting more data, is to expand the number of modes used to measure ϕs to improve the sensitivity of the combination. This thesis presents the measurement of the CP violating phase ϕs in the yet unstudied B⁰/s→ ψ(2S)ϕ decay mode. In addition to providing a measurement of ϕs the study of this mode presents an opportunity to confirm the lifetime difference of the B⁰/s mass eigenstates ∆Γs, currently only measured in the B⁰/s→ Jψϕ decay mode. The results from 3 fb-1 of LHCb data are; ϕs = 0:23+0:29-0:28 ± 0:02 rad, ∆Γs = 0:066+0:041-0:044 ± 0:007 ps-1. which are in agreement with the SM and the results from the LHCb measurement from B⁰/s→ Jψϕ decays.

Thesis (Ph. D.)--University of Chicago, Dept. of Physics, August 1997. / Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (p. [89]-93).

No description available.

No description available.

No description available.

KOPIO is an experiment designed to search for the CP-symmetry-violating reaction K_L⁰ → π⁰νν̅. Measurement of the branching ratio of this reaction, depending on the accuracy of the measurement, could be the most precise measurement of the CP-violation parameters of the Standard Model to date. The K_L⁰ → π⁰νν̅ reaction is exceedingly rare, with an expected branching ratio of (2.6 ± 1.2) ·10⁻¹¹ . The rareness of this reaction means two things: 1) that we need prodigious numbers of kaons, and 2) that a multitude of "improper" decays will have to be screened out by means of a veto detector system, part of which is being designed here at Virginia Tech. This detector must be able to detect the passage of daughters of the undesired decay reactions (charged particles and gammas). It must be operational inside a magnetic field, and must have signal timing fast enough to accommodate the rate at which these decays occur. A detector consisting of alternating layers of scintillator and lead, with wavelength-shifting fibers embedded in the scintillator, provides the characteristics sought after. This paper presents methodology used in design and construction of this detector, as well as results of signal property tests, using both cosmic rays and gammas as event triggers. Also included is a discussion on transporting the detector signal outside of the magnetic field so it can be read by photomultiplier tubes resting outside of the sweeping magnet. / Master of Science

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.

The LHCb experiment is an experiment based at the LHC in Geneva and is dedicated to the study of mesons containing bottom and charm quarks. One of the primary goals of the physics at LHCb is to measure CP-violating effects which lead to a dominance of matter over anti-matter in the universe. This thesis presents the measurement of the CP-violating phase Ø s which is one of the golden channels at LHCb. This phase is observed as the interference between mixing of B0s ↔ B-0s and decay of B0s → J/ψ K+K−. The results, based upon the 1.0 fb−1 dataset collected by LHCb during 2011, are: Ø s = 0.07±0.09±0.01 rad , ∆Γs = 0.100±0.016±0.002 ps−1 , Γs = 0.663±0.005±0.006 ps−1 . This analysis is also able to measure the mixing parameter ms = 17.71±0.10±0.01 ps−1. To improve upon this measurement the B0s → J/ψ K+K− analysis is combined with the B0s → J/ψ π+ π − decay channel to make the most accurate measurements to date of, Ø s = 0.01±0.07±0.01 rad, ∆Γs = 0.106±0.011±0.007 ps−1 and Γs = 0.661±0.004±0.006 ps−1. As an integral part of this work a comprehensive software suite known as RapidFit was developed, which is used by many other physicists and this is described.

An accurate determination of the angle γ of the Unitary Triangle is one of the most important goals of the LHCb experiment. The LHCb detector is a single-arm spectrometer at the LHC, optimised for beauty and charm flavour physics. As the angle γ is the least experimentally constrained parameter of the Unitary Triangle, its precise experimental determination can be used to test the validity of the Standard Model. The Unitary Triangle phase γ can be extracted in B → DK decays at tree-level, exploiting the interference between b → c(ūs) and b → u(c̄s) transitions. This interference is sensitive to γ and can give measurable charge asymmetries. In particular, γ ≠ 0 is required to produce direct CP violation in B decays and this is the only CP-violating mechanism for the decay of charged B^± mesons. In this thesis, an analysis of CP violation in B^± → DK^± and B^± → Dπ^± decays is presented, where the D meson is reconstructed in the two-body final states: K^±π^∓, K⁺K⁻, π⁺π⁻ and π^±K^∓. The analysis uses the full 2011 LHCb dataset of 1.0 fb^-1, collected from pp collisions at √s = 7 TeV. Several CP-related quantities, e.g the ratio of B → DK and B → Dπ branching fractions and their charge asymmetries, are measured via a simultaneous fit to the invariant mass distributions of the modes considered. The suppressed B^± → DK^± mode is observed for the first time with ≈ 10σ significance. Once all measurements are combined, direct CP violation is established in B^± decays with a total significance of 5.8σ.