Summary and Conclusions - It was shown that segmentation and pulse-shape discrimination can improve the discovery sensitivity of a next-gen 0vBB-decay experiment by 90%. - However, when practical aspects are considered (such as instrumenting each segment with front-end electronics), the discovery sensitivity is decreased by 19%. - This has extremely important consequences to proposed next-gen experiments since the two active collaborations have strongly advocated the use of segmented detectors for all or part of the experiment. - New germanium detector technology, currently under development, has demonstrated excellent multi-site background rejection capabilities without the complexity of segmentation or complicated PSD algorithms. - The physically-segmented p-type germanium detector technology has proven to be a useful and practical tool in modern nuclear physics. The PSEG technology deserves further development as it has the potential for use in a variety of applications.

A study of B-meson decays to final states with a single charm baryon is presented based on data recorded by the BABAR detector at the Stanford Linear Accelerator Center. Although the B meson is the lightest bottom-flavored meson, it is heavy enough to decay to a baryon made of three quarks and an antibaryon made of three antiquarks. By studying the baryonic weak decays of the B meson, we can investigate baryon production mechanisms in heavy meson decays. In particular, we measure the rates of the decays B{sup -} {yields} {Lambda}{sub c}{sup +}{bar p}{pi}{sup -} and {bar B}{sup 0} {yields} {Lambda}{sub c}{sup +}{bar p}. Comparing these rates, we confirm an observed trend in baryonic B decays that the decay with the lower energy release, B{sup -} {yields} {Lambda}{sub c}{sup +}{bar p}{pi}{sup -}, is favored over {bar B}{sup 0} {yields} {Lambda}{sub c}{sup +}{bar p}. The dynamics of the baryon-antibaryon ({Lambda}{sub c}{sup +}{bar p}) system in the three-body decay also provide insight into baryon-antibaryon production mechanisms. The B{sup -} {yields} {Lambda}{sub c}{sup +}{bar p}{pi}{sup -} system is a laboratory for searches for excited {Sigma}{sub c} baryon states; we observe the resonant decays B{sup -} {yields} {Sigma}{sub c}(2455){sup 0}{bar p} and B{sup -} …

A search for the Standard Model Higgs boson in the missing energy and acoplanar b-jet topology is reported, using an integrated luminosity of 0.93 fb{sup -1} recorded by the D0 detector at the Fermilab Tevatron p{bar p} Collider. The analysis includes signal contributions from p{bar p} {yields} ZH {yields} {nu}{bar {nu}}b{bar b}, as well as from WH production in which the charged lepton from the W boson decay is undetected. Neural networks are used to separate signal from background. In the absence of a signal, limits are set on {sigma}(p{bar p} {yields} VH) x B(H {yields} b{bar b}) at the 95% C.L. of 2.6-2.3 pb, for Higgs boson masses in the range 105-135 GeV, where V = W, Z. The corresponding expected limits range from 2.8 to 2.0 pb. Potential improvements to the analysis with an extended dataset totalling 4 fb{sup -1} are also discussed. Essential maintenance related to the increased luminosity and RunIIb upgrade was carried out on the impact parameter (IP) based b-tagging trigger tool and the effect of the changes on the b-tagger's performance was investigated.

We have used the Collider Detector at Fermilab (CDF-II) to set upper limits on the branching ratio of the flavor-changing neutral-current (FCNC) top quark decay t {yields} Zc using a technique employing ratios of W and Z production, measured in 1.52 fb{sup -1} of p{bar p} data. The analysis uses a comparison of two decay chains, p{bar p} {yields} t{bar t} {yields} WbWb {yields} {ell}{nu}bjjb and p{bar p} {yields} t{bar t} ZcWb {yields} {ell}{sup +}{ell}{sup -} cjjb, to cancel systematic uncertainties in acceptance, efficiency, and luminosity. We validate the MC modeling of acceptance and efficiency for lepton identification over the multi-year dataset also using a ratio of W and Z production, in this case the observed ratio of inclusive production of W to Z-bosons, a technique that will be essential for precision comparisons with the standard model at the LHC. We introduce several methods of determining backgrounds to the W and Z samples. To improve the discrimination against SM backgrounds to top quark decays, we calculate the top mass for each event with two leptons and four jets assuming it is a t{bar t} event with one of the top quarks decaying to Zc. The upper limit on the Br(t …

At particle accelerators the Standard Model has been tested and will be tested further to a great precision. The data analyzed in this thesis have been collected at the world's highest energetic-collider, the Tevatron, located at the Fermi National Accelerator Laboratory (FNAL) in the vicinity of Chicago, IL, USA. There, protons and antiprotons are collided at a center-of-mass energy of {radical}s = 1.96 TeV. The discovery of the top quark was one of the remarkable results not only for the CDF and D0 experiments at the Tevatron collider, but also for the Standard Model, which had predicted the existence of the top quark because of symmetry arguments long before already. Still, the Tevatron is the only facility able to produce top quarks. The predominant production mechanism of top quarks is the production of a top-antitop quark pair via the strong force. However, the Standard Model also allows the production of single top quarks via the electroweak interaction. This process features the unique opportunity to measure the |V{sub tb}| matrix element of the Cabbibo-Kobayashi-Maskawa (CKM) matrix directly, without assuming unitarity of the matrix or assuming that the number of quark generations is three. Hence, the measurement of the cross section of …

In this dissertation, we present the results of a time-dependent angular analysis of B_s → J/ΨΦ decays performed with the use of initial-state flavor tagging. CP violation is observed in this mode through the interference of decay without net mixing and decay with net mixing, that is, B_s → J/ΨΦ and B_s → $\bar{B}$_s → J/ΨΦ . The time-dependent angular analysis is used to extract the decay widths of the heavy and light B_s eigenstates and the difference between these decay widths ΔΓ_s {triple_bond} Γ_s^L-Γ_s^H. Initial-state flavor tagging is used to determine the matter-antimatter content of the B_s mesons at production time. We combine flavor tagging with the angular analysis, which statistically determines the contributions of the CP-even and CP-odd components at decay time, to measure the CP-violating phase β_s. The phase β_s is expressed in terms of elements of the Cabibbo-Kobayashi-Maskawa matrix as β_s {triple_bond} arg (-V_tsV*_tb/V_csV*_cb), and is predicted by the Standard Model to be close to zero, β_s^SM = 0.02. In the measurement of ΔΓ_s, we use a dataset corresponding to 1.7 fb^-1 of luminosity, collected at the CDF experiment from proton-antiproton collisions at a center of mass energy √s = 1.96 TeV. In the measurement of …