Decays of light, pseudoscalar mesons into lepton pairs are one possible way of detecting physics beyond the Standard Model. This thesis will focus on the η' → e+e- decay, because only few experiments have studied this decay. By the use of a basic simulation, the feasibility of conducting a search for the  η' → e+e- decay at DAΦNE, a electron-positron collider in Frascati, Italy, was investigated. The simulation implements an idea from previous experiments, where the η' decay was investigated through the e+e- → η' → X process. The results of the simulation show that experiments at DAΦNE could produce an observable signal of the process when the produced η' decays into one of the most probable decay modes. However, in order to draw a definite conclusion, a more detailed study is needed. / Sönderfallet av lätta, pseudoskalära mesoner till ett par av leptoner är ett möjligt sätt att detektera fysik bortom Standardmodellen. Detta examensarbete fokuserar på η’ → e+e- sönderfallet, på grund av att få experiment har studerat detta sönderfall. Genom att använda en enkel simulering, undersöktes möjligheten att studera η’ → e+e- sönderfallet vid DAΦNE, en elektron-positron accelerator i Frascati, Italien. Simuleringen följde samma genomförande som tidigare experiment, där η’ sönderfallet undersöktes genom e+e- → η’ → X processen. Resultaten av simuleringen visar på att experiment vid DAΦNE kan producera en detekterbar signal av processen då de producerade η’ sönderfaller till de mest troliga sönderfallen. På grund av begränsningarna i den utförda simulationen, behöver dock en mer detaljerad studie göras för att dra definitiva slutsatser.

Three interrelated topics in ship hydrodynamics - resistance, wave-making and wave decay - are investigated in an attempt to improve the accuracy of some simple methods used in the preliminary design of thin ships. Several published sets of data from classical and recent boundary layer experiments on flat plates are used to estimate boundary layer quantities such as thicknesses and eddy viscosities. These quantities are subsequently used to modify the hull shape and the free-surface boundary condition as a means of including viscous effects on wave-making and ship-wave decay. A recent technique is used to analyse 161 experimental flat-plate turbulent boundary layer velocity profiles, and a new skin-friction line is derived. Some practical methods are proposed for the numerical quadrature of integrals arising in thin-ship hydrodynamics. We demonstrate that for some integrals, rapid oscillation, rather than being a hindrance to accurate quadrature, can actually be beneficial if appropriate techniques are employed. We find that boundary layer displacement thickness effects on wave resistance are very small and can be safely ignored for full-size vessels. On the other hand, the idea of a detachment layer, an indication of where the boundary layer begins to thicken rapidly, is shown to have a significant effect on wave resistance. A modification to the Kelvin free-surface boundary condition is used as a means of including viscous effects on wave-making. Detailed comparisons of total resistance predictions and experiments are made for three model-size Wigley hulls. It is shown that inclusion of viscous effects smooths out the well-known humps and hollows in the wave resistance curves calculated using Michell's (inviscid) integral. Predictions of the total resistance of a model Wigley hull using Michell's integral and a simple skin-friction line are shown to be as good as those of a modern CFD computer code. Furthermore, the simple method does so in a very small time on an inexpensive computer. The effect of employing a form factor on the skin-friction is shown to improve correlations between resistance predictions and experiments. It has recently been proposed that a form factor should also be applied to the wave resistance. We show that good predictions are indeed possible, but that the use of a modified form of Michell's integral and an “appropriate" value of the eddy viscosity leads to even better agreement. Two existing wave-decay models are examined and a new formulation is suggested that combines the theoretical – 1/2 decay rate of transverse waves with the -1/3 decay rate of diverging waves. The effects of viscosity on ship-wave decay are considered. It is found that large values of the viscosity, of the order required to have a significant effect on wave resistance, lead to an over-damping of far-field waves at low Froude numbers. We show that it may be possible to get a rough estimate of the (ambient) eddy viscosity from an analysis of the decay of ship-waves with transverse distance from the sailing line, without resorting to computationally expensive Fourier transform methods. Three wave decay models are used to estimate the eddy viscosity from the behaviour of the wave decay. The model that uses the theoretical decay rates of transverse and of diverging waves is found to be slightly better at recapturing the original eddy viscosity than the other two models. / Thesis (Ph.D.) - University of Adelaide, School of Mathematical Sciences, 2009

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisor: Roy F. Schwitters. Vita. Includes bibliographical references.

Thesis (M.S.)--University of Michigan, 1968.

Thesis--University of California, Berkeley, 1959. / Includes bibliographical references (p. 81-84).

Thesis (Ph. D.)--University of Chicago, Dept. of Physics, June 2003. / Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1964. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Measurements of the Ƭ lepton polarization and forward-backward polarization asymmetry near the Z° resonance using the OPAL detector are described. The measurements are based on analyses of [special characters omitted] decays from a sample of 144, 810 [special characters omitted] candidates corresponding to an integrated luminosity of 151 pb-1. Assuming that the Ƭ lepton decays according to V-A theory, the average Ƭ polarization near [special characters omitted] is measured to be [special characters omitted] = (-14.10 ± 0.73 ± 0.55)% and the Ƭ polarization forward-backward asymmetry to be [special characters omitted] = (-10.55 ± 0.76 ± 0.25)%, where the first error is statistical and the second systematic. Taking into account the small effects of the photon propagator, photon-Z° interference and photonic radiative corrections, these results can be expressed in terms of the lepton neutral current asymmetry parameters: AƬ = 0.1466 ± 0.0076 ± 0.0057, Ae = 0.1464 ± 0.0108 ± 0.0036. These measurements are consistent with the hypothesis of lepton universality and combine to give [special characters omitted] = 0.1455 ± 0.0073. Within the context of the standard model this combined result corresponds to sin [special characters omitted] = 0.23172 ± 0.00092. Combining these results with those from the other OPAL neutral current measurements yields a value of sin [special characters omitted] = 0.23211 ± 0.00068. / Graduate

A systematic study of the change in proton single-particle occupancies in two neutrinoless double beta decay candidates, 130Te to 130Xe and 136Xe to 136Ba, has been performed. Final states in 129Sb, 129I, 135I and 135Cs have been populated using the (d,3He) single proton removal reaction. The deuterons were accelerated to 101 MeV using the coupled azimuthally varying field and Ring cyclotrons at the Research Center for Nuclear Physics, University of Osaka. The outgoing ejectiles were momentum analysed using the Grand Raiden magnetic spectrometer. Absolute cross sections were measured for states up to 7 MeV in excitation. Transferred angular momenta were identified through a comparison of angular distributions with those calculated using the distorted-wave Born approximation. Spectroscopic factors were extracted from the experimental cross sections. In addition to the 0v2B decay candidates the reaction was also performed on 128Te, 132Xe, 134Xe and 138Ba as a consistency check. The occupancies of the nuclei were determined from the spectroscopic factors, the reaction model was normalised using a common normalisation factor across all targets. The change in occupancies between the 0v2B decay candidates and their daughters were then determined. The change in occupancies were then compared with those calculated by interacting shell model, interacting boson model and quasiparticle random phase approximation. This comparison showed that whilst the three theories were qualitatively able to reproduce the change in occupancies, quantitatively there are significant discrepancies. These are the same models that are used to determine the nuclear matrix elements governing the rate of 0v2B decay.

abstract: A search for Klong to pi0 nu nubar was performed on the initial Physics data taken by the KOTO collaboration by the 30-GeV proton synchrotron at JPARC, located in Tokai, Japan. The detector used in the experiment is an upgraded version of the E391 detector, KOTO's predecessor experiment performed at KEK. The analysis was performed on 2.49 E+11 ± (0.91%)stat ± (2.50%)syst kaon decays. The analysis uses Klong to 3pi0, Klong to 2pi0, and Klong to 2 gamma; for normalization and Monte Carlo validation. Based on my independent analysis, the single event sensitivity was determined to be 1.31 E-8 ± (1.22%)stat ± (7.12%)syst, comparable with the E391 result. An upper limit of 5.12 E-8 was measured for the Klong to pi0 nu nubar branching ratio at a 90% confidence level. / Dissertation/Thesis / Doctoral Dissertation Physics 2015