We present an analysis of the formation of charmonium resonances of heavy quark pairs immersed in a deconfined environment for a finite time interval. This is intended to model the J/ψ suppression due to the possible formation of a color screening quark gluon plasma in heavy ion collisions. In particular, we examine how the the χ(c) and J/ψ states are affected in a quantum mechanical suppression model. We then investigate how the momentum dependence of the fraction of J/ψ's that come from radiative χ(c) decays or that are directly created can affect the momentum dependence of the resulting J/ψ suppression. We examine under what circumstances could this suppression momentum dependence be enhanced. This is of interest since previous quantum mechanical analyses have failed to model the strong momentum dependence observed in heavy ion collisions.

We use the nonperturbative techniques of current algebra and PCAC (partial conservation of axial-vector currents) to compute the nonleptonic weak decays K → 2π and 3π, as well as the two-body and nonresonant three-body decays of the charmed D and F(D(s)) mesons. In the case of two-body decays, the constituent quark model is employed to calculate the resulting unphysical meson-meson reduced matrix elements. Using an analogous current algebra - PCAC prescription, the three-body meson decays are expressed in terms of the previously determined two-body amplitudes. We utilize the pole model to extract baryon-baryon reduced matrix elements from the B → B' π and B'γ weak decays, which are then also computed in the constituent quark model. We make predictions for more than sixty decays with essentially no free parameters and, in most cases, find reasonable agreement with the data.

Dijet angular distributions provide a excellent look at the interactions between partons. The measurements performed by the DO detector are the most precise accomplished to date at pp colliders and cover a larger angular range than previously possible. Both leading order and next-to-leading order QCD calculations show agreement with the data over a large range in dijet invariant mass. This comparison is limited mainly by the large size of the theoretical uncertainties which are larger than the experimental uncertainties for some mass ranges. Additionally, a limit on quark compositeness of Λ(C) > 1.1 TeV has been obtained.

In this dissertation, I explore the relationship between solar energetic particles (SEPs) and the interplanetary magnetic field, and I use observations of SEPs to probe the region of space between the Sun and the Earth. After an introduction of major concepts in heliospheric physics, describing some of the history of energetic particles and defining the data sets used in the work, the rest of this dissertation is organized around three major concepts related to energetic particle transport: magnetic field-line length, interplanetary turbulence, and particle scattering and diffusion. In Chapter 2, I discuss how energetic particles can be used to measure the lengths of field lines and how particle scattering complicates the interpretation of these measurements. I then propose applying these measurements to a particular open problem: the origin and properties of heliospheric current sheets. In the next chapter, I move from the large to small scale and apply energetic particle measurements to important problems in interplanetary turbulence. I introduce two energetic-particle features, one of which I discovered in the course of this work, which have size scales roughly that of the correlation scale of the turbulence (the largest scale over which observations are expected to be similar). I discuss how multi-spacecraft measurements of these energetic particle features can provide a measure of the correlation scale independent of the magnetic field measurements. Finally, I consider interplanetary scattering and diffusion in detail. I describe new observations of particle diffusion in the direction perpendicular to the average magnetic field, showing that particles only scatter a few times between their injection at the Sun and observation at the Earth. I also provide numerical simulation results of diffusion parallel to the field which can be used to correct for the effects of transport on the particles. These corrections allow inferences to be made about the particle energies at injection from observations of the event-integrated fluences at 1 AU. By carefully including scattering, cooling, field line meandering and turbulence effects, solar-energetic particles become a powerful tool for studying the inner heliosphere.

Revised; Originally Published 2006 / 5 pp.

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