The strangeness contribution to the vector and axial form factors of the proton is presented for momentum transfers in the range 0.45

The LSND (Liquid Scintillator Neutrino Detector) experiment will be performed at LAMPF in the next several years. The main goal of the experiment is to search for [nu]{sub {mu}}-[nu]{sub e} oscillations with high sensitivity; however, an increasingly important by-product of this search is to measure [nu]p → [nu]p elastic scattering and determine the strange quark contribution, [Delta]s, to the spin of the proton. With the 800-MeV proton energy of LAMPF, neutrinos are produced from pion decay-in-flight with an average energy of about 150 MeV. This energy is sufficiently high so that the [nu]p → [nu]p cross section is large and is sufficiently low so that the low Q2 approximation (Q2 {much lt} m{sub p}2) is valid and the cross section can be expressed in a simple form dependent upon [Delta]s as the only unknown. LAMPF with its 1-mA proton intensity is, therefore, an ideal accelerator to perform this measurement. 12 refs., 7 figs., 2 tabs.

The goal of the G0 experiment is to determine the contribution of the strange quarks in the quark-antiquark sea to the structure of the nucleon. To this end, the experiment measured parityviolating asymmetries from elastic electron-proton scattering from 0.12 ≤ Q2 ≤ 1.0 (GeV/c)2 at Thomas Jefferson National Accelerator Facility. These asymmetries come from the interference of the electromagnetic and neutral weak interactions, and are sensitive to the strange quark contributions in the proton. The results from the forward-angle measurement, the linear combination of the strange electric and magnetic form factors GsE +[eta]GsM, suggest possible non-zero, Q2 dependent, strange quark contributions and provide new information to understand the magnitude of the contributions. This dissertation presents the analysis and results of the forward-angle measurement. In addition, the G0 experiment measured the beam-normal single-spin asymmetry in the elastic scattering of transversely polarized 3 GeV electrons from unpolarized protons at Q2 = 0.15, 0.25 (GeV/c)2 as part of the forward-angle measurement. The transverse asymmetry provides a direct probe of the imaginary component of the two-photon exchange amplitude, the complete description of which is important in the interpretation of data from precision electron-scattering experiments. The results of the measurement indicate that calculations using solely the elastic nucleon intermediate state are insufficient and generally agree with calculations that include significant inelastic hadronic intermediate state contributions. This dissertation presents the analysis and results of this measurement.

One of the main challenges in nuclear and particle physics in the last 20 years has been to understand how the proton's spin is built up from its quark and gluon constituents. Quark models generally predict that about 60% of the proton's spin should be carried by the spin of the quarks inside, whereas high energy scattering experiments have shown that the quark spin contribution is small - only about 30%. This result has been the underlying motivation for about 1000 theoretical papers and a global program of dedicated spin experiments at BNL, CERN, DESY and Jefferson Laboratory to map the individual quark and gluon angular momentum contributions to the proton's spin, which are now yielding exciting results. This book gives an overview of the present status of the field: what is new in the data and what can be expected in the next few years. The emphasis is on the main physical ideas and the interpretation of spin data. The interface between QCD spin physics and the famous axial U(1) problem of QCD (eta and etaprime meson physics) is also highlighted. Book jacket.

Neutrinos can be used as a unique and informative probe of the structure within nucleons. This thesis presents the tools and methodology for studying the strange quark spin in the nucleon through neutral current elastic neutrino-proton scattering in the MicroBooNE experiment located at the Fermi National Accelerator Lab. An automated boosted decision tree based proton identification algorithm is used to select proton in liquid argon TPC data with a 70% efficiency. After a set of protons are selected, a logistic regression model is used to select neutral current elastic proton interactions in MicroBooNE. Neutral current elastic proton interactions are selected with an 11% efficiency and 30% purity.

The G0 (G-Zero) forward angle experiment completed in Hall C of the Thomas Jefferson National Accelerator Facility (TJNAF) has measured the parity violating asymmetries in elastic electron-proton scattering over a Q2 range of 0.12