Experiment E143 at SLAC performed deep-inelastic scattering measurements with polarized electrons incident on polarized protons and deuterons. The data for the beam energy of 29 GeV cover the kinematical range of $x\sb{\rm Bj}>0.03$ and $1

We demonstrate how the heavy baryon method, previously applied to chiral perturbation theory calculations involving the interactions of nucleons and pions, can be generalized to include interactions with the first nucleon resonance--$\Delta$(1232). The formalism is developed in terms of a small scale $\delta$ expansion, which refers to soft momenta, the pion mass and the nucleon-delta mass splitting $\Delta$ = $M\sb{\Delta} - M\sb{N}$. First applications of this chiral theory are presented, in particular the calculation of mass and wavefunction renormalization, threshold neutral pion photoproduction, and forward Compton scattering.

This thesis reports on two experiments conducted by the HAPPEx (Hall A Proton Parity Experiment) collaboration at the Thomas Jefferson National Accelerator Facility. For both, the weak neutral current interaction (WNC, mediated by the Z0 boson) is used to probe novel properties of hadronic targets. The WNC interaction amplitude is extracted by measuring the parity-violating asymmetry in the elastic scattering of longitudinally polarized electrons off unpolarized target hadrons. HAPPEx-III, conducted in the Fall of 2009, used a liquid hydrogen target at a momentum transfer of Q2 = 0.62 GeV2. The measured asymmetry was used to set new constraints on the contribution of strange quark form factors ([special characters omitted]) to the nucleon electromagnetic form factors. A value of APV = −23.803 ± 0.778 (stat) ± 0.359 (syst) ppm resulted in [special characters omitted] = 0.003 ± 0.010 (stat) ± 0.004 (syst) ± 0.009 (FF). PREx, conducted in the Spring of 2010, used a polarized electron beam on a 208Pb target at a momentum transfer of Q 2 = 0.009 GeV2. This parity-violating asymmetry can be used to obtain a clean measurement of the root-mean-square radius of the neutrons in the 208Pb nucleus. The Z 0 boson couples mainly to neutrons; the neutron weak charge is much larger than that of the proton. The value of this asymmetry is at the sub-ppm level and has a projected experimental fractional precision of 3%. We will describe the accelerator setup used to set controls on helicity-correlated beam asymmetries and the analysis methods for finding the raw asymmetry for HAPPEx-III. We will also discuss in some detail the preparations to meet the experimental challenges associated with measuring such a small asymmetry with the degree of precision required for PREx.