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The experiments discussed in this thesis exploit parity violation in elastic electron proton scattering in order to measure properties of the nucleon. Both experiments make use of the high quality, highly polarized electron beam available at Thomas Jefferson National Accelerator Facility. Q_weak will measure the weak mixing angle, sin²θ_W, via a measurement of the weak charge of the proton, at a four-momentum transfer, Q² ~ 0.026 GeV²/c². The precision of this measurement gives Q_weak access to new physics at the scale of 2.3 TeV, making it a test of the standard model. The G⁰ experimental program provides the fully separated contributions of the strange quark to the charge and magnetization distributions of the nucleon at two different values of four-momentum transfer, Q² ~ 0.22 and 0.63 GeV²/c². The measurement of the strange quark content of the proton in the G⁰ experimental program and other parity-violating electron scattering experiments provides a measurement of the hadronic contribution to the asymmetry in Q_weak. In addition, G⁰ was able to measure the parity-conserving beam normal single spin asymmetries that provide a measurement of the imaginary part of two photon exchange. The measurement of this asymmetry is necessary to understand the systematic contribution to measurements of parity-violating asymmetries, but it is also an important physics result. Recent theoretical work has shown that higher order radiative effects, such as two photon exchange, may be able to explain discrepancies between experiments which measure the ratio of the electric and magnetic form factors of the proton. The measurement of the transverse or beam normal single spin asymmetries provides a benchmark for theories that estimate the size of radiative corrections that are important for precision electroweak scattering experiments such as those described in this thesis. The results of the measurement of the transverse asymmetries at backward angles in G⁰ are presented at the two values of Q² ~ 0.22 and 0.63 GeV²/c² for hydrogen. Results for deuterium, which can provide the first measurements of the beam normal single spin asymmetries on the neutron, are also presented. / Ph. D.

<p>The Standard Model describes all elementary particles known today, but at larger energies it will have to be complemented with new particles and interactions. To be able to distinguish new physics at proton colliders such as LHC at CERN, it is essential to have an appropriate description of the colliding protons and their interactions. The study of the proton is important also in itself, to get a better understanding of the non-perturbative aspects of the strong interaction.</p><p>In paper I-IV of this thesis, a model for the non-perturbative dynamics of quarks and gluons is developed, based on quantum fluctuations in hadrons. The parton distributions of the proton are given by momentum fluctuations, with sea quark distributions generated by fluctuations into baryon-meson pairs. This model can reproduce proton structure function data, as well as measured asymmetries between up and down valence quark distributions and between the anti-up and anti-down sea. It provides an intrinsic charm quark component as indicated by data. It also predicts an asymmetry in the strange sea of the proton, which can explain the NuTeV anomaly first attributed to new physics beyond the Standard Model.</p><p>Charged Higgs bosons are predicted by several theories for new physics, including Supersymmetry. At proton colliders, the predicted dominant production mechanism is in association with top and bottom quarks. In paper V-VII, different contributions to this production are studied, and an algorithm is developed for combining the two dominant processes gb -> tH^+/- and gg -> tbH^+/-. The algorithm gives a smooth transition from small to large transverse momenta of the b-quark, which is important when the b-quark is observed. It also gives arguments for the choice of factorisation scale in the process.</p>

The Standard Model describes all elementary particles known today, but at larger energies it will have to be complemented with new particles and interactions. To be able to distinguish new physics at proton colliders such as LHC at CERN, it is essential to have an appropriate description of the colliding protons and their interactions. The study of the proton is important also in itself, to get a better understanding of the non-perturbative aspects of the strong interaction. In paper I-IV of this thesis, a model for the non-perturbative dynamics of quarks and gluons is developed, based on quantum fluctuations in hadrons. The parton distributions of the proton are given by momentum fluctuations, with sea quark distributions generated by fluctuations into baryon-meson pairs. This model can reproduce proton structure function data, as well as measured asymmetries between up and down valence quark distributions and between the anti-up and anti-down sea. It provides an intrinsic charm quark component as indicated by data. It also predicts an asymmetry in the strange sea of the proton, which can explain the NuTeV anomaly first attributed to new physics beyond the Standard Model. Charged Higgs bosons are predicted by several theories for new physics, including Supersymmetry. At proton colliders, the predicted dominant production mechanism is in association with top and bottom quarks. In paper V-VII, different contributions to this production are studied, and an algorithm is developed for combining the two dominant processes gb -&gt; tH+/- and gg -&gt; tbH+/-. The algorithm gives a smooth transition from small to large transverse momenta of the b-quark, which is important when the b-quark is observed. It also gives arguments for the choice of factorisation scale in the process.