In this thesis I present two complementary strategies for probing beyond-the-Standard Model physics using data collected in e{sup +}e{sup -} collisions at lepton colliders. One strategy involves searching for effects at low energy mediated by new particles at the TeV mass scale, at which new physics is expected to manifest. Several new physics scenarios, including Supersymmetry and models with leptoquarks or compositeness, may lead to observable rates for charged lepton-flavor violating processes, which are forbidden in the Standard Model. I present a search for lepton-flavor violating decays of the {Upsilon}(3S) using data collected with the BABAR detector. This study establishes the 90% confidence level upper limits BF({Upsilon}(3S) {yields} e{tau}) < 5.0 x 10{sup -6} and BF({Upsilon}(3S) {yields} {mu}{tau}) < 4.1 x 10{sup -6} which are used to place constraints on new physics contributing to lepton-flavor violation at the TeV mass scale. An alternative strategy is to increase the collision energy above the threshold for new particles and produce them directly. I discuss research and development efforts aimed at producing a vertex tracker which achieves the physics performance required of a high energy lepton collider. A small-scale vertex tracker prototype is constructed using Silicon sensors of 50 {mu}m thickness and tested …

While historically hydrogen has been considered an impurity in titanium, when used as a temporary alloying agent it promotes beneficial changes to material properties that increase the hot-workability of the metal. This technique known as thermohydrogen processing was used to temporarily alloy hydrogen with commercially pure titanium sheet as a means of facilitating the friction stir welding process. Specific alloying parameters were developed to increase the overall hydrogen content of the titanium sheet ranging from commercially pure to 30 atomic percent. Each sheet was evaluated to determine the effect of the hydrogen content on process loads and tool deformation during the plunge phase of the friction stir welding process. Two materials, H-13 tool steel and pure tungsten, were used to fabricate friction stir welding tools that were plunged into each of the thermohydrogen processed titanium sheets. Tool wear was characterized and variations in machine loads were quantified for each tool material and weld metal combination. Thermohydrogen processing was shown to beneficially lower plunge forces and stabilize machine torques at specific hydrogen concentrations. The resulting effects of hydrogen addition to titanium metal undergoing the friction stir welding process are compared with modifications in titanium properties documented in modern literature. Such comparative …