Reduction of uncertainties for the Qweak experiment
LE3 .A278 2008
2008
Barkanova, Svetlana
Acadia University
Bachelor of Science
Honours
Physics
There are four fundamental forces in the universe: strong, electromagnetic, weak and gravitational. The electromagnetic force is stronger than the weak force by many orders of magnitude (the relative strengths of the two forces depends upon the interaction distance) and as a result, the electromagnetic force masks the weak interaction making it dicult to measure. The weak force is the only one of the four that violates parity. Simply put, this means there is a dierence between a process involving the weak force and the mirror image of the same process. This unique property of the weak interaction has allowed scientists to infer much about the internal structure of nucleons (protons and neutrons) by measuring the asymmetry between a subatomic reaction such as electon-proton scattering and the mirror inversion of the same reaction. The past few decades have seen great advancements in the eld of particle physics. Many competing theories have been set forward as possible extensions of the Standard Model of Particle Physics (SM) and only recently have the technological advances in experimental science allowed for some of these to be tested. Technology has nally advanced to the point where parity violation (PV) can be used to either challenge or corroborate the SM, and this is the specic goal of the Qp weak experiment. The Qp weak experiment, scheduled to run at Thomas Jeerson National Accelerator Facility (Jeerson Lab) in Virginia in 2010 will measure the weak charge of the proton to unprecedented accuracy. A disparity between the measured weak charge and that predicted by the SM theory could signal the presence of new physics. The level of accuracy proposed for Qp weak has resulted in a very strict error budget with careful
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