Book Description

The main goal of the proposal was to explore the feasibility of making a precision measurement of a leptonic or semileptonic weak neutral current amplitude with unprecedented precision at Q[sup 2]“M[sub Z][sup 2]. In particular, a plan was outlined to develop an experiment at the Stanford Linear Accelerator Center (SLAC) to measure the left-right asymmetry in the scattering of high energy longitudinally polarized electrons off atomic electrons in a liquid hydrogen target, a process known as Moeller scattering. Measurements of the weak neutral current amplitude at Q[sup 2]“M[sub Z][sup 2] provide access to measurements of the electroweak mixing angle sin[sup 2][theta][sub W]. This fundamental parameter of the electroweak theory is expected to increase from its value at the Z pole by 3%. This ''running'' of sin[sup 2][theta][sub W] has never been observed with significant precision. The SLAC experiment would measure this running with a significance of 8[sigma]. In the process, the measurement becomes sensitive to parity violating electron electron interactions at a high energy scale of 10 TeV. Such sensitivity is very complementary to the discovery reach of high energy colliders, that are sensitive to 10 TeV parity conserving interactions. The principal activities of the grant since its commencement in August 1995 has been to develop an experimental proposal to measure the parity violating electroweak asymmetry in fixed target Moeller scattering at SLAC End Station A, as well as to develop the precision electronics that would be necessary to carry out the experiment.