The Scientific Impact and Feasibility of an Ultra-precise 12 GeV Moeller Experiment to Test the Standard Model
December 11-13, 2006
Jefferson Lab, Newport News, VA USA
Workshop Consensus Statement
The availability of a stable, high intensity 11 GeV polarized electron beam with the Jefferson Laboratory Energy Upgrade provides an unprecedented opportunity to probe the limits of the electroweak theory through the study of parity-violation in Møller scattering. To explore this exciting possibility in detail, a workshop was held at Jefferson Laboratory, with participation from leading theorists and experimentalists in the field.
There was general consensus that a measurement of the parity-violating asymmetry with a total error five times smaller than for similar approved experiments at JLab was feasible. There was overwhelming enthusiasm to aggressively proceed with the design of such an experiment, which would yield a measurement of the weak mixing angle sin2θW(0) with an error between 0.0002 and 0.0003, which is more than a factor five improvement over the recent SLAC experiment. Such an experiment, with the stated precision, would continue JLab's world leadership role in electroweak physics, complementing similar efforts in beta-decay, g – 2, etc.
The broader physics impacts could be summarized as follows:
- Such a measurement would be the best low energy measurement and would be comparable to or better than the best single measurements at high-energy colliders of sin2θW, one of the most fundamental and important parameters of the electroweak theory.
- The combination of precision and clean interpretability would make it an essential complementary component of precision searches for physics beyond the standard model in the era of an active LHC program.
- Such a measurement would have unique sensitivity to properties of new physics phenomena such as R-parity violating SUSY, new heavy neutral gauge bosons, electron compositeness and lepton-number violating interactions mediated by charged Higgs bosons.
In terms of feasibility of the project, some of the points made were:
- The success of SLAC-E158 and the degree of systematic control achieved by the JLab parity violation program make it clear that such a precise measurement is feasible.
- The level of experimental control necessary, while unprecedented, appears within reach given recent experimental progress.
- The beam time required would be of the order of 4000 hours.
- Although not part of the baseline equipment, we note that the cost of such an endeavor would be comparable to other single installation experiments that have occurred in Halls A and C.
- The interest shown by experimentalists attending the workshop bodes well for the building of an international collaboration that would be able to launch and complete the experiment in a timely manner.
- One can state unequivocally that techniques are available to demonstrate in a redundant manner that the errors due to systematic effects could be controlled at a level that is well below the statistical error.