The Physics Case for the New Muon (g-2) Experiment

Understand

This White Paper briefly reviews the present status of the muon (g-2) experiment and the physics motivation for a new effort.

• The present comparison between experiment and theory indicates a tantalizing $3.4 \sigma$ deviation.
• An improvement in precision on this comparison by a factor of 2--with the central value remaining unchanged--will exceed the ``discovery'' threshold, with a sensitivity above $6 \sigma$.
• The 2.5-fold reduction improvement goal of the new Brookhaven E969 experiment, along with continued steady reduction of the standard model theory uncertainty, will achieve this more definitive test.