Annual Review of Nuclear and Particle Science vol:61 pages:23-46
Precision measurements in nuclear β decay provide sensitive means to test
the structure of the standard electroweak model; they also allow the determination
of fundamental properties in processes that involve the lightest quarks.
The primary aim of such tests is to find deviations from the Standard Model
predictions that may indicate new physics. We review here the status of precision
measurements in nuclear β decay, including selected experiments in
neutron decay, and discuss recent results and developments. Among these
developments are the consideration of nuclear mirror transitions as a new
window in which to test the unitarity condition of the Cabibbo-Kobayashi-
Maskawa quark-mixing matrix, measurements of angular correlation observables
to search for exotic couplings, and tests of discrete symmetries.