Speaker
Description
Nuclear beta decay has a long-standing history of shaping and testing the standard model of particle physics, and it continues to this day with elegant, ultra-precise low-energy nuclear measurements. Experiments observing the angular correlations between the electron, neutrino and recoil momenta following nuclear beta decay can be used to search for exotic currents contributing to the dominant V-A structure of the weak interaction. Precision measurements of the correlation parameters to <0.1% would be sensitive to (or meaningfully constrain) new physics, complementing other searches at large-scale facilities like the LHC.
Atom traps provide an ideal source of very cold, short-lived radioactive nuclei in an extremely clean and open environment. As such, they are invaluable tools for precision measurements of beta-decay parameters. The TRIUMF Neutral Atom Trap (TRINAT) collaboration utilizes neutral atom-trapping techniques with optical pumping methods to highly polarize (>99%) 37K atoms. Recently, we determined the beta asymmetry parameter, A_beta, to 0.3%, which is comparable to
or better than any other nuclear measuement, including the neutron. In terms of minimal left-right symmetric models, this implies a limit of >351 GeV for the mass of a possible right-handed W. Alternatively, one may interpret the result as a 4.4x better measurement of V_ud from 37K.
