Experimental HEP Seminar

Latest TWIST on Muon Decay

Art Olin

TRIUMF & University of Victoria

The Standard Model (SM) makes precise predictions for the parameters that characterize the energy and angle distributions of positrons emitted in the decay of polarized positive muons. The SM postulates a V-A Lorentz structure, excluding all additional Lorentz invariant local terms. For this tree-level leptonic decay strong interactions contributions are O(10^-7 ).

The goal of the TRIUMF Weak Interaction Symmetry Test (TWIST) was set by Vladimir Selivanov two decades ago: to search for new physics through a simultaneous measurement of these decay parameters with an order of magnitude increase in precision. Our final data is analyzed and we are presently finalizing our assessment of systematic errors before unblinding the results. I will discuss the results from earlier stages of the experiment, our expectations for the final precision, and some of the challenges involved in performing a high precision measurement.