Experimental Constraints on Left-Right Symmetric Models from Muon Decay

The TWIST Collaboration has completed a new measurement of the energy-angle spectrum of positrons from the decay of highly polarized muons. A simultaneous measurement of the muon decay parameters ρ, δ, and P_μ^πξ tests the standard model in a purely leptonic process and provides improved limits for relevant extensions to the standard model. Specifically, for the generalized left-right symmetric model |(gR/gL)ζ|<0.020 and (gL/gR)m₂>578 GeV/c², both 90% C.L.