A muon-spin-rotation technique has been used to place limits on right-handed currents in ${\mu }^{+}$ decay. The spins of polarized ${\mu }^{+}$ stopped in metal targets were precessed by 70-G or 110-G transverse fields. The muon-spin-rotation signal amplitude produced by high-momentum decay $e^{+}$ emitted near the beam direction implies $\frac{\xi P_{\mu }\delta }{\rho }>0.9955\mathrm{}$ and $M\left(W_2\right)>\mathrm{}370\mathrm{}$ GeV (90% confidence), where $W_2$ is a predominantly right-handed gauge boson. The present result combined with our previous spin-held analysis yields $\frac{\xi P_{\mu }\delta }{\rho }>0.9966\mathrm{}$ and $M\left(W_2\right)>\mathrm{}400\mathrm{}$ GeV.

• Received 14 January 1985

DOI:https://doi.org/10.1103/PhysRevLett.54.1887