Measurements of the Antineutrino Spin Asymmetry in Beta Decay of the Neutron and Restrictions on the Mass of a Right-Handed Gauge Boson

We report a new measurement of the neutron antineutrino spin asymmetry coefficient $B$ in the beta decay of polarized neutrons. Combining results of measurements of the observed asymmetry $PB=0.6617\mathrm{}\pm 0.0044$ with measurements of the neutron beam polarization $P=(66.88\pm 0.22)$%, we obtain the value $B=0.9894\mathrm{}\pm 0.0083$. This value implies that the mass of a hypothetical right-handed charged gauge boson in the left-right symmetric model of the weak interaction is greater than $281\mathrm{GeV}/c^2$ (90% C. L.). This is in agreement with restrictions from muon decay and direct searches for an additional vector boson $W^{\prime }$.