New limit on the<b><i>D</i></b>coefficient in polarized neutron decay

Abstract

We describe an experiment that has set new limits on the time reversal invariance violating D coefficient in neutron $\ensuremath{\beta}$ decay. The emiT experiment measured the angular correlation $〈\mathbf{J}〉\ensuremath{\cdot}({\mathbf{p}}_{e}\ifmmode\times\else\texttimes\fi{}{\mathbf{p}}_{p})$ using an octagonal symmetry that optimizes electron-proton coincidence rates. The result is $D=[\ensuremath{-}0.6\ifmmode\pm\else\textpm\fi{}1.2(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.5(\mathrm{syst})]\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}.$ This improves constraints on the phase of ${g}_{A}{/g}_{V}$ and limits contributions to T violation due to leptoquarks. This paper presents details of the experiment, data analysis, and the investigation of systematic effects.