SEARCH FOR T-VIOLATING TRANSVERSE MUON POLARIZATION IN K+ PI 0MU +NU DECAY USING STOPPED KAONS

An improved search for a $T$-violating transverse muon polarization $({P}_{T})$ in ${K}^{+}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{\ensuremath{\mu}}^{+}\ensuremath{\nu}$ decay was performed using kaon decays at rest. By means of this method, ${P}_{T}$ was extracted with small systematic errors, ${P}_{T}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\ensuremath{-}0.0042\ifmmode\pm\else\textpm\fi{}0.0049(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.0009(\mathrm{syst})$, and the $T$-violation parameter was determined to be $\mathrm{Im}\ensuremath{\xi}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\ensuremath{-}0.013\ifmmode\pm\else\textpm\fi{}0.016(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.003(\mathrm{syst})$.