# $\boldsymbol T$-VIOLATION PARAMETER IN ${{\boldsymbol K}^{0}}-{{\overline{\boldsymbol K}}^{0}}$ MIXING

The asymmetry $\mathit A_{\mathit T}$ = ${\Gamma\mathrm {({{\overline{\mathit K}}^{0}} \rightarrow {{\mathit K}^{0}} )} − \Gamma\mathrm {({{\mathit K}^{0}} \rightarrow {{\overline{\mathit K}}^{0}} )}\over \Gamma\mathrm {({{\overline{\mathit K}}^{0}} \rightarrow {{\mathit K}^{0}} )} + \Gamma\mathrm {({{\mathit K}^{0}} \rightarrow {{\overline{\mathit K}}^{0}} )}}$ must vanish if $\mathit T~$invariance holds.

# ASYMMETRY $\boldsymbol A_{\boldsymbol T}$ IN ${{\boldsymbol K}^{0}}-{{\overline{\boldsymbol K}}^{0}}$ MIXING INSPIRE search

VALUE ($10^{-3}$) EVTS DOCUMENT ID TECN
$6.6$ $\pm1.3$ $\pm1.0$ 640k 1
 1998 E
CPLR
1  ANGELOPOULOS 1998E measures the asymmetry $\mathit A_{\mathit T}$= [$\Gamma\mathrm {({{\overline{\mathit K}}} {}^{0}_{\mathit t=0} \rightarrow {{\mathit e}^{+}} {{\mathit \pi}^{-}} {{\mathit \nu}} _{\mathit t={{\mathit \tau}}} )}$ $−$ $\Gamma\mathrm {({{\mathit K}} {}^{0}_{\mathit t=0} \rightarrow {{\mathit e}^{-}} {{\mathit \pi}^{+}} {{\overline{\mathit \nu}}} _{\mathit t={{\mathit \tau}}} )}]/[\Gamma\mathrm {({{\overline{\mathit K}}} {}^{0}_{\mathit t=0} \rightarrow {{\mathit e}^{+}} {{\mathit \pi}^{-}} {{\mathit \nu}} _{\mathit t={{\mathit \tau}}} )}$ $+$ $\Gamma\mathrm {({{\mathit K}} {}^{0}_{\mathit t=0} \rightarrow {{\mathit e}^{-}} {{\mathit \pi}^{+}} {{\overline{\mathit \nu}}} _{\mathit t={{\mathit \tau}}} )}$] as a function of the neutral-kaon eigentime$~\tau$. The initial strangeness of the neutral kaon is tagged by the charge of the accompanying charged kaon in the reactions ${{\mathit p}}$ ${{\overline{\mathit p}}}$ $\rightarrow$ ${{\mathit K}^{-}}{{\mathit \pi}^{+}}{{\mathit K}^{0}}$ and ${{\mathit p}}$ ${{\overline{\mathit p}}}$ $\rightarrow$ ${{\mathit K}^{+}}{{\mathit \pi}^{-}}{{\overline{\mathit K}}^{0}}$ . The strangeness at the time of the decay is tagged by the lepton charge. The reported result is the average value of $\mathit A_{\mathit T}$ over the interval 1$\tau _{\mathit s}<\tau <20\tau _{\mathit s}$. From this value of $\mathit A_{\mathit T}$ ANGELOPOULOS 2001B, assuming $\mathit CPT$ invariance in the ${{\mathit e}}{{\mathit \pi}}{{\mathit \nu}}$ decay amplitude, determine the $\mathit T$-violating as $\Delta \mathit S=\Delta \mathit S$ conserving parameter (for its definition, see Review below) 4Re($\epsilon$) = $0.0062$ $\pm0.0014$ $\pm0.0010$.
Conservation Laws:
 TIME REVERSAL ($\mathit T$) INVARIANCE
References:
 ANGELOPOULOS 1998E
PL B444 43 First Direct Observation of Time Reversal NonInvariance in the Neutral Kaon System