STRANGE MESONS($\boldsymbol S$ = $\pm1$, $\boldsymbol C$ = $\boldsymbol B$ = 0) ${{\mathit K}^{+}}$ = ${\mathit {\mathit u}}$ ${\mathit {\overline{\mathit s}}}$, ${{\mathit K}^{0}}$ = ${\mathit {\mathit d}}$ ${\mathit {\overline{\mathit s}}}$, ${{\overline{\mathit K}}^{0}}$ = ${\mathit {\overline{\mathit d}}}$ ${\mathit {\mathit s}}$, ${{\mathit K}^{-}}$ = ${\mathit {\overline{\mathit u}}}$ ${\mathit {\mathit s}}$, similarly for ${{\mathit K}^{*}}$'s INSPIRE search

# ${{\boldsymbol K}^{0}}$ $I(J^P)$ = $1/2(0^{-})$

 See related review: $\mathit CPT$ Invariance Tests in Neutral Kaon Decay
 ${{\mathit K}^{0}}$ MASS $497.611 \pm0.013$ MeV (S = 1.2)
 ${\mathit m}_{{{\mathit K}^{0}}}–{\mathit m}_{{{\mathit K}^{\pm}}}$ $3.934 \pm0.020$ MeV (S = 1.6)
 ${{\mathit K}^{0}}$ MEAN SQUARE CHARGE RADIUS $-0.077 \pm0.010$ fm${}^{2}$
$\boldsymbol T$-VIOLATION PARAMETER IN ${{\boldsymbol K}^{0}}-{{\overline{\boldsymbol K}}^{0}}$ MIXING
 ASYMMETRY $\mathit A_{\mathit T}$ IN ${{\mathit K}^{0}}-{{\overline{\mathit K}}^{0}}$ MIXING $0.0066 \pm0.0016$
$\boldsymbol CP$-VIOLATION PARAMETERS
 Re($\epsilon$) $0.001596 \pm0.000013$
$\boldsymbol CPT$-VIOLATION PARAMETERS
 REAL PART OF $\delta$ $(2.5 \pm2.3) \times 10^{-4}$
 IMAGINARY PART OF $\delta$ $(-1.5 \pm1.6) \times 10^{-5}$
 Re(y) $0.0004 \pm0.0025$
 Re(x$_{-}$) $-0.0029 \pm0.0020$
 $\vert{}{\mathit m}_{{{\mathit K}^{0}}}–{\mathit m}_{{{\overline{\mathit K}}^{0}}}\vert{}/{\mathit m}_{\mathrm {average}}$ $<6 \times 10^{-19}$   CL=90.0%
 (${\Gamma}_{{\mathit K}^{0}}−{\Gamma}_{{\overline{\mathit K}}^{0}})/{\mathit m}_{{\mathrm {average}}}$ $(8 \pm8) \times 10^{-18}$
TESTS OF $\Delta \boldsymbol S$ = $\Delta \boldsymbol Q$ RULE
 Re(x$_{+}$) $-0.0009 \pm0.0030$