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

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

See related review:
$\mathit CP$ Violation in ${{\mathit K}_S^0}$ $\rightarrow$ 3 ${{\mathit \pi}}$
${{\boldsymbol K}_S^0}$ MEAN LIFE
Mean life $\tau $   $(8.954 \pm0.004) \times 10^{-11}$ s (S = 1.1)
${{\boldsymbol K}_S^0}$ FORM FACTORS
$\lambda _{+}$ (LINEAR ENERGY DEPENDENCE OF $\mathit f_{+}$ IN ${{\mathit K}_{{e3}}^{0}}$ DECAY)   $0.034 \pm0.004$  
$\boldsymbol CP$-VIOLATION PARAMETERS IN ${{\boldsymbol K}_S^0}$ DECAY
${{\mathit A}_{{S}}}$ = [ $\Gamma\mathrm {( {{\mathit K}_S^0} \rightarrow {{\mathit \pi}^{-}} {{\mathit e}^{+}} {{\mathit \nu}_{{e}}} )} - \Gamma\mathrm {( {{\mathit K}_S^0} \rightarrow {{\mathit \pi}^{+}} {{\mathit e}^{-}} {{\overline{\mathit \nu}}_{{e}}} )}$ ] $/$ SUM   $0.002 \pm0.010$  
PARAMETERS FOR ${{\boldsymbol K}_S^0}$ $\rightarrow$ 3 ${{\boldsymbol \pi}}$ DECAY
Im($\eta _{+−0}){}^{2}$ = $\Gamma\mathrm {( {{\mathit K}_S^0} \rightarrow {{\mathit \pi}^{+}} {{\mathit \pi}^{-}} {{\mathit \pi}^{0}} , \mathit CP-violating)}$ $/$ $\Gamma\mathrm {( {{\mathit K}_L^0} \rightarrow {{\mathit \pi}^{+}} {{\mathit \pi}^{-}} {{\mathit \pi}^{0}} )}$
Im($\eta _{+−0}$) = Im(A( ${{\mathit K}_S^0}$ $\rightarrow$ ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \pi}^{0}}$ , $\mathit CP$-violating) $/$ A( ${{\mathit K}_L^0}$ $\rightarrow$ ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \pi}^{0}}$ ))   $-0.002 \pm0.009$  
Im($\eta _{000}){}^{2}$ = $\Gamma\mathrm {( {{\mathit K}_S^0} \rightarrow 3 {{\mathit \pi}^{0}} )}$ / $\Gamma\mathrm {( {{\mathit K}_L^0} \rightarrow 3 {{\mathit \pi}^{0}} )}$
Im($\eta _{000}$) = Im($\mathit A$( ${{\mathit K}_S^0}$ $\rightarrow$ ${{\mathit \pi}^{0}}{{\mathit \pi}^{0}}{{\mathit \pi}^{0}}$ )/$\mathit A$( ${{\mathit K}_L^0}$ $\rightarrow$ ${{\mathit \pi}^{0}}{{\mathit \pi}^{0}}{{\mathit \pi}^{0}}$ ))   $-0.001 \pm0.016$  
$\vert \eta _{000}\vert $ = $\vert \mathit A$( ${{\mathit K}_S^0}$ $\rightarrow$ 3 ${{\mathit \pi}^{0}}$ )/$\mathit A$( ${{\mathit K}_L^0}$ $\rightarrow$ 3 ${{\mathit \pi}^{0}}$ )$\vert $   $<0.0088$   CL=90.0%
DECAY-PLANE ASYMMETRY IN ${{\boldsymbol \pi}^{+}}{{\boldsymbol \pi}^{-}}{{\boldsymbol e}^{+}}{{\boldsymbol e}^{-}}$ DECAYS
$\mathit CP$ asymmetry $\mathit A$ in ${{\mathit K}_S^0}$ $\rightarrow$ ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit e}^{+}}{{\mathit e}^{-}}$   $-0.004 \pm0.008$  
    constrained fit information