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STRANGE MESONS ($\mathit S$ = $\pm1$, $\mathit C$ = $\mathit B$ = 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   JSON  (beta) PDGID: S012

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

See related review:
$\mathit CP$ Violation in ${{\mathit K}_S^0}$ $\rightarrow$ 3 ${{\mathit \pi}}$

${{\mathit K}_S^0}$ MEAN LIFE

Mean life $\tau $   $(8.954 \pm0.004) \times 10^{-11}$ s (S = 1.1)  ...

${{\mathit K}_S^0}$ FORM FACTORS

$\lambda _{+}$ (LINEAR ENERGY DEPENDENCE OF $\mathit f_{+}$ IN ${{\mathit K}_{{e3}}^{0}}$ DECAY)   $0.034 \pm0.004$

$\mathit CP$-VIOLATION PARAMETERS IN ${{\mathit K}_S^0}$ 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   $-0.004 \pm0.006$

PARAMETERS FOR ${{\mathit K}_S^0}$ $\rightarrow$ 3 ${{\mathit \pi}}$ 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($\eta _{000}$) = 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 ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit e}^{+}}{{\mathit e}^{-}}$ DECAYS

$\mathit CP$ asymmetry $\mathit A$ in ${{\mathit K}_S^0}$ $\rightarrow$ ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit e}^{+}}{{\mathit e}^{-}}$   $-0.004 \pm0.008$

${{\mathit K}_S^0}$ DECAY MODES ▸  Expand all decays
Mode   Fraction ($\Gamma_i$ / $\Gamma$) Scale Factor/ Conf. Level P(MeV/c)   ▸ Hadronic modes ▸ Modes with photons or ${{\mathit \ell}}{{\overline{\mathit \ell}}}$ pairs ▸ Semileptonic modes ▸ $\mathit CP$ violating ($\mathit CP$) and $\Delta \mathit S$ = 1 weak neutral current ($\mathit S1$) modes
FOOTNOTES

Constrained Fit information