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

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

See related reviews:
Charged Kaon Mass
Rare Kaon Decays
Dalitz Plot Parameters for ${{\mathit K}}$ $\rightarrow$ 3 ${{\mathit \pi}}$ Decays
${{\mathit K}}{}^{\pm}_{{{\mathit \ell}}3}$ and ${{\mathit K}}{}^{0}_{{{\mathit \ell}}3}$ Form Factors
${{\mathit K}^{\pm}}$ MASS   $493.677 \pm0.016$ MeV (S = 2.8)
${\mathit m}_{{{\mathit K}^{+}}}–{\mathit m}_{{{\mathit K}^{-}}}$   $-0.03 \pm0.09$ MeV 
${{\mathit K}^{\pm}}$ MEAN LIFE   $(1.2380 \pm0.0020) \times 10^{-8}$ s (S = 1.8)
$({\mathit \tau}_{{{\mathit K}^{+}}}–{\mathit \tau}_{{{\mathit K}^{-}}})/{\mathit \tau}_{\mathrm {average}}$   $0.0010 \pm0.0009$  (S = 1.2)
${{\mathit K}^{\pm}}$ CHARGE RADIUS   $0.560 \pm0.031$ fm 
${{\mathit K}^{+}}$ LONGITUDINAL POLARIZATION OF EMITTED ${{\mathit \mu}^{+}}$   $<-0.990$   CL=90.0%
FORWARD-BACKWARD ASYMMETRY IN ${{\boldsymbol K}^{\pm}}$ DECAYS
A$_{FB}({{\mathit K}}{}^{\pm{}}_{{{\mathit \pi}} {{\mathit \mu}} {{\mathit \mu}} }$) = ${\Gamma\mathrm {(cos({{\mathit \theta}}_{ {{\mathit K}} {{\mathit \mu}} })>0)}−\Gamma\mathrm {(cos({{\mathit \theta}}_{ {{\mathit K}} {{\mathit \mu}} })<0)}\over \Gamma\mathrm {(cos({{\mathit \theta}}_{ {{\mathit K}} {{\mathit \mu}} })>0)}+\Gamma\mathrm {(cos({{\mathit \theta}}_{ {{\mathit K}} {{\mathit \mu}} })<0)}}$   $<0.023$   CL=90.0%
${{\mathit K}^{-}}$ modes are charge conjugates of the modes below.
    constrained fit information