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 PDGID:
S013

${{\mathit K}_L^0}$

$I(J^P)$ = $1/2(0^{-})$ 
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$\Delta \mathit m$ ($52.81$ $\pm0.09$) $ \times 10^{8}$ $\hbar{}$ s${}^{-1}$ 
 
${{\mathit K}_L^0}$ MEAN LIFE ($5.099$ $\pm0.021$) $ \times 10^{-8}$ s 
 
▸  ENERGY DEPENDENCE OF ${{\mathit K}_L^0}$ DALITZ PLOT
▸  ${{\mathit K}_L^0}$ FORM FACTORS
▸  CHARGE ASYMMETRY IN ${{\mathit K}_{{{\ell3}}}^{0}}$ DECAYS
▸  PARAMETERS FOR ${{\mathit K}_L^0}$ $\rightarrow$ 2 ${{\mathit \pi}}$ DECAY
▸  DECAY-PLANE ASYMMETRY IN ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit e}^{+}}{{\mathit e}^{-}}$ DECAYS
▸  PARAMETERS FOR ${{\mathit e}^{+}}{{\mathit e}^{-}}{{\mathit e}^{+}}{{\mathit e}^{-}}$ DECAYS
▸  CHARGE ASYMMETRY IN ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \pi}^{0}}$ DECAYS
▸  PARAMETERS for ${{\mathit K}_L^0}$ $\rightarrow$ ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \gamma}}$ DECAY
▸  $\mathit T$ VIOLATION TESTS IN ${{\mathit K}_L^0}$ DECAYS
▸  $\mathit CPT$-INVARIANCE TESTS IN ${{\mathit K}_L^0}$ DECAYS
▸  $\mathit x$ = A(${{\overline{\mathit K}}^{0}}$ $\rightarrow$ ${{\mathit \pi}^{-}}{{\mathit \ell}^{+}}{{\mathit \nu}})/A({{\mathit K}^{0}}$ $\rightarrow$ ${{\mathit \pi}^{-}}{{\mathit \ell}^{+}}{{\mathit \nu}}$) = A($\Delta \mathit S=−\Delta \mathit Q)/A(\Delta \mathit S=\Delta \mathit Q$)
Mode  
Fraction ($\Gamma_i$ / $\Gamma$) Scale Factor/
Conf. Level		 P(MeV/c)  
▸  Semileptonic modes
▸  Hadronic modes, including Charge conjugation${\times }$Parity Violating ($\mathit CPV$) modes
▸  Semileptonic modes with photons
▸  Hadronic modes with photons or ${{\mathit \ell}}{{\overline{\mathit \ell}}}$ pairs
▸  Other modes with photons or ${{\mathit \ell}}{{\overline{\mathit \ell}}}$ pairs
▸  Charge conjugation ${\times }$ Parity ($\mathit CP$) or Lepton Family number ($\mathit LF$) violating modes, or $\Delta \mathit S$ = 1 weak neutral current ($\mathit S1$) modes
▸  Lorentz invariance violating modes
[1] Re($\epsilon {{}^\prime}/\epsilon $) = $\epsilon {{}^\prime}/\epsilon $ to a very good approximation provided the phases satisfy $\mathit CPT$ invariance.
[2] The value is for the sum of the charge states or particle/antiparticle states indicated.
[3] This mode includes gammas from inner bremsstrahlung but not the direct emission mode ${{\mathit K}_L^0}$ $\rightarrow$ ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \gamma}}$(DE).
[4] See the Particle Listings below for the energy limits used in this measurement.
[5] Most of this radiative mode, the low-momentum ${{\mathit \gamma}}$ part, is also included in the parent mode listed without ${{\mathit \gamma}}$'s.
[6] Allowed by higher-order electroweak interactions.
[7] Violates $\mathit CP$ in leading order. Test of direct $\mathit CP$ violation since the indirect $\mathit CP$-violating and $\mathit CP$-conserving contributions are expected to be suppressed.
Constrained Fit information