pdgLive

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:

S010

${{\mathit K}^{\pm}}$

$I(J^P)$ = $1/2(0^{-})$

See related reviews:

Charged Kaon Mass
Rare Kaon Decays
Dalitz Plot Parameters for ${{\mathit K}}$ $\rightarrow$ 3 ${{\mathit \pi}}$ Decays

${{\mathit K}^{\pm}}$ 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)

$({\mathit \tau}_{{{\mathit K}^{+}}}–{\mathit \tau}_{{{\mathit K}^{-}}})/{\mathit \tau}_{\mathrm {average}}$

$(1.0 \pm0.9) \times 10^{-3}$ (S = 1.2)

▸	$\mathit CPT$ VIOLATION TESTS IN ${{\mathit K}^{\pm}}$ DECAYS

▸	$\mathit CP$ VIOLATION TESTS IN ${{\mathit K}^{\pm}}$ DECAYS

▸	$\mathit T$ VIOLATION TESTS IN ${{\mathit K}^{+}}$ AND ${{\mathit K}^{-}}$ DECAYS

▸	ENERGY DEPENDENCE OF ${{\mathit K}^{\pm}}$ DALITZ PLOT

▸	ALTERNATIVE PARAMETRIZATIONS OF ${{\mathit K}^{\pm}}$ $\rightarrow$ ${{\mathit \pi}^{\pm}}{{\mathit \pi}^{0}}{{\mathit \pi}^{0}}$ DALITZ PLOT

▸	${{\mathit K}_{{{{\mathit \ell}}3}}^{\pm}}$ FORM FACTORS

▸	${{\mathit K}_{{{{\mathit \ell}}4}}^{\pm}}$ FORM FACTORS

▸	${{\mathit K}^{\pm}}$ $\rightarrow$ ${{\mathit \ell}^{\pm}}{{\mathit \nu}}{{\mathit \gamma}}$ FORM FACTORS

${{\mathit K}^{\pm}}$ CHARGE RADIUS

$0.560 \pm0.031$ fm

${{\mathit K}^{+}}$ LONGITUDINAL POLARIZATION OF EMITTED ${{\mathit \mu}^{+}}$

$<-0.990$ CL=90.0%

FORWARD-BACKWARD ASYMMETRY IN ${{\mathit K}^{\pm}}$ DECAYS

A$_{FB}({{\mathit K}}{}^{\pm{}}_{{{\mathit \pi}} {{\mathit \mu}} {{\mathit \mu}} }$) = ${\Gamma\mathrm {(cos({{\mathit \theta}}_{ {{\mathit K}} {{\mathit \mu}} })>0)}−\Gamma\mathrm {(cos({{\mathit \theta}}_{ {{\mathit K}} {{\mathit \mu}} })<0)}\over \Gamma\mathrm {(cos({{\mathit \theta}}_{ {{\mathit K}} {{\mathit \mu}} })>0)}+\Gamma\mathrm {(cos({{\mathit \theta}}_{ {{\mathit K}} {{\mathit \mu}} })<0)}}$

$<0.009$ CL=90.0%

${{\mathit K}^{+}}$ DECAY MODES ▸ Expand all decays

${{\mathit K}^{-}}$ modes are charge conjugates of the modes below.

▸	Leptonic and semileptonic modes

▸	Hadronic modes

▸	Leptonic and semileptonic modes with photons

▸	Hadronic modes with photons or ${{\mathit \ell}}{{\overline{\mathit \ell}}}$ pairs

▸	Leptonic modes with ${{\mathit \ell}}{{\overline{\mathit \ell}}}$ pairs

▸	Lepton family number ($\mathit LF$), Lepton number ($\mathit L$), $\Delta \mathit S$ = $\Delta \mathit Q$ ($\mathit SQ$) violating modes, or $\Delta \mathit S$ = 1 weak neutral current ($\mathit S1$) modes

FOOTNOTES

Constrained Fit information

Except where otherwise noted, content of the 2023 Review of Particle Physics is licensed under a Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) license. The publication of the Review of Particle Physics is supported by US DOE, MEXT (Japan), INFN (Italy), JPS and CERN. Individual collaborators receive support for their PDG activities from their respective institutes or funding agencies. © 2023. See LBNL disclaimers.

CONTACT US

Email:

Mailing Address:

Were you looking to order PDG products?

CITATION

MIRRORS

${{\mathit K}^{\pm}}$