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${{\mathit \Lambda}}$ BARYONS ($\mathit S$ = $-1$, $\mathit I$ = 0) ${{\mathit \Lambda}^{0}}$ = ${\mathit {\mathit u}}$ ${\mathit {\mathit d}}$ ${\mathit {\mathit s}}$

INSPIRE   JSON PDGID: S018

${{\mathit \Lambda}}$ $I(J^P)$ = $0(1/2^{+})$

We have omitted some results that have been superseded by later experiments. See our earlier editions.

${{\mathit \Lambda}}$ MASS   $1115.683 \pm0.006$ MeV

(${\mathit m}_{{{\mathit \Lambda}}}–{\mathit m}_{{{\overline{\mathit \Lambda}}}}$) $/$ ${\mathit m}_{{{\mathit \Lambda}}}$   $(-0.1 \pm1.1) \times 10^{-5}$  (S = 1.6)

${{\mathit \Lambda}}$ MEAN LIFE   $(2.617 \pm0.010) \times 10^{-10}$ s (S = 1.5)

(${\mathit \tau}_{{{\mathit \Lambda}}}–{\mathit \tau}_{{{\overline{\mathit \Lambda}}}}$) $/$ ${\mathit \tau}_{{{\mathit \Lambda}}}$   $0.0009 \pm0.0032$

${{\mathit \Lambda}}$ MAGNETIC MOMENT   $-0.613 \pm0.004$ $\mu _{\mathit N}$

${{\mathit \Lambda}}$ ELECTRIC DIPOLE MOMENT   $<1.5 \times 10^{-16}$ $\mathit e~$cm  CL=95.0%

${{\mathit \Lambda}}$ $\mathit CP$-violating decay-rate asymmetries

$\mathit A_{CP}({{\mathit p}}{{\mathit \mu}^{-}}{{\overline{\mathit \nu}}_{{{\mu}}}}$) in ${{\mathit \Lambda}}$ $\rightarrow$ ${{\mathit p}}{{\mathit \mu}^{-}}{{\overline{\mathit \nu}}_{{{\mu}}}}$, ${{\overline{\mathit \Lambda}}}$ $\rightarrow$ ${{\overline{\mathit p}}}{{\mathit \mu}^{+}}{{\mathit \nu}_{{{\mu}}}}$   $0.02 \pm0.14$

Limit on ${{\overline{\mathit \Lambda}}}{{\mathit \Lambda}}$ oscillations   $<3.8 \times 10^{-18}$ GeV  CL=90.0%

${{\mathit \Lambda}}$ DECAY PARAMETERS

$\alpha _{−}$ FOR ${{\mathit \Lambda}}$ $\rightarrow$ ${{\mathit p}}{{\mathit \pi}^{-}}$   $0.747 \pm0.009$  (S = 2.5)

$\alpha _{+}$ FOR ${{\overline{\mathit \Lambda}}}$ $\rightarrow$ ${{\overline{\mathit p}}}{{\mathit \pi}^{+}}$   $-0.757 \pm0.004$

${{\overline{\mathit \alpha}}_{{{0}}}}$ FOR ${{\overline{\mathit \Lambda}}}$ $\rightarrow$ ${{\overline{\mathit n}}}{{\mathit \pi}^{0}}$   $-0.692 \pm0.017$

$\alpha _{{{\mathit \gamma}}}$ FOR ${{\mathit \Lambda}}$ $\rightarrow$ ${{\mathit n}}{{\mathit \gamma}}$   $-0.16 \pm0.11$

$\phi $ ANGLE FOR ${{\mathit \Lambda}}$ $\rightarrow$ ${{\mathit p}}{{\mathit \pi}^{-}}$ (tan$\phi $ = $\beta $ $/$ $\gamma $)   $-6.5 \pm3.5$ $^\circ{}$

$\alpha _{0}$ $/$ $\alpha _{−}$ = $\alpha\mathrm {( {{\mathit \Lambda}} \rightarrow {{\mathit n}} {{\mathit \pi}^{0}})}$ $/$ $\alpha\mathrm {( {{\mathit \Lambda}} \rightarrow {{\mathit p}} {{\mathit \pi}^{-}})}$   $1.01 \pm0.07$

${{\overline{\mathit \alpha}}_{{{0}}}}$ $/$ ${{\mathit \alpha}_{{{+}}}}$ in ${{\overline{\mathit \Lambda}}}$ $\rightarrow$ ${{\overline{\mathit n}}}{{\mathit \pi}^{0}}$, ${{\overline{\mathit \Lambda}}}$ $\rightarrow$ ${{\overline{\mathit p}}}{{\mathit \pi}^{+}}$   $0.913 \pm0.030$

(${{\mathit \alpha}_{{{-}}}}$ + ${{\mathit \alpha}_{{{+}}}})/({{\mathit \alpha}_{{{-}}}}−{{\mathit \alpha}_{{{+}}}}$) in ${{\mathit \Lambda}}$ $\rightarrow$ ${{\mathit p}}{{\mathit \pi}^{-}}$, ${{\overline{\mathit \Lambda}}}$ $\rightarrow$ ${{\overline{\mathit p}}}{{\mathit \pi}^{+}}$   $-0.001 \pm0.004$

R = $\vert G_{E}/G_{M}\vert $ in ${{\mathit \Lambda}}$ $\rightarrow$ ${{\mathit p}}{{\mathit \pi}^{-}}$, ${{\overline{\mathit \Lambda}}}$ $\rightarrow$ ${{\overline{\mathit p}}}{{\mathit \pi}^{+}}$   $0.96 \pm0.14$

$\Delta \Phi $ = $\Phi _{E}$ $−$ $\Phi _{M}$ in ${{\mathit \Lambda}}$ $\rightarrow$ ${{\mathit p}}{{\mathit \pi}^{-}}$, ${{\overline{\mathit \Lambda}}}$ $\rightarrow$ ${{\overline{\mathit p}}}{{\mathit \pi}^{+}}$   $37 \pm13$ degrees

${\mathit g}_{{{\mathit A}}}$ $/$ ${\mathit g}_{{{\mathit V}}}$ FOR ${{\mathit \Lambda}}$ $\rightarrow$ ${{\mathit p}}{{\mathit e}^{-}}{{\overline{\mathit \nu}}_{{{e}}}}$   $-0.718 \pm0.015$

${{\mathit \Lambda}}$ DECAY MODES ▸  Expand all decays
Mode   Fraction ($\Gamma_i$ / $\Gamma$) Scale Factor/ Conf. Level P(MeV/c)   $\Gamma_{1}$ ${{\mathit p}}{{\mathit \pi}^{-}}$   $(64.1\pm{0.5})\%$ 101   $\Gamma_{2}$ ${{\mathit n}}{{\mathit \pi}^{0}}$   $(35.9\pm{0.5})\%$ 104   $\Gamma_{3}$ ${{\mathit n}}{{\mathit \gamma}}$   $(8.3\pm{0.7})\times 10^{-4}$ 162   $\Gamma_{4}$ ${{\mathit p}}{{\mathit \pi}^{-}}{{\mathit \gamma}}$  [1] $(8.5\pm{1.4})\times 10^{-4}$ 101   $\Gamma_{5}$ ${{\mathit p}}{{\mathit e}^{-}}{{\overline{\mathit \nu}}_{{{e}}}}$   $(8.34\pm{0.14})\times 10^{-4}$ 163   $\Gamma_{6}$ ${{\mathit p}}{{\mathit \mu}^{-}}{{\overline{\mathit \nu}}_{{{\mu}}}}$   $(1.51\pm{0.19})\times 10^{-4}$ 131   ▸ Lepton ($\mathit L$) and/or Baryon ($\mathit B$) number violating decay modes
FOOTNOTES

Constrained Fit information