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${{\mathit N}}$ BARYONS
($\mathit S$ = 0, $\mathit I$ = 1/2)
${{\mathit p}}$, ${{\mathit N}^{+}}$ = ${\mathit {\mathit u}}$ ${\mathit {\mathit u}}$ ${\mathit {\mathit d}}$; ${{\mathit n}}$, ${{\mathit N}^{0}}$ = ${\mathit {\mathit u}}$ ${\mathit {\mathit d}}$ ${\mathit {\mathit d}}$

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

We have omitted some results that have been superseded by later experiments. See our earlier editions. Anyone interested in the neutron should look at these two review articles: D. Dubbers and M.G. Schmidt, ``The neutron and its role in cosmology and particle physics,'' Reviews of Modern Physics 83 1111 (2011); and F.E. Wietfeldt and G.L. Greene, ``The neutron lifetime,'' Reviews of Modern Physics 83 1173 (2011).

See related review:
Baryon Decay Parameters

${{\mathit n}}$ MASS (atomic mass units u)

$1.0086649160 \pm0.0000000005$ u

${{\mathit n}}$ MASS (MeV)

$939.5654205 \pm0.0000005$ MeV

${{\overline{\mathit n}}}$ MASS

$939.49 \pm0.05$ MeV

(${\mathit m}_{{{\mathit n}}}–{\mathit m}_{{{\overline{\mathit n}}}}$ )/ ${\mathit m}_{{{\mathit n}}}$

$(9 \pm5) \times 10^{-5}$

${\mathit m}_{{{\mathit n}}}–{\mathit m}_{{{\mathit p}}}$

$1.2933324 \pm0.0000005$ MeV

${{\mathit n}}$ MEAN LIFE

$878.4 \pm0.5$ s (S = 1.8)

${{\mathit n}}$ MAGNETIC MOMENT

$-1.9130427 \pm0.0000005$ $\mu _{\mathit N}$

${{\mathit n}}$ ELECTRIC DIPOLE MOMENT

$<1.8 \times 10^{-26}$ $\mathit e~$cm CL=90.0%

${{\mathit n}}$ MEAN-SQUARE CHARGE RADIUS

$-0.1155 \pm0.0017$ fm${}^{2}$

${{\mathit n}}$ MAGNETIC RADIUS

$0.864 {}^{+0.009}_{-0.008}$ fm

${{\mathit n}}$ ELECTRIC POLARIZABILITY ${{\mathit \alpha}_{{{n}}}}$

$0.00118 \pm0.00011$ fm${}^{3}$

${{\mathit n}}$ MAGNETIC POLARIZABILITY ${{\mathit \beta}_{{{n}}}}$

$(3.7 \pm1.2) \times 10^{-4}$ fm${}^{3}$

${{\mathit n}}$ CHARGE

$(-2 \pm8) \times 10^{-22}$ $\mathit e$

LIMIT ON ${{\mathit n}}{{\overline{\mathit n}}}$ OSCILLATIONS

Mean Time for ${{\mathit n}}{{\overline{\mathit n}}}$ Transition

$>8.6 \times 10^{7}$ s CL=90.0%

LIMIT ON ${{\mathit n}}{{\mathit n}^{\,'}}$ OSCILLATIONS

$> 448$ s CL=90.0%

${{\mathit n}}$ $\rightarrow$ ${{\mathit p}}{{\mathit e}^{-}}{{\overline{\mathit \nu}}_{{{e}}}}$ DECAY PARAMETERS

$\lambda {}\equiv{\mathit g}_{{{\mathit A}}}$ $/$ ${\mathit g}_{{{\mathit V}}}$

$-1.2753 \pm0.0013$ (S = 2.7)

${{\mathit e}^{-}}$ ASYMMETRY PARAMETER $\mathit A$

$-0.11958 \pm0.00021$ (S = 1.2)

${{\overline{\mathit \nu}}_{{{e}}}}$ ASYMMETRY PARAMETER $\mathit B$

$0.9807 \pm0.0030$

PROTON ASYMMETRY PARAMETER $\mathit C$

$-0.2377 \pm0.0026$

${{\mathit e}}-{{\overline{\mathit \nu}}_{{{e}}}}$ ANGULAR CORRELATION COEFFICIENT $\mathit a_{0}$

$-0.1044 \pm0.0007$

$\phi _{\mathit AV}$, PHASE OF ${\mathit g}_{{{\mathit A}}}$ RELATIVE TO ${\mathit g}_{{{\mathit V}}}$

$180.017 \pm0.026$ $^\circ{}$

TRIPLE CORRELATION COEFFICIENT $\mathit D$

$(-1.2 \pm2.0) \times 10^{-4}$

TRIPLE CORRELATION COEFFICIENT $\mathit R$

$0.004 \pm0.013$

FIERZ INTERFERENCE TERM $\mathit b$

$0.017 \pm0.020$

${{\boldsymbol n}}$ DECAY MODES ▸ Expand all decays

See the proton listings for many other neutron decay modes.

${{\mathit p}}{{\mathit e}^{-}}{{\overline{\mathit \nu}}_{{{e}}}}$

${{\mathit p}}{{\mathit e}^{-}}{{\overline{\mathit \nu}}_{{{e}}}}{{\mathit \gamma}}$

$(9.2\pm{0.7})\times 10^{-3}$

hydrogen-atom ${{\overline{\mathit \nu}}_{{{e}}}}$

$<2.7\times 10^{-3}$

▸	Charge conservation (${{\mathit Q}}$) violating mode

▸	Baryon number violating decay