${{\mathit \pi}^{+}}$ $\rightarrow$ ${{\mathit \mu}^{+}}{{\mathit \nu}_{{{\mu}}}}$  Decay Mode Summary INSPIRE   PDGID:
S008.1
Mode Fraction ($\Gamma_i$ / $\Gamma$) Scale Factor/
Conf. Level		 P(MeV/c)  
$\Gamma_{1}$ ${{\mathit \pi}^{+}}$ $\rightarrow$ ${{\mathit \mu}^{+}}{{\mathit \nu}_{{{\mu}}}}$ ($99.98770$ $\pm0.00004$) $ \times 10^{-2}$ 30
Note: Measurements of $\Gamma ({{\mathit e}^{+}}{{\mathit \nu}_{{{e}}}})/\Gamma ({{\mathit \mu}^{+}}{{\mathit \nu}_{{{\mu}}}}$) always include decays with ${{\mathit \gamma}}$'s, and measurements of $\Gamma ({{\mathit e}^{+}}{{\mathit \nu}_{{{e}}}}{{\mathit \gamma}}$) and $\Gamma ({{\mathit \mu}^{+}}{{\mathit \nu}_{{{\mu}}}}{{\mathit \gamma}}$) never include low-energy ${{\mathit \gamma}}$'s. Therefore, since no clean separation is possible, we consider the modes with ${{\mathit \gamma}}$'s to be subreactions of the modes without them, and let [$\Gamma ({{\mathit e}^{+}}{{\mathit \nu}_{{{e}}}}$) $+$ $\Gamma ({{\mathit \mu}^{+}}{{\mathit \nu}_{{{\mu}}}})]/\Gamma _{{\mathrm {total}}}$ = 100$\%$.
The following data is related to the above value:
 ▸ expand all datablocks
$\Gamma($ ${{\mathit \pi}^{+}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit \nu}_{{{e}}}}{{\mathit e}^{+}}{{\mathit e}^{-}})/\Gamma($ ${{\mathit \pi}^{+}}$ $\rightarrow$ ${{\mathit \mu}^{+}}{{\mathit \nu}_{{{\mu}}}})$
$\Gamma_{6}/\Gamma_{1}$
$\Gamma($ ${{\mathit \pi}^{+}}$ $\rightarrow$ ${{\mathit \mu}^{+}}{{\mathit \nu}_{{{\mu}}}}{{\mathit \nu}}{{\overline{\mathit \nu}}})/\Gamma($ ${{\mathit \pi}^{+}}$ $\rightarrow$ ${{\mathit \mu}^{+}}{{\mathit \nu}_{{{\mu}}}})$
$\Gamma_{7}/\Gamma_{1}$
$\lbrack{}\Gamma($ ${{\mathit \pi}^{+}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit \nu}_{{{e}}}})$+ $\Gamma($ ${{\mathit \pi}^{+}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit \nu}_{{{e}}}}{{\mathit \gamma}})\rbrack{}/[\Gamma($ ${{\mathit \pi}^{+}}$ $\rightarrow$ ${{\mathit \mu}^{+}}{{\mathit \nu}_{{{\mu}}}})$+ $\Gamma($ ${{\mathit \pi}^{+}}$ $\rightarrow$ ${{\mathit \mu}^{+}}{{\mathit \nu}_{{{\mu}}}}{{\mathit \gamma}})\rbrack{}$
($\Gamma_{3}$+ $\Gamma_{4})/(\Gamma_{1}$+ $\Gamma_{2}$)