Total decay width
= Total decay width
{title2=$\Gamma_{\mathrm{tot}}=\sum_i\Gamma_i$}
The sum of the <partial decay widths> over mutually exclusive final channels. It determines the unstable state's <mean lifetime> through $\tau=\hbar/\Gamma_{\mathrm{tot}}$. A new open channel increases the total width even when an existing channel's partial width remains unchanged.