= Integrated narrow vector resonance area
{title2=$\int\sigma_{ee}\,dE=6\pi^2B_{ee}^2\Gamma/M^2$}
For a narrow <vector meson> formed and observed in $e^+e^-$, neglecting external <masses> and slowly varying kinematic factors gives $\sigma_{ee}=3\pi\Gamma_{ee}^2/[M^2((E-M)^2+\Gamma^2/4)]$. Integrating the <Lorentz line shape> gives the displayed result. A normalized instrumental <convolution> preserves this full area, although it changes the observed peak and width. A constant uncorrected acceptance multiplies the area and must be divided out before extracting the <decay width>.
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