Missing momentum
= Missing momentum
{title2=$\mathbf p_{\rm miss}$}
The initial <momentum> minus the vector sum of reconstructed final visible <momenta>. At an <electron-positron collider> the full initial <four-momentum> is approximately known, unlike the hard partonic longitudinal momentum at a hadron collider. Nonzero missing <momentum> may indicate <neutrinos>, other invisible particles, or a detector loss; it is not alone proof of an invisible decay.