Lepton mixing matrix
= Lepton mixing matrix
{title2=$U_{\alpha i}$}
= PMNS matrix
{c}
{synonym}
The matrix relating weak-interaction <neutrino> flavour fields to <mass> eigenfields, $\nu_{\alpha L}=\sum_iU_{\alpha i}\nu_{iL}$. In the standard three-active-neutrino description it is unitary. Oscillation probabilities involve products of entries and mass-squared differences; lepton-number-violating amplitudes can depend on additional Majorana phases through products such as $U_{ei}^2m_i$.