Neutral D-meson mixing ($D^0\leftrightarrow {\bar{D}}^0$)

Neutral D-meson mixing is the time evolution between the flavor states $D^0=c\bar{u}$ and ${\bar{D}}^0=\bar{c}u$. The states with definite propagation masses and decay widths are generally superpositions of these flavor states, so an initially tagged flavor need not remain unchanged before decay.

A measurement tags the production flavor and compares time-dependent rates into selected final states. Some final states can be reached both directly and after mixing, producing interference; a wrong-flavor candidate is therefore not automatically a pure mixing event. The effective two-state Hamiltonian includes both dispersive and absorptive parts. Separating mixing, direct suppressed decays and detector charge asymmetries is part of the inference.^[ref]