  A gauge-field theory for massive neutral particles is developed on the basis
of the real four-component Majorana equation. By use of its spin operator, a
purely imaginary representation of the SU(2) algebra can be defined, which
gives a covariant derivative that is real. Such a coupling to the gauge field
preserves the real nature of the Majorana equation even when including
interactions. As the associated isospin is four-dimensional, this procedure
introduces four intrinsic degrees of freedom to the Majorana field, which may
be related to four flavours. The main aim is to describe here the mathematical
possibility for coupling Majorana particles with a gauge field which resembles
that of the weak interaction. By adding a fourth member to the family, flavour
could become a dynamic trait of the neutral Majorana particles, and thus lead
to a dynamic understanding of mixing.
