  A composite model of the standard model particles was recently derived using
the Dirac Lagrangian on a spacetime where time does not advance along the
worldlines of fundamental dust particles, called an 'internal spacetime'. The
aim of internal spacetime geometry is to model certain quantum phenomena using
(classical) degenerate spacetime metrics. For example, on an internal
spacetime, tangent spaces have variable dimension, and spin wavefunction
collapse is modeled by the projection from one tangent space to another. In
this article we show that the combinatorial structure of the internal Dirac
Lagrangian yields precisely the standard model trivalent vertices, together
with two additional new (longitudinal) Z vertices that generate the four-valent
boson vertices. In particular, we are able to derive electroweak parity
violation for both leptons and quarks. We also obtain new restrictions on the
possible spin states that can occur in certain interactions. Finally, we
determine the trivalent vertices of the new massive spin-2 boson predicted by
the model.
