  An intriguing feature of the Standard Model is that the representations of
the unbroken gauge symmetries are vector-like whereas those of the
spontaneously broken gauge symmetries are chiral. Here we provide a toy model
which shows that a natural explanation of this property could emerge in higher
dimensional field theories and discuss the difficulties that arise in the
attempt to construct a realistic theory. An interesting aspect of this type of
models is that the 4D low energy effective theory is not generically gauge
invariant. However, the non-invariant contributions to the observable
quantities are very small, of the order of the square of the ratio between the
light particle mass scale and the Kaluza-Klein mass scale. Remarkably, when we
take the unbroken limit both the chiral asymmetry and the non-invariant terms
disappear.
