either $\bar{\phi}$ or $\phi^\dagger$ of which there are 4 possibilities and generate the 4 different terms. The KK modes are always Dirac fermions, have masses of the order of the compactification scale and do the chirality flip by themselves. The KK modes mediate all higher order terms and their couplings to the zero modes and gauge fields are fixed, which fixes completely the Yukawa couplings

![Diagram that generates the effective Yukawa terms mediated by KK modes.[]{data-label="fig:kk"}](1.pdf)

Although the heavy KK modes mediate the effective Yukawa couplings, such diagrams are not very suppressed since the KK mode mass and the Wilson line VEVs $\braket{\phi,\bar{\phi}}$ are both the same order, namely the compactification scale. KK mode mediated higher order terms are possible but all involve insertions of $\phi\bar\phi$ contractions which do not change the mass matrix structure. This way the first order terms completely determine the structure of the mass matrices.

A model along these lines would have an effective $SU(3)$ gauged flavour symmetry where all fermions are triplets. Flavons in the triplet and antitriplet representation are generated automatically with aligned VEVs, resulting from the extra dimensional components of the underlying $SU(4)$ gauged flavour symmetry. No flavons need to be added by 