We study flavour-violating processes which involve heavy B- and D-mesons and
are mediated by Kaluza-Klein modes of gauge bosons in a previously suggested
model where three generations of the Standard Model fermions originate from a
single generation in six dimensions. We find the bound on the size R of the
extra spatial dimensions 1/R>3.3 TeV, which arises from the three-body decay
B_s to K mu e. Due to the still too low statistics this bound is much less
stringent than the constraint arising from K to mu e, 1/R>64 TeV, which was
found in a previous work (Frere et al., JHEP, 2003). Nevertheless, we argue
that a clear signature of the model would be an observation of K to mu e and
B_s to K mu e decays without observations of other flavour and lepton number
changing processes at the same precision level.Comment: 15 page