Connecting neutral current $B$ anomalies with the heaviness of the third family

It is possible, and for several reasons attractive, to explain a collection of recent anomalies involving b → sμμ processes with a Z gauge boson coupled only to the third family in the weak eigenbasis. From this premise, requiring cancellation of all gauge anomalies (including mixed and gravitational anomalies) fixes a unique charge assignment for the third family Standard Model fermions, which is simply proportional to hypercharge. After a brief discussion of some general features of anomaly cancellation in Z theories, we discuss the phenomenology of such a 'Third Family Hypercharge Model', which is subject to a trio of important constraints: (i) Bs − ¯ Bs mixing, (ii) lepton universality ofthe Z boson couplings, and (iii) constraints from direct searches for the Zboson at the LHC. Finally, in gauging third family hypercharge, this model forbids all Yukawa couplings (at the renormalisable level) save those of the third family, leading to a possible explanation of the heaviness of the third family.