SU(2)_L deconstruction and flavour (non)-universality

We study two-site deconstructions of the SU(2)_L gauge group factor of the SM. Models based on this approach can explain the hierarchies of the quark masses and CKM mixing between the third and light families if these fields are localised on different sites, leading to a global accidental U(2)_q× U(3)_u× U(3)_d flavour symmetry. This symmetry prevents dangerously large effects in flavour observables, making a TeV scale realisation possible. Given the structure of PMNS matrix in the neutrino sector, we explore different possibilities for the arrangement of the leptons on the two sites, and consider different models with U(2)_ℓ or U(3)_ℓ flavour symmetries. The phenomenology of the models is mostly governed by a massive vector triplet of SU(2)_L. We study the interesting interplay between LHC searches and precision observables. In particular, one of the models can give a sizeable lepton flavour universal effect in the Wilson coefficient C_9 while naturally suppressing contributions to C_10, as suggested by current b→ sℓ^+ℓ^- data, predicting simultaneously a mild positive shift in the W boson mass.