Lepton mixing predictions including Majorana phases from Δ(6n²) flavour symmetry and generalised CP

Generalised CP transformations are the only known framework which allows to predict Majorana phases in a flavour model purely from symmetry. For the first time generalised CP transformations are investigated for an infinite series of finite groups, Δ(6n²)=(Z_n×Z_n)⋊S₃. In direct models the mixing angles and Dirac CP phase are solely predicted from symmetry. The Δ(6n²) flavour symmetry provides many examples of viable predictions for mixing angles. For all groups the mixing matrix has a trimaximal middle column and the Dirac CP phase is 0 or π. The Majorana phases are predicted from residual flavour and CP symmetries where α₂₁ can take several discrete values for each n and the Majorana phase α₃₁ is a multiple of π. We discuss constraints on the groups and CP transformations from measurements of the neutrino mixing angles and from neutrinoless double-beta decay and find that predictions for mixing angles and all phases are accessible to experiments in the near future