On the difficulty of reconciling Dirac neutrinos with the PMNS matrix.

If neutrinos are Dirac particles, the universality of the Higgs coupling to the charged fermions of the Standard Model (SM) plus perturbative BSM corrections [1] strongly suggests an approximate congruence between the PMNS matrix and the CKM matrix, which is not observed. We present and discuss the modifications to the Dirac neutrino mass matrix required to remedy the discrepancy.

[1] T. Goldman and G. J. Stephenson Jr., Implications of Higgs Universality for BSM Physics: Quarks, in preparation; G. J. Stephenson Jr. and T. Goldman, Implications of Higgs Universality for BSM Physics: Leptons, in preparation.