Abstract
We show that a universal texture zero in the (1,1) position of all fermionic mass matrices, including heavy right-handed Majorana neutrinos driving a type-I see-saw mechanism, can lead to a viable spectrum of mass, mixing and CP violation for both quarks and leptons, including (but not limited to) three important postdictions: the Cabibbo angle, the charged lepton masses, and the leptonic ‘reactor’ angle. We model this texture zero with a non-Abelian discrete family symmetry that can easily be embedded in a grand unified framework, and discuss the details of the phenomenology after electroweak and family symmetry breaking. We provide an explicit numerical fit to the available data and obtain excellent agreement with the 18 observables in the charged fermion and neutrino sectors with just 9 free parameters. We further show that the vacua of our new scalar familon fields are readily aligned along desired directions in family space, and also demonstrate discrete gauge anomaly freedom at the relevant scale of our effective theory.
Highlights
The structure of the underlying family symmetry we choose to study is motivated by the observation that neutrino mixing is quite close to tribimaximal mixing, in which limit the neutrino mass eigenstates are given by
We show that a universal texture zero in the (1,1) position of all fermionic mass matrices, including heavy right-handed Majorana neutrinos driving a type-I see-saw mechanism, can lead to a viable spectrum of mass, mixing and CP violation for both quarks and leptons, including three important postdictions: the Cabibbo angle, the charged lepton masses, and the leptonic ‘reactor’ angle
The light neutrino mass and mixing structure is quite different because the right-handed neutrinos can have large Majorana masses and, for the case this is dominated by the third generation mass, sequential dominance takes place [25,26,27,28,29] and the see-saw mechanism suppresses the large third generation Dirac mass matrix contribution, allowing for the light neutrino mass eigenstates to be approximately given by eq (1.1)
Summary
An important issue in the determination of fermion mass predictions is the scale at which the prediction applies. In this paper we assume the scale is large and further that supersymmetry (SUSY) prevents radiative corrections from driving an unacceptably large electroweak breaking scale (the hierarchy problem) and allows for precise gauge coupling unification. In this case the radiative corrections due to gauge interactions are well understood for the quarks. In addition there may be large SUSY threshold corrections [34] Taking these corrections into account, quark and charged lepton masses and mixings are consistent with a symmetric mass matrix structure of the form. 1 3 md at the unification scale, which is in good agreement with the measured values after including radiative corrections [34]
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