Large neutrino mixing angleθ13MNSand quark-lepton mass ratios in unified flavor models

Abstract

We analyze how a large value of the leptonic mixing angle θ MNS 13 can be generated via charged lepton corrections in unified flavor models, using novel combinations of Clebsch-Gordan factors for obtaining viable quark-lepton mass ratios for the first two families. We discuss how these Clebsch-Gordan factors affect the relations between down-type quark mixing and charged lepton mixing in SU(5) grand unified theories and Pati-Salam unified models and calculate the resulting possible predictions for θ MNS 13 for models with θ ν 13 , θ e 13 ≪ θ e 12 . While symmetric mass matrices with zero (1,1)-elements always lead to comparatively small θ MNS 13 ≈ 2.8 • , we find novel combinations of Clebsch-Gordan factors for nonsymmetric mass matrices which can yield θ MNS 13 ≈ 5.1 • , 6.1 • , 7.6 • or 10.1 • , as favored by the current experimental hints for large θ MNS 13 . We discuss applications to classes of models with underlying tribimaximal or bimaximal mixing in the neutrino sector.1

Towards predictive flavour models in SUSY SU(5) GUTs with doublet-triplet splitting

“…Due to this, new Clebsch-Gordan (CG) factors appear as Yukawa coupling ratios, with interesting associated implications for the masses and mixing of the fermions, cf. [12,13] and [14][15][16][17]. The main goal of this paper is to show how GUT flavour models featuring these promising quark-lepton mass relations can be combined with a version of the DMPM for solving the DTS problem.…”

“…In figure 2 and table 1, we briefly review the topology of the diagram and field combinations that lead to the CG factors (Y e ) ji /(Y d ) ij = − 1 2 , − 3 2 and 6 for SU(5) GUTs, which have been shown to be useful for flavour model building [11][12][13]. To generate these relations we use a GUT breaking Higgs field H 24 in the adjoint representation of SU(5), and Higgs fieldsH 5 andH 45 in the5 and 45 representation.…”

Linking leptonic CP violation to quark unitarity triangle

“…The remarkable difference of the mixing angles between the CKM matrix and the PMNS matrix is due to the flavor structure in the right-handed neutrino mass matrix M R . Now, one can take [32,33] …”

“…Especially, θ e 12 ≃ θ C with θ C being the Cabibbo angle, comes from the GUT relations between the down-type Yukawa matrix Y d and the charged lepton Yukawa matrix Y e , and then one obtains the successful relation θ 13 ≃ θ C / √ 2 from eq. (2.31) [30][31][32][33]. In order to link the lepton mass matrices to the quark mass matrices, we consider the SO(10) GUT, which is broken down to the SM gauge group through the Pati-Salam symmetry [36,37].…”

“…By using some GUTs, the reactor angle of neutrinos is related to the quark mixing angle [32][33][34][35]. Actually, one of the authors has examined the mixing angles of both quarks and the leptons in the SO(10) GUT including the Pati-Salam symmetry [36,37].…”