Inverse neutrino mass hierarchy in a flavour GUT model

Abstract

We construct a supersymmetric SU(5) x A_4 flavour GUT model in which an inverse neutrino mass hierarchy is realised without fine-tuning of parameters. The model shares some properties with the normal hierarchy model which we presented in arXiv:1305.6612 - in particular the relation theta_13^PMNS = theta_C / sqrt(2). Besides these shared features, there are also important differences, mainly due to the different neutrino sector. These differences not only change the predictions in the lepton sector, but also in the quark sector, and will allow to discriminate between the two models using the results of present and future experiments. From a Markov Chain Monte Carlo fit we find that the inverse hierarchy model is in excellent agreement with the present experimental data.Comment: 18 pages, version published in NP

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.…”

“…[15][16][17]. By introducing pairs of heavy messengers in the SU(5) representations R andR, the renormalizable couplings associated with the effective operators are specified and a unique contraction of SU (5) indices of the effective operator is obtained simply by integrating out the messenger fields.…”

Linking leptonic CP violation to quark unitarity triangle

“…Similar discussions lead to sum rules for the mixing angles and the CP violating phase in the lepton sector [30,31]. For the lepton mixing [40,41], we write a general unitarity matrix U ′ PMNS including the Majorana phases ϕ 1 , ϕ 2 and the Dirac phase δ PMNS as follows:…”

“…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].…”

“…In this paper, we extend this approach of the CP violating phase to the lepton sector [30,31] and discuss the link of the CP violating phase between the quark and lepton sectors.…”