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Title: Fermion Masses and Mixings in SO(10) GUTs

Abstract

I will present a simple, economic and predictive model of Yukawa structures in the context of a renormalizable SO(10) grandunification. The righthanded neutrino mass is generated radiatively. The fermions have Yukawa couplings with one 10 and one 120 dimensional Higgses. The model predicts in the approxiamate two generation scenario degenerate neutrinos, small quark mixing and b - {tau} Yukawa unification.

Authors:
 [1]
  1. J.Stefan Institute, 1001 Ljubljana (Slovenia)
Publication Date:
OSTI Identifier:
20729184
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 805; Journal Issue: 1; Conference: PASCOS 2005: 11. international symposium on particles, strings, and cosmology, Gyeongju (Korea, Republic of), 30 May - 4 Jun 2005; Other Information: DOI: 10.1063/1.2149722; (c) 2005 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; GRAND UNIFIED THEORY; HIGGS BOSONS; HIGGS MODEL; MIXING; NEUTRINOS; QUARKS; RENORMALIZATION; REST MASS; SO-10 GROUPS

Citation Formats

Bajc, Borut. Fermion Masses and Mixings in SO(10) GUTs. United States: N. p., 2005. Web. doi:10.1063/1.2149722.
Bajc, Borut. Fermion Masses and Mixings in SO(10) GUTs. United States. doi:10.1063/1.2149722.
Bajc, Borut. Fri . "Fermion Masses and Mixings in SO(10) GUTs". United States. doi:10.1063/1.2149722.
@article{osti_20729184,
title = {Fermion Masses and Mixings in SO(10) GUTs},
author = {Bajc, Borut},
abstractNote = {I will present a simple, economic and predictive model of Yukawa structures in the context of a renormalizable SO(10) grandunification. The righthanded neutrino mass is generated radiatively. The fermions have Yukawa couplings with one 10 and one 120 dimensional Higgses. The model predicts in the approxiamate two generation scenario degenerate neutrinos, small quark mixing and b - {tau} Yukawa unification.},
doi = {10.1063/1.2149722},
journal = {AIP Conference Proceedings},
number = 1,
volume = 805,
place = {United States},
year = {Fri Dec 02 00:00:00 EST 2005},
month = {Fri Dec 02 00:00:00 EST 2005}
}
  • Fermion masses and mixing angles are studied in an SUSY SO(10){times}{Delta}(48){times}U(1) model with small tan{beta}. Thirteen parameters involving masses and mixing angles in the quark and charged lepton sector are successfully predicted by a single Yukawa coupling and three ratios of VEV{close_quote}s caused by necessary symmetry breaking. Ten relations among the low energy parameters have been found with four of them free from renormalization modifications. They could be tested directly by low energy experiments. {copyright} {ital 1996 The American Physical Society.}
  • We present a detailed study of the quark and lepton mass spectra in a SO(10) framework with one 10{sub H} and one 126{sub H} Higgs representations in the Yukawa sector. We consider in full generality the interplay between type I and type II seesaw for neutrino masses. We first perform a {chi}{sup 2} fit of fermion masses independent on the structure of the GUT Higgs potential and determine the regions of the parameter space that are preferred by the fermion mass sum rules. We then apply our study to the case of the minimal renormalizable SUSY SO(10) GUT with onemore » 10{sub H}, one 126{sub H}, one 126{sub H}, and one 210{sub H} Higgs representations. By requiring that proton decay bounds are fulfilled we identify a very limited area in the parameter space where all fermion data are consistently reproduced. We find that in all cases gauge coupling unification in the supersymmetric scenario turns out to be severely affected by the presence of lighter than GUT (albeit B-L conserving) states. We then conclusively show that the minimal supersymmetric SO(10) scenario here considered is not consistent with data. The fit of neutrino masses with type I and type II seesaws within a renormalizable SO(10) framework strongly suggests a non-SUSY scenario for gauge unification.« less
  • The {mu}-{tau} symmetry imposed on the neutrino mass matrix in the flavor basis is known to be quite predictive. We integrate this very specific neutrino symmetry into a more general framework based on the supersymmetric SO(10) grand unified theory. As in several other models, the fermion mass spectrum is determined by Hermitian mass matrices resulting from the renormalizable Yukawa couplings of the 16-plet of fermions with the Higgs fields transforming as 10, 126, and 120 representations of the SO(10) group. The {mu}-{tau} symmetry is spontaneously broken through the 120-plet. Consequences of this scheme are considered for fermion masses using bothmore » a type-I and a type-II seesaw mechanism. This scenario is shown to lead to a generalized CP invariance of the mass matrices and vanishing CP violating phases if the Yukawa couplings are invariant under the {mu}-{tau} symmetry. Small explicit breaking of the {mu}-{tau} symmetry is then shown to provide a very good understanding of all of the fermion masses and mixing. Detailed fits to the fermion spectrum are presented in several scenarios. One obtains a very good fit to all observables in the context of the type-I seesaw mechanism, but the type-II seesaw model also provides a good description except for the overall scale of the neutrino masses. Three major predictions on the leptonic mixing parameters in the type-I seesaw case are (i) the atmospheric mixing angle {theta}{sub 23}{sup l} close to maximal, (ii) {theta}{sub 13}{sup l} close to the present upper bound, and (iii) a negative but very small Dirac CP violating phase in the neutrino oscillations.« less
  • A supersymmetric SO(10)xA{sub 4} grand unified theory model is constructed for fermion masses and mixing by introducing a minimal set of low dimensional Higgs representations needed to break the gauge symmetry down to SU(3){sub c}xU(1){sub em}. The hierarchy of fermion masses can be understood in the framework of A{sub 4} symmetry. From the A{sub 4}-invariant superpotential, the 'double lopsided' mass matrices for the charged leptons and the down quarks are obtained. It is shown that this structure simultaneously leads to bi-large neutrino mixings and small Cabibbo-Kobayashi-Maskawa mixing angles. An excellent fit to the masses and mixings of the quarks andmore » leptons as well as to the CP violation parameter is obtained. Moreover, the model predicts the neutrino mixing angle sin{theta}{sub 13}{approx_equal}0.15.« less
  • We consider a minimal formulation of SO(10) grand unified theory wherein all the fermion masses arise from Yukawa couplings involving one 126 and one 10 of Higgs multiplets. It has recently been recognized that such theories can explain, via the type-II seesaw mechanism, the large {nu}{sub {mu}}-{nu}{sub {tau}} mixing as a consequence of b-{tau} unification at the grand unified theory scale. In this picture, however, the Cabibbo-Kobayashi-Maskawa quark-mixing matrix phase {delta} lies preferentially in the second quadrant, in contradiction with experimental measurements. We revisit this minimal model and show that the conventional type-I seesaw mechanism generates phenomenologically viable neutrino massesmore » and mixings, while being consistent with Cabibbo-Kobayashi-Maskawa quark-mixing matrix CP violation. We also present improved fits in the type-II seesaw scenario and suggest fully consistent fits in a mixed scenario.« less