scholarly journals Third-generation effects on fermion mass predictions in supersymmetric grand unified theories

1993 ◽  
Vol 48 (11) ◽  
pp. 5293-5304 ◽  
Author(s):  
Stephen G. Naculich
Keyword(s):  
Fermion Mass ◽  
Third Generation ◽  
Grand Unified Theories ◽  
Unified Theories

PredictiveAnsatzfor fermion mass matrices in supersymmetric grand unified theories

1992 ◽  
Vol 45 (11) ◽  
pp. 4192-4200 ◽  
Author(s):  
Savas Dimopoulos ◽  
Lawrence J. Hall ◽  
Stuart Raby
Keyword(s):  
Fermion Mass ◽  
Grand Unified Theories ◽  
Mass Matrices ◽  
Unified Theories

STRING-MOTIVATED GRAND UNIFIED THEORIES WITH HORIZONTAL GAUGE SYMMETRY

1994 ◽  
Vol 09 (30) ◽  
pp. 5369-5385 ◽  
Author(s):  
A.A. MASLIKOV ◽  
S.M. SERGEEV ◽  
G.G. VOLKOV
Keyword(s):  
Gauge Symmetry ◽  
Fermion Mass ◽  
Family Symmetry ◽  
Grand Unified Theories ◽  
Higher Dimensional ◽  
Unified Theories ◽  
Low Dimensional ◽  
Diagonal Subgroup ◽  
Higgs Fields ◽  
Level 2

In the framework of four-dimensional heterotic superstring with free fermions, we investigate the rank 8 grand unified string theories (GUST’s) which contain the SU(3) H gauge family symmetry. GUST’s of this type accommodate naturally the three fermion families presently observed and, moreover, can describe the fermion mass spectrum without high-dimensional representations of conventional unification groups. We explicitly construct GUST’s with gauge symmetry G= SU(5) × U(1) ×[ SU(3) × U(1) ]H ⊂ SO (16) in free complex fermion formulation. As the GUST’s originating from Kac-Moody algebras (KMA’s) contain only low-dimensional representations, it is usually difficult to break the gauge symmetry. We solve this problem by taking for the observable gauge symmetry the diagonal subgroup G sym of the rank 16 group G×G ⊂ SO(16) × SO(16) ⊂ E(8)×E(8). Such a construction effectively corresponds to a level 2 KMA, and therefore some higher-dimensional representations of the diagonal subgroup appear. This (due to G×G tensor Higgs fields) allows one to break GUST symmetry down to SU (3c)× U(1) em . In this approach the observed electromagnetic charge Q em can be viewed as a sum of two Q I and Q II charges of each G group. In this case, below the scale where G×G breaks down to G sym the spectrum does not contain particles with exotic fractional charges.

Water, Water, Here and There

2018 ◽  
Author(s):  
Steven E. Vigdor
Keyword(s):  
Quark Mass ◽  
Mass Difference ◽  
Baryon Number ◽  
Electroweak Phase Transition ◽  
Hydrogen Burning ◽  
Quark Masses ◽  
Grand Unified Theories ◽  
Down Quark ◽  
Unified Theories ◽  
The Stability

Chapter 4 deals with the stability of the proton, hence of hydrogen, and how to reconcile that stability with the baryon number nonconservation (or baryon conservation) needed to establish a matter–antimatter imbalance in the infant universe. Sakharov’s three conditions for establishing a matter–antimatter imbalance are presented. Grand unified theories and experimental searches for proton decay are described. The concept of spontaneous symmetry breaking is introduced in describing the electroweak phase transition in the infant universe. That transition is treated as the potential site for introducing the imbalance between quarks and antiquarks, via either baryogenesis or leptogenesis models. The up–down quark mass difference is presented as essential for providing the stability of hydrogen and of the deuteron, which serves as a crucial stepping stone in stellar hydrogen-burning reactions that generate the energy and elements needed for life. Constraints on quark masses from lattice QCD calculations and violations of chiral symmetry are discussed.

scholarly journals Accidental SO(10) axion from gauged flavour

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Luca Di Luzio
Keyword(s):  
Mass Window ◽  
High Quality ◽  
High Scale ◽  
Quality Problem ◽  
Axion Mass ◽  
Grand Unified Theories ◽  
Unified Theories ◽  
Canonical Dimension ◽  
General Perspective ◽  
Effective Operators

Abstract An accidental U(1) Peccei-Quinn (PQ) symmetry automatically arises in a class of SO(10) unified theories upon gauging the SU(3)f flavour group. The PQ symmetry is protected by the ℤ4 × ℤ3 center of SO(10) × SU(3)f up to effective operators of canonical dimension six. However, high-scale contributions to the axion potential posing a PQ quality problem arise only at d = 9. In the pre-inflationary PQ breaking scenario the axion mass window is predicted to be ma ∈ [7 × 10−8, 10−3] eV, where the lower end is bounded by the seesaw scale and the upper end by iso-curvature fluctuations. A high-quality axion, that is immune to the PQ quality problem, is obtained for ma ≳ 2 0.02 eV. We finally offer a general perspective on the PQ quality problem in grand unified theories.

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