Gauge Hierarchies in Unified Theories

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.

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Grand unified theories in renormalisable, classically scale invariant gravity

Journal of High Energy Physics ◽

10.1007/jhep10(2019)012 ◽

2019 ◽

Vol 2019 (10) ◽

Author(s):

Martin B. Einhorn ◽

D.R. Timothy Jones

Keyword(s):

Scale Invariant ◽

Grand Unified Theories ◽

Unified Theories

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Gravitational corrections to fermion masses in grand unified theories

Physical Review D ◽

10.1103/physrevd.84.037701 ◽

2011 ◽

Vol 84 (3) ◽

Cited By ~ 6

Author(s):

Xavier Calmet ◽

Ting-Cheng Yang

Keyword(s):

Grand Unified Theories ◽

Fermion Masses ◽

Unified Theories

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Accidental SO(10) axion from gauged flavour

Journal of High Energy Physics ◽

10.1007/jhep11(2020)074 ◽

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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Octonions and unified theories with orthogonal groups

Lettere al Nuovo Cimento ◽

10.1007/bf02785047 ◽

1977 ◽

Vol 18 (14) ◽

pp. 441-446 ◽

Cited By ~ 4

Author(s):

F. Buccella ◽

M. Falcioni ◽

A. Pugliese

Keyword(s):

Orthogonal Groups ◽

Unified Theories

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Précis ofUnified theories of cognition

Behavioral and Brain Sciences ◽

10.1017/s0140525x00069478 ◽

1992 ◽

Vol 15 (3) ◽

pp. 425-437 ◽

Cited By ~ 43

Author(s):

Allen Newell

Keyword(s):

Cognitive Science ◽

Full Range ◽

Cognitive Architecture ◽

Convincing Evidence ◽

Syllogistic Reasoning ◽

Human Cognition ◽

Unified Theory ◽

Theoretical Concepts ◽

Wide Range ◽

Unified Theories

AbstractThe book presents the case that cognitive science should turn its attention to developing theories of human cognition that cover the full range of human perceptual, cognitive, and action phenomena. Cognitive science has now produced a massive number of high-quality regularities with many microtheories that reveal important mechanisms. The need for integration is pressing and will continue to increase. Equally important, cognitive science now has the theoretical concepts and tools to support serious attempts at unified theories. The argument is made entirely by presenting an exemplar unified theory of cognition both to show what a real unified theory would be like and to provide convincing evidence that such theories are feasible. The exemplar is SOAR, a cognitive architecture, which is realized as a software system. After a detailed discussion of the architecture and its properties, with its relation to the constraints on cognition in the real world and to existing ideas in cognitive science, SOAR is used as theory for a wide range of cognitive phenomena: immediate responses (stimulus-response compatibility and the Sternberg phenomena); discrete motor skills (transcription typing); memory and learning (episodic memory and the acquisition of skill through practice); problem solving (cryptarithmetic puzzles and syllogistic reasoning); language (sentence verification and taking instructions); and development (transitions in the balance beam task). The treatments vary in depth and adequacy, but they clearly reveal a single, highly specific, operational theory that works over the entire range of human cognition, SOAR is presented as an exemplar unified theory, not as the sole candidate. Cognitive science is not ready yet for a single theory – there must be multiple attempts. But cognitive science must begin to work toward such unified theories.

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