On the neutrino number and isotropy of the universe in grand unified theories

1980 ◽  
Vol 28 (6) ◽  
pp. 205-208 ◽  
Author(s):  
D. V. Nanopoulos ◽  
D. Sutherland ◽  
A. Yildiz
Keyword(s):  
Grand Unified Theories ◽  
Unified Theories ◽  
The Universe

scholarly journals HIDDEN DIRAC MONOPOLES

2008 ◽  
Vol 23 (24) ◽  
pp. 4023-4037 ◽  
Author(s):  
VICENTE VENTO
Keyword(s):  
Electric Charge ◽  
Particle Physics ◽  
Magnetic Pole ◽  
Experimental Search ◽  
Grand Unified Theories ◽  
Unified Theories ◽  
Discrete Nature ◽  
Magnetic Poles ◽  
The Universe

Dirac showed that the existence of one magnetic pole in the universe could offer an explanation of the discrete nature of the electric charge. Magnetic poles appear naturally in most grand unified theories. Their discovery would be of greatest importance for particle physics and cosmology. The intense experimental search carried thus far has not met with success. I propose a universe with magnetic poles which are not observed free because they hide in deeply bound monopole–antimonopole states named monopolium. I discuss the realization of this proposal and its consistency with known cosmological features. I furthermore analyze its implications and the experimental signatures that confirm the scenario.

scholarly journals Beyond the Standard Model at LEP

1991 ◽  
Vol 336 (1642) ◽  
pp. 247-259 ◽  
Keyword(s):  
Dark Matter ◽  
Standard Model ◽  
Beyond The Standard Model ◽  
Grand Unified Theories ◽  
The Standard Model ◽  
Unified Theories ◽  
Massive Neutrinos ◽  
Supersymmetric Particles ◽  
The Universe

LEP data constrain severely many proposed extensions of the Standard Model. These include: massive neutrinos, which are now largely excluded as candidates for the dark matter of the Universe; supersymmetric particles, the lightest of which would still constitute detectable dark matter; technicolour, of which many favoured versions are now excluded by precision electroweak measurements; and grand unified theories, of which LEP data favour supersymmetric versions.

scholarly journals Observational Tests of Baryon Symmetric Cosmology

1983 ◽  
Vol 104 ◽  
pp. 437-445
Author(s):  
F. W. Stecker
Keyword(s):  
Big Bang ◽  
Blackbody Radiation ◽  
Baryon Asymmetry ◽  
Observational Constraints ◽  
Baryonic Matter ◽  
Grand Unified Theories ◽  
Unified Theories ◽  
Important Amount ◽  
Big Bang Model ◽  
The Universe

To the gods alone belongs it never to be old or die. But all things else melt with all-powerful time….SophoclesWith the advent of grand unified theories (GUTs) has come the concept (among others) that baryons (protons, etc.) can decay by changing into leptons (“Diamonds are not forever.”) and vice versa, baryonic matter can be created from the thermal blackbody radiation in the early universe (provided, of course, that the hot big-bang model is basically correct). Using this concept, models have been suggested to generate a universal baryon asymmetry, with the consequence that no important amount of antimatter would be left in the universe at the present time (see, e.g. Langacker 1981 and references therein). These models have been motivated by observational constraints on antimatter, at least in our little corner of the universe (Steigman 1976). However, some of these constraints have been shown to be overrestrlctive (Stecker 1978, Allen 1981) and an alternative model, also based on GUTs, has been suggested which maintains matter-antimatter (I.e., baryon) symmetry on a universal scale, but results in separate “fossil domains” of clusters of matter galaxies and clusters of antimatter galaxies.

Baryon asymmetry of the universe in grand unified theories

1979 ◽  
Vol 87 (1-2) ◽  
pp. 114-116 ◽  
Author(s):  
A.Yu. Ignatiev ◽  
V.A. Kuzmin ◽  
M.E. Shaposhnikov
Keyword(s):  
Baryon Asymmetry ◽  
Grand Unified Theories ◽  
Unified Theories ◽  
The Universe

From the standard model to grand unification

1982 ◽  
Vol 304 (1482) ◽  
pp. 69-86 ◽  
Keyword(s):  
Structure Constant ◽  
Fine Structure Constant ◽  
Grand Unification ◽  
Quark Masses ◽  
Grand Unified Theories ◽  
The Standard Model ◽  
Unified Theories ◽  
Order Of Magnitude ◽  
Near Future ◽  
The Universe

This paper reviews the limitations o f the standard SU (3) x SU (2) x U (l) model and develops the philosophy of grand unification. Some simple grand unified theories are presented, and calculations made of the order of magnitude of the fine-structure constant a, as well as of sin 2 0 W and some quark masses. Predictions for nucleon decay and neutrino masses are then discussed; they may be observable in the near future. It is suggested that grand unified theories complex enough for the understanding of the baryon asymmetry of the Universe may also predict a neutron electric dipole moment large enough to be measured. Finally, some inadequacies of GUTs are mentioned.

The Very Early Universe

1988 ◽  
Vol 20 (1) ◽  
pp. 656-658
Author(s):  
K. Sato
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Early Universe ◽  
Early Stage ◽  
Topological Defects ◽  
Evolution Of The Universe ◽  
Grand Unified Theories ◽  
Unified Theories ◽  
The Universe

In recent years, the research on the very early universe has shown quite remarkable developments. As is well known, this development was brought about by the introduction of the Grand Unified Theories (GUTs) into cosmology. These theories have not only enabled us to trace the evolution of the Universe back to the very early stage at temperatures of 1016 GeV or higher, but also introduced various new aspects into cosmology, such as baryogenesis, phase transitions and topological defects (monopoles, etc.). In particular, inflation, which grew out of the study of GUT phase transition, is the most important and fascinating outcome.

Frontiers of Physics

2017 ◽  
Author(s):  
Nicholas Manton ◽  
Nicholas Mee
Keyword(s):  
Standard Model ◽  
Beyond The Standard Model ◽  
Epr Paradox ◽  
Grand Unified Theories ◽  
Alternative Description ◽  
The Standard Model ◽  
Unified Theories ◽  
Modern Physics ◽  
The Universe

Despite the overwhelming successes of modern physics, there are questions that remain to be answered and these are considered in the final chapter. The interpretation of quantum mechanics is discussed, including the EPR paradox, the Aspect experiments and quantum entanglement. Next, the question of whether particles are really point-like and the possibility of an alternative description in terms of solitons is considered. The Skyrmion and the Standard Model sphaleron are described. Unexplained features of the universe, such as the matter–antimatter asymmetry, the existence of dark matter and the even more mysterious dark energy, are discussed. There is also a critique of the loose ends of the Standard Model and the need for a quantum theory of gravity. The chapter concludes with a look beyond the Standard Model at the arguments and evidence in favour of Grand Unified Theories and ultimately string theory.

Grand unified theories and the lepton number of the Universe

1981 ◽  
Vol 24 (8) ◽  
pp. 2090-2099 ◽  
Author(s):  
Jeffrey A. Harvey ◽  
Edward W. Kolb
Keyword(s):  
Lepton Number ◽  
Grand Unified Theories ◽  
Unified Theories ◽  
The Universe

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.

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