NUMERICAL REEXAMINATION OF SUPERSYMMETRIC AND NONSUPERSYMMETRIC SU(5)-LIKE GRAND UNIFIED MODELS

1989 ◽  
Vol 04 (10) ◽  
pp. 2531-2559 ◽  
Author(s):  
DARIUSZ K. GRECH
Keyword(s):  
Numerical Analysis ◽  
Numerical Computation ◽  
Numerical Results ◽  
Yukawa Couplings ◽  
Loop Level ◽  
Grand Unified Theories ◽  
Unified Theories ◽  
Supersymmetric Particles ◽  
The Difference

The significance of numerical analysis in both nonsupersymmetric and supersymmetric Grand Unified Theories is pointed out. The exact analytical and numerical analysis we present shows a need of larger corrections to the values of unifying parameters, i.e. sin 2 θw, Mx, τp than those often quoted in literature. When an unmodified nonsupersymmetric version of SU(5) is considered we show that numerical computation allows some of the models still to be experimentally admissible. The difference between analytical and numerical results for the supersymmetric SU(5) model is also stressed. In particular, corrections due to the mass threshold of additional generations or supersymmetric particles are calculated both analytically and numerically at the two-loop level. We found them far more important for the final values of sin 2 θw, Mx and τp than the effects of Higgs-Yukawa couplings between scalars and fermions.

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 Supersymmetric grand unified theories: Two-loop evolution of gauge and Yukawa couplings

1993 ◽  
Vol 47 (3) ◽  
pp. 1093-1113 ◽  
Author(s):  
V. Barger ◽  
M. S. Berger ◽  
P. Ohmann
Keyword(s):  
Yukawa Couplings ◽  
Grand Unified Theories ◽  
Unified Theories

Particle physicists’ candidates for dark matter

1986 ◽  
Vol 320 (1556) ◽  
pp. 475-485 ◽  
Keyword(s):  
Dark Matter ◽  
Big Bang ◽  
Strong Interactions ◽  
Grand Unified Theories ◽  
Unified Theories ◽  
Massive Neutrinos ◽  
Supersymmetric Particles ◽  
The Big Bang

A review is presented of the candidates for dark matter that arise in different particle theories. These include massive neutrinos and monopoles in grand unified theories, axions arising from attempts to explain cp conservation in the strong interactions, stable supersymmetric particles such as photinos, gravitinos or sneutrinos, and other possible stable relics from the Big Bang. Wherever possible, relations to laboratory information and possible experiments directly sensitive to the different dark-matter candidates are discussed.

scholarly journals A PARTICULAR CLASS OF GUTS WITH VANISHING ONE-LOOP BETA FUNCTIONS

1994 ◽  
Vol 09 (32) ◽  
pp. 5791-5800
Author(s):  
WOLFGANG LUCHA ◽  
FRANZ F. SCHÖBERL
Keyword(s):  
Renormalization Group ◽  
Explicit Solution ◽  
Coupling Constants ◽  
Scalar Boson ◽  
Finiteness Conditions ◽  
Yukawa Couplings ◽  
Grand Unified Theories ◽  
Unified Theories ◽  
The One

By explicit solution of the one-loop finiteness conditions for gauge and quartic scalar-boson self-interaction coupling constants, a particular class of grand unified theories with vanishing Yukawa couplings as well as vanishing one-loop renormalization-group beta functions is constructed.

Finite Unified Theories and the prediction of the Higgs mass

2007 ◽  
Vol 22 (31) ◽  
pp. 6057-6070 ◽  
Author(s):  
MYRIAM MONDRAGON ◽  
GEORGE ZOUPANOS
Keyword(s):  
Higgs Mass ◽  
Boson Mass ◽  
Drastic Reduction ◽  
Remarkable Property ◽  
Yukawa Couplings ◽  
Quark Masses ◽  
Grand Unified Theories ◽  
Unified Theories ◽  
Free Parameters ◽  
Soft Supersymmetry Breaking

Finite Unified Theories (FUTs) are N =1 supersymmetric Grand Unified Theories, which can be made all-loop finite, both in the gauge and Yukawa couplings and in the soft supersymmetry breaking sector. This remarkable property, based on the reduction of couplings at the quantum level, provides a drastic reduction in the number of free parameters, which in turn leads to predictions for the top and bottom quark masses, as well as predictions for the Higgs boson mass and the supersymmetric spectrum. Here we examine the predictions of two SU(5) FUTs, taking into account a number of theoretical and experimental constraints. We show how the phenomenological constraints can discriminate among the two models, and we give also the above mentioned predictions for the model that complies with all the constraints.

scholarly journals QUADRATIC DIVERGENCES IN GUTS WITH VANISHING ONE-LOOP BETA FUNCTIONS

1994 ◽  
Vol 09 (16) ◽  
pp. 2773-2782 ◽  
Author(s):  
WOLFGANG LUCHA ◽  
MICHAEL MOSER
Keyword(s):  
Vector Boson ◽  
Coupling Constants ◽  
Scalar Boson ◽  
Loop Level ◽  
Grand Unified Theories ◽  
Unified Theories ◽  
The One

All members of a recently proposed new set of (nonsupersymmetric) grand unified theories with one-loop-level vanishing beta functions for the gauge, Yukawa, and scalar-boson self-interaction coupling constants are shown to involve, already at the one-loop level, quadratically divergent contributions to both the vector-boson and scalar-boson masses.

scholarly journals Realistic GUT Yukawa couplings from a random clockwork model

2020 ◽  
Vol 80 (12) ◽  
Author(s):  
Gero von Gersdorff
Keyword(s):  
Yukawa Couplings ◽  
Grand Unified Theories ◽  
Unified Theories ◽  
Products Of Matrices

AbstractWe present realistic models of flavor in SU(5) and SO(10) grand unified theories (GUTs). The models are renormalizable and do not require any exotic representations in order to accommodate the necessary GUT breaking effects in the Yukawa couplings. They are based on a simple clockwork Lagrangian whose structure is enforced with just two (one) vectorlike U(1) symmetries in the case of SU(5) and SO(10) respectively. The inter-generational hierarchies arise spontaneously from products of matrices with order one random entries.

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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