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 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.

scholarly journals COMPLETE CLASSES OF GUTS WITH VANISHING ONE-LOOP BETA FUNCTIONS

1994 ◽  
Vol 09 (29) ◽  
pp. 5053-5075
Author(s):  
WOLFGANG LUCHA ◽  
FRANZ F. SCHÖBERL
Keyword(s):  
Gauge Coupling ◽  
Coupling Constants ◽  
Coupling Constant ◽  
Finiteness Conditions ◽  
Grand Unified Theories ◽  
Unified Theories ◽  
Dimensionless Coupling ◽  
The One ◽  
The Masses ◽  
Gauge Coupling Constant

By explicit solution of the one-loop finiteness conditions for all dimensionless coupling constants (i.e. the gauge coupling constant as well as Yukawa and quartic scalar-boson self-interaction coupling constants), two classes of grand unified theories characterized by renormalization-group beta functions which all vanish at least at the one-loop level are constructed and analyzed with respect to the (suspected) appearance of quadratic divergences, with the result that without exception in all of these models the masses of both vector and scalar bosons receive quadratically divergent one-loop contributions.

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 SPARTICLE MASS SPECTRUM IN GRAND UNIFIED THEORIES

2007 ◽  
Vol 22 (19) ◽  
pp. 3229-3259 ◽  
Author(s):  
B. ANANTHANARAYAN ◽  
P. N. PANDITA
Keyword(s):  
Mass Spectrum ◽  
Gauge Group ◽  
Gauge Groups ◽  
Grand Unified Theories ◽  
Renormalization Group Equations ◽  
The Standard Model ◽  
Unified Theories ◽  
The One ◽  
The Impact ◽  
Standard Model Gauge Group

We carry out a detailed analysis of sparticle mass spectrum in supersymmetric grand unified theories. We consider the spectroscopy of the squarks and sleptons in SU (5) and SO (10) grand unified theories, and show how the underlying supersymmetry breaking parameters of these theories can be determined from a measurement of different sparticle masses. This analysis is done analytically by integrating the one-loop renormalization group equations with appropriate boundary conditions implied by the underlying grand unified gauge group. We also consider the impact of nonuniversal gaugino masses on the sparticle spectrum, especially the neutralino and chargino masses which arise in supersymmetric grand unified theories with nonminimal gauge kinetic function. In particular, we study the interrelationships between the squark and slepton masses which arise in grand unified theories at the one-loop level, which can be used to distinguish between the different underlying gauge groups and their breaking pattern to the Standard Model gauge group. We also comment on the corrections that can affect these one-loop results.

scholarly journals HEAVY-NEUTRINO EFFECTS ON τ-LEPTON DECAYS

1994 ◽  
Vol 09 (38) ◽  
pp. 3595-3604 ◽  
Author(s):  
A. PILAFTSIS
Keyword(s):  
Standard Model ◽  
Heavy Neutrino ◽  
Lepton Flavor ◽  
Grand Unified Theories ◽  
The Standard Model ◽  
Unified Theories ◽  
Lepton Decays ◽  
The One

Minimal extensions of the standard model that are motivated by grand unified theories or superstring models with an E6 symmetry can naturally predict heavy neutrinos of Dirac or Majorana nature. Such heavy neutral leptons violate the decoupling theorem at the one-loop electroweak order and hence offer a unique chance for possible lepton-flavor decays of the τ-lepton, e.g. τ→eee or τ→μμμ, to be seen in LEP experiments. We analyze such decays in models with three and four generations.

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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