scholarly journals Cosmological evolution of fundamental constants: From theory to experiment

2015 ◽  
Vol 30 (22) ◽  
pp. 1540028 ◽  
Author(s):  
Xavier Calmet ◽  
Matthias Keller
Keyword(s):  
Time Evolution ◽  
Gauge Coupling ◽  
Current Status ◽  
Experimental Point ◽  
Fundamental Constants ◽  
Cosmological Time ◽  
Proton Mass ◽  
Grand Unified Theories ◽  
Unified Theories ◽  
Theoretical Side

In this paper, we discuss a possible cosmological time evolution of fundamental constants from the theoretical and experimental point of views. On the theoretical side, we explain that such a cosmological time evolution is actually something very natural which can be described by mechanisms similar to those used to explain cosmic inflation. We then discuss implications for grand unified theories, showing that the unification condition of the gauge coupling could evolve with cosmological time. Measurements of the electron-to-proton mass ratio can test grand unified theories using low energy data. Following the theoretical discussion, we review the current status of precision measurements of fundamental constants and their potential cosmological time dependence.

scholarly journals GRAND UNIFICATION WITHOUT HIGGS BOSONS

2012 ◽  
Vol 13 ◽  
pp. 20-27
Author(s):  
STEPHEN M. BARR ◽  
XAVIER CALMET
Keyword(s):  
Fixed Point ◽  
Weak Interactions ◽  
W Bosons ◽  
Gauge Coupling ◽  
Baryon Number ◽  
Higgs Bosons ◽  
Unified Theory ◽  
Grand Unified Theory ◽  
Grand Unified Theories ◽  
Unified Theories

We discuss how a model for the electroweak interactions without a Higgs could be embedded into a grand unified theory. The requirement of a non-trivial fixed point in the SU(2) sector of the weak interactions together with the requirement of the numerical unification of the gauge couplings leads to a prediction for the value of the SU(2) gauge coupling in the fixed point regime. The fixed point regime must be in the TeV region to solve the unitarity problem in the elastic scattering of W bosons. We find that the unification scale is at about 1014 GeV. Viable grand unified theories must thus conserve baryon number. We discuss how to build such a model without using Higgs bosons.

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.

scholarly journals Spectra of Distant Quasars and Verification of Possible Variation of Fundamental Constants over Cosmological Time-Scales

1994 ◽  
Vol 159 ◽  
pp. 361-362
Author(s):  
D.A. Varshalovich ◽  
A.Y. Potekhin
Keyword(s):  
Fine Structure ◽  
Time Scales ◽  
Spectroscopic Data ◽  
Structure Constant ◽  
Fine Structure Constant ◽  
Fundamental Constants ◽  
Mass Ratio ◽  
Cosmological Time ◽  
Proton Mass ◽  
Variation Rate

Constraints on possible variation rate of the fine-structure constant, , and the electron-proton mass ratio , over cosmological time scales are obtained from analyses of quasar spectroscopic data.

scholarly journals Perturbative unification of gauge couplings in supersymmetric E6 models

2016 ◽  
Vol 31 (22) ◽  
pp. 1650130 ◽  
Author(s):  
Gi-Chol Cho ◽  
Nobuhito Maru ◽  
Kaho Yotsutani
Keyword(s):  
Renormalization Group ◽  
Gauge Coupling ◽  
Gauge Fields ◽  
Grand Unified Theories ◽  
Renormalization Group Equations ◽  
Unified Theories ◽  
Perturbative Regime ◽  
Gut Scale ◽  
Gauge Couplings ◽  
Matter Fields

We study gauge coupling unification in supersymmetric (SUSY) E6 models where an additional U(1)[Formula: see text] gauge symmetry is broken near the TeV scale and a number of exotic matter fields from the 27 representations have O(TeV) mass. Solving the two-loop renormalization group equations (RGE) of gauge couplings and a kinetic mixing coupling between the U(1)[Formula: see text] and U(1)Y gauge fields, we find that the gauge couplings fall into the non-perturbative regime below the grand unified theories (GUT) scale. We examine threshold corrections on the running of gauge couplings from both light and heavy ([Formula: see text] GUT scale) particles and show constraints on the size of corrections to achieve the perturbative unification of gauge couplings.

scholarly journals Unification and supersymmetry

1983 ◽  
Vol 310 (1512) ◽  
pp. 279-292 ◽  
Keyword(s):  
Fine Structure ◽  
Weak Interactions ◽  
Structure Constant ◽  
Fine Structure Constant ◽  
Fundamental Constants ◽  
Quark Masses ◽  
Fundamental Particles ◽  
Grand Unified Theories ◽  
Mixing Parameter ◽  
Unified Theories

Current attempts to construct unified theories of fundamental particles and their interactions are described, with emphasis on their ability to understand the values of the fundamental constants. Examples include grand unified theories, which enable one to estimate the fine structure constant, the neutral weak interaction mixing parameter and certain quark masses. Finally, a review will be presented of the prospects offered by supersymmetry for understanding the scale of the weak interactions and for an eventual unification with gravity.

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.

Sign in / Sign up

Export Citation Format

Share Document