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.

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.

scholarly journals Fundamental physics and the fine-structure constant

2017 ◽  
Vol 5 (2) ◽  
pp. 46 ◽  
Author(s):  
Michael Sherbon
Keyword(s):  
Fine Structure ◽  
Structure Constant ◽  
Fine Structure Constant ◽  
Electron Mass ◽  
Fundamental Constants ◽  
Mass Ratio ◽  
Fundamental Physics ◽  
Weak Force ◽  
Strong Force ◽  
Symmetry Principles

From the exponential function of Euler’s equation to the geometry of a fundamental form, a calculation of the fine-structure constant and its relationship to the proton-electron mass ratio is given. Equations are found for the fundamental constants of the four forces of nature: electromagnetism, the weak force, the strong force and the force of gravitation. Symmetry principles are then associated with traditional physical measures.

scholarly journals Theory of the Anomalous Magnetic Moment of the Electron

Atoms ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 28 ◽  
Author(s):  
Tatsumi Aoyama ◽  
Toichiro Kinoshita ◽  
Makiko Nio
Keyword(s):  
Fine Structure ◽  
Magnetic Moment ◽  
Anomalous Magnetic Moment ◽  
Quantum Electrodynamics ◽  
Penning Trap ◽  
Weak Interactions ◽  
Perturbation Expansion ◽  
Structure Constant ◽  
Fine Structure Constant ◽  
Best Value

The anomalous magnetic moment of the electron a e measured in a Penning trap occupies a unique position among high precision measurements of physical constants in the sense that it can be compared directly with the theoretical calculation based on the renormalized quantum electrodynamics (QED) to high orders of perturbation expansion in the fine structure constant α , with an effective parameter α / π . Both numerical and analytic evaluations of a e up to ( α / π ) 4 are firmly established. The coefficient of ( α / π ) 5 has been obtained recently by an extensive numerical integration. The contributions of hadronic and weak interactions have also been estimated. The sum of all these terms leads to a e ( theory ) = 1 159 652 181.606 ( 11 ) ( 12 ) ( 229 ) × 10 − 12 , where the first two uncertainties are from the tenth-order QED term and the hadronic term, respectively. The third and largest uncertainty comes from the current best value of the fine-structure constant derived from the cesium recoil measurement: α − 1 ( Cs ) = 137.035 999 046 ( 27 ) . The discrepancy between a e ( theory ) and a e ( ( experiment ) ) is 2.4 σ . Assuming that the standard model is valid so that a e (theory) = a e (experiment) holds, we obtain α − 1 ( a e ) = 137.035 999 1496 ( 13 ) ( 14 ) ( 330 ) , which is nearly as accurate as α − 1 ( Cs ) . The uncertainties are from the tenth-order QED term, hadronic term, and the best measurement of a e , in this order.

scholarly journals VLT and E-ELT spectrographs & fundamental-constants

2009 ◽  
Vol 5 (H15) ◽  
pp. 326-326
Author(s):  
Paolo Molaro
Keyword(s):  
Fine Structure ◽  
Equivalence Principle ◽  
Structure Constant ◽  
Rate Of Change ◽  
Fine Structure Constant ◽  
Doppler Velocity ◽  
Fundamental Constants ◽  
Velocity Shift ◽  
Theoretical Predictions

The fundamental dimensionless physical constants cannot be predicted by theory but can only be measured experimentally. And so it is of their possible variation where there are several theoretical predictions but unfortunately with little theoretical guidance on the expected rate of change. The role of fundamental constants in the representation of nature as well as the implications of their variability for the Equivalence Principle and cosmology have been highlighted in many contributions at this conference (cfr K. Olive and J.P Uzan, these proceedings). Measuring the variability of the fine structure constant α or the electron-to-proton ratio μ by means of absorption lines implies the measurement of a tiny variation of the position of one or a few lines with regard to other lines which are taken as reference. For the fine structure constant the relation between its change and the doppler velocity shift is:

scholarly journals Leading isospin-breaking corrections to meson masses on the lattice

2018 ◽  
Vol 175 ◽  
pp. 06002 ◽  
Author(s):  
Davide Giusti ◽  
Vittorio Lubicz ◽  
Guido Martinelli ◽  
Francesco Sanfilippo ◽  
Silvano Simula ◽  
...  
Keyword(s):  
Fine Structure ◽  
Quark Mass ◽  
Light Quark ◽  
Structure Constant ◽  
Mass Splitting ◽  
Fine Structure Constant ◽  
Isospin Breaking ◽  
Decay Constants ◽  
Quark Masses ◽  
Small Parameters

We present a study of the isospin-breaking (IB) corrections to pseudoscalar (PS) meson masses using the gauge configurations produced by the ETM Collaboration with Nf = 2+1+1 dynamical quarks at three lattice spacings varying from 0.089 to 0.062 fm. Our method is based on a combined expansion of the path integral in powers of the small parameters [see formula in PDF] and αem, where [see formula in PDF] is the renormalized quark mass and αem the renormalized fine structure constant. We obtain results for the pion, kaon and Dmeson mass splitting; for the Dashen’s theorem violation parameters ϵγ(MM, 2 GeV), ϵπ0 ϵK0(MS, 2 GeV) for the light quark masses [see formula in PDF] for the flavour symmetry breaking parameters R(MS, 2 GeV) and Q(MS, 2 GeV) and for the strong IB effects on the kaon decay constants.

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.

The measurement of the fundamental constants

1983 ◽  
Vol 310 (1512) ◽  
pp. 215-220
Keyword(s):  
Fine Structure ◽  
Josephson Effect ◽  
Structure Constant ◽  
Atomic Mass ◽  
Fine Structure Constant ◽  
Fundamental Constants ◽  
Velocity Of Light ◽  
Time Standard

Some recent precision experiments that are likely to influence the accepted values of the fundamental constants are reviewed briefly: the measurement of the velocity of light, the possibility of redefining the metre in terms of the caesium time standard, developments that may allow the introduction of an atomic mass standard, the use of the Josephson effect to maintain electrical standards, and some experiments that have led to an improved precision for the fine structure constant.

scholarly journals Search for variation of the fundamental constants in atomic, molecular, and nuclear spectra

2009 ◽  
Vol 87 (1) ◽  
pp. 25-33 ◽  
Author(s):  
V V Flambaum ◽  
V A Dzuba
Keyword(s):  
Fine Structure ◽  
Absorption Spectra ◽  
Atomic Clock ◽  
Structure Constant ◽  
Fine Structure Constant ◽  
Frequency Change ◽  
Fundamental Constants ◽  
Mass Ratio ◽  
Proton Mass ◽  
Nuclear Transitions

The search for variation of the fundamental constants such as the fine-structure constant α (α = e2/hc) and the ratios of fundamental masses (for example, electron-to-proton mass ratio μ = me/mp) is reviewed. Strong emphasis is given to establishing the relationships between the change in the measured frequencies of atomic, molecular, or nuclear transitions and the corresponding change of the fundamental constants. Transitions in which the sensitivity of the frequency change to the variation of the fine-structure constant is strongly enhanced are discussed and most recent experimental results are presented. Most attention is given to the use of atomic, molecular, and nuclear transitions in the study of quasar absorption spectra and in atomic clock experiments.PACS Nos.: 31.25.Eb, 31.25.Jf

Sign in / Sign up

Export Citation Format

Share Document