scholarly journals Fine structure of helium and light helium-like ionsThis paper was presented at the International Conference on Precision Physics of Simple Atomic Systems, held at École de Physique, les Houches, France, 30 May – 4 June, 2010.

2011 ◽  
Vol 89 (1) ◽  
pp. 95-101 ◽  
Author(s):  
Krzysztof Pachucki ◽  
Vladimir A. Yerokhin
Keyword(s):  
Experimental Data ◽  
Fine Structure ◽  
Nuclear Charge ◽  
Structure Constant ◽  
Experimental Results ◽  
Fine Structure Constant ◽  
Atomic Systems ◽  
Fine Structure Splitting ◽  
Theoretical Predictions ◽  
Structure Splitting

Calculational results are presented for the fine structure splitting of the 23P state of helium and helium-like ions with nuclear charge Z up to 10. Theoretical predictions are in agreement with the latest experimental results for the helium fine structure intervals as well as with the most of the experimental data available for light helium-like ions. Comparing the theoretical value of the 23P0-23P1 interval in helium with experimental results (Zelevinsky et al. Phys. Rev. Lett. 95, 203001 (2005)), we determine the value of the fine structure constant α with an accuracy of 31 ppb.

scholarly journals Precision spectroscopy of atomic helium

2020 ◽  
Vol 7 (12) ◽  
pp. 1818-1827
Author(s):  
Yu R Sun ◽  
Shui-Ming Hu
Keyword(s):  
Fine Structure ◽  
Quantum Electrodynamics ◽  
Structure Constant ◽  
Fine Structure Constant ◽  
Nuclear Charge Radius ◽  
Precision Spectroscopy ◽  
Structure Splitting ◽  
Three Body ◽  
Atomic Helium

Abstract Helium is a prototype three-body system and has long been a model system for developing quantum mechanics theory and computational methods. The fine-structure splitting in the 23P state of helium is considered to be the most suitable for determining the fine-structure constant α in atoms. After more than 50 years of efforts by many theorists and experimentalists, we are now working toward a determination of α with an accuracy of a few parts per billion, which can be compared to the results obtained by entirely different methods to verify the self-consistency of quantum electrodynamics. Moreover, the precision spectroscopy of helium allows determination of the nuclear charge radius, and it is expected to help resolve the ‘proton radius puzzle’. In this review, we introduce the latest developments in the precision spectroscopy of the helium atom, especially the discrepancies among theoretical and experimental results, and give an outlook on future progress.

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:

The Present Key Importance of the Fine Structure Constant,α, to a Better Knowledge of All the Fundamental Physical Constants

1966 ◽  
Vol 21 (1-2) ◽  
pp. 70-79 ◽  
Author(s):  
Jesse W. M. DuMond
Keyword(s):  
Fine Structure ◽  
Correction Term ◽  
Fundamental Constant ◽  
Structure Constant ◽  
Internal Field ◽  
Fine Structure Constant ◽  
Sources Of Information ◽  
Hydrogen Maser ◽  
A Value ◽  
Structure Splitting

The dilemma is described which exists at the present time between the two present best sources of information as to the numerical value of the Sommerfeld fine structure constant, α. These two sources are the fine structure splitting in deuterium, determined in 1953 by Triebwasser, Dayhoff and Lamb, and the hyperfine structure splitting in hydrogen, measured more recently using the Ramsey hydrogen maser. The theoretical connection between the fine structure measurements and α is subject to little question but the experimental difficulties to obtain a precision of a few ppm are considerable. The relative precision obtained with the hydrogen maser on the other hand, is phenomenal (of order 10-11) but the theoretical connection between the hyperfine splitting and α is subject to a controversial correction for the internal field structure of the proton. Assuming this correction term to be correct at its present value, the hf splitting in Η implies a value of α 26 ppm higher than the fs splitting in D. Present existing sources of evidence, some favourable to the lower and some to the higher value of α, are presented and discussed and the key importance of a better knowledge of this fundamental constant is stressed.

scholarly journals Variations on Photon Vacuum Polarization

2019 ◽  
Vol 218 ◽  
pp. 01003 ◽  
Author(s):  
Fred Jegerlehner
Keyword(s):  
Fine Structure ◽  
Lattice Qcd ◽  
Vacuum Polarization ◽  
Magnetic Moments ◽  
Structure Constant ◽  
Fine Structure Constant ◽  
Isospin Breaking ◽  
Weak Mixing ◽  
Mixing Parameter ◽  
Theoretical Predictions

I provide updates for the theoretical predictions of the muon and electron anomalous magnetic moments, for the shift in the fine structure constant α(MZ )and for the weak mixing parameter $ \mathop {\sin }\nolimits^2 \mathop \Theta \nolimits_w (\mathop M\nolimits_Z ) $. Phenomenological results for Euclidean time correlators, the key objects in the lattice QCD approach to hadronic vacuum polarization, are briefly considered. Furthermore,I present a list of isospin breaking and electromagnetic corrections for the lepton moments, which may be used to supplement lattice QCD results obtained in the isospin limit and without the e.m. corrections.

Precision measurements of fine and hyperfine structure in lithium I and II

2005 ◽  
Vol 83 (4) ◽  
pp. 327-337 ◽  
Author(s):  
W A van Wijngaarden
Keyword(s):  
Fine Structure ◽  
Quantum Electrodynamics ◽  
Nuclear Charge ◽  
Structure Constant ◽  
Precision Measurements ◽  
Fine Structure Constant ◽  
Recent Measurement ◽  
Charge Radii ◽  
Fine And Hyperfine Structure

Recent advances in modeling Li I and II in conjunction with improved experimental techniques have enabled precise tests of quantum electrodynamics. For Li+, the hyperfine intervals of the 1s2s 3S1 and 1s2p 3P0,1,2 states are in excellent agreement with theory. A recent measurement of the 1s2p 3P1,2 fine-structure interval also agrees well with the calculated value and resolves a discrepancy found by two prior experiments. For neutral lithium, discrepancies exist among the results of various experiments for the 6,7Li D1 isotope shift and the 2P fine structure. However, all of the fine-structure measurements are several MHz larger than the theoretical value. Prospects for future experiments to improve the determination of the fine-structure constant and the relative 6,7Li nuclear charge radii are discussed. PACS Nos.: 32.10.Fn, 31.30.Gs, 42.62.Fi

Toward a determination of the fine structure constant at LNE by means of a new Thompson–Lampard calculable capacitorThis paper was presented at the International Conference on Precision Physics of Simple Atomic Systems, held at École de Physique, les Houches, France, 30 May – 4 June, 2010.

2011 ◽  
Vol 89 (1) ◽  
pp. 169-176 ◽  
Author(s):  
P. Gournay ◽  
O. Thévenot ◽  
L. Dupont ◽  
J. M. David ◽  
F. Piquemal
Keyword(s):  
Fine Structure ◽  
Quantum Electrodynamics ◽  
Structure Constant ◽  
Fine Structure Constant ◽  
Current Development ◽  
Atomic Systems ◽  
International Conference ◽  
New Si ◽  
Cross Capacitor

This paper reports on the current development of a new Thompson–Lampard calculable capacitor at LNE. The goal is to determine the von Klitzing constant RK at a significant level of uncertainty of about one part in 108. The comparison with other accurate measurements of h/e2 serves as a relevant test of validity of the theory predicting RK = h/e2, a decisive issue within the context of the new SI. Conversely, assuming that this relation is exact, the measurement of RK and thus that of the fine structure constant α can be used for testing quantum electrodynamics theory. The mechanical structure of the new LNE calculable cross capacitor has been designed and a new set of electrodes has been fabricated. The assembling of the calculable capacitor is in progress.

scholarly journals New Limit on Space-Time Variations in the Proton-to-Electron Mass Ratio from Analysis of Quasar J110325-264515 Spectra

Symmetry ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 344
Author(s):  
T. D. Le
Keyword(s):  
Fine Structure ◽  
Structure Constant ◽  
Space Time ◽  
Fine Structure Constant ◽  
Electron Mass ◽  
Mass Ratio ◽  
Quasar Spectra ◽  
Time Variations ◽  
Using Data ◽  
The Universe

Astrophysical tests of current values for dimensionless constants known on Earth, such as the fine-structure constant, α , and proton-to-electron mass ratio, μ = m p / m e , are communicated using data from high-resolution quasar spectra in different regions or epochs of the universe. The symmetry wavelengths of [Fe II] lines from redshifted quasar spectra of J110325-264515 and their corresponding values in the laboratory were combined to find a new limit on space-time variations in the proton-to-electron mass ratio, ∆ μ / μ = ( 0.096 ± 0.182 ) × 10 − 7 . The results show how the indicated astrophysical observations can further improve the accuracy and space-time variations of physics constants.

A Technique for the Laboratory Determination of Recirculation in Single Needle Dialysis

1993 ◽  
Vol 16 (2) ◽  
pp. 63-70 ◽  
Author(s):  
N.A. Hoenich ◽  
P.T. Smirthwaite ◽  
C. Woffindin ◽  
P. Lancaster ◽  
T.H. Frost ◽  
...  
Keyword(s):  
Experimental Data ◽  
Flow Rate ◽  
Experimental Results ◽  
New Technique ◽  
Treatment Efficiency ◽  
Single Lumen ◽  
Theoretical Predictions ◽  
Lumen Catheter ◽  
A New Technique

Recirculation is an important factor in single needle dialysis and, if high, can compromise treatment efficiency. To provide information regarding recirculation characteristics of access devices used in single needle dialysis, we have developed a new technique to characterise recirculation and have used this to measure the recirculation of a Terumo 15G fistula needle and a VasCath SC2300 single lumen catheter. The experimentally obtained results agreed well with those established clinically (8.5 ± 2.4% and 18.4 ± 3.4%). The experimental results have also demonstrated a dependence on access type, pump speeds and fistula flow rate. A comparison of experimental data with theoretical predictions showed that the latter exceeded those measured with the largest contribution being due to the experimental fistula.

Exciton fine structure splitting of single InGaAs self-assembled quantum dots

2004 ◽  
Vol 21 (2-4) ◽  
pp. 175-179 ◽  
Author(s):  
A Högele ◽  
B Alèn ◽  
F Bickel ◽  
R.J Warburton ◽  
P.M Petroff ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Fine Structure ◽  
Fine Structure Splitting ◽  
Structure Splitting ◽  
Self Assembled
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