scholarly journals Atomic calculations and search for variation of the fine-structure constant in quasar absorption spectra

2009 ◽  
Vol 87 (1) ◽  
pp. 15-23 ◽  
Author(s):  
V A Dzuba ◽  
V V Flambaum
Keyword(s):  
Fine Structure ◽  
Absorption Spectra ◽  
Periodic Table ◽  
Structure Constant ◽  
Electron Structure ◽  
Special Consideration ◽  
Fine Structure Constant ◽  
Critical Compilation

A brief review of the search for variation of the fine-structure constant in quasar absorption spectra is presented. Special consideration is given to the role of atomic calculations in the analysis of the observed data. A range of methods that allows us to perform calculations for atoms or ions with different electron structure and which cover practically all the Periodic Table of elements is discussed. Critical compilation of the results of the calculations as well as a review of the most recent results of the analysis are presented.PACS Nos.: 31.25.Eb, 31.25.Jf

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 An Updated Constraint on Variations of the Fine-Structure Constant Using Wavelengths of Fe II Absorption Line Multiplets

Symmetry ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 722 ◽  
Author(s):  
T. D. Le
Keyword(s):  
Fine Structure ◽  
Absorption Line ◽  
Absorption Spectra ◽  
Structure Constant ◽  
Fine Structure Constant ◽  
The Future ◽  
Stringent Limit

A new stringent limit relating to the variation of the fine-structure constant (α= e2/4πε0ℏc) has been extracted from Ritz wavelengths of 27 quasi_stellar object (QSO) absorption spectra lines of Fe II. The calculation was combined with laboratory wavelengths and QSO spectra to obtain the result ∆α/α=(0.027±0.832)×10-6. This result suggests how dedicated astrophysical estimations can improve these limits in the future and can also constrain space_time variations.

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

scholarly journals Experimental evidence of plasmarons and effective fine structure constant in electron-doped graphene/h-BN heterostructure

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Hongyun Zhang ◽  
Shuopei Wang ◽  
Eryin Wang ◽  
Xiaobo Lu ◽  
Qian Li ◽  
...  
Keyword(s):  
Fine Structure ◽  
Interaction Strength ◽  
Structure Constant ◽  
Fine Structure Constant ◽  
Electron Interaction ◽  
Strong Electron ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Doped Graphene

AbstractElectron-electron interaction is fundamental in condensed matter physics and can lead to composite quasiparticles called plasmarons, which strongly renormalize the dispersion and carry information of electron-electron coupling strength as defined by the effective fine structure constant $${\alpha }_{ee}^{* }$$ α e e * . Although h-BN with unique dielectric properties has been widely used as an important substrate for graphene, so far there is no experimental report of plasmarons in graphene/h-BN yet. Here, we report direct experimental observation of plasmaron dispersion in graphene/h-BN heterostructures through angle-resolved photoemission spectroscopy (ARPES) measurements upon in situ electron doping. Characteristic diamond-shaped dispersion is observed near the Dirac cone in both 0° (aligned) and 13.5° (twisted) graphene/h-BN, and the electron-electron interaction strength $${\alpha }_{ee}^{* }$$ α e e * is extracted to be $${\alpha }_{ee}^{* }\approx 0.9\pm 0.1$$ α e e * ≈ 0.9 ± 0.1 , highlighting the important role of electron-electron interaction. Our results suggest graphene/h-BN as an ideal platform for investigating strong electron-electron interaction with weak dielectric screening, and lays fundamental physics for gate-tunable nano-electronics and nano-plasmonics.

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.

Sign in / Sign up

Export Citation Format

Share Document