Progress in helium fine-structure calculations and the fine-structure constant

2002 ◽  
Vol 80 (11) ◽  
pp. 1195-1212 ◽  
Author(s):  
G WF Drake
Keyword(s):  
Fine Structure ◽  
Structure Constant ◽  
Fine Structure Constant ◽  
Electron Interaction ◽  
Computational Uncertainty ◽  
Structure Calculations ◽  
Theory And Experiment

The long-term goal of this work is to determine the fine-structure constant α from a comparison between theory and experiment for the fine-structure splittings of the helium 1s2p 3PJ states. All known terms of order α5 a.u. (α7 mc2) arising from the electron–electron interaction, and recoil corrections of order α4 µ / M a.u. are evaluated and added to previous tabulation. The predicted energy splittings are ν0,1 = 29 616.946 42(18) MHz and ν1,2 = 2291.154 62(31) MHz. Although the computational uncertainty is much less than ±1 kHz, there is an unexplained discrepancy between theory and experiment of 19.4(1.4) kHz for ν1,2. PACS Nos.: 31.30Jv, 32.10Fn

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.

scholarly journals Measurement of the running of the fine structure constant below 1 GeV with the KLOE detector

2019 ◽  
Vol 218 ◽  
pp. 02012
Author(s):  
Graziano Venanzoni
Keyword(s):  
Fine Structure ◽  
Energy Region ◽  
Direct Evidence ◽  
Branching Ratio ◽  
Structure Constant ◽  
Fine Structure Constant ◽  
Recent Measurement ◽  
Single Measurement ◽  
Lepton Universality ◽  
Hadronic Contribution

I will report on the recent measurement of the fine structure constant below 1 GeV with the KLOE detector. It represents the first measurement of the running of α(s) in this energy region. Our results show a more than 5σ significance of the hadronic contribution to the running of α(s), which is the strongest direct evidence both in time-and space-like regions achieved in a single measurement. From a fit of the real part of Δα(s) and assuming the lepton universality the branching ratio BR(ω → µ+µ−) = (6.6 ± 1.4stat ± 1.7syst) · 10−5 has been determined

scholarly journals Fine structure constant and the CMB damping scale

2012 ◽  
Vol 85 (10) ◽  
Author(s):  
Eloisa Menegoni ◽  
Maria Archidiacono ◽  
Erminia Calabrese ◽  
Silvia Galli ◽  
C. J. A. P. Martins ◽  
...  
Keyword(s):  
Fine Structure ◽  
Structure Constant ◽  
Fine Structure Constant

CONSTRAINTS ON SPATIAL VARIATIONS IN THE FINE-STRUCTURE CONSTANT FROMPLANCK

2014 ◽  
Vol 798 (1) ◽  
pp. 18 ◽  
Author(s):  
Jon O'Bryan ◽  
Joseph Smidt ◽  
Francesco De Bernardis ◽  
Asantha Cooray
Keyword(s):  
Fine Structure ◽  
Structure Constant ◽  
Spatial Variations ◽  
Fine Structure Constant

PHASE TRANSITIONS IN STRONG COUPLING QED4[N]

1992 ◽  
Vol 07 (30) ◽  
pp. 7629-7646 ◽  
Author(s):  
D. ATKINSON ◽  
H.J. DE GROOT ◽  
P.W. JOHNSON
Keyword(s):  
Phase Transition ◽  
Fixed Point ◽  
Fine Structure ◽  
Mean Field ◽  
Structure Constant ◽  
Fine Structure Constant ◽  
Massless Fermion ◽  
Charge Renormalization ◽  
Dynamical Breaking ◽  
Proper Account

We analyze coupled Dyson-Schwinger equations for massless fermion and photon propagators in QED4[N], taking proper account of charge renormalization. With one fermion flavor, we find a fixed point at an ultraviolet “fine-structure constant” of 2.10, corresponding to a phase transition (associated with the dynamical breaking of chiral symmetry) of mean-field type.

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