Testing fundamental interactions on the helium atom
Result description
We critically examine the current status of theoretical calculations of the energies, the fine structure, and the isotope shift of the lowest-lying states of helium, searching for unresolved discrepancies with experiments. Calculations are performed within the quantum electrodynamics expansion in powers of the fine structure constant a and the electron-to-nucleus mass ratio m/M. For energies, theoretical results are complete through orders alpha(6)m and alpha(6)m(2)/M, with the resulting accuracy ranging from 0.5 to 2 MHz for the n = 2 states. The fine-structure splitting of the 2(3) P state is predicted with a much better accuracy, 1.7 kHz, as a consequence of a calculation of the next-order alpha(7)m effect. An excellent agreement of the theoretical predictions with the recent measurements of the fine structure provides one of the best tests of the bound-state QED in few-electron systems. The isotope shift between He-3 and He-4 is treated with a subkilohertz accuracy, which allows for a high-precision determination of the differences of the nuclear charge radii delta r(2). Several such determinations, however, yield results that are in a 4 sigma disagreement with each other, which remains unexplained. Apart from this, we find no significant discrepancies between theory and experiment for the helium atom. A further calculation of the yet unknown alpha(7)m correction to energy levels will provide a sensitive test of universality in electromagnetic interactions of leptons by comparison of nuclear charge radii obtained by the helium and muonic helium spectroscopy.
Keywords
masshe-3protonradiusfrequencytransitionstatelamb shiftenergy-levels
The result's identifiers
Result code in IS VaVaI
Result on the web
DOI - Digital Object Identifier
Alternative languages
Result language
angličtina
Original language name
Testing fundamental interactions on the helium atom
Original language description
We critically examine the current status of theoretical calculations of the energies, the fine structure, and the isotope shift of the lowest-lying states of helium, searching for unresolved discrepancies with experiments. Calculations are performed within the quantum electrodynamics expansion in powers of the fine structure constant a and the electron-to-nucleus mass ratio m/M. For energies, theoretical results are complete through orders alpha(6)m and alpha(6)m(2)/M, with the resulting accuracy ranging from 0.5 to 2 MHz for the n = 2 states. The fine-structure splitting of the 2(3) P state is predicted with a much better accuracy, 1.7 kHz, as a consequence of a calculation of the next-order alpha(7)m effect. An excellent agreement of the theoretical predictions with the recent measurements of the fine structure provides one of the best tests of the bound-state QED in few-electron systems. The isotope shift between He-3 and He-4 is treated with a subkilohertz accuracy, which allows for a high-precision determination of the differences of the nuclear charge radii delta r(2). Several such determinations, however, yield results that are in a 4 sigma disagreement with each other, which remains unexplained. Apart from this, we find no significant discrepancies between theory and experiment for the helium atom. A further calculation of the yet unknown alpha(7)m correction to energy levels will provide a sensitive test of universality in electromagnetic interactions of leptons by comparison of nuclear charge radii obtained by the helium and muonic helium spectroscopy.
Czech name
—
Czech description
—
Classification
Type
Jimp - Article in a specialist periodical, which is included in the Web of Science database
CEP classification
—
OECD FORD branch
10300 - Physical sciences
Result continuities
Project
—
Continuities
I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace
Others
Publication year
2017
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů
Data specific for result type
Name of the periodical
Physical Review A
ISSN
2469-9926
e-ISSN
—
Volume of the periodical
95
Issue of the periodical within the volume
6
Country of publishing house
US - UNITED STATES
Number of pages
8
Pages from-to
—
UT code for WoS article
000404461300005
EID of the result in the Scopus database
—
Basic information
Result type
Jimp - Article in a specialist periodical, which is included in the Web of Science database
OECD FORD
Physical sciences
Year of implementation
2017