86 research outputs found
Virtual Resonant Emission and Oscillatory Long-Range Tails in van der Waals Interactions of Excited States: QED Treatment and Applications
We report on a quantum electrodynamic (QED) investigation of the interaction
between a ground state atom with another atom in an excited state. General
expressions, applicable to any atom, are indicated for the long-range tails
which are due to virtual resonant emission and absorption into and from vacuum
modes whose frequency equals the transition frequency to available lower-lying
atomic states. For identical atoms, one of which is in an excited state, we
also discuss the mixing term which depends on the symmetry of the two-atom wave
function (these evolve into either the gerade or the ungerade state for close
approach), and we include all nonresonant states in our rigorous QED treatment.
In order to illustrate the findings, we analyze the fine-structure resolved van
der Waals interaction for nD-1S hydrogen interactions with n=8,10,12 and find
surprisingly large numerical coefficients.Comment: 6 pages; RevTe
Hydrogen molecular ions for improved determination of fundamental constants
The possible use of high-resolution rovibrational spectroscopy of the
hydrogen molecular ions H + 2 and HD + for an independent determination of
several fundamental constants is analyzed. While these molecules had been
proposed for metrology of nuclear-to-electron mass ratios, we show that they
are also sensitive to the radii of the proton and deuteron and to the Rydberg
constant at the level of the current discrepancies colloquially known as the
proton size puzzle. The required level of accuracy, in the 10 --12 range, can
be reached both by experiments, using Doppler-free two-photon spectroscopy
schemes, and by theoretical predictions. It is shown how the measurement of
several well-chosen rovibrational transitions may shed new light on the
proton-radius puzzle, provide an alternative accurate determination of the
Rydberg constant, and yield new values of the proton-to-electron and
deuteron-to-proton mass ratios with one order of magnitude higher precision
Probing new spin-independent interactions through precision spectroscopy in atoms with few electrons
The very high precision of current measurements and theory predictions of spectral lines in few-electron atoms allows us to efficiently probe the existence of exotic forces between electrons, neutrons and protons. We investigate the sensitivity to new spin-independent interactions in transition frequencies (and their isotopic shifts) of hydrogen, helium and some heliumlike ions. We find that present data probe new regions of the force-carrier couplings to electrons and neutrons around the MeV mass range. We also find that, below few keV, the sensitivity to the electron coupling in precision spectroscopy of helium and positronium is comparable to that of the anomalous magnetic moment of the electron. Finally, we interpret our results in the dark-photon model where a new gauge boson is kinetically mixed with the photon. There, we show that helium transitions, combined with the anomalous magnetic moment of the electron, provide the strongest indirect bound from laboratory experiments above 100Â keV.United States. Department of Energy (Grant DE-SC0012567
Muonic hydrogen and the proton radius puzzle
The extremely precise extraction of the proton radius by Pohl et al. from the
measured energy difference between the 2P and 2S states of muonic hydrogen
disagrees significantly with that extracted from electronic hydrogen or elastic
electron-proton scattering. This is the proton radius puzzle. The origins of
the puzzle and the reasons for believing it to be very significant are
explained. Various possible solutions of the puzzle are identified, and future
work needed to resolve the puzzle is discussed.Comment: Minor modifications, some references added, to appear in Annu. Rev.
Nucl. Part. Sci. Vol 63 (2013). 60 pages, 5 figures, 1 tabl
Atomic Physics Constraints on the X Boson
Recently, a peak in the light fermion pair spectrum at invariant q)2 ≈ (16.7MeV)2 has been observed in the bombardment of 7Li by protons. This peak has been interpreted in terms of a protophobic interaction of fermions with a gauge boson (X boson) of invariant mass ≈16.7MeV which couples mainly to neutrons. High-precision atomic physics experiments aimed at observing the protophobic interaction need to separate the X boson effect from the nuclear-size effect, which is a problem because of the short range of the interaction (11.8 fm), which is commensurate with a nuclear halo. Here we analyze the X boson in terms of its consequences for both electronic atoms as well as muonic hydrogen and deuterium. We find that the most promising atomic systems where the X boson has an appreciable effect, distinguishable from a finite-nuclear-size effect, are muonic atoms of low and intermediate nuclear charge numbers
Natural line profile asymmetry
The paper discusses the line profile asymmetry of the photon scattering
process that arises naturally in quantum electrodynamics (QED). Based on
precision spectroscopic experiments conducted on hydrogen atoms, we focus our
attention on the two-photon transition. As one of the most precisely
determined transition frequencies, it is a key pillar of optical frequency
standards and is used in determining fundamental physical constants, testing
physical principles, and searching constraints on new fundamental interactions.
The results obtained in this work show the need to take into account the
natural line profile asymmetry in precision spectroscopic experiments
Atomic Physics Constraints on the X Boson
Recently, a peak in the light fermion pair spectrum at invariant q^2
approximately equal to 16.7 Me^2. has been observed in the bombardment of Li-7
by protons. This peak has been interpreted in terms of a protophobic
interaction of fermions with a gauge boson (X boson) of invariant mass of
approximately 16.7 MeV which couples mainly to neutrons. High-precision atomic
physics experiments aimed at observing the protophobic interaction need to
separate the X boson effect from the nuclear-size effect, which is a problem
because of the short range of the interaction 11.8 fm, which is commensurate
with a "nuclear halo". Here, we analyze the X boson in terms of its
consequences for both electronic atoms as well as muonic hydrogen and
deuterium. We find that the most promising atomic systems where the X boson has
an appreciable effect, distinguishable from a finite-nuclear-size effect, are
muonic atoms of low and intermediate nuclear charge numbers.Comment: 8 pages; RevTe
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