arXiv subjects
Publications and source records attributed to V. V. Flambaum.
We analyze the AC Stark shift of the Cs microwave atomic clock transition theoretically and experimentally. Theoretical and experimental data are in a good agreement with each other. Results indicate the absence of a magic wavelength at which there would be no differential shift of the clock states having zero projections of the total angular momentum.
The effects of the variation of the dimensionless strong interaction parameter Xq=mq/Lambda{QCD} (mq is the quark mass, Lambda{QCD} is the QCD scale) are enhanced about 1.5 x 10**5 times in the 7.6 eV "nuclear clock" transition between the ground and first excited states in the 229Th nucleus and about 1 x 10**8 times in the relative shift of the 0.1 eV compound resonance in 150Sm.The best terrestrial limit on the temporal variation of the fundamental constants, |delta(Xq)/Xq| < 4 x 10**-9 at 1.8 billion years ago (|d(Xq/Xq)/dt| < 2.2 x 10**-18 y**-1), is obtained from the shift of this Sm resonance derived from the Oklo natural nuclear reactor data. The results for 229Th and 150Sm are obtained by extrapolation from light nuclei where the many-body calculations can be performed more accurately. The errors produced by such extrapolation may be smaller than the errors of direct calculations in heavy nuclei. The extrapolation results are compared with the "direct" estimates obtained using the Walecka model. A number of numerical relations needed for the calculations of the variation effects in nuclear physics and atomic spectroscopy have been obtained: for the nuclear binding energy delta(E)/E ~ -1.45 delta(mq)/mq, for the spin-orbit intervals delta(Eso)/Eso ~ -0.22 delta(mq)/mq, for the nuclear radius delta(r)/r ~ 0.3 delta(mq)/mq (in units of Lambda{QCD}); for the shifts of nuclear resonances and weakly bound energy levels delta(Er) ~ 10 delta(Xq)/Xq MeV.
We consider microwave hyperfine transitions in the ground state of cesium and rubidium atoms which are presently used as the primary and the secondary frequency standards. The atoms are confined in an optical lattice generated by a circularly polarized laser field. We demonstrate that applying an external magnetic field with appropriately chosen direction may cancel dynamic Stark frequency shift making the frequency of the clock transition insensitive to the strengths of both the laser and the magnetic fields. This can be attained for practically any laser frequency which is sufficiently distant from a resonance.
High-precision calculations of the energy levels of the superheavy element Z=120 are presented. The relativistic Hartree-Fock and configuration interaction techniques are employed. The correlations between core and valence electrons are treated by means of the correlation potential method and many-body perturbation theory. Similar calculations for barium and radium are used to gauge the accuracy of the calculations and to improve the ab initio results.
We propose a new class of atomic microwave clocks based on the hyperfine transitions in the ground state of aluminum or gallium atoms trapped in optical lattices. For these elements magic wavelengths exist at which both levels of the hyperfine doublet are shifted at the same rate by the lattice laser field, cancelling its effect on the clock transition. Our analysis of various systematic effects shows that, while offering an improved control over systematic errors, the accuracy of the proposed microwave clock is competitive to that of the state-of-the-art primary frequency standard.
In the Letter [1] (also [2]) there is a claim that the generalised second law of thermodynamics (entropy increase) for black holes provides some limits on the rate of variation of the fundamental constants of nature (electric charge e, speed of light c, etc.). We have come to a different conclusion. The results in [1,2] are based on assumption that mass of a black hole does not change without radiation and accreation. We present arguments showing that this assumption is incorrect and give an estimate of the black hole mass variation due to alpha=e^2/\hbar c variation using entropy (and quantum energy level) conservation in an adiabatic process. No model-independent limits on the variation of the fundamental constants are derived from the second law of thermodynamics.
Exchange interaction strongly influences the long-range behaviour of localised electron orbitals. It violates the oscillation theorem (creates extra nodes) and produces a power-law decay instead of the usual exponential decrease at large distances. For inner orbitals inside molecules decay is 1/r^2, for macroscopic systems cos(k_f r)/r^n, where k_f is the Fermi momentum and n=3 for 1D, n=3.5 for 2D and n=4 for 3D crystal. Slow decay increases the exchange interaction between localised spins and the under-barrier tunneling amplitude.The under-barrier transmission coefficients in solids (e.g. for point contacts) become temperature-dependent.
We calculated the contribution of Coulomb energy to the spacing between the ground and first excited state of $^{229}$Th nucleus as a function of the deformation parameter $δ$. We show that despite the fact that the odd particle is a neutron, the change in Coulomb energy between these two states can reach several hundreds KeV.This means that the effect of the variation of the fine structure constant $α=e^2/\hbar c$ may be enhanced $ΔU_C/E \sim 10^4$ times in the $E=$7.6 eV "nuclear clock" transition between the ground and first excited states in the $^{229}$Th nucleus.
We calculate correction to the nuclear fission barrier produced by the atomic electrons. The result presented in analytical form is convenient to use in future nuclear calculations. The atomic electrons have a small stabilizing effect on nuclei, increasing lifetime in nuclear fission channel. This effect gives a new instrument to study the fission process.
High-precision calculations of the energy levels of the superheavy elements E119 and E120+ are presented. Dominating correlation corrections beyond relativistic Hartree-Fock are included to all orders in the Coulomb interaction using the Feynman diagram technique and the correlation potential method. The Breit interaction and quantum electrodynamics radiative corrections are considered. Also, the volume isotope shift is determined. A similar treatment for Cs, Fr, Ba+ and Ra+ is used to gauge the accuracy of the calculations and to refine the ab initio results.
The search for variation of the fundamental constants such as the fine structure constant $α$ ($α=e^2/\hbar c$) and the ratios of fundamental masses (e.g., electron to proton mass ratio $μ=m_e/m_p$) 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.
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 which allow to perform calculations for atoms or ions with different electron structure and which cover practically all 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.
The $^1\mathrm{S}_0$-$^3\mathrm{P}_0$ clock transition frequency $ν_\text{Sr}$ in neutral $^{87}$Sr has been measured relative to the Cs standard by three independent laboratories in Boulder, Paris, and Tokyo over the last three years. The agreement on the $1\times 10^{-15}$ level makes $ν_\text{Sr}$ the best agreed-upon optical atomic frequency. We combine periodic variations in the $^{87}$Sr clock frequency with $^{199}$Hg$^+$ and H-maser data to test Local Position Invariance by obtaining the strongest limits to date on gravitational-coupling coefficients for the fine-structure constant $α$, electron-proton mass ratio $μ$ and light quark mass. Furthermore, after $^{199}$Hg$^+$, $^{171}$Yb$^+$ and H, we add $^{87}$Sr as the fourth optical atomic clock species to enhance constraints on yearly drifts of $α$ and $μ$.
We perform calculations for the neutron skin of nuclei and its contribution to atomic parity non-conservation (PNC) in many isotopes of Cs, Ba, Sm, Dy, Yb, Tl, Pb, Bi, Fr, Ra. Three problems are addressed: i) Neutron-skin induced errors to single-isotope PNC, ii) Possibility to measure neutron skin using atomic PNC, iii) Neutron-skin induced errors for ratios of PNC effects in different isotopes. In the latter case the correlations in the neutron skin values for different isotopes lead to cancelations of the errors; this makes the isotopic ratio method a competitive tool in a search for new physics beyond the standard model.
A calculation of the current-quark-mass-dependence of nucleon static electromagnetic properties is necessary in order to use observational data as a means to place constraints on the variation of Nature's fundamental parameters. A Poincare' covariant Faddeev equation, which describes baryons as composites of confined-quarks and -nonpointlike-diquarks, is used to calculate this dependence The results indicate that, like observables dependent on the nucleons' magnetic moments, quantities sensitive to their magnetic and charge radii, such as the energy levels and transition frequencies in Hydrogen and Deuterium, might also provide a tool with which to place limits on the allowed variation in Nature's constants.
This review article is devoted to application of precision molecular spectroscopy to studies of the possible spatial and temporal variations of the fundamental constants. Both astrophysical observations and laboratory experiments are discussed.
Review of recent works devoted to the temporal and spatial variation of the fundamental constants and dependence of the fundamental constants on the gravitational potential (violation of local position invariance) is presented. We discuss the variation of the fine structure constant $α=e^2/\hbar c$, strong interaction and fundamental masses (Higgs vacuum), e.g. the electron-to-proton mass ratio $μ=m_e/M_p$ or $X_e=m_e/Λ_{QCD}$ and $X_q=m_q/Λ_{QCD}$. We also present new results from Big Bang nucleosynthesis and Oklo natural nuclear reactor data and propose new measurements of enhanced effects in atoms, nuclei and molecules, both in quasar and laboratory spectra.
Dependence of transition frequencies on the fine structure constant $α=e^2/\hbar c$ is calculated for several many-electron systems which are used or planned to be used in the laboratory search for the time variation of the fine structure constant. In systems with a large number of electrons in open shells (from 11 to 15) the relative effects of the variation may be strongly enhanced. For the transitions which were considered before the results are in good agreement with previous calculations.