V. A. Dzuba

Further evidence for cosmological evolution of the fine structure constant

We describe the results of a search for time variability of the fine structure constant alpha using absorption systems in the spectra of distant quasars. Three large optical data sets and two 21 cm and mm absorption systems provide four independent samples, spanning approximately 23% to 87% of the age of the universe. Each sample yields a smaller alpha in the past and the optical sample shows a 4 sigma deviation: Delta alpha/alpha = -0.72+/-0.18 x 10(-5) over the redshift range 0.5<z<3.5. We find no systematic effects which can explain our results. The only potentially significant systematic effects push Delta alpha/alpha towards positive values; i.e., our results would become more significant were we to correct for them.

Possible evidence for a variable fine-structure constant from QSO absorption lines: motivations, analysis and results

An experimental search for variation in the fundamental coupling constants is strongly motivated by modern high-energy physics theories. Comparison of quasar absorption line spectra with laboratory spectra provides a sensitive probe for variability of the ne structure constant, , over cosmological time-scales. We have previously developed and applied a new method providing an order of magnitude gain in precision over previous optical astrophysical constraints. Here we extend that work by including new quasar spectra of damped Lyman- absorption systems. We also re-analyse our previous lower redshift data and conrm our initial results. The constraints on come from simultaneous tting of absorption lines of subsets of the following species: Mgi ,M gii, Alii ,A liii ,S iii ,C rii ,F eii ,N iii and Znii. We present a detailed description of our methods and results based on an analysis of 49 quasar absorption systems (towards 28 QSOs) covering the redshift range 0:5 <z <3:5. There is statistical evidence for a smaller at earlier epochs: = =( 0:720:18)10 5 . The new and original samples are independent but separately yield consistent and signicant non-zero values of =. We summarise the results of a thorough investigation of systematic eects published in a companion paper. The value we quote above is the raw value, not corrected for any of these systematic eects. The only signicant systematic eects so far identied, if removed from our data, would lead to a more signicant deviation of = from zero.

Single-ion nuclear clock for metrology at the 19th decimal place.

The 7.6(5) eV nuclear magnetic-dipole transition in a single 229Th3+ ion may provide the foundation for an optical clock of superb accuracy. A virtual clock transition composed of stretched states within the 5F(5/2) electronic ground level of both nuclear ground and isomeric manifolds is proposed. It is shown to offer unprecedented systematic shift suppression, allowing for clock performance with a total fractional inaccuracy approaching 1×10(-19).

Revisiting parity non-conservation in cesium

We apply the sum-over-states approach to calculate partial contributions to parity nonconservation (PNC) in cesium [Porsev, Beloy, and Drevianko, Phys. Rev. Lett. 102, 181601 (2009)]. We find significant corrections to two nondominating terms coming from the contribution of the core and highly excited states (n>9, the so called tail). When these differences are taken into account the result of Porsev et al., E(PNC)=0.8906(24)×10(-11)i(-Q(W)/N) changes to 0.8977 (40), coming into good agreement with our previous calculations, 0.8980 (45). The interpretation of the PNC measurements in cesium still indicates reasonable agreement with the standard model (1.5σ); however, it gives new constraints on physics beyond it.

Summation of the high orders of perturbation theory for the parity nonconserving E1-amplitude of the 6s–7s transition in the caesium atom

Abstract Three dominating subsequences of diagrams in the correlation correction to amplitude are summed: screening of the electron-electron interaction, particle-hole interaction, and the iterations of the self-energy. The result of the calculations is E 1(6 s –7 s ) = (0.91 ± 0.01) × 10 −11 iea B (− Q w / N ), Q w is the weak charge of the nucleus, N is the number of neutrons. A recent experiment of Noecker et al. and our calculation give the following value of the Weinberg angle: sin 2 θ w =0.226±0.007 ( exp )±0.004 ( theor ).

Parity-violating interactions of cosmic fields with atoms, molecules, and nuclei: Concepts and calculations for laboratory searches and extracting limits

We propose methods and present calculations that can be used to search for evidence of cosmic fields by investigating the parity-violating effects, including parity nonconservation amplitudes and electric dipole moments, that they induce in atoms. The results are used to constrain important fundamental parameters describing the strength of the interaction of various cosmic fields with electrons, protons, and neutrons. Candidates for such fields are dark matter (including axions) and dark energy, as well as several more exotic sources described by standard-model extensions. Calculations of the effects induced by pseudoscalar and pseudovector fields are performed for H, Li, Na, K, Cu, Rb, Ag, Cs, Ba, Ba+, Dy, Yb, Au, Tl, Fr, and Ra+. Existing parity nonconservation experiments in Cs, Dy, Yb, and Tl are combined with these calculations to directly place limits on the interaction strength between the temporal component, b(0), of a static pseudovector cosmic field and the atomic electrons, with the most stringent limit of vertical bar b(0)(e)vertical bar < 7 x 10(-15) GeV, in the laboratory frame of reference, coming from Dy. From a measurement of the nuclear anapole moment of Cs, and a limit on its value for Tl, we also extract limits on the interaction strength between the temporal component of this cosmic field, as well as a related tensor cosmic-field component d(00), with protons and neutrons. The most stringent limits of vertical bar b(0)(p)vertical bar < 4 x 10(-8) GeV and vertical bar d(00)(p)vertical bar < 5 x 10(-8) for protons and vertical bar b(0)(n)vertical bar < 2 x 10(-7) GeV and vertical bar d(00)(n)vertical bar < 2 x 10(-7) for neutrons (in the laboratory frame) come from the results using Cs. Axions may induce oscillating parity-and time reversal-violating effects in atoms and molecules through the generation of oscillating nuclear magnetic quadrupole and Schiff moments, which arise from P- and T-odd intranuclear forces and from the electric dipole moments of constituent nucleons. Nuclear spin-independent parity nonconservation effects may be enhanced in diatomic molecules possessing close pairs of opposite-parity levels in the presence of time-dependent interactions.

High-precision calculation of parity nonconservation in cesium and test of the standard model

We have calculated the 6s-7s parity nonconserving (PNC) E1 transition amplitude, E_{PNC}, in cesium. We have used an improved all-order technique in the calculation of the correlations and have included all significant contributionsto E_{PNC}. Our final value E_{PNC} = 0.904 (1 +/- 0.5 %) \times 10^{-11}iea_{B}(-Q_{W}/N) has half the uncertainty claimed in old calculations used for the interpretation of Cs PNC experiments. The resulting nuclear weak chargeQ_{W} for Cs deviates by about 2 standard deviations from the value predicted by the standard model.

Enhanced Laboratory Sensitivity to Variation of the Fine-Structure Constant using Highly Charged Ions

We study atomic systems that are in the frequency range of optical atomic clocks and have enhanced sensitivity to potential time variation of the fine-structure constant α. The high sensitivity is due to coherent contributions from three factors: high nuclear charge Z, high ionization degree, and significant differences in the configuration composition of the states involved. Configuration crossing keeps the frequencies in the optical range despite the large ionization energies. We discuss a few promising examples that have the largest α sensitivities seen in atomic systems.

Relativistic effects in two valence-electron atoms and ions and the search for variation of the fine-structure constant

We perform accurate calculations of the dependence of transition frequencies in two-valence-electron atoms and ions on a variation of the fine-structure constant, {alpha}=e{sup 2}/({Dirac_h}/2{pi})c. The relativistic Hartree-Fock method is used with many-body perturbation theory and configuration interaction methods to calculate transition frequencies. The results are to be used in atomic-clock-type laboratory experiments designed to test whether {alpha} varies in time.

Limiting P-odd interactions of cosmic fields with electrons, protons and neutrons

We propose methods for extracting limits on the strength of P-odd interactions of pseudoscalar and pseudovector cosmic fields with electrons, protons, and neutrons, by exploiting the static and dynamic parity-nonconserving amplitudes and electric dipole moments they induce in atoms. Candidates for such fields are dark matter (including axions) and dark energy, as well as several more exotic sources described by Lorentz-violating standard model extensions. Atomic calculations are performed for H, Li, Na, K, Rb, Cs, Ba(+), Tl, Dy, Fr, and Ra(+). From these calculations and existing measurements in Dy, Cs, and Tl, we constrain the interaction strengths of the parity-violating static pseudovector cosmic field to be 7 × 10(-15) GeV with an electron, and 3 × 10(-8) GeV with a proton.