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V. V. Flambaum

Publications and source records attributed to V. V. Flambaum.

At least 145 records · Page 8Linked to original sources

Electron structure of superheavy elements Uut, Fl and Uup ($Z$=113 to 115)

We use recently developed method of accurate atomic calculations which combines linearized single-double coupled cluster method with the configuration interaction technique to calculate ionisation potentials, excitation energies, static polarizabilities and valence electron densities for superheavy elements Uut, Fl and Uup ($Z$=113 to 115) and their ions. The accuracy of the calculations is controlled by comparing similar calculations for lighter analogs of the superheavy elements, Tl, Pb and Bi with experiment. The role of relativistic effects and correlations is discussed and comparison with earlier calculations is presented.

physics.atom-ph↗

Limits on gravitational Einstein Equivalence Principle violation from monitoring atomic clock frequencies during a year

Sun's gravitation potential at earth varies during a year due to varying Earth-Sun distance. Comparing the results of very accurate measurements of atomic clock transitions performed at different time in the year allows us to study the dependence of the atomic frequencies on the gravitational potential. We examine the measurement data for the ratio of the frequencies in Hg$^+$ and Al$^+$ clock transitions and absolute frequency measurements (with respect to caesium frequency standard) for Dy, Sr, H, hyperfine transitions in Rb and H, and obtain significantly improved limits on the values of the gravity related parameter of the Einstein Equivalence Principle violating term in the Standard Model Extension Hamiltonian $c_{00} = (3.0 \pm 5.7) \times 10^{-7}$ and the parameter for the gravity-related variation of the fine structure constant $κ_α = (-5.3 \pm 10) \times 10^{-8}$.

physics.atom-ph↗

Search for the effect of massive bodies on atomic spectra and constraints on Yukawa-type interactions of scalar particles

We propose a new method to search for hypothetical scalar particles that have feeble interactions with Standard-Model particles. In the presence of massive bodies, these interactions produce a non-zero Yukawa-type scalar-field magnitude. Using radio-frequency spectroscopy data of atomic dysprosium, as well as atomic clock spectroscopy data, we constrain the Yukawa-type interactions of a scalar field with the photon, electron, and nucleons for a range of scalar-particle masses corresponding to length scales $ > 10$ cm. In the limit as the scalar-particle mass $m_ϕ\to 0$, our derived limits on the Yukawa-type interaction parameters are: $Λ_γ\gtrsim 8 \times 10^{19}$ GeV, $Λ_e \gtrsim 1.3 \times 10^{19}$ GeV, and $Λ_N \gtrsim 6 \times 10^{20}$ GeV. Our measurements also constrain combinations of interaction parameters, which cannot otherwise be probed with traditional anomalous-force measurements. We suggest further measurements to improve on the current level of sensitivity.

physics.atom-ph↗

Enhanced effects of variation of the fundamental constants in laser interferometers and application to dark matter detection

We outline new laser interferometer measurements to search for variation of the electromagnetic fine-structure constant $α$ and particle masses (including a non-zero photon mass). We propose a strontium optical lattice clock -- silicon single-crystal cavity interferometer as a novel small-scale platform for these new measurements. Multiple passages of a light beam inside an interferometer enhance the effects due to variation of the fundamental constants by the mean number of passages ($N_{\textrm{eff}} \sim 10^2$ for a large-scale gravitational-wave detector, such as LIGO, Virgo, GEO600 or TAMA300, while $N_{\textrm{eff}} \sim 10^5$ for a strontium clock -- silicon cavity interferometer). Our proposed laser interferometer measurements may be implemented as an extremely precise tool in the direct detection of scalar dark matter that forms an oscillating classical field or topological defects.

physics.atom-ph↗

Enhanced violation of the Lorentz invariance and Einstein's equivalence principle in nuclei and atoms

Local Lorentz Invariance violating (LLIV) and Einstein equivalence principle violating (EEPV) effects in atomic experiments are discussed. The EEPV effects are strongly enhanced in the narrow 7.8 eV transition in 229Th nucleus. Nuclear LLIV momentum tensors describing anisotropy in the maximal attainable speed for massive particles (analog of Michelson-Morley experiment for light) are expressed in terms of the experimental values of nuclear quadrupole moments. Calculations for nuclei of experimental interest 133Cs, 85Rb, 87Rb, 201Hg, 131Xe and 21Ne have been performed. The results for 21Ne are used to improve the limits on the proton LLIV constants by 4 orders of magnitude.

physics.atom-ph↗

Improved limits on interactions of low-mass spin-0 dark matter from atomic clock spectroscopy

Low-mass (sub-eV) spin-0 dark matter particles, which form a coherently oscillating classical field $ϕ= ϕ_0 \cos(m_ϕt)$, can induce oscillating variations in the fundamental constants through their interactions with the Standard Model sector. We calculate the effects of such possible interactions, which may include the linear interaction of $ϕ$ with the Higgs boson, on atomic and molecular transitions. Using recent atomic clock spectroscopy measurements, we derive new limits on the linear interaction of $ϕ$ with the Higgs boson, as well as its quadratic interactions with the photon and light quarks. For the linear interaction of $ϕ$ with the Higgs boson, our derived limits improve on existing constraints by up to $2-3$ orders of magnitude.

physics.atom-ph↗

Reply to comment on "Searching for Topological Defect Dark Matter via Nongravitational Signatures"

In the comment of Avelino, Sousa and Lobo [arXiv:1506.06028], it is argued, by comparing the kinetic energy of a topological defect with the overall energy of a pulsar, that the origin of the pulsar glitch phenomenon due to the passage of networks of topological defects through pulsars is faced with serious difficulties. Here, we point out that topological defects may trigger pulsar glitches within traditional scenarios, such as vortex unpinning. If the energy transfer from a topological defect exceeds the activation energy for a single pinned vortex, this may lead to an avalanche of unpinning of vortices and consequently a pulsar glitch, and therefore the source of angular momentum and energy required for a glitch event is provided by the pulsar itself. Indeed, the activation energy for such a process can be very small (essentially zero compared with the observed increase in the pulsar's rotational kinetic energy at the onset of a glitch). The unpinning of a vortex by a topological defect may occur through the passage of the defect into the core of the pulsar.

hep-ph↗

Dark matter scattering on electrons: Accurate calculations of atomic excitations and implications for the DAMA signal

We revisit the WIMP-type dark matter scattering on electrons that results in atomic ionization, and can manifest itself in a variety of existing direct-detection experiments. Unlike the WIMP-nucleon scattering, where current experiments probe typical interaction strengths much smaller than the Fermi constant, the scattering on electrons requires a much stronger interaction to be detectable, which in turn requires new light force carriers. We account for such new forces explicitly, by introducing a mediator particle with scalar or vector couplings to dark matter and to electrons. We then perform state of the art numerical calculations of atomic ionization relevant to the existing experiments. Our goals are to consistently take into account the atomic physics aspect of the problem (e.g., the relativistic effects, which can be quite significant), and to scan the parameter space: the dark matter mass, the mediator mass, and the effective coupling strength, to see if there is any part of the parameter space that could potentially explain the DAMA modulation signal. While we find that the modulation fraction of all events with energy deposition above 2 keV in NaI can be quite significant, reaching ~50%, the relevant parts of the parameter space are excluded by the XENON10 and XENON100 experiments.

hep-ph↗

Hyperfine-induced electric dipole contributions to the electric octupole and magnetic quadrupole atomic clock transitions

Hyperfine-induced electric dipole contributions may significantly increase probabilities of otherwise very weak electric octupole and magnetic quadrupole atomic clock transitions (e.g. transitions between $s$ and $f$ electron orbitals). These transitions can be used for exceptionally accurate atomic clocks, quantum information processing and search for dark matter. They are very sensitive to new physics beyond the Standard Model, such as temporal variation of the fine structure constant, the Lorentz invariance and Einstein equivalence principle violation. We formulate conditions under which the hyperfine-induced electric dipole contribution dominates. Due to the hyperfine quenching the electric octupole clock transition in $^{173}$Yb$^+$ is two orders of magnitude stronger than that in currently used $^{171}$Yb$^+$. Some enhancement is found in $^{143}$Nd$^{13+}$, $^{149}$Pm$^{14+}$, $^{147}$Sm$^{14+}$, and $^{147}$Sm$^{15+}$ ions.

physics.atom-ph↗

Ionization of atoms by slow heavy particles, including dark matter

Atoms and molecules can become ionized during the scattering of a slow, heavy particle off a bound electron. Such an interaction involving leptophilic weakly interacting massive particles (WIMPs) is a promising possible explanation for the anomalous 9 sigma annual modulation in the DAMA dark matter direct detection experiment [R. Bernabei et al., Eur. Phys. J. C 73, 2648 (2013)]. We demonstrate the applicability of the Born approximation for such an interaction by showing its equivalence to the semiclassical adiabatic treatment of atomic ionization by slow-moving WIMPs. Conventional wisdom has it that the ionization probability for such a process should be exponentially small. We show, however, that due to nonanalytic, cusp-like behaviour of Coulomb functions close to the nucleus this suppression is removed, leading to an effective atomic structure enhancement. Crucially, we also show that electron relativistic effects actually give the dominant contribution to such a process, enhancing the differential cross section by up to 1000 times.

physics.atom-ph↗

Enhanced effects of the Lorentz invariance and Einstein equivalence principle violation in 229Th nuclear transition

The Lorentz invariance and Einstein equivalence principle violating effects in the narrow 7.8 eV transition in 229Th nucleus may be 100 000 times larger than in atoms. This transition may be investigated using high precision laser spectroscopy methods, has a very small width, and suppressed systematic effects. Similar values of the effects are expected in 73 eV 235U nuclear transition which is coming within the reach of the laser spectroscopy. Mossbauer transitions give another possibility.

nucl-th↗

Level-resolved quantum statistical theory of electron capture into many-electron compound resonances in highly charged ions

The strong mixing of many-electron basis states in excited atoms and ions with open $f$ shells results in very large numbers of complex, chaotic eigenstates that cannot be computed to any degree of accuracy. Describing the processes which involve such states requires the use of a statistical theory. Electron capture into these 'compound resonances' leads to electron-ion recombination rates that are orders of magnitude greater than those of direct, radiative recombination, and cannot be described by standard theories of dielectronic recombination. Previous statistical theories considered this as a two-electron capture process which populates a pair of single-particle orbitals, followed by 'spreading' of the two-electron states into chaotically mixed eigenstates. This method is similar to a configuration-average approach, as it neglects potentially important effects of spectator electrons and conservation of total angular momentum. In this work we develop a statistical theory which considers electron capture into 'doorway' states with definite angular momentum obtained by the configuration interaction method. We apply this approach to electron recombination with W$^{20+}$, considering 2 million doorway states. Despite strong effects from the spectator electrons, we find that the results of the earlier theories largely hold. Finally, we extract the fluorescence yield (the probability of photoemission and hence recombination) by comparison with experiment.

physics.atom-ph↗

Can dark matter induce cosmological evolution of the fundamental constants of Nature?

We demonstrate that massive fields, such as dark matter, can directly produce a cosmological evolution of the fundamental constants of Nature. We show that a scalar or pseudoscalar (axion-like) dark matter field $ϕ$, which forms a coherently oscillating classical field and interacts with Standard Model particles via quadratic couplings in $ϕ$, produces `slow' cosmological evolution and oscillating variations of the fundamental constants. We derive limits on the quadratic interactions of $ϕ$ with the photon, electron and light quarks from measurements of the primordial $^4$He abundance produced during Big Bang nucleosynthesis and recent atomic dysprosium spectroscopy measurements. These limits improve on existing constraints by up to 15 orders of magnitude. We also derive limits on the previously unconstrained linear and quadratic interactions of $ϕ$ with the massive vector bosons from measurements of the primordial $^4$He abundance.

astro-ph.CO↗

Comment on "Axion induced oscillating electric dipole moments"

In the recent work [Phys. Rev. D 91, 111702(R) (2015)], C. Hill concludes that the axion electromagnetic anomaly induces an oscillating electron electric dipole moment of frequency $m_a$ and strength $\sim 10^{-32}~e$ cm, in the limit $v/c \to 0$ for the axion field. Here, we demonstrate that a proper treatment of this problem in the lowest order yields $\textit{no}$ electric dipole moment of the electron in the same limit. Instead, oscillating electric dipole moments of atoms and molecules are produced by different mechanisms.

hep-ph↗

A possible resonance mechanism of earthquakes

It had been observed by Linkov, Petrova and Osipov (1992) that there exist periodic 4-6 hours pulses of 200 microHz seismogravitational oscillations ( SGO ) before 95 % of powerful earthquakes. We explain this by beating between an oscillation eigenmode of a whole tectonic plate and a local eigenmode of an active zone. The beating transfers the oscillation energy from the remote zone of the tectonic plate to the active zone, triggering the earthquake. Oscillation frequencies of the plate and ones of the active zone are tuned to a resonance by an additional compression applied to the active zone due to collision of neighboring plates or the magma flow in the liquid underlay of the astenosphere ( the upper mantle). In the case when there are three or more SGO with incommensurable difference frequencies the SGO beating pattern looks quasi-random, thus masking the non-random nature of the beating process. Nevertheless, we are able to discuss a possibility of the short term earthquakes predictions based on an accurate monitoring of the beating dynamics.

physics.geo-ph↗

Effects of Lorentz Symmetry Violation in the Spectra of Rare-Earth Ions in a Crystal Field

We demonstrate that experiments measuring the transition energies of rare-earth ions doped in crystalline lattices are sensitive to violations of Local Lorentz Invariance and Einstein's Equivalence Principle. Using the crystal field of LaCl$_{3}$ as an example, we calculate the frame-dependent energy shifts of the transition frequencies between low-lying states of Ce$^{3+}$, Nd$^{3+}$, and Er$^{3+}$ dopants in the context of the Standard Model Extension, and show that they have high sensitivity to electron anomalies that break rotational invariance.

hep-ph↗

Manifestations of dark matter and variations of fundamental constants in atoms and astrophysical phenomena

We present an overview of recent developments in the detection of light bosonic dark matter, including axion, pseudoscalar axion-like and scalar dark matter, which form either a coherently oscillating classical field or topological defects (solitons). We emphasise new high-precision laboratory and astrophysical measurements, in which the sought effects are linear in the underlying interaction strength between dark matter and ordinary matter, in contrast to traditional detection schemes for dark matter, where the effects are quadratic or higher order in the underlying interaction parameters and are extremely small. New terrestrial experiments include measurements with atomic clocks, spectroscopy, atomic and solid-state magnetometry, torsion pendula, ultracold neutrons, and laser interferometry. New astrophysical observations include pulsar timing, cosmic radiation lensing, Big Bang nucleosynthesis and cosmic microwave background measurements. We also discuss various recently proposed mechanisms for the induction of slow `drifts', oscillating variations and transient-in-time variations of the fundamental constants of Nature by dark matter, which offer a more natural means of producing a cosmological evolution of the fundamental constants compared with traditional dark energy-type theories, which invoke a (nearly) massless underlying field. Thus, measurements of variation of the fundamental constants gives us a new tool in dark matter searches.

physics.atom-ph↗

Actinide ions for testing the spatial $α-$variation hypothesis

Testing the spatial variation of fine-structure constant $α$ indicated in [Webb et al., Phys. Rev. Lett. 107, 191101 (2011)] with terrestrial laboratory atomic measurements requires at least $\dotα/α\sim 10^{-19}~\textrm{y}^{-1}$ sensitivity. We conduct a systematic search of atomic systems for such a test that have all features of the best optical clock transitions leading to possibility of the frequency measurements with fractional accuracy on the level of $10^{-18}$ or better and have a factor of 100 extra enhancement of $α$-variation in comparisons to experimental frequency ratio measurement accuracy. We identify the pair of actinide Cf$^{15+}$ and Es$^{16+}$ ions as the best system for a test of spatial $α-$variation hypothesis as it satisfies both of these requirements and have sufficiently simple electronic structure to allow for high-precision predictions of all atomic properties required for rapid experimental progress.

physics.atom-ph↗