A laboratory search for variation of the fine-structure constant using atomic dysprosium

Cingöz, A.; Leefer, N.; Ferrell, S. J.; Lapierre, A.; Nguyen, Angela-Maithy; Yashchuk, Valeriy V.; Budker, Dmitry; Lamoreaux, S. K.; Torgerson, J. R.

doi:10.1140/epjst/e2008-00810-0

Cited by 7 publications

(8 citation statements)

References 30 publications

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“…Yb + is an excellent system for benchmark tests of new theoretical approaches capable of describing strong electron correlations. A development of such new approaches is also needed to improve theoretical description of complex atoms, such as Dy or Ho, which is becoming more important owing to recent experimental developments and new proposals with these systems [17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Correlation effects in Yb+and implications for parity violation

2012

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Calculation of the energies, magnetic dipole hyperfine structure constants, E1 transition amplitudes between the low-lying states, and nuclear spin-dependent parity-nonconserving amplitudes for the 2 S 1/2 -2 D 3/2,5/2 transitions in 171 Yb + ion is performed using two different approaches. First, we carried out many-body perturbation theory calculation considering Yb + as a monovalent system. Additional all-order calculations are carried out for selected properties. Second, we carried out configuration interaction calculation considering Yb as a 15-electron system and compared the results obtained by two methods. The accuracy of different methods is evaluated. We find that the monovalent description is inadequate for evaluation of some atomic properties due to significant mixing of the one-particle and the hole-two-particle configurations. Performing the calculation by such different approaches allowed us to establish the importance of various correlation effects for Yb + atomic properties for future improvement of theoretical precision in this complicated system.

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Section: Introductionmentioning

confidence: 99%

Correlation effects in Yb+and implications for parity violation

2012

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“…2, and more details can be found in Refs. [42,43]. The optimal statistical precision is σ ν = γ/(2π Ṅ τ ), where γ/(2π) ≈ 20 kHz is the natural linewidth of the transition (see bottom panel of Fig.…”

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Search for Ultralight Scalar Dark Matter with Atomic Spectroscopy

Tilburg¹,

Leefer²,

Bougas³

et al. 2015

Phys. Rev. Lett.

238

284

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We report new limits on ultralight scalar dark matter (DM) with dilaton-like couplings to photons that can induce oscillations in the fine-structure constant α. Atomic dysprosium exhibits an electronic structure with two nearly degenerate levels whose energy splitting is sensitive to changes in α. Spectroscopy data for two isotopes of dysprosium over a two-year span is analyzed for coherent oscillations with angular frequencies below 1 rad s −1 . No signal consistent with a DM coupling is identified, leading to new constraints on dilaton-like photon couplings over a wide mass range. Under the assumption that the scalar field comprises all of the DM, our limits on the coupling exceed those from equivalence-principle tests by up to 4 orders of magnitude for masses below 3 · 10 −18 eV. Excess oscillatory power, inconsistent with fine-structure variation, is detected in a control channel, and is likely due to a systematic effect. Our atomic spectroscopy limits on DM are the first of their kind, and leave substantial room for improvement with state-of-the-art atomic clocks.Dark matter (DM) makes up the majority of matter density in our Universe. Its ubiquitous abundance can be measured through its gravitational influence, but little is known about the microphysical properties of the DM particle(s), such as the mass, spin, and any nongravitational interactions. If the DM is bosonic rather than fermionic, it can have a sub-eV mass and such high occupation numbers that it acts more like a classical wavewith frequency equal to its mass-than a particle. Light bosonic dark matter has a natural production mechanism, namely early-universe misalignment of the field relative to the minimum of its potential [1][2][3]. Several motivated candidates in this category exist in the literature, most notably the QCD axion [4-6] and other axion-like particles, which, as parity-odd pseudo-Nambu-Goldstone bosons (PNGBs) of compact symmetry groups, primarily have derivative interactions with matter [7]. Light, parity-even bosons may also arise as PNGBs of noncompact groups such as those of scale, conformal, or shift symmetries, the most famous examples of which are dilatons [8][9][10]. Small explicit breakings of these symmetries may induce nonderivative operators for the scalar fields, such as mass terms and higher-dimensional operators coupling them to matter.We focus on ultralight scalar fields φ with couplings to the (square of the) electromagnetic field tensor F µν :where κ ≡ √ 4πG N , G N is Newton's constant, and e ≈ 0.303 is the electromagnetic gauge coupling (we use units in which = c = 1). The interaction is normalized such that d e = 1 yields an attractive force of gravitational strength between electromagnetic energy densities at distances smaller than the inverse mass (r m and naturalness considerations together suggest a minimum mass-squared for φ. However, given the existing hierarchy problems of the Standard Model, we remain agnostic to this issue and consider the full m φ -d e parameter space (see Ref.[13] for more discuss...

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“…Due to an extremely small energy interval between these states, many effects relevant to new physics are strongly enhanced [18][19][20]. The transition between these states was used to study parity non-conservation [21], time variation of the fine structure constant [2,7,17], LLI and EEP violation [2,6], and search for dark matter [22]. The latest study of the coupling of the variation of the fine structure constant to gravity reveals [17] …”

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Limits on gravitational Einstein equivalence principle violation from monitoring atomic clock frequencies during a year

Dzuba

Flambaum

2017

Phys. Rev. D

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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 c00 = (3.0 ± 5.7) × 10 −7 and the parameter for the gravity-related variation of the fine structure constant κα = (−5.3 ± 10) × 10 −8 . where c 00 is the parameter characterising the magnitude of EEP violation, U is the gravitation potential, c is the speed of light, p is the operator of the electron momentum (p = −ih∇). The change of the frequency of atomic transition between states a and b between two dates in the year isTo avoid any confusion with the sign let us assume that state a is always above state b on the energy scale so that hω ab = E a −E b > 0. ∆U in (2) is the change of the Sun's gravitation potential due to changing of the Earth-Sun distance,2m a is the expectation value of the kinetic energy of electrons in state a, and δK ab is the difference between the kinetic energies of the states a and b. The maximal change of the gravitation potential is between January and July, ∆U/c 2 ≈ 3.3 × 10 −10 [5, 6]. Therefore, comparing accurate frequency measurements performed in January and July, or fitting several measurements with a cosine function with the zero phase in the beginning of January and with period of one year, one can put constrains on the parameter c 00 ,Measuring atomic frequency means comparing it to some reference frequency, e.g. caesium primary frequency standard or another microwave or optical reference frequency. Therefore, we need to consider a ratio of two frequencies. In the non-relativistic limit one can use the Virial theorem ( p 2 /2m = −E total ) and obtain from Eq. (2)i.e. ∆ω/ω is the same for all electron transitions (except for the hyperfine transitions where the splitting is due to the "relativistic" magnetic interaction). This means that in the non-relativistic limit the effect in the ratio of optical frequencies is unobservable. Therefore, we should perform relativistic calculations. It is convenient to introduce relativistic factors R which describe deviation of the expectation value of the kinetic energy from the value, given by the Virial theorem,Here ∆E a is the energy shift of the state a due to the kinetic energy operator. In the non-relativistic limit R = 1. In the relativistic case R can be larger or smaller than one and can even be negative. For the relative change of two frequencies we now haveIt is clear from (6) that for higher sensitivity one should compar...

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A laboratory search for variation of the fine-structure constant using atomic dysprosium

Cited by 7 publications

References 30 publications

Correlation effects in Yb+and implications for parity violation

Correlation effects in Yb+and implications for parity violation

Search for Ultralight Scalar Dark Matter with Atomic Spectroscopy

Limits on gravitational Einstein equivalence principle violation from monitoring atomic clock frequencies during a year

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