Time variability of α from realistic models of Oklo reactors

Gould, C. R.; Sharapov, E.I.; Lamoreaux, S. K.

doi:10.1103/physrevc.74.024607

Cited by 87 publications

(131 citation statements)

References 22 publications

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“…[8], where a variation was reported. However, a recent full Monte Carlo simulation of the reactor [9] reports a result consistent with no variation at the level of 1.2 × 10 −17 /yr.…”

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confidence: 97%

Limit on the Temporal Variation of the Fine-Structure Constant Using Atomic Dysprosium

et al. 2007

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Over a period of eight months, we have monitored transition frequencies between nearly degenerate, opposite-parity levels in two isotopes of atomic dysprosium (Dy). These transition frequencies are highly sensitive to temporal variation of the fine-structure constant (α) due to relativistic corrections of large and opposite sign for the opposite-parity levels. In this unique system, in contrast to atomic-clock comparisons, the difference of the electronic energies of the opposite-parity levels can be monitored directly utilizing a radio-frequency (rf) electric-dipole transition between them. Our measurements show that the frequency variation of the 3.1-MHz transition in 163 Dy and the 235-MHz transition in 162 Dy are 9.0±6.7 Hz/yr and -0.6±6.5 Hz/yr, respectively. These results provide a value for the rate of fractional variation of α of (−2.7 ± 2.6) × 10 −15 yr −1 (1 σ) without any assumptions on the constancy of other fundamental constants, indicating absence of significant variation at the present level of sensitivity.

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“…[8], where a variation was reported. However, a recent full Monte Carlo simulation of the reactor [9] reports a result consistent with no variation at the level of 1.2 × 10 −17 /yr.…”

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confidence: 97%

Limit on the Temporal Variation of the Fine-Structure Constant Using Atomic Dysprosium

et al. 2007

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“…Most of these methods, both in the laboratory and at cosmological distances, have been sensitive to changes in the fine structure constant α (e.g. Webb et al 2001;Peik et al 2004;Gould et al 2006;Rosenband et al 2008; Molaro et al 2013). However, fractional ⋆ E-mail: nkanekar@ncra.tifr.res.in; Swarnajayanti Fellow changes in µ are expected to be far larger than those in α in most theoretical scenarios, by factors of 10−500 (e.g.…”

Section: Introductionmentioning

confidence: 99%

Constraints on changes in the proton–electron mass ratio using methanol lines

Kanekar

Ubachs

Menten

et al. 2015

Monthly Notices of the Royal Astronomical Society: Letters

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We report Karl G. Jansky Very Large Array (VLA) absorption spectroscopy in four methanol (CH 3 OH) lines in the z = 0.88582 gravitational lens towards PKS1830−211. Three of the four lines have very different sensitivity coefficients K µ to changes in the proton-electron mass ratio µ; a comparison between the line redshifts thus allows us to test for temporal evolution in µ. We obtain a stringent statistical constraint on changes in µ by comparing the redshifted 12.179 GHz and 60.531 GHz lines, [∆µ/µ] 1.1 × 10 −7 (2σ) over 0 < z 0.88582, a factor of ≈ 2.5 more sensitive than the best earlier results. However, the higher signal-to-noise ratio (by a factor of ≈ 2) of the VLA spectrum in the 12.179 GHz transition also indicates that this line has a different shape from that of the other three CH 3 OH lines (at > 4σ significance). The sensitivity of the above result, and that of all earlier CH 3 OH studies, is thus likely to be limited by unknown systematic errors, probably arising due to the frequency-dependent structure of PKS1830−211. A robust result is obtained by combining the three lines at similar frequencies, 48.372, 48.377 and 60.531 GHz, whose line profiles are found to be in good agreement. This yields the 2σ constraint [∆µ/µ] 4 × 10 −7 , the most stringent current constraint on changes in µ. We thus find no evidence for changes in the proton-electron mass ratio over a lookback time of ≈ 7.5 Gyrs.

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“…Assuming possible changes only in the electromagnetic coupling constant, Gould et al (2006) has obtained a model dependent constraint on |Δα/α| < 2 × 10 −8 . However, when the strength of the strong interaction -the parameter Λ QCD -is also considered to be variable, the Oklo data does not provide any bound on the variation of α (Flambaum & Shuryak 2002;Chin et al 2009).…”

Section: Introductionmentioning

confidence: 99%

Searching for spatial variations ofα²/μin the Milky Way

Levshakov

Molaro²,

Reimers

2010

A&A

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Aims. We probe the dependence of α 2 /μ on the ambient matter density by means of spectral observations in submm-and mm-wave bands. Methods. A procedure is suggested for exploring the value of F = α 2 /μ, where μ = m e /m p is the electron-to-proton mass ratio, and α = e 2 /( c) is the fine-structure constant. The fundamental physical constants, which are measured in different physical environments of high (terrestrial) and low (interstellar) densities of baryonic matter are supposed to vary in chameleon-like scalar field models, which predict that both masses and coupling constant may depend on the local matter density. The parameter ΔF/F = (F obs − F lab )/F lab can be estimated from the radial velocity offset, ΔV = V rot − V fs , between the low-laying rotational transitions in carbon monoxide 13 CO and the fine-structure transitions in atomic carbon [C i]. A model-dependent constraint on Δα/α can be obtained from ΔF/F using Δμ/μ independently measured from the ammonia method. Results. Currently available radio astronomical datasets provide an upper limit on |ΔV| < 110 m s −1 (1σ). When interpreted in terms of the spatial variation of F, this gives |ΔF/F| < 3.7 × 10 −7 . An order of magnitude improvement in this limit will allow us to independently test a non-zero value of Δμ/μ = (2.2 ± 0.4 stat ± 0.3 sys ) × 10 −8 , recently found with the ammonia method. Considering that the ammonia method restricts the spatial variation of μ at the level of |Δμ/μ| ≤ 3 × 10 −8 and assuming that ΔF/F is the same in the entire interstellar medium, one obtains that the spatial variation of α does not exceed the value |Δα/α| < 2 × 10 −7 . Since extragalactic gas clouds have similar densities to those in the interstellar medium, the bound on Δα/α is also expected to be less than 2 × 10 −7 at high redshift if no significant temporal dependence of α is present.

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Time variability of α from realistic models of Oklo reactors

Cited by 87 publications

References 22 publications

Limit on the Temporal Variation of the Fine-Structure Constant Using Atomic Dysprosium

Limit on the Temporal Variation of the Fine-Structure Constant Using Atomic Dysprosium

Constraints on changes in the proton–electron mass ratio using methanol lines

Searching for spatial variations ofα²/μin the Milky Way

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Time variability of α from realistic models of Oklo reactors

Cited by 87 publications

References 22 publications

Limit on the Temporal Variation of the Fine-Structure Constant Using Atomic Dysprosium

Limit on the Temporal Variation of the Fine-Structure Constant Using Atomic Dysprosium

Constraints on changes in the proton–electron mass ratio using methanol lines

Searching for spatial variations ofα2/μin the Milky Way

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Searching for spatial variations ofα²/μin the Milky Way