Possible variations of the fine structure constant α and their metrological significance

Бронников, К. А.; Kononogov, S. A.

doi:10.1088/0026-1394/43/5/r01

Cited by 21 publications

(15 citation statements)

References 71 publications

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“…Various reviews have been written on this topic. We will refer to the review [495] as FVC and we mention the following later reviews [27,48,71,117,228,270,273,390,498,500] and we refer to Ref. [354] for the numerical values of the constants adopted in this review.…”

Section: Introductionmentioning

confidence: 99%

Varying Constants, Gravitation and Cosmology

Uzan

2011

Living Rev. Relativ.

752

784

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Fundamental constants are a cornerstone of our physical laws. Any constant varying in space and/or time would reflect the existence of an almost massless field that couples to matter. This will induce a violation of the universality of free fall. Thus, it is of utmost importance for our understanding of gravity and of the domain of validity of general relativity to test for their constancy. We detail the relations between the constants, the tests of the local position invariance and of the universality of free fall. We then review the main experimental and observational constraints that have been obtained from atomic clocks, the Oklo phenomenon, solar system observations, meteorite dating, quasar absorption spectra, stellar physics, pulsar timing, the cosmic microwave background and big bang nucleosynthesis. At each step we describe the basics of each system, its dependence with respect to the constants, the known systematic effects and the most recent constraints that have been obtained. We then describe the main theoretical frameworks in which the low-energy constants may actually be varying and we focus on the unification mechanisms and the relations between the variation of different constants. To finish, we discuss the more speculative possibility of understanding their numerical values and the apparent fine-tuning that they confront us with.

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Section: Introductionmentioning

confidence: 99%

Varying Constants, Gravitation and Cosmology

Uzan

2011

Living Rev. Relativ.

752

784

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“…The fine structure constant, α, and the Rydberg, Ry, are among the significant parameters [1][2][3][4]. Data are also available from the geological record [6][7][8][9] and from astronomy [5,10,11]. We present here the first experimental comparison of a molecular clock to an atomic clock, which gives a direct line to the proton-to-electron mass ratio.…”

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confidence: 99%

Stability of the Proton-to-Electron Mass Ratio

et al. 2008

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“…energy scale α variations do not directly relate with very slow time variations considered below (see, e.g., [17]). …”

Section: Accuracies Of Esm Constants At Different Energy Scalesmentioning

confidence: 98%

Constants of the extended Standard Model and a search for their temporal variations

2009

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1 Verification of time α variations is of primary importance, but it should be taken into account that α variations are connected with variations of other coupling constants and masses of fundamental particles. Accuracies of ESM constants at different energy scalesThe fine structure constant is the most employed coupling constant, which in the Gauss In QCD framework a dependence of α c =g c 2 /4π on a transferred momentum (g c is acoupling constant between color quarks and gluons) can be evaluated with the perturbation theory and a renormalization scheme thereafter can be tested experimentally for transferred momenta larger than a QCD scale constant Λ QCD ≡ Λ c . The Λ c value is about several hundredsMeVs and depends on a number of active quarks participating in a process [1,28,29]. The Eq.(2) for the "running" coupling constant take place in a gauge theory and in doing so in the QED: β 0 = -4/3, in the GWS theory: β 0 = 10/3, at n f = 6, in the QCD: β 0 = 7, at n f = 6. Another parameter Λ c is used in the QCD instead of µ: Λ c 2 = µ 2 exp(-4π/β 0 α c (µ 2 )).Hence the QED coupling constant α grows when Q 2 increases, while α w and α c diminish and The value of the electromagnetic coupling at low energies (the fine structure constant α or the Sommerfeld constant), at present is most accurately determined from the measurement of the electron anomalous magnetic moment a e [30] The α value increases still further when the energy grows and at the Z-boson mass scale is (with an accuracy ∼7.1⋅10Note that these α variations depending on an energy scale manifest themselves at energies which are higher then energies of atomic transitions, i.e. energy scale α variations do not directly relate with very slow time variations considered below (see, e.g., [17]).The accuracy of determination of SM physical observables is very high in measurements of lepton anomalous magnetic moments a l . As it noted above the α value has the highest precision from a e measurement data. Notice that there is the discrepancy between the predicted and experimental value of muon magnetic moments at the 3,4 σ level, that indicates possible a contribution of "new physics" effects [33]. Moreover there is the intriguing difference (∼ 3,2 σ) between the values of the effective Weinberg angle measured from lepton and hadron contributions: sin 2 (θ eff ) l =0.23113(21), sin 2 (θ eff ) h =0.23222(27) [33].It is known, that quark masses cannot be measured in free states or any macroscopic external field, they have not classical limits unlike, for example, the electron mass [34]. In the QCD one cannot put a quark mass value at some "natural", "physical" scale. Quark masses are not uniquely defined, they depend on a renormalization scheme and their values m(µ) are governed by the following equation [1, 5]:where γ is an anomalous dimension, that is known in the perturbation theory up to fourth order, for instance, When momentum values are of order of magnitude Λ c , it is necessary to take into account nonperturbative contributions, which are dominating at ...

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Possible variations of the fine structure constant α and their metrological significance

Cited by 21 publications

References 71 publications

Varying Constants, Gravitation and Cosmology

Varying Constants, Gravitation and Cosmology

Stability of the Proton-to-Electron Mass Ratio

Constants of the extended Standard Model and a search for their temporal variations

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