Variation Of Fine-structure Constant Research Articles

JWST observations constrain the time evolution of fine structure constants and dark energy-electromagnetic coupling

Abstract It was hypothesized in the literature that some physical parameters may be time-evolving and the astrophysical data can serve as a probe. Recently, James Webb Space Telescope (JWST) have released its early observations. In this work, we select the JWST spectroscopic observations of the high redshift ($z>7.1$) galaxies with strong [\ion{O}{III}] ($\lambda=4959$\AA \,and $5007$\AA \,in the rest frame) emission lines to constraint the evolution of the fine structure constant ($\alpha$). With the spectra from two galaxies at redshifts of $7.19$ and $8.47$, the deviation of $\alpha$ to its fiducial value is found to be as small as $0.44^{+8.4+1.7}_{-8.3-1.7} \times 10^{-4}$ and $-10.0^{+18+1.5}_{-18-1.5} \times 10^{-4}$, respectively (the first error is statistical and the latter is systematic). The combination of our results with the previous data reveals that $\frac{1}{\alpha} \frac{d \alpha}{dt} = 0.30^{+4.5}_{-4.5} \times 10^{-17}~{\rm yr^{-1}}$. Clearly, there is no evidence for a cosmic evolution of $\alpha$. The prospect of further constraining the time evolution of $\alpha$ is also discussed. The scalar field of dark energy is hypothesized to drive the acceleration of the universe's expansion through an interaction with the electromagnetic field. By integrating the observational data of the fine-structure constant variation, $\frac{\Delta\alpha}{\alpha}(z)$, we have established a stringent upper limit on the coupling strength between dark energy and electromagnetism. Our analysis yields $\zeta \leq 3.92 \times 10^{-7}$ at the 95\% confidence level, representing the most stringent bound to date.

High-accuracy optical clocks with sensitivity to the fine-structure constant variation based on Sm[formula omitted]

We identify two metastable excited states in Sm10+ highly charged ion as candidates for high accuracy optical clocks. Several atomic properties relevant to optical clock development are calculated using relativistic many-body methods. This includes energy levels, transition amplitudes, lifetimes, scalar polarizabilities, black body radiation shift, and the sensitivity to the fine structure constant variation. We found that the clock transitions are not sensitive to perturbation, e.g., relative black body radiation shifts are ∼10−19. The enhancement factor for the α variation is ∼ 0.8 for one clock transition and ∼ 16 for another.

Cosmologically varying kinetic mixing

The portal connecting the invisible and visible sectors is one of the most natural explanations of the dark world. However, the early-time dark matter production via the portal faces extremely stringent late-time constraints. To solve such tension, we construct the scalar-controlled kinetic mixing varying with the ultralight CP-even scalar’s cosmological evolution. To realize this and eliminate the constant mixing, we couple the ultralight scalar within 10−33eV ≲ m0 ≪ eV with the heavy doubly charged messengers and impose the ℤ2 symmetry under the dark charge conjugation. Via the varying mixing, the keV – MeV dark photon dark matter is produced through the early-time freeze-in when the scalar is misaligned from the origin and free from the late-time exclusions when the scalar does the damped oscillation and dynamically sets the kinetic mixing. We also find that the scalar-photon coupling emerges from the underlying physics, which changes the cosmological history and provides the experimental targets based on the fine-structure constant variation and the equivalence principle violation. To ensure the scalar naturalness, we discretely re-establish the broken shift symmetry by embedding the minimal model into the ℤN-protected model. When N ~ 10, the scalar’s mass quantum correction can be suppressed much below 10−33eV.

A Comparison of Distant and Nearby Solar Twins

Properties of solar twins at kiloparsec distances from the local standard of rest are compared to solar twins within 100 pc of the Sun. They have a velocity distribution closely similar to that of the nearby twins in addition to closely matching T eff, and [Fe/H]. The new twins are a kpc distant from Earth, and closer to the Galactic center. Additionally, they may be significantly older than nearby twins, and thus are useful for spectroscopic comparison with solar twins, in the search for fine structure constant variation.

Highly charged ion (HCI) clocks: Frontier candidates for testing variation of fine-structure constant

Attempts are made to unify gravity with the other three fundamental forces of nature. As suggested by higher dimensional models, this unification may require space and time variation of some of the dimensionless fundamental constants. In this scenario, probing temporal variation of the electromagnetic fine structure constant (α=e2ℏc) in a low energy regime at the cosmological time scale is of immense interest. Atomic clocks are ideal candidates for probing α variation because their transition frequencies are measured with ultra-high precision. Since atomic transition frequency is a function of α, measurement of a clock frequency at different temporal and spatial locations can yield signatures to ascertain variation of α. Highly charged ions (HCIs) are very sensitive to variation of α and are least affected by external perturbations, making them excellent platforms for searching for temporal variation of α. In this work, we overview HCIs suitable for building atomic clocks because of their spectroscopic features and sensitivity to variation of α. The selection of HCI clock candidates is outlined based on two general rules—by analyzing trends in fine structure splitting and level-crossing patterns along a series of isoelectronic atomic systems of the periodic table. Two variants of relativistic many-body methods in the configuration interaction and coupled-cluster theory frameworks are employed to determine the properties of HCIs proposed for atomic clocks. These methods treat electronic correlation and relativistic effects under the frame of the Dirac-Coulomb Hamiltonian rigorously, while other higher-order relativistic effects are included approximately. Typical systematic effects of the HCI clock frequency measurements are discussed using the calculated atomic properties. This review will help understand limits and potentials of the proposed HCIs as the prospective atomic clock candidates and guide future HCI clock experiments.

Testing the violation of the equivalence principle in the electromagnetic sector and its consequences in f(T) gravity

A violation of the distance-duality relation is directly linked with a temporal variation of the electromagnetic fine-structure constant. We consider a number of well-studied f(T) gravity models and we revise the theoretical prediction of their corresponding induced violation of the distance-duality relationship. We further extract constraints on the involved model parameters through fine-structure constant variation data, alongside with supernovae data, and Hubble parameter measurements. Moreover, we constrain the evolution of the effective f(T) gravitational constant. Finally, we compare with revised constraints on the phenomenological parametrisations of the violation of the equivalence principle in the electromagnetic sector.

Stringent limit on space-time variation of fine-structure constant using high-resolution of quasar spectra

We have obtained a new limit on the space-time variation of the fine-structure constant(α=e24πε0ℏc)using the observations of Mg II line in quasar J110325-264515 spectra with redshiftzabs=1.8389. The obtained parameter isΔα/α=(−0.155±0.728)×10−6. It was derived from the comparison between the quasar J110325-264515 spectra and the laboratory sample spectra. The obtained result appears as a new highly sensitive probe of the cosmological variability of the fine-structure constant. From the relative spectra of the Mg II, we found the most stringent constraint up today onΔα/αcomparing to the previously published results.

Variation of the fine-structure constant caused by expansion of the Universe

In this paper, we evaluate the fine-structure constant variation that should take place as the pseudo-Riemannian Universe expands and its curvature is changed adiabatically. Such variation of the fine-structure constant is attributed to an energy loss by an extended physical system (consisting of baryonic component and electromagnetic (EM) field) due to expansion of our Universe. Obtained ratio [Formula: see text] (per second) is only five times smaller than actually reported experimental limit on this value. For this reason, the obtained variation can probably be measured within a couple of years. To argue the correctness of our approach, we calculate the Planck constant as adiabatic invariant of the EM field propagated on the pseudo-Riemannian manifold characterized by slowly varied geometry. Finally, we discuss the double clock experiment based on Al[Formula: see text] and Hg[Formula: see text] clocks carried out by Rosenband et al. (Science 2008). We show that in this case (when the fine-structure constant is changed adiabatically), the method based on double clock experiment cannot be applied to measure the fine-structure constant variation.

Constraining the magnetic field on white dwarf surfaces; Zeeman effects and fine structure constant variation

ABSTRACT White dwarf (WD) atmospheres are subjected to gravitational potentials around 105 times larger than occur on Earth. They provide a unique environment in which to search for any possible variation in fundamental physics in the presence of strong gravitational fields. However, a sufficiently strong magnetic field will alter absorption line profiles and introduce additional uncertainties in measurements of the fine structure constant. Estimating the magnetic field strength is thus essential in this context. Here, we model the absorption profiles of a large number of atomic transitions in the WD photosphere, including first-order Zeeman effects in the line profiles, varying the magnetic field as a free parameter. We apply the method to a high signal-to-noise, high-resolution, far-ultraviolet Hubble Space Telescope/Space Telescope Imaging Spectrograph spectrum of the WD G191−B2B. The method yields a sensitive upper limit on its magnetic field of B < 2300 G at the 3σ level. Using this upper limit, we find that the potential impact of quadratic Zeeman shifts on measurements of the fine structure constant in G191−B2B is 4 orders of magnitude below laboratory wavelength uncertainties.

Testing the variation of the fine structure constant with strongly lensed gravitational waves**Supported by the National Natural Science Fund of China (11775038, 11603005, 11647307)

The possible variation of the electromagnetic fine structure constant, αe, at cosmological scales has aroused great interest in recent years. Strongly lensed gravitational waves (GWs) and their electromagnetic counterparts could be used to test this variation. Under the assumption that the speed of a photon can be modified, whereas the speed of a GW is the same as predicted by general relativity, and they both propagate in a flat Friedman-Robertson-Walker universe, we investigated the difference in time delays of the images and derived the upper bound of the variation of αe. For a typical lensing system in the standard cosmological models, we obtained Bcosθ⩽1.85 × 10−5, where B is the dipolar amplitude and θ is the angle between observation and the preferred direction. Our result is consistent with the most up-to-date observations on αe. In addition, the observations of strongly lensed GWs and their electromagnetic counterparts could be used to test which types of alternative theories of gravity can account for the variation of αe.

Constraint on the time variation of the fine-structure constant with the SDSS-III/BOSS DR12 quasar sample

From the Sloan Digital Sky Survey (SDSS) Data Release 12, which covers the full Baryonic Oscillation Spectroscopic Survey (BOSS) footprint, we investigate the possible variation of the fine-structure constant over cosmological time-scales. We analyse the largest quasar sample considered so far in the literature, which contains 13175 spectra (10363 from SDSS-III/BOSS DR12 + 2812 from SDSS-II DR7) with redshift $z<\,$1. We apply the emission-line method on the [O III] doublet (4960, 5008 A) and obtain $\Delta\alpha/\alpha= \left(0.9 \pm 1.8\right)\times10^{-5}$ for the relative variation of the fine-structure constant. We also investigate the possible sources of systematics: misidentification of the lines, sky OH lines, H$\,\beta$ and broad line contamination, Gaussian and Voigt fitting profiles, optimal wavelength range for the Gaussian fits, chosen polynomial order for the continuum spectrum, signal-to-noise ratio and good quality of the fits. The uncertainty of the measurement is dominated by the sky subtraction. The results presented in this work, being systematics limited, have sufficient statistics to constrain robustly the variation of the fine-structure constant in redshift bins ($\Delta z\approx$ 0.06) over the last 7.9 Gyr. In addition, we study the [Ne III] doublet (3870, 3969 A) present in 462 quasar spectra and discuss the systematic effects on using these emission lines to constrain the fine-structure constant variation. Better constraints on $\Delta\alpha/\alpha\ $ ($<$10$^{-6}$) using the emission-line method would be possible with high-resolution spectroscopy and large galaxy/qso surveys.

Identifications of and EUV transitions of promethium-like Pt, Ir, Os and Re

We investigated Pm-, Nd-, and Pr-like spectra in the extreme ultra-violet region around 20 nm of Pt, Ir, Os, and Re (Z = 78–75) produced in the Heidelberg electron beam ion trap. Identification of the transitions was supported by several theoretical calculations, including collisional radiative modeling of the observed spectra. Special attention is given to the identifications of the alkaline-like – resonance lines in promethium-like highly charged ions. Previous identifications of these lines have been tentative at best due to disagreements with theory and doubts about the experimental charge state identifications. Our experimental results for the – wavelengths are accurate at the 0.005%-level. Understanding the level-structure of ions near the – level crossing is of particular importance for future searches of a possible fine-structure constant variation, and new optical clocks.

Frequency ratios of Sr, Yb, and Hg based optical lattice clocks and their applications

This article describes the recent progress of optical lattice clocks with neutral strontium ( 87 Sr), ytterbium ( 171 Yb) and mercury ( 199 Hg) atoms. In particular, we present frequency comparison between the clocks locally via an optical frequency comb and between two Sr clocks at remote sites using a phase-stabilized fibre link. We first review cryogenic Sr optical lattice clocks that reduce the room-temperature blackbody radiation shift by two orders of magnitude and serve as a reference in the following clock comparisons. Similar physical properties of Sr and Yb atoms, such as transition wavelengths and vapour pressure, have allowed our development of a compatible clock for both species. A cryogenic Yb clock is evaluated by referencing a Sr clock. We also report on an Hg clock, which shows one order of magnitude less sensitivity to blackbody radiation, while its large nuclear charge makes the clock sensitive to the variation of fine-structure constant. Connecting all three types of clocks by an optical frequency comb, the ratios of the clock frequencies are determined with uncertainties smaller than possible through absolute frequency measurements. Finally, we describe a synchronous frequency comparison between two Sr-based remote clocks over a distance of 15 km between RIKEN and the University of Tokyo, as a step towards relativistic geodesy. Cet article décrit les progrès récents des horloges optiques à réseau avec des atomes neutres de strontium ( 87 Sr), ytterbium ( 171 Yb) et mercure ( 199 Hg). Nous présentons en particulier une comparaison locale des fréquences entre des horloges en utilisant un peigne de fréquences et entre deux horloges à Sr distantes à l'aide d'un lien fibré stabilisé en phase. Nous commençons par une revue des horloges optiques à Sr cryogéniques qui réduisent le décalage de fréquence dû au corps noir à température ambiante de deux ordres de grandeur et servent de référence dans les comparaisons d'horloges qui sont décrites ensuite. Les propriétés physiques similaires du Sr et Yb, telles que les longueurs d'onde de transition et les pressions de vapeur saturante, nous ont permis de développer une horloge compatible avec les deux espèces. Une horloge à Yb cryogénique est évaluée par référence à une horloge à Sr cryogénique. Nous décrivons aussi une horloge à mercure qui présente une sensibilité au rayonnement du corps noir à température ambiante dix fois plus faible, alliée à une charge nucléaire élevée qui rend l'horloge sensible aux variations de la constante de structure fine. En connectant les trois types d'horloges avec un peigne de fréquences optiques, les rapports de fréquences sont mesurés avec des incertitudes plus faibles que ce qui est possible avec des mesures de fréquences absolues. Finalement, nous décrivons une comparaison de fréquence synchrone entre deux horloges à Sr distantes de 15 km entre RIKEN et l'université de Tokyo, une étape vers la géodésie relativiste.

Varying alpha and cosmic acceleration in Brans-Dicke-BSBM theory: stability analysis and observational tests

By integration of generalized BSBM and Brans-Dicke cosmological models, in this article, we investigate the theoretical framework of fine structure constant variation and current cosmic acceleration. We first develop a mathematical formalism to analyse the stability of the model. By employing observational data to constrain the model parameters, phase space is performed and the attractor solutions of the model are detected. We then examine the model against observational data such as observational Hubble parameter dataset and quasar absorption spectra. The results confirm current universe acceleration and also predicts fine structure constant variation. Furthermore, extrapolation of the best fitted model in high redshift (z > 15) illustrates a significantly larger variation of fine structure constant in earlier epoch of the universe.

Fractal space time and variation of fine-structure constant

The effect of fractal space time of the quantum particles on the variation of the fine structure constant $\alpha$ has been studied. The variation of fine structure constant has been investigated around De Broglie length $\lambda$ and compton length $\lambda_{c}$ and it has been suggested that the variation may be attributed to the dimensional transition of the particle trajectories between these two quantum domains. Considering the Fractal universe with a small inhomogeneity in the mass distribution in the early universe, the variation of the fine structure constant have been investigated between matter and radiation dominated era. The fine structure constant shows a critical behaviour with critical exponent which is fractional and shows a discontinuity. It has been suggested that the variation of the fine structure constant may be attributed to the intrinsic scale dependance of the fundamental constants of nature.

Universe acceleration and fine structure constant variation in BSBM theory

In this work we investigate the utilityof using SNe Ia observations in constraining the cosmological parameters in BSBM theory where a scalar field is responsible for both fine structure constant variation and late time universe acceleration. The model is discussed in the presence of an exponential self potential for the scalar field. Stability and phase space analysis of the solutions are studied. The model is tested against observational data for Hubble parameter and quasar absorption spectra. With the best fitted model parameters, the theory predicts a good match with the experimental results and exhibits fine structure constant variation. The analysis also predicts the recent universe acceleration and possible phantom crossing in future.

Fine structure constant variation or spacetime anisotropy?

Recent observations on the quasar absorption spectra supply evidence for the variation of the fine structure constant α. In this paper, we propose another interpretation of the observational data on the quasar absorption spectra: a scenario with spacetime inhomogeneity and anisotropy. Maybe the spacetime is characterized by the Finsler geometry instead of the Riemann one. The Finsler geometry admits fewer symmetries than the Riemann geometry does. We investigate the Finslerian geodesic equations in the Randers spacetime (a special Finsler spacetime). It is found that the cosmological redshift in this spacetime deviates from the one in general relativity. The modification term to the redshift could be generally revealed as a monopole plus dipole function of spacetime locations and directions. We suggest that this modification corresponds to the spatial monopole and dipole of α variation in the quasar absorption spectra.

Constraining [formula omitted] theories with temporal variation of fine structure constant

It is well known that f(R) theories in Einstein frame is conformally equivalent to quintessence models in which the scalar field minimally couples with gravity. If there exists a matter system in Jordan frame, then it interacts with the scalar field in Einstein frame due to the conformal transformations. This interaction, in general, may lead to changes of fundamental constants. Here we will consider possible time variation of fine structure constant in a general f(R) theory. We will use observational bounds on these variations and argue that it provides a criterion for constraining f(R) models.

Transition frequency shifts with fine-structure constant variation for Yb II

In this paper we report calculations of the relativistic corrections to transition frequencies ($q$ factors) of Yb II for the transitions from the odd-parity states to the metastable state $4{f}^{13}6{s}^{2}\text{ }{^{2}F}_{7/2}^{o}$. These transitions are of particular interest experimentally since they possess some of the largest $q$ factors calculated to date and the ${^{2}F}_{7/2}^{o}$ state can be prepared with high efficiency. This makes Yb II a very attractive candidate for the laboratory search for variation in the fine-structure constant $\ensuremath{\alpha}$.

Transition frequency shifts with fine-structure constant variation for Fe I and isotope-shift calculations in Fe I and Fe II

In this paper we calculated the relativistic corrections to transition frequencies ($q$ factors) of Fe I for the transitions from the even- and odd-parity states to the ground state. We also carried out isotope-shift calculations in Fe I and Fe II.