Fine Structure Constant Research Articles

Molecular Collapse States in Graphene/WSe_{2} Heterostructure Quantum Dots.

In relativistic physics, both atomic collapse in a heavy nucleus and Hawking radiation in a black hole are predicted to occur through the Klein tunneling process that couples particles and antiparticles. Recently, atomic collapse states (ACSs) were explicitly realized in graphene because of its relativistic Dirac excitation with a large "fine structure constant." However, the essential role of the Klein tunneling in the ACSs remains elusive in experiment. Here we systematically study the quasibound states in elliptical graphene quantum dots (GQDs) and two coupled circular GQDs. Bonding and antibonding molecular collapse states formed by two coupled ACSs are observed in both systems. Our experiments supported by theoretical calculations indicate that the antibonding state of the ACSs will change into a Klein-tunneling-induced quasibound state revealing deep connection between the ACSs and the Klein tunneling.

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.

Survey for Distant Solar Twins (SDST) – III. Identification of new solar twin and solar analogue stars

ABSTRACT The Survey for Distant Solar Twins aims to find stars very similar to the Sun at distances of 1–$4\, {\rm kpc}$, several times more distant than any currently known solar twins and analogues. The goal is to identify the best stars with which to test whether the fine-structure constant, α, varies with dark matter density in our Galaxy. Here, we use epic, our line-by-line differential technique, to measure the stellar parameters – effective temperature Teff, surface gravity log g, and metallicity [Fe/H] – from moderate-resolution (R ≲ 32 000) spectra of 877 solar twin and analogue candidates (547 at 1–$4\, {\rm kpc}$) observed with the High Efficiency and Resolution Multi-Element Spectrograph (HERMES) on the Anglo-Australian Telescope. These are consistent with expectations for Teff and log g from photometry, and for [Fe/H] from the Besançon stellar population model. epic provides small enough uncertainties ($\sim 90\, {\rm K}$, $0.08\, {\rm dex}$, and $0.05\, {\rm dex}$, respectively), even at the low signal-to-noise ratios available (${\rm S/N}\gtrsim$ 25 per pixel), to identify 299 new solar analogues ($\ge 90~{{\ \rm per\ cent}}$ confidence) and 20 solar twins (≥50 per cent confidence), 206 and 12 of which are at 1–$4\, {\rm kpc}$. By extending epic to measure line broadening and lithium abundance from HERMES spectra, and with ages derived from isochrone fitting with our stellar parameters, we identify 174 solar analogues at 1–$4\, {\rm kpc}$ that are relatively inactive, slowly rotating, and with no evidence of spectroscopic binarity. These are the preferred targets for follow-up spectroscopy to measure α.

Measurement quantization

We present principles of Measurement Quantization (MQ) and approaches to measurement that support the discreteness of measure. Several claims are addressed. Notably, that measure is discrete with respect to the internal frame, non-discrete with respect to the system frame and that length is contracted due to the discreteness of measure. We address the relation of angular measure to momentum, the physical significance of count bounds and that the fundamental measures — more precise expressions for Planck’s units — are an emergent property of the internal frame. Quantum experiments by Shwartz, et. al and CODATA provide physical support. We predict and derive values for elementary charge and the gravitational, Hubble, reduced Planck, electric, magnetic, Coulomb, and fine structure constants. We then correlate gravity with electromagnetism (unification). We present expressions for galactic rotation, dark matter, dark energy, and accelerating expansion. MQ advances over Loop Quantum Gravity with two frames, the difference which leads to the physical constants and the laws of nature. We correlate the quantum and cosmological, describing an inflation free quantum epoch, why it ceases and expansion. Therein are solutions to the horizon problem and homogenous, isotropic properties of the universe. Predictions include length contraction unrelated to special or general relativity (SR/GR), 13-digit measures of the gravitational constant, the Planck momentum, and universal mass accretion. A calculation of CMB age, quantity, present-day density and temperature provides additional support. Also offered, discrete solutions to the size and age of the universe, ground state orbital, SR, GR, and equivalence.

Casimir Self-Interaction Energy Density of Quantum Electrodynamic Fields.

Quantum electrodynamic fields possess fluctuations corresponding to transient particle-antiparticle dipoles, which can be characterized by a nonvanishing polarizability density. Here, we extend a recently proposed quantum scaling law to describe the volumetric and radial polarizability density of a quantum field corresponding to electrons and positrons and derive the Casimir self-interaction energy (SIE) density of the field, E[over ¯]_{SIE}, in terms of the fine-structure constant. The proposed model obeys the cosmological equation of state w=-1 and the magnitude of the calculated E[over ¯]_{SIE} lies in between the two recent measurements of the cosmological constant Λ obtained by the Planck Mission and the Hubble Space Telescope.

Dynamical effects from anomalies: Modified electrodynamics in Weyl semimetals

We discuss the modified quantum electrodynamics from a time-reversal-breaking Weyl semimetal coupled with a $U(1)$ gauge (electromagnetic) field. A key role is played by the soft dispersion of the photons in a particular direction, say $\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{z}$, due to the Hall conductivity of the Weyl semimetal. Due to the soft photon, the fermion velocity in $\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{z}$ is logarithmically reduced under renormalization group flow, together with the fine-structure constant. Meanwhile, fermions acquire a finite lifetime from spontaneous emission of the soft photon, namely, the Cherenkov radiation. At low-energy $E$, the inverse of the fermion lifetime scales as ${\ensuremath{\tau}}^{\ensuremath{-}1}\ensuremath{\sim}E/\mathrm{PolyLog}(E)$. Therefore, even though fermion quasiparticles are eventually well-defined at very low energy, over a wide intermediate energy window the Weyl semimetal behaves like a marginal Fermi liquid. Phenomenologically, our results are more relevant for emergent Weyl semimetals, where the fermions and photons all emerge from strongly correlated lattice systems. Possible experimental implications are discussed.

An Electron Model Based on the Fine Structure Constant

In previous publications, the author has proposed a model of the electron’s internal structure, wherein a positively-charged negative mass outer shell and a negatively-charged positive mass central core are proposed to resolve the electron’s charge and mass inconsistencies. That model is modified in this document by assuming the electron’s radius is exactly equal to the classical electron radius. The attributes of the internal components of the electron’s structure have been recalculated accordingly. The shape of the electron is also predicted, and found to be slightly aspherical on the order of an oblate ellipsoid. This shape is attributed to centrifugal force and compliant outer shell material. It is interesting to note that all of the electron’s attributes, both external and internal, with the exception of mass and angular moment, are functions of the fine structure constant a, and can be calculated from just three additional constants: electron mass, Planck’s constant, and speed of light. In particular, the ratios of the outer shell charge and mass to the electron charge and mass, respectively, are 3/2a. The ratios of the central core charge and mass to the electron charge and mass, respectively, are 1-(3/2a). Attributes of the electron are compared with those of the muon. Charge and spin angular momentum are the same, while mass, magnetic moment, and radius appear to be related by the fine structure constant. The mass of the electron outer shell is nearly equal to the mass of the muon. The muon internal structure can be modeled exactly the same as for the electron, with exactly the same attribute relationships.

Formation of hot spots around small primordial black holes

In this paper, we investigate the thermalization of Hawking radiation from primordial black holes (PBHs) in the early Universe, taking into account the interference effect on thermalization of high energy particles, known as Landau-Pomeranchuk-Migdal (LPM) effect. Small PBHs with masses ≲ 109 g completely evaporate before the big bang nucleosynthesis (BBN). The Hawking radiation emitted from these PBHs heats up the ambient plasma with temperature lower than the Hawking temperature, which results in a non-trivial temperature profile around the PBHs, namely a hot spot surrounding a PBH with a broken power-law tail. We find that the hot spot has a core with a radius much larger than the black hole horizon and its highest temperature is independent of the initial mass of the PBH such as 2 × 109 GeV × (α/0.1)19/3, where α generically represents the fine-structure constants. We also briefly discuss the implications of the existence of the hot spot for phenomenology.

A Fine-Structure Constant Can Be Explained Using the Electrochemical Method

We proposed an empirical equation for a fine-structure constant: . Then, . where mp and me are the rest mass of a proton and the rest mass of an electron, respectively. In this report, using the electrochemical method, we proposed an equivalent circuit. Then, we proposed a refined version of our own old empirical equations about the electromagnetic force and gravity. Regarding the factors of 9/2 and π, we used 3.132011447 and 4.488519503, respectively. The calculated values of Tc and G are 2.726312 K and 6.673778 × 10-11 (m3⋅kg-1⋅s-2).

Explanation of the Necessity of the Empirical Equations That Relate the Gravitational Constant and the Temperature of the CMB

In previous papers, we proposed an empirical equation for the fine-structure constant. Using this equation, we proposed a refined version of our own former empirical equations about the electromagnetic force and gravity in terms of the temperature of the cosmic microwave background. The calculated values of the temperature of the cosmic microwave background (Tc) and the gravitational constant (G) were 2.726312 K and 6.673778 × 10-11 m3⋅kg-1⋅ s-2, respectively. Then, for the values of the factors 9/2 and π in our equations, we used 4.488519503 and 3.132011447, respectively. However, we could not provide a theoretical explanation for the necessity of these empirical equations. In this paper, using the redefinition method for the UNIT, we show the necessity for our empirical equations.

Unity Formulas for the Coupling Constants and the Dimensionless Physical Constants

In this paper in an elegant way will be presented the unity formulas for the coupling constants and the dimensionless physical constants. We reached the conclusion of the simple unification of the fundamental interactions. We will find the formulas for the Gravitational constant. It will be presented that the gravitational fine-structure constant is a simple analogy between atomic physics and cosmology. We will find the expression that connects the gravitational fine-structure constant with the four coupling constants. Perhaps the gravitational fine-structure constant is the coupling constant for the fifth force. Also will be presented the simple unification of atomic physics and cosmology. We will find the formulas for the cosmological constant and we will propose a possible solution for the cosmological parameters. Perhaps the shape of the universe is Poincare dodecahedral space. This article will be followed by the energy wave theory and the fractal space-time theory.

THE RELATIVISTIC OBSERVER: Consequences of a Linear Expansion of Spacetime

Communication Dynamics Theory, defined in a companion paper, offers a new approach to understanding Spacetime. In Communication Dynamics Theory, physical reality is assumed to arise from an anisotropic expansion of a one-dimensional communication network. In this paper, we perform a first approximation mathematical transformation of the theory into hyperbolic geometry. The resulting model provides a potential basis for developing insight pertaining to previously poorly understood fundamental constants of physics. As a demonstration, we define a proton, neutron, and electron, demonstrate the emergence of observable space and time, and generate heuristic estimates of Euler’s number, the fine structure constant, and π, as well as geometric descriptions of fundamental forces of nature, occurring as natural consequences of the linear dynamic expansion of Spacetime.

Probing Galactic variations in the fine-structure constant using solar twin stars: methodology and results

ABSTRACT The rich absorption spectra of Sun-like stars are enticing probes for variations in the fine-structure constant, α, which gauges the strength of electromagnetism. While individual line wavelengths are sensitive to α, they are also sensitive to physical processes in the stellar atmospheres, which has precluded their use so far. Here we demonstrate a new differential approach using solar twins: velocity separations between close pairs of transitions are compared across stars with very similar physical properties, strongly suppressing astrophysical and instrumental systematic errors. We utilize 423 archival exposures of 18 solar twins from the High-Accuracy Radial velocity Planetary Searcher (HARPS), in which calibration errors can be reduced to ≲3 m s−1. For stars with ≈10 high-signal-to-noise ratio spectra (≥200 per pixel), velocity separations between pairs are measured with ≈10 m s−1 statistical precision. A companion paper assesses a range of systematic error sources using 130 stars, with a greater range of stellar parameters, providing accurate corrections for astrophysical effects and a residual, intrinsic star-to-star scatter of 0–13 m s−1. Within these uncertainties, we find no evidence for velocity separation differences in 17 transition pairs between solar twins. In a second companion paper, this is found to limit local (≲50 pc) variations in α to ≈50 parts per billion, ∼2 orders of magnitude less than other Galactic constraints.

Probing Galactic variations in the fine-structure constant using solar twin stars: Systematic errors

ABSTRACT Sun-like stars are a new probe of variations in the fine-structure constant, α, via the solar twins approach: velocity separations of close pairs of absorption lines are compared between stars with very similar stellar parameters, i.e. effective temperature, metallicity, and surface gravity within 100 K, 0.1 dex, and 0.2 dex of the Sun’s values. Here, we assess possible systematic errors in this approach by analysing ≳10 000 archival exposures from the High-Accuracy Radial Velocity Planetary Searcher (HARPS) of 130 stars covering a much broader range of stellar parameters. We find that each transition pair’s separation shows broad, low-order variations with stellar parameters that can be accurately modelled, leaving only a small residual, intrinsic star-to-star scatter of 0–33 m s−1 (average ≈7 m s−1, ≈1 × 10−4 Å at 5000 Å). This limits the precision available from a single pair in a single star. We consider potential systematic errors from a range of instrumental and astrophysical sources (e.g. wavelength calibration, charge transfer inefficiency, stellar magnetic activity, line blending) and conclude that variations in elemental abundances, isotope ratios, and stellar rotational velocities may explain this star-to-star scatter. Finally, we find that the solar twins approach can be extended to solar analogues – within 300 K, 0.3 dex, and 0.4 dex of the Sun’s parameters – without significant additional systematic errors, allowing a much larger number of stars to be used as probes of variation in α, including at much larger distances.

Relativistic Ritz approach to hydrogenlike atoms: Theoretical considerations

The Rydberg formula along with the Ritz quantum defect ansatz has been a standard theoretical tool used in atomic physics since before the advent of quantum mechanics, yet this approach has remained limited by its non-relativistic foundation. Here I present a long-distance relativistic effective theory describing hydrogen-like systems with arbitrary mass ratios, thereby extending the canonical Ritz-like approach. Fitting the relativistic theory to the hydrogen energy levels predicted by bound-state QED indicates that it is superior to the canonical, nonrelativistic approach. An analytic analysis reveals nonlinear consistency relations within the bound-state QED level predictions that relate higher-order corrections to those at lower order, providing guideposts for future perturbative calculations as well as insights into the asymptotic behavior of Bethe logarithms. Applications of the approach include fitting to atomic spectroscopic data, allowing for the determination the fine-structure constant from large spectral data sets and also to check for internal consistency of the data independently from bound-state QED.

Search for Ultralight Dark Matter from Long-Term Frequency Comparisons of Optical and Microwave Atomic Clocks.

We search for ultralight scalar dark matter candidates that induce oscillations of the fine structure constant, the electron and quark masses, and the quantum chromodynamics energy scale with frequency comparison data between a ^{171}Yb optical lattice clock and a ^{133}Cs fountain microwave clock that span 298days with an uptime of 15.4%. New limits on the couplings of the scalar dark matter to electrons and gluons in the mass range from 10^{-22} to 10^{-20} eV/c^{2} are set, assuming that each of these couplings is the dominant source of the modulation in the frequency ratio. The absolute frequency of the ^{171}Yb clock transition is also determined as 518 295 836 590 863.69(28)Hz, which is one of the important contributions toward a redefinition of the second in the International System of Units.

W-Boson Mass Anomaly as a Manifestation of Spontaneously Broken Additional SU(2) Global Symmetry on a New Fundamental Scale

Recently, the CDF Collaboration has announced a new precise measurement of the W-boson mass MW that deviates from the Standard Model (SM) prediction by 7σ. The discrepancy in MW is about ΔW ≃ 70 MeV and is probably caused by a beyond the SM physics. Within a certain scenario of extension of the SM, we obtain the relation ΔW ≃ 3α8πMW ≃ 70 MeV, where α is the electromagnetic fine structure constant. The main conjecture is the appearance of longitudinal components of the W-bosons as the Goldstone bosons of a spontaneously broken additional SU(2) global symmetry at distances much smaller than the electroweak symmetry breaking scale rEWSB. We argue that within this scenario, the masses of charged Higgs scalars can obtain an electromagnetic radiative contribution which enhances the observed value of MW± with respect to the usual SM prediction. Our relation for ΔW follows from the known one-loop result for the corresponding effective Coleman–Weinberg potential in combination with the Weinberg sum rules.

Graphene multilayers for coherent perfect absorption: effects of interlayer separation.

We present a model study to estimate the sensitivity of the optical absorption of multilayered graphene structure to the subnanometer interlayer separation. Starting from a transfer-matrix formalism we derive semi-analytical expressions for the far-field observables. Neglecting the interlayer separation, results in upper bounds to the absorption of 50% for real-valued sheet conductivities, exactly the value needed for coherent perfect absorption (CPA), while for complex-valued conductivities we identify upper bounds that are always lower. For pristine graphene the number of layers required to attain this maximum is found to be fixed by the fine structure constant. For finite interlayer separations we find that this upper bound of absorption only exists until a particular value of interlayer separation (Dlim) which is less than the realistic interlayer separation in graphene multilayers. Beyond this value, we find a strong dependence of absorption with the interlayer separation. For an infinite number of graphene layers a closed-form analytical expression for the absorption is derived, based on a continued-fraction analysis that also leads to a simple expression for Dlim. Our comparison with experiments illustrates that multilayer Van der Waals crystals suitable for CPA can be more accurately modelled as electronically independent layers and more reliable predictions of their optical properties can be obtained if their subnanometer interlayer separations are carefully accounted for.

Sulfur doped FeSe: A first-principles study of its electronic and superconducting properties

The self-consistent first-principles calculations, based on density functional theory (DFT) approach and the Green’s-function-based Korringa-Kohn-Rostoker Atomic Sphere Approximation (KKR-ASA) method within coherent potential approximation (CPA), are performed to investigate the electronic and superconducting properties of FeSe1-xSx (x = 0.0, 0.05) alloys. The spin-unpolarized calculations show a significant effect on the electronic structure for the substitution of S in FeSe. The outcome for electronic and superconducting properties have been examined in terms of changes in the density of states, band structure, Fermi surface, bare Sommerfeld constant, Hopfield parameters, and the superconducting transition temperature (Tc) of FeSe and FeSe0.95S0.05 alloys, respectively. All calculated results in terms of Tc compare well with the available experimental data. It hopes that the studied properties of these alloys would give the possibility to understand the new physics of iron-based superconductors experimentally.

A limit on variations in the fine-structure constant from spectra of nearby Sun-like stars.

The fine structure constant α sets the strength of the electromagnetic force. The Standard Model of particle physics provides no explanation for its value, which could potentially vary. The wavelengths of stellar absorption lines depend on α but are subject to systematic effects owing to astrophysical processes in stellar atmospheres. We measured precise line wavelengths from observations of 17 stars, selected to have almost identical atmospheric properties to those of the Sun (solar twins), which reduces those systematic effects. We found that α varies by [Formula: see text] parts per billion within 50 parsecs from Earth. Combining the results from all 17 stars provides an empirical local reference for stellar measurements of α, with an ensemble precision of 12 parts per billion.