Dynamical symmetries and fundamental fields
Dynamical symmetries and fundamental triplets with extreme nonrelativistic model of baryons - high energy interactions
HIGH ENERGY INTERACTION↗
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Theoretical Studies of Lorentz and CPT Symmetry
The fundamental symmetries studied here are Lorentz and CPT invariance, which form a cornerstone of the relativistic quantum theories used in modern descriptions of nature. The results obtained during the reporting period focus on the idea, originally suggested by the P.I. and his group in the late 1980s, that observable CPT and Lorentz violation in nature might emerge from the qualitatively new physics expected to hold at the Planck scale. What follows is a summary of results obtained during the period of this grant.
Kostelecky, V. Alan↗
Impressed Sources and Fields in the Volume-Integral-Equation Formulation of Electromagnetic Scattering by a Finite Object: A Tutorial
Although free space cannot generate electromagnetic waves, the majority of existing accounts of frequency-domain electromagnetic scattering by particles and particle groups are based on the postulate of existence of an impressed incident field, usually in the form of a plane wave. In this tutorial we discuss how to account for the actual existence of impressed source currents rather than impressed incident fields. Specifically, we outline a self-consistent theoretical formalism describing electromagnetic scattering by an arbitrary finite object in the presence of arbitrarily distributed impressed currents, some of which can be far removed from the object and some can reside in its vicinity, including inside the object. To make the resulting formalism applicable to a wide range of scattering-object morphologies, we use the framework of the volume integral equation formulation of electromagnetic scattering, couple it with the notion of the transition operator, and exploit the fundamental symmetry property of this operator. Among novel results, this tutorial includes a streamlined proof of fundamental symmetry (reciprocity) relations, a simplified derivation of the Foldy equations, and an explicit analytical expression for the transition operator of a multi-component scattering object.
Symmetry relations↗
Particle symmetries
Theory of fundamental particle symmetries derived from basic properties of space-time using principles of quantum mechanics and special relativity
RELATIVITY↗
Tests of Gravitational Symmetries with Pulsar Binary J1713+0747
Symmetries play a fundamental role in modern theories of gravity. The strong equivalence principle (SEP) constitutes a collection of gravitational symmetries which are all implemented by general relativity. Alternative theories, however, are generally expected to violate some aspects of SEP. We test three aspects of SEP using observed change rates in the orbital period and eccentricity of binary pulsar J1713+0747: (1) the gravitational constant’s constancy as part of locational invariance of gravitation; (2) the universality of free fall (UFF) for strongly self-gravitating bodies; (3) the post-Newtonian parameter ˆα3 in gravitational Lorentz invariance. Based on the pulsar timing result of the combined data set from the North American Nanohertz Gravitational Observatory and the European Pulsar Timing Array, we find G˙ /G = (−0.1 ± 0.9) × 10−12 yr−1, which is weaker than Solar system limits, but applies for strongly self-gravitating objects. Furthermore, we obtain an improved test for a UFF violation by a strongly self-gravitating mass falling in the gravitational field of our Galaxy, with a limit of |Delta| < 0.002 (95 per cent C.L.). Finally, we derive an improved limit on the self-acceleration of a gravitationally bound rotating body, to a preferred reference frame in the Universe, with −3 × 10−20 < ˆα3 < 4 × 10−20 (95 per cent C.L.). These results are based on direct UFF and ˆα3 tests using pulsar binaries, and they overcome various limitations of previous tests of this kind.
W W Zhu↗
In Situ Infrared Spectroscopy of the Gaseous Species Present in a Diamond Chemical Vapor Deposition System
We interfaced a Hot-Filament Chemical Vapor Deposition (HFCVD) system to the emission port of an FT-IR spectrometer, in order to study the gas phase species present during the deposition of diamond thin films. The implementation of the infrared (IR) emission technique in situ allowed the study of various carbon-containing species believed to be crucial in diamond film growth. The two IR-active vibrational fundamentals of methane, v(3)(f2) and v(4)(f2), were observed at three different filament temperatures: 1000, 1500 and 2000 C. However, the net signal of v(3) was emission, while that of v(4) was absorption. These results indicate that the v(4) fundamental is excited beyond equilibrium, while the v(3) fundamental remains mostly in the ground state. This is due to the small concentration of methane, the low energy of v(4) compared to v(3) or to the Hz vibrational mode, and symmetry considerations that forbid interaction among the four fundamentals of methane. Thus, the excitation of v(3) is more likely than its decay under HFCVD conditions, producing a non-equilibrium population. At a filament temperature of 2000 C, the v(3) (sigma(+)(3)) fundamental of acetylene and a band at 1328 cm-l also ascribed to acetylene (v5 (pi(U)) + v4) appear in net absorption. This correlates well with the onset of molecular hydrogen breaking by the filament, which occurs at temperatures around 2000 C and above. The hydrogen atoms produced in this heterogeneous reaction give rise to a chain of reactions that lead to acetylene, among other carbonaceous species.
Morell, G.↗
An Approach for the Assessment of System Upset Resilience
This report describes an approach for the assessment of upset resilience that is applicable to systems in general, including safety-critical, real-time systems. For this work, resilience is defined as the ability to preserve and restore service availability and integrity under stated conditions of configuration, functional inputs and environmental conditions. To enable a quantitative approach, we define novel system service degradation metrics and propose a new mathematical definition of resilience. These behavioral-level metrics are based on the fundamental service classification criteria of correctness, detectability, symmetry and persistence. This approach consists of a Monte-Carlo-based stimulus injection experiment, on a physical implementation or an error-propagation model of a system, to generate a system response set that can be characterized in terms of dimensional error metrics and integrated to form an overall measure of resilience. We expect this approach to be helpful in gaining insight into the error containment and repair capabilities of systems for a wide range of conditions.
Torres-Pomales, Wilfredo↗
Vibrational spectra and structure of azomethane and azomethane-d6.
The infrared and Raman spectra of azomethane and azomethane-d(6) were examined in detail. Vibrational data provided definitive verification of a trans-structure with C(2h) symmetry. A vibrational assignment is proposed for the 24 fundamental modes based upon the observed contours, isotopic shift ratios, and group frequency correlations. Spectra of the polycrystalline samples indicate that there are at least four molecules per unit cell, since a number of the bands were observed to be split into doublets. The crystal also appeared to have a center of symmetry, since mutual exclusion was clearly operative.
Durig, J. R.↗
Linear decentralized systems with special structure
Certain fundamental structures associated with linear systems having internal symmetries are outlined. It is shown that the theory of finite-dimensional algebras and their representations are closely related to such systems. It is also demonstrated that certain problems in the decentralized control of symmetric systems are equivalent to long-standing problems of linear systems theory. Even though the structure imposed arose in considering the problems of twin-lift helicopters, any large system composed of several identical intercoupled control systems can be modeled by a linear system that satisfies the constraints imposed. Internal symmetry can be exploited to yield new system-theoretic invariants and a better understanding of the way in which the underlying structure affects overall system performance.
Martin, C. F.↗
Three-dimensional solutions for coupled thermoelectroelastic response of multilayered plates
Analytic three-dimensional solutions are presented for the coupled thermoelectroelastic response of multilayered hybrid composite plates. The plates consist of a combination of fiber-reinforced cross-ply and piezothermoelastic layers. Both the thermoelectroelastic static response and its sensitivity coefficients are computed. The sensitivity coefficients measure the sensitivity of the response to variations in different mechanical, thermal and piezoelectric material properties of the plate. A linear constitutive model is used, and the material properties are assumed to be independent of the temperature and the electric field. The plates are assumed to have rectangular geometry and special material symmetries. A mixed formulation is used with the fundamental unknowns consisting of the three transverse stress components; three displacement components; transverse component of the electric displacement field; electric potential; transverse heat flux component, and temperature change. Each of the fundamental unknowns is expressed in terms of a double Fourier series in the Cartesian surface coordinates. A state space approach is used to generate the static response and to evaluate the sensitivity coefficients. Extensive numerical results are presented showing the effects of variation in the geometric parameters of the plate on the different response quantities and their sensitivity coefficients.
Xu, Kangming↗
Broken Symmetries and Magnetic Dynamos
Phase space symmetries inherent in the statistical theory of ideal magnetohydrodynamic (MHD) turbulence are known to be broken dynamically to produce large-scale coherent magnetic structure. Here, results of a numerical study of decaying MHD turbulence are presented that show large-scale coherent structure also arises and persists in the presence of dissipation. Dynamically broken symmetries in MHD turbulence may thus play a fundamental role in the dynamo process.
Shebalin, John V.↗
Dispersion relation for bianisotropic materials and its symmetry properties
The dispersion relation for an arbitrary general bianisotropic medium is derived in Cartesian coordinates, in a form well suited to imposing the boundary conditions when dealing with layered media with planar and parallel interfaces. Special cases of practical interest are also considered. Eleven fundamental coefficient families are identified by considering in detail all the symmetries present in the dispersion relation. An ad hoc expression of the determinant of the sum of two 3 x 3 matrices permits the use of a simple procedure to obtain the coefficients of the dispersion equation. The discussed symmetry properties have general validity, and this technique to evaluate the coefficients may be useful in other fields of application where dispersion relations are of importance.
Graglia, Roberto D.↗
Unsteady motion and transition to turbulence in developing curved duct flow
An experiment was performed to further the understanding of developing flows in curved ducts of square cross-section. Unlike most earlier works, attention was paid to investigating the time-dependent character of the motion. Mean and unsteady flow characteristics were determined using flow visualization and a laser-Doppler velocimeter. Only one velocity component, that aligned in the longitudinal (streamwise) coordinate direction, was measured. Notwithstanding, the time histories, autocorrelations and spectra derived reveal a time-periodic motion that becomes turbulent with increasing Reynolds number. The results are of intrinsic fundamental value and also illustrate the danger of imposing symmetry of the conservation equations on numerical solutions of this flow.
Arnal, M.↗
High-gain step-profiled integrated diagonal horn-antennas
A new step-profiled integrated-horn antenna is proposed. The antenna allows gains in the range of 17-20 dB to be achieved using standard (100) silicon wafers. The antenna is diagonally fed and exhibits very good circular symmetry within the 10-dB beamwidth. It has a fundamental Gaussian coupling efficiency of 83 percent. It is demonstrated that the profiled antenna has a radiation pattern similar to that of its smooth envelope horn, provided that the discontinuity between successive wafers does not exceed 0.15 lambda. The integrated stepped-profile horn performs much better than a corresponding smooth 70 deg flare-angle integrated horn of the same aperture size. The integrated step-profile horn is very well-suited for radio-astonomical and remote-sensing millimeter-wave imaging arrays requiring a large number of focal-plane elements.
Eleftheriades, George V.↗
Reducing Cross-Polarized Radiation From A Microstrip Antenna
Change in configuration of feed of nominally linearly polarized microstrip-patch transmitting array antenna reduces cross-polarized component of its radiation. Patches fed on opposing sides, in opposite phases. Combination of spatial symmetry and temporal asymmetry causes copolarized components of radiation from fundamental modes of patches to reinforce each other and cross-polarized components of radiation from higher-order modes to cancel each other.
Huang, John↗
On the nature of the baryon asymmetry
Whether the baryon asymmetry in the universe is a locally varying or universally fixed number is examined with focus on the existence of a possible matter antimatter domain structure in the universe arising from a GUT with spontaneous CP symmetry breaking. Theoretical considerations and observational data and astrophysical tests relating to this fundamental question are reviewed.
Stecker, F. W.↗
Searching for Organics, Fossils, and Biology on Mars
One of the goals of Astrobiology is to understand life on a fundamental level. All life on Earth is constructed from the same basic biochemical building blocks consisting of 20 amino acids with left handed symmetry, five nucleotides, a few sugars of right handed symmetry and some lipids. Using the metaphor of computers this is equivalent to saying that all life shares the same hardware. Beyond hardware similarity, it is now known that all life has fundamentally the same software. The genetic code of life is common to all organisms. Some have argued that the "hammer of evolution is heavy" and life anywhere is likely to be composed of identical biochemical and genetic patterns. However, in a system as complex as biochemistry it is likely that there are numerous local optima and the details of the optimum found by evolutionary selection on another world would likely depend on the initial conditions and random developments in the early biological history on that world. To address these fundamental questions in Astrobiology we need a second example of life: a second genesis.
McKay, Christopher P.↗
Dynamics of the universe and spontaneous symmetry breaking
It is shown that the presence of a phase transition early in the history of the universe, associated with spontaneous symmetry breaking (believed to take place at very high temperatures at which the various fundamental interactions unify), significantly modifies its dynamics and evolution. This is due to the energy 'pumping' during the phase transition from the vacuum to the substance, rather than the gravitating effects of the vacuum. The expansion law of the universe then differs substantially from the relation considered so far for the very early time expansion. In particular it is shown that under certain conditions this expansion law is exponential. It is further argued that under reasonable assumptions for the mass of the associated Higgs boson this expansion stage could last long enough to potentially account for the observed isotropy of the universe.
Kazanas, D.↗