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1

Mathematical Structure of Discrete Space-time  

E-Print Network [OSTI]

In this letter we briefly investigate the mathematical structure of space-time in the framework of discretization. It is shown that the discreteness of space-time may result in a new mechanical system which differ from the usual quantum mechanics (QM).

An-Wei Zhang

2009-10-08T23:59:59.000Z

2

Optical Activities as Computing Resources for Space-time Symmetries  

E-Print Network [OSTI]

It is known that optical activities can perform rotations. It is shown that the rotation, if modulated by attenuations, can perform symmetry operations of Wigner's little group which dictates the internal space-time symmetries of elementary particles.

Y. S. Kim

2009-02-23T23:59:59.000Z

3

Physics in discrete spaces (A): Space-Time organization  

E-Print Network [OSTI]

We put forward a model of discrete physical space that can account for the structure of space- time, give an interpretation to the postulates of quantum mechanics and provide a possible explanation to the organization of the standard model of particles.

P. Peretto

2010-12-29T23:59:59.000Z

4

The Modification of the Oppenheimer and Snyder Collapsing Dust Ball to a Static Ball in Discrete Space-time  

E-Print Network [OSTI]

Besides the singularity problem, the famous Oppenheimer and Snyder solution is discovered to be of deficiency in two aspects: the internal Friedmann space-time does not have the inherent symmetry and cannot connect to the external Schwarzschild space-time. So the process of gravitational collapse described by this solution is doubtful. The deficiency, together with the singularity problem, result from the imperfection of the field theory in continuous space-time, which is expressed by the infinite precision function theory. The space-time structure of the Oppenheimer and Snyder dust ball is founded to be discrete rather than continuous, and to describe the field theory in discrete space-time it requires a function theory with finite precision. Based on the i order real number and its equivalence class, which is defined in the real number field, the infinite precision function theory is extended to the finite precision function theory. The Einstein field equations are expressed in the form of finite precision, and then the collapsing dust ball solution in continuous space-time is modified to a static ball solution in discrete space-time. It solves all the problems of Oppenheimer and Snyder solution and shows that, with Planck length and Planck time as space-time quantum, a mechanism to resist the gravitational collapse could be obtained by the discretization of space-time.

G. Chen

2008-08-27T23:59:59.000Z

5

Discrete Abelian gauge symmetries and axions  

E-Print Network [OSTI]

We combine two popular extensions of beyond the Standard Model physics within the framework of intersecting D6-brane models: discrete Zn symmetries and Peccei-Quinn axions. The underlying natural connection between both extensions is formed by the presence of massive U(1) gauge symmetries in D-brane model building. Global intersecting D6-brane models on toroidal orbifolds of the type T6/Z2N and T6/Z2xZ2M with discrete torsion offer excellent playgrounds for realizing these extensions. A generation-dependent Z2 symmetry is identified in a global Pati-Salam model, while global left-right symmetric models give rise to supersymmetric realizations of the DFSZ axion model. In one class of the latter models, the axion as well as Standard Model particles carry a non-trivial Z3 charge.

Honecker, Gabriele

2015-01-01T23:59:59.000Z

6

Discrete Abelian gauge symmetries and axions  

E-Print Network [OSTI]

We combine two popular extensions of beyond the Standard Model physics within the framework of intersecting D6-brane models: discrete Zn symmetries and Peccei-Quinn axions. The underlying natural connection between both extensions is formed by the presence of massive U(1) gauge symmetries in D-brane model building. Global intersecting D6-brane models on toroidal orbifolds of the type T6/Z2N and T6/Z2xZ2M with discrete torsion offer excellent playgrounds for realizing these extensions. A generation-dependent Z2 symmetry is identified in a global Pati-Salam model, while global left-right symmetric models give rise to supersymmetric realizations of the DFSZ axion model. In one class of the latter models, the axion as well as Standard Model particles carry a non-trivial Z3 charge.

Gabriele Honecker; Wieland Staessens

2015-02-03T23:59:59.000Z

7

Quantization of Point Particles in 2+1 Dimensional Gravity and Space-Time Discreteness  

E-Print Network [OSTI]

By investigating the canonical commutation rules for gravitating quantized particles in a 2+1 dimensional world it is found that these particles live on a space-time lattice. The space-time lattice points can be characterized by three integers. Various representations are possible, the details depending on the topology chosen for energy-momentum space. We find that an $S_2\\times S_1$ topology yields a physically most interesting lattice within which first quantization of Dirac particles is possible. An $S_3$ topology also gives a lattice, but does not allow first quantized particles.

G. 't Hooft

1996-01-10T23:59:59.000Z

8

Hamilton Operators, Discrete Symmetries, Brute Force and SymbolicC++  

E-Print Network [OSTI]

To find the discrete symmetries of a Hamilton operator $\\hat H$ is of central importance in quantum theory. Here we describe and implement a brute force method to determine the discrete symmetries given by permutation matrices for Hamilton operators acting in a finite-dimensional Hilbert space. Spin and Fermi systems are considered as examples. A computer algebra implementation in SymbolicC++ is provided.

Willi-Hans Steeb; Yorick Hardy

2012-08-23T23:59:59.000Z

9

Discrete symmetry in graphene: the Dirac equation and beyond  

E-Print Network [OSTI]

In this pedagogical paper we review the discrete symmetries of the Dirac equation using elementary tools, but in a comparative order: the usual 3 + 1 dimensional case and the 2 + 1 dimensional case. Motivated by new applications of the 2d Dirac equation in condensed matter, we further analyze the discrete symmetries of a full tight-binding model in hexagonal lattices without conical approximations. We touch upon an effective CPT symmetry breaking that occurs when deformations and second-neighbor corrections are considered.

Sadurní, Emerson; Rosado, Alfonso

2014-01-01T23:59:59.000Z

10

Anomalies of discrete symmetries in various dimensions and group cohomology  

E-Print Network [OSTI]

We study 't Hooft anomalies for discrete global symmetries in bosonic theories in 2, 3 and 4 dimensions. We show that such anomalies may arise in gauge theories with topological terms in the action, if the total symmetry group is a nontrivial extension of the global symmetry by the gauge symmetry. Sometimes the 't Hooft anomaly for a d-dimensional theory with a global symmetry G can be canceled by anomaly inflow from a (d+1)-dimensional topological gauge theory with gauge group G. Such d-dimensional theories can live on the surfaces of Symmetry Protected Topological Phases. We also give examples of theories with more severe 't Hooft anomalies which cannot be canceled in this way.

Anton Kapustin; Ryan Thorngren

2014-04-16T23:59:59.000Z

11

Discrete and continuous symmetries in multi-Higgs-doublet models  

SciTech Connect (OSTI)

We consider the Higgs sector of multi-Higgs-doublet models in the presence of simple symmetries relating the various fields. We construct basis-invariant observables which may in principle be used to detect these symmetries for any number of doublets. A categorization of the symmetries into classes is required, which we perform in detail for the case of two and three Higgs doublets.

Ferreira, P. M. [Instituto Superior de Engenharia de Lisboa, Rua Conselheiro Emidio Navarro, 1900 Lisboa (Portugal); Centro de Fisica Teorica e Computacional, Faculdade de Ciencias, Universidade de Lisboa, Avenida Professor Gama Pinto 2, 1649-003 Lisboa (Portugal); Silva, Joao P. [Instituto Superior de Engenharia de Lisboa, Rua Conselheiro Emidio Navarro, 1900 Lisboa (Portugal); Centro de Fisica Teorica de Particulas, Instituto Superior Tecnico, P-1049-001 Lisboa (Portugal)

2008-12-01T23:59:59.000Z

12

Ramifications of Discrete R Symmetries USC, October 2012  

E-Print Network [OSTI]

in nature which appears extremely tuned: the cosmological constant (dark energy). We have no good ideas Symmetries #12;The Higgs Discovery July 4 2012: ATLAS/CMS/CERN announcement of candidate Higgs discovery Discovery for Supersymmetry Higgs at 125 GeV poses two challenges: 1 In MSSM, mh MZ . Radiative corrections

California at Santa Cruz, University of

13

High Harmonic Generation and Polarization: Angular Momentum Conservation vs Discrete Time-Dependent Symmetries  

E-Print Network [OSTI]

We discuss the place of angular momentum conservation in theoretical and numerical models for high harmonic generation (HHG). Recent experimental work [A. Fleischer et al., Nature Photonics 8, 543 (2014)] has shown conflicting results regarding the conservation of the (photon) angular momentum in HHG. Here we show that simulations using classical (laser and HHG) fields do not conserve angular momentum and that the properties of HHG spectra are actually due to more general discrete time-dependent symmetries that apply equally well for atoms and molecules (here illustrated with He, H3+, Ne+ and H2 models). To conclude, we propose a configuration to test for the accuracy of these simulations compared to selection rule predictions.

Mauger, F; Uzer, T

2015-01-01T23:59:59.000Z

14

Space, time and machines  

E-Print Network [OSTI]

The 2nd law of thermodynamics is used to shed light on present-day puzzles in cosmology. The universal law, given as an equation of motion, describes diverse systems when consuming free energy via various mechanisms to attain stationary states in their respective surroundings. Expansion of the Universe, galactic rotation and lensing as well as clustering of red-shifted spectral lines are found as natural consequences of the maximal energy dispersal that satisfies the conservation of energy, in the forms of kinetic, potential and dissipation. The Universe in its entirety is pictured as a giant Riemann resonator in evolution via step-by-step spontaneous breaking of one stationary-state symmetry to another to diminish energy density differences relative to its zero-density "surroundings". The continuum equation of evolution is proven equivalent to the Navier-Stokes equation. The ubiquitous flow equation has no solution because the forces and flows are inseparable when the dissipative process has three or more degrees of freedom. Since an evolving system is without a norm, there is no unitary transformation to solve the characteristic equation, but detailed trajectories remain inherently intractable. Conversely, stationary-state trajectories can be solved.

Arto Annila

2012-06-19T23:59:59.000Z

15

Conformal symmetries in the extremal process of two-dimensional discrete Gaussian Free Field  

E-Print Network [OSTI]

We study the extremal process associated with the Discrete Gaussian Free Field on the square lattice and show how the conformal symmetries manifest themselves in the scaling limit. Specifically, we prove that the joint process of spatial positions ($x$) and centered values ($h$) of the extreme local maxima in lattice versions of a bounded domain $D\\subset\\mathbb C$ converges, as the lattice spacing tends to zero, to a Poisson point process with intensity measure $Z^D( d x)\\otimes e^{-\\alpha h} d h$, where $\\alpha$ is a constant derived from overall normalization of the field and $Z^D$ is a random a.s.-finite measure on $D$. The laws of the measures $\\{Z^D\\}$ are naturally interrelated; restrictions to subdomains are governed by a Gibbs-Markov property and images under analytic bijections $f$ by the transformation rule $(Z^{f(D)}\\circ f)( d x) =^d |f'(x)|^4 Z^D( d x)$. Conditions are also given that determine the laws of these measures uniquely. All but one of these are known to hold for the critical Liouville Quantum Gravity measure associated with the Continuum Gaussian Free Field.

Marek Biskup; Oren Louidor

2014-10-17T23:59:59.000Z

16

A Potential Foundation for Emergent Space-Time  

E-Print Network [OSTI]

We present a novel derivation of both the Minkowski metric and Lorentz transformations from the consistent quantification of a causally ordered set of events with respect to an embedded observer. Unlike past derivations, which have relied on assumptions such as the existence of a 4-dimensional manifold, symmetries of space-time, or the constant speed of light, we demonstrate that these now familiar mathematics can be derived as the unique means to consistently quantify a network of events. This suggests that space-time need not be physical, but instead the mathematics of space and time emerges as the unique way in which an observer can consistently quantify events and their relationships to one another. The result is a potential foundation for emergent space-time.

Kevin H. Knuth; Newshaw Bahreyni

2014-12-19T23:59:59.000Z

17

E-Print Network 3.0 - abstract relational space-time Sample Search...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Summary: Methods in Applied Sciences and Engineering (ECCOMAS 2008) June 30 -July 5, 2008 Venice, Italy SPACE-TIME... may conserve discrete energy. Hence, in the present work, we...

18

An analytic toy model for relativistic accretion in Kerr space–time  

Science Journals Connector (OSTI)

......motion, since we have assumed mirror symmetry with respect to...technically the same as in the Schwarzschild case (see Paper I), with...space-time, since in the Schwarzschild case one of the roots was...solution given in Paper I for a Schwarzschild space-time. 4.2 Polar......

Emilio Tejeda; Paul A. Taylor; John C. Miller

2013-01-01T23:59:59.000Z

19

Space-time Curvature of Classical Electromagnetism  

E-Print Network [OSTI]

The space-time curvature carried by electromagnetic fields is discovered and a new unification of geometry and electromagnetism is found. Curvature is invariant under charge reversal symmetry. Electromagnetic field equations are examined with De Rham co homology theory. Radiative electromagnetic fields must be exact and co exact to preclude unobserved massless topological charges. Weyl's conformal tensor, here called ``the gravitational field'', is decomposed into a divergence-free non-local piece with support everywhere and a local piece with the same support as the matter. By tuning a local gravitational field to a Maxwell field the electromagnetic field's local gravitational field is discovered. This gravitational field carries the electromagnetic field's polarization or phase information, unlike Maxwell's stress-energy tensor. The unification assumes Einstein's equations and derives Maxwell's equations from curvature assumptions. Gravity forbids magnetic monopoles! This unification is stronger than the Einstein-Maxwell equations alone, as those equations must produce the electromagnetic field's local gravitational field and not just any conformal tensor. Charged black holes are examples. Curvature of radiative null electromagnetic fields is characterized.

R. W. M. Woodside

2004-10-08T23:59:59.000Z

20

Anomalous discrete chiral symmetry in the Gross-Neveu model and loop gas simulations  

E-Print Network [OSTI]

We investigate the discrete chiral transformation of a Majorana fermion on a torus. Depending on the boundary conditions the integration measure can change sign. Taking this anomalous behavior into account we define a chiral order parameter as a ratio of partition functions with differing boundary conditions. Then the lattice realization of the Gross-Neveu model with Wilson fermions is simulated using the recent `worm' technique on the loop gas or all-order hopping representation of the fermions. An algorithm is formulated that includes the Gross-Neveu interaction for N fermion species. The critical line m_c(g) is constructed for a range of couplings at N = 6 and for N = 2, the Thirring model, as examples.

Oliver Bär; Willi Rath; Ulli Wolff

2009-05-27T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

Special Relativity and possible Lorentz violations consistently coexist in Aristotle space-time  

E-Print Network [OSTI]

Some studies interpret quantum measurement as being explicitly non local. Others assume the preferred frame hypothesis. Unfortunately, these two classes of studies conflict with Minkowski space-time geometry. On the contrary, in Aristotle space-time, Lorentz invariance, interpreted as a physical property applying to all phenomena actually satisfying this symmetry (as opposed to a geometrical constraint applying to an assumed pre-existing Minkowski space-time) consistently coexists with possible Lorentz violations. Moreover, as will be pointed out, the geometrical framework provided by Aristotle space-time is in fact necessary to derive the Lorentz transformations from physical hypotheses.

B. Chaverondier

2008-05-15T23:59:59.000Z

22

Convergence of Space-Time Discrete Dynamics to Anisotropic ...  

E-Print Network [OSTI]

Oct 31, 2014 ... where ? is the unit (outward) normal of ?. (Note that D? is a symmetric matrix.) The .... boundary of the initial set ?0 is represented by a graph. ...... The simulation is performed using Matlab and Fast Fourier Transform. We start ...

2014-10-31T23:59:59.000Z

23

Space-time defects and teleparallelism  

E-Print Network [OSTI]

We consider the class of space-time defects investigated by Puntigam and Soleng. These defects describe space-time dislocations and disclinations (cosmic strings), and are in close correspondence to the actual defects that arise in crystals and metals. It is known that in such materials dislocations and disclinations require a small and large amount of energy, respectively, to be created. The present analysis is carried out in the context of the teleparallel equivalent of general relativity (TEGR). We evaluate the gravitational energy of these space-time defects in the framework of the TEGR and find that there is an analogy between defects in space-time and in continuum material systems: the total gravitational energy of space-time dislocations and disclinations (considered as idealized defects) is zero and infinit, respectively.

J. W. Maluf; A. Goya

2001-10-24T23:59:59.000Z

24

Space-times admitting a three-dimensional conformal group  

E-Print Network [OSTI]

Perfect fluid space-times admitting a three-dimensional Lie group of conformal motions containing a two-dimensional Abelian Lie subgroup of isometries are studied. Demanding that the conformal Killing vector be proper (i.e., not homothetic nor Killing), all such space-times are classified according to the structure of their corresponding three-dimensional conformal Lie group and the nature of their corresponding orbits (that are assumed to be non-null). Each metric is then explicitly displayed in coordinates adapted to the symmetry vectors. Attention is then restricted to the diagonal case, and exact perfect fluid solutions are obtained in both the cases in which the fluid four-velocity is tangential or orthogonal to the conformal orbits, as well as in the more general "tilting" case.

J. Carot; A. A. Coley; A. M. Sintes

2000-05-16T23:59:59.000Z

25

Space-Time Insight | Open Energy Information  

Open Energy Info (EERE)

Space-Time Insight Space-Time Insight Jump to: navigation, search Name Space-Time Insight Address 45680 Northport Loop East Place Fremont, California Zip 94538 Sector Efficiency Product SpaceTime Awareness Server Year founded 2008 Number of employees 11-50 Website http://www.spacetimeinsight.co Coordinates 37.4923832°, -121.9532879° Loading map... {"minzoom":false,"mappingservice":"googlemaps3","type":"ROADMAP","zoom":14,"types":["ROADMAP","SATELLITE","HYBRID","TERRAIN"],"geoservice":"google","maxzoom":false,"width":"600px","height":"350px","centre":false,"title":"","label":"","icon":"","visitedicon":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"copycoords":false,"static":false,"wmsoverlay":"","layers":[],"controls":["pan","zoom","type","scale","streetview"],"zoomstyle":"DEFAULT","typestyle":"DEFAULT","autoinfowindows":false,"kml":[],"gkml":[],"fusiontables":[],"resizable":false,"tilt":0,"kmlrezoom":false,"poi":true,"imageoverlays":[],"markercluster":false,"searchmarkers":"","locations":[{"text":"","title":"","link":null,"lat":37.4923832,"lon":-121.9532879,"alt":0,"address":"","icon":"","group":"","inlineLabel":"","visitedicon":""}]}

26

World Sheet and Space Time Physics in Two Dimensional (Super) String Theory  

E-Print Network [OSTI]

We show that tree level ``resonant'' $N$ tachyon scattering amplitudes, which define a sensible ``bulk'' S -- matrix in critical (super) string theory in any dimension, have a simple structure in two dimensional space time, due to partial decoupling of a certain infinite set of discrete states. We also argue that the general (non resonant) amplitudes are determined by the resonant ones, and calculate them explicitly, finding an interesting analytic structure. Finally, we discuss the space time interpretation of our results.

P. Di Francesco; D. Kutasov

1991-09-04T23:59:59.000Z

27

Exact Philosophy of Space-Time  

E-Print Network [OSTI]

Starting from Bunge's (1977) scientific ontology, we expose a materialistic relational theory of space-time, that carries out the program initiated by Leibniz, and provides a protophysical basis consistent with any rigorous formulation of General Relativity. Space-time is constructed from general concepts which are common to any consistent scientific theory and they are interpreted as emergent properties of the greatest assembly of things, namely, the world.

Héctor Vucetich

2011-09-26T23:59:59.000Z

28

Space time as a continuum with a point defect  

E-Print Network [OSTI]

In cosmology it has become usual to try and explain observational data, such as the temperature distribution of the cosmic microwave background or the accelerated expansion of the universe, introducing new entities as dark matter and dark energy. Here we describe a different approach treating space time as a continuum endowed with properties similar to the ones of ordinary material continua, such as internal viscosity and strain distributions originated by defects in the texture. A Lagrangian modelled on the one valid for simple dissipative phenomena in fluids is build and used for empty space time. The internal "viscosity" is shown to correspond to a four-vector field. Using the known symmetry of the universe, assuming the vector field to be divergence-less and solving the Euler-Lagrange equation we obtain directly inflation and a phase of accelerated expansion of space time. The vector field is shown to be connected with the displacement vector field induced by a point defect in a four-dimensional continuum...

Tartaglia, A

2006-01-01T23:59:59.000Z

29

Conserved Quantities for Polyhomogeneous Space-Times  

E-Print Network [OSTI]

The existence of conserved quantities with a structure similar to the Newman-Penrose quantities in a polyhomogeneous space-time is addressed. The most general form for the initial data formally consistent with the polyhomogeneous setting is found. The subsequent study is done for those polyhomogeneous space-times where the leading term of the shear contains no logarithmic terms. It is found that for these space-times the original NP quantities cease to be constants, but it is still possible to construct a set of other 10 quantities that are constant. From these quantities it is possible to obtain as a particular case a conserved quantity found by Chrusciel et al.

J. A. Valiente Kroon

1998-05-27T23:59:59.000Z

30

The Lorentz Group, Noncommutative Space-Time, and Nonlinear Electrodynamics in Majorana-Oppenheimer Formalism  

E-Print Network [OSTI]

Non-linear electrodynamics arising in the frames of field theories in non-commutative space-time is examined on the base of the Riemann-Silberstein-Majorana-Oppenheimer formalism. The problem of form-invariance of the non-linear constitutive relations governed by six non-commutative parameters \\theta_{kl} \\sim {\\bf K} = {\\bf n} + i {\\bf m} is explored in detail on the base of the complex orthogonal group theory SO(3.C). Two Abelian 2-parametric small groups, isomorphic to each other in abstract sense, and leaving unchangeable the extended constitutive relations at arbitrary six parameters \\theta_{kl} of effective media have been found, their realization depends explicitly on invariant length {\\bf K}^{2}. In the case of non-vanishing length a special reference frame in which the small group has the structure SO(2) \\otimes SO(1,1) has been found. In isotropic case no such reference frame exists. The way to interpret both Abelian small groups in physical terms consists in factorizing corresponding Lorentz transformations into Euclidean rotations and boosts. In the context of general study of various dual symmetries in non-commutative field theory, it is demonstrated explicitly that the non-linear constitutive equations in non-commutative electrodynamics are not invariant under continuous dual rotations, instead only invariance under discrete dual transformation exists.

V. Red'kov; E. Tolkachev

2011-09-09T23:59:59.000Z

31

Merging electromagnetism with space-time metric  

E-Print Network [OSTI]

In the present work, it is shown that the electromagnetism may be directly associated to the four-dimensional space-time geometry. The starting point is an analysis of the geodesic equation of general relativity where it is verified that it contains implicitly the effects of the Coulomb and the Lorentz forces. Consequently, some components of the metric tensor are identified with the components of the four-vector electromagnetic potential. Then, it is constructed a low-field equation for the electromagnetism in the same structure of the Einstein field equations for the gravitation, relating the curvature of space-time to sources of charge and current density. In this framework, all the Maxwell equations are implicit. A proof of consistency with the framework of quantum mechanics is shown.

C. A. Duarte

2014-03-10T23:59:59.000Z

32

Space-time measures for subluminal and superluminal motions  

E-Print Network [OSTI]

In present work we examine the implications on both, space-time measures and causal structure, of a generalization of the local causality postulate by asserting its validity to all motion regimes, the subluminal and superluminal ones. The new principle implies the existence of a denumerable set of metrical null cone speeds, \\{$c_k\\}$, where $c_1$ is the speed of light in vacuum, and $c_k/c \\simeq \\epsilon^{-k+1}$ for $k\\geq2$, where $\\epsilon^2$ is a tiny dimensionless constant which we introduce to prevent the divergence of the $x, t$ measures in Lorentz transformations, such that their generalization keeps $c_k$ invariant and as the top speed for every regime of motion. The non divergent factor $\\gamma_k$ equals $k\\epsilon^{-1}$ at speed $c_k$. We speak then of $k-$timelike and $k-$null intervals and of k-timelike and k-null paths on space-time, and construct a causal structure for each regime. We discuss also the possible transition of a material particle from the subluminal to the first superluminal regime and vice versa, making discrete changes in $v^2/c^2$ around the unit in terms of $\\epsilon^2$ at some event, if ponderable matter particles follow k-timelike paths, with $k=1,2$ in this case.

Benjam\\'\\in Calvo-Mozo

2014-05-20T23:59:59.000Z

33

Homothetic perfect fluid space-times  

E-Print Network [OSTI]

A brief summary of results on homotheties in General Relativity is given, including general information about space-times admitting an r-parameter group of homothetic transformations for r>2, as well as some specific results on perfect fluids. Attention is then focussed on inhomogeneous models, in particular on those with a homothetic group $H_4$ (acting multiply transitively) and $H_3$. A classification of all possible Lie algebra structures along with (local) coordinate expressions for the metric and homothetic vectors is then provided (irrespectively of the matter content), and some new perfect fluid solutions are given and briefly discussed.

J. Carot; A. M. Sintes

1996-07-24T23:59:59.000Z

34

Beyond Archimedean Space-Time Structure  

SciTech Connect (OSTI)

It took two millennia after Euclid and until in the early 1880s, when we went beyond the ancient axiom of parallels, and inaugurated geometries of curved spaces. In less than one more century, General Relativity followed. At present, physical thinking is still beheld by the yet deeper and equally ancient Archimedean assumption. In view of that, it is argued with some rather easily accessible mathematical support that Theoretical Physics may at last venture into the non-Archimedean realms. In this introductory paper we stress two fundamental consequences of the non-Archimedean approach to Theoretical Physics: one of them for quantum theory and another for relativity theory. From the non-Archimedean viewpoint, the assumption of the existence of minimal quanta of light (of the fixed frequency) is an artifact of the present Archimedean mathematical basis of quantum mechanics. In the same way the assumption of the existence of the maximal velocity, the velocity of light, is a feature of the real space-time structure which is fundamentally Archimedean. Both these assumptions are not justified in corresponding non-Archimedean models.

Rosinger, Elemer E. [Department of Mathematics and Applied Mathematics, University of Pretoria, Pretoria, 0002 (South Africa); Khrennikov, Andrei [International Center for Mathematical Modeling, in Physics and Cognitive Sciences, Linnaeus University, S-35195, Vaexjoe (Sweden)

2011-03-28T23:59:59.000Z

35

Space-Time Approach to Quantum Electrodynamics  

Science Journals Connector (OSTI)

In this paper two things are done. (1) It is shown that a considerable simplification can be attained in writing down matrix elements for complex processes in electrodynamics. Further, a physical point of view is available which permits them to be written down directly for any specific problem. Being simply a restatement of conventional electrodynamics, however, the matrix elements diverge for complex processes. (2) Electrodynamics is modified by altering the interaction of electrons at short distances. All matrix elements are now finite, with the exception of those relating to problems of vacuum polarization. The latter are evaluated in a manner suggested by Pauli and Bethe, which gives finite results for these matrices also. The only effects sensitive to the modification are changes in mass and charge of the electrons. Such changes could not be directly observed. Phenomena directly observable, are insensitive to the details of the modification used (except at extreme energies). For such phenomena, a limit can be taken as the range of the modification goes to zero. The results then agree with those of Schwinger. A complete, unambiguous, and presumably consistent, method is therefore available for the calculation of all processes involving electrons and photons.The simplification in writing the expressions results from an emphasis on the over-all space-time view resulting from a study of the solution of the equations of electrodynamics. The relation of this to the more conventional Hamiltonian point of view is discussed. It would be very difficult to make the modification which is proposed if one insisted on having the equations in Hamiltonian form.The methods apply as well to charges obeying the Klein-Gordon equation, and to the various meson theories of nuclear forces. Illustrative examples are given. Although a modification like that used in electrodynamics can make all matrices finite for all of the meson theories, for some of the theories it is no longer true that all directly observable phenomena are insensitive to the details of the modification used.The actual evaluation of integrals appearing in the matrix elements may be facilitated, in the simpler cases, by methods described in the appendix.

R. P. Feynman

1949-09-15T23:59:59.000Z

36

B R O O K H A V E N L E C T U R E SERIES Symmetry Principles...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

--B. Notice the spin direction of . Table 1 Symmetries discussed in elementary particle physics. Geometrical symmetries originate in concepts related to the space-time...

37

Spinor structure and internal symmetries  

E-Print Network [OSTI]

Space-time and internal symmetries are considered within one theoretical framework based on the generalized spin and abstract Hilbert space. Complex momentum is understood as a generating kernel of the underlying spinor structure. It is shown that tensor products of biquaternion algebras are associated with the each irreducible representation of the Lorentz group. Space-time discrete symmetries $P$, $T$ and their combination $PT$ are generated by the fundamental automorphisms of this algebraic background (Clifford algebras). Charge conjugation $C$ is presented by a pseudoautomorphism of the complex Clifford algebra. This description of the operation $C$ allows one to distinguish charged and neutral particles including particle-antiparticle interchange and truly neutral particles. Quotient representations of the Lorentz group and their possible relations with $P$- and $CP$-violations are considered. Spin and charge multiplets, based on the interlocking representations of the Lorentz group, are introduced. A central point of the work is a correspondence between Wigner definition of elementary particle as an irreducible representation of the Poincar\\'{e} group and $SU(3)$-description (quark scheme) of the particle as a vector of the supermultiplet (irreducible representation of $SU(3)$). This correspondence is realized on the ground of a spin-charge Hilbert space. Basic hadron supermultiplets of $SU(3)$-theory (baryon octet and two meson octets) are studied in this framework. It is shown that quark phenomenologies are naturally incorporated into presented scheme. The relationship between mass and spin allows one to take a new look at the problem of mass spectrum of elementary particles.

V. V. Varlamov

2014-09-04T23:59:59.000Z

38

The second law of thermodynamics, TCP, and Einstein causality in anti-de Sitter space-time  

E-Print Network [OSTI]

If the vacuum is passive for uniformly accelerated observers in anti-de Sitter space-time (i.e. cannot be used by them to operate a "perpetuum mobile"), they will (a) register a universal value of the Hawking-Unruh temperature, (b) discover a TCP symmetry, and (c) find that observables in complementary wedge-shaped regions are commensurable (local) in the vacuum state. These results are model independent and hold in any theory which is compatible with some weak notion of space-time localization.

Detlev Buchholz; Martin Florig; Stephen J. Summers

1999-05-25T23:59:59.000Z

39

Geodesic structure of Janis-Newman-Winicour space-time  

E-Print Network [OSTI]

In the present paper we study the geodesic structure of the Janis-Newman-Winicour(JNW) space-time which contains a strong curvature naked singularity. This metric is an extension of the Schwarzschild geometry when a massless scalar field is included. We find that the strength parameter $\\mu$ of the scalar field effects on the geodesic structure of the JNW space-time. By solving the geodesic equation and analyzing the behavior of effective potential, we investigate all geodesic types of the test particle and the photon in the JNW space-time. At the same time we simulate all the geodesic orbits corresponding to the energy levels of the effective potential in the JNW space-time.

Sheng Zhou; Ruanjing Zhang; Juhua Chen; Yongjiu Wang

2014-08-26T23:59:59.000Z

40

Slow Neutron Scattering and Space-Time Correlation Functions  

Science Journals Connector (OSTI)

......research-article Articles Slow Neutron Scattering and Space-Time Correlation...Osaka The cross section for neutron scattering is studied in the light of...Quasi-Classical Theory of Slow Neutron Scattering Takeo Nishigori and Sigenobu......

Sigenobu Sunakawa; Shuichiro Yamasaki; Takeo Nishigori

1967-06-01T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

Bose-Einstein condensation in the Rindler space-time  

E-Print Network [OSTI]

We analyze the critical acceleration of the Bose-Einstein condensation induced by the Unruh effect in a complex scalar field at the finite density in the Rindler space-time.

Takeuchi, Shingo

2015-01-01T23:59:59.000Z

42

Regular maximal slicings in asymptotically flat space?times  

Science Journals Connector (OSTI)

An estimate is provided for the lapse function defining asymptotically Euclidean maximal slicings in asymptotically flat space?times. This estimate is found to be in agreement with a similar estimate suggested on heuristic grounds by Smarr and York. It is also shown that in vacuum space?times the scalar curvature of maximal slices remains uniformly bounded in time provided that suitable conditions on the rate of growth of the (negative) lower bound of the Ricci curvature of the slices are satisfied.

Mauro Carfora

1985-01-01T23:59:59.000Z

43

Negative mass bubbles in de Sitter space-time  

E-Print Network [OSTI]

We study the possibility of the existence of negative mass bubbles within a de Sitter space-time background with matter content corresponding to a perfect fluid. It is shown that there exist configurations of the perfect fluid, that everywhere satisfy the dominant energy condition, the Einstein equations and the equations of hydrostatic equilibrium, however asymptotically approach the exact solution of Schwarzschid-de Sitter space-time with a negative mass.

Mbarek, Saoussen

2014-01-01T23:59:59.000Z

44

Negative mass bubbles in de Sitter space-time  

E-Print Network [OSTI]

We study the possibility of the existence of negative mass bubbles within a de Sitter space-time background with matter content corresponding to a perfect fluid. It is shown that there exist configurations of the perfect fluid, that everywhere satisfy the dominant energy condition, the Einstein equations and the equations of hydrostatic equilibrium, however asymptotically approach the exact solution of Schwarzschid-de Sitter space-time with a negative mass.

Saoussen Mbarek; M. B. Paranjape

2014-07-06T23:59:59.000Z

45

Tensor distributions on signature-changing space-times  

E-Print Network [OSTI]

Irregularities in the metric tensor of a signature-changing space-time suggest that field equations on such space-times might be regarded as distributional. We review the formalism of tensor distributions on differentiable manifolds, and examine to what extent rigorous meaning can be given to field equations in the presence of signature-change, in particular those involving covariant derivatives. We find that, for both continuous and discontinuous signature-change, covariant differentiation can be defined on a class of tensor distributions wide enough to be physically interesting.

David Hartley; Robin W. Tucker; Philip A. Tuckey; Tevian Dray

1997-01-21T23:59:59.000Z

46

Space-Time Curvature Signatures in Bose-Einstein Condensates  

E-Print Network [OSTI]

We derive a generalized Gross-Pitaevski (GP) equation immersed on a electromagnetic and a weak gravitational field starting from the covariant Complex Klein-Gordon field in a curved space-time. We compare it with the GP equation where the gravitational field is added by hand as an external potential. We show that there is a small difference of order $g z/c^2$ between them that could be measured in the future using Bose-Einstein Condensates (BEC). This represents the next order correction to the Newtonian gravity in a curved space-time.

Matos, Tonatiuh

2015-01-01T23:59:59.000Z

47

Space-time and special relativity from causal networks  

E-Print Network [OSTI]

We show how the Minkowskian space-time emerges from a topologically homogeneous causal network, presenting a simple analytical derivation of the Lorentz transformations, with metric as pure event-counting. The derivation holds generally for d=1 space dimension, however, it can be extended to d>1 for special causal networks.

Giacomo Mauro D'Ariano; Alessandro Tosini

2010-08-27T23:59:59.000Z

48

New orthogonal space-time block codes with full diversity  

E-Print Network [OSTI]

It has been shown from the Hurwitz-Radon theorem that square complex orthogonal space-time code designs cannot achieve full diversity and full rate simul-taneously, except in the two transmit antenna case. However, this result does not consider non...

Dalton, Lori Anne

2012-06-07T23:59:59.000Z

49

Electromagnetic space-time crystals. II. Fractal computational approach  

E-Print Network [OSTI]

A fractal approach to numerical analysis of electromagnetic space-time crystals, created by three standing plane harmonic waves with mutually orthogonal phase planes and the same frequency, is presented. Finite models of electromagnetic crystals are introduced, which make possible to obtain various approximate solutions of the Dirac equation. A criterion for evaluating accuracy of these approximate solutions is suggested.

G. N. Borzdov

2014-10-20T23:59:59.000Z

50

Propagation of Test Particles and Scalar Fields on a Class of Wormhole Space-Times  

E-Print Network [OSTI]

In this paper, we consider the problem of test particles and test scalar fields propagating on the background of a class of wormhole space-times. For test particles, we solve for arbitrary causal geodesics in terms of integrals which are solved numerically. These integrals are parametrized by the radius and shape of the wormhole throat as well as the initial conditions of the geodesic trajectory. In terms of these parameters, we compute the conditions for the geodesic to traverse the wormhole, to be reflected by the wormhole's potential or to be captured on an unstable bound orbit at the wormhole's throat. These causal geodesics are visualized by embedding plots in Euclidean space in cylindrical coordinates. For test scalar fields, we compute transmission coefficients and quasi-normal modes for arbitrary coupling of the field to the background geometry in the WKB approximation. We show that there always exists an unstable mode whenever the coupling constant is greater than 1/2. This analysis is interesting since recent computations of self-interactions of a static scalar field in wormhole space-times reveal some anomalous dependence on the coupling constant, principally, the existence of an infinite discrete set of poles. We show that this pathological behavior of the self-field is an artifact of computing the interaction for values of the coupling constant that do not lie in the domain of stability.

Peter Taylor

2014-04-29T23:59:59.000Z

51

Coupled fluids model in FRW space-time  

E-Print Network [OSTI]

In this paper, we analyze a two coupled fluids model by investigating several solutions for accelerated universe in flat FRW space-time. One of the fluids can be identified with the matter and the model possesses the standard matter solution also. Beyond the removal of the coincidence problem, we will see how the coupling may change the description of the energy contents of the universe and which features can be aquired with respect to the standard decoupled cases.

Shynaray Myrzakul; Ratbay Myrzakulov; Lorenzo Sebastiani

2014-06-06T23:59:59.000Z

52

Coupled fluids model in FRW space-time  

E-Print Network [OSTI]

In this paper, we analyze a two coupled fluids model by investigating several solutions for accelerated universe in flat FRW space-time. One of the fluids can be identified with the matter and the model possesses the standard matter solution also. Beyond the removal of the coincidence problem, we will see how the coupling may change the description of the energy contents of the universe and which features can be aquired with respect to the standard decoupled cases.

Myrzakul, Shynaray; Sebastiani, Lorenzo

2014-01-01T23:59:59.000Z

53

Noncommutativity in space-time extended by Liouville field  

E-Print Network [OSTI]

The world-sheet quantum conformal invariance can be realized in the presence of the conformal factor $F$, by inclusion of Liouville term. In the background with linear dilaton field, $\\Phi(x)=\\Phi_0+a_\\mu x^\\mu$, the field $F$ becomes a new noncommutative variable. Therefore, it is natural to extend space-time with a new coordinate, $F$, in order to unify expressions for noncommutativity parameter $\\Theta^{ij}$ of the space-time coordinates $x^i$, with the part $\\Theta^i$ connecting noncommutativity between coordinates $x^i$ and $F$. In this way we solve the problems of Dp-brane noncommutativity in a more elegant way. The technical advantage uses the fact that in the extended space-time the action with dilaton field can be rewritten in dilaton free form. We use canonical method and extend its application to the derivation of boundary conditions. From requirement that Hamiltonian, as the time translation generator, has well defined derivatives in the coordinates and momenta, we obtain boundary conditions directly in the canonical form.

B. Nikolic; B. Sazdovic

2007-11-28T23:59:59.000Z

54

Formation of naked singularities in five-dimensional space-time  

SciTech Connect (OSTI)

We numerically investigate the gravitational collapse of collisionless particles in spheroidal configurations both in four- and five-dimensional (5D) space-time. We repeat the simulation performed by Shapiro and Teukolsky (1991) that announced an appearance of a naked singularity, and also find similar results in the 5D version. That is, in a collapse of a highly prolate spindle, the Kretschmann invariant blows up outside the matter and no apparent horizon forms. We also find that the collapses in 5D proceed more rapidly than in 4D, and the critical prolateness for the appearance of an apparent horizon in 5D is loosened, compared to 4D cases. We also show how collapses differ with spatial symmetries comparing 5D evolutions in single-axisymmetry, SO(3), and those in double-axisymmetry, U(1)xU(1).

Yamada, Yuta [Faculty of Information Science and Technology, Osaka Institute of Technology, 1-79-1 Kitayama, Hirakata, Osaka 573-0196 (Japan); Shinkai, Hisa-aki [Faculty of Information Science and Technology, Osaka Institute of Technology, 1-79-1 Kitayama, Hirakata, Osaka 573-0196 (Japan); Computational Astrophysics Laboratory, Institute of Physical and Chemical Research (RIKEN), Hirosawa, Wako, Saitama 351-0198 (Japan)

2011-03-15T23:59:59.000Z

55

Dirac quantization condition for monopole in noncommutative space-time  

SciTech Connect (OSTI)

Since the structure of space-time at very short distances is believed to get modified possibly due to noncommutativity effects and as the Dirac quantization condition, {mu}e=(N/2)({Dirac_h}/2{pi})c, probes the magnetic field point singularity, a natural question arises whether the same condition will still survive. We show that the Dirac quantization condition on a noncommutative space in a model of dynamical noncommutative quantum mechanics remains the same as in the commutative case to first order in the noncommutativity parameter {theta}, leading to the conjecture that the condition will not alter in higher orders.0.

Chaichian, Masud; Tureanu, Anca [Department of Physics, University of Helsinki, P.O. Box 64, FIN-00014 Helsinki (Finland); Helsinki Institute of Physics, P.O. Box 64, FIN-00014 Helsinki (Finland); Ghosh, Subir [Physics and Applied Mathematics Unit, Indian Statistical Institute, Kolkata-700108 (India); Laangvik, Miklos [Department of Physics, University of Helsinki, P.O. Box 64, FIN-00014 Helsinki (Finland)

2009-06-15T23:59:59.000Z

56

Renormalization of gauge theories in curved space-time  

SciTech Connect (OSTI)

We consider the renormalization of general gauge theories on curved space-time background, with the main assumption being the existence of a gauge-invariant and diffeomorphism invariant regularization. Using the Batalin-Vilkovisky formalism, one can show that the theory possesses gauge invariant and diffeomorphism invariant renormalizability at quantum level, up to an arbitrary order of the loop expansion. Starting from this point, we discuss the locality of the counterterms and the general prescription for constructing the power-counting renormalizable theories on curved background.

Lavrov, Peter M. [Department of Mathematical Analysis, Tomsk State Pedagogical University, 634061, Kievskaya St. 60, Tomsk (Russian Federation); Shapiro, Ilya L. [Departamento de Fisica, ICE, Universidade Federal de Juiz de Fora, Juiz de Fora, CEP: 36036-330, MG (Brazil)

2010-02-15T23:59:59.000Z

57

Space-time measures for subluminal and superluminal motions  

E-Print Network [OSTI]

In present work we examine the implications on both, space-time measures and causal structure, of a generalization of the local causality postulate by asserting its validity to all motion regimes, the subluminal and superluminal ones. The new principle implies the existence of a denumerable set of metrical null cone speeds, \\{$c_k\\}$, where $c_1$ is the speed of light in vacuum, and $c_k/c \\simeq \\epsilon^{-k+1}$ for $k\\geq2$, where $\\epsilon^2$ is a tiny dimensionless constant which we introduce to prevent the divergence of the $x, t$ measures in Lorentz transformations, such that their generalization keeps $c_k$ invariant and as the top speed for every regime of motion. The non divergent factor $\\gamma_k$ equals $k\\epsilon^{-1}$ at speed $c_k$. We speak then of $k-$timelike and $k-$null intervals and of k-timelike and k-null paths on space-time, and construct a causal structure for each regime. We discuss also the possible transition of a material particle from the subluminal to the first superluminal regim...

Calvo-Mozo, Benjam\\'\\in

2014-01-01T23:59:59.000Z

58

Properties of few-body systems in relativistic quantum mechanics and constraints from transformations under Poincaré space-time translations  

E-Print Network [OSTI]

Different approaches have been applied to the calculation of form factors of various hadronic systems within relativistic quantum mechanics. In a one-body current approximation, they can lead to results evidencing large discrepancies. Looking for an explanation of this spreading, it is shown that, for the largest part, these discrepancies can be related to a violation of Poincar\\'e space-time translation invariance. Beyond energy-momentum conservation, which is generally assumed, fulfilling this symmetry implies specific relations that are generally ignored. Their relevance within the present context is discussed in detail both to explain the differences between predictions and to remove them.

B. Desplanques

2006-11-17T23:59:59.000Z

59

Photon Green Functions in Curved Space-Time  

E-Print Network [OSTI]

Quantization of electrodynamics in curved space-time in the Lorenz gauge and with arbitrary gauge parameter makes it necessary to study Green functions of non-minimal operators with variable coefficients. Starting from the integral representation of photon Green functions, we link them to the evaluation of integrals involving Gamma-functions. Eventually, the full asymptotic expansion of the Feynman photon Green function at small values of the world function, as well as its explicit dependence on the gauge parameter, are obtained without adding by hand a mass term to the Faddeev-Popov Lagrangian. Coincidence limits of second covariant derivatives of the associated Hadamard function are also evaluated, as a first step towards the energy-momentum tensor in the non-minimal case.

Giuseppe Bimonte; Enrico Calloni; Luciano Di Fiore; Giampiero Esposito; Leopoldo Milano; Luigi Rosa

2005-11-23T23:59:59.000Z

60

On space-times admitting shear-free, irrotational, geodesic null congruences  

E-Print Network [OSTI]

Space-times admitting a shear-free, irrotational, geodesic null congruence are studied. Attention is focused on those space-times in which the gravitational field is a combination of a perfect fluid and null radiation.

A. M. Sintes; A. A. Coley; D. J. McManus

2000-05-16T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

E-Print Network 3.0 - additive space-time white Sample Search...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

space-time white Search Powered by Explorit Topic List Advanced Search Sample search results for: additive space-time white Page: << < 1 2 3 4 5 > >> 1 Click to Submit...

62

Majorana-Oppenheimer approach to Maxwell electrodynamics in Riemannian space-time  

E-Print Network [OSTI]

The Riemann -- Silberstein -- Majorana -- Oppengeimer approach to the Maxwell electrodynamics in presence of electrical sources and arbitrary media is investigated within the matrix formalism. The symmetry of the matrix Maxwell equation under transformations of the complex rotation group SO(3.C) is demonstrated explicitly. In vacuum case, the matrix form includes four real $4 \\times 4$ matrices $\\alpha^{b}$. In presence of media matrix form requires two sets of $4 \\times 4$ matrices, $\\alpha^{b}$ and $\\beta^{b}$ -- simple and symmetrical realization of which is given. Relation of $\\alpha^{b}$ and $\\beta^{b}$ to the Dirac matrices in spinor basis is found. Minkowski constitutive relations in case of any linear media are given in a short algebraic form based on the use of complex 3-vector fields and complex orthogonal rotations from SO(3.C) group. The matrix complex formulation in the Esposito's form, based on the use of two electromagnetic 4-vector, is studied and discussed. Extension of the 3-vector complex matrix formalism to arbitrary Riemannian space-time in accordance with tetrad method by Tetrode-Weyl-Fock-Ivanenko is performed.

A. Bogush; V. Red'kov; N. Tokarevskaya; G. Spix

2009-05-03T23:59:59.000Z

63

Numerical Simulation of Detonation Initiation by the Space-Time Conservation Element and Solution Element Method.  

E-Print Network [OSTI]

??This dissertation is focused on the numerical simulation of the detonation initiation process. The space-time Conservation Element and Solution Element (CESE) method, a novel numerical… (more)

Wang, Bao

2010-01-01T23:59:59.000Z

64

The CP(N-1) Affine Gauge Theory in the Dynamical Space-time  

E-Print Network [OSTI]

An attempt to build quantum theory of field (extended) objects without a priori space-time geometry has been represented. Space-time coordinates are replaced by the intrinsic coordinates in the tangent fibre bundle over complex projective Hilbert state space $CP(N-1)$. The fate of a quantum system modeled by the generalized coherent states is rooted in this manifold. Dynamical (state-dependent) space-time arises only at the stage of the quantum "yes/no" measurement. The quantum measurement of the gauge ``field shell'' of the generalized coherent state is described in terms of the affine parallel transport of the local dynamical variables in $CP(N-1)$.

Peter Leifer

2006-05-25T23:59:59.000Z

65

A Space-Time Petrov--Galerkin Certified Reduced Basis Method: Application to the Boussinesq Equations  

E-Print Network [OSTI]

We present a space-time certified reduced basis method for long-time integration of parametrized parabolic equations with quadratic nonlinearity which admit an affine decomposition in parameter but with no restriction on ...

Yano, Masayuki

66

An analysis of Texas rainfall data and asymptotic properties of space-time covariance estimators  

E-Print Network [OSTI]

This dissertation includes two parts. Part 1 develops a geostatistical method to calibrate Texas NexRad rainfall estimates using rain gauge measurements. Part 2 explores the asymptotic joint distribution of sample space-time covariance estimators...

Li, Bo

2009-06-02T23:59:59.000Z

67

Quantum estimation of the Schwarzschild space-time parameters of the Earth  

E-Print Network [OSTI]

We propose a quantum experiment to measure with high precision the Schwarzschild space-time parameters of the Earth. The scheme can also be applied to measure distances by taking into account the curvature of the Earth's space-time. As a wave-packet of (entangled) light is sent from the Earth to a satellite it is red-shifted and deformed due to the curvature of space-time. Measurements after the propagation enable the estimation of the space-time parameters. We compare our results with the state of the art, which involves classical measurement methods, and discuss what developments are required in space-based quantum experiments to improve on the current measurement of the Schwarzschild radius of the Earth.

David Edward Bruschi; Animesh Datta; Rupert Ursin; Timothy C. Ralph; Ivette Fuentes

2014-08-31T23:59:59.000Z

68

Finding Space-Time Transformations for Uniform Recurrences viaBranching Parametric Linear Programming  

Science Journals Connector (OSTI)

Many important algorithms in signal and image processing can be described by uniform recurrences. A common method for the synthesis of systolic arrays from uniform recurrences is based on space-time transformations each of which consisting of two ...

Karl-Heinz Zimmermann; Wolfgang Achtziger

1997-03-01T23:59:59.000Z

69

Oppenheimer-Volkoff equation inD space-time dimensions  

Science Journals Connector (OSTI)

The equations which describe the hydrostatic equilibrium of a relativistic stellar configuration inD space-time dimensions (D ?/ 4) with a spherical symmetric gravitational field are obtained. With suitable trans...

T. Harko

1992-12-01T23:59:59.000Z

70

The Oppenheimer-Snyder space-time with a cosmological constant  

Science Journals Connector (OSTI)

We investigate the Oppenheimer-Snyder space-time with a positive cosmological...M o of the dust sphere is very large, there is no collapsing solution with the de Sitter-like asymptotic region whic...

Ken-ichi Nakao

1992-10-01T23:59:59.000Z

71

Perfect fluid space-times admitting a 3-dimensional conformal group acting on null orbits  

E-Print Network [OSTI]

Space-times admitting a 3-dimensional Lie group of conformal motions $C_3$ acting on null orbits are studied. Coordinate expressions for the metric and the conformal Killing vectors (CKV) are then provided (irrespectively of the matter content) and all possible perfect fluid solutions are found, although none of them verifies the weak and dominant energy conditions over the whole space-time manifold.

A. M. Sintes; J. Carot

2000-05-16T23:59:59.000Z

72

Topological horseshoes in travelling waves of discretized nonlinear wave equations  

SciTech Connect (OSTI)

Applying the concept of anti-integrable limit to coupled map lattices originated from space-time discretized nonlinear wave equations, we show that there exist topological horseshoes in the phase space formed by the initial states of travelling wave solutions. In particular, the coupled map lattices display spatio-temporal chaos on the horseshoes.

Chen, Yi-Chiuan, E-mail: YCChen@math.sinica.edu.tw [Institute of Mathematics, Academia Sinica, Taipei 10617, Taiwan (China)] [Institute of Mathematics, Academia Sinica, Taipei 10617, Taiwan (China); Chen, Shyan-Shiou, E-mail: sschen@ntnu.edu.tw [Department of Mathematics, National Taiwan Normal University, Taipei 11677, Taiwan (China)] [Department of Mathematics, National Taiwan Normal University, Taipei 11677, Taiwan (China); Yuan, Juan-Ming, E-mail: jmyuan@pu.edu.tw [Department of Financial and Computational Mathematics, Providence University, Shalu, Taichung 43301, Taiwan (China)] [Department of Financial and Computational Mathematics, Providence University, Shalu, Taichung 43301, Taiwan (China)

2014-04-15T23:59:59.000Z

73

SPACE TIME INTERFERENCE ALIGNMENT SCHEME FOR THE MIMO BC AND IC WITH DELAYED CSIT AND FINITE COHERENCE TIME  

E-Print Network [OSTI]

and Heath, space-time interference align- ment (STIA), proves that in the underdetermined (overloaded) multi in [11] proposed a scheme, hereafter referred to as space-time interference alignment (STIA

Gesbert, David

74

High-Fidelity Space-Time Adaptive Multiphysics Simulations in Nuclear Engineering  

SciTech Connect (OSTI)

Monolithic adaptive multimesh hp-FEM discretization of multiphysics coupled problems Monolithic coupling of hp-FEM and hp-DG methods New modular approach to higher-order time discretization of transient PDE problems

Solin, Pavel; Ragusa, Jean

2014-05-21T23:59:59.000Z

75

Mixed variational potentials and inherent symmetries of the Cahn–Hilliard theory of diffusive phase separation  

Science Journals Connector (OSTI)

...principle in the extended (mixed) space of the concentration and chemical...Cahn-Hilliard theory based on the time-space-discrete two-field variational...computing based on the Petsc library [23,24]. The Newton-Raphson...detailed comparison of alternative space-time discretizations with...

2014-01-01T23:59:59.000Z

76

Symmetry Energy  

E-Print Network [OSTI]

Examination of symmetry energy is carried out on the basis of an elementary binding-energy formula. Constraints are obtained on the energy value at the normal nuclear density and on the density dependence of the energy at subnormal densities.

P. Danielewicz

2006-07-15T23:59:59.000Z

77

Astrophysical symmetries  

Science Journals Connector (OSTI)

...indistinguishable from and as common as their mirror images. The actual patterns seen are...Taylor, Kelvin–Helmholtz, Schwarzschild, and other instabilities; and 12...whose shape has about as much mirror symmetry as the arachnid for which...

Virginia Trimble

1996-01-01T23:59:59.000Z

78

Symmetry Energy  

E-Print Network [OSTI]

Examination of symmetry energy is carried out on the basis of an elementary binding-energy formula. Constraints are obtained on the energy value at the normal nuclear density and on the density dependence of the energy at subnormal densities.

Danielewicz, P

2006-01-01T23:59:59.000Z

79

Energy-momentum Prescriptions in General Spherically Symmetric Space-times  

E-Print Network [OSTI]

Einstein, Landau-Lifshitz, Papapetrou, Weinberg, and M{\\o}ller energy-momentum prescriptions in general spherically symmetric space-times are investigated. It is shown that for two special but not unusual classes of general spherically symmetric space-times several energy-momentum prescriptions in Schwarzschild Cartesian coordinates lead to some coincidences in energy distribution. It is also obtained that for a special class of spherically symmetric metrics M{\\o}ller and Einstein energy-momentum prescriptions give the same result for energy distribution if and only if it has a specific dependence on radial coordinate.

Saeed Mirshekari; Amir M. Abbassi

2014-11-29T23:59:59.000Z

80

Is CP a Gauge Symmetry?  

E-Print Network [OSTI]

We suggest here that CP is a discrete {\\it gauge} symmetry, and is therefore not violated by quantum gravity. We show that four dimensional CP can arise as a discrete gauge symmetry in theories with dimensional compactification, if the original number of Minkowski dimensions equals $8k+1$, $8k+2$ or $8k+3$, and if there are certain restrictions on the gauge group; these conditions are met by superstrings. CP may then be broken spontaneously below $10^9$ GeV, explaining the observed CP violation in the kaon system without inducing a large EDMN. We discuss the phenomenology of such models, as well as the peculiar nature of cosmic ``CP strings'' which could be produced at the compactification scale. Such strings have the curious property that a particle carried around the string is turned into its CP conjugate. A single CP string renders four dimensional spacetime nonorientable.

Kiwoon Choi; David B. Kaplan; Ann E. Nelson

1992-05-04T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

THE PERFORMANCE OF SPACE-TIME CODED COOPERATIVE DIVERSITY IN AN ASYNCHRONOUS CELLULAR UPLINK  

E-Print Network [OSTI]

THE PERFORMANCE OF SPACE-TIME CODED COOPERATIVE DIVERSITY IN AN ASYNCHRONOUS CELLULAR UPLINK Kanchan G. Vardhe and Daryl Reynolds Lane Dept. of Comp. Sci. and Elect. Eng. West Virginia University Morgantown, WV kanchanv@csee.wvu.edu, darylreynolds@ieee.org ABSTRACT Most of the prior work on cooperative

Reynolds, Daryl

82

Powering Up With Space-Time Wind Forecasting Amanda S. HERING and Marc G. GENTON  

E-Print Network [OSTI]

Powering Up With Space-Time Wind Forecasting Amanda S. HERING and Marc G. GENTON The technology to harvest electricity from wind energy is now advanced enough to make entire cities powered by it a reality be more realistically assessed with a loss measure that depends upon the power curve relating wind speed

Genton, Marc G.

83

Kerr-Schild geometry from cosmology to microworld and space-time structure  

Science Journals Connector (OSTI)

The Kerr-Schild KS geometry is linked tightly with the auxiliary flat Minkowski background. Nevertheless, it describes many curved space-times and the related physical models, starting from cosmology and black holes to the microworld of the spinning ... Keywords: Bubble Models, Extended Electron, Higgs Field, Kerr-Schild Metric, Semi-Closed Universe, Solitons, Twistors, Vacuum

Alexander Burinskii

2013-01-01T23:59:59.000Z

84

Time-varying Reeb Graphs for Continuous Space-Time Data Herbert Edelsbrunner  

E-Print Network [OSTI]

and/or a fee. SOCG '04 New York City, New York USA Copyright 2004 ACM ?? . . . $4.99. of dataTime-varying Reeb Graphs for Continuous Space-Time Data Herbert Edelsbrunner , John Harer , Ajith the evolving sequence into a single, partially persistent data structure. We envision this data structure

Pascucci, Valerio

85

Inference of cowpox virus transmission rates between wild rodent host classes using space–time interaction  

Science Journals Connector (OSTI)

...hypothesis that space-time interaction among the cowpox cases of host class 2 with respect to cases of host class 1 was no greater than that expected from any subsample of the class 2 population at risk (i.e. not necessarily infected). Random...

2006-01-01T23:59:59.000Z

86

Photon emission in a constant magnetic field in 2+1 dimensional space-time  

E-Print Network [OSTI]

We calculate by the proper-time method the amplitude of the two-photon emission by a charged fermion in a constant magnetic field in (2+1)-dimensional space-time. The relevant dynamics reduces to that of a supesymmetric quantum-mechanical system with one bosonic and one fermionic degrees of freedom.

J. T. S. Amaral; S. I. Zlatev

2005-11-01T23:59:59.000Z

87

Climate Projections Using Bayesian Model Averaging and Space-Time Dependence  

E-Print Network [OSTI]

Climate Projections Using Bayesian Model Averaging and Space-Time Dependence K. Sham Bhat, Murali Haran, Adam Terando, and Klaus Keller. Abstract Projections of future climatic changes are a key input to the design of climate change mitiga- tion and adaptation strategies. Current climate change projections

Haran, Murali

88

Discrete-Gauss states and the generation of focussing dark beams  

E-Print Network [OSTI]

Discrete-Gauss states are a new class of gaussian solutions of the free Schr\\"odinger equation owning discrete rotational symmetry. They are obtained by acting with a discrete deformation operator onto Laguerre-Gauss modes. We present a general analytical construction of these states and show the necessary and sufficient condition for them to host embedded dark beams structures. We unveil the intimate connection between discrete rotational symmetry, orbital angular momentum, and the generation of focussing dark beams. The distinguishing features of focussing dark beams are discussed. The potential applications of Discrete-Gauss states in advanced optical trapping and quantum information processing are also briefly discussed.

Albert Ferrando

2014-03-25T23:59:59.000Z

89

Equations Governing Space-Time Variability of Liquid Water Path in Stratus Clouds  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Equations Governing Space-Time Variability of Equations Governing Space-Time Variability of Liquid Water Path in Stratus Clouds K. Ivanova Pennsylvania State University University Park, Pennsylvania T. P. Ackerman Pacific Northwest National Laboratory Richland, Washington M. Ausloos University of Liège B-4000 Liège, Belgium Abstract We present a method on how to derive an underlying mathematical (statistical or model free) equation for a liquid water path (LWP) signal directly from empirical data. The evolution of the probability density functions (PDFs) from small to large time scales is explicitly derived in the framework of Fokker-Planck equation. A drift and a diffusion term describing the deterministic and stochastic influences on the non-Gaussian fat tails of the liquid water probability distributions are obtained from

90

Iterative methods for solving space-time one dimensional multigroup diffusion equations  

Science Journals Connector (OSTI)

The numerical methods of Successive Overrelaxation (SOR), Successive-Line Overrelaxation (SLOR) and Alternating Direction Implicit (ADI) are used in this research to solve space-time one-dimensional diffusion equations. The results of this research have been compared with the ANL-Benchmark Problem BSS-6-A2. In general, the results are in agreement with the Argonne National Laboratory Benchmark Source Situation (BSS-6-A2). However, there is very little difference between SOR and ANL-BSS-6-A2 because of inner iterations in the SOR method. This research shows that the SLOR and ADI methods are more accurate and more efficient than the SOR method in solving space-time diffusion equations. SLOR is the most efficient in the case of a big number of mesh elements; however, the ADI method is the most efficient in the case of a small number of mesh elements.

Y. Yulianti; Z. Su'ud; A. Waris; S.N. Khotimah

2010-01-01T23:59:59.000Z

91

On the extension of Newton's second law to theories of gravitation in curved space-time  

E-Print Network [OSTI]

We investigate the possibility of extending Newton's second law to the general framework of theories in which special relativity is locally valid, and in which gravitation changes the flat Galilean space-time metric into a curved metric. This framework is first recalled, underlining the possibility to uniquely define a space metric and a local time in any given reference frame, hence to define velocity and momentum in terms of the local space and time standards. It is shown that a unique consistent definition can be given for the derivative of a vector (the momentum) along a trajectory. Then the possible form of the gravitation force is investigated. It is shown that, if the motion of free particles has to follow space-time geodesics, then the expression for the gravity acceleration is determined uniquely. It depends on the variation of the metric with space and time, and it involves the velocity of the particle.

Mayeul Arminjon

2006-09-14T23:59:59.000Z

92

Kaluza–Klein unified field theory and apparent four?dimensional space?time  

Science Journals Connector (OSTI)

In the 1920s Kaluza and Klein achieved an elegant unified theory of gravitation and electromagnetism by assuming that space?time is really 5?dimensional. Their approach has since been extended to even higher dimensions in an effort to provide a geometrical unification of all the fundamental interactions. Any such scheme must answer the obvious objection emphasized by Einstein: Why then does space?time a p p e a r to be only 4?dimensional? This paper provides a semihistorical introduction to Kaluza–Klein unification on a level accessible to those with a basic knowledge of general relativity and particle physics and examines the progress made in answering Einstein’s and related objections.

Christopher F. Chyba

1985-01-01T23:59:59.000Z

93

Evolution of a mass-less test scalar field on Boson Stars space-times  

E-Print Network [OSTI]

We numerically solve the mass-less test scalar field equation on the space-time background of boson stars and black holes. In order to do so, we use a numerical domain that contains future null infinity. We achieve this construction using a scri-fixing conformal compactification technique based on hyperboloidal constant mean curvature foliations of the space-time and solve the conformally invariant wave equation. We present two results: the scalar field shows oscillations of the quasi- normal-mode type found for black holes only for boson star configurations that are compact, and no signs of tail decay is found in the parameter space we explored. Even though our results do not correspond to the master equation of perturbations of boson star solutions, they indicate that the parameter space of boson stars as black hole mimickers is restricted to compact configurations.

F. D. Lora-Clavijo; A. Cruz-Osorio; F. S. Guzmán

2010-07-07T23:59:59.000Z

94

Probing space-time structure of new physics with polarized beams at the ILC  

E-Print Network [OSTI]

At the International Linear Collider large beam polarization of both the electron and positron beams will enhance the signature of physics due to interactions that are beyond the Standard Model. Here we review our recently obtained results on a general model independent method of determining for an arbitary one-particle inclusive state the space-time structure of such new physics through the beam polarization dependence and angular distribution of the final state particle.

B. Ananthanarayan

2006-07-03T23:59:59.000Z

95

Asymptotically Stationary and Static Space-times and Shear-free Null Geodesic Congruences  

E-Print Network [OSTI]

In classical electromagnetic theory, one formally defines the complex dipole moment (the electric plus 'i' magnetic dipole) and then computes (and defines) the complex center of charge by transforming to a complex frame where the complex dipole moment vanishes. Analogously in asymptotically flat space-times it has been shown that one can determine the complex center of mass by transforming the complex gravitational dipole (mass dipole plus 'i' angular momentum) (via an asymptotic tetrad trasnformation) to a frame where the complex dipole vanishes. We apply this procedure to such space-times which are asymptotically stationary or static, and observe that the calculations can be performed exactly, without any use of the approximation schemes which must be employed in general. In particular, we are able to exactly calculate complex center of mass and charge world-lines for such space-times, and - as a special case - when these two complex world-lines coincide, we recover the Dirac value of the gyromagnetic ratio.

T. M. Adamo; E. T. Newman

2009-06-12T23:59:59.000Z

96

Stress-energy tensor in colliding plane wave space-times: An approximation procedure  

E-Print Network [OSTI]

In a recent work on the quantization of a massless scalar field in a particular colliding plane wave space-time, we computed the vacuum expectation value of the stress-energy tensor on the physical state which corresponds to the Minkowski vacuum before the collision of the waves. We did such a calculation in a region close to both the Killing-Cauchy horizon and the folding singularities that such a space-time contains. In the present paper, we give a suitable approximation procedure to compute this expectation value, in the conformal coupling case, throughout the causal past of the center of the collision. This will allow us to approximately study the evolution of such an expectation value from the beginning of the collision until the formation of the Killing-Cauchy horizon. We start with a null expectation value before the arrival of the waves, which then acquires nonzero values at the beginning of the collision and grows unbounded towards the Killing-Cauchy horizon. The value near the horizon is compatible with our previous result, which means that such an approximation may be applied to other colliding plane wave space-times. Even with this approximation, the initial modes propagated into the interaction region contain a function which cannot be calculated exactly and to ensure the correct regularization of the stress-energy tensor with the point-splitting technique, this function must be given up to adiabatic order four of approximation.

Miquel Dorca

1997-11-07T23:59:59.000Z

97

Cosmological perturbations in the (1+3+6)-dimensional space-times  

E-Print Network [OSTI]

Cosmological perturbations in the (1+3+6)-dimensional space-times including photon gas without viscous processes are studied on the basis of Abbott et al.'s formalism. Space-times consist of the outer space (the 3-dimensional expanding section) and the inner space (the 6-dimensional section). The inner space expands initially and contracts later. Abbott et al. derived only power-type solutions in the small wave-number limit which appear at the final stage of the space-times. In this paper, we derive not only small wave-number solutions, but also large wave-number solutions. It is found that the latter solutions depend on the two wave-numbers k_r and k_R (which are defined in the outer and inner spaces, respectively), and that the k_r-dependent and k_R-dependent parts dominate the total perturbations when (k_r/r(t))/(k_R/R(t)) >> 1 or << 1, respectively, where r(t) and R(t) are the scale-factors in the outer and inner spaces. By comparing the behaviors of these perturbations, moreover, changes in the spectrum of perturbations in the outer space with time are discussed.

Kenji Tomita

2014-12-20T23:59:59.000Z

98

Cosmic strings in a space–time with positive cosmological constant  

Science Journals Connector (OSTI)

We study Abelian strings in a fixed de Sitter background. We find that the gauge and Higgs fields extend smoothly across the cosmological horizon and that the string solutions have oscillating scalar fields outside the cosmological horizon for all currently accepted values of the cosmological constant. If the gauge to Higgs boson mass ratio is small enough, the gauge field function has a power-like behaviour, while it is oscillating outside the cosmological horizon if Higgs and gauge boson mass are comparable. Moreover, we observe that Abelian strings exist only up to a maximal value of the cosmological constant and that two branches of solutions exist that meet at this maximal value. We also construct radially excited solutions that only exist for non-vanishing values of the cosmological constant and are thus a novel feature as compared to flat space–time. Considering the effect of the de Sitter string on the space–time, we observe that the deficit angle increases with increasing cosmological constant. Lensed objects would thus be separated by a larger angle as compared to asymptotically flat space–time.

Yves Brihaye; Betti Hartmann

2008-01-01T23:59:59.000Z

99

Cosmic strings in a space-time with positive cosmological constant  

E-Print Network [OSTI]

We study Abelian strings in a fixed de Sitter background. We find that the gauge and Higgs fields extend smoothly across the cosmological horizon and that the string solutions have oscillating scalar fields outside the cosmological horizon for all currently accepted values of the cosmological constant. If the gauge to Higgs boson mass ratio is small enough, the gauge field function has a power-like behaviour, while it is oscillating outside the cosmological horizon if Higgs and gauge boson mass are comparable. Moreover, we observe that Abelian strings exist only up to a maximal value of the cosmological constant and that two branches of solutions exist that meet at this maximal value. We also construct radially excited solutions that only exist for non-vanishing values of the cosmological constant and are thus a novel feature as compared to flat space-time. Considering the effect of the de Sitter string on the space-time, we observe that the deficit angle increases with increasing cosmological constant. Lensed objects would thus be separated by a larger angle as compared to asymptotically flat space-time.

Yves Brihaye; Betti Hartmann

2008-06-03T23:59:59.000Z

100

Broken Symmetry  

ScienceCinema (OSTI)

- Physics, as we know it, attempts to interpret the diverse natural phenomena as particular manifestations of general laws. This vision of a world ruled by general testable laws is relatively recent in the history of mankind. Basically it was initiated by the Galilean inertial principle. The subsequent rapid development of large-scale physics is certainly tributary to the fact that gravitational and electromagnetic forces are long-range and hence can be perceived directly without the mediation of highly sophisticated technical devices. - The discovery of subatomic structures and of the concomitant weak and strong short-range forces raised the question of how to cope with short-range forces in relativistic quantum field theory. The Fermi theory of weak interactions, formulated in terms of point-like current-current interaction, was well-defined in lowest order perturbation theory and accounted for existing experimental data.However, it was inconsistent in higher orders because of uncontrollable divergent quantum fluctuations. In technical terms, in contradistinction to quantum electrodynamics, the Fermi theorywas not ?renormalizable?. This difficulty could not be solved by smoothing the point-like interaction by a massive, and therefore short-range, charged ?vector? particle exchange: theories with massive charged vector bosons were not renormalizable either. In the early nineteen sixties, there seemed to be insuperable obstacles to formulating a consistent theory with short-range forces mediated by massive vectors. - The breakthrough came from the notion of spontaneous symmetry breaking which arose in the study of phase transitions and was introduced in field theory by Nambu in 1960. - Ferromagnets illustrate the notion in phase transitions. Although no direction is dynamically preferred, the magnetization selects a global orientation. This is a spontaneous broken symmetry(SBS)of rotational invariance. Such continuous SBS imply the existence of ?massless? modes (here spin-waves), which are the ancestors of the NG bosons discussed below. Fluctuations of the order parameter (the magnetization) are described by a ?massive? SBS mode. - In field theory, Nambu showed that broken chiral symmetry from a spontaneous generation of hadron masses induces massless pseudoscalar modes (identified with a massless limit of pion fields). This illustrates a general phenomenon made explicit by Goldstone: massless Nambu-Goldstone (NG) bosons are a necessary concomitant of spontaneously broken continuous symmetries. Massive SBS scalars bosons describe, as in phase transitions, the fluctuations of the SBS order parameters. - In 1964, with Robert Brout, we discovered a mechanism based on SBS by which short range interactions are generated from long range ones. A similar proposal was then made independently by Higgs in a different approach. Qualitatively, our mechanism works as follows. The long range fundamental electromagnetic and gravitational interactions are governed by extended symmetries,called gauge symmetries, which were supposed to guarantee that the elementary field constituents which transmit the forces, photons or gravitons, be massless. We considered a generalization of the electromagnetic ?vector? field, known as Yang-Mills fields, and coupled them to fields which acquire from SBS constant values in the vacuum. These fields pervade space, as did magnetization, but they have no spatial orientation: they are ?scalar?? fields. The vector Yang-Mills fields which interact with the scalar fields become massive and hence the forces they mediate become short ranged. We also showed that the mechanism can survive in absence of elementary scalar fields. - Because of the extended symmetries, the nature of SBS is profoundly altered: the NG fields are absorbed into the massive vector Yang-Mills fields and restore the gauge symmetry. This has a dramatic consequence. To confront precision experiments, the mechanism should be consistent at the quantum mechanical level, or in technical terms, should yield a ?renormalizable? theory. From our analysi

None

2011-10-06T23:59:59.000Z

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101

Direct space-time observation of pulse tunneling in an electromagnetic band gap  

SciTech Connect (OSTI)

We present space-time-resolved measurements of electromagnetic pulses tunneling through a coaxial electromagnetic band gap structure. The results show that during the tunneling process the field distribution inside the barrier is an exponentially decaying standing wave whose amplitude increases and decreases as it slowly follows the temporal evolution of the input pulse. At no time is a pulse maximum found inside the barrier, and hence the transmitted peak is not the incident peak that has propagated to the exit. The results support the quasistatic interpretation of tunneling dynamics and confirm that the group delay is not the traversal time of the input pulse peak.

Doiron, Serge; Hache, Alain [Department de physique et d'astronomie, Universite de Moncton, Moncton, New Brunswick, E1A 3E9 (Canada); Winful, Herbert G. [Department of Electrical Engineering and Computer Science, University of Michigan, 1301 Beal Avenue, Ann Arbor, Michigan 48109-2122 (United States)

2007-08-15T23:59:59.000Z

102

SYMMETRY Contract  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

SYMMETRY SYMMETRY Contract - - L E G A L N O T I C E The Enrico Fermi I n s t i t u t e f o r Nuclear S t u d i e s and Department o f Physics, t h e U n i v e r s i t y of Chicago, Chicago, I l l i n o i s Outline of Talks Delivered a t t h e I n t e r n a t i o n a l Conference on Elementary P a r t i c l e s and a t t h e Symposium on Elementary P a r t i c l e s Kyoto, September 1965 Revised January 1 9 6 6 FELLEASED @R ANNOUNCEMENT N J C U SCIENCE ABSTRACTS No. AT ( 11-1) -264 EFINS 06-19 3 DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency Thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process

103

Geodesic motion in the space-time of cosmic strings interacting via magnetic fields  

E-Print Network [OSTI]

We study the geodesic motion of test particles in the space-time of two Abelian-Higgs strings interacting via their magnetic fields. These bound states of cosmic strings constitute a field theoretical realization of p-q-strings which are predicted by inflationary models rooted in String Theory, e.g. brane inflation. In contrast to previously studied models describing p-q-strings our model possesses a Bogomolnyi-Prasad-Sommerfield (BPS) limit. If cosmic strings exist it would be exciting to detect them by direct observation. We propose that this can be done by the observation of test particle motion in the space-time of these objects. In order to be able to make predictions we have to solve the field equations describing the configuration as well as the geodesic equation numerically. The geodesics can then be classified according to the test particle's energy, angular momentum and momentum along the string axis. We find that the interaction of two Abelian-Higgs strings can lead to the existence of bound orbits that would be absent without the interaction. We also discuss the minimal and maximal radius of orbits and comment on possible applications in the context of gravitational wave emission.

Betti Hartmann; Valeria Kagramanova

2012-07-25T23:59:59.000Z

104

Non-perfect-fluid space-times in thermodynamic equilibrium and generalized Friedmann equations  

E-Print Network [OSTI]

Assuming homogeneous and parallax-free space-times, in the case of thermodynamic equilibrium, we construct the energy-momentum tensor of non-perfect fluids. To this end we derive the constitutive equations for energy density, isotropic and anisotropic pressure as well as heat-flux from the respective propagation equations. This provides these quantities in closed form, i. e. in terms of the structure constants of the three-dimensional isometry group of homogeneity and, respectively, of the kinematical quantities expansion, rotation and acceleration. Using Einstein's equations, the thereby occurring constants of integration can be determined such that one gets bounds on the kinematical quantities and finds a generalized form of the Friedmann equations. As a consequence, it is shown that, e. g., for a perfect fluid the Friedmann and G\\"odel models can be recovered. All this is derived without assuming any equations of state or other specific thermodynamic conditions, and, in principle, allows one to go beyond the standard phase cosmology to describe the transition from phase to phase dynamically. The constitutive equations deduced for the class of space-times under consideration point in the direction of extended thermodynamics.

Konrad Schatz; Horst-Heino von Borzeszkowski; Thoralf Chrobok

2014-11-29T23:59:59.000Z

105

Quantized topological terms in weakly coupled gauge theories and their connection to symmetry protected topological phases  

E-Print Network [OSTI]

We consider a weakly coupled gauge theory where charged particles all have large gaps (ie no Higgs condensation to break the gauge "symmetry") and the field strength fluctuates only weakly. We ask what kind of topological terms can be added to the Lagrangian of such a weakly coupled gauge theory. In this paper, we systematically construct quantized topological terms which are generalization of the Chern-Simons terms and $F\\wedge F$ terms, in space-time dimensions $d$ and for any gauge groups (continuous or discrete), using each element of the topological cohomology classes $H^{d+1}(BG,\\Z)$ on the classifying space $BG$ of the gauge group $G$. In 3$d$ or for finite gauge groups above 3$d$, the weakly coupled gauge theories are gapped. So our results on topological terms can be viewed as a systematic construction of gapped topologically ordered phases of weakly coupled gauge theories. In other cases, the weakly coupled gauge theories are gapless. So our results can be viewed as an attempt to systematically cons...

Hung, Ling-Yan

2012-01-01T23:59:59.000Z

106

Generalized CP symmetries and special regions of parameter space in the two-Higgs-doublet model  

SciTech Connect (OSTI)

We consider the impact of imposing generalized CP symmetries on the Higgs sector of the two-Higgs-doublet model, and identify three classes of symmetries. Two of these classes constrain the scalar potential parameters to an exceptional region of parameter space, which respects either a Z{sub 2} discrete flavor symmetry or a U(1) symmetry. We exhibit a basis-invariant quantity that distinguishes between these two possible symmetries. We also show that the consequences of imposing these two classes of CP symmetry can be achieved by combining Higgs family symmetries, and that this is not possible for the usual CP symmetry. We comment on the vacuum structure and on renormalization in the presence of these symmetries. Finally, we demonstrate that the standard CP symmetry can be used to build all the models we identify, including those based on Higgs family symmetries.

Ferreira, P. M. [Instituto Superior de Engenharia de Lisboa, Rua Conselheiro Emidio Navarro, 1900 Lisboa (Portugal); Centro de Fisica Teorica e Computacional, Faculdade de Ciencias, Universidade de Lisboa, Av. Prof. Gama Pinto 2, 1649-003 Lisboa (Portugal); Haber, Howard E. [Santa Cruz Institute for Particle Physics, University of California, Santa Cruz, California 95064 (United States); Silva, Joao P. [Instituto Superior de Engenharia de Lisboa, Rua Conselheiro Emidio Navarro, 1900 Lisboa (Portugal); Centro de Fisica Teorica de Particulas, Instituto Superior Tecnico, P-1049-001 Lisboa (Portugal)

2009-06-01T23:59:59.000Z

107

Symmetries Imposed on Two-Particle Systems. I. A Simple Model  

Science Journals Connector (OSTI)

The consequences of imposing symmetries on two-particle systems is discussed. Such symmetries are generated by finding groups which contain the direct product of a space-time group and an internal symmetry group, and which have irreducible representation spaces spanning the space of two-particle states. Consequences of the symmetry arise from assuming that the S operator transforms as an irreducible tensor operator under this group, so that relations between reduced matrix elements occurring in a partial-wave analysis are obtained.

William H. Klink

1969-05-25T23:59:59.000Z

108

Higher Rank Conformal Fields in the $Sp(2M)$ Symmetric Generalized Space-Time  

E-Print Network [OSTI]

We study various $Sp(2M)$ invariant field equations corresponding to rank $r$ tensor products of the Fock (singleton) representation of $Sp(2M)$. These equations are shown to describe localization on ``branes'' of different dimensions embedded into the generalized space-time $\\M_M$ with matrix (i.e., ``central charge'') coordinates. The case of bilinear tensor product is considered in detail. The conserved currents built from bilinears of rank 1 fields in $\\M_M$ are shown to satisfy the field equations of the rank 2 fields in $\\M_M$. Also, the rank 2 fields in $\\M_M$ are shown to be equivalent to the rank 1 fields in $\\M_{2M}$.

O. A. Gelfond; M. A. Vasiliev

2005-05-19T23:59:59.000Z

109

Doppler Effects from Bending of Light Rays in Curved Space-Times  

E-Print Network [OSTI]

We study Doppler effects in curved space-time, i.e. the frequency shifts induced on electromagnetic signals propagating in the gravitational field. In particular, we focus on the frequency shift due to the bending of light rays in weak gravitational fields. We consider, using the PPN formalism, the gravitational field of an axially symmetric distribution of mass. The zeroth order, i.e. the sphere, is studied then passing to the contribution of the quadrupole moment, and finally to the case of a rotating source. We give numerical estimates for situations of physical interest, and by a very preliminary analysis, we argue that analyzing the Doppler effect could lead, in principle, in the foreseeable future, to the measurement of the quadrupole moment of the giant planets of the Solar System.

Matteo Luca Ruggiero; Angelo Tartaglia; Lorenzo Iorio

2006-05-06T23:59:59.000Z

110

Origin of matter and space-time in the big bang  

SciTech Connect (OSTI)

We review the case for and against a bulk cosmic motion resulting from the quantum entanglement of our universe with the multiverse beyond our horizon. Within the current theory for the selection of the initial state of the universe from the landscape multiverse there is a generic prediction that pre-inflation quantum entanglement with other universes should give rise to a cosmic bulk flow with a correlation length of order horizon size and a velocity field relative to the expansion frame of the universe. Indeed, the parameters of this motion are are tightly constrained. A robust prediction can be deduced indicating that there should be an overall motion of of about 800 km/s relative to the background space time as defined by the cosmic microwave background (CMB). This talk will summarize the underlying theoretical motivation for this hypothesis. Of course our motion relative to the background space time (CMB dipole) has been known for decades and is generally attributed to the gravitational pull of the local super cluster. However, this cosmic peculiar velocity field has been recently deduced out to very large distances well beyond that of the local super cluster by using X-ray galaxy clusters as tracers of matter motion. This is achieved via the kinematic component of the Sunyaev-Zeldovich (KSZ) effect produced by Compton scattering of cosmic microwave background photons from the local hot intracluster gas. As such, this method measures peculiar velocity directly in the frame of the cluster. Similar attempts by our group and others have attempted to independently assess this bulk flow via Type la supernova redshifts. In this talk we will review the observation case for and against the existence of this bulk flow based upon the observations and predictions of the theory. If this interpretation is correct it has profound implications in that we may be observing for the first time both the physics that occurred before the big bang and the existence of the multiverse beyond our horizon.

Mathews, G. J. [University of Notre Dame, Center for Astrophysics/JINA, Notre Dame, IN 46556, USA and Division of Theoretical Astronomy, National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan); Kajino, T. [Division of Theoretical Astronomy, National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588, Japan and Department of Astronomy, Graduate School of Science, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Yamazaki, D. [Division of Theoretical Astronomy, National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan); Kusakabe, M. [School of Liberal Arts and Science, Korea Aerospace University, Goyang 412-791, Korea and Department of Physics, Soongsil University, Seoul 156-743 (Korea, Republic of); Cheoun, M.-K. [Department of Physics, Soongsil University, Seoul 156-743 (Korea, Republic of)

2014-05-02T23:59:59.000Z

111

Symmetries in nuclei  

SciTech Connect (OSTI)

The use of dynamical symmetries or spectrum generating algebras for the solution of the nuclear many-body problem is reviewed. General notions of symmetry and dynamical symmetry in quantum mechanics are introduced and illustrated with simple examples such as the SO(4) symmetry of the hydrogen atom and the isospin symmetry in nuclei. Two nuclear models, the shell model and the interacting boson model, are reviewed with particular emphasis on their use of group-theoretical techniques.

Van Isacker, P. [Grand Accelerateur National d'Ions Lourds, CEA/DSM-CNRS/IN2P3 BP 55027, F-14076 Caen Cedex 5 (France)

2011-03-21T23:59:59.000Z

112

Space–time kinetics modeling of Advanced Heavy Water Reactor for control studies  

Science Journals Connector (OSTI)

The paper presents the mathematical modeling of the space–time kinetics phenomena in Advanced Heavy Water Reactor (AHWR), a 920 MW (thermal), vertical pressure tube type thorium based nuclear reactor. The physical dimensions and the internal feedback effects of the AHWR are such that it is susceptible to xenon induced spatial oscillations. For the study of spatial effects and design of suitable control strategy, the need for a suitable mathematical model which is not of a very large order arises. In this paper, a mathematical model of the reactor within the framework of nodal modeling is derived with the two group neutron diffusion equation as the basis. A linear model in standard state space form is formulated from the set of equations so obtained. It has been shown that comparison of linear system properties could be helpful in deciding upon an appropriate nodalization scheme and thus obtaining a reasonably accurate model. For validation, the transient response of the simplified model has been compared with those from a rigorous finite-difference model.

S.R. Shimjith; A.P. Tiwari; M. Naskar; B. Bandyopadhyay

2010-01-01T23:59:59.000Z

113

Propagation of Test Particles and Scalar Fields on a Class of Wormhole Space-Times  

E-Print Network [OSTI]

In this paper, we consider the problem of test particles and test scalar fields propagating on the background of a class of wormhole space-times. For test particles, we solve for arbitrary causal geodesics in terms of integrals which are solved numerically. These integrals are parametrized by the radius and shape of the wormhole throat as well as the initial conditions of the geodesic trajectory. In terms of these parameters, we compute the conditions for the geodesic to traverse the wormhole, to be reflected by the wormhole's potential or to be captured on an unstable bound orbit at the wormhole's throat. These causal geodesics are visualized by embedding plots in Euclidean space in cylindrical coordinates. For test scalar fields, we compute transmission coefficients and quasi-normal modes for arbitrary coupling of the field to the background geometry in the WKB approximation. We show that there always exists an unstable mode whenever the coupling constant is greater than 1/2. This analysis is interesting si...

Taylor, Peter

2014-01-01T23:59:59.000Z

114

Space-like Dp branes: accelerating cosmologies versus conformally de Sitter space-time  

E-Print Network [OSTI]

We consider the space-like D$p$ brane solutions of type II string theories having isometries ISO$(p+1)$ $\\times$ SO$(8-p,1)$. These are asymptotically flat solutions or in other words, the metrics become flat at the time scale $\\tau \\gg \\tau_0$. On the other hand, when $\\tau \\sim \\tau_0$, we get $(p+1)+1$ dimensional flat FLRWmetrics upon compactification on a $(8-p)$ dimensional hyperbolic space with time dependent radii. We show that the resultant $(p+1)+1$ dimensional metrics describe transient accelerating cosmologies for all $p$ from 1 to 6, i.e., from $(2+1)$ to $(7+1)$ space-time dimensions. We show how the acceleration changes with the interplay of the various parameters characterizing the solutions in $(3+1)$ dimensions. Finally, for $\\tau \\ll \\tau_0$, after compactification on $(8-p)$ dimensional hyperbolic space, the resultant metrics are shown to take the form of $(p+1)+1$ dimensional de Sitter spaces upto a conformal transformation. Cosmologies here are decelerating, but, only in a particular conformal frame we get eternal acceleration.

Kuntal Nayek; Shibaji Roy

2014-11-10T23:59:59.000Z

115

Random center vortex lines in continuous 3D space-time  

E-Print Network [OSTI]

We present a model of center vortices, represented by closed random lines in continuous 2+1- dimensional space- time. These random lines are modeled as being piece-wise linear and an ensemble is generated by Monte Carlo methods. The physical space in which the vortex lines are defined is a cuboid with periodic boundary conditions. Besides moving, growing and shrinking of the vortex configuration, also reconnections are allowed. Our ensemble therefore contains not a fixed, but a variable number of closed vortex lines. This is expected to be important for realizing the deconfining phase transition. Using the model, we study both vortex percolation and the potential V (R) between quark and anti-quark as a function of distance R at different vortex densities, vortex segment lengths, reconnection conditions and at different temperatures. We have found three deconfinement phase transitions, as a function of density, as a function of vortex segment length, and as a function of temperature. The model reproduces the qualitative features of confinement physics seen in SU(2) Yang-Mills theory.

Roman Höllwieser; Derar Altarawneh; Michael Engelhardt

2014-11-26T23:59:59.000Z

116

Studies of Discrete and Flavor Symmetries in Supersymmetric Field Theories  

E-Print Network [OSTI]

dark matter models [86, 111], so searches for low energy antideuterons can provide a promising discovery

Monteux, Angelo

2014-01-01T23:59:59.000Z

117

Self–organized living systems: conjunction of a stable organization with chaotic fluctuations in biological space–time  

Science Journals Connector (OSTI)

...helix (Watson 1968), that he went to the library and he had to read less than 10 papers on...conjecture is that living systems operate in a space with a changing num- ber of dimensions (biological space-time), and that it is this very ability...

2003-01-01T23:59:59.000Z

118

A Generic Space-Time-Frequency Correlation Model and Its Corresponding Simulation Model for Narrowband MIMO Channels  

E-Print Network [OSTI]

A Generic Space-Time-Frequency Correlation Model and Its Corresponding Simulation Model.Laurenson d9ed. ac. uk Keyword: Wireless channels, NIIMO, STF correlation, deterministic simulation model theoretical reference model, a deterministic simulation model is then proposed and its 3-D STF correlation

Wang, Cheng-Xiang

119

Modified Brans-Dicke theory with space-time anisotropic parameters  

E-Print Network [OSTI]

We consider the ADM formalism of the Brans-Dicke theory and propose an anisotropic extension of the theory by introducing five free parameters. We find that the resulting theory reveals many interesting aspects which are not present in the original BD theory. We first discuss the ghost instability and strong coupling problems which are present in the gravity theory without the full diffeomorphism symmetry and show that they can be avoided in a region of the parameter space. We also perform the post-Newtonian approximation and show that the constraint of the Brans-Dicke parameter $\\omega_{{\\rm BD}}$ being large to be consistent with the solar system observations could be evaded in the extended theory. We also discuss that accelerating Universe can be achieved without the need of the potential for the Brans-Dicke scalar.

Taeyoon Moon; Phillial Oh

2014-02-22T23:59:59.000Z

120

Symmetries in physics  

E-Print Network [OSTI]

The concept of symmetries in physics is briefly reviewed. In the first part of these lecture notes, some of the basic mathematical tools needed for the understanding of symmetries in nature are presented, namely group theory, Lie groups and Lie algebras, and Noether's theorem. In the second part, some applications of symmetries in physics are discussed, ranging from isospin and flavor symmetry to more recent developments involving the interacting boson model and its extension to supersymmetries in nuclear physics.

Roelof Bijker

2005-09-02T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

$K_S$ semileptonic decays and test of $\\mathcal{CPT}$ symmetry with the KLOE detector  

E-Print Network [OSTI]

Study of semileptonic decays of neutral kaons allows to perform a test of discrete symmetries, as well as basic principles of the Standard Model. In this paper a general review on dependency between charge asymmetry constructed for semileptonic decays of short- and long-lived kaons and $\\mathcal{CPT}$ symmetry is given.

D. Kami?ska

2015-01-19T23:59:59.000Z

122

$K_S$ semileptonic decays and test of $\\mathcal{CPT}$ symmetry with the KLOE detector  

E-Print Network [OSTI]

Study of semileptonic decays of neutral kaons allows to perform a test of discrete symmetries, as well as basic principles of the Standard Model. In this paper a general review on dependency between charge asymmetry constructed for semileptonic decays of short- and long-lived kaons and $\\mathcal{CPT}$ symmetry is given.

Kami?ska, D

2015-01-01T23:59:59.000Z

123

Algorithms for coupled problems that preserve symmetries and the laws of thermodynamics  

E-Print Network [OSTI]

Algorithms for coupled problems that preserve symmetries and the laws of thermodynamics Part I is that they rigorously preserve the two laws of thermodynamics as well as the symmetries of the systems they model-equilibrium thermodynamics and we follow a systematic methodology that results in discrete evolution equations which mimic

Romero, Ignacio

124

Discrete Hamiltonian variational integrators  

Science Journals Connector (OSTI)

......Journal of Numerical Analysis (2011) 31, 1497-1532 doi:10.1093/imanum/drq027 Advance Access publication on March 17, 2011 Discrete Hamiltonian variational integrators MELVIN LEOK Department of Mathematics, University of California, San......

Melvin Leok; Jingjing Zhang

2011-10-01T23:59:59.000Z

125

Visibility in Discrete Geometry: an application to discrete geodesic paths  

E-Print Network [OSTI]

Visibility in Discrete Geometry: an application to discrete geodesic paths David Coeurjolly that are visible from a source pixel. Based on these definitions, we define discrete geodesic paths in dis- crete domain with obstacles. This allows us to introduce a new geodesic metric in discrete geometry

Paris-Sud XI, Université de

126

A discrete fractional random transform  

E-Print Network [OSTI]

We propose a discrete fractional random transform based on a generalization of the discrete fractional Fourier transform with an intrinsic randomness. Such discrete fractional random transform inheres excellent mathematical properties of the fractional Fourier transform along with some fantastic features of its own. As a primary application, the discrete fractional random transform has been used for image encryption and decryption.

Zhengjun Liu; Haifa Zhao; Shutian Liu

2006-05-20T23:59:59.000Z

127

The Symmetries of QCD  

ScienceCinema (OSTI)

The symmetries of a quantum field theory can be realized in a variety of ways. Symmetries can be realized explicitly, approximately, through spontaneous symmetry breaking or, via an anomaly, quantum effects can dynamically eliminate a symmetry of the theory that was present at the classical level.  Quantum Chromodynamics (QCD), the modern theory of the strong interactions, exemplify each of these possibilities. The interplay of these effects determine the spectrum of particles that we observe and, ultimately, account for 99% of the mass of ordinary matter. 

Sekhar Chivukula

2010-01-08T23:59:59.000Z

128

An unusual space-time evolution for heavy ion collisions at high energies due to the QCD phase transition  

E-Print Network [OSTI]

The space-time evolution of high energy non-central heavy ion collisions is studied with relativistic hydrodynamics. The results are very sensitive to the Equation of State(EoS). For an EoS with the QCD phase transition, an unusual matter distribution develops. Before freeze-out, two shells are formed which then physically separate and leave a maximum in the center. We make specific predictions for the azimuthal dependence of the flow and for two-pion interferometry, contrasting our results with a resonance gas EoS.

D. Teaney; E. V. Shuryak

1999-04-02T23:59:59.000Z

129

Unusual Space-Time Evolution for Heavy-Ion Collisions at High Energies due to the QCD Phase Transition  

Science Journals Connector (OSTI)

The space-time evolution of high-energy noncentral heavy-ion collisions is studied with relativistic hydrodynamics. The results are very sensitive to the equation of state (EoS). For an EoS with the QCD phase transition, an unusual matter distribution develops. Before freeze-out, two shells are formed which physically separate and leave a maximum in the center. We make specific predictions for the azimuthal dependence of the flow and for two-pion interferometry, contrasting our results with a resonance gas EoS.

D. Teaney and E. V. Shuryak

1999-12-13T23:59:59.000Z

130

Primary and reciprocal space-time experiments, relativistic reciprocity relations and Einstein's train-embankment thought experiment  

E-Print Network [OSTI]

The concepts of primary and reciprocal experiments and base and travelling frames in special relativity are concisely described and applied to several different space-time experiments. These include Einstein's train/embankment thought experiment and a related thought experiment, due to Sartori, involving two trains in parallel motion with different speeds. Spatially separated clocks which are synchronised in their common proper frame are shown to be so in all inertial frames and their spatial separation to be Lorentz invariant. The interpretions given by Einstein and Sartori of their experiments, as well as those given by the present author in previous papers, are shown to be erroneous.

J. H. Field

2011-11-11T23:59:59.000Z

131

Solution to the transverse-phase-space time-dependence problem with LAMPF's high-intensity H/sup +/ beam  

SciTech Connect (OSTI)

The 750 keV H/sup +/ beam at LAMPF has a transverse phase-space time-dependent transient during the first 200 ..mu..s of each 750-..mu..s-long macro-pulse. The time dependence is documented in an earlier report. Further studies indicate that the time dependence is due to space-charge neutralization resulting from secondary emission of electrons produced by collisions of the H/sup +/ and H/sub 2//sup +/ beams on the transport walls. One of several possible solutions has been tested and has proven successful in eliminating the time dependence of the beam entering the linac.

Hurd, J.W.

1983-01-01T23:59:59.000Z

132

Discrete and continuous exponential transforms of simple Lie groups of rank two  

E-Print Network [OSTI]

We develop and describe continuous and discrete transforms of class functions on compact simple Lie group $G$ as their expansions into series of uncommon special functions, called here $\\E$-functions in recognition of the fact that the functions generalize common exponential functions. The rank of $G$ is the number of variables in the $\\E$-functions. A uniform discretization of the decomposition problem is described on lattices of any density and symmetry admissible for the Lie group $G$.

Iryna Kashuba; Jiri Patera

2007-02-05T23:59:59.000Z

133

Nuclear Symmetry Energy  

Science Journals Connector (OSTI)

On the basis of a phenomenological theory proposed in an earlier paper the nuclear symmetry energy is recalculated. The value obtained is smaller than the one given before, which was incorrect. A relativistic calculation of the energy with the radius parameter r0=1.07×10-13 cm of the electron scattering experiments yields about the correct symmetry energy. Compensating uncertainties due to inaccuracy in r0, corrections due to the exclusion principle, and a possible difference in the radius of proton and neutron distributions make an accurate comparison with the empirical symmetry energy meaningless.

Hans-Peter Duerr

1958-01-01T23:59:59.000Z

134

2D and 3D Visibility in Discrete Geometry: an application to discrete geodesic paths  

E-Print Network [OSTI]

1 2D and 3D Visibility in Discrete Geometry: an application to discrete geodesic paths D discrete geodesic paths in discrete domain with obstacles. This allows us to introduce a new geodesic metric in discrete geometry. Keywords: discrete visibility, geodesic path, distance transform, discrete

Boyer, Edmond

135

Bohmian Mechanics with Discrete Operators  

E-Print Network [OSTI]

A deterministic Bohmian mechanics for operators with continuous and discrete spectra is presented. Randomness enters only through initial conditions. Operators with discrete spectra are incorporated into Bohmian mechanics by associating with each operator a continuous variable in which a finite range of the continuous variable correspond to the same discrete eigenvalue. In this way Bohmian mechanics can handle the creation and annihilation of particles. Examples are given and generalizations are discussed.

R. A. Hyman; Shane A. Caldwell; Edward Dalton

2004-01-02T23:59:59.000Z

136

The algebra of discrete torsion  

E-Print Network [OSTI]

Oct 1, 2004 ... ... of Vafa's and Douglas's picture of discrete torsion, J. High Energy ... Quasi Hopf algebras, group cohomology and orbifold models, Nuclear.

2004-10-13T23:59:59.000Z

137

Nuclear symmetry energy  

Science Journals Connector (OSTI)

To study the nuclear symmetry energy, we extend the Dirac-Brueckner approach with a Bonn one-boson-exchange nucleon-nucleon interaction to the general case of asymmetric nuclear matter. We extract the symmetry energy coefficient at the saturation to be about 31 MeV, which is in good agreement with the empirical value of 30±4 MeV. The symmetry energy is found to increase almost linearly with the density, which differs considerably from the results of nonrelativistic approaches. This finding also supports the linear parametrization of Prakash, Ainsworth, and Lattimer. We find, furthermore, that the higher-order dependence of the nuclear equation of state on the asymmetry parameter is unimportant.

C.-H. Lee; T. T. S. Kuo; G. Q. Li; G. E. Brown

1998-06-01T23:59:59.000Z

138

Symmetry planes of Paleozoic crinoids  

E-Print Network [OSTI]

Webster—Symmetry Planes of Paleozoic Crinoids 15Lane and -vestibule o CD 1 6 moot: 5 -hydropore 8b 7b Fin. 1—Symmetry planes of Paleozoic crinoids (1-5) and crinoid larvae (6-10). I. Anteroposterior (A-CD) symmetry plane of most Paleozoic crinoids... Webster—Symmetry Planes of Paleozoic Crinoids 15Lane and -vestibule o CD 1 6 moot: 5 -hydropore 8b 7b Fin. 1—Symmetry planes of Paleozoic crinoids (1-5) and crinoid larvae (6-10). I. Anteroposterior (A-CD) symmetry plane of most Paleozoic crinoids...

Lane, N. G.; Webster, G. D.

1967-11-30T23:59:59.000Z

139

Discrete Pearson distributions  

SciTech Connect (OSTI)

These distributions are generated by a first order recursive scheme which equates the ratio of successive probabilities to the ratio of two corresponding quadratics. The use of a linearized form of this model will produce equations in the unknowns matched by an appropriate set of moments (assumed to exist). Given the moments we may find valid solutions. These are two cases; (1) distributions defined on the non-negative integers (finite or infinite) and (2) distributions defined on negative integers as well. For (1), given the first four moments, it is possible to set this up as equations of finite or infinite degree in the probability of a zero occurrence, the sth component being a product of s ratios of linear forms in this probability in general. For (2) the equation for the zero probability is purely linear but may involve slowly converging series; here a particular case is the discrete normal. Regions of validity are being studied. 11 refs.

Bowman, K.O. [Oak Ridge National Lab., TN (United States); Shenton, L.R. [Georgia Univ., Athens, GA (United States); Kastenbaum, M.A. [Kastenbaum (M.A.), Basye, VA (United States)

1991-11-01T23:59:59.000Z

140

Symmetry and cluster magnetism  

Science Journals Connector (OSTI)

Three possible isomers of 13-atom iron clusters are studied using local-density-functional methods that allow the spin of the cluster to be determined self-consistently. The ground state is the icosahedral structure. It has the greatest magnetic moment because of increased symmetry-required orbital degeneracy for electrons of different spins.

Brett I. Dunlap

1990-05-15T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

Ant Algorithms for Discrete Optimization  

E-Print Network [OSTI]

Ant Algorithms for Discrete Optimization Marco Dorigo Gianni Di Caro IRIDIA CP 194/6 Universit algorithms, ant colony optimiza- tion, swarm intelligence, metaheuris- tics, natural computation Abstract This article presents an overview of recent work on ant algorithms, that is, algorithms for discrete

Hutter, Frank

142

Finsler manifolds with general symmetries  

E-Print Network [OSTI]

In this paper, we study generalized symmetric Finsler spaces. We first study symmetry preserving diffeomorphisms, then we show that the group of symmetry preserving diffeomorphisms is a transitive Lie transformation group. Finally we give some existence theorems.

Latifi, Dariush

2012-01-01T23:59:59.000Z

143

Symmetry Energy in Nuclear Surface  

E-Print Network [OSTI]

Interplay between the dependence of symmetry energy on density and the variation of nucleonic densities across nuclear surface is discussed. That interplay gives rise to the mass dependence of the symmetry coefficient in an energy formula. Charge symmetry of the nuclear interactions allows to introduce isoscalar and isovector densities that are approximately independent of the magnitude of neutron-proton asymmetry.

Pawel Danielewicz; Jenny Lee

2008-12-25T23:59:59.000Z

144

Symmetry Energy in Nuclear Surface  

E-Print Network [OSTI]

Interplay between the dependence of symmetry energy on density and the variation of nucleonic densities across nuclear surface is discussed. The interplay leads to a dependence of the symmetry coefficient, in energy formula, on nuclear mass. Charge symmetry of nuclear interactions allows to introduce isoscalar and isovector densities that are approximately independent of neutron-proton asymmetry.

Danielewicz, Pawel

2008-01-01T23:59:59.000Z

145

Gravitation and Duality Symmetry  

E-Print Network [OSTI]

By generalizing the Hodge dual operator to the case of soldered bundles, and working in the context of the teleparallel equivalent of general relativity, an analysis of the duality symmetry in gravitation is performed. Although the basic conclusion is that, at least in the general case, gravitation is not dual symmetric, there is a particular theory in which this symmetry shows up. It is a self dual (or anti-self dual) teleparallel gravity in which, due to the fact that it does not contribute to the interaction of fermions with gravitation, the purely tensor part of torsion is assumed to vanish. The ensuing fermionic gravitational interaction is found to be chiral. Since duality is intimately related to renormalizability, this theory may eventually be more amenable to renormalization than teleparallel gravity or general relativity.

V. C. de Andrade; A. L. Barbosa; J. G. Pereira

2005-05-16T23:59:59.000Z

146

Comparison of point kinetics, improved quasistatic and theta method as space-time kinetics solvers in DONJON-3 simulations  

SciTech Connect (OSTI)

To ensure the safety of nuclear reactors, we have to simulate accurately their normal operation and also accident cases. To perform transient calculations, coupled neutronic and fhermo-hydraulic codes are used. This article compares three neutronic solvers. The first one is the point kinetic approach where the flux shape is constant during all the transient. For the second method (the improved quasistatic method), the flux shape is constant but only during small time steps. Finally, we used the theta approach where both flux and precursors distributions vary with time and space. Transients of Lost Of Coolant Accident in CANDU-6 reactors have been simulated with DONJON and the outputs of a thermalhydraulic system code. Results show that the point kinetics is inappropriate for transient with large distortion of the flux shape. Improved quasistatic and theta methods give relatively similar results. However, the improved quasistatic approach is less stable and a little bit more sensitive on time-step and spatial discretization than the theta method is. (authors)

Chambon, R.; Marleau, G. [Institut de Genie Nucleaire, Ecole Polytechnique de Montreal, 2500 chemin de la Polytechnique, Montreal, QC H3C 3A7 (Canada)

2012-07-01T23:59:59.000Z

147

Geodesic spaces : momentum Groups : symmetry  

E-Print Network [OSTI]

Geodesic spaces : momentum :: Groups : symmetry Vaughan Pratt Stanford University BLAST 2010 a · b denoting b rotated 90 degrees about a. End of reprise. 3. This talk; Geodesic spaces At FMCS. as points evenly spaced along a geodesic , right distributivity expresses a symmetry of about an arbitrary

Pratt, Vaughan

148

Gauge Transformations as Spacetime Symmetries  

SciTech Connect (OSTI)

Weinberg has shown that massless fields of helicity {+-}1(vector fields) do not transform homogeneously under Unitary Lorentz Transformations (LT). We calculate explicitly the inhomogeneous term. We show that imposing strict invariance of the Lagrangian under LT for an iteracting Dirac field requires the fermion field to transform with a space-time (and photon creation and annihilation operators) dependent phase and dictates the interaction terms as those arising from the conventional gauge principle.

Angeles, Rene; Napsuciale, Mauro [Division de Ciencias e Ingenierias, Universidad de Guanajuato, Lomas del Bosque 103, Fraccionamiento Lomas del Campestre, Leon Guanajuato, 37150 (Mexico)

2009-04-20T23:59:59.000Z

149

Ant Algorithms for Discrete Optimization  

E-Print Network [OSTI]

Ant Algorithms for Discrete Optimization Marco Dorigo and Gianni Di Caro IRIDIA, Universit´e Libre, Switzerland luca@idsia.ch Abstract This paper overviews recent work on ant algorithms, that is, algorithms and of some of the most important aspects of the ACO meta-heuristic. 1 Introduction Ant algorithms were first

Gambardella, Luca Maria

150

Ant Algorithms for Discrete Optimization  

E-Print Network [OSTI]

Ant Algorithms for Discrete Optimization Marco Dorigo and Gianni Di Caro IRIDIA, Universit#19;e, Switzerland luca@idsia.ch Abstract This paper overviews recent work on ant algorithms, that is, algorithms work and of some of the most important aspects of the ACO meta-heuristic. 1 Introduction Ant algorithms

Ducatelle, Frederick

151

Discrete bidding games Mike Develin  

E-Print Network [OSTI]

Tic-Tac-Toe, are suitable for recreational play. We also present an analysis of Tic-Tac-Toe for both discrete and real-valued bidding. Contents 1 Introduction 2 1.1 A game of bidding Tic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 5 A partial order on games 21 6 Bidding Tic-Tac-Toe 23 6.1 Optimal moves

Payne, Sam

152

Symmetry-breaking mechanism for the Z4 general-covariant evolution system  

Science Journals Connector (OSTI)

The general-covariant Z4 formalism is further analyzed. The gauge conditions are generalized with a view to numerical relativity applications and the conditions for obtaining strongly hyperbolic evolution systems are given both at the first and the second order levels. A symmetry-breaking mechanism is proposed that allows one, when applied in a partial way, to recover previously proposed strongly hyperbolic formalisms, like the BSSN and the Bona-Massó formulas. When applied in its full form, the symmetry-breaking mechanism allows one to recover the full five-parameter family of first order KST systems. Numerical codes based in the proposed formalisms are tested. A robust stability test is provided by evolving random noise data around Minkowski space-time. A strong field test is provided by the collapse of a periodic background of plane gravitational waves, as described by the Gowdy metric.

C. Bona; T. Ledvinka; C. Palenzuela; M. Žá?ek

2004-03-26T23:59:59.000Z

153

Spectral theorem and partial symmetries  

SciTech Connect (OSTI)

A novel method of the decompositon of a quantum system's Hamiltonian is presented. In this approach the criterion of the decomposition is determined by the symmetries possessed by the sub-Hamiltonians. This procedure is rather generic and independent of the actual global symmetry, or the lack of it, of the full Hamilton operator. A detailed investigation of the time evolution of the various sub-Hamiltonians, therefore the change in time of the symmetry of the physical object, is presented for the case of a vibrator-plus-rotor model. Analytical results are illustrated by direct numerical calculations.

Gozdz, A. [University of Maria Curie-Sklodowska, Department of Mathematical Physics, Institute of Physics (Poland); Gozdz, M. [University of Maria Curie-Sklodowska, Department of Complex Systems and Neurodynamics, Institute of Informatics (Poland)

2012-10-15T23:59:59.000Z

154

Symmetries of Quarks and Leptons  

Science Journals Connector (OSTI)

The course is divided in four Chapters corresponding to three lectures. After an introductory first chapter, the second deals with the symmetries of strong interactions from a quark point of view. We shall dis...

F. Gürsey

1979-01-01T23:59:59.000Z

155

Symmetries of the Einstein Equations  

E-Print Network [OSTI]

Generalized symmetries of the Einstein equations are infinitesimal transformations of the spacetime metric that formally map solutions of the Einstein equations to other solutions. The infinitesimal generators of these symmetries are assumed to be local, \\ie at a given spacetime point they are functions of the metric and an arbitrary but finite number of derivatives of the metric at the point. We classify all generalized symmetries of the vacuum Einstein equations in four spacetime dimensions and find that the only generalized symmetry transformations consist of: (i) constant scalings of the metric (ii) the infinitesimal action of generalized spacetime diffeomorphisms. Our results rule out a large class of possible ``observables'' for the gravitational field, and suggest that the vacuum Einstein equations are not integrable.

C. G. Torre; I. M. Anderson

1993-02-23T23:59:59.000Z

156

VARIATIONAL ESTIMATES FOR DISCRETE SCHR  

E-Print Network [OSTI]

­dimensional discrete SchrË?odinger operator. We prove that if # ess (H) # [-2, 2], then H-H 0 is compact and # ess (H V = 0. One of our main results in this paper is Theorem 1. If # ess (H) # [-2, 2], then V (n) # 0 that # ess (H) = [-2, 2] if and only if V (n) # 0. Our motivation for this result came from two sources

157

Symmetry groups of single-wall nanotubes  

Science Journals Connector (OSTI)

An approach to the determination of the symmetry groups of structural analogs of single-wall carbon nanotubes using ideas in color symmetry theory is described. The line group structures of the symmetry groups of BN, BC3, BCN and BC2N nanotubes are identified. An extension of the method to address nanotubes with non-hexagonal symmetry is also presented.

De Las Pe?as, M.L.A.N.

2013-11-26T23:59:59.000Z

158

Parity-time symmetry broken by point-group symmetry  

SciTech Connect (OSTI)

We discuss a parity-time (PT) symmetric Hamiltonian with complex eigenvalues. It is based on the dimensionless Schrödinger equation for a particle in a square box with the PT-symmetric potential V(x, y) = iaxy. Perturbation theory clearly shows that some of the eigenvalues are complex for sufficiently small values of |a|. Point-group symmetry proves useful to guess if some of the eigenvalues may already be complex for all values of the coupling constant. We confirm those conclusions by means of an accurate numerical calculation based on the diagonalization method. On the other hand, the Schrödinger equation with the potential V(x, y) = iaxy{sup 2} exhibits real eigenvalues for sufficiently small values of |a|. Point group symmetry suggests that PT-symmetry may be broken in the former case and unbroken in the latter one.

Fernández, Francisco M., E-mail: fernande@quimica.unlp.edu.ar; Garcia, Javier [INIFTA (UNLP, CCT La Plata-CONICET), División Química Teórica, Blvd. 113 S/N, Sucursal 4, Casilla de Correo 16, 1900 La Plata (Argentina)] [INIFTA (UNLP, CCT La Plata-CONICET), División Química Teórica, Blvd. 113 S/N, Sucursal 4, Casilla de Correo 16, 1900 La Plata (Argentina)

2014-04-15T23:59:59.000Z

159

Chiral Symmetry Breaking in Graphene  

E-Print Network [OSTI]

The question of whether the Coulomb interaction is strong enough to break the sublattice symmetry of un-doped graphene is discussed. We formulate a strong coupling expansion where the ground state of the Coulomb Hamiltonian is found exactly and the kinetic hopping Hamiltonian is treated as a perturbation. We argue that many of the properties of the resulting system would be shared by graphene with a Hubbard model interaction. In particular, the best candidate sublattice symmetry breaking ground state is an antiferromagnetic Mott insulator. We discuss the results of some numerical simulations which indicate that the Coulomb interaction is indeed subcritical. We also point out the curious fact that, if the electron did not have spin degeneracy, the tendency to break chiral symmetry would be much greater and even relatively weak Coulomb interactions would likely gap the spectrum.

Gordon W. Semenoff

2011-08-15T23:59:59.000Z

160

Robust Hydraulic Fracture Monitoring (HFM) of Multiple Time Overlapping Events Using a Generalized Discrete Radon Transform  

E-Print Network [OSTI]

In this work we propose a novel algorithm for multiple-event localization for Hydraulic Fracture Monitoring (HFM) through the exploitation of the sparsity of the observed seismic signal when represented in a basis consisting of space time propagators. We provide explicit construction of these propagators using a forward model for wave propagation which depends non-linearly on the problem parameters - the unknown source location and mechanism of fracture, time and extent of event, and the locations of the receivers. Under fairly general assumptions and an appropriate discretization of these parameters we first build an over-complete dictionary of generalized Radon propagators and assume that the data is well represented as a linear superposition of these propagators. Exploiting this structure we propose sparsity penalized algorithms and workflow for super-resolution extraction of time overlapping multiple seismic events from single well data.

Ely, Gregory

2013-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

The Broken Symmetry of Time  

SciTech Connect (OSTI)

This paper seeks to clarify features of time asymmetry in terms of symmetry breaking. It is observed that, in general, a contingent situation or event requires the breaking of an underlying symmetry. The distinction between the universal anisotropy of temporal processes and the irreversibility of certain physical processes is clarified. It is also proposed that the Transactional Interpretation of quantum mechanics offers an effective way to explain general thermodynamic asymmetry in terms of the time asymmetry of radiation, where prior such efforts have fallen short.

Kastner, Ruth E. [Department of Philosophy, University of Maryland, College Park, MD 20742 (United States)

2011-11-29T23:59:59.000Z

162

Doppler effect and Hubble effect in different models of space-time in the case of auto-parallel motion of the observer  

E-Print Network [OSTI]

Doppler effect and Hubble effect in different models of space-time in the case of auto-parallel motion of the observer are considered. The Doppler effect and shift frequency parameter are specialized for the case of auto-parallel motion of the observer. The Hubble effect and shift frequency parameter are considered for the same case. It is shown that by the use of the variation of the shift frequency parameter during a time perod, considered locally in the proper frame of reference of an observer, one can directly determine the centrifugal (centripetal) relative velocity and acceleration as well as the Coriolis relative velocity and acceleration of an astronomical object moving relatively to the observer. All results are obtained on purely kinematic basis without taking into account the dynamic reasons for the considered effect. PACS numbers: 98.80.Jk; 98.62.Py; 04.90.+e; 04.80.Cc

Sawa Manoff

2004-01-04T23:59:59.000Z

163

Towards Industrial Strength Discrete Optimization via Simulation...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Towards Industrial Strength Discrete Optimization via Simulation: Multi-Fidelity Optimization and Data-Driven Robustness Event Sponsor: Mathematics and Computing Science - LANS...

164

Discrete particle transport in porous media : discrete observations of physical mechanisms influencing particle behavior  

E-Print Network [OSTI]

An understanding of how discrete particles in the micron to submicron range behave in porous media is important to a number of environmental problems. Discrete particle behavior in the interior of a porous medium is complex ...

Yoon, Joon Sik, 1973-

2005-01-01T23:59:59.000Z

165

Continuous space-time transformations  

E-Print Network [OSTI]

We prove that every continuous map acting on the four-dimensional Minkowski space and preserving light cones in one direction only is either a Poincar\\'e similarity, that is, a product of a Lorentz transformation and a dilation, or it is of a very special degenerate form. In the presence of the continuity assumption the main tool in the proof is a basic result from the homotopy theory of spheres.

Clément de Seguins Pazzis; Peter Šemrl

2015-02-04T23:59:59.000Z

166

Testing Lorentz symmetry with atoms and Light  

E-Print Network [OSTI]

This article reports on the Fifth Meeting on CPT and Lorentz Symmetry, CPT'10, held at the end of June 2010 in Bloomington, Indiana, USA. The focus is on recent tests of Lorentz symmetry using atomic and optical physics.

Neil Russell

2011-09-04T23:59:59.000Z

167

Learning to profit with discrete investment rules  

Science Journals Connector (OSTI)

The learning of optimal discrete investment rules is analysed and related to the problem of forecasting financial returns. The aim is twofold: to characterize some `good' learning methods for agents using investment rules of this form and to explain why many observed investment rules such as technical trading rules are discrete. A consistent estimator for discrete investment rules is used and it is shown, using simulations, that direct estimation of investment rules is preferable to the estimation of forecasting models to be used in such rules. This model and the associated results indicate there are a number of reasons why it may be easier to learn a good discrete investment rule than to learn a continuous rule; this provides a partial explanation of why discrete investment rules are used so widely.

Spyros Skouras

2001-01-01T23:59:59.000Z

168

Extreme events in discrete nonlinear lattices  

E-Print Network [OSTI]

We perform statistical analysis on discrete nonlinear waves generated though modulational instability in the context of the Salerno model that interpolates between the intergable Ablowitz-Ladik (AL) equation and the nonintegrable discrete nonlinear Schrodinger (DNLS) equation. We focus on extreme events in the form of discrete rogue or freak waves that may arise as a result of rapid coalescence of discrete breathers or other nonlinear interaction processes. We find power law dependence in the wave amplitude distribution accompanied by an enhanced probability for freak events close to the integrable limit of the equation. A characteristic peak in the extreme event probability appears that is attributed to the onset of interaction of the discrete solitons of the AL equation and the accompanied transition from the local to the global stochasticity monitored through the positive Lyapunov exponent of a nonlinear map.

A. Maluckov; Lj. Hadzievski; N. Lazarides; G. P. Tsironis

2009-01-22T23:59:59.000Z

169

Quantised Angular Momentum Vectors and Projection Angle Distributions for Discrete  

E-Print Network [OSTI]

Quantised Angular Momentum Vectors and Projection Angle Distributions for Discrete Radon-integral angular momenta angle sets. Keywords: Discrete projection, tomography, digital angles, finite Radon that may be well suited to describe projections on discrete grids. The resulting angle sets

Boyer, Edmond

170

A Discrete Event Simulation Model For Unstructured Supervisory Control  

E-Print Network [OSTI]

A Discrete Event Simulation Model For Unstructured Supervisory Control Of Unmanned Vehicles Committee #12;2 A Discrete Event Simulation Model For Unstructured Supervisory Control Of Unmanned multipleoperator multiplevehicle discrete event simulation model (MOMUVDES) is developed which captures

Cummings, Mary "Missy"

171

Nuclear Potential and Symmetry Energy  

Science Journals Connector (OSTI)

A quadratic dependence on momentum is assumed for the two-nucleon interaction energy in the independent-particle model, and is used in a study of the nuclear binding energy and symmetry energy. The corresponding optical potentials for elastic nucleon scattering are discussed. The semiempirical interaction used is compared with the two-body potentials commonly used in shell-model calculations. These are found to be inadequate.

G. R. Satchler

1958-01-15T23:59:59.000Z

172

Nuclear Compressibility and Symmetry Energy  

Science Journals Connector (OSTI)

A modification and generalization of the Puff-Martin model for many-fermion systems is employed to calculate nuclear compressibility and symmetry energy in order to provide a practical test of the model and at the same time obtain useful information about these interesting quantities. An alternative, heuristic, derivation of the Puff-Martin equations is presented in order to exhibit the role of the exclusion principle. The condition stated for normal nuclear matter is that the mean binding energy be minimal (with respect to variation of the Fermi momentum) rather than the Puff-Martin condition that the mean binding energy equal the "single particle" energy at the Fermi surface. These two quantities differ from each other by the rearrangement energy, which is found to be 10 Mev. Employing Puff's potential (hard-shell potential plus a separable Yamaguchi potential, acting only in relative S states), satisfactory agreement is obtained with observed binding energy and density. The value of nuclear compressibility, 214 Mev, falls within the wide range of semiempirical values. The symmetry energy coefficient, 43 Mev, is larger, by 40-80%, than those usually quoted in semiempirical mass formulas. However, our value of the symmetry coefficient is the same as that calculated by Brueckner and Gammel in the absence of odd-state forces; they found the coefficient to be reduced to 26 Mev when a more realistic potential, including odd-state contributions, is employed.

David S. Falk and Lawrence Wilets

1961-12-15T23:59:59.000Z

173

Space?time scales of sound?speed perturbations observed in the Philippine Sea: Contributions from internal waves and tides, eddies, and spicy thermohaline structure.  

Science Journals Connector (OSTI)

The Philippine Sea is a dynamic ocean basin with complex multi?scale sound speed structure. Therefore the PhilSea09 and PhilSea10 experiments have put significant resources toward quantifying the space?time scales of this sound speed variability so that the acoustic transmission data can be properly interpreted. In the PhilSea09 pilot study two moorings equipped with temperature (T) conductivity (C) and pressure sensors along with upper ocean ADCP monitored ocean variability for a month in the Spring. The measurements reveal an energetic and nonlinear mixed diurnal?semidiurnal internal tide a diffuse Garrett–Munk (GM) type internal wave field at or above the reference GM energy level and a strong eddy field. One mooring which was equipped with pumped sensors for enhanced salinity (S) resolution was able to accurately quantify T and S variability along isopycnals (spice). The spice contribution to sound speed fluctuation is strong near the mixed layer but is significantly weaker than the other contributions in the main thermocline. Frequency spectra as well as vertical covariance functions will be presented to quantify the temporal and vertical spatial scales of the observed fluctuations.

John A. Colosi; Brian Dushaw; Rex K. Andrew; Lora J. Van Effelen; Matthew A. Dzieciuch; Peter F. Worcester

2010-01-01T23:59:59.000Z

174

Spontaneous symmetry breaking in Schroedinger lattices with two nonlinear sites  

SciTech Connect (OSTI)

We introduce discrete systems in the form of straight (infinite) and ring-shaped chains, with two symmetrically placed nonlinear sites. The systems can be implemented in nonlinear optics (as waveguiding arrays) and Bose-Einstein condensates (by means of an optical lattice). A full set of exact analytical solutions for symmetric, asymmetric, and antisymmetric localized modes is found, and their stability is investigated in a numerical form. The symmetry-breaking bifurcation, through which the asymmetric modes emerge from the symmetric ones, is found to be of the subcritical type. It is transformed into a supercritical bifurcation if the nonlinearity is localized in relatively broad domains around two central sites, and also in the ring of a small size, i.e., in effectively nonlocal settings. The family of antisymmetric modes does not undergo bifurcations and features both stable and unstable portions. The evolution of unstable localized modes is investigated by means of direct simulations. In particular, unstable asymmetric states, which exist in the case of the subcritical bifurcation, give rise to breathers oscillating between the nonlinear sites, thus restoring an effective dynamical symmetry between them.

Brazhnyi, Valeriy A.; Malomed, Boris A. [Centro de Fisica do Porto, Faculdade de Ciencias, Universidade do Porto, R. Campo Alegre 687, Porto 4169-007 (Portugal); ICFO-Institut de Ciencies Fotoniques, Universitat Politecnica de Catalunya, Mediterranean Technology Park, 08860 Castelldefels (Barcelona) (Spain) and Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 69978 (Israel)

2011-05-15T23:59:59.000Z

175

Hidden Rotational Symmetries in Magnetic Domain Patterns  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Hidden Rotational Symmetries in Hidden Rotational Symmetries in Magnetic Domain Patterns Hidden Rotational Symmetries in Magnetic Domain Patterns Print Wednesday, 27 June 2012 00:00 Magnetic thin films have complicated domain patterns that may or may not repeat with each cycle through a hysteresis loop. A magnetic thin film with perpendicular anisotropy, such as that used in computer hard drives, for example, commonly exhibits labyrinthine domain patterns. These patterns are disordered over a macroscopic length scale, and intuitively we do not expect to observe any symmetry in such systems. Scientists at the ALS, the University of Oregon, and the University of California, San Diego, have recently used coherent soft x-ray scattering with angular Fourier analysis to discover that the disordered domain patterns do, in fact, exhibit rotational symmetries, which can be as small as two-fold or as large as 30-fold. Their study of magnetic symmetries gives scientists a toolbox for discovering hidden symmetries in diverse material systems.

176

Pauli-Villars regulator as a nonperturbative ultraviolet regularization scheme in discretized light-cone quantization  

Science Journals Connector (OSTI)

We propose a solution to the problem of renormalizing light-cone Hamiltonian theories while maintaining Lorentz invariance and other symmetries. The method uses generalized Pauli-Villars regulators to render the theory finite. We discuss the method in the context of Yukawa theory at one loop and for a soluble model in 3+1 dimensions. The model is studied nonperturbatively. Numerical results obtained with use of discretized light-cone quantization, special integration weighting factors, and the complex symmetric Lanczos diagonalization algorithm compare well with the analytic answers.

Stanley J. Brodsky; John R. Hiller; Gary McCartor

1998-06-11T23:59:59.000Z

177

Isolation of Discrete Nanoparticle-DNA Conjugates for Plasmonic Applications  

E-Print Network [OSTI]

Isolation of Discrete Nanoparticle-DNA Conjugates forABSTRACT. Discrete DNA-gold nanoparticle conjugates with DNABG_Keywords”). GOLD, NANOPARTICLE, NANOCRYSTAL, PLASMON,

Claridge, Shelley

2008-01-01T23:59:59.000Z

178

The electron-phonon interaction from fundamental local gauge symmetries in solids  

E-Print Network [OSTI]

The elastic properties of solids are described in close analogy with General Relativity, by locally gauging the translational group of space-time. Electron interactions with the crystal lattice are thus generated by enforcing full gauge invariance, with the introduction of a gauge field. Elementary excitations are associated with the local gauge, contrasting to the usual interpretation as being Goldstone bosons emerging from global symmetry breaking. In the linear limit of the theory, the gauge field displays elastic waves, that we identify with acoustic phonons, when the field is quantized. Coupling with the electronic part of the system yields the standard electron-phonon interaction. If spin-orbit effects are included, unusual couplings emerge between the strain field and the electronic spin current, leading to novel physics that may be relevant for spintronic applications.

C. A. Dartora; G. G. Cabrera

2013-07-12T23:59:59.000Z

179

Localization and chiral symmetry in 2+1 flavor domain wall QCD  

SciTech Connect (OSTI)

We present results for the dependence of the residual mass of domain wall fermions (DWF) on the size of the fifth dimension and its relation to the density and localization properties of low-lying eigenvectors of the corresponding hermitian Wilson Dirac operator relevant to simulations of 2+1 flavor domain wall QCD. Using the DBW2 and Iwasaki gauge actions, we generate ensembles of configurations with a $16^3\\times 32$ space-time volume and an extent of 8 in the fifth dimension for the sea quarks. We demonstrate the existence of a regime where the degree of locality, the size of chiral symmetry breaking and the rate of topology change can be acceptable for inverse lattice spacings $a^{-1} \\ge 1.6$ GeV.

David J. Antonio; Kenneth C. Bowler; Peter A. Boyle; Norman H. Christ; Michael A. Clark; Saul D. Cohen; Chris Dawson; Alistair Hart; Balint Joó; Chulwoo Jung; Richard D. Kenway; Shu Li; Meifeng Lin; Robert D. Mawhinney; Christopher M. Maynard; Shigemi Ohta; Robert J. Tweedie; Azusa Yamaguchi

2008-01-01T23:59:59.000Z

180

Languages and semantics of grammatical discrete structures  

Science Journals Connector (OSTI)

Applying grammatical formalisms to engineering problems requires consideration of spatial, functional, and behavioral design attributes. This paper explores structural design languages and semantics for the generation of feasible and purposeful discrete ... Keywords: Design Languages, Engineering Grammars, Structural Layout, Structural Semantics

Kristina Shea; Jonathan Cagan

1999-09-01T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


181

From nothing to something: discrete integrable systems  

E-Print Network [OSTI]

Chinese ancient sage Laozi said that everything comes from `nothing'. Einstein believes the principle of nature is simple. Quantum physics proves that the world is discrete. And computer science takes continuous systems as discrete ones. This report is devoted to deriving a number of discrete models, including well-known integrable systems such as the KdV, KP, Toda, BKP, CKP, and special Viallet equations, from `nothing' via simple principles. It is conjectured that the discrete models generated from nothing may be integrable because they are identities of simple algebra, model-independent nonlinear superpositions of a trivial integrable system (Riccati equation), index homogeneous decompositions of the simplest geometric theorem (the angle bisector theorem), as well as the M\\"obious transformation invariants.

S Y Lou; Yu-qi Li; Xiao-yan Tang

2014-07-27T23:59:59.000Z

182

Discrete Polyhedrization of a Lattice Point Set  

Science Journals Connector (OSTI)

We introduce a polyhedral representation of surfaces for analysis and recognition of three-dimensional digital images. Our representation is basedon combinatorial topology. By using a discrete version of combinatorial topology we also present an algorithm ...

Yukiko Kenmochi; Atsushi Imiya

2001-01-01T23:59:59.000Z

183

Symmetry, Defects, and Gauging of Topological Phases  

E-Print Network [OSTI]

We examine the interplay of symmetry and topological order in $2+1$ dimensional topological phases of matter. We present a definition of the \\it topological symmetry \\rm group, which characterizes the symmetry of the emergent topological quantum numbers of a topological phase $\\mathcal{C}$, and describe its relation with the microscopic symmetry of the underlying physical system. We derive a general framework to classify symmetry fractionalization in topological phases, including non-Abelian phases and the possibility that the symmetries permute the quasiparticle types. We develop a theory of extrinsic defects (fluxes) associated with elements of the symmetry group, which provides a general classification of symmetry-enriched topological phases derived from a topological phase of matter $\\mathcal{C}$ with (on-site) symmetry group $G$. The algebraic theory of the defects, known as a $G$-crossed braided tensory category $\\mathcal{C}_{G}^{\\times}$, allows one to compute many properties, such as the number of topologically distinct types of defects associated with each group element, their fusion rules, quantum dimensions, zero modes, braiding exchange transformations, a generalized Verlinde formula for the defects, and modular transformations of the $G$-crossed extensions of topological phases. We also examine the promotion of the global symmetry to a local gauge invariance, wherein the extrinsic $G$-defects are turned into deconfined quasiparticle excitations, which results in a different topological phase $\\mathcal{C}/G$. A number of instructive and/or physically relevant examples are studied in detail.

Maissam Barkeshli; Parsa Bonderson; Meng Cheng; Zhenghan Wang

2014-10-16T23:59:59.000Z

184

Port-Hamiltonian systems on discrete manifolds  

E-Print Network [OSTI]

This paper offers a geometric framework for modeling port-Hamiltonian systems on discrete manifolds. The simplicial Dirac structure, capturing the topological laws of the system, is defined in terms of primal and dual cochains related by the coboundary operators. This finite-dimensional Dirac structure, as discrete analogue of the canonical Stokes-Dirac structure, allows for the formulation of finite-dimensional port-Hamiltonian systems that emulate the behaviour of the open distributed-parameter systems with Hamiltonian dynamics.

Marko Seslija; Jacquelien M. A. Scherpen; Arjan van der Schaft

2012-01-27T23:59:59.000Z

185

Discrete Plasmons in Finite Semiconductor Multilayers  

Science Journals Connector (OSTI)

We observe discrete plasmons in layered 2D electron gases with a large, but finte, number of periods. The twofold degeneracy of plasmon modes with wave numbers in the first Brillouin zone of the infinite system is lifted by the loss of complete periodicity in the finite system. These characteristic discrete plasmon doublets are measured in inelastic-light-scattering spectra of multilayer GaAs/(AlGa)As heterostructures.

A. Pinczuk; M. G. Lamont; A. C. Gossard

1986-05-12T23:59:59.000Z

186

R Symmetries in the Landscape  

E-Print Network [OSTI]

In the landscape, states with $R$ symmetries at the classical level form a distinct branch, with a potentially interesting phenomenology. Some preliminary analyses suggested that the population of these states would be significantly suppressed. We survey orientifolds of IIB theories compactified on Calabi-Yau spaces based on vanishing polynomials in weighted projective spaces, and find that the suppression is quite substantial. On the other hand, we find that a $Z_2$ R-parity is a common feature in the landscape. We discuss whether the cosmological constant and proton decay or cosmology might select the low energy branch. We include also some remarks on split supersymmetry.

M. Dine; Z. Sun

2005-06-28T23:59:59.000Z

187

Hidden Rotational Symmetries in Magnetic Domain Patterns  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Hidden Rotational Symmetries in Magnetic Domain Patterns Print Hidden Rotational Symmetries in Magnetic Domain Patterns Print Magnetic thin films have complicated domain patterns that may or may not repeat with each cycle through a hysteresis loop. A magnetic thin film with perpendicular anisotropy, such as that used in computer hard drives, for example, commonly exhibits labyrinthine domain patterns. These patterns are disordered over a macroscopic length scale, and intuitively we do not expect to observe any symmetry in such systems. Scientists at the ALS, the University of Oregon, and the University of California, San Diego, have recently used coherent soft x-ray scattering with angular Fourier analysis to discover that the disordered domain patterns do, in fact, exhibit rotational symmetries, which can be as small as two-fold or as large as 30-fold. Their study of magnetic symmetries gives scientists a toolbox for discovering hidden symmetries in diverse material systems.

188

Symmetry and Dirac points in graphene spectrum  

E-Print Network [OSTI]

Existence and stability of Dirac points in the dispersion relation of operators periodic with respect to the hexagonal lattice is investigated for different sets of additional symmetries. The following symmetries are considered: rotation by $2\\pi/3$ and inversion, rotation by $2\\pi/3$ and horizontal reflection, inversion or reflection with weakly broken rotation symmetry, and the case where no Dirac points arise: rotation by $2\\pi/3$ and vertical reflection. All proofs are based on symmetry considerations and are elementary in nature. In particular, existence of degeneracies in the spectrum is proved by a transplantation argument (which is deduced from the (co)representation of the relevant symmetry group). The conical shape of the dispersion relation is obtained from its invariance under rotation by $2\\pi/3$. Persistence of conical points when the rotation symmetry is weakly broken is proved using a geometric phase in one case and parity of the eigenfunctions in the other.

Gregory Berkolaiko; Andrew Comech

2014-12-28T23:59:59.000Z

189

Dynamics-dependent symmetries in Newtonian mechanics  

E-Print Network [OSTI]

We exhibit two symmetries of one-dimensional Newtonian mechanics whereby a solution is built from the history of another solution via a generally nonlinear and complex potential-dependent transformation of the time. One symmetry intertwines the square roots of the kinetic and potential energies and connects solutions of the same dynamical problem (the potential is an invariant function). The other symmetry connects solutions of different dynamical problems (the potential is a scalar function). The existence of corresponding conserved quantities is examined using Noethers theorem and it is shown that the invariant-potential symmetry is correlated with energy conservation. In the Hamilton-Jacobi picture the invariant-potential transformation provides an example of a field-dependent symmetry in point mechanics. It is shown that this transformation is not a symmetry of the Schroedinger equation.

Peter Holland

2014-09-19T23:59:59.000Z

190

Time-Symmetric Discretization of The Harmonic Oscillator  

SciTech Connect (OSTI)

We explicitly and analytically demonstrate that simple time-symmetric discretization of the harmonic oscillator (used as a simple model of a discrete dynamical system), leads to discrete equations of motion whose solutions are perfectly stable at all time scales, and whose energy is exactly conserved. This result is important for both fundamental discrete physics, as well as for numerical analysis and simulation.

Antippa, Adel F. [Departement de Physique Universite du Quebec a Trois-Rivieres Trois-Rivieres, Quebec, G9A 5H7 (Canada); Dubois, Daniel M. [Centre for Hyperincursion and Anticipation in Ordered Systems, CHAOS asbl, Institute of Mathematics, B37, University of Liege Grande Traverse 12, B-4000 LIEGE 1 (Belgium)

2010-11-24T23:59:59.000Z

191

Inflation, Symmetry, and B-Modes  

E-Print Network [OSTI]

We examine the role of using symmetry and effective field theory in inflationary model building. We describe the standard formulation of starting with an approximate shift symmetry for a scalar field, and then introducing corrections systematically in order to maintain control over the inflationary potential. We find that this leads to models in good agreement with recent data. On the other hand, there are attempts in the literature to deviate from this paradigm by envoking other symmetries and corrections. In particular: in a suite of recent papers, several authors have made the claim that standard Einstein gravity with a cosmological constant and a massless scalar carries conformal symmetry. They further claim that such a theory carries another hidden symmetry; a global SO(1,1) symmetry. By deforming around the global SO(1,1) symmetry, they are able to produce a range of inflationary models with asymptotically flat potentials, whose flatness is claimed to be protected by these symmetries. These models tend to give rise to B-modes with small amplitude. Here we explain that these authors are merely introducing a redundancy into the description, not an actual conformal symmetry. Furthermore, we explain that the only real (global) symmetry in these models is not at all hidden, but is completely manifest when expressed in the Einstein frame; it is in fact the shift symmetry of a scalar field. When analyzed systematically as an effective field theory, deformations do not generally produce asymptotically flat potentials and small B-modes, but other types of potentials with B-modes of large amplitude; nicely compatible with recent BICEP2 data. Such simple models typically also produce the observed red spectral index, Gaussian fluctuations, etc. In short: simple models of inflation, organized by expanding around a shift symmetry, are in excellent agreement with recent data.

Mark P. Hertzberg

2014-03-20T23:59:59.000Z

192

Neutron star properties and the symmetry energy  

E-Print Network [OSTI]

The effect of the symmetry energy on the properties of compact stars is discussed. It is shown that, for stars with masses above 1 $M_\\odot$, the radius of the star varies linearly with the symmetry energy slope $L$. The dependence of the hyperon content and onset density of the direct Urca process on the symmetry energy and meson coupling parametrization are also analyzed.

Rafael Cavagnoli; Constança Providência; Debora P. Menezes

2011-08-08T23:59:59.000Z

193

Contact Symmetries and Hamiltonian Thermodynamics  

E-Print Network [OSTI]

In this work we analyze several aspects of the application of contact geometry to thermodynamics. We first investigate the role of gauge transformations and Legendre symmetries in thermodynamics, with respect to both the contact and the metric structures. Then we present a novel mathematical characterization of first order phase transitions as equilibrium processes on the thermodynamic phase space for which the Legendre symmetry is broken. Moreover, using contact Hamiltonian dynamics, we propose a formalism for thermodynamics that resembles the classical Hamiltonian formulation of conservative mechanics. We find out the general functional form for the relevant contact Hamiltonian in thermodynamics and show that it is a measure of the entropy production along thermodynamic processes. Therefore, we use such property to give a precise definition of thermodynamically admissible processes according to the Second Law of thermodynamics. Finally, we also show that we can give an equivalent formulation in terms of the Fisher-Rao metric, in analogy with the Theory of Relativity, where the metric structure defines admissible paths.

A. Bravetti; C. S. Lopez-Monsalvo; F. Nettel

2014-09-25T23:59:59.000Z

194

Symmetries and Renormalization of Noncommutative Field Theory  

SciTech Connect (OSTI)

An overview of recent developments in the renormalization and in the implementation of spacetime symmetries of noncommutative field theory is presented, and argued to be intimately related.

Szabo, Richard J. [Department of Mathematics, Heriot-Watt University, Colin Maclaurin Building, Riccarton, Edinburgh EH14 4AS (United Kingdom); Maxwell Institute for Mathematical Sciences, Heriot-Watt University, Colin Maclaurin Building, Riccarton, Edinburgh EH14 4AS (United Kingdom)

2007-06-19T23:59:59.000Z

195

Evidence for tetrahedral symmetry in 16O  

E-Print Network [OSTI]

We derive the rotation-vibration spectrum of a 4-alpha configuration with tetrahedral symmetry, T_d, and show evidence for the occurrence of this symmetry in the low-lying spectrum of 16O. All vibrational states with A, E and F symmetry appear to have been observed, as well as the rotational bands with L(P)=0(+), 3(-), 4(+), 6(+) on the A states, and part of the rotational bands built on the E, F states. We derive analytic expressions for the form factors and B(EL) values of the ground state rotational band and show that the measured values support the tetrahedral symmetry of this band.

R. Bijker; F. Iachello

2014-03-26T23:59:59.000Z

196

Evidence for tetrahedral symmetry in 16O  

E-Print Network [OSTI]

We derive the rotation-vibration spectrum of a 4-alpha configuration with tetrahedral symmetry, T_d, and show evidence for the occurrence of this symmetry in the low-lying spectrum of 16O. All vibrational states with A, E and F symmetry appear to have been observed, as well as the rotational bands with L(P)=0(+), 3(-), 4(+), 6(+) on the A states, and part of the rotational bands built on the E, F states. We derive analytic expressions for the form factors and B(EL) values of the ground state rotational band and show that the measured values support the tetrahedral symmetry of this band.

Bijker, R

2014-01-01T23:59:59.000Z

197

Symmetry energy in nuclear density functional theory  

E-Print Network [OSTI]

The nuclear symmetry energy represents a response to the neutron-proton asymmetry. In this survey we discuss various aspects of symmetry energy in the framework of nuclear density functional theory, considering both non-relativistic and relativistic self-consistent mean-field realizations side-by-side. Key observables pertaining to bulk nucleonic matter and finite nuclei are reviewed. Constraints on the symmetry energy and correlations between observables and symmetry-energy parameters, using statistical covariance analysis, are investigated. Perspectives for future work are outlined in the context of ongoing experimental efforts.

W. Nazarewicz; P. -G. Reinhard; W. Satula; D. Vretenar

2013-07-22T23:59:59.000Z

198

Issues in standard model symmetry breaking  

SciTech Connect (OSTI)

This work discusses the symmetry breaking sector of the SU(2) x U(1) electroweak model. The first two chapters discuss Higgs masses in two simple Higgs models. The author proves low-enery theorems for the symmetry breaking sector: The threshold behavior of gauge-boson scattering is completely determined, whenever the symmetry breaking sector meets certain simple conditions. The author uses these theorems to derive event rates for the superconducting super collider (SSC). The author shows that the SSC may be able to determine whether the interactions of the symmetry breaking sector are strong or weak. 54 refs.

Golden, M.

1988-04-01T23:59:59.000Z

199

Energy Levels of "Hydrogen Atom" in Discrete Time Dynamics  

E-Print Network [OSTI]

We analyze dynamical consequences of a conjecture that there exists a fundamental (indivisible) quant of time. In particular we study the problem of discrete energy levels of hydrogen atom. We are able to reconstruct potential which in discrete time formalism leads to energy levels of unperturbed hydrogen atom. We also consider linear energy levels of quantum harmonic oscillator and show how they are produced in the discrete time formalism. More generally, we show that in discrete time formalism finite motion in central potential leads to discrete energy spectrum, the property which is common for quantum mechanical theory. Thus deterministic (but discrete time!) dynamics is compatible with discrete energy levels.

Andrei Khrennikov; Yaroslav Volovich

2006-04-27T23:59:59.000Z

200

From Asymmetry to Full Symmetry: New Techniques for Symmetry Reduction in Model Checking  

Science Journals Connector (OSTI)

It is often the case that systems are “nearly symmetric”; they exhibit symmetry in a part of their description but are, nevertheless, globally asymmetric. We formalize several notions of near symmetry and show...

E. Allen Emerson; 1]Richard J. Trefler

1999-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


201

A H-infinity Fault Detection and Diagnosis Scheme for Discrete Nonlinear System Using Output Probability Density Estimation  

SciTech Connect (OSTI)

In this paper, a H-infinity fault detection and diagnosis (FDD) scheme for a class of discrete nonlinear system fault using output probability density estimation is presented. Unlike classical FDD problems, the measured output of the system is viewed as a stochastic process and its square root probability density function (PDF) is modeled with B-spline functions, which leads to a deterministic space-time dynamic model including nonlinearities, uncertainties. A weighting mean value is given as an integral function of the square root PDF along space direction, which leads a function only about time and can be used to construct residual signal. Thus, the classical nonlinear filter approach can be used to detect and diagnose the fault in system. A feasible detection criterion is obtained at first, and a new H-infinity adaptive fault diagnosis algorithm is further investigated to estimate the fault. Simulation example is given to demonstrate the effectiveness of the proposed approaches.

Zhang Yumin; Lum, Kai-Yew [Temasek Laboratories, National University of Singapore, Singapore 117508 (Singapore); Wang Qingguo [Depa. Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore)

2009-03-05T23:59:59.000Z

202

Invisibility and PT-symmetry  

E-Print Network [OSTI]

For a general complex scattering potential defined on a real line, we show that the equations governing invisibility of the potential are invariant under the combined action of parity and time-reversal (PT) transformation. We determine the PT-symmetric an well as non-PT-symmetric invisible configurations of an easily realizable exactly solvable model that consists of a two-layer planar slab consisting of optically active material. Our analysis shows that although PT-symmetry is neither necessary nor sufficient for the invisibility of a scattering potential, it plays an important role in the characterization of the invisible configurations. A byproduct of our investigation is the discovery of certain configurations of our model that are effectively reflectionless in a spectral range as wide as several hundred nanometers.

Ali Mostafazadeh

2012-06-01T23:59:59.000Z

203

PT-symmetry in honeycomb photonic lattices  

SciTech Connect (OSTI)

We apply gain and loss to honeycomb photonic lattices and show that the dispersion relation is identical to tachyons--particles with imaginary mass that travel faster than the speed of light. This is accompanied by -symmetry breaking in this structure. We further show that the -symmetry can be restored by deforming the lattice.

Szameit, Alexander; Rechtsman, Mikael C.; Bahat-Treidel, Omri; Segev, Mordechai [Physics Department and Solid State Institute, Technion, 32000 Haifa (Israel)

2011-08-15T23:59:59.000Z

204

Lie symmetries and 2D Material Physics  

E-Print Network [OSTI]

Inspired from Lie symmetry classification, we establish a correspondence between rank two Lie symmetries and 2D material physics. The material unit cell is accordingly interpreted as the geometry of a root system. The hexagonal cells, appearing in graphene like models, are analyzed in some details and are found to be associated with A_2 and G_2 Lie symmetries. This approach can be applied to Lie supersymmetries associated with fermionic degrees of freedom. It has been suggested that these extended symmetries can offer a new way to deal with doping material geometries. Motivated by Lie symmetry applications in high energy physics, we speculate on a possible connection with (p,q) brane networks used in the string theory compactification on singular Calabi-Yau manifolds.

Adil Belhaj; Moulay Brahim Sedra

2014-04-18T23:59:59.000Z

205

Exploiting Matrix Symmetries and Physical Symmetries in Matrix Product States and Tensor Trains  

E-Print Network [OSTI]

We focus on symmetries related to matrices and vectors appearing in the simulation of quantum many-body systems. Spin Hamiltonians have special matrix-symmetry properties such as persymmetry. Furthermore, the systems may exhibit physical symmetries translating into symmetry properties of the eigenvectors of interest. Both types of symmetry can be exploited in sparse representation formats such as Matrix Product States (MPS) for the desired eigenvectors. This paper summarizes symmetries of Hamiltonians for typical physical systems such as the Ising model and lists resulting properties of the related eigenvectors. Based on an overview of Matrix Product States (Tensor Trains or Tensor Chains) and their canonical normal forms we show how symmetry properties of the vector translate into relations between the MPS matrices and, in turn, which symmetry properties result from relations within the MPS matrices. In this context we analyze different kinds of symmetries and derive appropriate normal forms for MPS representing these symmetries. Exploiting such symmetries by using these normal forms will lead to a reduction in the number of degrees of freedom in the MPS matrices. This paper provides a uniform platform for both well-known and new results which are presented from the (multi-)linear algebra point of view.

T. Huckle; K. Waldherr; T. Schulte-Herbrueggen

2013-01-04T23:59:59.000Z

206

Scalar Field Theories with Polynomial Shift Symmetries  

E-Print Network [OSTI]

We continue our study of naturalness in nonrelativistic QFTs of the Lifshitz type, focusing on scalar fields that can play the role of Nambu-Goldstone (NG) modes associated with spontaneous symmetry breaking. Such systems allow for an extension of the constant shift symmetry to a shift by a polynomial of degree $P$ in spatial coordinates. These "polynomial shift symmetries" in turn protect the technical naturalness of modes with a higher-order dispersion relation, and lead to a refinement of the proposed classification of infrared Gaussian fixed points available to describe NG modes in nonrelativistic theories. Generic interactions in such theories break the polynomial shift symmetry explicitly to the constant shift. It is thus natural to ask: Given a Gaussian fixed point with polynomial shift symmetry of degree $P$, what are the lowest-dimension operators that preserve this symmetry, and deform the theory into a self-interacting scalar field theory with the shift symmetry of degree $P$? To answer this (essen...

Griffin, Tom; Horava, Petr; Yan, Ziqi

2014-01-01T23:59:59.000Z

207

Discrete Optimization A simulated annealing approach  

E-Print Network [OSTI]

for the constrained and the unconstrained circular cutting problem based upon simulated annealing. We define an energyDiscrete Optimization A simulated annealing approach for the circular cutting problem Mhand Hifi corner of the initial rectangle. Such values of the energy correspond to configurations where pieces

Zissimopoulos, Vassilis

208

Massively Parallel Computation of Discrete Logarithms \\Lambda  

E-Print Network [OSTI]

an order of magnitude using such an analysis. Among the reasons for this are: ffl if a high­level language, keeping in mind that log g a is only determined modulo the multiplicative order of g. For general be extremely useful to chart the increase in difficulty of computing discrete logarithms as the field size

McCurley, Kevin

209

Massively Parallel Computation of Discrete Logarithms  

E-Print Network [OSTI]

an order of magnitude using such an analysis. Among the reasons for this are: · if a high-level language, keeping in mind that logg a is only determined modulo the multiplicative order of g. For general be extremely useful to chart the increase in difficulty of computing discrete logarithms as the field size

Gordon, Dan

210

Comment on ``Discrete Boltzmann Equation for Microfluidics''  

E-Print Network [OSTI]

Comment on ``Discrete Boltzmann Equation for Microfluidics'' In a recent Letter [1], Li and Kwok use a lattice Boltzmann equation (LBE) for microfluidics. Their main claim is that an LBE model for microfluidics can be constructed based on the ``Bhatnagar-Gross-Kooky [sic]'' model by including ``the

Luo, Li-Shi

211

Quantum Gravity Phenomenology, Lorentz Invariance and Discreteness  

E-Print Network [OSTI]

Quantum Gravity Phenomenology, Lorentz Invariance and Discreteness Fay Dowker #3; , Joe Henson y invariant, and we recall the reasons why. For illustration, we introduce a phenomenological model of massive { LLI violating phenomenological e#11;ects of quantum gravity { has grown up around this idea

Sorkin, Rafael Dolnick

212

On the discrete bicycle transformation S. Tabachnikov  

E-Print Network [OSTI]

On the discrete bicycle transformation S. Tabachnikov E. Tsukerman 1 Introduction The motivation for this paper comes from the study of a simple model of bicycle motion. The bicycle is modeled as an oriented segment in the plane of fixed length , the wheelbase of the bicycle. The motion is constrained so

Tabachnikov, Sergei

213

Non-Noether symmetries of the modified Boussinesq equations  

Science Journals Connector (OSTI)

We investigate a one-parameter non-Noether symmetry group of the modified Boussinesq equations and show that this symmetry naturally...

G. Chavchanidze

2009-08-01T23:59:59.000Z

214

Symmetry-Driven Spontaneous Self-assembly of Nanoscale Ceria...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Symmetry-Driven Spontaneous Self-assembly of Nanoscale Ceria Building Blocks to Fractal Super-octahedra. Symmetry-Driven Spontaneous Self-assembly of Nanoscale Ceria Building...

215

Graphene, Lattice QFT and Symmetries  

E-Print Network [OSTI]

Borrowing ideas from tight binding model, we propose a board class of Lattice QFT models that are classified by the ADE Lie algebras. In the case of su(N) series, we show that the couplings between the quantum states living at the first nearest neighbor sites of the lattice $\\mathcal{L}_{su(N)}$ are governed by the complex fundamental representations \\underline{${{\\mathbf{N}}}$} and $\\bar{{\\mathbf{N}}}$ of $su(N)$; and the second nearest neighbor interactions are described by its adjoint $\\underline{\\mathbf{N}} \\otimes \\bar{\\mathbf{N}}$. The lattice models associated with the leading su(2), su(3) and su(4) cases are explicitly studied and their fermionic field realizations are given. It is also shown that the su(2) and su(3) models describe respectively the electronic properties of the acetylene chain and the graphene. It is established as well that the energy dispersion of the first nearest neighbor couplings is completely determined by the $A_{N}$ roots $ \\mathbf{\\alpha}$ through the typical dependence $N/2+\\sum_{roots}\\cos(\\mathbf{k}.\\alpha) $ with $\\mathbf{k}$ the wave vector. Other features such as DE extension and other applications are also discussed. Keywords: Tight Binding Model, Graphene, Lattice QFT, ADE Symmetries.

L. B Drissi; E. H Saidi; M. Bousmina

2011-01-05T23:59:59.000Z

216

Defining Employee Perceptions of Discretion: When, Where, and How  

E-Print Network [OSTI]

The construct employee discretion has been researched under many labels (e.g., flexibility, autonomy). As a result, employee discretion has been operationalized differently across multiple streams of research leading to construct deficiency...

Thompson, Rebecca Jean

2013-12-10T23:59:59.000Z

217

Symmetry of single-wall nanotubes  

Science Journals Connector (OSTI)

A review of the symmetry groups of the various single-wall nano- and microtubes considered in the literature (BN, GaN, MS2, C, BC3, BC2N) is presented.

Damnjanovic, M.

2001-04-27T23:59:59.000Z

218

Symmetry breaking and the deconstruction of mass  

Science Journals Connector (OSTI)

...issue Before, behind and beyond the discovery of the Higgs boson. organised and edited by John Ellis, Tejinder Virdee...Issue Before, behind and beyond the discovery of the Higgs boson . We briefly review some of the connections between symmetry...

2015-01-01T23:59:59.000Z

219

Symmetries and Interaction coefficients of Kelvin waves  

E-Print Network [OSTI]

We considered symmetry restriction on the interaction coefficients of Kelvin waves and demonstrated that linear in small wave vector asymptotic is not forbidden, as one can expect by naive reasoning.

Vladimir V. Lebedev; Victor S. L'vov

2010-05-25T23:59:59.000Z

220

Symmetry energy coefficients for asymmetric nuclear matter  

E-Print Network [OSTI]

Symmetry energy coefficients of asymmetric nuclear matter are investigated as the inverse of nuclear matter polarizabilities with two different approaches. Firstly a general calculation shows they may depend on the neutron-proton asymmetry itself. The choice of particular prescriptions for the density fluctuations lead to certain isospin (n-p asymmetry) dependences of the polarizabilities. Secondly, with Skyrme type interactions, the static limit of the dynamical polarizability is investigated corresponding to the inverse symmetry energy coefficient which assumes different values at different asymmetries (and densities and temperatures). The symmetry energy coefficient (in the isovector channel) is found to increase as n-p asymmetries increase. The spin symmetry energy coefficient is also briefly investigated.

Fábio L. Braghin

2003-12-16T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


221

Symmetry violations at BaBar  

E-Print Network [OSTI]

Following a brief introduction I report the current status of symmetry violation tests from the BaBar experiment, including recent results on the measurement of T violation, and searches for CP and T violation in mixing.

Adrian J. Bevan

2014-11-02T23:59:59.000Z

222

External breaking of ground-state symmetry  

Science Journals Connector (OSTI)

Ground-state symmetry can be broken by an external field. The threshold value of the symmetry-breaking field may be roughly estimated by comparing experimentally the behavior of two identical physical quantities, as functions of the field, for the set of field directions equivalent, with respect to the action, to a group generator. The kinetic coefficients as the functions of magnetic induction B are used as an illustration.

S. Malinowski

1994-01-01T23:59:59.000Z

223

Discrete Green's functions University of California, San Diego  

E-Print Network [OSTI]

Discrete Green's functions Fan Chung University of California, San Diego La Jolla, CA 92093-0112 S study discrete Green's functions and their relationship with discrete Laplace equations. Several methods for deriving Green's functions are discussed. Green's functions can be used to deal with diffusion

Graham, Fan Chung

224

Fractional Zaslavsky and Henon Discrete Maps  

E-Print Network [OSTI]

This paper is devoted to the memory of Professor George M. Zaslavsky passed away on November 25, 2008. In the field of discrete maps, George M. Zaslavsky introduced a dissipative standard map which is called now the Zaslavsky map. G. Zaslavsky initialized many fundamental concepts and ideas in the fractional dynamics and kinetics. In this paper, starting from kicked damped equations with derivatives of non-integer orders we derive a fractional generalization of discrete maps. These fractional maps are generalizations of the Zaslavsky map and the Henon map. The main property of the fractional differential equations and the correspondent fractional maps is a long-term memory and dissipation. The memory is realized by the fact that their present state evolution depends on all past states with special forms of weights.

Vasily E. Tarasov

2011-07-26T23:59:59.000Z

225

Symmetry and Covariance of Non-relativistic Quantum Mechanics  

E-Print Network [OSTI]

On the basis of a 5-dimensional form of space-time transformations non-relativistic quantum mechanics is reformulated in a manifestly covariant manner. The resulting covariance resembles that of the conventional relativistic quantum mechanics.

Minoru Omote; Susumu Kamefuchi

2000-05-10T23:59:59.000Z

226

Symmetry Energy I: Semi-Infinite Matter  

E-Print Network [OSTI]

Energy for a nucleus is considered in macroscopic limit, in terms of nucleon numbers. Further considered for a nuclear system is the Hohenberg-Kohn energy functional, in terms of proton and neutron densities. Finally, Skyrme-Hartree-Fock calculations are carried out for a half-infinite particle-stable nuclear-matter. In each case, the attention is focused on the role of neutron-proton asymmetry and on the nuclear symmetry energy. We extend the considerations on the symmetry term from an energy formula to the respective term in the Hohenberg-Kohn functional. We show, in particular, that in the limit of an analytic functional, and subject to possible Coulomb corrections, it is possible to construct isoscalar and isovector densities out of the proton and neutron densities, that retain a universal relation to each other, approximately independent of asymmetry. In the so-called local approximation, the isovector density is inversely proportional to the symmetry energy in uniform matter at the local isoscalar density. Generalized symmetry coefficient of a nuclear system is related, in the analytic limit of a functional, to an integral of the isovector density. We test the relations, inferred from the Hohenberg-Kohn functional, in the Skyrme-Hartree-Fock calculations of half-infinite matter. Within the calculations, we obtain surface symmetry coefficients and parameters characterizing the densities, for the majority of Skyrme parameterizations proposed in the literature. The volume-to-surface symmetry-coefficient ratio and the displacement of nuclear isovector relative to isoscalar surfaces both strongly increase as the slope of symmetry energy in the vicinity of normal density increases.

Pawel Danielewicz; Jenny Lee

2008-07-23T23:59:59.000Z

227

Universal symmetry-protected topological invariants for symmetry-protected topological states  

E-Print Network [OSTI]

Symmetry-protected topological (SPT) states are short-range entangled states with a symmetry G. They belong to a new class of quantum states of matter which are classified by the group cohomology $H^{d+1}(G,\\mathbb{R}/\\mathbb{Z})$ in d-dimensional space. In this paper, we propose a class of symmetry- protected topological invariants that may allow us to fully characterize SPT states with a symmetry group G (ie allow us to measure the cocycles in $H^{d+1}(G,\\mathbb{R}/\\mathbb{Z})$ that characterize the SPT states). We give an explicit and detailed construction of symmetry-protected topological invariants for 2+1D SPT states. Such a construction can be directly generalized to other dimensions.

Hung, Ling-Yan

2013-01-01T23:59:59.000Z

228

Symmetry Energy II: Isobaric Analog States  

E-Print Network [OSTI]

Using excitation energies to isobaric analog states (IAS) and charge invariance, we extract nuclear symmetry coefficients, from a mass formula, on a nucleus-by-nucleus basis. Consistently with charge invariance, the coefficients vary weakly across an isobaric chain. However, they change strongly with nuclear mass and range from a_a~10 MeV at mass A~10 to a_a~22 MeV at A~240. Following the considerations of a Hohenberg-Kohn functional for nuclear systems, we determine how to find in practice the symmetry coefficient using neutron and proton densities, even when those densities are simultaneously affected by significant symmetry-energy and Coulomb effects. These results facilitate extracting the symmetry coefficients from Skyrme-Hartree-Fock (SHF) calculations, that we carry out using a variety of Skyrme parametrizations in the literature. For the parametrizations, we catalog novel short-wavelength instabilities. In comparing the SHF and IAS results for the symmetry coefficients, we arrive at narrow (+-2.4 MeV)...

Danielewicz, Pawel

2014-01-01T23:59:59.000Z

229

Eugene Wigner and Fundamental Symmetry Principles  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Eugene Wigner and Fundamental Symmetry Principles Eugene Wigner and Fundamental Symmetry Principles Patents · Resources with Additional Information · Wigner Honored "[Eugene P.] Wigner's great contribution to science, for which he won the Nobel Prize in Physics in 1963, was his insight into the fundamental mathematics and physics of quantum mechanics. He applied and extended the mathematical theory of groups to the quantum world of the atom; specifically, he used group theory to organize the quantum energy levels of electrons in atoms in a way that is now standard. With that mathematical approach to the atom, Wigner became one of the first to apprehend the deep implications of symmetry, which has since emerged as one, if not the, key principle of 20th-century theoretical physics. ... Eugene P. Wigner

230

symmetry magazine | dimensions of particle physics  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

symmetry magazine symmetry magazine symmetry magazine dimensions of particle physics dimensions of particle physics A joint Fermilab/SLAC publication Search form Search Search Facebook Twitter RSS Feed subscribe masthead contact Home Departments application breaking commentary contest Day in the life Deconstruction Essay explain it in 60 seconds feature gallery Logbook Signal to background Science Topics applied science astrophysics Cosmic Frontier dark energy dark matter Energy Frontier extra dimensions Higgs boson Intensity Frontier neutrinos underground science Image Bank Archives Full Archives PDF Issues Print Editions sections subscribe application breaking commentary contest day in the life deconstruction essay explain it in 60 seconds feature gallery logbook signal to background Full Archives PDF Issues Print Editions

231

Quantum reference frames and deformed symmetries  

SciTech Connect (OSTI)

In the context of constrained quantum mechanics, reference systems are used to construct relational observables that are invariant under the action of the symmetry group. Upon measurement of a relational observable, the reference system undergoes an unavoidable measurement 'back-action' that modifies its properties. In a quantum-gravitational setting, it has been argued that such a back-action may produce effects that are described at an effective level as a form of deformed (or doubly) special relativity. We examine this possibility using a simple constrained system that has been extensively studied in the context of quantum information. While our conclusions support the idea of a symmetry deformation, they also reveal a host of other effects that may be relevant to the context of quantum gravity, and could potentially conceal the symmetry deformation.

Girelli, Florian [SISSA, Via Beirut 2-4, 34014 Trieste (Italy) and INFN, Sezione di Trieste, Trieste (Italy); Poulin, David [Center for the Physics of Information, California Institute of Technology, Pasadena, CA 91125 (United States)

2008-05-15T23:59:59.000Z

232

Quantum reference frames and deformed symmetries  

Science Journals Connector (OSTI)

In the context of constrained quantum mechanics, reference systems are used to construct relational observables that are invariant under the action of the symmetry group. Upon measurement of a relational observable, the reference system undergoes an unavoidable measurement “back-action” that modifies its properties. In a quantum-gravitational setting, it has been argued that such a back-action may produce effects that are described at an effective level as a form of deformed (or doubly) special relativity. We examine this possibility using a simple constrained system that has been extensively studied in the context of quantum information. While our conclusions support the idea of a symmetry deformation, they also reveal a host of other effects that may be relevant to the context of quantum gravity, and could potentially conceal the symmetry deformation.

Florian Girelli and David Poulin

2008-05-12T23:59:59.000Z

233

Symmetry Energy I: Semi-Infinite Matter  

E-Print Network [OSTI]

Nuclear energy is considered in the macroscopic limit for a nucleus. Considered, further, is the Hohenberg-Kohn functional for a nuclear system, in terms of proton and neutron densities. Finally, Skyrme-Hartree-Fock calculations are carried out for half-infinite particle-stable nuclear matter. In each case, the attention is focused on the role of neutron-proton asymmetry and on the symmetry energy. We extend the considerations on the symmetry term from an energy formula to the respective term in the Hohenberg-Kohn functional. We show, in particular, that in continuum limit of the considered functional, and subject to possible Coulomb corrections, it is possible to construct isoscalar and isovector densities out of the proton and neutron densities, that retain a universal relation to each other, approximately independent of asymmetry. In the so-called local approximation, the isovector density is inversely proportional to the symmetry energy in uniform matter at the local isoscalar density. Generalized symmetr...

Danielewicz, Pawel

2008-01-01T23:59:59.000Z

234

Symmetry Energy II: Isobaric Analog States  

E-Print Network [OSTI]

Using excitation energies to isobaric analog states (IAS) and charge invariance, we extract nuclear symmetry coefficients, from a mass formula, on a nucleus-by-nucleus basis. Consistently with charge invariance, the coefficients vary weakly across an isobaric chain. However, they change strongly with nuclear mass and range from a_a~10 MeV at mass A~10 to a_a~22 MeV at A~240. Following the considerations of a Hohenberg-Kohn functional for nuclear systems, we determine how to find in practice the symmetry coefficient using neutron and proton densities, even when those densities are simultaneously affected by significant symmetry-energy and Coulomb effects. These results facilitate extracting the symmetry coefficients from Skyrme-Hartree-Fock (SHF) calculations, that we carry out using a variety of Skyrme parametrizations in the literature. For the parametrizations, we catalog novel short-wavelength instabilities. In comparing the SHF and IAS results for the symmetry coefficients, we arrive at narrow (+-2.4 MeV) constraints on the symmetry energy values S(rho) at 0.04

Pawel Danielewicz; Jenny Lee

2013-07-15T23:59:59.000Z

235

Compartmentalization analysis using discrete fracture network models  

SciTech Connect (OSTI)

This paper illustrates how Discrete Fracture Network (DFN) technology can serve as a basis for the calculation of reservoir engineering parameters for the development of fractured reservoirs. It describes the development of quantitative techniques for defining the geometry and volume of structurally controlled compartments. These techniques are based on a combination of stochastic geometry, computational geometry, and graph theory. The parameters addressed are compartment size, matrix block size and tributary drainage volume. The concept of DFN models is explained and methodologies to compute these parameters are demonstrated.

La Pointe, P.R.; Eiben, T.; Dershowitz, W. [Golder Associates Inc., Redmond, WA (United States); Wadleigh, E. [Marathon Oil Company, Midland, TX (United States). Mid-Continent Region Production

1997-12-31T23:59:59.000Z

236

Robustness of discrete-time control systems  

E-Print Network [OSTI]

. The Bilinear Approach s-Plane to z-Plane F. Overbounding and Testing for Stability G. Interlacing Properties of Interval Polynomials Interlacing Property for Continuous- Time Systems Interlacing Property for Discrete- Time Systems Page 26 27 29 33... of p(z) from F(+t) Calculation of s+q Calculation of s~i Calculation of the Minimum Distance of p(z) from P&? Calculation of s Calculation of s Calculation of the Minimum Distance of p(z) from Flsi Calculation of ss Calculation of ss E...

Aguirre, Gabriel

1989-01-01T23:59:59.000Z

237

Compartmentalization analysis using discrete fracture network models  

SciTech Connect (OSTI)

This paper illustrates how Discrete Fracture Network (DFN) technology can serve as a basis for the calculation of reservoir engineering parameters for the development of fractured reservoirs. It describes the development of quantitative techniques for defining the geometry and volume of structurally controlled compartments. These techniques are based on a combination of stochastic geometry, computational geometry, and graph the theory. The parameters addressed are compartment size, matrix block size and tributary drainage volume. The concept of DFN models is explained and methodologies to compute these parameters are demonstrated.

La Pointe, P.R.; Eiben, T.; Dershowitz, W. [Golder Associates, Redmond, VA (United States); Wadleigh, E. [Marathon Oil Co., Midland, TX (United States)

1997-08-01T23:59:59.000Z

238

Modified discrete random walk with absorption  

E-Print Network [OSTI]

We obtain expected number of arrivals, probability of arrival, absorption probabilities and expected time before absorption for a modified discrete random walk on the (sub)set of integers. In a [pqrs] random walk the particle can move one step forward or backward, stay for a moment in the same state or it can be absorbed immediately in the current state. M[pqrs] is a modified version, where probabilities on both sides of a multiple function barrier M are of different [pqrs] type.

Theo van Uem

2009-03-02T23:59:59.000Z

239

Holographic Metals and Insulators with Helical Symmetry  

E-Print Network [OSTI]

Homogeneous, zero temperature scaling solutions with Bianchi VII spatial geometry are constructed in Einstein-Maxwell-Dilaton theory. They correspond to quantum critical saddle points with helical symmetry at finite density. Assuming $AdS_{5}$ UV asymptotics, the small frequency/(temperature) dependence of the AC/(DC) electric conductivity along the director of the helix are computed. A large class of insulating and conducting anisotropic phases is found, as well as isotropic, metallic phases. Conduction can be dominated by dissipation due to weak breaking of translation symmetry or by a quantum critical current.

Aristomenis Donos; Blaise Goutéraux; Elias Kiritsis

2014-06-24T23:59:59.000Z

240

Holographic Metals and Insulators with Helical Symmetry  

E-Print Network [OSTI]

Homogeneous, zero temperature scaling solutions with Bianchi VII spatial geometry are constructed in Einstein-Maxwell-Dilaton theory. They correspond to quantum critical saddle points with helical symmetry at finite density. Assuming $AdS_{5}$ UV asymptotics, the small frequency/(temperature) dependence of the AC/(DC) electric conductivity along the director of the helix are computed. A large class of insulating and conducting anisotropic phases is found, as well as isotropic, metallic phases. Conduction can be dominated by dissipation due to weak breaking of translation symmetry or by a quantum critical current.

Donos, Aristomenis

2014-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


241

F spin as a partial symmetry  

Science Journals Connector (OSTI)

We use the empirical evidence that F-spin multiplets exist in nuclei for only selected states as an indication that F spin can be regarded as a partial symmetry. We show that there is a class of non-F-scalar IBM-2 Hamiltonians with partial F-spin symmetry, which reproduce the known systematics of collective bands in nuclei. These Hamiltonians predict that the scissors states have good F-spin and form F-spin multiplets, which is supported by the existing data.

A. Leviatan and J. N. Ginocchio

2000-01-12T23:59:59.000Z

242

Pseudo-Spin Symmetry and its Applications  

E-Print Network [OSTI]

The pseudo-spin symmetry is reviewed. A mapping that produces the separation of the total angular momentum into pseudo-orbital and pseudo-spin degrees of freedom is discussed, together with the analytic transformations that take us from the normal parity space to the eigenstates of a pseudo-oscillator with one quanta less. The many-particle version of the unitary transformation to the pseudo-SU(3) space is established. As an example, these symmetries are used to describe the double beta decay phenomenon in heavy deformed nuclei.

Octavio Casta~nos; Jorge G. Hirsch; Peter O. Hess. To be published in Proc. CAM94 Phys. Meeting; AIP Press

1995-01-26T23:59:59.000Z

243

Symmetry reduction of metal phthalocyanines on metals  

Science Journals Connector (OSTI)

The temperature-dependent adsorption behavior of fourfold symmetric metal phthalocyanines (MPcs) on metals with commensurate and incommensurate symmetries was investigated by scanning tunneling microscopy. On the fourfold symmetric Cu(100) surface, planar and fourfold molecular structures in two equivalent orientations were found for MPcs when prepared at room temperature. In addition, two metastable orientations were identified when prepared at low temperature, which can be depopulated upon annealing. MPcs adsorbed on the sixfold symmetric Cu(111) surface showed a disturbed molecular appearance. The symmetry of molecular structures changed from fourfold to twofold, which is discussed in terms of molecule-substrate interaction.

Shih-Hsin Chang; Stefan Kuck; Jens Brede; Leonid Lichtenstein; Germar Hoffmann; Roland Wiesendanger

2008-12-29T23:59:59.000Z

244

Angular Symmetry of the 2 - Matrix  

Science Journals Connector (OSTI)

For a system of N spinless particles in a state of definite angular momentum L with definite z component M, the rotational symmetry properties of the two-particle density matrix are obtained in a completely explicit fashion. Also studied is the 2-matrix associated with an equally weighted (unpolarized) ensemble of the various M states for a given L.

Claude Garrod

1968-08-05T23:59:59.000Z

245

Symmetries and "principles of construction" in Foundations  

E-Print Network [OSTI]

Symmetries and "principles of construction" in Foundations Giuseppe Longo LIENS, CNRS ­ ENS, Paris Preliminaries A "foundational analysis" (a fully justified search for "unshakable certainties", in 1900) Frege and Hilbert: the search for (proof) principles and "unshakable certainties" (different: absolute laws

Longo, Giuseppe

246

Weyl-Gauge Symmetry of Graphene  

E-Print Network [OSTI]

The conformal invariance of the low energy limit theory governing the electronic properties of graphene is explored. In particular, it is noted that the massless Dirac theory in point enjoys local Weyl symmetry, a very large symmetry. Exploiting this symmetry in the two spatial dimensions and in the associated three dimensional spacetime, we find the geometric constraints that correspond to specific shapes of the graphene sheet for which the electronic density of states is the same as that for planar graphene, provided the measurements are made in accordance to the inner reference frame of the electronic system. These results rely on the (surprising) general relativistic-like behavior of the graphene system arising from the combination of its well known special relativistic-like behavior with the less explored Weyl symmetry. Mathematical structures, such as the Virasoro algebra and the Liouville equation, naturally arise in this three-dimensional context and can be related to specific profiles of the graphene sheet. Speculations on possible applications of three-dimensional gravity are also proposed.

Alfredo Iorio

2010-07-28T23:59:59.000Z

247

Spontaneous symmetry breaking in gauge theories  

Science Journals Connector (OSTI)

...and beyond the discovery of the Higgs boson. organised and edited by John...and beyond the discovery of the Higgs boson . The aim of this historical article...whose features is the now-famous Higgs boson. symmetry breaking|gauge theory...

2015-01-01T23:59:59.000Z

248

Evidential Symmetry and Mushy Credence Roger White  

E-Print Network [OSTI]

1 Evidential Symmetry and Mushy Credence Roger White MIT rog@mit.edu draft 4/07 The Principle arise. I'm wondering if the marble taken from this urn is black or white. I might have a rich body in the box has been selected from a shaken urn containing just five white and five black balls. Or I might

Fitelson, Branden

249

Charmonium in Nuclear Matter and Chiral Symmetry  

Science Journals Connector (OSTI)

......symmetry breaking of the QCD vacuum. The mass shifts we...3686) and (3770) in nuclear medium are large enough...proposed in the future accelerator facility at the German...non-trivial changes of the QCD vacuum in nuclear medium and on the origin......

Su Houng Lee; Che Ming Ko

2003-01-01T23:59:59.000Z

250

Efficient energy stable schemes with spectral discretization in space ...  

E-Print Network [OSTI]

We construct energy stable schemes for the time discretization of the highly nonlinear ... shape) in order to achieve a well-defined energy for the system.

2012-04-03T23:59:59.000Z

251

Lowest-rank Solutions of Continuous and Discrete Lyapunov ...  

E-Print Network [OSTI]

Fortunately,. Mesbahi and Papavassilopoulos [On the rank minimization prob- ... with the semidefinite cone constraint, the lowest-rank solutions of the discrete ...

2012-10-08T23:59:59.000Z

252

A Discrete Algorithm for Crystal Structure Prediction of Organic Molecules  

Science Journals Connector (OSTI)

The main features of the new algorithm are analysis of the molecule, discretization of the space, statistical atom-pair functions and clustering due to a similarity index.

Hofmann, D.W.M.

1997-03-01T23:59:59.000Z

253

DNA Origami Directed Self-Assembly of Discrete Silver Nanoparticle...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Self-Assembly of Discrete Silver Nanoparticle Architectures Source: Angewandte Chemie International Edition Year: 2010 Volume: 49 Pages: 2700-2704 ABSTRACT: DNA origami...

254

2-D discrete element modeling of unconsolidated sandstones.  

E-Print Network [OSTI]

??In this work unconsolidated sands saturated with heavy oil were modeled using a discrete element numerical model, (DEM). The DEM code was built in Mathematica… (more)

Franquet Barbara, Javier Alejandro

2012-01-01T23:59:59.000Z

255

Generalised CP and $\\Delta (6n^2)$ Family Symmetry in Semi-Direct Models of Leptons  

E-Print Network [OSTI]

We perform a detailed analysis of $\\Delta (6n^2)$ family symmetry combined with a generalised CP symmetry in the lepton sector, breaking to different remnant symmetries $G_{\

Ding, Gui-Jun; Neder, Thomas

2014-01-01T23:59:59.000Z

256

Density content of nuclear symmetry energy from nuclear observables  

Science Journals Connector (OSTI)

The nuclear symmetry energy at a given density measures the energy transferred in converting symmetric nuclear matter into the pure neutron matter. The density content of nuclear symmetry energy remains poorly co...

B K AGRAWAL

2014-11-01T23:59:59.000Z

257

Sets of Symmetry Breaking Constraints Barbara M. Smith  

E-Print Network [OSTI]

Sets of Symmetry Breaking Constraints Barbara M. Smith Cork Constraint Computation Centre, University College Cork, Ireland b.m.smith@4c.ucc.ie Abstract [Puget, 2004] has shown that if the symmetry

Smith, Barbara M.

258

Order statistics inference for describing topological coupling and mechanical symmetry breaking in multidomain proteins  

E-Print Network [OSTI]

Cooperativity is a hallmark of proteins, many of which show a modular architecture comprising discrete structural domains. Detecting and describing dynamic couplings between structural regions is difficult in view of the many-body nature of protein-protein interactions. By utilizing the GPU-based computational acceleration, we carried out simulations of the protein forced unfolding for the dimer WW-WW of the all-beta-sheet WW domains used as a model multidomain protein. We found that while the physically non-interacting identical protein domains (WW) show nearly symmetric mechanical properties at low tension, reflected, e.g., in the similarity of their distributions of unfolding times, these properties become distinctly different when tension is increased. Moreover, the uncorrelated unfolding transitions at a low pulling force become increasingly more correlated (dependent) at higher forces. Hence, the applied force not only breaks "the mechanical symmetry" but also couples the physically non-interacting prot...

Kononova, Olga; Barsegov, Valeri

2015-01-01T23:59:59.000Z

259

Nuclear symmetry energy at subnormal densities from measured nuclear masses  

Science Journals Connector (OSTI)

The symmetry energy coefficients for nuclei with mass number A=20–250 are extracted from more than 2000 measured nuclear masses. With the semiempirical connection between the symmetry energy coefficients of finite nuclei and the nuclear symmetry energy at reference densities, we investigate the density dependence of the symmetry energy of nuclear matter at subnormal densities. The obtained results are compared with those extracted from other methods.

Min Liu; Ning Wang; Zhu-Xia Li; Feng-Shou Zhang

2010-12-13T23:59:59.000Z

260

Nuclear symmetry energy at subnormal densities from measured nuclear masses  

E-Print Network [OSTI]

The symmetry energy coefficients for nuclei with mass number A=20~250 are extracted from more than 2000 measured nuclear masses. With the semi-empirical connection between the symmetry energy coefficients of finite nuclei and the nuclear symmetry energy at reference densities, we investigate the density dependence of symmetry energy of nuclear matter at subnormal densities. The obtained results are compared with those extracted from other methods.

Min Liu; Ning Wang; Zhuxia Li; Fengshou Zhang

2010-11-17T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

B-spline Contour Representation and Symmetry Detection  

Science Journals Connector (OSTI)

The detection of edges is only one of many steps in the understanding of images. Further processing necessarily involves grouping operations between contours. We present a representation of edge contours by approximating B-splines and show that such ... Keywords: B-spline contour representation, edge contours, edge detection, image recognition, parallel symmetries, planar shape description, shape from contour, skew symmetries, smooth local symmetries, splines (mathematics), symmetry detection

P. Saint-Marc; H. Rom; G. Medioni

1993-11-01T23:59:59.000Z

262

Symmetry Breaking in Subgraph Isomorphism Stephane Zampelli(1)  

E-Print Network [OSTI]

Satisfaction Problem (CSP) is a bijective function that preserves CSP structure and solutions. Symmetries of symmetries can thus speed up the solving of a CSP. Symmetries arise naturally in graphs as au- tomorphisms function. The CSP model of subgraph isomorphism should rep- resent a total function f : Np Nt. This total

Deville, Yves

263

Discretization and Algorithms for Strong Coupling in Computational Aeroelasticity  

E-Print Network [OSTI]

.2 Structural discretization . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 4.3 Mimicing the energy and the behaviour of the corresponding algorithmic processes. A discretization that mimics the energy budget the ambitions to do so for the overall aeroelastic scheme. A conservative load projection at the uid

264

EQUILIBRIUM RECONSTRUCTION FROM DISCRETE MAGNETIC MEASUREMENTS IN A TOKAMAK  

E-Print Network [OSTI]

EQUILIBRIUM RECONSTRUCTION FROM DISCRETE MAGNETIC MEASUREMENTS IN A TOKAMAK Blaise Faugeras (joint of the equilibrium in a Tokamak from discrete magnetic mea- surements. In order to solve this inverse problem we of a plasma in a Tokamak [1]. The state variable of interest in the modelization of such an equilibrium under

Faugeras, Blaise

265

Video Denoising and Simplification Via Discrete Regularization on Graphs  

E-Print Network [OSTI]

Video Denoising and Simplification Via Discrete Regularization on Graphs Mahmoud Ghoniem, Youssef algorithms for video de- noising and simplification based on discrete regularization on graphs. The main difference between video and image denoising is the temporal redundancy in video sequences. Recent works

Paris-Sud XI, Université de

266

Induction Generation Ostrowski Recognition Discrete geometry and numeration  

E-Print Network [OSTI]

Induction Generation Ostrowski Recognition Discrete geometry and numeration V. Berth´e LIRMM;Induction Generation Ostrowski Recognition A classical problem in Diophantine approximation How to approximate a line in R3 by points in Z3 ? How to define a discrete line in R3? #12;Induction Generation

267

Optimal Algorithms for Generating Discrete Random Variables with Changing Distributions  

E-Print Network [OSTI]

Optimal Algorithms for Generating Discrete Random Variables with Changing Distributions T. Hagerup arithmetic and the floor function, 3. generating a uniformly distributed real number between 0 and 1 K. Mehlhorn I. Munro Abstract We give optimal algorithms for generating discrete random variables

Mehlhorn, Kurt

268

Combined Delta-Nabla Sum Operator in Discrete Fractional Calculus  

E-Print Network [OSTI]

We introduce a more general discrete fractional operator, given by convex linear combination of the delta and nabla fractional sums. Fundamental properties of the new fractional operator are proved. As particular cases, results on delta and nabla discrete fractional calculus are obtained.

Bastos, Nuno R O

2010-01-01T23:59:59.000Z

269

Enhancing complex system performance using discrete-event simulation  

Science Journals Connector (OSTI)

In this paper, we utilize discrete-event simulation (DES) merged with human factors analysis to provide the venue within which the separation and deconfliction of the system/human operating principles can occur. A concrete example is presented to illustrate ... Keywords: discrete event simulation, potential capacity, queuing model

Glenn O. Allgood; Mohammed M. Olama; Joe E. Lake

2010-04-01T23:59:59.000Z

270

Institute of Operations Research Discrete Optimization and Logistics  

E-Print Network [OSTI]

Institute of Operations Research Discrete Optimization and Logistics 1 Prof. Dr. Stefan Nickel ­ Health Care Logistics: Overview Health Care Logistics 11/28/2013 #12;Institute of Operations Research Discrete Optimization and Logistics 2 Prof. Dr. Stefan Nickel ­ Health Care Logistics: Overview Health Care

Al Hanbali, Ahmad

271

Mechanical Integrators Derived from a Discrete Variational Principle  

E-Print Network [OSTI]

Mechanical Integrators Derived from a Discrete Variational Principle Jerey M. Wendlandt1;2 Mechanical Engineering, University of California at Berkeley, Berkeley, CA 94720, USA Jerrold E. Marsden3 for mechanical system simulation are created by using discrete algorithms to approximate the continuous equations

Marsden, Jerrold

272

A discrete model of energy-conserved wave function collapse  

Science Journals Connector (OSTI)

...articles 1009 159 A discrete model of energy-conserved wave function collapse Shan...100190, People's Republic of China Energy non-conservation is a serious problem...paper, we propose a discrete model of energy-conserved wave function collapse. It...

2013-01-01T23:59:59.000Z

273

Maxwell Equations in Complex Form of Majorana - Oppenheimer, Solutions with Cylindric Symmetry in Riemann S_{3} and Lobachevsky H_{3} Spaces  

E-Print Network [OSTI]

Complex formalism of Riemann - Silberstein - Majorana - Oppenheimer in Maxwell electrodynamics is extended to the case of arbitrary pseudo-Riemannian space - time in accordance with the tetrad recipe of Tetrode - Weyl - Fock - Ivanenko. In this approach, the Maxwell equations are solved exactly on the background of static cosmological Einstein model, parameterized by special cylindrical coordinates and realized as a Riemann space of constant positive curvature. A discrete frequency spectrum for electromagnetic modes depending on the curvature radius of space and three parameters is found, and corresponding basis electromagnetic solutions have been constructed explicitly. In the case of elliptical model a part of the constructed solutions should be rejected by continuity considerations. Similar treatment is given for Maxwell equations in hyperbolic Lobachevsky model, the complete basis of electromagnetic solutions in corresponding cylindrical coordinates has been constructed as well, no quantization of frequencies of electromagnetic modes arises.

A. A. Bogush; G. G. Krylov; E. M. Ovsiyuk; V. M. Red'kov

2009-07-05T23:59:59.000Z

274

Are We Observing Violations of Lorentz Symmetry?  

E-Print Network [OSTI]

Recent observations of ultra high energy cosmic rays and gamma rays suggest that there are small violations of Lorentz symmetry. If there were no such violations, then the GZK cut off would hold and cosmic rays with energy $\\sim 10^{20}eV$ or higher would not be reaching the earth. However some such events seem to have been observed. This has lead to phenomenological models in which there is a small violation of the Lorentz symmetry or the velocity of light. However recent Quantum Gravity and String Theory approaches which no longer consider a differentiable spacetime manifold already predict such violations. Similarly there are other theoretical reasons which also point to this. We briefly discuss the various possibilities.

B. G. Sidharth

2006-02-20T23:59:59.000Z

275

Local Conformal Symmetry in Physics and Cosmology  

E-Print Network [OSTI]

We show how to lift a generic non-scale invariant action in Einstein frame into a locally conformally-invariant (or Weyl-invariant) theory and present a new general form for Lagrangians consistent with Weyl symmetry. Advantages of such a conformally invariant formulation of particle physics and gravity include the possibility of constructing geodesically complete cosmologies. We present a conformal-invariant version of the standard model coupled to gravity, and show how Weyl symmetry may be used to obtain unprecedented analytic control over its cosmological solutions. Within this new framework, generic FRW cosmologies are geodesically complete through a series of big crunch - big bang transitions. We discuss a new scenario of cosmic evolution driven by the Higgs field in a \\textquotedblleft minimal\\textquotedblright% \\ conformal standard model, in which there is no new physics beyond the standard model at low energies, and the current Higgs vacuum is metastable as indicated by the latest LHC data.

Itzhak Bars; Paul Steinhardt; Neil Turok

2013-07-07T23:59:59.000Z

276

Generalized gravitational entropy without replica symmetry  

E-Print Network [OSTI]

We explore several extensions of the generalized entropy construction of Lewkowycz and Maldacena, including a formulation that does not rely on preserving replica symmetry in the bulk. We show that an appropriately general ansatz for the analytically continued replica metric gives us the flexibility needed to solve the gravitational field equations beyond general relativity. As an application of this observation we study Einstein-Gauss-Bonnet gravity with a small Gauss-Bonnet coupling and derive the condition that the holographic entanglement entropy must be evaluated on a surface which extremizes the Jacobson-Myers entropy. We find that in both general relativity and Einstein-Gauss-Bonnet gravity replica symmetry breaking terms are permitted by the field equations, suggesting that they do not generically vanish.

Joan Camps; William R. Kelly

2015-01-13T23:59:59.000Z

277

Bianchi Cosmological Models and Gauge Symmetries  

E-Print Network [OSTI]

We analyze carefully the problem of gauge symmetries for Bianchi models, from both the geometrical and dynamical points of view. Some of the geometrical definitions of gauge symmetries (=``homogeneity preserving diffeomorphisms'') given in the literature do not incorporate the crucial feature that local gauge transformations should be independent at each point of the manifold of the independent variables ( = time for Bianchi models), i.e, should be arbitrarily localizable ( in time). We give a geometrical definition of homogeneity preserving diffeomorphisms that does not possess this shortcoming. The proposed definition has the futher advantage of coinciding with the dynamical definition based on the invariance of the action ( in Lagrangian or Hamiltonian form). We explicitly verify the equivalence of the Lagrangian covariant phase space with the Hamiltonian reduced phase space. Remarks on the use of the Ashtekar variables in Bianchi models are also given.

Olivier Coussaert; Marc Henneaux

1993-01-05T23:59:59.000Z

278

Chiral symmetry, massive gluons and confinement  

SciTech Connect (OSTI)

It is quite difficult to obtain non-trivial chiral symmetry breaking solutions for the quark gap equation in the presence of dynamically generated gluon masses. An effective confining propagator has recently been proposed by Cornwall in order to solve this problem. We study phenomenological consequences of this approach, showing its compatibility with the experimental data. We argue that this confining propagator should be restricted to a small region of momenta, leading to effective four-fermion interactions at low energy.

Natale, A. A. [Instituto de Fisica Teorica - UNESP Rua Dr. Bento T. Ferraz, 271, Bl.II - 01140-070, Sao Paulo, SP (Brazil)

2013-03-25T23:59:59.000Z

279

Ermakov-Lewis symmetry in photonic lattices  

E-Print Network [OSTI]

We present a class of waveguide arrays that is the classical analog of a quantum harmonic oscillator where the mass and frequency depend on the propagation distance. In these photonic lattices refractive indices and second neighbor couplings define the mass and frequency of the analog quantum oscillator, while first neighbor couplings are a free parameter to adjust the model. The quantum model conserves the Ermakov-Lewis invariant, thus the photonic crystal also posses this symmetry.

Lara, B M Rodríguez; Moya-Cessa, H M; Christodoulides, D N

2014-01-01T23:59:59.000Z

280

Spontaneous symmetry breaking and the chain criterion  

Science Journals Connector (OSTI)

For the first time I have rigorously proved the equivalence between the necessary symmetry condition of the original Landau theory of second-order phase transitions, the chain criterion, and some recent propositions. I have introduced the new chain criterion which contains a powerful corollary. I have also established the validity of the chain criterion beyond the Landau theory, emphasizing its use as an algorithm for calculation of little groups.

Marko V. Jari?

1981-04-01T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


281

FLUID BIAXIAL BANANA PHASES: SYMMETRY AT WORK  

E-Print Network [OSTI]

FLUID BIAXIAL BANANA PHASES: SYMMETRY AT WORK P. E. Cladis,1 Helmut R. Brand2 and Harald Pleiner3 1. The macro- #12;P. E. Cladis, H. R. Brand and H. Pleiner Page 2 of 10 10/13/99 8:12 AM scopic expression a right-handed helix, then, -qo describes a left-handed one. As the mirror image of a right-hand is a left

Cladis, Patricia E.

282

Lagrangian generators of the Poincaré gauge symmetries  

Science Journals Connector (OSTI)

We have systematically computed the generators of the symmetries arising in Poincaré gauge theory formulation of gravity, both in 2+1 and 3+1 dimensions. This was done using a completely Lagrangian approach. The results are expected to be valid in any dimensions, as seen through lifting the results of the 2+1 dimensional example into the 3+1 dimensional one.

Rabin Banerjee; Debraj Roy; Saurav Samanta

2010-08-06T23:59:59.000Z

283

Symmetry energy: from nuclear matter to finite nuclei  

E-Print Network [OSTI]

We suggest a particular procedure of derivation of the beta-stability line and isotopic symmetry energy. The behavior of the symmetry energy coefficient $b(A,N-Z)$ is analyzed. We redefine the surface tension coefficient and the surface symmetry energy for an asymmetric nuclear Fermi-liquid drop with a finite diffuse layer. Following Gibbs-Tolman concept, we introduce the equimolar radius at which the surface tension is applied. The relation of the nuclear macroscopic characteristics like surface and symmetry energies, Tolman length, etc. to the bulk properties of nuclear matter is considered. The surface-to-volume symmetry energy ratio for several Skyrme-force parametrizations is obtained.

Kolomietz, V M

2014-01-01T23:59:59.000Z

284

Space–time correlations in urban sprawl  

Science Journals Connector (OSTI)

...neighbouring cities, i.e. does the migration of people from...following the analogy with physics presented in [23]. However...X , and YM Ioannides. 2004 Handbook of regional and urban economics...V Loreto. 2009 Statistical physics of social dynamics. Rev...

2014-01-01T23:59:59.000Z

285

Symmetry and Evolution in Quantum Gravity  

E-Print Network [OSTI]

We propose an operator constraint equation for the wavefunction of the Universe that admits genuine evolution. While the corresponding classical theory is equivalent to the canonical decomposition of General Relativity, the quantum theory makes predictions that are distinct from Wheeler-DeWitt cosmology. Furthermore, the local symmetry principle - and corresponding observables - of the theory have a direct interpretation in terms of a conventional gauge theory, where the gauge symmetry group is that of spatial conformal diffeomorphisms (that preserve the spatial volume of the Universe). The global evolution is in terms of an arbitrary parameter that serves only as an unobservable label for successive states of the Universe. Our proposal follows unambiguously from a suggestion of York whereby the independently specifiable initial data in the action principle of General Relativity is given by a conformal geometry and the spatial average of the York time on the spacelike hypersurfaces that bound the variation. Remarkably, such a variational principle uniquely selects the form of the constraints of the theory so that we can establish a precise notion of both symmetry and evolution in quantum gravity.

Sean Gryb; Karim Thebault

2014-03-25T23:59:59.000Z

286

Exploring Cartan gravity with dynamical symmetry breaking  

E-Print Network [OSTI]

It has been known for some time that General Relativity can be regarded as a Yang-Mills-type gauge theory in a symmetry broken phase. In this picture the gravity sector is described by an $SO(1,4)$ or $SO(2,3)$ gauge field $A^{a}_{\\phantom{a}b\\mu}$ and Higgs field $V^{a}$ which acts to break the symmetry down to that of the Lorentz group $SO(1,3)$. This symmetry breaking mirrors that of electroweak theory. However, a notable difference is that while the Higgs field $\\Phi$ of electroweak theory is taken as a genuine dynamical field satisfying a Klein-Gordon equation, the gauge independent norm $V^2\\equiv \\eta_{ab}V^{a}V^{b}$ of the Higgs-type field $V^a$ is typically regarded as non-dynamical. Instead, in many treatments $V^a$ does not appear explicitly in the formalism or is required to satisfy $V^2 = \\mathrm{const.} \

H. F. Westman; T. G. Zlosnik

2014-03-24T23:59:59.000Z

287

Discrete Exterior Geometry Approach to Structure-Preserving Discretization of Distributed-Parameter Port-Hamiltonian Systems  

E-Print Network [OSTI]

This paper addresses the issue of structure-preserving discretization of open distributed-parameter systems with Hamiltonian dynamics. Employing the formalism of discrete exterior calculus, we introduce a simplicial Dirac structure as a discrete analogue of the Stokes-Dirac structure and demonstrate that it provides a natural framework for deriving finite-dimensional port-Hamiltonian systems that emulate their infinite-dimensional counterparts. The spatial domain, in the continuous theory represented by a finite-dimensional smooth manifold with boundary, is replaced by a homological manifold-like simplicial complex and its augmented circumcentric dual. The smooth differential forms, in discrete setting, are mirrored by cochains on the primal and dual complexes, while the discrete exterior derivative is defined to be the coboundary operator. This approach of discrete differential geometry, rather than discretizing the partial differential equations, allows to first discretize the underlying Stokes-Dirac structure and then to impose the corresponding finite-dimensional port-Hamiltonian dynamics. In this manner, a number of important intrinsically topological and geometrical properties of the system are preserved.

Marko Seslija; Arjan van der Schaft; Jacquelien M. A. Scherpen

2012-02-27T23:59:59.000Z

288

The discrete potential Boussinesq equation and its multisoliton solutions  

E-Print Network [OSTI]

An alternate form of discrete potential Boussinesq equation is proposed and its multisoliton solutions are constructed. An ultradiscrete potential Boussinesq equation is also obtained from the discrete potential Boussinesq equation using the ultradiscretization technique. The detail of the multisoliton solutions is discussed by using the reduction technique. The lattice potential Boussinesq equation derived by Nijhoff et al. is also investigated by using the singularity confinement test. The relation between the proposed alternate discrete potential Boussinesq equation and the lattice potential Boussinesq equation by Nijhoff et al. is clarified.

Ken-ichi Maruno; Kenji Kajiwara

2009-08-12T23:59:59.000Z

289

Constrained Interpolation Remap of Discrete Divergence Free Fields  

National Nuclear Security Administration (NNSA)

Shashkov M. 1 Shashkov M. 1 Constrained Interpolation Remap of Discrete Divergence Free Fields P.B. Bochev, * M. Shashkov † * Sandia National Laboratories, Org. 9214, Albuquerque, NM 87185 † Los Alamos National Laboratory, T-7, Los Alamos, NM 87545 We present a constrained interpolation (CI) algorithm for remapping of divergence free vector fields encoded as 2-cochains on a two-dimensional cell complex. On contractible domains discrete divergence free fields are 2-coboundaries and so they have potentials represented by 1-cochains. The algorithm takes advantage of this fact by using the discrete potential to effect the remapping of the divergence free field. The discrete potential is reconstructed and interpolated to the new cell complex. Application of

290

Applications of Algebraic Topology to Compatible Spatial Discretizations  

National Nuclear Security Administration (NNSA)

Hyman J. 1 Hyman J. 1 Applications of Algebraic Topology to Compatible Spatial Discretizations P. B. Bochev, * J. M. Hyman † * Sandia National Laboratories, Org. 9214, Albuquerque, NM 87185 † Los Alamos National Laboratory, T-7, Los Alamos, NM 87545 We provide a common framework for compatible discretizations using algebraic topology to guide our analysis. The main concept is the natural inner product on cochains, which induces a combinatorial Hodge theory. The framework comprises of mutually consistent operations of differentiation and integration, has a discrete Stokes theorem, and preserves the invariants of the DeRham cohomology groups. The latter allows for an elementary calculation of the kernel of the discrete Laplacian. Our framework provides an abstraction that includes examples

291

Cavity QED implementation of the discrete quantum Fourier transform  

E-Print Network [OSTI]

We present a scheme for the implementation of the discrete quantum Fourier transform using cavity quantum electrodynamics. In the proposed scheme a series of atoms whose atomic coherence carries the input state passes through a series of cavities...

Scully, Marlan O.; Zubairy, M. Suhail

2002-01-01T23:59:59.000Z

292

Resolution of grain scale interactions using the Discrete Element Method  

E-Print Network [OSTI]

Granular materials are an integral part of many engineering systems. Currently, a popular tool for numerically investigating granular systems is the Discrete Element Method (DEM). Nearly all implementations of the DEM, ...

Johnson, Scott M. (Scott Matthew), 1978-

2006-01-01T23:59:59.000Z

293

A piecewise linear finite element discretization of the diffusion equation  

E-Print Network [OSTI]

it discretizes the diffusion equation on an arbitrary polyhedral mesh. We implemented our method in the KULL software package being developed at Lawrence Livermore National Laboratory. This code previously utilized Palmer's method as its diffusion solver, which...

Bailey, Teresa S

2006-10-30T23:59:59.000Z

294

Nano-tribology of discrete track recording media  

E-Print Network [OSTI]

1.27 (a) Schematic of slider flying over disk and pressure1.27 (a) Schematic of slider flying over disk and pressureat very small slider-disk flying heights for discrete track

Yoon, Yeoungchin

2010-01-01T23:59:59.000Z

295

Simulation of the head disk interface for discrete track media  

Science Journals Connector (OSTI)

This paper investigates the effect of discrete tracks on the steady state flying behavior of sub ambient proximity sliders. A ... air bearing simulator is used to simulate the flying characteristics of sliders ov...

Maik Duwensee; Shoji Suzuki; Judy Lin; David Wachenschwanz…

2007-05-01T23:59:59.000Z

296

2-D discrete element modeling of unconsolidated sandstones  

E-Print Network [OSTI]

developed in this thesis is compared to the results of triaxial tests performed in cylindrical core samples of unconsolidated sandstones saturated with heavy oil. The discrete element model treats the sand as a two dimensional assembly of particles...

Franquet Barbara, Javier Alejandro

2012-06-07T23:59:59.000Z

297

NEURAL NETWORKS FOR DISCRETE TOMOGRAPHY K.J. Batenburg a  

E-Print Network [OSTI]

NEURAL NETWORKS FOR DISCRETE TOMOGRAPHY K.J. Batenburg a W.A. Kosters b a Mathematical Institute of crystalline solids at atomic resolution from electron microscopic images can be considered the "holy grail

Kosters, Walter

298

Discrete Propagation in Numerically Simulated Nocturnal Squall Lines  

Science Journals Connector (OSTI)

Simulations of a typical midlatitude squall line were used to investigate a mechanism for discrete propagation, defined as convective initiation ahead of an existing squall line leading to a faster propagation speed for the storm complex. Radar ...

Robert G. Fovell; Gretchen L. Mullendore; Seung-Hee Kim

2006-12-01T23:59:59.000Z

299

Global confinement and discrete dynamo activity in the MST reversed...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

confinement and discrete dynamo activity in the MST reversed-field pinch* S. Hokin,+ A. Almagri, S. Assadi, J. Beckstead, G. Chartas, N. Cracker, M. Cudzinovic, D. Den Hat-tog, FL...

300

AC transmission system planning choosing lines from a discrete set  

E-Print Network [OSTI]

Transmission system planning (TSP) is a difficult nonlinear optimization problem involving non-convex quadratic terms, as well as discrete variables. We extend prior results for linear relaxations, drawing on a preliminary ...

Gilbertson, Eric W.

2013-04-24T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


301

Symmetries of Differential equations and Applications in Relativistic Physics  

E-Print Network [OSTI]

In this thesis, we study the one parameter point transformations which leave invariant the differential equations. In particular we study the Lie and the Noether point symmetries of second order differential equations. We establish a new geometric method which relates the point symmetries of the differential equations with the collineations of the underlying manifold where the motion occurs. This geometric method is applied in order the two and three dimensional Newtonian dynamical systems to be classified in relation to the point symmetries; to generalize the Newtonian Kepler-Ermakov system in Riemannian spaces; to study the symmetries between classical and quantum systems and to investigate the geometric origin of the Type II hidden symmetries for the homogeneous heat equation and for the Laplace equation in Riemannian spaces. At last but not least, we apply this geometric approach in order to determine the dark energy models by use the Noether symmetries as a geometric criterion in modified theories of gra...

Paliathanasis, Andronikos

2015-01-01T23:59:59.000Z

302

Symmetry Energy as a Function of Density and Mass  

E-Print Network [OSTI]

Energy in nuclear matter is, in practice, completely characterized at different densities and asymmetries, when the density dependencies of symmetry energy and of energy of symmetric matter are specified. The density dependence of the symmetry energy at subnormal densities produces mass dependence of nuclear symmetry coefficient and, thus, can be constrained by that latter dependence. We deduce values of the mass dependent symmetry coefficients, by using excitation energies to isobaric analog states. The coefficient systematic, for intermediate and high masses, is well described in terms of the symmetry coefficient values of a_a^V=(31.5-33.5) MeV for the volume coefficient and a_a^S=(9-12) MeV for the surface coefficient. These two further correspond to the parameter values describing density dependence of symmetry energy, of L~95 MeV and K_{sym}~25 MeV.

Pawel Danielewicz; Jenny Lee

2007-08-21T23:59:59.000Z

303

Symmetry Energy as a Function of Density and Mass  

SciTech Connect (OSTI)

Energy in nuclear matter is, in practice, completely characterized at different densities and asymmetries, when the density dependencies of symmetry energy and of energy of symmetric matter are specified. The density dependence of the symmetry energy at subnormal densities produces mass dependence of nuclear symmetry coefficient and, thus, can be constrained by that latter dependence. We deduce values of the mass dependent symmetry coefficients, by using excitation energies to isobaric analog states. The coefficient systematic, for intermediate and high masses, is well described in terms of the symmetry coefficient values of a{sub a}{sup V} = (31.5-33.5) MeV for the volume coefficient and a{sub a}{sup S} = (9-12) MeV for the surface coefficient. These two further correspond to the parameter values describing density dependence of symmetry energy, of L{approx}95 MeV and K{sub sym}{approx}25 MeV.

Danielewicz, Pawel; Lee, Jenny [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824 (United States)

2007-10-26T23:59:59.000Z

304

Symmetry Energy as a Function of Density and Mass  

E-Print Network [OSTI]

Energy in nuclear matter is, in practice, completely characterized at different densities and asymmetries, when the density dependencies of symmetry energy and of energy of symmetric matter are specified. The density dependence of the symmetry energy at subnormal densities produces mass dependence of nuclear symmetry coefficient and, thus, can be constrained by that latter dependence. We deduce values of the mass dependent symmetry coefficients, by using excitation energies to isobaric analog states. The coefficient systematic, for intermediate and high masses, is well described in terms of the symmetry coefficient values of a_a^V=(31.5-33.5) MeV for the volume coefficient and a_a^S=(9-12) MeV for the surface coefficient. These two further correspond to the parameter values describing density dependence of symmetry energy, of L~95 MeV and K_{sym}~25 MeV.

Danielewicz, Pawel

2007-01-01T23:59:59.000Z

305

Fractional Equations of Kicked Systems and Discrete Maps  

E-Print Network [OSTI]

Starting from kicked equations of motion with derivatives of non-integer orders, we obtain "fractional" discrete maps. These maps are generalizations of well-known universal, standard, dissipative, kicked damped rotator maps. The main property of the suggested fractional maps is a long-term memory. The memory effects in the fractional discrete maps mean that their present state evolution depends on all past states with special forms of weights. These forms are represented by combinations of power-law functions.

Vasily E. Tarasov; George M. Zaslavsky

2011-07-20T23:59:59.000Z

306

Scalar-Tensor Gravity Cosmology: Noether symmetries and analytical solutions  

E-Print Network [OSTI]

In this paper, we present a complete Noether Symmetry analysis in the framework of scalar-tensor cosmology. Specifically, we consider a non-minimally coupled scalar field action embedded in the FLRW spacetime and provide a full set of Noether symmetries for related minisuperspaces. The presence of symmetries implies that the dynamical system becomes integrable and then we can compute cosmological analytical solutions for specific functional forms of coupling and potential functions selected by the Noether Approach.

A. Paliathanasis; M. Tsamparlis; S. Basilakos; S. Capozziello

2014-03-03T23:59:59.000Z

307

Left-right symmetry at LHC  

Science Journals Connector (OSTI)

We revisit the issue of the limit on the scale of left-right symmetry breaking. We focus on the minimal SU(2)L×SU(2)R×U(1)B-L gauge theory with the seesaw mechanism and discuss the two possibilities of defining left-right symmetry as parity or charge conjugation. In the commonly adopted case of parity, we perform a complete numerical study of the quark mass matrices and the associated left and right mixing matrices without any assumptions usually made in the literature about the ratio of vacuum expectation values. We find that the usual lower limit on the mass of the right-handed gauge boson from the K mass difference, MWR>2.5??TeV, is subject to a possible small reduction due to the difference between right and left Cabibbo angles. In the case of charge conjugation the limit on MWR is somewhat more robust. However, the more severe bounds from CP-violating observables are absent in this case. In fact, the free phases can also resolve the present mild discrepancy between the standard model and CP violation in the B sector. Thus, even in the minimal case, both charged and neutral gauge bosons may be accessible at the Large Hadron Collider with spectacular signatures of lepton number violation.

Alessio Maiezza; Miha Nemevšek; Fabrizio Nesti; Goran Senjanovi?

2010-09-24T23:59:59.000Z

308

8 - Introduction to discrete dislocation statics and dynamics  

Science Journals Connector (OSTI)

Publisher Summary This chapter provides an introduction to discrete dislocation statics and dynamics. The chapter deals with the simulation of plasticity of metals at the microscopic and mesoscopic scale using space- and time-discretized dislocation statics and dynamics. The complexity of discrete dislocation models is due to the fact that the mechanical interaction of ensembles of such defects is of an elastic nature and, therefore, involves long-range interactions. Space-discretized dislocation simulations idealize dislocations outside the dislocation cores as linear defects that are embedded within an otherwise homogeneous, isotropic or anisotropic, linear elastic medium. The aim of the chapter is to concentrate on those simulations that are discrete in both space and time. It explicitly incorporates the properties of individual lattice defects in a continuum formulation. The theoretical framework of linear continuum elasticity theory is overviewed as required for the formulation of basic dislocation mechanics. The chapter also discusses the dislocation statics, where the fundamentals of linear isotropic and anisotropic elasticity theory that are required in dislocation theory are reviewed. The chapter describes the dislocation dynamics, where it is concerned with the introduction of continuum dislocation dynamics. The last two sections deal with kinematics of discrete dislocation dynamics and dislocation reactions and annihilation.

Dierk Raabe

2007-01-01T23:59:59.000Z

309

Symmetry Breaking in Graphene Gregory S. Boebinger, National...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Symmetry Breaking in Graphene Gregory S. Boebinger, National High Magnetic Field Laboratory DMR-Award 0654118 DC Field Facility While the laws of physics are often symmetric,...

310

Dynamical electroweak symmetry breaking and the top quark  

SciTech Connect (OSTI)

In this talk, I discuss theories of dynamical electroweak symmetry breaking, with emphasis on the implications of a heavy top quark on the weak interaction {rho} parameter.

Chivukula, R.S. [Boston Univ., MA (United States)

1997-01-01T23:59:59.000Z

311

Symmetry energy at subnuclear densities deduced from nuclear masses  

E-Print Network [OSTI]

We examine how nuclear masses are related to the density dependence of the symmetry energy. Using a macroscopic nuclear model we calculate nuclear masses in a way dependent on the equation of state of asymmetric nuclear matter. We find by comparison with empirical two-proton separation energies that a smaller symmetry energy at subnuclear densities, corresponding to a larger density symmetry coefficient L, is favored. This tendency, which is clearly seen for nuclei that are neutron-rich, nondeformed, and light, can be understood from the property of the surface symmetry energy in a compressible liquid-drop picture.

Kazuhiro Oyamatsu; Kei Iida

2010-04-19T23:59:59.000Z

312

gxxx005-conlaw.dvi  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

7 7 Page 1 TESTS OF DISCRETE SPACE-TIME SYMMETRIES TESTS OF DISCRETE SPACE-TIME SYMMETRIES TESTS OF DISCRETE SPACE-TIME SYMMETRIES TESTS OF DISCRETE SPACE-TIME SYMMETRIES CHARGE CONJUGATION (C ) INVARIANCE CHARGE CONJUGATION (C ) INVARIANCE CHARGE CONJUGATION (C ) INVARIANCE CHARGE CONJUGATION (C ) INVARIANCE CONLAW=C PAR=S009;DESIG=4 Γ(π 0 → 3γ)/Γ total <3.1 × 10 -8 , CL = 90% η C-nonconserving decay parameters NODE=S014230 NODE=S014A1 π + π - π 0 left-right asymmetry (0.09 + 0.11 - 0.12 ) × 10 -2 NODE=S014AS π + π - π 0 sextant asymmetry (0.12 + 0.10 - 0.11 ) × 10 -2 NODE=S014AQ π + π - π 0 quadrant asymmetry (- 0.09 ± 0.09) × 10 -2 NODE=S014A2 π + π - γ left-right asymmetry (0.9 ± 0.4) × 10 -2 NODE=S014BET π + π - γ parameter β (D-wave) - 0.02 ± 0.07 (S = 1.3) PAR=S014;DESIG=104 Γ(η → π 0 γ)/Γ total <9 × 10 -5 , CL = 90% PAR=S014;DESIG=103 Γ(η → 2π 0 γ)/Γ

313

Symmetry tests in photo-pion production  

SciTech Connect (OSTI)

Small angle electron scattering with intense electron beams opens up the possibility of performing almost real photon induced reactions with thin, polarized hydrogen and few body targets, allowing for the detection of low energy charged particles. This promises to be much more effective than conventional photon tagging techniques. For photo-pion reactions some fundamental new possibilities include: tests of charge symmetry in the N-N system by measurement of the neutron-neutron scattering length a{sub nn} in the and ggrD ? ?{sup +}nn reaction; tests of isospin breaking due to the mass difference of the up and down quarks; measurements with polarized targets are sensitive to ?N phase shifts and will test the validity of the Fermi-Watson (final state interaction) theorem. All of these experiments will test the accuracy and energy region of validity of chiral effective theories.

Bernstein, A. M., E-mail: bernstein@mit.edu [Physics Dept. and Laboratory for Nuclear Science Massachusetts Institute of Technology Cambridge MA. 02139 (United States)

2013-11-07T23:59:59.000Z

314

Symmetry Energy Effects on the Nuclear Landscape  

E-Print Network [OSTI]

While various mean-field models predict similar two-proton drip line in the nuclear landscape, their predictions for the two-neutron drip line involve extreme extrapolations and exhibit a significant variation. We demonstrate that this variation is mainly due to the different values of the symmetry energy $E_{\\rm{sym}}(\\rho_{\\rm{c}})$ at the subsaturation cross density $\\rho_{\\rm{c}}\\approx 0.11$ fm$^{-3}$ for different interactions. Based on the recent accurate constraint on $E_{\\rm{sym}}(\\rho_{\\rm{c}})$, we obtain a quite precise prediction for the location of the two-neutron drip line and thus a very precise estimate of $1981 \\pm 76$ for the number of bound even-even nuclei with proton number between $2$ and $120$ among which only $799$ have so far been discovered experimentally.

Rui Wang; Lie-Wen Chen

2014-10-09T23:59:59.000Z

315

Quantum symmetry and photoreactivity of azabenzenes  

SciTech Connect (OSTI)

The fundamental processes associated with a photochemical reaction are described with reference to experimental properties of azabenzenes. Consideration of both excitation and relaxation processes led to presentation of the symmetry propagator, a unifying principle which maps system fluctuations (perturbations acting on an initial state) with dissipations (transitions to different states), thus directing the energy flow along competing reactive and nonreactive pathways. A coherent picture of relaxation processes including chemical reactions was constructed with the aid of spectroscopic data. Pyrazine (1,4 diazine) possesses vibronically active modes which provide an efficient mechanism for internal conversion to the first excited singlet state, where other promoting modes of the correct symmetry induce both intersystem crossing to the triplet manifold, isomerization through diaza-benzvalene, and chemical reactions through cycloreversion of dewar pyrazine to yield HCN plus an azete. At higher energies simple H atom loss and internal conversion become more predominant, leading to ring opening followed by elimination of methylene nitrile and ground state reaction products. Efficiency of chemical transformations as dissipation mechanisms versus competing fluorescence, phosphorescence and radiationless relaxation was mapped from near ultraviolet to far ultraviolet by photodissociation quantum yields into reaction channels characterized by molecular beam photofragment translational spectroscopy. A reaction path model for azabenzene photochemistry was presented and tested against experiment. Presence of undiscovered channels in other azabenzene systems was predicted and verified. The dominant process, HCN elimination, was resolved into three distinct channels. Both molecular and atomic hydrogen elimination was observed, the former with significant vibrational excitation. Small yields of isomerization products, acetylene and N2, were also observed.

Chesko, J.D.M.

1995-06-01T23:59:59.000Z

316

VNI-3.1: MC-simulation program to study high-energy particle collisions in QCD by space-time evolution of parton-cascades and parton-hadron conversion  

E-Print Network [OSTI]

VNI is a general-purpose Monte-Carlo event-generator, which includes the simulation of lepton-lepton, lepton-hadron, lepton-nucleus, hadron-hadron, hadron-nucleus, and nucleus-nucleus collisions. On the basis of renormalization-group improved parton description and quantum-kinetic theory, it uses the real-time evolution of parton cascades in conjunction with a self-consistent hadronization scheme that is governed by the dynamics itself. The causal evolution from a specific initial state (determined by the colliding beam particles) is followed by the time-development of the phase-space densities of partons, pre-hadronic parton clusters, and final-state hadrons, in position-space, momentum-space and color-space. The parton-evolution is described in terms of a space-time generalization of the familiar momentum-space description of multipl (semi) hard interactions in QCD, involving 2 -> 2 parton collisions, 2 -> 1 parton fusion processes, and 1 -> 2 radiation processes. The formation of color-singlet pre-hadronic clusters and their decays into hadrons, on the other hand, is treated by using a spatial criterion motivated by confinement and a non-perturbative model for hadronization. This article gives a brief review of the physics underlying VNI, which is followed by a detailed description of the program itself. The latter program description emphasizes easy-to-use pragmatism and explains how to use the program (including a simple example), annotates input and control parameters, and discusses output data provided by it.

Klaus Geiger

1997-01-06T23:59:59.000Z

317

Symmetry in CSP solutions Nicoleta Neagu and Boi Faltings  

E-Print Network [OSTI]

Symmetry in CSP solutions Nicoleta Neagu and Boi Faltings Artificial Intelligence Laboratory (LIA for finding symmetric solutions of in a CSP. This method is using local symmetries of the CSP structure and research upon searching CSP solutions but few of them watch the relations between CSP solutions. In certain

Flener, Pierre

318

HIDDEN SYMMETRIES OF CYCLIC BRANCHED COVERINGS OF 2-BRIDGE KNOTS  

E-Print Network [OSTI]

HIDDEN SYMMETRIES OF CYCLIC BRANCHED COVERINGS OF 2-BRIDGE KNOTS MARCO RENI AND ANDREI VESNIN hyperbolic 3-manifolds Mn(K), which are n- fold cyclic branched coverings of 2-bridge knots K. We show the symmetry groups of knots and links (see [BZ], [Ka]). Particularly, the class of 2-bridge knots

319

ess5011 Robert J. Serfling MULTIVARIATE SYMMETRY AND  

E-Print Network [OSTI]

ess5011 Robert J. Serfling MULTIVARIATE SYMMETRY AND ASYMMETRY Robert J. Serfling University by modern group theory. 1 #12;ess5011 Robert J. Serfling Here we focus on the notion of symmetry and s independently distributed as chi-square with m degrees of freedom. 2 #12;ess5011 Robert J. Serfling An important

Serfling, Robert

320

Test of time reversal symmetry with resonance neutron scattering  

Science Journals Connector (OSTI)

Discussions for using thermal neutron scattering from nuclei for symmetry measurements stem from past experiments which have observed large parity violating effects in neutron scattering. The proposed LAMPF II proton storage ring spallation neutron source is a vast improvement over the neutron source used in the parity measurements. A proposal for a time reversal symmetry measurement at the LAMPF II facility is presented. (AIP)

J. David Bowman

1986-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


321

Asymptotic Stability of Heteroclinic Cycles in Systems with Symmetry, II  

E-Print Network [OSTI]

Asymptotic Stability of Heteroclinic Cycles in Systems with Symmetry, II Martin Krupa #3; Ian heteroclinic cycles that persist under perturbations that respect the symmetry. In previous work, we began a system- atic investigation into the asymptotic stability of such cycles. In particular, we found a su

322

Energy Content of Colliding Plane Waves using Approximate Noether Symmetries  

E-Print Network [OSTI]

This paper is devoted to study the energy content of colliding plane waves using approximate Noether symmetries. For this purpose, we use approximate Lie symmetry method of Lagrangian for differential equations. We formulate the first-order perturbed Lagrangian for colliding plane electromagnetic and gravitational waves. It is shown that in both cases, there does not exist

M. Sharif; Saira Waheed

2011-09-19T23:59:59.000Z

323

Molecular point?group symmetry in electronic structure calculations  

Science Journals Connector (OSTI)

A generalization of Pitzer’s equal contribution theorem is put forth. The new theorem specifies which types of matrix elements can be constructed using only symmetry?unique (batches of) integrals. A general and simple algorithm to use molecular point?group symmetry in electronic structure calculations is outlined.

Marco Häser

1991-01-01T23:59:59.000Z

324

Symmetry Energy from Systematic of Isobaric Analog States  

E-Print Network [OSTI]

Excitation energies to isobaric states, that are analogs of ground states, are dominated by contributions from the symmetry energy. This opens up a possibility of investigating the symmetry energy on nucleus-by-nucleus basis. Upon correcting energies of measured nuclear levels for shell and pairing effects, we find that the lowest energies for a given isospin rise in proportion to the square of isospin, allowing for an interpretation of the coefficient of proportionality in terms of a symmetry coefficient for a given nucleus. In the (A,Z) regions where there are enough data, we demonstrate a Z-independence of that coefficient. We further concentrate on the A-dependence of the coefficient, in order to learn about the density dependence of symmetry energy in uniform matter, given the changes of the density in the surface region. In parallel to the analysis of data, we carry out an analysis of the coefficient for nuclei calculated within the Skyrme-Hartree-Fock (SHF) approach, with known symmetry energy for uniform matter. While the data from isobaric analog states suggest a simple interpretation for the A-dependent symmetry coefficient, in terms of the surface and volume symmetry coefficients, the SHF results point to a more complicated situation within the isovector sector than in the isoscalar, with much stronger curvature effects in the first. We exploit the SHF results in estimating the curvature contributions to the symmetry coefficient. That assessment is hampered by instabilities of common Skyrme parameterizations of nuclear interactions.

Pawel Danielewicz; Jenny Lee

2011-11-01T23:59:59.000Z

325

Self-consistent Models of Strong Interaction with Chiral Symmetry  

DOE R&D Accomplishments [OSTI]

Some simple models of (renormalizable) meson-nucleon interaction are examined in which the nucleon mass is entirely due to interaction and the chiral ( gamma {sub 5}) symmetry is "broken'' to become a hidden symmetry. It is found that such a scheme is possible provided that a vector meson is introduced as an elementary field. (auth)

Nambu, Y.; Pascual, P.

1963-04-00T23:59:59.000Z

326

The role of symmetry in?fundamental?physics  

Science Journals Connector (OSTI)

...isotopic symmetry of the nuclear force is an...magnetics and pions in nuclear physics...symmetry of the Minkowski vacuum under changes of the...scale of atomic and nuclear physics is so much...generation of particle accelerators—a discovery of new...

David?J. Gross

1996-01-01T23:59:59.000Z

327

Abelian symmetries in multi-Higgs-doublet models  

Science Journals Connector (OSTI)

N-Higgs doublet models (NHDMs) are a popular framework to construct electroweak symmetry breaking mechanisms beyond the standard model. Usually, one builds an NHDM scalar sector which is invariant under a certain symmetry group. Although several such groups have been used, no general analysis of symmetries possible in the NHDM scalar sector exists. Here, we make the first step toward this goal by classifying the elementary building blocks, namely the Abelian symmetry groups, with a special emphasis on finite groups. We describe a strategy that identifies all Abelian groups which are realizable as symmetry groups of the NHDM Higgs potential. We consider both the groups of Higgs-family transformations only and the groups which also contain generalized CP transformations. We illustrate this strategy with the examples of 3HDM and 4HDM and prove several statements for arbitrary N.

Igor P Ivanov; Venus Keus; Evgeny Vdovin

2012-01-01T23:59:59.000Z

328

7.10 MATLAB Experiment on Discrete-Time Systems Purpose: In this experiment, we analyze time responses of a higher-order linear discrete-  

E-Print Network [OSTI]

7.10 MATLAB Experiment on Discrete-Time Systems Purpose: In this experiment, we analyze time responses of a higher-order linear discrete- time system using MATLAB. We study system impulse, step-time dynamic systems using MATLAB. Consider the linear discrete-time system

Gajic, Zoran

329

Discrete Lange-Newell criterion for dissipative systems  

Science Journals Connector (OSTI)

We report on the derivation of the discrete complex Ginzburg-Landau equation with first- and second-neighbor couplings using a nonlinear electrical network. Furthermore, we discuss theoretically and numerically modulational instability of plane carrier waves launched through the line. It is pointed out that the underlying analysis not only spells out the discrete Lange-Newell criterion by the means of the linear stability analysis at which the modulational instability occurs for the generation of a train of ultrashort pulses, but also characterizes the long-time dynamical behavior of the system when the instability grows.

Fabien II Ndzana; Alidou Mohamadou; Timoleon Crépin Kofané

2009-05-29T23:59:59.000Z

330

Gauge Symmetry and Gravito-Electromagnetism  

E-Print Network [OSTI]

A tensor description of perturbative Einsteinian gravity about an arbitrary background spacetime is developed. By analogy with the covariant laws of electromagnetism in spacetime, gravito-electromagnetic potentials and fields are defined to emulate electromagnetic gauge transformations under substitutions belonging to the gauge symmetry group of perturbative gravitation. These definitions have the advantage that on a flat background, with the aid of a covariantly constant timelike vector field, a subset of the linearised gravitational field equations can be written in a form that is fully analogous to Maxwell's equations (without awkward factors of 4 and extraneous tensor fields). It is shown how the remaining equations in the perturbed gravitational system restrict the time dependence of solutions to these equations and thereby prohibit the existence of propagating vector fields. The induced gravito-electromagnetic Lorentz force on a test particle is evaluated in terms of these fields together with the torque on a small gyroscope. It is concluded that the analogy of perturbative gravity to Maxwell's description of electromagnetism can be valuable for (quasi-)stationary gravitational phenomena but that the analogy has its limitations.

Simon J. Clark; Robin W. Tucker

2000-03-31T23:59:59.000Z

331

RG analysis of magnetic catalysis in dynamical symmetry breaking  

SciTech Connect (OSTI)

We perform the renormalization group analysis on the dynamical symmetry breaking under strong external magnetic field, studied recently by Gusynin, Miransky and Shovkovy. We find that any attractive four-Fermi interaction becomes strong in the low energy, thus leading to dynamical symmetry breaking. When the four-Fermi interaction is absent, the {beta}-function for the electromagnetic coupling vanishes in the leading order in 1/N. By solving the Schwinger-Dyson equation for the fermion propagator, we show that in 1/N expansion, for any electromagnetic coupling, dynamical symmetry breaking occurs due to the presence of Landau energy gap by the external magnetic field. 5 refs.

Hong, Deog Ki [Pusan National Univ., (Korea). Dept. of Physics]|[Florida Univ., Gainesville, FL (United States); Kim, Youngman [Hanyang Univ., Seoul (Korea). Dept. of Physics

1996-05-01T23:59:59.000Z

332

Sensitivity of nuclear stopping towards density dependent symmetry energy  

E-Print Network [OSTI]

The effect of density dependent symmetry energy on nuclear-stopping is studied using isospin-dependent quantum molecular dynamics model(IQMD). We have used the reduced isospin-dependent cross-section with soft(S) equation of state for the systems having different isostopic content, to explore the various aspects of nuclear stopping. The aim is to pin down the nature of the nuclear stopping with density dependent symmetry energy. Nuclear stopping is found to be sensitive towards the various forms of the density dependent symmetry energy. The nuclear stopping tends to decrease for the stiffer equation of state (EOS), i.e. larger values of gamma.

Karan Singh Vinayak; Suneel Kumar

2011-10-11T23:59:59.000Z

333

Constraints on the density dependence of the symmetry energy  

E-Print Network [OSTI]

Collisions involving 112Sn and 124Sn nuclei have been simulated with the improved Quantum Molecular Dynamics transport model. The results of the calculations reproduce isospin diffusion data from two different observables and the ratios of neutron and proton spectra. By comparing these data to calculations performed over a range of symmetry energies at saturation density and different representations of the density dependence of the symmetry energy, constraints on the density dependence of the symmetry energy at sub-normal density are obtained. Results from present work are compared to constraints put forward in other recent analysis.

M. B. Tsang; Yingxun Zhang; P. Danielewicz; M. Famiano; Zhuxia Li; W. G. Lynch; A. W. Steiner

2008-11-19T23:59:59.000Z

334

Constraints on the Density Dependence of the Symmetry Energy  

SciTech Connect (OSTI)

Collisions involving {sup 112}Sn and {sup 124}Sn nuclei have been simulated with the improved quantum molecular dynamics transport model. The results of the calculations reproduce isospin diffusion data from two different observables and the ratios of neutron and proton spectra. By comparing these data to calculations performed over a range of symmetry energies at saturation density and different representations of the density dependence of the symmetry energy, constraints on the density dependence of the symmetry energy at subnormal density are obtained. The results from the present work are compared to constraints put forward in other recent analyses.

Tsang, M. B.; Danielewicz, P.; Lynch, W. G.; Steiner, A. W. [Joint Institute of Nuclear Astrophysics and National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824 (United States); Physics and Astronomy Department, Michigan State University, East Lansing, Michigan 48824 (United States); Zhang Yingxun [Joint Institute of Nuclear Astrophysics and National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824 (United States); China Institute of Atomic Energy, P.O. Box 275 (18), Beijing 102413 (China); Famiano, M. [Physics Department, Western Michigan University, Kalamazoo, Michigan 49008 (United States); Li, Zhuxia [China Institute of Atomic Energy, P.O. Box 275 (18), Beijing 102413 (China)

2009-03-27T23:59:59.000Z

335

Constraints on the density dependence of the symmetry energy  

E-Print Network [OSTI]

Collisions involving 112Sn and 124Sn nuclei have been simulated with the improved Quantum Molecular Dynamics transport model. The results of the calculations reproduce isospin diffusion data from two different observables and the ratios of neutron and proton spectra. By comparing these data to calculations performed over a range of symmetry energies at saturation density and different representations of the density dependence of the symmetry energy, constraints on the density dependence of the symmetry energy at sub-normal density are obtained. Results from present work are compared to constraints put forward in other recent analysis.

Tsang, M B; Danielewicz, P; Famiano, M; Li, Zhuxia; Lynch, W G; Steiner, A W

2008-01-01T23:59:59.000Z

336

Hawking Radiation by Kerr Black Holes and Conformal Symmetry  

SciTech Connect (OSTI)

The exponential blueshift associated with the event horizon of a black hole makes conformal symmetry play a fundamental role in accounting for its thermal properties. Using a derivation based on two-point functions, we show that the full spectrum of thermal radiation of scalar particles by Kerr black holes can be explicitly derived on the basis of a conformal symmetry arising in the wave equation near the horizon. The simplicity of our approach emphasizes the depth of the connection between conformal symmetry and black hole radiance.

Agullo, Ivan; Parker, Leonard [Physics Department, University of Wisconsin-Milwaukee, P.O. Box 413, Milwaukee, Wisconsin 53201 (United States); Navarro-Salas, Jose [Departamento de Fisica Teorica and IFIC, Centro Mixto Universidad de Valencia-CSIC. Facultad de Fisica, Universidad de Valencia, Burjassot-46100, Valencia (Spain); Olmo, Gonzalo J. [Instituto de Estructura de la Materia, CSIC, Serrano 121, 28006 Madrid (Spain)

2010-11-19T23:59:59.000Z

337

Discrete geodesic regression in shape space Benjamin Berkels1  

E-Print Network [OSTI]

Discrete geodesic regression in shape space Benjamin Berkels1 , P. Thomas Fletcher2 , Behrend Benedikt.Wirth@cims.nyu.edu Abstract. A new approach for the effective computation of geodesic re- gression curves in shape spaces is presented. Here, one asks for a geodesic curve on the shape manifold

Rumpf, Martin

338

Discrete RNA Libraries from Pseudo-Torsional Space  

Science Journals Connector (OSTI)

The discovery that RNA molecules can fold into complex structures and carry out diverse cellular roles has led to interest in developing tools for modeling RNA tertiary structure. While significant progress has been made in establishing that the RNA backbone is rotameric, few libraries of discrete conformations specifically for use in RNA modeling have been validated. Here, we present six libraries of discrete RNA conformations based on a simplified pseudo-torsional notation of the RNA backbone, comparable to phi and psi in the protein backbone. We evaluate the ability of each library to represent single nucleotide backbone conformations, and we show how individual library fragments can be assembled into dinucleotides that are consistent with established RNA backbone descriptors spanning from sugar to sugar. We then use each library to build all-atom models of 20 test folds, and we show how the composition of a fragment library can limit model quality. Despite the limitations inherent in using discretized libraries, we find that several hundred discrete fragments can rebuild RNA folds up to 174 nucleotides in length with atomic-level accuracy (libraries presented here could easily be incorporated into RNA structural modeling, analysis, or refinement tools.

Elisabeth Humphris-Narayanan; Anna Marie Pyle

2012-01-01T23:59:59.000Z

339

Coded Adaptive Linear Precoded Discrete Multitone Over PLC Channel  

E-Print Network [OSTI]

Coded Adaptive Linear Precoded Discrete Multitone Over PLC Channel Fahad Syed Muhammmad, Jean- DMT system is presented in the power line communication (PLC) context with a loading algorithm which spectral density constraint. Using a multipath model of PLC channel, it is shown that the proposed coded

Boyer, Edmond

340

Discrete Mathematics 110 (1992) 43-59 North-Holland  

E-Print Network [OSTI]

' or `combine' de Bruijn cycles? (vii) What are the analogues for larger alphabets (k symbols rather than 2Discrete Mathematics 110 (1992) 43-59 North-Holland 43 Universal structures Fan Chung cycles Revised 12 April 1991 Abstract Chung, F., P. Diaconis and R. Graham, Universal cycles for combinatorial

Diaconis, Persi

Note: This page contains sample records for the topic "discrete space-time symmetries" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


341

The RUTGERS YOUNG SCHOLARS PROGRAM in DISCRETE MATHEMATICS  

E-Print Network [OSTI]

for Discrete Mathematics and Theoretical Computer Science [DIMACS], and is supported by a grant from school students who share your fascination with mathematics. ... attend a variety of mathematical assistants who are graduate and undergraduate Rutgers students majoring in mathematics or computer science

342

Nonconservative exact small-sample inference for discrete data  

Science Journals Connector (OSTI)

Exact small-sample methods for discrete data use probability distributions that do not depend on unknown parameters. However, they are conservative inferentially: the actual error probabilities for tests and confidence intervals are bounded above by ... Keywords: Binomial distribution, Clopper-Pearson confidence interval, Fuzzy inference, Mid-P-value

Alan Agresti; Anna Gottard

2007-08-01T23:59:59.000Z

343

Discrete Ordinate Method for Solving Inhomogeneous Vector Radiative Transfer Equation  

E-Print Network [OSTI]

paper.. This type of equation appears when modeling radiative transport in plane parallel media. WeDiscrete Ordinate Method for Solving Inhomogeneous Vector Radiative Transfer Equation We describe here a solution method for equations of the type given by: µ I(,µ) +I(,µ)- () 2 1 -1 Z(,µ,µ )I(,µ )dµ

Pattanaik, Sumanta N.

344

Sparse Twisted Tensor Frame Discretization Parametric Transport Operators  

E-Print Network [OSTI]

Parametric, high-dimensional transport Equations such as Vlasov-Poisson, Boltzmann and Radiative Transfer associated with the transport equation and by subsequent Galerkin discretization with a novel, sparse tensor of the phase space. In [22], for a model parametric transport problem arising in radiative transport, the use

Grohs, Philipp

345

Discrete wave turbulence of rotational capillary water waves  

E-Print Network [OSTI]

We study the discrete wave turbulent regime of capillary water waves with constant non-zero vorticity. The explicit Hamiltonian formulation and the corresponding coupling coefficient are obtained. We also present the construction and investigation of resonance clustering. Some physical implications of the obtained results are discussed.

Adrian Constantin; Elena Kartashova; Erik Wahlén

2010-05-12T23:59:59.000Z

346

Simulation on Discrete Fracture Network Using Flexible Voronoi Gridding  

E-Print Network [OSTI]

........................................... 3 1.2.2 Gridding Techniques ............................................................. 4 1.2.2.1 Globally Orthogonal Grid ...................................... 5 1.2.2.2 Corner Point Grid... ................................................... 5 1.2.3 Locally Orthogonal Grid ....................................................... 6 1.3 Introduction to Discrete Fracture Network Simulation ................... 7 1.4 Introduction to Fracture Aperture Measurement Using X-Ray CT...

Syihab, Zuher

2011-02-22T23:59:59.000Z

347

3D discrete rotations using hinge angles Yohan Thibaulta,  

E-Print Network [OSTI]

3D discrete rotations using hinge angles Yohan Thibaulta, , Akihiro Sugimotob , Yukiko Kenmochia a of Informatics, Japan Abstract In this paper, we study 3D rotations on grid points computed by using only integers. For that purpose, we investigate the intersection between the 3D half- grid and the rotation

Paris-Sud XI, Université de

348

New C*-completions of discrete groups and related spaces  

Science Journals Connector (OSTI)

......research-article PAPERS New C*-completions of discrete groups and related...associate a C*-algebra completion of the group ring that encapsulates...every ideal D (), the ideal completion C D() is a compact quantum...normal subgroup of infinite index. Suppose D1 () and D2......

Nathanial P. Brown; Erik P. Guentner

2013-12-01T23:59:59.000Z

349

Discrete Applied Mathematics 121 (2002) 139153 NeST graphs  

E-Print Network [OSTI]

Discrete Applied Mathematics 121 (2002) 139­153 NeST graphs Ryan B. Haywarda; , Paul E. Kearneyb; received in revised form 14 March 2001; accepted 26 March 2001 Abstract We establish results on NeST graphs show the equivalence of proper NeST graphs and unit NeST graphs, the equivalence of ÿxed distance NeST

Hayward, Ryan B.

350

Energy-Efficient Discrete Cosine Transform on Ronald Scrofano  

E-Print Network [OSTI]

Energy-Efficient Discrete Cosine Transform on FPGAs Ronald Scrofano Department of Computer Science is brought to mobile devices, it becomes important that it is possible to calculate the DCT in an energy-efficient the DCT with a linear array of PEs. This design is optimized for energy efficiency. We analyze the energy

Jang, Ju-Wook

351

Finite Element Discretization Strategies for the Inverse Electrocardiographic (ECG) Problem  

E-Print Network [OSTI]

Finite Element Discretization Strategies for the Inverse Electrocardiographic (ECG) Problem Dafang electrocardiographic (ECG) problems re- quires the ability to both quantify and minimize approxi- mation errors specifically for the inverse ECG prob- lem. By quantitatively analyzing the connection between the ill

Utah, University of

352

Extreme-Point Stability Tests for Discrete-Time Polynomials  

E-Print Network [OSTI]

TA9 -10:40 Extreme-Point Stability Tests for Discrete-Time Polynomials F. PCrez *, C been an increasinginterest in finding extreme- point results for the study of stability of uncertain in the coefficients space where Schur stability of the extremes im- plies the stability of the entire family 12). Our

353

DISCRETE QUANTUM MECHANICS AND THE SPEED OF LIGHT JOSEPH TOLES  

E-Print Network [OSTI]

DISCRETE QUANTUM MECHANICS AND THE SPEED OF LIGHT JOSEPH TOLES From S. McAdam, Unknowable Matters that nothing can travel faster than the speed of light. So instead of showing that it's impossible to determine the speed of light. 2. Associated Physics Photons are the smallest single unit of transverse electromagnetic

Morrow, James A.

354

Symmetry Breaking of H2 Dissociation by a Single Photon  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Symmetry Breaking of H2 Symmetry Breaking of H2 Dissociation by a Single Photon Symmetry Breaking of H2 Dissociation by a Single Photon Print Wednesday, 25 July 2007 00:00 A single hydrogen (or deuterium) molecule consists of only two protons (deuterons) and two electrons and is perfectly symmetric. Linearly polarized photons are similarly symmetric. So one might think that the angular distribution of photoelectrons resulting from photoionization of the molecule by the photon accompanied by dissociation into a hydrogen atom and a hydrogen ion would itself be symmetric. However, an international team of researchers from Germany, Spain, and the U.S. has now shown that this need not be the case. When there are multiple quantum paths for the process, interference between waves in the coherent superposition of electron states (which exists when the molecular fragments are still close together) skews the distribution by breaking the molecular symmetry.

355

New symmetry properties of pointlike scalar and Dirac particles  

E-Print Network [OSTI]

New symmetry properties are found for pointlike scalar and Dirac particles (Higgs boson and all leptons) in Riemannian spacetimes in the presence of electromagnetic interactions. A Hermitian form of the Klein-Gordon equation for a pointlike scalar particle in an arbitrary n-dimensional Riemannian spacetime is obtained. New conformal symmetries of initial and Hermitian forms of this equation are ascertained. In the above spacetime, general Hamiltonians in the generalized Feshbach-Villars and Foldy-Wouthuysen representations are derived. The conformal-like transformation conserving these Hamiltonians is found. Corresponding conformal symmetries of a Dirac particle are determined. It is proven that all conformal symmetries remain unchanged by an inclusion of electromagnetic interactions.

Alexander J. Silenko

2015-01-15T23:59:59.000Z

356

On a Broken Formal Symmetry between Kinetic and Gravitational Energy  

E-Print Network [OSTI]

Historically, the discovery of symmetries has played an important role in the progress of our fundamental understanding of nature. This paper will demonstrate that there exists in Newtonian theory in a spherical gravitational field a formal symmetry between the kinetic (KE) and gravitational potential energy (GPE) of a test mass. Put differently, there exists a way of expressing GPE such that the form of the mathematical expression remains invariant under an interchange of KE and GPE. When extended to relativity by a suitable assumption, it leads to a framework that bridges the general relativistic and Newtonian conceptions of gravitational energy, even though the symmetry is broken except in the infinitesimal limit. Recognizing this symmetry at infinitesimal scales makes it possible to write a relativistic equation of an individual graviton, the properties of which under under one interpretation may be unexpected.

Armin Nikkhah Shirazi

2014-07-16T23:59:59.000Z

357

Probing the density content of the nuclear symmetry energy  

Science Journals Connector (OSTI)

In this paper, we shall mainly focus on the behaviour of symmetry energy slope parameter L at densities close to ? 0. The value of L(? 0) has been shown [5] to be strongly correlat...

B K AGRAWAL; J N DE; S K SAMADDAR

2014-05-01T23:59:59.000Z

358

Magnetic Symmetry of Rare-Earth Orthochromites and Orthoferrites  

Science Journals Connector (OSTI)

A new magnetic symmetry of the rare-earth orthochromites and orthoferrites (RMO3) below the second Néel temperature due to the reordering of the rare-earth spins is proposed. It is shown that the magnetic symmetry group is lowered to the subgroup of index two, thereby keeping the unit cell invariant. The proposed symmetry is shown to be consistent with the previously observed spin configuration of RMO3 such as GdCrO3, DyFeO3, and DyCrO3, and would also be consistent with those of other RMO3. Although symmetry arguments and the calculation of the free energy show that two spin configurations are stable, in GdCrO3, a future measurement of the magnetoelectric tensor would determine which configuration GdCrO3 has. It is further predicted that the magnetoelectric effect should be observed in any RMO3 below the second Néel temperature.

Tsuyoshi Yamaguchi and Kunirô Tsushima

1973-12-01T23:59:59.000Z

359

Symmetry Breaking of H2 Dissociation by a Single Photon  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Symmetry Breaking of H2 Dissociation by a Single Photon Print A single hydrogen (or deuterium) molecule consists of only two protons (deuterons) and two electrons and is perfectly...

360

Dimensions of symmetry in syntax : agreement and clausal architecture  

E-Print Network [OSTI]

(cont.) are, then, determined at phase levels by late insertion of categorial features. One crucial aspect of the proposed theory of structural symmetry involves interweaving effects, which emerge as categorial determination ...

Hiraiwa, Ken, 1974-

2005-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


361

Symmetry Constraints on the Dynamics of Magnetically Confined Plasma  

SciTech Connect (OSTI)

In respect of their symmetry properties, toroidal magnetically confined plasmas have much in common with the Taylor-Couette flow. A symmetry-based analysis (equivalent bifurction theory) has proved very powerful in the analysis of the latter problem. This Letter discusses the applicability of the method to nuclear fusion experiments such as tokamaks and pinches. The likely behavior of the simplest models of rotationally symmetric tokamaks is described, and found to be potentially consistent with observation.

Arter, Wayne [EURATOM/UKAEA Fusion Association, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom)

2009-05-15T23:59:59.000Z

362

Anatomy of symmetry energy of dilute nuclear matter  

E-Print Network [OSTI]

The symmetry energy coefficients of dilute clusterized nuclear matter are evaluated in the $S$-matrix framework. Employing a few different definitions commonly used in the literature for uniform nuclear matter, it is seen that the different definitions lead to perceptibly different results for the symmetry coefficients for dilute nuclear matter. They are found to be higher compared to those obtained for uniform matter in the low density domain. The calculated results are in reasonable consonance with those extracted recently from experimental data.

J. N. De; S. K. Samaddar; B. K. Agrawal

2010-09-23T23:59:59.000Z

363

What Have Spacetime, Shape and Symmetry to Do with Thermodynamics?  

E-Print Network [OSTI]

Some highly speculative and serendipitous ideas that might relate thermodynamics, spacetime, shape and symmetry are brought together. A hypothetical spacetime comprising a pointwise lattice with a fixed metric is considered. If there were absolute symmetry between displacement and time it is suggested that the velocity of light would be an integer conversion factor between the units of these quantities. In the context of such outlandish hypotheses the answer to the question posed would be 'everything'.

Jim McGovern

2007-10-05T23:59:59.000Z

364

Symmetry energy for fragmentation in dynamical nuclear collisions  

SciTech Connect (OSTI)

We extract values for the free symmetry energy as a function of the fragment size (the proton number Z) from antisymmetrized molecular dynamics calculations of calcium collisions. Simple statistical physics describe well the distribution of hot nuclei at breakup, provided the surface symmetry term in the free energy is much smaller at high excitation than in ground state nuclei. This result may reflect the condition of low density and finite temperature when these systems disassemble.

Ono, Akira [Department of Physics, Tohoku University, Sendai 980-8578 (Japan); Danielewicz, P.; Lynch, W.G.; Tsang, M.B. [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824 (United States); Friedman, W.A. [Department of Physics, University of Wisconsin, Madison, Wisconsin 53706 (United States)

2004-10-01T23:59:59.000Z

365

Touch-down and take-off hysteresis of magnetic recording sliders on discrete track media  

Science Journals Connector (OSTI)

The flying behavior of a slider over discrete track ... by the presence of the grooves on the disk. In particular, the steady state flying height of a slider flying over discrete track media is lower than that of...

Y. Yoon; F. E. Talke

2010-01-01T23:59:59.000Z

366

Crystal-symmetry preserving Wannier states for fractional Chern insulators  

Science Journals Connector (OSTI)

Recently, many numerical evidences of fractional Chern insulator, i.e., the fractional quantum Hall states on lattices, are proposed when a Chern band is partially filled. Some trial wave functions of fractional Chern insulators can be obtained by mapping the fractional quantum Hall wave functions defined in the continuum onto the lattice through the Wannier state representation [Phys. Rev. Lett. 107, 126803 (2011)] in which the single particle Landau orbits in the Landau levels are identified with the one-dimensional Wannier states of the Chern bands with Chern number C=1. However, this mapping generically breaks the lattice point group symmetry. In this paper we discuss a general approach of modifying the mapping to accommodate the lattice rotational symmetry. The wave functions constructed through this modified mapping should serve as better trial wave functions in the thermodynamical limit and on the rotationally invariant finite lattice. Also these wave functions will form a good basis for the construction of lattice symmetry preserving pseudopotential formalism for fractional Chern insulators. The focus of this paper shall be mainly on the C4 rotational symmetry of square lattices. Similar analysis can be straightforwardly generalized to triangular or hexagonal lattices with C6 symmetry. We also generalize the discussion to the lattice symmetry of fractional Chern insulators with high Chern number bands.

Chao-Ming Jian and Xiao-Liang Qi

2013-10-25T23:59:59.000Z

367

Continued Fraction Expansion Approaches to Discretizing Fractional Order Derivatives—an Expository Review  

Science Journals Connector (OSTI)

This paper attempts to present an expository review of continued fraction expansion (CFE) based discretization schemes for fractional order differentiators...

Yangquan Chen; Blas M. Vinagre; Igor Podlubny

2004-12-01T23:59:59.000Z

368

Breakdown of 2mm symmetry in electron diffraction from multiwalled carbon nanotubes  

E-Print Network [OSTI]

Breakdown of 2mm symmetry in electron diffraction from multiwalled carbon nanotubes Zejian Liu of single-walled carbon nanotubes always have 2mm symmetry regardless if the nanotubes them- selves have such symmetry. We here show that, for the case of multiwalled carbon nanotubes, the 2mm symmetry can break down

Qin, Lu-Chang

369

TIME DISCRETE GEODESIC PATHS IN THE SPACE OF IMAGES B. BERKELS, A. EFFLAND, M. RUMPF  

E-Print Network [OSTI]

TIME DISCRETE GEODESIC PATHS IN THE SPACE OF IMAGES B. BERKELS, A. EFFLAND, M. RUMPF Abstract and intensity variation. A robust and effective variational time discretization of geodesics paths is proposed requirements for the input images, the existence of discrete geodesic paths defined as minimizers

Rumpf, Martin

370

DISCRETE GEODESIC CALCULUS IN THE SPACE OF VISCOUS FLUIDIC MARTIN RUMPF AND BENEDIKT WIRTH  

E-Print Network [OSTI]

DISCRETE GEODESIC CALCULUS IN THE SPACE OF VISCOUS FLUIDIC OBJECTS MARTIN RUMPF AND BENEDIKT WIRTH cheap dissimilarity measure, a time discrete geodesic calculus is developed, and applications to shape in shape space. The notion of discrete geodesics defined as energy minimizing paths gives rise

Rumpf, Martin

371

Numerical study of natural convection in a vertical porous annulus with discrete heating  

E-Print Network [OSTI]

Numerical study of natural convection in a vertical porous annulus with discrete heating M. Sankar online 20 December 2010 Keywords: Natural convection Annulus Discrete heating Porous medium Radii ratio to discrete heating. The outer wall is maintained iso- thermally at a lower temperature, while the top

Lopez, John M.

372

A DUALITY APPROACH TO THE GENEALOGIES OF DISCRETE NON-NEUTRAL WRIGHT-FISHER MODELS  

E-Print Network [OSTI]

A DUALITY APPROACH TO THE GENEALOGIES OF DISCRETE NON-NEUTRAL WRIGHT-FISHER MODELS THIERRY E formu- lae still are of great use when considering discrete non-neutral Wright-Fisher models, Running title: Duality and Discrete Non-Neutral Wright-Fisher Models. Keywords: Wright-Fisher Models

Paris-Sud XI, Université de

373

Controllable discrete diffraction in cascade-induced waveguides  

SciTech Connect (OSTI)

A new method for generating periodic lattices in quadratically nonlinear media by the three-wave cascade interaction is proposed. This method allows one to obtain stable structures with changeable parameters. These structures make it possible to realise the all-optical control of the character of the laser beam propagation. The use of the discrete diffraction allows the signal multiplexing in optical processing and information transfer devices and the control of the number of channels at the crystal output. The effect of the discrete diffraction anisotropy in the system of induced waveguides makes it possible to redistribute in the specified way the energy in the channels at the output. It is shown that the optical switching efficiency is maximal in the regime of the transverse Bragg resonance. The signal switching rate in optical lattices induced in a quadratically nonlinear medium is limited by the time of light propagation though the crystal and can achieve several terahertz. (nonlinear optical phenomena)

Borovkova, O V; Lobanov, V E; Sukhorukov, Anatolii P [M. V. Lomonosov Moscow State University, Faculty of Physics, Moscow (Russian Federation); Sukhorukova, A K [Russian State Geological Prospecting University, Moscow (Russian Federation)

2009-11-30T23:59:59.000Z

374

Fast Computation Algorithm for Discrete Resonances among Gravity Waves  

E-Print Network [OSTI]

Traditionally resonant interactions among short waves, with large real wave-numbers, were described statistically and only a small domain in spectral space with integer wave-numbers, discrete resonances, had to be studied separately in resonators. Numerical simulations of the last few years showed unambiguously the existence of some discrete effects in the short-waves part of the wave spectrum. Newly presented model of laminated turbulence explains theoretically appearance of these effects thus putting a novel problem - construction of fast algorithms for computation of solutions of resonance conditions with integer wave-numbers of order $10^3$ and more. Example of such an algorithm for 4-waves interactions of gravity waves is given. Its generalization on the different types of waves is briefly discussed.

Elena Kartashova

2006-05-25T23:59:59.000Z

375

Quantum Mechanics and Discrete Time from "Timeless" Classical Dynamics  

E-Print Network [OSTI]

We study classical Hamiltonian systems in which the intrinsic proper time evolution parameter is related through a probability distribution to the physical time, which is assumed to be discrete. - This is motivated by the ``timeless'' reparametrization invariant model of a relativistic particle with two compactified extradimensions. In this example, discrete physical time is constructed based on quasi-local observables. - Generally, employing the path-integral formulation of classical mechanics developed by Gozzi et al., we show that these deterministic classical systems can be naturally described as unitary quantum mechanical models. The emergent quantum Hamiltonian is derived from the underlying classical one. It is closely related to the Liouville operator. We demonstrate in several examples the necessity of regularization, in order to arrive at quantum models with bounded spectrum and stable groundstate.

H. -T. Elze

2003-07-03T23:59:59.000Z

376

Mechanism for a bounded and discrete mass spectrum of fermions  

E-Print Network [OSTI]

A mechanism for determining fermion masses in four spacetime dimensions is presented, which uses a scalar-field domain wall extending in a fifth spacelike dimension and a special choice of Yukawa coupling constants. A bounded and discrete fermion mass spectrum is obtained, which depends on a combination of the Yukawa coupling constants and the parameters of the scalar potential. A similar mechanism for a finite mass spectrum may apply to $(1+1)$--dimensional fermions relevant to condensed matter physics.

Klinkhamer, F R

2014-01-01T23:59:59.000Z

377

Renormalized waves and discrete breathers in $?$-FPU chains  

E-Print Network [OSTI]

We demonstrate via numerical simulation that in the \\textit{strongly} nonlinear limit, the $\\beta$-FPU system in thermal equilibrium behaves surprisingly like weakly nonlinear waves in properly renormalized normal variables. This arises because the collective effect of strongly nonlinear interactions effectively renormalizes linear dispersion frequency and leads to effectively weak interaction among these renormalized waves. Furthermore, we show that the dynamical scenario for thermalized $\\beta$-FPU chains is spatially highly localized discrete breathers riding chaotically on spatially extended, renormalized waves.

Boris Gershgorin; Yuri V. Lvov; David Cai

2005-08-20T23:59:59.000Z

378

On classification of second-order PDEs possessing partner symmetries  

Science Journals Connector (OSTI)

Recently we have demonstrated how to use partner symmetries for obtaining noninvariant solutions of the heavenly equations of Plebañski that govern heavenly gravitational metrics. In this paper, we present a classification of scalar second-order PDEs with four variables that possess partner symmetries and contain only second derivatives of the unknown. We present a general form of such a PDE together with recursion relations between partner symmetries. This general PDE is transformed to several simplest canonical forms containing two heavenly equations of Plebañski among them and two other nonlinear equations which we call the mixed heavenly equation and asymmetric heavenly equation. We have calculated all the point and contact symmetries of all the canonical equations which can be used as an input in our recursion relations. On an example of the mixed heavenly equation, we show how to use partner symmetries for obtaining noninvariant solutions of PDEs by a lift from invariant solutions. Finally, we present Ricci-flat self-dual metrics governed by solutions of the mixed heavenly equation and its Legendre transform.

M B Sheftel; A A Malykh

2009-01-01T23:59:59.000Z

379

Symmetries of asymptotically flat electrovacuum spacetimes and radiation  

E-Print Network [OSTI]

Symmetries compatible with asymptotic flatness and admitting gravitational and electromagnetic radiation are studied by using the Bondi-Sachs-van der Burg formalism. It is shown that in axially symmetric electrovacuum spacetimes in which at least locally a smooth null infinity in the sense of Penrose exists, the only second allowable symmetry is either the translational symmetry or the boost symmetry. Translationally invariant spacetimes with in general a straight "cosmic string" along the axis of symmetry are non-radiative although they can have a non-vanishing news function. The boost-rotation symmetric spacetimes are radiative. They describe "uniformly accelerated charged particles" or black holes which in general may also be rotating - the axial and an additional Killing vector are not assumed to be hypersurface orthogonal. The general functional forms of both gravitational and electromagnetic news functions, and of the mass aspect and total mass of asymptotically flat boost-rotation symmetric spacetimes at null infinity are obtained. The expressions for the mass are new even in the case of vacuum boost-rotation symmetric spacetimes with hypersurface orthogonal Killing vectors. In Appendices some errors appearing in previous works are corrected.

J. Bicak; A. Pravdova

1998-08-25T23:59:59.000Z

380

Symmetry Energy from Systematic of Isobaric Analog States  

E-Print Network [OSTI]

Excitation energies to isobaric states, that are analogs of ground states, are dominated by contributions from the symmetry energy. This opens up a possibility of investigating the symmetry energy on nucleus-by-nucleus basis. Upon correcting energies of measured nuclear levels for shell and pairing effects, we find that the lowest energies for a given isospin rise in proportion to the square of isospin, allowing for an interpretation of the coefficient of proportionality in terms of a symmetry coefficient for a given nucleus. In the (A,Z) regions where there are enough data, we demonstrate a Z-independence of that coefficient. We further concentrate on the A-dependence of the coefficient, in order to learn about the density dependence of symmetry energy in uniform matter, given the changes of the density in the surface region. In parallel to the analysis of data, we carry out an analysis of the coefficient for nuclei calculated within the Skyrme-Hartree-Fock (SHF) approach, with known symmetry energy for unif...

Danielewicz, Pawel

2011-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


381

Symmetry tuning for ignition capsules via the symcap technique  

SciTech Connect (OSTI)

Symmetry of an implosion is crucial to get ignition successfully. Several methods of control and measurement of symmetry have been applied on many laser systems with mm size hohlraums and ns pulses. On the National Ignition Facility [Moses et al., Phys. Plasmas 16, 041006 (2009)] we have large hohlraums of cm scale, long drive pulses of 10 s of ns, and a large number of beams with the option to tune their wavelengths. Here we discuss how we used the x-ray self-emission from imploding surrogates to ignition capsules (symcaps) to measure the symmetry of the implosion. We show that symcaps are good surrogates for low order symmetry, though having lower sensitivity to distortions than ignition capsules. We demonstrate the ability to transfer energy between laser beams in a gas-filled hohlraum using wavelength tuning, successfully tuning the lowest order symmetry of the symcaps in different size hohlraums at different laser energies within the specification established by calculations for successful ignition.

Kyrala, G. A.; Kline, J. L. [Los Alamos National Laboratory, P.O. Box 1663, MS E-526, Los Alamos, New Mexico 87544 (United States); Dixit, S.; Glenzer, S.; Kalantar, D.; Bradley, D.; Izumi, N.; Meezan, N.; Landen, O.; Callahan, D.; Weber, S. V.; Holder, J. P.; Glenn, S.; Edwards, M. J.; Koch, J.; Suter, L. J.; Haan, S. W.; Town, R. P. J.; Michel, P.; Jones, O. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)

2011-05-15T23:59:59.000Z

382

Symmetry Breaking of H2 Dissociation by a Single Photon  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Symmetry Breaking of H2 Dissociation by a Single Photon Print Symmetry Breaking of H2 Dissociation by a Single Photon Print A single hydrogen (or deuterium) molecule consists of only two protons (deuterons) and two electrons and is perfectly symmetric. Linearly polarized photons are similarly symmetric. So one might think that the angular distribution of photoelectrons resulting from photoionization of the molecule by the photon accompanied by dissociation into a hydrogen atom and a hydrogen ion would itself be symmetric. However, an international team of researchers from Germany, Spain, and the U.S. has now shown that this need not be the case. When there are multiple quantum paths for the process, interference between waves in the coherent superposition of electron states (which exists when the molecular fragments are still close together) skews the distribution by breaking the molecular symmetry.

383

Symmetry Breaking of H2 Dissociation by a Single Photon  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Symmetry Breaking of H2 Dissociation by a Single Photon Print Symmetry Breaking of H2 Dissociation by a Single Photon Print A single hydrogen (or deuterium) molecule consists of only two protons (deuterons) and two electrons and is perfectly symmetric. Linearly polarized photons are similarly symmetric. So one might think that the angular distribution of photoelectrons resulting from photoionization of the molecule by the photon accompanied by dissociation into a hydrogen atom and a hydrogen ion would itself be symmetric. However, an international team of researchers from Germany, Spain, and the U.S. has now shown that this need not be the case. When there are multiple quantum paths for the process, interference between waves in the coherent superposition of electron states (which exists when the molecular fragments are still close together) skews the distribution by breaking the molecular symmetry.

384

Domain Walls and Vortices in Chiral Symmetry Breaking  

E-Print Network [OSTI]

We study domain walls and vortices in chiral symmetry breaking in a QCD-like theory with N flavors in the chiral limit. If the axial anomaly is absent, there exist stable Abelian axial vortices winding around the spontaneously broken U(1)_A symmetry and non-Abelian axial vortices winding around both the U(1)_A and non-Abelian SU(N) chiral symmetries. In the presence of the axial anomaly term, metastable domain walls are present and Abelian axial vortices must be attached by N domain walls, forming domain wall junctions. We show that a domain wall junction decays into N non-Abelian vortices attached by domain walls, implying its metastability. We also show that domain walls decay through the quantum tunneling by creating a hole bounded by a closed non-Abelian vortex.

Minoru Eto; Yuji Hirono; Muneto Nitta

2013-09-18T23:59:59.000Z

385

Symmetry group analysis of an ideal plastic flow  

E-Print Network [OSTI]

In this paper, we study the Lie point symmetry group of a system describing an ideal plastic plane flow in two dimensions in order to find analytical solutions. The infinitesimal generators that span the Lie algebra for this system are obtained. We completely classify the subalgebras of up to codimension two in conjugacy classes under the action of the symmetry group. Based on invariant forms, we use Ansatzes to compute symmetry reductions in such a way that the obtained solutions cover simultaneously many invariant and partially invariant solutions. We calculate solutions of the algebraic, trigonometric, inverse trigonometric and elliptic type. Some solutions depending on one or two arbitrary functions of one variable have also been found. In some cases, the shape of a potentially feasible extrusion die corresponding to the solution is deduced. These tools could be used to thin, curve, undulate or shape a ring in an ideal plastic material.

Vincent Lamothe

2011-02-11T23:59:59.000Z

386

Consistency condition for inflation from (broken) conformal symmetry  

SciTech Connect (OSTI)

We investigate the symmetry constraints on the bispectrum, i.e. the three-point correlation function of primordial density fluctuations, in slow-roll inflation. It follows from the defining property of slow-roll inflation that primordial correlation functions inherit most of their structure from weakly broken de Sitter symmetries. Using holographic techniques borrowed from the AdS/CFT correspondence, the symmetry constraints on the bispectrum can be mapped to a set of stress-tensor Ward identities in a weakly broken 2+1-dimensional Euclidean CFT. We construct the consistency condition from these Ward identities using conformal perturbation theory. This requires a second order Ward identity and the use of the evolution equation. Our result also illustrates a subtle difference between conformal perturbation theory and the slow-roll expansion.

Schalm, Koenraad; Aalst, Ted van der [Instituut-Lorentz for Theoretical Physics, Universiteit Leiden, Niels Bohrweg 2, Leiden (Netherlands); Shiu, Gary, E-mail: kschalm@lorentz.leidenuniv.nl, E-mail: shiu@physics.wisc.edu, E-mail: vdaalst@lorentz.leidenuniv.nl [Department of Physics, University of Wisconsin-Madison, Madison, WI 53706 (United States)

2013-03-01T23:59:59.000Z

387

Role of density dependent symmetry energy in nuclear stopping  

E-Print Network [OSTI]

Information about the nuclear matter under the extreme conditions of temperature and density and the role of symmetry energy under these conditions is still a topic of crucial importance in the present day nuclear physics research. The multifragmentation, collective flow and the nuclear stopping is among the various rare phenomenon which can be observed in heavy-ion collisions at intermediate energies. The nuclear stopping, which is sensitive towards the symmetry energy has gained a lot of interest because it provides the possibility to examine the degree of thermalization or equilibration in the matter. Aim of the present study is to pin down the nuclear stopping for the different forms of density dependent symmetry energy

Karan Singh Vinayak; Suneel Kumar

2011-07-27T23:59:59.000Z

388

Mechanical similarity as a generalization of scale symmetry  

E-Print Network [OSTI]

In this paper we study the symmetry known as mechanical similarity (LMS) and present for any monomial potential. We analyze it in the framework of the Koopman-von Neumann formulation of classical mechanics and prove that in this framework the LMS can be given a canonical implementation. We also show that the LMS is a generalization of the scale symmetry which is present only for the inverse square potential. Finally we study the main obstructions which one encounters in implementing the LMS at the quantum mechanical level.

E. Gozzi; D. Mauro

2005-08-26T23:59:59.000Z

389

Symmetries of geodesic motion in Gödel-type spacetimes  

E-Print Network [OSTI]

In this paper, we study Noether gauge symmetries of geodesic motion for geodesic Lagrangian of four classes of metrics of G\\"{o}del-type spacetimes for which we calculated the Noether gauge symmetries for all classes I-IV, and find the first integrals of corresponding classes to derive a complete characterization of the geodesic motion. Using the obtained expressions for $\\dot{t}, \\dot{r}, \\dot{\\phi}$ and $\\dot{z}$ of each classes I-IV which depends essentially on two independent parameters $m$ and $w$, we explicitly integrated the geodesic equations of motion for the corresponding G\\"{o}del-type spacetimes.

U. Camci

2014-05-15T23:59:59.000Z

390

Considering relativistic symmetry as the first principle of quantum mechanics  

E-Print Network [OSTI]

On the basis of the relativistic symmetry of Minkowski space, we derive a Lorentz invariant equation for a spread electron. This equation slightly differs from the Dirac equation and includes additional terms originating from the spread of an electron. Further, we calculate the anomalous magnetic moment based on these terms. These calculations do not include any divergence; therefore, renormalization procedures are unnecessary. In addition, the relativistic symmetry existing among coordinate systems will provide a new prospect for the foundations of quantum mechanics like the measurement process.

T. Kawahara

2007-04-20T23:59:59.000Z

391

Dual Models with Global SU(2,2) Symmetry  

Science Journals Connector (OSTI)

The possibility of enlarging the gauge symmetry of the dual resonance models is considered by studying the structure of SU(2,2)- [or SO(4,2)] invariant dual models. n-point functions based on the degenerate representations of SU(2,2) are worked out in detail, and a condition under which these amplitudes are dual is specified. Dual models based on the nondegenerate representations are also discussed. Through a physical interpretation of the characteristics which emerge, a possible connection between the dimension N-1 of the hadronic matter and the gauge-symmetry group SO(N, 2) is pointed out.

Freydoon Mansouri

1973-08-15T23:59:59.000Z

392

The origin of order in random matrices with symmetries  

E-Print Network [OSTI]

From Noether's theorem we know symmetries lead to conservation laws. What is left to nature is the ordering of conserved quantities; for example, the quantum numbers of the ground state. In physical systems the ground state is generally associated with `low' quantum numbers and symmetric, low-dimensional irreps, but there is no \\textit{a priori} reason to expect this. By constructing random matrices with nontrivial point-group symmetries, I find the ground state is always dominated by extremal low-dimensional irreps. Going further, I suggest this explains the dominance of J=0 g.s. even for random two-body interactions.

Calvin W. Johnson

2012-06-25T23:59:59.000Z

393

CPT- and Lorentz-symmetry breaking: a review  

E-Print Network [OSTI]

The breakdown of spacetime symmetries has recently been identified as a promising candidate signal for underlying physics, possibly arising through quantum-gravitational effects. This talk gives an overview over various aspects of CPT- and Lorentz-violation research. Particular emphasis is given to the interplay between CPT, Lorentz, and translation symmetry, mechanisms for CPT and Lorentz breaking, and the construction of a low-energy quantum-field description of such effect. This quantum field framework, called the SME, is employed to determine possible phenomenological consequences of CPT and Lorentz violation for neutral-meson interferometry.

Ralf Lehnert

2006-12-28T23:59:59.000Z

394

Chiral and Heavy Quark Symmetry Violation in B Decays  

E-Print Network [OSTI]

The most general Lagrangian consistent with chiral, heavy quark, and strong interaction symmetries to order $1/M$ and to linear order in the SU(3) vector and axial currents is presented. Two new dimensionful and five dimensionless couplings arise at this order. The heavy to light flavor changing current is derived to the same order, giving rise to two additional dimensionful constants and six dimensionless ones. The dimensionless parameters are shown to be irrelevant at \\ord. The leading nonanalytic heavy quark and chiral symmetry violating corrections to heavy meson decay constants are computed, and implications to B decays are discussed; measurements of the experimentally accessible form factors for $D \\to \\pi l \

C. G. Boyd; B. Grinstein

1994-02-22T23:59:59.000Z

395

Infinitely many local higher symmetries without recursion operator or master symmetry: integrability of the Foursov--Burgers system revisited  

E-Print Network [OSTI]

We consider the Burgers-type system studied by Foursov, w_t &=& w_{xx} + 8 w w_x + (2-4\\alpha)z z_x, z_t &=& (1-2\\alpha)z_{xx} - 4\\alpha z w_x + (4-8\\alpha)w z_x - (4+8\\alpha)w^2 z + (-2+4\\alpha)z^3, (*) for which no recursion operator or master symmetry was known so far, and prove that the system (*) admits infinitely many local generalized symmetries that are constructed using a nonlocal {\\em two-term} recursion relation rather than from a recursion operator.

Artur Sergyeyev

2008-04-12T23:59:59.000Z

396

Magnus force in discrete and continuous two-dimensional superfluids  

SciTech Connect (OSTI)

Motion of vortices in two-dimensional superfluids in the classical limit is studied by solving the Gross-Pitaevskii equation numerically on a uniform lattice. We find that, in the presence of a superflow directed along one of the main lattice periods, vortices move with the superflow on fine lattices but perpendicular to it on coarse ones. We interpret this result as a transition from the full Magnus force in a Galilean-invariant limit to vanishing effective Magnus force in a discrete system, in agreement with the existing experiments on vortex motion in Josephson junction arrays.

Gecse, Z.; Khlebnikov, S. [Department of Physics, Purdue University, West Lafayette, Indiana 47907 (United States)

2005-08-01T23:59:59.000Z

397

Equilibria and Instabilities of a Slinky: Discrete Model  

E-Print Network [OSTI]

The Slinky is a well-known example of a highly flexible helical spring, exhibiting large, geometrically nonlinear deformations from minimal applied forces. By considering it as a system of coils that act to resist axial, shearing, and rotational deformations, we develop a discretized model to predict the equilibrium configurations of a Slinky via the minimization of its potential energy. Careful consideration of the contact between coils enables this procedure to accurately describe the shape and stability of the Slinky under different modes of deformation. In addition, we provide simple geometric and material relations that describe a scaling of the general behavior of flexible, helical springs.

Douglas P. Holmes; Andy D. Borum; Billy F. Moore III; Raymond H. Plaut; David A. Dillard

2014-03-26T23:59:59.000Z

398

A discrete-event simulation model for seaport operations.  

SciTech Connect (OSTI)

Discrete-event simulation has been used to assess detailed processes at seaports. Seaport operations are labor-intensive and require extensive use of personnel and machinery. The ability to conduct seaport operations efficiently can be improved significantly through proper utilization of seaport assets. The simulation described has been written in MODSIM II and addresses seaport operations in the context of military mobility. The simulation allows for multiple cargo types as well as multiple ship types. The overall goal of the simulation has been to determine seaport throughput capability.

Nevins, M. R.; Macal, C. M.; Joines, J.; Decision and Information Sciences; Transportation Engineering Agency

1998-01-01T23:59:59.000Z

399

Particle-hole symmetry broken pseudogap in high temperature superconductors  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Particle-hole symmetry broken pseudogap in Particle-hole symmetry broken pseudogap in high temperature superconductors High-temperature (Tc) superconductivity is one of the most important topics in condensed matter physics. Despite extensive studies over more than two decades, the microscopic mechanism of high temperature superconductivity still remains elusive due to many unconventional properties that are not well understood. Among them, the most mysterious behavior of high-Tc superconductor is the nature of so called "pseudogap", which has been a focus of the field for many years. In conventional superconductors, a gap exists in the energy absorption spectrum only below Tc, corresponding to the energy price to pay for breaking a Cooper pair of electrons. In high-Tc cuprate superconductors, an energy gap called the pseudogap exists above Tc but below T*, and is controversially attributed either to pre-formed superconducting pairs or to competing phases. Recently, by carefully studying the "symmetry" of the gap, researchers Makoto Hashimoto and Rui-Hua He, along with their co-workers in Prof. Zhi-Xun Shen's group at Stanford University, have found crucial evidence suggesting that the particle-hole symmetry required by superconductivity is broken in the pseudogap state.

400

Is the Standard Model saved asymptotically by conformal symmetry?  

E-Print Network [OSTI]

It is pointed out that the top-quark and Higgs masses and the Higgs VEV satisfy with great accuracy the relations 4m_H^2=2m_T^2=v^2, which are very special and reminiscent of analogous ones at Argyres - Douglas points with enhanced conformal symmetry. Furthermore, the RG evolution of the corresponding Higgs self-interaction and Yukawa couplings \\lambda(0)=1/8 and y(0)=1 leads to the free-field stable point \\lambda(M_Pl)= \\dot \\lambda(M_Pl)=0 in the pure scalar sector at the Planck scale, also suggesting enhanced conformal symmetry. Thus, it is conceivable that the Standard Model is the low-energy limit of a distinct special theory with (super?) conformal symmetry at the Planck scale. In the context of such a "scenario" one may further speculate that the Higgs particle is the Goldstone boson of (partly) spontaneously broken conformal symmetry. This would simultaneously resolve the hierarchy and Landau pole problems in the scalar sector and would provide a nearly flat potential with two almost degenerate minima at the electroweak and Planck scales.

A. Gorsky; A. Mironov; A. Morozov; T. N. Tomaras

2014-09-01T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


401

Is the Standard Model saved asymptotically by conformal symmetry?  

E-Print Network [OSTI]

It is pointed out that the top-quark and Higgs masses and the Higgs VEV satisfy with great accuracy the relations 4m_H^2=2m_T^2=v^2, which are very special and reminiscent of analogous ones at Argyres - Douglas points with enhanced conformal symmetry. Furthermore, the RG evolution of the corresponding Higgs self-interaction and Yukawa couplings \\lambda(0)=1/8 and y(0)=1 leads to the free-field stable point \\lambda(M_Pl)= \\dot \\lambda(M_Pl)=0 in the pure scalar sector at the Planck scale, also suggesting enhanced conformal symmetry. Thus, it is conceivable that the Standard Model is the low-energy limit of a distinct special theory with (super?) conformal symmetry at the Planck scale. In the context of such a "scenario" one may further speculate that the Higgs particle is the Goldstone boson of (partly) spontaneously broken conformal symmetry. This would simultaneously resolve the hierarchy and Landau pole problems in the scalar sector and would provide a nearly flat potential with two almost degenerate minima...

Gorsky, A; Morozov, A; Tomaras, T N

2014-01-01T23:59:59.000Z

402

CP and other gauge symmetries in string theory  

Science Journals Connector (OSTI)

We argue that CP is a gauge symmetry in string theory. As a consequence, CP cannot be explicitly broken either perturbatively or nonperturbatively; there can be no nonperturbative CP-violating parameters. String theory is thus an example of a theory where all ? angles arise due to spontaneous CP violation, and are in principle calculable.

Michael Dine; Robert G. Leigh; Douglas A. MacIntire

1992-10-05T23:59:59.000Z

403

Observation time scale, free-energy landscapes, and molecular symmetry  

E-Print Network [OSTI]

Observation time scale, free-energy landscapes, and molecular symmetry David J. Walesa,1 and Peter structures that interconvert on a given time scale are lumped together, the corresponding free-energy surface that are connected by free-energy barriers below a certain threshold. We illustrate this time dependence for some

Salamon, Peter

404

Symmetry and dynamics of molecular rotors in amphidynamic molecular crystals  

Science Journals Connector (OSTI)

...axial symmetry order Cn represented with a heavy line with the enclosure formed by their close...Nano & Molecular Medicine, University of Missouri-Columbia...20 g of a 60% dispersion in mineral oil) in 500 mL of 1,2-dimethoxyethane...

Steven D. Karlen; Horacio Reyes; R. E. Taylor; Saeed I. Khan; M. Frederick Hawthorne; Miguel A. Garcia-Garibay

2010-01-01T23:59:59.000Z

405

Nuclear Symmetry Energy in Relativistic Mean Field Theory  

E-Print Network [OSTI]

The Physical origin of the nuclear symmetry energy is studied within the relativistic mean field (RMF) theory. Based on the nuclear binding energies calculated with and without mean isovector potential for several isobaric chains we conform earlier Skyrme-Hartree-Fock result that the nuclear symmetry energy strength depends on the mean level spacing $\\epsilon (A)$ and an effective mean isovector potential strength $\\kappa (A)$. A detaied analysis of isospin dependence of the two components contributing to the nuclear symmetry energy reveals a quadratic dependence due to the mean-isoscalar potential, $\\sim\\epsilon T^2$, and, completely unexpectedly, the presence of a strong linear component $\\sim\\kappa T(T+1+\\epsilon/\\kappa)$ in the isovector potential. The latter generates a nuclear symmetry energy in RMF theory that is proportional to $E_{sym}\\sim T(T+1)$ at variance to the non-relativistic calculation. The origin of the linear term in RMF theory needs to be further explored.

Shufang Ban; Jie Meng; Wojciech Satula; Ramon A. Wyss

2005-09-12T23:59:59.000Z

406

Symmetry energy in the structure and in reactions  

E-Print Network [OSTI]

Efforts to extract information on magnitude and density dependence of the nuclear symmetry energy are discussed. The utilized data include those on mass dependence of the excitation energies to the isobaric analog states of ground states, as well as data on the diffusion of isospin in heavy-ion reactions. Results following from different observables are compared.

P. Danielewicz

2010-03-21T23:59:59.000Z

407

Symmetry energy in the structure and in reactions  

E-Print Network [OSTI]

Efforts to extract information on magnitude and density dependence of the nuclear symmetry energy are discussed. The utilized data include those on mass dependence of the excitation energies to the isobaric analog states of ground states, as well as data on the diffusion of isospin in heavy-ion reactions. Results following from different observables are compared.

Danielewicz, P

2010-01-01T23:59:59.000Z

408

The Eightfold Way: A Theory of Strong Interaction Symmetry  

DOE R&D Accomplishments [OSTI]

A new model of the higher symmetry of elementary particles is introduced ln which the eight known baryons are treated as a supermultiplet, degenerate in the limit of unitary symmetry but split into isotopic spin multiplets by a symmetry-breaking term. The symmetry violation is ascribed phenomenologically to the mass differences. The baryons correspond to an eight-dimensional irreducible representation of the unitary group. The pion and K meson fit into a similar set of eight particles along with a predicted pseudoscalar meson X {sup o} having I = 0. A ninth vector meson coupled to the baryon current can be accommodated naturally in the scheme. It is predicted that the eight baryons should all have the same spin and parity and that pseudoscalar and vector mesons should form octets with possible additional singlets. The mathematics of the unitary group is described by considering three fictitious leptons, nu , e {sup -}, and mu {sup -}, which may throw light on the structure of weak interactions. (D. L.C.)

Gell-Mann, M.

1961-03-15T23:59:59.000Z

409

$\\mu$-$\\tau$ reflection symmetry and radiative corrections  

E-Print Network [OSTI]

The $\\mu$-$\\tau$ reflection symmetry is compatible with current neutrino oscillation data and easily realized under family symmetries. We prove that this symmetry preserves $\\theta_{23}=45^\\circ$, $\\delta=\\pm90^\\circ$, $\\rho,\\sigma=0,90^\\circ$, and can be embedded into the seesaw mechanism. The $\\mu$-$\\tau$ reflection symmetry preserved at a high energy scale $\\Lambda_\\text{FS}$ will be broken by radiative corrections and result in deviations of $\\theta_{23}$ from $45^\\circ$ and $\\delta$ from $\\pm90^\\circ$ at the electroweak scale. We develop an analytical method to derive the corrections to all the mixing parameters. We perform a numerical analysis in the MSSM for $\\delta=-90^\\circ$ at $\\Lambda_\\text{FS}$, and observe that $\\theta_{23}>45^\\circ$ in the normal mass ordering, $\\theta_{23}<45^\\circ$ in the inverted mass ordering, and the sizable correction to $\\delta$ prefers a negative sign. These deviations have definite directions and can be tested in the future neutrino oscillation experiments.

Zhou, Ye-Ling

2014-01-01T23:59:59.000Z

410

The Lie point symmetry generators admitted by systems of linear differential equations  

Science Journals Connector (OSTI)

...1008 59 112 4 The Lie point symmetry generators admitted by systems of linear differential...existence of a basis of infinitesimal generators (as determined by Lie's algorithm...symmetry|linear system|infinitesimal generator|fibre-preserving|affine bundle...

2014-01-01T23:59:59.000Z

411

Light clusters production as a probe to nuclear symmetry energy RID A-2398-2009  

E-Print Network [OSTI]

the yields and the energy spectra of these light clusters are affected significantly by the density dependence of nuclear symmetry energy, with a stiffer symmetry energy giving a larger yield....

Chen, LW; Ko, Che Ming; Li, Ba.

2003-01-01T23:59:59.000Z

412

Fractured reservoir discrete feature network technologies. Final report, March 7, 1996 to September 30, 1998  

SciTech Connect (OSTI)

This report summarizes research conducted for the Fractured Reservoir Discrete Feature Network Technologies Project. The five areas studied are development of hierarchical fracture models; fractured reservoir compartmentalization, block size, and tributary volume analysis; development and demonstration of fractured reservoir discrete feature data analysis tools; development of tools for data integration and reservoir simulation through application of discrete feature network technologies for tertiary oil production; quantitative evaluation of the economic value of this analysis approach.

Dershowitz, William S.; Einstein, Herbert H.; LaPoint, Paul R.; Eiben, Thorsten; Wadleigh, Eugene; Ivanova, Violeta

1998-12-01T23:59:59.000Z

413

Nuclear symmetry potential in the relativistic impulse approximation RID A-2398-2009 RID C-6879-2009  

E-Print Network [OSTI]

-equivalent potential, and the nuclear symmetry potential in isospin asymmetric nuclear matter. We find that the nuclear symmetry potential at fixed baryon density decreases with increasing nucleon energy. In particular, the nuclear symmetry potential at saturation...

Li, Zeng-Hua; Chen, Lie-Wen; Ko, Che Ming; Li, Bao-An; Ma, Hong-Ru.

2006-01-01T23:59:59.000Z

414

Optimizing parameters for predicting the geochemical behavior and performance of discrete fracture networks in geothermal systems  

Broader source: Energy.gov [DOE]

Optimizing parameters for predicting the geochemical behavior and performance of discrete fracture networks in geothermal systems presentation at the April 2013 peer review meeting held in Denver, Colorado.

415

Comparison of Different Approaches for the Calculation of Projective Symmetry or the Axis of a SHGC  

E-Print Network [OSTI]

Comparison of Different Approaches for the Calculation of Projective Symmetry or the Axis of a SHGC;Comparison of Different Approaches for the Calculation of Projective Symmetry or the Axis of a SHGC Sven]. And although the projections of straight homogeneous generalised cylinders (SHGC) generally exhibit no symmetry

Hamburg,.Universität

416

Comparison between effective Hamiltonians in symmetry restoring theories: Intrinsic excitations in superfluid nuclei  

Science Journals Connector (OSTI)

The comparison between effective Hamiltonians, constructed within the framework of symmetry restoring methods, is discussed for the case of intrinsic two-quasiparticle excitations in superfluid nuclei. Particularly, the meaning of currently adopted approximations, i.e., number symmetry restoring effective interactions and ideal quasiparticle representation in gauge space, is discussed in connection with an intrinsic symmetry breaking mechanism in the number variable.

O. Civitarese and M. C. Licciardo

1990-04-01T23:59:59.000Z

417

Schur-decomposition for 3D matrix equations and its application in solving radiative discrete ordinates equations discretized by Chebyshev collocation spectral method  

SciTech Connect (OSTI)

The Schur-decomposition for three-dimensional matrix equations is developed and used to directly solve the radiative discrete ordinates equations which are discretized by Chebyshev collocation spectral method. Three methods, say, the spectral methods based on 2D and 3D matrix equation solvers individually, and the standard discrete ordinates method, are presented. The numerical results show the good accuracy of spectral method based on direct solvers. The CPU time cost comparisons against the resolutions between these three methods are made using MATLAB and FORTRAN 95 computer languages separately. The results show that the CPU time cost of Chebyshev collocation spectral method with 3D Schur-decomposition solver is the least, and almost only one thirtieth to one fiftieth CPU time is needed when using the spectral method with 3D Schur-decomposition solver compared with the standard discrete ordinates method.

Li Benwen [Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education), Northeastern University, P.O. Box 314, Shenyang, Liaoning 110004 (China)], E-mail: heatli@hotmail.com; Tian Shuai; Sun Yasong; Hu, Zhang-Mao [Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education), Northeastern University, P.O. Box 314, Shenyang, Liaoning 110004 (China)

2010-02-20T23:59:59.000Z

418

Prismatic Algorithm for Discrete D.C. Programming Problems  

E-Print Network [OSTI]

In this paper, we propose the first exact algorithm for minimizing the difference of two submodular functions (D.S.), i.e., the discrete version of the D.C. programming problem. The developed algorithm is a branch-and-bound-based algorithm which responds to the structure of this problem through the relationship between submodularity and convexity. The D.S. programming problem covers a broad range of applications in machine learning because this generalizes the optimization of a wide class of set functions. We empirically investigate the performance of our algorithm, and illustrate the difference between exact and approximate solutions respectively obtained by the proposed and existing algorithms in feature selection and discriminative structure learning.

Kawahara, Yoshinobu

2011-01-01T23:59:59.000Z

419

Spectra of Discrete Schrödinger Operators with Primitive Invertible Substitution Potentials  

E-Print Network [OSTI]

We study the spectral properties of discrete Schr\\"odinger operators with potentials given by primitive invertible substitution sequences (or by Sturmian sequences whose rotation angle has an eventually periodic continued fraction expansion, a strictly larger class than primitive invertible substitution sequences). It is known that operators from this family have spectra which are Cantor sets of zero Lebesgue measure. We show that the Hausdorff dimension of this set tends to $1$ as coupling constant $\\lambda$ tends to $0$. Moreover, we also show that at small coupling constant, all gaps allowed by the gap labeling theorem are open and furthermore open linearly with respect to $\\lambda$. Additionally, we show that, in the small coupling regime, the density of states measure for an operator in this family is exact dimensional. The dimension of the density of states measure is strictly smaller than the Hausdorff dimension of the spectrum and tends to $1$ as $\\lambda$ tends to $0$.

May Mei

2014-07-02T23:59:59.000Z

420

Supratransmission induced by waves collisions in a discrete electrical lattice  

Science Journals Connector (OSTI)

We numerically performed a way to produce a supratransmission phenomenon in the Salerno equation describing the dynamics of modulated waves in a discrete nonlinear transmission lattice. For the natural supratransmission phenomenon, there exists a threshold of amplitude for which energy can flow in the line. We show that gap transmission is possible with driven amplitude below the threshold due to the collision of different plane waves coming from both edges of the line. One of the two plane waves has a frequency in the forbidden gap, and another has a frequency in the allowed phonon band. During collision, the wave in the allowed band is considered as a perturbation of the ones in the forbidden gap.

A. B. Togueu Motcheyo; C. Tchawoua; J. D. Tchinang Tchameu

2013-10-02T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


421

Second Law of Thermodynamics with Discrete Quantum Feedback Control  

Science Journals Connector (OSTI)

A new thermodynamic inequality is derived which leads to the maximum work that can be extracted from multi-heat-baths with the assistance of discrete quantum feedback control. The maximum work is determined by the free-energy difference and a generalized mutual information content between the thermodynamic system and the feedback controller. This maximum work can exceed that in conventional thermodynamics and, in the case of a heat cycle with two heat baths, the heat efficiency can be greater than that of the Carnot cycle. The consistency of our results with the second law of thermodynamics is ensured by the fact that work is needed for information processing of the feedback controller.

Takahiro Sagawa and Masahito Ueda

2008-02-26T23:59:59.000Z

422

Quantal Heating of Conducting Electrons with Discrete Spectrum  

SciTech Connect (OSTI)

Usually heating of conducting electrons by dc electric field results in an increase of electron temperature. In this paper we show that the dc heating of 2D electrons, placed in quantized magnetic fields, results in a peculiar electron distribution, which has the same broadening or an effective 'temperature' as the unbiased electron system. The quantal heating, however, violates strongly the Ohm's Law. In the conducting system with discrete electron spectrum the quantal heating results in spectacular decrease of electron resistance and transition of the electrons into a state with zero differential resistance (ZDR). Finally the heating leads to apparent dc driven metal-insulator transition, which correlates with the transition into the ZDR state. The correlation is very unexpected and is not understood.

Vitkalov, S. A. [Department of Physics, The City College of New York, New York, NY 10031 (United States); Bykov, A. A. [Institute of Semiconductor Physics, 630090 Novosibirsk (Russian Federation)

2011-12-23T23:59:59.000Z

423

Yoichiro Nambu and the Mechanism of Spontaneous Broken Symmetries in  

Office of Scientific and Technical Information (OSTI)

Yoichiro Nambu and the Mechanism of Yoichiro Nambu and the Mechanism of Spontaneous Broken Symmetries in Subatomic Physics Resources with Additional Information · Awards Yoichiro Nambu Credit: University of Chicago Yoichiro Nambu was awarded the 2008 Nobel Prize in Physics "for the discovery of the mechanism of spontaneous broken symmetry in subatomic physics". Nambu 'has revolutionized modern scientific ideas about the nature of the most fundamental particles and the space through which they move. His theories form an essential cornerstone of what physicists call the Standard Model, which explains in a unified way three of the four fundamental forces of nature: strong, weak and electromagnetic. He also has significantly influenced the development of quantum chromodynamics, a theory that describes certain interactions between quarks and between protons and neutrons.' 1

424

Revisiting Noether gauge symmetry approach in quintom cosmology  

E-Print Network [OSTI]

The Noether gauge symmetry approach is revisited to study various quintom scenarios (those that arise by the presence of two dynamical scalar fields) to comprehend the role of dark energy in our universe. For such models, we obtain smooth parameterizations of the equation of state of dark energy across the boundary of cosmological constant $w_{\\Lambda}=-1$. This study gives rise to two new cases of the potential $V(\\phi, \\sigma)$, due to a quintom field in which nonlinear coupling of the scalar fields arise. Besides we report that a few cases of Noether gauge symmetries and their invariants in [Adnan Aslam, et. al., Astrophys Space Sci (2013), 348:533-540] are incorrect. Consequently, the given cosmological model in their paper is not a feasible quintom model.

Ali, Sajid

2015-01-01T23:59:59.000Z

425

Exponentially Fragile PT Symmetry in Lattices with Localized Eigenmodes  

SciTech Connect (OSTI)

We study the effect of localized modes in lattices of size N with parity-time (PT) symmetry. Such modes are arranged in pairs of quasidegenerate levels with splitting deltaapproxexp{sup -N/x}i where xi is their localization length. The level 'evolution' with respect to the PT breaking parameter gamma shows a cascade of bifurcations during which a pair of real levels becomes complex. The spontaneous PT symmetry breaking occurs at gamma{sub PT}approxmin(delta), thus resulting in an exponentially narrow exact PT phase. As N/xi decreases, it becomes more robust with gamma{sub PT}approx1/N{sup 2} and the distribution P(gamma{sub PT}) changes from log-normal to semi-Gaussian. Our theory can be tested in the frame of optical lattices.

Bendix, Oliver; Fleischmann, Ragnar [MPI for Dynamics and Self-Organization, Bunsenstrasse 10, Goettingen (Germany); Kottos, Tsampikos [Wesleyan University, Middletown, Connecticut, 06459 (United States); Shapiro, Boris [Technion - Israel Institute of Technology, Technion City, Haifa 32000 (Israel)

2009-07-17T23:59:59.000Z

426

Lorentz symmetry breaking as a quantum field theory regulator  

Science Journals Connector (OSTI)

Perturbative expansions of quantum field theories typically lead to ultraviolet (short-distance) divergences requiring regularization and renormalization. Many different regularization techniques have been developed over the years, but most regularizations require severe mutilation of the logical foundations of the theory. In contrast, breaking Lorentz invariance, while it is certainly a radical step, at least does not damage the logical foundations of the theory. I shall explore the features of a Lorentz symmetry breaking regulator in a simple polynomial scalar field theory and discuss its implications. In particular, I shall quantify just “how much” Lorentz symmetry breaking is required to fully regulate the quantum theory and render it finite. This scalar field theory provides a simple way of understanding many of the key features of Ho?ava’s recent article [Phys. Rev. D 79, 084008 (2009)] on 3+1 dimensional quantum gravity.

Matt Visser

2009-07-23T23:59:59.000Z

427

3D turtle geometry: artwork, theory, program equivalence and symmetry  

Science Journals Connector (OSTI)

We define a 3D variant of turtle graphics and present the theoretical foundations of 3D turtle geometry. This theory enables one to reason about open and closed 3D polygonal paths by means of algebraic calculations. In particular, we introduce several equivalence relations on turtle programs and theorems that define corresponding standard forms. Also we express the relationship between the symmetries of a 3D polygonal path and the symmetries of a generating turtle program in a suitable standard form. Finally, we discuss software tool support for 3D turtle geometry. Along the way, we present some artworks designed through 3D turtle graphics. These artworks have never been described in the literature before.

Tom Verhoeff

2010-01-01T23:59:59.000Z

428

Charmless $B \\to VP$ Decays Using Flavor SU(3) Symmetry  

E-Print Network [OSTI]

The decays of $B$ mesons to a charmless vector ($V$) and pseudoscalar ($P$) meson are analyzed within a framework of flavor SU(3) in which symmetry breaking is taken into account through ratios of decay constants in tree ($T$) amplitudes. The magnitudes and relative phases of tree and penguin amplitudes are extracted from data; the symmetry assumption is tested; and predictions are made for rates and CP asymmetries in as-yet-unseen decay modes. A key assumption for which we perform some tests and suggest others is a relation between penguin amplitudes in which the spectator quark is incorporated into either a pseudoscalar meson or a vector meson. Values of $\\gamma$ in the upper half of the range currently allowed by fits to other data are favored.

Chiang, C W; Luo, Z; Rosner, J L; Suprun, D A; Chiang, Cheng-Wei; Gronau, Michael; Luo, Zumin; Rosner, Jonathan L.; Suprun, Denis A.

2004-01-01T23:59:59.000Z

429

Charmless $B \\to VP$ Decays Using Flavor SU(3) Symmetry  

E-Print Network [OSTI]

The decays of $B$ mesons to a charmless vector ($V$) and pseudoscalar ($P$) meson are analyzed within a framework of flavor SU(3) in which symmetry breaking is taken into account through ratios of decay constants in tree ($T$) amplitudes. The magnitudes and relative phases of tree and penguin amplitudes are extracted from data; the symmetry assumption is tested; and predictions are made for rates and CP asymmetries in as-yet-unseen decay modes. A key assumption for which we perform some tests and suggest others is a relation between penguin amplitudes in which the spectator quark is incorporated into either a pseudoscalar meson or a vector meson. Values of $\\gamma$ slightly restricting the range currently allowed by fits to other data are favored, but outside this range there remain acceptable solutions which cannot be excluded solely on the basis of present $B \\to VP$ experiments.

Cheng-Wei Chiang; Michael Gronau; Zumin Luo; Jonathan L. Rosner; Denis A. Suprun

2003-09-12T23:59:59.000Z

430

Symmetry Properties of Single-Walled BC2N Nanotubes  

SciTech Connect (OSTI)

The symmetry properties of the single-walled BC2N nanotubes were investigated. All the BC2N nanotubes possess nonsymmorphic line groups. In contrast with the carbon and boron nitride nanotubes, armchair and zigzag BC2N nanotubes belong to different line groups, depending on the index n (even or odd) and the vector chosen. The number of Raman- active phonon modes is almost twice that of the infrared-active phonon modes for all kinds of BC2N nanotubes.

Pan, Hui [ORNL; Feng, Yuan Ping [National University of Singapore; Lin, Jainyi [Institute of Chemical and Engineering, Singapore

2009-06-01T23:59:59.000Z

431

CONSTRAINING THE SYMMETRY PARAMETERS OF THE NUCLEAR INTERACTION  

SciTech Connect (OSTI)

One of the major uncertainties in the dense matter equation of state has been the nuclear symmetry energy. The density dependence of the symmetry energy is important in nuclear astrophysics, as it controls the neutronization of matter in core-collapse supernovae, the radii of neutron stars and the thicknesses of their crusts, the rate of cooling of neutron stars, and the properties of nuclei involved in r-process nucleosynthesis. We show that fits of nuclear masses to experimental masses, combined with other experimental information from neutron skins, heavy ion collisions, giant dipole resonances, and dipole polarizabilities, lead to stringent constraints on parameters that describe the symmetry energy near the nuclear saturation density. These constraints are remarkably consistent with inferences from theoretical calculations of pure neutron matter, and, furthermore, with astrophysical observations of neutron stars. The concordance of experimental, theoretical, and observational analyses suggests that the symmetry parameters S{sub v} and L are in the range 29.0-32.7 MeV and 40.5-61.9 MeV, respectively, and that the neutron star radius, for a 1.4 M{sub Sun} star, is in the narrow window 10.7 km

Lattimer, James M. [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794-3800 (United States); Lim, Yeunhwan, E-mail: james.lattimer@stonybrook.edu, E-mail: yeunhwan.lim@gmail.com [Department of Physics Education, Daegu University, Gyeongsan 712-714 (Korea, Republic of)

2013-07-01T23:59:59.000Z

432

Search for gauge symmetry generators of singular Lagrangian theory  

E-Print Network [OSTI]

We propose a procedure which allows one to construct local symmetry generators of general quadratic Lagrangian theory. Manifest recurrence relations for generators in terms of so-called structure matrices of the Dirac formalism are obtained. The procedure fulfilled in terms of initial variables of the theory, and do not implies either separation of constraints on first and second class subsets or any other choice of basis for constraints.

A. A. Deriglazov

2005-09-29T23:59:59.000Z

433

Invisibility and PT Symmetry: A Simple Geometrical Viewpoint  

E-Print Network [OSTI]

We give a simplified account of the properties of the transfer matrix for a complex one-dimensional potential, paying special attention to the particular instance of unidirectional invisibility. In appropriate variables, invisible potentials appear as performing null rotations, which lead to the helicity-gauge symmetry of massless particles. In hyperbolic geometry, this can be interpreted, via M\\"{o}bius transformations, as parallel displacements, a geometric action that has no Euclidean analogy.

Luis L. Sanchez-Soto; Juan J. Monzon

2014-05-19T23:59:59.000Z

434

Symmetry energy of deformed neutron-rich nuclei  

E-Print Network [OSTI]

The symmetry energy, the neutron pressure and the asymmetric compressibility of deformed neutron-rich even-even nuclei are calculated on the examples of Kr and Sm isotopes within the coherent density fluctuation model using the symmetry energy as a function of density within the Brueckner energy-density functional. The correlation between the thickness of the neutron skin and the characteristics related with the density dependence of the nuclear symmetry energy is investigated for isotopic chains of these nuclei in the framework of the self-consistent Skyrme-Hartree-Fock plus BCS method. Results for an extended chain of Pb isotopes are also presented. A remarkable difference is found in the trend followed by the different isotopic chains: the studied correlations reveal a smoother behavior in the Pb case than in the other cases. We also notice that the neutron skin thickness obtained for $^{208}$Pb with SLy4 force is found to be in a good agreement with recent data.

Gaidarov, M K; Sarriguren, P; de Guerra, E Moya

2012-01-01T23:59:59.000Z

435

Charges and Generators of Symmetry Transformations in Quantum Field Theory  

Science Journals Connector (OSTI)

Within the Wightman approach to quantum field theory, we review and clarify the properties of formal charges, defined as space integrals for the fourth component of a local current. The conditions for a formal charge to determine an operator (generator) are discussed, in connection with the well-known theorems of Goldstone and of Coleman. The symmetry transformations generated by this operator—given its existence—are also studied in some detail. For generators in a scattering theory, we prove their additivity and thus provide a simple way to characterize them from their matrix elements between one-particle states. This characterization allows an immediate construction of the unitary operators implementing the symmetry transformations, and implies that all internal symmetry groups are necessarily compact. We also indicate how to construct interacting fields having definite internal quantum numbers. The present status of the proof of Noether's theorem and of its converse is discussed in the light of the rather delicate properties of formal charges.

CLAUDIO A. ORZALESI

1970-10-01T23:59:59.000Z

436

Integrating discretization and association rule-based classification for Alzheimer's disease diagnosis  

Science Journals Connector (OSTI)

This paper shows a computer aided diagnosis (CAD) combining continuous attribute discretization and association rule mining for the early diagnosis of Alzheimer's disease (AD) based on emission computed tomography images. A mask is obtained from the ... Keywords: Alzheimer's disease, Association rules, Computed aided diagnosis, Discretization, Image histogram

R. Chaves; J. RamíRez; J. M. GóRriz

2013-04-01T23:59:59.000Z

437

From max-plus algebra to nonexpansive mappings: a nonlinear theory for discrete event systems  

Science Journals Connector (OSTI)

Discrete event systems provide a useful abstraction for modelling a wide variety of systems: digital circuits, communication networks, manufacturing plants, etc. Their dynamics--stability, equilibrium states, cyclical behaviour, asymptotic average delays--are ... Keywords: cycle time, discrete event system, fixed point, max-plus semiring, nonexpansive map, nonlinear eigenvalue, nonnegative matrix, topical function

Jeremy Gunawardena

2003-02-01T23:59:59.000Z

438

Resonant plasmon scattering by discrete breathers in Josephson junction ladders A. E. Miroshnichenko,1  

E-Print Network [OSTI]

Resonant plasmon scattering by discrete breathers in Josephson junction ladders A. E scattering by discrete breathers in Josephson junction ladders. DOI: 10.1103/PhysRevB.71.174306 PACS number Josephson junction systems,2 coupled nonlinear optical waveguides,3 lattice vi- brations in crystals,4

Flach, Sergej

439

Resonant plasmon scattering by discrete breathers in Josephson junction ladders A. E. Miroshnichenko,1  

E-Print Network [OSTI]

Resonant plasmon scattering by discrete breathers in Josephson junction ladders A. E in Josephson junction ladders. We predict the existence of Fano resonances, and find them by computing in the plasmon scattering by discrete breathers in Josephson junction ladders. DOI: 10.1103/PhysRevB.71

440

Rank Tests for the Observability of Discrete-Time Jump Linear Systems with Inputs  

E-Print Network [OSTI]

Rank Tests for the Observability of Discrete-Time Jump Linear Systems with Inputs Ehsan Elhamifar of rank tests on the parameters of the JLS when the discrete state sequence is arbitrary. Our key verify observ- ability by checking a number of rank tests that is only quadratic in the number

Note: This page contains sample records for the topic "discrete space-time symmetries" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


441

A New Approach to Fuzzy Modeling and Control of Discrete-Time Systems  

E-Print Network [OSTI]

], the advantage of fuzzy logic in modeling and control is in the ability to combine modeling (constructingA New Approach to Fuzzy Modeling and Control of Discrete-Time Systems Michael Margaliot and Gideon Langholz #3; Abstract We present a new approach to fuzzy modeling and control of discrete-time sys- tems

Margaliot, Michael

442

Some unusual discrete VLF emissions observed at a low-latitude ground station at Agra  

E-Print Network [OSTI]

Some unusual discrete VLF emissions observed at a low-latitude ground station at Agra B. Singh February 1997 / Accepted: 17 February 1997 Abstract. A detailed analysis of the VLF emissions data obtained°1¢ N, L = 1.15) has yielded some unusual discrete VLF emissions of the rising type. These include (1

Paris-Sud XI, Université de

443

Discrete Barium Strontium Titanate (BST) Thin-Film Interdigital Varactors on Alumina: Design, Fabrication, Characterization, and  

E-Print Network [OSTI]

Discrete Barium Strontium Titanate (BST) Thin-Film Interdigital Varactors on Alumina: Design, Raleigh, NC-27695-7914, USA. Email:jayeshnath@ieee.org Abstract -- Discrete Barium Strontium Titanate (BST, capacitors, BST, ferroelectric, thin-film, barium strontium titanate, bandpass filter, IP3, ACPR, temperature

444

Area and Throughput Trade-Offs in the Design of Pipelined Discrete Wavelet Transform Architectures  

E-Print Network [OSTI]

Area and Throughput Trade-Offs in the Design of Pipelined Discrete Wavelet Transform Architectures wavelet transform (DWT) as a linear space-to-frequency transform of the image domain in an irreversible compression. This irreversible discrete wavelet transform is implemented by FIR filter using 9/7 Daubechies

Boyer, Edmond

445

PARALLEL COMPUTATIONS OF RADIATIVE HEAT TRANSFER USING THE DISCRETE ORDINATES METHOD  

E-Print Network [OSTI]

the radiative transport equation on parallel computers. Mathematical libraries developed by third parties the discrete ordi- nates method. They observed that the global nature of radiative transport resultedPARALLEL COMPUTATIONS OF RADIATIVE HEAT TRANSFER USING THE DISCRETE ORDINATES METHOD Gautham

Utah, University of

446

Stability of discrete memory states to stochastic fluctuations in neuronal systems  

E-Print Network [OSTI]

endowed with feedback loops, for short-term memory. Fluctuations are due to highly irregular spike firing on an autophosphorylation mechanism of calcium/calmodulin-dependent protein kinase II CaMKII molecules. There, fluctuations in calcium concentration can lead to discrete changes in the number of ions bound to a protein5 and discrete

Wang, Xiao-Jing

447

Rectangular discrete radon transform for buildings extraction from high resolution satellite images  

Science Journals Connector (OSTI)

This paper presents a new approach titled Rectangular Discrete Radon Transform (RDRT) which is based on the generalization of the classical Radon transform to project the images with rectangular objects instead of straight lines. The RDRT was conceived ... Keywords: high resolution satellite image, rectangular buildings, rectangular discrete radon transform

Elouedi Ines; Hamouda Atef; Rojbani Hmida

2012-06-01T23:59:59.000Z

448

ORIGINAL PAPER A new discrete electromagnetism-based meta-heuristic  

E-Print Network [OSTI]

ORIGINAL PAPER A new discrete electromagnetism-based meta-heuristic for solving Electromagnetism-like Mechanism (SEM) is one of the swarm-based optimization methods which is examined Electromagnetism-like Mechanism is proposed which utilizes Genetic Algorithm (GA) operators to work in discrete

Li, Xiaodong

449

A Discrete Event Simulation Model for "Efficient Selection of Relay Vehicles for  

E-Print Network [OSTI]

1 A Discrete Event Simulation Model for "Efficient Selection of Relay Vehicles for Broadcasting discrete event-driven simulation model for DIB and EDIB protocols on VANET. We define six types of events the ACK message to the sender. The following variables are used in the simulation model: · vehs stores

Lin, Jason Yi-Bing

450

A Mixed Finite-Element Discretization of the Energy-Transport Model for Semiconductors  

E-Print Network [OSTI]

A Mixed Finite-Element Discretization of the Energy-Transport Model for Semiconductors Stefan Holst #12;tting mixed #12;nite-element method is used to discretize the stationary energy. Energy-transport models describe the ow of electrons through a semi- conductor device, in uenced by di

Pietra, Paola

451

Nonlinear Schrodinger equations and their spectral semi-discretizations over long times  

E-Print Network [OSTI]

of a convolution potential avoids resonances among the frequencies (eigen- values) of the linearized systemNonlinear Schr¨odinger equations and their spectral semi-discretizations over long times Ludwig¨odinger equations with small initial data (or small nonlinearity) and their spec- tral semi-discretizations in space

Tübingen, Universität

452

Effect of interactions on two-dimensional fermionic symmetry-protected topological phases with Z2 symmetry  

Science Journals Connector (OSTI)

We study the effect of interactions on two-dimensional fermionic symmetry-protected topological (SPT) phases using the recently proposed braiding statistics approach. We focus on a simple class of examples: superconductors with a Z2 Ising symmetry. Although these systems are classified by Z in the noninteracting limit, our results suggest that the classification collapses to Z8 in the presence of interactions—consistent with previous work that analyzed the stability of the edge. Specifically, we show that there are at least eight different types of Ising superconductors that cannot be adiabatically connected to one another, even in the presence of strong interactions. In addition, we prove that each of the seven nontrivial superconductors have protected edge modes.

Zheng-Cheng Gu and Michael Levin

2014-05-19T23:59:59.000Z

453

Symmetry breaking Hopf bifurcations in equations with O(2) symmetry with application to the Kuramoto-Sivashinsky equation  

SciTech Connect (OSTI)

In problems with O(2) symmetry, the Jacobian matrix at nontrivial steady state solutions with D{sub n} symmetry always has a zero eigenvalue due to the group orbit of solutions. We consider bifurcations which occur when complex eigenvalues also cross the imaginary axis and develop a numerical method which involves the addition of a new variable, namely the velocity of solutions drifting around the group orbit, and another equation, which has the form of a phase condition for isolating one solution on the group orbit. The bifurcating branch has a particular type of spatio-temporal symmetry which can be broken in a further bifurcation which gives rise to modulated travelling wave solutions which drift around the group orbit. Multiple Hopf bifurcations are also considered. The methods derived are applied to the Kuramoto-Sivashinsky equation and we give results at two different bifurcations, one of which is a multiple Hopf bifurcation. Our results give insight into the numerical results of Hyman, Nicolaenko, and Zaleski. 30 refs., 2 figs., 2 tabs.

Amdjadi, F. [Univ. of Surrey, Guildford (United Kingdom)] [Univ. of Surrey, Guildford (United Kingdom); [Zanjan Univ. (Iran, Islamic Republic of); Aston, P.J. [Univ. of Surrey, Guildford (United Kingdom)] [Univ. of Surrey, Guildford (United Kingdom); Plechac, P. [Heriot-Watt Univ., Edinburgh (United Kingdom)] [Heriot-Watt Univ., Edinburgh (United Kingdom)

1997-02-01T23:59:59.000Z

454

Delay-dependent robust $$H_\\infty $$ control for 2-D discrete nonlinear systems with state delays  

Science Journals Connector (OSTI)

This paper investigates the problem of robust $$H_\\infty $$ control for a class of 2-D (two-dimensional) discrete state delayed systems with sector nonlinearity ... Keywords: $$H_\\infty $$ performance, 2D discrete systems, Exponential stability, State delays

Shipei Huang; Zhengrong Xiang

2014-10-01T23:59:59.000Z

455

Discrete Event Modeling of Algae Cultivation and Harvesting at Commercial Scale: Capital Costs, Operating Costs, and System Bottlenecks  

SciTech Connect (OSTI)

Discrete Event Modeling of Algae Cultivation and Harvesting at Commercial Scale: Capital Costs, Operating Costs, and System Bottlenecks

Lacey, Ph.D, P.E., Ronald E. [Texas A& M University

2012-07-16T23:59:59.000Z

456

Flavor S_4 times Z_2 symmetry and neutrino mixing  

E-Print Network [OSTI]

We present a model of the lepton masses and flavor mixing based on the discrete group $S_4 \\times Z_2$. In this model, all the charged leptons and neutrinos are assigned to the $3_\\alpha$ representation of $S_4$ in the Yamanouchi bases. The charged lepton and neutrino masses are mainly determined by the vacuum expectation value structures of the Higgs fields. A nearly tri-bimaximal lepton flavor mixing pattern, which is in agreement with the current experimental results, can be accommodated in our model. The neutrino mass spectrum takes the nearly degenerate pattern, and thus can be well tested in the future precise experiments.

He Zhang

2006-12-18T23:59:59.000Z

457

Space group symmetry fractionalization in a family of exactly solvable models with Z2 topological order  

E-Print Network [OSTI]

We study square lattice space group symmetry fractionalization in a family of exactly solvable models with $\\mathbb{Z}_2$ topological order in two dimensions. In particular, we have obtained a complete understanding of which distinct types of symmetry fractionalization (symmetry classes) can be realized within this class of models, which are generalizations of Kitaev's $\\mathbb{Z}_2$ toric code to arbitrary lattices. This question is motivated by earlier work of A. M. Essin and one of us (M. H.), where the idea of symmetry classification was laid out, and which, for square lattice symmetry, produces 2080 symmetry classes consistent with the fusion rules of $\\mathbb{Z}_2$ topological order. This approach does not produce a physical model for each symmetry class, and indeed there are reasons to believe that some symmetry classes may not be realizable in strictly two-dimensional systems, thus raising the question of which classes are in fact possible. While our understanding is limited to a restricted class of models, it is complete in the sense that for each of the 2080 possible symmetry classes, we either prove rigorously that the class cannot be realized in our family of models, or we give an explicit model realizing the class. We thus find that exactly 487 symmetry classes are realized in the family of models considered. With a more restrictive type of symmetry action, where space group operations act trivially in the internal Hilbert space of each spin degree of freedom, we find that exactly 82 symmetry classes are realized. In addition, we present a single model that realizes all $2^6 = 64$ types of symmetry fractionalization allowed for a single anyon species ($\\mathbb{Z}_2$ charge excitation), as the parameters in the Hamiltonian are varied. The paper concludes with a summary and a discussion of two results pertaining to more general bosonic models.

Hao Song; Michael Hermele

2014-09-04T23:59:59.000Z

458

A Michelson-Morley Test of Lorentz Symmetry for Electrons  

E-Print Network [OSTI]

All evidence so far suggests that the absolute spatial orientation of an experiment never affects its outcome. This is reflected in the Standard Model of physics by requiring all particles and fields to be invariant under Lorentz transformations. The most well-known test of this important cornerstone of physics are Michelson-Morley-type experiments\\cite{MM, Herrmann2009,Eisele2009} verifying the isotropy of the speed of light. Lorentz symmetry also implies that the kinetic energy of an electron should be independent of the direction of its velocity, \\textit{i.e.,} its dispersion relation should be isotropic in space. In this work, we search for violation of Lorentz symmetry for electrons by performing an electronic analogue of a Michelson-Morley experiment. We split an electron-wavepacket bound inside a calcium ion into two parts with different orientations and recombine them after a time evolution of 95ms. As the Earth rotates, the absolute spatial orientation of the wavepackets changes and anisotropies in the electron dispersion would modify the phase of the interference signal. To remove noise, we prepare a pair of ions in a decoherence-free subspace, thereby rejecting magnetic field fluctuations common to both ions\\cite{Roos2006}. After a 23 hour measurement, we limit the energy variations to $h\\times 11$ mHz ($h$ is Planck's constant), verifying that Lorentz symmetry is preserved at the level of $1\\times10^{-18}$. We improve on the Lorentz-violation limits for the electron by two orders of magnitude\\cite{Hohensee2013c}. We can also interpret our result as testing the rotational invariance of the Coloumb potential, improving limits on rotational anisotropies in the speed of light by a factor of five\\cite{Herrmann2009,Eisele2009}. Our experiment demonstrates the potential of quantum information techniques in the search for physics beyond the Standard Model.

T. Pruttivarasin; M. Ramm; S. G. Porsev; I. I. Tupitsyn; M. Safronova; M. A. Hohensee; H. Haeffner

2014-12-06T23:59:59.000Z

459

A Discrete Evolutionary Model for Chess Players' Ratings  

E-Print Network [OSTI]

The Elo system for rating chess players, also used in other games and sports, was adopted by the World Chess Federation over four decades ago. Although not without controversy, it is accepted as generally reliable and provides a method for assessing players' strengths and ranking them in official tournaments. It is generally accepted that the distribution of players' rating data is approximately normal but, to date, no stochastic model of how the distribution might have arisen has been proposed. We propose such an evolutionary stochastic model, which models the arrival of players into the rating pool, the games they play against each other, and how the results of these games affect their ratings. Using a continuous approximation to the discrete model, we derive the distribution for players' ratings at time $t$ as a normal distribution, where the variance increases in time as a logarithmic function of $t$. We validate the model using published rating data from 2007 to 2010, showing that the parameters obtained...

Fenner, Trevor; Loizou, George

2011-01-01T23:59:59.000Z

460

Laboratory tests of Lorentz and CPT symmetry with muons  

Science Journals Connector (OSTI)

The prospects are explored for testing Lorentz and CPT symmetry in the muon sector via the spectroscopy of muonium and various muonic atoms, and via measurements of the anomalous magnetic moments of the muon and antimuon. The effects of Lorentz-violating operators of both renormalizable and nonrenormalizable dimensions are included. We derive observable signals, extract first constraints from existing data on a variety of coefficients for Lorentz and CPT violation, and estimate sensitivities attainable in forthcoming experiments. The potential of Lorentz violation to resolve the proton radius puzzle and the muon anomaly discrepancy is discussed.

André H. Gomes; V. Alan Kostelecký; Arnaldo J. Vargas

2014-10-21T23:59:59.000Z

Note: This page contains sample records for the topic "discrete space-time symmetries" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


461

Spontaneous symmetry breaking and optimization of functional renormalization group  

E-Print Network [OSTI]

The requirement for the absence of spontaneous symmetry breaking in the d=1 dimension has been used to optimize the regulator dependence of functional renormalization group equations in the framework of the sine-Gordon scalar field theory. Results obtained by the optimization of this kind were compared to those of the Litim-Pawlowski and the principle of minimal sensitivity optimization scenarios. The optimal parameters of the compactly supported smooth (CSS) regulator, which recovers all major types of regulators in appropriate limits, have been determined beyond the local potential approximation, and the Litim limit of the CSS was found to be the optimal choice.

I. Nandori; I. G. Marian; V. Bacso

2014-02-27T23:59:59.000Z

462

Charge and CP symmetry breaking in two Higgs doublet models  

E-Print Network [OSTI]

We show that, for the most generic model with two Higgs doublets possessing a minimum that preserves the $U(1)_{em}$ symmetry, charge breaking (CB) cannot occur. If CB does not occur, the potential could have two different minima, and there is in principle no general argument to show which one is the deepest. The depth of the potential at a stationary point that breaks CB or CP, relative to the $U(1)_{em}$ preserving minimum, is proportional to the squared mass of the charged or pseudoscalar Higgs, respectively.

A. Barroso; P. M. Ferreira; R. Santos

2005-11-07T23:59:59.000Z

463

3d mirror symmetry as a canonical transformation  

E-Print Network [OSTI]

We generalize the free Fermi-gas formulation of certain 3d ${\\cal N}=3$ supersymmetric Chern-Simons-matter theories by allowing Fayet-Iliopoulos couplings as well as mass terms for bifundamental matter fields. The resulting partition functions are given by simple modifications of the argument of the Airy function found previously. With these extra parameters it is easy to see that mirror-symmetry corresponds to linear canonical transformations on the phase space (or operator algebra) of the 1-dimensional fermions.

Drukker, Nadav

2015-01-01T23:59:59.000Z

464

Conifold singularities, resumming instantons and non-perturbative mirror symmetry  

E-Print Network [OSTI]

We determine the instanton corrected hypermultiplet moduli space in type IIB compactifications near a Calabi-Yau conifold point where the size of a two-cycle shrinks to zero. We show that D1-instantons resolve the conifold singularity caused by worldsheet instantons. Furthermore, by resumming the instanton series, we reproduce exactly the results obtained by Ooguri and Vafa on the type IIA side, where membrane instantons correct the hypermultiplet moduli space. Our calculations therefore establish that mirror symmetry holds non-perturbatively in the string coupling.

Frank Saueressig; Stefan Vandoren

2007-04-26T23:59:59.000Z

465

Combination rules, charge symmetry, and Hall effect in cuprates  

Science Journals Connector (OSTI)

The rule relating the observed Hall coefficient to the spin and charge responses of the uniform doped Mott insulator is derived. It is essential to include the contribution of holon and spinon three-current correlations to the effective action of the gauge field. In the vicinity of the Mott insulating point the Hall coefficient is holon dominated and weakly temperature dependent. In the vicinity of a point of charge conjugation symmetry, the holon contribution to the observed Hall coefficient is small: the Hall coefficient follows the temperature dependence of the diamagnetic susceptibility with a sign determined by the Fermi-surface shape.

A. J. Schofield and J. M. Wheatley

1993-05-01T23:59:59.000Z

466

Short note: A simplified technique for the efficient and highly accurate discretization of boundary integral equations in 2D on domains with corners  

Science Journals Connector (OSTI)

Keywords: Acoustic scattering, Boundary integral equation, Corner singularity, Direct solver, Grid refinement, High-order discretization, Nyström discretization, Quadrature, Weakly singular integral equation

A. Gillman; S. Hao; P. G. Martinsson

2014-01-01T23:59:59.000Z

467

Turbulent heat transfer and friction in a square channel with discrete rib turbulators  

E-Print Network [OSTI]

in which two opposite walls are roughened with parallel and crossed arrays of full ribs, cross-cut discrete ribs, and beveled discrete ribs. The discrete ribs are staggered in alternate rows of three and two ribs The rib-roughened channel models... and length on the convective heat transfer in nb-roughened triangular ducts. Ribs were placed on two of the three walls of the test ducts to model the internal cooling passage at the leading edge of a. turbine airfoil. The local heat transfer augmentation...

McMillin, Robert Dale

2012-06-07T23:59:59.000Z

468

On a class of second-order PDEs admitting partner symmetries  

E-Print Network [OSTI]

Recently we have demonstrated how to use partner symmetries for obtaining noninvariant solutions of heavenly equations of Plebanski that govern heavenly gravitational metrics. In this paper, we present a class of scalar second-order PDEs with four variables, that possess partner symmetries and contain only second derivatives of the unknown. We present recursion relations for symmetries for these PDEs. We also present a complete set of simplest canonical forms to which the general PDE with partner symmetries can be transformed by point and Legendre transformations, together with recursions for symmetries of these canonical equations. These canonical forms contain the first and second equations of Plebanski and also new equations which we call mixed heavenly equation and asymmetric heavenly equation. On the example of the mixed heavenly equation, we show how to use partner symmetries for obtaining noninvariant solutions of PDEs by a lift from invariant solutions.

Sheftel, M B

2009-01-01T23:59:59.000Z

469

Geostatistical Space-Time Models, Stationarity, Separability, and Full  

E-Print Network [OSTI]

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162 4.4 Irish wind data, 1997) and the assessment of wind energy resources (Haslett and Raftery, 1989). Geostatistical- centrations, precipitation fields and surface winds are characterized by spatial and temporal variability

Genton, Marc G.

470

Multiple symbol decoding of differential space-time codes  

E-Print Network [OSTI]

2 A 4 ( 1 p2 e|2 kM ; k = 0;1; ;M 1 ) : a2i+1 = a2i: (2.1) De ne the following matrices: A0 4 2 66 4 a0 a1 a 1 a 0 3 77 5 ; Ai 4 2 66 4 a2i a2i+1 a 2i+1 a 2i 3 77 5 ; for i 1; (2.2) Gi 4 AiAH0 : (2.3) 5 It is easy to see that Ai and Gi... are both orthogonal matrices, i.e., AiAHi = AHi Ai = GiGHi = GHi Gi = I2. Hence, given Gi, Ai can be obtained by Ai = GiA0: (2.4) Also, Gi is always an element of a nite set G. Gi 2 G 4 8> >>: 2 66 4 g 0 0 g 3 77 5 ; 2 66 4 0 g g 0 3 77 5 9...

Singhal, Rohit

2004-09-30T23:59:59.000Z

471

Surface tension with Normal Curvature in Curved Space-Time  

E-Print Network [OSTI]

With an aim to include the contribution of surface tension in the action of the boundary, we define the tangential pressure in terms of surface tension and Normal curvature in a more naturally geometric way. First, we show that the negative tangential pressure is independent of the four-velocity of a very thin hyper-surface. Second, we relate the 3-pressure of a surface layer to the normal curvature and the surface tension. Third, we relate the surface tension to the energy of the surface layer. Four, we show that the delta like energy flows across the hyper-surface will be zero for such a representation of intrinsic 3-pressure. Five, for the weak field approximation and for static spherically symmetric configuration, we deduce the classical Kelvin's relation. Six, we write a modified action for the boundary having contributions both from surface tension and normal curvature of the surface layer. Also we propose a method to find the physical action assuming a reference background, where the background is not flat.

Himanshu kumar; Sharf Alam; Suhail Ahmad

2012-11-01T23:59:59.000Z

472

Space-Time Prediction of Ocean Winds Anders Malmberg  

E-Print Network [OSTI]

to Monthly Weather Review. C Malmberg, A. (2005). QuikSCAT Measurements and ECMWF Wind Forecasts heights overlaid with satellite mea- surements. #12;Impetus Forecasted wave heights overlaid with satellite mea- surements. Merge forecasts and satellite observations and provide a measure of uncertainty

Malmberg, Anders

473

Radiation by Moving Mirrors in Curved Space-Time  

Science Journals Connector (OSTI)

......theory in the presence of a mirror in a curved two-dimensional...change of acceleration of the mirror is independent of the state...comoving flux emitted by a mirror lowered in a static gravitational...Theory in Two-Dimensional Schwarzschild-de Sitter Spacetime. II......

Adrian Ottewill; Shin Takagi

1988-01-01T23:59:59.000Z

474

Space-time Brownian motion and the Beurling-Ahlfor...  

E-Print Network [OSTI]

the argument does not really treat the Beurling–Ahlfors operator as a single ... Burkholder, Martingales and singular integrals in Banach spaces, Handbook on.

Rodrigo BaŒuelos

2002-06-15T23:59:59.000Z

475

The symmetry and simplicity of the laws of physics and the Higgs boson  

E-Print Network [OSTI]

We describe the theoretical ideas, developed between the 1950s-1970s, which led to the prediction of the Higgs boson, the particle that was discovered in 2012. The forces of nature are based on symmetry principles. We explain the nature of these symmetries through an economic analogy. We also discuss the Higgs mechanism, which is necessary to avoid some of the naive consequences of these symmetries, and to explain various features of elementary particles.

Juan Maldacena

2014-10-24T23:59:59.000Z

476

The symmetry and simplicity of the laws of physics and the Higgs boson  

E-Print Network [OSTI]

We describe the theoretical ideas, developed between the 1950s-1970s, which led to the prediction of the Higgs boson, the particle that was discovered in 2012. The forces of nature are based on symmetry principles. We explain the nature of these symmetries through an economic analogy. We also discuss the Higgs mechanism, which is necessary to avoid some of the naive consequences of these symmetries, and to explain various features of elementary particles.

Maldacena, Juan

2014-01-01T23:59:59.000Z

477

Autonomous three dimensional Newtonian systems which admit Lie and Noether point symmetries  

E-Print Network [OSTI]

We determine the autonomous three dimensional Newtonian systems which admit Lie point symmetries and the three dimensional autonomous Newtonian Hamiltonian systems, which admit Noether point symmetries. We apply the results in order to determine the two dimensional Hamiltonian dynamical systems which move in a space of constant non-vanishing curvature and are integrable via Noether point symmetries. The derivation of the results is geometric and can be extended naturally to higher dimensions.

M. Tsamparlis; A. Paliathanasis; L. Karpathopoulos

2012-05-18T23:59:59.000Z

478

A way forward in the study of the symmetry energy: experiment, theory, and observation  

SciTech Connect (OSTI)

The symmetry energy describes how the energy of nuclear matter rises as one goes away from equal numbers of neutrons and protons. This is very important to describe neutron rich matter in astrophysics. This article reviews our knowledge of the symmetry energy from theoretical calculations, nuclear structure measurements, heavy ion collisions, and astronomical observations. We then present a roadmap to make progress in areas of relevance to the symmetry energy that promotes collaboration between astrophysics and the nuclear physics communities.

Horowitz, Charles; Brown, E F.; Kim, Y.; Lynch, W G.; Michaels, Robert; Ono, A.; Piekarewicz, Jorge; Tsang, M B.; Wolter, H H.

2014-07-01T23:59:59.000Z

479

Evidence for Triangular D_3h Symmetry in 12C  

E-Print Network [OSTI]

We report a measurement of a new high spin Jp = 5- state at 22.4(0.2) MeV in 12C which fits very well to the predicted (ground state) rotational band of an oblate equilateral triangular spinning top with a D_3h symmetry characterized by the sequence 0+, 2+, 3-, 4+/-, 5- with almost degenerate 4+ and 4- (parity doublet) states. Such a D_3h symmetry was observed in triatomic molecules and it is observed here for the first time in nuclear physics. We discuss a classification of other rotation-vibration bands in 12C such as the (0+) Hoyle band and the (1-) bending mode band and suggest measurements in search of the predicted ("missing") states that may shed new light on clustering in 12C and light nuclei. In particular the observation (or non-observation) of the predicted ("missing") states in the Hoyle band will allow us to conclude the geometrical arrangement of the three alpha-particle composing the Hoyle state at 7.654 MeV in 12C.

Marin-Lambarri, D J; Freer, M; Gai, M; Kokalova, Tz; Parker, D J; Wheldon, C

2014-01-01T23:59:59.000Z

480

Evidence for Triangular D_3h Symmetry in 12C  

E-Print Network [OSTI]

We report a measurement of a new high spin Jp = 5- state at 22.4(0.2) MeV in 12C which fits very well to the predicted (ground state) rotational band of an oblate equilateral triangular spinning top with a D_3h symmetry characterized by the sequence 0+, 2+, 3-, 4+/-, 5- with almost degenerate 4+ and 4- (parity doublet) states. Such a D_3h symmetry was observed in triatomic molecules and it is observed here for the first time in nuclear physics. We discuss a classification of other rotation-vibration bands in 12C such as the (0+) Hoyle band and the (1-) bending mode band and suggest measurements in search of the predicted ("missing") states that may shed new light on clustering in 12C and light nuclei. In particular the observation (or non-observation) of the predicted ("missing") states in the Hoyle band will allow us to conclude the geometrical arrangement of the three alpha-particle composing the Hoyle state at 7.654 MeV in 12C.

D. J. Marin-Lambarri; R. Bijker; M. Freer; M. Gai; Tz. Kokalova; D. J. Parker; C. Wheldon

2014-05-29T23:59:59.000Z

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481

SURFACE SYMMETRY ENERGY OF NUCLEAR ENERGY DENSITY FUNCTIONALS  

SciTech Connect (OSTI)

We study the bulk deformation properties of the Skyrme nuclear energy density functionals. Following simple arguments based on the leptodermous expansion and liquid drop model, we apply the nuclear density functional theory to assess the role of the surface symmetry energy in nuclei. To this end, we validate the commonly used functional parametrizations against the data on excitation energies of superdeformed band-heads in Hg and Pb isotopes, and fission isomers in actinide nuclei. After subtracting shell effects, the results of our self-consistent calculations are consistent with macroscopic arguments and indicate that experimental data on strongly deformed configurations in neutron-rich nuclei are essential for optimizing future nuclear energy density functionals. The resulting survey provides a useful benchmark for further theoretical improvements. Unlike in nuclei close to the stability valley, whose macroscopic deformability hangs on the balance of surface and Coulomb terms, the deformability of neutron-rich nuclei strongly depends on the surface-symmetry energy; hence, its proper determination is crucial for the stability of deformed phases of the neutron-rich matter and description of fission rates for r-process nucleosynthesis.

Nikolov, N; Schunck, N; Nazarewicz, W; Bender, M; Pei, J

2010-12-20T23:59:59.000Z

482

Mesoscale symmetries explain dynamical equivalence of food webs  

Science Journals Connector (OSTI)

A goal of complex system research is to identify the dynamical implications of network structure. While early results focused mainly on local or global structural properties, there is now growing interest in mesoscale structures that comprise more than one node but not the whole network. A central challenge is to discover under what conditions the occurrence of a specific mesoscale motif already allows conclusions on the dynamics of a network as a whole. In this paper, we investigate the dynamics of ecological food webs, complex heterogeneous networks of interacting populations. Generalizing the results of MacArthur and Sánchez-García (2009 Phys. Rev. E 80 26117), we show that certain mesoscale symmetries imply the existence of localized dynamical modes. If these modes are unstable the occurrence of the corresponding mesoscale motif implies dynamical instability regardless of the structure of the embedding network. In contrast, if the mode is stable it means that the symmetry can be exploited to reduce the number of nodes in the model, without changing the dynamics of the system. This result explains a previously observed dynamical equivalence between food webs containing a different number of species.

Helge Aufderheide; Lars Rudolf; Thilo Gross

2012-01-01T23:59:59.000Z

483

Flavour symmetry breaking in the kaon parton distribution amplitude  

E-Print Network [OSTI]

We compute the kaon's valence-quark (twist-two parton) distribution amplitude (PDA) by projecting its Poincare'-covariant Bethe-Salpeter wave-function onto the light-front. At a scale \\zeta=2GeV, the PDA is a broad, concave and asymmetric function, whose peak is shifted 12-16% away from its position in QCD's conformal limit. These features are a clear expression of SU(3)-flavour-symmetry breaking. They show that the heavier quark in the kaon carries more of the bound-state's momentum than the lighter quark and also that emergent phenomena in QCD modulate the magnitude of flavour-symmetry breaking: it is markedly smaller than one might expect based on the difference between light-quark current masses. Our results add to a body of evidence which indicates that at any energy scale accessible with existing or foreseeable facilities, a reliable guide to the interpretation of experiment requires the use of such nonperturbatively broadened PDAs in leading-order, leading-twist formulae for hard exclusive processes instead of the asymptotic PDA associated with QCD's conformal limit. We illustrate this via the ratio of kaon and pion electromagnetic form factors: using our nonperturbative PDAs in the appropriate formulae, $F_K/F_\\pi=1.23$ at spacelike-$Q^2=17\\,{\\rm GeV}^2$, which compares satisfactorily with the value of $0.92(5)$ inferred in $e^+ e^-$ annihilation at $s=17\\,{\\rm GeV}^2$.

Chao Shi; Lei Chang; Craig D. Roberts; Sebastian M. Schmidt; Peter C. Tandy; Hong-Shi Zong

2014-06-12T23:59:59.000Z

484

Long distance symmetries for nuclear forces and the similarity renormalization group  

SciTech Connect (OSTI)

In this work we study the emergence of long distance symmetries for nuclear forces within the framework of the similarity renormalization group approach.

Szpigel, S. [Faculdade de Computacao e Informatica, Universidade Presbiteriana Mackenzie, 01302-907, Sao Paulo - SP (Brazil); Timoteo, V. S. [Faculdade de Tecnologia, Universidade Estadual de Campinas, 13484-332, Limeira - SP (Brazil); Arriola, E. R. [Departamento de Fisica Atomica, Molecular y Nuclear and Instituto Carlos I de Fisica Teorica y Computacional, Universidad de Granada, E-18071, Granada (Spain)

2013-03-25T23:59:59.000Z

485

Symmetry-dictated trucation: Solutions of the spherical shell model for heavy nuclei  

SciTech Connect (OSTI)

Principles of dynamical symmetry are used to simplify the spherical shell model. The resulting symmetry-dictated truncation leads to dynamical symmetry solutions that are often in quantitative agreement with a variety of observables. Numerical calculations, including terms that break the dynamical symmetries, are shown that correspond to shell model calculations for heavy deformed nuclei. The effective residual interaction is simple, well-behaved, and can be determined from basic observables. With this approach, we intend to apply the shell model in systematic fashion to all nuclei. The implications for nuclear structure far from stability and for nuclear masses and other quantities of interest in astrophysics are discussed.

Guidry, M.W. [Tennessee Univ., Knoxville, TN (United States). Dept. of Physics]|[Oak Ridge National Lab., TN (United States)

1992-12-31T23:59:59.000Z

486

Matrix elements of the tight?binding method for lattices with D 14 4h symmetry  

Science Journals Connector (OSTI)

We have evaluated the matrix components of the Hamiltonian in the LCAO approximation for crystals with D 14 4h symmetry.

C. Jouanin; C. Gout; J. P. Albert

1975-01-01T23:59:59.000Z

487

E-Print Network 3.0 - approximate su3 symmetry Sample Search...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

strong... effects can be controlled with the help of SU(3) symmetry, by relating them to tree-level amplitudes... corresponding to different decays are ... Source: Cornell...

488

Ramifications of the Nuclear Symmetry Energy for Neutron Stars, Nuclei, and Heavy-Ion Collisions  

E-Print Network [OSTI]

The pervasive role of the nuclear symmetry energy in establishing some nuclear static and dynamical properties, and in governing some attributes of neutron star properties is highlighted.

Andrew W. Steiner; Bao-An Li; Madappa Prakash

2007-11-29T23:59:59.000Z

489

Nuclear symmetry energy effects on liquid-gas phase transition in hot asymmetric nuclear matter  

E-Print Network [OSTI]

The liquid-gas phase transition in hot asymmetric nuclear matter is investigated within relativistic mean-field model using the density dependence of nuclear symmetry energy constrained from the measured neutron skin thickness of finite nuclei. We find symmetry energy has a significant influence on several features of liquid-gas phase transition. The boundary and area of the liquid-gas coexistence region, the maximal isospin asymmetry and the critical values of pressure and isospin asymmetry all of which systematically increase with increasing softness in the density dependence of symmetry energy. The critical temperature below which the liquid-gas mixed phase exists is found higher for a softer symmetry energy.

Bharat K. Sharma; Subrata Pal

2010-01-14T23:59:59.000Z

490

E-Print Network 3.0 - a4 flavour symmetry Sample Search Results  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

- Department of Physics, East Carolina University Collection: Physics 13 Theory and Phenomenology of CP Violation Thomas Mannela Summary: describe. Flavour Symmetries: Isospin or...

491

$N$-boson spectrum from a Discrete Scale Invariance  

E-Print Network [OSTI]

We present the analysis of the $N$-boson spectrum computed using a soft two-body potential the strength of which has been varied in order to cover an extended range of positive and negative values of the two-body scattering length $a$ close to the unitary limit. The spectrum shows a tree structure of two states, one shallow and one deep, attached to the ground-state of the system with one less particle. It is governed by an unique universal function, $\\Delta(\\xi)$, already known in the case of three bosons. In the three-particle system the angle $\\xi$, determined by the ratio of the two- and three-body binding energies $E_3/E_2=\\tan^2\\xi$, characterizes the Discrete Scale Invariance of the system. Extending the definition of the angle to the $N$-body system as $E_N/E_2=\\tan^2\\xi$, we study the $N$-boson spectrum in terms of this variable. The analysis of the results, obtained for up to $N=16$ bosons, allows us to extract a general formula for the energy levels of the system close to the unitary limit. Interestingly, a linear dependence of the universal function as a function of $N$ is observed at fixed values of $a$. We show that the finite-range nature of the calculations results in the range corrections that generate a shift of the linear relation between the scattering length $a$ and a particular form of the universal function. We also comment on the limits of applicability of the universal relations.

A. Kievsky; N. K. Timofeyuk; M. Gattobigio

2014-05-10T23:59:59.000Z

492

A LARGE SCALE CONTINUUM-DISCRETE NUMERICAL MODELLING: APPLICATION TO OVERBURDEN DAMAGE OF A SALT CAVERN  

E-Print Network [OSTI]

CAVERN SOULEY Mountaka1 , MERCERAT Diego2 , DRIAD-LEBEAU Lynda1 , BERNARD Pascal2 1 INERIS, Ecole des collapse). KEYWORDS: cavern, numerical modelling, continuum-discrete, overburden, damage. RÃ?SUMÃ?: Dans l

Boyer, Edmond

493

NEURAL NETWORKS FOR DISCRETE TOMOGRAPHY K.J. Batenburg a W.A. Kosters b  

E-Print Network [OSTI]

NEURAL NETWORKS FOR DISCRETE TOMOGRAPHY K.J. Batenburg a W.A. Kosters b a Mathematical Institute of crystalline solids at atomic resolution from electron microscopic images can be considered the ``holy grail

Kosters, Walter

494

Discrete Packet Analysis for Improved Atmospheric Rejection on Modulated Laser Signals  

SciTech Connect (OSTI)

This slide-show discusses how the method of discrete packet analysis improves atmospheric compensation for quasi-CW fluorescence detection methods. This is key to improving remote sensing capabilities.

O'Neill, M., McKenna, I., DiBenedetto, J., Capelle, G., Trainham, R.

2012-07-19T23:59:59.000Z

495

Discrete flow mapping: transport of phase space densities on triangulated surfaces  

Science Journals Connector (OSTI)

...The response of a thin moulded aluminium car component (range rover shock tower) to...discretization schemes for the shallow-water equations. Mont. Weather Rev. 138...Lyon, RH . 1969 Statistical analysis of power injection and response in structures and...

2013-01-01T23:59:59.000Z

496

Testing and examination of TMI-2 electrical components and discrete devices  

SciTech Connect (OSTI)

This report discusses the approach and results of the in situ test conducted on TMI-2 reactor building electrical components and discrete devices. Also included are the necessary presumptions and assumptions to correlate observed anomalies to the accident.

Soberano, F.T.

1982-11-01T23:59:59.000Z

497

A Parametric Mixed-Integer Optimization Algorithm for Multiobjective Engineering Problems Involving Discrete Decisions  

Science Journals Connector (OSTI)

When the multiobjective problem involves continuous and discrete decisions, as is usually the case in process decision making, it can be formulated as follows: ... The parametric programming theory has mostly focused on linear problems (Gal, 1979). ...

Katerina P. Papalexandri; Theodora I. Dimkou

1998-04-16T23:59:59.000Z

498

A simple preconditioner for the SIPG discretization of linear elasticity equations  

Science Journals Connector (OSTI)

We deal with the solution of the systems of linear algebraic equations arising from Symmetric Interior Penalty discontinuous Galerkin (SIPG) discretization of linear elasticity problems in primal (displacement) formulation. The main focus of the paper ...

B. Ayuso; I. Georgiev; J. Kraus; L. Zikatanov

2010-08-01T23:59:59.000Z

499

DSA Preconditioning for the S_N Equations with Strictly Positive Spatial Discretization  

E-Print Network [OSTI]

Preconditioners based upon sweeps and diffusion-synthetic acceleration (DSA) have been constructed and applied to the zeroth and first spatial moments of the 1-D transport equation using SN angular discretization and a strictly positive nonlinear...

Bruss, Donald

2012-07-16T23:59:59.000Z

500

Algebraic multigrid for stabilized finite element discretizations of the Navier Stokes equation  

E-Print Network [OSTI]

A multilevel method for the solution of systems of equations generated by stabilized Finite Element discretizations of the Euler and Navier Stokes equations on generalized unstructured grids is described. The method is ...

Okusanya, Tolulope Olawale, 1972 -

2002-01-01T23:59:59.000Z