WorldWideScience

Sample records for point symmetry group

  1. Surface field theories of point group symmetry protected topological phases

    Science.gov (United States)

    Huang, Sheng-Jie; Hermele, Michael

    2018-02-01

    We identify field theories that describe the surfaces of three-dimensional bosonic point group symmetry protected topological (pgSPT) phases. The anomalous nature of the surface field theories is revealed via a dimensional reduction argument. Specifically, we study three different surface field theories. The first field theory is quantum electrodynamics in three space-time dimensions (QED3) with four flavors of fermions. We show this theory can describe the surfaces of a majority of bosonic pgSPT phases protected by a single mirror reflection, or by Cn v point group symmetry for n =2 ,3 ,4 ,6 . The second field theory is a variant of QED3 with charge-1 and charge-3 Dirac fermions. This field theory can describe the surface of a reflection symmetric pgSPT phase built by placing an E8 state on the mirror plane. The third field theory is an O (4 ) nonlinear sigma model with a topological theta term at θ =π , or, equivalently, a noncompact CP1 model. Using a coupled wire construction, we show this is a surface theory for bosonic pgSPT phases with U (1 ) ×Z2P symmetry. For the latter two field theories, we discuss the connection to gapped surfaces with topological order. Moreover, we conjecture that the latter two field theories can describe surfaces of more general bosonic pgSPT phases with Cn v point group symmetry.

  2. The utilization of abelian point group symmetry in the graphical unitary group approach to the calculation of correlated electronic wavefunctions

    Science.gov (United States)

    Shavitt, I.

    1979-01-01

    A procedure is described for the utilization of abelian point group symmetry in the graphical unitary group approach (GUGA) to calculations of correlated electronic wavefunctions. The procedure is based on a recursively computed set of symmetry dependent counting indices, and results in the separate numbering, without gaps, of the Gelfand states (configuration functions) belonging to each symmetry species

  3. Many body topological invariants in topological phases with point group symmetry

    Science.gov (United States)

    Shiozaki, Ken; Shapourian, Hassan; Ryu, Shinsei

    A way to detect topological phases from a given short-range entangled state is discussed. Many body topological invariants are defined as partition functions of topological quantum field theory (TQFT) on space-time manifolds, for example, real projective spaces. It is expected that by translating TQFT partition functions to the operator formalism one can get a definition of many body topological invariants made from ground state wave functions and symmetry operations. We propose that a kind of non-local operator, the ''partial point group transformation'', on a short-range entangled state is a unified measure to detect topologically nontrivial phases with point group symmetry. In this talk, I introduce (i) the partial rotations on (2 +1)d chiral superconductors, and (ii) the Z16 invariant from the partial inversion on (3 +1)d superconductors. These partial point group transformations can be analytically calculated from the boundary theory. We confirmed that analytical results from the boundary theory match with direct numerical calculations on bulk.

  4. Symmetry and group theory in chemistry

    CERN Document Server

    Ladd, M

    1998-01-01

    A comprehensive discussion of group theory in the context of molecular and crystal symmetry, this book covers both point-group and space-group symmetries.Provides a comprehensive discussion of group theory in the context of molecular and crystal symmetryCovers both point-group and space-group symmetriesIncludes tutorial solutions

  5. Groups and Symmetry

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 4; Issue 10. Groups and Symmetry: A Guide to Discovering Mathematics. Geetha Venkataraman. Book Review Volume 4 Issue 10 October 1999 pp 91-92. Fulltext. Click here to view fulltext PDF. Permanent link:

  6. Groups and symmetry

    CERN Document Server

    Farmer, David W

    1995-01-01

    In most mathematics textbooks, the most exciting part of mathematics-the process of invention and discovery-is completely hidden from the reader. The aim of Groups and Symmetry is to change all that. By means of a series of carefully selected tasks, this book leads readers to discover some real mathematics. There are no formulas to memorize; no procedures to follow. The book is a guide: Its job is to start you in the right direction and to bring you back if you stray too far. Discovery is left to you. Suitable for a one-semester course at the beginning undergraduate level, there are no prerequ

  7. Group analysis and renormgroup symmetries

    International Nuclear Information System (INIS)

    Kovalev, V.F.; Pustovalov, V.V.; Shirkov, D.V.

    1996-01-01

    An original regular approach to constructing special type symmetries for boundary-value problems, namely renormgroup symmetries, is presented. Different methods of calculating these symmetries based on modern group analysis are described. An application of the approach to boundary value problems is demonstrated with the help of a simple mathematical model. 35 refs

  8. 8x8 and 10x10 Hyperspace Representations of SU(3) and 10-fold Point-Symmetry Group of Quasicrystals

    Science.gov (United States)

    Animalu, Alexander

    2012-02-01

    In order to further elucidate the unexpected 10-fold point-symmetry group structure of quasi-crystals for which the 2011 Nobel Prize in chemistry was awarded to Daniel Shechtman, we explore a correspondence principle between the number of (projective) geometric elements (points[vertices] + lines[edges] + planes[faces]) of primitive cells of periodic or quasi-periodic arrangement of hard or deformable spheres in 3-dimensional space of crystallography and elements of quantum field theory of particle physics [points ( particles, lines ( particles, planes ( currents] and hence construct 8x8 =64 = 28+36 = 26 + 38, and 10x10 =100= 64 + 36 = 74 + 26 hyperspace representations of the SU(3) symmetry of elementary particle physics and quasicrystals of condensed matter (solid state) physics respectively, As a result, we predict the Cabibbo-like angles in leptonic decay of hadrons in elementary-particle physics and the observed 10-fold symmetric diffraction pattern of quasi-crystals.

  9. Fluid relabelling symmetries, Lie point symmetries and the Lagrangian map in magnetohydrodynamics and gas dynamics

    Science.gov (United States)

    Webb, G. M.; Zank, G. P.

    2007-01-01

    We explore the role of the Lagrangian map for Lie symmetries in magnetohydrodynamics (MHD) and gas dynamics. By converting the Eulerian Lie point symmetries of the Galilei group to Lagrange label space, in which the Eulerian position coordinate x is regarded as a function of the Lagrange fluid labels x0 and time t, one finds that there is an infinite class of symmetries in Lagrange label space that map onto each Eulerian Lie point symmetry of the Galilei group. The allowed transformation of the Lagrangian fluid labels x0 corresponds to a fluid relabelling symmetry, including the case where there is no change in the fluid labels. We also consider a class of three, well-known, scaling symmetries for a gas with a constant adiabatic index γ. These symmetries map onto a modified form of the fluid relabelling symmetry determining equations, with non-zero source terms. We determine under which conditions these symmetries are variational or divergence symmetries of the action, and determine the corresponding Lagrangian and Eulerian conservation laws by use of Noether's theorem. These conservation laws depend on the initial entropy, density and magnetic field of the fluid. We derive the conservation law corresponding to the projective symmetry in gas dynamics, for the case γ = (n + 2)/n, where n is the number of Cartesian space coordinates, and the corresponding result for two-dimensional (2D) MHD, for the case γ = 2. Lie algebraic structures in Lagrange label space corresponding to the symmetries are investigated. The Lie algebraic symmetry relations between the fluid relabelling symmetries in Lagrange label space, and their commutators with a linear combination of the three symmetries with a constant adiabatic index are delineated.

  10. Fluid relabelling symmetries, Lie point symmetries and the Lagrangian map in magnetohydrodynamics and gas dynamics

    International Nuclear Information System (INIS)

    Webb, G M; Zank, G P

    2007-01-01

    We explore the role of the Lagrangian map for Lie symmetries in magnetohydrodynamics (MHD) and gas dynamics. By converting the Eulerian Lie point symmetries of the Galilei group to Lagrange label space, in which the Eulerian position coordinate x is regarded as a function of the Lagrange fluid labels x 0 and time t, one finds that there is an infinite class of symmetries in Lagrange label space that map onto each Eulerian Lie point symmetry of the Galilei group. The allowed transformation of the Lagrangian fluid labels x 0 corresponds to a fluid relabelling symmetry, including the case where there is no change in the fluid labels. We also consider a class of three, well-known, scaling symmetries for a gas with a constant adiabatic index γ. These symmetries map onto a modified form of the fluid relabelling symmetry determining equations, with non-zero source terms. We determine under which conditions these symmetries are variational or divergence symmetries of the action, and determine the corresponding Lagrangian and Eulerian conservation laws by use of Noether's theorem. These conservation laws depend on the initial entropy, density and magnetic field of the fluid. We derive the conservation law corresponding to the projective symmetry in gas dynamics, for the case γ = (n + 2)/n, where n is the number of Cartesian space coordinates, and the corresponding result for two-dimensional (2D) MHD, for the case γ = 2. Lie algebraic structures in Lagrange label space corresponding to the symmetries are investigated. The Lie algebraic symmetry relations between the fluid relabelling symmetries in Lagrange label space, and their commutators with a linear combination of the three symmetries with a constant adiabatic index are delineated

  11. GENERAL: A Maple Package to Compute Lie Symmetry Groups and Symmetry Reductions of (1+1)-Dimensional Nonlinear Systems

    Science.gov (United States)

    Yao, Ruo-Xia; Lou, Sen-Yue

    2008-06-01

    Armed with the computer algebra system Maple, using a direct algebraic substitution method, we obtain Lie point symmetries, Lie symmetry groups and the corresponding symmetry reductions of one component nonlinear integrable and nonintegrable equations only by clicking the 'Enter' key. Abundant (1+1)-dimensional nonlinear mathematical physical systems are analysed effectively by using a Maple package LieSYMGRP proposed by us.

  12. Partial dynamical symmetry at critical points of quantum phase transitions.

    Science.gov (United States)

    Leviatan, A

    2007-06-15

    We show that partial dynamical symmetries can occur at critical points of quantum phase transitions, in which case underlying competing symmetries are conserved exactly by a subset of states, and mix strongly in other states. Several types of partial dynamical symmetries are demonstrated with the example of critical-point Hamiltonians for first- and second-order transitions in the framework of the interacting boson model, whose dynamical symmetries correspond to different shape phases in nuclei.

  13. Partial Dynamical Symmetry at Critical Points of Quantum Phase Transitions

    International Nuclear Information System (INIS)

    Leviatan, A.

    2007-01-01

    We show that partial dynamical symmetries can occur at critical points of quantum phase transitions, in which case underlying competing symmetries are conserved exactly by a subset of states, and mix strongly in other states. Several types of partial dynamical symmetries are demonstrated with the example of critical-point Hamiltonians for first- and second-order transitions in the framework of the interacting boson model, whose dynamical symmetries correspond to different shape phases in nuclei

  14. Symmetry and group theory throughout physics

    Directory of Open Access Journals (Sweden)

    Villain J.

    2012-03-01

    Full Text Available As noticed in 1884 by Pierre Curie [1], physical properties of matter are tightly related to the kind of symmetry of the medium. Group theory is a systematic tool, though not always easy to handle, to exploit symmetry properties, for instance to find the eigenvectors and eigenvalues of an operator. Certain properties (optical activity, piezoelectricity are forbidden in molecules or crystals of high symmetry. A few theorems (Noether, Goldstone establish general relations between physical properties and symmetry. Applications of group theory to condensed matter physics, elementary particle physics, quantum mechanics, electromagnetism are reviewed. Group theory is not only a tool, but also a beautiful construction which casts insight into natural phenomena.

  15. Group symmetries and information propagation

    International Nuclear Information System (INIS)

    Draayer, J.P.

    1980-01-01

    Spectroscopy concerns itself with the ways in which the Hamiltonian and other interesting operators defined in few-particle spaces are determined or determine properties of many-particle systems. But the action of the central limit theorem (CLT) filters the transmission of information between source and observed so whether propagating forward from a few-particle defining space, as is usual in theoretical studies, or projecting backward to it from measured things, each is only sensitive to averaged properties of the other. Our concern is with the propagation of spectroscopic information in the presence of good symmetries when filtering action of the CLT is effective. Specifically, we propose to address the question, What propagates and how. We begin with some examples, using both scalar and isospin geometries to illustrate simple propagation. Examples of matrix propagation are studied; contact with standard tensor algebra is established and an algorithm put forward for the expansion of any operator in terms of another set, complete or not; shell-model results for 20 Ne using a realistic interaction and two trace-equivalent forms are presented; and some further challenges are mentioned

  16. Linear or linearizable first-order delay ordinary differential equations and their Lie point symmetries

    Science.gov (United States)

    Dorodnitsyn, Vladimir A.; Kozlov, Roman; Meleshko, Sergey V.; Winternitz, Pavel

    2018-05-01

    A recent article was devoted to an analysis of the symmetry properties of a class of first-order delay ordinary differential systems (DODSs). Here we concentrate on linear DODSs, which have infinite-dimensional Lie point symmetry groups due to the linear superposition principle. Their symmetry algebra always contains a two-dimensional subalgebra realized by linearly connected vector fields. We identify all classes of linear first-order DODSs that have additional symmetries, not due to linearity alone, and we present representatives of each class. These additional symmetries are then used to construct exact analytical particular solutions using symmetry reduction.

  17. Computing the Symmetry Groups of the Platonic Solids With the ...

    Indian Academy of Sciences (India)

    teaching a course in abstract algebra and trying to introduce the students to Maple. Keywords. Platonic solids, symmetry groups, Maple package. Figure 1. Patrick J Morandi ... group theory and use of the computer algebra package. Maple. The five .... To help understand the Maple commands we use, we point out that the ...

  18. Emergent symmetry and dimensional reduction at a quantum critical point

    Science.gov (United States)

    Schmalian, J.; Batista, C. D.

    2008-03-01

    We show that the spatial dimensionality of the quantum critical point associated with Bose-Einstein condensation at T=0 is reduced when the underlying lattice comprises a set of layers coupled by a frustrating interaction. For this purpose, we use an heuristic mean field approach that is complemented and justified by a more rigorous renormalization group analysis. Due to the presence of an emergent symmetry, i.e., a symmetry of the ground state that is absent in the underlying Hamiltonian, a three-dimensional interacting Bose system undergoes a chemical potential tuned quantum phase transition that is strictly two-dimensional. Our theoretical predictions for the critical temperature as a function of the chemical potential correspond very well with recent measurements in BaCuSi2O6 .

  19. Lie point symmetries of differential-difference equations

    Energy Technology Data Exchange (ETDEWEB)

    Levi, D [Dipartimento di Ingegneria Elettronica, Universita degli Studi Roma Tre and Sezione INFN, Roma Tre, Via della Vasca Navale 84, 00146 Roma (Italy); Winternitz, P [Centre de recherches mathematiques et, Departement de mathematiques et statistique, Universite de Montreal, C.P. 6128, succ. Centre-ville, H3C 3J7, Montreal, Quebec (Canada); Yamilov, R I, E-mail: levi@roma3.infn.i, E-mail: wintern@crm.umontreal.c, E-mail: RvlYamilov@matem.anrb.r [Ufa Institute of Mathematics, Russian Academy of Sciences, 112 Chernyshevsky Street, Ufa 450008 (Russian Federation)

    2010-07-23

    We present an algorithm for determining the Lie point symmetries of differential equations on fixed non-transforming lattices, i.e. equations involving both continuous and discrete-independent variables. The symmetries of a specific integrable discretization of the Krichever-Novikov equation, the Toda lattice and Toda field theory are presented as examples of the general method. (fast track communication)

  20. Discrete Flavour Symmetries from the Heisenberg Group

    CERN Document Server

    Floratos, E.G.

    2016-01-01

    Non-abelian discrete symmetries are of particular importance in model building. They are mainly invoked to explain the various fermion mass hierarchies and forbid dangerous superpotential terms. In string models they are usually associated to the geometry of the compactification manifold and more particularly to the magnetised branes in toroidal compactifications. Motivated by these facts, in this note we propose a unified framework to construct representations of finite discrete family groups based on the automorphisms of the discrete and finite Heisenberg group. We focus in particular in the $PSL_2(p)$ groups which contain the phenomenologically interesting cases.

  1. Symplectic structures and dynamical symmetry groups

    International Nuclear Information System (INIS)

    Torres del Castillo, G.F.; Velazquez Q, M.P.

    2004-01-01

    Apart from the total energy, the two-dimensional isotropic harmonic oscillator possesses three independent constants of motion which, with the standard symplectic structure, generates a dynamical symmetry group isomorphic to SU (2). We show that, by suitably redefining the symplectic structure, any of these three constants of motion can be used as a Hamiltonian, and that the remaining two, together with the total energy, generate a dynamical symmetry group isomorphic to SU (1,1). We also show that the standard energy levels of the quantum two-dimensional isotropic harmonic oscillator and their degeneracies are obtained making use of the appropriate representations of SU(1,1), provided that the canonical commutation relations are modified according to the new symplectic structure. Whereas in classical mechanics the different symplectic structures lead to equivalent formulations of the equations of motion, in quantum mechanics the modifications of the commutation relations should be accompanied by modifications in the interpretation of the formalism in order to obtain results equivalent to those found with the common relations. (Author) 12 refs

  2. Symmetry groups of state vectors in canonical quantum gravity

    International Nuclear Information System (INIS)

    Witt, D.M.

    1986-01-01

    In canonical quantum gravity, the diffeomorphisms of an asymptotically flat hypersurface S, not connected to the identity, but trivial at infinity, can act nontrivially on the quantum state space. Because state vectors are invariant under diffeomorphisms that are connected to the identity, the group of inequivalent diffeomorphisms is a symmetry group of states associated with S. This group is the zeroth homotopy group of the group of diffeomorphisms fixing a frame of infinity on S. It is calculated for all hypersurfaces of the form S = S 3 /G-point, where the removed point is thought of as infinity on S and the symmetry group S is the zeroth homotopy group of the group of diffeomorphisms of S 3 /G fixing a point and frame, denoted π 0 Diff/sub F/(S 3 /G). Before calculating π 0 Diff/sub F/ (S 3 /G), it is necessary to find π 0 of the group of diffeomorphisms. Once π 0 Diff(S 3 /G) is known, π 0 Diff/sub x/ 0 (S 3 /G) is calculated using a fiber bundle involving Diff(S 3 /G), Diff/sub x/ 0 (S 3 /G), and S 3 /G. Finally, a fiber bundle involving Diff/sub F/(S 3 /G), Diff(S 3 /G), and the bundle of frames over S 3 /G is used along with π 0 Diff/sub x/ 0 (S 3 /G) to calculate π 0 Diff/sub F/(S 3 /G)

  3. The open superstring 6-point amplitude with manifest symmetries

    International Nuclear Information System (INIS)

    Barreiro, Luiz Antonio; Medina, Ricardo; Stieberger, Stephan

    2011-01-01

    Full text: The general tree level amplitude for massless bosons states of open superstrings has been known for a long time ago. It is clear how to obtain this general formula using vertex operators in the Ramond-Neveu-Schwarz formalism. From the beginning of the eighties the explicit expression for this formula has been known in the case of 3 and 4-point amplitudes. In that decade an attempt (with partial success) was done, by Kitazawa, to obtain the corresponding 5-point amplitude. Only in 2002 a complete and correct expression for this amplitude was obtained. Its low energy expansion was compared to the corresponding one from the low energy effective Lagrangian of the open superstring, finding a perfect match. A few years later, in 2005, it was realized that the 5-point formula could be written in a very much compact form, as a sum of two terms: each of them consisting of a momentum factor and a kinematic expression. This constituted a generalization of the 4-point amplitude case, which had been known to be cast in only one momentum factor multiplied by one kinematic expression. For this simplification to happen, known symmetries of the (tree level) scattering amplitudes were implemented in a manifest form. These symmetries are (on-shell) gauge symmetry, cyclic symmetry and twisting symmetry (or world sheet parity). In the recent years it has been realized that the N-point amplitude can be written as a sum of (N - 3)! terms (where N > 3). This result not only agrees with the 3, 4 and 5-point results, but also with the 6-point result which had been obtained by 2005, written as a sum of six terms. The expression that up to now has been obtained for the 6-point amplitude is quite complicated and, besides knowing that it consists of six terms, is not very illuminating. In this work we report on the recent result of writing the 6-point amplitude with gauge, cyclic and twisting symmetries manifest. Not only because of the manifest symmetries this result is important

  4. Radiative symmetry breaking from interacting UV fixed points

    DEFF Research Database (Denmark)

    Abel, Steven; Sannino, Francesco

    2017-01-01

    It is shown that the addition of positive mass-squared terms to asymptotically safe gauge-Yukawa theories with perturbative UV fixed points leads to calculable radiative symmetry breaking in the IR. This phenomenon, and the multiplicative running of the operators that lies behind it, is akin...

  5. On Lie point symmetry of classical Wess-Zumino-Witten model

    International Nuclear Information System (INIS)

    Maharana, Karmadeva

    2001-06-01

    We perform the group analysis of Witten's equations of motion for a particle moving in the presence of a magnetic monopole, and also when constrained to move on the surface of a sphere, which is the classical example of Wess-Zumino-Witten model. We also consider variations of this model. Our analysis gives the generators of the corresponding Lie point symmetries. The Lie symmetry corresponding to Kepler's third law is obtained in two related examples. (author)

  6. Computing the Symmetry Groups of the Platonic Solids With the ...

    Indian Academy of Sciences (India)

    In this article we will determine the symmetry groups of the platonic solids by a combination of some elementary group theory and use of the computer algebra package. Maple. The five platonic solids are the tetrahedron, the cube, the octahedron, the dodecahedron, and the icosa- hedron. By determining a symmetry group, ...

  7. Critical-point symmetry in a finite system

    International Nuclear Information System (INIS)

    Leviatan, A.; Ginocchio, J. N.

    2003-01-01

    At a critical point of a second-order phase transition the intrinsic energy surface is flat and there is no stable minimum value of the deformation. However, for a finite system, we show that there is an effective deformation which can describe the dynamics at the critical point. This effective deformation is determined by minimizing the energy surface after projection onto the appropriate symmetries. We derive analytic expressions for energies and quadrupole rates which provide good estimates for these observables at the critical point

  8. Critical-point symmetry in a finite system.

    Science.gov (United States)

    Leviatan, A; Ginocchio, J N

    2003-05-30

    At a critical point of a second-order phase transition the intrinsic energy surface is flat and there is no stable minimum value of the deformation. However, for a finite system, we show that there is an effective deformation which can describe the dynamics at the critical point. This effective deformation is determined by minimizing the energy surface after projection onto the appropriate symmetries. We derive analytic expressions for energies and quadrupole rates which provide good estimates for these observables at the critical point.

  9. Gene microarray data analysis using parallel point-symmetry-based clustering.

    Science.gov (United States)

    Sarkar, Anasua; Maulik, Ujjwal

    2015-01-01

    Identification of co-expressed genes is the central goal in microarray gene expression analysis. Point-symmetry-based clustering is an important unsupervised learning technique for recognising symmetrical convex- or non-convex-shaped clusters. To enable fast clustering of large microarray data, we propose a distributed time-efficient scalable approach for point-symmetry-based K-Means algorithm. A natural basis for analysing gene expression data using symmetry-based algorithm is to group together genes with similar symmetrical expression patterns. This new parallel implementation also satisfies linear speedup in timing without sacrificing the quality of clustering solution on large microarray data sets. The parallel point-symmetry-based K-Means algorithm is compared with another new parallel symmetry-based K-Means and existing parallel K-Means over eight artificial and benchmark microarray data sets, to demonstrate its superiority, in both timing and validity. The statistical analysis is also performed to establish the significance of this message-passing-interface based point-symmetry K-Means implementation. We also analysed the biological relevance of clustering solutions.

  10. Beauty is Attractive: Moduli Trapping at Enhanced Symmetry Points

    Energy Technology Data Exchange (ETDEWEB)

    Kofman, L

    2004-02-27

    We study quantum effects on moduli dynamics arising from the production of particles which are light at points of enhanced symmetry in moduli space. The resulting forces trap the moduli at these points. Moduli trapping occurs in time-dependent quantum field theory, as well as in systems of moving D-branes, where it leads the branes to combine into stacks. Trapping also occurs in the presence of gravity, though the range over which the moduli can roll is limited by Hubble friction. We observe that a scalar field trapped on a steep potential can induce a stage of acceleration of the universe, which we call trapped inflation. Moduli trapping ameliorates the cosmological moduli problem and may affect vacuum selection. In particular, rolling moduli are most powerfully attracted to the points of greatest symmetry. Given suitable assumptions about the dynamics of the very early universe, this effect might help to explain why among the plethora of possible vacuum states of string theory, we appear to live in one with a large number of (spontaneously broken) symmetries.

  11. Symmetry an introduction to group theory and its applications

    CERN Document Server

    McWeeny, Roy

    2002-01-01

    Well-organized volume develops ideas of group and representation theory in progressive fashion. Emphasis on finite groups describing symmetry of regular polyhedra and of repeating patterns, plus geometric illustrations.

  12. Lie symmetries and differential galois groups of linear equations

    NARCIS (Netherlands)

    Oudshoorn, W.R.; Put, M. van der

    2002-01-01

    For a linear ordinary differential equation the Lie algebra of its infinitesimal Lie symmetries is compared with its differential Galois group. For this purpose an algebraic formulation of Lie symmetries is developed. It turns out that there is no direct relation between the two above objects. In

  13. Allowable irreducible representations of the point groups with five ...

    Indian Academy of Sciences (India)

    Allowable irreducible representations of the point groups with five-fold rotations – that represent the symmetry of the quasicrystals in two and three dimensions – are derived by employing the little group technique in conjunction with the solvability property. The point groups D 5 h ( 10 ¯ m 2 ) and I h ( 2 m 3 ¯ 5 ¯ ) are taken ...

  14. Symmetry Reductions and Group-Invariant Radial Solutions to the n-Dimensional Wave Equation

    Science.gov (United States)

    Feng, Wei; Zhao, Songlin

    2018-01-01

    In this paper, we derive explicit group-invariant radial solutions to a class of wave equation via symmetry group method. The optimal systems of one-dimensional subalgebras for the corresponding radial wave equation are presented in terms of the known point symmetries. The reductions of the radial wave equation into second-order ordinary differential equations (ODEs) with respect to each symmetry in the optimal systems are shown. Then we solve the corresponding reduced ODEs explicitly in order to write out the group-invariant radial solutions for the wave equation. Finally, several analytical behaviours and smoothness of the resulting solutions are discussed.

  15. GENERAL: Symmetry Reductions and Group-Invariant Solutions of (2 + 1)-Dimensional Caudrey-Dodd-Gibbon-Kotera-Sawada Equation

    Science.gov (United States)

    Lü, Na; Mei, Jian-Qin; Zhang, Hong-Qing

    2010-04-01

    With the aid of symbolic computation, we present the symmetry transformations of the (2 + 1)-dimensional Caudrey-Dodd-Gibbon-Kotera-Sawada equation with Lou's direct method that is based on Lax pairs. Moreover, with the symmetry transformations we obtain the Lie point symmetries of the CDGKS equation, and reduce the equation with the obtained symmetries. As a result, three independent reductions are presented and some group-invariant solutions of the equation are given.

  16. Determining Symmetry Properties of Gravitational Fields of Terrestrial Group Planets

    Directory of Open Access Journals (Sweden)

    R.A. Kascheev

    2016-09-01

    Full Text Available Numerous models of gravity fields of the Solar system bodies have been constructed recently owing to successful space missions. These models are sets of harmonic coefficients of gravity potential expansion in series of spherical functions, which is Laplace series. The sets of coefficients are different in quantity of numerical parameters, sources and composition of the initial observational data, methods to obtain and process them, and, consequently, in a variety of properties and accuracy characteristics. For this reason, the task of comparison of different models of celestial bodies considered in the paper is of interest and relevant. The main purpose of this study is comparison of the models of gravitational potential of the Earth, Moon, Mars, and Venus with the quantitative criteria of different types of symmetries developed by us. It is assumed that some particular symmetry of the density distribution function of the planetary body causes similar symmetry of its gravitational potential. The symmetry of gravitational potential, in its turn, imposes additional conditions (restrictions, which must be satisfied by the harmonic coefficients. The paper deals with seven main types of symmetries: central, axial, two symmetries specular relative to the equatorial planes and prime meridian, as well as three rotational symmetries (at π angle around the coordinate system axes. According to the results of calculations carried out for the Earth, Moon, Mars, and Venus, the values of the criteria vary considerably for different types of symmetries and for different planets. It means that the specific value of each criterion corresponding to a particular celestial body is indicative of the properties and internal structure characteristics of the latter and, therefore, it can be used as a tool for comparative planetology. On the basis of the performed calculations, it is possible to distinguish two groups of celestial bodies having similar properties of

  17. Renormalisation group improved leptogenesis in family symmetry models

    International Nuclear Information System (INIS)

    Cooper, Iain K.; King, Stephen F.; Luhn, Christoph

    2012-01-01

    We study renormalisation group (RG) corrections relevant for leptogenesis in the case of family symmetry models such as the Altarelli-Feruglio A 4 model of tri-bimaximal lepton mixing or its extension to tri-maximal mixing. Such corrections are particularly relevant since in large classes of family symmetry models, to leading order, the CP violating parameters of leptogenesis would be identically zero at the family symmetry breaking scale, due to the form dominance property. We find that RG corrections violate form dominance and enable such models to yield viable leptogenesis at the scale of right-handed neutrino masses. More generally, the results of this paper show that RG corrections to leptogenesis cannot be ignored for any family symmetry model involving sizeable neutrino and τ Yukawa couplings.

  18. Architects of symmetry in finite nonabelian groups

    Czech Academy of Sciences Publication Activity Database

    Křížek, Michal; Somer, L.

    2010-01-01

    Roč. 21, č. 4 (2010), s. 307-319 ISSN 0865-4824 R&D Projects: GA AV ČR(CZ) IAA100190803 Institutional research plan: CEZ:AV0Z10190503 Keywords : Abel Prize * sporadic groups * monster Subject RIV: BA - General Mathematics

  19. Gauging the graded conformal group with unitary internal symmetries

    International Nuclear Information System (INIS)

    Ferrara, S.; Townsend, P.K.; Kaku, M.; Nieuwenhuizen Van, P.

    1977-06-01

    Gauge theories for extended SU(N) conformal supergravity are constructed which are invariant under local scale, chiral, proper conformal, supersymmetry and internal SU(N) transformations. The relation between intrinsic parity and symmetry properties of their generators of the internal vector mesons is established. These theories contain no cosmological constants, but technical problems inherent to higher derivative actions are pointed out

  20. Space-Group Symmetries Generate Chaotic Fluid Advection in Crystalline Granular Media

    Science.gov (United States)

    Turuban, R.; Lester, D. R.; Le Borgne, T.; Méheust, Y.

    2018-01-01

    The classical connection between symmetry breaking and the onset of chaos in dynamical systems harks back to the seminal theory of Noether [Transp. Theory Statist. Phys. 1, 186 (1918), 10.1080/00411457108231446]. We study the Lagrangian kinematics of steady 3D Stokes flow through simple cubic and body-centered cubic (bcc) crystalline lattices of close-packed spheres, and uncover an important exception. While breaking of point-group symmetries is a necessary condition for chaotic mixing in both lattices, a further space-group (glide) symmetry of the bcc lattice generates a transition from globally regular to globally chaotic dynamics. This finding provides new insights into chaotic mixing in porous media and has significant implications for understanding the impact of symmetries upon generic dynamical systems.

  1. Lie point symmetries and reductions of one-dimensional equations describing perfect Korteweg-type nematic fluids

    Science.gov (United States)

    De Matteis, Giovanni; Martina, Luigi

    2012-03-01

    A system of partial differential equations, describing one-dimensional nematic liquid crystals is studied by Lie group analysis. These equations are the Euler-Lagrange equations associated with a free energy functional that depends on the mass density and the gradient of the mass density. The group analysis is an algorithmic approach that allows us to show all the point symmetries of the system, to determine all possible symmetry reductions and, finally, to obtain invariant solutions in the form of travelling waves. The Hamiltonian formulation of the dynamical equations is also considered and the conservation laws found by exploiting the local symmetries.

  2. Computing the Symmetry Groups of the Platonic Solids With the ...

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 9; Issue 8. Computing the Symmetry Groups of the Platonic Solids With the Help of Maple. Patrick J Morandi. General Article Volume 9 Issue 8 August 2004 pp 18-26. Fulltext. Click here to view fulltext PDF. Permanent link:

  3. The Emergence of Dirac points in Photonic Crystals with Mirror Symmetry

    Science.gov (United States)

    He, Wen-Yu; Chan, C. T.

    2015-01-01

    We show that Dirac points can emerge in photonic crystals possessing mirror symmetry when band gap closes. The mechanism of generating Dirac points is discussed in a two-dimensional photonic square lattice, in which four Dirac points split out naturally after the touching of two bands with different parity. The emergence of such nodal points, characterized by vortex structure in momentum space, is attributed to the unavoidable band crossing protected by mirror symmetry. The Dirac nodes can be unbuckled through breaking the mirror symmetry and a photonic analog of Chern insulator can be achieved through time reversal symmetry breaking. Breaking time reversal symmetry can lead to unidirectional helical edge states and breaking mirror symmetry can reduce the band gap to amplify the finite size effect, providing ways to engineer helical edge states. PMID:25640993

  4. Measure of departure from marginal point-symmetry for two-way contingency tables

    Directory of Open Access Journals (Sweden)

    Kouji Yamamoto

    2013-05-01

    Full Text Available For two-way contingency tables, Tomizawa (1985 considered the point-symmetry and marginal point-symmetry models, and Tomizawa, Yamamoto and Tahata (2007 proposed a measure to represent the degree of departure from point-symmetry. The present paper proposes a measure to represent the degree of departure from marginal pointsymmetry for two-way tables. The proposed measure is expressed by using Cressie-Read power-divergence or Patil-Taillie diversity index. This measure would be useful for comparing the degrees of departure from marginal point-symmetry in several tables. The relationship between the degree of departure from marginal point-symmetry and the measure is shown when it is reasonable to assume underlying bivariate normal distribution. Examples are shown.

  5. The analysis of crystallographic symmetry types in finite groups

    Science.gov (United States)

    Sani, Atikah Mohd; Sarmin, Nor Haniza; Adam, Nooraishikin; Zamri, Siti Norziahidayu Amzee

    2014-06-01

    Undeniably, it is human nature to prefer objects which are considered beautiful. Most consider beautiful as perfection, hence they try to create objects which are perfectly balance in shape and patterns. This creates a whole different kind of art, the kind that requires an object to be symmetrical. This leads to the study of symmetrical objects and pattern. Even mathematicians and ethnomathematicians are very interested with the essence of symmetry. One of these studies were conducted on the Malay traditional triaxial weaving culture. The patterns derived from this technique are symmetrical and this allows for further research. In this paper, the 17 symmetry types in a plane, known as the wallpaper groups, are studied and discussed. The wallpaper groups will then be applied to the triaxial patterns of food cover in Malaysia.

  6. Bogolyubov renormalization group and symmetry of solution in mathematical physics

    International Nuclear Information System (INIS)

    Shirkov, D.V.; Kovalev, V.F.

    2000-01-01

    Evolution of the concept known in the theoretical physics as the Renormalization Group (RG) is presented. The corresponding symmetry, that has been first introduced in QFT in mid-fifties, is a continuous symmetry of a solution with respect to transformation involving parameters (e.g., of boundary condition) specifying some particular solution. After short detour into Wilson's discrete semi-group, we follow the expansion of QFT RG and argue that the underlying transformation, being considered as a reparametrization one, is closely related to the self-similarity property. It can be treated as its generalization, the Functional Self-similarity (FS). Then, we review the essential progress during the last decade of the FS concept in application to boundary value problem formulated in terms of differential equations. A summary of a regular approach recently devised for discovering the RG = FS symmetries with the help of the modern Lie group analysis and some of its applications are given. As a main physical illustration, we give application of a new approach to solution for a problem of self-focusing laser beam in a nonlinear medium

  7. Thermal conductivity of the accidental degeneracy and enlarged symmetry group models for superconducting UPt3

    International Nuclear Information System (INIS)

    Graf, M.J.; Los Alamos National Lab., NM; Yip, S.K.; Sauls, J.A.

    1999-01-01

    The authors present theoretical calculations of the thermal conductivity for the accidental degeneracy and enlarged symmetry group models that have been proposed to explain the phase diagram of UPt 3 . The order parameters for these models possess point nodes or cross nodes, reflecting the broken symmetries of the ground state. These broken symmetries lead to robust predictions for the ratio of the low-temperature thermal conductivity for heat flow along the c axis and in the basal plane. The anisotropy of the heat current response at low temperatures is determined by the phase space for scattering by impurities. The measured anisotropy ratio, κ c /κ b , provides a strong constraint on theoretical models for the ground state order parameter. The accidental degeneracy and enlarged symmetry group models based on no spin-orbit coupling do not account for the thermal conductivity of UPt 3 . The models for the order parameter that fit the experimental data for the c and b directions of the heat current are the 2D E 1g and E 2u models, for which the order parameters possess line nodes in the ab-plane and point nodes along the c axis, and the A 1g circle-plus E 1g model of Zhitomirsky and Ueda. This model spontaneously breaks rotational symmetry in the ab-plane below T c2 and predicts a large anisotropy for the ab-plane heat current

  8. Symmetry in chemistry

    CERN Document Server

    Jaffé, Hans H

    1977-01-01

    This book, devoted exclusively to symmetry in chemistry and developed in an essentially nonmathematical way, is a must for students and researchers. Topics include symmetry elements and operations, multiple symmetry operations, multiplication tables and point groups, group theory applications, and crystal symmetry. Extensive appendices provide useful tables.

  9. Group quantization on configuration space: Gauge symmetries and linear fields

    International Nuclear Information System (INIS)

    Navarro, M.; Aldaya, V.; Calixto, M.

    1997-01-01

    A new, configuration-space picture of a formalism of group quantization, the GAQ formalism, is presented in the context of a previous algebraic generalization. This presentation serves to make a comprehensive discussion in which other extensions of the formalism, principally to incorporate gauge symmetries, are developed as well. Both images are combined in order to analyze, in a systematic manner and with complete generality, the case of linear fields (Abelian current groups). To illustrate these developments we particularize them for several fields and, in particular, we carry out the quantization of the Abelian Chern endash Simons models over an arbitrary closed surface in detail. copyright 1997 American Institute of Physics

  10. arXiv Radiative symmetry breaking from interacting UV fixed points

    CERN Document Server

    Abel, Steven

    2017-09-28

    It is shown that the addition of positive mass-squared terms to asymptotically safe gauge-Yukawa theories with perturbative UV fixed points leads to calculable radiative symmetry breaking in the IR. This phenomenon, and the multiplicative running of the operators that lies behind it, is akin to the radiative symmetry breaking that occurs in the supersymmetric standard model.

  11. New Insights into Viral Architecture via Affine Extended Symmetry Groups

    Directory of Open Access Journals (Sweden)

    T. Keef

    2008-01-01

    Full Text Available Since the seminal work of Caspar and Klug on the structure of the protein containers that encapsulate and hence protect the viral genome, it has been recognized that icosahedral symmetry is crucial for the structural organization of viruses. In particular, icosahedral symmetry has been invoked in order to predict the surface structures of viral capsids in terms of tessellations or tilings that schematically encode the locations of the protein subunits in the capsids. Whilst this approach is capable of predicting the relative locations of the proteins in the capsids, a prediction on the relative sizes of different virus particles in a family cannot be made. Moreover, information on the full 3D structure of viral particles, including the tertiary structures of the capsid proteins and the organization of the viral genome within the capsid are inaccessible with their approach. We develop here a mathematical framework based on affine extensions of the icosahedral group that allows us to address these issues. In particular, we show that the relative radii of viruses in the family of Polyomaviridae and the material boundaries in simple RNA viruses can be determined with our approach. The results complement Caspar and Klug's theory of quasi-equivalence and provide details on virus structure that have not been accessible with previous methods, implying that icosahedral symmetry is more important for virus architecture than previously appreciated.

  12. Structure of Lie point and variational symmetry algebras for a class of odes

    Science.gov (United States)

    Ndogmo, J. C.

    2018-04-01

    It is known for scalar ordinary differential equations, and for systems of ordinary differential equations of order not higher than the third, that their Lie point symmetry algebras is of maximal dimension if and only if they can be reduced by a point transformation to the trivial equation y(n)=0. For arbitrary systems of ordinary differential equations of order n ≥ 3 reducible by point transformations to the trivial equation, we determine the complete structure of their Lie point symmetry algebras as well as that for their variational, and their divergence symmetry algebras. As a corollary, we obtain the maximal dimension of the Lie point symmetry algebra for any system of linear or nonlinear ordinary differential equations.

  13. The abstract GPT and GCPT groups of discrete C, P and T symmetries

    Science.gov (United States)

    Lazzeretti, Paolo

    2017-07-01

    Essential symmetry properties of physical quantities of classical mechanics and classical electromagnetism can be rationalized via the Abelian symmetry group GPT , with four operations (identity E, space inversion P, time reversal T, and combined PT) isomorphic to the spatial C2v point group. To account for charge conjugation C, a larger discrete group, GCPT , with eight operations (E, P, T, C , and their products, CP, CT, PT , and CPT), isomorphic to the spatial D2h point group, has been considered. Some features of these groups are discussed by a few examples, showing in particular that they provide group-theoretical implications for the existence of magnetic monopoles, magnetic scalar potential, magnetic charge density and magnetic current density, and magnetic-field induced electronic anapoles. A set of linearly independent vectors belonging to a representation space is constituted by eight fermion bilinears of quantum field theory. The GCPT group can be used to determine the discrete symmetry properties of molecular response tensors and provides interesting elucidations of established notions in a different, group-theoretical light, e.g., new understanding of duality transformations, which leave the Maxwell equations invariant, and a geometrical reinterpretation of Barron's concept of true enantiomers.

  14. Partial Symmetry Breaking by Local Search in the Group

    NARCIS (Netherlands)

    Prestwich, S.; Hnich, B.; Simonis, H.; Rossi, R.; Tarim, S.A.

    2012-01-01

    The presence of symmetry in constraint satisfaction problems can cause a great deal of wasted search effort, and several methods for breaking symmetries have been reported. In this paper we describe a new method called Symmetry Breaking by Nonstationary Optimisation, which interleaves local search

  15. The Poincare group as the symmetry group of canonical general relativity

    International Nuclear Information System (INIS)

    Beig, R.; Murchadha, N. o

    1986-01-01

    This work reconsiders the formulation, due to Regge and Teitelboim, of the phase space approach to General Relativity in the asymptotically flat context, phrasing it in the language of symplectic geometry. The necessary boundary conditions at spatial infinity are spelled out in detail. Precise meaning is given to the statement that, as a result of these boundary conditions, the Poincare group acts as a symmetry group on the phase space of G.R. This situation is compared with the spi-picture of Ashtekar and Hansen, where a larger asymptotic symmetry group is obtained. (Author)

  16. Duality, Gauge Symmetries, Renormalization Groups and the BKT Transition

    Science.gov (United States)

    José, Jorge V.

    2017-03-01

    In this chapter, I will briefly review, from my own perspective, the situation within theoretical physics at the beginning of the 1970s, and the advances that played an important role in providing a solid theoretical and experimental foundation for the Berezinskii-Kosterlitz-Thouless theory (BKT). Over this period, it became clear that the Abelian gauge symmetry of the 2D-XY model had to be preserved to get the right phase structure of the model. In previous analyses, this symmetry was broken when using low order calculational approximations. Duality transformations at that time for two-dimensional models with compact gauge symmetries were introduced by José, Kadanoff, Nelson and Kirkpatrick (JKKN). Their goal was to analyze the phase structure and excitations of XY and related models, including symmetry breaking fields which are experimentally important. In a separate context, Migdal had earlier developed an approximate Renormalization Group (RG) algorithm to implement Wilson’s RG for lattice gauge theories. Although Migdal’s RG approach, later extended by Kadanoff, did not produce a true phase transition for the XY model, it almost did asymptotically in terms of a non-perturbative expansion in the coupling constant with an essential singularity. Using these advances, including work done on instantons (vortices), JKKN analyzed the behavior of the spin-spin correlation functions of the 2D XY-model in terms of an expansion in temperature and vortex-pair fugacity. Their analysis led to a perturbative derivation of RG equations for the XY model which are the same as those first derived by Kosterlitz for the two-dimensional Coulomb gas. JKKN’s results gave a theoretical formulation foundation and justification for BKT’s sound physical assumptions and for the validity of their calculational approximations that were, in principle, strictly valid only at very low temperatures, away from the critical TBKT temperature. The theoretical predictions were soon tested

  17. Shape/Phase Transitions and Critical Point Symmetries in Atomic Nuclei

    OpenAIRE

    Bonatsos, Dennis

    2008-01-01

    Shape/phase transitions in atomic nuclei have first been discovered in the framework of the Interacting Boson Approximation (IBA) model. Critical point symmetries appropriate for nuclei at the transition points have been introduced as special solutions of the Bohr Hamiltonian, stirring the introduction of additional new solutions describing wide ranges of nuclei. A short review of these recent developments will be attempted.

  18. EXECUTIVE SUMMARY OF THE SNOWMASS 2001 WORKING GROUP : ELECTROWEAK SYMMETRY BREAKING

    International Nuclear Information System (INIS)

    CARENA, M.; GERDES, D.W.; HABER, H.E.; TURCOT, A.S.; ZERWAS, P.M.

    2001-01-01

    In this summary report of the 2001 Snowmass Electroweak Symmetry Breaking Working Group, the main candidates for theories of electroweak symmetry breaking are surveyed, and the criteria for distinguishing among the different approaches are discussed. The potential for observing electroweak symmetry breaking phenomena at the upgraded Tevatron and the LHC is described. We emphasize the importance of a high-luminosity e + e - linear collider for precision measurements to clarify the underlying electroweak symmetry breaking dynamics. Finally, we note the possible roles of the μ + μ - collider and VLHC for further elucidating the physics of electroweak symmetry breaking

  19. Strong Coupling of a Quantum Oscillator to a Flux Qubit at Its Symmetry Point

    NARCIS (Netherlands)

    Fedorov, A.; Feofanov, A.K.; Macha, P.; Forn-Díaz, P.; Harmans, C.J.P.M.; Mooij, J.E.

    2010-01-01

    A flux qubit biased at its symmetry point shows a minimum in the energy splitting (the gap), providing protection against flux noise. We have fabricated a qubit of which the gap can be tuned fast and have coupled this qubit strongly to an LC oscillator. We show full spectroscopy of the

  20. Towards a non-abelian electric-magnetic symmetry: the skeleton group

    NARCIS (Netherlands)

    Kampmeijer, L.; Bais, F.A.; Schroers, B.J.; Slingerland, J.K.

    2010-01-01

    We propose an electric-magnetic symmetry group in non-abelian gauge theory, which we call the skeleton group. We work in the context of non-abelian unbroken gauge symmetry, and provide evidence for our proposal by relating the representation theory of the skeleton group to the labelling and fusion

  1. Entanglement Properties of a Higher-Integer-Spin AKLT Model with Quantum Group Symmetry

    Directory of Open Access Journals (Sweden)

    Chikashi Arita

    2012-10-01

    Full Text Available We study the entanglement properties of a higher-integer-spin Affleck-Kennedy-Lieb-Tasaki model with quantum group symmetry in the periodic boundary condition. We exactly calculate the finite size correction terms of the entanglement entropies from the double scaling limit. We also evaluate the geometric entanglement, which serves as another measure for entanglement. We find the geometric entanglement reaches its maximum at the isotropic point, and decreases with the increase of the anisotropy. This behavior is similar to that of the entanglement entropies.

  2. On the Lie point symmetry analysis and solutions of the inviscid ...

    Indian Academy of Sciences (India)

    (Springer, New York, 2002). [7] P J Olver, Application of Lie groups to differential equations (Springer, New York, 1993). [8] N H Ibragimov, CRC handbook of Lie group analysis of differential equations, Volume 1,. Symmetries, exact solutions and conservation laws (CRC Press, Boca Raton, 1994). 414. Pramana – J. Phys.

  3. Lie Point Symmetries and Exact Solutions of the Coupled Volterra System

    International Nuclear Information System (INIS)

    Ping, Liu; Sen-Yue, Lou

    2010-01-01

    The coupled Volterra system, an integrable discrete form of a coupled Korteweg–de Vries (KdV) system applied widely in fluids, Bose–Einstein condensation and atmospheric dynamics, is studied with the help of the Lie point symmetries. Two types of delayed differential reduction systems are derived from the coupled Volterra system by means of the symmetry reduction approach and symbolic computation. Cnoidal wave and solitary wave solutions for a delayed differential reduction system and the coupled Volterra system are proposed, respectively. (general)

  4. Fixed point algebras for easy quantum groups

    DEFF Research Database (Denmark)

    Gabriel, Olivier; Weber, Moritz

    2016-01-01

    Compact matrix quantum groups act naturally on Cuntz algebras. The first author isolated certain conditions under which the fixed point algebras under this action are Kirchberg algebras. Hence they are completely determined by their K-groups. Building on prior work by the second author,we prove...... that free easy quantum groups satisfy these conditions and we compute the K-groups of their fixed point algebras in a general form. We then turn to examples such as the quantum permutation group S+ n,the free orthogonal quantum group O+ n and the quantum reflection groups Hs+ n. Our fixed point......-algebra construction provides concrete examples of free actions of free orthogonal easy quantum groups,which are related to Hopf-Galois extensions....

  5. Jacobi–Lie symmetry and Jacobi–Lie T-dual sigma models on group manifolds

    Directory of Open Access Journals (Sweden)

    A. Rezaei-Aghdam

    2018-01-01

    Full Text Available Using the concept of Jacobi–Lie group and Jacobi–Lie bialgebra, we generalize the definition of Poisson–Lie symmetry to Jacobi–Lie symmetry. In this regard, we generalize the concept of Poisson–Lie T-duality to Jacobi–Lie T-duality and present Jacobi–Lie T-dual sigma models on Lie groups, which have Jacobi–Lie symmetry. Using this symmetry, new cases of duality appear and some examples are given. This generalization may provide insights to understand the quantum features of Poisson–Lie T-duality, in a more satisfactory way.

  6. Point groups in the Vibron model

    Energy Technology Data Exchange (ETDEWEB)

    Leviatan, A.

    1989-08-01

    The question of incorporating the notion of point groups in the algebraic Vibron model for molecular rotation--vibration spectra is addressed. Boson transformations which act on intrinsic states are identified as the algebraic analog of the discrete point group transformations. A prescription for assigning point group labels to states of the Vibron model is obtained. In case of nonlinear triatomic molecules the Jacobi coordinates are found to be a convenient possible choice for the geometric counterparts of the algebraic shape parameters. The work focuses on rigid diatomic and triatomic molecules (linear and bent).

  7. On the dynamical symmetry points and the orientations of the principal axes of inertia of a rigid body

    NARCIS (Netherlands)

    Amel'kin, N. I.

    For an arbitrary rigid body, all dynamical symmetry points are found, and the directions of the axes of dynamical symmetry are determined for these points. We obtain conditions on the principal central moments of inertia under which the Lagrange and Kovalevskaya cases can be realized for the rigid

  8. Statistical symmetry restoration in fully developed turbulence: Renormalization group analysis of two models

    Science.gov (United States)

    Antonov, N. V.; Gulitskiy, N. M.; Kostenko, M. M.; Malyshev, A. V.

    2018-03-01

    In this paper we consider the model of incompressible fluid described by the stochastic Navier-Stokes equation with finite correlation time of a random force. Inertial-range asymptotic behavior of fully developed turbulence is studied by means of the field theoretic renormalization group within the one-loop approximation. It is corroborated that regardless of the values of model parameters and initial data the inertial-range behavior of the model is described by the limiting case of vanishing correlation time. This indicates that the Galilean symmetry of the model violated by the "colored" random force is restored in the inertial range. This regime corresponds to the only nontrivial fixed point of the renormalization group equation. The stability of this point depends on the relation between the exponents in the energy spectrum E ∝k1 -y and the dispersion law ω ∝k2 -η . The second analyzed problem is the passive advection of a scalar field by this velocity ensemble. Correlation functions of the scalar field exhibit anomalous scaling behavior in the inertial-convective range. We demonstrate that in accordance with Kolmogorov's hypothesis of the local symmetry restoration the main contribution to the operator product expansion is given by the isotropic operator, while anisotropic terms should be considered only as corrections.

  9. Extreme covariant quantum observables in the case of an Abelian symmetry group and a transitive value space

    International Nuclear Information System (INIS)

    Haapasalo, Erkka Theodor; Pellonpaeae, Juha-Pekka

    2011-01-01

    We represent quantum observables as normalized positive operator valued measures and consider convex sets of observables which are covariant with respect to a unitary representation of a locally compact Abelian symmetry group G. The value space of such observables is a transitive G-space. We characterize the extreme points of covariant observables and also determine the covariant extreme points of the larger set of all quantum observables. The results are applied to position, position difference, and time observables.

  10. Fixed points in a group of isometries

    NARCIS (Netherlands)

    Voorneveld, M.

    2000-01-01

    The Bruhat-Tits xed point theorem states that a group of isometries on a complete metric space with negative curvature possesses a xed point if it has a bounded orbit. This theorem is extended by a relaxation of the negative curvature condition in terms of the w-distance functions introduced by Kada

  11. Variational Principles, Lie Point Symmetries, and Similarity Solutions of the Vector Maxwell Equations in Non-linear Optics

    DEFF Research Database (Denmark)

    Webb, Garry; Sørensen, Mads Peter; Brio, Moysey

    2004-01-01

    to circumvent this problem, non-canonical Poisson bracket formulations of the equations are obtained in which the electric field is one of the non-canonical variables. Noether's theorem, and the Lie point symmetries admitted by the equations are used to obtain four conservation laws, including......The vector Maxwell equations of nonlinear optics coupled to a single Lorentz oscillator and with instantaneous Kerr nonlinearity are investigated by using Lie symmetry group methods. Lagrangian and Hamiltonian formulations of the equations are obtained. The aim of the analysis is to explore...... the properties of Maxwell's equations in nonlinear optics, without resorting to the commonly used nonlinear Schr\\"odinger (NLS) equation approximation in which a high frequency carrier wave is modulated on long length and time scales due to nonlinear sideband wave interactions. This is important in femto...

  12. Fingerprints of bosonic symmetry protected topological state in a quantum point contact

    OpenAIRE

    Zhang, Rui-Xing; Liu, Chao-Xing

    2016-01-01

    In this work, we study the transport through a quantum point contact for bosonic helical liquid that exists at the edge of a bilayer graphene under a strong magnetic field. We identify "smoking gun" transport signatures to distinguish bosonic symmetry protected topological (BSPT) state from fermionic two-channel quantum spin Hall (QSH) state in this system. In particular, a novel charge insulator/spin conductor phase is found for BSPT state, while either charge insulator/spin insulator or cha...

  13. Hierarchy of kissing numbers for exceptional Lie symmetry groups in high energy physics

    International Nuclear Information System (INIS)

    El Naschie, M.S.

    2008-01-01

    We are constructing a hierarchy of kissing numbers representing singular contact points of hyper-spheres in exceptional Lie symmetry groups lattice arrangement embedded in the 26 dimensional bosonic strings spacetime. That way we find a total number of points and dimensions equal to 548. This is 52 more than the order of E 8 E 8 of heterotic string theory and leads to the prediction of 69 elementary particles at an energy scale under 1 T. In other words, our mathematical model predicts nine more particles than what is currently experimentally known to exist in the standard model of high energy physics namely only 60. The result is thus in full agreement with all our previous theoretical findings

  14. Additivity of Feature-based and Symmetry-based Grouping Effects in Multiple Object Tracking

    Directory of Open Access Journals (Sweden)

    Chundi eWang

    2016-05-01

    Full Text Available Multiple object tracking (MOT is an attentional process wherein people track several moving targets among several distractors. Symmetry, an important indicator of regularity, is a general spatial pattern observed in natural and artificial scenes. According to the laws of perceptual organization proposed by Gestalt psychologists, regularity is a principle of perceptual grouping, such as similarity and closure. A great deal of research reported that feature-based similarity grouping (e.g., grouping based on color, size, or shape among targets in MOT tasks can improve tracking performance. However, no additive feature-based grouping effects have been reported where the tracking objects had two or more features. Additive effect refers to a greater grouping effect produced by grouping based on multiple cues instead of one cue. Can spatial symmetry produce a similar grouping effect similar to that of feature similarity in MOT tasks? Are the grouping effects based on symmetry and feature similarity additive? This study includes four experiments to address these questions. The results of Experiments 1 and 2 demonstrated the automatic symmetry-based grouping effects. More importantly, an additive grouping effect of symmetry and feature similarity was observed in Experiments 3 and 4. Our findings indicate that symmetry can produce an enhanced grouping effect in MOT and facilitate the grouping effect based on color or shape similarity. The where and what pathways might have played an important role in the additive grouping effect.

  15. Hypersurfaces in Pn with 1-parameter symmetry groups II

    DEFF Research Database (Denmark)

    Plessis, Andrew du; Wall, C.T.C.

    2010-01-01

    We assume V a hypersurface of degree d in with isolated singularities and not a cone, admitting a group G of linear symmetries. In earlier work we treated the case when G is semi-simple; here we analyse the unipotent case. Our first main result lists the possible groups G. In each case we discuss...... the geometry of the action, reduce V to a normal form, find the singular points, study their nature, and calculate the Milnor numbers. The Tjurina number τ(V) ≤ (d − 1) n–2(d 2 − 3d + 3): we call V oversymmetric if this value is attained. We calculate τ in many cases, and characterise the oversymmetric...

  16. Quantum group symmetry of classical and noncommutative geometry

    Indian Academy of Sciences (India)

    Debashish Goswami

    2016-07-01

    Jul 1, 2016 ... groups (Hopf algebras) by 'deforming' the algebraic relations of U(L) for Lie algebras of compact simple Lie groups. For example, Uq(SL(2))...dually, one has deformed coordinate algebras, e.g. SLq(2) etc. Woronowicz proposed an analytic theory of quantum groups ('compact quantum groups')...then Vaes,.

  17. Symmetries and groups in particle physics; Symmetrien und Gruppen in der Teilchenphysik

    Energy Technology Data Exchange (ETDEWEB)

    Scherer, Stefan [Mainz Univ. (Germany)

    2016-07-01

    The aim of this book consists of a didactic introduction to the group-theoretical considerations and methods, which have led to an ever deeper understanding of the interactions of the elementary particles. The first three chapters deal primarily with the foundations of the representation theory of primarily finite groups, whereby many results are also transferable to compact Lie groups. In the third chapter we discuss the concept of Lie groups and their connection with Lie algebras. In the remaining chapter it is mainly about the application of group theory in physics. Chapter 4 deals with the groups SO(3) and SU(2), which occur in connection with the description of the angular momentum in quantum mechanics. We discuss the Wigner-Eckar theorem together with some applications. In chapter 5 we are employed to the composition properties of strongly interacting systems, so called hadrons, and discuss extensively the transformation properties of quarks with relation to the special unitary groups. The Noether theorem is generally treated in connection to the conservation laws belonging to the Galilei group and the Poincare group. We confine us in chapter 6 to internal symmetries, but explain for that extensively the application to quantum field theory. Especially an outlook on the effect of symmetries in form of so called Ward identities is granted. In chapter 7 we turn towards the gauge principle and discuss first the construction of quantum electrodynamics. In the following we generalize the gauge principle to non-Abelian groups (Yang-Mills theories) and formulate the quantum chromodynamics (QCD). Especially we take a view of ''random'' global symmetries of QCD, especially the chiral symmetry. In chapter 8 we illuminate the phenomenon of spontaneous symmetry breaking both for global and for local symmetries. In the final chapter we work out the group-theoretical structure of the Standard Model. Finally by means of the group SU(5) we take a view to

  18. On the Physical Reasons for the Extension of Symmetry Groups in Molecular Spectroscopy

    Directory of Open Access Journals (Sweden)

    Carlo di Lauro

    2010-02-01

    Full Text Available Several situations of general interest, in which the symmetry groups usually applied to spectroscopy problems need to be extended, are reviewed. It is emphasized that any symmetry group of geometrical operations to be used in Molecular Spectroscopy should be extended for completeness by considering the time reversal operator, as far as the Hamiltonian is invariant with respect to the inversion of the direction of motion. This can explain the degeneracy of pairs of vibrational and rotational states spanning the so-called separably degenerate irreducible representations, in symmetric tops of low symmetry, and Kramers degeneracy in odd electron molecules in the absence of magnetic fields. An extension with account of time reversal is also useful to determine relative phase conventions on vibration-rotation wavefunctions, which render all vibration-rotation matrix elements real. An extension of a molecular symmetry group may be required for molecules which can attain different geometries by large amplitude periodical motions, if such motions are hindered and are not completely free. Special cases involving the internal rotation are discussed in detail. It is observed that the symmetry classification of vibrational modes involving displacements normal to the internal rotation axis is not univocal, but can be done in several ways, which actually correspond to different conventions on the separation of vibration and internal rotation in the adopted basis functions. The symmetry species of the separate vibrational and torsional factors of these functions depend on the adopted convention.

  19. sl (6,r) as the group of symmetries for non relativistic quantum systems

    African Journals Online (AJOL)

    It is shown that the 13 one parameter generators of the Lie group SL(6, R) are the maximal group of symmetries for nonrelativistic quantum systems. The group action on the set of states S Ĥ (H complex Hilbert space) preserves transition probabilities as well as the dynamics of the system. By considering a prolongation of ...

  20. Symmetry group and group representations associated with the thermodynamic covariance principle.

    Science.gov (United States)

    Sonnino, Giorgio; Evslin, Jarah; Sonnino, Alberto; Steinbrecher, György; Tirapegui, Enrique

    2016-10-01

    The main objective of this work [previously appeared in literature, the thermodynamical field theory (TFT)] is to determine the nonlinear closure equations (i.e., the flux-force relations) valid for thermodynamic systems out of Onsager's region. The TFT rests upon the concept of equivalence between thermodynamic systems. More precisely, the equivalent character of two alternative descriptions of a thermodynamic system is ensured if, and only if, the two sets of thermodynamic forces are linked with each other by the so-called thermodynamic coordinate transformations (TCT). In this work, we describe the Lie group and the group representations associated to the TCT. The TCT guarantee the validity of the so-called thermodynamic covariance principle (TCP): The nonlinear closure equations, i.e., the flux-force relations, everywhere and in particular outside the Onsager region, must be covariant under TCT. In other terms, the fundamental laws of thermodynamics should be manifestly covariant under transformations between the admissible thermodynamic forces, i.e., under TCT. The TCP ensures the validity of the fundamental theorems for systems far from equilibrium. The symmetry properties of a physical system are intimately related to the conservation laws characterizing that system. Noether's theorem gives a precise description of this relation. We derive the conserved (thermodynamic) currents and, as an example of calculation, a system out of equilibrium (tokamak plasmas) where the validity of TCP imposed at the level of the kinetic equations is also analyzed.

  1. Full Symmetry Groups and Similar Reductions of a (2+1)-Dimensional Resonant Davey—Stewartson System

    Science.gov (United States)

    Hu, Xiao-Rui; Chen, Yong; Qian, Long-Jiang

    2011-05-01

    Applying the classical Lie symmetry method to the (2+1)-dimensional resonant Davey—Stewartson system introduced by Tang [X.Y. Tang et al., Chaos, Solitons and Fractals 42 (2007) 2707], a more general infinite dimensional Lie symmetry with Kac-Moody-Virasoro type Lie algebra is obtained, which involves four arbitrary functions of t. Alternatively, by a simple direct method, the full symmetry groups including Lie symmetry group and non-Lie symmetry group are gained straightly. In this way, the related Lie algebra can be easily found by a more simple limiting procedure. Lastly, via solving the characteristic equations, three types of the general similar reductions are derived.

  2. Symmetry group application for the (3+1)-dimensional Rossby waves

    Energy Technology Data Exchange (ETDEWEB)

    Kudryavtsev, A.G., E-mail: kudryavtsev_a_g@mail.r [Institute of Applied Mechanics, Russian Academy of Sciences, Moscow 119991 (Russian Federation); Myagkov, N.N., E-mail: NN_Myagkov@mail.r [Institute of Applied Mechanics, Russian Academy of Sciences, Moscow 119991 (Russian Federation)

    2011-01-17

    The (3+1)-dimensional nonlinear Charney-Obukhov equation is analyzed by means of the classical Lie group approach. The classical Lie symmetry group calculated allows one to obtain new exact Rossby wave solutions when a particular Rossby wave solution is known. New solutions obtained assist in the understanding how the Rossby waves change when the background wind changes.

  3. Nonsymmorphic-symmetry-protected hourglass Dirac loop, nodal line, and Dirac point in bulk and monolayer X3SiTe6 (X = Ta, Nb)

    Science.gov (United States)

    Li, Si; Liu, Ying; Wang, Shan-Shan; Yu, Zhi-Ming; Guan, Shan; Sheng, Xian-Lei; Yao, Yugui; Yang, Shengyuan A.

    2018-01-01

    Nonsymmorphic space group symmetries can generate exotic band crossings in topological metals and semimetals. Here, based on symmetry analysis and first-principles calculations, we reveal rich band-crossing features in the existing layered compounds Ta3SiTe6 and Nb3SiTe6 , enabled by nonsymmorphic symmetries. We show that in the absence of spin-orbit coupling (SOC), these three-dimensional (3D) bulk materials possess accidental Dirac loops and essential fourfold nodal lines. In the presence of SOC, there emerges an hourglass Dirac loop—a fourfold degenerate nodal loop, on which each point is a neck point of an hourglass-type dispersion. We show that this interesting type of band crossing is protected and dictated by the nonsymmorphic space group symmetries and it gives rise to drumheadlike surface states. Furthermore, we also investigate these materials in the monolayer form. We show that these two-dimensional (2D) monolayers host nodal lines in the absence of SOC and the nodal lines transform to essential spin-orbit Dirac points when SOC is included. Our work suggests a realistic material platform for exploring the fascinating physics associated with nonsymmorphic band crossings in both 3D and 2D systems.

  4. Fingerprints of bosonic symmetry protected topological state in a quantum point contact

    Science.gov (United States)

    Zhang, Rui-Xing; Liu, Chao-Xing

    In this work, we study the transport through a quantum point contact for two-channel interacting helical liquids that exist at the edge of a bilayer graphene under a strong magnetic field. We identify ``smoking gun'' transport signatures to distinguish bosonic symmetry protected topological (BSPT) state from fermionic two-channel quantum spin Hall (QSH) state in this system. In particular, a novel charge insulator/spin conductor phase is found for a weak repulsive interaction in the BSPT state, while either charge insulator/spin insulator or charge conductor/spin conductor phase is expected for the two-channel QSH state. In the strong interaction limit, shot noise measurement for the BSPT state is expect to reveal charge-2e instanton tunneling, in comparison with the charge-e tunneling in the two-channel QSH phase.

  5. Fingerprints of a Bosonic Symmetry-Protected Topological State in a Quantum Point Contact

    Science.gov (United States)

    Zhang, Rui-Xing; Liu, Chao-Xing

    2017-05-01

    In this work, we study the transport through a quantum point contact for bosonic helical liquid that exists at the edge of a bilayer graphene under a strong magnetic field. We identify "smoking gun" transport signatures to distinguish a bosonic symmetry-protected topological (BSPT) state from a fermionic two-channel quantum spin Hall (QSH) state in this system. In particular, a novel charge-insulator-spin-conductor phase is found for the BSPT state, while either the charge-insulator-spin-insulator or the charge-conductor-spin-conductor phase is expected for the two-channel QSH state. Consequently, a simple transport measurement will reveal the fingerprint of bosonic topological physics in bilayer graphene systems.

  6. Gauge origin of discrete flavor symmetries in heterotic orbifolds

    Directory of Open Access Journals (Sweden)

    Florian Beye

    2014-09-01

    Full Text Available We show that non-Abelian discrete symmetries in orbifold string models have a gauge origin. This can be understood when looking at the vicinity of a symmetry enhanced point in moduli space. At such an enhanced point, orbifold fixed points are characterized by an enhanced gauge symmetry. This gauge symmetry can be broken to a discrete subgroup by a nontrivial vacuum expectation value of the Kähler modulus T. Using this mechanism it is shown that the Δ(54 non-Abelian discrete symmetry group originates from a SU(3 gauge symmetry, whereas the D4 symmetry group is obtained from a SU(2 gauge symmetry.

  7. Painleve analysis and symmetry group for the coupled Zakharov-Kuznetsov equation

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Heng-Chun, E-mail: hhengchun@163.com [College of Science, University of Shanghai for Science and Technology, Shanghai 200093 (China); Jia, Xiao-Qing; Sang, Ben-Wen [College of Science, University of Shanghai for Science and Technology, Shanghai 200093 (China)

    2011-09-12

    The Painleve property for the coupled Zakharov-Kuznetsov equation is verified with the WTC approach and new exact solutions of bell-type are constructed from standard truncated expansion. A symmetry transformation group theorem is also given out from a simple direct method. -- Highlights: → Painleve property for coupled Zakharov-Kuznetsov system is verified by WTC method. → Symmetry group for coupled ZK system is given out by a simple direct method. → Bell-type solution for coupled ZK system is constructed from standard truncation.

  8. Painleve analysis and symmetry group for the coupled Zakharov-Kuznetsov equation

    International Nuclear Information System (INIS)

    Hu, Heng-Chun; Jia, Xiao-Qing; Sang, Ben-Wen

    2011-01-01

    The Painleve property for the coupled Zakharov-Kuznetsov equation is verified with the WTC approach and new exact solutions of bell-type are constructed from standard truncated expansion. A symmetry transformation group theorem is also given out from a simple direct method. -- Highlights: → Painleve property for coupled Zakharov-Kuznetsov system is verified by WTC method. → Symmetry group for coupled ZK system is given out by a simple direct method. → Bell-type solution for coupled ZK system is constructed from standard truncation.

  9. Similar Symmetries: The Role of Wallpaper Groups in Perceptual Texture Similarity

    Directory of Open Access Journals (Sweden)

    Fraser Halley

    2011-05-01

    Full Text Available Periodic patterns and symmetries are striking visual properties that have been used decoratively around the world throughout human history. Periodic patterns can be mathematically classified into one of 17 different Wallpaper groups, and while computational models have been developed which can extract an image's symmetry group, very little work has been done on how humans perceive these patterns. This study presents the results from a grouping experiment using stimuli from the different wallpaper groups. We find that while different images from the same wallpaper group are perceived as similar to one another, not all groups have the same degree of self-similarity. The similarity relationships between wallpaper groups appear to be dominated by rotations.

  10. Structure of Symmetry Groups via Cartan's Method: Survey of Four Approaches

    Directory of Open Access Journals (Sweden)

    Oleg I. Morozov

    2005-10-01

    Full Text Available In this review article we discuss four recent methods for computing Maurer-Cartan structure equations of symmetry groups of differential equations. Examples include solution of the contact equivalence problem for linear hyperbolic equations and finding a contact transformation between the generalized Hunter-Saxton equation and the Euler-Poisson equation.

  11. On symmetry groups of a 2D nonlinear diffusion equation with source

    Indian Academy of Sciences (India)

    April 2015 physics pp. 543–553. On symmetry groups of a 2D nonlinear diffusion equation with source. RODICA CIMPOIASU. Research Center Frontier in Biology and Astrobiology, University of Craiova, 13 A.I.Cuza,. 200585 Craiova, Romania. E-mail: rodicimp@yahoo.com. MS received 27 November 2013; revised 8 May ...

  12. A fast point-cloud computing method based on spatial symmetry of Fresnel field

    Science.gov (United States)

    Wang, Xiangxiang; Zhang, Kai; Shen, Chuan; Zhu, Wenliang; Wei, Sui

    2017-10-01

    Aiming at the great challenge for Computer Generated Hologram (CGH) duo to the production of high spatial-bandwidth product (SBP) is required in the real-time holographic video display systems. The paper is based on point-cloud method and it takes advantage of the propagating reversibility of Fresnel diffraction in the propagating direction and the fringe pattern of a point source, known as Gabor zone plate has spatial symmetry, so it can be used as a basis for fast calculation of diffraction field in CGH. A fast Fresnel CGH method based on the novel look-up table (N-LUT) method is proposed, the principle fringe patterns (PFPs) at the virtual plane is pre-calculated by the acceleration algorithm and be stored. Secondly, the Fresnel diffraction fringe pattern at dummy plane can be obtained. Finally, the Fresnel propagation from dummy plan to hologram plane. The simulation experiments and optical experiments based on Liquid Crystal On Silicon (LCOS) is setup to demonstrate the validity of the proposed method under the premise of ensuring the quality of 3D reconstruction the method proposed in the paper can be applied to shorten the computational time and improve computational efficiency.

  13. Symmetry Groups for the Decomposition of Reversible Computers, Quantum Computers, and Computers in between

    Directory of Open Access Journals (Sweden)

    Alexis De Vos

    2011-06-01

    Full Text Available Whereas quantum computing circuits follow the symmetries of the unitary Lie group, classical reversible computation circuits follow the symmetries of a finite group, i.e., the symmetric group. We confront the decomposition of an arbitrary classical reversible circuit with w bits and the decomposition of an arbitrary quantum circuit with w qubits. Both decompositions use the control gate as building block, i.e., a circuit transforming only one (qubit, the transformation being controlled by the other w−1 (qubits. We explain why the former circuit can be decomposed into 2w − 1 control gates, whereas the latter circuit needs 2w − 1 control gates. We investigate whether computer circuits, not based on the full unitary group but instead on a subgroup of the unitary group, may be decomposable either into 2w − 1 or into 2w − 1 control gates.

  14. Hidden Uq (sl(2)) Uq (sl(2)) Quantum Group Symmetry in Two Dimensional Gravity

    Science.gov (United States)

    Cremmer, Eugène; Gervais, Jean-Loup; Schnittger, Jens

    1997-02-01

    In a previous paper, the quantum-group-covariant chiral vertex operators in the spin 1/2 representation were shown to act, by braiding with the other covariant primaries, as generators of the well known Uq(sl(2)) quantum group symmetry (for a single screening charge). Here, this structure is transformed to the Bloch wave/Coulomb gas operator basis, thereby establishing for the first time its quantum group symmetry properties. A Uq(sl(2)) otimes Uq(sl(2)) symmetry of a novel type emerges: The two Cartan-generator eigenvalues are specified by the choice of matrix element (Vermamodules); the two Casimir eigenvalues are equal and specified by the Virasoro weight of the vertex operator considered; the co-product is defined with a matching condition dictated by the Hilbert space structure of the operator product. This hidden symmetry possesses a novel Hopf-like structure compatible with these conditions. At roots of unity it gives the right truncation. Its (non-linear) connection with the Uq(sl(2)) previously discussed is disentangled.

  15. Symmetries of nonlinear ordinary differential equations: The ...

    Indian Academy of Sciences (India)

    2015-10-21

    Oct 21, 2015 ... Lie point symmetries; -symmetries; Noether symmetries; contact symmetries; adjoint symmetries; nonlocal symmetries; hidden symmetries; ... 620 024, India; Centre for Nonlinear Science and Engineering, School of Electrical and Electronics Engineering, SASTRA University, Thanjavur 613 401, India ...

  16. Group theoretical classification of broken symmetry states of the two-fold degenerate Hubbard model on a triangular lattice

    International Nuclear Information System (INIS)

    Masago, Akira; Suzuki, Naoshi

    2001-01-01

    By a group theoretical procedure we derive the possible spontaneously broken-symmetry states for the two-fold degenerate Hubbard model on a two-dimensional triangular lattice. For ordering wave vectors corresponding to the points Γ and K in the first BZ we find 22 states which include 16 collinear and six non-collinear states. The collinear states include the usual SDW and CDW states which appear also in the single-band Hubbard model. The non-collinear states include exotic ordering states of orbitals and spins as well as the triangular arrangement of spins

  17. Zitterbewegung and symmetry switching in Klein’s four-group

    Science.gov (United States)

    Chotorlishvili, L.; Zięba, P.; Tralle, I.; Ugulava, A.

    2018-01-01

    Zitterbewegung is the exotic phenomenon associated either with relativistic electron-positron rapid oscillation or to electron-hole transitions in narrow gap semiconductors. In the present work, we enlarge the concept of Zitterbewegung and show that trembling motion may occur due to dramatic changes in the symmetry of the system. In particular, we exploit a paradigmatic model of quantum chaos, the quantum mathematical pendulum (universal Hamiltonian). The symmetry group of this system is Klein’s four-group that possesses three invariant subgroups. The energy spectrum of the system parametrically depends on the height of the potential barrier, and contains degenerate and non-degenerate areas, corresponding to the different symmetry subgroups. Change in the height of the potential barrier switches the symmetry subgroup and leads to trembling motion. We analyzed mean square fluctuations of the velocity operator and observed that trembling is enhanced in highly excited states. We observed a link between the phenomena of trembling motion and the uncertainty relations of noncommutative operators of the system.

  18. Integrability from point symmetries in a family of cosmological Horndeski Lagrangians

    Science.gov (United States)

    Dimakis, N.; Giacomini, Alex; Paliathanasis, Andronikos

    2017-07-01

    For a family of Horndeski theories, formulated in terms of a generalized Galileon model, we study the integrability of the field equations in a Friedmann-Lemaître-Robertson-Walker space-time. We are interested in point transformations which leave invariant the field equations. Noether's theorem is applied to determine the conservation laws for a family of models that belong to the same general class. The cosmological scenarios with or without an extra perfect fluid with constant equation of state parameter are the two important cases of our study. The de Sitter universe and ideal gas solutions are derived by using the invariant functions of the symmetry generators as a demonstration of our result. Furthermore, we discuss the connection of the different models under conformal transformations while we show that when the Horndeski theory reduces to a canonical field the same holds for the conformal equivalent theory. Finally, we discuss how singular solutions provides nonsingular universes in a different frame and vice versa.

  19. Integrability from point symmetries in a family of cosmological Horndeski Lagrangians

    Energy Technology Data Exchange (ETDEWEB)

    Dimakis, N.; Giacomini, Alex [Universidad Austral de Chile, Instituto de Ciencias Fisicas y Matematicas, Valdivia (Chile); Paliathanasis, Andronikos [Universidad Austral de Chile, Instituto de Ciencias Fisicas y Matematicas, Valdivia (Chile); Durban University of Technology, Institute of Systems Science, Durban (South Africa)

    2017-07-15

    For a family of Horndeski theories, formulated in terms of a generalized Galileon model, we study the integrability of the field equations in a Friedmann-Lemaitre-Robertson-Walker space-time. We are interested in point transformations which leave invariant the field equations. Noether's theorem is applied to determine the conservation laws for a family of models that belong to the same general class. The cosmological scenarios with or without an extra perfect fluid with constant equation of state parameter are the two important cases of our study. The de Sitter universe and ideal gas solutions are derived by using the invariant functions of the symmetry generators as a demonstration of our result. Furthermore, we discuss the connection of the different models under conformal transformations while we show that when the Horndeski theory reduces to a canonical field the same holds for the conformal equivalent theory. Finally, we discuss how singular solutions provides nonsingular universes in a different frame and vice versa. (orig.)

  20. Symmetry breaking in fluid dynamics: Lie group reducible motions for real fluids

    International Nuclear Information System (INIS)

    Holm, D.D.

    1976-07-01

    The physics of fluids is based on certain kinematical invariance principles, which refer to coordinate systems, dimensions, and Galilean reference frames. Other, thermodynamic, symmetry principles are introduced by the material description. In the present work, the interplay between these two kinds of invariance principles is used to solve for classes of one-dimensional non-steady isentropic motions of a fluid whose equation of state is of Mie-Gruneisen type. Also, the change in profile and attenuation of weak shock waves in a dissipative medium is studied at the level of Burgers' approximation from the viewpoint of its underlying symmetry structure. The mathematical method of approach is based on the theory of infinitesimal Lie groups. Fluid motions are characterized according to inequivalent subgroups of the full invariance group of the flow description and exact group reducible solutions are presented

  1. Symmetry breaking in fluid dynamics: Lie group reducible motions for real fluids

    Energy Technology Data Exchange (ETDEWEB)

    Holm, D.D.

    1976-07-01

    The physics of fluids is based on certain kinematical invariance principles, which refer to coordinate systems, dimensions, and Galilean reference frames. Other, thermodynamic, symmetry principles are introduced by the material description. In the present work, the interplay between these two kinds of invariance principles is used to solve for classes of one-dimensional non-steady isentropic motions of a fluid whose equation of state is of Mie-Gruneisen type. Also, the change in profile and attenuation of weak shock waves in a dissipative medium is studied at the level of Burgers' approximation from the viewpoint of its underlying symmetry structure. The mathematical method of approach is based on the theory of infinitesimal Lie groups. Fluid motions are characterized according to inequivalent subgroups of the full invariance group of the flow description and exact group reducible solutions are presented.

  2. Generation of symmetry coordinates for crystals using multiplier representations of the space groups

    DEFF Research Database (Denmark)

    Hansen, Flemming Yssing

    1978-01-01

    Symmetry coordinates play an important role in the normal-mode calculations of crystals. It is therefore of great importance to have a general method, which may be applied for any crystal at any wave vector, to generate these. The multiplier representations of the space groups as given by Kovalev...... and the projection-operator technique provide a basis for such a method. The method is illustrated for the nonsymmorphic D36 space group, and the theoretical background for the representations of space groups in general is reviewed and illustrated on the example above. It is desirable to perform the projection...... of symmetry coordinates in such a way that they may be used for as many wave vectors as possible. We discuss how to achieve this goal. The detailed illustrations should make it simple to apply the theory in any other case....

  3. Integral group actions on symmetric spaces and discrete duality symmetries of supergravity theories

    Energy Technology Data Exchange (ETDEWEB)

    Carbone, Lisa [Mathematics Rutgers University, Hill Center-Busch Campus, 110 Frelinghuysen Rd., Piscataway, New Jersey 08854 (United States); Murray, Scott H. [Mathematics & Statistics, University of Canberra, ACT 2601 (Australia); Sati, Hisham [Department of Mathematics, University of Pittsburgh, 301 Thackeray Hall, Pittsburgh, Pennsylvania 15260 (United States)

    2015-10-15

    For G = G(ℝ), a split, simply connected, semisimple Lie group of rank n and K the maximal compact subgroup of G, we give a method for computing Iwasawa coordinates of K∖G using the Chevalley generators and the Steinberg presentation. When K∖G is a scalar coset for a supergravity theory in dimensions ≥3, we determine the action of the integral form G(ℤ) on K∖G. We give explicit results for the action of the discrete U-duality groups SL{sub 2}(ℤ) and E{sub 7}(ℤ) on the scalar cosets SO(2)∖SL{sub 2}(ℝ) and [SU(8)/( ± Id)]∖E{sub 7(+7)}(ℝ) for type IIB supergravity in ten dimensions and 11-dimensional supergravity reduced to D = 4 dimensions, respectively. For the former, we use this to determine the discrete U-duality transformations on the scalar sector in the Borel gauge and we describe the discrete symmetries of the dyonic charge lattice. We determine the spectrum-generating symmetry group for fundamental BPS solitons of type IIB supergravity in D = 10 dimensions at the classical level and we propose an analog of this symmetry at the quantum level. We indicate how our methods can be used to study the orbits of discrete U-duality groups in general.

  4. Symmetries, Information and Monster Groups before and after the Big Bang

    Directory of Open Access Journals (Sweden)

    Arturo Tozzi

    2016-12-01

    Full Text Available The Monster group, the biggest of the sporadic groups, is equipped with the highest known number of dimensions and symmetries. Taking into account variants of the Borsuk–Ulam theorem and a novel topological approach cast in a physical fashion that has the potential to be operationalized, the universe can be conceived as a lower-dimensional manifold encompassed in the Monster group. Our universe might arise from spontaneous dimension decrease and symmetry breaking that occur inside the very structure of the Monster Module. We elucidate how the energetic loss caused by projection from higher to lower dimensions and by the Monster group’s non-abelian features is correlated with the present-day asymmetry in the thermodynamic arrow. By linking the Monster Module to its theoretical physical counterparts, it is then possible to calculate its enthalpy and Lie group trajectories. Our approach also reveals how a symmetry break might lead to a universe based on multi-dimensional string theories and CFT/AdS (anti-de Sitter/conformal field theory correspondence.

  5. Partner Symmetries, Group Foliation and ASD Ricci-Flat Metrics without Killing Vectors

    Directory of Open Access Journals (Sweden)

    Andrei A. Malykh

    2013-11-01

    Full Text Available We demonstrate how a combination of our recently developed methods of partner symmetries, symmetry reduction in group parameters and a new version of the group foliation method can produce noninvariant solutions of complex Monge-Ampère equation (CMA and provide a lift from invariant solutions of CMA satisfying Boyer-Finley equation to non-invariant ones. Applying these methods, we obtain a new noninvariant solution of CMA and the corresponding Ricci-flat anti-self-dual Einstein-Kähler metric with Euclidean signature without Killing vectors, together with Riemannian curvature two-forms. There are no singularities of the metric and curvature in a bounded domain if we avoid very special choices of arbitrary functions of a single variable in our solution. This metric does not describe gravitational instantons because the curvature is not concentrated in a bounded domain.

  6. The Structure of Reduced Sudoku Grids and the Sudoku Symmetry Group

    OpenAIRE

    Jones, Siân K.; Perkins, Stephanie; Roach, Paul A.

    2012-01-01

    A Sudoku grid is a constrained Latin square. In this paper a reduced Sudoku grid is described, the properties of which differ, through necessity, from that of a reduced Latin square. The Sudoku symmetry group is presented and applied to determine a mathematical relationship between the number of reduced Sudoku grids and the total number of Sudoku grids for any size. This relationship simplifies the enumeration of Sudoku grids and an example of the use of this method is given.

  7. Vortices, circumfluence, symmetry groups and Darboux transformations of the Euler equations

    OpenAIRE

    Lou, S. Y.; Tang, X. Y.; Jia, M.; Huang, F.

    2005-01-01

    The Euler equation (EE) is one of the basic equations in many physical fields such as the fluids, plasmas, condense matters, astrophysics, oceanic and atmospheric dynamics. A new symmetry group theorem of the two dimensional EE is obtained via a simple direct method and the theorem is used to find \\em exact analytical \\rm vortex and circumfluence solutions. Some types of Darboux transformations (DTs) for the both two and three dimensional EEs are obtained for \\em arbitrary spectral parameters...

  8. Point defects in group IV semiconductors

    CERN Document Server

    Pizzini, S

    2017-01-01

    Aim of this book is to focus on the properties of defects in semiconductors of the fourth group under a physico-chemical approach, capable to demonstrate whether the full acknowledgement of their chemical nature could account for several problems encountered in practice or would suggest further experimental or theoretical accomplishments.

  9. Discrete Symmetries Analysis and Exact Solutions of the Inviscid Burgers Equation

    Directory of Open Access Journals (Sweden)

    Hongwei Yang

    2012-01-01

    Full Text Available We discuss the Lie point symmetries and discrete symmetries of the inviscid Burgers equation. By employing the Lie group method of infinitesimal transformations, symmetry reductions and similarity solutions of the governing equation are given. Based on discrete symmetries analysis, two groups of discrete symmetries are obtained, which lead to new exact solutions of the inviscid Burgers equation.

  10. A Phase Transformation with no Change in Space Group Symmetry: Octafluoronaphtalene

    DEFF Research Database (Denmark)

    Pawley, G. S.; Dietrich, O. W.

    1975-01-01

    A solid-state phase transformation in octafluoronaphthalene has been discovered at 266.5K on cooling, and at 15K higher on heating. The symmetry of both phases is found to be the same, namely monoclinic with space group P21/c. The unit cell parameters change by up to 10%, but the integrity...... of a single crystal, which shatters on cooling, is good enough for a single-crystal structure determination. This has been done in both phases to a sufficient accuracy that a mechanism for the transformation can be proposed. Molecules which lie parallel to one another shear to a new parallel position......, the shear movement being equal to one carbon-carbon bond of the naphthalene skeleton. In this process the molecules reorient, but are still related by the same symmetry operations. This transformation, although not unique, is probably the first of its kind to be discovered in molecular systems....

  11. ATLAS Point-1 System Administration Group

    CERN Multimedia

    Marc Dobson

    2007-01-01

    Hello, my name is Joe Blog and I am about to go on shift at ATLAS. When I enter the control room shown below with my CERN ID card, I go to the subsystem desk for which I am responsible. This is the first shift of the run period and there is a login window displayed on the screens. I just need to hit return and the control room desktop is started. Before I can do anything I must give my credentials in the shifter window which is then synchronised with the shift plan. After that I have access to all the allowed commands and can start preparing for the run. In order not to forget any steps I consult the documentation on how to prepare for a run on the Point-1 web. I can also check what the general status is for the ATLAS online computing farm, the sub-detectors and the LHC by using the utilities provided. ATLAS Control Room. The situation described is made up but the conditions are real. But the control room that the shifters and general public see is only the tip of the iceberg. Behind these tools lie the...

  12. First-Order Interfacial Transformations with a Critical Point: Breaking the Symmetry at a Symmetric Tilt Grain Boundary

    Science.gov (United States)

    Yang, Shengfeng; Zhou, Naixie; Zheng, Hui; Ong, Shyue Ping; Luo, Jian

    2018-02-01

    First-order interfacial phaselike transformations that break the mirror symmetry of the symmetric ∑5 (210 ) tilt grain boundary (GB) are discovered by combining a modified genetic algorithm with hybrid Monte Carlo and molecular dynamics simulations. Density functional theory calculations confirm this prediction. This first-order coupled structural and adsorption transformation, which produces two variants of asymmetric bilayers, vanishes at an interfacial critical point. A GB complexion (phase) diagram is constructed via semigrand canonical ensemble atomistic simulations for the first time.

  13. Parity-Time Symmetry and the Toy Models of Gain-Loss Dynamics near the Real Kato's Exceptional Points

    Czech Academy of Sciences Publication Activity Database

    Znojil, Miloslav

    2016-01-01

    Roč. 8, č. 6 (2016), s. 52 ISSN 2073-8994 R&D Projects: GA ČR GA16-22945S Institutional support: RVO:61389005 Keywords : parity-time symmetry * Schrodinger equation * physical Hilbert space * inner-product metric operator * real exceptional points * solvable models * quantum Big Bang * quantum Inflation period Subject RIV: BE - Theoretical Physics Impact factor: 1.457, year: 2016

  14. Observation of valleylike edge states of sound at a momentum away from the high-symmetry points

    Science.gov (United States)

    Xia, Bai-Zhan; Zheng, Sheng-Jie; Liu, Ting-Ting; Jiao, Jun-Rui; Chen, Ning; Dai, Hong-Qing; Yu, De-Jie; Liu, Jian

    2018-04-01

    In condensed matter physics, topologically protected edge transportation has drawn extensive attention over recent years. Thus far, the topological valley edge states have been produced near the Dirac cones fixed at the high-symmetry points of the Brillouin zone. In this paper, we demonstrate a unique valleylike phononic crystal (PnC) with the position-varying Dirac cones at the high-symmetry lines of the Brillouin zone boundary. The emergence of such Dirac cones, characterized by the vortex structure in a momentum space, is attributed to the unavoidable band crossing protected by the mirror symmetry. The Dirac cones can be unbuckled and a complete band gap can be induced through breaking the mirror symmetry. Interestingly, by simply rotating the square columns, we realize the valleylike vortex states and the band inversion effect which leads to the valley Hall phase transition. Along the valleylike PnC interfaces separating two distinct acoustic valley Hall phases, the valleylike protected edge transport of sound in domain walls is observed in both the simulations and the experiments. These results are promising for the exploration of alternative topological phenomena in the valleylike PnCs beyond the graphenelike lattice.

  15. dx^2-y^2 paring symmetry of heavy fermion CeIrIn5 remote from antiferromagnetic quantum critical point

    Science.gov (United States)

    Kasahara, Yuichi; Iwasawa, T.; Shimizu, Y.; Shishido, H.; Shibauchi, T.; Vekhter, I.; Matsuda, Y.

    2008-03-01

    Quasi-two dimensional heavy Fermion CeIrIn5 involves two distinct superconducting domes in the phase diagram, which appear as a function of pressure or Rh substitution of Ir. In the analogy to CeCu2Si2, two distinct superconducting domes with different symmetry has been invoked. We report on the results of low-temperature thermal transport of CeIrIn5 in the second dome, which locates away from an antiferromagnetic quantum critical point. The thermal conductivity is measured under a magnetic field rotated with respect to the crystal axes, which give direct evidence for superconducting gap structure. Clear fourfold oscillation with minima at [110] and [1-10] directions is observed as rotating magnetic field within the basal ab-plane, while no oscillation is observed within the bc-plane. In sharp contrast to previous reports that suggested Eg symmetry with horizontal line node within the ab-plane [1], our results are most consistent with dx^2- y^2 symmetry with vertical line nodes along the c-axis. These results imply that two superconducting domes have the same gap symmetry which appears to be mediated by antiferromagnetic spin fluctuations. [1] H. Shakeripour et al., Phys. Rev. Lett. 99, 187004 (2007).

  16. A contour integral representation for the dual five-point function and a symmetry of the genus-4 surface in R6

    International Nuclear Information System (INIS)

    Hanson, Andrew J; Sha Jiping

    2006-01-01

    The invention of the 'dual resonance model' N-point functions B N motivated the development of current string theory. The simplest of these models, the four-point function B 4 , is the classical Euler Beta function. Many standard methods of complex analysis in a single variable have been applied to elucidate the properties of the Euler Beta function, leading, for example, to analytic continuation formulae such as the contour-integral representation obtained by Pochhammer in 1890. However, the precise features of the expected multiple-complex-variable generalizations to B N have not been systematically studied. Here we explore the geometry underlying the dual five-point function B 5 , the simplest generalization of the Euler Beta function. The original integrand defining B 5 leads to a polyhedral structure for the five-crosscap surface, embedded in RP 5 , that has 12 pentagonal faces and a symmetry group of order 120 in PGL(6). We find a Pochhammer-like representation for B 5 that is a contour integral along a surface of genus 5 in CP 2 x 4(CP 2 )-bar. The symmetric embedding of the five-crosscap surface in RP 5 is doubly covered by a corresponding symmetric embedding of the surface of genus 4 in S 5 is contained in R 6 that has a polyhedral structure with 24 pentagonal faces and a symmetry group of order 240 in O(6). These symmetries enable the construction of elegant visualizations of these surfaces. The key idea of this paper is to realize that the compactification of the set of five-point cross-ratios forms a smooth real algebraic subvariety that is the five-crosscap surface in RP 5 . It is in the complexification of this surface that we construct the contour integral representation for B 5 . Our methods are generalizable in principle to higher dimensions, and therefore should be of interest for further study

  17. Molecular symmetry and group theory a programmed introduction to chemical applications

    CERN Document Server

    Vincent, Alan

    2013-01-01

    This substantially revised and expanded new edition of the bestselling textbook, addresses the difficulties that can arise with the mathematics that underpins the study of symmetry, and acknowledges that group theory can be a complex concept for students to grasp.Written in a clear, concise manner, the author introduces a series of programmes that help students learn at their own pace and enable to them understand the subject fully. Readers are taken through a series of carefully constructed exercises, designed to simplify the mathematics and give them a full understanding of how this

  18. Symmetries and Laplacians introduction to harmonic analysis, group representations and applications

    CERN Document Server

    Gurarie, D

    1992-01-01

    Designed as an introduction to harmonic analysis and group representations,this book covers a wide range of topics rather than delving deeply into anyparticular one. In the words of H. Weyl ...it is primarily meant forthe humble, who want to learn as new the things set forth therein, rather thanfor the proud and learned who are already familiar with the subject and merelylook for quick and exact information.... The main objective is tointroduce the reader to concepts, ideas, results and techniques that evolvearound symmetry-groups, representations and Laplacians. Morespecifically, the main interest concerns geometrical objects and structures{X}, discrete or continuous, that possess sufficiently large symmetrygroup G, such as regular graphs (Platonic solids), lattices, andsymmetric Riemannian manifolds. All such objects have a natural Laplacian&Dgr;, a linear operator on functions over X, invariant underthe group action. There are many problems associated with Laplacians onX, such as continuous or discrete...

  19. An improved contour symmetry axes extraction algorithm and its application in the location of picking points of apples

    International Nuclear Information System (INIS)

    Wang, D.; Song, H.; Yu, X.; Zhang, W.; Qu, W.; Xu, Y.

    2015-01-01

    The key problem for picking robots is to locate the picking points of fruit. A method based on the moment of inertia and symmetry of apples is proposed in this paper to locate the picking points of apples. Image pre-processing procedures, which are crucial to improving the accuracy of the location, were carried out to remove noise and smooth the edges of apples. The moment of inertia method has the disadvantage of high computational complexity, which should be solved, so convex hull was used to improve this problem. To verify the validity of this algorithm, a test was conducted using four types of apple images containing 107 apple targets. These images were single and unblocked apple images, single and blocked apple images, images containing adjacent apples, and apples in panoramas. The root mean square error values of these four types of apple images were 6.3, 15.0, 21.6 and 18.4, respectively, and the average location errors were 4.9°, 10.2°, 16.3° and 13.8°, respectively. Furthermore, the improved algorithm was effective in terms of average runtime, with 3.7 ms and 9.2 ms for single and unblocked and single and blocked apple images, respectively. For the other two types of apple images, the runtime was determined by the number of apples and blocked apples contained in the images. The results showed that the improved algorithm could extract symmetry axes and locate the picking points of apples more efficiently. In conclusion, the improved algorithm is feasible for extracting symmetry axes and locating the picking points of apples. (Author)

  20. An improved contour symmetry axes extraction algorithm and its application in the location of picking points of apples

    Directory of Open Access Journals (Sweden)

    Dandan Wang

    2015-03-01

    Full Text Available The key problem for picking robots is to locate the picking points of fruit. A method based on the moment of inertia and symmetry of apples is proposed in this paper to locate the picking points of apples. Image pre-processing procedures, which are crucial to improving the accuracy of the location, were carried out to remove noise and smooth the edges of apples. The moment of inertia method has the disadvantage of high computational complexity, which should be solved, so convex hull was used to improve this problem. To verify the validity of this algorithm, a test was conducted using four types of apple images containing 107 apple targets. These images were single and unblocked apple images, single and blocked apple images, images containing adjacent apples, and apples in panoramas. The root mean square error values of these four types of apple images were 6.3, 15.0, 21.6 and 18.4, respectively, and the average location errors were 4.9°, 10.2°, 16.3° and 13.8°, respectively. Furthermore, the improved algorithm was effective in terms of average runtime, with 3.7 ms and 9.2 ms for single and unblocked and single and blocked apple images, respectively. For the other two types of apple images, the runtime was determined by the number of apples and blocked apples contained in the images. The results showed that the improved algorithm could extract symmetry axes and locate the picking points of apples more efficiently. In conclusion, the improved algorithm is feasible for extracting symmetry axes and locating the picking points of apples.

  1. An improved contour symmetry axes extraction algorithm and its application in the location of picking points of apples

    Energy Technology Data Exchange (ETDEWEB)

    Wang, D.; Song, H.; Yu, X.; Zhang, W.; Qu, W.; Xu, Y.

    2015-07-01

    The key problem for picking robots is to locate the picking points of fruit. A method based on the moment of inertia and symmetry of apples is proposed in this paper to locate the picking points of apples. Image pre-processing procedures, which are crucial to improving the accuracy of the location, were carried out to remove noise and smooth the edges of apples. The moment of inertia method has the disadvantage of high computational complexity, which should be solved, so convex hull was used to improve this problem. To verify the validity of this algorithm, a test was conducted using four types of apple images containing 107 apple targets. These images were single and unblocked apple images, single and blocked apple images, images containing adjacent apples, and apples in panoramas. The root mean square error values of these four types of apple images were 6.3, 15.0, 21.6 and 18.4, respectively, and the average location errors were 4.9°, 10.2°, 16.3° and 13.8°, respectively. Furthermore, the improved algorithm was effective in terms of average runtime, with 3.7 ms and 9.2 ms for single and unblocked and single and blocked apple images, respectively. For the other two types of apple images, the runtime was determined by the number of apples and blocked apples contained in the images. The results showed that the improved algorithm could extract symmetry axes and locate the picking points of apples more efficiently. In conclusion, the improved algorithm is feasible for extracting symmetry axes and locating the picking points of apples. (Author)

  2. Two dimentional lattice vibrations from direct product representations of symmetry groups

    Directory of Open Access Journals (Sweden)

    J. N. Boyd

    1983-01-01

    two dimensional crystals. First, the Born cyclic condition is applied to a double chain composed of coupled linear lattices to obtain a cylindrical arrangement. Then the quadratic Lagrangian function for the system is written in matrix notation. The Lagrangian is diagonalized to yield the natural frequencies of the system. The transformation to achieve the diagonalization was obtained from group theorectic considerations. Next, the techniques developed for the double chain are applied to a square lattice. The square lattice is transformed into the toroidal Ising model. The direct product nature of the symmetry group of the torus reveals the transformation to diagonalize the Lagrangian for the Ising model, and the natural frequencies for the principal directions in the model are obtained in closed form.

  3. Optics of short-pitch deformed-helix ferroelectric liquid crystals: Symmetries, exceptional points, and polarization-resolved angular patterns

    Science.gov (United States)

    Kiselev, Alexei D.; Chigrinov, Vladimir G.

    2014-10-01

    In order to explore electric-field-induced transformations of polarization singularities in the polarization-resolved angular (conoscopic) patterns emerging after deformed-helix ferroelectric liquid crystal (DHFLC) cells with subwavelength helix pitch, we combine the transfer matrix formalism with the results for the effective dielectric tensor of biaxial FLCs evaluated using an improved technique of averaging over distorted helical structures. Within the framework of the transfer matrix method, we deduce a number of symmetry relations and show that the symmetry axis of L lines (curves of linear polarization) is directed along the major in-plane optical axis which rotates under the action of the electric field. When the angle between this axis and the polarization plane of incident linearly polarized light is above its critical value, the C points (points of circular polarization) appear in the form of symmetrically arranged chains of densely packed star-monstar pairs. We also emphasize the role of phase singularities of a different kind and discuss the enhanced electro-optic response of DHFLCs near the exceptional point where the condition of zero-field isotropy is fulfilled.

  4. The homological functor of a Bieberbach group with a cyclic point group of order two

    Science.gov (United States)

    Hassim, Hazzirah Izzati Mat; Sarmin, Nor Haniza; Ali, Nor Muhainiah Mohd; Masri, Rohaidah; Idrus, Nor'ashiqin Mohd

    2014-07-01

    The generalized presentation of a Bieberbach group with cyclic point group of order two can be obtained from the fact that any Bieberbach group of dimension n is a direct product of the group of the smallest dimension with a free abelian group. In this paper, by using the group presentation, the homological functor of a Bieberbach group a with cyclic point group of order two of dimension n is found.

  5. On symmetry groups of a 2D nonlinear diffusion equation with source

    Indian Academy of Sciences (India)

    Symmetry analysis of higher-dimensional diffusion equations with convection was first considered in [15]. The equation considered here had the form: ut = n. ∑ i=1. (Di(u)uxi )xi + G(u)uxn . (3). The objective of this paper is to obtain the conditions enabling nontrivial symmetries to exist for the 2D nonlinear equation with a ...

  6. Reduction by Lie Group Symmetries in Diffeomorphic Image Registration and Deformation Modelling

    Directory of Open Access Journals (Sweden)

    Stefan Sommer

    2015-05-01

    Full Text Available We survey the role of reduction by symmetry in the large deformation diffeomorphic metric mapping framework for registration of a variety of data types (landmarks, curves, surfaces, images and higher-order derivative data. Particle relabelling symmetry allows the equations of motion to be reduced to the Lie algebra allowing the equations to be written purely in terms of the Eulerian velocity field. As a second use of symmetry, the infinite dimensional problem of finding correspondences between objects can be reduced for a range of concrete data types, resulting in compact representations of shape and spatial structure. Using reduction by symmetry, we describe these models in a common theoretical framework that draws on links between the registration problem and geometric mechanics. We outline these constructions and further cases where reduction by symmetry promises new approaches to the registration of complex data types.

  7. On some homological functors of a Bieberbach group with symmetric point group

    Science.gov (United States)

    Ting, Tan Yee; Idrus, Nor'ashiqin Mohd; Masri, Rohaidah; Ladi, Nor Fadzilah Abdul

    2017-05-01

    Bieberbach groups with symmetric point group are polycyclic. The properties of the groups can be explored by computing their homological functors. In this paper, some homological functors of a Bieberbach group with symmetric point group, such as the Schur multiplier and the G-trivial subgroup of the nonabelian tensor square, are generalized up to finite dimension and are represented in the form of direct product of cyclic groups.

  8. Homological functor of a torsion free crystallographic group of dimension five with a nonabelian point group

    Science.gov (United States)

    Ting, Tan Yee; Idrus, Nor'ashiqin Mohd.; Masri, Rohaidah; Sarmin, Nor Haniza; Hassim, Hazzirah Izzati Mat

    2014-06-01

    Torsion free crystallographic groups, called Bieberbach groups, appear as fundamental groups of compact, connected, flat Riemannian manifolds and have many interesting properties. New properties of the group can be obtained by, not limited to, exploring the groups and by computing their homological functors such as nonabelian tensor squares, the central subgroup of nonabelian tensor squares, the kernel of the mapping of nonabelian tensor squares of a group to the group and many more. In this paper, the homological functor, J(G) of a centerless torsion free crystallographic group of dimension five with a nonabelian point group which is a dihedral point group is computed using commutator calculus.

  9. Validation of missed space-group symmetry in X-ray powder diffraction structures with dispersion-corrected density functional theory

    DEFF Research Database (Denmark)

    Hempler, Daniela; Schmidt, Martin U.; Van De Streek, Jacco

    2017-01-01

    More than 600 molecular crystal structures with correct, incorrect and uncertain space-group symmetry were energy-minimized with dispersion-corrected density functional theory (DFT-D, PBE-D3). For the purpose of determining the correct space-group symmetry the required tolerance on the atomic...... with missed symmetry were investigated by dispersion-corrected density functional theory. In 98.5% of the cases the correct space group is found....

  10. Systematic group-specific trends for point defects in bcc transition metals: An ab initio study

    International Nuclear Information System (INIS)

    Nguyen-Manh, D.; Dudarev, S.L.; Horsfield, A.P.

    2007-01-01

    Density functional theory calculations have been performed to study the systematic trends of point defect behaviours in bcc transition metals. We found that in all non-magnetic bcc transition metals, the most stable self-interstitial atom (SIAs) defect configuration has the symmetry. The calculated formation energy differences between the dumbbell and the lowest-energy configuration of metals in group 5B (V, Nb, Ta) are consistently larger than those of the corresponding element in group 6B (Cr, Mo, W). The predicted trends of SIA defects are fundamentally different from those in ferromagnetic α-Fe and correlate very well with the pronounced group-specific variation of thermally activated migration of SIAs under irradiation depending on the position of bcc metals in the periodic table

  11. Group classification and symmetry reduction of a (2+1) dimensional diffusion-advection equation

    Science.gov (United States)

    Elwakil, S. A.; Zahran, M. A.; Sabry, R.

    2005-11-01

    Based on classical Lie group method, we consider the continuum problem of the driven diffusive flow of particles past an impenetrable obstacle (rod) of length L. The infinitesimals of the diffusion-advection equation in (2+1) dimensions were found for an arbitrary nonlinear advection. The symmetries corresponding to different forms of the nonlinear advection are obtained. Three models are studied in details. The results show that the presence of an obstacle, whether stationary or moving, in a driven diffusive flow with nonlinear drift will distort the local concentration profile to a state which divided the (x, y)-plane into two regions. The concentration is relatively higher in one side than the other side, apart from the value of D/{\\upsilon L}, where D is the diffusion coefficient and υ is the drift velocity. This problem has relevance for the size segregation of particulate matter which results from the relative motion of different-size particles induced by shaking. Also, the obtained solutions include soliton, periodical, rational and singular solutions.

  12. Renormalization-group flows and fixed points in Yukawa theories

    DEFF Research Database (Denmark)

    Mølgaard, Esben; Shrock, R.

    2014-01-01

    We study renormalization-group flows in Yukawa theories with massless fermions, including determination of fixed points and curves that separate regions of different flow behavior. We assess the reliability of perturbative calculations for various values of Yukawa coupling y and quartic scalar....... In the regime of weak couplings where the perturbative calculations are most reliable, we find that the theories have no nontrivial fixed points, and the flow is toward a free theory in the infrared....

  13. Field-theory representation of gauge-gravity symmetry-protected topological invariants, group cohomology, and beyond.

    Science.gov (United States)

    Wang, Juven C; Gu, Zheng-Cheng; Wen, Xiao-Gang

    2015-01-23

    The challenge of identifying symmetry-protected topological states (SPTs) is due to their lack of symmetry-breaking order parameters and intrinsic topological orders. For this reason, it is impossible to formulate SPTs under Ginzburg-Landau theory or probe SPTs via fractionalized bulk excitations and topology-dependent ground state degeneracy. However, the partition functions from path integrals with various symmetry twists are universal SPT invariants, fully characterizing SPTs. In this work, we use gauge fields to represent those symmetry twists in closed spacetimes of any dimensionality and arbitrary topology. This allows us to express the SPT invariants in terms of continuum field theory. We show that SPT invariants of pure gauge actions describe the SPTs predicted by group cohomology, while the mixed gauge-gravity actions describe the beyond-group-cohomology SPTs. We find new examples of mixed gauge-gravity actions for U(1) SPTs in (4+1)D via the gravitational Chern-Simons term. Field theory representations of SPT invariants not only serve as tools for classifying SPTs, but also guide us in designing physical probes for them. In addition, our field theory representations are independently powerful for studying group cohomology within the mathematical context.

  14. Focus point gauge mediation in product group unification

    International Nuclear Information System (INIS)

    Bruemmer, Felix; Ibe, Masahiro; Tokyo Univ., Kashiwa; Yanagida, Tsutomu T.

    2013-03-01

    In certain models of gauge-mediated supersymmetry breaking with messenger fields in incomplete GUT multiplets, the radiative corrections to the Higgs potential cancel out during renormalization group running. This allows for relatively heavy superpartners and for a 125 GeV Higgs while the ne-tuning remains modest. In this paper, we show that such gauge mediation models with ''focus point'' behaviour can be naturally embedded into a model of SU(5) x U(3) product group unification.

  15. An infinite lie group of symmetry of one-dimensional gas flow, for a class of entropy distributions

    Science.gov (United States)

    Gaffet, B.

    1984-06-01

    We have shown in earlier works the existence of three previously unknown symmetries of the equations of one-dimensional gas dynamics, with arbitrary entropy distribution and arbitrary polytropic index γ. These symmetries are seen here to form a group whenever the equation of state is of the form P = ϱ3( a0 + a1M + a2M2) -2 where M = ∝ ϱd r is the Lagrangian mass coordinate. Introducing the remaining symmetry of space-translation enlarges the group into a Lie group of symmetry of infinite order, from which an infinite number of conservation laws can be deduced by application of Noether's theorem. The Lie group has a finite sub-algebra of order eight, which has SU3 structure; the list of associated conservation laws includes each of the six ones that are derivable from general physical principles, namely: the energy, momentum and the center-of-mass integrals, two integrals expressing scale invariance, and one associated with the virial theorem; the remaining two integrals of the octet are of a new type. Such a situation reminds us of the case of the Korteweg-de Vries equation in the soliton problem, where the symmetries and infinite number of conservation laws arise as a result of the possibility to linearize through the inverse-scattering method. Thus the question is raised of whether the inverse-scattering method also applies to gas-dynamical equations (with the above equation of state), or else whether another method of linearization may be found.

  16. Classical Lie Point Symmetry Analysis of a Steady Nonlinear One-Dimensional Fin Problem

    Directory of Open Access Journals (Sweden)

    R. J. Moitsheki

    2012-01-01

    Full Text Available We consider the one-dimensional steady fin problem with the Dirichlet boundary condition at one end and the Neumann boundary condition at the other. Both the thermal conductivity and the heat transfer coefficient are given as arbitrary functions of temperature. We perform preliminary group classification to determine forms of the arbitrary functions appearing in the considered equation for which the principal Lie algebra is extended. Some invariant solutions are constructed. The effects of thermogeometric fin parameter and the exponent on temperature are studied. Also, the fin efficiency is analyzed.

  17. Classification of the Lie and Noether point symmetries for the Wave and the Klein-Gordon equations in pp-wave spacetimes

    OpenAIRE

    Paliathanasis, A.; Tsamparlis, M.; Mustafa, M. T.

    2017-01-01

    We perform a classification of the Lie and Noether point symmetries for the Klein-Gordon and for the wave equation in pp-wave spacetimes. To perform this analysis we reduce the problem of the determination of the point symmetries to the problem of existence of conformal killing vectors on the pp-wave spacetimes. We use the existing results of the literature for the isometry classes of the pp-wave spacetimes and we determine in each class the functional form of the potential in which the Klein...

  18. Quantized Response and Topological Magnetic Insulators with Inversion Symmetry

    NARCIS (Netherlands)

    Turner, A.M.; Zhang, Y.; Mong, R.S.K.; Vishwanath, A.

    2012-01-01

    We study three-dimensional insulators with inversion symmetry in which other point group symmetries, such as time reversal, are generically absent. We find that certain information about such materials’ behavior is determined by just the eigenvalues under inversion symmetry of occupied states at

  19. Polynomial Graphs and Symmetry

    Science.gov (United States)

    Goehle, Geoff; Kobayashi, Mitsuo

    2013-01-01

    Most quadratic functions are not even, but every parabola has symmetry with respect to some vertical line. Similarly, every cubic has rotational symmetry with respect to some point, though most cubics are not odd. We show that every polynomial has at most one point of symmetry and give conditions under which the polynomial has rotational or…

  20. Allowable irreducible representations of the point groups with five ...

    Indian Academy of Sciences (India)

    table 2). Table 1. Character table for the point group D5. D5. E. 2C5. 2C2. 5. 5C2. A1. 1. 1. 1. 1. A2. 1. 1. 1. 1. E1. 2. 2 cos 72. ◦. 2 cos 144. ◦. 0. E2. 2. 2 cos 144. ◦. 2 cos 72. ◦. 0. Generating elements: C5, C2; Defining relations: (C5)5 = (C2)2 = E ...

  1. Non-linear entropy functionals and a characteristic invariant of symmetry group actions on infinite quantum systems

    International Nuclear Information System (INIS)

    Hudetz, T.

    1989-01-01

    We review the development of the non-Abelian generalization of the Kolmogorov-Sinai(KS) entropy invariant, as initated by Connes and Stormer and completed by Connes, Narnhofer and Thirring only recently. As an introduction and motivation, the classical KS theory is reformulated in terms of Abelian W * -algebras. Finally, we describe simple physical applications of the developed characteristic invariant to space-time symmetry group actions on infinite quantum systems. 42 refs. (Author)

  2. Hidden U$_{q}$(sl(2)) x U$_{q}$(sl(2)) quantum group symmetry in two dimensional gravity

    CERN Document Server

    Cremmer, E; Schnittger, J

    1997-01-01

    In a previous paper, we proposed a construction of U_q(sl(2)) quantum group symmetry generators for 2d gravity, where we took the chiral vertex operators of the theory to be the quantum group covariant ones established in earlier works. The basic idea was that the covariant fields in the spin 1/2 representation themselves can be viewed as generators, as they act, by braiding, on the other fields exactly in the required way. Here we transform this construction to the more conventional description of 2d gravity in terms of Bloch wave/Coulomb gas vertex operators, thereby establishing for the first time its quantum group symmetry properties. A U_q(sl(2))\\otimes U_q(sl(2)) symmetry of a novel type emerges: The two Cartan-generator eigenvalues are specified by the choice of matrix element (bra/ket Verma-modules); the two Casimir eigenvalues are equal and specified by the Virasoro weight of the vertex operator considered; the co-product is defined with a matching condition dictated by the Hilbert space structure of...

  3. On the Cut-off Point for Combinatorial Group Testing

    DEFF Research Database (Denmark)

    Fischer, Paul; Klasner, N.; Wegener, I.

    1999-01-01

    The following problem is known as group testing problem for n objects. Each object can be essential (defective) or non-essential (intact). The problem is to determine the set of essential objects by asking queries adaptively. A query can be identified with a set Q of objects and the query Q...... group testing is equal to p* = 12(3 - 5), i.e., the strategy of testing each object individually minimizes the average number of queries iff p >= p* or n = 1. In the combinatorial setting the worst case number of queries is of interest. It has been conjectured that the cut-off point of combinatorial...... group testing is equal to alpha* = 13, i.e., the strategy of testing n - 1 objects individually minimizes the worst case number of queries iff k/n >= alpha* and k

  4. 3D Printed Molecules and Extended Solid Models for Teaching Symmetry and Point Groups

    Science.gov (United States)

    Scalfani, Vincent F.; Vaid, Thomas P.

    2014-01-01

    Tangible models help students and researchers visualize chemical structures in three dimensions (3D). 3D printing offers a unique and straightforward approach to fabricate plastic 3D models of molecules and extended solids. In this article, we prepared a series of digital 3D design files of molecular structures that will be useful for teaching…

  5. Symmetry-adapted density matrix renormalization group calculations of the primary excited states of poly(para-phenylene vinylene).

    Science.gov (United States)

    Bursill, Robert J; Barford, William

    2009-06-21

    The Pariser-Parr-Pople model of pi-conjugated electrons is solved by a three-block, symmetry-adapted density matrix renormalization group (DMRG) method for the light emitting polymer, poly(para-phenylene vinylene). The energies of the primary excited states are calculated. There is excellent agreement between theory and experiment when solid state screening is incorporated into the model parameters, enabling us to make an identification of the origin of the key spectroscopic features. Appendices describe important technical aspects of the three-block DMRG approach: Local Hilbert space efficiency and its relation to the matrix product formulation of the DMRG; an efficient computational procedure for constructing symmetry-adapted states for DMRG calculations; and correct superblock state targeting to ensure good convergence of the method.

  6. Spin-anisotropy commensurable chains. Quantum group symmetries and N = 2 SUSY

    Science.gov (United States)

    Bérkovich, Alexander; Gómez, César; Sierra, Germán

    1994-03-01

    In this paper we consider a class of 2D integrable models. These models are higher- spin XXZ-chains with an extra condition of the commensurability between spin ( j) and anisotropy ( γ): sin γ (2 j + 1) = 0. Thus, the mathematics underlying this commensurability is provided by the quantum groups with the deformation parameter being an Nth root of unity. Our discussion covers a range of topics including new integrable deformations, thermodynamics, conformal behaviour, S-matrices and magnetization. The emerging picture strongly depends on the N-parity. For the N-even case at the commensurable point, S- matrices factorize into an N = 2 supersymmetric sine-Gordon matrix and an RSOS piece. The physics of the N-odd case is rather different. Here, there are hints suggesting that supersymmetry is still present, however we did not unravel its nature, yet. In this case, S-matrices factorize into two RSOS pieces. The second RSOS piece has dependence on an extra parameter. Away from the commensurable point, we find an unusual magnetic behaviour. The magnetization of our chains depends on the sign of the external magnetic field.

  7. Weak C* Hopf Symmetry

    OpenAIRE

    Rehren, K. -H.

    1996-01-01

    Weak C* Hopf algebras can act as global symmetries in low-dimensional quantum field theories, when braid group statistics prevents group symmetries. Possibilities to construct field algebras with weak C* Hopf symmetry from a given theory of local observables are discussed.

  8. Response matrix method for neutron transport in reactor lattices using group symmetry properties

    International Nuclear Information System (INIS)

    Mund, E.H.

    1991-01-01

    This paper describes a response matrix method for the approximate solution of one-velocity, multi-dimensional transport problems in reactor lattices, with isotropic neutron scattering. The transport equation is solved on a homogeneous cell by using a Petrov-Galerkin technique based on a set of trial and test functions (including polynomials and exponential functions) closely related to transport problems in infinite media. The number of non-zero elements of the response matrices reduces to a minimum when the symmetry properties of the cell are included ab initio in the span of the basis functions. To include these properties, use is made of projection operations which are performed very efficiently on symbolic manipulation programs. Numerical results of model problems in square geometry show a good agreement with reference solutions

  9. The bandgap controlling by geometrical symmetry design in hybrid phononic crystal

    Science.gov (United States)

    Zhang, Z.; Han, X. K.; Ji, G. M.

    2018-02-01

    The effects of symmetries on the bandgap in a newly designed hybrid phononic crystal plate composed of rubber slab and epoxy resin stub are studied for better controlling of bandgaps. The point group symmetry is changed by changing the orientation of the stub. The translation group symmetry is changed by changing the side length and the height of adjacent stubs. Results show that the point group symmetry and translation group symmetry can be important factors for controlling of the bandgaps of phononic crystal. Wider bandgap is obtained by suitable orientation of the stub. Lower bandgap appears when the differences between the adjacent stubs become bigger in supercell.

  10. On some homological functors of Bieberbach group of dimension four with dihedral point group of order eight

    Science.gov (United States)

    Mohammad, Siti Afiqah; Ali, Nor Muhainiah Mohd; Sarmin, Nor Haniza; Idrus, Nor'ashiqin Mohd; Masri, Rohaidah

    2014-06-01

    A Bieberbach group is a torsion free crystallographic group, which is an extension of a free abelian group of finite rank by a finite point group, while homological functors of a group include nonabelian tensor square, exterior square and Schur Multiplier. In this paper, some homological functors of a Bieberbach group of dimension four with dihedral point group of order eight are computed.

  11. From spin groups and modular P{sub 1}CT symmetry to covariant representations and the spin-statistics theorem

    Energy Technology Data Exchange (ETDEWEB)

    Lorenzen, R.

    2007-03-15

    Starting from the assumption of modular P{sub 1}CT symmetry in quantum field theory a representation of the universal covering of the Poincar'e group is constructed in terms of pairs of modular conjugations. The modular conjugations are associated with field algebras of unbounded operators localised in wedge regions. It turns out that an essential step consists in characterising the universal covering group of the Lorentz group by pairs of wedge regions, in conjunction with an analysis of its geometrical properties. In this thesis two approaches to this problem are developed in four spacetime dimensions. First a realisation of the universal covering as the quotient space over the set of pairs of wedge regions is presented. In spite of the intuitive definition, the necessary properties of a covering space are not straightforward to prove. But the geometrical properties are easy to handle. The second approach takes advantage of the well-known features of spin groups, given as subgroups of Clifford algebras. Characterising elements of spin groups by pairs of wedge regions is possible in an elegant manner. The geometrical analysis is performed by means of the results achieved in the first approach. These geometrical properties allow for constructing a representation of the universal cover of the Lorentz group in terms of pairs of modular conjugations. For this representation the derivation of the spin-statistics theorem is straightforward, and a PCT operator can be defined. Furthermore, it is possible to transfer the results to nets of field algebras in algebraic quantum field theory with ease. Many of the usual assumptions in quantum field theory like the spectrum condition or the existence of a covariant unitary representation, as well as the assumption on the quantum field to have only finitely many components, are not required. For the standard axioms, the crucial assumption of modular P{sub 1}CT symmetry constitutes no loss of generality because it is a

  12. Ermakov's Superintegrable Toy and Nonlocal Symmetries

    Directory of Open Access Journals (Sweden)

    P.G.L. Leach

    2005-11-01

    Full Text Available We investigate the symmetry properties of a pair of Ermakov equations. The system is superintegrable and yet possesses only three Lie point symmetries with the algebra sl(2, R. The number of point symmetries is insufficient and the algebra unsuitable for the complete specification of the system. We use the method of reduction of order to reduce the nonlinear fourth-order system to a third-order system comprising a linear second-order equation and a conservation law. We obtain the representation of the complete symmetry group from this system. Four of the required symmetries are nonlocal and the algebra is the direct sum of a one-dimensional Abelian algebra with the semidirect sum of a two-dimensional solvable algebra with a two-dimensional Abelian algebra. The problem illustrates the difficulties which can arise in very elementary systems. Our treatment demonstrates the existence of possible routes to overcome these problems in a systematic fashion.

  13. Ermakov's Superintegrable Toy and Nonlocal Symmetries

    Science.gov (United States)

    Leach, P. G. L.; Karasu Kalkanli, A.; Nucci, M. C.; Andriopoulos, K.

    2005-11-01

    We investigate the symmetry properties of a pair of Ermakov equations. The system is superintegrable and yet possesses only three Lie point symmetries with the algebra sl(2, R). The number of point symmetries is insufficient and the algebra unsuitable for the complete specification of the system. We use the method of reduction of order to reduce the nonlinear fourth-order system to a third-order system comprising a linear second-order equation and a conservation law. We obtain the representation of the complete symmetry group from this system. Four of the required symmetries are nonlocal and the algebra is the direct sum of a one-dimensional Abelian algebra with the semidirect sum of a two-dimensional solvable algebra with a two-dimensional Abelian algebra. The problem illustrates the difficulties which can arise in very elementary systems. Our treatment demonstrates the existence of possible routes to overcome these problems in a systematic fashion.

  14. Symmetries of nonlinear ordinary differential equations: The ...

    Indian Academy of Sciences (India)

    2015-10-21

    Oct 21, 2015 ... Abstract. Lie symmetry analysis is one of the powerful tools to analyse nonlinear ordinary dif- ferential equations. We review the effectiveness of this method in terms of various symmetries. We present the method of deriving Lie point symmetries, contact symmetries, hidden symmetries, nonlocal symmetries ...

  15. Symbolic Detection of Permutation and Parity Symmetries of Evolution Equations

    KAUST Repository

    Alghamdi, Moataz

    2017-06-18

    We introduce a symbolic computational approach to detecting all permutation and parity symmetries in any general evolution equation, and to generating associated invariant polynomials, from given monomials, under the action of these symmetries. Traditionally, discrete point symmetries of differential equations are systemically found by solving complicated nonlinear systems of partial differential equations; in the presence of Lie symmetries, the process can be simplified further. Here, we show how to find parity- and permutation-type discrete symmetries purely based on algebraic calculations. Furthermore, we show that such symmetries always form groups, thereby allowing for the generation of new group-invariant conserved quantities from known conserved quantities. This work also contains an implementation of the said results in Mathematica. In addition, it includes, as a motivation for this work, an investigation of the connection between variational symmetries, described by local Lie groups, and conserved quantities in Hamiltonian systems.

  16. Symmetries of quantum spaces. Subgroups and quotient spaces of quantum SU(2) and SO(3) groups

    International Nuclear Information System (INIS)

    Podles, P.

    1995-01-01

    We prove that each action of a compact matrix quantum group on a compact quantum space can be decomposed into irreducible representations of the group. We give the formula for the corresponding multiplicities in the case of the quotient quantum spaces. We describe the subgroups and the quotient spaces of quantum SU(2) and SO(3) groups. (orig.)

  17. Exact renormalization group equation for the Lifshitz critical point

    Science.gov (United States)

    Bervillier, C.

    2004-10-01

    An exact renormalization equation (ERGE) accounting for an anisotropic scaling is derived. The critical and tricritical Lifshitz points are then studied at leading order of the derivative expansion which is shown to involve two differential equations. The resulting estimates of the Lifshitz critical exponents compare well with the O(ε) calculations. In the case of the Lifshitz tricritical point, it is shown that a marginally relevant coupling defies the perturbative approach since it actually makes the fixed point referred to in the previous perturbative calculations O(ε) finally unstable.

  18. Group theory approach to unification of gravity with internal symmetry gauge interactions. Part 1

    International Nuclear Information System (INIS)

    Samokhvalov, S.E.; Vanyashin, V.S.

    1990-12-01

    The infinite group of deformed diffeomorphisms of space-time continuum is put into the basis of the Gauge Theory of Gravity. This gives rise to some new ways for unification of gravity with other gauge interactions. (author). 7 refs

  19. Spin-Anisotropy Commensurable Chains: Quantum Group Symmetries and N=2 SUSY

    OpenAIRE

    Berkovich, A.; Gomez, C.; Sierra, G.

    1993-01-01

    In this paper we consider a class of the 2D integrable models. These models are higher spin XXZ chains with an extra condition of the commensurability between spin and anisotropy. The mathematics underlying this commensurability is provided by the quantum groups with deformation parameter being an Nth root of unity. Our discussion covers a range of topics including new integrable deformations, thermodynamics, conformal behaviour, S-matrices and magnetization. The emerging picture strongly dep...

  20. On the mixed symmetry irreducible representations of the Poincare group in the BRST approach

    International Nuclear Information System (INIS)

    Burdik, C.; Pashnev, A.; Tsulaya, M.

    2001-01-01

    The Lagrangian description of irreducible massless representations of the Poincare group with the corresponding Young tableaux having two rows along with some explicit examples including the notoph and Weyl tensor is given. For this purpose the method of the BRST constructions is used adopted to the systems of the second class constraints by the construction of auxiliary representations of the algebras of constraints in terms of Verma modules

  1. Focus point gauge mediation in product group unification

    International Nuclear Information System (INIS)

    Brümmer, Felix; Ibe, Masahiro; Yanagida, Tsutomu T.

    2013-01-01

    In certain models of gauge-mediated supersymmetry breaking with messenger fields in incomplete GUT multiplets, the radiative corrections to the Higgs potential cancel out during renormalization group running. This allows for relatively heavy superpartners and for a 125 GeV Higgs while the fine-tuning remains modest. In this Letter, we show that such gauge mediation models with “focus point” behaviour can be naturally embedded into a model of SU(5)×U(3) product group unification

  2. Partial dynamical symmetry

    International Nuclear Information System (INIS)

    Alhassid, Y.; Leviatan, A.

    1993-01-01

    A novel symmetry structure, partial dynamical symmetry is introduced. The Hamiltonian is not invariant under the transformations of a group G and irreps of G are mixed in its eigenstates. it possesses, however, a partial set of eigenstates which do have good symmetry and can be labeled by irreps of G. A general algorithm to construct such Hamiltonians for a semi-simple group G is presented. (Author) 6 refs

  3. Conditions for Symmetries in the Buckle Patterns of Laminated-Composite Plates

    Science.gov (United States)

    Nemeth, Michael P.

    2012-01-01

    Conditions for the existence of certain symmetries to exist in the buckle patterns of symmetrically laminated composite plates are presented. The plates considered have a general planform with cutouts, variable thickness and stiffnesses, and general support and loading conditions. The symmetry analysis is based on enforcing invariance of the corresponding eigenvalue problem for a group of coordinate transformations associated with buckle patterns commonly exhibited by symmetrically laminated plates. The buckle-pattern symmetries examined include a central point of inversion symmetry, one plane of reflective symmetry, and two planes of reflective symmetry.

  4. On group orders of retional points of elliptic curves | Weng ...

    African Journals Online (AJOL)

    We consider elliptic curves without complex multiplication defined over the rationals or with complex multiplication defined over the Hilbert class field of the endomorphism ring. We examine the distribution of almost prime group orders of these curves when reduced modulo a prime ideal. Mathematics Subject Classification ...

  5. Anomalous Symmetry Fractionalization and Surface Topological Order

    Directory of Open Access Journals (Sweden)

    Xie Chen

    2015-10-01

    Full Text Available In addition to possessing fractional statistics, anyon excitations of a 2D topologically ordered state can realize symmetry in distinct ways, leading to a variety of symmetry-enriched topological (SET phases. While the symmetry fractionalization must be consistent with the fusion and braiding rules of the anyons, not all ostensibly consistent symmetry fractionalizations can be realized in 2D systems. Instead, certain “anomalous” SETs can only occur on the surface of a 3D symmetry-protected topological (SPT phase. In this paper, we describe a procedure for determining whether a SET of a discrete, on-site, unitary symmetry group G is anomalous or not. The basic idea is to gauge the symmetry and expose the anomaly as an obstruction to a consistent topological theory combining both the original anyons and the gauge fluxes. Utilizing a result of Etingof, Nikshych, and Ostrik, we point out that a class of obstructions is captured by the fourth cohomology group H^{4}(G,U(1, which also precisely labels the set of 3D SPT phases, with symmetry group G. An explicit procedure for calculating the cohomology data from a SET is given, with the corresponding physical intuition explained. We thus establish a general bulk-boundary correspondence between the anomalous SET and the 3D bulk SPT whose surface termination realizes it. We illustrate this idea using the chiral spin liquid [U(1_{2}] topological order with a reduced symmetry Z_{2}×Z_{2}⊂SO(3, which can act on the semion quasiparticle in an anomalous way. We construct exactly solved 3D SPT models realizing the anomalous surface terminations and demonstrate that they are nontrivial by computing three-loop braiding statistics. Possible extensions to antiunitary symmetries are also discussed.

  6. Z n clock models and chains of so(n)2 non-Abelian anyons: symmetries, integrable points and low energy properties

    Science.gov (United States)

    Finch, Peter E.; Flohr, Michael; Frahm, Holger

    2018-02-01

    We study two families of quantum models which have been used previously to investigate the effect of topological symmetries in one-dimensional correlated matter. Various striking similarities are observed between certain {Z}n quantum clock models, spin chains generalizing the Ising model, and chains of non-Abelian anyons constructed from the so(n)2 fusion category for odd n, both subject to periodic boundary conditions. In spite of the differences between these two types of quantum chains, e.g. their Hilbert spaces being spanned by tensor products of local spin states or fusion paths of anyons, the symmetries of the lattice models are shown to be closely related. Furthermore, under a suitable mapping between the parameters describing the interaction between spins and anyons the respective Hamiltonians share part of their energy spectrum (although their degeneracies may differ). This spin-anyon correspondence can be extended by fine-tuning of the coupling constants leading to exactly solvable models. We show that the algebraic structures underlying the integrability of the clock models and the anyon chain are the same. For n  =  3,5,7 we perform an extensive finite size study—both numerical and based on the exact solution—of these models to map out their ground state phase diagram and to identify the effective field theories describing their low energy behaviour. We observe that the continuum limit at the integrable points can be described by rational conformal field theories with extended symmetry algebras which can be related to the discrete ones of the lattice models.

  7. Quantum Space-Time Deformed Symmetries Versus Broken Symmetries

    CERN Document Server

    Amelino-Camelia, G

    2002-01-01

    Several recent studies have concerned the faith of classical symmetries in quantum space-time. In particular, it appears likely that quantum (discretized, noncommutative,...) versions of Minkowski space-time would not enjoy the classical Lorentz symmetries. I compare two interesting cases: the case in which the classical symmetries are "broken", i.e. at the quantum level some classical symmetries are lost, and the case in which the classical symmetries are "deformed", i.e. the quantum space-time has as many symmetries as its classical counterpart but the nature of these symmetries is affected by the space-time quantization procedure. While some general features, such as the emergence of deformed dispersion relations, characterize both the symmetry-breaking case and the symmetry-deformation case, the two scenarios are also characterized by sharp differences, even concerning the nature of the new effects predicted. I illustrate this point within an illustrative calculation concerning the role of space-time symm...

  8. Symmetries in nature

    International Nuclear Information System (INIS)

    Mainzer, K.

    1988-01-01

    Symmetry, disymmetry, chirality etc. are well-known topics in chemistry. But they cannot only be found on the molecular level of matter. Atoms and elementary particles in physics are also characterized by particular symmetry groups. Even living organisms and populations on the macroscopic level have functional properties of symmetry. The whole physical, chemical, and biological evolution seems to be regulated by the emergence of new symmetries and the breaking down of old ones. One is reminded of Heisenberg's famous statement: 'Die letzte Wurzel der Erscheinungen ist also nicht die Materie, sondern das mathematische Gesetz, die Symmetrie, die mathematische Form' (Wandlungen in den Grundlagen der Naturwissenschaften, 1959). Historically the belief in symmetry and simplicity of nature has a long philosophical tradition from the Pythagoreans, Plato and Greek astronomers to Kepler and modern scientists. Today, 'symmetries in nature' is a common topic of mathematics, physics, chemistry, and biology. A lot of Nobel prizes were given in honour of inquiries concerning symmetries in nature. The fascination of symmetries is not only motivated by science, but by art and religion too. Therefore 'symmetris in nature' is an interdisciplinary topic which may help to overcome C.P. Snow's 'Two Cultures' of natural sciences and humanities. (author) 17 refs., 21 figs

  9. Applications of Lie Groups and Gauge Functions to the Construction of Exact Difference Equations for Initial and Two-Point Boundary Value Problems

    Energy Technology Data Exchange (ETDEWEB)

    R. Axford

    2002-08-02

    New methods are developed to construct exact difference equations from which numerical solutions of both initial value problems and two-point boundary value problems involving first and second order ordinary differential equations can be computed. These methods are based upon the transformation theory of differential equations and require the identification of symmetry properties of the differential equations. The concept of the divergence-invariance of a variational principle is also applied to the construction of difference equations. It is shown how first and second order ordinary differential equations that admit groups of point transformations can be integrated numerically by constructing any number of exact difference equations.

  10. Necessary Condition for Emergent Symmetry from the Conformal Bootstrap.

    Science.gov (United States)

    Nakayama, Yu; Ohtsuki, Tomoki

    2016-09-23

    We use the conformal bootstrap program to derive the necessary conditions for emergent symmetry enhancement from discrete symmetry (e.g., Z_{n}) to continuous symmetry [e.g., U(1)] under the renormalization group flow. In three dimensions, in order for Z_{2} symmetry to be enhanced to U(1) symmetry, the conformal bootstrap program predicts that the scaling dimension of the order parameter field at the infrared conformal fixed point must satisfy Δ_{1}>1.08. We also obtain the similar necessary conditions for Z_{3} symmetry with Δ_{1}>0.580 and Z_{4} symmetry with Δ_{1}>0.504 from the simultaneous conformal bootstrap analysis of multiple four-point functions. As applications, we show that our necessary conditions impose severe constraints on the nature of the chiral phase transition in QCD, the deconfinement criticality in Néel valence bond solid transitions, and anisotropic deformations in critical O(n) models. We prove that some fixed points proposed in the literature are unstable under the perturbation that cannot be forbidden by the discrete symmetry. In these situations, the second-order phase transition with enhanced symmetry cannot happen.

  11. On the abelianization of all Bieberbach groups of dimension four with symmetric point group of order six

    Science.gov (United States)

    Ting, Tan Yee; Idrus, Nor'ashiqin Mohd; Masri, Rohaidah; Fauzi, Wan Nor Farhana Wan Mohd; Sarmin, Nor Haniza; Hassim, Hazzirah Izzati Mat

    2014-12-01

    A torsion free crystallographic group, which is known as a Bieberbach group, has many interesting properties. The properties of the groups can be explored by computing the homological functors of the groups. In the computation of the homological functors, the abelianization of groups plays an important role. The abelianization of a group can be constructed by computing its derived subgroup. In this paper, the construction of the abelianization of all Bieberbach groups of dimension four with symmetric point group of order six are shown. Groups, Algorithms and Programming (GAP) software is used to assist the construction.

  12. Quantum symmetry for pedestrians

    International Nuclear Information System (INIS)

    Mack, G.; Schomerus, V.

    1992-03-01

    Symmetries more general than groups are possible in quantum therory. Quantum symmetries in the narrow sense are compatible with braid statistics. They are theoretically consistent much as supersymmetry is, and they could lead to degenerate multiplets of excitations with fractional spin in thin films. (orig.)

  13. Applications of chiral symmetry

    International Nuclear Information System (INIS)

    Pisarski, R.D.

    1995-03-01

    The author discusses several topics in the applications of chiral symmetry at nonzero temperature. First, where does the rho go? The answer: up. The restoration of chiral symmetry at a temperature T χ implies that the ρ and a 1 vector mesons are degenerate in mass. In a gauged linear sigma model the ρ mass increases with temperature, m ρ (T χ ) > m ρ (0). The author conjectures that at T χ the thermal ρ - a 1 , peak is relatively high, at about ∼1 GeV, with a width approximately that at zero temperature (up to standard kinematic factors). The ω meson also increases in mass, nearly degenerate with the ρ, but its width grows dramatically with temperature, increasing to at least ∼100 MeV by T χ . The author also stresses how utterly remarkable the principle of vector meson dominance is, when viewed from the modern perspective of the renormalization group. Secondly, he discusses the possible appearance of disoriented chiral condensates from open-quotes quenchedclose quotes heavy ion collisions. It appears difficult to obtain large domains of disoriented chiral condensates in the standard two flavor model. This leads to the last topic, which is the phase diagram for QCD with three flavors, and its proximity to the chiral critical point. QCD may be very near this chiral critical point, and one might thereby generated large domains of disoriented chiral condensates

  14. R-symmetries from the orbifolded heterotic string

    International Nuclear Information System (INIS)

    Schmitz, Matthias

    2014-08-01

    We examine the geometric origin of discrete R-symmetries in heterotic orbifold compactifications. By analysing the symmetries of the worldsheet instanton solutions and the underlying geometry, we obtain a scheme that allows us to systematically explore the R-symmetries arising in these compactifications. Applying this scheme to a classification of orbifold geometries, we are able to find all R-symmetries of heterotic orbifolds with Abelian point groups. We show that in the vast majority of cases, the R-symmetries found satisfy anomaly universality constraints, as required in heterotic orbifolds. Then we examine the implications of the presence of these R-symmetries on a class of phenomenologically attractive orbifold compactifications known as the heterotic mini-landscape. We use the technique of Hilbert bases in order to analyse the properties of a vacuum configuration. We find that phenomenologically viable models remain and the main attractive features of the mini-landscape are unaltered.

  15. Symmetry and symmetry breaking in quantum mechanics

    International Nuclear Information System (INIS)

    Chomaz, Philippe

    1998-01-01

    In the world of infinitely small, the world of atoms, nuclei and particles, the quantum mechanics enforces its laws. The discovery of Quanta, this unbelievable castration of the Possible in grains of matter and radiation, in discrete energy levels compels us of thinking the Single to comprehend the Universal. Quantum Numbers, magic Numbers and Numbers sign the wave. The matter is vibration. To describe the music of the world one needs keys, measures, notes, rules and partition: one needs quantum mechanics. The particles reduce themselves not in material points as the scholars of the past centuries thought, but they must be conceived throughout the space, in the accomplishment of shapes of volumes. When Einstein asked himself whether God plays dice, there was no doubt among its contemporaries that if He exists He is a geometer. In a Nature reduced to Geometry, the symmetries assume their role in servicing the Harmony. The symmetries allow ordering the energy levels to make them understandable. They impose there geometrical rules to the matter waves, giving them properties which sometimes astonish us. Hidden symmetries, internal symmetries and newly conceived symmetries have to be adopted subsequently to the observation of some order in this world of Quanta. In turn, the symmetries provide new observables which open new spaces of observation

  16. Density functional theory-broken symmetry (DFT-BS) methodology applied to electronic and magnetic properties of bioinorganic prosthetic groups.

    Science.gov (United States)

    Mouesca, Jean-Marie

    2014-01-01

    The goal of this "how to" chapter is to present in a way as simple and practical as possible some of the concepts, key issues, and practices behind the so-called broken symmetry (BS) state which is widely used within the density functional theory (DFT) (for a very nice but thoughtful introduction to DFT (without equations!), read Perdew et al. (J Chem Theory Comput 5:902-908, 2009)) community to compute energetic as well as spectroscopic properties pertaining to (poly-)radicals, bioinorganic clusters (especially those containing transition metal ions), etc. Such properties encompass exchange coupling constants J (molecular magnetism) but also (among other things) g-tensors and hyperfine coupling tensors A (from electron paramagnetic resonance), isomer shifts δ and quadrupolar tensors ΔE Q (from Mössbauer), etc.Hopefully, this chapter will appeal to those DFT practitioners who would like to understand the basics behind the BS state and help them "demystify" some of the issues involved with them. More technical issues will only be alluded to, and appropriate references will be given for those interested to go beyond this mere introduction. This chapter is however not a review of the field. Consequently, it will be primarily based on my own experience. The goal here (in the spirit of a "how to" chapter) is to accompany the readers' thoughts in a progressive way along increasingly complex issues rather than encumbering the same thoughts with too complicate mathematical details (the few derivations which are given will therefore be explicit). Moreover, I will emphasize in this chapter the interplay between the computation of BS states on the one hand, and the derivation of phenomenological models on the other hand, whose parameters can be supplied from appropriate BS states. Finally, this chapter is dedicated to Louis Noodleman (Scripps Research Institute, CA, USA), pioneer (Noodleman, J Chem Phys 74:5737-5743, 1981; Noodleman, Chem Phys 109:131-143, 1986) and

  17. Parity-Time Symmetry and the Toy Models of Gain-Loss Dynamics near the Real Kato’s Exceptional Points

    Directory of Open Access Journals (Sweden)

    Miloslav Znojil

    2016-06-01

    Full Text Available For a given operator D ( t of an observable in theoretical parity-time symmetric quantum physics (or for its evolution-generator analogues in the experimental gain-loss classical optics, etc. the instant t c r i t i c a l of a spontaneous breakdown of the parity-time alias gain-loss symmetry should be given, in the rigorous language of mathematics, the Kato’s name of an “exceptional point”, t c r i t i c a l = t ( E P . In the majority of conventional applications the exceptional point (EP values are not real. In our paper, we pay attention to several exactly tractable toy-model evolutions for which at least some of the values of t ( E P become real. These values are interpreted as “instants of a catastrophe”, be it classical or quantum. In the classical optical setting the discrete nature of our toy models might make them amenable to simulations. In the latter context the instant of Big Bang is mentioned as an illustrative sample of possible physical meaning of such an EP catastrophe in quantum cosmology.

  18. Dihedral flavor symmetries

    International Nuclear Information System (INIS)

    Blum, Alexander Simon

    2009-01-01

    This thesis deals with the possibility of describing the flavor sector of the Standard Model of Particle Physics (with neutrino masses), that is the fermion masses and mixing matrices, with a discrete, non-abelian flavor symmetry. In particular, mass independent textures are considered, where one or several of the mixing angles are determined by group theory alone and are independent of the fermion masses. To this end a systematic analysis of a large class of discrete symmetries, the dihedral groups, is analyzed. Mass independent textures originating from such symmetries are described and it is shown that such structures arise naturally from the minimization of scalar potentials, where the scalars are gauge singlet flavons transforming non-trivially only under the flavor group. Two models are constructed from this input, one describing leptons, based on the group D 4 , the other describing quarks and employing the symmetry D 14 . In the latter model it is the quark mixing matrix element V ud - basically the Cabibbo angle - which is at leading order predicted from group theory. Finally, discrete flavor groups are discussed as subgroups of a continuous gauge symmetry and it is shown that this implies that the original gauge symmetry is broken by fairly large representations. (orig.)

  19. Dihedral flavor symmetries

    Energy Technology Data Exchange (ETDEWEB)

    Blum, Alexander Simon

    2009-06-10

    This thesis deals with the possibility of describing the flavor sector of the Standard Model of Particle Physics (with neutrino masses), that is the fermion masses and mixing matrices, with a discrete, non-abelian flavor symmetry. In particular, mass independent textures are considered, where one or several of the mixing angles are determined by group theory alone and are independent of the fermion masses. To this end a systematic analysis of a large class of discrete symmetries, the dihedral groups, is analyzed. Mass independent textures originating from such symmetries are described and it is shown that such structures arise naturally from the minimization of scalar potentials, where the scalars are gauge singlet flavons transforming non-trivially only under the flavor group. Two models are constructed from this input, one describing leptons, based on the group D{sub 4}, the other describing quarks and employing the symmetry D{sub 14}. In the latter model it is the quark mixing matrix element V{sub ud} - basically the Cabibbo angle - which is at leading order predicted from group theory. Finally, discrete flavor groups are discussed as subgroups of a continuous gauge symmetry and it is shown that this implies that the original gauge symmetry is broken by fairly large representations. (orig.)

  20. The nonabelian tensor square of Bieberbach group of dimension five with dihedral point group of order eight

    Science.gov (United States)

    Fauzi, Wan Nor Farhana Wan Mohd; Idrus, Nor'ashiqin Mohd; Masri, Rohaidah; Sarmin, Nor Haniza

    2014-07-01

    The nonabelian tensor product was originated in homotopy theory as well as in algebraic K-theory. The nonabelian tensor square is a special case of the nonabelian tensor product where the product is defined if the two groups act on each other in a compatible way and their action are taken to be conjugation. In this paper, the computation of nonabelian tensor square of a Bieberbach group, which is a torsion free crystallographic group, of dimension five with dihedral point group of order eight is determined. Groups, Algorithms and Programming (GAP) software has been used to assist and verify the results.

  1. Trends and Cut-Point Changes in Obesity Parameters by Age Groups Considering Metabolic Syndrome.

    Science.gov (United States)

    Park, Hyung Jun; Hong, Young Ho; Cho, Yun Jung; Lee, Ji Eun; Yun, Jae Moon; Kwon, Hyuktae; Kim, Sang Hyuck

    2018-02-12

    Non-communicable diseases (NCDs) are an important issue worldwide. Obesity has a close relationship with NCDs. Various age-related changes should be considered when evaluating obesity. National representative cohort data from the National Health Insurance Service National Sample Cohort from 2012 to 2013 were used. Sex-specific and age group-specific (10-year intervals) means for body mass index (BMI), waist circumference (WC), and waist-to-height ratio (WtHR) were calculated. Optimal cut-points for obesity parameters were defined as the value predicting two or more components of metabolic syndrome (except WC). The mean value and optimal cut-point for BMI decreased with age for men. The mean BMI value for women increased with age, but optimal cut-points showed no remarkable difference. The mean WC of men increased with age, but the optimal cut-points were similar for age groups. For women, the mean value and optimal cut-point for WC increased with age. Regarding WtHR, the mean value and optimal cut-point increased with age for men and women. Differences across age groups were larger for women. The mean values of the obesity indices and the optimal cut-points were changed according to age groups. This study supports the necessity of applying age group-specific cut-points for the various obesity parameters. © 2018 The Korean Academy of Medical Sciences.

  2. Recursions of Symmetry Orbits and Reduction without Reduction

    Directory of Open Access Journals (Sweden)

    Andrei A. Malykh

    2011-04-01

    Full Text Available We consider a four-dimensional PDE possessing partner symmetries mainly on the example of complex Monge-Ampère equation (CMA. We use simultaneously two pairs of symmetries related by a recursion relation, which are mutually complex conjugate for CMA. For both pairs of partner symmetries, using Lie equations, we introduce explicitly group parameters as additional variables, replacing symmetry characteristics and their complex conjugates by derivatives of the unknown with respect to group parameters. We study the resulting system of six equations in the eight-dimensional space, that includes CMA, four equations of the recursion between partner symmetries and one integrability condition of this system. We use point symmetries of this extended system for performing its symmetry reduction with respect to group parameters that facilitates solving the extended system. This procedure does not imply a reduction in the number of physical variables and hence we end up with orbits of non-invariant solutions of CMA, generated by one partner symmetry, not used in the reduction. These solutions are determined by six linear equations with constant coefficients in the five-dimensional space which are obtained by a three-dimensional Legendre transformation of the reduced extended system. We present algebraic and exponential examples of such solutions that govern Legendre-transformed Ricci-flat Kähler metrics with no Killing vectors. A similar procedure is briefly outlined for Husain equation.

  3. Hourglass semimetals with nonsymmorphic symmetries in three dimensions

    Science.gov (United States)

    Wang, Luyang; Jian, Shao-Kai; Yao, Hong

    2017-08-01

    It was recently shown that nonsymmorphic space-group symmetries can protect novel surface states with hourglasslike dispersions. In this paper, we show that such dispersions can also appear in the bulk of three-dimensional (3D) systems which respect nonsymmorphic symmetries. Specifically, we construct 3D lattice models featuring hourglasslike dispersions in the bulk, which are protected by nonsymmorphic and time-reversal symmetries. We call such systems hourglass semimetals, as they have point or line nodes associated with hourglasslike dispersions. Hourglass nodal lines appear in glide-invariant planes, while hourglass Weyl points can occur on screw-invariant axes. The Weyl points and surface Fermi arcs in hourglass Weyl semimetals are stable against weak perturbations breaking those nonsymmorphic symmetries. Our results may shed light on searching for exotic Weyl semimetals in nonsymmorphic materials.

  4. Symmetry witnesses

    Science.gov (United States)

    Aniello, Paolo; Chruściński, Dariusz

    2017-07-01

    A symmetry witness is a suitable subset of the space of selfadjoint trace class operators that allows one to determine whether a linear map is a symmetry transformation, in the sense of Wigner. More precisely, such a set is invariant with respect to an injective densely defined linear operator in the Banach space of selfadjoint trace class operators (if and) only if this operator is a symmetry transformation. According to a linear version of Wigner’s theorem, the set of pure states—the rank-one projections—is a symmetry witness. We show that an analogous result holds for the set of projections with a fixed rank (with some mild constraint on this rank, in the finite-dimensional case). It turns out that this result provides a complete classification of the sets of projections with a fixed rank that are symmetry witnesses. These particular symmetry witnesses are projectable; i.e. reasoning in terms of quantum states, the sets of ‘uniform’ density operators of corresponding fixed rank are symmetry witnesses too.

  5. Symmetry Adapted Basis Sets

    DEFF Research Database (Denmark)

    Avery, John Scales; Rettrup, Sten; Avery, James Emil

    In theoretical physics, theoretical chemistry and engineering, one often wishes to solve partial differential equations subject to a set of boundary conditions. This gives rise to eigenvalue problems of which some solutions may be very difficult to find. For example, the problem of finding...... in such problems can be much reduced by making use of symmetry-adapted basis functions. The conventional method for generating symmetry-adapted basis sets is through the application of group theory, but this can be difficult. This book describes an easier method for generating symmetry-adapted basis sets...

  6. Symmetry Analysis and Conservation Laws for the Hunter—Saxton Equation

    Science.gov (United States)

    Mehdi, Nadjafikhah; Fatemeh, Ahangari

    2013-03-01

    In this paper, the problem of determining the most general Lie point symmetries group and conservation laws of a well known nonlinear hyperbolic PDE in mathematical physics called the Hunter-Saxton equation (HSE) is analyzed. By applying the basic Lie symmetry method for the HSE, the classical Lie point symmetry operators are obtained. Also, the algebraic structure of the Lie algebra of symmetries is discussed and an optimal system of one-dimensional subalgebras of the HSE symmetry algebra which creates the preliminary classification of group invariant solutions is constructed. Particularly, the Lie invariants as well as similarity reduced equations corresponding to infinitesimal symmetries are obtained. Mainly, the conservation laws of the HSE are computed via three different methods including Boyer's generalization of Noether's theorem, first homotopy method and second homotopy method.

  7. Mirror symmetry

    CERN Document Server

    Voisin, Claire

    1999-01-01

    This is the English translation of Professor Voisin's book reflecting the discovery of the mirror symmetry phenomenon. The first chapter is devoted to the geometry of Calabi-Yau manifolds, and the second describes, as motivation, the ideas from quantum field theory that led to the discovery of mirror symmetry. The other chapters deal with more specialized aspects of the subject: the work of Candelas, de la Ossa, Greene, and Parkes, based on the fact that under the mirror symmetry hypothesis, the variation of Hodge structure of a Calabi-Yau threefold determines the Gromov-Witten invariants of its mirror; Batyrev's construction, which exhibits the mirror symmetry phenomenon between hypersurfaces of toric Fano varieties, after a combinatorial classification of the latter; the mathematical construction of the Gromov-Witten potential, and the proof of its crucial property (that it satisfies the WDVV equation), which makes it possible to construct a flat connection underlying a variation of Hodge structure in the ...

  8. A model of intrinsic symmetry breaking

    International Nuclear Information System (INIS)

    Ge, Li; Li, Sheng; George, Thomas F.; Sun, Xin

    2013-01-01

    Different from the symmetry breaking associated with a phase transition, which occurs when the controlling parameter is manipulated across a critical point, the symmetry breaking presented in this Letter does not need parameter manipulation. Instead, the system itself suddenly undergoes symmetry breaking at a certain time during its evolution, which is intrinsic symmetry breaking. Through a polymer model, it is revealed that the origin of the intrinsic symmetry breaking is nonlinearity, which produces instability at the instance when the evolution crosses an inflexion point, where this instability breaks the original symmetry

  9. Web-Supported Chemistry Education: Design of an Online Tutorial for Learning Molecular Symmetry

    Science.gov (United States)

    Korkmaz, Ali; Harwood, William S.

    2004-01-01

    This paper describes our use of the ADDIE protocol to design and develop an interactive tutorial for students learning molecular symmetry operations and point groups. The tutorial provides a 3-D environment where students can examine molecules, structures, and symmetry elements. Most such tutorials are connected to courses or instructors in…

  10. The self-defining axis of symmetry: A new method to determine optimal symmetry and its application and limitation in craniofacial surgery.

    Science.gov (United States)

    Martini, Markus; Klausing, Anne; Messing-Jünger, Martina; Lüchters, Guido

    2017-09-01

    Analysis of symmetry represents an essential aspect of plastic-reconstructive surgery. For cases in which reference points are either not fixed or are changed due to corrective intervention the determination of a symmetry axis is sometimes almost impossible and a pre-defined symmetry axis would not always be helpful. To assess cranial shape of surgical patients with craniosynostosis, a new algebraic approach was chosen in which deviation from the optimal symmetry axis could be quantified. Optimal symmetry was defined based on a single central point in the fronto-orbital advancement (FOA) hyperplane and a corresponding landmark pair. The forehead symmetry evaluation was based on 3D-scans series of 13 children, on whom cranioplasty with FOA was performed and 15 healthy children who served as control group. Children with plagiocephaly showed considerable improvement in symmetry postoperatively, with stable values over one year, while those with trigonocephaly and brachycephaly showed constant good symmetry in the forehead both pre- and postoperatively. With the help of an optimally calculated symmetry axis this new analysis method offers a solution, which is independent of preset dimensions. Patients can be evaluated according to their individual needs regarding symmetry and also be compared with one another. Copyright © 2017 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

  11. Symmetries of the refined D1/D5 BPS spectrum

    Science.gov (United States)

    Benjamin, Nathan; Harrison, Sarah M.

    2017-11-01

    We examine the large N 1/4-BPS spectrum of the symmetric orbifold CFT Sym N ( M ) deformed to the supergravity point in moduli space for M = K3 and T 4. We consider refinement under both left- and right-moving SU(2) R symmetries of the superconformal algebra, and decompose the spectrum into characters of the algebra. We find that at large N the character decomposition satisfies an unusual property, in which the degeneracy only depends on a certain linear combination of left- and right-moving quantum numbers, suggesting deeper symmetry structure. Furthermore, we consider the action of discrete symmetry groups on these degeneracies, where certain subgroups of the Conway group are known to play a role. We also comment on the potential for larger discrete symmetry groups to appear in the large N limit.

  12. Collective states and crossing symmetry

    International Nuclear Information System (INIS)

    Heiss, W.D.

    1977-01-01

    Collective states are usually described in simple terms but with the use of effective interactions which are supposed to contain more or less complicated contributions. The significance of crossing symmetry is discussed in this connection. Formal problems encountered in the attempts to implement crossing symmetry are pointed out

  13. Symmetry and inflation

    International Nuclear Information System (INIS)

    Chimento, Luis P.

    2002-01-01

    We find the group of symmetry transformations under which the Einstein equations for the spatially flat Friedmann-Robertson-Walker universe are form invariant. They relate the energy density and the pressure of the fluid to the expansion rate. We show that inflation can be obtained from nonaccelerated scenarios by a symmetry transformation. We derive the transformation rule for the spectrum and spectral index of the curvature perturbations. Finally, the group is extended to investigate inflation in the anisotropic Bianchi type-I spacetime and the brane-world cosmology

  14. Parallel point-multiplication architecture using combined group operations for high-speed cryptographic applications.

    Directory of Open Access Journals (Sweden)

    Md Selim Hossain

    Full Text Available In this paper, we propose a novel parallel architecture for fast hardware implementation of elliptic curve point multiplication (ECPM, which is the key operation of an elliptic curve cryptography processor. The point multiplication over binary fields is synthesized on both FPGA and ASIC technology by designing fast elliptic curve group operations in Jacobian projective coordinates. A novel combined point doubling and point addition (PDPA architecture is proposed for group operations to achieve high speed and low hardware requirements for ECPM. It has been implemented over the binary field which is recommended by the National Institute of Standards and Technology (NIST. The proposed ECPM supports two Koblitz and random curves for the key sizes 233 and 163 bits. For group operations, a finite-field arithmetic operation, e.g. multiplication, is designed on a polynomial basis. The delay of a 233-bit point multiplication is only 3.05 and 3.56 μs, in a Xilinx Virtex-7 FPGA, for Koblitz and random curves, respectively, and 0.81 μs in an ASIC 65-nm technology, which are the fastest hardware implementation results reported in the literature to date. In addition, a 163-bit point multiplication is also implemented in FPGA and ASIC for fair comparison which takes around 0.33 and 0.46 μs, respectively. The area-time product of the proposed point multiplication is very low compared to similar designs. The performance ([Formula: see text] and Area × Time × Energy (ATE product of the proposed design are far better than the most significant studies found in the literature.

  15. Parallel point-multiplication architecture using combined group operations for high-speed cryptographic applications.

    Science.gov (United States)

    Hossain, Md Selim; Saeedi, Ehsan; Kong, Yinan

    2017-01-01

    In this paper, we propose a novel parallel architecture for fast hardware implementation of elliptic curve point multiplication (ECPM), which is the key operation of an elliptic curve cryptography processor. The point multiplication over binary fields is synthesized on both FPGA and ASIC technology by designing fast elliptic curve group operations in Jacobian projective coordinates. A novel combined point doubling and point addition (PDPA) architecture is proposed for group operations to achieve high speed and low hardware requirements for ECPM. It has been implemented over the binary field which is recommended by the National Institute of Standards and Technology (NIST). The proposed ECPM supports two Koblitz and random curves for the key sizes 233 and 163 bits. For group operations, a finite-field arithmetic operation, e.g. multiplication, is designed on a polynomial basis. The delay of a 233-bit point multiplication is only 3.05 and 3.56 μs, in a Xilinx Virtex-7 FPGA, for Koblitz and random curves, respectively, and 0.81 μs in an ASIC 65-nm technology, which are the fastest hardware implementation results reported in the literature to date. In addition, a 163-bit point multiplication is also implemented in FPGA and ASIC for fair comparison which takes around 0.33 and 0.46 μs, respectively. The area-time product of the proposed point multiplication is very low compared to similar designs. The performance ([Formula: see text]) and Area × Time × Energy (ATE) product of the proposed design are far better than the most significant studies found in the literature.

  16. Pointing to "That": Deixis and Shared Intentionality in Young Children's Collaborative Group Work

    Science.gov (United States)

    Murphy, Carol

    2014-01-01

    In this article I present examples of young children's interaction in collaborative group work in mathematics and consider how the children shared intentions, that is, how they influenced the thinking of another. By analysing the children's use of deixis as an aspect of indexicality, I examined how the students pointed out mathematical…

  17. 75 FR 27119 - ViewPoint Financial Group, Inc., Plano, Texas; Approval of Conversion Application

    Science.gov (United States)

    2010-05-13

    ... DEPARTMENT OF THE TREASURY Office of Thrift Supervision [AC-37: OTS No. H-47111] ViewPoint Financial Group, Inc., Plano, Texas; Approval of Conversion Application Notice is hereby given that on May 6..., Plano, Texas, to convert to the stock form of organization. Copies of the application are available for...

  18. Point group invariants in the Uqp(u(2)) quantum algebra picture

    International Nuclear Information System (INIS)

    Kibler, M.

    1993-07-01

    Some consequences of a qp-quantization of a point group invariant developed in the enveloping algebra of SU(2) are examined. A set of open problems concerning such invariants in the U qp (u(2)) quantum algebra picture is briefly discussed. (author) 18 refs

  19. The Lagrangian Map and Lie Symmetries in Magnetohydrodynamics and Gas Dynamics

    Science.gov (United States)

    Ko, C. M.; Webb, G. M.; Ratkiewicz, R. E.; Zank, G. P.

    2007-12-01

    We explore the role of the Lagrangian map for Lie symmetries in magnetohydrodynamics and gas dynamics. By converting the Eulerian Lie point symmetries of the Galilean group to Lagrange label space, in which the Eulerian position is regarded as a function of the Lagrange fluid label and time t, one finds that there is an infinite class of symmetries in Lagrange label space that map onto each Lie point symmetry. This involves the solution of the Lie determining equations for the fluid relabeling symmetries. We also consider a class of scaling symmetries for a gas with a constant adiabatic index. These symmetries map onto a modified form of the fluid relabeling symmetry determining equations with non-zero source terms. We investigate under what conditions the scaling symmetries give rise to conservation laws, and find that the conservation laws depend on the initial entropy, density and magnetic field of the fluid. Lie algebraic structures in Lagrange label space corresponding to the symmetries are investigated.

  20. An accurate solution of point reactor neutron kinetics equations of multi-group of delayed neutrons

    International Nuclear Information System (INIS)

    Yamoah, S.; Akaho, E.H.K.; Nyarko, B.J.B.

    2013-01-01

    Highlights: ► Analytical solution is proposed to solve the point reactor kinetics equations (PRKE). ► The method is based on formulating a coefficient matrix of the PRKE. ► The method was applied to solve the PRKE for six groups of delayed neutrons. ► Results shows good agreement with other traditional methods in literature. ► The method is accurate and efficient for solving the point reactor kinetics equations. - Abstract: The understanding of the time-dependent behaviour of the neutron population in a nuclear reactor in response to either a planned or unplanned change in the reactor conditions is of great importance to the safe and reliable operation of the reactor. In this study, an accurate analytical solution of point reactor kinetics equations with multi-group of delayed neutrons for specified reactivity changes is proposed to calculate the change in neutron density. The method is based on formulating a coefficient matrix of the homogenous differential equations of the point reactor kinetics equations and calculating the eigenvalues and the corresponding eigenvectors of the coefficient matrix. A small time interval is chosen within which reactivity relatively stays constant. The analytical method was applied to solve the point reactor kinetics equations with six-groups delayed neutrons for a representative thermal reactor. The problems of step, ramp and temperature feedback reactivities are computed and the results compared with other traditional methods. The comparison shows that the method presented in this study is accurate and efficient for solving the point reactor kinetics equations of multi-group of delayed neutrons

  1. Projective symmetry of partons in Kitaev's honeycomb model

    Science.gov (United States)

    Mellado, Paula

    2015-03-01

    Low-energy states of quantum spin liquids are thought to involve partons living in a gauge-field background. We study the spectrum of Majorana fermions of Kitaev's honeycomb model on spherical clusters. The gauge field endows the partons with half-integer orbital angular momenta. As a consequence, the multiplicities reflect not the point-group symmetries of the cluster, but rather its projective symmetries, operations combining physical and gauge transformations. The projective symmetry group of the ground state is the double cover of the point group. We acknowledge Fondecyt under Grant No. 11121397, Conicyt under Grant No. 79112004, and the Simons Foundation (P.M.); the Max Planck Society and the Alexander von Humboldt Foundation (O.P.); and the US DOE Grant No. DE-FG02-08ER46544 (O.T.).

  2. Current algebras, measures quasi-invariant under diffeomorphism groups, and infinite quantum systems with accumulation points

    Science.gov (United States)

    Sakuraba, Takao

    The approach to quantum physics via current algebra and unitary representations of the diffeomorphism group is established. This thesis studies possible infinite Bose gas systems using this approach. Systems of locally finite configurations and systems of configurations with accumulation points are considered, with the main emphasis on the latter. In Chapter 2, canonical quantization, quantization via current algebra and unitary representations of the diffeomorphism group are reviewed. In Chapter 3, a new definition of the space of configurations is proposed and an axiom for general configuration spaces is abstracted. Various subsets of the configuration space, including those specifying the number of points in a Borel set and those specifying the number of accumulation points in a Borel set are proved to be measurable using this axiom. In Chapter 4, known results on the space of locally finite configurations and Poisson measure are reviewed in the light of the approach developed in Chapter 3, including the approach to current algebra in the Poisson space by Albeverio, Kondratiev, and Rockner. Goldin and Moschella considered unitary representations of the group of diffeomorphisms of the line based on self-similar random processes, which may describe infinite quantum gas systems with clusters. In Chapter 5, the Goldin-Moschella theory is developed further. Their construction of measures quasi-invariant under diffeomorphisms is reviewed, and a rigorous proof of their conjectures is given. It is proved that their measures with distinct correlation parameters are mutually singular. A quasi-invariant measure constructed by Ismagilov on the space of configurations with accumulation points on the circle is proved to be singular with respect to the Goldin-Moschella measures. Finally a generalization of the Goldin-Moschella measures to the higher-dimensional case is studied, where the notion of covariance matrix and the notion of condition number play important roles. A

  3. Molecular symmetry and spectroscopy

    CERN Document Server

    Bunker, Philip; Jensen, Per

    2006-01-01

    The first edition, by P.R. Bunker, published in 1979, remains the sole textbook that explains the use of the molecular symmetry group in understanding high resolution molecular spectra. Since 1979 there has been considerable progress in the field and a second edition is required; the original author has been joined in its writing by Per Jensen. The Material of the first edition has been reorganized and much has been added. The molecular symmetry group is now introduced early on, and the explanation of how to determine nuclear spin statistical weights has been consolidated in one chapter, after groups, symmetry groups, character tables and the Hamiltonian have been introduced. A description of the symmetry in the three-dimensional rotation group K(spatial), irreducible spherical tensor operators, and vector coupling coefficients is now included. The chapters on energy levels and selection rules contain a great deal of material that was not in the first edition (much of it was undiscovered in 1979), concerning ...

  4. An introduction to Yangian symmetries

    International Nuclear Information System (INIS)

    Bernard, D.

    1992-01-01

    Some aspects of the quantum Yangians as symmetry algebras of two-dimensional quantum field theories are reviewed. They include two main issues: the first is the classical Heisenberg model, covering non-Abelian symmetries, generators of the symmetries and the semi-classical Yangians, an alternative presentation of the semi-classical Yangians, digression on Poisson-Lie groups. The second is the quantum Heisenberg chain, covering non-Abelian symmetries and the quantum Yangians, the transfer matrix and an alternative presentation of the Yangians, digression on the double Yangians. (K.A.) 15 refs

  5. Breaking Symmetries

    Directory of Open Access Journals (Sweden)

    Kirstin Peters

    2010-11-01

    Full Text Available A well-known result by Palamidessi tells us that πmix (the π-calculus with mixed choice is more expressive than πsep (its subset with only separate choice. The proof of this result argues with their different expressive power concerning leader election in symmetric networks. Later on, Gorla offered an arguably simpler proof that, instead of leader election in symmetric networks, employed the reducibility of incestual processes (mixed choices that include both enabled senders and receivers for the same channel when running two copies in parallel. In both proofs, the role of breaking (initial symmetries is more or less apparent. In this paper, we shed more light on this role by re-proving the above result - based on a proper formalization of what it means to break symmetries without referring to another layer of the distinguishing problem domain of leader election. Both Palamidessi and Gorla rephrased their results by stating that there is no uniform and reasonable encoding from πmix into πsep. We indicate how the respective proofs can be adapted and exhibit the consequences of varying notions of uniformity and reasonableness. In each case, the ability to break initial symmetries turns out to be essential.

  6. Spinor Structure and Internal Symmetries

    Science.gov (United States)

    Varlamov, V. V.

    2015-10-01

    Spinor structure 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. 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 Poincaré 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 is established. The introduced spin-mass formula and its combination with Gell-Mann-Okubo mass formula allows one to take a new look at the problem of mass spectrum of elementary particles.

  7. Point of care testing of phospholipase A2 group IIA for serological diagnosis of rheumatoid arthritis

    Science.gov (United States)

    Liu, Nathan J.; Chapman, Robert; Lin, Yiyang; Mmesi, Jonas; Bentham, Andrew; Tyreman, Matthew; Abraham, Sonya; Stevens, Molly M.

    2016-02-01

    Secretory phospholipase A2 group IIA (sPLA2-IIA) was examined as a point of care marker for determining disease activity in rheumatoid (RA) and psoriatic (PsA) arthritis. Serum concentration and activity of sPLA2-IIA were measured using in-house antibodies and a novel point of care lateral flow device assay in patients diagnosed with varying severities of RA (n = 30) and PsA (n = 25) and found to correlate strongly with C-reactive protein (CRP). Levels of all markers were elevated in patients with active RA over those with inactive RA as well as both active and inactive PsA, indicating that sPLA2-IIA can be used as an analogue to CRP for RA diagnosis at point of care.Secretory phospholipase A2 group IIA (sPLA2-IIA) was examined as a point of care marker for determining disease activity in rheumatoid (RA) and psoriatic (PsA) arthritis. Serum concentration and activity of sPLA2-IIA were measured using in-house antibodies and a novel point of care lateral flow device assay in patients diagnosed with varying severities of RA (n = 30) and PsA (n = 25) and found to correlate strongly with C-reactive protein (CRP). Levels of all markers were elevated in patients with active RA over those with inactive RA as well as both active and inactive PsA, indicating that sPLA2-IIA can be used as an analogue to CRP for RA diagnosis at point of care. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr08423g

  8. Givental Graphs and Inversion Symmetry

    NARCIS (Netherlands)

    Dunin-Barkovskiy, P.; Shadrin, S.; Spitz, L.

    2013-01-01

    Inversion symmetry is a very non-trivial discrete symmetry of Frobenius manifolds. It was obtained by Dubrovin from one of the elementary Schlesinger transformations of a special ODE associated to a Frobenius manifold. In this paper, we review the Givental group action on Frobenius manifolds in

  9. Charged fluids with symmetries

    Indian Academy of Sciences (India)

    conformal Killing vector on the electromagnetic field tensor and the role of Maxwell's equations. 2. Conformal symmetries. Manifolds with structure may admit groups of transformations which preserve this struc- ture. A conformal motion preserves the metric up to a factor and maps null geodesics conformally. A conformal ...

  10. SYMMETRY OF COMPOSITE CRYSTALS

    NARCIS (Netherlands)

    VANSMAALEN, S

    1991-01-01

    Composite crystals are crystals that consist of two or more subsystems, in first approximation each one having its own three-dimensional periodicity. The symmetry of these subsystems is then characterized by an ordinary space group. Due to their mutual interaction the true structure consists of a

  11. Integrating biological motion: the role of grouping in the perception of point-light actions.

    Directory of Open Access Journals (Sweden)

    Ervin Poljac

    Full Text Available The human visual system is highly sensitive to biological motion and manages to organize even a highly reduced point-light stimulus into a vivid percept of human action. The current study investigated to what extent the origin of this saliency of point-light displays is related to its intrinsic Gestalt qualities. In particular, we studied whether biological motion perception is facilitated when the elements can be grouped according to good continuation and similarity as Gestalt principles of perceptual organization. We found that both grouping principles enhanced biological motion perception but their effects differed when stimuli were inverted. These results provide evidence that Gestalt principles of good continuity and similarity also apply to more complex and dynamic meaningful stimuli.

  12. Numerical solution of multi groups point kinetic equations by simulink toolbox of Matlab software

    International Nuclear Information System (INIS)

    Hadad, K.; Mohamadi, A.; Sabet, H.; Ayobian, N.; Khani, M.

    2004-01-01

    The simulink toolbox of Matlab Software was employed to solve the point kinetics equation with six group delayed neutrons. The method of Adams-Bash ford showed a good convergence in solving the system of simultaneous equations and the obtained results showed good agreements with other numerical schemes. The flexibility of the package in changing the system parameters and the user friendly interface makes this approach a reliable educational package in revealing the affects of reactivity changes on power incursions

  13. Rigidity and symmetry

    CERN Document Server

    Weiss, Asia; Whiteley, Walter

    2014-01-01

    This book contains recent contributions to the fields of rigidity and symmetry with two primary focuses: to present the mathematically rigorous treatment of rigidity of structures, and to explore the interaction of geometry, algebra, and combinatorics. Overall, the book shows how researchers from diverse backgrounds explore connections among the various discrete structures with symmetry as the unifying theme.  Contributions present recent trends and advances in discrete geometry, particularly in the theory of polytopes. The rapid development of abstract polytope theory has resulted in a rich theory featuring an attractive interplay of methods and tools from discrete geometry, group theory, classical geometry, hyperbolic geometry and topology.  The volume will also be a valuable source as an introduction to the ideas of both combinatorial and geometric rigidity theory and its applications, incorporating the surprising impact of symmetry. It will appeal to students at both the advanced undergraduate and gradu...

  14. ISO(4,1) symmetry in the EFT of inflation

    Energy Technology Data Exchange (ETDEWEB)

    Creminelli, Paolo [Abdus Salam International Centre for Theoretical Physics, Strada Costiera 11, 34151, Trieste (Italy); Emami, Razieh [School of Physics, Institute for Research in Fundamental Sciences (IPM), P. O. Box 19395-5531, Teheran (Iran, Islamic Republic of); Simonović, Marko; Trevisan, Gabriele, E-mail: creminel@ictp.it, E-mail: emami@mail.ipm.ir, E-mail: msimonov@sissa.it, E-mail: gtrevi@sissa.it [Scuola Internazionale Superiore di Studi Avanzati (SISSA), via Bonomea 265, 34136, Trieste (Italy)

    2013-07-01

    In DBI inflation the cubic action is a particular linear combination of the two, otherwise independent, cubic operators π-dot {sup 3} and π-dot (∂{sub i}π){sup 2}. We show that in the Effective Field Theory (EFT) of inflation this is a consequence of an approximate 5D Poincar and apos;e symmetry, ISO(4,1), non-linearly realized by the Goldstone π. This symmetry uniquely fixes, at lowest order in derivatives, all correlation functions in terms of the speed of sound c{sub s}. In the limit c{sub s} → 1, the ISO(4,1) symmetry reduces to the Galilean symmetry acting on π. On the other hand, we point out that the non-linear realization of SO(4,2), the isometry group of 5D AdS space, does not fix the cubic action in terms of c{sub s}.

  15. Experimental probes of emergent symmetries in the quantum Hall system

    CERN Document Server

    Lutken, C A

    2011-01-01

    Experiments studying renormalization group flows in the quantum Hall system provide significant evidence for the existence of an emergent holomorphic modular symmetry Gamma(0)(2). We briefly review this evidence and show that, for the lowest temperatures, the experimental determination of the position of the quantum critical points agrees to the parts per mille level with the prediction from Gamma(0)(2). We present evidence that experiments giving results that deviate substantially from the symmetry predictions are not cold enough to be in the quantum critical domain. We show how the modular symmetry extended by a non-holomorphic particle hole duality leads to an extensive web of dualities related to those in plateau insulator transitions, and we derive a formula relating dual pairs (B, B(d)) of magnetic field strengths across any transition. The experimental data obtained for the transition studied so far is in excellent agreement with the duality relations following from this emergent symmetry, and rule out...

  16. Symmetry and physical properties of crystals

    CERN Document Server

    Malgrange, Cécile; Schlenker, Michel

    2014-01-01

    Crystals are everywhere, from natural crystals (minerals) through the semiconductors and magnetic materials in electronic devices and computers or piezoelectric resonators at the heart of our quartz watches to electro-optical devices. Understanding them in depth is essential both for pure research and for their applications. This book provides a clear, thorough presentation of their symmetry, both at the microscopic space-group level and the macroscopic point-group level. The implications of the symmetry of crystals for their physical properties are then presented, together with their mathematical description in terms of tensors. The conditions on the symmetry of a crystal for a given property to exist then become clear, as does the symmetry of the property. The geometrical representation of tensor quantities or properties is presented, and its use in determining important relationships emphasized. An original feature of this book is that most chapters include exercises with complete solutions. This all...

  17. A symmetry model for genetic coding via a wallpaper group composed of the traditional four bases and an imaginary base E: towards category theory-like systematization of molecular/genetic biology.

    Science.gov (United States)

    Sawamura, Jitsuki; Morishita, Shigeru; Ishigooka, Jun

    2014-05-07

    Previously, we suggested prototypal models that describe some clinical states based on group postulates. Here, we demonstrate a group/category theory-like model for molecular/genetic biology as an alternative application of our previous model. Specifically, we focus on deoxyribonucleic acid (DNA) base sequences. We construct a wallpaper pattern based on a five-letter cruciform motif with letters C, A, T, G, and E. Whereas the first four letters represent the standard DNA bases, the fifth is introduced for ease in formulating group operations that reproduce insertions and deletions of DNA base sequences. A basic group Z5 = {r, u, d, l, n} of operations is defined for the wallpaper pattern, with which a sequence of points can be generated corresponding to changes of a base in a DNA sequence by following the orbit of a point of the pattern under operations in group Z5. Other manipulations of DNA sequence can be treated using a vector-like notation 'Dj' corresponding to a DNA sequence but based on the five-letter base set; also, 'Dj's are expressed graphically. Insertions and deletions of a series of letters 'E' are admitted to assist in describing DNA recombination. Likewise, a vector-like notation Rj can be constructed for sequences of ribonucleic acid (RNA). The wallpaper group B = {Z5×∞, ●} (an ∞-fold Cartesian product of Z5) acts on Dj (or Rj) yielding changes to Dj (or Rj) denoted by 'Dj◦B(j→k) = Dk' (or 'Rj◦B(j→k) = Rk'). Based on the operations of this group, two types of groups-a modulo 5 linear group and a rotational group over the Gaussian plane, acting on the five bases-are linked as parts of the wallpaper group for broader applications. As a result, changes, insertions/deletions and DNA (RNA) recombination (partial/total conversion) are described. As an exploratory study, a notation for the canonical "central dogma" via a category theory-like way is presented for future developments. Despite the large incompleteness of our

  18. Discrete symmetries in the MSSM

    Energy Technology Data Exchange (ETDEWEB)

    Schieren, Roland

    2010-12-02

    The use of discrete symmetries, especially abelian ones, in physics beyond the standard model of particle physics is discussed. A method is developed how a general, abelian, discrete symmetry can be obtained via spontaneous symmetry breaking. In addition, anomalies are treated in the path integral approach with special attention to anomaly cancellation via the Green-Schwarz mechanism. All this is applied to the minimal supersymmetric standard model. A unique Z{sup R}{sub 4} symmetry is discovered which solves the {mu}-problem as well as problems with proton decay and allows to embed the standard model gauge group into a simple group, i.e. the Z{sup R}{sub 4} is compatible with grand unification. Also the flavor problem in the context of minimal flavor violation is addressed. Finally, a string theory model is presented which exhibits the mentioned Z{sup R}{sub 4} symmetry and other desirable features. (orig.)

  19. Triple Point Topological Metals

    Directory of Open Access Journals (Sweden)

    Ziming Zhu

    2016-07-01

    Full Text Available Topologically protected fermionic quasiparticles appear in metals, where band degeneracies occur at the Fermi level, dictated by the band structure topology. While in some metals these quasiparticles are direct analogues of elementary fermionic particles of the relativistic quantum field theory, other metals can have symmetries that give rise to quasiparticles, fundamentally different from those known in high-energy physics. Here, we report on a new type of topological quasiparticles—triple point fermions—realized in metals with symmorphic crystal structure, which host crossings of three bands in the vicinity of the Fermi level protected by point group symmetries. We find two topologically different types of triple point fermions, both distinct from any other topological quasiparticles reported to date. We provide examples of existing materials that host triple point fermions of both types and discuss a variety of physical phenomena associated with these quasiparticles, such as the occurrence of topological surface Fermi arcs, transport anomalies, and topological Lifshitz transitions.

  20. VOXEL- AND GRAPH-BASED POINT CLOUD SEGMENTATION OF 3D SCENES USING PERCEPTUAL GROUPING LAWS

    Directory of Open Access Journals (Sweden)

    Y. Xu

    2017-05-01

    Full Text Available Segmentation is the fundamental step for recognizing and extracting objects from point clouds of 3D scene. In this paper, we present a strategy for point cloud segmentation using voxel structure and graph-based clustering with perceptual grouping laws, which allows a learning-free and completely automatic but parametric solution for segmenting 3D point cloud. To speak precisely, two segmentation methods utilizing voxel and supervoxel structures are reported and tested. The voxel-based data structure can increase efficiency and robustness of the segmentation process, suppressing the negative effect of noise, outliers, and uneven points densities. The clustering of voxels and supervoxel is carried out using graph theory on the basis of the local contextual information, which commonly conducted utilizing merely pairwise information in conventional clustering algorithms. By the use of perceptual laws, our method conducts the segmentation in a pure geometric way avoiding the use of RGB color and intensity information, so that it can be applied to more general applications. Experiments using different datasets have demonstrated that our proposed methods can achieve good results, especially for complex scenes and nonplanar surfaces of objects. Quantitative comparisons between our methods and other representative segmentation methods also confirms the effectiveness and efficiency of our proposals.

  1. - and Graph-Based Point Cloud Segmentation of 3d Scenes Using Perceptual Grouping Laws

    Science.gov (United States)

    Xu, Y.; Hoegner, L.; Tuttas, S.; Stilla, U.

    2017-05-01

    Segmentation is the fundamental step for recognizing and extracting objects from point clouds of 3D scene. In this paper, we present a strategy for point cloud segmentation using voxel structure and graph-based clustering with perceptual grouping laws, which allows a learning-free and completely automatic but parametric solution for segmenting 3D point cloud. To speak precisely, two segmentation methods utilizing voxel and supervoxel structures are reported and tested. The voxel-based data structure can increase efficiency and robustness of the segmentation process, suppressing the negative effect of noise, outliers, and uneven points densities. The clustering of voxels and supervoxel is carried out using graph theory on the basis of the local contextual information, which commonly conducted utilizing merely pairwise information in conventional clustering algorithms. By the use of perceptual laws, our method conducts the segmentation in a pure geometric way avoiding the use of RGB color and intensity information, so that it can be applied to more general applications. Experiments using different datasets have demonstrated that our proposed methods can achieve good results, especially for complex scenes and nonplanar surfaces of objects. Quantitative comparisons between our methods and other representative segmentation methods also confirms the effectiveness and efficiency of our proposals.

  2. Continuous symmetry reduction and return maps for high-dimensional flows

    Science.gov (United States)

    Siminos, Evangelos; Cvitanović, Predrag

    2011-01-01

    We present two continuous symmetry reduction methods for reducing high-dimensional dissipative flows to local return maps. In the Hilbert polynomial basis approach, the equivariant dynamics is rewritten in terms of invariant coordinates. In the method of moving frames (or method of slices) the state space is sliced locally in such a way that each group orbit of symmetry-equivalent points is represented by a single point. In either approach, numerical computations can be performed in the original state space representation, and the solutions are then projected onto the symmetry-reduced state space. The two methods are illustrated by reduction of the complex Lorenz system, a five-dimensional dissipative flow with rotational symmetry. While the Hilbert polynomial basis approach appears unfeasible for high-dimensional flows, symmetry reduction by the method of moving frames offers hope.

  3. Flavor symmetry and topology change in nuclear symmetry energy for compact stars

    International Nuclear Information System (INIS)

    Lee, Hyun Kyu; Rho, Mannque

    2013-01-01

    The nuclear symmetry energy figures crucially in the structure of asymmetric nuclei and, more importantly, in the equation of state (EoS) of compact stars. At present it is almost totally unknown, both experimentally and theoretically, in the density regime appropriate for the interior of neutron stars. Basing on a strong-coupled structure of dense baryonic matter encoded in the skyrmion crystal approach with a topology change and resorting to the notion of generalized hidden local symmetry in hadronic interactions, we address a variety of hitherto unexplored issues of nuclear interactions associated with the symmetry energy, i.e., kaon condensation and hyperons, possible topology change in dense matter, nuclear tensor forces, conformal symmetry, chiral symmetry, etc., in the EoS of dense compact-star matter. One of the surprising results coming from HLS structure that is distinct from what is given by standard phenomenological approaches is that at high density, baryonic matter is driven by renormalization group flow to the 'dilaton-limit fixed point' constrained by 'mended symmetries'. We further propose how to formulate kaon condensation and hyperons in compact-star matter in a framework anchored on a single effective Lagrangian by treating hyperons as the Callan–Klebanov kaon-skyrmion bound states simulated on crystal lattice. This formulation suggests that hyperons can figure in the stellar matter — if at all — when or after kaons condense, in contrast to the standard phenomenological approaches where the hyperons appear as the first strangeness degree of freedom in matter, thereby suppressing or delaying kaon condensation. In our simplified description of the stellar structure in terms of symmetry energies, which is compatible with that of the 1.97 solar mass star, kaon condensation plays a role of 'doorway state' to strange quark matter. (author)

  4. Symmetry and quantum mechanics

    CERN Document Server

    Corry, Scott

    2016-01-01

    This book offers an introduction to quantum mechanics for professionals, students, and others in the field of mathematics who have a minimal background in physics with an understanding of linear algebra and group theory. It covers such topics as Lie groups, algebras and their representations, and analysis (Hilbert space, distributions, the spectral Theorem, and the Stone-Von Neumann Theorem). The book emphasizes the role of symmetry and is useful to physicists as it provides a mathematical introduction to the topic.

  5. Preferences for symmetry in human faces in two cultures: data from the UK and the Hadza, an isolated group of hunter-gatherers.

    Science.gov (United States)

    Little, Anthony C; Apicella, Coren L; Marlowe, Frank W

    2007-12-22

    Many studies show agreement within and between cultures for general judgements of facial attractiveness. Few studies, however, have examined the attractiveness of specific traits and few have examined preferences in hunter-gatherers. The current study examined preferences for symmetry in both the UK and the Hadza, a hunter-gatherer society of Tanzania. We found that symmetry was more attractive than asymmetry across both the cultures and was more strongly preferred by the Hadza than in the UK. The different ecological conditions may play a role in generating this difference. Such variation in preference may be adaptive if it reflects adaptation to local conditions. Symmetry is thought to indicate genetic quality, which may be more important among the Hadza with much higher mortality rates from birth onwards. Hadza men who were more often named as good hunters placed a greater value on symmetry in female faces. These results suggest that high quality Hadza men are more discriminating in their choice of faces. Hadza women had increased preferences for symmetry in men's faces when they were pregnant or nursing, perhaps due to their increased discrimination and sensitivity to foods and disease harmful to a foetus or nursing infant. These results imply that symmetry is an evolutionarily relevant trait and that variation in symmetry preference appears strategic both between cultures and within individuals of a single culture.

  6. Involution symmetries and the PMNS matrix

    Indian Academy of Sciences (India)

    Palash B Pal

    2017-10-09

    Oct 9, 2017 ... approach, advocated first by Lam [1], one starts by look- ing at the symmetries of the low-energy Lagrangian, and tries to see which group can contain these symmetries. The bigger symmetry might then determine the PMNS matrix, or at least some information about its elements. In this paper, we are going ...

  7. Geometrical symmetries in atomic nuclei: From theory predictions to experimental verifications

    International Nuclear Information System (INIS)

    Dudek, J; Molique, H; Curien, D; Góźdź, A

    2013-01-01

    In the lectures delivered at the 2012 Predeal School an overview has been presented of the contemporary theory of the nuclear geometrical (shape) symmetries. The formalism combines two most powerful theory tools applicable in the context: The group- and group-representation theory together with the modern realistic mean-field theory. We suggest that all point-groups of symmetry of the mean-field Hamiltonian, sufficiently rich in symmetry elements (as discussed in the text) may lead to the magic numbers that characterise such a group in analogy with the spherical magic gaps characterising nuclear sphericity. We discuss in simple terms the mathematical and physical arguments for the presence of such symmetries in nuclei. In our opinion: It is not so much the question of Whether? – but rather: Where in the Nuclear Chart several of the point group-symmetries will be seen? We focus our presentation on the tetrahedral symmetry with the magic numbers calculated to be 32, 40, 56, 64, 70, 90 and 136, and discuss qualitatively the problem of the formulation of the experimental criteria which would allow for the final discovery of the tetrahedral symmetry in subatomic physics.

  8. Floral guidance of learning a preference for symmetry by bumblebees.

    Science.gov (United States)

    Plowright, Catherine M S; Bridger, Jeremy J M; Xu, Vicki; Herlehy, Racheal A; Collin, Charles A

    2017-11-01

    This study examines the mechanism underlying one way in which bumblebees are known to develop a preference for symmetric patterns: through prior non-differential reinforcement on simple patterns (black discs and white discs). In three experiments, bees were given a choice among symmetric and asymmetric black-and-white non-rewarding patterns presented at the ends of corridors in a radial maze. Experimental groups had prior rewarded non-discrimination training on white patterns and black patterns, while control groups had no pre-test experience outside the colony. No preference for symmetry was obtained for any of the control groups. Prior training with circular patterns highlighting a horizontal axis of symmetry led to a specific subsequent preference for horizontal over vertical symmetry, while training with a vertical axis abolished this effect. Circles highlighting both axes created a general avoidance of asymmetry in favour of symmetric patterns with vertical, horizontal or both axes of symmetry. Training with plain circles, but not with deformed circles, led to a preference for symmetry: there was no evidence that the preference emerged just by virtue of having attention drawn away from irrelevant pattern differences. Our results point to a preference for symmetry developing gradually through first learning to extract an axis of symmetry from simple patterns and subsequently recognizing that axis in new patterns. They highlight the importance of continued learning through non-differential reinforcement by skilled foragers. Floral guides can function not only to guide pollinators to the source of reward but also to highlight an axis of symmetry for use in subsequent floral encounters.

  9. The central subgroup of the nonabelian tensor square of Bieberbach group of dimension three with point group C2 × C2

    Science.gov (United States)

    Ladi, Nor Fadzilah Abdul; Masri, Rohaidah; Idrus, Nor'ashiqin Mohd; Ting, Tan Yee

    2017-05-01

    Bieberbach groups are crystallographic groups. By computing the central subgroup of the nonabelian tensor square of a group, the properties of the group can be determined. In this paper, the central subgroup of the nonabelian tensor square of one Bieberbach group of dimension three with point group C2 × C2 is computed. In order to compute the ∇ (S3 (3)), the derived subgroup and the abelianization of the group are first constructed.

  10. Renormalization group equations and the Lifshitz point in noncommutative Landau-Ginsburg theory

    International Nuclear Information System (INIS)

    Chen, G.-H.; Wu, Y.-S.

    2002-01-01

    A one-loop renormalization group (RG) analysis is performed for noncommutative Landau-Ginsburg theory in an arbitrary dimension. We adopt a modern version of the Wilsonian RG approach, in which a shell integration in momentum space bypasses the potential IR singularities due to UV-IR mixing. The momentum-dependent trigonometric factors in interaction vertices, characteristic of noncommutative geometry, are marginal under RG transformations, and their marginality is preserved at one loop. A negative Θ-dependent anomalous dimension is discovered as a novel effect of the UV-IR mixing. We also found a noncommutative Wilson-Fisher (NCWF) fixed point in less than four dimensions. At large noncommutativity, a momentum space instability is induced by quantum fluctuations, and a consequential first-order phase transition is identified together with a Lifshitz point in the phase diagram. In the vicinity of the Lifshitz point, we introduce two critical exponents ν m and β k , whose values are determined to be 1/4 and 1/2, respectively, at mean-field level

  11. Point defects and composition in hexagonal group-III nitride monolayers: A first-principles calculation

    Science.gov (United States)

    Gao, Han; Ye, Han; Yu, Zhongyuan; Zhang, Yunzhen; Liu, Yumin; Li, Yinfeng

    2017-12-01

    In this paper, we systematically investigate the structural, electronic and magnetic properties of hexagonal group-III nitride monolayers with point defects and alloying on the basis of first-principles calculations. Six typical point defects including three vacancies and three antisites are modeled in pure AlN, GaN and InN monolayers. The defect-induced modifications of band gaps and magnetic properties are demonstrated. The vacancy of nitrogen, with lowest formation energy, metalizes the semiconducting nitride monolayers. The defects losing single group-III atom introduce net magnetic moment to the systems, while others maintain non-magnetic. For ordered alloy monolayers, the AlGaN and InGaN systems are taken into consideration. The compositional variation is achieved by atomic substitution in supercells with different sizes. We find that the lattice constant and cohesive energy follow good linear relation with concentration while a slight bowing effect is observed for the band gap. These results provide a development in defective and alloy nitride monolayers and extend the potential applications.

  12. Symmetry chains and adaptation coefficients

    International Nuclear Information System (INIS)

    Fritzer, H.P.; Gruber, B.

    1985-01-01

    Given a symmetry chain of physical significance it becomes necessary to obtain states which transform properly with respect to the symmetries of the chain. In this article we describe a method which permits us to calculate symmetry-adapted quantum states with relative ease. The coefficients for the symmetry-adapted linear combinations are obtained, in numerical form, in terms of the original states of the system and can thus be represented in the form of numerical tables. In addition, one also obtains automatically the matrix elements for the operators of the symmetry groups which are involved, and thus for any physical operator which can be expressed either as an element of the algebra or of the enveloping algebra. The method is well suited for computers once the physically relevant symmetry chain, or chains, have been defined. While the method to be described is generally applicable to any physical system for which semisimple Lie algebras play a role we choose here a familiar example in order to illustrate the method and to illuminate its simplicity. We choose the nuclear shell model for the case of two nucleons with orbital angular momentum l = 1. While the states of the entire shell transform like the smallest spin representation of SO(25) we restrict our attention to its subgroup SU(6) x SU(2)/sub T/. We determine the symmetry chains which lead to total angular momentum SU(2)/sub J/ and obtain the symmetry-adapted states for these chains

  13. Dual symmetry in gauge theories

    International Nuclear Information System (INIS)

    Koshkarov, A.L.

    1997-01-01

    Continuous dual symmetry in electrodynamics, Yang-Mills theory and gravitation is investigated. Dual invariant which leads to badly nonlinear motion equations is chosen as a Lagrangian of the pure classical dual nonlinear electrodynamics. In a natural manner some dual angle which is determined by the electromagnetic strengths at the point of the time-space appears in the model. Motion equations may well be interpreted as the equations of the standard Maxwell theory with source. Alternative interpretation is the quasi-Maxwell linear theory with magnetic charge. Analogous approach is possible in the Yang-Mills theory. In this case the dual-invariant non-Abelian theory motion equations possess the same instanton solutions as the conventional Yang-Mills equations have. An Abelian two-parameter dual group is found to exist in gravitation. Irreducible representations have been obtained: the curvature tensor was expanded into the sum of twice anti-self-dual and self-dual parts. Gravitational instantons are defined as (real )solutions to the usual duality equations. Central symmetry solutions to these equations are obtained. The twice anti-self-dual part of the curvature tensor may be used for introduction of new gravitational equations generalizing Einstein''s equations. However, the theory obtained reduces to the conformal-flat Nordstroem theory

  14. Critical Point Facility (CPE) Group in the Spacelab Payload Operations Control Center (SL POCC)

    Science.gov (United States)

    1992-01-01

    The primary payload for Space Shuttle Mission STS-42, launched January 22, 1992, was the International Microgravity Laboratory-1 (IML-1), a pressurized manned Spacelab module. The goal of IML-1 was to explore in depth the complex effects of weightlessness of living organisms and materials processing. Around-the-clock research was performed on the human nervous system's adaptation to low gravity and effects of microgravity on other life forms such as shrimp eggs, lentil seedlings, fruit fly eggs, and bacteria. Materials processing experiments were also conducted, including crystal growth from a variety of substances such as enzymes, mercury iodide, and a virus. The Huntsville Operations Support Center (HOSC) Spacelab Payload Operations Control Center (SL POCC) at the Marshall Space Flight Center (MSFC) was the air/ground communication channel used between the astronauts and ground control teams during the Spacelab missions. Featured is the Critical Point Facility (CPE) group in the SL POCC during STS-42, IML-1 mission.

  15. College grade point average as a personnel selection device: ethnic group differences and potential adverse impact.

    Science.gov (United States)

    Roth, P L; Bobko, P

    2000-06-01

    College grade point average (GPA) is often used in a variety of ways in personnel selection. Unfortunately, there is little empirical research literature in human resource management that informs researchers or practitioners about the magnitude of ethnic group differences and any potential adverse impact implications when using cumulative GPA for selection. Data from a medium-sized university in the Southeast (N = 7,498) indicate that the standardized average Black-White difference for cumulative GPA in the senior year is d = 0.78. The authors also conducted analyses at 3 GPA screens (3.00, 3.25, and 3.50) to demonstrate that employers (or educators) might face adverse impact at all 3 levels if GPA continues to be implemented as part of a selection system. Implications and future research are discussed.

  16. Detection and correction of underassigned rotational symmetry prior to structure deposition

    International Nuclear Information System (INIS)

    Poon, Billy K.; Grosse-Kunstleve, Ralf W.; Zwart, Peter H.; Sauter, Nicholas K.

    2010-01-01

    An X-ray structural model can be reassigned to a higher symmetry space group using the presented framework if its noncrystallographic symmetry operators are close to being exact crystallographic relationships. About 2% of structures in the Protein Data Bank can be reclassified in this way. Up to 2% of X-ray structures in the Protein Data Bank (PDB) potentially fit into a higher symmetry space group. Redundant protein chains in these structures can be made compatible with exact crystallographic symmetry with minimal atomic movements that are smaller than the expected range of coordinate uncertainty. The incidence of problem cases is somewhat difficult to define precisely, as there is no clear line between underassigned symmetry, in which the subunit differences are unsupported by the data, and pseudosymmetry, in which the subunit differences rest on small but significant intensity differences in the diffraction pattern. To help catch symmetry-assignment problems in the future, it is useful to add a validation step that operates on the refined coordinates just prior to structure deposition. If redundant symmetry-related chains can be removed at this stage, the resulting model (in a higher symmetry space group) can readily serve as an isomorphous replacement starting point for re-refinement using re-indexed and re-integrated raw data. These ideas are implemented in new software tools available at http://cci.lbl.gov/labelit

  17. Scale symmetry and virial theorem

    International Nuclear Information System (INIS)

    Westenholz, C. von

    1978-01-01

    Scale symmetry (or dilatation invariance) is discussed in terms of Noether's Theorem expressed in terms of a symmetry group action on phase space endowed with a symplectic structure. The conventional conceptual approach expressing invariance of some Hamiltonian under scale transformations is re-expressed in alternate form by infinitesimal automorphisms of the given symplectic structure. That is, the vector field representing scale transformations leaves the symplectic structure invariant. In this model, the conserved quantity or constant of motion related to scale symmetry is the virial. It is shown that the conventional virial theorem can be derived within this framework

  18. Chemical potential and reaction electronic flux in symmetry controlled reactions.

    Science.gov (United States)

    Vogt-Geisse, Stefan; Toro-Labbé, Alejandro

    2016-07-15

    In symmetry controlled reactions, orbital degeneracies among orbitals of different symmetries can occur along a reaction coordinate. In such case Koopmans' theorem and the finite difference approximation provide a chemical potential profile with nondifferentiable points. This results in an ill-defined reaction electronic flux (REF) profile, since it is defined as the derivative of the chemical potential with respect to the reaction coordinate. To overcome this deficiency, we propose a new way for the calculation of the chemical potential based on a many orbital approach, suitable for reactions in which symmetry is preserved. This new approach gives rise to a new descriptor: symmetry adapted chemical potential (SA-CP), which is the chemical potential corresponding to a given irreducible representation of a symmetry group. A corresponding symmetry adapted reaction electronic flux (SA-REF) is also obtained. Using this approach smooth chemical potential profiles and well defined REFs are achieved. An application of SA-CP and SA-REF is presented by studying the Cs enol-keto tautomerization of thioformic acid. Two SA-REFs are obtained, JA'(ξ) and JA'' (ξ). It is found that the tautomerization proceeds via an in-plane delocalized 3-center 4-electron O-H-S hypervalent bond which is predicted to exist only in the transition state (TS) region. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  19. How does symmetry impact the flexibility of proteins?

    Science.gov (United States)

    Schulze, Bernd; Sljoka, Adnan; Whiteley, Walter

    2014-02-13

    It is well known that (i) the flexibility and rigidity of proteins are central to their function, (ii) a number of oligomers with several copies of individual protein chains assemble with symmetry in the native state and (iii) added symmetry sometimes leads to added flexibility in structures. We observe that the most common symmetry classes of protein oligomers are also the symmetry classes that lead to increased flexibility in certain three-dimensional structures-and investigate the possible significance of this coincidence. This builds on the well-developed theory of generic rigidity of body-bar frameworks, which permits an analysis of the rigidity and flexibility of molecular structures such as proteins via fast combinatorial algorithms. In particular, we outline some very simple counting rules and possible algorithmic extensions that allow us to predict continuous symmetry-preserving motions in body-bar frameworks that possess non-trivial point-group symmetry. For simplicity, we focus on dimers, which typically assemble with twofold rotational axes, and often have allosteric function that requires motions to link distant sites on the two protein chains.

  20. Approximate Noether symmetries and collineations for regular perturbative Lagrangians

    Science.gov (United States)

    Paliathanasis, Andronikos; Jamal, Sameerah

    2018-01-01

    Regular perturbative Lagrangians that admit approximate Noether symmetries and approximate conservation laws are studied. Specifically, we investigate the connection between approximate Noether symmetries and collineations of the underlying manifold. In particular we determine the generic Noether symmetry conditions for the approximate point symmetries and we find that for a class of perturbed Lagrangians, Noether symmetries are related to the elements of the Homothetic algebra of the metric which is defined by the unperturbed Lagrangian. Moreover, we discuss how exact symmetries become approximate symmetries. Finally, some applications are presented.

  1. Chiral symmetry and chiral-symmetry breaking

    International Nuclear Information System (INIS)

    Peskin, M.E.

    1982-12-01

    These lectures concern the dynamics of fermions in strong interaction with gauge fields. Systems of fermions coupled by gauge forces have a very rich structure of global symmetries, which are called chiral symmetries. These lectures will focus on the realization of chiral symmetries and the causes and consequences of thier spontaneous breaking. A brief introduction to the basic formalism and concepts of chiral symmetry breaking is given, then some explicit calculations of chiral symmetry breaking in gauge theories are given, treating first parity-invariant and then chiral models. These calculations are meant to be illustrative rather than accurate; they make use of unjustified mathematical approximations which serve to make the physics more clear. Some formal constraints on chiral symmetry breaking are discussed which illuminate and extend the results of our more explicit analysis. Finally, a brief review of the phenomenological theory of chiral symmetry breaking is presented, and some applications of this theory to problems in weak-interaction physics are discussed

  2. Generic first-order phase transitions between isotropic and orientational phases with polyhedral symmetries

    Science.gov (United States)

    Liu, Ke; Greitemann, Jonas; Pollet, Lode

    2018-01-01

    Polyhedral nematics are examples of exotic orientational phases that possess a complex internal symmetry, representing highly nontrivial ways of rotational symmetry breaking, and are subject to current experimental pursuits in colloidal and molecular systems. The classification of these phases has been known for a long time; however, their transitions to the disordered isotropic liquid phase remain largely unexplored, except for a few symmetries. In this work, we utilize a recently introduced non-Abelian gauge theory to explore the nature of the underlying nematic-isotropic transition for all three-dimensional polyhedral nematics. The gauge theory can readily be applied to nematic phases with an arbitrary point-group symmetry, including those where traditional Landau methods and the associated lattice models may become too involved to implement owing to a prohibitive order-parameter tensor of high rank or (the absence of) mirror symmetries. By means of exhaustive Monte Carlo simulations, we find that the nematic-isotropic transition is generically first-order for all polyhedral symmetries. Moreover, we show that this universal result is fully consistent with our expectation from a renormalization group approach, as well as with other lattice models for symmetries already studied in the literature. We argue that extreme fine tuning is required to promote those transitions to second-order ones. We also comment on the nature of phase transitions breaking the O(3 ) symmetry in general cases.

  3. The presentation of the nonabelian tensor square of a Bieberbach group of dimension five with dihedral point group

    Science.gov (United States)

    Fauzi, Wan Nor Farhana Wan Mohd; Idrus, Nor'ashiqin Mohd; Masri, Rohaidah; Ting, Tan Yee; Sarmin, Nor Haniza; Hassim, Hazzirah Izzati Mat

    2014-12-01

    One of the homological functors of a group, is the nonabelian tensor square. It is important in the determination of the other homological functors of a group. In order to compute the nonabelian tensor square, we need to get its independent generators and its presentation. In this paper, we present the calculation of getting the presentation of the nonabelian tensor square of the group. The presentation is computed based on its independent generators by using the polycyclic method.

  4. Geometry and symmetry

    CERN Document Server

    Yale, Paul B

    2012-01-01

    This book is an introduction to the geometry of Euclidean, affine, and projective spaces with special emphasis on the important groups of symmetries of these spaces. The two major objectives of the text are to introduce the main ideas of affine and projective spaces and to develop facility in handling transformations and groups of transformations. Since there are many good texts on affine and projective planes, the author has concentrated on the n-dimensional cases.Designed to be used in advanced undergraduate mathematics or physics courses, the book focuses on ""practical geometry,"" emphasi

  5. Perception of Mirror Symmetry in Autism Spectrum Disorders

    Science.gov (United States)

    Falter, Christine M.; Bailey, Anthony J.

    2012-01-01

    Gestalt grouping in autism spectrum disorders (ASD) is selectively impaired for certain organization principles but for not others. Symmetry is a fundamental Gestalt principle characterizing many biological shapes. Sensitivity to symmetry was tested using the Picture Symmetry Test, which requires finding symmetry lines on pictures. Individuals…

  6. Statistical symmetries of the Lundgren-Monin-Novikov hierarchy.

    Science.gov (United States)

    Wacławczyk, Marta; Staffolani, Nicola; Oberlack, Martin; Rosteck, Andreas; Wilczek, Michael; Friedrich, Rudolf

    2014-07-01

    It was shown by Oberlack and Rosteck [Discr. Cont. Dyn. Sys. S, 3, 451 2010] that the infinite set of multipoint correlation (MPC) equations of turbulence admits a considerable extended set of Lie point symmetries compared to the Galilean group, which is implied by the original set of equations of fluid mechanics. Specifically, a new scaling group and an infinite set of translational groups of all multipoint correlation tensors have been discovered. These new statistical groups have important consequences for our understanding of turbulent scaling laws as they are essential ingredients of, e.g., the logarithmic law of the wall and other scaling laws, which in turn are exact solutions of the MPC equations. In this paper we first show that the infinite set of translational groups of all multipoint correlation tensors corresponds to an infinite dimensional set of translations under which the Lundgren-Monin-Novikov (LMN) hierarchy of equations for the probability density functions (PDF) are left invariant. Second, we derive a symmetry for the LMN hierarchy which is analogous to the scaling group of the MPC equations. Most importantly, we show that this symmetry is a measure of the intermittency of the velocity signal and the transformed functions represent PDFs of an intermittent (i.e., turbulent or nonturbulent) flow. Interesting enough, the positivity of the PDF puts a constraint on the group parameters of both shape and intermittency symmetry, leading to two conclusions. First, the latter symmetries may no longer be Lie group as under certain conditions group properties are violated, but still they are symmetries of the LMN equations. Second, as the latter two symmetries in its MPC versions are ingredients of many scaling laws such as the log law, the above constraints implicitly put weak conditions on the scaling parameter such as von Karman constant κ as they are functions of the group parameters. Finally, let us note that these kind of statistical symmetries are

  7. Broken Symmetry

    CERN Multimedia

    CERN. Geneva

    2011-01-01

    - 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 quant...

  8. 4D Pyritohedral Symmetry

    Directory of Open Access Journals (Sweden)

    Nazife O. Koca

    2016-12-01

    Full Text Available We describe an extension of the pyritohedral symmetry in 3D to 4-dimensional Euclidean space and construct the group elements of the 4D pyritohedral group of order 576 in terms of quaternions. It turns out that it is a maximal subgroup of both the rank-4 Coxeter groups W (F4 and W (H4, implying that it is a group relevant to the crystallographic as well as quasicrystallographic structures in 4-dimensions. We derive the vertices of the 24 pseudoicosahedra, 24 tetrahedra and the 96 triangular pyramids forming the facets of the pseudo snub 24-cell. It turns out that the relevant lattice is the root lattice of W (D4. The vertices of the dual polytope of the pseudo snub 24-cell consists of the union of three sets: 24-cell, another 24-cell and a new pseudo snub 24-cell. We also derive a new representation for the symmetry group of the pseudo snub 24-cell and the corresponding vertices of the polytopes.

  9. Paying Attention to Symmetry

    OpenAIRE

    Kootstra, Gert; Nederveen, Arco; de Boer, Bart

    2008-01-01

    Humans are very sensitive to symmetry in visual patterns. Symmetry is detected and recognized very rapidly. While viewing symmetrical patterns eye fixations are concentrated along the axis of symmetry or the symmetrical center of the patterns. This suggests that symmetry is a highly salient feature. Existing computational models of saliency, however, have mainly focused on contrast as a measure of saliency. These models do not take symmetry into account. In this paper, we discuss local symmet...

  10. Building Point Detection from Vehicle-Borne LiDAR Data Based on Voxel Group and Horizontal Hollow Analysis

    Directory of Open Access Journals (Sweden)

    Yu Wang

    2016-05-01

    Full Text Available Information extraction and three-dimensional (3D reconstruction of buildings using the vehicle-borne laser scanning (VLS system is significant for many applications. Extracting LiDAR points, from VLS, belonging to various types of building in large-scale complex urban environments still retains some problems. In this paper, a new technical framework for automatic and efficient building point extraction is proposed, including three main steps: (1 voxel group-based shape recognition; (2 category-oriented merging; and (3 building point identification by horizontal hollow ratio analysis. This article proposes a concept of “voxel group” based on the voxelization of VLS points: each voxel group is composed of several voxels that belong to one single real-world object. Then the shapes of point clouds in each voxel group are recognized and this shape information is utilized to merge voxel group. This article puts forward a characteristic nature of vehicle-borne LiDAR building points, called “horizontal hollow ratio”, for efficient extraction. Experiments are analyzed from two aspects: (1 building-based evaluation for overall experimental area; and (2 point-based evaluation for individual building using the completeness and correctness. The experimental results indicate that the proposed framework is effective for the extraction of LiDAR points belonging to various types of buildings in large-scale complex urban environments.

  11. Integrating Biological Motion: The Role of Grouping in the Perception of Point-Light Actions

    NARCIS (Netherlands)

    Poljac, E.; Verfaillie, K.; Wagemans, J.

    2011-01-01

    The human visual system is highly sensitive to biological motion and manages to organize even a highly reduced point-light stimulus into a vivid percept of human action. The current study investigated to what extent the origin of this saliency of point-light displays is related to its intrinsic

  12. Reflection symmetry-integrated image segmentation.

    Science.gov (United States)

    Sun, Yu; Bhanu, Bir

    2012-09-01

    This paper presents a new symmetry-integrated region-based image segmentation method. The method is developed to obtain improved image segmentation by exploiting image symmetry. It is realized by constructing a symmetry token that can be flexibly embedded into segmentation cues. Interesting points are initially extracted from an image by the SIFT operator and they are further refined for detecting the global bilateral symmetry. A symmetry affinity matrix is then computed using the symmetry axis and it is used explicitly as a constraint in a region growing algorithm in order to refine the symmetry of the segmented regions. A multi-objective genetic search finds the segmentation result with the highest performance for both segmentation and symmetry, which is close to the global optimum. The method has been investigated experimentally in challenging natural images and images containing man-made objects. It is shown that the proposed method outperforms current segmentation methods both with and without exploiting symmetry. A thorough experimental analysis indicates that symmetry plays an important role as a segmentation cue, in conjunction with other attributes like color and texture.

  13. A molecular symmetry analysis of the electronic states and transition dipole moments for molecules with two torsional degrees of freedom

    Energy Technology Data Exchange (ETDEWEB)

    Obaid, R. [Institut für Theoretische Chemie, Universität Wien, Währinger Straße 17, 1090 Vienna (Austria); Applied Chemistry Department, Palestine Polytechnic University, Hebron, Palestine (Country Unknown); Leibscher, M., E-mail: monika.leibscher@itp.uni-hannover.de [Institut für Theoretische Physik, Leibniz Universität Hannover, Appelstr. 2, 30167 Hannover (Germany)

    2015-02-14

    We present a molecular symmetry analysis of electronic states and transition dipole moments for molecules which undergo large amplitude intramolecular torsions. The method is based on the correlation between the point group of the molecule at highly symmetric configurations and the molecular symmetry group. As an example, we determine the global irreducible representations of the electronic states and transition dipole moments for the quinodimethane derivative 2-[4-(cyclopenta-2,4-dien-1-ylidene)cyclohexa-2,5-dien-1-ylidene]-2H-1, 3-dioxole for which two torsional degrees of freedom can be activated upon photo-excitation and construct the resulting symmetry adapted transition dipole functions.

  14. Exploiting Symmetry on Parallel Architectures.

    Science.gov (United States)

    Stiller, Lewis Benjamin

    1995-01-01

    This thesis describes techniques for the design of parallel programs that solve well-structured problems with inherent symmetry. Part I demonstrates the reduction of such problems to generalized matrix multiplication by a group-equivariant matrix. Fast techniques for this multiplication are described, including factorization, orbit decomposition, and Fourier transforms over finite groups. Our algorithms entail interaction between two symmetry groups: one arising at the software level from the problem's symmetry and the other arising at the hardware level from the processors' communication network. Part II illustrates the applicability of our symmetry -exploitation techniques by presenting a series of case studies of the design and implementation of parallel programs. First, a parallel program that solves chess endgames by factorization of an associated dihedral group-equivariant matrix is described. This code runs faster than previous serial programs, and discovered it a number of results. Second, parallel algorithms for Fourier transforms for finite groups are developed, and preliminary parallel implementations for group transforms of dihedral and of symmetric groups are described. Applications in learning, vision, pattern recognition, and statistics are proposed. Third, parallel implementations solving several computational science problems are described, including the direct n-body problem, convolutions arising from molecular biology, and some communication primitives such as broadcast and reduce. Some of our implementations ran orders of magnitude faster than previous techniques, and were used in the investigation of various physical phenomena.

  15. The Root Lattice D4 and Planar Quasilattices with Octagonal and Dodecagonal Symmetry

    Science.gov (United States)

    Baake, M.; Joseph, D.; Schlottmann, M.

    Quasiperiodic patterns with eight- and twelvefold symmetry are presented which share the root lattice D4, i.e., the 4-D face-centered hypercubic lattice, for their minimal embedding in four-space. We derive the patterns by means of the dualization method and investigate key properties like vertex configurations, local deflation/inflation symmetries and kinematic diffraction. The generalized point symmetries (and thus the Laue group) of these patterns are the dihedral groups d8 and d12, respectively, which share a common subgroup, d4. We introduce a contiunous one-parameter rotation between the two phases which leaves this subgroup invariant. This should prove useful for modelling alloys like V15Ni10Si where quasicrystalline phases with eight- and twelvefold symmetry coexist.

  16. Symposium Symmetries in Science XIII

    CERN Document Server

    Gruber, Bruno J; Yoshinaga, Naotaka; Symmetries in Science XI

    2005-01-01

    This book is a collection of reviews and essays about the recent developments in the area of Symmetries and applications of Group Theory. Contributions have been written mostly at the graduate level but some are accessible to advanced undergraduates. The book is of interest to a wide audience and covers a broad range of topics with a strong degree of thematical unity. The book is part of a Series of books on Symmetries in Science and may be compared to the published Proceedings of the Colloquia on Group Theoretical Methods in Physics. Here, however, prevails a distinguished character for presenting extended reviews on present applications to Science, not restricted to Theoretical Physics.

  17. Soft theorems from anomalous symmetries

    Science.gov (United States)

    Huang, Yu-tin; Wen, Congkao

    2015-12-01

    We discuss constraints imposed by soft limits for effective field theories arising from symmetry breaking. In particular, we consider those associated with anomalous conformal symmetry as well as duality symmetries in supergravity. We verify these soft theorems for the dilaton effective action relevant for the a-theorem, as well as the one-loop effective action for N=4 supergravity. Using the universality of leading transcendental coefficients in the α' expansion of string theory amplitudes, we study the matrix elements of operator R 4 with half maximal supersymmetry. We construct the non-linear completion of R 4 that satisfies both single and double soft theorems up to seven points. This supports the existence of duality invariant completion of R 4.

  18. Soft theorems from anomalous symmetries

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yu-tin [Department of Physics and Astronomy, National Taiwan University,Taipei 10617, Taiwan, ROC (China); Wen, Congkao [I.N.F.N. Sezione di Roma “Tor Vergata”,Via della Ricerca Scientifica, 00133 Roma (Italy)

    2015-12-22

    We discuss constraints imposed by soft limits for effective field theories arising from symmetry breaking. In particular, we consider those associated with anomalous conformal symmetry as well as duality symmetries in supergravity. We verify these soft theorems for the dilaton effective action relevant for the a-theorem, as well as the one-loop effective action for N=4 supergravity. Using the universality of leading transcendental coefficients in the α{sup ′} expansion of string theory amplitudes, we study the matrix elements of operator R{sup 4} with half maximal supersymmetry. We construct the non-linear completion of R{sup 4} that satisfies both single and double soft theorems up to seven points. This supports the existence of duality invariant completion of R{sup 4}.

  19. Near Point of Convergence Break for Different Age Groups in Turkish Population with Normal Binocular Vision: Normative Data

    Directory of Open Access Journals (Sweden)

    Nihat Sayın

    2013-12-01

    Full Text Available Purpose: The purpose of this study was to evaluate the near point of convergence break in Turkish population with normal binocular vision and to obtain the normative data for the near point of convergence break in different age groups. Such database has not been previously reported. Material and Method: In this prospective study, 329 subjects with normal binocular vision (age range, 3-72 years were evaluated. The near point of convergence break was measured 4 times repeatedly with an accommodative target. Mean values of near point of convergence break were provided for these age groups (≤10, 11-20, 21-30, 31-40, 41-50, 51-60, and >60 years old. A statistical comparison (one-way ANOVA and post-hoc test of these values between age groups was performed. A correlation between the near point of convergence break and age was evaluated by Pearson’s correlation test. Results: The mean value for near point of convergence break was 2.46±1.88 (0.5-14 cm. Specifically, 95% of measurements in all subjects were 60 year-old age groups in the near point of convergence break values (p=0.0001, p=0.0001, p=0.006, p=0.001, p= 0.004. A mild positive correlation was observed between the increase in near point of convergence break and increase of age (r=0.355 (p<0.001. Discussion: The values derived from a relatively large study population to establish a normative database for the near point of convergence break in the Turkish population with normal binocular vision are in relevance with age. This database has not been previously reported. (Turk J Ophthalmol 2013; 43: 402-6

  20. Quantum mechanics. Symmetries. 5. corr. ed.; Quantenmechanik. Symmetrien

    Energy Technology Data Exchange (ETDEWEB)

    Greiner, Walter [Frankfurt Univ. (Germany). Frankfurt Inst. for Advanced Studies; Mueller, Berndt [Duke Univ., Durham, NC (United States). Dept. of Physics

    2014-07-01

    The volume quantum mechanics treats the as elegant as mighty theory of the symmetry groups and their application in quantum mechanics and the theory of the elementary particles. By means of many examples and problems with worked-out solutions the application of the fundamental principles to realistic problems is elucidated. The themes are symmetries in quantum mechanics, representations of the algebra of the angular momentum operators as generators of the SO(3) group. fundamental properties of Lie groups as mathematical supplement, symmetry groups and their physical meaning, thr isospin group, the hypercharge, quarks and the symmetry group SU(3), representations of the permutation group and Young diagrams, group characters as mathematical supplement, charm and the symmetry group SU(4), Cartan-Weyl claasification as mathematical supplement, special discrete symmetries, dynamical symmetries and the hydrogen atom, non-compact Lie groups as mathematical supplement, a proof of Racah's theorem.

  1. limit and complete classification of symmetry schemes in proton ...

    Indian Academy of Sciences (India)

    The various group chains starting fromU(6)ªSUF(2) and Uπ(6)¨Uν(6) are identified and studied in great detail in the past; see for example [1,3,4]. Let us point out that IBM-1 model corresponds to the F = N/2 states in pnIBM where N is the total number of bosons. The F = N/2 1 states are the so-called mixed symmetry states. In.

  2. Relative Critical Points

    Directory of Open Access Journals (Sweden)

    Debra Lewis

    2013-05-01

    Full Text Available Relative equilibria of Lagrangian and Hamiltonian systems with symmetry are critical points of appropriate scalar functions parametrized by the Lie algebra (or its dual of the symmetry group. Setting aside the structures – symplectic, Poisson, or variational – generating dynamical systems from such functions highlights the common features of their construction and analysis, and supports the construction of analogous functions in non-Hamiltonian settings. If the symmetry group is nonabelian, the functions are invariant only with respect to the isotropy subgroup of the given parameter value. Replacing the parametrized family of functions with a single function on the product manifold and extending the action using the (coadjoint action on the algebra or its dual yields a fully invariant function. An invariant map can be used to reverse the usual perspective: rather than selecting a parametrized family of functions and finding their critical points, conditions under which functions will be critical on specific orbits, typically distinguished by isotropy class, can be derived. This strategy is illustrated using several well-known mechanical systems – the Lagrange top, the double spherical pendulum, the free rigid body, and the Riemann ellipsoids – and generalizations of these systems.

  3. Symmetry gauge theory for paraparticles

    International Nuclear Information System (INIS)

    Kursawe, U.

    1986-01-01

    In the present thesis it was shown that for identical particles the wave function of which has a more complicated symmetry than it is the case at the known kinds of particles, the bosons and fermions, a gauge theory can be formulated, the so-called 'symmetry gauge theory'. This theory has its origin alone in the symmetry of the particle wave functions and becomes first relevant when more than two particles are considered. It was shown that for particles with mixed-symmetrical wave functions, so-called 'paraparticles', the quantum mechanical state is no more described by one Hilbert-space element but by a many-dimensional subspace of this Hilbert space. The gauge freedom consists then just in the freedom of the choice of the basis in this subspace, the corresponding gauge group is the group of the unitary basis transformation in this subspace. (orig./HSI) [de

  4. Symmetry and emergence

    Science.gov (United States)

    Witten, Edward

    2018-02-01

    In a modern understanding of particle physics, global symmetries are approximate and gauge symmetries may be emergent. This view, which has echoes in condensed-matter physics, is supported by a variety of arguments from experiment and theory.

  5. Symmetry and perturbation theory

    Science.gov (United States)

    Gaeta, Giuseppe

    A co-chain map for the G invariant De Rham complex -- New examples of trihamiltonian structures linking different Lenard chains -- Wave propagation in an elastic medium: GDS equations -- Parametric excitation in nonlinear dynamics -- Collisionless action-minimizing trajectories for the equivariant 3-body problem in R2 -- The Lagrangian and Hamiltonian formulations for a special class of non-conservative systems -- Shadowing chains of collision orbits for the elliptic 3-body problem -- Similarity reductions of an optical model -- Fold, transcritical and pitchfork singularities for time-reversible systems -- Homographic three-body motions with positive and negative masses -- Remarks on conformal Killing tensors and separation of variables -- A regularity theory for optimal partition problems -- Lambda and mu-symmetries -- Potential symmetries and linearization of some evolution equations -- Periodic solutions for zero mass nonlinear wave equations -- Fundamental covariants in the invariant theory of Killing tensors -- Global geometry of 3-body trajectories with vanishing angular momentum -- The relation between the topological structure of the set of controllable affine systems and topological structures of the set of controllable homogenuous systems in low dimension -- On preservation of action variables for satellite librations in elliptic orbits with account of solar light pressure -- An explicit solution of the (quantum) elliptic Calogero-Sutherland model -- An application of the Melnikov integral to a restricted three body problem -- Reductions of integrable equations and automorphic Lie algebras -- Geometric reduction of Poisson operators -- Closed manifolds admitting metrics with the same geodesics -- A transcritical-flip bifurcation in a model for a robot-arm -- Alignment and the classification of Lorentz-signature tensors -- Renormalization group symmetry and gas dynamics -- Refined computation of hypernormal forms -- New order reductions for Euler

  6. Ermakov's Superintegrable Toy and Nonlocal Symmetries

    OpenAIRE

    Leach, P. G. L.; Karasu, A.; Nucci, M. C.; Andriopoulos, K.

    2005-01-01

    We investigate the symmetry properties of a pair of Ermakov equations. The system is superintegrable and yet possesses only three Lie point symmetries with the algebra sl(2, R). The number of point symmetries is insufficient and the algebra unsuitable for the complete specification of the system. We use the method of reduction of order to reduce the nonlinear fourth-order system to a third-order system comprising a linear second-order equation and a conservation law. We obtain the representat...

  7. Symmetries and conservation laws of the damped harmonic oscillator

    Indian Academy of Sciences (India)

    We work with a formulation of Noether-symmetry analysis which uses the properties of infinitesimal point transformations in the space-time variables to establish the association between symmetries and conservation laws of a dynamical system. Here symmetries are expressed in the form of generators. We have studied the ...

  8. Origin of family symmetries

    International Nuclear Information System (INIS)

    Nilles, Hans Peter

    2012-04-01

    Discrete (family) symmetries might play an important role in models of elementary particle physics. We discuss the origin of such symmetries in the framework of consistent ultraviolet completions of the standard model in field and string theory. The symmetries can arise due to special geometrical properties of extra compact dimensions and the localization of fields in this geometrical landscape. We also comment on anomaly constraints for discrete symmetries.

  9. Origin of family symmetries

    Energy Technology Data Exchange (ETDEWEB)

    Nilles, Hans Peter [Bonn Univ. (Germany). Bethe Center for Theoretical Physics; Bonn Univ. (Germany). Physikalisches Inst.; Ratz, Michael [Technische Univ. Muenchen, Garching (Germany). Physik-Department; Vaudrevange, Patrick K.S. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2012-04-15

    Discrete (family) symmetries might play an important role in models of elementary particle physics. We discuss the origin of such symmetries in the framework of consistent ultraviolet completions of the standard model in field and string theory. The symmetries can arise due to special geometrical properties of extra compact dimensions and the localization of fields in this geometrical landscape. We also comment on anomaly constraints for discrete symmetries.

  10. Providing full point-to-point communications among compute nodes of an operational group in a global combining network of a parallel computer

    Energy Technology Data Exchange (ETDEWEB)

    Archer, Charles J.; Faraj, Daniel A.; Inglett, Todd A.; Ratterman, Joseph D.

    2018-01-30

    Methods, apparatus, and products are disclosed for providing full point-to-point communications among compute nodes of an operational group in a global combining network of a parallel computer, each compute node connected to each adjacent compute node in the global combining network through a link, that include: receiving a network packet in a compute node, the network packet specifying a destination compute node; selecting, in dependence upon the destination compute node, at least one of the links for the compute node along which to forward the network packet toward the destination compute node; and forwarding the network packet along the selected link to the adjacent compute node connected to the compute node through the selected link.

  11. Wigner's Symmetry Representation Theorem

    Indian Academy of Sciences (India)

    IAS Admin

    This article elucidates the important role the no- tion of symmetry has played in physics. It dis- cusses the proof of one of the important theorems of quantum mechanics, viz., Wigner's Symmetry. Representation Theorem. It also shows how the representations of various continuous and dis- crete symmetries follow from the ...

  12. Symmetry, asymmetry and dissymmetry

    International Nuclear Information System (INIS)

    Wackenheim, A.; Zollner, G.

    1987-01-01

    The authors discuss the concept of symmetry and defect of symmetry in radiological imaging and recall the definition of asymmetry (congenital or constitutional) and dissymmetry (acquired). They then describe a rule designed for the cognitive method of automatic evaluation of shape recognition data and propose the use of reversal symmetry [fr

  13. Work characteristics and determinants of job satisfaction in four age groups: university employees' point of view.

    NARCIS (Netherlands)

    Bos, J.T.; Donders, N.C.G.M.; Bouwman-Brouwer, K.M.; Gulden, J.W.J. van der

    2009-01-01

    PURPOSE: To investigate (a) differences in work characteristics and (b) determinants of job satisfaction among employees in different age groups. METHODS: A cross-sectional questionnaire was filled in by 1,112 university employees, classified into four age groups. (a) Work characteristics were

  14. Chiral symmetry and chiral-symmetry breaking

    Energy Technology Data Exchange (ETDEWEB)

    Peskin, M.E.

    1982-12-01

    These lectures concern the dynamics of fermions in strong interaction with gauge fields. Systems of fermions coupled by gauge forces have a very rich structure of global symmetries, which are called chiral symmetries. These lectures will focus on the realization of chiral symmetries and the causes and consequences of thier spontaneous breaking. A brief introduction to the basic formalism and concepts of chiral symmetry breaking is given, then some explicit calculations of chiral symmetry breaking in gauge theories are given, treating first parity-invariant and then chiral models. These calculations are meant to be illustrative rather than accurate; they make use of unjustified mathematical approximations which serve to make the physics more clear. Some formal constraints on chiral symmetry breaking are discussed which illuminate and extend the results of our more explicit analysis. Finally, a brief review of the phenomenological theory of chiral symmetry breaking is presented, and some applications of this theory to problems in weak-interaction physics are discussed. (WHK)

  15. Spatial and Spin Symmetry Breaking in Semidefinite-Programming-Based Hartree-Fock Theory.

    Science.gov (United States)

    Nascimento, Daniel R; DePrince, A Eugene

    2018-04-16

    The Hartree-Fock problem was recently recast as a semidefinite optimization over the space of rank-constrained two-body reduced-density matrices (RDMs) [ Phys. Rev. A 2014 , 89 , 010502(R) ]. This formulation of the problem transfers the nonconvexity of the Hartree-Fock energy functional to the rank constraint on the two-body RDM. We consider an equivalent optimization over the space of positive semidefinite one-electron RDMs (1-RDMs) that retains the nonconvexity of the Hartree-Fock energy expression. The optimized 1-RDM satisfies ensemble N-representability conditions, and ensemble spin-state conditions may be imposed as well. The spin-state conditions place additional linear and nonlinear constraints on the 1-RDM. We apply this RDM-based approach to several molecular systems and explore its spatial (point group) and spin ( Ŝ 2 and Ŝ 3 ) symmetry breaking properties. When imposing Ŝ 2 and Ŝ 3 symmetry but relaxing point group symmetry, the procedure often locates spatial-symmetry-broken solutions that are difficult to identify using standard algorithms. For example, the RDM-based approach yields a smooth, spatial-symmetry-broken potential energy curve for the well-known Be-H 2 insertion pathway. We also demonstrate numerically that, upon relaxation of Ŝ 2 and Ŝ 3 symmetry constraints, the RDM-based approach is equivalent to real-valued generalized Hartree-Fock theory.

  16. Nonlocal Symmetries to Systems of Nonlinear Diffusion Equations

    International Nuclear Information System (INIS)

    Qu Changzheng; Kang Jing

    2008-01-01

    In this paper, we study potential symmetries to certain systems of nonlinear diffusion equations. Those systems have physical applications in soil science, mathematical biology, and invariant curve flows in R 3 . Lie point symmetries of the potential system, which cannot be projected to vector fields of the given dependent and independent variables, yield potential symmetries. The class of the system that admits potential symmetries is expanded.

  17. Symmetry Adaptation of the Rotation-Vibration Theory for Linear Molecules

    Directory of Open Access Journals (Sweden)

    Katy L. Chubb

    2018-04-01

    Full Text Available A numerical application of linear-molecule symmetry properties, described by the D ∞ h point group, is formulated in terms of lower-order symmetry groups D n h with finite n. Character tables and irreducible representation transformation matrices are presented for D n h groups with arbitrary n-values. These groups can subsequently be used in the construction of symmetry-adapted ro-vibrational basis functions for solving the Schrödinger equations of linear molecules. Their implementation into the symmetrisation procedure based on a set of “reduced” vibrational eigenvalue problems with simplified Hamiltonians is used as a practical example. It is shown how the solutions of these eigenvalue problems can also be extended to include the classification of basis-set functions using ℓ, the eigenvalue (in units of ℏ of the vibrational angular momentum operator L ^ z . This facilitates the symmetry adaptation of the basis set functions in terms of the irreducible representations of D n h . 12 C 2 H 2 is used as an example of a linear molecule of D ∞ h point group symmetry to illustrate the symmetrisation procedure of the variational nuclear motion program Theoretical ROVibrational Energies (TROVE.

  18. Parastatistics and gauge symmetries

    International Nuclear Information System (INIS)

    Govorkov, A.B.

    1982-01-01

    A possible formulation of gauge symmetries in the Green parafield theory is analysed and the SO(3) gauge symmetry is shown to be on a distinct status. The Greenberg paraquark hypothesis turns out to be not equivalent to the hypothesis of quark colour SU(3)sub(c) symmetry. Specific features of the gauge SO(3) symmetry are discussed, and a possible scheme where it is an exact subgroup of the broken SU(3)sub(c) symmetry is proposed. The direct formulation of the gauge principle for the parafield represented by quaternions is also discussed

  19. Molecular symmetry in ab initio calculations

    International Nuclear Information System (INIS)

    Madhavan, P.V.; Whitten, J.L.

    1987-01-01

    A scheme is presented for the construction of the Fock matrix in LCAO-SCF calculations and for the transformation of basis integrals to LCAO-MO integrals that can utilize several symmetry unique lists of integrals corresponding to different symmetry groups. The algorithm is fully compatible with vector processing machines and is especially suited for parallel processing machines. copyright 1987 Academic Press, Inc

  20. Family gauge symmetry from a composite model

    International Nuclear Information System (INIS)

    Zhou, B.R.; Chang, C.H.; Princeton Univ., NJ

    1983-01-01

    A family gauge symmetry SUsup(F)(2) could emerge from a composite model of quarks and leptons under some assumptions of chiral hyperflavor symmetry-breaking pattern. Possible dynamical mechanisms which break the family and electroweak gauge group and produce quark-lepton masses are indicated and their phenomenologies are discussed qualitatively. (orig.)

  1. Clifford algebraic symmetries in physics

    International Nuclear Information System (INIS)

    Salingaros, N.

    1986-01-01

    This paper reviews the following appearances of Clifford algebras in theoretical physics: statistical mechanics; general relativity; quantum electrodynamics; internal symmetries; the vee product; classical electrodynamics; charged-particle motion; and the Lorentz group. It is concluded that the power of the Clifford-algebraic description resides in its ability to perform representation-free calculations which are generalizations of the traditional vector algebra and that this considerable computational asset, in combination with the intrinsic symmetry, provides a practical framework for much of theoretical physics. 5 references

  2. Symmetries and Geometry

    Science.gov (United States)

    Witten, Edward

    2016-03-01

    In this talk, I will describe global and gauge symmetries and the interplay between them. The meaning of global symmetries is clear: they act on physical observables. Gauge symmetries are more elusive as they typically do not act on physical observables. Gauge symmetries are redundancies in the mathematical description of a physical system rather than properties of the system itself. The existence of nonperturbative dualities makes it clear that this distinction is unavoidable. Yet in our best understanding the gauge symmetries are deeper. The lepton number symmetries that are probed by the wonderful experimental results that will be reported in this session give an excellent illustration. They are regarded in the Standard Model as indirect consequences of gauge symmetries and they are expected to be only approximate. This expectation is supported by the observation of neutrino oscillations.

  3. Generalized global symmetries

    International Nuclear Information System (INIS)

    Gaiotto, Davide; Kapustin, Anton; Seiberg, Nathan; Willett, Brian

    2015-01-01

    A q-form global symmetry is a global symmetry for which the charged operators are of space-time dimension q; e.g. Wilson lines, surface defects, etc., and the charged excitations have q spatial dimensions; e.g. strings, membranes, etc. Many of the properties of ordinary global symmetries (q=0) apply here. They lead to Ward identities and hence to selection rules on amplitudes. Such global symmetries can be coupled to classical background fields and they can be gauged by summing over these classical fields. These generalized global symmetries can be spontaneously broken (either completely or to a subgroup). They can also have ’t Hooft anomalies, which prevent us from gauging them, but lead to ’t Hooft anomaly matching conditions. Such anomalies can also lead to anomaly inflow on various defects and exotic Symmetry Protected Topological phases. Our analysis of these symmetries gives a new unified perspective of many known phenomena and uncovers new results.

  4. Hidden Symmetries of Stochastic Models

    Directory of Open Access Journals (Sweden)

    Boyka Aneva

    2007-05-01

    Full Text Available In the matrix product states approach to $n$ species diffusion processes the stationary probability distribution is expressed as a matrix product state with respect to a quadratic algebra determined by the dynamics of the process. The quadratic algebra defines a noncommutative space with a $SU_q(n$ quantum group action as its symmetry. Boundary processes amount to the appearance of parameter dependent linear terms in the algebraic relations and lead to a reduction of the $SU_q(n$ symmetry. We argue that the boundary operators of the asymmetric simple exclusion process generate a tridiagonal algebra whose irriducible representations are expressed in terms of the Askey-Wilson polynomials. The Askey-Wilson algebra arises as a symmetry of the boundary problem and allows to solve the model exactly.

  5. Translational Symmetry and Microscopic Constraints on Symmetry-Enriched Topological Phases: A View from the Surface

    Directory of Open Access Journals (Sweden)

    Meng Cheng

    2016-12-01

    Full Text Available The Lieb-Schultz-Mattis theorem and its higher-dimensional generalizations by Oshikawa and Hastings require that translationally invariant 2D spin systems with a half-integer spin per unit cell must either have a continuum of low energy excitations, spontaneously break some symmetries, or exhibit topological order with anyonic excitations. We establish a connection between these constraints and a remarkably similar set of constraints at the surface of a 3D interacting topological insulator. This, combined with recent work on symmetry-enriched topological phases with on-site unitary symmetries, enables us to develop a framework for understanding the structure of symmetry-enriched topological phases with both translational and on-site unitary symmetries, including the effective theory of symmetry defects. This framework places stringent constraints on the possible types of symmetry fractionalization that can occur in 2D systems whose unit cell contains fractional spin, fractional charge, or a projective representation of the symmetry group. As a concrete application, we determine when a topological phase must possess a “spinon” excitation, even in cases when spin rotational invariance is broken down to a discrete subgroup by the crystal structure. We also describe the phenomena of “anyonic spin-orbit coupling,” which may arise from the interplay of translational and on-site symmetries. These include the possibility of on-site symmetry defect branch lines carrying topological charge per unit length and lattice dislocations inducing degeneracies protected by on-site symmetry.

  6. Using Lie Symmetry Analysis to Solve a Problem That Models Mass Transfer from a Horizontal Flat Plate

    Directory of Open Access Journals (Sweden)

    W. Sinkala

    2012-01-01

    Full Text Available We use Lie symmetry analysis to solve a boundary value problem that arises in chemical engineering, namely, mass transfer during the contact of a solid slab with an overhead flowing fluid. This problem was earlier tackled using Adomian decomposition method (Fatoorehchi and Abolghasemi 2011, leading to the Adomian series form of solution. It turns out that the application of Lie group analysis yields an elegant form of the solution. After introducing the governing mathematical model and some preliminaries of Lie symmetry analysis, we compute the Lie point symmetries admitted by the governing equation and use these to construct the desired solution as an invariant solution.

  7. Dual Symmetry in Gauge Theories

    OpenAIRE

    Koshkarov, A. L.

    1997-01-01

    Continuous dual symmetry in electrodynamics, Yang-Mills theory and gravitation is investigated. Dual invariant which leads to badly nonlinear motion equations is chosen as a Lagrangian of the pure classical dual nonlinear electrodynamics. In a natural manner some dual angle which is determined by the electromagnetic strengths at the point of the time-space appears in the model. Motion equations may well be interpreted as the equations of the standard Maxwell theory with source. Alternative in...

  8. The fundamental principles of the physical protection, the group of six point of view

    International Nuclear Information System (INIS)

    Claeys, M.; Carnas, L.; Robeyns, G.; Rommevaux, G.; Venot, R.; Hagemann, A.; Fontaneda Gonzalez, A.; Gimenez Gonzalez, S.; Isaksson, S.G.; Wager, K.; Price, C.

    2001-01-01

    This paper presents the joint experience of the Group of Six in the field of physical protection against the theft or unauthorized removal of nuclear material and against the sabotage of nuclear material and nuclear facilities, which emerged from the joint discussion. Several fundamental principles stem from this experience. Of course the particular terms and conditions of the implementation of these principles are specific to each country. (authors)

  9. Pseudo-time-reversal symmetry and topological edge states in two-dimensional acoustic crystals

    KAUST Repository

    Mei, Jun

    2016-09-02

    We propose a simple two-dimensional acoustic crystal to realize topologically protected edge states for acoustic waves. The acoustic crystal is composed of a triangular array of core-shell cylinders embedded in a water host. By utilizing the point group symmetry of two doubly degenerate eigenstates at the Î

  10. Second-quantized mirror symmetry

    CERN Document Server

    Ferrara, Sergio; Strominger, A; Vafa, C

    1995-01-01

    We propose and give strong evidence for a duality relating Type II theories on Calabi-Yau spaces and heterotic strings on K3 \\times T^2, both of which have N=2 spacetime supersymmetry. Entries in the dictionary relating the dual theories are derived from an analysis of the soliton string worldsheet in the context of N=2 orbifolds of dual N=4 compactifications of Type II and heterotic strings. In particular we construct a pairing between Type II string theory on a self-mirror Calabi-Yau space X with h^{11}= h^{21}= 11 and a (4, 0) background of heterotic string theory on K3\\times T^2. Under the duality transformation the usual first-quantized mirror symmetry of X becomes a second-quantized mirror symmetry which determines nonperturbative quantum effects. This enables us to compute the exact quantum moduli space. Mirror symmetry of X implies that the low-energy N=2 gauge theory is finite, even at enhanced symmetry points. This prediction is verified by direct computation on the heterotic side. Other branches of...

  11. Superdeformations and fermion dynamical symmetries

    International Nuclear Information System (INIS)

    Wu, Cheng-Li

    1990-01-01

    In this talk, I will present a link between nuclear collective motions and their underlying fermion dynamical symmetries. In particular, I will focus on the microscopic understanding of deformations. It is shown that the SU 3 of the one major shell fermion dynamical symmetry model (FDSM) is responsible for the physics of low and high spins in normal deformation. For the recently observed phenomena of superdeformation, the physics of the problem dictates a generalization to a supershell structure (SFDSM), which also has an SU 3 fermion dynamical symmetry. Many recently discovered feature of superdeformation are found to be inherent in such an SU 3 symmetry. In both cases the dynamical Pauli effect plays a vital role. A particularly noteworthy discovery from this model is that the superdeformed ground band is not the usual unaligned band but the D-pair aligned (DPA) band, which sharply crosses the excited bands. The existence of such DPA band is a key point to understand many properties of superdeformation. Our studies also poses new experimental challenge. This is particularly interesting since there are now plans to build new and exciting γ-ray detecting systems, like the GAMMASPHERE, which could provide answers to some of these challenges. 34 refs., 11 figs., 5 tabs

  12. Features of effective medical knowledge resources to support point of care learning: a focus group study.

    Directory of Open Access Journals (Sweden)

    David A Cook

    Full Text Available OBJECTIVE: Health care professionals access various information sources to quickly answer questions that arise in clinical practice. The features that favorably influence the selection and use of knowledge resources remain unclear. We sought to better understand how clinicians select among the various knowledge resources available to them, and from this to derive a model for an effective knowledge resource. METHODS: We conducted 11 focus groups at an academic medical center and outlying community sites. We included a purposive sample of 50 primary care and subspecialist internal medicine and family medicine physicians. We transcribed focus group discussions and analyzed these using a constant comparative approach to inductively identify features that influence the selection of knowledge resources. RESULTS: We identified nine features that influence users' selection of knowledge resources, namely efficiency (with sub-features of comprehensiveness, searchability, and brevity, integration with clinical workflow, credibility, user familiarity, capacity to identify a human expert, reflection of local care processes, optimization for the clinical question (e.g., diagnosis, treatment options, drug side effect, currency, and ability to support patient education. No single existing resource exemplifies all of these features. CONCLUSION: The influential features identified in this study will inform the development of knowledge resources, and could serve as a framework for future research in this field.

  13. Spectral distributions and symmetries

    International Nuclear Information System (INIS)

    Quesne, C.

    1980-01-01

    As it is now well known, the spectral distribution method has both statistical and group theoretical aspects which make for great simplifications in many-Fermion system calculations with respect to more conventional ones. Although both aspects intertwine and are equally essential to understand what is going on, we are only going to discuss some of the group theoretical aspects, namely those connected with the propagation of information, in view of their fundamental importance for the actual calculations of spectral distributions. To be more precise, let us recall that the spectral distribution method may be applied in principle to many-Fermion spaces which have a direct-product structure, i.e., are obtained by distributing a certain number n of Fermions over N single-particle states (O less than or equal to n less than or equal to N), as it is the case for instance for the nuclear shell model spaces. For such systems, the operation of a central limit theorem is known to provide us with a simplifying principle which, when used in conjunction with exact or broken symmetries, enables us to make definite predictions in those cases which are not amendable to exact shell model diagonalizations. The distribution (in energy) of the states corresponding to a fixed symmetry is then defined by a small number of low-order energy moments. Since the Hamiltonian is defined in few-particle subspaces embedded in the n-particlespace, the low-order moments, we are interested in, can be expressed in terms of simpler quantities defined in those few-particle subspaces: the information is said to propagate from the simple subspaces to the more complicated ones. The possibility of actually calculating spectral distributions depends upon the finding of simple ways to propagate the information

  14. Symmetry-protected topological insulator and its symmetry-enriched topologically ordered boundary

    Science.gov (United States)

    Wang, Juven; Wen, Xiao-Gang; Witten, Edward

    We propose a mechanism for achieving symmetry-enriched topologically ordered boundaries for symmetry-protected topological states, including those of topological insulators. Several different boundary phases and their phase transitions are considered, including confined phases, deconfined phases, symmetry-breaking, gapped and gapless phases. National Science Foundation PHY-1606531, Corning Glass Works Foundation Fellowship, NSF Grant DMR- 1506475 and NSFC 11274192, the BMO Financial Group and the John Templeton Foundation No. 39901.

  15. Discrete symmetries and their stringy origin

    International Nuclear Information System (INIS)

    Mayorga Pena, Damian Kaloni

    2014-05-01

    Discrete symmetries have proven to be very useful in controlling the phenomenology of theories beyond the standard model. In this work we explore how these symmetries emerge from string compactifications. Our approach is twofold: On the one hand, we consider the heterotic string on orbifold backgrounds. In this case the discrete symmetries can be derived from the orbifold conformal field theory, and it can be shown that they are in close relation with the orbifold geometry. We devote special attention to R-symmetries, which arise from discrete remnants of the Lorentz group in compact space. Further we discuss the physical implications of these symmetries both in the heterotic mini-landscape and in newly constructed models based on the Z 2 x Z 4 orbifold. In both cases we observe that the discrete symmetries favor particular locations in the orbifold where the particles of standard model should live. On the other hand we consider a class of F-theory models exhibiting an SU(5) gauge group, times additional U(1) symmetries. In this case, the smooth compactification background does not permit us to track the discrete symmetries as transparently as in orbifold models. Hence, we follow a different approach and search for discrete subgroups emerging after the U(1)s are broken. We observe that in this approach it is possible to obtain the standard Z 2 matter parity of the MSSM.

  16. Gapless Symmetry-Protected Topological Order

    Directory of Open Access Journals (Sweden)

    Thomas Scaffidi

    2017-11-01

    Full Text Available We introduce exactly solvable gapless quantum systems in d dimensions that support symmetry-protected topological (SPT edge modes. Our construction leads to long-range entangled, critical points or phases that can be interpreted as critical condensates of domain walls “decorated” with dimension (d-1 SPT systems. Using a combination of field theory and exact lattice results, we argue that such gapless SPT systems have symmetry-protected topological edge modes that can be either gapless or symmetry broken, leading to unusual surface critical properties. Despite the absence of a bulk gap, these edge modes are robust against arbitrary symmetry-preserving local perturbations near the edges. In two dimensions, we construct wave functions that can also be interpreted as unusual quantum critical points with diffusive scaling in the bulk but ballistic edge dynamics.

  17. Symmetry and bifurcations of momentum mappings

    International Nuclear Information System (INIS)

    Arms, J.M.; Marsden, J.E.; Moncrief, V.

    1981-01-01

    The zero set of a momentum mapping is shown to have a singularity at each point with symmetry. The zero set is diffeomorphic to the product of a manifold and the zero set of a homogeneous quadratic function. The proof uses the Kuranishi theory of deformations. Among the applications, it is shown that the set of all solutions of the Yang-Mills equations on a Lorentz manifold has a singularity at any solution with symmetry, in the sense of a pure gauge symmetry. Similarly, the set of solutions of Einstein's equations has a singularity at any solution that has spacelike Killing fields, provided the spacetime has a compact Cauchy surface. (orig.)

  18. Symmetry and bifurcations of momentum mappings

    Science.gov (United States)

    Arms, Judith M.; Marsden, Jerrold E.; Moncrief, Vincent

    1981-01-01

    The zero set of a momentum mapping is shown to have a singularity at each point with symmetry. The zero set is diffeomorphic to the product of a manifold and the zero set of a homogeneous quadratic function. The proof uses the Kuranishi theory of deformations. Among the applications, it is shown that the set of all solutions of the Yang-Mills equations on a Lorentz manifold has a singularity at any solution with symmetry, in the sense of a pure gauge symmetry. Similarly, the set of solutions of Einstein's equations has a singularity at any solution that has spacelike Killing fields, provided the spacetime has a compact Cauchy surface.

  19. Terahertz emission from the intrinsic Josephson junctions of high-symmetry thermally-managed Bi2Sr2CaCu2O8+δ microstrip antennas

    Science.gov (United States)

    Klemm, Richard A.; Davis, Andrew E.; Wang, Qing X.; Yamamoto, Takashi; Cerkoney, Daniel P.; Reid, Candy; Koopman, Maximiliaan L.; Minami, Hidetoshi; Kashiwagi, Takanari; Rain, Joseph R.; Doty, Constance M.; Sedlack, Michael A.; Morales, Manuel A.; Watanabe, Chiharu; Tsujimoto, Manabu; Delfanazari, Kaveh; Kadowaki, Kazuo

    2017-12-01

    We show for high-symmetry disk, square, or equilateral triangular thin microstrip antennas of any composition respectively obeying C ∞v , C 4v , and C 3v point group symmetries, that the transverse magnetic electromagnetic cavity mode wave functions are restricted in form to those that are one-dimensional representations of those point groups. Plots of the common nodal points of the ten lowest-energy non-radiating two-dimensional representations of each of these three symmetries are presented. For comparison with symmetry-broken disk intrinsic Josephson junction microstrip antennas constructed from the highly anisotropic layered superconductor Bi2Sr2CaCu2O8+δ (BSCCO), we present plots of the ten lowest frequency orthonormal wave functions and of their emission power angular distributions. These results are compared with previous results for square and equilateral triangular thin microstrip antennas.

  20. Human Odometry Verifies the Symmetry Perspective on Bipedal Gaits

    Science.gov (United States)

    Turvey, M. T.; Harrison, Steven J.; Frank, Till D.; Carello, Claudia

    2012-01-01

    Bipedal gaits have been classified on the basis of the group symmetry of the minimal network of identical differential equations (alias "cells") required to model them. Primary gaits are characterized by dihedral symmetry, whereas secondary gaits are characterized by a lower, cyclic symmetry. This fact was used in a test of human…

  1. Computation of the unitary group for the Rashba spin–orbit coupled operator, with application to point-interactions

    Science.gov (United States)

    Juršėnas, Rytis

    2018-01-01

    We compute an explicit formula for the one-parameter unitary group of the single-particle Rashba spin–orbit coupled operator in dimension three. As an application, we derive the formula for the Green function for the two-particle operator, and then prove that the spin-dependent point-interaction is of class \\renewcommand{\\H}{H} \\H-4 . The latter is thus the example of a supersingular perturbation for which no self-adjoint operator can be constructed.

  2. The zonal satellite problem. III Symmetries

    Directory of Open Access Journals (Sweden)

    Mioc V.

    2002-01-01

    Full Text Available The two-body problem associated with a force field described by a potential of the form U =Sum(k=1,n ak/rk (r = distance between particles, ak = real parameters is resumed from the only standpoint of symmetries. Such symmetries, expressed in Hamiltonian coordinates, or in standard polar coordinates, are recovered for McGehee-type coordinates of both collision-blow-up and infinity-blow-up kind. They form diffeomorphic commutative groups endowed with a Boolean structure. Expressed in Levi-Civita’s coordinates, the problem exhibits a larger group of symmetries, also commutative and presenting a Boolean structure.

  3. Using local symmetry for landmark selection

    OpenAIRE

    Kootstra, Geert; de Jong, Sjoerd; Schomaker, Lambert R. B.

    2009-01-01

    Most visual Simultaneous Localization And Mapping (SLAM) methods use interest points as landmarks in their maps of the environment. Often the interest points are detected using contrast features, for instance those of the Scale Invariant Feature Transform (SIFT). The SIFT interest points, however, have problems with stability, and noise robustness. Taking our inspiration from human vision, we therefore propose the use of local symmetry to select interest points. Our method, the MUlti-scale Sy...

  4. The symmetries and conservation laws of some Gordon-type ...

    Indian Academy of Sciences (India)

    Abstract. In this letter, the Lie point symmetries of a class of Gordon-type wave equations that arise in the Milne space-time are presented and analysed. Using the Lie point symmetries, it is showed how to reduce Gordon-type wave equations using the method of invariants, and to obtain exact solutions corresponding to ...

  5. The symmetries and conservation laws of some Gordon-type ...

    Indian Academy of Sciences (India)

    Using the Lie point symmetries, it is showed how to reduce Gordon-type wave equations using the method of invariants, and to obtain exact solutions corresponding to some boundary values. The Noether point symmetries and conservation laws are obtained for the Klein–Gordon equation in one case. Finally, the existence ...

  6. Lie-algebra approach to symmetry breaking

    International Nuclear Information System (INIS)

    Anderson, J.T.

    1981-01-01

    A formal Lie-algebra approach to symmetry breaking is studied in an attempt to reduce the arbitrariness of Lagrangian (Hamiltonian) models which include several free parameters and/or ad hoc symmetry groups. From Lie algebra it is shown that the unbroken Lagrangian vacuum symmetry can be identified from a linear function of integers which are Cartan matrix elements. In broken symmetry if the breaking operators form an algebra then the breaking symmetry (or symmetries) can be identified from linear functions of integers characteristic of the breaking symmetries. The results are applied to the Dirac Hamiltonian of a sum of flavored fermions and colored bosons in the absence of dynamical symmetry breaking. In the partially reduced quadratic Hamiltonian the breaking-operator functions are shown to consist of terms of order g 2 , g, and g 0 in the color coupling constants and identified with strong (boson-boson), medium strong (boson-fermion), and fine-structure (fermion-fermion) interactions. The breaking operators include a boson helicity operator in addition to the familiar fermion helicity and ''spin-orbit'' terms. Within the broken vacuum defined by the conventional formalism, the field divergence yields a gauge which is a linear function of Cartan matrix integers and which specifies the vacuum symmetry. We find that the vacuum symmetry is chiral SU(3) x SU(3) and the axial-vector-current divergence gives a PCAC -like function of the Cartan matrix integers which reduces to PCAC for SU(2) x SU(2) breaking. For the mass spectra of the nonets J/sup P/ = 0 - ,1/2 + ,1 - the integer runs through the sequence 3,0,-1,-2, which indicates that the breaking subgroups are the simple Lie groups. Exact axial-vector-current conservation indicates a breaking sum rule which generates octet enhancement. Finally, the second-order breaking terms are obtained from the second-order spin tensor sum of the completely reduced quartic Hamiltonian

  7. Kohn's theorem and Galilean symmetry

    Science.gov (United States)

    Zhang, P.-M.; Horvathy, P. A.

    2011-08-01

    The relation between the separability of a system of charged particles in a uniform magnetic field and Galilean symmetry is revisited using Duval's “Bargmann framework”. If the charge-to-mass ratios of the particles are identical, ea/ma=ɛ for all particles, then the Bargmann space of the magnetic system is isometric to that of an anisotropic harmonic oscillator. Assuming that the particles interact through a potential which only depends on their relative distances, the system splits into one representing the center of mass plus a decoupled internal part, and can be mapped further into an isolated system using Niederer's transformation. Conversely, the manifest Galilean boost symmetry of the isolated system can be “imported” to the oscillator and to the magnetic systems, respectively, to yield the symmetry used by Gibbons and Pope to prove the separability. For vanishing interaction potential the isolated system is free and our procedure endows all our systems with a hidden Schrödinger symmetry, augmented with independent internal rotations. All these properties follow from the cohomological structure of the Galilei group, as explained by Souriau's “décomposition barycentrique”.

  8. Symmetry and Interculturality

    Science.gov (United States)

    Marchis, Iuliana

    2009-01-01

    Symmetry is one of the fundamental concepts in Geometry. It is a Mathematical concept, which can be very well connected with Art and Ethnography. The aim of the article is to show how to link the geometrical concept symmetry with interculturality. For this mosaics from different countries are used.

  9. Symmetries in Optimal Control

    NARCIS (Netherlands)

    Schaft, A.J. van der

    1987-01-01

    It is argued that the existence of symmetries may simplify, as in classical mechanics, the solution of optimal control problems. A procedure for obtaining symmetries for the optimal Hamiltonian resulting from the Maximum Principle is given; this avoids the actual calculation of the optimal

  10. Symmetry Festival 2016

    CERN Document Server

    2016-01-01

    The Symmetry Festival is a science and art program series, the most important periodic event (see its history) to bring together scientists, artists, educators and practitioners interested in symmetry (its roots, what is behind, applications, etc.), or in the consequences of its absence.

  11. Charged fluids with symmetries

    Indian Academy of Sciences (India)

    metric tensor field and generate constants of the motion along null geodesics for massless particles. Conformal symmetries arise in various physical applications. The existence of conformal symmetries in relativistic cosmological models, with restrictions on the matter content and fluid four-velocity, have been extensively ...

  12. Enhanced symmetries of gauge theory and resolving the spectrum of local operators

    International Nuclear Information System (INIS)

    Kimura, Yusuke; Ramgoolam, Sanjaye

    2008-01-01

    Enhanced global non-Abelian symmetries at zero coupling in Yang Mills theory play an important role in diagonalizing the two-point functions of multimatrix operators. Generalized Casimirs constructed from the iterated commutator action of these enhanced symmetries resolve all the multiplicity labels of the bases of matrix operators which diagonalize the two-point function. For the case of U(N) gauge theory with a single complex matrix in the adjoint of the gauge group we have a U(N) x4 global symmetry of the scaling operator at zero coupling. Different choices of commuting sets of Casimirs, for the case of a complex matrix, lead to the restricted Schur basis previously studied in connection with string excitations of giant gravitons and the Brauer basis studied in connection with brane-antibrane systems. More generally these remarks can be extended to the diagonalization for any global symmetry group G. Schur-Weyl duality plays a central role in connecting the enhanced symmetries and the diagonal bases.

  13. Arithmetic crystal classes of magnetic symmetries

    International Nuclear Information System (INIS)

    Angelova, M.N.; Boyle, L.L.

    1993-01-01

    The symmetries and properties of a broad class of magnetic crystals are described by magnetic space groups which contain both (unitary) spatial symmetry operations and their combinations with the (anti-unitary operation of) time inversion, 0. The spatial symmetry operations form a halving, non-magnetic, space group H of the magnetic group M such that M=H+aH. As an abstract group the magnetic group M is isomorphic to a non-magnetic group G. The anti-unitary operator a is simply the time inversion 0 when M is a grey group but a product of time inversion with some spatial operation belonging to the coset G-H when M is a black-and-white group. (Author)

  14. Renormalization group flows and fixed points for a scalar field in curved space with nonminimal F (ϕ )R coupling

    Science.gov (United States)

    Merzlikin, Boris S.; Shapiro, Ilya L.; Wipf, Andreas; Zanusso, Omar

    2017-12-01

    Using covariant methods, we construct and explore the Wetterich equation for a nonminimal coupling F (ϕ )R of a quantized scalar field to the Ricci scalar of a prescribed curved space. This includes the often considered nonminimal coupling ξ ϕ2R as a special case. We consider the truncations without and with scale- and field-dependent wave-function renormalization in dimensions between four and two. Thereby the main emphasis is on analytic and numerical solutions of the fixed point equations and the behavior in the vicinity of the corresponding fixed points. We determine the nonminimal coupling in the symmetric and spontaneously broken phases with vanishing and nonvanishing average fields, respectively. Using functional perturbative renormalization group methods, we discuss the leading universal contributions to the RG flow below the upper critical dimension d =4 .

  15. Electric-magnetic duality as a secondary symmetry

    International Nuclear Information System (INIS)

    Brandt, R.A.; Young, K.

    1980-01-01

    In both the abelian and non-abelian classical point magnetic monopole theories, electric current conservation is a consequence of gauge invariance, but, since there is no magnetic gauge group, magnetic current conservation is not a Noether-type conservation law. In the abelian models, the equations of motion (but not the lagrangian) are invariant to the duality rotations in electric-magnetic charge space, but this is not the case in the non-abelian models. In an attempt to understand these and related points, we introduce a generalization of Noether's theorem. Consider a physical system described by a set of variables THETA and characterized by a lagrangian density L(THETA). A transormation law THETA → G THETA which leaves L invariant leads to a conserved current Jsub(μ)(THETA). We then call G a primary symmetry. A second transformation law THETA → D THETA which leaves the equations of motion, but not L, invariant then leads to another conserved current Jsub(μ)(D THETA). We then call D a secondary symmetra. Our main point is that Jsub(μ) (D THETA) may be conserved even if the equations of motion are not invariant under D. All that is required is that the change of the equations of motion under D is perpendicular (in the field space) to the change of the fields under G. Then we call D an incomplete secondary symmetry. We show that in both the abelian and non-abelian monopole theories, duality is an incomplete secondary symmetry whose associated conservation law is magnetic current conservation. Thus it is the interpretation of duality as a secondary symmetry which explains magnetic current conservation and which generalizes from the abelian theories to the non-abelian ones. This suggests that magnetic current conservation may remain valid in quantum field theory. (orig.)

  16. Improved Statistics for Determining the Patterson Symmetry fromUnmerged Diffraction Intensities

    Energy Technology Data Exchange (ETDEWEB)

    Sauter, Nicholas K.; Grosse-Kunstleve, Ralf W.; Adams, Paul D.

    2006-01-09

    We examine procedures for detecting the point-group symmetryof macromolecular datasets and propose enhancements. To validate apoint-group, it is sufficient to compare pairs of Bragg reflections thatare related by each of the group's component symmetry operators.Correlation is commonly expressed in the form of a single statisticalquantity (such as Rmerge) that incorporates information from all of theobserved reflections. However, the usual practice of weighting all pairsof symmetry-related intensities equally can obscure the fact that thevarious symmetry operators of the point-group contribute differingfractions of the total set. In some cases where particular symmetryelements are significantly under-represented, statistics calculatedglobally over all observations do not permit conclusions about thepoint-group and Patterson symmetry. The problem can be avoided byrepartitioning the data in a way that explicitly takes note of individualoperators. The new analysis methods, incorporated into the programLABELIT (cci.lbl.gov/labelit), can be performed early enough during dataacquisition, and are quick enough, that it is feasible to pause tooptimize the data collection strategy.

  17. Conformal correlators of mixed-symmetry tensors

    CERN Document Server

    Costa, Miguel S

    2015-01-01

    We generalize the embedding formalism for conformal field theories to the case of general operators with mixed symmetry. The index-free notation encoding symmetric tensors as polynomials in an auxiliary polarization vector is extended to mixed-symmetry tensors by introducing a new commuting or anticommuting polarization vector for each row or column in the Young diagram that describes the index symmetries of the tensor. We determine the tensor structures that are allowed in n-point conformal correlation functions and give an algorithm for counting them in terms of tensor product coefficients. We show, with an example, how the new formalism can be used to compute conformal blocks of arbitrary external fields for the exchange of any conformal primary and its descendants. The matching between the number of tensor structures in conformal field theory correlators of operators in d dimensions and massive scattering amplitudes in d+1 dimensions is also seen to carry over to mixed-symmetry tensors.

  18. Physics from symmetry

    CERN Document Server

    Schwichtenberg, Jakob

    2015-01-01

    This is a textbook that derives the fundamental theories of physics from symmetry.   It starts by introducing, in a completely self-contained way, all mathematical tools needed to use symmetry ideas in physics. Thereafter, these tools are put into action and by using symmetry constraints, the fundamental equations of Quantum Mechanics, Quantum Field Theory, Electromagnetism, and Classical Mechanics are derived. As a result, the reader is able to understand the basic assumptions behind, and the connections between the modern theories of physics. The book concludes with first applications of the previously derived equations.

  19. Group method analysis of mixed convection stagnation-point flow of non-Newtonian nanofluid over a vertical stretching surface

    Science.gov (United States)

    Nabwey, Hossam A.; Boumazgour, Mohamed; Rashad, A. M.

    2017-07-01

    The group method analysis is applied to study the steady mixed convection stagnation-point flow of a non-Newtonian nanofluid towards a vertical stretching surface. The model utilized for the nanofluid incorporates the Brownian motion and thermophoresis effects. Applying the one-parameter transformation group which reduces the number of independent variables by one and thus, the system of governing partial differential equations has been converted to a set of nonlinear ordinary differential equations, and these equations are then computed numerically using the implicit finite-difference scheme. Comparison with previously published studies is executed and the results are found to be in excellent agreement. Results for the velocity, temperature, and the nanoparticle volume fraction profiles as well as the local skin-friction coefficient and local Nusselt number are presented in graphical and tabular forms, and discussed for different values of the governing parameters to show interesting features of the solutions.

  20. Symmetry Reduction, Exact Solutions, and Conservation Laws of the (2+1)-Dimensional Dispersive Long Wave Equations

    Science.gov (United States)

    Dong, Zhong Zhou; Chen, Yong

    2009-10-01

    By means of the generalized direct method, we investigate the (2+1)-dimensional dispersive long wave equations. A relationship is constructed between the new solutions and the old ones and we obtain the full symmetry group of the (2+1)-dimensional dispersive long wave equations, which includes the Lie point symmetry group S and the discrete groups D. Some new forms of solutions are obtained by selecting the form of the arbitrary functions, based on their relationship. We also find an infinite number of conservation laws of the (2+1)-dimensional dispersive long wave equations.

  1. AFLOWSYM: A robust procedure to perform the complete symmetry analysis of crystals

    Science.gov (United States)

    Hicks, David; Oses, Corey; Curtarolo, Stefano

    Determination of the symmetry profile of structures is a persistent challenge in materials science as evident from implementation-specific results. Herein, we present a robust procedure for evaluating the complete suite of symmetry operations, including that of the lattice point group, factor group, crystallographic point group, and space group. The protocol resolves a system-specific mapping tolerance, which accounts for variability of error in reported atomic positions. A tolerance is validated through an analysis of the operations it defines, which must all be consistent with fundamental crystallographic principles. The approach has been successfully tested against the Inorganic Crystal Structure Database (ICSD) entries cataloged in the aflow.org online repository. The AFLOWSYM package is implemented within the automatic, high-throughput computational framework AFLOW and is available for public use at aflow.org.

  2. Dynamical symmetries for fermions

    International Nuclear Information System (INIS)

    Guidry, M.

    1989-01-01

    An introduction is given to the Fermion Dynamical Symmetry Model (FDSM). The analytical symmetry limits of the model are then applied to the calculation of physical quantities such as ground-state masses and B(E 2 ) values in heavy nuclei. These comparisons with data provide strong support for a new principle of collective motion, the Dynamical Pauli Effect, and suggest that dynamical symmetries which properly account for the pauli principle are much more persistent in nuclear structure than the corresponding boson symmetries. Finally, we present an assessment of criticisms which have been voiced concerning the FDSM, and a discussion of new phenomena and ''exotic spectroscopy'' which may be suggested by the model. 14 refs., 8 figs., 4 tabs

  3. Gauge symmetry from decoupling

    Directory of Open Access Journals (Sweden)

    C. Wetterich

    2017-02-01

    Full Text Available Gauge symmetries emerge from a redundant description of the effective action for light degrees of freedom after the decoupling of heavy modes. This redundant description avoids the use of explicit constraints in configuration space. For non-linear constraints the gauge symmetries are non-linear. In a quantum field theory setting the gauge symmetries are local and can describe Yang–Mills theories or quantum gravity. We formulate gauge invariant fields that correspond to the non-linear light degrees of freedom. In the context of functional renormalization gauge symmetries can emerge if the flow generates or preserves large mass-like terms for the heavy degrees of freedom. They correspond to a particular form of gauge fixing terms in quantum field theories.

  4. Wigner's Symmetry Representation Theorem

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 19; Issue 10. Wigner's Symmetry Representation Theorem: At the Heart of Quantum Field Theory! Aritra Kr Mukhopadhyay. General Article Volume 19 Issue 10 October 2014 pp 900-916 ...

  5. Symmetry generators in singular theories

    International Nuclear Information System (INIS)

    Lavrov, P.M.; Tyutin, I.V.

    1989-01-01

    It is proved that in the singular nondegenerate theories any symmetry of the lagrangian under non-point transformations of lagrangian variables with the open (in the general case) algebra in the hamiltonian approach generates corresponding transformations of canonical variables the generator of which is the Noether charge with respect to the Dirac brackets. On the surface of all constraints these transformations leave the hamiltonian invariant and the algebra of the Noether charges is closed. As a consequence it is shown that the nilpotent BRST charge operator always exists in gauge theories of the general form (if possible anomalies are not taken into account)

  6. Mirror symmetry, chiral symmetry breaking, and antihydrogen states in natural atomic H

    CERN Document Server

    Van Hooydonk, G

    2002-01-01

    Molecular band spectra reveal a left-right symmetry for atoms Yvan Hooydonk, Spectrochim. Acta A 56, 2273 (2000)¿. Intra-atomic left- right symmetry points to antiatom states and, to make sense, this must also show in line spectra. H Lyman ns singlets show a mirror plane at quantum number n/sub 0/= 1/2 pi . A symmetry-breaking oscillator (1- 1/2 pi /n)/sup 2/ means that some of these n states are antihydrogenic. This view runs ahead of CERN's antiproton decelerator project on antihydrogen. (7 refs).

  7. Frameworks with crystallographic symmetry.

    Science.gov (United States)

    Borcea, Ciprian S; Streinu, Ileana

    2014-02-13

    Periodic frameworks with crystallographic symmetry are investigated from the perspective of a general deformation theory of periodic bar-and-joint structures in Euclidean spaces of arbitrary dimension. It is shown that natural parametrizations provide affine section descriptions for families of frameworks with a specified graph and symmetry. A simple geometrical setting for displacive phase transitions is obtained. Upper bounds are derived for the number of realizations of minimally rigid periodic graphs.

  8. Interactions between constituent single symmetries in multiple symmetry

    NARCIS (Netherlands)

    Treder, M.S.; Vloed, G. van der; Helm, P.A. van der

    2011-01-01

    As a rule, the discriminability of multiple symmetries from random patterns increases with the number of symmetry axes, but this number does not seem to be the only determinant. In particular, multiple symmetries with orthogonal axes seem better discriminable than multiple symmetries with

  9. On radiative gauge symmetry breaking in the minimal supersymmetric model

    International Nuclear Information System (INIS)

    Gamberini, G.; Ridolfi, G.; Zwirner, F.

    1990-01-01

    We present a critical reappraisal of radiative gauge symmetry breaking in the minimal supersymmetric standard model. We show that a naive use of the renormalization group improved tree-level potential can lead to incorrect conclusions. We specify the conditions under which the above method gives reliable results, by performing a comparison with the results obtained from the full one-loop potential. We also point out how the stability constraint and the conditions for the absence of charge- and colour-breaking minima should be applied. Finally, we comment on the uncertainties affecting the model predictions for physical observables, in particular for the top quark mass. (orig.)

  10. [Evaluating how health is prioritised in Colombia from the point of view of Bogotá-based research groups].

    Science.gov (United States)

    Escobar-Díaz, Fabio A; Agudelo, Carlos A

    2009-01-01

    Assessing how priorities are established in Colombia in line with international methodologies and from the perspective of Bogotá-based Category A health research groups. This study used a qualitative approach; 14 leaders from groups selected via a propositive sample were given semi-structured interviews to obtain a comprehensive interpretation of priority-setting in Colombia. ATLAS Ti software was used for organising information and producing categories from transcripts. Each group had a different research background and came from health research areas such as basic science, clinical science and the wide field of public health. Some talked about their own definitions of health and establishing priorities as related to their own epistemological frameworks. Other leaders stressed that a bio-medical approach still predominated in health research, priority-setting and the inter-national methodologies used for such end. Many recognised the importance of differ-ent social actors (i.e. apart from researchers) becoming involved in defining health research priorities within a scenario emphasising dialogue and coming to agreement. The leaders criticised the national health science and technology system raising questions regarding defining priorities; they stated that dialogue and involvement must be promoted. These findings revealed enormous heterogeneity regarding prioritising health research as every researcher has a different point of view due to their experience and backgrounds and the difficulties in researchers' reaching consensus.

  11. Symmetries of Mücket-Treder's two-body problem

    Science.gov (United States)

    Mioc, V.

    The two-body problem associated to the classical potential field proposed by Mücket and Treder (1977) is considered from the only standpoint of symmetries. The corresponding vector field in Hamiltonian or standard polar coordinates presents nice symmetries that form eight-element symmetric Abelian groups endowed with an idempotent structure. Expressed in Levi-Civita coordinates, the problem exhibits a sixteen-element group of symmetries, also Abelian and presenting an idempotent structure.

  12. Dynamical symmetry breakdown in SU(5) and SO(10)

    International Nuclear Information System (INIS)

    Shellard, R.C.

    1983-09-01

    Some restrictions imposed upon Grand Unified Theories by dynamical symmetry breakdown are examined. It is observed in particular, that theories with SU(5) as symmetry group, with 3 or more fermion families undergo dynamical symmetry breakdown, and some of the fermions will acquire mass at the Grand Unified scale. On the other hand, the SO(10) group, with 3 families is free from this problem. (Author) [pt

  13. Nonlocal Symmetries and Exact Solutions for PIB Equation

    Science.gov (United States)

    Xin, Xiang-Peng; Miao, Qian; Chen, Yong

    2012-09-01

    In this paper, the symmetry group of the (2+1)-dimensional Painlevé integrable Burgers (PIB) equations is studied by means of the classical symmetry method. Ignoring the discussion of the infinite-dimensional subalgebra, we construct an optimal system of one-dimensional group invariant solutions. Furthermore, by using the conservation laws of the reduced equations, we obtain nonlocal symmetries and exact solutions of the PIB equations.

  14. Researching the value system of interest groups as the starting point for directing urbanisation of the countryside

    Directory of Open Access Journals (Sweden)

    Mojca Golobič

    2001-01-01

    Full Text Available When planning rehabilitation of transitory, rural space, where processes of restructuring agriculture intertwine with urban processes, key definitions concern places where restructuring agriculture and changes in land use are causing degradation and places where further urbanisation or re-naturation are the better option. In these definitions it is necessary to follow opinions and goals of users that are nevertheless difficult to obtain in a mode that can be directly integrated in standardised rational procedures of physical planning. The presented procedure facilitates the procurement of such knowledge and its transparent integration in local development plans. Thus we can identify interest groups, their viewpoints, and potential conflicts in initial value systems and check their conflicting or harmonising starting points in space.

  15. Symmetries and conservation laws of the damped harmonic oscillator

    Indian Academy of Sciences (India)

    then a continuous symmetry transformation (point, contact or higher-order) that leaves the action functional invariant yields a conservation law. Thus studies in symmetries and conservation laws of a physical system using this theorem require the associated equation of motion to follow from the action principle [2]. The object ...

  16. Lie and Noether symmetries of systems of complex ordinary ...

    Indian Academy of Sciences (India)

    The Lie and Noether point symmetry analyses of a th-order system of complex ordinary differential equations (ODEs) with dependent variables are performed. The decomposition of complex symmetries of the given system of complex ODEs yields Lie- and Noether-like operators. The system of complex ODEs can be ...

  17. Non-geometric fluxes and mixed-symmetry potentials

    NARCIS (Netherlands)

    Bergshoeff, E.A.; Penas, V.A.; Riccioni, F.; Risoli, S.

    2015-01-01

    We discuss the relation between generalised fluxes and mixed-symmetry potentials. We refer to the fluxes that cannot be described even locally in the framework of supergravity as ‘non-geometric’. We first consider the NS fluxes, and point out that the non-geometric R flux is dual to a mixed-symmetry

  18. A complete symmetry classification and reduction of some classes of ...

    African Journals Online (AJOL)

    ... dimensional Lie algebras of point symmetry generators are used to construct exact solutions for some classes invariant under the subalgebra. Comparisons and other significant results regarding other equations, like the Laplace's equation, are made. Keywords: Lie symmetry classification; nonlinear (1-2) wave equation

  19. Antiunitary symmetry operators in quantum mechanics

    International Nuclear Information System (INIS)

    Carinena, J.F.; Santander, M.

    1981-01-01

    A criterion to decide that some symmetries of a quantum system must be realized as antiunitary operators is given. It is based on some mathematical theorems about the second cohomology group of the symmetry group when expressed in terms of those of a normal subgroup and the corresponding factor group. It is also shown that this criterion implies that the only possibility for the unitary subgroup in the Galilean case is that generated by the space reflection and the connected component containing the identity; otherwise only massless systems would arise. (author)

  20. Support for a ban on tobacco powerwalls and other point-of-sale displays: findings from focus groups.

    Science.gov (United States)

    Schmitt, Carol L; Allen, Jane A; Kosa, Katherine M; Curry, Laurel E

    2015-02-01

    This study uses focus group data to document consumer perceptions of powerwall and other point-of-sale (POS) tobacco displays, and support for a ban on tobacco displays. Four focus groups were conducted in 2012 by a trained moderator. The study comprised 34 adult residents of New York State, approximately half with children under age 18 years living at home. Measures used in the study were awareness and perceptions of powerwall and other POS displays, and level of support for a ban on tobacco displays. Analysis focused on perceptions of powerwall and other POS displays, level of support for a ban on tobacco displays and reasons participants oppose a display ban. This study documents a general lack of concern about tobacco use in the community, which does not appear to be associated with support for a ban on POS tobacco displays. Although all participants had seen tobacco powerwalls and most considered them to be a form of advertising, participants were divided as to whether they played a role in youth smoking. Additional research is warranted to determine what factors individuals weigh in assigning value to a ban on POS tobacco displays and other tobacco control policies and how educational efforts can influence those assessments. © The Author 2014. Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  1. Calculation procedure for formulating lauric and palmitic fat blends based on the grouping of triacylglycerol melting points

    International Nuclear Information System (INIS)

    Nusantoro, B.P.; Yanty, N.A.M.; Van de Walle, D.; Hidayat, C.; Danthine, S.; Dewettinck, K.

    2017-01-01

    A calculation procedure for formulating lauric and palmitic fat blends has been developed based on grouping TAG melting points. This procedure offered more flexibility in choosing the initial fats and oils and eventually gave deeper insight into the existing chemical compositions and better prediction on the physicochemical properties and microstructure of the fat blends. The amount of high, medium and low melting TAGs could be adjusted using the given calculation procedure to obtain the desired functional properties in the fat blends. Solid fat contents and melting behavior of formulated fat blends showed particular patterns with respect to ratio adjustments of the melting TAG groups. These outcomes also suggested that both TAG species and their quantity had a significant influence on the crystallization behavior of the fat blends. Palmitic fat blends, in general, were found to exhibit higher SFC values than those of Lauric fat blends. Instead of the similarity in crystal microstructure, lauric fat blends were stabilized at β polymorph while palmitic fat blends were stabilized at β’ polymorph. [es

  2. Partial Dynamical Symmetry in a Many-Fermion System

    International Nuclear Information System (INIS)

    Escher, J.; Leviatan, A.

    1999-01-01

    Partial dynamical symmetry (PDS) describes a situation in which some eigenstates exhibit a symmetry which the associated Hamiltonian does not share. We present a family of fermionic Hamiltonians with partial SU(3) symmetry in the framework of the Symplectic Shell Model. We briefly review the symplectic theory and establish a relation between the PDS Hamiltonians and commonly employed symplectic Hamiltonians. Characteristics of the PDS eigenstates are discussed and the resulting spectra are compared to those of real nuclei. We point out similarities and differences between the fermion case and a recently established partial SU(3) symmetry in the Interacting Boson Model

  3. Hidden superconformal symmetry: Where does it come from?

    Science.gov (United States)

    Inzunza, Luis; Plyushchay, Mikhail S.

    2018-02-01

    It is known that a single quantum harmonic oscillator is characterized by a hidden spectrum generating superconformal symmetry, but its origin has remained rather obscure. We show how this hidden superconformal symmetry can be derived by applying a nonlocal Foldy-Wouthuysen transformation to three extended systems with fermion degrees of freedom. The associated systems have essentially different nature from the point of view of conventional supersymmetric quantum mechanics, and generate the desired hidden symmetry in three different ways. We also trace out how the hidden superconformal symmetry of the quantum free particle system is produced in the limit of zero frequency.

  4. Physics from symmetry

    CERN Document Server

    Schwichtenberg, Jakob

    2018-01-01

    This is a textbook that derives the fundamental theories of physics from symmetry. It starts by introducing, in a completely self-contained way, all mathematical tools needed to use symmetry ideas in physics. Thereafter, these tools are put into action and by using symmetry constraints, the fundamental equations of Quantum Mechanics, Quantum Field Theory, Electromagnetism, and Classical Mechanics are derived. As a result, the reader is able to understand the basic assumptions behind, and the connections between the modern theories of physics. The book concludes with first applications of the previously derived equations. Thanks to the input of readers from around the world, this second edition has been purged of typographical errors and also contains several revised sections with improved explanations. .

  5. Electroweak symmetry breaking

    Energy Technology Data Exchange (ETDEWEB)

    Chanowitz, M.S.

    1990-09-01

    The Higgs mechanism is reviewed in its most general form, requiring the existence of a new symmetry-breaking force and associated particles, which need not however be Higgs bosons. The first lecture reviews the essential elements of the Higgs mechanism, which suffice to establish low energy theorems for the scattering of longitudinally polarized W and Z gauge bosons. An upper bound on the scale of the symmetry-breaking physics then follows from the low energy theorems and partial wave unitarity. The second lecture reviews particular models, with and without Higgs bosons, paying special attention to how the general features discussed in lecture 1 are realized in each model. The third lecture focuses on the experimental signals of strong WW scattering that can be observed at the SSC above 1 TeV in the WW subenergy, which will allow direct measurement of the strength of the symmetry-breaking force. 52 refs., 10 figs.

  6. Application of symmetry operation measures in structural inorganic chemistry.

    Science.gov (United States)

    Echeverría, Jorge; Alvarez, Santiago

    2008-12-01

    This paper presents an application of the recently proposed symmetry operation measures to the determination of the effective symmetry point group of coordination polyhedra in inorganic solids. Several structure types based on octahedra are found to present distinct distortion patterns each, not strictly attached to the crystallographic site symmetry. These include the (NH4)2[CuCl4], CdI2 (brucite), FeS2 (pyrite), TiO2 (rutile), CaCl2, GdFeO3, PbTiO3,LiNbO3, BiI3, CrCl3, Al2O3, and NiWO4 structures. It is shown that a similar analysis can be applied to the Bailar and tetragonal Jahn-Teller distortions of molecular transition metal complexes, as well as to solids based on tetrahedra, such as the ZnCl2, FeS, BeCl2, SiS2, and KFeS2 structure types.

  7. Measures with symmetry properties

    CERN Document Server

    Schindler, Werner

    2003-01-01

    Symmetries and invariance principles play an important role in various branches of mathematics. This book deals with measures having weak symmetry properties. Even mild conditions ensure that all invariant Borel measures on a second countable locally compact space can be expressed as images of specific product measures under a fixed mapping. The results derived in this book are interesting for their own and, moreover, a number of carefully investigated examples underline and illustrate their usefulness and applicability for integration problems, stochastic simulations and statistical applications.

  8. Symmetry, structure, and spacetime

    CERN Document Server

    Rickles, Dean

    2007-01-01

    In this book Rickles considers several interpretative difficulties raised by gauge-type symmetries (those that correspond to no change in physical state). The ubiquity of such symmetries in modern physics renders them an urgent topic in philosophy of physics. Rickles focuses on spacetime physics, and in particular classical and quantum general relativity. Here the problems posed are at their most pathological, involving the apparent disappearance of spacetime! Rickles argues that both traditional ontological positions should be replaced by a structuralist account according to which relational

  9. Operational symmetries basic operations in physics

    CERN Document Server

    Saller, Heinrich

    2017-01-01

    This book describes the endeavour to relate the particle spectrum with representations of operational electroweak spacetime, in analogy to the atomic spectrum as characterizing representations of hyperbolic space. The spectrum of hyperbolic position space explains the properties of the nonrelativistic atoms; the spectrum of electroweak spacetime is hoped to explain those of the basic interactions and elementary particles. In this book, the theory of operational symmetries is developed from the numbers, from Plato’s and Kepler’s symmetries over the simple Lie groups to their applications in nonrelativistic, special relativistic and general relativistic quantum theories with the atomic spectrum for hyperbolic position and, in first attempts, the particle spectrum for electroweak spacetime. The standard model of elementary particles and interactions is characterized by a symmetry group. In general, as initiated by Weyl and stressed by Heisenberg, quantum theory can be built as a theory of operation groups an...

  10. Effective operators and extended symmetry

    CERN Document Server

    Frère, J M; Moreno, J M; Orloff, J

    1994-01-01

    In this note we expand on our previous study of the implications of LEP1 results for future colliders. We extend the effective operator-based analysis of De R\\'ujula et al. to a larger symmetry group, and show at which cost their expectations can be relaxed. Of particular interest to experiment is a rephrasing of our previous results in terms of the Renard et al. parametrization for the gauge boson self-couplings (slightly extended to include $\\delta g_{\\gamma}$). We suggest the use of a ($\\delta g_{\\gamma}$, $\\delta g_{Z}$) plot to confront the expectations of various models.

  11. Holographic Metals and Insulators with Helical Symmetry

    CERN Document Server

    Donos, Aristomenis; Kiritsis, Elias

    2014-01-01

    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.

  12. Spectroscopic criteria for identification of nuclear tetrahedral and octahedral symmetries: Illustration on a rare earth nucleus

    Science.gov (United States)

    Dudek, J.; Curien, D.; Dedes, I.; Mazurek, K.; Tagami, S.; Shimizu, Y. R.; Bhattacharjee, T.

    2018-02-01

    We formulate criteria for identification of the nuclear tetrahedral and octahedral symmetries and illustrate for the first time their possible realization in a rare earth nucleus 152Sm. We use realistic nuclear mean-field theory calculations with the phenomenological macroscopic-microscopic method, the Gogny-Hartree-Fock-Bogoliubov approach, and general point-group theory considerations to guide the experimental identification method as illustrated on published experimental data. Following group theory the examined symmetries imply the existence of exotic rotational bands on whose properties the spectroscopic identification criteria are based. These bands may contain simultaneously states of even and odd spins, of both parities and parity doublets at well-defined spins. In the exact-symmetry limit those bands involve no E 2 transitions. We show that coexistence of tetrahedral and octahedral deformations is essential when calculating the corresponding energy minima and surrounding barriers, and that it has a characteristic impact on the rotational bands. The symmetries in question imply the existence of long-lived shape isomers and, possibly, new waiting point nuclei—impacting the nucleosynthesis processes in astrophysics—and an existence of 16-fold degenerate particle-hole excitations. Specifically designed experiments which aim at strengthening the identification arguments are briefly discussed.

  13. Fermion-induced quantum critical points

    OpenAIRE

    Li, Zi-Xiang; Jiang, Yi-Fan; Jian, Shao-Kai; Yao, Hong

    2017-01-01

    A unified theory of quantum critical points beyond the conventional Landau?Ginzburg?Wilson paradigm remains unknown. According to Landau cubic criterion, phase transitions should be first-order when cubic terms of order parameters are allowed by symmetry in the Landau?Ginzburg free energy. Here, from renormalization group analysis, we show that second-order quantum phase transitions can occur at such putatively first-order transitions in interacting two-dimensional Dirac semimetals. As such t...

  14. Group theory for chemists fundamental theory and applications

    CERN Document Server

    Molloy, K C

    2010-01-01

    The basics of group theory and its applications to themes such as the analysis of vibrational spectra and molecular orbital theory are essential knowledge for the undergraduate student of inorganic chemistry. The second edition of Group Theory for Chemists uses diagrams and problem-solving to help students test and improve their understanding, including a new section on the application of group theory to electronic spectroscopy.Part one covers the essentials of symmetry and group theory, including symmetry, point groups and representations. Part two deals with the application of group theory t

  15. Interactions between constituent single symmetries in multiple symmetry.

    Science.gov (United States)

    Treder, Matthias Sebastian; van der Vloed, Gert; van der Helm, Peter A

    2011-07-01

    As a rule, the discriminability of multiple symmetries from random patterns increases with the number of symmetry axes, but this number does not seem to be the only determinant. In particular, multiple symmetries with orthogonal axes seem better discriminable than multiple symmetries with nonorthogonal axes. In six experiments on imperfect two-fold symmetry, we investigated whether this is due to extra structure in the form of so-called correlation rectangles, which arise only in the case of orthogonal axes, or to the relative orientation of the axes as such. The results suggest that correlation rectangles are not perceptually relevant and that the percept of a multiple symmetry results from an orientation-dependent interaction between the constituent single symmetries. The results can be accounted for by a model involving the analysis of symmetry at all orientations, smoothing (averaging over neighboring orientations), and extraction of peaks.

  16. Testing for central symmetry

    NARCIS (Netherlands)

    Einmahl, John; Gan, Zhuojiong

    Omnibus tests for central symmetry of a bivariate probability distribution are proposed. The test statistics compare empirical measures of opposite regions. Under rather weak conditions, we establish the asymptotic distribution of the test statistics under the null hypothesis; it follows that they

  17. Symmetries in fundamental physics

    CERN Document Server

    Sundermeyer, Kurt

    2014-01-01

    Over the course of the last century it has become clear that both elementary particle physics and relativity theories are based on the notion of symmetries. These symmetries become manifest in that the "laws of nature" are invariant under spacetime transformations and/or gauge transformations. The consequences of these symmetries were analyzed as early as in 1918 by Emmy Noether on the level of action functionals. Her work did not receive due recognition for nearly half a century, but can today be understood as a recurring theme in classical mechanics, electrodynamics and special relativity, Yang-Mills type quantum field theories, and in general relativity. As a matter of fact, as shown in this monograph, many aspects of physics can be derived solely from symmetry considerations. This substantiates the statement of E.P.Wigner "... if we knew all the laws of nature, or the ultimate Law of nature, the invariance properties of these laws would not furnish us new information." Thanks to Wigner we now also underst...

  18. Introduction to Chiral Symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Koch, Volker [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2017-05-09

    These lectures are an attempt to a pedagogical introduction into the elementary concepts of chiral symmetry in nuclear physics. We will also discuss some effective chiral models such as the linear and nonlinear sigma model as well as the essential ideas of chiral perturbation theory. We will present some applications to the physics of ultrarelativistic heavy ion collisionsd.

  19. Horror Vacui Symmetry.

    Science.gov (United States)

    Crumpecker, Cheryl

    2003-01-01

    Describes an art lesson used with children in the third grade to help them learn about symmetry, as well as encouraging them to draw larger than usual. Explains that students learn about the belief called "Horror Vacui" of the Northwest American Indian tribes and create their interpretation of this belief. (CMK)

  20. Symmetries in fundamental physics

    CERN Document Server

    Sundermeyer, Kurt

    2014-01-01

    Over the course of the last century it has become clear that both elementary particle physics and relativity theories are based on the notion of symmetries. These symmetries become manifest in that the "laws of nature" are invariant under spacetime transformations and/or gauge transformations. The consequences of these symmetries were analyzed as early as in 1918 by Emmy Noether on the level of action functionals. Her work did not receive due recognition for nearly half a century, but can today be understood as a recurring theme in classical mechanics, electrodynamics and special relativity, Yang-Mills type quantum field theories, and in general relativity. As a matter of fact, as shown in this monograph, many aspects of physics can be derived solely from symmetry considerations. This substantiates the statement of E.P. Wigner "... if we knew all the laws of nature, or the ultimate Law of nature, the invariance properties of these laws would not furnish us new information." Thanks to Wigner we now also unders...

  1. Classical mirror symmetry

    CERN Document Server

    Jinzenji, Masao

    2018-01-01

    This book furnishes a brief introduction to classical mirror symmetry, a term that denotes the process of computing Gromov–Witten invariants of a Calabi–Yau threefold by using the Picard–Fuchs differential equation of period integrals of its mirror Calabi–Yau threefold. The book concentrates on the best-known example, the quintic hypersurface in 4-dimensional projective space, and its mirror manifold. First, there is a brief review of the process of discovery of mirror symmetry and the striking result proposed in the celebrated paper by Candelas and his collaborators. Next, some elementary results of complex manifolds and Chern classes needed for study of mirror symmetry are explained. Then the topological sigma models, the A-model and the B-model, are introduced. The classical mirror symmetry hypothesis is explained as the equivalence between the correlation function of the A-model of a quintic hyper-surface and that of the B-model of its mirror manifold. On the B-model side, the process of construct...

  2. Deformations of spacetime and internal symmetries

    Directory of Open Access Journals (Sweden)

    Gresnigt Niels G.

    2017-01-01

    Full Text Available Algebraic deformations provide a systematic approach to generalizing the symmetries of a physical theory through the introduction of new fundamental constants. The applications of deformations of Lie algebras and Hopf algebras to both spacetime and internal symmetries are discussed. As a specific example we demonstrate how deforming the classical flavor group S U(3 to the quantum group S Uq(3 ≡ U q (su(3 (a Hopf algebra and taking into account electromagnetic mass splitting within isospin multiplets leads to new and exceptionally accurate baryon mass sum rules that agree perfectly with experimental data.

  3. Higgsless approach to electroweak symmetry breaking

    CERN Document Server

    Grojean, Christophe

    2007-01-01

    Higgsless models are an attempt to achieve a breaking of the electroweak symmetry via boundary conditions at the end-points of a fifth dimension compactified on an interval, as an alternative to the usual Higgs mechanism. There is no physical Higgs scalar in the spectrum and the perturbative unitarity violation scale is delayed via the exchange of massive spin-1 KK resonances. The correct mass spectrum is reproduced in a model in warped space, which inherits a custodial symmetry from a left–right gauge symmetry in the bulk. Phenomenological challenges as well as collider signatures are presented. From the AdS/CFT perspective, this model appears as a weakly coupled dual to walking technicolour models.

  4. Supersymmetric defect models and mirror symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Hook, Anson; Kachru, Shamit; Torroba, Gonzalo

    2013-11-01

    We study supersymmetric field theories in three space-time dimensions doped by various configurations of electric charges or magnetic fluxes. These are supersymmetric avatars of impurity models. In the presence of additional sources such configurations are shown to preserve half of the supersymmetries. Mirror symmetry relates the two sets of configurations. We discuss the implications for impurity models in 3d NN = 4 QED with a single charged hypermultiplet (and its mirror, the theory of a free hypermultiplet) as well as 3d NN = 2 QED with one flavor and its dual, a supersymmetric Wilson-Fisher fixed point. Mirror symmetry allows us to find backreacted solutions for arbitrary arrays of defects in the IR limit of NN = 4 QED. Our analysis, complemented with appropriate string theory brane constructions, sheds light on various aspects of mirror symmetry, the map between particles and vortices and the emergence of ground state entropy in QED at finite density.

  5. Symmetry and bifurcations of momentum mappings

    Energy Technology Data Exchange (ETDEWEB)

    Arms, J.M.; Marsden, J.E.; Moncrief, V.

    1981-01-01

    The zero set of a momentum mapping is shown to have a singularity at each point with symmetry. The zero set is diffeomorphic to the product of a manifold and the zero set of a homogeneous quadratic function. The proof uses the Kuranishi theory of deformations. Among the applications, it is shown that the set of all solutions of the Yang-Mills equations on a Lorentz manifold has a singularity at any solution with symmetry, in the sense of a pure gauge symmetry. Similarly, the set of solutions of Einstein's equations has a singularity at any solution that has spacelike Killing fields, provided the spacetime has a compact Cauchy surface.

  6. Symmetry characterization of eigenstates in opal-based photonic crystals

    CERN Document Server

    López-Torres, E; Sakoda, K; Sánchez-Dehesa, J

    2002-01-01

    The complete symmetry characterization of eigenstates in bare opal systems is obtained by means of group theory. This symmetry assignment has allowed us to identify several bands that cannot couple with an incident external plane wave. Our prediction is supported by layer-KKR calculations, which are also performed: the coupling coefficients between bulk modes and externally excited field tend to zero when symmetry properties mismatch.

  7. Asymmetry and Symmetry in the Beauty of Human Faces

    Directory of Open Access Journals (Sweden)

    Marjan Hessamian

    2010-02-01

    Full Text Available The emphasis in the published literature has mostly been on symmetry as the critical source for beauty judgment. In fact, both symmetry and asymmetry serve as highly aesthetic sources of beauty, whether the context is perceptual or conceptual. The human brain is characterized by symbolic cognition and this type of cognition facilitates a range of aesthetic reactions. For example, both art and natural scenery contain asymmetrical elements, which nevertheless render the whole effect beautiful. A further good case in point is, in fact, human faces. Normally, faces are structurally left-right symmetrical content-wise but not size-wise or function-wise. Attractiveness has often been discussed in terms of content-wise full-face symmetry. To test whether or not attractiveness can be gleaned only from the presence of left-right full-faces we tested half faces. Three separate groups of participants viewed and rated the attractiveness of 56 full-faces (women’s and men’s, their 56 vertical left hemi-faces and 56 vertical right hemi-faces. We found no statistically significant differences in the attractiveness ratings of full- and hemi-faces (whether left or right. Instead, we found a strong and significant positive correlation between the ratings of the hemi- and full-faces. These results are consistent with the view that the underpinning of human facial beauty is complex and that bilateral symmetry does not constitute a principle factor in beauty assessment. We discuss that the highly evolved human brain, compared to other animals, as well as symbolic and abstract cognition in humans enable a wide variety of aesthetic reactions.

  8. Weyl-gauge symmetry of graphene

    International Nuclear Information System (INIS)

    Iorio, Alfredo

    2011-01-01

    Research highlights: → Graphene action's Weyl symmetry identifies shapes for which the DOS is invariant. → Electrons on graphene might experience a general-relativistic-like spacetime. → Rich mathematical structures, such as the Liouville's equation, naturally arise. - Abstract: 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.

  9. Dynamical symmetries of the shell model

    Energy Technology Data Exchange (ETDEWEB)

    Van Isacker, P

    2000-07-01

    The applications of spectrum generating algebras and of dynamical symmetries in the nuclear shell model are many and varied. They stretch back to Wigner's early work on the supermultiplet model and encompass important landmarks in our understanding of the structure of the atomic nucleus such as Racah's SU(2) pairing model and Elliot's SU(3) rotational model. One of the aims of this contribution has been to show the historical importance of the idea of dynamical symmetry in nuclear physics. Another has been to indicate that, in spite of being old, this idea continues to inspire developments that are at the forefront of today's research in nuclear physics. It has been argued in this contribution that the main driving features of nuclear structure can be represented algebraically but at the same time the limitations of the symmetry approach must be recognised. It should be clear that such approach can only account for gross properties and that any detailed description requires more involved numerical calculations of which we have seen many fine examples during this symposium. In this way symmetry techniques can be used as an appropriate starting point for detailed calculations. A noteworthy example of this approach is the pseudo-SU(3) model which starting from its initial symmetry Ansatz has grown into an adequate and powerful description of the nucleus in terms of a truncated shell model. (author)

  10. Chiral Symmetry, Heavy Quark Symmetry and Bound States

    OpenAIRE

    Yoshida, Yuhsuke

    1995-01-01

    I investigate the bound state problems of lowest-lying mesons and heavy mesons. Chiral symmetry is essential when one consider lowest-lying mesons. Heavy quark symmetry plays an central role in considering the semi-leptonic form factors of heavy mesons. Various properties based on the symmetries are revealed using Bethe-Salpeter equations.

  11. Benchmarking Density Functional Theory Approaches for the Description of Symmetry-Breaking in Long Polymethine Dyes

    KAUST Repository

    Gieseking, Rebecca L.

    2016-04-25

    Long polymethines are well-known experimentally to symmetry-break, which dramatically modifies their linear and nonlinear optical properties. Computational modeling could be very useful to provide insight into the symmetry-breaking process, which is not readily available experimentally; however, accurately predicting the crossover point from symmetric to symmetry-broken structures has proven challenging. Here, we benchmark the accuracy of several DFT approaches relative to CCSD(T) geometries. In particular, we compare analogous hybrid and long-range corrected (LRC) functionals to clearly show the influence of the functional exchange term. Although both hybrid and LRC functionals can be tuned to reproduce the CCSD(T) geometries, the LRC functionals are better performing at reproducing the geometry evolution with chain length and provide a finite upper limit for the gas-phase crossover point; these methods also provide good agreement with the experimental crossover points for more complex polymethines in polar solvents. Using an approach based on LRC functionals, a reduction in the crossover length is found with increasing medium dielectric constant, which is related to localization of the excess charge on the end groups. Symmetry-breaking is associated with the appearance of an imaginary frequency of b2 symmetry involving a large change in the degree of bond-length alternation. Examination of the IR spectra show that short, isolated streptocyanines have a mode at ~1200 cm-1 involving a large change in bond-length alternation; as the polymethine length or the medium dielectric increases, the frequency of this mode decreases before becoming imaginary at the crossover point.

  12. Ten key points for the appropriate use of antibiotics in hospitalised patients: a consensus from the Antimicrobial Stewardship and Resistance Working Groups of the International Society of Chemotherapy

    NARCIS (Netherlands)

    Hara, G. Levy; Kanj, S.S.; Pagani, L.; Abbo, L.; Endimiani, A.; Wertheim, H.F.L.; Amabile-Cuevas, C.; Tattevin, P.; Mehtar, S.; Cardoso, F.; Unal, S.; Gould, I.

    2016-01-01

    The Antibiotic Stewardship and Resistance Working Groups of the International Society for Chemotherapy propose ten key points for the appropriate use of antibiotics in hospital settings. (i) Get appropriate microbiological samples before antibiotic administration and carefully interpret the results:

  13. Gauged discrete symmetries and proton stability

    International Nuclear Information System (INIS)

    Mohapatra, Rabindra N.; Ratz, Michael

    2007-01-01

    We discuss the results of a search for anomaly-free Abelian Z N discrete symmetries that lead to automatic R-parity conservation and prevent dangerous higher-dimensional proton decay operators in simple extensions of minimal supersymmetric extension of the standard model based on the left-right symmetric group, the Pati-Salam group and SO(10). We require that the superpotential for the models have enough structures to be able to give correct symmetry breaking to minimal supersymmetric extension of the standard model and potentially realistic fermion masses. We find viable models in each of the extensions, and for all the cases, anomaly freedom of the discrete symmetry restricts the number of generations

  14. On Symmetries in Optimal Control

    NARCIS (Netherlands)

    Schaft, A.J. van der

    1986-01-01

    We discuss the use of symmetries in solving optimal control problems. In particular a procedure for obtaining symmetries is given which can be performed before the actual calculation of the optimal control and optimal Hamiltonian.

  15. Family symmetries in F-theory GUTs

    CERN Document Server

    King, S F; Ross, G G

    2010-01-01

    We discuss F-theory SU(5) GUTs in which some or all of the quark and lepton families are assigned to different curves and family symmetry enforces a leading order rank one structure of the Yukawa matrices. We consider two possibilities for the suppression of baryon and lepton number violation. The first is based on Flipped SU(5) with gauge group SU(5)\\times U(1)_\\chi \\times SU(4)_{\\perp} in which U(1)_{\\chi} plays the role of a generalised matter parity. We present an example which, after imposing a Z_2 monodromy, has a U(1)_{\\perp}^2 family symmetry. Even in the absence of flux, spontaneous breaking of the family symmetry leads to viable quark, charged lepton and neutrino masses and mixing. The second possibility has an R-parity associated with the symmetry of the underlying compactification manifold and the flux. We construct an example of a model with viable masses and mixing angles based on the gauge group SU(5)\\times SU(5)_{\\perp} with a U(1)_{\\perp}^3 family symmetry after imposing a Z_2 monodromy.

  16. A cyclic symmetry principle in physics

    International Nuclear Information System (INIS)

    Green, H.S.; Adelaide Univ., SA

    1994-01-01

    Many areas of modern physics are illuminated by the application of a symmetry principle, requiring the invariance of the relevant laws of physics under a group of transformations. This paper examines the implications and some of the applications of the principle of cyclic symmetry, especially in the areas of statistical mechanics and quantum mechanics, including quantized field theory. This principle requires invariance under the transformations of a finite group, which may be a Sylow π-group, a group of Lie type, or a symmetric group. The utility of the principle of cyclic invariance is demonstrated in finding solutions of the Yang-Baxter equation that include and generalize known solutions. It is shown that the Sylow π-groups have other uses, in providing a basis for a type of generalized quantum statistics, and in parametrising a new generalization of Lie groups, with associated algebras that include quantized algebras. 31 refs

  17. Symmetry energy of the nucleus in the relativistic Thomas–Fermi ...

    Indian Academy of Sciences (India)

    S HADDAD

    2017-10-26

    Oct 26, 2017 ... GANIL/France, and the GSI facility FAIR in Germany, which produce new data for neutron-rich nuclei. A key point is the ... the value of the nuclear matter symmetry energy is deter- mined at the local density value inside the nucleus. The symmetry energy integral and the symmetry energy of the nucleus are ...

  18. Non-abelian symmetries in tensor networks: A quantum symmetry space approach

    International Nuclear Information System (INIS)

    Weichselbaum, Andreas

    2012-01-01

    A general framework for non-abelian symmetries is presented for matrix-product and tensor-network states in the presence of well-defined orthonormal local as well as effective basis sets. The two crucial ingredients, the Clebsch–Gordan algebra for multiplet spaces as well as the Wigner–Eckart theorem for operators, are accounted for in a natural, well-organized, and computationally straightforward way. The unifying tensor-representation for quantum symmetry spaces, dubbed QSpace, is particularly suitable to deal with standard renormalization group algorithms such as the numerical renormalization group (NRG), the density matrix renormalization group (DMRG), or also more general tensor networks such as the multi-scale entanglement renormalization ansatz (MERA). In this paper, the focus is on the application of the non-abelian framework within the NRG. A detailed analysis is presented for a fully screened spin- 3/2 three-channel Anderson impurity model in the presence of conservation of total spin, particle–hole symmetry, and SU(3) channel symmetry. The same system is analyzed using several alternative symmetry scenarios based on combinations of U(1) charge , SU(2) spin , SU(2) charge , SU(3) channel , as well as the enveloping symplectic Sp(6) symmetry. These are compared in detail, including their respective dramatic gain in numerical efficiency. In the Appendix, finally, an extensive introduction to non-abelian symmetries is given for practical applications, together with simple self-contained numerical procedures to obtain Clebsch–Gordan coefficients and irreducible operators sets. The resulting QSpace tensors can deal with any set of abelian symmetries together with arbitrary non-abelian symmetries with compact, i.e. finite-dimensional, semi-simple Lie algebras. - Highlights: ► We introduce a transparent framework for non-abelian symmetries in tensor networks. ► The framework was successfully applied within the numerical renormalization group.

  19. Symmetry and topology in evolution

    International Nuclear Information System (INIS)

    Lukacs, B.; Berczi, S.; Molnar, I.; Paal, G.

    1991-10-01

    This volume contains papers of an interdisciplinary symposium on evolution. The aim of this symposium, held in Budapest, Hungary, 28-29 May 1991, was to clear the role of symmetry and topology at different levels of the evolutionary processes. 21 papers were presented, their topics included evolution of the Universe, symmetry of elementary particles, asymmetry of the Earth, symmetry and asymmetry of biomolecules, symmetry and topology of lining objects, human asymmetry etc. (R.P.)

  20. Applications of Classical Scaling Symmetry

    OpenAIRE

    Bludman, Sidney

    2011-01-01

    Any symmetry reduces a second-order differential equation to a first-order equation: variational symmetries of the action (exemplified by central field dynamics) lead to conservation laws, but symmetries of only the equations of motion (exemplified by scale-invariant hydrostatics), yield first-order {\\em non-conservation laws} between invariants. We obtain these conservation laws by extending Noether's Theorem to non-variational symmetries, and present a variational formulation of spherical a...

  1. Quantum symmetries in particle interactions

    International Nuclear Information System (INIS)

    Shirkov, D.V.

    1983-01-01

    The concept of a quantum symmetry is introduced as a symmetry in the formulation of which quantum representations and specific quantum notions are used essentially. Three quantum symmetry principles are discussed: the principle of renormalizability (possibly super-renormalizability), the principle of local gauge symmetry, and the principle of supersymmetry. It is shown that these principles play a deterministic role in the development of quantum field theory. Historically their use has led to ever stronger restrictions on the interaction mechanism of quantum fields

  2. Symmetry chains for the atomic shell model. I. Classification of symmetry chains for atomic configurations

    International Nuclear Information System (INIS)

    Gruber, B.; Thomas, M.S.

    1980-01-01

    In this article the symmetry chains for the atomic shell model are classified in such a way that they lead from the group SU(4l+2) to its subgroup SOsub(J)(3). The atomic configurations (nl)sup(N) transform like irreducible representations of the group SU(4l+2), while SOsub(J)(3) corresponds to total angular momentum in SU(4l+2). The defining matrices for the various embeddings are given for each symmetry chain that is obtained. These matrices also define the projection onto the weight subspaces for the corresponding subsymmetries and thus relate the various quantum numbers and determine the branching of representations. It is shown in this article that three (interrelated) symmetry chains are obtained which correspond to L-S coupling, j-j coupling, and a seniority dependent coupling. Moreover, for l<=6 these chains are complete, i.e., there are no other chains but these. In articles to follow, the symmetry chains that lead from the group SO(8l+5) to SOsub(J)(3) will be discussed, with the entire atomic shell transforming like an irreducible representation of SO(8l+5). The transformation properties of the states of the atomic shell will be determined according to the various symmetry chains obtained. The symmetry lattice discussed in this article forms a sublattice of the larger symmetry lattice with SO(8l+5) as supergroup. Thus the transformation properties of the states of the atomic configurations, according to the various symmetry chains discussed in this article, will be obtained too. (author)

  3. Emergence of Symmetries from Entanglement

    CERN Multimedia

    CERN. Geneva

    2016-01-01

    Maximal Entanglement appears to be a key ingredient for the emergence of symmetries. We first illustrate this phenomenon using two examples: the emergence of conformal symmetry in condensed matter systems and  the relation of tensor networks to holography. We further present a Principle of Maximal Entanglement that seems to dictate to a large extend the structure of gauge symmetry.

  4. Broken symmetries in field theory

    NARCIS (Netherlands)

    Kok, Mark Okker de

    2008-01-01

    The thesis discusses the role of symmetries in Quantum Field Theory. Quantum Field Theory is the mathematical framework to describe the physics of elementary particles. A symmetry here means a transformation under which the model at hand is invariant. Three types of symmetry are distinguished: 1.

  5. Partial symmetries in nuclear spectroscopy

    International Nuclear Information System (INIS)

    Leviatan, A.

    1996-01-01

    The notions of exact, dynamical and partial symmetries are discussed in relation to nuclear spectroscopy. Explicit forms of Hamiltonians with partial SU(3) symmetry are presented in the framework of the interacting boson model of nuclei. An analysis of the resulting spectrum and electromagnetic transitions demonstrates the relevance of such partial symmetry to the spectroscopy of axially deformed nuclei. (Author)

  6. CRE Solvability, Nonlocal Symmetry and Exact Interaction Solutions of the Fifth-Order Modified Korteweg-de Vries Equation

    Science.gov (United States)

    Cheng, Wen-Guang; Qiu, De-Qin; Yu, Bo

    2017-06-01

    This paper is concerned with the fifth-order modified Korteweg-de Vries (fmKdV) equation. It is proved that the fmKdV equation is consistent Riccati expansion (CRE) solvable. Three special form of soliton-cnoidal wave interaction solutions are discussed analytically and shown graphically. Furthermore, based on the consistent tanh expansion (CTE) method, the nonlocal symmetry related to the consistent tanh expansion (CTE) is investigated, we also give the relationship between this kind of nonlocal symmetry and the residual symmetry which can be obtained with the truncated Painlevé method. We further study the spectral function symmetry and derive the Lax pair of the fmKdV equation. The residual symmetry can be localized to the Lie point symmetry of an enlarged system and the corresponding finite transformation group is computed. Supported by National Natural Science Foundation of China under Grant No. 11505090, and Research Award Foundation for Outstanding Young Scientists of Shandong Province under Grant No. BS2015SF009

  7. Symmetry and symmetry breaking in quantum mechanics; Symetrie et brisure de symetrie en mechanique quantique

    Energy Technology Data Exchange (ETDEWEB)

    Chomaz, Philippe [Grand Accelerateur National d`Ions Lourds (GANIL), 14 - Caen (France)

    1998-12-31

    In the world of infinitely small, the world of atoms, nuclei and particles, the quantum mechanics enforces its laws. The discovery of Quanta, this unbelievable castration of the Possible in grains of matter and radiation, in discrete energy levels compels us of thinking the Single to comprehend the Universal. Quantum Numbers, magic Numbers and Numbers sign the wave. The matter is vibration. To describe the music of the world one needs keys, measures, notes, rules and partition: one needs quantum mechanics. The particles reduce themselves not in material points as the scholars of the past centuries thought, but they must be conceived throughout the space, in the accomplishment of shapes of volumes. When Einstein asked himself whether God plays dice, there was no doubt among its contemporaries that if He exists He is a geometer. In a Nature reduced to Geometry, the symmetries assume their role in servicing the Harmony. The symmetries allow ordering the energy levels to make them understandable. They impose there geometrical rules to the matter waves, giving them properties which sometimes astonish us. Hidden symmetries, internal symmetries and newly conceived symmetries have to be adopted subsequently to the observation of some order in this world of Quanta. In turn, the symmetries provide new observables which open new spaces of observation 17 refs., 16 figs.

  8. Lattice-Symmetry-Driven Phase Competition in Vanadium Dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Tselev, Alexander [ORNL; Luk' yanchuk, Prof. Igor A. [University of Picardie Jules Verne, Amiens, France; Ivanov, Ilia N [ORNL; Budai, John D [ORNL; Tischler, Jonathan Zachary [ORNL; Strelcov, Evgheni [Southern Illinois University; Kolmakov, Andrei [Southern Illinois University; Kalinin, Sergei V [ORNL

    2011-01-01

    We performed group-theoretical analysis of the symmetry relationships between lattice structures of R, M1, M2, and T phases of vanadium dioxide in the frameworks of the general Ginzburg-Landau phase transition theory. The analysis leads to a conclusion that the competition between the lower-symmetry phases M1, M2, and T in the metal-insulator transition is pure symmetry driven, since all the three phases correspond to different directions of the same multi-component structural order parameter. Therefore, the lower-symmetry phases can be stabilized in respect to each other by small perturbations such as doping or stress.

  9. Integrable systems and lie symmetries in classical mechanics

    International Nuclear Information System (INIS)

    Sen, T.

    1986-01-01

    The interrelationship between integrability and symmetries in classical mechanics is studied. Two-dimensional time- and velocity-independent potentials form the domain of the study. It is shown that, contrary to folklore, existence of a single finite symmetry does not ensure integrability. A method due to Darboux is used to construct potentials that admit a time-independent invariant. All potentials admitting invariants linear or quadratic in the momentum coordinates are constructed. These are the only integrable potentials which can be expressed as arbitrary functions of certain arguments. A complete construction of potentials admitting higher-order invariants does not seem possible. However, the necessary general forms for potentials that admit a particular invariant of arbitrary order are found. These invariants must be spherically symmetric in the leading terms. Two kinds of symmetries are studied: point Lie symmetries of the Newtonian equations of motion for conservative potentials, and point Noether symmetries of the action functionals obtained from the standard Lagrangians associated with these potentials. All conservative potentials which admit these symmetries are constructed. The class of potentials admitting Noether symmetries is shown to be a subclass of those admitting Lie symmetries

  10. A broken symmetry ontology: Quantum mechanics as a broken symmetry

    International Nuclear Information System (INIS)

    Buschmann, J.E.

    1988-01-01

    The author proposes a new broken symmetry ontology to be used to analyze the quantum domain. This ontology is motivated and grounded in a critical epistemological analysis, and an analysis of the basic role of symmetry in physics. Concurrently, he is led to consider nonheterogeneous systems, whose logical state space contains equivalence relations not associated with the causal relation. This allows him to find a generalized principle of symmetry and a generalized symmetry-conservation formalisms. In particular, he clarifies the role of Noether's theorem in field theory. He shows how a broken symmetry ontology already operates in a description of the weak interactions. Finally, by showing how a broken symmetry ontology operates in the quantum domain, he accounts for the interpretational problem and the essential incompleteness of quantum mechanics. He proposes that the broken symmetry underlying this ontological domain is broken dilation invariance

  11. Dark discrete gauge symmetries

    International Nuclear Information System (INIS)

    Batell, Brian

    2011-01-01

    We investigate scenarios in which dark matter is stabilized by an Abelian Z N discrete gauge symmetry. Models are surveyed according to symmetries and matter content. Multicomponent dark matter arises when N is not prime and Z N contains one or more subgroups. The dark sector interacts with the visible sector through the renormalizable kinetic mixing and Higgs portal operators, and we highlight the basic phenomenology in these scenarios. In particular, multiple species of dark matter can lead to an unconventional nuclear recoil spectrum in direct detection experiments, while the presence of new light states in the dark sector can dramatically affect the decays of the Higgs at the Tevatron and LHC, thus providing a window into the gauge origin of the stability of dark matter.

  12. Strong Electroweak Symmetry Breaking

    CERN Document Server

    Grinstein, Benjamin

    2011-01-01

    Models of spontaneous breaking of electroweak symmetry by a strong interaction do not have fine tuning/hierarchy problem. They are conceptually elegant and use the only mechanism of spontaneous breaking of a gauge symmetry that is known to occur in nature. The simplest model, minimal technicolor with extended technicolor interactions, is appealing because one can calculate by scaling up from QCD. But it is ruled out on many counts: inappropriately low quark and lepton masses (or excessive FCNC), bad electroweak data fits, light scalar and vector states, etc. However, nature may not choose the minimal model and then we are stuck: except possibly through lattice simulations, we are unable to compute and test the models. In the LHC era it therefore makes sense to abandon specific models (of strong EW breaking) and concentrate on generic features that may indicate discovery. The Technicolor Straw Man is not a model but a parametrized search strategy inspired by a remarkable generic feature of walking technicolor,...

  13. Leadership, power and symmetry

    DEFF Research Database (Denmark)

    Spaten, Ole Michael

    2016-01-01

    Research publications concerning managers who coach their own employees are barely visible despite its wide- spread use in enterprises (McCarthy & Milner, 2013; Gregory & Levy, 2011; Crabb, 2011). This article focuses on leadership, power and moments of symmetry in the coaching relationship...... regarding managers coaching their employees and it is asked; what contributes to coaching of high quality when one reflects on the power aspect as being immanent? Fourteen middle managers coached five of their employees, and all members of each party wrote down cues and experiences immediately after each...... session. Thereafter we executed qualitative interviews with both managers and employees. Subsequently, a Thematic Analysis resulted in several themes, including power and moments of symmetry in the coaching relationship. One main conclusion is that the most fruitful coaching was obtained when the coachee...

  14. Asymmetry, Symmetry and Beauty

    Directory of Open Access Journals (Sweden)

    Abbe R. Kopra

    2010-07-01

    Full Text Available Asymmetry and symmetry coexist in natural and human processes.  The vital role of symmetry in art has been well demonstrated. This article highlights the complementary role of asymmetry. Further we show that the interaction of asymmetric action (recursion and symmetric opposition (sinusoidal waves are instrumental in generating creative features (relatively low entropy, temporal complexity, novelty (less recurrence in the data than in randomized copies and complex frequency composition. These features define Bios, a pattern found in musical compositions and in poetry, except for recurrence instead of novelty. Bios is a common pattern in many natural and human processes (quantum processes, the expansion of the universe, gravitational waves, cosmic microwave background radiation, DNA, physiological processes, animal and human populations, and economic time series. The reduction in entropy is significant, as it reveals creativity and contradicts the standard claim of unavoidable decay towards disorder. Artistic creations capture fundamental features of the world.

  15. Precursors and BRST symmetry

    Science.gov (United States)

    de Boer, Jan; Freivogel, Ben; Kabir, Laurens; Lokhande, Sagar F.

    2017-07-01

    In the AdS/CFT correspondence, bulk information appears to be encoded in the CFT in a redundant way. A local bulk field corresponds to many different non-local CFT operators (precursors). We recast this ambiguity in the language of BRST symmetry, and propose that in the large N limit, the difference between two precursors is a BRST exact and ghost-free term. This definition of precursor ambiguities has the advantage that it generalizes to any gauge theory. Using the BRST formalism and working in a simple model with global symmetries, we re-derive a precursor ambiguity appearing in earlier work. Finally, we show within this model that the obtained ambiguity has the right number of parameters to explain the freedom to localize precursors within different spatial regions of the boundary order by order in the large N expansion.

  16. Dynamic generation of light states with discrete symmetries

    Science.gov (United States)

    Cordero, S.; Nahmad-Achar, E.; Castaños, O.; López-Peña, R.

    2018-01-01

    A dynamic procedure is established within the generalized Tavis-Cummings model to generate light states with discrete point symmetries, given by the cyclic group Cn. We consider arbitrary dipolar coupling strengths of the atoms with a one-mode electromagnetic field in a cavity. The method uses mainly the matter-field entanglement properties of the system, which can be extended to any number of three-level atoms. An initial state constituted by the superposition of two states with definite total excitation numbers, |ψ〉 M1,and |ψ〉 M 2, is considered. It can be generated by the proper selection of the time of flight of an atom passing through the cavity. We demonstrate that the resulting Husimi function of the light is invariant under cyclic point transformations of order n =| M1-M2| .

  17. Symmetry breaking and chaos

    International Nuclear Information System (INIS)

    Bunakov, V.E.; Ivanov, I.B.

    1999-01-01

    Connections between the symmetries of Hamiltonian systems in classical and quantum mechanics, on one hand, and their regularity or chaoticity, on the other hand, are considered. The quantum-chaoticity criterion that was proposed previously and which was borrowed from the theory of compound-nucleus resonances is used to analyze the quantum diamagnetic Kepler problem - that is, the motion of a spinless charged particle in a Coulomb and a uniform magnetic field

  18. Symmetry in music

    International Nuclear Information System (INIS)

    Herrero, O F

    2010-01-01

    Music and Physics are very close because of the symmetry that appears in music. A periodic wave is what music really is, and there is a field of Physics devoted to waves researching. The different musical scales are the base of all kind of music. This article tries to show how this musical scales are made, how the consonance is the base of many of them and how symmetric they are.

  19. Symmetry in music

    Energy Technology Data Exchange (ETDEWEB)

    Herrero, O F, E-mail: o.f.herrero@hotmail.co [Conservatorio Superior de Musica ' Eduardo Martinez Torner' Corrada del Obispo s/n 33003 - Oviedo - Asturias (Spain)

    2010-06-01

    Music and Physics are very close because of the symmetry that appears in music. A periodic wave is what music really is, and there is a field of Physics devoted to waves researching. The different musical scales are the base of all kind of music. This article tries to show how this musical scales are made, how the consonance is the base of many of them and how symmetric they are.

  20. Broken SU(3) symmetry at low spin in {sup 178-186}Os

    Energy Technology Data Exchange (ETDEWEB)

    Bouldjedri, A [Department of Physics, Faculty of Science, University of Batna, Avenue Boukhelouf M El Hadi, 05000 Batna (Algeria); Benabderrahmane, M L [Department of Physics, Faculty of Science, University of Constantine, Route Ain El Bey, 25000 Constantine (Algeria)

    2003-07-01

    The test of the SU(3) symmetry near the neutron number N = 104 is extended to the osmium isotopes. It is shown that the available experimental data point towards a slightly broken SU(3) symmetry. This result is analysed theoretically using three mechanisms of symmetry breaking: the effect of SO(6), the consistent Q-formalism and the parameter symmetry of the interacting boson model.

  1. Discrete symmetries in Heterotic/F-theory duality and mirror symmetry

    Science.gov (United States)

    Cvetič, Mirjam; Grassi, Antonella; Poretschkin, Maximilian

    2017-06-01

    We study aspects of Heterotic/F-theory duality for compactifications with Abelian discrete gauge symmetries. We consider F-theory compactifications on genus-one fibered Calabi-Yau manifolds with n-sections, associated with the Tate-Shafarevich group Z_n. Such models are obtained by studying first a specific toric set-up whose associated Heterotic vector bundle has structure group Z_n. By employing a conjectured Heterotic/F-theory mirror symmetry we construct dual geometries of these original toric models, where in the stable degeneration limit we obtain a discrete gauge symmetry of order two and three, for compactifications to six dimensions. We provide explicit constructions of mirror-pairs for symmetric examples with Z_2 and Z_3, in six dimensions. The Heterotic models with symmetric discrete symmetries are related in field theory to a Higgsing of Heterotic models with two symmetric abelian U(1) gauge factors, where due to the Stückelberg mechanism only a diagonal U(1) factor remains massless, and thus after Higgsing only a diagonal discrete symmetry of order n is present in the Heterotic models and detected via Heterotic/F-theory duality. These constructions also provide further evidence for the conjectured mirror symmetry in Heterotic/F-theory at the level of fibrations with torsional sections and those with multi-sections.

  2. A new attempt towards the unification of space-time and internal gauge symmetries

    International Nuclear Information System (INIS)

    Aldaya, V; Sanchez-Sastre, E

    2006-01-01

    The neat formulation that describes the gauge interactions associated with internal symmetries is extended to the case of a simple, yet non-trivial, symmetry group structure which mixes gravity and electromagnetism by associating a gauge symmetry with a central extension of the Poincare group

  3. Boson-fermion symmetries in the W-Pt region

    International Nuclear Information System (INIS)

    Warner, D.D.

    1985-01-01

    The concept of symmetry in the Interacting Boson Model (IBM) description of even-even nuclei has proved to be one of the model's most important elements, because they provide benchmarks in the formulation of a unified description of a broad range of nuclei. The importance of the recently proposed symmetries in odd-even systems can thus be viewed in the same light, and their role in pointing to a simple prescription for the changing collective structure in odd A nuclei throughout a major shell is likely to prove even more essential, given the much greater complexity of the boson-fermion (IBFM) Hamiltonian. The group structure of a boson-fermion system is described by U/sup B/(6) x U/sup F/(m) where m specifies the number of states available to the odd fermion, and thus depends on the single particle space assumed. The ability to construct group chains corresponding to the symmetries SU(5), SU(3) or 0(6) depends on the value of m. Of the structures studied in detail to date, the case of m = 12 is the one with the broadest potential. The fermion is allowed to occupy orbits with j = 1/2, 3/2 and 5/2, so that the assumed single particle space corresponds to the negative parity states available to an odd neutron at the end of the N = 82-126 shell, namely, P/sub 1/2/, p/sub 3/2/ and f/sub 5/2/. The region of interest thus spans the W-Pt nuclei, and since one prerequisite for an odd-A symmetry is the existence of that same symmetry in the neighboring even-even core nucleus, the odd Pt nuclei around A = 196 offer the obvious testing ground for the 0(6) limit of U(6/12). The heavier even-even W nuclei, on the other hand, have the characteristics of an axial rotor, and hence the negative parity structure of the neighboring odd W isotopes offers the possibility to study the validity of the SU(3) limit. Given a definition and understanding of these two limits, the construction of a simple description of the transitional Os nuclei can be considered

  4. The Search for Symmetries in the Genetic Code:

    Science.gov (United States)

    Antoneli, Fernando; Forger, Michael; Hornos, José Eduardo M.

    We give a full classification of the possible schemes for obtaining the distribution of multiplets observed in the standard genetic code by symmetry breaking in the context of finite groups, based on an extended notion of partial symmetry breaking that incorporates the intuitive idea of "freezing" first proposed by Francis Crick, which is given a precise mathematical meaning.

  5. Lepton family symmetries for neutrino masses and mixing

    Indian Academy of Sciences (India)

    I then focus on the tetrahedral group A4 and show how the charged-lepton and neutrino mass matrices may be constrained, followed by a catalog of recent models, with one detailed example. I will also discuss the symmetry S4 with another example and mention briefly the symmetry B4. These examples show how exact ...

  6. The quantum symmetry of rational field theories

    International Nuclear Information System (INIS)

    Fuchs, J.

    1993-12-01

    The quantum symmetry of a rational quantum field theory is a finite-dimensional multi-matrix algebra. Its representation category, which determines the fusion rules and braid group representations of superselection sectors, is a braided monoidal C*-category. Various properties of such algebraic structures are described, and some ideas concerning the classification programme are outlined. (orig.)

  7. Holography with broken Poincaré symmetry

    NARCIS (Netherlands)

    Korovins, J.

    2014-01-01

    This thesis deals with the extensions of the holographic dualities to the situations where part of the Poincaré group has been broken. Such theories are particularly relevant for applications of gauge/gravity dualities to condensed matter systems, which usually exhibit non-relativistic symmetry.

  8. Symmetry in bonding and spectra an introduction

    CERN Document Server

    Douglas, Bodie E

    1985-01-01

    Many courses dealing with the material in this text are called ""Applications of Group Theory."" Emphasizing the central role and primary importance of symmetry in the applications, Symmetry in Bonding and Spectra enables students to handle applications, particularly applications to chemical bonding and spectroscopy. It contains the essential background in vectors and matrices for the applications, along with concise reviews of simple molecular orbital theory, ligand field theory, and treatments of molecular shapes, as well as some quantum mechanics. Solved examples in the text illustra

  9. Fibre bundles. Monopoles and internal symmetries

    International Nuclear Information System (INIS)

    Horvathy, P.A.; Rawnsley, J.H.

    1985-01-01

    Asymptotic monopole configurations are described in fibre-bundle terms. Bundle reduction -the geometric procedure for spontaneous symmetry breaking- is studied in detail: the monopole-bundle is reducible to a given subgroup K of the gauge group if and only if the Higgs charge satisfies a suitable constraint. The Yang-Mills connection reduces if and only if the non-Abelian charge vector belongs to the Lie algebra of K. The problem of ''global color'' can also be formulated in these terms. Our theory allows us to determine which subgroups K are internal symmetries of a given field configuration

  10. Continuous symmetry from Euclid to Klein

    CERN Document Server

    Barker, William

    2007-01-01

    The fundamental idea of geometry is that of symmetry. With that principle as the starting point, Barker and Howe begin an insightful and rewarding study of Euclidean geometry. The primary focus of the book is on transformations of the plane. The transformational point of view provides both a path for deeper understanding of traditional synthetic geometry and tools for providing proofs that spring from a consistent point of view. As a result, proofs become more comprehensible, as techniques can be used and reused in similar settings. The approach to the material is very concrete, with complete

  11. Conformal field theory with gauge symmetry

    CERN Document Server

    Ueno, Kenji

    2008-01-01

    This book presents a systematic approach to conformal field theory with gauge symmetry from the point of view of complex algebraic geometry. After presenting the basic facts of the theory of compact Riemann surfaces and the representation theory of affine Lie algebras in Chapters 1 and 2, conformal blocks for pointed Riemann surfaces with coordinates are constructed in Chapter 3. In Chapter 4 the sheaf of conformal blocks associated to a family of pointed Riemann surfaces with coordinates is constructed, and in Chapter 5 it is shown that this sheaf supports a projective flat connection-one of

  12. Broken Reflection Symmetry

    Science.gov (United States)

    Rugari, Steven Louis

    1992-01-01

    We have carried out a search for broken reflection symmetry in the exotic nucleus ^{114 }Xe. Evidence for broken reflection symmetry has been previously observed in the actinide region, most notably Ra-Th nuclei, and more recently in the neutron rich nuclei ^{144}Ba, ^{146}Ce, and ^{146,148}Nd. This evidence has been discussed in terms of two conceptually different theoretical frameworks, namely alpha clustering and octupole deformation. The alpha clustering model makes global predictions of the relative strengths of enhanced electric dipole (E1) transitions characteristic of broken reflection symmetry, and predicts a dependence on isospin divided by nuclear mass (N-Z) ^2/A^2 of the reduced transition probability, B(E1), where A is the nuclear mass number and N and Z are, respectively, the neutron and proton number. The nuclei studied previously have approximately the same value of (N-Z)^2/A ^2 between 0.033 and 0.05. In ^ {114}Xe this parameter is much different, (N-Z)^2/A^2 =.0028, allowing for a test of the prediction. On the other hand, the octupole model description is less straightforward. Two terms contributing to the calculation of reduced transition strengths are based on the collective liquid drop model of nuclei and have a global dependence on A^2 Z^2. A third term, however, depends explicitly on the shell model description of the valence nucleons and can be large enough to remove this global dependence. The nucleus ^{114}Xe was produced in the heavy ion fusion evaporation reaction ^{60}Ni(^ {58}Ni,2p2n)^{114 }Xe in two separate measurements at Daresbury Laboratory and at Yale University. The nucleus was identified by means of a recoil mass spectrometer in the first reaction and by detection of evaporated neutrons in the second. Gamma ray spectra were collected in coincidence with these triggers using similar gamma detector setups. Information on the angular distributions of the gamma rays was collected for at least three separate angles in each

  13. Gauge symmetries, topology, and quantisation

    International Nuclear Information System (INIS)

    Balachandran, A.P.

    1994-01-01

    The following two loosely connected sets of topics are reviewed in these lecture notes: (1) Gauge invariance, its treatment in field theories and its implications for internal symmetries and edge states such as those in the quantum Hall effect. (2) Quantisation on multiply connected spaces and a topological proof the spin-statistics theorem which avoids quantum field theory and relativity. Under (1), after explaining the meaning of gauge invariance and the theory of constraints, we discuss boundary conditions on gauge transformations and the definition of internal symmetries in gauge field theories. We then show how the edge states in the quantum Hall effect can be derived from the Chern-Simons action using the preceding ideas. Under (2), after explaining the significance of fibre bundles for quantum physics, we review quantisation on multiply connected spaces in detail, explaining also mathematical ideas such as those of the universal covering space and the fundamental group. These ideas are then used to prove the aforementioned topological spin-statistics theorem

  14. Exact Group Invariant Solutions and Conservation Laws of the Complex Modified Korteweg-de Vries Equation

    Science.gov (United States)

    Johnpillai, Andrew G.; Kara, Abdul H.; Biswas, Anjan

    2013-09-01

    We study the scalar complex modified Korteweg-de Vries (cmKdV) equation by analyzing a system of partial differential equations (PDEs) from the Lie symmetry point of view. These systems of PDEs are obtained by decomposing the underlying cmKdV equation into real and imaginary components. We derive the Lie point symmetry generators of the system of PDEs and classify them to get the optimal system of one-dimensional subalgebras of the Lie symmetry algebra of the system of PDEs. These subalgebras are then used to construct a number of symmetry reductions and exact group invariant solutions to the system of PDEs. Finally, using the Lie symmetry approach, a couple of new conservation laws are constructed. Subsequently, respective conserved quantities from their respective conserved densities are computed.

  15. Symmetry breaking in occupation number based slave-particle methods

    Science.gov (United States)

    Georgescu, Alexandru B.; Ismail-Beigi, Sohrab

    2017-10-01

    We describe a theoretical approach to finding spontaneously symmetry-broken electronic phases due to strong electronic interactions when using recently developed slave-particle (slave-boson) approaches based on occupation numbers. We describe why, to date, spontaneous symmetry breaking has proven difficult to achieve in such approaches. We then provide a total energy based approach for introducing auxiliary symmetry-breaking fields into the solution of the slave-particle problem that leads to lowered total energies for symmetry-broken phases. We point out that not all slave-particle approaches yield energy lowering: the slave-particle model being used must explicitly describe the degrees of freedom that break symmetry. Finally, our total energy approach permits us to greatly simplify the formalism used to achieve a self-consistent solution between spinon and slave modes while increasing the numerical stability and greatly speeding up the calculations.

  16. Band warping, band non-parabolicity, and Dirac points in electronic and lattice structures

    Science.gov (United States)

    Resca, Lorenzo; Mecholsky, Nicholas A.; Pegg, Ian L.

    2017-10-01

    We illustrate at a fundamental level the physical and mathematical origins of band warping and band non-parabolicity in electronic and vibrational structures. We point out a robust presence of pairs of topologically induced Dirac points in a primitive-rectangular lattice using a p-type tight-binding approximation. We analyze two-dimensional primitive-rectangular and square Bravais lattices with implications that are expected to generalize to more complex structures. Band warping is shown to arise at the onset of a singular transition to a crystal lattice with a larger symmetry group, which allows the possibility of irreducible representations of higher dimensions, hence band degeneracy, at special symmetry points in reciprocal space. Band warping is incompatible with a multi-dimensional Taylor series expansion, whereas band non-parabolicities are associated with multi-dimensional Taylor series expansions to all orders. Still band non-parabolicities may merge into band warping at the onset of a larger symmetry group. Remarkably, while still maintaining a clear connection with that merging, band non-parabolicities may produce pairs of conical intersections at relatively low-symmetry points. Apparently, such conical intersections are robustly maintained by global topology requirements, rather than any local symmetry protection. For two p-type tight-binding bands, we find such pairs of conical intersections drifting along the edges of restricted Brillouin zones of primitive-rectangular Bravais lattices as lattice constants vary relatively to each other, until these conical intersections merge into degenerate warped bands at high-symmetry points at the onset of a square lattice. The conical intersections that we found appear to have similar topological characteristics as Dirac points extensively studied in graphene and other topological insulators, even though our conical intersections have none of the symmetry complexity and protection afforded by the latter more

  17. Randomized Controlled Trial of Acupuncture for Women with Fibromyalgia: Group Acupuncture with Traditional Chinese Medicine Diagnosis-Based Point Selection.

    Science.gov (United States)

    Mist, Scott D; Jones, Kim Dupree

    2018-02-13

    Group acupuncture is a growing and cost-effective method for delivering acupuncture in the United States and is the practice model in China. However, group acupuncture has not been tested in a research setting. To test the treatment effect of group acupuncture vs group education in persons with fibromyalgia. Random allocation two-group study with repeated measures. Group clinic in an academic health center in Portland, Oregon. Women with confirmed diagnosis of fibromyalgia (American College of Radiology 1990 criteria) and moderate to severe pain levels. Twenty treatments of a manualized acupuncture treatment based on Traditional Chinese Medicine diagnosis or group education over 10 weeks (both 900 minutes total). Weekly Revised Fibromyalgia Impact Questionnaire (FIQR) and Global Fatigue Index at baseline, five weeks, and 10 weeks and a four-week follow-up were assessed. Thirty women were recruited, with 78% reporting symptoms for longer than 10 years. The mean attendance was 810 minutes for acupuncture and 861 minutes for education. FIQR total, FIQR pain, and Global Fatigue Index all had clinically and statistically significant improvement in the group receiving acupuncture at end of treatment and four weeks post-treatment but not in participants receiving group education between groups. Compared with education, group acupuncture improved global symptom impact, pain, and fatigue. Furthermore, it was a safe and well-tolerated treatment option, improving a broader proportion of patients than current pharmaceutical options.

  18. Scalar-flat Kaehler metrics with conformal Bianchi V symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Dunajski, Maciej [Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA (United Kingdom); Plansangkate, Prim, E-mail: M.Dunajski@damtp.cam.ac.uk, E-mail: plansang@CRM.UMontreal.ca [Centre de Recherches Mathematiques (CRM), Universite de Montreal, CP 6128, Montreal (Quebec) H3C 3J7 (Canada)

    2011-06-21

    We provide an affirmative answer to a question posed by Tod (1995, Twistor Theory (New York: Dekker)), and construct all four-dimensional Kaehler metrics with vanishing scalar curvature which are invariant under the conformal action of the Bianchi V group. The construction is based on the combination of twistor theory and the isomonodromic problem with two double poles. The resulting metrics are non-diagonal in the left-invariant basis and are explicitly given in terms of Bessel functions and their integrals. We also make a connection with the LeBrun ansatz, and characterize the associated solutions of the SU({infinity}) Toda equation by the existence a non-abelian two-dimensional group of point symmetries.

  19. Symmetries leading to inflation

    International Nuclear Information System (INIS)

    Aguirregabiria, Juan M.; Lazkoz, Ruth; Chimento, Luis P.; Jakubi, Alejandro S.

    2003-01-01

    We present here the general transformation that leaves unchanged the form of the field equations for perfect fluid Friedmann-Robertson-Walker and Bianchi type V cosmologies. The symmetries found can be used as algorithms for generating new cosmological models from existing ones. A particular case of the general transformation is used to illustrate the crucial role played by the number of scalar fields in the occurrence of inflation. Related to this, we also study the existence and stability of Bianchi type V power law solutions

  20. PREFACE: Symmetries and Integrability of Difference Equations

    Science.gov (United States)

    Doliwa, Adam; Korhonen, Risto; Lafortune, Stéphane

    2007-10-01

    The notion of integrability was first introduced in the 19th century in the context of classical mechanics with the definition of Liouville integrability for Hamiltonian flows. Since then, several notions of integrability have been introduced for partial and ordinary differential equations. Closely related to integrability theory is the symmetry analysis of nonlinear evolution equations. Symmetry analysis takes advantage of the Lie group structure of a given equation to study its properties. Together, integrability theory and symmetry analysis provide the main method by which nonlinear evolution equations can be solved explicitly. Difference equations (DE), like differential equations, are important in numerous fields of science and have a wide variety of applications in such areas as mathematical physics, computer visualization, numerical analysis, mathematical biology, economics, combinatorics, and quantum field theory. It is thus crucial to develop tools to study and solve DEs. While the theory of symmetry and integrability for differential equations is now largely well-established, this is not yet the case for discrete equations. Although over recent years there has been significant progress in the development of a complete analytic theory of difference equations, further tools are still needed to fully understand, for instance, the symmetries, asymptotics and the singularity structure of difference equations. The series of SIDE meetings on Symmetries and Integrability of Difference Equations started in 1994. Its goal is to provide a platform for an international and interdisciplinary communication for researchers working in areas associated with integrable discrete systems, such as classical and quantum physics, computer science and numerical analysis, mathematical biology and economics, discrete geometry and combinatorics, theory of special functions, etc. The previous SIDE meetings took place in Estérel near Montréal, Canada (1994), at the University of

  1. Extensions of automorphisms and gauge symmetries

    International Nuclear Information System (INIS)

    Buchholz, D.; Doplicher, S.; Longo, R.; Roberts, J.E.

    1993-01-01

    We characterize the automophisms of a C*-algebra A which extend to automorphisms of the crossed product B of A by a compact group dual. The case where the inclusion A contains or equal to B is equipped with a group of automorphisms commuting with the dual action is also treated. These results are applied to the analysis of broken gauge symmetries in Quantum Field Theory to draw conclusions on the structure of the degenerate vacua on the field algebra. (orig.)

  2. Bootstrap Dynamical Symmetry Breaking

    Directory of Open Access Journals (Sweden)

    Wei-Shu Hou

    2013-01-01

    Full Text Available Despite the emergence of a 125 GeV Higgs-like particle at the LHC, we explore the possibility of dynamical electroweak symmetry breaking by strong Yukawa coupling of very heavy new chiral quarks Q . Taking the 125 GeV object to be a dilaton with suppressed couplings, we note that the Goldstone bosons G exist as longitudinal modes V L of the weak bosons and would couple to Q with Yukawa coupling λ Q . With m Q ≳ 700  GeV from LHC, the strong λ Q ≳ 4 could lead to deeply bound Q Q ¯ states. We postulate that the leading “collapsed state,” the color-singlet (heavy isotriplet, pseudoscalar Q Q ¯ meson π 1 , is G itself, and a gap equation without Higgs is constructed. Dynamical symmetry breaking is affected via strong λ Q , generating m Q while self-consistently justifying treating G as massless in the loop, hence, “bootstrap,” Solving such a gap equation, we find that m Q should be several TeV, or λ Q ≳ 4 π , and would become much heavier if there is a light Higgs boson. For such heavy chiral quarks, we find analogy with the π − N system, by which we conjecture the possible annihilation phenomena of Q Q ¯ → n V L with high multiplicity, the search of which might be aided by Yukawa-bound Q Q ¯ resonances.

  3. In search of symmetry lost

    CERN Multimedia

    Wilczek, Frank

    2004-01-01

    Powerful symmetry principles have guided physicists in their quest for nature's fundamental laws. The successful gauge theory of electroweak interactions postulates a more extensive symmetry for its equations than are manifest in the world (8 pages) Powerful symmetry principles have guided physicists in their quest for nature's fundamental laws. The successful gauge theory of electroweak interactions postulates a more extensive symmetry for its equations than are manifest in the world. The discrepancy is ascribed to a pervasive symmetry-breaking field, which fills all space uniformly, rendering the Universe a sort of exotic superconductor. So far, the evidence for these bold ideas is indirect. But soon the theory will undergo a critical test depending on whether the quanta of this symmetry-breaking field, the so-called Higgs particles, are produced at the Large Hadron Collider (due to begin operation in 2007).

  4. Evidence for partial dynamical symmetries in atomic nuclei.

    Science.gov (United States)

    Casten, R F; Cakirli, R B; Blaum, K; Couture, A

    2014-09-12

    Symmetries in nature offer very simple descriptions of complex systems. Partial Dynamical Symmetries (PDS) can considerably broaden their relevance. To present the first extensive test of a PDS for nuclei, we compare an SU(3) PDS to gamma to ground band B(E2) values for 47 deformed nuclei. The parameter-free PDS is found to be quite successful, but with characteristic discrepancies, suggesting that symmetry remnants are more pervasive than heretofore realized. Furthermore, the SU(3) PDS gives new insights into collective models (e.g., interacting boson approximation). If these reproduce the PDS, they reflect finite size effects, while differences from the PDS point to SU(3) configuration mixing.

  5. Fluctuations and symmetry energy in nuclear fragmentation dynamics.

    Science.gov (United States)

    Colonna, M

    2013-01-25

    Within a dynamical description of nuclear fragmentation, based on the liquid-gas phase transition scenario, we explore the relation between neutron-proton density fluctuations and nuclear symmetry energy. We show that, along the fragmentation path, isovector fluctuations follow the evolution of the local density and approach an equilibrium value connected to the local symmetry energy. Higher-density regions are characterized by smaller average asymmetry and narrower isotopic distributions. This dynamical analysis points out that fragment final state isospin fluctuations can probe the symmetry energy of the density domains from which fragments originate.

  6. Neutrino masses and family symmetry

    International Nuclear Information System (INIS)

    Grinstein, B.; Preskill, J.; Wise, M.B.

    1985-01-01

    Neutrino masses in the 100 eV-1 MeV range are permitted if there is a spontaneously broken global family symmetry that allows the heavy neutrinos to decay by Goldstone boson emission with a cosmologically acceptable lifetime. The family symmetry may be either abelian or nonabelian; we present models illustrating both possibilities. If the family symmetry is nonabelian, then the decay tau -> μ + Goldstone boson or tau -> e + Goldstone may have an observable rate. (orig.)

  7. Exact dynamical and partial symmetries

    Energy Technology Data Exchange (ETDEWEB)

    Leviatan, A, E-mail: ami@phys.huji.ac.il [Racah Institute of Physics, The Hebrew University, Jerusalem 91904 (Israel)

    2011-03-01

    We discuss a hierarchy of broken symmetries with special emphasis on partial dynamical symmetries (PDS). The latter correspond to a situation in which a non-invariant Hamiltonian accommodates a subset of solvable eigenstates with good symmetry, while other eigenstates are mixed. We present an algorithm for constructing Hamiltonians with this property and demonstrate the relevance of the PDS notion to nuclear spectroscopy, to quantum phase transitions and to mixed systems with coexisting regularity and chaos.

  8. Exact dynamical and partial symmetries

    International Nuclear Information System (INIS)

    Leviatan, A

    2011-01-01

    We discuss a hierarchy of broken symmetries with special emphasis on partial dynamical symmetries (PDS). The latter correspond to a situation in which a non-invariant Hamiltonian accommodates a subset of solvable eigenstates with good symmetry, while other eigenstates are mixed. We present an algorithm for constructing Hamiltonians with this property and demonstrate the relevance of the PDS notion to nuclear spectroscopy, to quantum phase transitions and to mixed systems with coexisting regularity and chaos.

  9. The conservation of orbital symmetry

    CERN Document Server

    Woodward, R B

    2013-01-01

    The Conservation of Orbital Symmetry examines the principle of conservation of orbital symmetry and its use. The central content of the principle was that reactions occur readily when there is congruence between orbital symmetry characteristics of reactants and products, and only with difficulty when that congruence does not obtain-or to put it more succinctly, orbital symmetry is conserved in concerted reaction. This principle is expected to endure, whatever the language in which it may be couched, or whatever greater precision may be developed in its application and extension. The book ope

  10. Leptogenesis and residual CP symmetry

    International Nuclear Information System (INIS)

    Chen, Peng; Ding, Gui-Jun; King, Stephen F.

    2016-01-01

    We discuss flavour dependent leptogenesis in the framework of lepton flavour models based on discrete flavour and CP symmetries applied to the type-I seesaw model. Working in the flavour basis, we analyse the case of two general residual CP symmetries in the neutrino sector, which corresponds to all possible semi-direct models based on a preserved Z 2 in the neutrino sector, together with a CP symmetry, which constrains the PMNS matrix up to a single free parameter which may be fixed by the reactor angle. We systematically study and classify this case for all possible residual CP symmetries, and show that the R-matrix is tightly constrained up to a single free parameter, with only certain forms being consistent with successful leptogenesis, leading to possible connections between leptogenesis and PMNS parameters. The formalism is completely general in the sense that the two residual CP symmetries could result from any high energy discrete flavour theory which respects any CP symmetry. As a simple example, we apply the formalism to a high energy S 4 flavour symmetry with a generalized CP symmetry, broken to two residual CP symmetries in the neutrino sector, recovering familiar results for PMNS predictions, together with new results for flavour dependent leptogenesis.

  11. Quarks, baryons and chiral symmetry

    CERN Document Server

    Hosaka, Atsushi

    2001-01-01

    This book describes baryon models constructed from quarks, mesons and chiral symmetry. The role of chiral symmetry and of quark model structure with SU(6) spin-flavor symmetry are discussed in detail, starting from a pedagogic introduction. Emphasis is placed on symmetry aspects of the theories. As an application, the chiral bag model is studied for nucleon structure, where important methods of theoretical physics, mostly related to the semiclassical approach for a system of strong interactions, are demonstrated. The text is more practical than formal; tools and ideas are explained in detail w

  12. Constraints and hidden symmetry in two-dimensional gravity

    Energy Technology Data Exchange (ETDEWEB)

    Barcelos-Neto, J. (Instituto de Fisica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro 21945-970 (Brazil))

    1994-01-15

    We study the hidden symmetry of Polyakov two-dimensional gravity by means of first-class constraints. These are obtained from the combination of Fourier mode expansions of the usual (second-class) constraints of the theory. We show that, more than the usual SL(2,[ital R]), there is a hidden Virasoro symmetry in the theory. The results of the above analysis are also confirmed from the point of view of a geometrical symplectic treatment.

  13. Sample size and classification error for Bayesian change-point models with unlabelled sub-groups and incomplete follow-up.

    Science.gov (United States)

    White, Simon R; Muniz-Terrera, Graciela; Matthews, Fiona E

    2018-05-01

    Many medical (and ecological) processes involve the change of shape, whereby one trajectory changes into another trajectory at a specific time point. There has been little investigation into the study design needed to investigate these models. We consider the class of fixed effect change-point models with an underlying shape comprised two joined linear segments, also known as broken-stick models. We extend this model to include two sub-groups with different trajectories at the change-point, a change and no change class, and also include a missingness model to account for individuals with incomplete follow-up. Through a simulation study, we consider the relationship of sample size to the estimates of the underlying shape, the existence of a change-point, and the classification-error of sub-group labels. We use a Bayesian framework to account for the missing labels, and the analysis of each simulation is performed using standard Markov chain Monte Carlo techniques. Our simulation study is inspired by cognitive decline as measured by the Mini-Mental State Examination, where our extended model is appropriate due to the commonly observed mixture of individuals within studies who do or do not exhibit accelerated decline. We find that even for studies of modest size ( n = 500, with 50 individuals observed past the change-point) in the fixed effect setting, a change-point can be detected and reliably estimated across a range of observation-errors.

  14. Black Hole Entropy from Bondi-Metzner-Sachs Symmetry at the Horizon.

    Science.gov (United States)

    Carlip, S

    2018-03-09

    Near the horizon, the obvious symmetries of a black hole spacetime-the horizon-preserving diffeomorphisms-are enhanced to a larger symmetry group with a three-dimensional Bondi-Metzner-Sachs algebra. Using dimensional reduction and covariant phase space techniques, I investigate this augmented symmetry and show that it is strong enough to determine the black hole entropy in any dimension.

  15. Black Hole Entropy from Bondi-Metzner-Sachs Symmetry at the Horizon

    Science.gov (United States)

    Carlip, S.

    2018-03-01

    Near the horizon, the obvious symmetries of a black hole spacetime—the horizon-preserving diffeomorphisms—are enhanced to a larger symmetry group with a three-dimensional Bondi-Metzner-Sachs algebra. Using dimensional reduction and covariant phase space techniques, I investigate this augmented symmetry and show that it is strong enough to determine the black hole entropy in any dimension.

  16. Symmetry structures and conservation laws of Petrov III and Papapetrou metrics

    Science.gov (United States)

    Bokhari, A. H.; Zaman, F. D.; Narain, R.; Kara, A. H.

    2013-07-01

    In this paper, Noether symmetries of some spacetime metrics are studied. Considering invariance of the action integral under one parameter Lie group of transformations, it is shown that a large class of Noether symmetries is found. In particular, it is shown that the isometries form a sub-Lie algebra of Noether symmetries.

  17. Symmetries in heavy nuclei and the proton-neutron interaction

    Energy Technology Data Exchange (ETDEWEB)

    Casten, R.F.

    1986-01-01

    The Interacting Boson Approximation (IBA) nuclear structure model can be expressed in terms of the U(6) group, and thereby leads to three dynamical symmetries (or group chains) corresponding to different nuclear coupling schemes and geometrical shapes. The status of the empirical evidence for these three symmetries is reviewed, along with brief comments on the possible existence of supersymmetries in nuclei. The relationships between these symmetries, the nuclear phase transitional regions linking them, and the residual proton-neutron interaction are discussed in terms of a particularly simple scheme for parameterizing the effects of that interaction. 34 refs., 15 figs.

  18. Symmetry-Breaking in a Rate Model for a Biped Locomotion Central Pattern Generator

    Directory of Open Access Journals (Sweden)

    Ian Stewart

    2014-01-01

    Full Text Available The timing patterns of animal gaits are produced by a network of spinal neurons called a Central Pattern Generator (CPG. Pinto and Golubitsky studied a four-node CPG for biped dynamics in which each leg is associated with one flexor node and one extensor node, with Ζ2 x Ζ2 symmetry. They used symmetric bifurcation theory to predict the existence of four primary gaits and seven secondary gaits. We use methods from symmetric bifurcation theory to investigate local bifurcation, both steady-state and Hopf, for their network architecture in a rate model. Rate models incorporate parameters corresponding to the strengths of connections in the CPG: positive for excitatory connections and negative for inhibitory ones. The three-dimensional space of connection strengths is partitioned into regions that correspond to the first local bifurcation from a fully symmetric equilibrium. The partition is polyhedral, and its symmetry group is that of a tetrahedron. It comprises two concentric tetrahedra, subdivided by various symmetry planes. The tetrahedral symmetry arises from the structure of the eigenvalues of the connection matrix, which is involved in, but not equal to, the Jacobian of the rate model at bifurcation points. Some of the results apply to rate equations on more general networks.

  19. High interocular corneal symmetry in average simulated keratometry, central corneal thickness, and posterior elevation.

    Science.gov (United States)

    Myrowitz, Elliott H; Kouzis, Anthony C; O'Brien, Terrence P

    2005-05-01

    The purpose of this study was to assess interocular corneal symmetry in average simulated keratometry, corneal thickness, and posterior corneal elevation. This retrospective analysis included data from scanning slit topography (Orbscan II; Bausch and Lomb, Rochester, NY) on 242 eyes from 121 consecutive patients undergoing standard evaluation for consideration of elective laser vision correction. The symmetry between the right and left eye in average simulated keratometry, minimum central corneal thickness, and posterior corneal elevation was assessed by comparative data analysis. Simulated keratometry ranged from 39.9 to 48.6 D. The interocular difference in average simulated keratometry was 0.47 D (standard deviation [SD] 0.43). The interocular Pearson correlation coefficient for average simulated keratometry was 0.90 (p central corneal thickness was 0.95 (p symmetry in all these parameters was very high in this group of consecutive patients. Asymmetry of these interocular parameters may warrant repeat clinical testing for accuracy and may predict corneal abnormalities. Normative data on posterior cornea elevation is presented. This study points out potentially clinically important high interocular corneal symmetry data in simulated keratometry, corneal thickness, and posterior corneal elevation.

  20. Criticality of O (N ) symmetric models in the presence of discrete gauge symmetries

    Science.gov (United States)

    Pelissetto, Andrea; Tripodo, Antonio; Vicari, Ettore

    2018-01-01

    We investigate the critical properties of the three-dimensional antiferromagnetic RPN -1 model, which is characterized by a global O (N ) symmetry and a discrete Z2 gauge symmetry. We perform a field-theoretical analysis using the Landau-Ginzburg-Wilson (LGW) approach and a numerical Monte Carlo study. The LGW field-theoretical results are obtained by high-order perturbative analyses of the renormalization-group flow of the most general Φ4 theory with the same global symmetry as the model, assuming a gauge-invariant order-parameter field. For N =4 no stable fixed point is found, implying that any transition must necessarily be of first order. This is contradicted by the numerical results that provide strong evidence for a continuous transition. This suggests that gauge modes are not always irrelevant, as assumed by the LGW approach, but they may play an important role to determine the actual critical dynamics at the phase transition of O (N ) symmetric models with a discrete Z2 gauge symmetry.

  1. Symmetry Reduction of Two-Dimensional Damped Kuramoto—Sivashinsky Equation

    Science.gov (United States)

    Mehdi, Nadjafikhah; Fatemeh, Ahangari

    2011-08-01

    In this paper, the problem of determining the largest possible set of symmetries for an important nonlinear dynamical system: the two-dimensional damped Kuramoto—Sivashinsky ((2D) DKS) equation is studied. By applying the basic Lie symmetry method for the (2D) DKS equation, the classical Lie point symmetry operators are obtained. Also, the optimal system of one-dimensional subalgebras of the equation is constructed. The Lie invariants as well as similarity reduced equations corresponding to infinitesimal symmetries are obtained. The nonclassical symmetries of the (2D) DKS equation are also investigated.

  2. Holography without translational symmetry

    CERN Document Server

    Vegh, David

    2013-01-01

    We propose massive gravity as a holographic framework for describing a class of strongly interacting quantum field theories with broken translational symmetry. Bulk gravitons are assumed to have a Lorentz-breaking mass term as a substitute for spatial inhomogeneities. This breaks momentum-conservation in the boundary field theory. At finite chemical potential, the gravity duals are charged black holes in asymptotically anti-de Sitter spacetime. The conductivity in these systems generally exhibits a Drude peak that approaches a delta function in the massless gravity limit. Furthermore, the optical conductivity shows an emergent scaling law: $|\\sigma(\\omega)| \\approx {A \\over \\omega^{\\alpha}} + B$. This result is consistent with that found earlier by Horowitz, Santos, and Tong who introduced an explicit inhomogeneous lattice into the system.

  3. Neutrino mass and mixing with discrete symmetry

    Science.gov (United States)

    King, Stephen F.; Luhn, Christoph

    2013-05-01

    This is a review paper about neutrino mass and mixing and flavour model building strategies based on discrete family symmetry. After a pedagogical introduction and overview of the whole of neutrino physics, we focus on the PMNS mixing matrix and the latest global fits following the Daya Bay and RENO experiments which measure the reactor angle. We then describe the simple bimaximal, tri-bimaximal and golden ratio patterns of lepton mixing and the deviations required for a non-zero reactor angle, with solar or atmospheric mixing sum rules resulting from charged lepton corrections or residual trimaximal mixing. The different types of see-saw mechanism are then reviewed as well as the sequential dominance mechanism. We then give a mini-review of finite group theory, which may be used as a discrete family symmetry broken by flavons either completely, or with different subgroups preserved in the neutrino and charged lepton sectors. These two approaches are then reviewed in detail in separate chapters including mechanisms for flavon vacuum alignment and different model building strategies that have been proposed to generate the reactor angle. We then briefly review grand unified theories (GUTs) and how they may be combined with discrete family symmetry to describe all quark and lepton masses and mixing. Finally, we discuss three model examples which combine an SU(5) GUT with the discrete family symmetries A4, S4 and Δ(96).

  4. Baryon magnetic moments: Symmetries and relations

    Energy Technology Data Exchange (ETDEWEB)

    Parreno, Assumpta [University of Barcelona; Savage, Martin [Univ. of Washington, Seattle, WA (United States); Tiburzi, Brian [City College of New York, NY (United States); City Univ. (CUNY), NY (United States); Wilhelm, Jonas [Justus-Liebig-Universitat Giessen, Giessen, Germany; Univ. of Washington, Seattle, WA (United States); Chang, Emmanuel [Univ. of Washington, Seattle, WA (United States); Detmold, William [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Orginos, Kostas [College of William and Mary, Williamsburg, VA (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2018-04-01

    Magnetic moments of the octet baryons are computed using lattice QCD in background magnetic fields, including the first treatment of the magnetically coupled Σ0- Λ system. Although the computations are performed for relatively large values of the up and down quark masses, we gain new insight into the symmetries and relations between magnetic moments by working at a three-flavor mass-symmetric point. While the spinflavor symmetry in the large Nc limit of QCD is shared by the naïve constituent quark model, we find instances where quark model predictions are considerably favored over those emerging in the large Nc limit. We suggest further calculations that would shed light on the curious patterns of baryon magnetic moments.

  5. Nonlinear symmetry realizations and the generalized CP sup(n-1) model

    International Nuclear Information System (INIS)

    Santos, T.A.

    1982-01-01

    The genralized CP sup(n-1) model having U(p) as Gauge group in the two-dimension Euclidean space in the several existing formulations is presented. Such a model is described as a nonlinear symmetry realization which becames linear when restricted to a determined sub-groups treating therefore of fields which have values in the quocient space G/H. Classical instanton and meron solutions for this model are presented and the existence of a mechanism to generate a family of non auto-dual solutions with finite action, taking as starting point the instanton solutions, is demonstrated. (L.C.) [pt

  6. Hartree-Fock symmetry breaking around conical intersections

    Science.gov (United States)

    Jake, Lena C.; Henderson, Thomas M.; Scuseria, Gustavo E.

    2018-01-01

    We study the behavior of Hartree-Fock (HF) solutions in the vicinity of conical intersections. These are here understood as regions of a molecular potential energy surface characterized by degenerate or nearly degenerate eigenfunctions with identical quantum numbers (point group, spin, and electron numbers). Accidental degeneracies between states with different quantum numbers are known to induce symmetry breaking in HF. The most common closed-shell restricted HF instability is related to singlet-triplet spin degeneracies that lead to collinear unrestricted HF solutions. Adding geometric frustration to the mix usually results in noncollinear generalized HF (GHF) solutions, identified by orbitals that are linear combinations of up and down spins. Near conical intersections, we observe the appearance of coplanar GHF solutions that break all symmetries, including complex conjugation and time-reversal, which do not carry good quantum numbers. We discuss several prototypical examples taken from the conical intersection literature. Additionally, we utilize a recently introduced magnetization diagnostic to characterize these solutions, as well as a solution of a Jahn-Teller active geometry of H8+2.

  7. Characterization of Partial Intrinsic Symmetries

    NARCIS (Netherlands)

    Shehu, Aurela; Brunton, Alan; Wuhrer, Stefanie; Wand, Michael

    2014-01-01

    We present a mathematical framework and algorithm for characterizing and extracting partial intrinsic symmetries of surfaces, which is a fundamental building block for many modern geometry processing algorithms. Our goal is to compute all “significant” symmetry information of the shape, which we

  8. Symmetry preservation during radiation damage

    International Nuclear Information System (INIS)

    Bhat, S.V.; Abdel-Gawad, M.M.H.

    1991-01-01

    An examination of radiation-damage processes consequent to high-energy irradiation in certain ammonium salts studied using ESR of free radicals together with the structural information available from neutron diffraction studies shows that, other factors being equal/nearly equal, symmetry-related bonds are preserved in preference to those unrelated to one another by any symmetry. (author). 23 refs., 3 tabs

  9. Singlets of fermionic gauge symmetries

    NARCIS (Netherlands)

    Bergshoeff, E.A.; Kallosh, R.E.; Rahmanov, M.A.

    1989-01-01

    We investigate under which conditions singlets of fermionic gauge symmetries which are "square roots of gravity" can exist. Their existence is non-trivial because there are no fields neutral in gravity. We tabulate several examples of singlets of global and local supersymmetry and κ-symmetry and

  10. Symmetry guide to ferroaxial transitions

    Czech Academy of Sciences Publication Activity Database

    Hlinka, Jiří; Přívratská, J.; Ondrejkovič, Petr; Janovec, Václav

    2016-01-01

    Roč. 116, č. 17 (2016), 1-6, č. článku 177602. ISSN 0031-9007 R&D Projects: GA ČR GA15-04121S Institutional support: RVO:68378271 Keywords : symmetry * symmetry breaking * ferroaxial Transitions * property tensors * Aizu species Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 8.462, year: 2016

  11. Relationships between melting point and boiling point of organic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Yalkowsky, S.H.; Krzyzaniak, J.F.; Myrdal, P.B. (Univ. of Arizona, Tucson, AZ (United States). College of Pharmacy)

    1994-07-01

    Relationships between melting point and boiling point are shown to be dependent upon the molecular symmetry number and a modified count of the total number of atoms in the molecule. Using the above relationships, the boiling and melting points of nearly 1,000 non-hydrogen-bonding organic compounds have been correlated. The correlations for boiling point and melting point have root mean square errors of 28 and 36 C, respectively.

  12. Domain wall network as QCD vacuum: confinement, chiral symmetry, hadronization

    Directory of Open Access Journals (Sweden)

    Nedelko Sergei N.

    2017-01-01

    Full Text Available An approach to QCD vacuum as a medium describable in terms of statistical ensemble of almost everywhere homogeneous Abelian (anti-self-dual gluon fields is reviewed. These fields play the role of the confining medium for color charged fields as well as underline the mechanism of realization of chiral SUL(Nf × SUR(Nf and UA(1 symmetries. Hadronization formalism based on this ensemble leads to manifestly defined quantum effective meson action. Strong, electromagnetic and weak interactions of mesons are represented in the action in terms of nonlocal n-point interaction vertices given by the quark-gluon loops averaged over the background ensemble. Systematic results for the mass spectrum and decay constants of radially excited light, heavy-light mesons and heavy quarkonia are presented. Relationship of this approach to the results of functional renormalization group and Dyson-Schwinger equations, and the picture of harmonic confinement is briefly outlined.

  13. Symmetries in geology and geophysics.

    Science.gov (United States)

    Turcotte, D L; Newman, W I

    1996-12-10

    Symmetries have played an important role in a variety of problems in geology and geophysics. A large fraction of studies in mineralogy are devoted to the symmetry properties of crystals. In this paper, however, the emphasis will be on scale-invariant (fractal) symmetries. The earth's topography is an example of both statistically self-similar and self-affine fractals. Landforms are also associated with drainage networks, which are statistical fractal trees. A universal feature of drainage networks and other growth networks is side branching. Deterministic space-filling networks with side-branching symmetries are illustrated. It is shown that naturally occurring drainage networks have symmetries similar to diffusion-limited aggregation clusters.

  14. Axions from chiral family symmetry

    International Nuclear Information System (INIS)

    Chang, D.; Pal, P.B.; Maryland Univ., College Park; Senjanovic, G.

    1985-01-01

    We investigate the possibility that family symmetry, Gsub(F), is spontaneously broken chiral global symmetry. We classify the interesting cases when family symmetry can result in an automatic Peccei-Quinn symmetry U(1)sub(PQ) and thus provide a solution to the strong CP problem. The result disfavors having two or four families. For more than four families, U(1)sub(PQ) is in general automatic. In the case of three families, a unique Higgs sector allows U(1)sub(PQ) in the simplest case of Gsub(F)=[SU(3)] 3 . Cosmological consideration also puts strong constraint on the number of families. For Gsub(F)=[SU(N)] 3 cosmology singles out the three-family (N=3) case as a unique solution if there are three light neutrinos. Possible implication of decoupling theorem as applied to family symmetry breaking is also discussed. (orig.)

  15. Shape analysis with subspace symmetries

    KAUST Repository

    Berner, Alexander

    2011-04-01

    We address the problem of partial symmetry detection, i.e., the identification of building blocks a complex shape is composed of. Previous techniques identify parts that relate to each other by simple rigid mappings, similarity transforms, or, more recently, intrinsic isometries. Our approach generalizes the notion of partial symmetries to more general deformations. We introduce subspace symmetries whereby we characterize similarity by requiring the set of symmetric parts to form a low dimensional shape space. We present an algorithm to discover subspace symmetries based on detecting linearly correlated correspondences among graphs of invariant features. We evaluate our technique on various data sets. We show that for models with pronounced surface features, subspace symmetries can be found fully automatically. For complicated cases, a small amount of user input is used to resolve ambiguities. Our technique computes dense correspondences that can subsequently be used in various applications, such as model repair and denoising. © 2010 The Author(s).

  16. Spatially-protected Topology and Group Cohomology in Band Insulators

    Science.gov (United States)

    Alexandradinata, A.

    This thesis investigates band topologies which rely fundamentally on spatial symmetries. A basic geometric property that distinguishes spatial symmetry regards their transformation of the spatial origin. Point groups consist of spatial transformations that preserve the spatial origin, while un-split extensions of the point groups by spatial translations are referred to as nonsymmorphic space groups. The first part of the thesis addresses topological phases with discretely-robust surface properties: we introduce theories for the Cnv point groups, as well as certain nonsymmorphic groups that involve glide reflections. These band insulators admit a powerful characterization through the geometry of quasimomentum space; parallel transport in this space is represented by the Wilson loop. The non-symmorphic topology we study is naturally described by a further extension of the nonsymmorphic space group by quasimomentum translations (the Wilson loop), thus placing real and quasimomentum space on equal footing -- here, we introduce the language of group cohomology into the theory of band insulators. The second part of the thesis addresses topological phases without surface properties -- their only known physical consequences are discrete signatures in parallel transport. We provide two such case studies with spatial-inversion and discrete-rotational symmetries respectively. One lesson learned here regards the choice of parameter loops in which we carry out transport -- the loop must be chosen to exploit the symmetry that protects the topology. While straight loops are popular for their connection with the geometric theory of polarization, we show that bent loops also have utility in topological band theory.

  17. Quantum Numbers and the Eigenfunction Approach to Obtain Symmetry Adapted Functions for Discrete Symmetries

    Directory of Open Access Journals (Sweden)

    Renato Lemus

    2012-11-01

    Full Text Available The eigenfunction approach used for discrete symmetries is deduced from the concept of quantum numbers. We show that the irreducible representations (irreps associated with the eigenfunctions are indeed a shorthand notation for the set of eigenvalues of the class operators (character table. The need of a canonical chain of groups to establish a complete set of commuting operators is emphasized. This analysis allows us to establish in natural form the connection between the quantum numbers and the eigenfunction method proposed by J.Q. Chen to obtain symmetry adapted functions. We then proceed to present a friendly version of the eigenfunction method to project functions.

  18. Topological methods for variational problems with symmetries

    CERN Document Server

    Bartsch, Thomas

    1993-01-01

    Symmetry has a strong impact on the number and shape of solutions to variational problems. This has been observed, for instance, in the search for periodic solutions of Hamiltonian systems or of the nonlinear wave equation; when one is interested in elliptic equations on symmetric domains or in the corresponding semiflows; and when one is looking for "special" solutions of these problems. This book is concerned with Lusternik-Schnirelmann theory and Morse-Conley theory for group invariant functionals. These topological methods are developed in detail with new calculations of the equivariant Lusternik-Schnirelmann category and versions of the Borsuk-Ulam theorem for very general classes of symmetry groups. The Morse-Conley theory is applied to bifurcation problems, in particular to the bifurcation of steady states and hetero-clinic orbits of O(3)-symmetric flows; and to the existence of periodic solutions nearequilibria of symmetric Hamiltonian systems. Some familiarity with the usualminimax theory and basic a...

  19. Hospital-acquired urinary tract infection point prevalence in Turkey: Differences in risk factors among patient groups

    Science.gov (United States)

    2013-01-01

    Background The aim of this study was to determine the point prevalence of nosocomial urinary tract infections (UTIs) and to investigate risk factors for pathogen type (E. coli vs. others) and extended-spectrum beta-lactamase (ESBL) positivity among nosocomial UTI patients. Methods A questionnaire consisting of 44 questions on demographic data and risk factors of UTI cases was sent to 51 tertiary care hospitals. Univariate and multivariate analyses were conducted. Results The overall prevalence of UTI was 1.82% (483/26534). The prevalence of UTI was higher in intensive care units (ICUs) with 6.77% versus 1.45% outside ICUs. Hospitals of the Ministry of Health (compared to university hospitals), hospitals in less developed provinces and hospitals with bed capacity urinary catheter were more likely to have received immunosuppressive therapy, current corticosteroid use, renal transplantation and uterine prolapsus and less likely to have another infection outside the urinary tract, as compared to catheterized patients. Among the 422 culture-positive patients, the most common pathogen was E. coli (45.5%). The risk factors increasing the likelihood of E. coli in urine culture were being female, history of urinary tract operation, no use of antibiotics in the preceding three months and infection outside the urinary tract. There were 247 patients with E. coli or Klebsiella spp. positive in culture. Among these, 61% (n=151) were ESBL- positive. Among patients having E. coli/Klebsiella positive in culture, antibiotic use in the preceding three months and history of urinary tract operation were the independent risk factors significantly increasing the risk of ESBL. Conclusions The reasons underlying the high prevalence of nosocomial UTIs, and a better understanding of the risk factors might lead to improved control of these infections. PMID:24188193

  20. Probing symmetry and symmetry breaking in resonant soft-x-ray fluorescence spectra of molecules

    Energy Technology Data Exchange (ETDEWEB)

    Glans, P.; Gunnelin, K.; Guo, J. [Uppsala Univ. (Sweden)] [and others

    1997-04-01

    Conventional non-resonant soft X-ray emission brings about information about electronic structure through its symmetry and polarization selectivity, the character of which is governed by simple dipole rules. For centro-symmetric molecules with the emitting atom at the inversion center these rules lead to selective emission through the required parity change. For the more common classes of molecules which have lower symmetry or for systems with degenerate core orbitals (delocalized over identical sites), it is merely the local symmetry selectivity that provides a probe of the local atomic orbital contribution to the molecular orbital. For instance, in X-ray spectra of first row species the intensities essentially map the p-density at each particular atomic site, and, in a molecular orbital picture, the contribution of the local p-type atomic orbitals in the LCAO description of the molecular orbitals. The situation is different for resonant X-ray fluorescence spectra. Here strict parity and symmetry selectivity gives rise to a strong frequency dependence for all molecules with an element of symmetry. In addition to symmetry selectivity the strong frequency dependence of resonant X-ray emission is caused by the interplay between the shape of a narrow X-ray excitation energy function and the lifetime and vibrational broadenings of the resonantly excited core states. This interplay leads to various observable effects, such as linear dispersion, resonance narrowing and emission line (Stokes) doubling. Also from the point of view of polarization selectivity, the resonantly excited X-ray spectra are much more informative than the corresponding non-resonant spectra. Examples are presented for nitrogen, oxygen, and carbon dioxide molecules.

  1. Cut-off points to identify sarcopenia according to European Working Group on Sarcopenia in Older People (EWGSOP) definition.

    Science.gov (United States)

    Bahat, Gulistan; Tufan, Asli; Tufan, Fatih; Kilic, Cihan; Akpinar, Timur Selçuk; Kose, Murat; Erten, Nilgun; Karan, Mehmet Akif; Cruz-Jentoft, Alfonso J

    2016-12-01

    The reported prevalence of sarcopenia ranges widely depending on its definition criterion. European Working Group on Sarcopenia in Older People (EWGSOP) developed a practical clinical definition and consensus diagnostic criteria. This definition recommends using normative data of the study population rather than other reference populations. We aimed to define the reference cut-off values for muscle mass, muscle strength and calf circumference in Turkey in order to improve general applicability of EWGSOP criteria. Healthy young adults between 18 and 39 years of age with no known chronic disease or chronic drug usage were included in our study to serve as reference population for assessing muscle mass. Community-dwelling older outpatients were prospectively recruited from the geriatrics outpatient clinics of a university hospital for assessing hand grip strength and calf circumference. Body composition was assessed by bioimpedance analysis. Muscle strength was assessed measuring hand grip strength with a Jamar hand dynamometer. The cut-off thresholds for muscle mass were defined as the mean-2SD of the values of the young reference study population; for grip strength were calculated from ROC analyses using cut-off values that predicted gait speed young reference group included a total of 301 participants (187 male, 114 female; mean age: 26.5 ± 4.6 years). The cut-off thresholds for skeletal muscle mass indexes were 9.2 kg/m 2 and 7.4 kg/m 2 in males and females, respectively. The older community dwelling group included 406 subjects (123 male, 283 female, mean age: 76.6 ± 6.7 years). The cut-off thresholds for hand grip strength were 32 kg and 22 kg for males and females. The cut-off threshold for calf circumference was 33 cm for both males and females. The cut-off thresholds for muscle mass, grip strength and calf circumference were somewhat higher but comparable with other reference populations. Further worldwide studies from different nations and

  2. 't Hooft anomaly matching for discrete symmetries

    International Nuclear Information System (INIS)

    Csaki, C.; Murayama, Hitoshi; Lawrence Berkeley National Lab., CA

    1998-05-01

    The authors show how to extend the 't Hooft anomaly matching conditions to discrete symmetries. They check these discrete anomally matching conditions on several proposed low-energy spectra of certain strongly interacting gauge theories. The excluded examples include the proposed chirally symmetric vacuum of pure N = 1 supersymmetric yang-Mills theories, certain non-supersymmetric confining theories and some self-dual N = 1 supersymmetric theories based on exceptional groups

  3. Gravitational consequences of a broken Lorentz symmetry

    International Nuclear Information System (INIS)

    Tartaglia, A.

    1987-01-01

    The paper shows that breaking the Lorentz symmetry in the tangent space generates, at least in two examples, short-range gravitational repulsion. This can avoid the singularities usually present in the general relativistic theory of gravity. Different possible breaking mechanisms are presented, finally remarking that the non-Lorentz-preserving co-ordinate transformations in the tangent space do indeed form a Lie group whose Lie algebra is neither simple nor semi-simple

  4. Group-invariant finite Fourier transforms

    International Nuclear Information System (INIS)

    Shenefelt, M.H.

    1988-01-01

    The computation of the finite Fourier transform of functions is one of the most used computations in crystallography. Since the Fourier transform involved in 3-dimensional, the size of the computation becomes very large even for relatively few sample points along each edge. In this thesis, there is a family of algorithms that reduce the computation of Fourier transform of functions respecting the symmetries. Some properties of these algorithms are: (1) The algorithms make full use of the group of symmetries of a crystal. (2) The algorithms can be factored and combined according to the prime factorization of the number of points in the sample space. (3) The algorithms are organized into a family using the group structure of the crystallographic groups to make iterative procedures possible

  5. Symmetries as by-products of conserved quantities

    Science.gov (United States)

    Romero-Maltrana, Diego

    2015-11-01

    There is general consensus among physicists in considering symmetries as a source of conserved quantities, a conclusion allegedly supported by Emmy Noether's theorems. Recently it has been pointed out that no arrow of explanation can be extracted from Noether's work, and there are also criticisms against the priority of particular symmetries over specific conserved quantities under Noether's ideas, but there are no general arguments against the aforementioned consensus, nor proposals promoting an explanation that leads from conserved quantities to symmetries. In this paper a general argument is built which favours conserved quantities over symmetries inasmuch as the presence of the former seems to allow (i.e. it seems to be a sufficient condition leading to) symmetrical descriptions.

  6. Partial dynamical symmetries and shape coexistence in nuclei

    Science.gov (United States)

    Leviatan, A.; Gavrielov, N.

    2017-11-01

    We present a symmetry-based approach for shape coexistence in nuclei, founded on the concept of partial dynamical symmetry (PDS). The latter corresponds to the situation where only selected states (or bands of states) of the coexisting configurations preserve the symmetry while other states are mixed. We construct explicitly critical-point Hamiltonians with two or three PDSs of the types U(5), SU(3), \\overline{{SU}(3)} and SO(6), appropriate to double or triple coexistence of spherical, prolate, oblate and γ-soft deformed shapes, respectively. In each case, we analyze the topology of the energy surface with multiple minima and corresponding normal modes. Characteristic features and symmetry attributes of the quantum spectra and wave functions are discussed. Analytic expressions for quadrupole moments and E2 rates involving the remaining solvable states are derived and isomeric states are identified by means of selection rules.

  7. Spin, mass, and symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Peskin, M.E. [Stanford Univ., CA (United States)

    1994-12-01

    When the strong interactions were a mystery, spin seemed to be just a complication on top of an already puzzling set of phenomena. But now that particle physicists have understood the strong, weak, and electromagnetic interactions, to be gauge theories, with matter built of quarks and leptons, it is recognized that the special properties of spin 1/2 and spin 1 particles have taken central role in the understanding of Nature. The lectures in this summer school will be devoted to the use of spin in unravelling detailed questions about the fundamental interactions. Thus, why not begin by posing a deeper question: Why is there spin? More precisely, why do the basic pointlike constituents of Nature carry intrinsic nonzero quanta of angular momentum? Though the authos has found no definite answer to this question, the pursuit of an answer has led through a wonderful tangle of speculations on the deep structure of Nature. Is spin constructed or is it fundamental? Is it the requirement of symmetry? In the furthest flights taken, it seems that space-time itself is too restrictive a notion, and that this must be generalized in order to gain a full appreciation of spin. In any case, there is no doubt that spin must play a central role in unlocking the mysteries of fundamental physics.

  8. Gravitation and Gauge Symmetries

    CERN Document Server

    Stewart, J

    2002-01-01

    The purpose of this book (I quote verbatim from the back cover) is to 'shed light upon the intrinsic structure of gravity and the principle of gauge invariance, which may lead to a consistent unified field theory', a very laudable aim. The content divides fairly clearly into four sections (and origins). After a brief introduction, chapters 2-6 review the 'Structure of gravity as a theory based on spacetime gauge symmetries'. This is fairly straightforward material, apparently based on a one-semester graduate course taught at the University of Belgrade for about two decades, and, by implication, this is a reasonably accurate description of its level and assumed knowledge. There follow two chapters of new material entitled 'Gravity in flat spacetime' and 'Nonlinear effects in gravity'. The final three chapters, entitled 'Supersymmetry and supergravity', 'Kaluza-Klein theory' and 'String theory' have been used for the basis of a one-semester graduate course on the unification of fundamental interactions. The boo...

  9. Segmentation Using Symmetry Deviation

    DEFF Research Database (Denmark)

    Hollensen, Christian; Højgaard, L.; Specht, L.

    2011-01-01

    and evaluate the method. The method uses deformable registration on computed tomography(CT) to find anatomical symmetry deviations of Head & Neck squamous cell carcinoma and combining it with positron emission tomography (PET) images. The method allows the use anatomical and symmetrical information of CT scans...... segmentations on manual contours was evaluated using concordance index and sensitivity for the hypopharyngeal patients. The resulting concordance index and sensitivity was compared with the result of using a threshold of 3 SUV using a paired t-test. Results: The anatomical and symmetrical atlas was constructed...... and sensitivity of respectively 0.43±0.15 and 0.56±0.18 was acquired. It was compared to the concordance index of segmentation using absolute threshold of 3 SUV giving respectively 0.41±0.16 and 0.51±0.19 for concordance index and sensitivity yielding p-values of 0.33 and 0.01 for a paired t-test respectively....

  10. Spin, mass, and symmetry

    International Nuclear Information System (INIS)

    Peskin, M.E.

    1994-01-01

    When the strong interactions were a mystery, spin seemed to be just a complication on top of an already puzzling set of phenomena. But now that particle physicists have understood the strong, weak, and electromagnetic interactions, to be gauge theories, with matter built of quarks and leptons, it is recognized that the special properties of spin 1/2 and spin 1 particles have taken central role in the understanding of Nature. The lectures in this summer school will be devoted to the use of spin in unravelling detailed questions about the fundamental interactions. Thus, why not begin by posing a deeper question: Why is there spin? More precisely, why do the basic pointlike constituents of Nature carry intrinsic nonzero quanta of angular momentum? Though the authos has found no definite answer to this question, the pursuit of an answer has led through a wonderful tangle of speculations on the deep structure of Nature. Is spin constructed or is it fundamental? Is it the requirement of symmetry? In the furthest flights taken, it seems that space-time itself is too restrictive a notion, and that this must be generalized in order to gain a full appreciation of spin. In any case, there is no doubt that spin must play a central role in unlocking the mysteries of fundamental physics

  11. Symmetries in nuclear structure

    CERN Document Server

    Allaart, K; Dieperink, A

    1983-01-01

    The 1982 summer school on nuclear physics, organized by the Nuclear Physics Division of the Netherlands' Physical Society, was the fifth in a series that started in 1963. The number of students attending has always been about one hundred, coming from about thirty countries. The theme of this year's school was symmetry in nuclear physics. This book covers the material presented by the enthusi­ astic speakers, who were invited to lecture on this subject. We think they have succeeded in presenting us with clear and thorough introductory talks at graduate or higher level. The time schedule of the school and the location allowed the participants to make many informal contacts during many social activities, ranging from billiards to surf board sailing. We hope and expect that the combination of a relaxed atmosphere during part of the time and hard work during most of the time, has furthered the interest in, and understanding of, nuclear physics. The organization of the summer school was made possible by substantia...

  12. Quark diquark symmetry breaking

    International Nuclear Information System (INIS)

    Souza, M.M. de

    1980-01-01

    Assuming the baryons are made of quark-diquark pairs, the wave functions for the 126 allowed ground states are written. The quark creation and annihilations operators are generalized to describe the quark-diquark structure in terms of a parameter σ. Assuming that all quark-quark interactions are mediated by gluons transforming like an octet of vector mesons, the effective Hamiltonian and the baryon masses as constraint equations for the elements of the mass matrix is written. The symmetry is the SU(6) sub(quark)x SU(21) sub(diquark) broken by quark-quark interactions respectively invariant under U(6), U(2) sub(spin), U(3) and also interactions transforming like the eighth and the third components of SU(3). In the limit of no quark-diquark structure (σ = 0), the ground state masses is titted to within 1% of the experimental data, except for the Δ(1232), where the error is almost 2%. Expanding the decuplet mass equations in terms of σ and keeping terms only up to the second order, this error is reduced to 67%. (Author) [pt

  13. Decoherence and discrete symmetries in deformed relativistic kinematics

    Science.gov (United States)

    Arzano, Michele

    2018-01-01

    Models of deformed Poincaré symmetries based on group valued momenta have long been studied as effective modifications of relativistic kinematics possibly capturing quantum gravity effects. In this contribution we show how they naturally lead to a generalized quantum time evolution of the type proposed to model fundamental decoherence for quantum systems in the presence of an evaporating black hole. The same structures which determine such generalized evolution also lead to a modification of the action of discrete symmetries and of the CPT operator. These features can in principle be used to put phenomenological constraints on models of deformed relativistic symmetries using precision measurements of neutral kaons.

  14. The development of a collapsing method for the mixed group and point cross sections and its application on multi-dimensional deep penetration calculations

    International Nuclear Information System (INIS)

    Bor-Jing Chang; Yen-Wan H. Liu

    1992-01-01

    The HYBRID, or mixed group and point, method was developed to solve the neutron transport equation deterministically using detailed treatment at cross section minima for deep penetration calculations. Its application so far is limited to one-dimensional calculations due to the enormous computing time involved in multi-dimensional calculations. In this article, a collapsing method is developed for the mixed group and point cross section sets to provide a more direct and practical way of using the HYBRID method in the multi-dimensional calculations. A testing problem is run. The method is then applied to the calculation of a deep penetration benchmark experiment. It is observed that half of the window effect is smeared in the collapsing treatment, but it still provide a better cross section set than the VITAMIN-C cross sections for the deep penetrating calculations

  15. Nonlinear electromagnetic fields and symmetries

    Science.gov (United States)

    Barjašić, Irena; Gulin, Luka; Smolić, Ivica

    2017-06-01

    We extend the classical results on the symmetry inheritance of the canonical electromagnetic fields, described by the Maxwell's Lagrangian, to a much wider class of models, which include those of the Born-Infeld, power Maxwell and the Euler-Heisenberg type. Symmetry inheriting fields allow the introduction of electromagnetic scalar potentials and these are proven to be constant on the Killing horizons. Finally, using the relations obtained along the analysis, we generalize and simplify the recent proof for the symmetry inheritance of the 3-dimensional case, as well as give the first constraint for the higher dimensional electromagnetic fields.

  16. Conformal Symmetry as a Template for QCD

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, S

    2004-08-04

    Conformal symmetry is broken in physical QCD; nevertheless, one can use conformal symmetry as a template, systematically correcting for its nonzero {beta} function as well as higher-twist effects. For example, commensurate scale relations which relate QCD observables to each other, such as the generalized Crewther relation, have no renormalization scale or scheme ambiguity and retain a convergent perturbative structure which reflects the underlying conformal symmetry of the classical theory. The ''conformal correspondence principle'' also dictates the form of the expansion basis for hadronic distribution amplitudes. The AdS/CFT correspondence connecting superstring theory to superconformal gauge theory has important implications for hadron phenomenology in the conformal limit, including an all-orders demonstration of counting rules for hard exclusive processes as well as determining essential aspects of hadronic light-front wavefunctions. Theoretical and phenomenological evidence is now accumulating that QCD couplings based on physical observables such as {tau} decay become constant at small virtuality; i.e., effective charges develop an infrared fixed point in contradiction to the usual assumption of singular growth in the infrared. The near-constant behavior of effective couplings also suggests that QCD can be approximated as a conformal theory even at relatively small momentum transfer. The importance of using an analytic effective charge such as the pinch scheme for unifying the electroweak and strong couplings and forces is also emphasized.

  17. T{sub 13} flavor symmetry and decaying dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Kajiyama, Yuji, E-mail: yuji.kajiyama@kbfi.e [National Institute of Chemical Physics and Biophysics, Ravala 10, Tallinn 10143 (Estonia); Department of Physics, Niigata University, Niigata 950-2128 (Japan); Okada, Hiroshi, E-mail: HOkada@Bue.edu.e [Centre for Theoretical Physics, British University in Egypt, El Sherouk City, Postal No. 11837, P.O. Box 43 (Egypt)

    2011-07-11

    We study a new flavor symmetric model with non-Abelian discrete symmetry T{sub 13}. The T{sub 13} group is isomorphic to Z{sub 13} x Z{sub 3}, and it is the minimal group having two complex triplets in the irreducible representations. We show that the T{sub 13} symmetry can derive lepton masses and mixings consistently. Moreover, if we assume a gauge-singlet fermionic decaying dark matter, its decay operators are also constrained by the T{sub 13} symmetry so that only dimension six operators of leptonic decay are allowed. We find that the cosmic-ray anomalies reported by PAMELA and Fermi-LAT are well explained by decaying dark matter controlled by the T{sub 13} flavor symmetry.

  18. Bilateral coordination and gait symmetry after body-weight supported treadmill training for persons with chronic stroke.

    Science.gov (United States)

    Combs, Stephanie A; Dugan, Eric L; Ozimek, Elicia N; Curtis, Amy B

    2013-04-01

    Locomotor interventions are commonly assessed using functional outcomes, but these outcomes provide limited information about changes toward recovery or compensatory mechanisms. The study purposes were to examine changes in gait symmetry and bilateral coordination following body-weight supported treadmill training in individuals with chronic hemiparesis due to stroke and to compare findings to participants without disability. Nineteen participants with stroke (>6 months) who ambulated between 0.4 and 0.8 m/s and 22 participants without disability were enrolled in this repeated-measures study. The stroke group completed 24 intervention sessions over 8 weeks with 20 minutes of walking/session. The non-disabled group served as a comparison for describing changes in symmetry and coordination. Bilateral 3-dimensional motion analysis and gait speed were assessed across 3 time points (pre-test, immediate post-test, and 6-month retention). Continuous relative phase was used to evaluate bilateral coordination (thigh-thigh, shank-shank, foot-foot) and gait symmetry was assessed with spatiotemporal ratios (step length, swing time, stance time). Significant improvements in continuous relative phase (shank-shank and foot-foot couplings) were found at post-test and retention for the stroke group. Significant differences in spatiotemporal symmetry ratios were not found over time. Compared to the non-disabled group, changes in bilateral coordination moved in the direction of normal recovery. Most measures of continuous relative phase were more responsive to change after training than the spatiotemporal ratios. After body-weight supported treadmill training, the stroke group made improvements toward recovery of normal bilateral coordination. Bilateral coordination and gait symmetry measures may assess different aspects of gait. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. Emergent physics: Fermi point scenario

    OpenAIRE

    Volovik, G. E.

    2008-01-01

    The Fermi-point scenario of emergent gravity has the following consequences: gravity emerges together with fermionic and bosonic matter; emergent fermionic matter consists of massless Weyl fermions; emergent bosonic matter consists of gauge fields; Lorentz symmetry persists well above the Planck energy; space-time is naturally 4-dimensional; Universe is naturally flat; cosmological constant is naturally small or zero; underlying physics is based on discrete symmetries; `quantum gravity' canno...

  20. Strings, Branes and Symmetries

    International Nuclear Information System (INIS)

    Westerberg, A.

    1997-01-01

    Recent dramatic progress in the understanding of the non-perturbative structure of superstring theory shows that extended objects of various kinds, collectively referred to as p-branes, are an integral part of the theory. In this thesis, comprising an introductory text and seven appended research papers, we study various aspects of p-branes with relevance for superstring theory. The first part of the introductory text is a brief review of string theory focussing on the role of p-branes. In particular, we consider the so-called D-branes which currently are attracting a considerable amount of attention. The purpose of this part is mainly to put into context the results of paper 4, 5 and 6 concerning action functionals describing the low-energy dynamics of D-branes. The discussion of perturbative string theory given in this part of the introduction is also intended to provide some background to paper 2 which contains an application of the Reggeon-sewing approach to the construction of string vertices. The second part covers a rather different subject, namely higher-dimensional loop algebras and their cohomology, with the aim of facilitating the reading of papers 1, 3 and 7. The relation to p-branes is to be found in paper 1 where we introduce a certain higher-dimensional generalization of the loop algebra and discuss its potential applicability as a symmetry algebra for p-branes. Papers 3 and 7 are mathematically oriented out-growths of this paper addressing the issue of realizing algebras of this kind, known in physics as current algebras, in terms of pseudo differential operators (PSDOs). The main result of paper 3 is a proof of the equivalence between certain Lie-algebra cocycles on the space of second-quantizable PSDOs

  1. Global aspects of symmetries in sigma models with torsion

    International Nuclear Information System (INIS)

    Papadopoulos, G.; Imperial Coll. of Science and Technology, London

    1994-07-01

    It is shown that non-trivial topological sectors can prevent the quantum mechanical implementation of the symmetries of the classical field equations of sigma models with torsion. The associated anomaly is computed, and it is shown that it depends on the homotopy class of the topological sector of the theory and the group action on the sigma model manifold that generates the symmetries of the classical field equations. (orig.)

  2. Symmetry-preserving difference schemes for some heat transfer equations

    Science.gov (United States)

    Bakirova, M. I.; Dorodnitsyn, V. A.; Kozlov, R. V.

    1997-12-01

    Lie group analysis of differential equations is a generally recognized method, which provides invariant solutions, integrability, conservation laws etc. In this paper we present three characteristic examples of the construction of invariant difference equations and meshes, where the original continuous symmetries are preserved in discrete models. Conservation of symmetries in difference modelling helps to retain qualitative properties of the differential equations in their difference counterparts.

  3. Symmetries of Particle Physics: Space-time and Local Gauge ...

    Indian Academy of Sciences (India)

    The round cross-section of the rod has full rotational symmetry about the axis of the rod (this is called an U(l) symmetry group). This 'internal' symme- try makes it hard to see whether or not energy is stored in the rod without allowing it to untwist itself. To help you, let me draw guidelines along the rod to make the twist visible.

  4. Analysis of chiral symmetry breaking mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Xin-Heng, Guo [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Tao, Huang [Academia Sinica, Beijing, BJ (China). Inst. of High Energy Physics; Chuang, Wang

    1997-07-01

    The renormalization group invariant quark condensate {mu} is determinate both from the consistent equation for quark condensate in the chiral limit and from the Schwinger-Dyson (SD) equation improved by the intermediate range QCD force singular like {delta} (q) which is associated with the gluon condensate. The solutions of {mu} in these two equations are consistent. We also obtain the critical strong coupling constant {alpha}c above which chiral symmetry breaks in two approaches. The nonperturbative kernel of the SD equation makes {alpha}c smaller and {mu} bigger. An intuitive picture of the condensation above {alpha}c is discussed. In addition, with the help of the Slavnov-Taylor-Ward (STW) identity we derive the equations for the nonperturbative quark propagator from SD equation in the presence of the intermediate-range force is also responsible for dynamical chiral symmetry breaking. (author) 32 refs., 2 figs.

  5. Tensegrity structures form, stability, and symmetry

    CERN Document Server

    Zhang, Jing Yao

    2015-01-01

    To facilitate a deeper understanding of tensegrity structures, this book focuses on their two key design problems: self-equilibrium analysis and stability investigation. In particular, high symmetry properties of the structures are extensively utilized. Conditions for self-equilibrium as well as super-stability of tensegrity structures are presented in detail. An analytical method and an efficient numerical method are given for self-equilibrium analysis of tensegrity structures: the analytical method deals with symmetric structures and the numerical method guarantees super-stability. Utilizing group representation theory, the text further provides analytical super-stability conditions for the structures that are of dihedral as well as tetrahedral symmetry. This book not only serves as a reference for engineers and scientists but is also a useful source for upper-level undergraduate and graduate students. Keeping this objective in mind, the presentation of the book is self-contained and detailed, with an abund...

  6. Symmetry Reductions, Exact Solutions and Conservation Laws of Asymmetric Nizhnik-Novikov-Veselov Equation

    International Nuclear Information System (INIS)

    Wang Ling; Dong Zhongzhou; Liu Xiqiang

    2008-01-01

    By applying a direct symmetry method, we get the symmetry of the asymmetric Nizhnik-Novikov-Veselov equation (ANNV). Taking the special case, we have a finite-dimensional symmetry. By using the equivalent vector of the symmetry, we construct an eight-dimensional symmetry algebra and get the optimal system of group-invariant solutions. To every case of the optimal system, we reduce the ANNV equation and obtain some solutions to the reduced equations. Furthermore, we find some new explicit solutions of the ANNV equation. At last, we give the conservation laws of the ANNV equation.

  7. Symmetry and Phase Transitions in Nuclei

    International Nuclear Information System (INIS)

    Iachello, F.

    2009-01-01

    Phase transitions in nuclei have received considerable attention in recent years, especially after the discovery that, contrary to expectations, systems at the critical point of a phase transition display a simple structure. In this talk, quantum phase transitions (QPT), i.e. phase transitions that occur as a function of a coupling constant that appears in the quantum Hamiltonian, H, describing the system, will be reviewed and experimental evidence for their occurrence in nuclei will be presented. The phase transitions discussed in the talk will be shape phase transitions. Different shapes have different symmetries, classified by the dynamic symmetries of the Interacting Boson Model, U(5), SU(3) and SO(6). Very recently, the concept of Quantum Phase Transitions has been extended to Excited State Quantum Phase Transitions (ESQPT). This extension will be discussed and some evidence for incipient ESQPT in nuclei will be presented. Systems at the critical point of a phase transition are called 'critical systems'. Approximate analytic formulas for energy spectra and other properties of 'critical nuclei', in particular for nuclei at the critical point of the second order U(5)-SO(6) transition, called E(5), and along the line of first order U(5)-SU(3) transitions, called X(5), will be presented. Experimental evidence for 'critical nuclei' will be also shown. Finally, the microscopic derivation of shape phase transitions in nuclei within the framework of density functional methods will be briefly discussed.(author)

  8. Symmetries in the Lagrangean formalism

    International Nuclear Information System (INIS)

    Grigore, D.R.

    1987-09-01

    We generalize the analysis of Levy-Leblond for lagrangean systems with symmetry. We prove that this analysis goes through practically unchanged and after that we analyse in detail some examples.(author)

  9. Sterile neutrinos and B-L symmetry

    Science.gov (United States)

    Fileviez Pérez, Pavel; Murgui, Clara

    2018-02-01

    We revisit the relation between the neutrino masses and the spontaneous breaking of the B-L gauge symmetry. We discuss the main scenarios for Dirac and Majorana neutrinos and point out two simple mechanisms for neutrino masses. In this context the neutrino masses can be generated either at tree level or at quantum level and one predicts the existence of very light sterile neutrinos with masses below the eV scale. The predictions for lepton number violating processes such as μ → e and μ → eγ are discussed in detail. The impact from the cosmological constraints on the effective number of relativistic degree of freedom is investigated.

  10. Non-Gaussianity from Broken Symmetries

    CERN Document Server

    Kolb, Edward W; Vallinotto, A; Kolb, Edward W.; Riotto, Antonio; Vallinotto, Alberto

    2006-01-01

    Recently we studied inflation models in which the inflaton potential is characterized by an underlying approximate global symmetry. In the first work we pointed out that in such a model curvature perturbations are generated after the end of the slow-roll phase of inflation. In this work we develop further the observational implications of the model and compute the degree of non-Gaussianity predicted in the scenario. We find that the corresponding nonlinearity parameter, $f_{NL}$, can be as large as 10^2.

  11. Nuclear symmetries at low isospin

    International Nuclear Information System (INIS)

    Juillet, Olivier

    1999-01-01

    With the development of radioactive beams, an area of intense research in nuclear physics concerns the structure of exotic systems with roughly equal numbers of protons and neutrons. These nuclei might in fact develop a proton-neutron superfluidity whose importance compared to pairing correlations between like nucleons is currently investigated. The work presented in this thesis suggests to look at such a competition in an algebraic framework based on a Wigner SU(4) symmetry that combines the pseudo-spin and isospin degrees of freedom. After a detailed review of group theory in quantum mechanics, the validity of the pseudo-SU(4) classification is shown via a direct analysis of realistic shell model states. Its consequences on binding energies and β decay are also studied. Moreover, a simplified boson realisation with zero orbital angular momentum is used to find some physical features of N=Z nuclei such as the condensation of α-like structures or the destruction of isoscalar superfluid correlations by the spin-orbit potential. Finally, another bosonization scheme that includes quadrupole degrees of freedom (IBM-4 model) is tested for the first time by diagonalization of a full Hamiltonian deduced from a realistic shell model interaction. The quality of the results, especially for odd-odd nuclei, allows one to consider this boson approximation as an alternative to standard fermionic approaches for the collective structure of the exotic line N∼Z=28-50. (author) [fr

  12. Symmetry and order parameter dynamics of the human odometer.

    Science.gov (United States)

    Abdolvahab, Mohammad; Carello, Claudia; Pinto, Carla; Turvey, M T; Frank, Till D

    2015-02-01

    Bipedal gaits have been classified on the basis of the group symmetry of the minimal network of identical differential equations (alias cells) required to model them. Primary bipedal gaits (e.g., walk, run) are characterized by dihedral symmetry, whereas secondary bipedal gaits (e.g., gallop-walk, gallop- run) are characterized by a lower, cyclic symmetry. This fact has been used in tests of human odometry (e.g., Turvey et al. in P Roy Soc Lond B Biol 276:4309-4314, 2009, J Exp Psychol Hum Percept Perform 38:1014-1025, 2012). Results suggest that when distance is measured and reported by gaits from the same symmetry class, primary and secondary gaits are comparable. Switching symmetry classes at report compresses (primary to secondary) or inflates (secondary to primary) measured distance, with the compression and inflation equal in magnitude. The present research (a) extends these findings from overground locomotion to treadmill locomotion and (b) assesses a dynamics of sequentially coupled measure and report phases, with relative velocity as an order parameter, or equilibrium state, and difference in symmetry class as an imperfection parameter, or detuning, of those dynamics. The results suggest that the symmetries and dynamics of distance measurement by the human odometer are the same whether the odometer is in motion relative to a stationary ground or stationary relative to a moving ground.

  13. Renormgroup symmetry for solution functionals

    International Nuclear Information System (INIS)

    Shirkov, D.V.; Kovalev, V.F.

    2004-01-01

    The paper contains generalization of the renormgroup algorithm for boundary value problems of mathematical physics and related concept of the renormgroup symmetry, formulated earlier by the authors with reference to models based on differential equations. These algorithm and symmetry are formulated now for models with nonlocal (integral) equations. We discuss in detail and illustrate by examples the applications of the generalized algorithm to models with nonlocal terms which appear as linear functionals of the solution. (author)

  14. Symmetry analysis and conservation laws for a coupled (2 + 1)-dimensional hyperbolic system

    Science.gov (United States)

    Muatjetjeja, Ben; Khalique, Chaudry Masood

    2015-05-01

    This paper aims to perform Lie symmetry analysis and Noether symmetry classification of a coupled (2 + 1)-dimensional hyperbolic system. In the Lie analysis, the principal Lie algebra which is six dimensional extends in thirteen cases. It is further shown that four main cases arise in the Noether classification with respect to the standard Lagrangian. Moreover, conservation laws are established for the cases which admit Noether point symmetries.

  15. Lie Group Analysis of the Photo-Induced Fluorescence of Drosophila Oogenesis with the Asymmetrically Localized Gurken Protein.

    Directory of Open Access Journals (Sweden)

    Jen-Cheng Wang

    Full Text Available Lie group analysis of the photo-induced fluorescence of Drosophila oogenesis with the asymmetrically localized Gurken protein has been performed systematically to assess the roles of ligand-receptor complexes in follicle cells. The (2×2 matrix representations resulting from the polarized tissue spectra were employed to characterize the asymmetrical Gurken distributions. It was found that the fluorescence of the wild-type egg shows the Lie point symmetry X 23 at early stages of oogenesis. However, due to the morphogen regulation by intracellular proteins and extracellular proteins, the fluorescence of the embryogenesis with asymmetrically localized Gurken expansions exhibits specific symmetry features: Lie point symmetry Z 1 and Lie point symmetry X 1. The novel approach developed herein was successfully used to validate that the invariant-theoretical characterizations are consonant with the observed asymmetric fluctuations during early embryological development.

  16. Lie Group Analysis of the Photo-Induced Fluorescence of Drosophila Oogenesis with the Asymmetrically Localized Gurken Protein.

    Science.gov (United States)

    Wang, Jen-Cheng; Wang, Pei-Yu; Chen, Hung-Ing; Wu, Kai-Ling; Pai, Li-Mei; Nee, Tzer-En

    2013-01-01

    Lie group analysis of the photo-induced fluorescence of Drosophila oogenesis with the asymmetrically localized Gurken protein has been performed systematically to assess the roles of ligand-receptor complexes in follicle cells. The (2×2) matrix representations resulting from the polarized tissue spectra were employed to characterize the asymmetrical Gurken distributions. It was found that the fluorescence of the wild-type egg shows the Lie point symmetry X 23 at early stages of oogenesis. However, due to the morphogen regulation by intracellular proteins and extracellular proteins, the fluorescence of the embryogenesis with asymmetrically localized Gurken expansions exhibits specific symmetry features: Lie point symmetry Z 1 and Lie point symmetry X 1. The novel approach developed herein was successfully used to validate that the invariant-theoretical characterizations are consonant with the observed asymmetric fluctuations during early embryological development.

  17. PREFACE: Symmetries in Science XVI

    Science.gov (United States)

    2014-10-01

    This volume of the proceedings ''Symmetries in Science XVI'' is dedicated to the memory of Miguel Lorente and Allan Solomon who both participated several times in these Symposia. We lost not only two great scientists and colleagues, but also two wonderful persons of high esteem whom we will always remember. Dieter Schuch, Michael Ramek There is a German saying ''all good things come in threes'' and ''Symmetries in Science XVI'', convened July 20-26, 2013 at the Mehrerau Monastery, was our third in the sequel of these symposia since taking it over from founder Bruno Gruber who instigated it in 1988 (then in Lochau). Not only the time seemed to have been perfect (one week of beautiful sunshine), but also the medley of participants could hardly have been better. This time, 34 scientists from 16 countries (more than half outside the European Union) came together to report and discuss their latest results in various fields of science, all related to symmetries. The now customary grouping of renowned experts and talented newcomers was very rewarding and stimulating for all. The informal, yet intense, discussions at ''Gasthof Lamm'' occurred (progressively later) each evening till well after midnight and finally till almost daybreak! However, prior to the opening ceremony and during the conference, respectively, we were informed that Miguel Lorente and Allan Solomon had recently passed away. Both attended the SIS Symposia several times and had many friends among present and former participants. Professor Peter Kramer, himself a long-standing participant and whose 80th birthday commemoration prevented him from attending SIS XVI, kindly agreed to write the obituary for Miguel Lorente. Professors Richard Kerner and Carol Penson (both also former attendees) penned, at very short notice, the tribute to Allan Solomon. The obituaries are included in these Proceedings and further tributes have been posted to our conference website. In 28 lectures and an evening poster

  18. Study of temperature distribution of fuel, clad and coolant in the VVER-1000 reactor core during group-10 control rod scram by using diffusion and point kinetic methods

    International Nuclear Information System (INIS)

    Rahgoshay, M.; Rahmani, Y.

    2007-01-01

    In this paper, through the application of two different methods (point kinetic and diffusion), the temperature distribution of fuel, clad and coolant has been studied and calculated during group-10 control rod scram, in the Bushehr Nuclear Power Plant (Iran) with a VVER-1000 reactor core. In the reactor core of Bushehr NPP, 10 groups of control rods are used of which, group-10 control rods contain the highest amount of injected negative reactivity in terms of quantity as compared to other groups of control rods. In this paper we explain impacts of negative reactivity, caused by a complete or minor scram of group-10 control rods, on thermoneutronic parameters of the VVER-1000 nuclear reactor core. It should be noted that through these calculations and by using the results, we can develop a sound understanding of impacts of this controlling element in optimum control of the reactor core and, on this basis, with careful attention and by gaining access to a reliable simulation (on the basis of results of calculations made in this survey) we can monitor the VVER-1000 reactor core through a smart control system. In continuation, for a more accurate survey and for comparing results of different calculation systems (point kinetic and diffusion), by using COSTANZA-R,Z calculation code (in which neutronic calculations are based on diffusion model) and using WIMS code at different areas and temperatures (for calculation of constant physical coefficients and temperature coefficients needed in COSTANZAR, Z code) for the VVER-1000 reactor core of Bushehr NPP, calculation of temperature distribution of fuel elements and coolant by using diffusion model is made in the course of group-10 control rods scram and afterwards. (author)

  19. Ambiguities and symmetry relations associated with fermionic tensor densities

    International Nuclear Information System (INIS)

    Dallabona, G.; Battistel, O. A.

    2004-01-01

    We consider the consistent evaluation of perturbative (divergent) Green functions associated with fermionic tensor densities and the derivation of symmetry relations for them. We show that, in spite of current algebra methods being not applicable, it is possible to derive symmetry properties analogous to the Ward identities of vector and axial-vector densities. The proposed method, which is applicable to any previously chosen order of perturbative calculation, gives the same results as those of current algebra when such a tool is applicable. By using a very general calculational strategy, concerning the manipulations and calculations involving divergent Feynman integrals, we evaluate the purely fermionic two-point functions containing tensor vertices and derive their symmetry properties. The present investigation is the first step in the study and characterization of possible anomalies involving fermionic tensor densities, particularly in purely fermionic three-point functions

  20. Test of Pseudospin Symmetry in Deformed Nuclei

    OpenAIRE

    Ginocchio, J. N.; Leviatan, A.; Meng, J.; Zhou, Shan-Gui

    2003-01-01

    Pseudospin symmetry is a relativistic symmetry of the Dirac Hamiltonian with scalar and vector mean fields equal and opposite in sign. This symmetry imposes constraints on the Dirac eigenfunctions. We examine extensively the Dirac eigenfunctions of realistic relativistic mean field calculations of deformed nuclei to determine if these eigenfunctions satisfy these pseudospin symmetry constraints.