Right unitarity triangles and tri-bimaximal mixing from discrete symmetries and unification
Energy Technology Data Exchange (ETDEWEB)
Antusch, S., E-mail: antusch@mppmu.mpg.de [Max-Planck-Institut fuer Physik (Werner-Heisenberg-Institut), Foehringer Ring 6, D-80805 Muenchen (Germany); King, Stephen F., E-mail: king@soton.ac.uk [School of Physics and Astronomy, University of Southampton, SO17 1BJ Southampton (United Kingdom); Luhn, Christoph, E-mail: christoph.luhn@soton.ac.uk [School of Physics and Astronomy, University of Southampton, SO17 1BJ Southampton (United Kingdom); Spinrath, M., E-mail: spinrath@sissa.it [SISSA/ISAS and INFN, Via Bonomea 265, I-34136 Trieste (Italy)
2011-09-21
We propose new classes of models which predict both tri-bimaximal lepton mixing and a right-angled Cabibbo-Kobayashi-Maskawa (CKM) unitarity triangle, {alpha}{approx}90{sup o}. The ingredients of the models include a supersymmetric (SUSY) unified gauge group such as SU(5), a discrete family symmetry such as A{sub 4} or S{sub 4}, a shaping symmetry including products of Z{sub 2} and Z{sub 4} groups as well as spontaneous CP violation. We show how the vacuum alignment in such models allows a simple explanation of {alpha}{approx}90{sup o} by a combination of purely real or purely imaginary vacuum expectation values (vevs) of the flavons responsible for family symmetry breaking. This leads to quark mass matrices with 1-3 texture zeros that satisfy the 'phase sum rule' and lepton mass matrices that satisfy the 'lepton mixing sum rule' together with a new prediction that the leptonic CP violating oscillation phase is close to either 0{sup o}, 90{sup o}, 180{sup o}, or 270{sup o} depending on the model, with neutrino masses being purely real (no complex Majorana phases). This leads to the possibility of having right-angled unitarity triangles in both the quark and lepton sectors.
Solving the strong CP problem with discrete symmetries and the right unitarity triangle
Energy Technology Data Exchange (ETDEWEB)
Antusch, Stefan, E-mail: stefan.antusch@unibas.ch [Department of Physics, University of Basel, Klingelbergstr. 82, CH-4056 Basel (Switzerland); Max-Planck-Institut für Physik (Werner-Heisenberg-Institut), Föhringer Ring 6, D-80805 München (Germany); Holthausen, Martin, E-mail: martin.holthausen@mpi-hd.mpg.de [Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany); Schmidt, Michael A., E-mail: michael.schmidt@unimelb.edu.au [ARC Centre of Excellence for Particle Physics at the Terascale, School of Physics, The University of Melbourne, Melbourne, Victoria 3010 (Australia); Spinrath, Martin, E-mail: spinrath@sissa.it [SISSA/ISAS and INFN, Via Bonomea 265, I-34136 Trieste (Italy)
2013-12-21
We present a solution to the strong CP problem based on spontaneous CP violation and discrete family symmetries. The model predicts in a natural way the almost right-angled quark unitarity triangle angle (α≃90°) by making the entries of the quark mass matrices either real or imaginary. By this choice the determinants of the mass matrices are rendered real and hence the strong CP phase vanishes. We present a toy model for the quark sector that demonstrates the viability of our approach.
Triangle-hinge models for unoriented membranes
Fukuma, Masafumi; Sugishita, Sotaro; Umeda, Naoya
2016-07-01
Triangle-hinge models [M. Fukuma, S. Sugishita, and N. Umeda, J. High Energy Phys. 1507, 088 (2015)] are introduced to describe worldvolume dynamics of membranes. The Feynman diagrams consist of triangles glued together along hinges and can be restricted to tetrahedral decompositions in a large-N limit. In this paper, after clarifying that all the tetrahedra resulting in the original models are orientable, we define a version of triangle-hinge models that can describe the dynamics of unoriented membranes. By regarding each triangle as representing a propagation of an open membrane of disk topology, we introduce a local worldvolume parity transformation which inverts the orientation of a triangle, and define unoriented triangle-hinge models by gauging the transformation. Unlike two-dimensional cases, this local transformation generally relates a manifold to a nonmanifold, but still is a well-defined manipulation among tetrahedral decompositions. We further show that matter fields can be introduced in the same way as in the original oriented models. In particular, the models will describe unoriented membranes in a target spacetime by taking matter fields to be the target space coordinates.
Top-Higgs and top-pion phenomenology in the top triangle moose model
Chivukula, R. Sekhar; Simmons, Elizabeth H.; Coleppa, Baradhwaj; Logan, Heather E.; Martin, Adam
2011-03-01
We discuss the deconstructed version of a topcolor-assisted technicolor model wherein the mechanism of top quark mass generation is separated from the rest of electroweak symmetry breaking. The minimal deconstructed version of this scenario is a “triangle moose” model, where the top quark gets its mass from coupling to a top-Higgs field, while the gauge boson masses are generated from a Higgsless sector. The spectrum of the model includes scalar (top-Higgs) and pseudoscalar (top-pion) states. In this paper, we study the properties of these particles, discuss their production mechanisms and decay modes, and suggest how best to search for them at the LHC.
Top-Higgs and Top-pion phenomenology in the Top Triangle Moose model
Chivukula, R Sekhar; Logan, Heather E; Martin, Adam; Simmons, Elizabeth H
2011-01-01
We discuss the deconstructed version of a topcolor-assisted technicolor model wherein the mechanism of top quark mass generation is separated from the rest of electroweak symmetry breaking. The minimal deconstructed version of this scenario is a "triangle moose" model, where the top quark gets its mass from coupling to a top-Higgs field, while the gauge boson masses are generated from a Higgsless sector. The spectrum of the model includes scalar (top-Higgs) and pseudoscalar (top-pion) states. In this paper, we study the properties of these particles, discuss their production mechanisms and decay modes, and suggest how best to search for them at the LHC.
Putting matters on the triangle-hinge models
Fukuma, Masafumi; Umeda, Naoya
2015-01-01
In a recent paper [arXiv:1503.08812] a new class of models generating three-dimensional random volumes are introduced, where the Boltzmann weight of each configuration is given by the product of values assigned to the triangles and the hinges. These triangle-hinge models are characterized by semisimple associative algebras, and the set of possible diagrams can be reduced such that only and all of the three-dimensional manifolds with tetrahedral decompositions are generated. In this letter, we give a general prescription to put matters on the models. We show that the degrees of freedom representing matter fields can be assigned to simplices of any dimensions (tetrahedra, triangles, edges and vertices) in such a way that they have local interactions. Simple examples include the Ising model, the q-state Potts models and the RSOS models coupled to three-dimensional quantum gravity. We also show that the three-dimensional colored tensor models can be obtained by putting specific matters on both tetrahedra and tria...
Unitarity Triangle analysis beyond the Standard Model from UTfit
Bona, Marcella
2016-01-01
The Unitarity Triangle (UT) analysis can be used to constrain the parameter space in possible new physics (NP) scenarios. We present here an update of the UT analysis beyond the Standard Model (SM) by the UTfit collaboration. Assuming NP, all of the available experimental and theoretical information on ∆F = 2 processes is combined using a model-independent parametrisation. We determine the allowed NP contributions in the kaon, D, Bd, and Bs sectors and, in various NP scenarios, we translate them into bounds for the NP scale as a function of NP couplings.
Models of electroweak symmetry breaking
Pomarol, Alex
2015-01-01
This chapter present models of electroweak symmetry breaking arising from strongly interacting sectors, including both Higgsless models and mechanisms involving a composite Higgs. These scenarios have also been investigated in the framework of five-dimensional warped models that, according to the AdS/CFT correspondence, have a four-dimensional holographic interpretation in terms of strongly coupled field theories. We explore the implications of these models at the LHC.
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.
Deconstructed Higgsless Models at LHC: The Top Triangle Moose
Chivukula, R Sekhar; Coleppa, Baradhwaj; Simmons, Elizabeth H
2010-01-01
We describe a deconstructed Higgsless model in which electroweak symmetry breaking results largely from a Higgsless mechanism while the top quark mass is generated by a topcolor mechanism. The top quark mass arises from a Yukawa coupling to an effective top-Higgs which develops a small vacuum expectation value. Both the heavy partners of the electoweak gauge bosons and those for the SM fermions can be light enough to be visible at LHC.
Symmetries in multi-Higgs-doublet models
Ivanov, I P
2012-01-01
We report the recent progress in understanding of symmetries which can be implemented in the scalar sector of electroweak symmetry breaking models with several Higgs doublets. In particular we present the list of finite reparametrization symmetry groups which can appear in the three-Higgs-doublet models.
Symmetries of the dissipative Hofstadter model
Freed, D E
1993-01-01
The dissipative Hofstadter model, which describes a particle in 2-D subject to a periodic potential, uniform magnetic field, and dissipation, is also related to open string boundary states. This model exhibits an SL(2,Z) duality symmetry and hidden reparametrization invariance symmetries. These symmetries are useful for finding exact solutions for correlation functions.
A model of intrinsic symmetry breaking
Energy Technology Data Exchange (ETDEWEB)
Ge, Li [Research Center for Quantum Manipulation, Department of Physics, Fudan University, Shanghai 200433 (China); Li, Sheng [Department of Physics, Zhejiang Normal University, Zhejiang 310004 (China); George, Thomas F., E-mail: tfgeorge@umsl.edu [Office of the Chancellor and Center for Nanoscience, Department of Chemistry and Biochemistry, University of Missouri-St. Louis, St. Louis, MO 63121 (United States); Department of Physics and Astronomy, University of Missouri-St. Louis, St. Louis, MO 63121 (United States); Sun, Xin, E-mail: xin_sun@fudan.edu.cn [Research Center for Quantum Manipulation, Department of Physics, Fudan University, Shanghai 200433 (China)
2013-11-01
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.
Parameter Symmetry of the Interacting Boson Model
Shirokov, A M; Smirnov, Yu F; Shirokov, Andrey M.; Smirnov, Yu. F.
1998-01-01
We discuss the symmetry of the parameter space of the interacting boson model (IBM). It is shown that for any set of the IBM Hamiltonian parameters (with the only exception of the U(5) dynamical symmetry limit) one can always find another set that generates the equivalent spectrum. We discuss the origin of the symmetry and its relevance for physical applications.
Approximate Flavor Symmetry in Supersymmetric Model
Tao, Zhijian
1998-01-01
We investigate the maximal approximate flavor symmetry in the framework of generic minimal supersymmetric standard model. We consider the low energy effective theory of the flavor physics with all the possible operators included. Spontaneous flavor symmetry breaking leads to the approximate flavor symmetry in Yukawa sector and the supersymmetry breaking sector. Fermion mass and mixing hierachies are the results of the hierachy of the flavor symmetry breaking. It is found that in this theory i...
Parameter counting in models with global symmetries
Energy Technology Data Exchange (ETDEWEB)
Berger, Joshua [Institute for High Energy Phenomenology, Newman Laboratory of Elementary Particle Physics, Cornell University, Ithaca, NY 14853 (United States)], E-mail: jb454@cornell.edu; Grossman, Yuval [Institute for High Energy Phenomenology, Newman Laboratory of Elementary Particle Physics, Cornell University, Ithaca, NY 14853 (United States)], E-mail: yuvalg@lepp.cornell.edu
2009-05-18
We present rules for determining the number of physical parameters in models with exact flavor symmetries. In such models the total number of parameters (physical and unphysical) needed to described a matrix is less than in a model without the symmetries. Several toy examples are studied in order to demonstrate the rules. The use of global symmetries in studying the minimally supersymmetric standard model (MSSM) is examined.
Local discrete symmetries from superstring derived models
Energy Technology Data Exchange (ETDEWEB)
Faraggi, A.E.
1996-10-01
Discrete and global symmetries play an essential role in many extensions of the Standard Model, for example, to preserve the proton lifetime, to prevent flavor changing neutral currents, etc. An important question is how can such symmetries survive in a theory of quantum gravity, like superstring theory. In a specific string model the author illustrates how local discrete symmetries may arise in string models and play an important role in preventing fast proton decay and flavor changing neutral currents. The local discrete symmetry arises due to the breaking of the non-Abelian gauge symmetries by Wilson lines in the superstring models and forbids, for example dimension five operators which mediate rapid proton decay, to all orders of nonrenormalizable terms. In the context of models of unification of the gauge and gravitational interactions, it is precisely this type of local discrete symmetries that must be found in order to insure that a given model is not in conflict with experimental observations.
Local discrete symmetries from superstring derived models
Faraggi, Alon E.
1997-02-01
Discrete and global symmetries play an essential role in many extensions of the Standard Model, for example, to preserve the proton lifetime, to prevent flavor changing neutral currents, etc. An important question is how can such symmetries survive in a theory of quantum gravity, like superstring theory. In a specific string model I illustrate how local discrete symmetries may arise in string models and play an important role in preventing fast proton decay and flavor changing neutral currents. The local discrete symmetry arises due to the breaking of the non-Abelian gauge symmetries by Wilson lines in the superstring models and forbids, for example dimension five operators which mediate rapid proton decay, to all orders of nonrenormalizable terms. In the context of models of unification of the gauge and gravitational interactions, it is precisely this type of local discrete symmetries that must be found in order to insure that a given model is not in conflict with experimental observations.
Local discrete symmetries from superstring derived models
Faraggi, A E
1996-01-01
Discrete and global symmetries play an essential role in many extensions of the Standard Model, for example, to preserve the proton lifetime, to prevent flavor changing neutral currents, etc. An important question is how can such symmetries survive in a theory of quantum gravity, like superstring theory. In a specific string model I illustrate how local discrete symmetries may arise in string models and play an important role in preventing fast proton decay and flavor changing neutral currents. The local discrete symmetry arises due to the breaking of the non--Abelian gauge symmetries by Wilson lines in the superstring models and forbids, for example dimension five operators which mediate rapid proton decay, to all orders of nonrenormalizable terms. In the context of models of unification of the gauge and gravitational interactions, it is precisely this type of local discrete symmetries that must be found in order to insure that a given model is not in conflict with experimental observations.
Sierpinski, Waclaw
2011-01-01
The Pythagorean Theorem is one of the fundamental theorems of elementary geometry, and Pythagorean triangles - right triangles whose sides are natural numbers - have been studied by mathematicians since antiquity. In this classic text, a brilliant Polish mathematician explores the intriguing mathematical relationships in such triangles.Starting with ""primitive"" Pythagorean triangles, the text examines triangles with sides less than 100, triangles with two sides that are successive numbers, divisibility of one of the sides by 3 or by 5, the values of the sides of triangles, triangles with th
Torabi-Dashti, Mohammad
2011-01-01
Like Pascal's triangle, Faulhaber's triangle is easy to draw: all you need is a little recursion. The rows are the coefficients of polynomials representing sums of integer powers. Such polynomials are often called Faulhaber formulae, after Johann Faulhaber (1580-1635); hence we dub the triangle Faulhaber's triangle.
Kim, Joohoan
Using the viewpoint of semiotics, this paper "re-reads" Karl Marx's labor theory of value and suggests a "triple triangle" model for commodity production and shows how this model could be a model for semiosis in general. The paper argues that there are three advantages to considering homogeneity of the sign production and the…
Faulting and block rotation in the Afar triangle, East Africa: The Danakil "crank-arm" model
Souriot, T.; Brun, J.-P.
1992-10-01
Several domains of contrasted extensional deformation have been identified in the southern Afar triangle (East Africa) from fault patterns analyzed with panchromatic stereoscopic SPOT (Système Probatoire d'Observation de la Terre) images. Stretching directions and statistical orientation and offset variations of faults fit with the Danakii "crank-arm" model of Sichler: A 10° sinistral rotation of the Danakil block explains the fault geometry and dextral block rotation in the southern part of the Afar triangle, as well as the oblique extension in the Tadjoura Gulf. Analogue modeling supports this interpretation.
Symmetry in Image Registration and Deformation Modeling
DEFF Research Database (Denmark)
Sommer, Stefan; Jacobs, Henry O.
We survey the role of symmetry in diffeomorphic registration of landmarks, curves, surfaces, images and higher-order data. The infinite dimensional problem of finding correspondences between objects can for a range of concrete data types be reduced resulting in compact representations of shape...... and spatial structure. This reduction is possible because the available data is incomplete in encoding the full deformation model. Using reduction by symmetry, we describe the reduced models in a common theoretical framework that draws on links between the registration problem and geometric mechanics....... Symmetry also arises in reduction to the Lie algebra using particle relabeling symmetry allowing the equations of motion to be written purely in terms of Eulerian velocity field. Reduction by symmetry has recently been applied for jet-matching and higher-order discrete approximations of the image matching...
Inextendibility of expanding cosmological models with symmetry
Energy Technology Data Exchange (ETDEWEB)
Dafermos, Mihalis [University of Cambridge, Department of Pure Mathematics and Mathematical Statistics, Wilberforce Road, Cambridge CB3 0WB (United Kingdom); Rendall, Alan D [Max Planck Institute for Gravitational Physics, Albert Einstein Institute, Am Muehlenberg 1, D-14476 Golm (Germany)
2005-12-07
A new criterion for inextendibility of expanding cosmological models with symmetry is presented. It is applied to derive a number of new results and to simplify the proofs of existing ones. In particular, it shows that the solutions of the Einstein-Vlasov system with T{sup 2} symmetry, including the vacuum solutions, are inextendible in the future. The technique introduced adds a qualitatively new element to the available tool-kit for studying strong cosmic censorship. (letter to the editor)
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)
New Symmetries for a Model of Fast Diffusion
Institute of Scientific and Technical Information of China (English)
QIN Mao-Chang; XU Xue-Jun; MEI Feng-Xiang
2004-01-01
@@ The new symmetries for a mathematical model of fast diffusion are determined. A new system method is given to search for new symmetries of differential equations written in a conserved form, several new symmetry generators and exact solutions are presented.
Models for neutrino mass with discrete symmetries
Morisi, S.
2011-08-01
Discrete non-abelian flavor symmetries give in a natural way tri-bimaximal (TBM) mixing as showed in a prototype model. However neutrino mass matrix pattern may be very different from the tri-bimaximal one if small deviations of TBM will be observed. We give the result of a model independent analysis for TBM neutrino mass pattern.
Models for neutrino mass with discrete symmetries
Morisi, S
2010-01-01
Discrete non-abelian flavor symmetries give in a natural way tri-bimaximal (TBM) mixing as showed in a prototype model. However neutrino mass matrix pattern may be very different from the tri-bimaximal one if small deviations of TBM will be observed. We give the result of a model independent analysis for TBM neutrino mass pattern.
Lyon, Edward G.
2011-08-01
This paper describes the Assessment Practices Framework and how I used it to study a high school Chemistry teacher as she designed, implemented, and learned from a chemistry lab report. The framework consists of exploring three teacher-centered components of classroom assessment (assessment beliefs, practices, and reflection) and analyzing components with the assessment triangle model (Pellegrino et al. in, Knowing what students know: The science and design of educational assessment. National Academy Press, Washington DC, 2001). Employing the framework, I report the teacher's assessment practices, report the alignment in her assessment practices through the three vertices of the assessment triangle (cognition, observation, and interpretation), and suggest relations between her beliefs and practices. I conclude by discussing the contribution and limitations of the Assessment Practices Framework while conducting future research and supporting science teachers in assessing student learning.
Cutter-workpiece engagement determination for general milling using triangle mesh modeling
Directory of Open Access Journals (Sweden)
Xun Gong
2016-04-01
Full Text Available Cutter-workpiece engagement (CWE is the instantaneous contact geometry between the cutter and the in-process workpiece during machining. It plays an important role in machining process simulation and directly affects the calculation of the predicted cutting forces and torques. The difficulty and challenge of CWE determination come from the complexity due to the changing geometry of in-process workpiece and the curved tool path of cutter movement, especially for multi-axis milling. This paper presents a new method to determine the CWE for general milling processes. To fulfill the requirement of generality, which means for any cutter type, any in-process workpiece shape, and any tool path even with self-intersections, all the associated geometries are to be modeled as triangle meshes. The involved triangle-to-triangle intersection calculations are carried out by an effective method in order to realize the multiple subtraction Boolean operations between the tool and the workpiece mesh models and to determine the CWE. The presented method has been validated by a series of case studies of increasing machining complexity to demonstrate its applicability to general milling processes.
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.
Anomalous Abelian symmetry in the standard model
Energy Technology Data Exchange (ETDEWEB)
Ramond, P.
1995-12-31
The observed hierarchy of quark and lepton masses can be parametrized by nonrenormalizable operators with dimensions determined by an anomalous Abelian family symmetry, a gauge extension to the minimal supersymmetric standard model. Such an Abelian symmetry is generic to compactified superstring theories, with its anomalies compensated by the Green-Schwarz mechanism. If we assume these two symmetries to be the same, we find the electroweak mixing angle to be sin {sup 2}{theta}{sub {omega}} = 3/8 at the string scale, just by setting the ratio of the product of down quark to charged lepton masses equal to one at the string scale. This assumes no GUT structure. The generality of the result suggests a superstring origin for the standard model. We generalize our analysis to massive neutrinos, and mixings in the lepton sector.
Supersymmetric Defect Models and Mirror Symmetry
Hook, Anson; Torroba, Gonzalo
2013-01-01
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 N=4 QED with a single charged hypermultiplet (and its mirror, the theory of a free hypermultiplet) as well as 3d N=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 N=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.
Hidden Symmetry of a Fluid Dynamical Model
Neves, C
2001-01-01
A connection between solutions of the relativistic d-brane system in (d+1) dimensions with the solutions of a Galileo invariant fluid in d-dimensions is by now well established. However, the physical nature of the light-cone gauge description of a relativistic membrane changes after the reduction to the fluid dynamical model since the gauge symmetry is lost. In this work we argue that the original gauge symmetry present in a relativistic d-brane system can be recovered after the reduction process to a d-dimensional fluid model. To this end we propose, without introducing Wess-Zumino fields, a gauge invariant theory of isentropic fluid dynamics and show that this symmetry corresponds to the invariance under local translation of the velocity potential in the fluid dynamics picture. We show that different but equivalent choices of the sympletic sector lead to distinct representations of the embedded gauge algebra.
Systematic model building with flavor symmetries
Energy Technology Data Exchange (ETDEWEB)
Plentinger, Florian
2009-12-19
The observation of neutrino masses and lepton mixing has highlighted the incompleteness of the Standard Model of particle physics. In conjunction with this discovery, new questions arise: why are the neutrino masses so small, which form has their mass hierarchy, why is the mixing in the quark and lepton sectors so different or what is the structure of the Higgs sector. In order to address these issues and to predict future experimental results, different approaches are considered. One particularly interesting possibility, are Grand Unified Theories such as SU(5) or SO(10). GUTs are vertical symmetries since they unify the SM particles into multiplets and usually predict new particles which can naturally explain the smallness of the neutrino masses via the seesaw mechanism. On the other hand, also horizontal symmetries, i.e., flavor symmetries, acting on the generation space of the SM particles, are promising. They can serve as an explanation for the quark and lepton mass hierarchies as well as for the different mixings in the quark and lepton sectors. In addition, flavor symmetries are significantly involved in the Higgs sector and predict certain forms of mass matrices. This high predictivity makes GUTs and flavor symmetries interesting for both, theorists and experimentalists. These extensions of the SM can be also combined with theories such as supersymmetry or extra dimensions. In addition, they usually have implications on the observed matter-antimatter asymmetry of the universe or can provide a dark matter candidate. In general, they also predict the lepton flavor violating rare decays {mu} {yields} e{gamma}, {tau} {yields} {mu}{gamma}, and {tau} {yields} e{gamma} which are strongly bounded by experiments but might be observed in the future. In this thesis, we combine all of these approaches, i.e., GUTs, the seesaw mechanism and flavor symmetries. Moreover, our request is to develop and perform a systematic model building approach with flavor symmetries and
Efficient Symmetry Reduction and the Use of State Symmetries for Symbolic Model Checking
Directory of Open Access Journals (Sweden)
Christian Appold
2010-06-01
Full Text Available One technique to reduce the state-space explosion problem in temporal logic model checking is symmetry reduction. The combination of symmetry reduction and symbolic model checking by using BDDs suffered a long time from the prohibitively large BDD for the orbit relation. Dynamic symmetry reduction calculates representatives of equivalence classes of states dynamically and thus avoids the construction of the orbit relation. In this paper, we present a new efficient model checking algorithm based on dynamic symmetry reduction. Our experiments show that the algorithm is very fast and allows the verification of larger systems. We additionally implemented the use of state symmetries for symbolic symmetry reduction. To our knowledge we are the first who investigated state symmetries in combination with BDD based symbolic model checking.
The Symmetry of Partner Modelling
Dillenbourg, Pierre; Lemaignan, Séverin; Sangin, Mirweis; Nova, Nicolas; Molinari, Gaëlle
2016-01-01
Collaborative learning has often been associated with the construction of a shared understanding of the situation at hand. The psycholinguistics mechanisms at work while establishing common grounds are the object of scientific controversy. We postulate that collaborative tasks require some level of mutual modelling, i.e. that each partner needs…
Random matrix model approach to chiral symmetry
Verbaarschot, J J M
1996-01-01
We review the application of random matrix theory (RMT) to chiral symmetry in QCD. Starting from the general philosophy of RMT we introduce a chiral random matrix model with the global symmetries of QCD. Exact results are obtained for universal properties of the Dirac spectrum: i) finite volume corrections to valence quark mass dependence of the chiral condensate, and ii) microscopic fluctuations of Dirac spectra. Comparisons with lattice QCD simulations are made. Most notably, the variance of the number of levels in an interval containing $n$ levels on average is suppressed by a factor $(\\log n)/\\pi^2 n$. An extension of the random matrix model model to nonzero temperatures and chemical potential provides us with a schematic model of the chiral phase transition. In particular, this elucidates the nature of the quenched approximation at nonzero chemical potential.
State of Modeling Symmetry in Hohlraums
Energy Technology Data Exchange (ETDEWEB)
Jones, O. S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2015-07-22
Modeling radiation drive asymmetry is challenging problem whose agreement with data depends on the hohlraum gas fill density. Modeling to date uses the HYDRA code with crossbeam energy transfer (CBET) calculated separately, and backscattered light removed from the input laser. For high fill hohlraums (~>1 mg/cc), matching symmetry requires ad hoc adjustments to CBET during picket and peak of drive. For near-vacuum hohlraums, there is little CBET or backscatter, and drive is more waist-high than predicted. For intermediate fill densities (~0.6 mg/cc) there appears to be a region of small CBET and backscatter where symmetry is reasonably well modeled. A new technique where backscatter and CBET are done “inline” appears it could bring high fill simulations closer to data.
Rotational symmetry breaking in baby Skyrme models
Hen, Itay
2007-01-01
We consider multisolitons with charges 1 =< B =< 5 in the baby Skyrme model for the one-parametric family of potentials U=\\mu^2 (1-\\phi_3)^s with 0models. We find that for charge one, stable solutions exist for every value of s and they are rotationally-symmetric. For higher charges, stable solutions exist only below s \\approx 2. In the charge-two sector the stable solutions are always rotationally-symmetric and ring-like. For charge three and above, rotational symmetry is exhibited only in the small s region; above a certain critical value of s, this symmetry is broken and a strong repulsion between the constituent one-Skyrmions becomes apparent. We also compute the spatial energy distributions of these solutions.
Particle Mechanics Models with W-symmetries
Gomis, J P; Kamimura, K; Roca, J
1995-01-01
We introduce a particle mechanics model with Sp($2M$) gauge invariance. Different partial gauge-fixings by means of sl(2) embeddings on the gauge algebra lead to reduced models which are invariant under diffeomorphisms and classical non-linear \\W-transformations as the residual gauge symmetries thus providing a set of models of gauge and matter fields coupled in a \\W-invariant way. The equations of motion for the matter variables give Lax operators in a matrix form. We examine several examples in detail and discuss the issue of integration of infinitesimal \\W-transformations.
Geodesic models generated by Lie symmetries
Abebe, G Z; Govinder, K S
2014-01-01
We study the junction condition relating the pressure to the heat flux at the boundary of a shearing and expanding spherically symmetric radiating star when the fluid particles are travelling in geodesic motion. The Lie symmetry generators that leave the junction condition invariant are identified and the optimal system is generated. We use each element of the optimal system to transform the partial differential equation to an ordinary differential equation. New exact solutions, which are group invariant under the action of Lie point infinitesimal symmetries, are found. We obtain families of traveling wave solutions and self-similar solutions, amongst others. The gravitational potentials are given in terms of elementary functions, and the line elements can be given explicitly in all cases. We show that the Friedmann dust model is regained as a special case, and we can connect our results to earlier investigations.
Electroweak symmetry breaking beyond the Standard Model
Indian Academy of Sciences (India)
Gautam Bhattacharyya
2012-10-01
In this paper, two key issues related to electroweak symmetry breaking are addressed. First, how ﬁne-tuned different models are that trigger this phenomenon? Second, even if a light Higgs boson exists, does it have to be necessarily elementary? After a brief introduction, the ﬁne-tuning aspects of the MSSM, NMSSM, generalized NMSSM and GMSB scenarios shall be reviewed, then the little Higgs, composite Higgs and the Higgsless models shall be compared. Finally, a broad overview will be given on where we stand at the end of 2011.
Approximate Noether gauge symmetries of the Bardeen model
Energy Technology Data Exchange (ETDEWEB)
Camci, U. [Akdeniz University, Department of Physics, Faculty of Science, Antalya (Turkey)
2014-12-01
We investigate the approximate Noether gauge symmetries of the geodesic Lagrangian for the Bardeen spacetime model. This is accommodated by a set of new approximate Noether gauge symmetry relations for the perturbed geodesic Lagrangian in the spacetime. A detailed analysis of the spacetime of the Bardeen model up to third-order approximate Noether gauge symmetries is presented. (orig.)
Pythagorean triangles within Pythagorean triangles
Zelator, Konstantine
2010-01-01
In this work, we investigate the following question. Given a Pythagorean triangle BCA, with the right angle at C, let P be a point on the hupotenuse BA; and let D and E be the perpendicular projections of the point P onto the sides BC and CA respectively.When is either of the right triangles BDP and PEA Pythagorean? As it turns out, according to Theorem1, they are either both Pythagorean, or neither of them is.When they are both Pythagorean,a complete parametric description of these two triangles is given; in terms of the parameters that describe the Pythagorean triangle BCA. Later in the paper, we offer a complete analysis of three special cases:the case wherein the point P is the midpoint M of the hypotenuse BA; the case when P is the foot I of the 90 degree angle bisector;and the case in ehich the point P is the foot F of the perpendicular drawn from the vertex C to the hypotenuse. After that, some other cases are investigated as well.Specifically, we consider the case in which not only the triangles BDP a...
Tourism Based on the Model of Strategic Place Triangle (A Case Study in Wisata Bahari Lamongan
Directory of Open Access Journals (Sweden)
Ismuhadi Heru Wijayanto
2014-09-01
Full Text Available Tourism is a very promising prospects to support the economic development of a region. We assess Wisata Bahari Lamongan (WBL as a tourism object. WBL was having significant decreased visitors in the last six years, thus a strategic plan is need to re-increase the number of visitors. Thisstudy used Strategic Triangle Place (SPT model as an analysis tool to assess the strategic planning in WBL. SPT is an approach that includes three key components, namely: Positioning, Differentiation and Brand (PDB. This research used Soft System Methodology (SSM which relevant to analyzethe strategic plan model which is expected to be recommendations from tourists on problems in WBL.The result of this showed that the strategic planning of WBL did not completely accordance with the SPT model. Positioning and differentiation elements were still weak, and the brand was not well developed. Therefore, we recommend WBL to set targeted segmentation of all social backgrounds and ages, especially children. WBL shouldmade the sea as main differentiated factor, thus it has marine tourism potential. WBL should build an image by providing best service quality, security, comfortness, cleanliness, and best quality rides. Keywords: Strategic Planning, Strategic Place Triangle, Positioning, Differentiation, Brand
Energy Spectrum Symmetry of Heisenberg Model in Fock Space
Institute of Scientific and Technical Information of China (English)
WANG An-Min; ZHU Ren-Gui
2006-01-01
@@ We extend the BCS paring model with equally spaced energy levels to a general one-dimensional spin-l/2 Heisenberg model. The two well-known symmetries of the Heisenberg model, i.e. permutational and spin-inversion symmetries, no longer exist. However, when jointing these two operations together, we find a new symmetry of energy spectrum between its subspace n and subspace L - n of the Fock space. A rigorous proof is presented.
A minimal seesaw model with mu-tau symmetry
Jurciukonis, Darius; Juodagalvis, Andrius
2015-01-01
We analyse a flavour model for a lepton sector which is based on type I seesaw mechanism, a Z_2 symmetry for lepton flavours, a mu-tau interchange symmetry and a CP symmetry. This model fits well the data of neutrino mass squared differences and oscillation angles. The model predicts an overall neutrino mass scale for normal and inverted neutrino mass hierarchy and the effective mass m_beta, which is used in the neutrinoless double beta decay.
Symmetry breaking: The standard model and superstrings
Energy Technology Data Exchange (ETDEWEB)
Gaillard, M.K.
1988-08-31
The outstanding unresolved issue of the highly successful standard model is the origin of electroweak symmetry breaking and of the mechanism that determines its scale, namely the vacuum expectation value (vev)v that is fixed by experiment at the value v = 4m//sub w//sup 2///g/sup 2/ = (..sqrt..2G/sub F/)/sup /minus/1/ approx. = 1/4 TeV. In this talk I will discuss aspects of two approaches to this problem. One approach is straightforward and down to earth: the search for experimental signatures, as discussed previously by Pierre Darriulat. This approach covers the energy scales accessible to future and present laboratory experiments: roughly (10/sup /minus/9/ /minus/ 10/sup 3/)GeV. The second approach involves theoretical speculations, such as technicolor and supersymmetry, that attempt to explain the TeV scale. 23 refs., 5 figs.
A Molecular Model for Chiral Symmetry Breaking
Latinwo, Folarin; Stillinger, Frank; Debenedetti, Pablo
In this work, we present a new class of molecular models for chiral phenomena in condensed matter systems. A key feature of these models is the ability of the four-site (tetramer) ``molecules'' to inter-convert between two distinct chiral forms (enantiomers). Given this feature, we use analytical theory and computer simulations to investigate the emergent chiral properties (including symmetry breaking) over a range of conditions. In particular, we consider the single-molecule level and condensed-phase behavior of our model system. Interestingly, we find that our liquid-phase predictions are in excellent agreement with recent experimental reports on chiral self-sorting in isotropic liquids. From this perspective, our model demonstrates accurate predictive capabilities, as well as a platform for understanding the microscopic origins of a variety of chiral phenomena. In a broader context, we anticipate that this class of models will be relevant to chirality-dominated areas such as the pharmaceutical industry and pre-biotic geochemistry.
Symmetry and partial order reduction techniques in model checking Rebeca
Jaghouri, M.M.; Sirjani, M.; Mousavi, M.R.; Movaghar, A.
2007-01-01
Rebeca is an actor-based language with formal semantics that can be used in modeling concurrent and distributed software and protocols. In this paper, we study the application of partial order and symmetry reduction techniques to model checking dynamic Rebeca models. Finding symmetry based equivalen
Discrete flavor symmetries in D-brane models
Marchesano, Fernando; Vázquez-Mercado, Liliana
2013-01-01
We study the presence of discrete flavor symmetries in D-brane models of particle physics. By analyzing the compact extra dimensions of these models one can determine when such symmetries exist both in the context of intersecting and magnetized D-brane constructions. Our approach allows to distinguish between approximate and exact discrete symmetries, and it can be applied to compactification manifolds with continuous isometries or to manifolds that only contain discrete isometries, like Calabi-Yau three-folds. We analyze in detail the class of rigid D-branes models based on a Z_2 x Z'_2 toroidal orientifold, for which the flavor symmetry group is either the dihedral group D_4 or tensor products of it. We construct explicit Pati-Salam examples in which families transform in non-Abelian representations of the flavor symmetry group, constraining Yukawa couplings beyond the effect of massive U(1) D-brane symmetries.
Classifying Chinese children with dyslexia by dual-route and triangle models of Chinese reading.
Wang, Li-Chih; Yang, Hsien-Ming
2014-11-01
This present study focuses on classifying developmental dyslexia by combining two famous models, the dual-route model and the triangle model of Chinese reading, re-examining validity of the subtypes, and observing the error types of word recognition for each subtype. Sixty-sixth graders with dyslexia in Chinese and 45 sixth graders who were matched by age and IQ with the dyslexic group were involved in the present study. Twelve (20%) sixth graders from the dyslexic group were classified as having phonological dyslexia, 11 (18.3%) were classified as surface dyslexia, 12 (20%) were classified as deep dyslexia, and five (8.3%) of them were classified as displaying more than one kind of deficit. Besides, still more than half (31; 51.7%) of the dyslexic group did not belong to any subtypes here. These subtypes had a good validity based on comparison of their phonological awareness, orthography, and semantics. Finally, for their error types of word recognition, both children with multiple-deficit dyslexia and children with non-subtype dyslexia showed a proportional pattern of six kinds of errors. Children with phonological dyslexia showed more phonetic errors and analogy errors, children with surface dyslexia showed more visual errors and analogy errors, and children with deep dyslexia showed more semantic errors and selective errors.
Quantum symmetries induced by phonons in the Hubbard model
Montorsi, Arianna; Rasetti, Mario
1994-03-01
We show how the addition of a phonon field to the Hubbard model deforms the superconducting su(2) part of the global symmetry Lie algebra su(2)⊗su(2)/openZ2, holding at half filling for the customary model, into a quantum [su(2)]q symmetry, holding for a filling which depends on the electron-phonon interaction strength. Such symmetry originates in the feature that in the presence of phonons the hopping amplitude turns out to depend on the coupling strength. The states generated by resorting to this q symmetry exhibit both off-diagonal long-range order and pairing.
Kac-Moody Symmetry in Hosotani Model
Shiraishi, Kiyoshi
2012-01-01
The symmetry of the massive tower of fields in higher-dimensional Yang-Mills theory compactified on a space-time of the form M_d x S^1 is clarified. The transformations form a loop algebra, a class of Kac-Moody algebras. Since the symmetry is spontaneously broken, vector fields "eat" Goldstone bosons and acquire masses. The field of zero-mass mode can also become massive provided that the field of the internal component develops a vacuum expectation value. The relation between the "restoration" of the symmetry in massive modes and the gauge transformation of the zero-mode vacuum field is discussed.
Symmetries and solvable models for evaporating 2D black holes
Cruz, J; Navarro-Salas, J; Talavera, C F
1997-01-01
We study the evaporation process of a 2D black hole in thermal equilibrium when the ingoing radiation is switched off suddenly. We also introduce global symmetries of generic 2D dilaton gravity models which generalize the extra symmetry of the CGHS model.
Review of Rotational Symmetry Breaking in Baby Skyrme Models
Karliner, Marek
2009-01-01
We discuss one of the most interesting phenomena exhibited by baby skyrmions -- breaking of rotational symmetry. The topics we will deal with here include the appearance of rotational symmetry breaking in the static solutions of baby Skyrme models, both in flat as well as in curved spaces, the zero-temperature crystalline structure of baby skyrmions, and finally, the appearance of spontaneous breaking of rotational symmetry in rotating baby skyrmions.
Thawing model and symmetry breaking in a coupled quintessence model
Honardoost, M; Sepangi, H R
2015-01-01
We consider the thawing model in the framework of coupled quintessence scenario. The effective potential has $Z_2$ symmetry which is broken spontaneously when dark matter density becomes less than a critical value leading the quintessence equation of state parameter to deviate from -1. Conditions required for this procedure are obtained and analytical solution for the equation of state parameter is derived.
Discrete symmetries in the three-Higgs-doublet model
Ivanov, I P
2012-01-01
N-Higgs-doublet models (NHDM) are among the most popular examples of electroweak symmetry breaking mechanisms beyond the Standard Model. Discrete symmetries imposed on the NHDM scalar potential play a pivotal role in shaping the phenomenology of the model, and various symmetry groups have been studied so far. However, in spite of all efforts, the classification of finite Higgs-family symmetry groups realizable in NHDM for any N>2 is still missing. Here, we solve this problem for the three-Higgs-doublet model. Using recently found realizable abelian groups and applying Burnside's theorem and other group-theoretic tools, we find the full list of finite symmetry groups of Higgs-family transformations which are realizable in the scalar sector of 3HDM.
Relativistic pseudospin symmetry and shell model Hamiltonians that conserve pseudospin symmetry
Energy Technology Data Exchange (ETDEWEB)
Ginocchio, Joseph N [Los Alamos National Laboratory
2010-09-21
Professor Akito Arima and his colleagues discovered 'pseudospin' doublets forty-one years ago in spherical nuclei. These doublets were subsequently discovered in deformed nuclei. We show that pseudospin symmetry is an SU(2) symmetry of the Dirac Hamiltonian which occurs when the scalar and vector potentials are opposite in sign but equal in magnitude. This symmetry occurs independent of the shape of the nucleus: spherical, axial deformed, triaxial, and gamma unstable. We survey some of the evidence that pseudospin symmetry is approximately conserved for a Dirac Hamiltonian with realistic scalar and vector potentials by examining the energy spectra, the lower components of the Dirac eigenfunctions, the magnetic dipole and Gamow-Teller transitions in nuclei, the upper components of the Dirac eigenfunctions, and nucleon-nucleus scattering. We shall also suggest that pseudospin symmetry may have a fundamental origin in chiral symmetry breaking by examining QCD sum rules. Finally we derive the shell model Hamiltonians which conserve pseudospin and show that they involve tensor interactions.
Self-consistent Models of Strong Interaction with Chiral Symmetry
Nambu, Y.; Pascual, P.
1963-04-01
Some simple models of (renormalizable) meson-nucleon interaction are examined in which the nucleon mass is entirely due to interaction and the chiral ( gamma {sub 5}) symmetry is "broken'' to become a hidden symmetry. It is found that such a scheme is possible provided that a vector meson is introduced as an elementary field. (auth)
SU(5) symmetry of spdfg interacting boson model
Institute of Scientific and Technical Information of China (English)
LI; Jingsheng(李京生); LIU; Yuxin(刘玉鑫); GAO; Peng(高鹏)
2003-01-01
The extended interacting boson model with s-, p-, d-, f- and g-bosons included (spdfg IBM)is investigated. The algebraic structure including the generators, the Casimir operators of the groups at the SU(5) dynamical symmetry and the branching rules of the irreducible representation reductions along the group chain are obtained. The typical energy spectrum of the symmetry is given.
Symmetry breaking and cosmic acceleration in scalar field models
Sadjadi, M Mohseni; Sepangi, H R
2015-01-01
We study the possible role of symmetry breaking in the onset of the acceleration of the Universe in a scalar field dark energy model. We propose a new scenario in which acceleration of the Universe is driven by a positive potential produced by means of symmetry breaking.
PT-symmetry in quasi-integrable models
Assis, P E G
2015-01-01
We reinforce the observations of almost stable scattering in nonintegrable models and show that $\\mathcal{PT}$-symmetry can be used as a guiding principle to select relevant systems also when it comes to integrability properties. We show that the presence of unbroken $\\mathcal{PT}$-symmetry in classical field theories produces quasi-integrable excitations with asymptotically conserved charges.
Partial dynamical symmetry in the symplectic shell model
Energy Technology Data Exchange (ETDEWEB)
Escher, J. [TRIUMF, Vancouver, British Columbia (Canada); Leviatan, A. [Hebrew Univ., Racah Inst. of Physics, Jerusalem (Israel)
2000-08-01
We present an example of a partial dynamical symmetry (PDS) in an interacting fermion system and demonstrate the close relationship of the associated Hamiltonians with a realistic quadrupole-quadrupole interaction, thus shedding light on this important interaction. Specifically, in the framework of the symplectic shell model of nuclei, we prove the existence of a family of fermionic Hamiltonians with partial SU(3) symmetry. We outline the construction process for the PDS eigenstates with good symmetry and give analytic expressions for the energies of these states and E2 transition strengths between them. Characteristics of both pure and mixed-symmetry PDS eigenstates are discussed and the resulting spectra and transition strengths are compared to those of real nuclei. The PDS concept is shown to be relevant to the description of prolate, oblate, as well as triaxially deformed nuclei. Similarities and differences between the fermion case and the previously established partial SU(3) symmetry in the interacting boson model are considered. (author)
SO(10) models with flavour symmetries: classification and examples
Ivanov, I. P.; Lavoura, L.
2016-10-01
Renormalizable SO(10) grand unified theory (GUT) models equipped with flavour symmetries are a popular framework for addressing the flavour puzzle. Usually, the flavour symmetry group has been an ad hoc choice, and no general arguments limiting this choice were known. In this paper, we establish the full list of flavour symmetry groups which may be enforced, without producing any further accidental symmetry, on the Yukawa-coupling matrices of an SO(10) GUT with arbitrary numbers of scalar multiplets in the {{10}}, \\bar{{{126}}}, and {{120}} representations of SO(10). For each of the possible discrete non-Abelian symmetry groups, we present examples of minimal models which do not run into obvious contradiction with the phenomenological fermion masses and mixings.
A left-right symmetric flavor symmetry model
Energy Technology Data Exchange (ETDEWEB)
Rodejohann, Werner [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Xu, Xun-Jie [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Tsinghua University, Institute of Modern Physics and Center for High Energy Physics, Beijing (China)
2016-03-15
We discuss flavor symmetries in left-right symmetric theories. We show that such frameworks are a different environment for flavor symmetry model building compared to the usually considered cases. This does not only concern the need to obey the enlarged gauge structure, but also more subtle issues with respect to residual symmetries. Furthermore, if the discrete left-right symmetry is charge conjugation, potential inconsistencies between the flavor and charge conjugation symmetries should be taken care of. In our predictive model based on A{sub 4} we analyze the correlations between the smallest neutrino mass, the atmospheric mixing angle and the Dirac CP phase, the latter prefers to lie around maximal values. There is no lepton flavor violation from the Higgs bi-doublet. (orig.)
A left-right symmetric flavor symmetry model
Rodejohann, Werner
2015-01-01
We discuss flavor symmetries in left-right symmetric theories. We show that such frameworks are a different environment for flavor symmetry model building compared to the usually considered cases. This does not only concern the need to obey the enlarged gauge structure, but also more subtle issues with respect to residual symmetries. Furthermore, if the discrete left-right symmetry is charge conjugation, potential inconsistencies between the flavor and charge conjugation symmetries should be taken care of. In our predictive model based on $A_4$ we analyze the correlations between the smallest neutrino mass, the atmospheric mixing angle and the Dirac CP phase, the latter prefers to lie around maximal values. There is no lepton flavor violation from the Higgs bi-doublet.
A left-right symmetric flavor symmetry model
Rodejohann, Werner; Xu, Xun-Jie
2016-03-01
We discuss flavor symmetries in left-right symmetric theories. We show that such frameworks are a different environment for flavor symmetry model building compared to the usually considered cases. This does not only concern the need to obey the enlarged gauge structure, but also more subtle issues with respect to residual symmetries. Furthermore, if the discrete left-right symmetry is charge conjugation, potential inconsistencies between the flavor and charge conjugation symmetries should be taken care of. In our predictive model based on A_4 we analyze the correlations between the smallest neutrino mass, the atmospheric mixing angle and the Dirac CP phase, the latter prefers to lie around maximal values. There is no lepton flavor violation from the Higgs bi-doublet.
New statistical lattice model with double honeycomb symmetry
Naji, S.; Belhaj, A.; Labrim, H.; Bhihi, M.; Benyoussef, A.; El Kenz, A.
2014-04-01
Inspired from the connection between Lie symmetries and two-dimensional materials, we propose a new statistical lattice model based on a double hexagonal structure appearing in the G2 symmetry. We first construct an Ising-1/2 model, with spin values σ = ±1, exhibiting such a symmetry. The corresponding ground state shows the ferromagnetic, the antiferromagnetic, the partial ferrimagnetic and the topological ferrimagnetic phases depending on the exchange couplings. Then, we examine the phase diagrams and the magnetization using the mean field approximation (MFA). Among others, it has been suggested that the present model could be localized between systems involving the triangular and the single hexagonal lattice geometries.
Renormalisation group improved leptogenesis in family symmetry models
Energy Technology Data Exchange (ETDEWEB)
Cooper, Iain K., E-mail: ikc1g08@soton.ac.uk [School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ (United Kingdom); King, Stephen F., E-mail: king@soton.ac.uk [School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ (United Kingdom); Luhn, Christoph, E-mail: christoph.luhn@durham.ac.uk [School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ (United Kingdom); Institute for Particle Physics Phenomenology, University of Durham, Durham, DH1 3LE (United Kingdom)
2012-06-11
We study renormalisation group (RG) corrections relevant for leptogenesis in the case of family symmetry models such as the Altarelli-Feruglio A{sub 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 {tau} Yukawa couplings.
Directory of Open Access Journals (Sweden)
David A Rolls
Full Text Available We compare two broad types of empirically grounded random network models in terms of their abilities to capture both network features and simulated Susceptible-Infected-Recovered (SIR epidemic dynamics. The types of network models are exponential random graph models (ERGMs and extensions of the configuration model. We use three kinds of empirical contact networks, chosen to provide both variety and realistic patterns of human contact: a highly clustered network, a bipartite network and a snowball sampled network of a "hidden population". In the case of the snowball sampled network we present a novel method for fitting an edge-triangle model. In our results, ERGMs consistently capture clustering as well or better than configuration-type models, but the latter models better capture the node degree distribution. Despite the additional computational requirements to fit ERGMs to empirical networks, the use of ERGMs provides only a slight improvement in the ability of the models to recreate epidemic features of the empirical network in simulated SIR epidemics. Generally, SIR epidemic results from using configuration-type models fall between those from a random network model (i.e., an Erdős-Rényi model and an ERGM. The addition of subgraphs of size four to edge-triangle type models does improve agreement with the empirical network for smaller densities in clustered networks. Additional subgraphs do not make a noticeable difference in our example, although we would expect the ability to model cliques to be helpful for contact networks exhibiting household structure.
Energy Technology Data Exchange (ETDEWEB)
Tareyeva, E.E. [Institute for High Pressure Physics, Russian Academy of Sciences, 142190 Troitsk (Russian Federation); Schelkacheva, T.I., E-mail: tanschelk@gmail.com [Institute for High Pressure Physics, Russian Academy of Sciences, 142190 Troitsk (Russian Federation); Chtchelkatchev, N.M. [Institute for High Pressure Physics, Russian Academy of Sciences, 142190 Troitsk (Russian Federation); L.D. Landau Institute for Theoretical Physics, Russian Academy of Sciences, 117940 Moscow (Russian Federation); Department of Theoretical Physics, Moscow Institute of Physics and Technology, 141700 Moscow (Russian Federation)
2013-02-15
We investigate near the point of glass transition the expansion of the free energy corresponding to the generalized Sherrington–Kirkpatrick model with arbitrary diagonal operators U{sup -hat} standing instead of Ising spins. We focus on the case when U{sup -hat} is an operator with broken reflection symmetry. Such a consideration is important for understanding the behavior of spin glass-like phases in a number of real physical systems, mainly in orientational glasses in mixed molecular crystals which present just the case. We build explicitly a full replica symmetry breaking (FRSB) solution of the equations for the orientational glass order parameters when the nonsymmetric part of U{sup -hat} is small. This particular result presents a counterexample in the context of usually adopted conjecture of the absence of FRSB solution in systems with no reflection symmetry.
Tareyeva, E. E.; Schelkacheva, T. I.; Chtchelkatchev, N. M.
2013-02-01
We investigate near the point of glass transition the expansion of the free energy corresponding to the generalized Sherrington-Kirkpatrick model with arbitrary diagonal operators Uˆ standing instead of Ising spins. We focus on the case when Uˆ is an operator with broken reflection symmetry. Such a consideration is important for understanding the behavior of spin glass-like phases in a number of real physical systems, mainly in orientational glasses in mixed molecular crystals which present just the case. We build explicitly a full replica symmetry breaking (FRSB) solution of the equations for the orientational glass order parameters when the nonsymmetric part of Uˆ is small. This particular result presents a counterexample in the context of usually adopted conjecture of the absence of FRSB solution in systems with no reflection symmetry.
Partial Dynamical Symmetry in the Symplectic Shell Model
Escher, J; Escher, Jutta; Leviatan, Amiram
2002-01-01
We present an example of a partial dynamical symmetry (PDS) in an interacting fermion system and demonstrate the close relationship of the associated Hamiltonians with a realistic quadrupole-quadrupole interaction, thus shedding new light on this important interaction. Specifically, in the framework of the symplectic shell model of nuclei, we prove the existence of a family of fermionic Hamiltonians with partial SU(3) symmetry. We outline the construction process for the PDS eigenstates with good symmetry and give analytic expressions for the energies of these states and E2 transition strengths between them. Characteristics of both pure and mixed-symmetry PDS eigenstates are discussed and the resulting spectra and transition strengths are compared to those of real nuclei. The PDS concept is shown to be relevant to the description of prolate, oblate, as well as triaxially deformed nuclei. Similarities and differences between the fermion case and the previously established partial SU(3) symmetry in the Interact...
Quantum symmetries induced by phonons in the Hubbard model
Montorsi, Arianna; Rasetti, Mario
1994-01-01
We show how the addition of a phonon field to the Hubbard model deforms the superconducting su(2) part of the global symmetry Lie algebra su(2)⊗su(2)/openZ2, holding at half filling for the customary model, into a quantum [su(2)]q symmetry, holding for a filling which depends on the electron-phonon interaction strength. Such symmetry originates in the feature that in the presence of phonons the hopping amplitude turns out to depend on the coupling strength. The states generated by resorting t...
Classically conformal radiative neutrino model with gauged B - L symmetry
Okada, Hiroshi; Orikasa, Yuta
2016-09-01
We propose a classically conformal model in a minimal radiative seesaw, in which we employ a gauged B - L symmetry in the standard model that is essential in order to work the Coleman-Weinberg mechanism well that induces the B - L symmetry breaking. As a result, nonzero Majorana mass term and electroweak symmetry breaking simultaneously occur. In this framework, we show a benchmark point to satisfy several theoretical and experimental constraints. Here theoretical constraints represent inert conditions and Coleman-Weinberg condition. Experimental bounds come from lepton flavor violations (especially μ → eγ), the current bound on the Z‧ mass at the CERN Large Hadron Collider, and neutrino oscillations.
Particle model with generalized Poincaré symmetry
Smith, A.
2017-08-01
Using the techniques of nonlinear coset realization with a generalized Poincaré group, we construct a relativistic particle model, invariant under the generalized symmetries, providing a dynamical realization of the B5 algebra.
Mirror symmetry for two parameter models, 2
Candelas, Philip; Katz, S; Morrison, Douglas Robert Ogston; Philip Candelas; Anamaria Font; Sheldon Katz; David R Morrison
1994-01-01
We describe in detail the space of the two K\\"ahler parameters of the Calabi--Yau manifold \\P_4^{(1,1,1,6,9)}[18] by exploiting mirror symmetry. The large complex structure limit of the mirror, which corresponds to the classical large radius limit, is found by studying the monodromy of the periods about the discriminant locus, the boundary of the moduli space corresponding to singular Calabi--Yau manifolds. A symplectic basis of periods is found and the action of the Sp(6,\\Z) generators of the modular group is determined. From the mirror map we compute the instanton expansion of the Yukawa couplings and the generalized N=2 index, arriving at the numbers of instantons of genus zero and genus one of each degree. We also investigate an SL(2,\\Z) symmetry that acts on a boundary of the moduli space.
Chiral symmetry and the constituent quark model
Glozman, L Ya
1995-01-01
New results on baryon structure and spectrum developed in collaboration with Dan Riska [1-4] are reported. The main idea is that beyond the chiral symmetry spontaneous breaking scale light and strange baryons should be considered as systems of three constituent quarks with an effective confining interaction and a chiral interaction that is mediated by the octet of Goldstone bosons (pseudoscalar mesons) between the constituent quarks.
The flavour problem and family symmetry beyond the Standard Model
Dziewit, Bartosz; Richter, Monika; Zając, Sebastian; Zrałek, Marek
2016-01-01
In the frame of two Higgs doublet model we try to explain the lepton masses and mixing matrix elements assuming that neutrinos are Dirac particles. Discrete family symmetry groups, which are subgroups of U(3) up to the 1025 order are considered. Like in the one Higgs Standard Model, we found that discrete family symmetries do not give satisfactory answer for this basic questions in the flavour problem.
A biologically plausible model of human shape symmetry perception.
Poirier, Frédéric J A M; Wilson, Hugh R
2010-01-19
Symmetry is usually computationally expensive to encode reliably, and yet it is relatively effortless to perceive. Here, we extend F. J. A. M. Poirier and H. R. Wilson's (2006) model for shape perception to account for H. R. Wilson and F. Wilkinson's (2002) data on shape symmetry. Because the model already accounts for shape perception, only minimal neural circuitry is required to enable it to encode shape symmetry as well. The model is composed of three main parts: (1) recovery of object position using large-scale non-Fourier V4-like concentric units that respond at the center of concentric contour segments across orientations, (2) around that recovered object center, curvature mechanisms combine multiplicatively the responses of oriented filters to encode object-centric local shape information, with a preference for convexities, and (3) object-centric symmetry mechanisms. Model and human performances are comparable for symmetry perception of shapes. Moreover, with some improvement of edge recovery, the model can encode symmetry axes in natural images such as faces.
EW scale DM models with dark gauge symmetries
Ko, P
2016-01-01
In this talk, I describe a class of electroweak (EW) scale dark matter (DM) models where its stability or longevity are the results of underlying dark gauge symmetries: stable due to unbroken local dark gauge symmetry or topology, or long-lived due to the accidental global symmetry of dark gauge theories. Compared with the usual phenomenological dark matter models (including DM EFT or simplified DM models), DM models with local dark gauge symmetries include dark gauge bosons, dark Higgs bosons and sometimes excited dark matter. And dynamics among these fields are completely fixed by local gauge principle. The idea of singlet portals including the Higgs portal can thermalize these hidden sector dark matter very efficiently, so that these DM could be easily thermal DM. I also discuss the limitation of the usual DM effective field theory or simplified DM models without the full SM gauge symmetry, and emphasize the importance of the full SM gauge symmetry and renormalizability especially for collider searches for...
Abelian symmetries in multi-Higgs-doublet models
Ivanov, Igor P; Vdovin, Evgeny
2012-01-01
Classifying symmetry groups which can be implemented in the scalar sector of a model with $N$ Higgs doublets is a difficult and an unsolved task for $N>2$. Here, we make the first step towards this goal by classifying the Abelian symmetry groups. We describe a strategy that identifies all Abelian groups which can be realized as symmetry groups of the NHDM scalar potential. We give examples of the use of this strategy in 3HDM and 4HDM and prove several statements for arbitrary $N$.
N= 4 Supersymmetric Quantum Mechanical Model: Novel Symmetries
Krishna, S
2016-01-01
We discuss a set of novel discrete symmetry transformations of the N = 4 supersymmetric quantum mechanical model of a charged particle moving on a sphere in the background of Dirac magnetic monopole. The usual five continuous symmetries (and their conserved Noether charges) and two discrete symmetries together provide the physical realizations of the de Rham cohomological operators of differential geometry. We have also exploited the supervariable approach to derive the nilpotent N = 4 SUSY transformations and provided the geometrical interpretation in the language of translational generators along the Grassmannian directions onto (1, 4)-dimensional supermanifold.
𝒩 = 4 supersymmetric quantum mechanical model: Novel symmetries
Krishna, S.
2017-04-01
We discuss a set of novel discrete symmetry transformations of the 𝒩 = 4 supersymmetric quantum mechanical model of a charged particle moving on a sphere in the background of Dirac magnetic monopole. The usual five continuous symmetries (and their conserved Noether charges) and two discrete symmetries together provide the physical realizations of the de Rham cohomological operators of differential geometry. We have also exploited the supervariable approach to derive the nilpotent 𝒩 = 4 SUSY transformations and provided the geometrical interpretation in the language of translational generators along the Grassmannian directions 𝜃α and 𝜃¯α onto (1, 4)-dimensional supermanifold.
Symmetries and deformations in the spherical shell model
Van Isacker, P.; Pittel, S.
2016-02-01
We discuss symmetries of the spherical shell model that make contact with the geometric collective model of Bohr and Mottelson. The most celebrated symmetry of this kind is SU(3), which is the basis of Elliott’s model of rotation. It corresponds to a deformed mean field induced by a quadrupole interaction in a single major oscillator shell N and can be generalized to include several major shells. As such, Elliott’s SU(3) model establishes the link between the spherical shell model and the (quadrupole component of the) geometric collective model. We introduce the analogue symmetry induced by an octupole interaction in two major oscillator shells N-1 and N, leading to an octupole-deformed solution of the spherical shell model. We show that in the limit of large oscillator shells, N\\to ∞ , the algebraic octupole interaction tends to that of the geometric collective model.
Abelian symmetries in multi-Higgs-doublet models
Ivanov, Igor P; Vdovin, Evgeny
2011-01-01
N-Higgs-doublet models (NHDM) are a popular framework to construct electroweak symmetry breaking mechanisms beyond the Standard model. Usually, one builds an NHDM scalar sector which is invariant under a certain symmetry group. Although several such groups have been used, no general analysis of symmetries possible in the NHDM scalar sector exists. Here, we describe a strategy that identifies all abelian groups which are realizable as symmetry groups of the NHDM Higgs potential. We consider both the groups of Higgs-family transformations only and the groups which also contain generalized CP transformations. We illustrate this strategy with the examples of 3HDM and 4HDM and prove several statements for arbitrary N.
The origin of discrete symmetries in F-theory models
2015-01-01
While non-abelian groups are undoubtedly the cornerstone of Grand Unified Theories (GUTs), phenomenology shows that the role of abelian and discrete symmetries is equally important in model building. The latter are the appropriate tool to suppress undesired proton decay operators and various flavour violating interactions, to generate a hierarchical fermion mass spectrum, etc. In F-theory, GUT symmetries are linked to the singularities of the elliptically fibred K3 manifolds; they are of ADE ...
Spontaneous symmetry breaking in the composite-vector-boson model
Energy Technology Data Exchange (ETDEWEB)
Garavaglia, T.
1986-11-15
Spontaneous symmetry breaking is discussed in the Abelian, QED-like, composite-vector-boson model. When the auxiliary vector field has a nonzero vacuum expectation value, a global symmetry, Lorentz invariance, is broken. It is shown that the regularization of the saddle-point conditions for the quantum fluctuation generating functional is consistent only with a spacelike vacuum expectation value for the auxiliary vector field.
Folded Sheet Versus Transparent Sheet Models for Human Symmetry Judgments
Directory of Open Access Journals (Sweden)
Jacques Ninio
2011-07-01
Full Text Available As a contribution to the mysteries of human symmetry perception, reaction time data were collected on the detection of symmetry or repetition violations, in the context of short term visual memory studies. The histograms for reaction time distributions are rather narrow in the case of symmetry judgments. Their analysis was performed in terms of a simple kinetic model of a mental process in two steps, a slow one for the construction of the representation of the images to be compared, and a fast one, in the 50 ms range, for the decision. There was no need for an additional ‘mental rotation’ step. Symmetry seems to facilitate the construction step. I also present here original stimuli showing a color equalization effect across a symmetry axis, and its counterpart in periodic patterns. According to a “folded sheet model”, when a shape is perceived, the brain automatically constructs a mirror-image representation of the shape. Based in part on the reaction time analysis, I present here an alternative “transparent sheet” model in which the brain constructs a single representation, which can be accessed from two sides, thus generating simultaneously a pattern and its mirror-symmetric partner. Filtering processes, implied by current models of symmetry perception could intervene at an early stage, by nucleating the propagation of similar perceptual groupings in the two symmetric images.
Geometric symmetries in light nuclei
Bijker, Roelof
2016-01-01
The algebraic cluster model is is applied to study cluster states in the nuclei 12C and 16O. The observed level sequences can be understood in terms of the underlying discrete symmetry that characterizes the geometrical configuration of the alpha-particles, i.e. an equilateral triangle for 12C, and a regular tetrahedron for 16O. The structure of rotational bands provides a fingerprint of the underlying geometrical configuration of alpha-particles.
A radiative model of quark masses with binary tetrahedral symmetry
Natale, Alexander
2017-01-01
A radiative model of quark and lepton masses utilizing the binary tetrahedral (T‧) flavor symmetry, or horizontal symmetry, is proposed which produces the first two generation of quark masses through their interactions with vector-like quarks that carry charges under an additional U (1). By softly-breaking the T‧ to a residual Z4 through the vector-like quark masses, a CKM mixing angle close to the Cabibbo angle is produced. In order to generate the cobimaximal neutrino oscillation pattern (θ13 ≠ 0 ,θ23 = π / 4 ,δCP = ± π / 2) and protect the horizontal symmetry from arbitrary corrections in the lepton sector, there are automatically two stabilizing symmetries in the dark sector. Several benchmark cases where the correct relic density is achieved in a multi-component DM scenario, as well as the potential collider signatures of the vector-like quarks are discussed.
The Friedberg-Lee symmetry and minimal seesaw model
Energy Technology Data Exchange (ETDEWEB)
He Xiaogang [Center for High Energy Physics, Peking University, Beijing (China); Department of Physics and Center for Theoretical Sciences, National Taiwan University, Taipei, Taiwan (China); Liao Wei, E-mail: liaow@ecust.edu.c [Center for High Energy Physics, Peking University, Beijing (China); Institute of Modern Physics, East China University of Science and Technology, Shanghai (China)
2009-11-02
The Friedberg-Lee (FL) symmetry is generated by a transformation of a fermionic field q to q+xiz. This symmetry puts very restrictive constraints on allowed terms in a Lagrangian. Applying this symmetry to N fermionic fields, we find that the number of independent fields is reduced to N-1 if the fields have gauge interaction or the transformation is a local one. Using this property, we find that a seesaw model originally with three generations of left- and right-handed neutrinos, with the left-handed neutrinos unaffected but the right-handed neutrinos transformed under the local FL translation, is reduced to an effective theory of minimal seesaw which has only two right-handed neutrinos. The symmetry predicts that one of the light neutrino masses must be zero.
The Friedberg-Lee symmetry and minimal seesaw model
He, Xiao-Gang; Liao, Wei
2009-11-01
The Friedberg-Lee (FL) symmetry is generated by a transformation of a fermionic field q to q + ξz. This symmetry puts very restrictive constraints on allowed terms in a Lagrangian. Applying this symmetry to N fermionic fields, we find that the number of independent fields is reduced to N - 1 if the fields have gauge interaction or the transformation is a local one. Using this property, we find that a seesaw model originally with three generations of left- and right-handed neutrinos, with the left-handed neutrinos unaffected but the right-handed neutrinos transformed under the local FL translation, is reduced to an effective theory of minimal seesaw which has only two right-handed neutrinos. The symmetry predicts that one of the light neutrino masses must be zero.
The Friedberg-Lee Symmetry and Minimal Seesaw Model
He, Xiao-Gang
2009-01-01
The Friedberg-Lee (FL) symmetry is generated by a transformation of a fermionic field $q$ to $q + \\xi z$. This symmetry puts very restrictive constraints on allowed terms in a Lagrangian. Applying this symmetry to $N$ fermionic fields, we find that the number of independent fields is reduced to $N-1$ if the fields have gauge interaction or the transformation is a local one. Using this property, we find that a seesaw model originally with three generations of left- and right-handed neutrinos, with the left-handed neutrinos unaffected but the right-handed neutrinos transformed under the local FL translation, is reduced to an effective theory of minimal seesaw which has only two right-handed neutrinos. The symmetry predicts that one of the light neutrino mass must be zero.
Self-Similar Symmetry Model and Cosmic Microwave Background
Directory of Open Access Journals (Sweden)
Tomohide eSonoda
2016-05-01
Full Text Available In this paper, we present the self-similar symmetry (SSS model that describes the hierarchical structure of the universe. The model is based on the concept of self-similarity, which explains the symmetry of the cosmic microwave background (CMB. The approximate length and time scales of the six hierarchies of the universe---grand unification, electroweak unification, the atom, the pulsar, the solar system, and the galactic system---are derived from the SSS model. In addition, the model implies that the electron mass and gravitational constant could vary with the CMB radiation temperature.
An SU(5) grand unified model with discrete flavour symmetries
Hernández, A E Cárcamo; Schmidt, Iván
2014-01-01
We propose a model based on the $SU(5)$ grand unification with an extra $Z_{2}\\otimes Z_{2}^{\\prime}\\otimes Z_{2}^{\\prime \\prime}\\otimes Z_{4}\\otimes Z_{12}$ flavor symmetry, which successfully describes the observed SM fermion mass and mixing pattern. The observed quark mass and mixing pattern is caused by the $Z_{4}$ and $Z_{12}$ symmetries, which are broken at very high scale by the $SU(5)$ scalar singlets $\\sigma $ and $\\chi $, charged respectively under these symmetries and which acquire VEVs at the GUT scale. The light neutrino masses are generated via a type I seesaw mechanism with three heavy Majorana neutrinos. The model has in total 17 effective free parameters, from which 2 are fixed and 15 are fitted to reproduce the experimental values of the 18 physical parameters in the quark and lepton sectors. The model predictions for both quark and lepton sectors are in excellent agreement with the experimental data.
Singh, Manpreet; Vashistha, Arpit; Chaudhary, Manoj; Kaur, Gagandeep
2016-01-01
The purpose of this manuscript is to add some more information in the present scientific literature on these nearly forgotten triangles of surgical importance. The neck is an area that lends itself to anatomical geometry, such as triangles. Many triangles of the neck have been described, and some are well-known, yet, some have been nearly forgotten, i.e., Lesser's triangle, Farabeuf triangle, Pirogoff's triangle, and Beclard's triangle. From the anatomic and surgical point of view, the neck is an amazingly interesting place. It is like a connection where crucial functional units meet and pass. Added surgical landmarks are always helpful to the surgeon while dealing with the neck. Described triangles of neck in this article are always reliable and constant landmarks for head and neck surgeons.
Quantum symmetries induced by phonons in the Hubbard model
Energy Technology Data Exchange (ETDEWEB)
Montorsi, A.; Rasetti, M. (Theory Division, Los Alamos National Laboratories, Los Alamos, New Mexico 87545 (United States) Dipartimento di Fisica and Unita Istituto Nazionale di Fisica della Materia, Politecnico di Torino, I-10129 Torino (Italy))
1994-03-14
We show how the addition of a phonon field to the Hubbard model deforms the [ital superconducting] su(2) part of the global symmetry Lie algebra su(2)[direct product]su(2)/[ital openZ][sub 2], holding at half filling for the customary model, into a [ital quantum] [su(2)][sub [ital q
Graphical Gaussian models with edge and vertex symmetries
DEFF Research Database (Denmark)
Højsgaard, Søren; Lauritzen, Steffen L
2008-01-01
study the properties of such models and derive the necessary algorithms for calculating maximum likelihood estimates. We identify conditions for restrictions on the concentration and correlation matrices being equivalent. This is for example the case when symmetries are generated by permutation...... of variable labels. For such models a particularly simple maximization of the likelihood function is available...
Nonlocal regularization of abelian models with spontaneous symmetry breaking
Clayton, M. A.
2001-01-01
We demonstrate how nonlocal regularization is applied to gauge invariant models with spontaneous symmetry breaking. Motivated by the ability to find a nonlocal BRST invariance that leads to the decoupling of longitudinal gauge bosons from physical amplitudes, we show that the original formulation of the method leads to a nontrivial relationship between the nonlocal form factors that can appear in the model.
Institute of Scientific and Technical Information of China (English)
2005-01-01
<正>We know that the area of any right triangle is half the area of the rectangle which has the same height and the same base with the triangle.The area of rectangle DFEG below is bh.So the area of triangle DFG is 1/2bh. Now we can give a proof of the conclusion that every triangle has half the area of a related rectangle.
Extended superconformal symmetry, Freudenthal triple systems and gauged WZW models
Günaydin, M
1995-01-01
We review the construction of extended ( N=2 and N=4 ) superconformal algebras over triple systems and the gauged WZW models invariant under them. The N=2 superconformal algebras (SCA) realized over Freudenthal triple systems (FTS) admit extension to ``maximal'' N=4 SCA's with SU(2)XSU(2)XU(1) symmetry. A detailed study of the construction and classification of N=2 and N=4 SCA's over Freudenthal triple systems is given. We conclude with a study and classification of gauged WZW models with N=4 superconformal symmetry.
Noether symmetry approach in f(R)-tachyon model
Energy Technology Data Exchange (ETDEWEB)
Jamil, Mubasher, E-mail: mjamil@camp.nust.edu.pk [Center for Advanced Mathematics and Physics (CAMP), National University of Sciences and Technology (NUST), H-12, Islamabad (Pakistan); Mahomed, F.M., E-mail: Fazal.Mahomed@wits.ac.za [Centre for Differential Equations, Continuum Mechanics and Applications, School of Computational and Applied Mathematics, University of the Witwatersrand, Wits 2050 (South Africa); Momeni, D., E-mail: d.momeni@yahoo.com [Department of Physics, Faculty of Sciences, Tarbiat Moa' llem University, Tehran (Iran, Islamic Republic of)
2011-08-26
In this Letter by utilizing the Noether symmetry approach in cosmology, we attempt to find the tachyon potential via the application of this kind of symmetry to a flat Friedmann-Robertson-Walker (FRW) metric. We reduce the system of equations to simpler ones and obtain the general class of the tachyon's potential function and f(R) functions. We have found that the Noether symmetric model results in a power law f(R) and an inverse fourth power potential for the tachyonic field. Further we investigate numerically the cosmological evolution of our model and show explicitly the behavior of the equation of state crossing the cosmological constant boundary.
An Interacting N = 2 Supersymmetric Quantum Mechanical Model: Novel Symmetries
Krishna, S; Malik, R P
2015-01-01
We demonstrate the existence of a set of novel discrete symmetry transformations in the case of an interacting N = 2 supersymmetric quantum mechanical model of a system of an electron moving on a sphere in the background of a magnetic monopole and establish its interpretation in the language of differential geometry. These discrete symmetries are, over and above, the usual three continuous symmetries of the theory which together provide the physical realization of the de Rham cohomological operators of differential geometry. We derive the nilpotent N = 2 SUSY transformations by exploiting our idea of supervariable approach and provide geometrical meaning to these transformations in the language of Grassmannian translational generators on a (1, 2)-dimensional supermanifold on which our N = 2 SUSY quantum mechanical model is generalized. We express the conserved supercharges and the invariance of the Lagrangian in terms of the supervariables, obtained after the imposition of the SUSY invariant restrictions, and...
{ P }{ T } symmetry in quasi-integrable models
Assis, P. E. G.
2016-06-01
Observations of almost stable scattering in nonintegrable models have been reinforced and a framework is proposed to describe quasi-integrability in terms of { P }{ T } symmetry. This new mechanism can be used to regard { P }{ T } symmetry in classical field theories as a guiding principle to also select relevant systems when it comes to integrability properties. It turns out that the if a deformed Lax pair is invariant under this symmetry, corresponding to the unbroken { P }{ T }-symmetric regime, quasi-integrable excitations are produced with asymptotically conserved charges. A generic nonlinear field equation is used in order to verify the validity of the assumptions but results for a specific non-integrable class of models are also presented. A set of quasi-integrable excitations is investigated and shown to have spectral functions with appropriate properties, which might lead to the determination of the almost conserved charges.
E6 inspired supersymmetric models with exact custodial symmetry
Nevzorov, Roman
2013-01-01
The breakdown of E6 gauge symmetry at high energies may lead to supersymmetric models based on the standard model gauge group together with extra U(1)ψ and U(1)χ gauge symmetries. To ensure anomaly cancellation the particle content of these E6 inspired models involves extra exotic states that generically give rise to nondiagonal flavor transitions and rapid proton decay. We argue that a single discrete Z˜2H symmetry can be used to forbid tree-level flavor changing transitions, as well as the most dangerous baryon and lepton number violating operators. We present 5D and 6D orbifold grand unified theory constructions that lead to the E6 inspired supersymmetric models of this type. The breakdown of U(1)ψ and U(1)χ gauge symmetries that preserves E6 matter parity assignment guarantees that ordinary quarks and leptons and their superpartners, as well as the exotic states which originate from 27 representations of E6, survive to low energies. These E6 inspired models contain two dark matter candidates and must also include additional TeV scale vectorlike lepton or vectorlike down-type quark states to render the lightest exotic quark unstable. We examine gauge coupling unification in these models and discuss their implications for collider phenomenology and cosmology.
E6 inspired SUSY models with exact custodial symmetry
Nevzorov, R
2012-01-01
The breakdown of E_6 gauge symmetry at high energies may result in supersymmetric (SUSY) models based on the Standard Model (SM) gauge group together with extra U(1)_{\\psi} and U(1)_{\\chi} gauge symmetries. To ensure anomaly cancellation the particle content of these E_6 inspired models involves extra exotic states that can give rise to non--diagonal flavour transitions and rapid proton decay. We argue that a single discrete \\tilde{Z}^{H}_2 symmetry can be used to forbid tree--level flavor-changing transitions and the most dangerous baryon and lepton number violating operators. We present 5D and 6D orbifold GUT models that can lead to the E_6 inspired SUSY models of this type. The breakdown of U(1)_{\\psi} and U(1)_{\\chi} gauge symmetries that preserves E_6 matter parity assignment guarantees that the exotic states which originate from 27_i representations of E_6 as well as ordinary quark and lepton states survive to low energies. The considered E_6 inspired models contain at least two dark-matter candidates a...
On exact triangles consisting of stable vector bundles on tori
Kobayashi, Kazushi
2016-01-01
In this paper, we consider the exact triangles consisting of stable holomorphic vector bundles on one-dimensional complex tori, and discuss their relations with the corresponding Fukaya category via the homological mirror symmetry.
Discrete symmetry breaking beyond the standard model
Dekens, Wouter Gerard
2015-01-01
The current knowledge of elementary particles and their interactions is summarized in the Standard Model of particle physics. Practically all the predictions of this model, that have been tested, were confirmed experimentally. Nonetheless, there are phenomena which the model cannot explain. For
The fundamental role of symmetry in nuclear models
Energy Technology Data Exchange (ETDEWEB)
Rowe, D. J. [Department of Physics, University of Toronto, Toronto, Ontario M5S 1A7 (Canada)
2013-06-10
The purpose of these lectures is to illustrate how symmetry and pattern recognition play essential roles in the progression from experimental observation to an understanding of nuclear phenomena in terms of interacting neutrons and protons. We do not discuss weak interactions nor relativistic and sub-nucleon degrees of freedom. The explicit use of symmetry and the power of algebraic methods, in combination with analytical and geometrical methods are illustrated by their use in deriving a shell-model description of nuclear rotational dynamics and the structure of deformed nuclei.
Flavour symmetries in a renormalizable SO(10) model
Ferreira, P M; Jurčiukonis, D; Lavoura, L
2015-01-01
In the context of a renormalizable supersymmetric SO(10) Grand Unified Theory, we consider the fermion mass matrices generated by the Yukawa couplings to a $\\mathbf{10} \\oplus \\mathbf{120} \\oplus \\overline{\\mathbf{126}}$ representation of scalars. We perform a complete investigation of the possibilities of imposing flavour symmetries in this scenario; the purpose is to reduce the number of Yukawa coupling constants in order to identify potentially predictive models. We have found that there are only 14 inequivalent cases of Yukawa coupling matrices, out of which 13 cases are generated by $Z_n$ symmetries, with suitable $n$, and one case is generated by a $Z_2 \\times Z_2$ symmetry. A numerical analysis of the 14 cases reveals that only two of them---dubbed A and B in the present paper---allow good fits to the experimentally known fermion masses and mixings.
Ambiguities and Symmetry Relations in a Free Fermion Model
Battistel, O A
1999-01-01
We present a systematic study of one, two and three point functions of vector, axial-vector, scalar and pseudoscalar densities constructed in a free fermion model. The divergent content of the amplitudes are left in the form of (external momenta independent) 4-D integrals for which an appropriate regulating function is only implicitly assumed, and the integrals are not evaluated at any step of the calculation. The ambiguities and Symmetries Violations, in all cases, are shown to be associated with coefficients involving three relations between divergent integrals of the same degree of divergence. Setting these coefficients to zero is mandatory, e.g., for preserving gauge symmetry in QED. The implications for the ambiguities and symmetry violations are investigated. The results emerging from this alternative approach allow us to conclude that the traditional method used to establish the triangular anomalies could be questionable.
Radiative breaking of conformal symmetry in the Standard Model
Arbuzov, A. B.; Nazmitdinov, R. G.; Pavlov, A. E.; Pervushin, V. N.; Zakharov, A. F.
2016-02-01
Radiative mechanism of conformal symmetry breaking in a comformal-invariant version of the Standard Model is considered. The Coleman-Weinberg mechanism of dimensional transmutation in this system gives rise to finite vacuum expectation values and, consequently, masses of scalar and spinor fields. A natural bootstrap between the energy scales of the top quark and Higgs boson is suggested.
Leptogenesis in a model with Friedberg-Lee symmetry
Araki, Takeshi; Geng, C. Q.
2009-10-01
We study the matter-antimatter asymmetry through the leptogenesis mechanism in a specific model with the Friedberg-Lee (FL) symmetry. We relate the leptogenesis with the CP violating Dirac and Majorana phases in the Maki-Nakagawa-Sakata leptonic mixing matrix and illustrate the net baryon asymmetry of the universe in terms of these phases.
Leptogenesis in a model with Friedberg-Lee symmetry
Energy Technology Data Exchange (ETDEWEB)
Araki, Takeshi [Department of Physics, National Tsing Hua University, Hsinchu, 300, Taiwan (China)], E-mail: araki@phys.nthu.edu.tw; Geng, C.Q. [Department of Physics, National Tsing Hua University, Hsinchu, 300, Taiwan (China)], E-mail: geng@phys.nthu.edu.tw
2009-10-05
We study the matter-antimatter asymmetry through the leptogenesis mechanism in a specific model with the Friedberg-Lee (FL) symmetry. We relate the leptogenesis with the CP violating Dirac and Majorana phases in the Maki-Nakagawa-Sakata leptonic mixing matrix and illustrate the net baryon asymmetry of the universe in terms of these phases.
A review on symmetries for certain Aedes aegypti models
Freire, Igor Leite; Torrisi, Mariano
2015-04-01
We summarize our results related with mathematical modeling of Aedes aegypti and its Lie symmetries. Moreover, some explicit, group-invariant solutions are also shown. Weak equivalence transformations of more general reaction diffusion systems are also considered. New classes of solutions are obtained.
Leptogenesis in model with Friedberg-Lee symmetry
Araki, Takeshi
2009-01-01
We study the matter-antimatter asymmetry through the leptogenesis mechanism in the model with the Friedberg-Lee (FL) symmetry. We relate the leptogenesis with the CP violating Dirac and Majorana phases in the Maki-Nakagawa-Sakata leptonic mixing matrix and illustrate the net baryon asymmetry of the universe in terms of these phases.
The Calogero Model and the Virasoro Symmetry
Bergshoeff, E.; Vasiliev, M.
1995-01-01
We construct new realizations of the Virasoro algebra inspired by the Calogero model. The Virasoro algebra we find acts as a kind of spectrum-generating algebra of the Calogero model. Furthermore, we present the superextension of these results and introduce a class of higher spin extensions of the V
Conformal symmetry vs. chiral symmetry breaking in the SU(3) sextet model
Drach, Vincent; Hietanen, Ari; Pica, Claudio; Sannino, Francesco
2015-01-01
We present new results for the SU(3) "sextet model" with two flavors transforming according to the two-index symmetric representation of the gauge group. The simulations are performed using unimproved Wilson fermions. We measure the meson and baryon spectrum of the theory for multiple bare quark masses at two different lattice spacings. To address the pressing issue of whether the model is inside or below the conformal window, we compare the spectrum to the expectations for a theory with spontaneous chiral symmetry breaking and to those of an IR conformal theory. Regardless of the answer (conformal or chirally broken), the theory is a cornerstone in our understanding of near-conformal and composite dynamics, ranging from Technicolor models to unparticle physics. It is also interesting for the composite dynamics of vector-like singlets with respect to the Standard Model interactions.
Chiral Redox-Active Isosceles Triangles.
Nalluri, Siva Krishna Mohan; Liu, Zhichang; Wu, Yilei; Hermann, Keith R; Samanta, Avik; Kim, Dong Jun; Krzyaniak, Matthew D; Wasielewski, Michael R; Stoddart, J Fraser
2016-05-11
Designing small-molecule organic redox-active materials, with potential applications in energy storage, has received considerable interest of late. Herein, we report on the synthesis, characterization, and application of two rigid chiral triangles, each of which consist of non-identical pyromellitic diimide (PMDI) and naphthalene diimide (NDI)-based redox-active units. (1)H and (13)C NMR spectroscopic investigations in solution confirm the lower symmetry (C2 point group) associated with these two isosceles triangles. Single-crystal X-ray diffraction analyses reveal their rigid triangular prism-like geometries. Unlike previously investigated equilateral triangle containing three identical NDI subunits, both isosceles triangles do not choose to form one-dimensional supramolecular nanotubes by dint of [C-H···O] interaction-driven columnar stacking. The rigid isosceles triangle, composed of one NDI and two PMDI subunits, forms-in the presence of N,N-dimethylformamide-two different types of intermolecular NDI-NDI and NDI-PMDI π-π stacked dimers with opposite helicities in the solid state. Cyclic voltammetry reveals that both isosceles triangles can accept reversibly up to six electrons. Continuous-wave electron paramagnetic resonance and electron-nuclear double-resonance spectroscopic investigations, supported by density functional theory calculations, on the single-electron reduced radical anions of the isosceles triangles confirm the selective sharing of unpaired electrons among adjacent redox-active NDI subunit(s) within both molecules. The isosceles triangles have been employed as electrode-active materials in organic rechargeable lithium-ion batteries. The evaluation of the structure-performance relationships of this series of diimide-based triangles reveals that the increase in the number of NDI subunits, replacing PMDI ones, within the molecules improves the electrochemical cell performance of the batteries.
Viability of minimal left-right models with discrete symmetries
Dekens, Wouter; Boer, Daniël
2014-12-01
We provide a systematic study of minimal left-right models that are invariant under P, C, and/or CP transformations. Due to the high amount of symmetry such models are quite predictive in the amount and pattern of CP violation they can produce or accommodate at lower energies. Using current experimental constraints some of the models can already be excluded. For this purpose we provide an overview of the experimental constraints on the different left-right symmetric models, considering bounds from colliders, meson-mixing and low-energy observables, such as beta decay and electric dipole moments. The features of the various Yukawa and Higgs sectors are discussed in detail. In particular, we give the Higgs potentials for each case, discuss the possible vacua and investigate the amount of fine-tuning present in these potentials. It turns out that all left-right models with P, C, and/or CP symmetry have a high degree of fine-tuning, unless supplemented with mechanisms to suppress certain parameters. The models that are symmetric under both P and C are not in accordance with present observations, whereas the models with either P, C, or CP symmetry cannot be excluded by data yet. To further constrain and discriminate between the models measurements of B-meson observables at LHCb and B-factories will be especially important, while measurements of the EDMs of light nuclei in particular could provide complementary tests of the LRMs.
Viability of minimal left–right models with discrete symmetries
Energy Technology Data Exchange (ETDEWEB)
Dekens, Wouter, E-mail: w.g.dekens@rug.nl; Boer, Daniël
2014-12-15
We provide a systematic study of minimal left–right models that are invariant under P, C, and/or CP transformations. Due to the high amount of symmetry such models are quite predictive in the amount and pattern of CP violation they can produce or accommodate at lower energies. Using current experimental constraints some of the models can already be excluded. For this purpose we provide an overview of the experimental constraints on the different left–right symmetric models, considering bounds from colliders, meson-mixing and low-energy observables, such as beta decay and electric dipole moments. The features of the various Yukawa and Higgs sectors are discussed in detail. In particular, we give the Higgs potentials for each case, discuss the possible vacua and investigate the amount of fine-tuning present in these potentials. It turns out that all left–right models with P, C, and/or CP symmetry have a high degree of fine-tuning, unless supplemented with mechanisms to suppress certain parameters. The models that are symmetric under both P and C are not in accordance with present observations, whereas the models with either P, C, or CP symmetry cannot be excluded by data yet. To further constrain and discriminate between the models measurements of B-meson observables at LHCb and B-factories will be especially important, while measurements of the EDMs of light nuclei in particular could provide complementary tests of the LRMs.
Noether Symmetries Quantization and Superintegrability of Biological Models
Directory of Open Access Journals (Sweden)
Maria Clara Nucci
2016-12-01
Full Text Available It is shown that quantization and superintegrability are not concepts that are inherent to classical Physics alone. Indeed, one may quantize and also detect superintegrability of biological models by means of Noether symmetries. We exemplify the method by using a mathematical model that was proposed by Basener and Ross (2005, and that describes the dynamics of growth and sudden decrease in the population of Easter Island.
Intrinsic Conformal Symmetries in Szekeres models
Apostolopoulos, Pantelis S
2016-01-01
We show that Spatially Inhomogeneous (SI) and Irrotational dust models admit a \\emph{6-dimensional algebra }of \\emph{Intrinsic Conformal Vector Fields} (ICVFs) $\\mathbf{X}_{\\alpha }$ satisfying $p_{a}^{c}p_{b}^{d}\\mathcal{L}_{\\mathbf{X}_{\\alpha }}p_{cd}=2\\phi (\\mathbf{X}_{\\alpha })p_{ab}$ where $p_{ab} $ is the associated metric of the 2d distribution $\\mathcal{X}$ normal to the fluid velocity $u^{a}$ and the radial unit spacelike vector field $x^{a}$. The Intrinsic Conformal (IC) algebra is determined for each of the curvature value $\\epsilon $ that characterizes the structure of the screen space $\\mathcal{X}$. In addition the conformal flatness of the hypersurfaces $\\mathbf{u}=\\mathbf{0}$ indicates the existence of a \\emph{10-dimensional algebra} of ICVFs of the 3d metric $h_{ab}$. We illustrate this expectation and propose a method to derive them by giving explicitly the \\emph{7 proper} ICVFs of the Lema\\^{\\i}tre-Tolman-Bondi (LTB) model which represents the simplest subclass within the Szekeres family.
The Fibonacci partition triangles
Fahr, Philipp
2011-01-01
In two previous papers we have presented partition formulae for the Fibonacci numbers motivated by the appearance of the Fibonacci numbers in the representation theory of the 3-Kronecker quiver and its universal cover, the 3-regular tree. Here we show that the basic information can be rearranged in two triangles. They are quite similar to the Pascal triangle of the binomial coefficients, but in contrast to the additivity rule for the Pascal triangle, we now deal with additivity along hooks, or, equivalently, with additive functions for valued translation quivers. As for the Pascal triangle, we see that the numbers in these Fibonacci partition triangles are given by evaluating polynomials. We show that the two triangles can be obtained from each other by looking at differences of numbers, it is sufficient to take differences along arrows and knight's moves.
Symmetry Energy Effects in a Statistical Multifragmentation Model
Institute of Scientific and Technical Information of China (English)
ZHANG Lei; GAO Yuan1; ZHANG Hong-Fei; CHEN Xi-Meng; Yu Mei-Ling; LI Jun-Qing
2011-01-01
The symmetry energy effects on the nuclear disintegration mechanisms of the neutron-rich system (A0 = 200, Z0 = 78) are studied in the framework of the statistical multifragmentation model (SMM) within its micro-canonical ensemble. A modified symmetry energy term with consideration of the volume and surface asymmetry is adopted instead of the original invariable value in the standard SMM model. The results indicate that as the volume and surface asymmetries are considered, the neutron-rich system translates to a fission-like process from evaporation earlier than the original standard SMM model at lower excitation energies, and its mass distribution has larger probabilities in the medium-heavy nuclei range so that the system breaks up more averagely. When the excitation energy becomes higher, the volume and surface asymmetry lead to a smaller average multiplicity.%The symmetry energy effects on the nuclear disintegration mechanisms of the neutron-rich system (A0 =200,Z0 =78) are studied in the framework of the statistical multifragmentation model (SMM) within its micro-canonical ensemble.A modified symmetry energy term with consideration of the volume and surface asymmetry is adopted instead of the original invariable value in the standard SMM model.The results indicate that as the volume and surface asymmetries are considered,the neutron-rich system translates to a fission-like process from evaporation earlier than the original standard SMM model at lower excitation energies,and its mass distribution has larger probabilities in the medium-heavy nuclei range so that the system breaks up more averagely.When the excitation energy becomes higher,the volume and surface asymmetry lead to a smaller average multiplicity.
Beyond the standard gauging: gauge symmetries of Dirac sigma models
Chatzistavrakidis, Athanasios; Deser, Andreas; Jonke, Larisa; Strobl, Thomas
2016-08-01
In this paper we study the general conditions that have to be met for a gauged extension of a two-dimensional bosonic σ-model to exist. In an inversion of the usual approach of identifying a global symmetry and then promoting it to a local one, we focus directly on the gauge symmetries of the theory. This allows for action functionals which are gauge invariant for rather general background fields in the sense that their invariance conditions are milder than the usual case. In particular, the vector fields that control the gauging need not be Killing. The relaxation of isometry for the background fields is controlled by two connections on a Lie algebroid L in which the gauge fields take values, in a generalization of the common Lie-algebraic picture. Here we show that these connections can always be determined when L is a Dirac structure in the H-twisted Courant algebroid. This also leads us to a derivation of the general form for the gauge symmetries of a wide class of two-dimensional topological field theories called Dirac σ-models, which interpolate between the G/G Wess-Zumino-Witten model and the (Wess-Zumino-term twisted) Poisson sigma model.
Dimer Models from Mirror Symmetry and Quivering Amoebae
Feng, B; Kennaway, K D; Vafa, C; Feng, Bo; He, Yang-Hui; Kennaway, Kristian D.; Vafa, Cumrun
2005-01-01
Dimer models are 2-dimensional combinatorial systems that have been shown to encode the gauge groups, matter content and tree-level superpotential of the world-volume quiver gauge theories obtained by placing D3-branes at the tip of a singular toric Calabi-Yau cone. In particular the dimer graph is dual to the quiver graph. However, the string theoretic explanation of this was unclear. In this paper we use mirror symmetry to shed light on this: the dimer models live on a T^2 subspace of the T^3 fiber that is involved in mirror symmetry and is wrapped by D6-branes. These D6-branes are mirror to the D3-branes at the singular point, and geometrically encode the same quiver theory on their world-volume.
Synchronization in Triangled Complex Networks
Institute of Scientific and Technical Information of China (English)
LU Xin-Biao; LI Xiang; WANG Xiao-Fan
2006-01-01
Using a tunable clustering coefficient model withoutchanging the degree distribution, we investigate the effect of clustering coefficient on synchronization of networks with both unweighted and weighted couplings. For several typical categories of complex networks, the more triangles are in the networks, the worse the synchronizability of the networks is.
Symmetry-Based Tight Binding Modeling of Halide Perovskite Semiconductors
Boyer-Richard, Soline; Katan, Claudine; Traoré, Boubacar; Scholz, Reinhard; Jancu, Jean-Marc; Even, Jacky
2016-01-01
International audience; On the basis of a general symmetry analysis, this paper presents an empirical tight-binding (TB) model for the reference Pm-3m perovskite cubic phase of halide perovskites of general formula ABX3. The TB electronic band diagram, with and without spin orbit coupling effect of MAPbI3 has been determined based on state of the art density functional theory results including many body corrections (DFT+GW). It affords access to various properties, including distorted structu...
Trivial symmetries in a 3D topological torsion model of gravity
Banerjee, Rabin; 10.1088/1742-6596/405/1/012028
2012-01-01
We study the gauge symmetries in a Mielke-Baekler type model of gravity in 2+1 dimensions. The model is built in a Poincare gauge theory framework where localisation of Poincare symmetries lead to gravity. However, explicit construction of gauge symmetries in the model through a Hamiltonian procedure yields an apparently different set of symmetries, as has been noted by various authors. Here, we show that the two sets of symmetries are actually equivalent in a canonical sense, their difference being just a set of trivial symmetries.
Nuclear symmetry energy in a modified quark meson coupling model
Mishra, R N; Panda, P K; Barik, N; Frederico, T
2015-01-01
We study nuclear symmetry energy and the thermodynamic instabilities of asymmetric nuclear matter in a self-consistent manner by using a modified quark-meson coupling model where the confining interaction for quarks inside a nucleon is represented by a phenomenologically averaged potential in an equally mixed scalar-vector harmonic form. The nucleon-nucleon interaction in nuclear matter is then realized by introducing additional quark couplings to $\\sigma$, $\\omega$, and $\\rho$ mesons through mean-field approximations. We find an analytic expression for the symmetry energy ${\\cal E}_{sym}$ as a function of its slope $L$. Our result establishes a linear correlation between $L$ and ${\\cal E}_{sym}$. We also analyze the constraint on neutron star radii in $(pn)$ matter with $\\beta$ equilibrium.
Adiabatic approximation for the Rabi model with broken inversion symmetry
Shen, Li-Tuo; Yang, Zhen-Biao; Wu, Huai-Zhi
2017-01-01
We study the properties and behavior of the Rabi model with broken inversion symmetry. Using an adiabatic approximation approach, we explore the high-frequency qubit and oscillator regimes, and obtain analytical solutions for the qubit-oscillator system. We demonstrate that, due to broken inversion symmetry, the positions of two potentials and zero-point energies in the oscillators become asymmetric and have a quadratic dependence on the mean dipole moments within the high-frequency oscillator regime. Furthermore, we find that there is a critical point above which the qubit-oscillator system becomes unstable, and the position of this critical point has a quadratic dependence on the mean dipole moments within the high-frequency qubit regime. Finally, we verify this critical point based on the method of semiclassical approximation.
Chaos, solitons and fractals in hidden symmetry models
Energy Technology Data Exchange (ETDEWEB)
Maccari, Attilio [Technical Institute ' G. Cardano' , Piazza della Resistenza 1, 00015 Monterotondo, Rome (Italy)] e-mail: solitone@yahoo.it
2006-01-01
A spontaneous symmetry breaking (or hidden symmetry) model is reduced to a system nonlinear evolution equations integrable via an appropriate change of variables, by means of the asymptotic perturbation (AP) method, based on spatio-temporal rescaling and Fourier expansion. It is demonstrated the existence of coherent solutions as well as chaotic and fractal patterns, due to the possibility of selecting appropriately some arbitrary functions. Dromion, lump, breather, instanton and ring soliton solutions are derived and the interaction between these coherent solutions are completely elastic, because they pass through each other and preserve their shapes and velocities, the only change being a phase shift. Finally, one can construct lower dimensional chaotic patterns such as chaotic-chaotic patterns, periodic-chaotic patterns, chaotic soliton and dromion patterns. In a similar way, fractal dromion and lump patterns as well as stochastic fractal excitations can appear in the solution.
Discrete symmetries and model-independent patterns of lepton mixing
Hernandez, D
2012-01-01
In the context of discrete flavor symmetries, we elaborate a method that allows one to obtain relations between the mixing parameters in a model-independent way. Under very general conditions, we show that flavor groups of the von Dyck type, that are not necessarily finite, determine the absolute values of the entries of one column of the mixing matrix. We apply our formalism to finite subgroups of the infinite von Dyck groups, such as the modular groups, and find cases that yield an excellent agreement with the best fit values for the mixing angles. We explore the Klein group as the residual symmetry of the neutrino sector and explain the permutation property that appears between the elements of the mixing matrix in this case.
Discrete symmetries and model-independent patterns of lepton mixing
Hernandez, D.; Smirnov, A. Yu.
2013-03-01
In the context of discrete flavor symmetries, we elaborate a method that allows one to obtain relations between the mixing parameters in a model-independent way. Under very general conditions, we show that flavor groups of the von Dyck type, that are not necessarily finite, determine the absolute values of the entries of one column of the mixing matrix. We apply our formalism to finite subgroups of the infinite von Dyck groups, such as the modular groups, and find cases that yield an excellent agreement with the best fit values for the mixing angles. We explore the Klein group as the residual symmetry of the neutrino sector and explain the permutation property that appears between the elements of the mixing matrix in this case.
Triangle and GA Methods for UAVs Jamming
Directory of Open Access Journals (Sweden)
Yu Zhang
2014-01-01
Full Text Available We focus on how to jam UAVs network efficiently. The system model is described and the problem is formulated. Based on two properties and a theorem which helps to decide good location for a jammer, we present the Triangle method to find good locations for jammers. The Triangle method is easy to understand and has overall computational complexity of ON2. We also present a genetic algorithm- (GA- based jamming method, which has computational complex of OLMN2. New chromosome, mutation, and crossover operations are redefined for the GA method. The simulation shows that Triangle and GA methods perform better than Random method. If the ratio of jammers’ number to UAVs’ number is low (lower than 1/5 in this paper, GA method does better than Triangle method. Otherwise, Triangle method performs better.
Koyunkaya, Melike Yigit; Kastberg, Signe; Quinlan, James; Edwards, Michael Todd; Keiser, Jane
2015-01-01
Right triangles play a significant role in mathematics. In this favorite lesson, the authors help students understand variant and invariant properties by considering relationships among angle measures and side lengths in right triangles. Students explore these relationships using interactive mathematics software, changing one angle and observing…
Blanke, Monika
2016-01-01
Motivated by the recently improved results from the Fermilab Lattice and MILC Collaborations on the hadronic matrix elements entering $\\Delta M_{s,d}$ in $B_{s,d}^0-\\bar B_{s,d}^0$ mixing, we determine the Universal Unitarity Triangle (UUT) in models with Constrained Minimal Flavour Violation (CMFV). Of particular importance are the very precise determinations of the ratio $|V_{ub}|/|V_{cb}|=0.0864\\pm0.0025$ and of the angle $\\gamma=(62.7\\pm 2.1)^\\circ$. They follow in this framework from the experimental values of $\\Delta M_{d}/\\Delta M_s$ and of the CP-asymmetry $S_{\\psi K_S}$. As in CMFV models the new contributions to meson mixings can be described by a single flavour-universal variable $S(v)$, we next determine the CKM matrix elements $|V_{ts}|$, $|V_{td}|$, $|V_{cb}|$ and $|V_{ub}|$ as functions of $S(v)$ using the experimental value of $\\Delta M_s$ as input. The lower bound on $S(v)$ in these models, derived by us in 2006, implies then upper bounds on these four CKM elements and on the CP-violating par...
Beyond the standard gauging: gauge symmetries of Dirac Sigma Models
Chatzistavrakidis, Athanasios; Jonke, Larisa; Strobl, Thomas
2016-01-01
In this paper we study the general conditions that have to be met for a gauged extension of a two-dimensional bosonic sigma-model to exist. In an inversion of the usual approach of identifying a global symmetry and then promoting it to a local one, we focus directly on the gauge symmetries of the theory. This allows for action functionals which are gauge invariant for rather general background fields in the sense that their invariance conditions are milder than the usual case. In particular, the vector fields that control the gauging need not be Killing. The relaxation of isometry for the background fields is controlled by two connections on a Lie algebroid L in which the gauge fields take values, in a generalization of the common Lie-algebraic picture. Here we show that these connections can always be determined when L is a Dirac structure in the H-twisted Courant algebroid. This also leads us to a derivation of the general form for the gauge symmetries of a wide class of two-dimensional topological field th...
Realisation of chiral symmetry in the domain model of QCD
Kalloniatis, Alexander C
2003-01-01
The domain model for the QCD vacuum has previously been developed and shown to exhibit confinement of quarks and strong correlation of the local chirality of quark modes and duality of the background domain-like gluon field. Quark fluctuations satisfy a chirality violating boundary conditions parametrized by a random chiral angle $\\alpha_j$ on the $j-th$ domain. The free energy of an ensemble of $N\\to\\infty$ domains depends on $\\{\\alpha_j, j=1... N\\}$ through the logarithm of the quark determinant. Its parity odd part is given by the axial anomaly. The anomaly contribution to the free energy suppresses continuous axial U(1) degeneracy in the ground state, leaving only a residual axial Z(2) symmetry. This discrete symmetry and flavour $SU(N_f)_L\\times SU(N_f)_R$ chiral symmetry in turn are spontaneously broken with a quark condensate arising due to the asymmetry of the spectrum of Dirac operator. In order to illustrate the splitting between the $\\eta'$ from octet pseudoscalar mesons realised in the domain mode...
Cosmological constraints on spontaneous R-symmetry breaking models
Energy Technology Data Exchange (ETDEWEB)
Hamada, Yuta; Kobayashi, Tatsuo [Kyoto Univ. (Japan). Dept. of Physics; Kamada, Kohei [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Ookouchi, Yutaka [Kyoto Univ. (Japan). Dept. of Physics; Kyoto Univ. (Japan). The Hakubi Center for Advanced Research and Dept. of Physics
2012-11-15
We study general constraints on spontaneous R-symmetry breaking models coming from the cosmological effects of the pseudo Nambu-Goldstone bosons, R-axions. They are substantially produced in the early Universe and may cause several cosmological problems. We focus on relatively long-lived R-axions and find that in a wide range of parameter space, models are severely constrained. In particular, R-axions with mass less than 1 MeV are generally ruled out for relatively high reheating temperature, T{sub R}>10 GeV.
Classification of finite reparametrization symmetry groups in the three-Higgs-doublet model
Ivanov, I P
2012-01-01
Symmetries play a crucial role in electroweak symmetry breaking models with non-minimal Higgs content. Within each class of these models, it is desirable to know which symmetry groups can be implemented via the scalar sector. In N-Higgs-doublet models, this classification problem was solved only for N=2 doublets. Very recently, we suggested a method to classify all realizable finite symmetry groups of Higgs-family transformations in the three-Higgs-doublet model (3HDM). Here, we present this classification in all detail together with an introduction to the theory of solvable groups, which play the key role in our derivation. We also consider generalized-CP symmetries, and discuss the interplay between Higgs-family symmetries and CP-conservation. In particular, we prove that presence of the $Z_4$ symmetry guarantees the explicit CP-conservation of the potential. This work completes classification of finite reparametrization symmetry groups in 3HDM.
Classification of finite reparametrization symmetry groups in the three-Higgs-doublet model
Energy Technology Data Exchange (ETDEWEB)
Ivanov, Igor P. [Universite de Liege, IFPA, Liege (Belgium); Sobolev Institute of Mathematics, Novosibirsk (Russian Federation); Vdovin, E. [Sobolev Institute of Mathematics, Novosibirsk (Russian Federation)
2013-02-15
Symmetries play a crucial role in electroweak symmetry breaking models with non-minimal Higgs content. Within each class of these models, it is desirable to know which symmetry groups can be implemented via the scalar sector. In N-Higgs-doublet models, this classification problem was solved only for N=2 doublets. Very recently, we suggested a method to classify all realizable finite symmetry groups of Higgs-family transformations in the three-Higgs-doublet model (3HDM). Here, we present this classification in all detail together with an introduction to the theory of solvable groups, which play the key role in our derivation. We also consider generalized-CP symmetries, and discuss the interplay between Higgs-family symmetries and CP-conservation. In particular, we prove that presence of the Z{sub 4} symmetry guarantees the explicit CP-conservation of the potential. This work completes classification of finite reparametrization symmetry groups in 3HDM. (orig.)
Classification of finite reparametrization symmetry groups in the three-Higgs-doublet model
Ivanov, Igor P.; Vdovin, E.
2013-02-01
Symmetries play a crucial role in electroweak symmetry breaking models with non-minimal Higgs content. Within each class of these models, it is desirable to know which symmetry groups can be implemented via the scalar sector. In N-Higgs-doublet models, this classification problem was solved only for N=2 doublets. Very recently, we suggested a method to classify all realizable finite symmetry groups of Higgs-family transformations in the three-Higgs-doublet model (3HDM). Here, we present this classification in all detail together with an introduction to the theory of solvable groups, which play the key role in our derivation. We also consider generalized- CP symmetries, and discuss the interplay between Higgs-family symmetries and CP-conservation. In particular, we prove that presence of the ℤ4 symmetry guarantees the explicit CP-conservation of the potential. This work completes classification of finite reparametrization symmetry groups in 3HDM.
A model capturing novel strand symmetries in bacterial DNA
Energy Technology Data Exchange (ETDEWEB)
Sobottka, Marcelo, E-mail: sobottka@mtm.ufsc.br [Departamento de Matematica, Universidade Federal de Santa Catarina (Brazil); Hart, Andrew G., E-mail: ahart@dim.uchile.cl [Departamento de Ingenieria Matematica and Centro de Modelamiento Matematico, Universidad de Chile (Chile)
2011-07-15
Highlights: {yields} We propose a simple stochastic model to construct primitive DNA sequences. {yields} The model provide an explanation for Chargaff's second parity rule in primitive DNA sequences. {yields} The model is also used to predict a novel type of strand symmetry in primitive DNA sequences. {yields} We extend the results for bacterial DNA sequences and compare distributional properties intrinsic to the model to statistical estimates from 1049 bacterial genomes. {yields} We find out statistical evidences that the novel type of strand symmetry holds for bacterial DNA sequences. -- Abstract: Chargaff's second parity rule for short oligonucleotides states that the frequency of any short nucleotide sequence on a strand is approximately equal to the frequency of its reverse complement on the same strand. Recent studies have shown that, with the exception of organellar DNA, this parity rule generally holds for double-stranded DNA genomes and fails to hold for single-stranded genomes. While Chargaff's first parity rule is fully explained by the Watson-Crick pairing in the DNA double helix, a definitive explanation for the second parity rule has not yet been determined. In this work, we propose a model based on a hidden Markov process for approximating the distributional structure of primitive DNA sequences. Then, we use the model to provide another possible theoretical explanation for Chargaff's second parity rule, and to predict novel distributional aspects of bacterial DNA sequences.
Davies, T.; Fry, H.; Wilson, A.; Palmisano, A; Altaweel, M.; Radner, K.
2014-01-01
We present a spatial interaction entropy maximizing and structural dynamics model of settlements from the Middle Bronze (MBA) and Iron Ages (IA) in the Khabur Triangle (KT) region within Syria. The model addresses factors that make locations attractive for trade and settlement, affecting settlement growth and change. We explore why some sites become relatively major settlements, while others diminish in the periods discussed. We assess how political and geographic constraints affect regional ...
Sikora, W
2011-01-01
The evacuation of football stadium scenarios are discussed as model realizing ordered states, described as movements of individuals according to fields of displacements, calculated correspondingly to given scenario. The symmetry of the evacuation space is taken into account in calculation of displacements field - the displacements related to every point of this space are presented in the coordinate frame in the best way adapted to given symmetry space group, which the set of basic vectors of irreducible representation of given group is. The speeds of individuals at every point in the presented model have the same quantity. As the results the times of evacuation and average forces acting on individuals during the evacuation are given. Both parameters are compared with the same parameters got without symmetry considerations. They are calculated in the simulation procedure. The new program (using modified Helbing model) has been elaborated and presented in this work for realization the simulation tasks the.
Geometrical symmetries of nuclear systems: D(3h) and T(d) symmetries in light nuclei
Bijker, Roelof
2016-01-01
The role of discrete (or point-group) symmetries in alpha-cluster nuclei is discussed in the framework of the algebraic cluster model which describes the relative motion of the alpha-particles. Particular attention is paid to the discrete symmetry of the geometric arrangement of the alpha-particles, and the consequences for the structure of the corresponding rotational bands. The method is applied to study cluster states in the nuclei 12C and 16O. The observed level sequences can be understood in a simple way as a consequence of the underlying discrete symmetry that characterizes the geometrical configuration of the alpha-particles, i.e. an equilateral triangle with D(3h) symmetry for 12C, and a tetrahedron with T(d) symmetry for 16O. The structure of rotational bands provides a fingerprint of the underlying geometrical configuration of alpha-particles.
A "Littlest Higgs" Model with Custodial SU(2) Symmetry
Chang, S
2003-01-01
In this note, a ``littlest higgs'' model is presented which has an approximate custodial SU(2) symmetry. The model is based on the coset space $SO(9)/(SO(5)\\times SO(4))$. The light pseudo-goldstone bosons of the theory include a single higgs doublet below a TeV and a set of three $SU(2)_W$ triplets and an electroweak singlet in the TeV range. All of these scalars obtain approximately custodial SU(2) preserving vacuum expectation values. This model addresses a defect in the earlier $SO(5)\\times SU(2)\\times U(1)$ moose model, with the only extra complication being an extended top sector. Some of the precision electroweak observables are computed and do not deviate appreciably from Standard Model predictions. A wide range of higgs masses is allowed in a large region of parameter space consistent with naturalness.
A Preonic Model with Colour-Spin Symmetry
Doğangün, Oktay; Ünel, Gökhan
2011-01-01
We have constructed a preonic model starting from a coloured fermionic preon and by postulating a new symmetry, MUSY. This new symmetry is defined via the MU number involving colour, charge and spin properties of the preons. We show that all the known fields of the Standard Model (SM) can be constructed using the fermionic preon and 6 preonic scalars, its MUSY partners. As an example, we present well known \\beta-decay process at MUSY level. MUSY also forbids some processes such as proton decay (preserving the baryon number) and hence, it is compatible with current experimental results. In this model the number of SM generations arises to be three naturally. The MUSY generalization of the SUSY algebra is constructed and the MUSY invariant Lagrangian is also explicitly written. Similar to other preonic and supersymmetric models, a number of new particles are predicted. These particles do not interact with any of the SM fermions but only with the gauge bosons. These particles could be dark matter candidates
Discrete Flavor Symmetries and Models of Neutrino Mixing
Altarelli, Guido
2010-01-01
We review the application of non abelian discrete groups to the theory of neutrino masses and mixing, which is strongly suggested by the agreement of the Tri-Bimaximal mixing pattern with experiment. After summarizing the motivation and the formalism, we discuss specific models, based on A4, S4 and other finite groups, and their phenomenological implications, including lepton flavor violating processes, leptogenesis and the extension to quarks. In alternative to Tri-Bimaximal mixing the application of discrete flavor symmetries to quark-lepton complementarity and Bimaximal Mixing is also considered.
Two Higgs doublet models with an $S_3$ symmetry
Cogollo, D
2016-01-01
We study all implementations of the $S_3$ symmetry in the two Higgs doublet model with quarks, consistent with non-zero quark masses and a Cabibbo-Kobayashi-Maskawa (CKM) matrix which is not block diagonal. We study the impact of the various soft-breaking terms and vacuum expectation values, and find an interesting relation between $\\alpha$ and $\\beta$. We also show that, in this minimal setting, only two types of assignments are possible: either all field sectors are in singlets or all field sectors have a doublet.
Symmetry Nonrestoration in a Gross-Neveu Model with Random Chemical Potential
Hong, S I; Hong, Seok-In; Kogut, John B.
2001-01-01
We study the symmetry behavior of the Gross-Neveu model in three and two dimensions with random chemical potential. This is equivalent to a four-fermion model with charge conjugation symmetry as well as Z_2 chiral symmetry. At high temperature the Z_2 chiral symmetry is always restored. In three dimensions the initially broken charge conjugation symmetry is not restored at high temperature, irrespective of the value of the disorder strength. In two dimensions and at zero temperature the charge conjugation symmetry undergoes a quantum phase transition from a symmetric state (for weak disorder) to a broken state (for strong disorder) as the disorder strength is varied. For any given value of disorder strength, the high-temperature behavior of the charge conjugation symmetry is the same as its zero-temperature behavior. Therefore, in two dimensions and for strong disorder strength the charge conjugation symmetry is not restored at high temperature.
Symmetry-Based Tight Binding Modeling of Halide Perovskite Semiconductors.
Boyer-Richard, Soline; Katan, Claudine; Traoré, Boubacar; Scholz, Reinhard; Jancu, Jean-Marc; Even, Jacky
2016-10-06
On the basis of a general symmetry analysis, this paper presents an empirical tight-binding (TB) model for the reference Pm-3m perovskite cubic phase of halide perovskites of general formula ABX3. The TB electronic band diagram, with and without spin orbit coupling effect of MAPbI3 has been determined based on state of the art density functional theory results including many body corrections (DFT+GW). It affords access to various properties, including distorted structures, at a significantly reduced computational cost. This is illustrated with the calculation of the band-to-band absorption spectrum, the variation of the band gap under volumetric strain, as well as the Rashba effect for a uniaxial symmetry breaking. Compared to DFT approaches, this empirical model will help to tackle larger issues, such as the electronic band structure of large nanostructures, including many-body effects, or heterostructures relevant to perovskite device modeling suited to the description of atomic-scale features.
Mixed-Symmetry Shell-Model Calculations in Nuclear Physics
Gueorguiev, V G
2010-01-01
We consider a novel approach to the nuclear shell model. The one-dimensional harmonic oscillator in a box is used to introduce the concept of an oblique-basis shell-model theory. By implementing the Lanczos method for diagonalization of large matrices, and the Cholesky algorithm for solving generalized eigenvalue problems, the method is applied to nuclei. The mixed-symmetry basis combines traditional spherical shell-model states with SU(3) collective configurations. We test the validity of this mixed-symmetry scheme on 24Mg and 44Ti. Results for 24Mg, obtained using the Wilthental USD intersection in a space that spans less than 10% of the full-space, reproduce the binding energy within 2% as well as an accurate reproduction of the low-energy spectrum and the structure of the states - 90% overlap with the exact eigenstates. In contrast, for an m-scheme calculation, one needs about 60% of the full space to obtain compatible results. Calculations for 44Ti support the mixed-mode scheme although the pure SU(3) ca...
Adjoint $SU(5)$ GUT model with $T_{7}$ flavor symmetry
Arbeláez, Carolina; Kovalenko, Sergey; Schmidt, Iván
2015-01-01
We propose an adjoint $SU(5)$ GUT model with a $T_{7}$ family symmetry and an extra $Z_{2}\\otimes Z_{2}^{\\prime }\\otimes Z_{3}\\otimes Z_{4}\\otimes Z_{12}$ discrete group, that successfully describes the prevailing Standard Model (SM) fermion mass and mixing pattern. The observed hierarchy of the charged fermion masses and the quark mixing angles arises from the $Z_{3}\\otimes Z_{4}\\otimes Z_{12}$ symmetry breaking, which occurs near the GUT scale. The light active neutrino masses are generated by type I and type III seesaw mechanisms mediated by the fermionic $SU(5)$ singlet and the adjoint $\\mathbf{24}$-plet. The model predicts the effective Majorana neutrino mass parameter of neutrinoless double beta decay to be $m_{\\beta \\beta }=$ 4 and 50 meV for the normal and the inverted neutrino spectrum, respectively. We construct several benchmark scenarios, which lead to $SU(5)$ gauge coupling unification and are compatible with the known phenomenological constraints originating from the lightness of neutrinos, prot...
Institute of Scientific and Technical Information of China (English)
WANG Dian-Fu
2008-01-01
In terms of the Nambu-Jona-Lasinio mechanism, dynamical breaking of gauge symmetry for the maximally generalized Yang-Mills model is investigated. The gauge symmetry behavior at finite temperature is also investigated and it is shown that the gauge symmetry broken dynamically at zero temperature can be restored at finite temperatures.
Lie symmetries and exact solutions for a short-wave model
Institute of Scientific and Technical Information of China (English)
Chen Ai-Yong; Zhang Li-Na; Wen Shuang-Quan
2013-01-01
In this paper,the Lie symmetry analysis and generalized symmetry method are performed for a short-wave model.The symmetries for this equation are given,and the phase portraits of the traveling wave systems are analyzed using the bifurcation theory of dynamical systems.The exact parametric representations of four types of traveling wave solutions are obtained.
Symmetry Breaking on Density in Escaping Ants: Experiment and Alarm Pheromone Model
Geng Li; Di Huan; Bertrand Roehner; Yijuan Xu; Ling Zeng; Zengru Di; Zhangang Han
2014-01-01
International audience; The symmetry breaking observed in nature is fascinating. This symmetry breaking is observed in both human crowds and ant colonies. In such cases, when escaping from a closed space with two symmetrically located exits, one exit is used more often than the other. Group size and density have been reported as having no significant impact on symmetry breaking, and the alignment rule has been used to model symmetry breaking. Density usually plays important roles in collectiv...
van Meer, Peter J K; Graham, Melanie L; Schuurman, Henk-Jan
2015-07-15
Nonclinical studies in animals are conducted to demonstrate proof-of-concept, mechanism of action and safety of new drugs. For a large part, in particular safety assessment, studies are done in compliance with international regulatory guidance. However, animal models supporting the initiation of clinical trials have their limitations, related to uncertainty regarding the predictive value for a clinical condition. The 3Rs principles (refinement, reduction and replacement) are better applied nowadays, with a more comprehensive application with respect to the original definition. This regards also regulatory guidance, so that opportunities exist to revise or reduce regulatory guidance with the perspective that the optimal balance between scientifically relevant data and animal wellbeing or a reduction in animal use can be achieved. In this manuscript we review the connections in the triangle between nonclinical efficacy/safety studies and regulatory aspects, with focus on in vivo testing of drugs. These connections differ for different drugs (chemistry-based low molecular weight compounds, recombinant proteins, cell therapy or gene therapy products). Regarding animal models and their translational value we focus on regulatory aspects and indications where scientific outcomes warrant changes, reduction or replacement, like for, e.g., biosimilar evaluation and safety testing of monoclonal antibodies. On the other hand, we present applications where translational value has been clearly demonstrated, e.g., immunosuppressives in transplantation. Especially for drugs of more recent date like recombinant proteins, cell therapy products and gene therapy products, a regulatory approach that allows the possibility to conduct combined efficacy/safety testing in validated animal models should strengthen scientific outcomes and improve translational value, while reducing the numbers of animals necessary. Copyright © 2015 Elsevier B.V. All rights reserved.
Triangles in a Lattice Parabola.
Sastry, K. R. S.
1991-01-01
Discussed are properties possessed by polygons inscribed in the lattice parabola y=x, including the area of a triangle, triangles of minimum area, conditions for right triangles, triangles whose area is the cube of an integer, and implications of Pick's Theorem. Further directions to pursue are suggested. (MDH)
Triangles in a Lattice Parabola.
Sastry, K. R. S.
1991-01-01
Discussed are properties possessed by polygons inscribed in the lattice parabola y=x, including the area of a triangle, triangles of minimum area, conditions for right triangles, triangles whose area is the cube of an integer, and implications of Pick's Theorem. Further directions to pursue are suggested. (MDH)
Three-Triplet Model with Double SU(3) Symmetry
Han, M. Y.; Nambu, Y.
1965-01-01
With a view to avoiding some of the kinematical and dynamical difficulties involved in the single triplet quark model, a model for the low lying baryons and mesons based on three triplets with integral charges is proposed, somewhat similar to the two-triplet model introduced earlier by one of us (Y. N.). It is shown that in a U(3) scheme of triplets with integral charges, one is naturally led to three triplets located symmetrically about the origin of I{sub 3} - Y diagram under the constraint that Nishijima-Gell-Mann relation remains intact. A double SU(3) symmetry scheme is proposed in which the large mass splittings between different representations are ascribed to one of the SU(3), while the other SU(3) is the usual one for the mass splittings within a representation of the first SU(3).
Building SO$_{10}$- models with $\\mathbb{D}_{4}$ symmetry
Laamara, R Ahl; Saidi, E H
2015-01-01
Using characters of finite group representations and monodromy of matter curves in F-GUT, we complete partial results in literature by building SO$% _{10}$ models with dihedral $\\mathbb{D}_{4}$ discrete symmetry. We first revisit the $\\mathbb{S}_{4}$-and $\\mathbb{S}_{3}$-models from the discrete group character view, then we extend the construction to $\\mathbb{D}_{4}$.\\ We find that there are three types of $SO_{10}\\times \\mathbb{D}_{4}$ models depending on the ways the $\\mathbb{S}_{4}$-triplets break down in terms of irreducible $\\mathbb{D}_{4}$- representations: $\\left({\\alpha} \\right) $ as $\\boldsymbol{1}_{_{+,-}}\\oplus \\boldsymbol{1}_{_{+,-}}\\oplus \\boldsymbol{1}_{_{-,+}};$ or $\\left({\\beta}\\right) \\boldsymbol{\\ 1}_{_{+,+}}\\oplus \\boldsymbol{1}_{_{+,-}}\\oplus \\boldsymbol{1}_{_{-,-}};$ or also $\\left({\\gamma}\\right) $ $\\mathbf{1}_{_{+,-}}\\oplus \\mathbf{2}_{_{0,0}}$. Superpotentials and other features are also given.
Directory of Open Access Journals (Sweden)
Jeffrey R. Schmidt
2012-08-01
Full Text Available Using the most elementary methods and considerations, the solution of the star-triangle condition (a2+b2-c2/2ab = ((a’^2+(b’^2-(c’^2/2a’b’ is shown to be a necessary condition for the extension of the operator coalgebra of the six-vertex model to a bialgebra. A portion of the bialgebra acts as a spectrum-generating algebra for the algebraic Bethe ansatz, with which higher-dimensional representations of the bialgebra can be constructed. The star-triangle relation is proved to be necessary for the commutativity of the transfer matrices T(a, b, c and T(a’, b’, c’.
Chivukula, R. S.; Christensen, N. D.; Coleppa, B.; Simmons, E. H.
2011-01-01
We introduce a deconstructed model that incorporates both Higgsless and top-color mechanisms. The model alleviates the typical tension in Higgsless models between obtaining the correct top quark mass and keeping Δρ small. It does so by singling out the top quark mass generation as arising from a Yukawa coupling to an effective top-Higgs which develops a small vacuum expectation value, while electroweak symmetry breaking results largely from a Higgsless mechanism. As a result, the heavy partners of the SM fermions can be light enough to be seen at the LHC.
Chivukula, R S; Coleppa, B; Simmons, E H
2010-01-01
We introduce a deconstructed model that incorporates both Higgsless and top-color mechanisms. The model alleviates the typical tension in Higgsless models between obtaining the correct top quark mass and keeping delta-rho small. It does so by singling out the top quark mass generation as arising from a Yukawa coupling to an effective top-Higgs which develops a small vacuum expectation value, while electroweak symmetry breaking results largely from a Higgsless mechanism. As a result, the heavy partners of the SM fermions can be light enough to be seen at the LHC.
Institute of Scientific and Technical Information of China (English)
梁佳敏; 刘广钟; 徐明
2015-01-01
定位问题是水声传感器网络研究领域的关键技术之一。目前大部分定位算法集中在定位算法的改进，忽视节点部署模型对定位精度的影响。提出一种用于定位的正三角形节点部署模型，在二维空间下，将锚节点以正三角的形式均匀部署，在定位区域内，未知节点总会处于以锚节点为顶点的正三角形中。在这个部署模型下，提出一种定位算法。通过Matlab进行仿真实验，结果表明，最小二乘法，Chan算法和改进算法按正三角形部署的节点模型的平均定位误差小于同节点密度下的均匀随机部署模型。在相同的节点部署密度下，正三角形模型部署下的改进算法稳定性要好于最小二乘法和Chan算法。%Localisation problem is one of the key technologies in underwater acoustic sensor network research.Currently,most of positioning algorithms focus on improving the positioning algorithm,but neglect the impact of node deployment model on positioning accuracy. We put forward an equilateral triangle nodes deployment model for positioning,in which the anchor nodes are deployed uniformly in equilateral triangle form in two-dimensional space,making the unknown nodes be always in the equilateral triangle,which takes the anchor points as vertices,within the localisation area.Based on this deployment model we put forward a positioning algorithm.Through simulation experiments on Matlab,the results showed that the average position errors of the node models deployed in equilateral triangle using three algorithms of the least square algorithm,the Chan algorithm and the improved algorithm were all less than that of the uniform random deployment model under same node density.Under same node deployment density,the improved algorithm had better stability than the least square algorithm and Chan algorithm in equilateral triangle-deployed model.
Triangle Lattice Green Functions for Vector Fields
Moritz, Brian; Schwalm, William
2000-03-01
The triangle lattice is convenient for modeling fields and fluid flows in two dimensions. Discrete vector field equations are defined through the analogy between differential forms and simplicial homology theory. The basic vector difference operators on the lattice correspond to the graph adjacency matricies of the triangle, honeycomb, and Kagomé lattices. The scalar Green functions for nearest neighbor interactions on the triangle lattice are known in closed form in terms of the complete elliptic integrals. Green functions for vector field operators are obtained explicitly in terms of the known scalar Green functions. The scalar Green functions for the Kagomé lattice are thus written in terms of the Green functions for the triangle lattice and ultimately in closed form. Thus, Green functions for a wide range of vector difference models are reduced to closed form in terms of the complete elliptic integrals.
Restricted Quantum Affine Symmetry of Perturbed Minimal Models
Felder, G
1992-01-01
We study the structure of superselection sectors of an arbitrary perturbation of a conformal field theory. We describe how a restriction of the q-deformed $\\hat{sl(2)}$ affine Lie algebra symmetry of the sine-Gordon theory can be used to derive the S-matrices of the $\\Phi^{(1,3)}$ perturbations of the minimal unitary series. This analysis provides an identification of fields which create the massive kink spectrum. We investigate the ultraviolet limit of the restricted sine-Gordon model, and explain the relation between the restriction and the Fock space cohomology of minimal models. We also comment on the structure of degenerate vacuum states. Deformed Serre relations are proven for arbitrary affine Toda theories, and it is shown in certain cases how relations of the Serre type become fractional spin supersymmetry relations upon restriction.
Exactly solvable models of scattering with SL(2, C) symmetry
Energy Technology Data Exchange (ETDEWEB)
Levay, P. [School of Physics, University of Melbourne, Parkville (Australia); Department of Theoretical Physics, Institute of Physics, Technical University, Budapest (Hungary)
2002-08-02
Using the theory of induced representations two exactly solvable models of non-relativistic scattering with SL(2, C) symmetry are presented. The first describes the scattering of a charged particle moving on the Poincare upper half space H under the influence of an SU(2) non-Abelian gauge potential with isospin s. The second deals with a one-dimensional coupled-channel scattering problem for a charged particle in a matrix-valued scalar potential containing Morse-like interaction terms. The coupled channel wavefunctions and the corresponding scattering matrices are calculated. A detailed description of the underlying geometric structures is also given and a generalization for restricting the motion to fundamental domains of H (three manifolds of constant negative sectional curvature) is outlined. Such models provide an interesting generalization to the known ones of multichannel scattering, quantum chaos and chaotic cosmology. (author)
A mathematical model of symmetry based on mathematical definition
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
Tolerance is imperative for seamless integration of CAD/CAM(Computer Aided Disign/Computer Aided Manufacture) which is just a text attribute and has no semantics in present CAD systems. There are many tolerance types, the relations between which are very complicated. In addition, the different principles of tolerance make study of tolerance difficult; and there may be various meanings or interpretation for the same type of tolerance because of the literal definition. In this work, latest unambiguous mathematical definition was applied to study, explain and clarify: (1) the formation and representation of tolerance zone, and (2) the formation and representation of variational elements; after which, the mathematical models of symmetry of different tolerance principles and different interpretations were derived. An example is given to illustrate the application of these models in tolerance analysis.
Antonella Del Rosso
2012-01-01
In the theory of the Standard Model, the masses, interactions and physical states of quarks – the basic constituents of matter – are described mathematically by a matrix known as the Cabibbo-Kobayashi-Maskawa (CKM) matrix. Three angles enter into the definition of the elements of the matrix. If their sum is not 180°, new physics might be the reason. A typical LHCb event during the recent proton-lead ion run. The LHCb experiment at CERN has measured precisely for the first time at a hadron collider one of the three angles - the “gamma” angle – so far known with the largest uncertainty. It’s a matter of angles: if their sum is not exactly 180°, the geometric shape is not a triangle. And if the angles are those related to the CKM matrix, we enter the realm of physics beyond the Standard Model. Experiments at B-factories have measured the three angles – α, β and γ &...
de Sitter symmetries and inflationary scalar-vector models
Directory of Open Access Journals (Sweden)
Juan P. Beltrán Almeida
2016-12-01
Full Text Available In this paper, we study the correspondence between a field theory in de Sitter space in D-dimensions and a dual conformal field theory in a euclidean space in (D − 1-dimensions. In particular, we investigate the form in which this correspondence is established for a system of interacting scalar and a vector fields propagating in de Sitter space. We analyze some necessary (but not sufficient conditions for which conformal symmetry is preserved in the dual theory in (D − 1-dimensions, making possible the establishment of the correspondence. The discussion that we address in this paper is framed on the context of inflationary cosmology. Thusly, the results obtained here pose some relevant possibilities of application to the calculation of the fields’s correlation functions and of the primordial curvature perturbation ζ, in inflationary models including coupled scalar and vector fields.
Symmetry and the Standard Model mathematics and particle physics
Robinson, Matthew
2011-01-01
While elementary particle physics is an extraordinarily fascinating field, the huge amount of knowledge necessary to perform cutting-edge research poses a formidable challenge for students. The leap from the material contained in the standard graduate course sequence to the frontiers of M-theory, for example, is tremendous. To make substantial contributions to the field, students must first confront a long reading list of texts on quantum field theory, general relativity, gauge theory, particle interactions, conformal field theory, and string theory. Moreover, waves of new mathematics are required at each stage, spanning a broad set of topics including algebra, geometry, topology, and analysis. Symmetry and the Standard Model: Mathematics and Particle Physics, by Matthew Robinson, is the first volume of a series intended to teach math in a way that is catered to physicists. Following a brief review of classical physics at the undergraduate level and a preview of particle physics from an experimentalist's per...
Phenomenology of Standard Model in spontaneously broken mirror symmetry
Dyatlov, Igor T
2016-01-01
Violated mirror symmetry (MS) is capable of reproducing observed qualitative properties of weak mixing for quarks and leptons. In violated MS, lepton phenomenology, that is, small neutrino masses and mixing properties different from those of quarks, requires the Dirac nature of neutrinos and existence of processes that change the total lepton number. Such processes involve heavy mirror neutrinos, and therefore occur at very high energies. CP non-conservation would mean here that the parity conserving MS Lagrangian must be non-invariant to both time reversal T and (according to the CPT theorem) the charge conjugation C. All these properties create appropriate conditions for leptogenesis, a mechanism for generating baryon-lepton asymmetry of the Universe in violated MS models.
The Interplay Between GUT and Flavour Symmetries in a Pati-Salam x S4 Model
de Adelhart Toorop, Reinier; Merlo, Luca
2010-01-01
Both Grand Unified symmetries and discrete flavour symmetries are appealing ways to describe apparent structures in the gauge and flavour sectors of the Standard Model. Both symmetries put constraints on the high energy behaviour of the theory. This can give rise to unexpected interplay when building models that possess both symmetries. We investigate on the possibility to combine a Pati-Salam model with the discrete flavour symmetry $S_4$ that gives rise to quark-lepton complementarity. Under appropriate assumptions at the GUT scale, the model reproduces fermion masses and mixings both in the quark and in the lepton sectors. We show that in particular the Higgs sector and the running Yukawa couplings are strongly affected by the combined constraints of the Grand Unified and family symmetries. This in turn reduces the phenomenologically viable parameter space, with high energy mass scales confined to a small region and some parameters in the neutrino sector slightly unnatural. In the allowed regions, we can r...
Mirror symmetry for two-parameter models, 1
Candelas, Philip; Font, A; Katz, S; Morrison, Douglas Robert Ogston; Candelas, Philip; Ossa, Xenia de la; Font, Anamaria; Katz, Sheldon; Morrison, David R.
1994-01-01
We study, by means of mirror symmetry, the quantum geometry of the K\\"ahler-class parameters of a number of Calabi-Yau manifolds that have $b_{11}=2$. Our main interest lies in the structure of the moduli space and in the loci corresponding to singular models. This structure is considerably richer when there are two parameters than in the various one-parameter models that have been studied hitherto. We describe the intrinsic structure of the point in the (compactification of the) moduli space that corresponds to the large complex structure or classical limit. The instanton expansions are of interest owing to the fact that some of the instantons belong to families with continuous parameters. We compute the Yukawa couplings and their expansions in terms of instantons of genus zero. By making use of recent results of Bershadsky et al. we compute also the instanton numbers for instantons of genus one. For particular values of the parameters the models become birational to certain models with one parameter. The co...
DEFF Research Database (Denmark)
Irwin, Alan
2014-01-01
I denne måneds klumme fra Direktionen skriver forskningsdekan Alan Irwin om den omvendte Bermuda-Trekant, The Copenhagen Triangle, et sted hvor mennesker, idéer og innovation opstår, og ansporer og nærer hinanden.......I denne måneds klumme fra Direktionen skriver forskningsdekan Alan Irwin om den omvendte Bermuda-Trekant, The Copenhagen Triangle, et sted hvor mennesker, idéer og innovation opstår, og ansporer og nærer hinanden....
Broken Time Translation Symmetry as a Model for Quantum State Reduction
Directory of Open Access Journals (Sweden)
Jasper van Wezel
2010-04-01
Full Text Available The symmetries that govern the laws of nature can be spontaneously broken, enabling the occurrence of ordered states. Crystals arise from the breaking of translation symmetry, magnets from broken spin rotation symmetry and massive particles break a phase rotation symmetry. Time translation symmetry can be spontaneously broken in exactly the same way. The order associated with this form of spontaneous symmetry breaking is characterised by the emergence of quantum state reduction: systems which spontaneously break time translation symmetry act as ideal measurement machines. In this review the breaking of time translation symmetry is first compared to that of other symmetries such as spatial translations and rotations. It is then discussed how broken time translation symmetry gives rise to the process of quantum state reduction and how it generates a pointer basis, Born’s rule, etc. After a comparison between this model and alternative approaches to the problem of quantum state reduction, the experimental implications and possible tests of broken time translation symmetry in realistic experimental settings are discussed.
Nucci, M. C.
2016-09-01
We review some of our recent work devoted to the problem of quantization with preservation of Noether symmetries, finding hidden linearity in superintegrable systems, and showing that nonlocal symmetries are in fact local. In particular, we derive the Schrödinger equation for the isochronous Calogero goldfish model using its relation to Darwin equation. We prove the linearity of a classical superintegrable system on a plane of nonconstant curvature. We find the Lie point symmetries that correspond to the nonlocal symmetries (also reinterpreted as λ-symmetries) of the Riccati chain.
Mystery of the Bermuda Triangle
Institute of Scientific and Technical Information of China (English)
王雅骧
2004-01-01
The Bernmda Triangle is also called Devil's Triangle. It is an imaginary area in the Atlantic Ocean. It extends more than one-million square kilometers between the island of Bermuda, the coast of southern Florida
DEFF Research Database (Denmark)
Ibarra, Alejandro; Lopez-Gehler, Sergio; Molinaro, Emiliano
2016-01-01
We introduce a new type of gamma-ray spectral feature, which we denominate gamma-ray triangle. This spectral feature arises in scenarios where dark matter self-annihilates via a chiral interaction into two Dirac fermions, which subsequently decay in flight into another fermion and a photon. The r...
Gershon, Tim
2007-01-01
"Physicists at "B-factories" in the US and Japan are closing in on an abstract diagram called the unitarity triangle in the quest to explain the difference between matter and antimatter. But such measurements could also point the way to the discovery of new fundamental particles." (5 pages)
African Journals Online (AJOL)
Temechegn
This paper describes uses of the systemic chemistry triangle [SCT] in which we get the benefits of both ..... The teachers follows up the following scenario for teaching [Fig.12]:. 1. ... [SATL]: A 10- year's review, AJCE, 1(1) 29-47. 3. Fahmy ...
Generalized holographic electroweak symmetry breaking models and the possibility of negative S^
Round, Mark
2011-07-01
Within an AdS/CFT inspired model of electroweak symmetry breaking, the effects of various boundary terms and modifications to the background are studied. The effect on the S^ precision parameter is discussed, with particular attention to its sign and whether the theory is unitary when S^<0. Connections between the various possible AdS slice models of symmetry breaking are discussed.
Generalised Holographic Electroweak Symmetry Breaking Models and the Possibility of Negative S
Round, Mark
2011-01-01
Within an AdS/CFT inspired model of electroweak symmetry breaking the effects of various boundary terms and modifications to the background are studied. The effect on the S precision parameter is discussed with particular attention to its sign and whether the theory is unitary when S. Connections between the various possible AdS slice models of symmetry breaking are discussed.
Directory of Open Access Journals (Sweden)
Andronikos Paliathanasis
2016-05-01
Full Text Available We perform a classification of the Lie point symmetries for the Black-Scholes-Merton Model for European options with stochastic volatility, σ, in which the last is defined by a stochastic differential equation with an Orstein-Uhlenbeck term. In this model, the value of the option is given by a linear (1 + 2 evolution partial differential equation in which the price of the option depends upon two independent variables, the value of the underlying asset, S, and a new variable, y. We find that for arbitrary functional form of the volatility, σ ( y , the (1 + 2 evolution equation always admits two Lie point symmetries in addition to the automatic linear symmetry and the infinite number of solution symmetries. However, when σ ( y = σ 0 and as the price of the option depends upon the second Brownian motion in which the volatility is defined, the (1 + 2 evolution is not reduced to the Black-Scholes-Merton Equation, the model admits five Lie point symmetries in addition to the linear symmetry and the infinite number of solution symmetries. We apply the zeroth-order invariants of the Lie symmetries and we reduce the (1 + 2 evolution equation to a linear second-order ordinary differential equation. Finally, we study two models of special interest, the Heston model and the Stein-Stein model.
Lepton Flavour Violation in Models with A4 Flavour Symmetry
Feruglio, Ferruccio; Lin, Yin; Merlo, Luca
2008-01-01
We analyze lepton flavour violating transitions, leptonic magnetic dipole moments (MDMs) and electric dipole moments (EDMs) in a class of models characterized by the flavour symmetry A4 x Z3 x U(1)_{FN}, whose choice is motivated by the approximate tri-bimaximal mixing observed in neutrino oscillations. We construct the relevant low-energy effective Lagrangian where these effects are dominated by dimension six operators, suppressed by the scale M of new physics. All the flavour breaking effects are universally described by the vacuum expectation values of a set of spurions. We separately analyze both a supersymmetric and a general case. While the observed discrepancy delta a_mu in the anomalous MDM of the muon suggests M of order of a few TeV, several data require M above 10 TeV, in particular the limit on EDM of the electron. In the general case also the present limit on BR(mu -> e gamma) requires M >10 TeV, at least. The branching ratios for mu -> e gamma, tau -> mu gamma and tau -> e gamma are all expecte...
Symmetry breaking on density in escaping ants: experiment and alarm pheromone model.
Directory of Open Access Journals (Sweden)
Geng Li
Full Text Available The symmetry breaking observed in nature is fascinating. This symmetry breaking is observed in both human crowds and ant colonies. In such cases, when escaping from a closed space with two symmetrically located exits, one exit is used more often than the other. Group size and density have been reported as having no significant impact on symmetry breaking, and the alignment rule has been used to model symmetry breaking. Density usually plays important roles in collective behavior. However, density is not well-studied in symmetry breaking, which forms the major basis of this paper. The experiment described in this paper on an ant colony displays an increase then decrease of symmetry breaking versus ant density. This result suggests that a Vicsek-like model with an alignment rule may not be the correct model for escaping ants. Based on biological facts that ants use pheromones to communicate, rather than seeing how other individuals move, we propose a simple yet effective alarm pheromone model. The model results agree well with the experimental outcomes. As a measure, this paper redefines symmetry breaking as the collective asymmetry by deducing the random fluctuations. This research indicates that ants deposit and respond to the alarm pheromone, and the accumulation of this biased information sharing leads to symmetry breaking, which suggests true fundamental rules of collective escape behavior in ants.
Symmetry breaking on density in escaping ants: experiment and alarm pheromone model.
Li, Geng; Huan, Di; Roehner, Bertrand; Xu, Yijuan; Zeng, Ling; Di, Zengru; Han, Zhangang
2014-01-01
The symmetry breaking observed in nature is fascinating. This symmetry breaking is observed in both human crowds and ant colonies. In such cases, when escaping from a closed space with two symmetrically located exits, one exit is used more often than the other. Group size and density have been reported as having no significant impact on symmetry breaking, and the alignment rule has been used to model symmetry breaking. Density usually plays important roles in collective behavior. However, density is not well-studied in symmetry breaking, which forms the major basis of this paper. The experiment described in this paper on an ant colony displays an increase then decrease of symmetry breaking versus ant density. This result suggests that a Vicsek-like model with an alignment rule may not be the correct model for escaping ants. Based on biological facts that ants use pheromones to communicate, rather than seeing how other individuals move, we propose a simple yet effective alarm pheromone model. The model results agree well with the experimental outcomes. As a measure, this paper redefines symmetry breaking as the collective asymmetry by deducing the random fluctuations. This research indicates that ants deposit and respond to the alarm pheromone, and the accumulation of this biased information sharing leads to symmetry breaking, which suggests true fundamental rules of collective escape behavior in ants.
Quantum groups as generalized gauge symmetries in WZNW models. Part I. The classical model
Hadjiivanov, L.; Furlan, P.
2017-07-01
Wess-Zumino-Novikov-Witten (WZNW) models over compact Lie groups G constitute the best studied class of (two dimensional, 2 D) rational conformal field theories (RCFTs). A WZNW chiral state space is a finite direct sum of integrable representations of the corresponding affine (current) algebra, and the correlation functions of primary fields are monodromy invariant combinations of left times right sector conformal blocks solving the Knizhnik-Zamolodchikov equation. However, even in this very well understood case of 2 D RCFT, the "internal" (gauge) symmetry that governs the ensuing fusion rules remains unclear. On the other hand, the canonical approach to the classical chiral WZNW theory developed by Faddeev, Alekseev, Shatashvili, Gawedzki and Falceto reveals its Poisson-Lie symmetry. After a covariant quantization, the latter gives rise to an associated quantum group symmetry which naturally requires an extension of the state space. This paper contains a review of earlier work on the subject with a special emphasis, in the case G = SU( n), on the emerging chiral "WZNW zero modes" which provide an adequate algebraic description of the internal symmetry structure of the model. Combining further left and right zero modes, one obtains a specific dynamical quantum group, the structure of its Fock representation resembling the axiomatic approach to gauge theories in which a "restricted" quantum group plays the role of a generalized gauge symmetry.
On q-deformed symmetries as Poisson-Lie symmetries and application to Yang-Baxter type models
Delduc, F.; Lacroix, S.; Magro, M.; Vicedo, B.
2016-10-01
Yang-Baxter type models are integrable deformations of integrable field theories, such as the principal chiral model on a Lie group G or σ-models on (semi-)symmetric spaces G/F. The deformation has the effect of breaking the global G-symmetry of the original model, replacing the associated set of conserved charges by ones whose Poisson brackets are those of the q-deformed Poisson-Hopf algebra {{\\mathscr{U}}}q({g}). Working at the Hamiltonian level, we show how this q-deformed Poisson algebra originates from a Poisson-Lie G-symmetry. The theory of Poisson-Lie groups and their actions on Poisson manifolds, in particular the formalism of the non-abelian moment map, is reviewed. For a coboundary Poisson-Lie group G, this non-abelian moment map must obey the Semenov-Tian-Shansky bracket on the dual group {G}* , up to terms involving central quantities. When the latter vanish, we develop a general procedure linking this Poisson bracket to the defining relations of the Poisson-Hopf algebra {{\\mathscr{U}}}q({g}), including the q-Poisson-Serre relations. We consider reality conditions leading to q being either real or a phase. We determine the non-abelian moment map for Yang-Baxter type models. This enables to compute the corresponding action of G on the fields parametrising the phase space of these models.
Modeling of the symmetry factor of electrochemical proton discharge via the Volmer reaction
DEFF Research Database (Denmark)
Björketun, Mårten E.; Tripkovic, Vladimir; Skúlason, Egill
2013-01-01
A scheme for evaluating symmetry factors of elementary electrode reactions using a density functional theory (DFT) based model of the electrochemical double layer is presented. As an illustration, the symmetry factor is determined for hydrogen adsorption via the electrochemical Volmer reaction. T...
Virtual and Printed 3D Models for Teaching Crystal Symmetry and Point Groups
Casas, Lluís; Estop, Euge`nia
2015-01-01
Both, virtual and printed 3D crystal models can help students and teachers deal with chemical education topics such as symmetry and point groups. In the present paper, two freely downloadable tools (interactive PDF files and a mobile app) are presented as examples of the application of 3D design to study point-symmetry. The use of 3D printing to…
Symmetries, Symmetry Breaking, Gauge Symmetries
Strocchi, Franco
2015-01-01
The concepts of symmetry, symmetry breaking and gauge symmetries are discussed, their operational meaning being displayed by the observables {\\em and} the (physical) states. For infinitely extended systems the states fall into physically disjoint {\\em phases} characterized by their behavior at infinity or boundary conditions, encoded in the ground state, which provide the cause of symmetry breaking without contradicting Curie Principle. Global gauge symmetries, not seen by the observables, are nevertheless displayed by detectable properties of the states (superselected quantum numbers and parastatistics). Local gauge symmetries are not seen also by the physical states; they appear only in non-positive representations of field algebras. Their role at the Lagrangian level is merely to ensure the validity on the physical states of local Gauss laws, obeyed by the currents which generate the corresponding global gauge symmetries; they are responsible for most distinctive physical properties of gauge quantum field ...
A Generalized Yang-Mills Model and Dynamical Breaking of Gauge Symmetry
Institute of Scientific and Technical Information of China (English)
WANG Dian-Fu; SONG He-Shan
2005-01-01
A generalized Yang-Mills model, which contains, besides the vector part Vμ, also a scalar part S, is constructed and the dynamical breaking of gauge symmetry in the model is also discussed. It is shown, in terms of Nambu-Jona-Lasinio (NJL) mechanism, that the gauge symmetry breaking can be realized dynamically in the generalized Yang-Mills model. The combination of the generalized Yang-Mills model and the NJL mechanism provides a way to overcome the difficulties related to the Higgs field and the Higgs mechanism in the usual spontaneous symmetry breaking theory.
Explicit chiral symmetry breaking in Gross-Neveu type models
Energy Technology Data Exchange (ETDEWEB)
Boehmer, Christian
2011-07-25
This thesis is devoted to the study of a 1+1-dimensional, fermionic quantum field theory with Lagrangian L= anti {psi}i{gamma}{sup {mu}}{partial_derivative}{sub {mu}}{psi}-m{sub 0} anti {psi}{psi}+(g{sup 2})/(2)(anti {psi}{psi}){sup 2}+(G{sup 2})/(2)(anti {psi}i{gamma}{sub 5}{psi}){sup 2} in the limit of an infinite number of flavors, using semiclassical methods. The main goal of the present work was to see what changes if we allow for explicit chiral symmetry breaking, either by a bare mass term, or a splitting of the scalar and pseudo-scalar coupling constants, or both. In the first case, this becomes the massive NJL{sub 2} model. In the 2nd and 3rd cases we are dealing with a model largely unexplored so far. The first half of this thesis deals with the massive NJL{sub 2} model. Before attacking the phase diagram, it was necessary to determine the baryons of the model. We have carried out full numerical Hartree-Fock calculations including the Dirac sea. The most important result is the first complete phase diagram of the massive NJL{sub 2} model in ({mu},T,{gamma}) space, where {gamma} arises from m{sub 0} through mass renormalization. In the 2nd half of the thesis we have studied a generalization of the massless NJL{sub 2} model with two different (scalar and pseudoscalar) coupling constants, first in the massless version. Renormalization of the 2 coupling constants leads to the usual dynamical mass by dynamical transmutation, but in addition to a novel {xi} parameter interpreted as chiral quenching parameter. As far as baryon structure is concerned, the most interesting result is the fact that the new baryons interpolate between the kink of the GN model and the massless baryon of the NJL{sub 2} model, always carrying fractional baryon number 1/2. The phase diagram of the massless model with 2 coupling constants has again been determined numerically. At zero temperature we have also investigated the massive, generalized GN model with 3 parameters. It is well
On q-deformed symmetries as Poisson-Lie symmetries and application to Yang-Baxter type models
Delduc, Francois; Magro, Marc; Vicedo, Benoit
2016-01-01
Yang-Baxter type models are integrable deformations of integrable field theories, such as the principal chiral model on a Lie group $G$ or $\\sigma$-models on (semi-)symmetric spaces $G/F$. The deformation has the effect of breaking the global $G$-symmetry of the original model, replacing the associated set of conserved charges by ones whose Poisson brackets are those of the $q$-deformed Poisson-Hopf algebra $\\mathscr U_q(\\mathfrak g)$. Working at the Hamiltonian level, we show how this $q$-deformed Poisson algebra originates from a Poisson-Lie $G$-symmetry. The theory of Poisson-Lie groups and their actions on Poisson manifolds, in particular the formalism of the non-abelian moment map, is reviewed. For a coboundary Poisson-Lie group $G$, this non-abelian moment map must obey the Semenov-Tian-Shansky bracket on the dual group $G^*$, up to terms involving central quantities. When the latter vanish, we develop a general procedure linking this Poisson bracket to the defining relations of the Poisson-Hopf algebra...
Lepton flavour violation in models with A flavour symmetry
Feruglio, Ferruccio; Hagedorn, Claudia; Lin, Yin; Merlo, Luca
2009-03-01
We analyze lepton flavour violating transitions, leptonic magnetic dipole moments (MDMs) and electric dipole moments (EDMs) in a class of models characterized by the flavour symmetry A×Z×U(1, whose choice is motivated by the approximate tri-bimaximal mixing observed in neutrino oscillations. We construct the relevant low-energy effective Lagrangian where these effects are dominated by dimension six operators, suppressed by the scale M of new physics. All the flavour breaking effects are universally described by the vacuum expectation values of a set of spurions. We separately analyze both a supersymmetric and a general case. While the observed discrepancy δa in the anomalous MDM of the muon suggests M of order of a few TeV, several data require M above 10 TeV, in particular the limit on EDM of the electron. In the general case also the present limit on BR(μ→eγ) requires M>10 TeV, at least. The branching ratios for μ→eγ, τ→μγ and τ→eγ are all expected to be of the same order. In the supersymmetric case the constraint from μ→eγ is softened and it can be satisfied by a smaller scale M. In this case both the observed δa and the current bound on BR(μ→eγ) can be satisfied, at the price of a rather small value for ||, of the order of a few percents, that reflects on a similar value for θ.
Quintom cosmological model and some possible solutions using Lie and Noether symmetries
Dutta, Sourav; Chakraborty, Subenoy
2016-01-01
The present work deals with a quintom model of dark energy in the framework of a spatially flat isotropic and homogeneous Friedmann-Lemaitre-Robertson-Walker (FLRW) universe. At first, Lie point symmetry is imposed to the system and the unknown coupled potential of the model is determined. Then Noether symmetry, which is also a point like symmetry of the Lagrangian, is imposed on the physical system and the potential takes a general form. It is shown that the Lie algebra of Noether symmetry is a sub-algebra of the corresponding Lie algebra of the Lie symmetry. Finally, a point transformation in the three dimensional augmented space is performed suitably so that one of the variables become cyclic and as a result there is considerable simplification to the physical system. Hence conserved quantities (i.e, constants of motion) are expressed in a compact form and cosmological solutions are evaluated and analyzed in the present context.
Chirally Invariant Avatar in a Model of Neutrinos with Light Cone Reflection Symmetry
Chodos, Alan
2016-01-01
In previous work we developed a model of neutrinos based on a new symmetry, Light Cone Reflection (LCR), that interchanges spacelike and timelike intervals. In this paper we start with the four-dimensional model, and construct a two-dimensional avatar that obeys the same equations of motion, and preserves both the light-cone reflection symmetry and the chiral symmetry of the original theory. The avatar also contains the interaction that rendered the four-dimensional model gauge invariant. In an addendum, we make some remarks about how to determine the scalar field that enters into the definition of the LCR-covariant derivative.
Curvature-induced symmetry breaking in nonlinear Schrodinger models
DEFF Research Database (Denmark)
Gaididei, Yuri Borisovich; Mingaleev, S. F.; Christiansen, Peter Leth
2000-01-01
We consider a curved chain of nonlinear oscillators and show that the interplay of curvature and nonlinearity leads to a symmetry breaking when an asymmetric stationary state becomes energetically more favorable than a symmetric stationary state. We show that the energy of localized states decrea...
The symmetry breaking phenomenon in anharmonic oscillator model
Mastine, Antonio Carlos; Natti, Erica Regina Takano
2010-01-01
In this article a non-perturbative time-dependent technique is used to treat the initial value problem, in Quantum Mechanics context, for a non-equilibrium self-interacting fermionic system in the presence of an external magnetic field. Particularly, in mean-field regime, we study the dynamical symmetry breaking phenomenon, identifying the physical processes associated.
Chiral and U(1) axial symmetry restoration in linear sigma models with two quark flavors
Michalski, S
2006-01-01
We study the restoration of chiral symmetry in linear sigma models with two quark flavors. The models taken into consideration have a U(2) x U(2) and an O(N) internal symmetry. The physical mesons of these models are sigma, pion, \\eta and a_0 where the latter two are not present in the O(N) model. Including two-loop contributions through sunset graphs we calculate the temperature behavior of the order parameter and the masses for explicit chiral symmetry breaking with and without a U(1) axial anomaly. Decay threshold effects introduced by the sunset graphs alter the temperature dependence of the condensate and consequently that of the masses as well. Chiral symmetry tends to be restored at higher temperatures in the two-loop approximation than in the Hartree-Fock approximation. To model a dynamical restoration of the U(1) axial symmetry we imply a temperature-dependent anomaly parameter that sharply drops at about 175 MeV. This triggers the restoration of chiral symmetry before the full symmetry is restored a...
Symmetry energy and neutron star properties in the saturated Nambu–Jona-Lasinio model
Directory of Open Access Journals (Sweden)
Si-Na Wei
2016-12-01
Full Text Available In this work, we adopt the Nambu–Jona-Lasinio (NJL model that ensures the nuclear matter saturation properties to study the density dependence of the symmetry energy. With the interactions constrained by the chiral symmetry, the symmetry energy shows novel characters different from those in conventional mean-field models. First, the negative symmetry energy at high densities that is absent in relativistic mean-field (RMF models can be obtained in the RMF approximation by introducing a chiral isovector–vector interaction, although it would be ruled out by the neutron star (NS stability. Second, with the inclusion of the isovector–scalar interaction the symmetry energy exhibits a general softening at high densities even for the large slope parameter of the symmetry energy. The NS properties obtained in the present NJL model can be in accord with the observations. The NS maximum mass obtained with various isovector–scalar couplings and momentum cutoffs is well above the 2M⊙, and the NS radius obtained well meets the limits extracted from recent measurements. In particular, the significant reduction of the canonical NS radius occurs with the moderate decrease of the slope of the symmetry energy.
Low-Scale Leptogenesis and the Domain Wall Problem in Models with Discrete Flavor Symmetries
Riva, Francesco
2010-01-01
We propose a new mechanism for leptogenesis, which is naturally realized in some models with a flavor symmetry based on the discrete group A_4, where the symmetry breaking parameter also controls the Majorana masses for the heavy right handed (RH) neutrinos. During the early universe, for T>TeV, part of the symmetry is restored, due to finite temperature contributions, and the RH neutrinos remain massless and can be produced in thermal equilibrium even at temperatures well below the most conservative gravitino bounds. Below this temperature the phase transition occurs and they become massive, decaying out of equilibrium and producing the necessary lepton asymmetry. Unless the symmetry is broken explicitly by Planck-suppressed terms, the domain walls generated by the symmetry breaking survive till the quark-hadron phase transition, where they disappear due to a small energy splitting between different vacua caused by the QCD anomaly.
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.
Local conformal symmetry in black holes, standard model, and quantum gravity
Hooft, Gerard ’T.
The black hole information problem and the firewall problem can be addressed by assuming an extra local symmetry: conformal invariance. It must be an exact symmetry, spontaneously broken by the vacuum, in a way similar to the Brout-Englert-Higgs (BEH) mechanism. We note how this symmetry formally removes the horizon and the singularity inside black holes. For the Standard Model this symmetry is severely restrictive, demanding all coupling constants, masses and even the cosmological constant to be computable, in principle. Finally, this symmetry suggests that the Weyl action (the square of the Weyl curvature) should be added to the Einstein-Hilbert action. The ensuing indefinite metric states are briefly studied, and we conclude with some remarks concerning the interpretation of quantum mechanics.
BETHE ANSATZ FOR SUPERSYMMETRIC MODEL WITH?Uq[osp( 1｜2 ) ] SYMMETRY
Institute of Scientific and Technical Information of China (English)
杨文力
2001-01-01
Using the algebraic Bethe ansatz method, we obtain the eigenvalues of the transfer matrix of the supersymmetric model with Uq[osp(1｜2)] symmetry under periodic boundary and twisted boundary conditions.
Femoralni trikotnik: The femoral triangle:
Mlakar, Boštjan; Ravnik, Dean
1999-01-01
The topography and structures of the femoral triangle are presented. The femorai triangle lies between the inguinal ligament at the base, the sartoriusmuscle at the lateral border and the long adductor muscle at the medial border. The apex of the femoral triangle is situated at the meeting point of the medial borders of the sartorius and long adductor muscles. The subinguinal space, which is divided into the lacuna musculorum and lacuna vasorum, provides a passageway for the lateral cutaneous...
All Majorana Models with Translation Symmetry are Supersymmetric
Hsieh, Timothy H; Grover, Tarun
2016-01-01
We establish results similar to Kramers and Lieb-Schultz-Mattis theorems but involving only translation symmetry and for Majorana modes. In particular, we show that all states are at least doubly degenerate in any one and two dimensional array of Majorana modes with translation symmetry, periodic boundary conditions, and an odd number of modes per unit cell. Moreover, we show that all such systems have an underlying N=2 supersymmetry and explicitly construct the generator of the supersymmetry. Furthermore, we show that there cannot be a unique gapped ground state in such one dimensional systems with anti-periodic boundary conditions. These general results are fundamentally a consequence of the fact that translations for Majorana modes are represented projectively, which in turn stems from the anomalous nature of a single Majorana mode.
A scalar field dark energy model: Noether symmetry approach
Dutta, Sourav; Panja, Madan Mohan; Chakraborty, Subenoy
2016-04-01
Scalar field dark energy cosmology has been investigated in the present paper in the frame work of Einstein gravity. In the context of Friedmann-Lemaitre-Robertson-Walker space time minimally coupled scalar field with self interacting potential and non-interacting perfect fluid with barotropic equation of state (dark matter) is chosen as the matter context. By imposing Noether symmetry on the Lagrangian of the system the symmetry vector is obtained and the self interacting potential for the scalar field is determined. Then we choose a point transformation (a, φ )→ (u, v) such that one of the transformation variable (say u) is cyclic for the Lagrangian. Subsequently, using conserved charge (corresponding to the cyclic co-ordinate) and the constant of motion, solutions are obtained. Finally, the cosmological implication of the solutions in the perspective of recent observation has been examined.
All Majorana Models with Translation Symmetry are Supersymmetric
Hsieh, Timothy H.; Halász, Gábor B.; Grover, Tarun
2016-10-01
We establish results similar to Kramers and Lieb-Schultz-Mattis theorems but involving only translation symmetry and for Majorana modes. In particular, we show that all states are at least doubly degenerate in any one- and two-dimensional array of Majorana modes with translation symmetry, periodic boundary conditions, and an odd number of modes per unit cell. Moreover, we show that all such systems have an underlying N =2 supersymmetry and explicitly construct the generator of the supersymmetry. Furthermore, we establish that there cannot be a unique gapped ground state in such one-dimensional systems with antiperiodic boundary conditions. These general results are fundamentally a consequence of the fact that translations for Majorana modes are represented projectively, which in turn stems from the anomalous nature of a single Majorana mode. An experimental signature of the degeneracy arising from supersymmetry is a zero-bias peak in tunneling conductance.
Triangle Universities Nuclear Laboratory
Energy Technology Data Exchange (ETDEWEB)
1991-01-01
This report contains brief papers that discusses the following topics: Fundamental Symmetries in the Nucleus; Internucleon Interactions; Dynamics of Very Light Nuclei; Facets of the Nuclear Many-Body Problem; and Nuclear Instruments and Methods.
Electroweak symmetry breaking and beyond the Standard Model physics – A review
Indian Academy of Sciences (India)
Gautam Bhattacharyya
2009-01-01
In this talk, I shall first discuss the Standard Model Higgs mechanism and then highlight some of its deficiencies making a case for the need to go beyond the Standard Model (BSM). The BSM tour will be guided by symmetry arguments. I shall pick up four specific BSM scenarios, namely, supersymmetry, little Higgs, gauge-Higgs unification, and the Higgsless approach. The discussion will be confined mainly on their electroweak symmetry breaking aspects.
Quantum groups as generalized gauge symmetries in WZNW models. Part II. The quantized model
Hadjiivanov, L.; Furlan, P.
2017-07-01
This is the second part of a paper dealing with the "internal" (gauge) symmetry of the Wess-Zumino-Novikov-Witten (WZNW) model on a compact Lie group G. It contains a systematic exposition, for G = SU( n), of the canonical quantization based on the study of the classical model (performed in the first part) following the quantum group symmetric approach first advocated by L.D. Faddeev and collaborators. The internal symmetry of the quantized model is carried by the chiral WZNW zero modes satisfying quadratic exchange relations and an n-linear determinant condition. For generic values of the deformation parameter the Fock representation of the zero modes' algebra gives rise to a model space of U q ( sl( n)). The relevant root of unity case is studied in detail for n = 2 when a "restricted" (finite dimensional) quotient quantum group is shown to appear in a natural way. The module structure of the zero modes' Fock space provides a specific duality with the solutions of the Knizhnik-Zamolodchikov equation for the four point functions of primary fields suggesting the existence of an extended state space of logarithmic CFT type. Combining left and right zero modes (i.e., returning to the 2 D model), the rational CFT structure shows up in a setting reminiscent to covariant quantization of gauge theories in which the restricted quantum group plays the role of a generalized gauge symmetry.
Conformal symmetry vs. chiral symmetry breaking in the SU(3) sextet model
DEFF Research Database (Denmark)
Drach, Vincent; Hansen, Martin; Hietanen, Ari;
2015-01-01
We present new results for the SU(3) "sextet model" with two flavors transforming according to the two-index symmetric representation of the gauge group. The simulations are performed using unimproved Wilson fermions. We measure the meson and baryon spectrum of the theory for multiple bare quark ...
Radiative Effects and Electroweak Symmetry Breaking in a Supersymmetric Preon Model
Kim, Jongbae
We construct the low energy effective theory of composite quarks, leptons, and Higgs bosons for a supersymmetric preon model and study the effects of renormalization-group based radiative corrections. The study on the evolution of scalar masses for avoiding color and charge breakings leads us to conclude that Yukawa couplings are bounded from above. The implementation of electroweak symmetry breaking requires that only the purely dynamical symmetry breaking should be needed for the model, but the combined scheme of dynamical and radiative symmetry breaking as well as the purely radiative symmetry breaking scheme be disfavored. Our analysis of (mb)/(m_τ ) including radiative effects shows that, should a discrepancy be found between the observed and the theoretical value of (mb)/(m_τ ) after experimental determination of supersymmetric particle masses, it would imply that the complete quark-lepton universality in the supersymmetric preon model does not hold either for the Yukawa couplings, or for the condensates, or for both.
Unified model of fermion masses with Wilson line flavor symmetry breaking
Seidl, Gerhart
2008-01-01
We present a supersymmetric SU(5) GUT model with a discrete non-Abelian flavor symmetry that is broken by Wilson lines. The model is formulated in 4+3 dimensions compactified on a manifold S^3/Z_n. Symmetry breaking by Wilson lines is topological and allows to realize the necessary flavor symmetry breaking without a vacuum alignment mechanism. The model predicts the hierarchical pattern of charged fermion masses and quark mixing angles. Small normal hierarchical neutrino masses are generated by the type-I seesaw mechanism. The non-Abelian flavor symmetry predicts to leading order exact maximal atmospheric mixing while the solar angle emerges from quark-lepton complementarity. The resulting leptonic mixing matrix is in excellent agreement with current data and could be tested in future neutrino oscillation experiments.
The interplay between grand unified and flavour symmetries in a Pati-Salam x S4 model
Toorop, Reinier de Adelhart
2010-01-01
Both discrete flavour symmetries and Grand Unified symmetries explain apparent structures in the mass sector of the Standard Model. A model that combines both symmetries is therefore very appealing. We construct a model with the $S_4$ flavour symmetry and the Pati-Salam unification. We show that this model can indeed explain many observable relations between the masses of the quarks and leptons and that it is predictive in the neutrino sector. However, the combination of the two symmetries leads to new complications in the Higgs sector and in the running of the renormalisation group equations.
Decay patterns of multi-quasiparticle bands—a model independent test of chiral symmetry
Lawrie, E. A.
2017-09-01
Nuclear chiral systems exhibit chiral symmetry bands, built on left-handed and right-handed angular momentum nucleon configurations. The experimental search for such chiral systems revealed a number of suitable candidates, however an unambiguous identification of nuclear chiral symmetry is still outstanding. In this work it is shown that the decay patterns of chiral bands built on multi-quasiparticle configurations are different from those involving different single-particle configurations. It is suggested to use the observed decay patterns of chiral candidates as a new model-independent test of chiral symmetry.
The Effective Kahler Potential, Metastable Vacua and R-Symmetry Breaking in O'Raifeartaigh Models
Benjamin, Shermane; Kain, Ben
2010-01-01
Much has been learned about metastable vacua and R-symmetry breaking in O'Raifeartaigh models. Such work has largely been done from the perspective of the superpotential and by including Coleman-Weinberg corrections to the scalar potential. Instead, we consider these ideas from the perspective of the one loop effective Kahler potential. We translate known ideas to this framework and construct convenient formulas for computing individual terms in the expanded effective Kahler potential. We do so for arbitrary R-charge assignments and allow for small R-symmetry violating terms so that both spontaneous and explicit R-symmetry breaking is allowed in our analysis.
Ordering dynamics of microscopic models with nonconserved order parameter of continuous symmetry
DEFF Research Database (Denmark)
Zhang, Z.; Mouritsen, Ole G.; Zuckermann, Martin J.
1993-01-01
Numerical Monte Carlo temperature-quenching experiments have been performed on two three-dimensional classical lattice models with continuous ordering symmetry: the Lebwohl-Lasher model [Phys. Rev. A 6, 426 (1972)] and the ferromagnetic isotropic Heisenberg model. Both models describe a transition...... from a disordered phase to an orientationally ordered phase of continuous symmetry. The Lebwohl-Lasher model accounts for the orientational ordering properties of the nematic-isotropic transition in liquid crystals and the Heisenberg model for the ferromagnetic-paramagnetic transition in magnetic...
Froggatt-Nielsen models with a residual Z_4^R symmetry
Dreiner, Herbi K; Opferkuch, Toby
2013-01-01
The Froggatt-Nielsen mechanism provides an elegant explanation for the hierarchies of fermion masses and mixings in terms of a U(1) symmetry. Promoting such a family symmetry to an R-symmetry, we explicitly construct supersymmetric Froggatt-Nielsen models which are gauged, family dependent U(1)_R completions of the Z_4^R symmetry proposed by Lee, Raby, Ratz, Ross, Schieren, Schmidt-Hoberg and Vaudrevange in 2010. Forbidden by Z_4^R, the mu-term is generated around the supersymmetry breaking scale m_3/2 from either the Kahler potential or the superpotential. Neutrinos acquire their mass via the type I seesaw mechanism with three right-handed neutrino superfields. Taking into account the Green-Schwarz anomaly cancellation conditions, we arrive at a total of 3 x 34 distinct phenomenologically viable charge assignments for the standard model fields, most of which feature highly fractional charges.
Fermat Surface and Group Theory in Symmetry of Rapidity Family in Chiral Potts Model
Roan, Shi-shyr
2013-01-01
The present paper discusses various mathematical aspects about the rapidity symmetry in chiral Potts model (CPM) in the context of algebraic geometry and group theory . We re-analyze the symmetry group of a rapidity curve in $N$-state CPM, explore the universal group structure for all $N$, and further enlarge it to modular symmetries of the complete rapidity family in CPM. As will be shown in the article that all rapidity curves in $N$-state CPM constitute a Fermat hypersurface in $\\PZ^3$ of degree 2N as the natural generalization of the Fermat K3 elliptic surface $(N=2)$, we conduct a thorough algebraic geometry study about the rapidity fibration of Fermat surface and its reduced hyperelliptic fibration via techniques in algebraic surface theory. Symmetries of rapidity family in CPM and hyperelliptic family in $\\tau^{(2)}$-model are exhibited through the geometrical representation of the universal structural group in mathematics.
Wang, Zhi-Wei; Steele, T G; Mann, R B; Hanif, T
2016-01-01
We consider a conformal complex singlet extension of the Standard Model with a Higgs portal interaction. Two different scenarios depending on whether the global U(1) symmetry is broken or not have been studied. In the unbroken phase, the decay of the complex singlet is protected by the global U(1) symmetry which leads to an ideal cold dark matter candidate. In the broken phase, we are able to provide a second Higgs at $554\\,\\rm{GeV}$. In addition, gauging the global U(1) symmetry, we can construct an asymptotically safe U(1)' leptophobic model. We combine the notion of asymptotic safety with conformal symmetry and use the renormalization group equations as a bridge to connect UV boundary conditions and Electroweak/ TeV scale physics. We also provide a detailed example to show that these boundary conditions will lead to phenomenological signatures such as diboson excesses which could be tested at the LHC.
On permutation symmetries of hopfield model neural network
Directory of Open Access Journals (Sweden)
Jiyang Dong
2001-01-01
Full Text Available Discrete Hopfield neural network (DHNN is studied by performing permutation operations on the synaptic weight matrix. The storable patterns set stored with Hebbian learning algorithm in a network without losing memories is studied, and a condition which makes sure all the patterns of the storable patterns set have a same basin size of attraction is proposed. Then, the permutation symmetries of the network are studied associating with the stored patterns set. A construction of the storable patterns set satisfying that condition is achieved by consideration of their invariance under a point group.
Winkelsas, John
2006-01-01
The Bermuda Triangle is famous for the unexplained disappearances of ships and aircraft, and for strange meteorological phenomena that allegedly have occurred within its boundaries. This article presents an activity wherein students are asked to create their own geographical triangles to research, but instead of focusing on the unexplainable,…
The Bermuda Triangle of Education.
Bertrand, Yves
The pedagogical triangle of teacher, learner, and subject matter has in its center a fourth element: the communication system. Each feature of the pedagogical triangle, and the communication system as well, relies on a very important cultural component. Problems occur when communication processes in a classroom are fragmented and related to…
Cosmological models with spinor and scalar fields by Noether symmetry approach
Kremer, Gilberto M
2013-01-01
General cosmological models with spinor and scalar fields playing the role of gravitational sources are analyzed. The Noether symmetry approach is taken as a criterion to constrain the undefined potentials and couplings of the generic actions. For all the found Noether symmetries the corresponding dynamical systems can be analytically integrated. The obtained cosmological solutions describe the early and late Universe as expected by basing on the known eras of the Universe.
CP violation from flavor symmetry in a lepton quarticity dark matter model
Chuliá, Salvador Centelles; Srivastava, Rahul; Valle, José W. F.
2016-10-01
We propose a simple Δ (27) ⊗Z4 model where neutrinos are predicted to be Dirac fermions. The smallness of their masses follows from a type-I seesaw mechanism and the leptonic CP violating phase correlates with the pattern of Δ (27) flavor symmetry breaking. The scheme naturally harbors a WIMP dark matter candidate associated to the Dirac nature of neutrinos, in that the same Z4 lepton number symmetry also ensures dark matter stability.
Predicting CP Violation from Flavor Symmetry in a Lepton Quarticity Dark Matter Model
Chuliá, Salvador Centelles; Valle, José W F
2016-01-01
We propose a simple $\\Delta (27) \\otimes Z_4$ model where neutrinos are predicted to be Dirac fermions. The smallness of their masses follows from a type-I seesaw mechanism and the leptonic CP violating phase correlates with the pattern of $\\Delta (27)$ flavor symmetry breaking. The scheme naturally harbors a WIMP dark matter candidate associated to the Dirac nature of neutrinos, in that the same $Z_4$ lepton number symmetry also ensures dark matter stability.
Van Enter, A C D
2003-01-01
We consider various sufficiently nonlinear sigma models for nematic ordering of RP^{N-1} type and of lattice gauge type with continous symmetries. We rigorously show that they exhibit a first-order transition in the temperature. The result holds in dimension 2 or more for the RP{N-1} models and in dimension 3 or more for the lattice gauge models. In the two-dimensional case our results clarify and solve a recent controversy about the possibilty of such transitions. For lattice gauge models our methods provide the first prof of a first-order transition in a model with a continous gauge symmetry.
Symmetry-enriched string nets: Exactly solvable models for SET phases
Heinrich, Chris; Burnell, Fiona; Fidkowski, Lukasz; Levin, Michael
2016-12-01
We construct exactly solvable models for a wide class of symmetry-enriched topological (SET) phases. Our construction applies to two-dimensional (2D) bosonic SET phases with finite unitary on-site symmetry group G and we conjecture that our models realize every phase in this class that can be described by a commuting projector Hamiltonian. Our models are designed so that they have a special property: If we couple them to a dynamical lattice gauge field with gauge group G , the resulting gauge theories are equivalent to string-net models. This property is what allows us to analyze our models in generality. As an example, we present a model for a phase with the same anyon excitations as the toric code and with a Z2 symmetry which exchanges the e and m type anyons. We further illustrate our construction with a number of additional examples.
Anomaly-free U(1) gauge symmetries in neutrino seesaw flavor models
Cebola, Luis M; Felipe, Ricardo Gonzalez
2013-01-01
Adding right-handed neutrino singlets and/or fermion triplets to the particle content of the Standard Model allows for the implementation of the seesaw mechanism to give mass to neutrinos and, simultaneously, for the construction of anomaly-free gauge group extensions of the theory. We consider Abelian extensions based on an extra U(1)_X gauge symmetry, where X is an arbitrary linear combination of the baryon number B and the individual lepton numbers L_{e,mu,tau}. By requiring cancellation of gauge anomalies, we perform a detailed analysis in order to identify the charge assignments under the new gauge symmetry that lead to neutrino phenomenology compatible with current experiments. In particular, we study how the new symmetry can constrain the flavor structure of the Majorana neutrino mass matrix, leading to two-zero textures with a minimal extra fermion and scalar content. The possibility of distinguishing different gauge symmetries and seesaw realizations at colliders is also briefly discussed.
Wahlen-Strothman, Jacob M; Hermes, Matthew R; Degroote, Matthias; Qiu, Yiheng; Zhao, Jinmo; Dukelsky, Jorge; Scuseria, Gustavo E
2016-01-01
Coupled cluster and symmetry projected Hartree-Fock are two central paradigms in electronic structure theory. However, they are very different. Single reference coupled cluster is highly successful for treating weakly correlated systems, but fails under strong correlation unless one sacrifices good quantum numbers and works with broken-symmetry wave functions, which is unphysical for finite systems. Symmetry projection is effective for the treatment of strong correlation at the mean-field level through multireference non-orthogonal configuration interaction wavefunctions, but unlike coupled cluster, it is neither size extensive nor ideal for treating dynamic correlation. We here examine different scenarios for merging these two dissimilar theories. We carry out this exercise over the integrable Lipkin model Hamiltonian, which despite its simplicity, encompasses non-trivial physics for degenerate systems and can be solved via diagonalization for a very large number of particles. We show how symmetry projection...
The strong-weak coupling symmetry in 2D Φ4 field models
Directory of Open Access Journals (Sweden)
B.N.Shalaev
2005-01-01
Full Text Available It is found that the exact beta-function β(g of the continuous 2D gΦ4 model possesses two types of dual symmetries, these being the Kramers-Wannier (KW duality symmetry and the strong-weak (SW coupling symmetry f(g, or S-duality. All these transformations are explicitly constructed. The S-duality transformation f(g is shown to connect domains of weak and strong couplings, i.e. above and below g*. Basically it means that there is a tempting possibility to compute multiloop Feynman diagrams for the β-function using high-temperature lattice expansions. The regular scheme developed is found to be strongly unstable. Approximate values of the renormalized coupling constant g* found from duality symmetry equations are in an agreement with available numerical results.
Spontaneous symmetry breaking in a non-conserving two-species driven model
Energy Technology Data Exchange (ETDEWEB)
Levine, E [Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot, 76100 (Israel); Willmann, R D [Institut fuer Festkoerperforschung, Forschungszentrum Juelich, 52425 Juelich (Germany)
2004-03-12
A two-species particle model on an open chain with dynamics which is non-conserving in the bulk is introduced. The dynamical rules which define the model obey a symmetry between the two species. The model exhibits a rich behaviour which includes spontaneous symmetry breaking and localized shocks. The phase diagram in several regions of parameter space is calculated within the mean-field approximation, and compared with Monte Carlo simulations. In the limit where fluctuations in the number of particles in the system are taken to be zero, an exact solution is obtained. We present and analyse a physical picture which serves to explain the different phases of the model.
On symmetries of N=(4,4) sigma models on T^4
Volpato, Roberto
2014-01-01
Motivated by an analogous result for K3 models, we classify all groups of symmetries of non-linear sigma models on a torus T^4 that preserve the N=(4,4) superconformal algebra. The resulting symmetry groups are isomorphic to certain subgroups of the Weyl group of E8, that plays a role similar to the Conway group for the case of K3 models. Our analysis heavily relies on the triality automorphism of the T-duality group SO(4,4,Z). As a byproduct of our results, we discover new explicit descriptions of K3 models as asymmetric orbifolds of torus CFTs.
Noether Symmetries Of A Modified Model In Teleparallel Gravity
Tajahmad, Behzad
2016-01-01
In this paper, we have presented the Noether symmetries of flat FRW spacetime in the context of a new action in Teleparallel Gravity which we construct it based on f(R) version. This modified action contains a coupling between scalar field potential and magnetism. Also, we introduce an innovative approach (B.N.S. Approach) for exact solutions which carry more conserved currents than Noether approach. By data analysis the exact solutions, obtained from Noether approach, late time acceleration and phase crossing are realized, and some deep connections with observational data such as age of universe, the present amount of scale factor, state and deceleration parameters are observed. In B.N.S. approach, we have considered dark energy dominated era.
Precision Spectroscopy and Higher Spin symmetry in the ABJM model
Bianchi, Massimo; Samsonyan, Marine
2010-01-01
We revisit Kaluza-Klein compactification of 11-d supergravity on S^7/Z_k using group theory techniques that may find application in other flux vacua with internal coset spaces. Among the SO(2) neutral states, we identify marginal deformations and fields that couple to the recently discussed world-sheet instanton of Type IIA on CP^3. We also discuss charged states, dual to monopole operators, and the Z_k projection of the Osp(4|8) singleton and its tensor products. In particular, we show that the doubleton spectrum may account for N=6 higher spin symmetry enhancement in the limit of vanishing 't Hooft coupling in the boundary Chern-Simons theory.
Van Isacker, P
2010-01-01
The use of dynamical symmetries or spectrum generating algebras for the solution of the nuclear many-body problem is reviewed. General notions of symmetry and dynamical symmetry in quantum mechanics are introduced and illustrated with simple examples such as the SO(4) symmetry of the hydrogen atom and the isospin symmetry in nuclei. Two nuclear models, the shell model and the interacting boson model, are reviewed with particular emphasis on their use of group-theoretical techniques.
Model dependence of the neutron-skin thickness on the symmetry energy
Mondal, C.; Agrawal, B. K.; Centelles, M.; Colò, G.; Roca-Maza, X.; Paar, N.; Viñas, X.; Singh, S. K.; Patra, S. K.
2016-06-01
The model dependence in the correlations of the neutron-skin thickness in heavy nuclei with various symmetry-energy parameters is analyzed by using several families of systematically varied microscopic mean-field models. Such correlations show a varying degree of model dependence once the results for all the different families are combined. Some mean-field models associated with similar values of the symmetry-energy slope parameter at saturation density L , and pertaining to different families, yield a greater-than-expected spread in the neutron-skin thickness of the 208Pb nucleus. The effective value of the symmetry-energy slope parameter Leff, determined by using the nucleon density profiles of the finite nucleus and the density derivative S'(ρ ) of the symmetry energy starting from about saturation density up to low densities typical of the surface of nuclei, seems to account for the spread in the neutron-skin thickness for the models with similar L . The differences in the values of Leff are mainly due to the small differences in the nucleon density distributions of heavy nuclei in the surface region and the behavior of the symmetry energy at subsaturation densities.
The exact solution of an octagonal rectangle triangle random tiling
De Gier, J; Gier, Jan de; Nienhuis, Bernard
1996-01-01
We present a detailed calculation of the recently published exact solution of a random tiling model possessing an eight-fold symmetric phase. The solution is obtained using Bethe Ansatz and provides closed expressions for the entropy and phason elastic constants. Qualitatively, this model has the same features as the square-triangle random tiling model. We use the method of P. Kalugin, who solved the Bethe Ansatz equations for the square-triangle tiling, which were found by M. Widom.
Dynamical Electroweak Symmetry Breaking in String Models with D-branes
Kitazawa, Noriaki
2009-01-01
The possibility of dynamical electroweak symmetry breaking by strong coupling gauge interaction in models with D-branes in String Theory is examined. Instead of elementary scalar Higgs doublet fields, the gauge symmetry with strong coupling (technicolor) is introduced. As the first step of this direction, a toy model, which is not fully realistic, is concretely analyzed in some detail. The model consists of D-branes and anti-D-branes at orbifold singularities in (T^2 x T^2 x T^2)/Z_3 which preserves supersymmetry. Supersymmetry is broken through the brane supersymmetry breaking. It is pointed out that the problem of large S parameter in dynamical electroweak symmetry breaking scenario may be solved by natural existence of kinetic term mixings between hypercharge U(1) gauge boson and massive anomalous U(1) gauge bosons. The problems to be solved toward constructing more realistic models are clarified in the analysis.
Maximally Generalized Yang-Mills Model and Dynamical Breaking of Gauge Symmetry
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
A maximally generalized Yang-Mills model, which contains, besides the vector part Vμ, also an axial-vector part Aμ, a scalar part S, a pseudoscalar part P, and a tensor part Tμv, is constructed and the dynamical breaking of gauge symmetry in the model is also discussed. It is shown, in terms of the Nambu-Jona-Lasinio mechanism, that the gauge symmetry breaking can be realized dynamically in the maximally generalized Yang-Mills model. The combination of the maximally generalized Yang-Mills model and the NJL mechanism provides a way to overcome the difficulties related to the Higgs field and the Higgs mechanism in the usual spontaneous symmetry breaking theory.
A model of neutrino mass and dark matter with an accidental symmetry
Directory of Open Access Journals (Sweden)
Amine Ahriche
2015-06-01
Full Text Available We present a model of radiative neutrino mass that automatically contains an accidental Z2 symmetry and thus provides a stable dark matter candidate. This allows a common framework for the origin of neutrino mass and dark matter without invoking any symmetries beyond those of the Standard Model. The model can be probed by direct-detection experiments and μ→e+γ searches, and predicts a charged scalar that can appear at the TeV scale, within reach of collider experiments.
Symmetries of 2-lattices and second order accuracy of the Cauchy--Born Model
Van Koten, Brian
2012-01-01
We show that the Cauchy--Born model of a single-species 2-lattice is second order if the atomistic and continuum kinematics are connected in a novel way. Our proof uses a generalization to 2-lattices of the point symmetry of Bravais lattices. Moreover, by identifying similar symmetries in multi-species pair interaction models, we construct a new stored energy density, using shift-gradients but not strain gradients, that is also second order accurate. These results can be used to develop highly accurate continuum models and atomistic/continuum coupling methods for materials such as graphene, hcp metals, and shape memory alloys.
A (1 + 2-Dimensional Simplified Keller–Segel Model: Lie Symmetry and Exact Solutions. II
Directory of Open Access Journals (Sweden)
Roman Cherniha
2017-01-01
Full Text Available A simplified Keller–Segel model is studied by means of Lie symmetry based approaches. It is shown that a (1 + 2-dimensional Keller–Segel type system, together with the correctly-specified boundary and/or initial conditions, is invariant with respect to infinite-dimensional Lie algebras. A Lie symmetry classification of the Cauchy problem depending on the initial profile form is presented. The Lie symmetries obtained are used for reduction of the Cauchy problem to that of (1 + 1-dimensional. Exact solutions of some (1 + 1-dimensional problems are constructed. In particular, we have proved that the Cauchy problem for the (1 + 1-dimensional simplified Keller–Segel system can be linearized and solved in an explicit form. Moreover, additional biologically motivated restrictions were established in order to obtain a unique solution. The Lie symmetry classification of the (1 + 2-dimensional Neumann problem for the simplified Keller–Segel system is derived. Because Lie symmetry of boundary-value problems depends essentially on geometry of the domain, which the problem is formulated for, all realistic (from applicability point of view domains were examined. Reduction of the the Neumann problem on a strip is derived using the symmetries obtained. As a result, an exact solution of a nonlinear two-dimensional Neumann problem on a finite interval was found.
Shukla, A.; Krishna, S.; Malik, R. P.
2014-12-01
We derive the off-shell nilpotent and absolutely anticommuting Becchi-Rouet-Stora-Tyutin (BRST) and anti-BRST symmetry transformations, corresponding to the (1-form) Yang-Mills (YM) and (2-form) tensorial gauge symmetries of the four (3+1)-dimensional (4D) Freedman-Townsend (FT) model, by exploiting the augmented version of Bonora-Tonin's (BT) superfield approach to BRST formalism where the 4D flat Minkowskian theory is generalized onto the (4, 2)-dimensional supermanifold. One of the novel observations is the fact that we are theoretically compelled to go beyond the horizontality condition (HC) to invoke an additional set of gauge-invariant restrictions (GIRs) for the derivation of the full set of proper (anti-)BRST symmetries. To obtain the (anti-)BRST symmetry transformations, corresponding to the tensorial (2-form) gauge symmetries within the framework of augmented version of BT-superfield approach, we are logically forced to modify the FT-model to incorporate an auxiliary 1-form field and the kinetic term for the antisymmetric (2-form) gauge field. This is also a new observation in our present investigation. We point out some of the key differences between the modified FT-model and Lahiri-model (LM) of the dynamical non-Abelian 2-form gauge theories. We also briefly mention a few similarities.
Symmetry plane model for turbulent flows with vortex generators
Arnaud, Gilles L.; Russell, David A.
1991-01-01
An approximate procedure is proposed for predicting the performance of counterrotating vortex-generator installations in incompressible flow. An inviscid calculation that includes the motion of the vortices is used to obtain crossflow velocities at the boundary-layer edge as a function of initial position, spacing, and strength of the vortices, and local values of the spanwise gradient are then folded into an integral turbulent-boundary layer procedure applied in the plane of symmetry. Special attention is paid to the consistency of the approximations and equations used. The two-dimensional aerodynamics of vortex generator installations on a NACA 0016 airfoil at angle-of-attack are estimated in this manner, and the results compared with experiments carried out with a 30-cm chord wing mounted in a 2.4 x 3.6-m cross-section wind tunnel and tested at chord Reynolds numbers of 0.7 and 1.4 x 10 to the 6th. Agreement in the separation location is found for these complex flows for a range of conditions.
Three-Higgs-doublet models: symmetries, potentials and Higgs boson masses
Energy Technology Data Exchange (ETDEWEB)
Keus, Venus [School of Physics and Astronomy, University of Southampton,Southampton, SO17 1BJ (United Kingdom); Department of Physics, Royal Holloway, University of London,Egham Hill, Egham TW20 0EX (United Kingdom); Particle Physics Department, Rutherford Appleton Laboratory,Chilton, Didcot, Oxon OX11 0QX (United Kingdom); King, Stephen F. [School of Physics and Astronomy, University of Southampton,Southampton, SO17 1BJ (United Kingdom); Moretti, Stefano [School of Physics and Astronomy, University of Southampton,Southampton, SO17 1BJ (United Kingdom); Particle Physics Department, Rutherford Appleton Laboratory,Chilton, Didcot, Oxon OX11 0QX (United Kingdom)
2014-01-13
We catalogue and study three-Higgs-doublet models in terms of all possible allowed symmetries (continuous and discrete, Abelian and non-Abelian), where such symmetries may be identified as flavour symmetries of quarks and leptons. We analyse the potential in each case, and derive the conditions under which the vacuum alignments (0,0,v), (0,v,v) and (v,v,v) are minima of the potential. For the alignment (0,0,v), relevant for dark matter models, we calculate the corresponding physical Higgs boson mass spectrum. Motivated by supersymmetry, we extend the analysis to the case of three up-type Higgs doublets and three down-type Higgs doublets (six doublets in total). Many of the results are also applicable to flavon models where the three Higgs doublets are replaced by three electroweak singlets.
Noether symmetries and anisotropic universe models in f(R, T) gravity
Sharif, M.; Nawazish, Iqra
2017-08-01
This paper investigates the existence of Noether symmetries of some anisotropic homogeneous universe models in non-minimally coupled f(R, T) gravity (R and T represent Ricci scalar and trace of the energy-momentum tensor). We evaluate symmetry generators and the corresponding conserved quantities for two models of this theory admitting direct and indirect non-minimal curvature-matter coupling. We also discuss exact solutions for dust as well as non-dust matter distribution and study the physical behavior of some cosmological parameters through these solutions. For dust distribution, the exact solution corresponds to power-law expansion and Einstein universe while exponential expansion appears for non-dust matter. The graphical analysis of these solutions and cosmological parameters provide consistent results with recent observations about accelerated cosmic expansion. We conclude that Noether symmetry generators and conserved quantities exist for both models.
Conformal symmetry of the critical 3D Ising model inside a sphere
Cosme, Catarina; Penedones, Joao
2015-01-01
We perform Monte-Carlo simulations of the three-dimensional Ising model at the critical temperature and zero magnetic field. We simulate the system in a ball with free boundary conditions on the two dimensional spherical boundary. Our results for one and two point functions in this geometry are consistent with the predictions from the conjectured conformal symmetry of the critical Ising model.
Baskaran, G.
1989-01-01
Using a nonmean-field approach the triangular-lattice S = 1/2 Heisenberg antiferromagnet with nearest- and next-nearest-neighbor couplings is shown undergo an Ising-type phase transition into a chiral-symmetry-broken phase (Kalmeyer-Laughlin-like state) at small T. Removal of next-nearest-neighbor coupling introduces a local Z2 symmetry, thereby suppressing any finite-T chiral order.
Gauge-Higgs Unification Models in Six Dimensions with S2/Z2 Extra Space and GUT Gauge Symmetry
Directory of Open Access Journals (Sweden)
Cheng-Wei Chiang
2012-01-01
Full Text Available We review gauge-Higgs unification models based on gauge theories defined on six-dimensional spacetime with S2/Z2 topology in the extra spatial dimensions. Nontrivial boundary conditions are imposed on the extra S2/Z2 space. This review considers two scenarios for constructing a four-dimensional theory from the six-dimensional model. One scheme utilizes the SO(12 gauge symmetry with a special symmetry condition imposed on the gauge field, whereas the other employs the E6 gauge symmetry without requiring the additional symmetry condition. Both models lead to a standard model-like gauge theory with the SU(3×SU(2L×U(1Y(×U(12 symmetry and SM fermions in four dimensions. The Higgs sector of the model is also analyzed. The electroweak symmetry breaking can be realized, and the weak gauge boson and Higgs boson masses are obtained.
Energy Technology Data Exchange (ETDEWEB)
Fernandez-Ramirez, C. [Grupo de Fisica Nuclear, Departamento de Fisica Atomica, Molecular y Nuclear, Facultad de Ciencias Fisicas, Universidad Complutense de Madrid, Avda. Complutense s/n, E-28040 Madrid (Spain)], E-mail: cesar@nuc2.fis.ucm.es; Moya de Guerra, E. [Grupo de Fisica Nuclear, Departamento de Fisica Atomica, Molecular y Nuclear, Facultad de Ciencias Fisicas, Universidad Complutense de Madrid, Avda. Complutense s/n, E-28040 Madrid (Spain); Instituto de Estructura de la Materia, CSIC, Serrano 123, E-28006 Madrid (Spain); Udias, J.M. [Grupo de Fisica Nuclear, Departamento de Fisica Atomica, Molecular y Nuclear, Facultad de Ciencias Fisicas, Universidad Complutense de Madrid, Avda. Complutense s/n, E-28040 Madrid (Spain)
2008-02-21
We investigate the importance of crossing symmetry in effective field models and the effects of phenomenological nucleon resonance widths on the paradigmatic case of pion photoproduction. We use reaction models containing four star resonances up to 1.8 GeV ({delta}(1232), N(1440), N(1520), N(1535), {delta}(1620), N(1650), {delta}(1700), and N(1720)) with different prescriptions for crossed terms and widths, to fit the latest world database on pion photoproduction. We compare {chi}{sup 2} results from selected multipoles and fits. The {chi}{sup 2} is highly dependent on the fulfillment of crossing symmetry and the inclusion of u channels.
A bilayer Double Semion model with symmetry-enriched topological order
Ortiz, L.; Martin-Delgado, M. A.
2016-12-01
We construct a new model of two-dimensional quantum spin systems that combines intrinsic topological orders and a global symmetry called flavour symmetry. It is referred as the bilayer Doubled Semion model (bDS) and is an instance of symmetry-enriched topological order. A honeycomb bilayer lattice is introduced to combine a Double Semion Topological Order with a global spin-flavour symmetry to get the fractionalization of its quasiparticles. The bDS model exhibits non-trivial braiding self-statistics of excitations and its dual model constitutes a Symmetry-Protected Topological Order with novel edge states. This dual model gives rise to a bilayer Non-Trivial Paramagnet that is invariant under the flavour symmetry and the well-known spin flip symmetry. On the one hand, the Hermele model is constructed with a square lattice in a multilayer structure that forms a quasi-three-dimensional model, but the square lattice cannot support a DS model. (see Appendix C and [39]). On the other hand, the Levin-Gu method is realized on a single hexagonal layer, but we would need a multilayer realization of that construction. This is problematic since the necessary coordination condition (3) is incompatible with a multilayer structure of honeycomb layers. Interestingly enough, we can rephrase this compatibility problem between these two fractionalization methods as a compatibility condition between global symmetries. The key point is to realize that the Levin-Gu method deals with a spin-flip symmetry, e.g. G = Z2fs, explicitly shown in the spin model introduced in Section 4, while the Hermele method is about a spin-flavour symmetry among lattice layers, e.g. G = Z2fv. This spin-favour symmetry is present explicitly in the string model presented in Eq. (26).We hereby summarize briefly some of our main results:i/ We have constructed a bilayer Doubled Semion (bDS) model that has intrinsic topological orders of type G =Z2 and is invariant under the global symmetry group G = Z2fv
Symmetry breaking patterns of the 3-3-1 model at finite temperature
Energy Technology Data Exchange (ETDEWEB)
Borges, J.S. [Universidade do Estado do Rio de Janeiro, Departamento de Fisica de Altas Energias, Rio de Janeiro, RJ (Brazil); Ramos, Rudnei O. [Universidade do Estado do Rio de Janeiro, Departamento de Fisica Teorica, Rio de Janeiro, RJ (Brazil)
2016-06-15
We consider the minimal version of an extension of the standard electroweak model based on the SU(3){sub c} x SU(3){sub L} x U(1){sub X} gauge symmetry (the 3-3-1 model). We analyze the most general potential constructed from three scalars in the triplet representation of SU(3){sub L}, whose neutral components develop nonzero vacuum expectation values, giving mass for all the model's massive particles. For different choices of parameters, we obtain the particle spectrum for the two symmetry breaking scales: one where the SU(3){sub L} x U(1){sub X} group is broken down to SU(2){sub L} x U(1){sub Y} and a lower scale similar to the standard model one. Within the considerations used, we show that the model encodes two first-order phase transitions, respecting the pattern of symmetry restoration. The last transition, corresponding to the standard electroweak one, is found to be very weak first-order, most likely turning second-order or a crossover in practice. However, the first transition in this model can be strongly first-order, which might happen at a temperature not too high above the second one. We determine the respective critical temperatures for symmetry restoration for the model. (orig.)
Symmetry-preserving contact interaction model for heavy-light mesons
Serna, F E; Krein, G
2016-01-01
We use a symmetry-preserving regularization method of ultraviolet divergences in a vector-vector contact interac- tion model for low-energy QCD. The contact interaction is a representation of nonperturbative kernels used Dyson-Schwinger and Bethe-Salpeter equations. The regularization method is based on a subtraction scheme that avoids standard steps in the evaluation of divergent integrals that invariably lead to symmetry violation. Aiming at the study of heavy-light mesons, we have implemented the method to the pseudoscalar pion and Kaon mesons. We have solved the Dyson-Schwinger equation for the u, d and s quark propagators, and obtained the bound-state Bethe-Salpeter amplitudes in a way that the Ward-Green-Takahashi identities reflecting global symmetries of the model are satisfied for arbitrary routing of the momenta running in loop integrals.
Non-anomalous flavor symmetries and SU(6) x SU(2) sub R model
Abe, Y; Hattori, C; Hayashi, T; Ito, M; Matsuda, M; Matsuoka, T
2002-01-01
We introduce the flavor symmetry Z sub M x Z sub N x D4 into the SU(6) x SU(2) sub R string-inspired model. The cyclic group Z sub M and the dihedral group D sub 4 are R symmetries, while Z sub N is a non-R symmetry. By imposing the anomaly-free conditions on the model, we obtain a viable solution under many phenomenological constraints coming from the particle spectra. For the neutrino sector, we find a LMA-MSW solution but no SMA-MSW solution. The solution includes phenomenologically acceptable results concerning fermion masses and mixings and also concerning hierarchical energy scales including the GUT scale, the mu scale and the Majorana mass scale of R-handed neutrinos. (author)
External Fields and Chiral Symmetry Breaking in the Sakai-Sugimoto Model
Johnson, Clifford V
2008-01-01
Using the Sakai-Sugimoto model we study the effect of an external magnetic field on the dynamics of fundamental flavours in both the confined and deconfined phases of a large N_c gauge theory. We find that an external magnetic field promotes chiral symmetry breaking, consistent with the ``magnetic catalysis'' observed in the field theory literature, and seen in other studies using holographic duals. The external field increases the separation between the deconfinement temperature and the chiral symmetry restoring temperature. In the deconfined phase we investigate the temperature-magnetic field phase diagram and observe, for example, there exists a maximum critical temperature (at which symmetry is restored) for very large magnetic field. We find that this and certain other phenomena persist for the Sakai-Sugimoto type models with probe branes of diverse dimensions. We comment briefly on the dynamics in the presence of an external electric field.
Classically conformal radiative neutrino model with gauged B−L symmetry
Directory of Open Access Journals (Sweden)
Hiroshi Okada
2016-09-01
Full Text Available We propose a classically conformal model in a minimal radiative seesaw, in which we employ a gauged B−L symmetry in the standard model that is essential in order to work the Coleman–Weinberg mechanism well that induces the B−L symmetry breaking. As a result, nonzero Majorana mass term and electroweak symmetry breaking simultaneously occur. In this framework, we show a benchmark point to satisfy several theoretical and experimental constraints. Here theoretical constraints represent inert conditions and Coleman–Weinberg condition. Experimental bounds come from lepton flavor violations (especially μ→eγ, the current bound on the Z′ mass at the CERN Large Hadron Collider, and neutrino oscillations.
Symmetry-preserving contact interaction model for heavy-light mesons
Energy Technology Data Exchange (ETDEWEB)
Serna, F. E.; Brito, M. A.; Krein, G. [Instituto de Física Teórica, Universidade Estadual Paulista (Brazil); Rua Dr. Bento Teobaldo Ferraz, 271 - Bloco II, 01140-070 São Paulo, SP (Brazil)
2016-01-22
We use a symmetry-preserving regularization method of ultraviolet divergences in a vector-vector contact interaction model for low-energy QCD. The contact interaction is a representation of nonperturbative kernels used Dyson-Schwinger and Bethe-Salpeter equations. The regularization method is based on a subtraction scheme that avoids standard steps in the evaluation of divergent integrals that invariably lead to symmetry violation. Aiming at the study of heavy-light mesons, we have implemented the method to the pseudoscalar π and K mesons. We have solved the Dyson-Schwinger equation for the u, d and s quark propagators, and obtained the bound-state Bethe-Salpeter amplitudes in a way that the Ward-Green-Takahashi identities reflecting global symmetries of the model are satisfied for arbitrary routing of the momenta running in loop integrals.
Correspondences between WZNW models and CFTs with W-algebra symmetry
Creutzig, Thomas; Ronne, Peter B
2015-01-01
We study theories with W-algebra symmetries and their relation to WZNW models on (super-)groups. Correlation functions of the WZNW models are expressed in terms of correlators of CFTs with W-algebra symmetry. The symmetries of the theories involved in these correspondences are related by the Drinfeld-Sokolov reduction of Lie algebras to W-algebras. The W-algebras considered in this paper are the Bershadsky-Polyakov algebra for sl(3) and the quasi-superconformal algebra for generic sl(N|M). The quantum W-algebras obtained from affine sl(N) are constructed using embeddings of sl(2) into sl(N), and these can in turn be characterized by partitions of N. The above cases correspond to \\underline{N+2} = \\underline{2} + N \\underline{1} and its supergroup extension. Finally, sl(2N) and the correspondence corresponding to \\underline{2N} = N \\underline{2} is also analyzed.
Detailed Description of Mixed Symmetry States in 94Mo Using Interacting Boson Model
Institute of Scientific and Technical Information of China (English)
LONG GuiLu; F.H. Al-Khudair
2002-01-01
We have investigated the low-lying collective states and electromagnetic transitions in 94Mo within the framework of the interacting boson model. The influence of model parameters on the energy levels and electromagnetic properties has been investigated. The analysis of the obtained results and the parameter values predict that the 23+state is the lowest mixed symmetry state with pure F = Fmax - 1 in this nucleus. The calculated results predicate that the 25+ (two-Q-phonon) mixed symmetry state is closed to the J = 2+ at 2.870 MeV in the experimental data, and the 2.965 MeV state is the lowest mixed symmetry with J = 3+.
Shukla, A; Malik, R P
2013-01-01
We derive the off-shell nilpotent and absolutely anticommuting Becchi-Rouet-Stora-Tyutin (BRST) and anti-BRST symmetry transformations, corresponding to the (1-form) Yang-Mills (YM) and (2-form) tensor gauge symmetries of the four (3 + 1)-dimensional (4D) Freedman-Townsend (FT) model, by exploiting the augmented version of Bonora-Tonin's (BT) superfield approach to BRST formalism where the 4D flat Minkowskian theory is generalized onto the (4, 2)-dimensional supermanifold. One of the novel observations is the fact that we are theoretically compelled to go beyond the horizontality condition (HC) to invoke an additional set of gauge-invariant restrictions (GIRs) for the derivation of the full set of proper (anti-)BRST symmetries. To obtain the (anti-)BRST symmetry transformations, corresponding to the tensorial (2-form) gauge symmetries (within the framework of augmented version of BT-superfield approach), we are theoretically forced to modify the FT-model to incorporate an auxiliary 1-form field and the kineti...
Independent particle model of spontaneous symmetry breaking in planar π-electron systems
Thiamová, G.; Paldus, J.
2008-03-01
The singlet stability of symmetry adapted (SA), restricted Hartree-Fock (RHF) solutions, and the implied symmetry breaking for several planar, π-electron systems, is investigated using the semiempirical Pariser-Parr-Pople Hamiltonian in the whole range of the coupling constant. We focus here on highly symmetric cyclic polyenes C10H10 and C14H14 and their various distorted analogues of lower symmetry, in particular on the perimeter models of naphthalene and anthracene (p-naphthalene and p-anthracene) modeling the so-called [n]-annulenes. Relying on earlier results for general systems with conjugated double-bonds, we explore the character and properties of both the SA and broken-symmetry (BS) RHF solutions for these systems and relate their behavior to those of highly symmetric cyclic polyenes and corresponding polyacenes. In this way we are able to provide a better understanding of the spontaneous symmetry breaking in these systems at the Hartree-Fock level of approximation.
Anomaly-free discrete gauge symmetries in Froggatt-Nielsen models
Energy Technology Data Exchange (ETDEWEB)
Luhn, C.
2006-05-15
Discrete symmetries (DS) can forbid dangerous B- and L-violating operators in the supersymmetric Lagrangian. Due to the violation of global DSs by quantum gravity effects, the introduced DS should be a remnant of a spontaneously broken local gauge symmetry. Demanding anomaly freedom of the high-energy gauge theory, we determine all family-independent anomaly-free Z{sub N} symmetries which are consistent with the trilinear MSSM superpotential terms in Part I. We find one outstanding Z{sub 6} symmetry, proton hexality P{sub 6}, which prohibits all B- and L-violating operators up to dimension five, except for the Majorana neutrino mass terms LH{sub u}LH{sub u}. In Part II, we combine the idea that a DS should have a gauge origin with the scenario of Froggatt and Nielsen (FN). We construct concise U(1){sub X} FN models in which the Z{sub 3} symmetry baryon triality, B{sub 3}, arises from U(1){sub X} breaking. We choose this specific DGS because it allows for R-parity violating interactions; thus neutrino masses can be explained without introducing right-handed neutrinos. We find six phenomenologically viable B{sub 3}-conserving FN models. (orig.)
Up and down cascade in a dynamo model: spontaneous symmetry breaking.
Blanter, E M; Narteau, C; Shnirman, M G; Le Mouël, J L
1999-05-01
A multiscale turbulent model of dynamo is proposed. A secondary magnetic field is generated from a primary field by a flow made of turbulent helical vortices (cyclones) of different ranges, and amplified by an up and down cascade mechanism. The model displays symmetry breakings of different ranges although the system construction is completely symmetric. Large-scale symmetry breakings for symmetric conditions of the system evolution are investigated for all kinds of cascades: pure direct cascade, pure inverse cascade, and up and down cascade. It is shown that long lived symmetry breakings of high scales can be obtained only in the case of the up and down cascade. The symmetry breakings find expression in intervals of constant polarity of the secondary field (called chrons of the geomagnetic field). Long intervals of constant polarity with quick reversals are obtained in the model; conditions for such a behavior are investigated. Strong variations of the generated magnetic field during intervals of constant polarity are also observed in the model. Possible applications of the model to geodynamo modeling and various directions of future investigation are briefly discussed.
Symmetry: modeling the effects of masking noise, axial cueing and salience.
Chen, Chien-Chung; Tyler, Christopher W
2010-04-06
Symmetry detection is an interesting probe of pattern processing because it requires the matching of novel patterns without the benefit of prior recognition. However, there is evidence that prior knowledge of the axis location plays an important role in symmetry detection. We investigated how the prior information about the symmetry axis affects symmetry detection under noise-masking conditions. The target stimuli were random-dot displays structured to be symmetric about vertical, horizontal, or diagonal axes and viewed through eight apertures (1.2 degrees diameter) evenly distributed around a 6 degrees diameter circle. The information about axis orientation was manipulated by (1) cueing of axis orientation before the trial and (2) varying axis salience by including or excluding the axis region within the noise apertures. The percentage of correct detection of the symmetry was measured at for a range of both target and masking noise densities. The threshold vs. noise density function was flat at low noise density and increased with a slope of 0.75-0.8 beyond a critical density. Axis cueing reduced the target threshold 2-4 fold at all noise densities while axis salience had an effect only at high noise density. Our results are inconsistent with an ideal observer or signal-to-noise account of symmetry detection but can be explained by a multiple-channel model is which the response in each channel is the ratio between the nonlinear transform of the responses of sets of early symmetry detectors and the sum of external and intrinsic sources of noise.
Workshop on the CKM Unitarity Triangle
Patrice Loïez
2002-01-01
The CKM Unitarity Triangle Workshop is meant to provide an opportunity for an intense and fruitful exchange of ideas between experimentalists and theorists to assess the present knowledge on fundamental parameters from the data of LEP and other colliders, to define an agenda of future measurements to further probe the model assumptions employed in the interpretation of the data and to indicate paths for the B physics programme at LHC.
Factorisation fits and the unitarity triangle
De Groot, N; Whittingham, I B
2003-01-01
In this paper we present fits to charmless hadronic B decay data from the BaBar, Belle and Cleo experiments using models by Beneke et. al. and Ciuchini et al. When we include the data from pseudo-scalar vector decays (PV) the current experimental results favour the inclusions of a so-called "charming penguin" term. We also present fit results for the Unitary Triangle parameters and the CP violating asymmetries
Gampe, David; Ludwig, Ralf; Qahman, Khalid; Afifi, Samir
2016-02-01
In the Mediterranean region, particularly in the Gaza strip, an increased risk of drought is among the major concerns related to climate change. The impacts of climate change on water availability, drought risk and food security can be assessed by means of hydro-climatological modeling. However, the region is prone to severe observation data scarcity, which limits the potential for robust model parameterization, calibration and validation. In this study, the physically based, spatially distributed hydrological model WaSiM is parameterized and evaluated using satellite imagery to assess hydrological quantities. The Triangle Method estimates actual evapotranspiration (ETR) through the Normalized Difference Vegetation Index (NDVI) and land surface temperature (LST) provided by Landsat TM imagery. So-derived spatially distributed evapotranspiration is then used in two ways: first a subset of the imagery is used to parameterize the irrigation module of WaSiM and second, withheld scenes are applied to evaluate the performance of the hydrological model in the data scarce study area. The results show acceptable overall correlation with the validation scenes (r=0.53) and an improvement over the usual irrigation parameterization scheme using land use information exclusively. This model setup is then applied for future drought risk assessment in the Gaza Strip using a small ensemble of four regional climate projections for the period 2041-2070. Hydrological modeling reveals an increased risk of drought, assessed with an evapotranspiration index, compared to the reference period 1971-2000. Current irrigation procedures cannot maintain the agricultural productivity under future conditions without adaptation.
Icosahedral symmetry described by an incommensurately modulated crystal structure model
DEFF Research Database (Denmark)
Wolny, Janusz; Lebech, Bente
1986-01-01
A crystal structure model of an incommensurately modulated structure is presented. Although six different reciprocal vectors are used to describe the model, all calculations are done in three dimensions making calculation of the real-space structure trivial. Using this model, it is shown that both...
CP and other Symmetries of Symmetries
Trautner, Andreas
2016-01-01
Outer automorphisms of symmetries ("symmetries of symmetries") in relativistic quantum field theories are studied, including charge conjugation (C), space-reflection (P) , and time-reversal (T) transformations. The group theory of outer automorphisms is pedagogically introduced and it is shown that CP transformations are special outer automorphisms of the global, local, and space-time symmetries of a theory. It is shown that certain discrete groups allow for a group theoretical prediction of parameter independent CP violating complex phases with fixed geometrical values. The remainder of this thesis pioneers the study of outer automorphisms which are not related to C, P, or T. It is shown how outer automorphisms, in general, relate symmetry invariants and, in theories with spontaneous symmetry breaking, imply relations between different vacuum expectation values. Thereby, outer automorphisms can give rise to emergent symmetries. An example model with a discrete symmetry and three copies of the Standard Model ...
Model dependence of the neutron-skin thickness on the symmetry energy
Mondal, C; Centelles, M; Colò, G; Roca-Maza, X; Paar, N; Viñas, X; Singh, S K; Patra, S K
2016-01-01
The model dependence in the correlations of the neutron-skin thickness in heavy nuclei with various symmetry energy parameters is analyzed by using several families of systematically varied microscopic mean field models. Such correlations show a varying degree of model dependence once the results for all the different families are combined. Some mean field models associated with similar values of the symmetry energy slope parameter at saturation density $L$, and pertaining to different families, yield a greater-than-expected spread in the neutron-skin thickness of the $^{208}$Pb nucleus. The effective value of the symmetry energy slope parameter $L_{\\rm eff}$, determined by using the nucleon density profiles of the finite nucleus and the density derivative $S^\\prime(\\rho)$ of the symmetry energy starting from about saturation density up to low densities typical of the surface of nuclei, seems to account for the spread in the neutron-skin thickness for the models with similar $L$. The differences in the values...
Symmetry analysis for hyperbolic equilibria using a TB/dengue fever model
Massoukou, R. Y. M.'Pika; Govinder, K. S.
2016-08-01
We investigate the interplay between Lie symmetry analysis and dynamical systems analysis. As an example, we take a toy model describing the spread of TB and dengue fever. We first undertake a comprehensive dynamical systems analysis including a discussion about local stability. For those regions in which such analyzes cannot be translated to global behavior, we undertake a Lie symmetry analysis. It is shown that the Lie analysis can be useful in providing information for systems where the (local) dynamical systems analysis breaks down.
Assessing the effects of symmetry on motif discovery and modeling.
Directory of Open Access Journals (Sweden)
Lala M Motlhabi
Full Text Available BACKGROUND: Identifying the DNA binding sites for transcription factors is a key task in modeling the gene regulatory network of a cell. Predicting DNA binding sites computationally suffers from high false positives and false negatives due to various contributing factors, including the inaccurate models for transcription factor specificity. One source of inaccuracy in the specificity models is the assumption of asymmetry for symmetric models. METHODOLOGY/PRINCIPAL FINDINGS: Using simulation studies, so that the correct binding site model is known and various parameters of the process can be systematically controlled, we test different motif finding algorithms on both symmetric and asymmetric binding site data. We show that if the true binding site is asymmetric the results are unambiguous and the asymmetric model is clearly superior to the symmetric model. But if the true binding specificity is symmetric commonly used methods can infer, incorrectly, that the motif is asymmetric. The resulting inaccurate motifs lead to lower sensitivity and specificity than would the correct, symmetric models. We also show how the correct model can be obtained by the use of appropriate measures of statistical significance. CONCLUSIONS/SIGNIFICANCE: This study demonstrates that the most commonly used motif-finding approaches usually model symmetric motifs incorrectly, which leads to higher than necessary false prediction errors. It also demonstrates how alternative motif-finding methods can correct the problem, providing more accurate motif models and reducing the errors. Furthermore, it provides criteria for determining whether a symmetric or asymmetric model is the most appropriate for any experimental dataset.
Perilaku Kecurangan Akademik Mahasiswa Akuntansi: Dimensi Fraud Triangle
Directory of Open Access Journals (Sweden)
Annisa Fitriana
2012-08-01
Full Text Available This study examine the dimensions of Fraud Triangle to explain this effect on the student’s cheating. This study uses a model of research The Academic Dishonesty Scale modifi cation. Sample in this study were 217 accounting students in Brawijaya University Malang. Data was collected through survey methods. This study have obtained empirical evidence that student’s cheating behaviorwas determined by the dimensions of the Fraud Triangle consists of incentive, opportunity and rationalization.
Search for symmetries beyond the Standard Model with ATLAS
Tal Hod, Noam; The ATLAS collaboration
2015-01-01
Searches for new physics beyond the Standard Model (SM) at the LHC are mainly driven by two approaches: a signature-based search where one looks for a deviation from the SM prediction in event yield or kinematic properties, and a more theory-oriented approach where the search is designed to look for specific signatures/topologies predicted by certain beyond standard model (BSM ) scenarios. Extensive searches for such signatures have been performed in ATLAS at LHC Run 1 in the context of Supersymmetry, Extended Gauge models, Technicolor, Little Higgs, Extra Dimensions, Left-Right symmetric models, and many other BSM scenarios. Highlights from these searches are presented.
Phenomenology of the standard model under conditions of spontaneously broken mirror symmetry
Energy Technology Data Exchange (ETDEWEB)
Dyatlov, I. T., E-mail: dyatlov@thd.pnpi.spb.ru [National Research Center Kurchatov Institute, Petersburg Nuclear Physics Institute (Russian Federation)
2017-03-15
Spontaneously broken mirror symmetry is able to reproduce observed qualitative properties of weak mixing for quark and leptons. Under conditions of broken mirror symmetry, the phenomenology of leptons—that is, small neutrino masses and a mixing character other than that in the case of quarks—requires the Dirac character of the neutrinos and the existence of processes violating the total lepton number. Such processes involve heavy mirror neutrinos; that is, they proceed at very high energies. Here, CP violation implies that a P-even mirror-symmetric Lagrangian must simultaneously be T-odd and, according to the CPT theorem, C-odd. All these properties create preconditions for the occurrence of leptogenesis, which is a mechanism of the emergence of the baryon–lepton asymmetry of the universe in models featuring broken mirror symmetry.
Formation and local symmetry of the Holstein polaron in the t-J model
Ma, Han; Lee, T. K.; Chen, Yan
2013-04-01
The formation and local symmetry of a spin-lattice polaron has been investigated semiclassically in planar Holstein t-J-like models within the exact diagonalization method. Due to the interplay of strong correlations and electron-lattice interaction, the doped hole may either move freely or lead to the localized spin-lattice distortion and form a Holstein polaron. The formation of a polaron breaks the translational symmetry by suppression of antiferromagnetic correlations and inducement of ferromagnetic correlations locally. Moreover, the breaking of local rotational symmetry around the polaron has been shown. The ground state is generically a parity singlet and the first excited state may be a parity doublet. Further consequences of the density of states spectra for comparison with scanning tunneling microscopy experiments are discussed.
The role of conformal symmetry in gravity and the standard model
Lucat, Stefano
2016-01-01
In this paper we consider conformal symmetry in the context of manifolds with general affine connection. We extend the conformal transformation law of the metric to a general metric compatible affine connection, and find that it is a symmetry of both the geodesic equation and the Riemann tensor. We derive the generalised Jacobi equation and Raychaudhuri equation and show that they are both conformally invariant. Using the geodesic deviation~(Jacobi) equation we analyse the behaviour of geodesics in different conformal frames. Since we find that our version of conformal symmetry is exact in classical pure Einstein's gravity, we ask whether one can extend it to the standard model. We find that it is possible to write conformal invariant lagrangians in any dimensions for vector, fermion and scalar fields, but that such lagrangians are only gauge invariant in four dimensions. Provided one introduces a dilaton field, gravity can be conformally coupled to matter.
Contact terms and duality symmetry in the critical dissipative Hofstadter model
Freed, D E
1993-01-01
The dissipative Hofstadter model describes the quantum mechanics of a charged particle in two dimensions subject to a periodic potential, uniform magnetic field, and dissipative force. Its phase diagram exhibits an SL(2,Z) duality symmetry and has an infinite number of critical circles in the dissipation/magnetic field plane. In addition, multi-critical points on a particular critical circle correspond to non-trivial solutions of open string theory. The duality symmetry is expected to provide relations between correlation functions at different multi-critical points. Many of these correlators are contact terms. However we expect them to have physical significance because under duality they transform into functions that are non-zero for large separations of the operators. Motivated by the search for exact, regulator independent solutions for these contact terms, in this paper we derive many properties and symmetries of the coordinate correlation functions at the special multi-critical points. In particular, we...
The role of conformal symmetry in gravity and the standard model
Lucat, Stefano; Prokopec, Tomislav
2016-12-01
In this paper we consider conformal symmetry in the context of manifolds with general affine connection. We extend the conformal transformation law of the metric to a general metric compatible affine connection, and find that it is a symmetry of both the geodesic equation and the Riemann tensor. We derive the generalised Jacobi equation and Raychaudhuri equation and show that they are both conformally invariant. Using the geodesic deviation (Jacobi) equation we analyse the behaviour of geodesics in different conformal frames. Since we find that our version of conformal symmetry is exact in classical pure Einstein's gravity, we ask whether one can extend it to the standard model. We find that it is possible to write conformal invariant Lagrangians in any dimensions for vector, fermion and scalar fields, but that such Lagrangians are only gauge invariant in four dimensions. Provided one introduces a dilaton field, gravity can be conformally coupled to matter.
A4 and CP symmetry and a model with maximal CP violation
Li, Cai-Chang; Lu, Jun-Nan; Ding, Gui-Jun
2016-12-01
We study a second CP symmetry compatible with the A4 flavor group, which interchanges the representations 1‧ and 1″. We analyze the lepton mixing patterns arising from the A4 and CP symmetry broken to residual subgroups Z3 and Z2 × CP in the charged lepton and neutrino sectors respectively. One phenomenologically viable mixing pattern is found, and it predicts maximal atmospheric mixing angle as well as maximal Dirac CP phase, trivial Majorana phases and the correlation sin2 θ12cos2 θ13 = 1 / 3. We construct a concrete model based on the A4 and CP symmetry, the above interesting mixing pattern is achieved, the observed charged lepton mass hierarchy is reproduced, and the reactor mixing angle θ13 is of the correct order.
$A_4$ and CP symmetry and a model with maximal CP violation
Li, Cai-Chang; Ding, Gui-Jun
2016-01-01
We study a second CP symmetry compatible with the $A_4$ flavor group, which interchanges the representations $\\mathbf{1}'$ and $\\mathbf{1}"$. We analyze the lepton mixing patterns arising from the $A_4$ and CP symmetry broken to residual subgroups $Z_3$ and $Z_2\\times CP$ in the charged lepton and neutrino sectors respectively. One phenomenologically viable mixing pattern is found, and it predicts maximal atmospheric mixing angle as well as maximal Dirac CP phase, trivial Majorana phase and the correlation $\\sin^2\\theta_{12}\\cos^2\\theta_{13}=1/3$. We construct a concrete model based on the $A_4$ and CP symmetry, the above interesting mixing pattern is achieved, the observed charged lepton mass hierarchy is reproduced, and the reactor mixing angle $\\theta_{13}$ is of the correct order.
Explicit and Dynamical Chiral Symmetry Bresking in an Effective Quark-Quark Interaction Model
Institute of Scientific and Technical Information of China (English)
宗红石; 吴小华; 侯丰尧; 赵恩广
2004-01-01
A method for obtaining the small current quark mass effect on the dressed quark propagator from an effective quark-quark interaction model is developed. Within this approach both the explicit and dynamical chiral symmetry breakings are analysed. A comparison with the previous results is given.
Collider and dark matter searches in the inert doublet model from Peccei-Quinn symmetry
Alves, Alexandre; Camargo, Daniel A.; Dias, Alex G.; Longas, Robinson; Nishi, Celso C.; Queiroz, Farinaldo S.
2016-10-01
Weakly Interacting Massive Particles (WIMPs) and axions are arguably the most compelling dark matter candidates in the literature. Could they coexist as dark matter particles? More importantly, can they be incorporated in a well motivated framework in agreement with experimental data? In this work, we show that this two component dark matter can be realized in the Inert Doublet Model in an elegant and natural manner by virtue of the spontaneous breaking of a Peccei-Quinn U(1) P Q symmetry into a residual {Z}_2 symmetry. The WIMP stability is guaranteed by the {Z}_2 symmetry and a new dark matter component, the axion, arises. There are two interesting outcomes: (i) vector-like quarks needed to implement the Peccei-Quinn symmetry in the model may act as a portal between the dark sector and the SM fields with a supersymmetry-type phenomenology at colliders; (ii) two-component Inert Doublet Model re-opens the phenomenologically interesting 100-500 GeV mass region. We show that the model can successfully realize a two component dark matter framework and at the same time avoid low and high energy physics constraints such as monojet and dijet plus missing energy, as well as indirect and direct dark matter detection bounds.
Pion Susceptibilities of the Vacuum in a Modified Global Colour Symmetry Model
Institute of Scientific and Technical Information of China (English)
ZONG Hong-Shi; WU Xiao-Hua; DING Xiao-Ping; L0 Xiao-Fu; ZHAO En-Guang
2001-01-01
Based on a modified version of the global color symmetry model, the pion susceptibilities of vacuum needed in the QCD sum rule external-field method for the coupling of pseudoscalar current to hadron have bean calculated beyond the vacuum saturation approximation. Comparison with the previous estimations has been given.
Symmetry Reductions of a 1.5-Layer Ocean Circulation Model
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
The (2+1)-dimensional nonlinear 1.5-layer ocean circulation model without external wind stress forcing is analyzed by using the classical Lie group approach. Some Lie point symmetries and their corresponding two-dimensional reduction equations are obtained.
Provable first-order transitions for nonlinear vector and gauge models with continuous symmetries
Enter, Aernout C.D. van; Shlosman, Senya B.
2005-01-01
We consider various sufficiently nonlinear vector models of ferromagnets, of nematic liquid crystals and of nonlinear lattice gauge theories with continuous symmetries. We show, employing the method of Reflection Positivity and Chessboard Estimates, that they all exhibit first-order transitions in t
Collider and dark matter searches in the inert doublet model from Peccei-Quinn symmetry
Energy Technology Data Exchange (ETDEWEB)
Alves, Alexandre [Departamento de Ciências Exatas e da Terra, Universidade Federal de São Paulo,Diadema-SP, 09972-270 (Brazil); Camargo, Daniel A.; Dias, Alex G. [Universidade Federal do ABC, Centro de Ciências Naturais e Humanas,09210-580, Santo André-SP (Brazil); Longas, Robinson [Instituto de Física, Universidad de Antioquia,Calle 70 No. 52-21, Medellín (Colombia); Nishi, Celso C. [Universidade Federal do ABC, Centro de Matemática, Computação e Cognição Naturais,09210-580, Santo André-SP (Brazil); Queiroz, Farinaldo S. [Max-Planck-Institut fur Kernphysik,Saupfercheckweg 1, 69117 Heidelberg (Germany)
2016-10-04
Weakly Interacting Massive Particles (WIMPs) and axions are arguably the most compelling dark matter candidates in the literature. Could they coexist as dark matter particles? More importantly, can they be incorporated in a well motivated framework in agreement with experimental data? In this work, we show that this two component dark matter can be realized in the Inert Doublet Model in an elegant and natural manner by virtue of the spontaneous breaking of a Peccei-Quinn U(1){sub PQ} symmetry into a residual ℤ{sub 2} symmetry. The WIMP stability is guaranteed by the ℤ{sub 2} symmetry and a new dark matter component, the axion, arises. There are two interesting outcomes: (i) vector-like quarks needed to implement the Peccei-Quinn symmetry in the model may act as a portal between the dark sector and the SM fields with a supersymmetry-type phenomenology at colliders; (ii) two-component Inert Doublet Model re-opens the phenomenologically interesting 100–500 GeV mass region. We show that the model can successfully realize a two component dark matter framework and at the same time avoid low and high energy physics constraints such as monojet and dijet plus missing energy, as well as indirect and direct dark matter detection bounds.
Infinitely many states and stochastic symmetry in a Gaussian Potts-Hopfield model
van Enter, ACD; Schaap, HG
2002-01-01
We study a Gaussian Potts-Hopfield model. Whereas for Ising spins and two disorder variables per site the chaotic pair scenario is realized, we find that for q-state Potts spins q (q - 1)-tuples occur. Beyond the breaking of a continuous stochastic symmetry, we study the fluctuations and obtain the
Optimal Design of Round Bottomed Triangle Channels
Directory of Open Access Journals (Sweden)
Ayman T. Hameed
2013-05-01
Full Text Available In optimal design concept, the geometric dimensions of a channel cross-section are determined in a manner to minimize the total construction costs. The Direct search optimization method by using MATALAB is used to solve the resulting channel optimization models for a specified flow rate, roughness coefficient and longitudinal slope. The developed optimization models are applied to design the round bottomed triangle channel and trapezoidal channels to convey a given design flow considering various design scenarios However, it also can be extended to other shapes of channels. This method optimizes the total construction cost by minimizing the cross-sectional area and wetted perimeter per unit length of the channel. In the present study, it is shown that for all values of side slope, the total construction cost in the round bottomed triangle cross-section are less than those of trapezoidal cross-section for the same values of discharge. This indicates that less excavation and a lining are involved and therefore implies that the round bottomed triangle cross-section is more economical than trapezoidal cross-section.
Symmetry Breaking, Unification, and Theories Beyond the Standard Model
Energy Technology Data Exchange (ETDEWEB)
Nomura, Yasunori
2009-07-31
A model was constructed in which the supersymmetric fine-tuning problem is solved without extending the Higgs sector at the weak scale. We have demonstrated that the model can avoid all the phenomenological constraints, while avoiding excessive fine-tuning. We have also studied implications of the model on dark matter physics and collider physics. I have proposed in an extremely simple construction for models of gauge mediation. We found that the {mu} problem can be simply and elegantly solved in a class of models where the Higgs fields couple directly to the supersymmetry breaking sector. We proposed a new way of addressing the flavor problem of supersymmetric theories. We have proposed a new framework of constructing theories of grand unification. We constructed a simple and elegant model of dark matter which explains excess flux of electrons/positrons. We constructed a model of dark energy in which evolving quintessence-type dark energy is naturally obtained. We studied if we can find evidence of the multiverse.
Quantum structure of T-dualized models with symmetry breaking
Casteill, P Y
2000-01-01
We study the principal sigma-models defined on any group manifold GL x GR/GD with breaking of GR, and their T-dual transforms. For abritary breaking we can express the torsion and Ricci tensor of the dual model in terms of the frame geometry of the initial principal model. Using these results, we give necessary and sufficient conditions for the dual model to be torsionless and prove that the one-loop renormalizability of a given principal model is inherited by its dual partner, who shares the same beta-functions. These results are shown to hold also if the principal model is endowed with torsion. As an application we compute the beta-functions for the full Bianchi family and show that for some choices of the breaking parameters the dilaton anomaly is absent: for these choices the dual torsion vanishes. For the dualized Bianchi V model (which is torsionless for any breaking), we take advantage of its simpler structure, to study its two-loops renormalizability.
A late time accelerated FRW model with scalar and vector fields via Noether symmetry
Energy Technology Data Exchange (ETDEWEB)
Vakili, Babak, E-mail: b-vakili@iauc.ac.ir
2014-11-10
We study the evolution of a three-dimensional minisuperspace cosmological model by the Noether symmetry approach. The phase space variables turn out to correspond to the scale factor of a flat Friedmann–Robertson–Walker (FRW) model, a scalar field with potential function V(ϕ) with which the gravity part of the action is minimally coupled and a vector field of its kinetic energy is coupled with the scalar field by a coupling function f(ϕ). Then, the Noether symmetry of such a cosmological model is investigated by utilizing the behavior of the corresponding Lagrangian under the infinitesimal generator of the desired symmetry. We explicitly calculate the form of the coupling function between the scalar and the vector fields and also the scalar field potential function for which such symmetry exists. Finally, by means of the corresponding Noether current, we integrate the equations of motion and obtain exact solutions for the scale factor, scalar and vector fields. It is shown that the resulting cosmology is an accelerated expansion universe for which its expansion is due to the presence of the vector field in the early times, while the scalar field is responsible of its late time expansion.
A late time accelerated FRW model with scalar and vector fields via Noether symmetry
Directory of Open Access Journals (Sweden)
Babak Vakili
2014-11-01
Full Text Available We study the evolution of a three-dimensional minisuperspace cosmological model by the Noether symmetry approach. The phase space variables turn out to correspond to the scale factor of a flat Friedmann–Robertson–Walker (FRW model, a scalar field with potential function V(ϕ with which the gravity part of the action is minimally coupled and a vector field of its kinetic energy is coupled with the scalar field by a coupling function f(ϕ. Then, the Noether symmetry of such a cosmological model is investigated by utilizing the behavior of the corresponding Lagrangian under the infinitesimal generator of the desired symmetry. We explicitly calculate the form of the coupling function between the scalar and the vector fields and also the scalar field potential function for which such symmetry exists. Finally, by means of the corresponding Noether current, we integrate the equations of motion and obtain exact solutions for the scale factor, scalar and vector fields. It is shown that the resulting cosmology is an accelerated expansion universe for which its expansion is due to the presence of the vector field in the early times, while the scalar field is responsible of its late time expansion.
A late time accelerated FRW model with scalar and vector fields via Noether symmetry
Vakili, Babak
2014-01-01
We study the evolution of a three-dimensional minisuperspace cosmological model by the Noether symmetry approach. The phase space variables turn out to correspond to the scale factor of a flat Friedmann-Robertson-Walker (FRW) model, a scalar field with potential function $V(\\phi)$ with which the gravity part of the action is minimally coupled and a vector field its kinetic energy is coupled with the scalar field by a coupling function $f(\\phi)$. Then, the Noether symmetry of such a cosmological model is investigated by utilizing the behavior of the corresponding Lagrangian under the infinitesimal generator of the desired symmetry. We explicitly calculate the form of the coupling function between the scalar and the vector fields and also the scalar field potential function for which such symmetry exists. Finally, by means of the corresponding Noether current we integrate the equations of motion and obtain exact solutions for the scale factor, scalar and vector fields. It is shown that the resulting cosmology i...
A late time accelerated FRW model with scalar and vector fields via Noether symmetry
Vakili, Babak
2014-11-01
We study the evolution of a three-dimensional minisuperspace cosmological model by the Noether symmetry approach. The phase space variables turn out to correspond to the scale factor of a flat Friedmann-Robertson-Walker (FRW) model, a scalar field with potential function V (ϕ) with which the gravity part of the action is minimally coupled and a vector field of its kinetic energy is coupled with the scalar field by a coupling function f (ϕ). Then, the Noether symmetry of such a cosmological model is investigated by utilizing the behavior of the corresponding Lagrangian under the infinitesimal generator of the desired symmetry. We explicitly calculate the form of the coupling function between the scalar and the vector fields and also the scalar field potential function for which such symmetry exists. Finally, by means of the corresponding Noether current, we integrate the equations of motion and obtain exact solutions for the scale factor, scalar and vector fields. It is shown that the resulting cosmology is an accelerated expansion universe for which its expansion is due to the presence of the vector field in the early times, while the scalar field is responsible of its late time expansion.
Natural PQ symmetry in the 3-3-1 model with a minimal scalar sector
Energy Technology Data Exchange (ETDEWEB)
Vega, Bruce Lehmann Sanchez; Garcia, Juan Carlos Montero [Instituto de Fisica Teorica (IFT/UNESP), SP (Brazil)
2011-07-01
Full text: In the framework of a 3-3-1 model with a minimal scalar sector we make a detailed study concerning the implementation of the PQ symmetry in order to solve the strong CP problem. For the original version of the model, with only two scalar triplets, we show that the entire Lagrangian is invariant under a PQ-like symmetry but no axion is produced since an U(1) subgroup remains unbroken. Although in this case the strong CP problem can still be solved, the solution is largely disfavored since three quark states are left massless to all orders in perturbation theory. The addition of a third scalar triplet removes the massless quark states but the resulting axion is visible. In order to become realistic the model must be extended to account for massive quarks and invisible axion. We show that the addition of a scalar singlet together with a ZN discrete gauge symmetry can successfully accomplish these tasks and protect the axion field against quantum gravitational effects. To make sure that the protecting discrete gauge symmetry is anomaly free we use a discrete version of the Green-Schwarz mechanism. (author)
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.
Modeling outer-sphere disorder in the symmetry breaking of PPV.
Liu, L Angela; Yaron, David J
2009-04-21
Disorder plays an important role in the photophysics of conjugated polymers such as poly(para-phenylene vinylene) (PPV). The dipole moments measured by electroabsorption spectroscopy for a centrosymmetric system such as PPV provide a direct quantitative measure of disorder-induced symmetry breaking. Although inner-sphere (structural) disorder is present, outer-sphere (environmental) disorder dominates the symmetry breaking in PPV. This paper develops and compares six models of outer-sphere disorder that differ in their representation of the electrostatic environment of PPV in glassy solvents. The most detailed model is an all-atom description of the solvent glass and this model forms the basis for comparison of the less detailed models. Four models are constructed in which multipoles are placed at points on a lattice. These lattice models differ in the degree to which they include correlation between the lattice spacings and the orientations of the multipoles. A simple model that assigns random Gaussian-distributed electrostatic potentials to each atom in the PPV molecule is also considered. Comparison of electronic structure calculations of PPV in these electrostatic environments using the all-atom model as a benchmark reveals that dipole and quadrupole lattices provide reasonable models of organic glassy solvents. Including orientational correlation among the solvent molecules decreases the effects of outer-sphere disorder, whereas including correlation in the lattice spacings increases the effects. Both the dipole and quadrupole moments of the solvent molecules can have significant effects on the symmetry breaking and these effects are additive. This additivity provides a convenient means for predicting the effects of various glassy solvents based on their multipole moments. The results presented here suggest that electrostatic disorder can account for the observed symmetry breaking in organic glasses. Furthermore, the lattice models are in general agreement
Twisted spectral triple for the Standard Model and spontaneous breaking of the Grand Symmetry
Devastato, Agostino
2014-01-01
Grand symmetry models in noncommutative geometry have been introduced to explain how to generate minimally (i.e. without adding new fermions) an extra scalar field beyond the standard model, which both stabilizes the electroweak vacuum and makes the computation of the mass of the Higgs compatible with its experimental value. In this paper, we use Connes-Moscovici twisted spectral triples to cure a technical problem of the grand symmetry, that is the appearance together with the extra scalar field of unbounded vectorial terms. The twist makes these terms bounded, and also permits to understand the breaking to the standard model as a dynamical process induced by the spectral action. This is a spontaneous breaking from a pre-geometric Pati-Salam model to the almost-commutative geometry of the standard model, with two Higgs-like fields: scalar and vector.
Interplay between sign problem and Z_3 symmetry in three-dimensional Potts model
Hirakida, Takehiro; Takahashi, Junichi; Yahiro, Masanobu
2016-01-01
We construct four kinds of Z3-symmetric three-dimentional (3-d) Potts models, each with different number of states at each site on a 3-d lattice, by extending the 3-d three-state Potts model. Comparing the ordinary Potts model with the four Z3-symmetric Potts models, we investigate how Z3 symmetry affects the sign problem and see how the deconfinement transition line changes in the $\\mu-\\kappa$ plane as the number of states increases, where $\\mu$ $(\\kappa)$ plays a role of chemical potential (temperature) in the models. We find that the sign problem is almost cured by imposing Z3 symmetry. This mechanism may happen in Z3-symmetric QCD-like theory. We also show that the deconfinement transition line has stronger $\\mu$-dependence with respect to increasing the number of states.
Interplay between sign problem and Z3 symmetry in three-dimensional Potts models
Hirakida, Takehiro; Kouno, Hiroaki; Takahashi, Junichi; Yahiro, Masanobu
2016-07-01
We construct four kinds of Z3 -symmetric three-dimensional (3D) Potts models, each with a different number of states at each site on a 3D lattice, by extending the 3D 3-state Potts model. Comparing the ordinary Potts model with the four Z3-symmetric Potts models, we investigate how Z3 symmetry affects the sign problem and see how the deconfinement transition line changes in the μ -κ plane as the number of states increases, where μ (κ ) plays a role of chemical potential (temperature) in the models. We find that the sign problem is almost cured by imposing Z3 symmetry. This mechanism may happen in Z3-symmetric QCD-like theory. We also show that the deconfinement transition line has stronger μ dependence with respect to increasing the number of states.
Spontaneous symmetry breaking in the O(4) scalar model on a lattice
Demchik, Vadim; Skalozub, Vladimir
2014-01-01
The spontaneous symmetry breaking in the four component scalar $\\lambda \\phi^4$ model (O(4) model) is investigated on a lattice dependently on the value of the coupling constant $\\lambda$. A general approach for dealing with this phenomenon is developed. In the spherical coordinates in the internal space of the scalar field, the Goldstone modes are integrated out by the saddle point method that reduces the functional integral of the model to the effective one component theory convenient for lattice investigations. The partition function of the model is calculated analytically up to the one-loop order. Monte Carlo simulations are performed with a QCDGPU software package on a HGPU cluster. It is shown that for $\\lambda < 10^{-5}$ the scalar field condensate does not create. For larger values of coupling symmetry breaking happens. Qualitatively, this is similar to that of observed already in the O(1) model.
Phase diagram of model anisotropic particles with octahedral symmetry
Noya, E. G.; Vega, C.; Doye, J. P. K.; Louis, A. A.
2007-01-01
We computed the phase diagram for a system of model anisotropic particles with six attractive patches in an octahedral arrangement. We chose to study this model for a relatively narrow value of the patch width where the lowest-energy configuration of the system is a simple cubic crystal. At this value of the patch width, there is no stable vapour-liquid phase separation, and there are three other crystalline phases in addition to the simple cubic crystal that is most stable at low pressure. F...
N=2 superconformal symmetry in super coset models
Energy Technology Data Exchange (ETDEWEB)
Creutzig, Thomas; Roenne, Peter B.; Schomerus, Volker [DESY, Hamburg (Germany). DESY Theory Group
2009-07-15
We extend the Kazama-Suzuki construction of models with N=(2,2) world-sheet supersymmetry to cosets S/K of supergroups. Among the admissible target spaces that allow for an extension to N=2 superconformal algebras are some simple Lie supergroups, including PSL(N vertical stroke N). Our general analysis is illustrated at the example of the N=1 WZNW model on GL(1 vertical stroke 1). After constructing its N=2 superconformal algebra we determine the (anti-)chiral ring of the theory. It exhibits an interesting interplay between world-sheet and target space supersymmetry. (orig.)
Symmetries of preon interactions modeled as a finite group
Bellinger, James N.
1997-07-01
I model preon interactions as a finite group. Treating the elements of the group as the bases of a vector space, I examine those linear mappings under which the transformed bases may be treated as members of a group isomorphic to the original. In some cases these mappings are continuous Lie groups.
Symmetries of preon interactions modeled as a finite group
Energy Technology Data Exchange (ETDEWEB)
Bellinger, J.N. [University of Wisconsin at Madison, Madison, Wisconsin 53706 (United States)
1997-07-01
I model preon interactions as a finite group. Treating the elements of the group as the bases of a vector space, I examine those linear mappings under which the transformed bases may be treated as members of a group isomorphic to the original. In some cases these mappings are continuous Lie groups. {copyright} {ital 1997 American Institute of Physics.}
Electro symmetry breaking and beyond the standard model
Energy Technology Data Exchange (ETDEWEB)
Barklow, T. [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Dawson, S. [Brookhaven National Lab., Upton, NY (United States); Haber, H.E. [California Univ., Santa Cruz, CA (United States). Inst. for Particle Physics; Siegrist, J. [Lawrence Berkeley Lab., CA (United States)
1995-05-01
The development of the Standard Model of particle physics is a remarkable success story. Its many facets have been tested at present day accelerators; no significant unambiguous deviations have yet been found. In some cases, the model has been verified at an accuracy of better than one part in a thousand. This state of affairs presents our field with a challenge. Where do we go from here? What is our vision for future developments in particle physics? Are particle physicists` recent successes a signal of the field`s impending demise, or do real long-term prospects exist for further progress? We assert that the long-term health and intellectual vitality of particle physics depends crucially on the development of a new generation of particle colliders that push the energy frontier by an order of magnitude beyond present capabilities. In this report, we address the scientific issues underlying this assertion.
A Democratic Gauge Model for Dark/Visible Matter Symmetry
Oliveira, O; Hussein, M S; de Paula, W; Frederico, T
2011-01-01
We develop a model for visible matter-dark matter interaction based on the exchange of a weakly interacting massive gauge boson called herein the WIMG. Our model hinges on the assumption that all known particles in the visible matter have their counterparts in the dark matter. We postulate six families of particles five of which are dark. This leads to the unavoidable postulation of six parallel worlds, the visible one and five invisible worlds. We give arguments on particle decays and lifetimes that set a limit on the mass of the WIMG, the gray boson responsible for the very meager communication among these worlds. The 5:1 ratio of dark to visible matter is taken for granted.
A mathematical model of symmetry based on mathematical definition
Institute of Scientific and Technical Information of China (English)
刘玉生; 杨将新; 吴昭同; 高曙明
2002-01-01
Tolerance is imperative for seamless integration of CAD/CAM(Computer Aided Disignd/Computer Aided Manufacture) which is just a text attribute and has no semantics in present CAD systems. There are many tolerance types, the relations between which are very complicated. In addition, the different principles of tolerance make study of tolerance difficult; and there may be various meanings or interpretation for the same type of tolerance beeanse of the literal definition. In this work, latest unambiguous mathematical definition was applied to study, explain and clarify: ( 1 ) the formation and representation of tolerance zone, and (2) the formation and representation of variational elements ; after which, the mathematical models of syrmmetry of different tolerance principles and different interpretations were derived. An example is given to illustrate the application of these models in tolerance analysis.
Scalar products in generalized models with SU(3)-symmetry
Wheeler, M.
2012-01-01
We consider a generalized model with SU(3)-invariant R-matrix, and review the nested Bethe Ansatz for constructing eigenvectors of the transfer matrix. A sum formula for the scalar product between generic Bethe vectors, originally obtained by Reshetikhin [11], is discussed. This formula depends on a certain partition function Z(\\{\\lambda\\},\\{\\mu\\}|\\{w\\},\\{v\\}), which we evaluate explicitly. In the limit when the variables \\{\\mu\\} or \\{v\\} approach infinity, this object reduces to the domain w...
Two viable large scalar multiplet models with an accidental Z2 symmetry
Earl, Kevin; Logan, Heather E; Pilkington, Terry
2013-01-01
Models in which the Higgs sector is extended by a single scalar electroweak multiplet Z will possess an accidental global Z2 symmetry if Z has isospin T=5/2 (sextet) or 7/2 (octet) and carries the same hypercharge as the Standard Model Higgs doublet. This Z2 symmetry keeps the lightest (neutral) member of Z stable and has interesting implications for phenomenology. We determine the constraints on these models from precision electroweak measurements and Higgs boson decays to two photons. We compute the thermal relic density of the stable member of Z and show that, for masses below 1 TeV, it can make up at most 1% of the dark matter in the universe. We also show that current dark matter direct detection experiments do not constrain the models, but future ton-scale experiments will probe their parameter space.
Implications of Lorentz symmetry violation on a 5D supersymmetric model
García-Aguilar, J D
2016-01-01
Field models with $n$ extra spatial dimensions have a larger $SO(1,3+n)$ Lorentz symmetry which is broken down to the standard $SO(1,3)$ four dimensional symmetry by the compactification process. By considering all Lorentz violating operators in a $5D$ supersymmetric Wess-Zumino mo\\-del, which otherwise conserve standard Poincare invariance in four dimensions, we show that Supersymmetry can be restored upon a simple deformation of the supersymmetric transformations. However, Supersymmetry shall not be preserved in the effective $4D$ theory that arises after compactification when the $5D$ Lorentz violating operators do not preserve $Z_2: y\\rightarrow -y$ bulk parity. We also show that parity preserving models, on the other hand, do provide well defined supersymmetric KK models.
On the stability of the parity symmetry of the scotogenic model
Energy Technology Data Exchange (ETDEWEB)
Merle, Alexander; Platscher, Moritz [Max-Planck-Institut fuer Physik, Foehringer Ring 6, 80805 Muenchen (Germany)
2015-07-01
We study the 1-loop structure of the scotogenic model - a simple extension of the SM by an inert scalar doublet and heavy singlet Majorana neutrino fields, all having odd charge under a Z{sub 2} symmetry. This model can account for a variety of phenomena, such as small neutrino masses, lepton flavour violation and Dark Matter. In addition to the well-known theoretical and experimental bounds on the model's scalar sector, we consider the issue of naturalness which arises as the heavy Majorana fermions are coupled to the inert doublet and give rise to potentially large negative corrections to the corresponding scalar mass parameter. Thus, the right choice of model parameters is indispensable to keep the central parity symmetry intact.
Precision measurements of {\\theta}12 for testing models of discrete leptonic flavour symmetries
Ballett, Peter; Luhn, Christoph; Pascoli, Silvia; Schmidt, Michael A
2014-01-01
Models of leptonic flavour with discrete symmetries can provide an attractive explanation of the pattern of elements found in the leptonic mixing matrix. The next generation of neutrino oscillation experiments will allow the mixing parameters to be tested to a new level of precision, crucially measuring the CP violating phase {\\delta} for the first time. In this contribution, we present results of a systematic survey of the predictions of a class of models based on residual discrete symmetries and the prospects for excluding such models at medium- and long-term oscillation experiments. We place particular emphasis on the complementary role that a future circa 50 km reactor experiment, e.g. JUNO, can play in constraining these models.
Slavnov and Gaudin-Korepin Formulas for Models without U(1) Symmetry: the Twisted XXX Chain
Belliard, Samuel; Pimenta, Rodrigo A.
2015-12-01
We consider the XXX spin-1/2 Heisenberg chain on the circle with an arbitrary twist. We characterize its spectral problem using the modified algebraic Bethe anstaz and study the scalar product between the Bethe vector and its dual. We obtain modified Slavnov and Gaudin-Korepin formulas for the model. Thus we provide a first example of such formulas for quantum integrable models without U(1) symmetry characterized by an inhomogenous Baxter T-Q equation.
Natural R parity conservation with horizontal symmetries a four generation model
Berezhiani, Z G; Berezhiani, Zurab; Nardi, Enrico
1995-01-01
The absence of R parity violating operators can be naturally ensured in the presence of a SU(N)_H\\ (N=4,6...) horizontal gauge symmetry, independently of the vertical gauge group. We study an extension of the supersymmetric standard model with four families and gauged SU(4)_H. Beyond preserving R parity, the model gives rise to the realistic fermion mass matrices which naturally ensure the heaviness of the fourth family fermions b',t',\\tau',\
Quark model with chiral-symmetry breaking and confinement in the Covariant Spectator Theory
Energy Technology Data Exchange (ETDEWEB)
Biernat, Elmer P. [CFTP, Instituto Superior TÃ©cnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; Pena, Maria Teresa [CFTP, Instituto Superior TÃ©cnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; Departamento de FÃsica, Instituto Superior TÃ©cnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; Ribiero, Jose' Emilio F. [CeFEMA, Instituto Superior TÃ©cnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; Stadler, Alfred [Departamento de FÃsica, Universidade de Ãvora, 7000-671 Ãvora, Portugal; Gross, Franz L. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
2016-03-01
We propose a model for the quark-antiquark interaction in Minkowski space using the Covariant Spectator Theory. We show that with an equal-weighted scalar-pseudoscalar structure for the confining part of our interaction kernel the axial-vector Ward-Takahashi identity is preserved and our model complies with the Adler-zero constraint for pi-pi-scattering imposed by chiral symmetry.
Canalization and symmetry in Boolean models for genetic regulatory networks
Energy Technology Data Exchange (ETDEWEB)
Reichhardt, C J Olson [Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Bassler, Kevin E [Department of Physics, University of Houston, Houston, TX 77204-5005 (United States)
2007-04-20
Canalization of genetic regulatory networks has been argued to be favoured by evolutionary processes due to the stability that it can confer to phenotype expression. We explore whether a significant amount of canalization and partial canalization can arise in purely random networks in the absence of evolutionary pressures. We use a mapping of the Boolean functions in the Kauffman N-K model for genetic regulatory networks onto a k-dimensional Ising hypercube (where k = K) to show that the functions can be divided into different classes strictly due to geometrical constraints. The classes can be counted and their properties determined using results from group theory and isomer chemistry. We demonstrate that partially canalizing functions completely dominate all possible Boolean functions, particularly for higher k. This indicates that partial canalization is extremely common, even in randomly chosen networks, and has implications for how much information can be obtained in experiments on native state genetic regulatory networks.
Covariance in models of loop quantum gravity: Spherical symmetry
Bojowald, Martin; Reyes, Juan D
2015-01-01
Spherically symmetric models of loop quantum gravity have been studied recently by different methods that aim to deal with structure functions in the usual constraint algebra of gravitational systems. As noticed by Gambini and Pullin, a linear redefinition of the constraints (with phase-space dependent coefficients) can be used to eliminate structure functions, even Abelianizing the more-difficult part of the constraint algebra. The Abelianized constraints can then easily be quantized or modified by putative quantum effects. As pointed out here, however, the method does not automatically provide a covariant quantization, defined as an anomaly-free quantum theory with a classical limit in which the usual (off-shell) gauge structure of hypersurface deformations in space-time appears. The holonomy-modified vacuum theory based on Abelianization is covariant in this sense, but matter theories with local degrees of freedom are not. Detailed demonstrations of these statements show complete agreement with results of ...
Verifying three-dimensional skull model reconstruction using cranial index of symmetry.
Directory of Open Access Journals (Sweden)
Woon-Man Kung
Full Text Available BACKGROUND: Difficulty exists in scalp adaptation for cranioplasty with customized computer-assisted design/manufacturing (CAD/CAM implant in situations of excessive wound tension and sub-cranioplasty dead space. To solve this clinical problem, the CAD/CAM technique should include algorithms to reconstruct a depressed contour to cover the skull defect. Satisfactory CAM-derived alloplastic implants are based on highly accurate three-dimensional (3-D CAD modeling. Thus, it is quite important to establish a symmetrically regular CAD/CAM reconstruction prior to depressing the contour. The purpose of this study is to verify the aesthetic outcomes of CAD models with regular contours using cranial index of symmetry (CIS. MATERIALS AND METHODS: From January 2011 to June 2012, decompressive craniectomy (DC was performed for 15 consecutive patients in our institute. 3-D CAD models of skull defects were reconstructed using commercial software. These models were checked in terms of symmetry by CIS scores. RESULTS: CIS scores of CAD reconstructions were 99.24±0.004% (range 98.47-99.84. CIS scores of these CAD models were statistically significantly greater than 95%, identical to 99.5%, but lower than 99.6% (p<0.001, p = 0.064, p = 0.021 respectively, Wilcoxon matched pairs signed rank test. These data evidenced the highly accurate symmetry of these CAD models with regular contours. CONCLUSIONS: CIS calculation is beneficial to assess aesthetic outcomes of CAD-reconstructed skulls in terms of cranial symmetry. This enables further accurate CAD models and CAM cranial implants with depressed contours, which are essential in patients with difficult scalp adaptation.
Rašin, Andrija
1994-01-01
We discuss the idea of approximate flavor symmetries. Relations between approximate flavor symmetries and natural flavor conservation and democracy models is explored. Implications for neutrino physics are also discussed.
S-Matrices and Quantum Group Symmetry of q-Deformed Sigma Models
Hollowood, Timothy J; Schmidtt, David M
2015-01-01
Recently, several kinds of integrable deformations of the string world sheet theory in the gauge/gravity correspondence have been constructed. One class of these, the q-deformations with q a root of unity, has been shown to be related to a particular discrete deformation of the principal chiral models and (semi-)symmetric space sigma models involving a gauged WZW model. We conjecture a form for the exact S-matrices of the bosonic integrable field theories of this type. The S-matrices imply that the theories have a hidden infinite dimensional affine quantum group symmetry. We provide some evidence, via quantum inverse scattering techniques, that the theories do indeed possess the finite-dimensional part of this quantum group symmetry.
S-matrices and quantum group symmetry of k-deformed sigma models
Hollowood, Timothy J.; Miramontes, J. Luis; Schmidtt, David M.
2016-11-01
Recently, two kinds of integrable deformations of the string world sheet theory in the gauge/gravity correspondence have been constructed (Delduc et al 2014 Phys. Rev. Lett. 112 051601; Hollowood et al 2014 J. Phys. A: Math. Theor. 47 495402). One class of these, the k deformations associated to the more general q deformations but with q={{{e}}}{{i}π /k} a root of unity, has been shown to be related to a particular discrete deformation of the principal chiral models and (semi-)symmetric space sigma models involving a gauged WZW model. We conjecture a form for the exact S-matrices of the bosonic integrable field theories of this type. The S-matrices imply that the theories have a hidden infinite dimensional affine quantum group symmetry. We provide some evidence, via quantum inverse scattering techniques, that the theories do indeed possess the finite-dimensional part of this quantum group symmetry.
More on cosmological constraints on spontaneous R-symmetry breaking models
Energy Technology Data Exchange (ETDEWEB)
Hamada, Yuta; Kobayashi, Tatsuo [Kyoto Univ. (Japan). Dept. of Physics; Kamada, Kohei [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Ecole Polytechnique Federale de Lausanne (Switzerland). Inst. de Theorie des Phenomenes Physiques; Ookouchi, Yutaka [Kyushu Univ., Fukuoka (Japan). Faculty of Arts and Science
2013-10-15
We study the spontaneous R-symmetry breaking model and investigate the cosmological constraints on this model due to the pseudo Nambu-Goldstone boson, R-axion. We consider the R-axion which has relatively heavy mass in order to complement our previous work. In this regime, model parameters, R-axions mass and R-symmetry breaking scale, are constrained by Big Bang Nucleosynthesis and overproduction of the gravitino produced from R-axion decay and thermal plasma. We find that the allowed parameter space is very small for high reheating temperature. For low reheating temperature, the U(1){sub R} breaking scale f{sub a} is constrained as f{sub a}<10{sup 12-14} GeV regardless of the value of R-axion mass.
More on cosmological constraints on spontaneous R-symmetry breaking models
Hamada, Yuta; Kobayashi, Tatsuo; Ookouchi, Yutaka
2014-01-01
We study the spontaneous R-symmetry breaking model and investigate the cosmological constraints on this model due to the pseudo Nambu-Goldstone boson, R-axion. We consider the R-axion which has relatively heavy mass in order to complement our previous work. In this regime, model parameters, R-axions mass and R-symmetry breaking scale, are constrained by Big Bang Nucleosynthesis and overproduction of the gravitino produced from R-axion decay and thermal plasma. We find that the allowed parameter space is very small for high reheating temperature. For low reheating temperature, the $U(1)_R$ breaking scale $f_a$ is constrained as $f_a<10^{12-14}\\GeV$ regardless of the value of R-axion mass.
More on cosmological constraints on spontaneous R-symmetry breaking models
Energy Technology Data Exchange (ETDEWEB)
Hamada, Yuta; Kobayashi, Tatsuo [Department of Physics, Kyoto University, Kyoto, 606-8502 (Japan); Kamada, Kohei [Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, Hamburg, D-22607 (Germany); Ookouchi, Yutaka, E-mail: hamada@gauge.scphys.kyoto-u.ac.jp, E-mail: kohei.kamada@epfl.ch, E-mail: kobayash@gauge.scphys.kyoto-u.ac.jp, E-mail: yutaka.ookouchi@artsci.kyushu-u.ac.jp [Faculty of Arts and Science, Kyushu University, Fukuoka, 819–0395 (Japan)
2014-01-01
We study the spontaneous R-symmetry breaking model and investigate the cosmological constraints on this model due to the pseudo Nambu-Goldstone boson, R-axion. We consider the R-axion which has relatively heavy mass in order to complement our previous work. In this regime, model parameters, R-axions mass and R-symmetry breaking scale, are constrained by Big Bang Nucleosynthesis and overproduction of the gravitino produced from R-axion decay and thermal plasma. We find that the allowed parameter space is very small for high reheating temperature. For low reheating temperature, the U(1){sub R} breaking scale f{sub a} is constrained as f{sub a} < 10{sup 12−14} GeV regardless of the value of R-axion mass.
Neutrino Masses from an A4 Symmetry in Holographic Composite Higgs Models
del Aguila, Francisco; Santiago, Jose
2010-01-01
We show that holographic composite Higgs Models with a discrete A4 symmetry naturally predict hierarchical charged lepton masses and an approximate tri-bimaximal lepton mixing with the correct scale of neutrino masses. They also satisfy current constraints from electroweak precision tests, lepton flavor violation and lepton mixing in a large region of parameter space. Two phenomenologically relevant features arise in these models. First, an extra suppression on the lepton Yukawa couplings makes the tau lepton more composite than naively expected from its mass. As a consequence new light leptonic resonances, with masses as low as few hundreds of GeV, large couplings to tau and a very characteristic collider phenomenology, are quite likely. Second, the discrete symmetry A4 together with the model structure provide a double-layer of flavor protection that allows to keep tree-level mediated processes below present experimental limits. One-loop processes violating lepton flavor, like mu -> e gamma, may be however ...
Lepton-flavour violation in a Pati-Salam model with gauged flavour symmetry
Feldmann, Thorsten; Moch, Paul
2016-01-01
Combining Pati-Salam (PS) and flavour symmetries in a renormalisable setup, we devise a scenario which produces realistic masses for the charged leptons. Flavour-symmetry breaking scalar fields in the adjoint representations of the PS gauge group are responsible for generating different flavour structures for up- and down-type quarks as well as for leptons. The model is characterised by new heavy fermions which mix with the Standard Model quarks and leptons. In particular, the partners for the third fermion generation induce sizeable sources of flavour violation. Focusing on the charged-lepton sector, we scrutinise the model with respect to its implications for lepton-flavour violating processes such as $\\mu \\rightarrow e\\gamma$, $\\mu\\rightarrow 3e$ and muon conversion in nuclei.
Haba, Naoyuki; Okada, Nobuchika; Yamaguchi, Yuya
2015-01-01
We suggest the so-called bosonic seesaw mechanism in the context of a classically conformal $U(1)_{B-L}$ extension of the Standard Model with two Higgs doublet fields. The $U(1)_{B-L}$ symmetry is radiatively broken via the Coleman-Weinberg mechanism, which also generates the mass terms for the two Higgs doublets through quartic Higgs couplings. Their masses are all positive but, nevertheless, the electroweak symmetry breaking is realized by the bosonic seesaw mechanism. We analyze the renormalization group evolutions for all model couplings, and find that a large hierarchy among the quartic Higgs couplings, which is crucial for the bosonic seesaw mechanism to work, is dramatically reduced toward high energies. Therefore, the bosonic seesaw is naturally realized with only a mild hierarchy, if some fundamental theory, which provides the origin of the classically conformal invariance, completes our model at some high energy, for example, the Planck scale. The requirements for the perturbativity of the running c...
On the particle-hole symmetry of the fermionic spinless Hubbard model in D=1
Directory of Open Access Journals (Sweden)
M.T. Thomaz
2014-06-01
Full Text Available We revisit the particle-hole symmetry of the one-dimensional (D=1 fermionic spinless Hubbard model, associating that symmetry to the invariance of the Helmholtz free energy of the one-dimensional spin-1/2 XXZ Heisenberg model, under reversal of the longitudinal magnetic field and at any finite temperature. Upon comparing two regimes of that chain model so that the number of particles in one regime equals the number of holes in the other, one finds that, in general, their thermodynamics is similar, but not identical: both models share the specific heat and entropy functions, but not the internal energy per site, the first-neighbor correlation functions, and the number of particles per site. Due to that symmetry, the difference between the first-neighbor correlation functions is proportional to the z-component of magnetization of the XXZ Heisenberg model. The results presented in this paper are valid for any value of the interaction strength parameter V, which describes the attractive/null/repulsive interaction of neighboring fermions.
A heterotic standard model with B−L symmetry and a stable proton
Energy Technology Data Exchange (ETDEWEB)
Buchbinder, Evgeny I. [The University of Western Australia, 35 Stirling Highway, Crawley WA 6009 (Australia); Constantin, Andrei; Lukas, Andre [Rudolf Peierls Centre for Theoretical Physics, Oxford University,1 Keble Road, Oxford, OX1 3NP (United Kingdom)
2014-06-17
We consider heterotic Calabi-Yau compactifications with S(U(4)×U(1)) background gauge fields. These models lead to gauge groups with an additional U(1) factor which, under certain conditions, can combine with hypercharge to a B−L symmetry. The associated gauge boson is automatically super-massive and, hence, does not constitute a phenomenological problem. We illustrate this class of compactifications with a model based on the monad construction, which leads to a supersymmetric standard model with three families of quarks and leptons, one pair of Higgs doublets, three right-handed neutrinos and no exotics charged under the standard model group. The presence of the B−L symmetry means that the model is safe from proton decay induced by dimension four operators. Due to the presence of a special locus in moduli space where the bundle structure group is Abelian and the low-energy symmetry enhances we can also show the absence of dimension five proton-decay inducing operators.
Yukawa textures or dark doublets from Two Higgs Doublet Models with $Z_3$ symmetry
Aranda, Alfredo; Noriega-Papaqui, Roberto; Vaquera-Araujo, Carlos A
2014-01-01
The effect of $Z_3$ symmetry on the general Two Higgs Doublet Model is explored. Of particular interest is the question of what can a $Z_3$ symmetry do beyond the usual case with $Z_2$. There are two independent scenarios that give some interesting results: first, by giving non-trivial charges to the Standard Model fermions, it is possible to use the $Z_3$ symmetry of the scalar potential to generate potentially useful Yukawa textures. This is not possible with $Z_2$. A series of possibilities is presented where their viability is addressed and a specific example in the quark sector is given for concreteness. The second venue of interest is in the area of inert doublets. It is shown that by considering the Standard Model plus two additional inert doublet scalars, i.e. a Dark Two Higgs Doublet Model, together with $Z_3$, a scenario can be obtained that differs from the $Z_2$ case. Some general comments are presented on the potentially interesting phenomenology of such model.
Vacuum stability and radiative electroweak symmetry breaking in an SO(10) dark matter model
Mambrini, Yann; Nagata, Natsumi; Olive, Keith A.; Zheng, Jiaming
2016-06-01
Vacuum stability in the Standard Model is problematic as the Higgs quartic self-coupling runs negative at a renormalization scale of about 1010 GeV . We consider a nonsupersymmetric SO(10) grand unification model for which gauge coupling unification is made possible through an intermediate scale gauge group, Gint=SU (3 )C⊗SU (2 )L⊗SU (2 )R⊗U (1 )B -L . Gint is broken by the vacuum expectation value of a 126 of SO(10) which not only provides for neutrino masses through the seesaw mechanism but also preserves a discrete Z2 that can account for the stability of a dark matter candidate, here taken to be the Standard Model singlet component of a bosonic 16 . We show that in addition to these features the model insures the positivity of the Higgs quartic coupling through its interactions to the dark matter multiplet and 126 . We also show that the Higgs mass squared runs negative, triggering electroweak symmetry breaking. Thus, the vacuum stability is achieved along with radiative electroweak symmetry breaking and captures two more important elements of supersymmetric models without low-energy supersymmetry. The conditions for perturbativity of quartic couplings and for radiative electroweak symmetry breaking lead to tight upper and lower limits on the dark matter mass, respectively, and this dark matter mass region (1.35-2 TeV) can be probed in future direct detection experiments.
A Heterotic Standard Model with B-L Symmetry and a Stable Proton
Buchbinder, Evgeny I; Lukas, Andre
2014-01-01
We consider heterotic Calabi-Yau compactifications with S(U(4)xU(1)) background gauge fields. These models lead to gauge groups with an additional U(1) factor which, under certain conditions, can combine with hypercharge to a B-L symmetry. The associated gauge boson is automatically super-massive and, hence, does not constitute a phenomenological problem. We illustrate this class of compactifications with a model based on the monad construction, which leads to a supersymmetric standard model with three families of quarks and leptons, one pair of Higgs doublets, three right-handed neutrinos and no exotics charged under the standard model group. The presence of the B-L symmetry means that the model is safe from proton decay induced by dimension four operators. Due to the presence of a special locus in moduli space where the bundle structure group is Abelian and the low-energy symmetry enhances we can also show the absence of dimension five proton-decay inducing operators.
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.
Neutrinos and flavor symmetries
Tanimoto, Morimitsu
2015-07-01
We discuss the recent progress of flavor models with the non-Abelian discrete symmetry in the lepton sector focusing on the θ13 and CP violating phase. In both direct approach and indirect approach of the flavor symmetry, the non-vanishing θ13 is predictable. The flavor symmetry with the generalised CP symmetry can also predicts the CP violating phase. We show the phenomenological analyses of neutrino mixing for the typical flavor models.
Neutrinos and flavor symmetries
Energy Technology Data Exchange (ETDEWEB)
Tanimoto, Morimitsu
2015-07-15
We discuss the recent progress of flavor models with the non-Abelian discrete symmetry in the lepton sector focusing on the θ{sub 13} and CP violating phase. In both direct approach and indirect approach of the flavor symmetry, the non-vanishing θ{sub 13} is predictable. The flavor symmetry with the generalised CP symmetry can also predicts the CP violating phase. We show the phenomenological analyses of neutrino mixing for the typical flavor models.
Universal Unitarity Triangle 2016 and the tension between ΔM{sub s,d} and ε{sub K} in CMFV models
Energy Technology Data Exchange (ETDEWEB)
Blanke, Monika [Karlsruhe Institute of Technology, Institut fur Kernphysik, Eggenstein-Leopoldshafen (Germany); Karlsruhe Institute of Technology, Institut fur Theoretische Teilchenphysik, Karlsruhe (Germany); Buras, Andrzej J. [TUM-IAS, Garching (Germany); TUM, Physik Department, Garching (Germany)
2016-04-15
Motivated by the recently improved results from the Fermilab Lattice and MILC Collaborations on the hadronic matrix elements entering ΔM{sub s,d} in B{sup 0}{sub s,d}- anti B{sup 0}{sub s,d} mixing, we determine the universal unitarity triangle (UUT) in models with constrained minimal flavour violation (CMFV). Of particular importance are the very precise determinations of the ratio vertical stroke V{sub ub} vertical stroke / vertical stroke V{sub cb} vertical stroke = 0.0864 ± 0.0025 and of the angle γ = (62.7 ± 2.1) {sup circle}. They follow in this framework from the experimental values of ΔM{sub d}/ΔM{sub s} and of the CP-asymmetry S{sub ψK{sub S}}. As in CMFV models the new contributions to meson mixings can be described by a single flavour-universal variable S(v), we next determine the CKM matrix elements vertical stroke V{sub ts} vertical stroke, vertical stroke V{sub td} vertical stroke, vertical stroke V{sub cb} vertical stroke and vertical stroke V{sub ub} vertical stroke as functions of S(v) using the experimental value of ΔM{sub s} as input. The lower bound on S(v) in these models, derived by us in 2006, implies then upper bounds on these four CKM elements and on the CP-violating parameter ε{sub K}, which turns out to be significantly below its experimental value. This strategy avoids the use of tree-level determinations of vertical stroke V{sub ub} vertical stroke and vertical stroke V{sub cb} vertical stroke, which are presently subject to considerable uncertainties. On the other hand, if ε{sub K} is used instead of ΔM{sub s} as input, ΔM{sub s,d} are found to be significantly above the data. In this manner we point out that the new lattice data have significantly sharpened the tension between ΔM{sub s,d} and ε{sub K} within the CMFV framework. This implies the presence of new physics contributions beyond this framework that are responsible for the breakdown of the flavour universality of the function S(v). We also present the
Nuclear symmetry energy with mesonic cross-couplings in the effective chiral model
Malik, Tuhin; Banerjee, Kinjal; Jha, T. K.; Agrawal, B. K.
2017-09-01
The effective chiral model is extended by introducing the contributions from the cross-couplings between isovector and isoscalar mesons. These cross-couplings are found to be instrumental in improving the density content of the nuclear symmetry energy. The nuclear symmetry energy as well as its slope and curvature parameters at the saturation density are in harmony with those deduced from a diverse set of experimental data. The equation of state for pure neutron matter at subsaturation densities is also in accordance with the ones obtained from different microscopic models. The maximum mass of a neutron star is consistent with the measurement, and the radius at the canonical mass of the neutron star is within the empirical bounds.
Connecting an effective model of confinement and chiral symmetry to lattice QCD
Fraga, E; Fraga, Eduardo; Mocsy, Agnes
2007-01-01
We construct an effective model for the chiral field and the Polyakov loop in which we can investigate the interplay between the approximate chiral symmetry restoration and the deconfinement of color in a thermal SU(3) gauge theory with three flavors of massive quarks. The phenomenological couplings between these two sectors can then be related to the recent lattice data on the renormalized Polyakov loop and the chiral condensate close to the critical region.
From Exact to Partial Dynamical Symmetries: Lessons From the Interacting Boson Model
Leviatan, A
2012-01-01
We exploit the rich algebraic structure of the interacting boson model to explain the notion of partial dynamical symmetry (PDS), and present a procedure for constructing Hamiltonians with this property. We demonstrate the relevance of PDS to various topics in nuclear spectroscopy, including K-band splitting, odd-even staggering in the gamma-band and anharmonicity of excited vibrational bands. Special emphasis in this construction is paid to the role of higher-order terms.
Scotogenic $Z_2$ or $U(1)_D$ Model of Neutrino Mass with $\\Delta(27)$ Symmetry
Ma, Ernest
2014-01-01
The scotogenic model of radiative neutrino mass with $Z_2$ or $U(1)_D$ dark matter is shown to accommodate $\\Delta(27)$ symmetry naturally. The resulting neutrino mass matrix is identical to either of two forms, one proposed in 2006, the other in 2008. These two structures are studied in the context of present neutrino data, with predictions of $CP$ violation and neutrinoless double beta decay.
Semiclassical matrix model for quantum chaotic transport with time-reversal symmetry
Energy Technology Data Exchange (ETDEWEB)
Novaes, Marcel, E-mail: marcel.novaes@gmail.com
2015-10-15
We show that the semiclassical approach to chaotic quantum transport in the presence of time-reversal symmetry can be described by a matrix model. In other words, we construct a matrix integral whose perturbative expansion satisfies the semiclassical diagrammatic rules for the calculation of transport statistics. One of the virtues of this approach is that it leads very naturally to the semiclassical derivation of universal predictions from random matrix theory.
Neutrinos Masses in a Multi-Higgs Model with A4 symmetry
Machado, A. C. B.; Montero, J. C.; Pleitez, V.
2012-08-01
Presently it is well known that neutrino oscillation data are well described by massive neutrinos and their mixing. This suggests changes in the standard model (SM) and makes the flavor physics even more interesting. Recently, it has been proposed a multi-Higgs extension of the SM with Abelian and non-Abelian discrete symmetries which seeks to explain the origin of the masses and mixing matrices in all charge sectors.
Haynes, S E
1983-10-01
It is widely known that linear restrictions involve bias. What is not known is that some linear restrictions are especially dangerous for hypothesis testing. For some, the expected value of the restricted coefficient does not lie between (among) the true unconstrained coefficients, which implies that the estimate is not a simple average of these coefficients. In this paper, the danger is examined regarding the additive linear restriction almost universally imposed in statistical research--the restriction of symmetry. Symmetry implies that the response of the dependent variable to a unit decrease in an expanatory variable is identical, but of opposite sign, to the response to a unit increase. The 1st section of the paper demonstrates theoretically that a coefficient restricted by symmetry (unlike coefficients embodying other additive restrictions) is not a simple average of the unconstrained coefficients because the relevant interacted variables are inversly correlated by definition. The next section shows that, under the restriction of symmetry, fertility in Finland from 1885-1925 appears to respond in a prolonged manner to infant mortality (significant and positive with a lag of 4-6 years), suggesting a response to expected deaths. However, unscontrained estimates indicate that this finding is spurious. When the restriction is relaxed, the dominant response is rapid (significant and positive with a lag of 1-2 years) and stronger for declines in mortality, supporting an aymmetric response to actual deaths. For 2 reasons, the danger of the symmetry restriction may be especially pervasive. 1st, unlike most other linear constraints, symmetry is passively imposed merely by ignoring the possibility of asymmetry. 2nd, modles in a wide range of fields--including macroeconomics (e.g., demand for money, consumption, and investment models, and the Phillips curve), international economics (e.g., intervention models of central banks), and labor economics (e.g., sticky wage
Topological Symmetry, Spin Liquids and CFT Duals of Polyakov Model with Massless Fermions
Energy Technology Data Exchange (ETDEWEB)
Unsal, Mithat
2008-04-30
We prove the absence of a mass gap and confinement in the Polyakov model with massless complex fermions in any representation of the gauge group. A U(1){sub *} topological shift symmetry protects the masslessness of one dual photon. This symmetry emerges in the IR as a consequence of the Callias index theorem and abelian duality. For matter in the fundamental representation, the infrared limits of this class of theories interpolate between weakly and strongly coupled conformal field theory (CFT) depending on the number of flavors, and provide an infinite class of CFTs in d = 3 dimensions. The long distance physics of the model is same as certain stable spin liquids. Altering the topology of the adjoint Higgs field by turning it into a compact scalar does not change the long distance dynamics in perturbation theory, however, non-perturbative effects lead to a mass gap for the gauge fluctuations. This provides conceptual clarity to many subtle issues about compact QED{sub 3} discussed in the context of quantum magnets, spin liquids and phase fluctuation models in cuprate superconductors. These constructions also provide new insights into zero temperature gauge theory dynamics on R{sup 2,1} and R{sup 2,1} x S{sup 1}. The confined versus deconfined long distance dynamics is characterized by a discrete versus continuous topological symmetry.
Approximate Bregman near neighbors in sublinear time: Beyond the triangle inequality
Abdullah, Amirali; Venkatasubramanian, Suresh
2011-01-01
Bregman divergences are important distance measures that are used extensively in data-driven applications such as computer vision, text mining, and speech processing, and are a key focus of interest in machine learning. Answering nearest neighbor (NN) queries under these measures very important in these applications and has been the subject of extensive study, but is problematic because these distance measures lack metric properties like symmetry and the triangle inequality. In this paper, we present the first approximate nearest-neighbor (ANN) algorithms, which run in polylog(n) time for Bregman divergences of fixed dimension. To do so, we explore two properties of Bregman divergences that are vital to the analysis: a reverse triangle inequality (RTI) and a relaxed triangle inequality called mu-defectiveness. We show that even though Bregman divergences do not satisfy the triangle inequality, the above properties can be utilized to design an efficient search data structure that follows the general two-stage ...
Symplectic Symmetry and the Ab Initio No-Core Shell Model
Energy Technology Data Exchange (ETDEWEB)
Draayer, Jerry P.; Dytrych, Tomas; Sviratcheva, Kristina D.; Bahri, Chairul; /Louisiana State U.; Vary, James P.; /Iowa State U. /LLNL, Livermore /SLAC
2007-03-14
The symplectic symmetry of eigenstates for the 0{sub gs}{sup +} in {sup 16}O and the 0{sub gs}{sup +} and lowest 2{sup +} and 4{sup +} configurations of {sup 12}C that are well-converged within the framework of the no-core shell model with the JISP16 realistic interaction is examined. These states are found to project at the 85-90% level onto very few symplectic representations including the most deformed configuration, which confirms the importance of a symplectic no-core shell model and reaffirms the relevance of the Elliott SU(3) model upon which the symplectic scheme is built.
Teleparallel dark energy model with a fermionic field via Noether symmetry
Energy Technology Data Exchange (ETDEWEB)
Kucukakca, Yusuf [Akdeniz University, Department of Physics, Faculty of Science, Antalya (Turkey)
2014-10-15
In the present work, we consider a model with a fermionic field that is non-minimally coupled to gravity in the framework of teleparallel gravity. In order to determine the forms of the coupling and potential function of fermionic field for the considered model, we use the Noether symmetry approach. By applying this approach, for the Friedman-Robertson-Walker metric, we obtain the respective potential and coupling functions as a linear and power-law form of the bilinear Ψ. Furthermore, we search for the exact cosmological solution of the model. It is shown that the fermionic field plays the role of dark energy. (orig.)
Nuclear symmetry energy in a modified quark-meson coupling model
Mishra, R. N.; Sahoo, H. S.; Panda, P. K.; Barik, N.; Frederico, T.
2015-10-01
We study nuclear symmetry energy and the thermodynamic instabilities of asymmetric nuclear matter in a self-consistent manner by using a modified quark-meson coupling model where the confining interaction for quarks inside a nucleon is represented by a phenomenologically averaged potential in an equally mixed scalar-vector harmonic form. The nucleon-nucleon interaction in nuclear matter is then realized by introducing additional quark couplings to σ ,ω , and ρ mesons through mean-field approximations. We find an analytic expression for the symmetry energy Esym as a function of its slope L . Our result establishes a linear correlation between L and Esym. We also analyze the constraint on neutron star radii in (p n ) matter with β equilibrium.
Chiral Symmetry Breaking and External Fields in the Kuperstein-Sonnenschein Model
Alam, M Sohaib; Kundu, Arnab
2012-01-01
A novel holographic model of chiral symmetry breaking has been proposed by Kuperstein and Sonnenschein by embedding non-supersymmetric probe D7 and anti-D7 branes in the Klebanov-Witten background. We study the dynamics of the probe flavours in this model in the presence of finite temperature and a constant electromagnetic field. In keeping with the weakly coupled field theory intuition, we find the magnetic field promotes spontaneous breaking of chiral symmetry whereas the electric field restores it. The former effect is universally known as the "magnetic catalysis" in chiral symmetry breaking. In the presence of an electric field such a condensation is inhibited and a current flows. Thus we are faced with a steady-state situation rather than a system in equilibrium. We conjecture a definition of thermodynamic free energy for this steady-state phase and using this proposal we study the detailed phase structure when both electric and magnetic fields are present in two representative configurations: mutually p...
Correspondences between WZNW models and CFTs with W-algebra symmetry
Creutzig, Thomas; Hikida, Yasuaki; Rønne, Peter B.
2016-02-01
We study theories with W-algebra symmetries and their relation to WZNW-type models on (super-)groups generalizing the H 3 + WZNW to Liouville correspondence. Correlation functions of the WZNW models are expressed in terms of correlators of CFTs with W-algebra symmetry. The symmetries of the theories involved in these correspondences are related by the Drinfeld-Sokolov reduction of Lie algebras to W-algebras. The W-algebras considered in this paper are the Bershadsky-Polyakov algebra for sl(3) and the quasi-superconformal algebra for generic sl( N| M). The quantum W-algebras obtained from affine sl( N) are constructed using embeddings of sl(2) into sl( N), and these can in turn be characterized by partitions of N. The above cases correspond to N + 2 = 2 + N 1 and its supergroup extension. Finally, sl(2 N) and the correspondence corresponding to 2 N = N 2 is also analyzed. These are all W-algebras that are generated by fields of at most dimension two.
Novel symmetries in an interacting 𝒩 = 2 supersymmetric quantum mechanical model
Krishna, S.; Shukla, D.; Malik, R. P.
2016-07-01
In this paper, we demonstrate the existence of a set of novel discrete symmetry transformations in the case of an interacting 𝒩 = 2 supersymmetric quantum mechanical model of a system of an electron moving on a sphere in the background of a magnetic monopole and establish its interpretation in the language of differential geometry. These discrete symmetries are, over and above, the usual three continuous symmetries of the theory which together provide the physical realizations of the de Rham cohomological operators of differential geometry. We derive the nilpotent 𝒩 = 2 SUSY transformations by exploiting our idea of supervariable approach and provide geometrical meaning to these transformations in the language of Grassmannian translational generators on a (1, 2)-dimensional supermanifold on which our 𝒩 = 2 SUSY quantum mechanical model is generalized. We express the conserved supercharges and the invariance of the Lagrangian in terms of the supervariables (obtained after the imposition of the SUSY invariant restrictions) and provide the geometrical meaning to (i) the nilpotency property of the 𝒩 = 2 supercharges, and (ii) the SUSY invariance of the Lagrangian of our 𝒩 = 2 SUSY theory.
Elizalde, E; Odintsov, S D; Shilnov, Yu I; Shil'nov, Yu. I.
1998-01-01
A four-fermion model with additional higher-derivative terms is investigated in an external electromagnetic field. The effective potential in the leading order of large-N expansion is calculated in external constant magnetic and electric fields. It is shown that, in contrast to the former results concerning the universal character of "magnetic catalysis" in dynamical symmetry breaking, in the present higher-derivative model the magnetic field restores chiral symmetry broken initially on the tree level. Numerical results describing a second-order phase transition that accompanies the symmetry restoration at the quantum level are presented.
Jia, L Y
2016-01-01
The particle-hole symmetry (equivalence) of the full shell-model Hilbert space is straightforward and routinely used in practical calculations. In this work we show that this symmetry is preserved in the subspace truncated at a certain generalized seniority, and give the explicit transformation between the states in the two types (particle and hole) of representations. Based on the results, we study the particle-hole symmetry in popular theories that could be regarded as further truncations on top of the generalized seniority, including the microscopic interacting boson (fermion) model, the nucleon-pair approximation, and others.
Cumulants of the three-state Potts model and of nonequilibrium models with C{sub 3v} symmetry
Energy Technology Data Exchange (ETDEWEB)
Tome, Tania [Instituto de Fisica, Universidade de Sao Paulo, Sao Paulo, SP (Brazil); Petri, Alberto [Istituto di Acustica O M Corbino, Consiglio Nazionale delle Ricerche, Via del Fosso del Cavaliere, Rome (Italy)
2002-07-05
The critical behaviour of two-dimensional stochastic lattice gas models with C{sub 3v} symmetry is analysed. We study the cumulants of the order parameter for the three-state (equilibrium) Potts model and for two irreversible models whose dynamic rules are invariant under the symmetry operations of the point group C{sub 3v}. By means of extensive numerical analysis of the phase transition we show that irreversibility does not affect the critical behaviour of the systems. In particular, we find that the Binder reduced fourth-order cumulant takes a universal value U* which is the same for the three-state Potts model and for the irreversible models. The same universal behaviour is observed for the reduced third-order cumulant. (author)
Charged Fermion Masses and Mixing from a SU(3) Family Symmetry Model
Hernandez-Galeana, Albino
2016-01-01
Within the framework of a Beyond Standard Model (BSM) with a local $SU(3)$ family symmetry, we report an updated fit of parameters which account for the known spectrum of quarks and charged lepton masses and the quark mixing in a $4\\times 4$ non-unitary $V_{CKM}$. In this scenario, ordinary heavy fermions, top and bottom quarks and tau lepton, become massive at tree level from Dirac See-saw mechanisms implemented by the introduction of a new set of $SU(2)_L$ weak singlet vector-like fermions, $U,D,E,N$, with $N$ a sterile neutrino. The $N_{L,R}$ sterile neutrinos allow the implementation of a $8\\times 8$ general See-saw Majorana neutrino mass matrix with four massless eigenvalues at tree level. Hence, light fermions, including neutrinos, obtain masses from loop radiative corrections mediated by the massive $SU(3)$ gauge bosons. $SU(3)$ family symmetry is broken spontaneously in two stages, whose hierarchy of scales yield an approximate $SU(2)$ global symmetry associated with the $Z_1, Y_1^\\pm$ gauge boson mas...
Supervariable Approach to the Nilpotent Symmetries for a Toy Model of the Hodge Theory
Directory of Open Access Journals (Sweden)
D. Shukla
2016-01-01
Full Text Available We exploit the standard techniques of the supervariable approach to derive the nilpotent Becchi-Rouet-Stora-Tyutin (BRST and anti-BRST symmetry transformations for a toy model of the Hodge theory (i.e., a rigid rotor and provide the geometrical meaning and interpretation to them. Furthermore, we also derive the nilpotent (anti-co-BRST symmetry transformations for this theory within the framework of the above supervariable approach. We capture the (anti-BRST and (anti-co-BRST invariance of the Lagrangian of our present theory within the framework of augmented supervariable formalism. We also express the (anti-BRST and (anti-co-BRST charges in terms of the supervariables (obtained after the application of the (dual-horizontality conditions and (anti-BRST and (anti-co-BRST invariant restrictions to provide the geometrical interpretations for their nilpotency and anticommutativity properties. The application of the dual-horizontality condition and ensuing proper (i.e., nilpotent and absolutely anticommuting fermionic (anti-co-BRST symmetries are completely novel results in our present investigation.
A Three-Loop Neutrino Model with Global $U(1)$ Symmetry
Hatanaka, Hisaki; Okada, Hiroshi; Orikasa, Yuta
2014-01-01
We study a three-loop induced neutrino model with a global $U(1)$ symmetry at TeV scale, in which we naturally accommodate a bosonic dark matter candidate. We discuss the allowed regions of masses and quartic couplings for charged scalar bosons as well as the dark matter mass on the analogy of the original Zee-Babu model, and show the difference between them. We also discuss the possibility of the collider searches, in which future like-sign electron liner collider could be promising.
Spontaneous symmetry breaking in three-Higgs-doublet S 3-symmetric models
Emmanuel-Costa, D.; Ogreid, O. M.; Osland, P.; Rebelo, M. N.
2017-07-01
The talk summarises work done by the authors consisting of a detailed study of the possible vacua in models with three Higgs doublets with S 3 symmetry and without explicit CP violation. Different vacua require special regions of the parameter space which were analysed in our work. We establish the possibility of spontaneous CP violation in this framework and we also show which complex vacua conserve CP. In our work we discussed constraints from vacuum stability. The results presented here are relevant for model building.
The 750 GeV Diphoton excess in a $U(1)$ hidden symmetry model
Das, Kasinath
2015-01-01
Recent results from the experimental collaborations at LHC give hints of a resonance in the diphoton channel at an invariant mass of 750 GeV. We show that such a scalar resonance would be possible in an $U(1)$ extension of the SM where the extended symmetry is hidden and yet to be discovered. We explore the possibilities of accommodating this excess by introducing a minimal extension to the matter content and highlight the parameter space that can accommodate the observed diphoton resonance in the model. The model also predicts new interesting signals that may be observed at the current LHC run.
Predictivity of models with spontaneously broken non-Abelian discrete flavor symmetries
Chen, Mu-Chun; Fallbacher, Maximilian; Omura, Yuji; Ratz, Michael; Staudt, Christian
2013-08-01
In a class of supersymmetric flavor models predictions are based on residual symmetries of some subsectors of the theory such as those of the charged leptons and neutrinos. However, the vacuum expectation values of the so-called flavon fields generally modify the Kähler potential of the setting, thus changing the predictions. We derive simple analytic formulae that allow us to understand the impact of these corrections on the predictions for the masses and mixing parameters. Furthermore, we discuss the effects on the vacuum alignment and on flavor changing neutral currents. Our results can also be applied to non-supersymmetric flavor models.
Predictivity of models with spontaneously broken non-Abelian discrete flavor symmetries
Chen, Mu-Chun; Omura, Yuji; Ratz, Michael; Staudt, Christian
2013-01-01
In a class of supersymmetric flavor models predictions are based on residual symmetries of some subsectors of the theory such as those of the charged leptons and neutrinos. However, the vacuum expectation values of the so-called flavon fields generally modify the K\\"ahler potential of the setting, thus changing the predictions. We derive simple analytic formulae that allow us to understand the impact of these corrections on the predictions for the masses and mixing parameters. Furthermore, we discuss the effects on the vacuum alignment and on flavor changing neutral currents. Our results can also be applied to non--supersymmetric flavor models.
A three-loop neutrino model with global U(1 symmetry
Directory of Open Access Journals (Sweden)
Hisaki Hatanaka
2015-05-01
Full Text Available We study a three-loop induced neutrino model with a global U(1 symmetry at TeV scale, in which we naturally accommodate a bosonic dark matter candidate. We discuss the allowed regions of masses and quartic couplings for charged scalar bosons as well as the dark matter mass on the analogy of the original Zee–Babu model, and show the difference between them. We also discuss that the possibility of the collider searches in a future like-sign electron liner collider could be promising.
Fermionic Symmetry-Protected Topological Phase in a Two-Dimensional Hubbard Model
Chen, Cheng-Chien; Muechler, Lukas; Car, Roberto; Neupert, Titus; Maciejko, Joseph
2016-08-01
We study the two-dimensional (2D) Hubbard model using exact diagonalization for spin-1 /2 fermions on the triangular and honeycomb lattices decorated with a single hexagon per site. In certain parameter ranges, the Hubbard model maps to a quantum compass model on those lattices. On the triangular lattice, the compass model exhibits collinear stripe antiferromagnetism, implying d -density wave charge order in the original Hubbard model. On the honeycomb lattice, the compass model has a unique, quantum disordered ground state that transforms nontrivially under lattice reflection. The ground state of the Hubbard model on the decorated honeycomb lattice is thus a 2D fermionic symmetry-protected topological phase. This state—protected by time-reversal and reflection symmetries—cannot be connected adiabatically to a free-fermion topological phase.
The star-triangle relation and 3d superconformal indices
Gahramanov, I
2015-01-01
Superconformal indices of 3d N=2 supersymmetric field theories are investigated from the Yang-Baxter equation point of view. Solutions of the star-triangle relation, vertex and IRF Yang-Baxter equations are expressed in terms of the q-special functions associated with these 3d indices. For a two-dimensional monopole-spin system on the square lattice a free energy per spin is explicitly determined. Similar to the partition functions, superconformal indices of 3d theories with the chiral symmetry breaking reduce to Dirac delta functions with the support on chemical potentials of the preserved flavor groups.
Tadpole-Induced Electroweak Symmetry Breaking and pNGB Higgs Models
Harnik, Roni; Kearney, John
2016-01-01
We investigate induced electroweak symmetry breaking (EWSB) in models in which the Higgs is a pseudo-Nambu-Goldstone boson (pNGB). In pNGB Higgs models, Higgs properties and precision electroweak measurements imply a hierarchy between the EWSB and global symmetry-breaking scales, $v_H \\ll f_H$. When the pNGB potential is generated radiatively, this hierarchy requires fine-tuning to a degree of at least $\\sim v_H^2/f_H^2$. We show that if Higgs EWSB is induced by a tadpole arising from an auxiliary sector at scale $f_\\Sigma \\ll v_H$, this tuning is significantly ameliorated or can even be removed. We present explicit examples both in Twin Higgs models and in Composite Higgs models based on $SO(5)/SO(4)$. For the Twin case, the result is a fully natural model with $f_H \\sim 1$ TeV and the lightest colored top partners at 2 TeV. These models also have an appealing mechanism to generate the scales of the auxiliary sector and Higgs EWSB directly from the scale $f_H$, with a natural hierarchy $f_\\Sigma \\ll v_H \\ll ...
Tadpole-Induced Electroweak Symmetry Breaking and pNGB Higgs Models
Energy Technology Data Exchange (ETDEWEB)
Harnik, Roni [Fermilab; Howe, Kiel [Fermilab; Kearney, John [Fermilab
2016-03-11
We investigate induced electroweak symmetry breaking (EWSB) in models in which the Higgs is a pseudo-Nambu-Goldstone boson (pNGB). In pNGB Higgs models, Higgs properties and precision electroweak measurements imply a hierarchy between the EWSB and global symmetry-breaking scales, $v_H \\ll f_H$. When the pNGB potential is generated radiatively, this hierarchy requires fine-tuning to a degree of at least $\\sim v_H^2/f_H^2$. We show that if Higgs EWSB is induced by a tadpole arising from an auxiliary sector at scale $f_\\Sigma \\ll v_H$, this tuning is significantly ameliorated or can even be removed. We present explicit examples both in Twin Higgs models and in Composite Higgs models based on $SO(5)/SO(4)$. For the Twin case, the result is a fully natural model with $f_H \\sim 1$ TeV and the lightest colored top partners at 2 TeV. These models also have an appealing mechanism to generate the scales of the auxiliary sector and Higgs EWSB directly from the scale $f_H$, with a natural hierarchy $f_\\Sigma \\ll v_H \\ll f_H \\sim{\\rm TeV}$. The framework predicts modified Higgs coupling as well as new Higgs and vector states at LHC13.
(12) limit and complete classiﬁcation of symmetry schemes in proton–neutron interacting boson model
Indian Academy of Sciences (India)
V K B Kota
2003-01-01
It is shown that the proton–neutron interacting boson model (pnIBM) admits new symmetry limits with (12) algebra which break spin but preserves the quantum number . The generators of (12) are derived and the quantum number of (12) for a given boson number is determined by identifying the corresponding quasi-spin algebra. The (12) algebra generates two symmetry schemes and for both of them, complete classiﬁcation of the basis states and typical spectra are given. With the (12) algebra identiﬁed, complete classiﬁcation of pnIBM symmetry limits with good is established.
The effective Kaehler potential, metastable vacua and R-symmetry breaking in O'Raifeartaigh models
Energy Technology Data Exchange (ETDEWEB)
Benjamin, Shermane; Freund, Christopher [Department of Physics and Astronomy, Rowan University, 201 Mullica Hill Road, Glassboro, NJ 08028 (United States); Kain, Ben, E-mail: kain@rowan.ed [Department of Physics and Astronomy, Rowan University, 201 Mullica Hill Road, Glassboro, NJ 08028 (United States)
2011-01-21
Much has been learned about metastable vacua and R-symmetry breaking in O'Raifeartaigh models. Such work has largely been done from the perspective of the superpotential and by including Coleman-Weinberg corrections to the scalar potential. Instead, we consider these ideas from the perspective of the one loop effective Kaehler potential. We translate known ideas to this framework and construct convenient formulas for computing individual terms in the expanded effective Kaehler potential. We do so for arbitrary R-charge assignments and allow for small R-symmetry violating terms so that both spontaneous and explicit R-symmetry breaking is allowed in our analysis.
Discriminative phenomenological features of scale invariant models for electroweak symmetry breaking
Directory of Open Access Journals (Sweden)
Katsuya Hashino
2016-01-01
Full Text Available Classical scale invariance (CSI may be one of the solutions for the hierarchy problem. Realistic models for electroweak symmetry breaking based on CSI require extended scalar sectors without mass terms, and the electroweak symmetry is broken dynamically at the quantum level by the Coleman–Weinberg mechanism. We discuss discriminative features of these models. First, using the experimental value of the mass of the discovered Higgs boson h(125, we obtain an upper bound on the mass of the lightest additional scalar boson (≃543 GeV, which does not depend on its isospin and hypercharge. Second, a discriminative prediction on the Higgs-photon–photon coupling is given as a function of the number of charged scalar bosons, by which we can narrow down possible models using current and future data for the di-photon decay of h(125. Finally, for the triple Higgs boson coupling a large deviation (∼+70% from the SM prediction is universally predicted, which is independent of masses, quantum numbers and even the number of additional scalars. These models based on CSI can be well tested at LHC Run II and at future lepton colliders.
Muon-Tau Symmetry and Leptogenesis in the Minimal Seesaw Model
Ostrosky, Daniel Wegman
2008-01-01
The measured values for the mixture angles in neutrino oscillations suggest the existence of a symmetry of interchange of flavor between muon and tau neutrinos. Using this symmetry we analyzed the minimal seesaw model for neutrino masses, where the Majorana mass was diagonalized, and it is demonstrated that the model supports at most 3 CP violation phases and 5 real masses at high energies. Nevertheless, at low energies, only 4 parameters of mass and one relative Majorana CP phase remain. Therefore using the experimental values of the masses square differences, the mixture angles and the hierarchy, we can determine some parameters of the model but not all. Also we propose the use of the parameter of baryonic asymmetry of the universe due to leptogenesis to determine one more phase of the model. Finally we used a normal hierarchy for the masses of the right handed neutrinos to make an approximation, that allowed us to completely reconstruct the mass matrix for left handed neutrinos. In special the value of mee...
Radiative Symmetry Breaking in the Supersymmetric Minimal B-L Extended Standard Model
Burell, Zachary
2016-01-01
The Standard Model (SM) of particle physics is a precise model of electroweak interactions, however there is growing tension between the SM and observations (neutrino oscillations, dark matter, dark energy, baryogenesis, among others). There is no reason to expect the validity of the ad hoc SM to remain intact at energy scales above a few TeV, thus a more fundamental theory will almost certainly be required. Motivated by these considerations, we investigate a Supersymmetric version of a natural extension of the SM, the $U(1)_{B-L}$ model, that is obtained by gauging the accidental B-L symmetry that exists in the ordinary SM. The Supersymmetric $U(1)_{B-L}$ extended SM can resolve the neutrino mass problem, the dark matter problem, the hierarchy problem, and provides a mechanism for establishing the observed baryon asymmetry of the Universe. When we include quantum corrections to the Higgs potential of the model, we find that Radiative $B-L$ symmetry breaking occurs through the interplay between large Majorana...
Symmetry Breaking and Adaptation Evidence from a Toy Model of a Virus
Mora, J; Waelbroeck, H
1997-01-01
We argue that the phenomenon of symmetry breaking in genetics can enhance the adaptability of a species to changes in the environment. In the case of a virus, the claim is that the codon bias in the neutralization epitope improves the virus' ability to generate mutants that evade the induced immune response. We support our claim with a simple ``toy model'' of a viral epitope evolving in competition with the immune system. The effective selective advantage of a higher mutability leads to a dominance of codons that favour non-synonymous mutations. The results in this paper suggest the possibility of emergence of an algorithmic language in more complicated systems.
Scalar sector properties of two-Higgs-doublet models with a global U(1) symmetry
Bhattacharyya, Gautam; Pal, Palash B; Rebelo, M N
2013-01-01
We analyze the scalar sector properties of a general class of two-Higgs-doublet models which has a global U(1) symmetry in the quartic terms. We find constraints on the parameters of the potential from the considerations of unitarity of scattering amplitudes, the global stability of the potential and the $\\rho$-parameter. We concentrate on the spectrum of the non-standard scalar masses in the decoupling limit which is preferred by the Higgs data at the LHC. We exhibit charged-Higgs induced contributions to the diphoton decay width of the 125\\,GeV Higgs boson and its correlation with the corresponding $Z\\gamma$ width.
Scalar sector properties of two-Higgs-doublet models with a global U(1) symmetry
Bhattacharyya, Gautam; Das, Dipankar; Pal, Palash B.; Rebelo, M. N.
2013-01-01
We analyze the scalar sector properties of a general class of two-Higgs-doublet models which has a global U(1) symmetry in the quartic terms. We find constraints on the parameters of the potential from the considerations of unitarity of scattering amplitudes, the global stability of the potential and the $\\rho$-parameter. We concentrate on the spectrum of the non-standard scalar masses in the decoupling limit which is preferred by the Higgs data at the LHC. We exhibit charged-Higgs induced co...
A study of symmetry restoration at finite temperature in the O(4) model using anisotropic lattices
Gavai, R. V.; Heller, U. M.; Karsch, F.; Plache, B.; Neuhaus, T.
Results of investigations of the O(4) spin model at finite temperature using anisotropic lattices are presented. In both the large N approximation and the numerical simulations using the Wolff cluster algorithm we find that the ratio of the symmetry restoration temperature TSR to the Higgs mass mH is independent of the anisotropy. We obtain a lower bound of 0.59 ± 0.04 for the ratio, T SR/m H, at m H ⋍ 0.5 , which is lowered furhter by about 10% at m Ha ⋍ 1 .
A study of symmetry restoration at finite temperature in the O(4) model using anisotropic lattices
Gavai, R V; Karsch, Frithjof; Plache, B; Neuhaus, T
1992-01-01
Results of investigations of the $O(4)$ spin model at finite temperature using anisotropic lattices are presented. In both the large $N$ approximation and the numerical simulations using the Wolff cluster algorithm we find that the ratio of the symmetry restoration temperature $T_{\\rm SR}$ to the Higgs mass $m_{\\rm H}$ is independent of the anisotropy. We obtain a lower bound of $0.59 \\pm 0.04$ for the ratio, $T_{\\rm SR}/m_{\\rm H}$, at $m_{\\rm H}a \\simeq 0.5$, which is lowered further by about $10 \\%$ at $m_{\\rm H}a \\simeq 1.$
Spontaneously Symmetry-Breaking States in the Attractive SU(N) Hubbard Model
Koga, Akihisa; Yanatori, Hiromasa
2017-03-01
We investigate spontaneously symmetry-breaking states in the attractive SU(N) Hubbard model at half filling. Combining dynamical mean-field theory with the continuous-time quantum Monte Carlo method, we obtain finite-temperature phase diagrams for the superfluid state. When N > 2, a second-order phase transition occurs in the weak coupling region, while a first-order phase transition with hysteresis appears in the strong coupling region. We also discuss the stability of the density wave state and clarify the component dependence of the maximum critical temperature.
Evarestov, RA
2015-01-01
This book deals with the theoretical and computational simulation of monoperiodic nanostructures for different classes of inorganic substances. These simulations are related to their synthesis and experimental studies. A theoretical formalism is developed to describe 1D nanostructures with symmetric shapes and morphologies. Three types of models are considered for this aim: (i) nanotubes (rolled from 2D nanolayers and described within the formalism of line symmetry groups); (ii) nanoribbons (obtained from 2D nanolayers by their cutting along the chosen direction of translation); (iii) nanowire
Saadatmand, S. N.; McCulloch, I. P.
2016-09-01
Using density-matrix renormalization-group calculations for infinite cylinders, we elucidate the properties of the spin-liquid phase of the spin-1/2 J1-J2 Heisenberg model on the triangular lattice. We find four distinct ground states characteristic of a nonchiral, Z2 topologically ordered state with vison and spinon excitations. We shed light on the interplay of topological ordering and global symmetries in the model by detecting fractionalization of time-reversal and space-group dihedral symmetries in the anyonic sectors, which leads to the coexistence of symmetry protected and intrinsic topological order. The anyonic sectors, and information on the particle statistics, can be characterized by degeneracy patterns and symmetries of the entanglement spectrum. We demonstrate the ground states on finite-width cylinders are short-range correlated and gapped; however, some features in the entanglement spectrum suggest that the system develops gapless spinonlike edge excitations in the large-width limit.
Ciafaloni, Paolo; Torrente-Lujan, Emilio; Urbano, Alfredo
2009-01-01
We address the problem of rationalizing the pattern of fermion masses and mixings by adding a nonabelian flavor symmetry in a grand unified framework. With this purpose, we include an A4 flavor symmetry into a unified renormalizable SUSY GUT SU(5) model. With the help of the "Type II Seesaw" mechanism we are able to obtain the pattern of observed neutrino mixings in a natural way, through the so called tribimaximal matrix.
Del Cima, Oswaldo M; Piguet, Olivier
2016-01-01
In this paper, we revisit the issue intensively studied in recent years on the generation of terms by radiative corrections in models with broken Lorentz symmetry. The algebraic perturbative method of handling the problem of renormalization of the theories with Lorentz symmetry breaking, is used. We hope to make clear the Symanzik's aphorism: "{\\it Whether you like it or not, you have to include in the lagrangian all counter terms consistent with locality and power-counting, unless otherwise constrained by Ward identities.}"
Energy Technology Data Exchange (ETDEWEB)
Krishna, S., E-mail: skrishna.bhu@gmail.com [Physics Department, Centre of Advanced Studies, Banaras Hindu University (BHU), Varanasi-221 005 (India); Shukla, A., E-mail: ashukla038@gmail.com [Physics Department, Centre of Advanced Studies, Banaras Hindu University (BHU), Varanasi-221 005 (India); Malik, R.P., E-mail: rpmalik1995@gmail.com [Physics Department, Centre of Advanced Studies, Banaras Hindu University (BHU), Varanasi-221 005 (India); DST-CIMS, Faculty of Science, BHU-Varanasi-221 005 (India)
2014-12-15
Using the supersymmetric (SUSY) invariant restrictions on the (anti-)chiral supervariables, we derive the off-shell nilpotent symmetries of the general one (0+1)-dimensional N=2 SUSY quantum mechanical (QM) model which is considered on a (1, 2)-dimensional supermanifold (parametrized by a bosonic variable t and a pair of Grassmannian variables θ and θ-bar with θ{sup 2}=(θ-bar){sup 2}=0,θ(θ-bar)+(θ-bar)θ=0). We provide the geometrical meanings to the two SUSY transformations of our present theory which are valid for any arbitrary type of superpotential. We express the conserved charges and Lagrangian of the theory in terms of the supervariables (that are obtained after the application of SUSY invariant restrictions) and provide the geometrical interpretation for the nilpotency property and SUSY invariance of the Lagrangian for the general N=2 SUSY quantum theory. We also comment on the mathematical interpretation of the above symmetry transformations. - Highlights: • A novel method has been proposed for the derivation of N=2 SUSY transformations. • General N=2 SUSY quantum mechanical (QM) model with a general superpotential, is considered. • The above SUSY QM model is generalized onto a (1, 2)-dimensional supermanifold. • SUSY invariant restrictions are imposed on the (anti-)chiral supervariables. • Geometrical meaning of the nilpotency property is provided.
Symmetry classes of alternating sign matrices in a nineteen-vertex model
Hagendorf, Christian; Morin-Duchesne, Alexi
2016-05-01
The nineteen-vertex model of Fateev and Zamolodchikov on a periodic lattice with an anti-diagonal twist is investigated. Its inhomogeneous transfer matrix is shown to have a simple eigenvalue, with the corresponding eigenstate displaying intriguing combinatorial features. Similar results were previously found for the same model with a diagonal twist. The eigenstate for the anti-diagonal twist is explicitly constructed using the quantum separation of variables technique. A number of sum rules and special components are computed and expressed in terms of Kuperberg’s determinants for partition functions of the inhomogeneous six-vertex model. The computations of some components of the special eigenstate for the diagonal twist are also presented. In the homogeneous limit, the special eigenstates become eigenvectors of the Hamiltonians of the integrable spin-one XXZ chain with twisted boundary conditions. Their sum rules and special components for both twists are expressed in terms of generating functions arising in the weighted enumeration of various symmetry classes of alternating sign matrices (ASMs). These include half-turn symmetric ASMs, quarter-turn symmetric ASMs, vertically symmetric ASMs, vertically and horizontally perverse ASMs and double U-turn ASMs. As side results, new determinant and pfaffian formulas for the weighted enumeration of various symmetry classes of alternating sign matrices are obtained.
Astrophysical Constraints on the scale of Left-Right Symmetry in Inverse Seesaw Models
Borah, Debasish
2012-01-01
We revisit the recently studied supersymmetric gauged inverse seesaw model \\cite{An:2011uq} to incorporate astrophysical constraints on lightest supersymmetric particle (LSP) lifetime such that LSP constitutes the dark matter of the Universe. The authors in \\cite{An:2011uq} considered light sneutrino LSP that can play the role of inelastic dark matter (iDM) such that desired iDM mass splitting and tiny Majorana masses of neutrinos can have a common origin. Here we point out that due to spontaneous R-parity $(R_p = (-1)^{3(B-L)+2s})$ breaking in such generic supersymmetric gauged inverse seesaw models, LSP can not be perfectly stable but decays to standard model particles after non-renormalizable operators allowed by the gauge symmetry are introduced. We show that strong astrophysical constraints on LSP lifetime makes sneutrino dark matter more natural than standard neutralino dark matter. We also show that long-livedness of sneutrino dark matter constrains the left right symmetry breaking scale $M_R < 10^4...
Lepton Flavour Violation in a Supersymmetric Model with A4 Flavour Symmetry
Feruglio, Ferruccio; Lin, Yin; Merlo, Luca
2009-01-01
We compute the branching ratios for mu-> e gamma, tau-> mu gamma and tau -> e gamma in a supersymmetric model invariant under the flavour symmetry group A4 X Z3 X U(1)_{FN}, in which near tri-bimaximal lepton mixing is naturally predicted. At leading order in the small symmetry breaking parameter u, which is of the same order as the reactor mixing angle theta_{13}, we find that the branching ratios generically scale as u^2. Applying the current bound on the branching ratio of mu -> e gamma shows that small values of u or tan(beta) are preferred in the model for mass parameters m_{SUSY} and m_{1/2} smaller than 1000 GeV. The bound expected from the on-going MEG experiment will provide a severe constraint on the parameter space of the model either enforcing u approx 0.01 and small tan(beta) or m_{SUSY} and m_{1/2} above 1000 GeV. In the special case of universal soft supersymmetry breaking terms in the flavon sector a cancellation takes place in the amplitudes and the branching ratios scale as u^4, allowing for...
On the stability of multiscale models of dynamical symmetry breaking from holography
Energy Technology Data Exchange (ETDEWEB)
Faedo, Anton F. [Department of Physics, College of Science, Swansea University, Singleton Park, Swansea, Wales (United Kingdom); Departament de Física Fonamental and Institut de Ciències del Cosmos, Universitat de Barcelona, Martí i Franquès 1, E-08028 Barcelona (Spain); Piai, Maurizio; Schofield, Daniel [Department of Physics, College of Science, Swansea University, Singleton Park, Swansea, Wales (United Kingdom)
2014-03-15
We consider two classes of backgrounds of Type IIB supergravity obtained by wrapping D5-branes on a two-cycle inside the conifold. The field theory dual exhibits confinement and, in addition, a region in which the dynamics is walking, at least in the weak sense that the running of the coupling is anomalously slow. We introduce quenched matter in the fundamental, modeled by probe D7-branes which wrap an internal three-dimensional manifold and lie at the equator of the transverse two-sphere. In the space spanned by the remaining internal angle and the radial coordinate, the branes admit two embeddings. The first one is U-shaped: the branes merge at some finite value of the radius. The second one is disconnected and extends along the entire radial direction at fixed angular separation. We interpret these two configurations as corresponding to chiral-symmetry breaking and preserving phases, respectively. We present a simple diagnostic tool to examine the classical stability of the embedding, based on the concavity/convexity conditions for the relevant thermodynamic potentials. We use this criterion to show that U-shaped probes that explore the walking region are unstable, hence providing a dynamical origin for the tachyonic mode found in the literature. Whenever this occurs, the disconnected solution becomes favored energetically. We find that in one of the two classes of backgrounds the U-shaped embedding is always unstable, and thus never realized dynamically. Consequently, these models cannot be used to describe chiral-symmetry breaking. In the second category of solutions, our analysis reveals the presence of a first-order phase transition between chiral-symmetry broken and restored phases. Interestingly, this is in the same class that contains a parametrically light scalar in the spectrum of glueballs of the dual field theory.
A model of quarks with Δ(6N{sup 2}) family symmetry
Energy Technology Data Exchange (ETDEWEB)
Ishimori, Hajime [Department of Physics, Kyoto University, Kyoto 606-8502 (Japan); King, Stephen F. [School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ (United Kingdom)
2014-07-30
We propose a first model of quarks based on the discrete family symmetry Δ(6N{sup 2}) in which the Cabibbo angle is correctly determined by a residual Z{sub 2}×Z{sub 2} subgroup, and the smaller quark mixing angles may be qualitatively understood from the model. The present model of quarks may be regarded as a first step towards formulating a complete model of quarks and leptons based on Δ(6N{sup 2}), in which the lepton mixing matrix is fully determined by a Klein subgroup. For example, the choice N=28 provides an accurate determination of both the reactor angle and the Cabibbo angle.
Evidence for Symplectic Symmetry in Ab Initio No-Core Shell Model Results for Light Nuclei
Energy Technology Data Exchange (ETDEWEB)
Dytrych, Tomas; Sviratcheva, Kristina D.; Bahri, Chairul; Draayer, Jerry P.; /Louisiana State U.; Vary, James P.; /Iowa State U. /LLNL, Livermore /SLAC
2007-04-24
Clear evidence for symplectic symmetry in low-lying states of {sup 12}C and {sup 16}O is reported. Eigenstates of {sup 12}C and {sup 16}O, determined within the framework of the no-core shell model using the JISP16 NN realistic interaction, typically project at the 85-90% level onto a few of the most deformed symplectic basis states that span only a small fraction of the full model space. The results are nearly independent of whether the bare or renormalized effective interactions are used in the analysis. The outcome confirms Elliott's SU(3) model which underpins the symplectic scheme, and above all, points to the relevance of a symplectic no-core shell model that can reproduce experimental B(E2) values without effective charges as well as deformed spatial modes associated with clustering phenomena in nuclei.
Implications of Lorentz symmetry violation on a 5D supersymmetric model
García-Aguilar, J. D.; Pérez-Lorenzana, A.
2017-04-01
Field models with n extra spatial dimensions have a larger SO(1, 3 + n) Lorentz symmetry which is broken down to the standard SO(1, 3) four-dimensional one by the compactification process. By considering Lorentz violating operators in a 5D supersymmetric Wess-Zumino model, which otherwise conserve the standard four-dimensional Poincaré invariance, we show that supersymmetry (SUSY) can be restored upon a simple deformation of the supersymmetric transformations. However, SUSY is not preserved in the effective 4D theory that arises after compactification when the 5D Lorentz violating operators do not preserve Z2 : y →-y bulk parity. Our mechanism unveils a possible connection among Lorentz violation and the Scherk-Schwarz mechanism. We also show that parity preserving models, on the other hand, do provide well defined supersymmetric KK models.
A model for the implementation of symmetry breaking from B-to-Z-DNA configurations
Reséndiz-Antonio, M.; Godina-Nava, J. J.
2012-02-01
Supported in the helicoidal model performed by M. Barbi et al, we propose a extended Morse potential version to study the symmetry breaking in a simple non-linear DNA model based in two plane base rotors. The intention is study the development of the intermediate states appearing in the junction B-to-Z DNA, useful for understanding its biological function, once is characterized the phase transition involved. With this model, we make a comparison between the non-linear dynamics of a handedness homogeneous base-pair winding in a right-handed sense and a left handed sense. Numerical results determine that the right-handed sense is the preferential direction of winding of our spring's model that can emulate the common DNA behavior.
Nasal Soft-Tissue Triangle Deformities.
Foda, Hossam M T
2016-08-01
The soft-tissue triangle is one of the least areas attended to in rhinoplasty. Any postoperative retraction, notching, or asymmetries of soft triangles can seriously affect the rhinoplasty outcome. A good understanding of the risk factors predisposing to soft triangle deformities is necessary to prevent such problems. The commonest risk factors in our study were the wide vertical domal angle between the lateral and intermediate crura, and the increased length of intermediate crus. Two types of soft triangle grafts were described to prevent and treat soft triangle deformities. The used soft triangle grafts resulted in an excellent long-term aesthetic and functional improvement. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.
Reverse Triangle Inequalities for Potentials
Pritsker, I. E.; Saff, E. B.
2013-01-01
We study the reverse triangle inequalities for suprema of logarithmic potentials on compact sets of the plane. This research is motivated by the inequalities for products of supremum norms of polynomials. We find sharp additive constants in the inequalities for potentials, and give applications of our results to the generalized polynomials. We also obtain sharp inequalities for products of norms of the weighted polynomials $w^nP_n, deg(P_n)\\le n,$ and for sums of suprema of potentials with ex...
Fibonacci's Triangle: A Vehicle for Problem Solving.
Ouellette, Hugh
1979-01-01
A method for solving certain types of problems is illustrated by problems related to Fibonacci's triangle. The method involves pattern recognition, generalizing, algebraic manipulation, and mathematical induction. (MP)
Superfield Approach to Nilpotent Symmetries of the Freedman-Townsend Model: Novel Features
Malik, R. P.
2012-09-01
We perform the Becchi-Rouet-Stora-Tyutin (BRST) analysis of the Freedman-Townsend (FT) model of topologically massive non-Abelian theory by exploiting its (1-form) Yang-Mills (YM) gauge transformations to show the existence of some novel features that are totally different from the results obtained in such a kind of consideration carried out for the dynamical non-Abelian 2-form theory. We tap here the potential and power of the augmented version of Bonora-Tonin's superfield approach to BRST formalism to derive the full set of off-shell nilpotent and absolutely anticommuting (anti-)BRST symmetry transformations where, in addition to the horizontality condition (HC), we are theoretically compelled to exploit the appropriate gauge-invariant restrictions (GIRs) on the (super)fields for the derivation of the appropriate symmetry transformations for all the relevant fields. We compare our key results with that of the other such attempt for the discussion of the present model within the framework of BRST formalism.
Mixed Mediation of Supersymmetry Breaking in Models with Anomalous U(1) Gauge Symmetry
Energy Technology Data Exchange (ETDEWEB)
Choi, Kiwoon, E-mail: kchoi@kaist.ac.kr [Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 305-701 (Korea, Republic of)
2010-11-01
There can be various built-in sources of supersymmetry breaking in models with anomalous U(1) gauge symmetry, e.g. the U(1) D-term, the F-components of the modulus superfield required for the Green-Schwarz anomaly cancellation mechanism and the chiral matter superfields required to cancel the Fayet-Iliopoulos term, and finally the supergravity auxiliary component which can be parameterized by the F-component of chiral compensator. The relative strength between these supersymmetry breaking sources depends crucially on the characteristics of D-flat direction and also on how the D-flat direction is stabilized at a vacuum with nearly vanishing cosmological constant. We examine the possible pattern of the mediation of supersymmetry breaking in models with anomalous U(1) gauge symmetry, and find that various different mixed mediation scenarios can be realized, including the mirage mediation which corresponds to a mixed modulus-anomaly mediation, D-term domination giving a split sparticle spectrum, and also a mixed gauge-D-term mediation scenario.
Fermion unification model based on the intrinsic SU(8 symmetry of a generalized Dirac equation
Directory of Open Access Journals (Sweden)
Eckart eMarsch
2015-10-01
Full Text Available A natural generalization of the original Dirac spinor into a multi-component spinor is achieved, which corresponds to the single lepton and the three quarks of the first family of the standard model of elementary particle physics. Different fermions result from similarity transformations of the Dirac equation, but apparently there can be no more fermions according to the maximal multiplicity revealed in this study. Rotations in the fermion state space are achieved by the unitary generators of the U(1 and the SU(3 groups, corresponding to quantum electrodynamics (QED based on electric charge and chromodynamics (QCD based on colour charge. In addition to hypercharge the dual degree of freedom of hyperspin emerges, which occurs due to the duplicity implied by the two related (Weyl and Dirac representations of the Dirac equation. This yields the SU(2 symmetry of the weak interaction, which can be married to U(1 to generate the unified electroweak interaction as in the standard model. Therefore, the symmetry group encompassing all the three groups mentioned above is SU(8, which can accommodate and unify the observed eight basic stable fermions.
Determination of the CKM unitarity triangle parameters by end 1999
Caravaglios, F; Roudeau, Patrick; Stocchi, A
2000-01-01
Within the Standard Model, a review of the current determination of the CKMunitarity triangle parameters is presented, using experimental constraints fromthe measurements of |epsilon_K|, V_ub/V_cb, Delta m_d and from the limit onDelta m_s, available by end 1999.
CP-odd invariants for multi-Higgs models: applications with discrete symmetry
Varzielas, Ivo de Medeiros; Luhn, Christoph; Neder, Thomas
2016-01-01
CP-odd invariants provide a basis independent way of studying the CP properties of Lagrangians. We propose powerful methods for constructing basis invariants and determining whether they are CP-odd or CP-even, then systematically construct all of the simplest CP-odd invariants up to a given order, finding many new ones. The CP-odd invariants are valid for general potentials when expressed in a standard form. We then apply our results to scalar potentials involving three (or six) Higgs fields which form irreducible triplets under a discrete symmetry, including invariants for both explicit as well as spontaneous CP violation. The considered cases include one triplet of Standard Model (SM) gauge singlet scalars, one triplet of SM Higgs doublets, two triplets of SM singlets, and two triplets of SM Higgs doublets. For each case we study the potential symmetric under one of the simplest discrete symmetries with irreducible triplet representations, namely $A_4$, $S_4$, $\\Delta(27)$ or $\\Delta(54)$, as well as the in...
Escobar, C A
2015-01-01
After imposing current conservation together with the Gauss law as initial conditions on the Abelian Nambu model, we prove that the resulting theory is equivalent to standard QED in the non-linear gauge $\\left(A_{\\mu }A^{\\mu }-n^{2}M^{2}\\right)=0$, to all orders in perturbation theory. We show this by writing both models in terms of the same variables, which produce identical Feynman rules for the interactions and propagators. A crucial point is to verify that the Faddeev-Popov ghosts arising from the gauge fixing procedure in the QED sector decouple to all orders. We verify this decoupling by following a method like that employed in Yang-Mills theories when investigating the behavior of axial gauges. The equivalence between the two theories supports the idea that gauge particles can be envisaged as the Goldstone bosons originating from spontaneous Lorentz symmetry breaking.
The nuclear symmetry energy, the inner crust, and global neutron star modeling
Newton, William G; Hooker, Josh; Li, Bao-An
2011-01-01
The structure and composition of the inner crust of neutron stars, as well as global stellar properties such as radius and moment of inertia, have been shown to correlate with parameters characterizing the symmetry energy of nuclear matter such as its magnitude J and density dependence L at saturation density. It is thus mutually beneficial to nuclear physicists and astrophysicists to examine the combined effects of such correlations on potential neutron star observables in the light of recent experimental and theoretical constraints on J, L, and relationships between them. We review some basic correlations between these nuclear and astrophysical observables, and illustrate the impact of recent progress in constraining the J-L parameter space on the composition of the inner crust, crust-core transition density and pressure, and extent of the hypothesized pasta region. We use a simple compressible liquid drop model in conjunction with a simple model of nuclear matter which allows for independent, smooth, varia...
Quantum Local Symmetry of the D-Dimensional Non-Linear Sigma Model: A Functional Approach
Directory of Open Access Journals (Sweden)
Andrea Quadri
2014-04-01
Full Text Available We summarize recent progress on the symmetric subtraction of the Non-Linear Sigma Model in D dimensions, based on the validity of a certain Local Functional Equation (LFE encoding the invariance of the SU(2 Haar measure under local left transformations. The deformation of the classical non-linearly realized symmetry at the quantum level is analyzed by cohomological tools. It is shown that all the divergences of the one-particle irreducible (1-PI amplitudes (both on-shell and off-shell can be classified according to the solutions of the LFE. Applications to the non-linearly realized Yang-Mills theory and to the electroweak theory, which is directly relevant to the model-independent analysis of LHC data, are briefly addressed.
Unstable spiral waves and local Euclidean symmetry in a model of cardiac tissue
Energy Technology Data Exchange (ETDEWEB)
Marcotte, Christopher D.; Grigoriev, Roman O. [School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States)
2015-06-15
This paper investigates the properties of unstable single-spiral wave solutions arising in the Karma model of two-dimensional cardiac tissue. In particular, we discuss how such solutions can be computed numerically on domains of arbitrary shape and study how their stability, rotational frequency, and spatial drift depend on the size of the domain as well as the position of the spiral core with respect to the boundaries. We also discuss how the breaking of local Euclidean symmetry due to finite size effects as well as the spatial discretization of the model is reflected in the structure and dynamics of spiral waves. This analysis allows identification of a self-sustaining process responsible for maintaining the state of spiral chaos featuring multiple interacting spirals.
Antonov, A N; Sarriguren, P; de Guerra, E Moya
2016-01-01
The volume and surface components of the nuclear symmetry energy (NSE) and their ratio are calculated within the coherent density fluctuation model (CDFM). The estimations use the results of the model for the NSE in finite nuclei based on the Brueckner energy-density functional for nuclear matter. In addition, we present results for the NSE and its volume and surface contributions obtained by using the Skyrme energy-density functional. The CDFM weight function is obtained using the proton and neutron densities from the self-consistent HF+BCS method with Skyrme interactions. We present and discuss the values of the volume and surface contributions to the NSE and their ratio obtained for the Ni, Sn, and Pb isotopic chains studying their isotopic sensitivity. The results are compared with estimations of other approaches which have used available experimental data on binding energies, neutron-skin thicknesses, excitation energies to isobaric analog states (IAS) and also with results of other theoretical methods.
Atomki anomaly and dark matter in a radiative seesaw model with gauged $B-L$ symmetry
Seto, Osamu
2016-01-01
Motivated by recently reported anomalies in a decay of an excited state of beryllium by the Atomki collaboration, we study a radiative seesaw model with gauged $B-L$ symmetry and a $Z_2$ parity. Assuming that the anomalies originate from the decay of the $B-L$ gauge boson followed by the nuclear decay, the mass of the lightest right-handed neutrino or the dark matter candidate can be determined below $10$ GeV. We show that for this mass range, the model can explain the anomalies in the beryllium decay and the relic dark matter abundance consistent with neutrino masses. We also predict its spin-independent cross section in direct detection experiments for this mass range.
Non-zero $\\theta_{13}$ and CP violation in a model with $A_4$ flavor symmetry
Ahn, Y H
2012-01-01
Motivated by $5.2\\sigma$ observation of non-zero $\\theta_{13}$ from the Daya Bay experiment, we propose a renormalizable neutrino model with $A_4$ discrete symmetry accounting for deviations from the tri-bimaximal (TBM) mixing pattern of neutrino mixing matrix indicated by neutrino oscillation data. In the model, the light neutrino masses can be generated by radiative corrections, and we show how the light neutrino mass matrix can be diagonalized by the PMNS mixing matrix whose entries are determined by the current neutrino data including the Daya Bay result. We show that the origin of the deviations from the TBM mixing is non-degeneracy of the neutrino Yukawa coupling constants, and unremovable CP phases in the neutrino Yukawa matrix give rise to the low energy CP violation measurable from neutrino oscillation as well as high energy CP violation required for leptogenesis.
Unification of gauge, family, and flavor symmetries illustrated in gauged SU(12) models
Albright, Carl H.; Feger, Robert P.; Kephart, Thomas W.
2016-04-01
To explain quark and lepton masses and mixing angles, one has to extend the standard model, and the usual practice is to put the quarks and leptons into irreducible representations of discrete groups. We argue that discrete flavor symmetries (and their concomitant problems) can be avoided if we extend the gauge group. In the framework of SU(12) we give explicit examples of models having varying degrees of predictability obtained by scanning over groups and representations and identifying cases with operators contributing to mass and mixing matrices that need little fine-tuning of prefactors. Fitting with quark and lepton masses run to the GUT scale and known mixing angles allows us to make predictions for the neutrino masses and hierarchy, the octant of the atmospheric mixing angle, leptonic C P violation, Majorana phases, and the effective mass observed in neutrinoless double beta decay.
Unification of gauge, family, and flavor symmetries illustrated in gauged SU(12) models
Albright, Carl H; Kephart, Thomas W
2016-01-01
To explain quark and lepton masses and mixing angles, one has to extend the standard model, and the usual practice is to put the quarks and leptons into irreducible representations of discrete groups. We argue that discrete flavor symmetries (and their concomitant problems) can be avoided if we extend the gauge group. In the framework of SU(12) we give explicit examples of models having varying degrees of predictability obtained by scanning over groups and representations and identifying cases with operators contributing to mass and mixing matrices that need little fine- tuning of prefactors. Fitting with quark and lepton masses run to the GUT scale and known mixing angles allows us to make predictions for the neutrino masses and hierarchy, the octant of the atmospheric mixing angle, leptonic CP violation, Majorana phases, and the effective mass observed in neutrinoless double beta decay.
Symmetries in atmospheric sciences
Bihlo, Alexander
2009-01-01
Selected applications of symmetry methods in the atmospheric sciences are reviewed briefly. In particular, focus is put on the utilisation of the classical Lie symmetry approach to derive classes of exact solutions from atmospheric models. This is illustrated with the barotropic vorticity equation. Moreover, the possibility for construction of partially-invariant solutions is discussed for this model. A further point is a discussion of using symmetries for relating different classes of differential equations. This is illustrated with the spherical and the potential vorticity equation. Finally, discrete symmetries are used to derive the minimal finite-mode version of the vorticity equation first discussed by E. Lorenz (1960) in a sound mathematical fashion.
Cycle-maximal triangle-free graphs
DEFF Research Database (Denmark)
Durocher, Stephane; Gunderson, David S.; Li, Pak Ching;
2015-01-01
Abstract We conjecture that the balanced complete bipartite graph K ⌊ n / 2 ⌋ , ⌈ n / 2 ⌉ contains more cycles than any other n -vertex triangle-free graph, and we make some progress toward proving this. We give equivalent conditions for cycle-maximal triangle-free graphs; show bounds...
Representations of Subgroups of Universal Triangle Groups
Institute of Scientific and Technical Information of China (English)
Jianguo Xia
2007-01-01
Let G be a universal triangle group, and H a subgroup of G such that the chamber system △H is a tight triangle geometryThen H, which is canonically isomorphic to the topological fundamental group π1(△H) of △ H, is a finitely presented group.For some H we give their representations.
Circumcenter, Circumcircle and Centroid of a Triangle
Directory of Open Access Journals (Sweden)
Coghetto Roland
2016-03-01
Full Text Available We introduce, using the Mizar system [1], some basic concepts of Euclidean geometry: the half length and the midpoint of a segment, the perpendicular bisector of a segment, the medians (the cevians that join the vertices of a triangle to the midpoints of the opposite sides of a triangle.
Partitioning Pythagorean Triangles Using Pythagorean Angles
Swenson, Carl E.; Yandl, Andre L.
2012-01-01
Inside any Pythagorean right triangle, it is possible to find a point M so that drawing segments from M to each vertex of the triangle yields angles whose sines and cosines are all rational. This article describes an algorithm that generates an infinite number of such points.
The Weimar Triangle and The Ukrainian Crisis
Directory of Open Access Journals (Sweden)
Jean-Christophe Romer
2014-12-01
Full Text Available The article analyzes the activity of Weimar Triangle (Germany, France, Poland during Ukrainian crisis (2013-2014 as an efficient, but still largely underestimated negotiation force of the European Union. The evolution of role of Weimar Triangle in post-bipolar era is indicated, as well as the role of this specific structure during Ukrainian crisis.
Altitude, Orthocenter of a Triangle and Triangulation
Directory of Open Access Journals (Sweden)
Coghetto Roland
2016-03-01
Full Text Available We introduce the altitudes of a triangle (the cevians perpendicular to the opposite sides. Using the generalized Ceva’s Theorem, we prove the existence and uniqueness of the orthocenter of a triangle [7]. Finally, we formalize in Mizar [1] some formulas [2] to calculate distance using triangulation.
Effective theory and emergent SU(2 ) symmetry in the flat bands of attractive Hubbard models
Tovmasyan, Murad; Peotta, Sebastiano; Törmä, Päivi; Huber, Sebastian D.
2016-12-01
In a partially filled flat Bloch band electrons do not have a well defined Fermi surface and hence the low-energy theory is not a Fermi liquid. Nevertheless, under the influence of an attractive interaction, a superconductor well described by the Bardeen-Cooper-Schrieffer (BCS) wave function can arise. Here we study the low-energy effective Hamiltonian of a generic Hubbard model with a flat band. We obtain an effective Hamiltonian for the flat band physics by eliminating higher-lying bands via the perturbative Schrieffer-Wolff transformation. At first order in the interaction energy we recover the usual procedure of projecting the interaction term onto the flat band Wannier functions. We show that the BCS wave function is the exact ground state of the projected interaction Hamiltonian, if a simple uniform pairing condition on the single-particle states is satisfied, and that the compressibility is diverging as a consequence of an emergent SU(2 ) symmetry. This symmetry is broken by second-order interband transitions resulting in a finite compressibility, which we illustrate for a one-dimensional ladder with two perfectly flat bands. These results motivate a further approximation leading to an effective ferromagnetic Heisenberg model. The gauge-invariant result for the superfluid weight of a flat band can be obtained from the ferromagnetic Heisenberg model only if the maximally localized Wannier functions in the Marzari-Vanderbilt sense are used. Finally, we prove an important inequality D ≥W2 between the Drude weight D and the winding number W , which guarantees ballistic transport for topologically nontrivial flat bands in one dimension.
The Top of the Biomimetic Triangle
Institute of Scientific and Technical Information of China (English)
Andrei P. Sommer; Dan Zhu; Matthias Wiora; Hans-Joerg Fecht
2008-01-01
There is increasing observational evidence indicating that crystalline interfacial water layers play a central role in evolution and biology. For instance in cellular recognition processes, in particular during first contact events, where cells decide upon survival or entering apoptosis. Understanding water layers is thus crucial in biomedical engineering, specifically in the design of biomaterials inspired by biomimetic principles. Whereas there is ample experimental evidence for crystalline interfacial water layers on surfaces in air, their subaquatic presence could not be verified directly, so far. Analysing a polarity dependent asym- metry in the surface conductivity on hydrogenated nanocrystalline diamond, we show that crystalline interfacial water layers persist subaquatically. Nanoscopic interfacial water layers with an order different from that of bulk water have been identified at room temperature on both hydrophilic and hydrophobic model surfaces - in air and subaquatically. Their generalization and systematic inclusion into the catalogue of physical and chemical determinants of biocompatibility complete the biomimetic triangle.
Obtuse triangle suppression in anisotropic meshes
Sun, Feng
2011-12-01
Anisotropic triangle meshes are used for efficient approximation of surfaces and flow data in finite element analysis, and in these applications it is desirable to have as few obtuse triangles as possible to reduce the discretization error. We present a variational approach to suppressing obtuse triangles in anisotropic meshes. Specifically, we introduce a hexagonal Minkowski metric, which is sensitive to triangle orientation, to give a new formulation of the centroidal Voronoi tessellation (CVT) method. Furthermore, we prove several relevant properties of the CVT method with the newly introduced metric. Experiments show that our algorithm produces anisotropic meshes with much fewer obtuse triangles than using existing methods while maintaining mesh anisotropy. © 2011 Elsevier B.V. All rights reserved.
The Pascal Triangle of a Discrete Image: Definition, Properties and Application to Shape Analysis
Directory of Open Access Journals (Sweden)
Mireille Boutin
2013-04-01
Full Text Available We define the Pascal triangle of a discrete (gray scale image as a pyramidal arrangement of complex-valued moments and we explore its geometric significance. In particular, we show that the entries of row k of this triangle correspond to the Fourier series coefficients of the moment of order k of the Radon transform of the image. Group actions on the plane can be naturally prolonged onto the entries of the Pascal triangle. We study the prolongation of some common group actions, such as rotations and reflections, and we propose simple tests for detecting equivalences and self-equivalences under these group actions. The motivating application of this work is the problem of characterizing the geometry of objects on images, for example by detecting approximate symmetries.
Pythagorean triangles of equal areas
Directory of Open Access Journals (Sweden)
Malvina Baica
1988-01-01
Full Text Available The main intent in this paper is to find triples of Rational Pythagorean Triangles (abbr. RPT having equal areas. A new method of solving a2+ab+b2=c2 is to set a=y−1, b=y+1, y∈N−{0,1} and get Pell's equation c2−3y2=1. To solve a2−ab−b2=c2, we set a=12(y+1, b=y−1, y≥2, y∈N and get a corresponding Pell's equation. The infinite number of solutions in Pell's equation gives rise to an infinity of solutions to a2±ab+b2=c2. From this fact the following theorems are proved.
Constitutive modelling of magnetic shape memory alloys with discrete and continuous symmetries.
Haldar, K; Lagoudas, D C
2014-09-08
A free energy-based constitutive formulation is considered for magnetic shape memory alloys. Internal state variables are introduced whose evolution describes the transition from reference state to the deformed and transformed one. We impose material symmetry restrictions on the Gibbs free energy and on the evolution equations of the internal state variables. Discrete symmetry is considered for single crystals, whereas continuous symmetry is considered for polycrystalline materials.
LFV and Dipole Moments in Models with A4 Flavour Symmetry
Merlo, Luca
2009-01-01
It is presented an analysis on lepton flavour violating transitions, leptonic magnetic dipole moments and electric dipole moments in a class of models characterized by the flavour symmetry A4 x Z3 x U(1)_FN, whose choice is motivated by the approximate Tri-Bimaximal mixing observed in neutrino oscillations. A low-energy effective Lagrangian is constructed, where these effects are dominated by dimension six operators, suppressed by the scale M of new physics. All the flavour breaking effects are universally described by the vacuum expectation values of a set of spurions. Two separate cases, a supersymmetric and a general one, are described. An upper limit on the reactor angle of a few percent is concluded.
Study of the ${\\eta}^{\\prime}$ ${\\to}$ $Ve^{+}e^{-}$ decay with hidden local symmetry model
Yang, Yueling; Lu, Gongru
2014-01-01
Within the hidden local symmetry framework, the Dalitz decay ${\\eta}^{\\prime}$ ${\\to}$ $Ve^{+}e^{-}$ is studied with the vector meson dominance model. It is found that the partial width ${\\Gamma}({\\eta}^{\\prime}{\\to}{\\omega}e^{+}e^{-})$ ${\\approx}$ $40$ eV and branching ratio ${\\cal B}({\\eta}^{\\prime}{\\to}{\\omega}e^{+}e^{-})$ ${\\approx}$ $2{\\times}10^{-4}$, and ${\\Gamma}({\\eta}^{\\prime}{\\to}{\\rho}e^{+}e^{-})$ ${\\approx}$ $10{\\Gamma}({\\eta}^{\\prime}{\\to}{\\omega}e^{+}e^{-})$ and ${\\cal B}({\\eta}^{\\prime}{\\to}{\\rho}e^{+}e^{-})$ ${\\approx}$ $10{\\cal B}({\\eta}^{\\prime}{\\to}{\\omega}e^{+}e^{-})$. The maximum position of the dilepton distribution is $m_{e^{+}e^{-}}$ ${\\approx}$ $1.33$ MeV. These decays are measurable with the advent of high statistics ${\\eta}^{\\prime}$ experiments.
Electroweak symmetry breaking and collider signatures in the next-to-minimal composite Higgs model
Niehoff, Christoph; Straub, David M
2016-01-01
We conduct a detailed numerical analysis of the composite pseudo-Nambu-Goldstone Higgs model based on the next-to-minimal coset $\\text{SO}(6)/\\text{SO}(5)\\cong\\text{SU}(4)/\\text{Sp}(4)$, featuring an additional SM singlet scalar in the spectrum, which we allow to mix with the Higgs boson. We identify regions in parameter space compatible with all current experimental constraints, including radiative electroweak symmetry breaking, flavour physics, and direct searches at colliders. We find the additional scalar, with a mass predicted to be below a TeV, to be virtually unconstrained by current LHC data, but potentially in reach of run 2 searches. Promising indirect searches include rare semi-leptonic $B$ decays, CP violation in $B_s$ mixing, and the electric dipole moment of the neutron.
Efficiency optimization and symmetry-breaking in a model of ciliary locomotion
Michelin, Sebastien
2010-01-01
A variety of swimming microorganisms, called ciliates, exploit the bending of a large number of small and densely-packed organelles, termed cilia, in order to propel themselves in a viscous fluid. We consider a spherical envelope model for such ciliary locomotion where the dynamics of the individual cilia are replaced by that of a continuous overlaying surface allowed to deform tangentially to itself. Employing a variational approach, we determine numerically the time-periodic deformation of such surface which leads to low-Reynolds locomotion with minimum rate of energy dissipation (maximum efficiency). Employing both Lagrangian and Eulerian points of views, we show that in the optimal swimming stroke, individual cilia display weak asymmetric beating, but that a significant symmetry-breaking occurs at the organism level, with the whole surface deforming in a wave-like fashion reminiscent of metachronal waves of biological cilia. This wave motion is analyzed using a formal modal decomposition, is found to occu...
Stability of string defects in models of non-Abelian symmetry breaking
Thatcher, M J
1999-01-01
In this paper we describe a new type of topological defect, called a homilia string, which is stabilized via interactions with the string network. Using analytical and numerical techniques, we investigate the stability and dynamics of homilia strings, and their implications for cosmology. In SU(N) models of symmetry breaking, monopoles are identified with the intersection of two homilia strings. Due to repulsive forces, the homilia strings seperate, resulting in monopole annihilation. Homilia string loops cannot stabilize as vortons, which circumvents the adverse cosmological consequences of stable loops. In principle, measurments of the cosmic microwave background can distinguish between the smaller fluctuations induced by a homilia string network and those due to primordial cosmic strings.
Model of skyscraper evacuation with the use of space symmetry and fluid dynamic approximation
Sikora, W; Kupczak, A
2011-01-01
The simulation of evacuation of pedestrians from skyscraper is a situation where the symmetry analysis method and equations of fluid dynamics finds to be very useful. When applied, they strongly reduce the number of free parameters used in simulations and in such a way speed up the calculations and make them easier to manage by the programmer and what is even more important, they can give a fresh insight into a problem of evacuation and help with incorporation of "Ambient Intelligent Devices" into future real buildings. We have analyzed various, simplified, cases of evacuation from skyscraper by employing improved "Social Force Model". For each of them we obtained the average force acting on the pedestrian as a function of the evacuation time. The results clearly show that both methods mentioned above, can be successfully implemented in the simulation process and return with satisfactory conclusions.
Numerical analysis of magnetic states mixing in the Heisenberg model with the dihedral symmetry
Directory of Open Access Journals (Sweden)
Jaśniewicz-Pacer K.
2013-01-01
Full Text Available The total spin number S is not a ‘good quantum number for’ the Heisenberg model with singleion anisotropy, so the Hamiltonian eigenstates with diﬀerent S may form linear combinations. Sometimes it is assumed that S can be used as an ‘approximate quantum number’, though some results show that mixing of S-states is important in investigations of magnetic molecules. Some small spin systems with the dihedral symmetry are analyzed to investigate diﬀerent schemes of mixing and its dependence on the anisotropy parameter. The results show various behavior of the magnetic state mixing. The mean (over a state value of total spin is quite stable for the ground state, but in other cases this dependence is nonlinear and sometimes non-monotonic.
Quark Loop Effects on Dressed Gluon Propagator in Framework of Global Color Symmetry Model
Institute of Scientific and Technical Information of China (English)
ZONG Hong-Shi; SUN Wei-Min
2006-01-01
Based on the global color symmetry model (GCM), a method for obtaining the quark loop effects on the dressed gluon propagator in GCM is developed. In the chiral limit, it is found that the dressed gluon propagator containing the quark loop effects in the Nambu-Goldstone and Wigner phases are quite different. In solving the quark self-energy functions in the two different phases and subsequent study of bag constant one should use the above dressed gluon propagator as input. The above approach for obtaining the current quark mass effects on the dressed gluon propagator is quite general and can also be used to calculate the chemical potential dependence of the dressed gluon propagator.
Symmetries, Lagrangians and Conservation Laws of an Easter Island Population Model
Directory of Open Access Journals (Sweden)
M.C. Nucci
2015-09-01
Full Text Available Basener and Ross (2005 proposed a mathematical model that describes the dynamics of growth and sudden decrease in the population of Easter Island. We have applied Lie group analysis to this system and found that it can be integrated by quadrature if the involved parameters satisfy certain relationships. We have also discerned hidden linearity. Moreover, we have determined a Jacobi last multiplier and, consequently, a Lagrangian for the general system and have found other cases independently and dependently on symmetry considerations in order to construct a corresponding variational problem, thus enabling us to find conservation laws by means of Noether’s theorem. A comparison with the qualitative analysis given by Basener and Ross is provided.
Quinto, A. G.; Ferrari, A. F.; Lehum, A. C.
2016-06-01
In this work, we investigate the consequences of the Renormalization Group Equation (RGE) in the determination of the effective superpotential and the study of Dynamical Symmetry Breaking (DSB) in an N = 1 supersymmetric theory including an Abelian Chern-Simons superfield coupled to N scalar superfields in (2 + 1) dimensional spacetime. The classical Lagrangian presents scale invariance, which is broken by radiative corrections to the effective superpotential. We calculate the effective superpotential up to two-loops by using the RGE and the beta functions and anomalous dimensions known in the literature. We then show how the RGE can be used to improve this calculation, by summing up properly defined series of leading logs (LL), next-to-leading logs (NLL) contributions, and so on... We conclude that even if the RGE improvement procedure can indeed be applied in a supersymmetric model, the effects of the consideration of the RGE are not so dramatic as it happens in the non-supersymmetric case.
A Model of Fermion Masses and Flavor Mixings with Family Symmetry $SU(3)\\otimes U(1)$
Yang, Wei-Min; Zhong, Jin-Jin
2011-01-01
The family symmetry $SU(3)\\otimes U(1)$ is proposed to solve flavor problems about fermion masses and flavor mixings. It's breaking is implemented by some flavon fields at the high-energy scale. In addition a discrete group $Z_{2}$ is introduced to generate tiny neutrino masses, which is broken by a real singlet scalar field at the middle-energy scale. The low-energy effective theory is elegantly obtained after all of super-heavy fermions are integrated out and decoupling. All the fermion mass matrices are regularly characterized by four fundamental matrices and thirteen parameters. The model can perfectly fit and account for all the current experimental data about the fermion masses and flavor mixings, in particular, it finely predicts the first generation quark masses and the values of $\\theta^{\\,l}_{13}$ and $J_{CP}^{\\,l}$ in neutrino physics. All of the results are promising to be tested in the future experiments.
Convolution symmetries of integrable hierarchies, matrix models and $\\tau$-functions
Harnad, J
2009-01-01
Generalized convolution symmetries of integrable hierarchies of KP-Toda and 2KP-Toda type have the effect of multiplying the Fourier coefficients of the Baker-Akhiezer function by a specified sequence of constants. The induced action on the associated fermionic Fock space is diagonal in the standard orthonormal base determined by occupation sites and labeled by partitions. The coefficients in the single and double Schur function expansions of the associated $\\tau$-functions, which are the Pl\\"ucker coordinates of a decomposable element, are multiplied by the corresponding diagonal factors. Applying such transformations to matrix integrals, we obtain new matrix models of externally coupled type which are also KP-Toda or 2KP-Toda $\\tau$-functions. More general multiple integral representations of tau functions are similarly obtained, as well as finite determinantal expressions for them.
A new symmetry model for hohlraum-driven capsule implosion experiments on the NIF
Jones, O.; Rygg, R.; Tomasini, R.; Eder, D.; Kritcher, A.; Milovich, J.; Peterson, L.; Thomas, C.; Barrios, M.; Benedetti, R.; Doeppner, T.; Ma, T.; Nagel, S.; Pak, A.; Field, J.; Izumi, N.; Glenn, S.; Town, R.; Bradley, D.
2016-03-01
We have developed a new model for predicting the time-dependent radiation drive asymmetry in laser-heated hohlraums. The model consists of integrated Hydra capsule-hohlraum calculations coupled to a separate model for calculating the crossbeam energy transfer between the inner and outer cones of the National Ignition Facility (NIF) indirect drive configuration. The time- dependent crossbeam transfer model parameters were adjusted in order to best match the P2 component of the shape of the inflight shell inferred from backlit radiographs of the capsule taken when the shell was at a radius of 150-250 μm. The adjusted model correctly predicts the observed inflight P2 and P4 components of the shape of the inflight shell, and also the P2 component of the shape of the hotspot inferred from x-ray self-emission images at the time of peak emission. It also correctly captures the scaling of the inflight P4 as the hohlraum length is varied. We then applied the newly benchmarked model to quantify the improved symmetry of the N130331 layered deuterium- tritium (DT) experiment in a re-optimized longer hohlraum.
Jimbo, Michio
2013-03-01
Since the beginning of 1980s, hidden infinite dimensional symmetries have emerged as the origin of integrability: first in soliton theory and then in conformal field theory. Quest for symmetries in quantum integrable models has led to the discovery of quantum groups. On one hand this opened up rapid mathematical developments in representation theory, combinatorics and other fields. On the other hand it has advanced understanding of correlation functions of lattice models, leading to multiple integral formulas in integrable spin chains. We shall review these developments which continue up to the present time.
Progress towards a more predictive model for hohlraum radiation drive and symmetry
Jones, Ogden
2016-10-01
The high flux model (HFM) was first developed to match emission levels observed from Au spheres illuminated symmetrically at the UR-LLE OMEGA laser. It utilizes a modern non-LTE atomic physics model and an electron thermal flux limiter of 0.15 or a non-local electron transport model. Shortly thereafter, the HFM was also found to better match the radiation drive observed through the laser entrance hole of laser-heated vacuum hohlraums on the NIF. Subsequent capsule implosion experiments driven by hohlraums filled with 1-1.6 mg/cc of He, having case-to-capsule ratios of 2.6, and pulse lengths 15-20 ns have been characterized by relatively large amounts of laser backscatter losses (up to 18% of the input laser energy). They have also utilized cross beam energy transfer (CBET) to transfer power to the lasers depositing energy near the hohlraum waist. When the HFM is applied to these experiments, the hohlraum x-ray drive is over-predicted by 20-30% during peak laser power, and the drive symmetry cannot be matched without making ad hoc corrections. More recent experiments using hohlraum fills from 0-0.6 mg/cc He, case-to-capsule ratios 3-4, and pulse lengths 6-10 ns have little or no CBET or backscatter and are in better agreement with calculations using the HFM, although discrepancies remain. Uncertainties remaining in the computational models of emissivity, laser absorption, heat transport, etc. used in our hydrodynamic codes can significantly affect predictions. In this work we test various physically-plausible adjustments or alternatives to these models in order to find a more predictive model for radiation drive in the regime with little or no backscatter or CBET. We utilize measurements of the radiation drive, shape and trajectory of the imploding shell, shape of the stagnated hot spot, and bang time in capsule implosions and spectroscopic measurements of the hohlraum plasma conditions to compare against high resolution hydrodynamic calculations using the various
Symmetry foundations of a polymer model for close-packed metallic liquids and glasses
Kraposhin, V. S.; Talis, A. L.
2016-02-01
The atomic packing density of metallic melts and glasses is too high for their structures to be considered as chaotic. To remove this contradiction, we propose to describe the structures of metallic liquids and the glasses that form from them using (i) a base set of three spirals made of regular tetrahedra with specific noncrystallographic symmetry and (ii) combinatorial permutations of the vertices of a set of the coordination polyhedra that describe the polymorphic transformations in metals. The symmetry base of the proposed model of the structures of liquids and glasses is represented by projective linear groups PSL(2, p), where the order of the Galois field is p = 3, 7, and 11. These groups uniquely determine a tetrahedron, the 7-vertex joining of four tetrahedra along their faces (tetrablock), the 11-vertex joining of two tetrablocks into a spiral, and the throwing over of the diagonals in a rhombus from two triangular faces of neighboring tetrahedra. The throwing over of the diagonals in a rhombus is considered as a unit act of any structural transformation and ensures the melt-crystal, melt-glass, and glass-crystal transitions and the structural relaxation of metallic glasses. In terms of the proposed scheme, the high density of melts and glasses is caused by tetrahedral packing (up to 78%), and the absence of a diffraction pattern of melts and glasses is explained by the absence of translation along the spiral axis. The suggested polymer model also explains the collective effects (string vibrations) that were detected upon measuring the shear modulus relaxation of a metallic glass.
Zhang, Sun
2015-01-01
In this paper, based on the works of Capozziello et al., we have studied the Noether symmetry approach in the cosmological model with scalar and gauge fields proposed recently by Soda et al. The correct Noether symmetries and related Lie algebra are given according to the minisuperspace quantum cosmological model. The Wheeler-De Witt (WDW) equation is presented after quantization and the classical trajectories are then obtained in the semi-classical limit. The oscillating features of the wave function in the cosmic evolution recover the so-called Hartle criterion, and the selection rule in minisuperspace quantum cosmology is strengthened. Then we have realized now the proposition that Noether symmetries select classical universes.
Absence of the Fifth Force Problem in a Model with Spontaneously Broken Dilatation Symmetry
Guendelman, E I
2007-01-01
A scale invariant model containing dilaton $\\phi$ and dust (as a model of matter) is studied where the shift symmetry $\\phi\\to\\phi +const.$ is spontaneously broken at the classical level due to intrinsic features of the model. The dilaton to matter coupling "constant" $f$ appears to be dependent of the matter density. In normal conditions, i.e. when the matter energy density is many orders of magnitude larger than the dilaton contribution to the dark energy density, $f$ becomes less than the ratio of the "mass of the vacuum" in the volume occupied by the matter to the Planck mass. The model yields this kind of "Archimedes law" without any especial (intended for this) choice of the underlying action and without fine tuning of the parameters. The model not only explains why all attempts to discover a scalar force correction to Newtonian gravity were unsuccessful so far but also predicts that in the near future there is no chance to detect such corrections in the astronomical measurements as well as in the speci...
Symmetry-respecting real-space renormalization for the quantum Ashkin-Teller model.
O'Brien, Aroon; Bartlett, Stephen D; Doherty, Andrew C; Flammia, Steven T
2015-10-01
We use a simple real-space renormalization-group approach to investigate the critical behavior of the quantum Ashkin-Teller model, a one-dimensional quantum spin chain possessing a line of criticality along which critical exponents vary continuously. This approach, which is based on exploiting the on-site symmetry of the model, has been shown to be surprisingly accurate for predicting some aspects of the critical behavior of the quantum transverse-field Ising model. Our investigation explores this approach in more generality, in a model in which the critical behavior has a richer structure but which reduces to the simpler Ising case at a special point. We demonstrate that the correlation length critical exponent as predicted from this real-space renormalization-group approach is in broad agreement with the corresponding results from conformal field theory along the line of criticality. Near the Ising special point, the error in the estimated critical exponent from this simple method is comparable to that of numerically intensive simulations based on much more sophisticated methods, although the accuracy decreases away from the decoupled Ising model point.
Institute of Scientific and Technical Information of China (English)
ZHOU Bang-Rong
2004-01-01
By means of critical behaviors of the dynamical fermion mass in four-fermion interaction models, we show by explicit calculations that when T ＝ 0 the particle density will have a discontinuous jumping across the critical chemical potential μc in 2D and 3D Gross-Neveu (GN) model and these physically explain the first-order feature of the corresponding symmetry restoring phase transitions. For the second-order phase transitions in the 3D GN model when T → 0 and in 4D Nambu-Jona-Lasinio (NJL) model when T ＝ 0, it is proven that the particle density itself will be continuous across μc but its derivative over the chemical potential μ will have a discontinuous jumping. The results give a physical explanation of implications of the tricritical point (T, μ) = (0,μc) in the 3D GN model. The discussions also show effectiveness of the critical analysis approach of phase transitions.
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)
Sourrouille, Lucas
2015-11-01
We consider a generalization of non-relativistic Schrödinger-Higgs Lagrangian by introducing a nonstandard kinetic term. We show that this model is Galilean invariant, we construct the conserved charges associated to the symmetries and realize the algebra of the Galilean group. In addition, we study the model in the presence of a gauge field. We also show that the gauged model is Galilean invariant. Finally, we explore relations between the twin models and their solutions.
The role of conformal symmetry in gravity and the standard model
Lucat, Stefano; Prokopec, Tomislav
2016-01-01
In this paper we consider conformal symmetry in the context of manifolds with general affine connection. We extend the conformal transformation law of the metric to a general metric compatible affine connection, and find that it is a symmetry of both the geodesic equation and the Riemann tensor. We
DEFF Research Database (Denmark)
Hagedorn, C.
2014-01-01
be detected by future experiments, thanks to the presence of a flavour symmetry Gf which constrains the form of the relevant couplings. The symmetry Gf is chosen to be finite, discrete and non-abelian and also helps to predict the peculiar lepton mixing pattern. © 2014 Elsevier B.V....
Vacuum Stability and Radiative Electroweak Symmetry Breaking in an SO(10) Dark Matter Model
Mambrini, Yann; Olive, Keith A; Zheng, Jiaming
2016-01-01
Vacuum stability in the Standard Model is problematic as the Higgs quartic self-coupling runs negative at a renormalization scale of about $10^{10}$ GeV. We consider a non-supersymmetric SO(10) grand unification model for which gauge coupling unification is made possible through an intermediate scale gauge group, $G_{\\rm int}=\\text{SU}(3)_C\\otimes \\text{SU}(2)_L\\otimes \\text{SU}(2)_R \\otimes \\text{U}(1)_{B-L}$. $G_{\\rm int}$ is broken by the vacuum expectation value of a 126 of SO(10) which not only provides for neutrino masses through the see-saw mechanism, but also preserves a discrete $\\mathbb{Z}_2$ that can account for the stability of a dark matter candidate, here taken to be the Standard Model singlet component of a bosonic 16. We show that in addition to these features, the model insures the positivity of the Higgs quartic coupling through its interactions to the dark matter multiplet and 126. We also show that the Higgs mass-squared runs negative triggering electroweak symmetry breaking. Thus the vacu...
Twisted Spectral Triple for the Standard Model and Spontaneous Breaking of the Grand Symmetry
Energy Technology Data Exchange (ETDEWEB)
Devastato, Agostino, E-mail: agostino.devastato@na.infn.it; Martinetti, Pierre, E-mail: martinetti@dima.unige.it [Università di Napoli Federico II, Dipartimento di Fisica (Italy)
2017-03-15
Grand symmetry models in noncommutative geometry, characterized by a non-trivial action of functions on spinors, have been introduced to generate minimally (i.e. without adding new fermions) and in agreement with the first order condition an extra scalar field beyond the standard model, which both stabilizes the electroweak vacuum and makes the computation of the mass of the Higgs compatible with its experimental value. In this paper, we use a twist in the sense of Connes-Moscovici to cure a technical problem due to the non-trivial action on spinors, that is the appearance together with the extra scalar field of unbounded vectorial terms. The twist makes these terms bounded and - thanks to a twisted version of the first-order condition that we introduce here - also permits to understand the breaking to the standard model as a dynamical process induced by the spectral action, as conjectured in [24]. This is a spontaneous breaking from a pre-geometric Pati-Salam model to the almost-commutativegeometryofthestandardmodel,withtwoHiggs-likefields: scalar and vector.
Twisted Spectral Triple for the Standard Model and Spontaneous Breaking of the Grand Symmetry
Devastato, Agostino; Martinetti, Pierre
2017-03-01
Grand symmetry models in noncommutative geometry, characterized by a non-trivial action of functions on spinors, have been introduced to generate minimally (i.e. without adding new fermions) and in agreement with the first order condition an extra scalar field beyond the standard model, which both stabilizes the electroweak vacuum and makes the computation of the mass of the Higgs compatible with its experimental value. In this paper, we use a twist in the sense of Connes-Moscovici to cure a technical problem due to the non-trivial action on spinors, that is the appearance together with the extra scalar field of unbounded vectorial terms. The twist makes these terms bounded and - thanks to a twisted version of the first-order condition that we introduce here - also permits to understand the breaking to the standard model as a dynamical process induced by the spectral action, as conjectured in [24]. This is a spontaneous breaking from a pre-geometric Pati-Salam model to the almost-commutativegeometryofthestandardmodel,withtwoHiggs-likefields: scalar and vector.
Energy Technology Data Exchange (ETDEWEB)
Del Cima, Oswaldo M.; Franco, Daniel H.T.; Piguet, Olivier, E-mail: opiguet@pq.cnpq.br
2016-11-15
In this paper, we revisit the issue intensively studied in recent years on the generation of terms by radiative corrections in models with broken Lorentz symmetry. The algebraic perturbative method of handling the problem of renormalization of the theories with Lorentz symmetry breaking, is used. We hope to make clear the Symanzik's aphorism: “Whether you like it or not, you have to include in the lagrangian all counter terms consistent with locality and power-counting, unless otherwise constrained by Ward identities.”{sup 1}.
Directory of Open Access Journals (Sweden)
Oswaldo M. Del Cima
2016-11-01
Full Text Available In this paper, we revisit the issue intensively studied in recent years on the generation of terms by radiative corrections in models with broken Lorentz symmetry. The algebraic perturbative method of handling the problem of renormalization of the theories with Lorentz symmetry breaking, is used. We hope to make clear the Symanzik's aphorism: “Whether you like it or not, you have to include in the lagrangian all counter terms consistent with locality and power-counting, unless otherwise constrained by Ward identities.”1
Are bilinear quadrilaterals better than linear triangles?
Energy Technology Data Exchange (ETDEWEB)
D`Azevedo, E.F.
1993-08-01
This paper compares the theoretical effectiveness of bilinear approximation over quadrilaterals with linear approximation over triangles. Anisotropic mesh transformation is used to generate asymptotically optimally efficient meshes for piecewise linear interpolation over triangles and bilinear interpolation over quadrilaterals. The theory and numerical results suggest triangles may have a slight advantage over quadrilaterals for interpolating convex data function but bilinear approximation may offer a higher order approximation for saddle-shaped functions on a well-designed mesh. This work is a basic study on optimal meshes with the intention of gaining insight into the more complex meshing problems in finite element analysis.
Are Bilinear Quadrilaterals Better Than Linear Triangles?
Energy Technology Data Exchange (ETDEWEB)
D' Azevedo, E.F.
1993-01-01
This paper compares the theoretical effectiveness of bilinear approximation over quadrilaterals with linear approximation over triangles. Anisotropic mesh transformation is used to generate asymptotically optimally efficient meshes for piecewise linear interpolation over triangles and bilinear interpolation over quadrilaterals. For approximating a convex function, although bilinear quadrilaterals are more efficient, linear triangles are more accurate and may be preferred in finite element computations; whereas for saddle-shaped functions, quadrilaterals may offer a higher order approximation on a well-designed mesh. A surprising finding is different grid orientations may yield an order of magnitude improvement in approximation accuracy.
Bilateral Petit’s Triangle Hernia
Directory of Open Access Journals (Sweden)
Sanjay Kumar Bhasin, Arshad Bashir Khan, Sanjay Sharma
2006-07-01
Full Text Available Lumbar traingle hernia that occurs through lumbar triangles is very rare type of hernia. Only about 300 cases havebeen reported till date. Bilateral Petit’s triangle hernia find further rarity and the case under reference is probably thefirst ever reported case of Primary bilateral Petit’s triangle hernia. The present case is of a 46 years old married,multigravida female who presented with 1 year duration of LBA and subsequently notice of swelling both sides oflow back. FNAC revealed lipoma and on exploration it turned out to be rarest extra peritoneal bilateral Petit’s trianglehernia, fat as contents.
Kappa-symmetry of superstring sigma model and generalized 10d supergravity equations
Energy Technology Data Exchange (ETDEWEB)
Tseytlin, A.A.; Wulff, L. [Blackett Laboratory, Imperial College,London SW7 2AZ (United Kingdom)
2016-06-29
We determine the constraints imposed on the 10d target superspace geometry by the requirement of classical kappa-symmetry of the Green-Schwarz superstring. In the type I case we find that the background must satisfy a generalization of type I supergravity equations. These equations depend on an arbitrary vector X{sub a} and imply the one-loop scale invariance of the GS sigma model. In the special case when X{sub a} is the gradient of a scalar ϕ (dilaton) one recovers the standard type I equations equivalent to the 2d Weyl invariance conditions of the superstring sigma model. In the type II case we find a generalized version of the 10d supergravity equations the bosonic part of which was introduced in http://arxiv.org/abs/1511.05795. These equations depend on two vectors X{sub a} and K{sub a} subject to 1st order differential relations (with the equations in the NS-NS sector depending only on the combination X{sub a}=X{sub a}+K{sub a}). In the special case of K{sub a}=0 one finds that X{sub a}=∂{sub a}ϕ and thus obtains the standard type II supergravity equations. New generalized solutions are found if K{sub a} is chosen to be a Killing vector (and thus they exist only if the metric admits an isometry). Non-trivial solutions of the generalized equations describe K-isometric backgrounds that can be mapped by T-duality to type II supergravity solutions with dilaton containing a linear isometry-breaking term. Examples of such backgrounds appeared recently in the context of integrable η-deformations of AdS{sub n}×S{sup n} sigma models. The classical kappa-symmetry thus does not, in general, imply the 2d Weyl invariance conditions for the GS sigma model (equivalent to type II supergravity equations) but only weaker scale invariance type conditions.
LHC constraints on large scalar multiplet models with a $Z_2$ symmetry
Logan, Heather E; Pilkington, Terry
2015-01-01
We study the LHC search constraints on models that extend the Standard Model (SM) with an inert, complex scalar electroweak multiplet, $\\Sigma$, with isospin T=5/2 (sextet) or T=7/2 (octet) and identical hypercharge to the SM Higgs doublet. Imposing a global $Z_2$ symmetry under which $\\Sigma \\to -\\Sigma$, the lightest member of $\\Sigma$ is stable and we require that it be neutral ($\\zeta^{0,r}$) to avoid cosmological constraints from charged relics. Pair production of scalars by electroweak interactions followed by cascade decays to $\\zeta^{0,r}$ through W and Z emission produces signatures similar to those of supersymmetric electroweak gauginos, and we constrain the models by recasting a collection of such searches made with data from the 8 TeV run of the LHC. We find that there is no sensitivity from these searches to the compressed spectrum regime, in which the mass splittings between the lightest and heaviest states in $\\Sigma$ are less than about 20 GeV. In the remaining parameter space, we find signifi...
Affine q-deformed symmetry and the classical Yang-Baxter σ-model
Delduc, F.; Kameyama, T.; Magro, M.; Vicedo, B.
2017-03-01
The Yang-Baxter σ-model is an integrable deformation of the principal chiral model on a Lie group G. The deformation breaks the G × G symmetry to U(1)rank( G) × G. It is known that there exist non-local conserved charges which, together with the unbroken U(1)rank( G) local charges, form a Poisson algebra [InlineMediaObject not available: see fulltext.], which is the semiclassical limit of the quantum group {U}_q(g) , with g the Lie algebra of G. For a general Lie group G with rank( G) > 1, we extend the previous result by constructing local and non-local conserved charges satisfying all the defining relations of the infinite-dimensional Poisson algebra [InlineMediaObject not available: see fulltext.], the classical analogue of the quantum loop algebra {U}_q(Lg) , where Lg is the loop algebra of g. Quite unexpectedly, these defining relations are proved without encountering any ambiguity related to the non-ultralocality of this integrable σ-model.
Nonequilibrium evolution in scalar O(N) models with spontaneous symmetry breaking
Baacke, J
2002-01-01
We consider the out-of-equilibrium evolution of a classical condensate field and its quantum fluctuations for a scalar O(N) model with spontaneously broken symmetry. In contrast to previous studies we do not consider the large $N$ limit, but the case of finite $N$, including N=1, i.e., plain $\\lambda \\phi^ 4$ theory. The instabilities encountered in the one-loop approximation are prevented, as in the large-N limit, by back reaction of the fluctuations on themselves, or, equivalently, by including a resummation of bubble diagrams. For this resummation and its renormalization we use formulations developed recently based on the effective action formalism of Cornwall, Jackiw and Tomboulis. The formulation of renormalized equations for finite $N$ derived here represents a useful tool for simulations with realistic models. Here we concentrate on the phase structure of such models. We observe the transition between the spontaneously broken and the symmetric phase at low and high energy densities, respectively. This ...
Spontaneous symmetry breaking in nonlinear systems: An overview and a simple model
Malomed, Boris A
2015-01-01
The paper combines two topics belonging to the general theme of the spontaneous symmetry breaking (SSB) in systems including two basic competing ingredients: the self-focusing cubic nonlinearity and a double-well-potential (DWP) structure. Such systems find diverse physical realizations, chiefly in optical waveguides, made of a nonlinear material and featuring a transverse DWP structure, and in models of atomic BEC with attractive inter-atomic interactions, loaded into a pair of symmetric potential wells coupled by tunneling across the separating barrier. With the increase of the nonlinearity strength, the SSB occurs at a critical value of the strength. The first part of the paper offers a brief overview of the topic. The second part presents a model which is designed as the simplest one capable to produce the SSB phenomenology in the one-dimensional geometry. The model is based on the DWP built as an infinitely deep potential box, which is split into two wells by a delta-functional barrier at the central poi...
Lepton Masses in a Minimal Model with Triplet Higgs and $S_3\\times Z_4$ Flavor Symmetry
Mitra, Manimala
2008-01-01
Viable neutrino and charged lepton masses and mixings are obtained by imposing the $S_3 \\times Z_4$ flavor symmetry in a model with a few additional Higgs and no extra fermions. We use $SU(2)_L$ triplet Higgs which are arranged as a doublet of $S_3$, and standard model singlet Higgs which are also put as doublets of $S_3$. We break the $S_3$ symmetry in this minimal model by giving vacuum expectation values (VEV) to the additional Higgs fields. Dictated by the minimum condition for the scalar potential, we obtain certain VEV alignments which allow us to maintain exact $\\mu-\\tau$ symmetry in the neutrino sector, while breaking it maximally for the charged leptons. This helps us to simultaneously explain the hierarchical charged lepton masses, and the neutrino masses and mixings. In particular, we obtain maximal $\\theta_{23}$ and zero $\\theta_{13}$. We allow for a mild breaking of the $\\mu-\\tau$ symmetry for the neutrinos and study the phenomenology. We give predictions for $\\theta_{13}$ and the CP violating Ja...
Nova symmetry: Experiments, modeling, and interpretation (HLP3 and HLP4)
Energy Technology Data Exchange (ETDEWEB)
Suter, L.J.; Hauer, A.A. [Los Alamos National Lab., NM (United States); Powers, L.V.
1996-06-01
Understanding and controlling capsule implosion symmetry is a key requirement for inertial confinement fusion (ICF). Symmetry was specifically called out in the Nova Technical Contract (NTC) as the HLP4 task. Later, elements of HLP3 were expanded to include symmetry work. For nearly a decade and a half it has been recognized that the fundamental asymmetry in a laser-heated hohlraum is a long-wavelength pole-waist radiation flux variation that varies like the P{sub 2} Legendre polynomial. It has also been recognized that one can control this asymmetry and achieve nearly symmetric implosions by appropriately pointing the laser beams.
Inequivalent Quantizations of the N = 3 Calogero model with Scale and Mirror-S_3 Symmetry
Yonezawa, N; Tsutsui, Izumi; Yonezawa, Nobuhiro
2006-01-01
We study the inequivalent quantizations of the N = 3 Calogero model by separation of variables, in which the model decomposes into the angular and the radial parts. Our inequivalent quantizations respect the ` mirror-S_3\\rq\\ invariance (which realizes the symmetry under the cyclic permutations of the particles) and the scale invariance in the limit of vanishing harmonic potential. We find a two-parameter family of novel quantizations in the angular part and classify the eigenstates in terms of the irreducible representations of the S_3 group. The scale invariance restricts the quantization in the radial part uniquely, except for the eigenstates coupled to the lowest two angular levels for which two types of boundary conditions are allowed independently from all upper levels. It is also found that the eigenvalues corresponding to the singlet representations of the S_3 are universal (parameter-independent) in the family, whereas those corresponding to the doublets of the S_3 are dependent on one of the paramete...
Kappa-symmetry of superstring sigma model and generalized 10d supergravity equations
Wulff, L
2016-01-01
We determine the constraints imposed on the 10d target superspace geometry by the requirement of classical kappa-symmetry of the Green-Schwarz superstring. In the type I case we find that the background must satisfy a generalization of type I supergravity equations. These equations depend on an arbitrary vector X_a and imply the one-loop scale invariance of the GS sigma model. In the special case when X_a is the gradient of a scalar \\phi (dilaton) one recovers the standard type I equations equivalent to the 2d Weyl invariance conditions of the superstring sigma model. In the type II case we find a generalized version of the 10d supergravity equations the bosonic part of which was introduced in arXiv:1511.05795. These equations depend on two vectors \\X_a and K_a subject to 1st order differential relations (with the equations in the NS-NS sector depending only on the combination X_a = \\X_a + K_a). In the special case of K_a=0 one finds that \\X_a=\\d_a \\phi and thus obtains the standard type II supergravity equat...
A neutrino mass model with S3 symmetry and see-saw interplay
Pramanick, Soumita
2016-01-01
We develop a see-saw model for neutrino masses and mixing with an S3\\times Z3 symmetry. It involves an interplay of Type-I and Type-II see-saw contributions of which the former is subdominant. The S3 \\times Z3 quantum numbers of the fermion and scalar fields are chosen such that the Type-II see-saw generates a mass matrix which incorporates the atmospheric mass splitting and sets \\theta_{23} = \\pi/4. The solar splitting and \\theta_{13} are absent, while the third mixing angle can achieve any value, \\theta_{12}^0. Specific choices of \\theta_{12}^0 are of interest, e.g., 35.3^\\circ (tribimaximal), 45.0^\\circ (bimaximal), 31.7^\\circ (golden ratio), and 0^\\circ (no solar mixing). The role of the Type-I see-saw is to nudge all quantities into the range indicated by the data. The model results in novel interrelationships between these quantities due to their common origin, making it readily falsifiable. For example, normal (inverted) ordering is associated with \\theta_{23} in the first (second) octant. CP-violation...
Inference in Graphical Gaussian Models with Edge and Vertex Symmetries with the gRc Package for R
DEFF Research Database (Denmark)
Højsgaard, Søren; Lauritzen, Steffen L
2007-01-01
In this paper we present the R package gRc for statistical inference in graphical Gaussian models in which symmetry restrictions have been imposed on the concentration or partial correlation matrix. The models are represented by coloured graphs where parameters associated with edges or vertices o...... of same colour are restricted to being identical. We describe algorithms for maximum likelihood estimation and discuss model selection issues. The paper illustrates the practical use of the gRc package......In this paper we present the R package gRc for statistical inference in graphical Gaussian models in which symmetry restrictions have been imposed on the concentration or partial correlation matrix. The models are represented by coloured graphs where parameters associated with edges or vertices...
Density conditions for triangles in multipartite graphs
DEFF Research Database (Denmark)
Bondy, Adrian; Shen, Jin; Thomassé, Stephan
2006-01-01
subgraphs in G. We investigate in particular the case where G is a complete multipartite graph. We prove that a finite tripartite graph with all edge densities greater than the golden ratio has a triangle and that this bound is best possible. Also we show that an infinite-partite graph with finite parts has...... a triangle, provided that the edge density between any two parts is greater than 1/2....
Energy Technology Data Exchange (ETDEWEB)
El Naschie, M.S. [King Abdul Aziz City of Science and Technology, Riyadh (Saudi Arabia)
2007-04-15
The notion of a particle-like state emerging from a symmetry breaking is given five corresponding pictures. We start from a geometrical picture in two dimensions involving a modular curve constructed using 336 triangles. The same number of building blocks is found again, this time as 336 contact points in the ten dimensional space of super string theory in the context of the largest kissing number of lattice sphere packing. The next corresponding representation is an abstract one pertinent to the order of the simple linear Lie group SL(2, n) in seven dimensions (n = 7) which leads to 336 symmetries. Subsequently a tensorial picture is given using the Riemannian tensor of relativity theory but this time in an eight dimensional space (n = 8) for which the number of independent components is again 336. Finally we use a physical string theory related picture in the 12 dimensions of F theory to find 336 moduli space dimensions representing the instanton cells of our theory. It is evident that the five preceding pictures are ten fold interconnected and exchangeable. This additional mental freedom does not only enhance the feeling of understanding, but also facilitates the easy recognition of complex mathematical relations and its connection to the physical concepts.
Applied psychometrics in clinical psychiatry: the pharmacopsychometric triangle
DEFF Research Database (Denmark)
Bech, P
2009-01-01
OBJECTIVE: To consider applied psychometrics in psychiatry as a discipline focusing on pharmacopsychology rather than psychopharmacology as illustrated by the pharmacopsychometric triangle. METHOD: The pharmacopsychological dimensions of clinically valid effects of drugs (antianxiety, antidepress......OBJECTIVE: To consider applied psychometrics in psychiatry as a discipline focusing on pharmacopsychology rather than psychopharmacology as illustrated by the pharmacopsychometric triangle. METHOD: The pharmacopsychological dimensions of clinically valid effects of drugs (antianxiety......, antidepressive, antimanic, and antipsychotic), of clinically unwanted effects of these drugs, and the patients' own subjective perception of the balance between wanted and unwanted effects are analysed using rating scales assessed by modern psychometric tests (item response theory models) RESULTS: Symptom rating...... scales fulfilling the item response theory models have been shown to be psychometrically valid outcome scales as their total scores are sufficient statistics for demonstrating dose-response relationship within the various classes of antianxiety, antidepressive, antimanic or antipsychotic drugs. The total...
Nuclear matter fourth-order symmetry energy in relativistic mean field models
Cai, Bao-Jun
2011-01-01
Within the nonlinear relativistic mean field model, we derive the analytical expression of the nuclear matter fourth-order symmetry energy $E_{4}(\\rho)$. Our results show that the value of $E_{4}(\\rho)$ at normal nuclear matter density $\\rho_{0}$ is generally less than 1 MeV, confirming the empirical parabolic approximation to the equation of state for asymmetric nuclear matter at $\\rho_{0}$. On the other hand, we find that the $E_{4}(\\rho)$ may become nonnegligible at high densities. Furthermore, the analytical form of the $E_{4}(\\rho)$ provides the possibility to study the higher-order effects on the isobaric incompressibility of asymmetric nuclear matter, i.e., $K_{\\mathrm{sat}}(\\delta)=K_{0}+K_{\\mathrm{{sat},2}}\\delta ^{2}+K_{\\mathrm{{sat},4}}\\delta ^{4}+\\mathcal{O}(\\delta ^{6})$ where $\\delta =(\\rho_{n}-\\rho_{p})/\\rho $ is the isospin asymmetry, and we find that the value of $K_{\\mathrm{{sat},4}}$ is generally comparable with that of the $K_{\\mathrm{{sat},2}}$. In addition, we study the effects of the $E...
On the stability of multi-scale models of dynamical symmetry breaking from holography
Faedo, Anton F; Schofield, Daniel
2013-01-01
We consider two classes of backgrounds of Type IIB supergravity obtained by wrapping D5-branes on a two-cycle inside the conifold. The field theory dual exhibits confinement and, in addition, a region in which the dynamics is walking, at least in the weak sense that the running of the coupling is anomalously slow. We introduce quenched matter in the fundamental, modelled by probe D7-branes which wrap an internal three-dimensional manifold and lie at the equator of the transverse two-sphere. In the space spanned by the remaining internal angle and the radial coordinate the branes admit two embeddings. The first one is U-shaped: the branes merge at some finite value of the radius. The second one is disconnected and extends along the entire radial direction at fixed angular separation. We interpret these two configurations as corresponding to chiral-symmetry breaking and preserving phases, respectively. We present a simple diagnostic tool to examine the classical stability of the embedding, based on the concavit...
Monte-Carlo event generation for a two-Higgs-doublet model with maximal CP symmetry
Brehmer, Johann
2012-01-01
Recently a two-Higgs-doublet model with maximal symmetry under generalised CP transformations, the MCPM, has been proposed. The theory features a unique fermion mass spectrum which, although not describing nature precisely, provides a good approximation. It also predicts the existence of five Higgs bosons with a particular signature. In this thesis I implemented the MCPM into the Monte-Carlo event generation package MadGraph, allowing the simulation of any MCPM tree-level process. The generated events are in a standardised format and can be used for further analysis with tools such as PYTHIA or GEANT, eventually leading to the comparison with experimental data and the exclusion or discovery of the theory. The implementation was successfully validated in different ways. It was then used for a first comparison of the MCPM signal events with the SM background and previous searches for new physics, hinting that the data expected at the LHC in the next years might provide exclusion limits or show signatures of thi...
The T7 flavor symmetry in 3-3-1 model with neutral leptons
Vien, V V
2014-01-01
We construct a 3-3-1 model based on non-Abelian discrete symmetry $T_7$ responsible for the fermion masses. Neutrinos get masses from only anti-sextets which are in triplets $\\underline{3}$ and $\\underline{3}^*$ under $T_7$. The flavor mixing patterns and mass splitting are obtained without perturbation. The tribimaximal form obtained with the breaking $T_7 \\rightarrow Z_3$ in charged lepton sector and both $T_7 \\rightarrow Z_3$ and $Z_3 \\rightarrow \\{\\mathrm{Identity}\\}$ must be taken place in neutrino sector but only apart in breakings $Z_3 \\rightarrow \\{\\mathrm{Identity}\\}$ (without contribution of $\\si'$), and the upper bound on neutrino mass $\\sum_{i=1}^3m_i$ at the level is presented. The Dirac CP violation phase $\\delta$ is predicted to either $\\frac{\\pi}{2}$ or $\\frac{3\\pi}{2}$ which is maximal CP violation. From the Dirac CP violation phase we obtain the relation between Euler's angles which is consistent with the experimental in PDG 2012. On the other hand, the realistic lepton mixing can be obtaine...
Meyer, R. A.; Scholten, O.; Brant, S.; Paar, V.
1990-01-01
We have investigated the structure of 144Nd84 within the framework of the cluster vibration model. Further, we have mapped, approximately, the cluster vibration model states into the proton-neutron interacting-boson model, with particular emphasis on the mixed-symmetry states, hindered transitions,
Harter, Andrew K.; Lee, Tony E.; Joglekar, Yogesh N.
2016-06-01
Aubry-André-Harper lattice models, characterized by a reflection-asymmetric sinusoidally varying nearest-neighbor tunneling profile, are well known for their topological properties. We consider the fate of such models in the presence of balanced gain and loss potentials ±i γ located at reflection-symmetric sites. We predict that these models have a finite PT -breaking threshold only for specific locations of the gain-loss potential and uncover a hidden symmetry that is instrumental to the finite threshold strength. We also show that the topological edge states remain robust in the PT -symmetry-broken phase. Our predictions substantially broaden the possible experimental realizations of a PT -symmetric system.
Lepton mass and mixing in a simple extension of the Standard Model based on T7 flavor symmetry
Vien, V V
2016-01-01
A simple Standard Model Extension based on $T_7$ flavor symmetry which accommodates lepton mass and mixing with non-zero $\\theta_{13}$ and CP violation phase is proposed. At the tree- level, the realistic lepton mass and mixing pattern is derived through the spontaneous symmetry breaking by just one vacuum expectation value ($v$) which is the same as in the Standard Model. Neutrinos get small masses from one $SU(2)_L$ doublet and two $SU(2)_L$ singlets in which one being in $\\underline{1}$ and the two others in $\\underline{3}$ and $\\underline{3}^*$ under $T_7$ , respectively. The model also gives a remarkable prediction of Dirac CP violation $\\delta_{CP}=172.598^\\circ$ in both normal and inverted hierarchies which is still missing in the neutrino mixing matrix.
Emerging lattice approach to the K-Unitarity Triangle
Lehner, Christoph; Soni, Amarjit
2015-01-01
It has been clear for past many years that in low energy observables new physics can only appear as a perturbation. Therefore precise theoretical predictions and precise experimental measurements have become mandatory. Here we draw attention to the significant advances that have been made on the lattice in recent years in $K\\to \\pi \\pi$, $\\Delta M_K$, the long-distance part of $\\varepsilon$ and rare K-decays. Thus, in conjunction with experiments, the construction of a unitarity triangle purely from Kaon physics should soon become feasible. Along with the B-unitarity triangle, this should allow for more stringent tests of the Standard Model and tighter constraints on new physics.
Algebraic proof and application of Lumley's realizability triangle
Gerolymos, G A
2016-01-01
Lumley [Lumley J.L.: Adv. Appl. Mech. 18 (1978) 123--176] provided a geometrical proof that any Reynolds-stress tensor $\\overline{u_i'u_j'}$ (indeed any tensor whose eigenvalues are invariably nonnegative) should remain inside the so-called Lumley's realizability triangle. An alternative formal algebraic proof is given that the anisotropy invariants of any positive-definite symmetric Cartesian rank-2 tensor in the 3-D Euclidian space $\\mathbb{E}^3$ define a point which lies within the realizability triangle. This general result applies therefore not only to $\\overline{u_i'u_j'}$ but also to many other tensors that appear in the analysis and modeling of turbulent flows. Typical examples are presented based on DNS data for plane channel flow.
Triangle-based key management scheme for wireless sensor networks
Institute of Scientific and Technical Information of China (English)
Hangyang DAI; Hongbing XU
2009-01-01
For security services in wireless sensor net-works, key management is a fundamental building block.In this article, we propose a triangle-based key predis-tribution approach and show that it can improve the effectiveness of key management in wireless sensor networks. This is achieved by using the bivariate polynomial in a triangle deployment system based on deployment information about expected locations of the sensor nodes. The analysis indicates that this scheme can achieve higher probability of both direct key establishment and indirect key establishment. On the other hand, the security analysis shows that its security against node capture would increase with a decrease of the sensor node deployment density and size of the deployment model and an increase of the polynomial degree.
Micheau, Jean-Claude; Coudret, Christophe; Cruz, José-Manuel; Buhse, Thomas
2012-10-14
A comprehensive kinetic analysis of three prototypical autocatalytic cycle models based on the absolute asymmetric Soai reaction is presented. The three models, which can give rise to amplification of enantiomeric excess and mirror-image symmetry breaking, vary by their monomeric, dimeric or trimeric order of the assumed catalytic species. Our numerical approach considered the entire chiral combinatorics of the diastereomeric interactions in the models as well as the multiplicity of coupled reversible reactions without applying fast equilibration or quasi-steady state approximations. For the simplest monomeric model, an extensive range of parameters was explored employing a random grid parameter scanning method that revealed the influence of the parameter values on the product distribution, the reaction-time, the attenuation or amplification of enantiomeric excess as well as on the presence or absence of mirror-image symmetry breaking. A symmetry breaking test was imposed on the three models showing that an increase in the catalytic oligomer size from one to three leads to a higher tolerance to poorer chiral recognition between the diastereoisomers and identifies the greater impact of the diastereoisomeric energy difference over an imperfect stereoselectivity in the catalytic step. This robustness is understood as a particular case of so-called kinetic proofreading in asymmetric autocatalysis.
D=11 superstring model with 30 kappa--symmetries and 30/ 32 BPS states in an extended superspace
Bandos, I A; Picon, M; Varela, O
2003-01-01
A superstring model in the D=11 superspace maximally extended by antisymmetric tensor bosonic coordinates, $\\Sigma^{(528|32)}$, is proposed. It possesses 30 kappa-symmetries and 32 target space supersymmetries. The usual preserved supersymmetry--kappa-symmetry correspondence suggests that it describes the excitations of a BPS state preserving all but two supersymmetries. The model can also be formulated in any $\\Sigma^{({n(n+1)\\over 2}|n)}$ superspace, n=32 corresponding to D=11. It may also be treated as a `higher--spin generalization' of the usual Green--Schwarz superstring. Although the global symmetry of the model is a generalization of the super--Poincar\\'e group, ${\\Sigma}^{({n(n+1)\\over 2}|n)}\\times\\supsetSp(n)$, it may be formulated in terms of constrained OSp(2n|1) orthosymplectic supertwistors. We workout this supertwistor realization and its Hamiltonian dynamics. We also give the super--p--brane generalization of the model. In particular, the $\\Sigma^{(528|32)}$ supermembrane model describes excita...
The disease triangle: pathogens, the environment and society.
Scholthof, Karen-Beth G
2007-02-01
The primary means to define any disease is by naming a pathogen or agent that negatively affects the health of the host organism. Another assumed, but often overlooked, determinant of disease is the environment, which includes deleterious physical and social effects on mankind. The disease triangle is a conceptual model that shows the interactions between the environment, the host and an infectious (or abiotic) agent. This model can be used to predict epidemiological outcomes in plant health and public health, both in local and global communities. Here, the Irish potato famine of the mid-nineteenth century is used as an example to show how the disease triangle, originally devised to interpret plant disease outcomes, can be applied to public health. In parallel, malaria is used to discuss the role of the environment in disease transmission and control. In both examples, the disease triangle is used as a tool to discuss parameters that influence socioeconomic outcomes as a result of host-pathogen interactions involving plants and humans.
Institute of Scientific and Technical Information of China (English)
李佳; 雷国平; 崔明哲; 王伟娜; 姜磊; 张健; 张鹏
2012-01-01
According to the characteristics of mining oriented urban land use and the nature of triangle model, the status and trends of urban land sustainable use of Fuxin was analyzed and evaluated. 19 evaluation indices reflecting the natural, economic and social elected to were selected build evaluation index system by combi- ning with the rationality of non-resource enviromnent, economic feasibility and non-social acceptability, and the analytic hierarchy process was used to calculate weight, three composite index values were obtained by the weighted average method. Finally, triangle model was used to analyze the status and trends of urban land sustainable use of Fuxin. The results showed that status of land sustainable use shifted from relatively non- sustainability to relatively common sustainability, the trends shifted from relatively weak sustainability to very strong sustainability, and ecological performance changed from weak to good condition from 2001 to 2009, in urban area of Fuxin. Itls feasible to apply the triangle model in evaluation of urban land sustainable use Fuxin need to focus on resolving the adjustment of industrial structure, environmental protection and population control in terms of the development in the future.%根据矿业城市土地利用特点和三角模型性质，对阜新市城市土地可持续利用状态与趋势进行分析评价。结合非资源环境合理性、经济可行性以及非社会可接受性3个指数，选取反映阜新市自然、经济和社会等方面的19项评价指标，构建评价指标体系，运用层次分析法计算权重，然后采用加权平均法求得3个综合指数值，最后利用三角模型对阜新市市区土地可持续利用状态与趋势进行分析。结果表明：2001～2009年阜新市市区土地可持续利用状态由相对不可持续上升为相对一般可持续，土地可持续利用趋势由相对弱可持续转变为相对很强可持续；生态表现
Energy Technology Data Exchange (ETDEWEB)
Yamasaki, Hisatsugu [Department of Applied Physics, Osaka City University, Osaka 558-8585 (Japan); Natsume, Yuhei [Graduate School of Science and Technology, Chiba University, Chiba 263-8522 (Japan); Terai, Akira [Department of Applied Physics, Osaka City University, Osaka 558-8585 (Japan); Nakamura, Katsuhiro [Department of Applied Physics, Osaka City University, Osaka 558-8585 (Japan)
2004-09-01
We investigate the frustrated quantum three-spin model (S{sub 1},S{sub 2},S{sub 3}) of spin = 1/2 on a triangle, in which spins are coupled with lattice-vibrational modes through the antiferromagnetic exchange interaction depending on distances between spin sites. The present model corresponds to the dynamic Jahn-Teller system E{sub g} - e{sub g} proposed by Longuet-Higgins et al (1958 Proc. R. Soc. A 244 1). This correspondence is revealed by using the transformation to Nakamura-Bishop's bases used in Phys. Rev. Lett. 54 861 (1985). Furthermore, we elucidate the relationship between a chiral order parameter {chi}-circumflex = S{sub 1}{center_dot}(S{sub 2}xS{sub 3}) in the spin system and the electronic orbital angular momentum l-circumflex{sub z} in E{sub g} - e{sub g} vibronic model: the regular oscillatory behaviour of the expectation value <{chi}-circumflex> with increasing energy can be found as in the case of
Noether symmetries and exact solutions of an Euler-Bernoulli beam model
Fatima, Aeeman; Mahomed, Fazal M.; Khalique, Chaudry Masood
2016-07-01
In this paper, a Noether symmetry analysis is carried out for an Euler-Bernoulli beam equation via the standard Lagrangian of its reduced scalar second-order equation which arises from the standard Lagrangian of the fourth-order beam equation via its Noether integrals. The Noether symmetries corresponding to the reduced equation is shown to be the inherited Noether symmetries of the standard Lagrangian of the beam equation. The corresponding Noether integrals of the reduced Euler-Lagrange equations are deduced which remarkably allows for three families of new exact solutions of the static beam equation. These are shown to contain all the previous solutions obtained from the standard Lie analysis and more.
Love triangles, quantum fluctuations and spin jam
Lee, Seung-Hun
When magnetic moments are interacting with each other in a situation resembling that of complex love triangles, called frustration, a large set of states that are energetically equivalent emerge. This leads to exotic spin states such as spin liquid and spin ice. Recently, we presented evidence for the existence of a topological glassy state, that we call spin jam, induced by quantum fluctuations. The case in point is SrCr9pGa12-9pO19 (SCGO(p)), a highly frustrated magnet, in which the magnetic Cr ions form a quasi-two-dimensional triangular system of bi-pyramids. This system has been an archetype in search for exotic spin states. Understanding the nature of the state has been a great intellectual challenge. Our new experimental data and theoretical spin jam model provide for the first time a coherent understanding of the phenomenon. Furthermore, the findings strongly support the possible existence of purely topological glassy states. Reference:
Leviatan, A
2010-01-01
This overview focuses on the notion of partial dynamical symmetry (PDS), for which a prescribed symmetry is obeyed by a subset of solvable eigenstates, but is not shared by the Hamiltonian. General algorithms are presented to identify interactions, of a given order, with such intermediate-symmetry structure. Explicit bosonic and fermionic Hamiltonians with PDS are constructed in the framework of models based on spectrum generating algebras. PDSs of various types are shown to be relevant to nuclear spectroscopy, quantum phase transitions and systems with mixed chaotic and regular dynamics.
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 ...
Häring, Reto Andreas
1993-01-01
The representations of the observable algebra of a low dimensional quantum field theory form the objects of a braided tensor category. The search for gauge symmetry in the theory amounts to finding an algebra which has the same representation category. In this paper we try to establish that every quantum field theory satisfying some basic axioms posseses a weak quasi Hopf algebra as gauge symmetry. The first step is to construct a functor from the representation category to the category of finite dimensional vector spaces. Given such a functor we can use a generalized reconstruction theorem to find the symmetry algebra. It is shown how this symmetry algebra is used to build a gauge covariant field algebra and we investigate the question why this generality is necessary.