text
stringlengths 62
2.94k
|
|---|
Clustering Properties of Dynamical Dark Energy Models ; We provide a generic but physically clear discussion of the clustering properties of dark energy models. We explicitly show that in quintessencetype models the dark energy fluctuations, on scales smaller than the Hubble radius, are of the order of the perturbations to the Newtonian gravitational potential, hence necessarily small on cosmological scales. Moreover, comparable fluctuations are associated with different gauge choices. We also demonstrate that the often used homogeneous approximation is unrealistic, and that the socalled dark energy mutation is a trivial artifact of an effective, single fluid description. Finally, we discuss the particular case where the dark energy fluid is coupled to dark matter. |
Jet RiemannLagrange Geometry and Some Applications in Theoretical Biology ; The aim of this paper is to construct a natural RiemannLagrange differential geometry on 1jet spaces, in the sense of nonlinear connections, generalized Cartan connections, dtorsions, dcurvatures, jet electromagnetic fields and jet electromagnetic YangMills energies, starting from some given nonlinear evolution ODEs systems modelling biologic phenomena like the cancer cell population model or the infection by human immunodeficiency virustype 1 HIV1 model. |
Chaos in Galaxies ; After general considerations about limits of theories and models, where small changes may imply large effects, we discuss three cases in galactic astrophysics illustrating how galactic dynamics models may become insufficient when previously neglected effects are taken into account 1 Like in 3D hydrodynamics, the nonlinearity of the PoissonBoltzmann system may imply dissipation through the growth of discontinuous solutions. 2 The relationship between the microscopic exponential sensitivity of Nbody systems and the stability of mean field galaxy models. 3 The role of quantum physics in the dynamics of structure formation, considering that cosmological neutrinos are massive and semidegenerate fermions. |
Interaction between scalar field and ideal fluid with inhomogeneous equation of state ; In this letter we study a model of interaction between the scalar field and an inhomogeneous ideal fluid. We have considered two forms of the ideal fluid and a power law expansion for the scale factor. We have solved the equations for the energy densities. Also we show that besides being a dark energy model to explain the cosmic acceleration, this model shows a decaying nature of the scalar field potential and the interaction parameter. |
Maxisets for Model Selection ; We address the statistical issue of determining the maximal spaces maxisets where model selection procedures attain a given rate of convergence. By considering first general dictionaries, then orthonormal bases, we characterize these maxisets in terms of approximation spaces. These results are illustrated by classical choices of wavelet model collections. For each of them, the maxisets are described in terms of functional spaces. We take a special care of the issue of calculability and measure the induced loss of performance in terms of maxisets. |
A 5Dimensional Spherical Symmetric Solution in EinsteinYangMills Theory With GaussBonnet Term ; We present a numerical solution on a 5dimensional spherically symmetric space time, in EinsteinYangMillsGaussBonnet theory using a two point boundary value routine. It turns out that the GaussBonnet contribution has a profound influence on the behaviour of the particlelike solution it increases the number of nodes of the YM field. When a negative cosmological constant in incorporated in the model, it turns out that there is no horizon and no singular behaviour of the model. For positive cosmological constant the model has singular behaviour. |
Reactiondiffusion processes in zero transverse dimensions as toy models for highenergy QCD ; We examine numerically different zerodimensional reactiondiffusion processes as candidate toy models for highenergy QCD evolution. Of the models examined Reggeon Field Theory, Directed Percolation and Reversible Processes only the latter shows the behaviour commonly expected, namely an increase of the scattering amplitude with increasing rapidity. Further, we find that increasing recombination terms, quantum loops and the heuristic inclusion of a running of the couplings, generically slow down the evolution. |
Quantum simulator for the Ising model with electrons floating on a helium film ; We propose a physical setup that can be used to simulate the quantum dynamics of the Ising model with presentday technology. Our scheme consists of electrons floating on superfluid helium which interact via Coulomb forces. In the limit of low temperatures, the system will stay near the ground state where its Hamiltonian is equivalent to the Ising model and thus shows phenomena such as quantum criticality. Furthermore, the proposed design could be generalized in order to study interacting field theories e.g., lambdaphi4 and adiabatic quantum computers. |
A model of the quantumclassical and mindbrain connections, and of the role of the quantum Zeno effect in the physical implementation of conscious intent ; A simple exactly solvable model is given of the dynamical coupling between a person's classically described perceptions and that person's quantum mechanically described brain. The model is based jointly upon von Neumann's theory of measurement and the empirical findings of close connections between conscious intentions and synchronous oscillations in well separated parts of the brain. A quantumZenoeffectbased mechanism is described that allows conscious intentions to influence brain activity in a functionally appropriate way. The robustness of this mechanism in the face of environmental decoherence effects is emphasized. |
Cauchy problem for viscous shallow water equations with a term of capillarity ; In this article, we consider the compressible NavierStokes equation with density dependent viscosity coefficients and a term of capillarity introduced by Coquel et al in cite5CR. This model includes at the same time the barotropic NavierStokes equations with variable viscosity coefficients, shallowwater system and the model of Rohde. We first study the wellposedness of the model in critical regularity spaces with respect to the scaling of the associated equations. In a functional setting as close as possibleto the physical energy spaces, we prove global existence of solutions close to a stable equilibrium, and local in time existence for solutions with general initial data. Uniqueness is also obtained. |
On false discovery control under dependence ; A popular framework for false discovery control is the random effects model in which the null hypotheses are assumed to be independent. This paper generalizes the random effects model to a conditional dependence model which allows dependence between null hypotheses. The dependence can be useful to characterize the spatial structure of the null hypotheses. Asymptotic properties of false discovery proportions and numbers of rejected hypotheses are explored and a largesample distributional theory is obtained. |
Detectability of a phantomlike braneworld model with the integrated SachsWolfe effect ; We study a braneworld model in which a phantomlike behaviour occurs with only cold dark matter and a cosmological constant, due to a large distance modification of gravity. With the addition of curvature, the geometrical tests are not strict enough to rule out models in which gravity is modified significantly on large scales. We show that this degeneracy in the parameter space is broken by the structure formation tests, such as the integrated SachsWolfe effect, which can probe general relativity on large scales. |
A Lindblad model for a spin chain coupled to heat baths ; We study a XY model which consists of a spin chain coupled to heat baths. We give a repeated quantum interaction Hamiltonian describing this model. We compute the explicit form of the associated Lindblad generator in the case of the spin chain coupled to one, two and several heat baths. We further study the properties of quantum master equation such as approach to equilibrium, local equilibrium states, entropy production and quantum detailed balance condition. |
Skepsis on the scenario of Biological Evolution provided by stochastic models ; Stochastic models, based on random processes, may lead to power law distributions, which provide long range correlations. The observation of power law behavior and the presence of long range correlations in biological systems has been demonstrated in various studies. The combination of the two just mentioned results, theoretical and experimental, supports strongly the scenario of biological evolution across different organisms. In the current Letter we explore in a general way, using the algebra of Nonextensive Statistics introduced by Tsallis and coworkers, if the processes which are described by a class of stochastic models are really random and discuss the results with regard to a possible biological evolution. |
Noncanonicaly Embedded Rational Map Soliton in Quantum SU3 Skyrme Model ; The quantum Skyrme model is considered in non canonical bases SU3 SO3 for the state vectors. A rational map ansatz is used to describe the soliton with the topological number bigger than one. The canonical quantization of the Lagrangian generates in Hamiltonian five different moments of inertia and negative quantum mass corrections, which can stabilize the quantum soliton solution. Explicit expressions of the quantum Lagrangian and the Hamiltonian are derived for this model soliton. |
An entirely analytical cosmological model ; The purpose of the present study is to show that in a particular cosmological model, with an affine equation of state, one can obtain, besides the background given by the scale factor, Hubble and deceleration parameters, a representation in terms of scalar fields and, more important, explicit mathematical expressions for the density contrast and the power spectrum. Although the model so obtained is not realistic, it reproduces features observed in some previous numerical studies and, therefore, it may be useful in the testing of numerical codes and as a pedagogical tool. |
On the parabolicelliptic limit of the doubly parabolic KellerSegel system modelling chemotaxis ; We establish new convergence results, in strong topologies, for solutions of the parabolicparabolic KellerSegel system in the plane, to the corresponding solutions of the parabolicelliptic model, as a physical parameter goes to zero. Our main tools are suitable spacetime estimates, implying the global existence of slowly decaying in general, nonintegrable solutions for these models, under a natural smallness assumption. |
Extended Zee model for Neutrino Mass, Leptogenesis and Sterile Neutrino like Dark Matter ; We propose an extension of the standard model with a U1rm BL global symmetry that accommodates radiative neutrino masses along with dark matter and leptogenesis. The observed matter antimatter asymmetry of the universe is generated through the leptogenesis route keeping the U1rm BL symmetry intact. The BL global symmetry is then softly broken, providing the subeV neutrino masses. The model then incorporates a MeV scale sterile neutrino like dark matter. |
Mass Matrix Model Broken From A4 To 2 leftrightarrow 3 Symmetry ; 2leftrightarrow3 symmetry is realized by the breaking from alterating group of degree 4 A4 symmetry. A4 explains why the generation number is three. However the mass matrices are realized in the form of the breaking to 2leftrightarrow 3 symmetry times Z3, which leads us to 2leftrightarrow 3 symmetric mass matrix with vanishing 1,1 component. Thus the 3times 3 mass matrix model with 2leftrightarrow 3 symmetry and vanishing 1,1 component has the group theoretical background as the symmetry in GUT model. |
Efficient quantum circuits for oneway quantum computing ; While Isingtype interactions are ideal for implementing controlled phase flip gates in oneway quantum computing, natural interactions between solidstate qubits are most often described by either the XY or the Heisenberg models. We show an efficient way of generating cluster states directly using either the iSWAP gate for the XY model, or the sqrtrm SWAP gate for the Heisenberg model. Our approach thus makes oneway quantum computing more feasible for solidstate devices. |
On Torsionfree Vacuum Solutions of the Model of de Sitter Gauge Theory of Gravity ; It is shown that all vacuum solutions of Einstein field equation with a positive cosmological constant are the solutions of a model of dS gauge theory of gravity. Therefore, the model is expected to pass the observational tests on the scale of solar system and explain the indirect evidence of gravitational wave from the binary pulsars PSR191316. |
Magnetism of quantum dot clusters A Hubbard model study ; Magnetic properties of two and threedimensional clusters of quantum dots are studied with exact diagonalization of a generalized Hubbard model. We study the weak coupling limit, where the electrons interact only within a quantum dot and consider cases where the second or third harmonic oscillator shell is partially filled. The results show that in the case of halffilled shell the magnetism is determined by the antiferromagnetic Heisenberg model with spin 12, 1 or 32, depending on the number of electrons in the open shell. For other fillings the system in most cases favors a large total spin, indicating a ferromagnetic coupling between the dots. |
Quantum induced w 1 crossing of the quintessence and phantom models ; Considering the single scalar field models of dark energy, i.e. the quintessence and phantom models, it is shown that the quantum effects can cause the system crosses the w 1 line. This phenomenon does not occur in classical level. The quantum effects are described via the account of conformal anomaly. |
Model category extensions of the PirashviliSominska theorems ; We describe the class of semistable model categories, which generalize the equivalence of finite products and coproducts in abelian and stable model categories, and use this to establish Morita equivalences among categories of functors. We provide a construction of pairs of small categoriesknown as conjugate pairswhose associated categories of diagrams are Quillen equivalent in the semistable setting. We frame our development in the context of Morita theory, following Slominska's work on similar questions for categories of functors enriched over and taking values in Rmodules. |
Twofield cosmological models and largescale cosmic magnetic fields ; We consider two different toy cosmological models based on two fields one normal scalar and one phantom realizing the same evolution of the BangtoRip type. One of the fields pseudoscalar interacts with the magnetic field breaking the conformal invariance of the latter. The effects of the amplification of cosmic magnetic fields are studied and it is shown that the presence of such effects can discriminate between different cosmological models realizing the same global evolution of the universe. |
Fractional dynamic symmetries and the ground state properties of nuclei ; Based on the Riemann and Caputo definition of the fractional derivative we use the fractional extensions of the standard rotation group SO3 to construct a higher dimensional representation of a fractional rotation group with mixed derivative types. An extended symmetric rotor model is derived, which predicts the sequence of magic proton and neutron numbers accurately. The ground state properties of nuclei are correctly reproduced within the framework of this model. |
Notes on interacting holographic dark energy model in a closed universe ; We consider interacting holographic dark energy model in Friedmann Robertson Walker space time with positive spatial curvature and investigate the behavior of curvature parameter and dark energy density in accelerated expanding epoch. We also derive some conditions needed to cross the phantom divide line in this model. |
Discontinuity Induced Bifurcations in a Model of Saccharomyces cerevisiae ; We perform a bifurcation analysis of the mathematical model of Jones and Kompala K.D. Jones and D.S. Kompala, Cybernetic model of the growth dynamics of Saccharomyces cerevisiae in batch and continuous cultures, J. Biotech., 71105131, 1999. Stable oscillations arise via AndronovHopf bifurcations and exist for intermediate values of the dilution rate as has been noted from experiments previously. A variety of discontinuity induced bifurcations arise from a lack of global differentiability. We identify and classify discontinuous bifurcations including several codimensiontwo scenarios. Bifurcation diagrams are explained by a general unfolding of these singularities. |
A note on dark energy induced by Dbrane motion ; In this note we study the possibility of obtaining dark energy solution in a Dbrane scenario in a warped background that includes braneposition dependent corrections for the nonperturbative superpotential. The volume modulus is stabilized at instantaneous minima of the potential. Though the model can account for the existence of dark energy within present observational bound finetuning of the model parameters becomes unavoidable. Moreover, the model does not posses a tracker solution. |
Vector models for dark energy ; We explore the possibility that the present stage of accelerated expansion of the universe is due to the presence of a cosmic vector field. We show that vector theories allow for the generation of an accelerated phase without the introduction of potential terms or unnatural scales in the Lagrangian. We propose a particular model with the same number of parameters as LCDM and excellent fits to SNIa data. The model is scaling during radiation era, with natural initial conditions, thus avoiding the cosmic coincidence problem. Upcoming observations will be able to clearly discriminate it from standard LCDM cosmology |
Displacementnoisefree gravitationalwave detection with two FabryPerot cavities ; We propose two detuned FabryPerot cavities, each pumped through both the mirrors, positioned in line as a toy model of the gravitationalwave GW detector free from displacement noise of the test masses. It is demonstrated that the noise of cavity mirrors can be completely excluded in a proper linear combination of the cavities output signals. This model is illustrated by a simplified round trip model without FabryPerot cavities. We show that in lowfrequency region the obtained displacementnoisefree response signal is stronger than the one of the interferometer recently proposed by S.Kawamura and Y.Chen. |
Exact JastrowSlater wave function for the onedimensional Luttinger model ; We show that it is possible to describe the ground state of the Luttinger model in terms of a JastrowSlater wave function. Moreover, our findings reveal that oneparticle excitations and their corresponding dynamics can be faithfully represented only when a Jastrow factor of a similar form is applied to a coherent superposition of many Slater determinants. We discuss the possible relevance of this approach for the theoretical description of photoemission spectra in higher dimensionality, where the present wave function can be straightforwardly generalized and can be used as a variational ansatz, that is exact for the 1D Luttinger model. |
Neutrino mass and lowscale leptogenesis in a testable SUSY SO10 model ; It is shown that a supersymmetric SO10 model extended with fermion singlets can accommodate the observed neutrino masses and mixings as well as generate the desired lepton asymmetry in concordance with the gravitino constraint. A necessary prediction of the model is nearTeV scale doublycharged Higgs scalars which should be detectable at the LHC. |
Gravity in Gauge Mediation ; We investigate O'Raifeartaightype models for Fterm supersymmetry breaking in gauge mediation scenarios in the presence of gravity. It is pointed out that the vacuum structure of those models is such that in metastable vacua gravity mediation contribution to scalar masses is always suppressed to the level below 1 percent, almost sufficient for avoiding FCNC problem. Close to that limit, gravitino mass can be in the range 10100 GeV, opening several interesting possibilities for gauge mediation models, including GiudiceMasiero mechanism for mu and Bmu generation. Gravity sector can include stabilized moduli. |
Pair Production of TwoHiggsDoubletModel Light Higgs Bosons in Collisions ; We study the production of a pair of light, neutral, CPeven Higgs bosons in photonphoton collisions within the general Two Higgs Doublet Model THDM. This is a process for which the lowest order contribution in both, the Standard Model and the THDM, appears at one loop. We find that the cross section for this process can be much larger in the THDM than in the Standard Model and the number of events expected at the Photon Collider will allow a determination of some of the parameters in the scalar potential. |
Symmetries and exact solutions of the rotating shallow water equations ; Lie symmetry analysis is applied to study the nonlinear rotating shallow water equations. The 9dimensional Lie algebra of point symmetries admitted by the model is found. It is shown that the rotating shallow water equations are related with the classical shallow water model with the change of variables. The derived symmetries are used to generate new exact solutions of the rotating shallow equations. In particular, a new class of timeperiodic solutions with quasiclosed particle trajectories is constructed and studied. The symmetry reduction method is also used to obtain some invariant solutions of the model. Examples of these solutions are presented with a brief physical interpretation. |
RelativeVelocityDependent Webertype Models in Electromagnetism ; This article reconsiders the relativevelocitydependent approach to modeling electromagnetism that was proposed initially by Weber before data from cathoderaytube CRT experiments was available. It is shown that identifying the nonlinear, relativevelocity terms using CRT data results in a model, which not only captures standard relativistic effects in optics, highenergy particles, and gravitation, but also explains apparent discrepancies between predicted and measured energy i in highenergyparticle absorption experiments and ii in the classical betaray spectrum of radiumE. |
Critical Behaviour of Structure Factors at a Quantum Phase Transition ; We review the theoretical behaviour of the total and oneparticle structure factors at a quantum phase transition for temperature T0. The predictions are compared with exact or numerical results for the transverse Ising model, the alternating Heisenberg chain, and the bilayer Heisenberg model. At the critical wavevector, the results are generally in accord with theoretical expectations. Away from the critical wavevector, however, different models display quite different behaviours for the oneparticle residues and structure factors. |
Implied volatility explosions European calls and implied volatilities close to expiry in exponential Levy models ; We examine the small expiry behaviour of European call options in stock price models of exponential L'evy type. In most cases of interest, we are able to identify the exact small expiry asymptotics. In complete generality we are able to show that the time value of the call option has Otau decay as tau time to expiry goes to zero. Using our results on the behaviour of call options close to expiry we show that implied volatility explodes as tauto0 in most exponential L'evy models. Attention is restricted to calls and implied volatilities that are not atthemoney. |
Network effects in a human capital based economic growth model ; We revisit a recently introduced agent modelACS bf 11, 99 2008, where economic growth is a consequence of education human capital formation and innovation, and investigate the influence of the agents' social network, both on an agent's decision to pursue education and on the output of new ideas. Regular and random networks are considered. The results are compared with the predictions of a mean field representative agent model. |
Generalization of the model of conflict between two armed groups ; The conflicts between armed groups often go on for years. The classical model of such conflicts accounts for the number of participants and for the technology level of the equipment of the groups. Below we extend this model in order to account for events that are present for limited time. As examples we discuss three kinds of such events inclusion of reserves, presence of epidemics and use of nonconventional weapons. We show that if such events are not handled properly by the leaders of the groups the corresponding group can lose the conflict. |
The rheology of hard sphere suspensions at arbitrary volume fractions An improved differential viscosity model ; We propose a simple and general model accounting for the dependence of the viscosity of a hard sphere suspension at arbitrary volume fractions. The model constitutes a continuummedium description based on a recursivedifferential method that assumes a hierarchy of relaxation times. Geometrical information of the system is introduced through an effective volume fraction that approaches the usual filling fraction at low concentrations and becomes one at maximum packing. The agreement of our expression for the viscosity with experiments at low and highshear rates and in the highfrequency limit is remarkable for all volume fractions. |
On the violation of the CHSH network model inequality ; In the present paper it is demonstrated that the quantum correlation 2dim unitary parameter vectors can be arbitrarily close approximated with a local hidden variables model. Moreover, the CHSH inequality can be violated with the present model. This does not conclusively demonstrate that locality and causality can be restored to quantum mechanics. However, it does show that an experimental search for local hidden causality need not be fruitless beforehand. |
The driving force of labor productivity ; Labor productivity in developed countries is analyzed and modeled. Modeling is based on our previous finding that the rate of labor force participation is a unique function of GDP per capita. Therefore, labor productivity is fully determined by the rate of economic growth, and thus, is a secondary economic variable. Initially, we assess a model for the U.S. and then test it using data for Japan, France, the UK, Italy, and Canada. Results obtained for these countries validate those for the U.S. The evolution of labor force productivity is predictable at least at an 11year horizon |
Offdiagonal correlations in onedimensional anyonic models A replica approach ; We propose a generalization of the replica trick that allows to calculate the large distance asymptotic of offdiagonal correlation functions in anyonic models with a proper factorizable groundstate wavefunction. We apply this new method to the exact determination of all the harmonic terms of the correlations of a gas of impenetrable anyons and to the Calogero Sutherland model. Our findings are checked against available analytic and numerical results. |
Reconstructing a StringInspired Nonminimally Coupled Quintom Model ; Motivated by the recent work of Zhang and Chen citebin, we generalize their work to the nonminimally coupled case. We consider a quintom model of dark energy with a single scalar field T given by a Lagrangian which inspired by tachyonic Lagrangian in string theory. We consider nonminimal coupling of tachyon field to the scalar curvature, then we reconstruct this model in the light of three forms of parametrization for dynamical dark energy. |
Reconstructing the potentials for the quintessence and tachyon dark energy, from the holographic principle ; We propose an holographic quintessence and tachyon models of dark energy. The correspondence between the quintessence and tachyon energy densities with the holographic density, allows the reconstruction of the potentials and the dynamics for the quintessence and tachyon fields, in flat FRW background. The proposed infrared cutoff for the holographic energy density works for two cases of the constant alpha for alpha1 we reconstructed the holographic quintessence model in the region before the omega1 crossing for the EoS parameter. The cosmological dynamics for alpha1 was also reconstructed for the holographic quintessence and tachyon models. |
Four switching categories for thinfilm and bulk ferroelectrics ; We classify the switching kinetics of ferroelectrics including both epitaxialpolycrystalline thin films and singlecrystallineceramic bulks at various applied fields into four categories, depending on whether the depolarization field andor the polarization reversal induced by the switching promotion effect between adjacent parts can be neglected. We show that our statistical model developed very recently Journal of Physics Condensed Matter 21, 012207 2009 in its generalized form applies to all these four categories. Finally we make the comparison between our model and the conventional KolmogorovAvramiIshibashi model and discuss the behavior of the switching currents for different n. |
Modeling H2 Fluorescence in Planetary Atmospheres with Partial Frequency Redistribution ; We present the modeling of partial frequency redistribution PRD effects for the fluorescent emission lines of molecular hydrogen, the general computational approximations, and the applications to planetary atmospheres, as well as interstellar medium. Our model is applied to FUSE observations of Jupiter, Saturn, and reflection nebulae, allowing an independent confirmation of the H2 abundance and the structure of planetary atmospheres. |
A discrete inhomogeneous model for the yeast cell cycle ; We study the robustness and stability of the yeast cell regulatory network by using a general inhomogeneous discrete model. We find that inhomogeneity, on average, enhances the stability of the biggest attractor of the dynamics and that the large size of the basin of attraction is robust against changes in the parameters of inhomogeneity. We find that the most frequent orbit, which represents the cellcycle pathway, has a better biological meaning than the one exhibited by the homogeneous model. |
A geometricprobabilistic method for counting lowlying states in the BoussoPolchinski Landscape ; We propose an accurate method for counting states of close to zero and positive cosmological constant in the BoussoPolchinski Landscape. This method is based on simple geometrical considerations on the highdimensional lattice of quantized fluxes and on a probabilistic model the random hyperplane model that provides a distribution of the values of the cosmological constant. Justification of the assumptions made in this model are given by means of numerical experiments. |
RealValued Charged Fields and Interpretation of Quantum Mechanics II ; In the first part of this work httpwww.arxiv.orgabsquantph0509044, it was shown that the KleinGordonMaxwell electrodynamics in the unitary gauge allows natural elimination of the particle wave function and describes independent evolution of the electromagnetic field. Therefore, the electromagnetic field can be regarded as the guiding field in the Bohm interpretation of quantum mechanics. An extension of those results to the DiracMaxwell electrodynamics was less general, but represented at least an interesting toy model of quantum theory. Another model based on the DiracMaxwell electrodynamics is considered in this work. The model also typically allows elimination of the wave function and describes independent evolution of the electromagnetic field. |
Dark energy and possible alternatives ; We present a brief review of various approaches to late time acceleration of universe. The cosmological relevance of scaling solutions is emphasized in case of scalar field models of dark energy. The underlying features of a variety of scalar field models is highlighted. Various alternatives to dark energy are discussed including the string curvature corrections to EinsteinHilbert action, higher dimensional effects, nonlocally corrected gravity and fR theories of gravity. The recent developments related to fR models with disappearing cosmological constant are reviewed. |
A TeVscale model for neutrino mass, DM and baryon asymmetry ; We discuss a model which would explain neutrino oscillation, dark matter, and baryon asymmetry of the Universe simultaneously by the physics at TeV scales. Tiny neutrino masses are generated at the three loop level due to the exact Z2 symmetry, by which the stability of the dark matter candidate is also guaranteed. The extra Higgs doublet is required not only for the tiny neutrino masses but also for successful electroweak baryogenesis. The model provides various discriminative predictions especially in charged Higgs phenomenology. |
An Adaptive Markov Chain Monte Carlo Method for GARCH Model ; We propose a method to construct a proposal density for the MetropolisHastings algorithm in Markov Chain Monte Carlo MCMC simulations of the GARCH model. The proposal density is constructed adaptively by using the data sampled by the MCMC metho d itself. It turns out that autocorrelations between the data generated with our adaptive proposal density are greatly reduced. Thus it is concluded that the adaptive construction method is very efficient and works well for the MCMC simulations of the GARCH model. |
Neutrino Models and Leptogenesis ; Neutrino properties can play a crucial role in determining the matterantimatter asymmetry of the universe if thermal leptogenesis is the correct solution to the baryogenesis problem. Owing to this, the study of neutrino models goes beyond the mere purpose of generating tiny neutrino masses, and it is natural to incorporate the puzzle of the cosmic baryon asymmetry. To this end, we have investigated several different extensions of the neutrino model based on the type I seesaw mechanism with particular emphasis on their leptogenesis implications. |
Compactons versus Solitons ; We investigate whether the recently proposed PTsymmetric extensions of generalized Kortewegde Vries equations admit genuine soliton solutions besides compacton solitary waves. For models which admit stable compactons having a width which is independent of their amplitude and those which possess unstable compacton solutions the Painleve test fails, such that no soliton solutions can be found. The Painleve test is passed for models allowing for compacton solutions whose width is determined by their amplitude. Consequently these models admit soliton solutions in addition to compactons and are integrable. |
Fermions Coupled to Emergent Noncommutative Gravity ; We study the coupling of fermions to YangMills matrix models in the framework of emergent noncommutative gravity. It is shown that the matrix model action provides an appropriate coupling for fermions to gravity, albeit with a nonstandard spinconnection. Integrating out the fermions in a nontrivial geometrical background induces indeed the EinsteinHilbert action for onshell geometries plus a dilatonlike term. This result explains UVIR mixing as a gravity effect. It also illuminates why UVIR mixing remains even in supersymmetric models, except in the N4 case. |
Linear Processes for Functional Data ; Linear processes on functional spaces were born about fifteen years ago. And this original topic went through the same fast development as the other areas of functional data modeling such as PCA or regression. They aim at generalizing to random curves the classical ARMA models widely known in time series analysis. They offer a wide spectrum of models suited to the statistical inference on continuous time stochastic processes within the paradigm of functional data. Essentially designed to improve the quality and the range of prediction, they give birth to challenging theoretical and applied problems. We propose here a state of the art which emphasizes recent advances and we present some promising perspectives based on our experience in this area. |
Existence of weak solution for compressible fluid models of Korteweg type ; This work is devoted to prove existence of global weak solutions for a general isothermal model of capillary fluids derived by J. E Dunn and J. Serrin 1985 6, which can be used as a phase transition model. We improve the results of 5 by showing the existence of global weak solution in dimension two for initial data in the energy space, close to a stable equilibrium and with specific choices on the capillary coefficients. In particular we are interested in capillary coefficients approximating a constant capillarity coefficient. To finish we show the existence of global weak solution in dimension one for a specific type of capillary coefficients with large initial data in the energy space. |
T' Predictions of PMNS and CKM Angles ; Generalizing a previous model to accommodate the third quark family and CP violation, we present a T' model which predicts tribimaximal neutrino PMNS mixings while the central predictions for quark mixings are VtdVts 0.245 and VubVcb 0.237 with a predicted CP violating KM phase deltaKM 65.80. All these are acceptably close to experiment, including the KM phase for which the allowed values are 630 deltaKM 720, and depend only on use of symmetry T' times Z2 to define the model and no additional parameters. |
Tailoring triaxial Nbody models via a novel madetomeasure method ; The madetomeasure Nbody method Syer Tremaine 1996 slowly adapts the particle weights of an Nbody model, whilst integrating the trajectories in an assumed static potential, until some constraints are satisfied, such as optimal fits to observational data. I propose a novel technique for this adaption procedure, which overcomes several limitations and shortcomings of the original method. The capability of the new technique is demonstrated by generating realistic Nbody equilibrium models for darkmatter haloes with prescribed density profile, triaxial shape, and slowly outwardly growing radial velocity anisotropy |
Dark energy interacting with dark matter and unparticle ; We study dynamical behaviors of the dark energy models interacting with dark matter and unparticle in the standard flat FRW cosmology. We considered four different interacting models and examined the stability of the critical points. We find that there exist latetime scaling attractors corresponding to an accelerating Universe and the alleviation of the coincidence problem depends on the choice of parameters in the models. |
Neuronal Coding of pacemaker neurons A random dynamical systems approach ; The behaviour of neurons under the influence of periodic external input has been modelled very successfully by circle maps. The aim of this note is to extend certain aspects of this analysis to a much more general class of forcing processes. We apply results on the fibred rotation number of randomly forced circle maps to show the uniqueness of the asymptotic firing frequency of ergodically forced pacemaker neurons. The details of the analysis are carried out for the forced leaky integrateandfire model, but the results should also remain valid for a large class of further models. |
Heterogeneous pair approximation for voter models on networks ; For models whose evolution takes place on a network it is often necessary to augment the meanfield approach by considering explicitly the degree dependence of average quantities heterogeneous meanfield. Here we introduce the degree dependence in the pair approximation heterogeneous pair approximation for analyzing voter models on uncorrelated networks. This approach gives an essentially exact description of the dynamics, correcting some inaccurate results of previous approaches. The heterogeneous pair approximation introduced here can be applied in full generality to many other processes on complex networks. |
Matrix factorisations and open topological string theory ; Amplitudes in open topological string theory may be described completely by certain Ainfinitycategories. We detail a general construction of all cyclic minimal models for a given Ainfinityalgebra and apply this result to the case of N2 supersymmetric LandauGinzburg models. This allows to solve the treelevel theory in the sense that all amplitudes and hence the effective superpotential can be computed algorithmically. Furthermore, the construction provides a novel derivation of the topological metric of such models. |
On the gauge coupling unification ; We consider a quarklepton symmetry model of unification of the strong and electromagnetic interactions. The model has the gauge group SU4times U1Y and the minimal Higgs structure consisting of one complex quartet of scalar particles. The spontaneous breakdown of the gauge group to SU3ctimes U1em due to nonzero vacuum expectation value of the Higgs quartet provides the simplest realization of the Higgs mechanism which generates masses for gauge bosons, and masses to quarks and leptons. Using the embedding of the gauge group to SU5, we study the evolution of coupling constants and find a connection of the couplings with the gauge couplings of the standard model. |
Diffeomorphism covariant star products and noncommutative gravity ; The use of a diffeomorphism covariant star product enables us to construct diffeomorphism invariant gravities on noncommutative symplectic manifolds without twisting the symmetries. As an example, we construct noncommutative deformations of all twodimensional dilaton gravity models thus overcoming some difficulties of earlier approaches. One of such models appears to be integrable. We find all classical solutions of this model and discuss their properties. |
Fermion Mixings in SU9 Family Unification ; In an SU9 model of gauged family unification, we propose an explanation for why angles observed in the lepton flavor it PMNS mixing matrix are significantly larger than those measured for any analagous quark flavor it KM mixing angle. It is directly related to a seesaw mechanism that we assume to be responsible for the generation of neutrino masses. Our model is more constrained and therefore even more predictive than a model previously proposed by Barr. |
Fewphotons model of the optical emission of semiconductor quantum dots ; The JaynesCummings model provides a well established theoretical framework for single electron two level systems in a radiation field. Similar exactly solvable models for semiconductor light emitters such as quantum dots dominated by many particle interactions are not known. We access these systems by a generalized cluster expansion, the photonprobabilityclusterexpansion a reliable approach for few photon dynamics in many body electron systems. As a first application, we discuss vacuum Rabi flopping and show that their amplitude determines the number of electrons in the quantum dot. |
LemaitreTolmanBondi cosmological models, smoothness, and positivity of the central deceleration parameter ; We argued in a previous paper R. A. Vanderveld et al. 2006, arXivastroph0602476 that negative deceleration parameters at the center of symmetry in LemaitreTolmanBondi cosmological models can only occur if the model is not smooth at the origin. Here we demonstrate explicitly the connection between nonsmoothness and the failure of positivity theorems for deceleration. We also address some confusion that has arisen in the literature and respond to some recent criticisms of our arguments. |
Universal Quantum Computation with Abelian Anyon Models ; We consider topological quantum memories for a general class of abelian anyon models defined on spin lattices. These are nonuniversal for quantum computation when restricting to topological operations alone, such as braiding and fusion. The effects of additional nontopological operations, such as spin measurements, are studied. These are shown to allow universal quantum computation, while still utilizing topological protection. Our work gives an insight into the relation between abelian models and their nonabelian counterparts. |
Models and theories of lambda calculus ; In this paper we briefly summarize the contents of Manzonetto's PhD thesis which concerns denotational semantics and equationalorder theories of the pure untyped lambdacalculus. The main research achievements include i a general construction of lambdamodels from reflexive objects in possibly nonwellpointed categories; ii a Stonestyle representation theorem for combinatory algebras; iii a proof that no effective lambdamodel can have lambdabeta or lambdabetaeta as its equational theory this can be seen as a partial answer to an open problem introduced by HonsellRonchi Della Rocca in 1984. |
Bianchi typeI model with cosmic string in the presence of a magnetic field spinor description ; A Bianchi typeI cosmological model in the presence of a magnetic flux along a cosmic string is investigated. A nonlinear spinor field is used to simulate the cosmological cloud of strings. It is shown that the spinor field simulation offer the possibility to solve the system of Einstein's equation without any additional assumptions. It is shown that the present model is nonsingular at the end of the evolution and does not allow the anisotropic Universe to turn into an isotropic one. |
A matrix model for simple Hurwitz numbers, and topological recursion ; We introduce a new matrix model representation for the generating function of simple Hurwitz numbers. We calculate the spectral curve of the model and the associated symplectic invariants developed in EynardOrantin. As an application, we prove the conjecture proposed by Bouchard and Marino, relating Hurwitz numbers to the spectral invariants of the Lambert curve expxy expy. |
Geometry of the N2 supersymmetric sigma model with Euclidean worldsheet ; We investigate the target space geometry of supersymmetric sigma models in two dimensions with Euclidean signature, and the conditions for N2 supersymmetry. For a real action, the geometry for the N2 model is not the generalized Kahler geometry that arises for Lorentzian signature, but is an interesting modification of this which is not a complex geometry. |
Orbitalselective Mott Transitions in a Doped Twoband Hubbard Model ; We extend previous studies on orbitalselective Mott transitions in the paramagnetic state of the halffilled degenerate twoband Hubbard model to the general doped case, using a highprecision quantum Monte Carlo dynamical meanfield theory solver. For sufficiently strong interactions, orbitalselective Mott transitions as a function of total band filling are clearly visible in the bandspecific fillings, quasiparticle weights, double occupancies, and spectra. The results are contrasted with those of singleband models for similar correlation strengths. |
Closed inflationary universe in Patch Cosmology ; In this article we study closed inflationary universe models using the GaussBonnet Brane. We determine and characterize the existence of a universe with Omega 1, with an appropriate period of inflation. We have found that this model is less restrictive in comparison with the standard approach where a scalar field is considered. We use recent astronomical observations to constrain the parameters appearing in the model. |
Generalized GinzburgLandau models for nonconventional superconductors ; We review some recent extensions of the GinzburgLandau model able to describe several properties of nonconventional superconductors. In the first extension, swave superconductors endowed with two different critical temperatures are considered, their main thermodynamical and magnetic properties being calculated and discussed. Instead in the second extension we describe spintriplet superconductivity with a single critical temperature, studying in detail the main predicted physical properties. A thorough discussion of the peculiar predictions of our models and their physical consequences is as well performed. |
NeighborSpecific BGP More Flexible Routing Policies While Improving Global Stability ; Please Note This document was written to summarize and facilitate discussion regarding 1 the benefits of changing the way BGP selects routes to selecting the most preferred route allowed by export policies, or more generally, to selecting BGP routes on a perneighbor basis, 2 the safety condition that guarantees global routing stability under the NeighborSpecific BGP model, and 3 ways of deploying this model in practice. A paper presenting the formal model and proof of the stability conditions was published at SIGMETRICS 2009 and is available online. |
Entropy and efficiency of a molecular motor model ; In this paper we investigate the use of pathintegral formalism and the concepts of entropy and traffic in the context of molecular motors. We show that together with timereversal symmetry breaking arguments one can find bounds on efficiencies of such motors. To clarify this techinque we use it on one specific model to find both the thermodynamic and the Stokes efficiencies, although the arguments themselves are more general and can be used on a wide class of models. We also show that by considering the molecular motor as a ratchet, one can find additional bounds on the thermodynamic efficiency. |
Unusual Higgs or Supersymmetry from Natural Electroweak Symmetry Breaking ; This review provides an elementary discussion of electroweak symmetry breaking in the minimal and the nexttominimal supersymmetric models with the focus on the finetuning problem the tension between natural electroweak symmetry breaking and the direct search limit on the Higgs boson mass. Two generic solutions of the finetuning problem are discussed in detail models with unusual Higgs decays; and models with unusual pattern of soft supersymmetry breaking parameters. |
A NoisyChannel Model for Document Compression ; We present a document compression system that uses a hierarchical noisychannel model of text production. Our compression system first automatically derives the syntactic structure of each sentence and the overall discourse structure of the text given as input. The system then uses a statistical hierarchical model of text production in order to drop nonimportant syntactic and discourse constituents so as to generate coherent, grammatical document compressions of arbitrary length. The system outperforms both a baseline and a sentencebased compression system that operates by simplifying sequentially all sentences in a text. Our results support the claim that discourse knowledge plays an important role in document summarization. |
Finitetime fluctuations in the degree statistics of growing networks ; This paper presents a comprehensive analysis of the degree statistics in models for growing networks where new nodes enter one at a time and attach to one earlier node according to a stochastic rule. The models with uniform attachment, linear attachment the Barab'asiAlbert model, and generalized preferential attachment with initial attractiveness are successively considered. The main emphasis is on finitesize i.e., finitetime effects, which are shown to exhibit different behaviors in three regimes of the sizedegree plane stationary, finitesize scaling, large deviations. |
SingleSector Supersymmetry Breaking in Supersymmetric QCD ; We construct examples of singlesector supersymmetry breaking based on simple deformations of supersymmetric QCD with weakly gauged flavor group. These theories are calculable in a weakly coupled Seiberg dual description. In these models, some of the particles in the first two generations of quarks and leptons are composites of the same strong dynamics which leads to dynamical supersymmetry breaking. Such models can explain the hierarchies of Yukawa couplings in the Standard Model, in a way that predictively correlates with the spectrum of SUSYbreaking soft terms. |
N2 Superconformal Symmetry in Super Coset Models ; We extend the KazamaSuzuki construction of models with N2,2 worldsheet supersymmetry to cosets SK of supergroups. Among the admissible target spaces that allow for an extension to N2 superconformal algebras are some simple Lie supergroups, including PSLNN. Our general analysis is illustrated at the example of the N1 WZNW model on GL11. After constructing its N2 superconformal algebra we determine the antichiral ring of the theory. It exhibits an interesting interplay between worldsheet and target space supersymmetry. |
Exact results for the Barabasi queuing model ; Previous works on the queuing model introduced by Barab'asi to account for the heavy tailed distributions of the temporal patterns found in many human activities mainly concentrate on the extremal dynamics case and on lists of only two items. Here we obtain exact results for the general case with arbitrary values of the list length L and of the degree of randomness that interpolates between the deterministic and purely random limits. The statistically fundamental quantities are extracted from the solution of master equations. From this analysis, new scaling features of the model are uncovered. |
Interacting agegraphic dark energy models in nonflat universe ; A socalled agegraphic dark energy was recently proposed to explain the dark energydominated universe. In this Letter, we generalize the agegraphic dark energy models to the universe with spatial curvature in the presence of interaction between dark matter and dark energy. We show that these models can accommodate wD 1 crossing for the equation of state of dark energy. In the limiting case of a flat universe, i.e. k 0, all previous results of agegraphic dark energy in flat universe are restored. |
Multiferroics seen from theoretic derivation of a tight binding model ; One presented some lattice models, while the theoretic derivation has not been found, and the importance of correlation effects has to be emphasized. On the basis of the nonrelativistic Hamiltonian from the Dirac equation, we derive in detail a tight binding model. We find that both ferromagnetism and ferroelectricity are from the correlation effect between electrons, and magnetic and electric orders are strongly coupled due to the spinorbit interaction. |
Correlation functions of integrable models a description of the ABACUS algorithm ; Recent developments in the theory of integrable models have provided the means of calculating dynamical correlation functions of some important observables in systems such as Heisenberg spin chains and onedimensional atomic gases. This article explicitly describes how such calculations are generally implemented in the ABACUS C library, emphasizing the universality in treatment of different cases coming as a consequence of unifying features within the Bethe Ansatz. |
Braneworld cosmology and varying G ; We consider a braneworld cosmological model coupled to a bulk scalar field. Since the brane tension turns out to be proportional to Newton coupling G, in such a model a time variation of G naturally occurs. By resorting to available bounds on the variation of G, the parameters of the model are constrained. The constraints coming from nucleosynthesis and CMB result to be the severest ones. |
The motion of galaxy clusters in inhomogeneous cosmologies ; LemaitreTolmanBondi inhomogeneous spacetimes can be used as a cosmological model to account for the type Ia supernova data. However, such models also give rise to large velocities of galaxy clusters with respect to the cosmic microwave background. Those velocities can be measured using the kinematic SunyaevZeldovich effect. This paper presents a calculation of galaxy cluster velocities as a function of redshift for such a model. |
Subleading asymptotic behaviour of area correlations in the BarrettCrane model ; The BarrettCrane spin foam model for quantum gravity provides an excellent setting for testing analytical and numerical tools used to probe spinfoam models. Here, we complete the report on the numerical analysis of the single 4simplex area correlations begun in Phys. Lett. B670 2009 403406, discussing the nexttoleading order corrections oneloop corrections with particular attention to their measure dependence, and the difference between the Gaussian and Bessel ansatze for the boundary state. |
Granulation across the HR diagram ; We have obtained ultrahigh quality spectra R180,000; SN300 with unprecedented wavelength coverage 4400 to 7400 A for a number of stars covering most of the HR diagram in order to test the predictions of models of stellar surface convection. Line bisectors and core wavelength shifts are both measured and modeled, allowing us to validate andor reveal the limitations of stateoftheart hydrodynamic model atmospheres of different stellar parameters. We show the status of our project and preliminary results. |
Crossing the Phantom divide line in the Chaplygin gas model ; The role of the interaction in reaching and crossing the phantom divide line in the Chaplygin gas model is discussed. We obtain some necessary properties of the interaction that allow the model to arrive at or cross the phantom divide line. We show that these properties put some conditions on the ratio of dark matter to dark energy density in the present epoch. |
Axially Symmetric Cosmological Mesonic Stiff Fluid Models in Lyra's Geometry ; In this paper, we obtained a new class of axially symmetric cosmological mesonic stiff fluid models in the context of Lyra's geometry. Expressions for the energy, pressure and the massless scalar field are derived by considering the time dependent displacement field. We found that the mesonic scalar field depends on only t coordinate. Some physical properties of the obtained models are discussed. |
Asymptotic analysis of the PonzanoRegge model for handlebodies ; Using the coherent state techniques developed for the analysis of the EPRL model we give the asymptotic formula for the PonzanoRegge model amplitude for nontardis triangulations of handlebodies in the limit of large boundary spins. The formula produces a sum over all possible immersions of the boundary triangulation and its value is given by the cosine of the Regge action evaluated on these. Furthermore the asymptotic scaling registers the existence of flexible immersions. We verify numerically that this formula approximates the 6jsymbol for large spins. |
Utility Function and Optimum Consumption in the models with Habit Formation and Catching up with the Joneses ; This paper analyzes popular timenonseparable utility functions that describe habit formation consumer preferences comparing current consumption with the time averaged past consumption of the same individual and catching up with the Joneses CuJ models comparing individual consumption with a crosssectional average consumption level. Few of these models give reasonable optimum consumption time series. We introduce theoretically justified utility specifications leading to a plausible consumption behavior to show that habit formation preferences must be described by a power CRRA utility function different from the exponential CARA used for CuJ. |
FRW Cosmology with Variable G and Lambda ; We have considered a cosmological model of the FRW universe with variable G and Lambda. The solutions have been obtained for flat model with particular form of cosmological constant. The cosmological parameters have also been obtained for dust, radiation and stiff matter. The statefinder parameters are analyzed and have shown that these depends only on w and epsilon. Further the lookback time, proper distance, luminosity distance and angular diameter distance have also been calculated for our model. |
Nonparametric estimation of covariance functions by model selection ; We propose a model selection approach for covariance estimation of a multidimensional stochastic process. Under very general assumptions, observing i.i.d replications of the process at fixed observation points, we construct an estimator of the covariance function by expanding the process onto a collection of basis functions. We study the non asymptotic property of this estimate and give a tractable way of selecting the best estimator among a possible set of candidates. The optimality of the procedure is proved via an oracle inequality which warrants that the best model is selected. |