Cone Wave Research Articles

Basic properties of free stratified flows

Results of analytical studies of the governing equations of stratified rotating fluids based on the unification of theories of continuous and discrete groups, perturbations and modern numerical visualizations are described. Symmetries of basic systems and their simplified versions, different approximations and constitutive turbulent models are compared. A new method to calculate discrete groups analytically, which does not need a preliminary search for continuous groups, is developed. As an example of the practical use of the developed algorithm, a complete classification of cellular and roll structures of Benard convection is presented. A complete classification of 3D periodic motions in compressible viscous stratified and rotating fluids, including regular (wave) and singular elements, is performed by perturbation methods. In all cases, in a viscous fluid, besides waves there are two different periodic boundary layers. In a homogeneous fluid the split boundary layers are merged, thus forming a joint doubly-degenerate structure. Stratification and rotation reduce the degeneration of the 3D periodic boundary layers. Calculations of a 3D periodic wave beam emitted by an oscillating part of a sloping plane are visualized by a computer-graphics method. The existence of thin extended components on the edges of the 3D wave cone is demonstrated.

Self-action of Bessel light beams in cubic gyrotropic photorefractive crystals

We have studied conversion and interaction of a Bessel laser beam of zero order in photorefractive crystals. We have established that in a cubic gyrotropic crystal, two Bessel light beams propagate with different wave vectors and cone angles, but with identical conicity parameters. As the power in the Bessel light beam increases, we have experimentally observed a new optical effect: self-action of a Bessel light beam. We have studied the effect of external influences and the parameters of the beam itself on the process of self-refraction in photorefractive crystals.

Magnetic excitations of stripes and checkerboards in the cuprates

We discuss the magnetic excitations of well-ordered stripe and checkerboard phases, including the high energy magnetic excitations of recent interest and possible connections to the "resonance peak" in cuprate superconductors. Using a suitably parametrized Heisenberg model and spin wave theory, we study a variety of magnetically ordered configurations, including vertical and diagonal site- and bond-centered stripes and simple checkerboards. We calculate the expected neutron scattering intensities as a function of energy and momentum. At zero frequency, the satellite peaks of even square-wave stripes are suppressed by as much as a factor of 34 below the intensity of the main incommensurate peaks. We further find that at low energy, spin wave cones may not always be resolvable experimentally. Rather, the intensity as a function of position around the cone depends strongly on the coupling across the stripe domain walls. At intermediate energy, we find a saddlepoint at $(\pi,\pi)$ for a range of couplings, and discuss its possible connection to the "resonance peak" observed in neutron scattering experiments on cuprate superconductors. At high energy, various structures are possible as a function of coupling strength and configuration, including a high energy square-shaped continuum originally attributed to the quantum excitations of spin ladders. On the other hand, we find that simple checkerboard patterns are inconsistent with experimental results from neutron scattering.

E141 電場を付与したシリコーン油-水界面の挙動(界面・相変化・熱物性とその応用2)

The effect of the electric field on the horizontal interface of water and silicone oil is studied experimentally. The negative electrode is installed in water, and the positive one is in the oil, and dc high voltage is applied between the electrodes. The circular cone waves with sharp tip are formed on the interface that became unstable by the electric field. In a high voltage, the drops of water generate from each tip of the wave. The phenomena are taken with a high-speed video camera, and analyzed.

Generalized parton distributions in the impact parameter space with nonzero skewedness

We investigate the generalized parton distributions (GPDs) with non-zero $\xi$ and $\Delta^\perp$ for a relativistic spin-1/2 composite system, namely for an electron dressed with a photon, in light-front framework by expressing them in terms of overlaps of light-cone wave functions. The wave function provides a template for the quark spin-one diquark structure of the valence light cone wave function of the proton. We verify the inequalities among the GPDs with different helicities and show the qualitative behaviour of the fermion and gauge boson GPDs in the impact parameter space.

Photopigment coexpression in mammals: comparative and developmental aspects.

In mammals, each cone had been thought to contain only one single type of photopigment. It was not until the early 1990s that photopigment coexpression was reported. In the house mouse, the distribution of color cones shows a characteristic division. Whereas in the upper retinal field the ratio of short wave to middle-to-long wave cones falls in the usual range (1:10), in the ventral retinal field M/L-pigment expression is completely missing. In the transitional zone, numerous dual cones are detectable (spatial coexpression). In other species without retinal division, dual cones appear during development, suggesting that M/L-cones develop from S-cones. Dual elements represent a transitory stage in M/L-cone differentiation that disappear with maturation (transitory coexpression). These two phenomena seem to be mutually exclusive in the species studied so far. In the comparative part of this report the retinal cone distribution of eight rodent species is reported. In two species dual cones appear in adult specimens without retinal division, and dual elements either occupy the dorsal peripheral retina, or make up the entire cone population. This is the first observation proving that all cones of a retina are of dual nature. These species are good models for the study of molecular control of opsin expression and renders them suitable sources of dual cones for investigations on the role and neural connections of this peculiar cone type. In the developmental part, the retinal maturation of other species is examined to test the hypothesis of transitory coexpression. In these species S-pigment expression precedes that of the M/L-pigment, but dual cones are either identified in a small number or they are completely missing from the developing retina. These results exclude a common mechanism for M/L-cone maturation: they either transdifferentiate from S-cones or develop independently.

Particle simulation of Alfvén waves excited at a boundary

A particle-in-cell (PIC) code has been developed that is capable of describing the propagation of compressional and shear Alfvén waves excited from a boundary. The code is used to elucidate the properties of Alfvén wave cones radiated from sources having transverse scale comparable to the electron skin depth. Good agreement between theoretical predictions and simulation results is found over a wide range of frequencies. An investigation has been undertaken of the effect of hot ions on the Alfvén wave cones. The PIC simulations demonstrate that as the ion temperature is increased there is a reversal in the cone angle. The reversal implies that there is a cross-field focusing of the shear Alfvén waves. This is a feature which is presently being considered in studies of field-line resonances in the earth’s magnetic field. The PIC results also illustrate the damping of shear modes due to the Doppler-shifted cyclotron resonance with hot ions.

Light mesons on the light front

We study the properties of light mesons in the scalar, pseudoscalar, and vector channels within the light-front quantization, by using the (one flavor) Nambu-Jona-Lasinio model with vector interaction. After taking into account the effects of chiral symmetry breaking, we derive the bound-state equation in each channel in the large $N$ limit ($N$ is the number of colors), which means that we consider the lowest $q\overline{q}$ Fock state with the constituent quark and antiquark. By solving the bound-state equation, we simultaneously obtain a mass and a light cone (LC) wave function of the meson. While we reproduce the previous results for the scalar and pseudoscalar mesons, we find that, for a vector meson, the bound-state equations for the transverse and longitudinal polarizations look different from each other. However, eventually after imposing a cutoff which is invariant under the parity and boost transformations, one finds these two are identical, giving the same mass and the same (spin-independent) LC wave function. When the vector interaction becomes larger than a critical value, the vector state forms a bound state, whose mass decreases as the interaction becomes stronger. While the LC wave function of the pseudoscalar meson is broadly distributed in longitudinal momentum ($x$) space, that of the vector meson is squeezed around $x=1/2$.

Validation of a Source–Receiver Model for Road Traffic-Induced Vibrations in Buildings. I: Source Model

This work focuses on the coupling of a validated source model for free field traffic-induced vibrations to a receiver model that enables one to predict the response of buildings, accounting for dynamic soil-structure interaction. The resulting model is validated by means of in situ measurements, that have been performed in and around a single-family dwelling during the passage of a truck with known characteristics at speeds between 23 km/h and 58 km/h on joints between plates of the concrete pavement and on a plywood unevenness installed on the road. Simultaneous vibration measurements have been performed with a mobile data acquisition system on the truck's axles. The objective of part I of this paper is to present the validation of the source model. The characteristics of the vehicle and the road unevenness are discussed, and the vehicle response is validated. The response is independent of the vehicle speed for the passage on the joints, whereas, for the passage on the plywood unevenness, the vibrations increase with the vehicle speed. The dynamic road-soil interaction problem is subsequently solved. Special consideration is given to the determination of the dynamic soil characteristics using the spectral analysis surface wave and seismic cone penetration test methods and to the validation of the transfer functions in the soil. The free-field incident wave field is finally validated. This incident wave field is used in part II of the paper to predict and validate the response of the single family dwelling.

Spin waves in striped phases

In many antiferromagnetic, quasi-two-dimensional materials, doping with holes leads to ``stripe'' phases, in which the holes congregate along antiphase domain walls in the otherwise antiferromagnetic texture. Using a suitably parametrized two-dimensional Heisenberg model on a square lattice, we study the spin wave spectra of well-ordered spin stripes, comparing bond-centered antiphase domain walls to site-centered antiphase domain walls for a range of spacings between the stripes and for stripes both aligned with the lattice (``vertical'') and oriented along the diagonals of the lattice (``diagonal''). Our results establish that there are qualitative differences between the expected neutron scattering responses for the bond-centered and site-centered cases. In particular, bond-centered stripes of odd spacing generically exhibit more elastic peaks than their site-centered counterparts. For inelastic scattering, we find that bond-centered stripes produce more spin wave bands than site-centered stripes of the same spacing and that bond-centered stripes produce rather isotropic low energy spin wave cones for a large range of parameters, despite local microscopic anisotropy. We find that extra scattering intensity due to the crossing of spin wave modes (which may be linked to the ``resonance peak'' in the cuprates) is more likely for diagonal stripes, whether site- or bond-centered, whereas spin wave bands generically repel, rather than cross, when stripes are vertical.

Transitions from electrostatic to electromagnetic whistler wave excitation

At frequencies below the electron cyclotron and above the lower hybrid frequency in a magnetoplasma, the refractive index is anisotropic and shows resonances at certain angles caused by electron inertia. For a radiating antenna in a plasma, the short wavelengths near this resonance angle may contribute to the radiation pattern of the antenna. A series of experiments is reported, in which waves were excited using a small 1-cm-diam electrostatically coupled antenna into a preformed plasma, densities (ne) from 1015 to 1018 m−3 and magnetic fields from 30 to 60 G. Maps of the wave amplitude and phase were made within the plasma by scanning the position of a b-dot probe. At low densities (e.g., ne<5×1016 m−3 at 50 G and 3 mTorr), a single amplitude maximum along the group velocity resonance cone angle was measured that decayed as the distance from the antenna increased. The observed radiation pattern in all cases was consistent with that of a point source in an unbounded plasma, and no global eigenmode resonances were found. As the density was increased, the apparent attenuation of the resonance cone waves increased and they appeared to withdraw into the antenna. At high densities (ne>5×1016 m−3) the radiation pattern was characterized by a monotonic increase in wave phase in the axial direction, a central maximum for Bz, and off-axis maxima for Bx and By which are consistent with the propagation of m=0 helicon waves, and no evidence of resonance cone structure. This change in the radiation pattern is reproduced numerically in a homogeneous plasma model including an electrostatically coupled antenna with the same geometry as that used in the experiment.

2004 REVIEW OF LIGHT CONE FIELD THEORY

We review the basic concepts of the Poincare group in light cone quantum mechanics and light cone field theory. We discuss recent progress in light cone representations of the Bethe–Salpeter equation, with application to the pion form factor, and the quark Schwinger–Dyson equation. Applications are discussed for deeply virtual Compton scattering, particularly for skewed parton distributions of the pion, and rare B to lepton pair decays. Meson light cone wave functions and recent experimental studies of light cone wave functions are also covered. This review was motivated by the LANL Light Cone 2002 International Workshop.

A new membrane model for the ballistic impact response and V50 performance of multi-ply fibrous systems

This paper develops an analytical model for the ballistic impact response of fibrous materials of interest in body armor applications. It focuses on an un-tensioned 2D membrane impacted transversely by a blunt-nosed projectile, a problem that has remained unsolved for a half a century. Membrane properties are assumed characteristic of the best current body armor materials (Kevlar ®, Spectra ®, Zylon ®, S2 glass), which have very high stiffness and strength per unit weight, and low strain-to-failure. Successful comparisons will be made with extensive experimental data on such material systems as reported by Cunniff [Decoupled response of textile body armor. Proc. 18th Int. Symp. of Ballistics, San Antonio, Texas, 1999a, pp. 814–821; V s– V r relationships in textile system impact. Proc. 18th Int. Symp. of Ballistics, San Antonio, Texas, 1999b; Dimensional parameters for optimization of textile-based body armor systems, Proc. 18th Int. Symp. of Ballistics, San Antonio, Texas, 1999c, pp. 1303–1310]. Our mathematical formulation draws on the seminal work of Rakhmatulin and Dem’yanov [Strength Under High Transient Loads, 1961, pp. 94–152]. Under constant projectile velocity we first develop self-similar solution forms for the tensile ‘implosion’ wave and the curved cone wave that develops in its wake. Through matching boundary conditions at the cone wave front, we obtain an accurate approximate solution for the membrane response including cone wave speed and strain distribution. We then consider projectile deceleration due to membrane reactive forces, and obtain results on cone velocity, displacement and strain concentration versus time. Other results obtained are the membrane ballistic limit, or V 50 velocity, and the residual velocity when penetrated above this limit. We then derive an exact functional representation of a V 50 ‘master curve’ found empirically by Cunniff [ibid] to reduce data for a wide variety of fabric systems impacted by blunt cylindrical projectiles. This curve is given in terms two dimensionless parameters based only on fiber mechanical properties and the ratio of the fabric areal density to the projectile mass divided by its area of fabric contact. Our functional representation has no fitting parameters beyond one reflecting uncertainty in the effective diameter of the impact zone relative to the projectile diameter, and even then the values are consistent across several experimental systems. The extremely successful comparison of our analytical model to experimental results in the literature raises fundamental questions about many long-held views on fabric system impact behavior and parameters thought to be important.

Nonperturbative QCD treatment of $J/\Psi$ photoproduction

We present a nonperturbative QCD calculation of elastic $J/\psi$ meson production in photon-proton scattering at high energies. Using light cone wave functions of the photon and vector mesons, and the framework of the model of the stochastic QCD vacuum, we calculate the differential and integrated elastic cross sections for $\gamma p \goto J/\psi p $ . With an energy dependence following the two-pomeron model we are able to give a consistent description of the integrated cross sections and the differential cross sections at low $|t|$ in the range from 20 GeV up to the highest HERA energies. We discuss different approaches to introduce saturation and find no specific effects up to energies presently available. We also calculate and compare to experiments the cross section for $\upsilon$ photoproduction.

The second moment of the pion light cone wave function

We present a preliminary result for second moment of the light cone wave function of the pion. This parameter is the subject of a discrepancy between theoretical predictions (coming from lattice and sum rules) and a recent experimental result (that remarkably agrees with purely perturbative predictions). In this work we exploit lattice hypercubic symmetries to remove power divergences and, moreover, implement a full 1-loop matching for all the contributing operators.

The generation of beams of three-dimensional periodic internal waves in an exponentially stratified fluid

The spectral method is used to construct an exact solution of the linearized problem of the generation of disturbances by localized sources that execute arbitrary periodic motions in a viscous exponentially stratified fluid. The expressions obtained do not contain any adjusting parameters and describe conical beams of three-dimensional periodic internal waves and two types of boundary layers, the spatial scale of which is given by the kinematic viscosity and the buoyancy frequency of the medium. The thickness of one of them, which is analogous to Stokes periodic flow in a homogeneous viscous fluid, is specified by the kinematic viscosity and the wave frequency, that is, it additionally depends on a ratio of the wave and buoyancy frequencies. The thickness of the specific internal boundary layer also depends on the geometry of the problem. In the approximation of weak stratification and low viscosity, asymptotic estimates of the expressions obtained are presented for two types of generators, namely, in the form of a plane inclined rectangle that vibrates along its surface (a frictional source) and along the normal to it (a piston source) in the non-degenerate case when the wave cone does not touch the radiating plane. In limiting cases the analytical expressions obtained agree with known exact solutions of the problem of generating axially symmetric and two-dimensional periodic internal waves.

QCD condensates and the pion wave functions in the nonlocal chiral model

We use the simple instanton motivated Nambu--Jona-Lasinio--type model to calculate a twist 3 pseudoscalar pion light cone wave function ${\ensuremath{\psi}}_{\ensuremath{\pi}}^{\mathrm{PS}}.$ Using the normalization condition for ${\ensuremath{\psi}}_{\ensuremath{\pi}}^{\mathrm{PS}}$ we calculate the quark condensate and also the gluon condensate, which agree with the phenomenological values for these quantities. Since we can compute also the ${k}_{T}^{2}$ dependence of the light cone wave functions, we calculate ${k}_{T}^{2}$ moments of the pseudoscalar and axial-vector wave functions which are related to the mixed vacuum condensates. This allows us to extract the condensates and compare them with existing estimates.

Anisotropic plasma crystal solitons.

An analytical two-dimensional model for weakly dispersive and weakly nonlinear longitudinal and transverse shear waves propagating in an ideal two-dimensional hexagonal Yukawa crystal is presented. The model takes into account the nonlinear terms up to the third order. Both compressional and shear soliton solutions are found in the long-wavelength approximation. It is shown that the compressional solitons are always supersonic and weakly anisotropic. The shear solitons, on the other hand, exhibit strong anisotropy and can be both subsonic and supersonic, depending on the direction of propagation. In the model, shear solitons cannot propagate along the main axes. The role of weak damping as well as formation of multiple solitons is analyzed. The results are discussed in connection with wave and Mach cone experiments in a monolayer hexagonal plasma crystal, and a diagnostic method is proposed to measure both the charge of the microparticles and the lattice parameter.

Evolution of electron beam generated waves resulting in transverse ion heating and filamentation of the plasma

We present here a systematic simulational study on electron beam driven waves and their consequences in terms of plasma electrodynamics. The study is performed by using three‐dimensional particle‐in‐cell code, parallelized to simulate a large volume of plasma. Our simulation shows that an initial electron beam of finite radius with beam velocity along the ambient magnetic field triggers a series of events in the evolution of the waves and the plasma. In the initial stage (t ≤ 200 ωpo−1, ωpo being the electron plasma frequency with the total electron density n0), high frequency waves near ω ∼ ωpo are driven. These waves progressively disappear giving way to the dominance of lower hybrid (LH) waves. The phase of the lower hybrid waves lasts over the time interval . In this time period the LH waves stochastically accelerate ions transverse to B0, and the beam electrons are scattered outside the initial beam volume to occupy the entire volume of the simulation plasma. The ion acceleration leads to the formation of elongated tail in the perpendicular velocity distribution. The large‐amplitude LH waves are seen to undergo a parametric decay into resonance cone waves at frequencies ω < Ωi, the ion cyclotron frequency. Such extremely low‐frequency (ELF) waves are the electrostatic version of the inertial Alfven waves. The phase of the strong LH waves is followed by a stage in which HF waves with frequencies ω ∼ ωpo appear again, but in this stage they are strongly modulated by the already present ELF waves and other low‐frequency waves in the frequency range near the ion cyclotron frequency Ωi and its harmonics. Beginning with the LH wave stage and continuing into the late stages of ELF waves, the plasma density is highly filamented and the filaments oscillate with the ELF frequencies. The relevance of our results to the observations on plasma waves from satellites is brought out.

Pion light cone wave function in the nonlocal NJL model

We use the simple instanton motivated NJL-type model to calculate the leading twist pion light cone wave function. The model consists in employing the momentum dependent quark mass in the quark loop entering the definition of the wave function. The result is analytical up to a solution of a certain algebraic equation. Various properties including the ${k}_{T}$ dependence of the pion wave function are discussed. The resulting ${k}_{T}$ integrated wave function is not asymptotic and is in agreement with recent analysis of the CLEO data.