January 1998 arXiv papers — page 13

Y. Itoh, M. Hotta, M. Morikawa, T. Futamase

We investigate dynamical instability of a two-dimensional quantum black hole model considered by Lowe in his study of Hawking evaporation. The model is supposed to express a black hole in equilibrium with a bath of Hawking radiation. It turns out that the model has at least one instability modes for a wide range of parameters, and thus it is unstable.

T. Futamase, M. Hotta, Y. Itoh

We study the conditions for 2-dimensional dilaton gravity models to have dynamical formation of black holes and construct all such models. Furthermore we present a parametric representation of the general solutions of the black holes.

Patrick R. Brady, Ian G. Moss, Robert C. Myers

Spacetimes which have been considered counter-examples to strong cosmic censorship are revisited. We demonstrate the classical instability of the Cauchy horizon inside charged black holes embedded in de Sitter spacetime for all values of the physical parameters. The relevant modes which maintain the instability, in the regime which was previously considered

C. Wolverton, Alex Zunger

Using a combination of first-principles total energies, a cluster expansion technique, and Monte Carlo simulations, we have studied the Li/Co ordering in LiCoO_2 and Li-vacancy/Co ordering in CoO_2. We find: (i) A ground state search of the space of substitutional cation configurations yields the (layered) CuPt structure as the lowest-energy state in the oct

J. Ferrer, J. Sánchez-Cañizares, M. A. González-Alvarez

We study an extended Hubbard model with on-site repulsion and nearest neighbors attraction which tries to mimic some of the experimental features of doped cuprates in the superconducting state. We draw and discuss the phase diagram as a function of the effective interactions among electrons for a wide range of doping concentrations. We locate the region whic

W. Belzig, C. Bruder, M. Sigrist

We investigate the electronic structure of twin boundaries in orthorhombically distorted high-T$_c$ materials using the quasiclassical theory of superconductivity. At low temperatures we find a local instability to a time-reversal symmetry breaking state at the twin boundary. This state yields spontaneous currents along the twin boundary that are microscopic

Jean Desbois, Stephane Ouvry, Christophe Texier

Persistent currents and magnetization are considered for a two-dimensional electron (or gas of electrons) coupled to various magnetic fields. Thermodynamic formulae for the magnetization and the persistent current are established and the ``classical'' relationship between current and magnetization is shown to hold for systems invariant both by transl

C. Kuebert, P. J. Hirschfeld

We calculate the magnetic field dependence of quasiparticle transport properties in the vortex state of a d-wave superconductor arising solely from the quasiparticle's Doppler shift in the superflow field surrounding the vortex. Qualitative features agree well with experiments on cuprate and heavy fermion superconductors at low fields and temperatures. W

K. Mussawisade, J. E. Santos, G. M. Schütz, ;

We derive a self-duality relation for a one-dimensional model of branching and annihilating random walkers with an even number of offsprings. With the duality relation and by deriving exact results in some limiting cases involving fast diffusion we obtain new information on the location and nature of the phase transition line between an active stationary sta

G. M. Schütz, K. Mussawisade

We study diffusion-limited pair annihilation $A+A\to 0$ on one-dimensional lattices with inhomogeneous nearest neighbour hopping in the limit of infinite reaction rate. We obtain a simple exact expression for the particle concentration $ρ_k(t)$ of the many-particle system in terms of the conditional probabilities $P(m;t|l;0)$ for a single random walker in a

Cristian F. Moukarzel

A matching algorithm for the identification of backbones in percolation problems is introduced. Using this procedure, percolation backbones are studied in two- to five-dimensional systems containing 1.7x10^7 sites, two orders of magnitude larger than was previously possible using burning algorithms.

Hideki Kamegawa, Tsuyoshi Hondou, Fumiko Takagi

Molecular motors are known to have the high efficiency of energy transformation in the presence of thermal fluctuation. Motivated by the surprising fact, recent studies of thermal ratchet models are showing how and when work should be extracted from non-equilibrium fluctuations. One of the important finding was brought by Magnasco where he studied the temper

G. Montambaux, D. Zanchi

The theory and experiments showing Quantum Hall effect in the quasi-one-dimensional conductors of the Bechgaard salts family are briefly reviewed. The sign reversals observed under some experimental conditions are explained within the framework of the Quantized Nesting Model. The sequence of reversals is driven by slight modifications of the geometry of the

A. Pelissetto, E. Vicari

We consider the effective potential in three-dimensional models with O(N) symmetry. For generic values of N, and in particular for the physically interesting cases N=0,1,2,3, we determine the six-point and eight-point renormalized coupling constants which parametrize its small-field expansion. These estimates are obtained from the analysis of their $ε$-expan

V. I. Yukalov, E. P. Yukalova

Electric current in semiconductors is considered as a function of time. Nonequilibrium fluctuations of the current are studied for strongly nonuniform samples. It is demonstrated that at special conditions the total electric current through a device can exhibit a negative fluctuation, when the current is directed against the applied voltage.

Yuli Lyanda-Geller

Transport and thermodynamic properties of disordered conductors are considerably modified when the angle through which the electron spin precesses due to spin-orbit interaction (SOI) during the mean free time becomes significant. Cooperon and Diffusion equations are solved for the entire range of strength of SOI. The implications of SOI for the electron-elec

Masahiko Hayashi

The spectral flow in the cores of moving dislocations is found to play an important role in the dynamics and transport of charge density wave (CDW) by significantly modifying the hydrodynamic effective action of the condensate. The analogy of spectral flow in CDW with the baryogenesis in the early universe is pointed out.

H. Koizumi, T. Hotta, Y. Takada

The effect of the Berry phase is included explicitly in the wavefunction describing conduction electrons in a crystal composed of periodically arrayed Jahn-Teller centers that have conically intersecting potential energy surfaces. The Berry phase can make a drastic change in the band structure, leading generally to the formation of an orbital-density-wave st

D. Simonian, S. V. Kravchenko, M. P. Sarachik, V. M. Pudalov

For an electron density near the H=0 insulator-to-conductor transition, the magnetoconductivity of the low-temperature conducting phase in high-mobility silicon MOSFETs is consistent with the form $Δσ(H_{||},T)\equivσ(H_{||},T)-σ(0,T) = f(H_{||}/T)$ for magnetic fields $H_{||}$ applied parallel to the plane of the electron system. This sets a valuable constr

J. R. Dorfman, Arnulf Latz, Henk van Beijeren

We consider a general method for computing the sum of positive Lyapunov exponents for moderately dense gases. This method is based upon hierarchy techniques used previously to derive the generalized Boltzmann equation for the time dependent spatial and velocity distribution functions for such systems. We extend the variables in the generalized Boltzmann equa

M. Falcioni, D. Vergni, A. Vulpiani

We introduce a ``spatial'' Lyapunov exponent to characterize the complex behavior of non chaotic but convectively unstable flow systems. This complexity is of spatial type and is due to sensitivity to the boundary conditions. We show that there exists a relation between the spatial-complexity index we define and the comoving Lyapunov exponents. In th

D. Dobrzycka, A. Dobrzycki, D. Engels, H. -J. Hagen

We present the analysis of the spectroscopic observations of a newly discovered cataclysmic variable HS0551+7241. In 1995 the star's brightness dropped by Delta(B)~2.5 mag and HS0551+7241 entered a low state lasting for ~2 yr. The H-alpha, H-beta and HeII(4686) emission line radial velocity curves show evidence of short ~50 min fluctuations superimposed

Andrew W. Blain

The intensity of the cosmic microwave background radiation in the fields of clusters of galaxies is modified by inverse Compton scattering in the hot intracluster gas - the Sunyaev-Zel'dovich (SZ) effect. The effect is expected to be most pronounced at a frequency of about 350 GHz (a wavelength of about 800 microns), and has been detected in the centimet

Andrew W. Blain

An extremely sensitive all-sky survey will be carried out in the millimetre/submillimetre waveband by the forthcoming ESA mission Planck Surveyor. The main scientific goal of the mission is to make very accurate measurements of the spatial power spectrum of primordial anisotropies in the cosmic microwave background radiation; however, hundreds of thousands o

D. R. Lorimer, A. Jessner, J. H. Seiradakis, A. G. Lyne

We describe a data format currently in use amongst European institutions for exchanging and archiving pulsar data. The format is designed to be as flexible as possible with regard to present and future compatibility with different operating systems. One application of the common format is simultaneous multi-frequency observations of single pulses. A data arc

D. R. Lorimer, A. G. Lyne, F. Camilo

We have carried out a sensitive search for young pulsars associated with supernova remnants using the 76-m Lovell radio telescope at Jodrell Bank. The observations were made at 606 MHz using a system with a bandwidth of 8 MHz and a set noise temperature on cold sky of about 50 K. The survey targeted 33 remnants in the northern hemisphere and achieved a nomin

Rene D. Oudmaijer, Martin A. T. Groenewegen, Hans Schrijver

The theoretical prediction that trigonometric parallaxes suffer from a statistical effect, has become topical again now that the results of the Hipparcos satellite have become available. This statistical effect, the so-called Lutz-Kelker bias, causes measured parallaxes to be too large. This has the implication that inferred distances, and hence inferred lum

G. Puehlhofer, A. Daum, G. Hermann, M. Hess

Stereoscopic viewing of TeV gamma-ray air showers with systems of Imaging Atmospheric Cherenkov Telescopes (IACTs) allows to reconstruct the origin of individual primary particles with an accuracy of 0.1 degree or better. The shower impact point can be determined within 15 meters. To actually achieve this resolution, the pointing of the telescopes of an IACT

D. R. Lorimer

The study of pulsars has come a long way since their accidental discovery as ``scruff'' on pen chart recordings of the radio sky at 81 MHz by Jocelyn Bell and Anthony Hewish at Cambridge some thirty years ago. The present sample of almost 800 objects is the result of an immense amount of observing time at the largest radio telescopes around the world

S. J. Hardy, D. B. Melrose

A standard version of a kinetic instability for the generation of Langmuir waves by a beam of electrons is adapted to describe the analogous instability due to a beam of neutrinos. The interaction between a Langmuir wave and a neutrino is treated in the one-loop approximation to lowest order in an expansion in $1/M_W^2$ in the standard electroweak model. It

Peter Berczik, Sergei G. Kravchuk

The evolving galaxy is considered as a system of baryonic fragments embedded into the static dark nonbaryonic (DH) and baryonic (BH) halo and subjected to gravitational and viscous interactions. Though the chemical evolution of each fragment is treated in the frame of one -- zone model with instantaneous recycling, the local gas density and, therefore, its s

Mark W. Sincell

We calculate the amplitude of the Lyman discontinuity for an accretion disk around a maximally rotating black hole. The locally emitted disk spectrum is computed with a previously developed numerical model (Sincell and Krolik 1998) and then a new general relativistic ray-tracing code is used to determine the observed spectra as a function of inclination angl

Andrea Ferrara, Simone Marri

We review some of the possible observable effects (reionization, feedback on galaxy formation, supernovae and metal enrichment) of the first collapsed, luminous (Pop III) objects in the universe. We show that supernovae in these objects should be considerably magnified by the intervening cosmological matter distribution; the implications of this process are

Heino Falcke, Andrew S. Wilson, Chris Simpson

We present HST/WFPC2 images, in narrow-band filters containing the [OIII] lambda5007 and Halpha+[NII] emission-lines and their adjacent continua, of a sample of seven Seyfert 2 galaxies selected on the basis of possessing either extended emission-line regions in ground-based observations or a hidden broad-line region in polarized light. Six of the galaxies h

Heino Falcke, W. M. Goss, Hiroshi Matsuo, Peter Teuben

We report results from a multiwavelength campaign to measure the simultaneous spectrum of the super-massive black hole candidate Sgr A* in the Galactic Center from cm to mm-wavelengths using the VLA, BIMA, the Nobeyama 45m, and the IRAM 30m telescopes. The observations confirm that the previously detected mm-excess is an intrinsic feature of the spectrum of

H. Saio, K. Nomoto

We have investigated the consequences of merging double white dwarf systems by calculating evolutionary models of accreting white dwarfs. We have considered two cases; a massive C-O white dwarf of ~1M_sun accreting C-O mixture, and a low mass white dwarf with an initial mass of 0.4M_sun accreting matter composed mostly of helium. The accretion rate of the C-

Wendy L. Freedman, Jeremy R. Mould, Robert C. Kennicutt, Barry F. Madore

A review of the Hubble Space Telescope H0 Key Project is given, as presented at the IAU Symposium 183 on "Cosmological Parameters" held in Kyoto, Japan in August, 1997. An outline of the goals and progress toward this effort is given. Cepheid distances to over a dozen galaxies have now been measured using HST. These distances form the basis for the c

Vadim Urpin, Denis Konenkov

We consider the magnetic and spin evolution of isolated neutron stars assuming that the magnetic field is initially confined to the crust. The evolution of the crustal field is determined by the conductive properties of the crust which, in its turn, depend on the thermal history of the neutron star. Due to this fact, a study of the magnetic field decay may b

Alexandre M. Zagoskin

We predict that the mesoscopic tensile force fluctuations in metal quantum point contacts (nanowires) arise as a result of finite electric voltage on the contact. They are due to reconfiguration of the electronic subsystem and are correlated with the nonlinearities of the current-voltage characteristics of the contact. The observation of the effect would dir

Pavel Etingof, Travis Schedler, Alexandre Soloviev

In 1992 V$.$Drinfeld formulated a number of problems in quantum group theory. In particular, he suggested to consider ``set-theoretical'' solutions to the quantum Yang-Baxter equation, i.e. solutions given by a permutation R of the set $X\times X$, where X is a fixed set. In this paper we study such solutions, which in addition satisfy the unitarity

Igor Tsatskis

An explanation of the anomalous concentration dependence of diffuse scattering from the Pt-V alloy system (splitting of the (100) short-range order intensity peak with increasing Pt content) is proposed. The effect is attributed to the competition between the interaction and self-energy curvatures. A similar temperature behaviour is predicted.

C. Bachas, B. Rai, T. N. Tomaras

We establish the existence of a static, classically stable string solution in a region of parameters of the generic two-Higgs Standard Model. In an appropriate limit of parameters, the solution reduces to the well-known soliton of the O(3) non-linear sigma model.

P. Rozmej, R. Arvieu

The aim of this article is to present the interference effects which occur during the time evolution of simple angular wave packets (WP) which can be associated to a diatomic rigid molecule (heteronuclear) or to a quantum rigid body with axial symmetry like a molecule or a nucleus. The time evolution is understood entirely within the frame of fractional revi

Dror Bar-Natan, Stavros Garoufalidis, Lev Rozansky, Dylan Thurston

We continue the work started in part I (q-alg/9706004) and prove the invariance and universality in the class of finite type invariants of the object defined and motivated there, namely the Aarhus integral of rational homology 3-spheres. Our main tool in proving invariance is a translation scheme that translates statements in multi-variable calculus (Gaussia

Xi-Wen Hou, Zhong-Qi Ma

The highly excited stretching vibrational energy levels and the intensities of infrared transitions in tetrahedral molecules are studied in a U(2) algebraic model. Its applications to silane and silicon tetrafluoride are presented with smaller standard deviations than those of other models.

Xi-Wen Hou, Shi-Hai Dong, Mi Xie, Zhong-Qi Ma

Both the stretch and bend vibrational spectrum and the intensity of infrared transitions in a tetrahedral molecule are studied in a U(2) algebraic model, where the spurious states in the model Hamiltonian and the wavefunctions are exactly removed. As an example, we apply the model to silicon tetrafluoride SiF$_4$.

Carlos A. Torre

We define a subcategory of the category of diffeological spaces, which contains smooth manifolds, the diffeomorphism subgroups and its coadjoint orbits. In these spaces we construct a tangent bundle, vector fields and a de Rham cohomology.

Valeri V. Dvoeglazov

Following to the lines drawn in my previous paper about the S=0 relativistic oscillator I build up an oscillatorlike system which can be named as the S=1 Proca oscillator. The Proca field function is obtained in the framework of the Bargmann-Wigner prescription and the interaction is introduced similarly to the S=1/2 Dirac oscillator case regarded by Moshins

N. I. Ussyukina

A method is presented for obtaining the $ε$-expansion for on-shell massless scalar double-box diagram.

Igor Tsatskis

The explanation is presented for the temperature dependence of the fourfold intensity peak splitting found recently in diffuse scattering from the disordered Cu3Au alloy. The wavevector and temperature dependence of the self-energy is identified as the origin of the observed behaviour. Two approaches for the calculation of the self-energy, the high-temperatu

Sascha Hilgenfeldt, Detlef Lohse, Willy Moss

The strong dependence of the intensity of single bubble sonoluminescence (SBSL) on water temperature observed in experiment can be accounted for by the temperature dependence of the material constants of water, most essentially of the viscosity, of the argon solubility in water, and of the vapor pressure. The strong increase of light emission at low water te

Beverly J. Smith

Using the mid-infrared camera (ISOCAM) on the Infrared Space Observatory (ISO), the Sb LINER galaxy NGC 7331 has been imaged in two broadband and four narrowband filters between 6.75 and 15 microns. These maps show a prominent circumnuclear ring of radius 0.25 arcminutes X 0.75 arcminutes (1.1 X 3.3 kpc) encircling an extended central source. The 7.7 and 11.

Adam Burrows, R. F. Sawyer

Including nucleon-nucleon correlations due to both Fermi statistics and nuclear forces, we have developed a general formalism for calculating the neutral-current neutrino-nucleon opacities in nuclear matter. We derive corrections to the dynamic structure factors due to both density and spin correlations and find that neutrino-nucleon cross sections are suppr

Thierry Forveille, Patrick J. Huggins, Rafael Bachiller, Pierre Cox

We report high resolution (2.5 arcsec) CO J=1-0 line imaging which confirms the presence of a molecular disk around the origin of the spectacular, 14 arcmin times 4 arcmin, episodic jets in the planetary nebula KjPn 8. The disk is 30 arcsec in diameter with an expansion velocity of approximately 7 km/s. The axis of the disk is aligned with the youngest and f

László Á. Gergely, Zoltán I. Perjés, Mátyás Vasúth

A convenient formalism for averaging the losses produced by gravitational radiation backreaction over one orbital period was developed in an earlier paper. In the present paper we generalize this formalism to include the case of a closed system composed from two bodies of comparable masses, one of them having the spin S. We employ the equations of motion giv

H. Kleinert, A. Pelster

We draw attention to a novel type of geometric gauge invariance relating the autoparallel equations of motion in different Riemann-Cartan spacetimes with each other. The novelty lies in the fact that the equations of motion are invariant even though the actions are not. As an application we use this gauge transformation to map the action of a spinless point

Xiangdong Ji, Jonathan Osborne

We calculate the one-loop corrections to a general off-forward deeply-virtual Compton process at leading twist for both parton helicity-dependent and independent cases. We show that the infrared divergences can be factorized entirely into off-forward parton distributions, even when one of the two photons is onshell. We argue that this property persists to al

Igor F. Herbut

I study the zero temperature phase transition between superfluid and insulating ground states of the Bose-Hubbard model in a random chemical potential and at large integer average number of particles per site. Duality transformation maps the pure Bose-Hubbard model onto the sine-Gordon theory in one dimension (1D), and onto the three dimensional Higgs electr

Wojciech Florek, Stanislaw Walcerz

In this lecture some mathematical tools necessary for a proper description of the Heisenberg antiferromagnet are presented. We would like to point out differences between ferro- and antiferromagnetic cases of Heisenberg Hamiltonian for finite spin systems. The ground-state properties are discussed.

Kiran M. Kolwankar, Anil D. Gangal

The notion of a local fractional derivative (LFD) was introduced recently for functions of a single variable. LFD was shown to be useful in studying fractional differentiability properties of fractal and multifractal functions. It was demonstrated that the local Holder exponent/ dimension was directly related to the maximum order for which LFD existed. We ha

Urs Bisang, Guenter Ahlers

Measurements of the mean-square amplitude of thermally-induced fluctuations of a thin layer of the nematic liquid crystal I52 subjected to a voltage V < Vc are reported. They yield the limit of stability Vc of the spatially uniform conduction state to infinitesimal perturbations. Localized long-lived convecting structures known as worms form spontaneously fr

Georgia Benkart, José M. Pérez-Izquierdo

Using the natural irreducible 8-dimensional representation and the two spin representations of the quantum group $U_q$(D$_4$) of D$_4$, we construct a quantum analogue of the split octonions and study its properties. We prove that the quantum octonion algebra satisfies the q-Principle of Local Triality and has a nondegenerate bilinear form which satisfies a

William P. Thurston

Geometrization theorem, fibered case: Every three-manifold that fibers over the circle admits a geometric decomposition. Double limit theorem: for any sequence of quasi-Fuchsian groups whose controlling pair of conformal structures tends toward a pair of projectively measured laminations that bind the surface, there is a convergent subsequence. This preprint

Yurii M. Burman

The famous Whitney formula relates the winding number of the smooth generic curve in the real plane to the number of its self-intersection points counted with appropriate signs. We extend this formula to smooth immersions of R^n to R^{2n}. Then use this result together with the general technique of Laplace integrals to get an explicit formula for the generat

Wojciech Florek, Stanislaw Walcerz

Results obtained for the antisymmetric gauge A=[Hy,-Hx]/2 by Brown and Zak are compared with those based on pure group-theoretical considerations and corresponding to the Landau gauge A=[0,Hx]. Imposing the periodic boundary conditions one has to be very careful since the first gauge leads to a factor system which is not normalized. A period N introduced in

A. Sawada, Z. F. Ezawa, H. Ohno, Y. Horikoshi

The Hall-plateau width and the activation energy were measured in the bilayer quantum Hall state at filling factor ν=2, 1 and 2/3, by changing the total electron density and the density ratio in the two quantum wells. Their behavior are remarkably different from one to another. The ν=1 state is found stable over all measured range of the density difference,

M. I. Salkola, J. R. Schrieffer

Nonequilibrium properties of short-coherence-length s-wave superconductors are analyzed in the presence of extrinsic and intrinsic inhomogeneities. In general, the lowest-energy configurations of quasiparticle excitations are topological textures where quasiparticles segregate into antiphase domain walls between superconducting regions whose order-parameter

Jie Liu, Shi-Gang Chen, Bambi Hu

An improved quasistatic model is used to describe the ionization process of atoms in intense linearly polarized fields. Numerical calculations of Above-Threshold-Ionization (ATI) energy spectra and photoelectron angular distributions (PAD) of hydrogen atoms reveal clearly plateau and side lobe structures, which are in good agreement with recent ATI experimen

G. Fasano, S. Cristiani, S. Arnouts, M. Filippi

We present the results of the detailed surface photometry of a sample of early-type galaxies in the Hubble Deep Field. Effective radii, surface brightnesses and total V_606 magnitudes have been obtained, as well as U_300, B_450, I_814, J, H and K colors, which are compared with the predictions of chemical-spectrophotometric models of population synthesis. Sp

Sergey N. Solodukhin

A quantum field described by the field operator $Δ_{a}=Δ+ aδ_Σ$ involving a $δ$-like potential is considered. Mathematically, the treatment of the $δ$-potential is based on the theory of self-adjoint extension of the unperturbed operator $Δ$. We give the general expressions for the resolvent and the heat kernel of the perturbed operator $Δ_{a}$. The main att

S. Groote, J. G. Körner, J. A. Leyva

We consider the effect of gluon radiation on the energy of top/antitop quarks and on the anticollinearity of top-antitop quark pairs produced in $e^+e^-$ annihilation. Our results are presented in terms of the $E_q$-dependence of the $t\bar tg$ cross section and the dependence on the cosine of the opening angle $θ_{12}$ between top and antitop for a center o

R. Argurio, F. Englert, L. Houart

The entropy of the four dimensional Schwarzschild black hole is derived by mapping it onto a configuration of intersecting branes with four charges. This configuration is obtained by performing several boosts and dualities on a neutral black brane of M-theory to which the Schwarzschild black hole is related by trivial compactification. The infinite boost lim

A. V. Belitsky, A. Schaefer

We present results for higher order perturbative corrections to Compton scattering in the generalized Bjorken kinematics. The approach we have used is based on the combination of two techniques: conformal operator product expansion on the one side, and resummation of the fermion vacuum insertions with consequent restoration of the full QCD beta-function via

J. Salas, A. D. Sokal

We study the 3-state square-lattice Potts antiferromagnet at zero temperature by a Monte Carlo simulation using the Wang-Swendsen-Kotecký cluster algorithm, on lattices up to $1024 \times 1024$. We confirm the critical exponents predicted by Burton and Henley based on the height representation of this model.

L. N. Granda, S. D. Odintsov

We study the exact renormalization group (RG) in $R^2$-gravity in the effective average action formalism using the background field method. The truncated evolution equation (where truncation is made to low-derivatives functionals space) for such a theory in a de Sitter background leads to a set of nonperturbative RG equations for cosmological and gravitation

I. H. Inoue, O. Goto, H. Makino, N. E. Hussey

Single crystals of the perovskite-type $3d^{1}$ metallic alloy system Ca$_{1-x}$Sr$_x$VO$_3$ were synthesized in order to investigate metallic properties near the Mott transition. The substitution of a Ca$^{2+}$ ion for a Sr$^{2+}$ ion reduces the band width $W$ due to a buckling of the V-O-V bond angle from $\sim180^\circ$ for SrVO$_3$ to $\sim160^\circ$ fo

Luis J. Garay

An effective model for the spacetime foam is constructed in terms of nonlocal interactions in a classical background. In the weak-coupling approximation, the evolution of the low-energy density matrix is determined by a master equation that predicts loss of quantum coherence. Moreover, spacetime foam can be described by a quantum thermal field that, apart fr

H. Totland, Y. M. Galperin, V. L. Gurevich

We calculate the rate of acoustic phonon generation by a current-carrying, ballistic quantum channel, defined in a two-dimensional electron gas by a split-gate. Both uniform and nonuniform channels are considered. The generation rate of acoustic phonons of a particular frequency and direction of propagation is a steplike function of the applied bias voltage,

V. M. Pudalov, G. Brunthaler, A. Prinz, G. Bauer

We show that the two-dimensional metallic state in Si-MOS samples persists over a wide range of temperatures (16 mK to 8 K), sample peak mobilities (varying by a factor of 8), carrier densities (0.8 to $35\times 10^{11}$ cm$^{-2}$) and conductances from 0.3 to $120 e^2/h$. Our data reveal a failure of the universal one-parameter scaling. We have found a weak

C. Christou, A. Feo, H. Panagopoulos, E. Vicari

We calculate the third coefficient of the lattice beta function associated with the Wilson formulation for both gauge fields and fermions. This allows us to evaluate the three-loop correction (linear in $g_0^2$) to the relation between the lattice Lambda-parameter and the bare coupling $g_0$, which is important in order to verify asymptotic scaling predictio

R. Dick, M. Gaul

Supersymmetric Peccei-Quinn symmetry and string theory predict a complex scalar field comprising a dilaton and an axion. These fields are massless at high energies, but it is known since long that the axion is stabilized in an instanton dominated vacuum. Instantons and axions together also provide a mechanism to stabilize a dilaton, thus accounting for a dil

Igor G. Korepanov

We give a review of some recent work on generalization of the Bethe ansatz in the case of $2+1$-dimensional models of quantum field theory. As such a model, we consider one associated with the tetrahedron equation, i.e. the $2+1$-dimensional generalization of the famous Yang--Baxter equation. We construct some eigenstates of the transfer matrix of that model

Yasusada Nambu, Atsushi Taruya

We investigate gauge invariant cosmological perturbations in a spatially flat Friedman-Robertson-Walker universe with scalar fields. It is well known that the evolution equation for the gauge invariant quantities has exact solutions in the long-wavelength limit. We find that these gauge invariant solutions can be obtained by differentiating the background so

Y. P. Jing, G. Boerner

We study the reliability of the reconstruction method which uses a modelling of the redshift distortions of the two-point correlation function to estimate the pairwise peculiar velocity dispersion of galaxies. In particular, the dependence of this quantity on different models for the infall velocity is examined for the Las Campanas Redshift Survey. We make e

Alon E. Faraggi, Marco Matone

We show that the stationary quantum Hamilton-Jacobi equation of non-relativistic 1D systems, underlying Bohmian mechanics, takes the classical form with $\partial_q$ replaced by $\partial_{\hat q}$ where $d\hat q={dq\over \sqrt{1-β^2}}$. The $β^2$ term essentially coincides with the quantum potential that, like $V-E$, turns out to be proportional to a curvat

Andrey Tsiganov

Some special solutions to the reflection equation are considered. These boundary matrices are defined on the common quantum space with the other operators in the chain. The relations with the Drinfeld twist are discussed.

Mircea Iosifescu

The kinematical constraints of pair operators in nuclear collective motion, pointed out by Yamamura and identified by Nishiyama as relations between so(2n) generators, are recognized as equations satisfied by second-degree annihilators (deduced in previous work) of irreducible so(2n)-modules. The recursion relations for Nishiyama&#39;s tensors and their depe

D. A. Trifonov

It is shown that any two Hamiltonians H(t) and H&#39;(t) of N dimensional quantum systems can be related by means of time-dependent canonical transformations (CT). The dynamical symmetry group of system with Hamiltonian H(t) coincides with the invariance group of H(t). Quadratic Hamiltonians can be diagonalized by means of linear time-dependent CT. The diago

P. Hrasko

The question of the origin of the Gibbs-factorials is reconsidered. It is argued, using the example of the Brownian motion, that their appearance in classical statistical calculations cannot in general be traced back to the symmetry postulate of quantum mechanics as often assumed.

Ruediger Scheibl, Ulrich Heinz

Cluster production in ultrarelativistic heavy ion collision may prove an interesting tool to extract physical quantities of the fireball.

M. Aiello, M. M. Giannini, E. Santopinto

We have calculated the transition form factors for the electromagnetic excitation of the negative parity resonances of the nucleon using different models previously proposed and we discuss their results and limits by comparison with experimental data.

James R. Norris

Sufficient conditions are given for existence and uniqueness in Smoluchowski&#39;s coagulation equation, for a wide class of coagulation kernels and initial mass distributions. An example of non-uniqueness is constructed. The stochastic coalescent is shown to converge weakly to the solution of Smoluchowski&#39;s equation.

Vitali Liskevich, Michael Röckner

Strong and Markov uniqueness problems in $L^2$ for Dirichlet operators on rigged Hilbert spaces are studied. An analytic approach based on a--priori estimates is used. The extension of the problem to the $L^p$-setting is discussed. As a direct application essential self--adjointness and strong uniqueness in $L^p$ is proved for the generator (with initial dom

Michael Röckner, Byron Schmuland

The Dirichlet form associated with the intrinsic gradient on Poisson space is known to be quasi-regular on the complete metric space $\ddotΓ=$ $\{Z_+$-valued Radon measures on $\IR^d\}$. We show that under mild conditions, the set $\ddotΓ\setminusΓ$ is $\e$-exceptional, where $Γ$ is the space of locally finite configurations in $\IR^d$, that is, measures $γ\

Dmitri Zaitsev

For $D$, $D&#39;$ analytic polyhedra in $C^n$, it is proven that a biholomorphic mapping $f\colon D\to D&#39;$ extends holomorphically to a dense boundary subset under certain condition of general position. This result is also extended to a more general class of domains with no smoothness condition on the boundary.

Dmitri Zaitsev

The topic of the paper is the study of germs of local holomorphisms $f$ between $C^n$ and $C^{n&#39;}$ such that $f(M)\subset M&#39;$ and $df(T^cM)=T^cM&#39;$ for $M\subset C^n$ and $M&#39;\subset C^{n&#39;}$ generic real-analytic CR submanifolds of arbitrary codimensions. It is proved that for $M$ minimal and $M&#39;$ finitely nondegenerate, such germs depe

William P. Thurston

This paper develops a theory of Lipschitz comparisons of hyperbolic surfaces analogous to the theory of quasi-conformal comparisons. Extremal Lipschitz maps (minimal stretch maps) and geodesics for the `Lipschitz metric&#39; are constructed. The extremal Lipschitz constant equals the maximum ratio of lengths of measured laminations, which is attained with pr

D. Kaledin, M. Verbitsky

Let $X$ be a hyperkaehler manifold. Trianalytic subvarieties of $X$ are subvarieties which are complex analytic with respect to all complex structures induced by the hyperkaehler structure. Given a 2-dimensional complex torus $T$, the Hilbert scheme $T^{[n]}$ classifying zero-dimensional subschemes of $T$ admits a hyperkaehler structure. A finite cover of $T

Ricardo Schiappa, Rui Dilao

We extend the general solution to the Cauchy problem for the relativistic closed string (Phys. Lett. B404 (1997) 57-65, hep-th/9704084) to the case of open strings attached to Dp-branes, including the cases where the initial data has a knotlike topology. We use this extended solution to derive intrinsic dynamical properties of open and closed relativistic st

S. Nojiri, S. D. Odintsov

The derivation of the conformal anomaly for dilaton coupled electromagnetic field in curved space is presented. The models of this sort naturally appear in stringy gravity or after spherical reduction of multidimensional Einstein-Maxwell theory. It is shown that unlike the case of minimal vector in curved space or dilaton coupled scalar the anomaly induced e