September 1997 arXiv papers — page 18

A. Di Giacomo, B. Lucini, L. Montesi, G. Paffuti

Dual superconductivity in the confining phase of gauge theories is discussed in terms of a disorder parameter which vanishes in normal phase and is different from zero in the superconducting phase.

P. Garcia-Abia

Using the data collected by the four experiments at LEP during 1990-1994, a precise measurement of the tau longitudinal polarisation (P_tau) has been performed, as well as the measurement of the transverse-transverse and transverse-normal tau spin correlations. From the P_tau measurement, assuming lepton universality of the neutral currents, the effective we

Alexander Gromov

Boundary problem for Tolman-Bondi model is formulated. One-to-one correspondence between singularities hypersurfaces and initial conditions of the Tolman-Bondi model is constructed.

K. A. Bronnikov, M. A. Grebeniuk, V. D. Ivashchuk, V. N. Melnikov

A multidimensional field model describing the behaviour of (at most) one Einstein space of non-zero curvature and n Ricci-flat internal spaces is considered. The action contains several dilatonic scalar fields and antisymmetric forms. The problem setting covers various problems with field dependence on a single space-time coordinate, in particular, isotropic

Majid Abolhasani, Mehdi Golshani

One of the basic peoblems of quantum cosmology is the problem of time. Various solutions have been proposed for this problem. One approach is to use the Bohmian time. Another Approach is to use the probabilistic time which was recently introduced by Castagnino. We consider both of these definitions as generalizations of a semi-classical time and compare them

D. A. W. Hutchinson, E. Zaremba

We investigate the zero-temperature collective excitations of a Bose-condensed atomic gas in anisotropic parabolic traps. The condensate density is determined by solving the Gross-Pitaevskii (GP) equation using a spherical harmonic expansion. The GP eigenfunctions are then used to solve the Bogoliubov equations to obtain the collective excitation frequencies

S. V. Iordanskii

The skyrmionic mass was calculated in the main order of the gradient expansion in derivatives of the rotation matrix. The mass is proportinal to the topological invariant which is the absolut value of the degree of the mapping. The coefficient is defined by the exchange interaction. The charged skyrmions in magnetic field give rise to a special branch of cyc

Domenico Gazzillo, Achille Giacometti, Flavio Carsughi

We present a closed analytical formula for the scattering intensity from charged hard sphere fluids with any arbitrary number of components. Our result is an extension to ionic systems of Vrij's analogous expression for uncharged hard sphere mixtures. Use is made of Baxter's factor correlation functions within the Mean Spherical Approximation (MSA).

Markus Holzmann, Juergen Audretsch

An ultracold wave packet of bosonic atoms loaded into a travelling laser wave may form a many-atom soliton.This is disturbed by a homogeneous force field, for example by the inevitable gravitation. The wave packet is accelerated and therefore the laser frequency appears to be chirped in the rest frame of the atoms. We derive the effective nonlinear Schröding

Yuval Oreg, Alex Kamenev

We study the Coulomb drag effect in double layer electronic systems with local tunneling links. The possibility of tunneling between the layers leads to a pronounced exchange contribution to the transconductance, which is negative and non-vanishing at zero temperature. The diffusive motion of the electrons inside each layer in interplay with the electron-ele

Richard P. Sear

In a mixed suspension of rods and small polymer coils, the rods adsorb onto a hard wall in contact with the suspension. This adsorption is studied in the low density of rods limit. It is driven by depletion forces and is much stronger for long rods than for spheres. This is shown by means of exact, numerical, calculations and an approximate theory.

V. A. Kashurnikov, A. V. Krasavin, B. V. Svistunov

We study one-dimensional truncated (no more than 2 particles on a site) bosonic Hubbard model in both repulsive and attractive regimes by exact diagonalization and exact worldline Monte Carlo simulation. In the commensurate case (one particle per site) we demonstrate that the point of Mott-insulator -- superfluid transition, $(U/t)_c=0.50\pm 0.05$, is remark

A. S. Moskvin, A. S. Ovchinnikov

In the framework of the model of the polar singlet-triplet Jahn-Teller centers the cross-section is obtained for magnetic neutron scattering in high-$T_{c}$ cuprates. Multi-mode character of the $CuO_{4}$ cluster ground manifold in the new phase of polar centers determines the dependence of magnetic form-factor on the local structure and charge state of the

Yu. Kagan, B. V. Svistunov

We consider the self-evolution of strongly non-equilibrium interacting Bose gas. Due to the mere fact of large (as compared to unity) occupation numbers in the initial state the problem is directly reduced to the question of temporal evolution of the statistical matrix diagonal in the coherent-state representation. Strictly speaking, gauge symmetry is not de

C. A. Stafford, D. Baeriswyl, J. Burki

A unified treatment of the cohesive and conducting properties of metallic nanostructures in terms of the electronic scattering matrix is developed. A simple picture of metallic nanocohesion in which conductance channels act as delocalized chemical bonds is derived in the jellium approximation. Universal force oscillations of order epsilon_F/lambda_F are pred

P. Dieleman, H. G. Bukkems, T. M. Klapwijk, M. Schicke

We have experimentally investigated the quasiparticle shot noise in NbN/MgO/NbN superconductor - insulator - superconductor tunnel junctions. The observed shot noise is significantly larger than theoretically expected. We attribute this to the occurrence of multiple Andreev reflection processes in pinholes present in the MgO barrier. This mechanism causes th

E. Dagotto, S. Yunoki, A. L. Malvezzi, A. Moreo

The phase diagram of the ferromagnetic Kondo model for manganites is investigated using computational techniques. In clusters of dimensions 1 and 2, Monte Carlo simulations in the limit where the localized spins are classical show a rich low temperature phase diagram with three dominant regions: (i) a ferromagnetic phase, (ii) phase separation between hole-p

Mirko Degli Esposti, Gianluigi Del Magno, Marco Lenci

A class of non-compact billiards is introduced, namely the infinite step billiards, i.e., systems of a point particle moving freely in the domain $Ω= \bigcup_{n\in\N} [n,n+1] \times [0,p_n]$, with elastic reflections on the boundary; here $p_0 = 1, p_n > 0$ and $p_n$ vanishes monotonically. After describing some generic ergodic features of these dynamical sy

Limin Wang, V. F. Mukhanov, Paul J. Steinhardt

We examine the theoretical foundations of standard methods for computing density perturbations in inflationary models. We find that: (1) the time-delay formalism (introduced by Guth and Pi, 1982) is only valid when inflation is well-described by the de Sitter solution and the equation-of-state is nearly unchanging; and, (2) the horizon-crossing/Bessel approx

Peter Hoeflich

From the spectra and light curves it is clear that SNIa events are thermonuclear explosions of white dwarfs. However, details of the explosion are highly under debate. Here, we present detailed models which are consistent with respect to the explosion mechanism, the optical and infrared light curves, and the spectral evolution. This leaves the description of

C. L. Carilli, K. M. Menten, M. J. Reid, M. P. Rupen

We have searched for redshifted neutral hydrogen 21cm absorption toward sources from the Stickel et al. `red quasar' sub-sample. Five of these red quasars have been searched for redshifted HI 21cm absorption to optical depth levels of a few percent, and four show strong absorption. This 80% success rate for the red quasars compares to the much lower succ

D. H. Hartmann, D. D. Dixon, E. D. Kolaczyk, J. Samimi

The region near the Galactic center may have experienced recurrent episodes of injection of energy in excess of $\sim$ 10$^{55}$ ergs due to repeated starbursts involving more than $\sim$ 10$^4$ supernovae. This hypothesis can be tested by measurements of $γ$-ray lines produced by the decay of radioactive isotopes and positron annihilation, or by searches fo

G. Mark Voit

The nulling interferometers proposed to study planets around other stars are generally well suited for studying small-scale structures surrounding other bright pointlike objects such as the nuclei of active galaxies. Conventional interferometric techniques will produce useful maps of optical/IR line and continuum emission within active galaxies on scales of

W. Van Dyke Dixon, Mark Hurwitz, Stuart Bowyer

We present measurements of interstellar H_2 absorption lines in the continuum spectra of seven early-type stars in the Galactic disk at distances between 1 and 4 kpc. Five of these stars provide lines of sight through the Sagittarius spiral arm. The spectra, obtained with the Berkeley EUV/FUV spectrometer on the ORFEUS telescope in 1993 September, have a res

F. Combes, T. Wiklind, N. Nakai, Paris Observatory

We report new observations of molecular oxygen in absorption at z=0.685 in front of the radio source B0218+357. The lines at 56.3 and 118.7 GHz have been observed, redshifted to 33.4 and 70.5 GHz respectively, with the 12m at Kitt Peak, 43m at Green Bank telescopes, and the 45m Nobeyama radio telescope. Deriving the surface filling factor of the absorbing da

The MACHO Collaboration, C. Alcock, R. A. Allsman, D. Alves

We report the discovery of 20 1H/2H and 7 F/1H beat Cepheids in the SMC by the MACHO Project. We utilize the 20 1H/2H stars to determine lightcurve shape for the SMC second-overtone (2H) mode of Cepheid pulsation. We predict, similar to the findings of Alcock et al. (1997, ApJ, submitted), that 2H Cepheids will have nearly or purely sinusoidal light variatio

C. Clement, R. W. Hilditch, J. Kaluzny, S. M. Rucinski

New observations of variable stars in the globular cluster M3 reveal that the RR Lyrae variable V79 is a double-mode (RRd) variable with the first overtone mode dominating. In all previous studies, V79 was found to be a fundamental mode (RRab) pulsator with an irregular light curve. This is the first observed mode switch for an RR Lyrae variable and it is di

A. F. Illarionov, I. V. Igumenshchev

A new statistical approach is presented to study the thermal instability process of optically thin unmagnetized plasma. In this approach the time evolution of mass distribution function over temperature is calculated. This function characterizes the statistical properties of the multiphase medium of arbitrary spaced three-dimensional structure of arbitrary t

M. Crézé, E. Chereul, O. Bienaymé, C. Pichon

Hipparcos data provide the first, volume limited and absolute magnitude limited homogeneous tracer of stellar density and velocity distributions in the solar neighbourhood. The density of A-type stars more luminous than $M_v=2.5$ can be accurately mapped within a sphere of 125 pc radius, while proper motions in galactic latitude provide the vertical velocity

S. R. Habbal, R. Woo, S. Fineschi, R. O'Neal

We present in this Letter the first coordinated radio occultation measurements and ultraviolet observations of the inner corona below 5.5 Rs, obtained during the Galileo solar conjunction in January 1997, to establish the origin of the slow solar wind. Limits on the flow speed are derived from the Doppler dimming of the resonantly scattered componentof the o

M. Gramann

We investigate the power spectrum of velocity fluctuations in the universe, $V^2(k)$, starting from four different measures of velocity: (1) the power spectrum of velocity fluctuations from peculiar velocities of galaxies; (2) the rms peculiar velocity of galaxy clusters; (3) the power spectrum of velocity fluctuations from the power spectrum of density fluc

Pippa Goldschmidt, Lance Miller

The recently-finished Edinburgh UVX quasar survey at B < 18 is used together with other complete samples to estimate the shape and evolution of the optical luminosity function in the redshift range 0.3 < z < 2.2. There is a significantly higher space density of quasars at high luminosity and low redshift than previously found in the PG sample of Schmidt & Gr

R. M. C. de Almeida, S. Moss de Oliveira, T. J. P. Penna

We present a model for biological aging that considers the number of individuals whose (inherited) genetic charge determines the maximum age for death: each individual may die before that age due to some external factor, but never after that limit. The genetic charge of the offspring is inherited from the parent with some mutations, described by a transition

Alfredo T. Suzuki, Alexandre G. M. Schmidt

Negative dimensional integration method (NDIM) is a technique to deal with D-dimensional Feynman loop integrals. Since most of the physical quantities in perturbative Quantum Field Theory (pQFT) require the ability of solving them, the quicker and easier the method to evaluate them the better. The NDIM is a novel and promising technique, ipso facto requiring

M. F. Bietenholz, N. Bartel, M. P. Rupen

M81 is the nearest galaxy with an active galactic nucleus, with the possibly exception of Cen A. The nucleus is exceptionally compact. Here we present results from new VLA and VLBI observations of the nucleus of M81. The VLA shows that its flux density and spectral index are variable by 50% on a timescale of weeks. The VLBI imaging results show that there is

Amol S. Dighe, Michael Gronau, Jonathan L. Rosner

The CLEO Collaboration has now observed the decays $B^+ \to ωπ^+$ and $B \to ωK^+$ with branching ratios of $(1.1^{+0.6}_{-0.5} \pm 0.2) \times 10^{-5}$ and $(1.5^{+0.7}_{-0.6} \pm 0.3) \times 10^{-5}$, respectively. These are the first reported decays to charmless final states involving a vector (V) and a pseudoscalar (P) meson. The implications of these de

Q-Han Park, H. J. Shin

The Bäcklund transformation for the three-level Maxwell-Bloch equation is presented in the matrix potential formalism. By applying the Bäcklund transformation to a constant electric field background, we obtain a general solution for matched pulses (a pair of solitary waves) which can emit or absorb a light velocity solitary pulse but otherwise propagate with

Q-Han Park, H. J. Shin

We introduce a new notion of &#34;matrix potential&#34; to nonlinear optical systems. In terms of a matrix potential $g$, we present a gauge field theoretic formulation of the Maxwell-Bloch equation that provides a semiclassical description of the propagation of optical pulses through resonant multi-level media. We show that the Bloch part of the equation ca

M. Reinaldo-Falagan, P. Tarazona, E. Chacon, J. P. Hernandez

Thermodynamic and electronic properties are obtained for a lattice-gas model fluid with self-consistent, partial, occupation of its sites; the self consistency consists in obtaining ionic configurations from grand-canonical Monte Carlo simulations based on fits to the exact, electronic, tight-binding energies of isothermal ensembles of those same ionic confi

A. Bartl, E. Christova, T. Gajdosik, W. Majerotto

We present a complete analysis of the electrtic and weak dipole moment form factors of the top quark within the Minimal Supersymmetric Standard Model with complex parameters. We include gluino, chargino, and neutralino exchange in the loops of the $γt\bar{t}$ and $Z t\bar{t}$ vertices.

Friedemann Brandt, Norbert Dragon

A four dimensional gauge theory with nonpolynomial but local interactions of 1-form and 2-form gauge potentials is constructed. The model is a nontrivial deformation of a free gauge theory with nonpolynomial dependence on the deformation parameter (= gauge coupling constant).

Michele Maggiore

Perturbative $α&#39;$ corrections to the low energy string effective action have been recently found to have a potentially regularizing effect on the singularity of the lowest order pre-big-bang solutions. Whether they actually regularize it, however, cannot be determined working at any finite order in a perturbative expansion in powers of the string constan

Chang-Yeong Lee, Dong Won Lee

We analyze the gauge symmetry of a topological mass generating action in four dimensions which contains both a vector and a second rank antisymmetric tensor fields. In the Abelian case, this system induces an effective mass for the vector gauge field via a topological coupling $B \wedge F$ in the presence of a kinetic term for the antisymmetric tensor field

H. G. Dosch, S. Narison

We select sum rules from which one can extract directly reliable limits on the size of the chiral symmetry breaking light quark condensate $<\barψψ>$. Combined results from the nucleon and $B^*-B$ mass-splitting sum rules give a result compatible with the standard value: $<\barψψ> (1 GeV) \simeq (-229 MeV)^3$, through the determinations of the quark-gluon mi

The Virgo Consortium, :, A. Jenkins, C. S. Frenk

We present an analysis of the clustering evolution of dark matter in four cold dark matter (CDM) cosmologies. We use a suite of high resolution, 17-million particle, N-body simulations which sample volumes large enough to give clustering statistics with unprecedented accuracy. We investigate both a flat and an open model with Omega_0=0.3, and two models with

Ya. V. Lisitsyn, A. V. Shapovalov

For a system of linear partial differential equations (LPDEs) we introduce an operator equation for auxiliary operators. These operators are used to construct a kernel of an integral transformation leading the LPDE to the separation of variables (SoV). The auxiliary operators are found for various types of the SoV including conventional SoV in the scalar sec

Lars M. Johansen

It is shown that Bell&#39;s proof of violation of local realism in phase space is incorrect. Using Bell&#39;s approach, a violation can be derived also for nonnegative Wigner distributions. The error is found to lie in the use of an unnormalizable Wigner function.

Michael B. Mensky, Roberto Onofrio, Carlo Presilla

Application of the path-integral approach to continuous measurements leads to effective Lagrangians or Hamiltonians in which the effect of the measurement is taken into account through an imaginary term. We apply these considerations to nonlinear oscillators with use of numerical computations to evaluate quantum limitations for monitoring position in such a

Michael B. Mensky, Roberto Onofrio, Carlo Presilla

We discuss a model of repeated measurements of position in a quantum system which is monitored for a finite amount of time with a finite instrumental error. In this framework we recover the optimum monitoring of a harmonic oscillator proposed in the case of an instantaneous collapse of the wavefunction into an infinite-accuracy measurement result. We also es

Victor G. Kac

This is a review of recent results on conformal (super)algebras. It may be viewed as an amplification of my Wigner medal acceptance speech (given in July 1996 in Goslar, Germany) reproduced in the introduction.

Amit Halder

An alternative method of generation of Cerenkev radiation is proposed over here with the help of a rotating source and a reflector. The principle is that, if we focus a narrow beam of light on to source of light is rotated with certain angular velocity then the light spot on the surface will move with very high velocity which may exceed the velocity of light

U. Becciani, R. Ansaloni, V. Antonuccio-Delogu, G. Erbacci

N-body algorithms for long-range unscreened interactions like gravity belong to a class of highly irregular problems whose optimal solution is a challenging task for present-day massively parallel computers. In this paper we describe a strategy for optimal memory and work distribution which we have applied to our parallel implementation of the Barnes & Hut (

S. N. Gurbatov, S. I. Simdyankin, E. Aurell, U. Frisch

This work is devoted to the decay ofrandom solutions of the unforced Burgers equation in one dimension in the limit of vanishing viscosity. The initial velocity is homogeneous and Gaussian with a spectrum proportional to $k^n$ at small wavenumbers $k$ and falling off quickly at large wavenumbers. In physical space, at sufficiently large distances, there is a

S. B. Carr, I. R. Afnan, B. F. Gibson

The $ΛΛ$ interaction resulting from the SU(3) rotation of the S-wave component of the Nijmegen OBE potential $D$ is used to calculate the binding energy of $^{ 6}_{ΛΛ}$He as a $ΛΛα$ three-body system, and the neutron differential energy spectrum for the reaction $Ξ^- + d \to n + Λ+ Λ$.

Joerg Wildeshaus

This is a revised version of ANT-0049. Given an elliptic curve E --> B over a base B with zero section i, we denote, letting E&#39;:= E - i(B), by L(E) the Q-vector space with basis ({s}, s \in E&#39;(B)). Assume that B is smooth and separated over a field of characteristic 0. On the lowest step, the weak version of the elliptic Zagier conjecture predicts th

Paul Bankston

We survey various attempts to transport the ultraproduct construction from the realm of model theory to that of general topology.

I. Antoniadis, M. Quiros

We describe the breaking of supersymmetry in M-theory by coordinate dependent (Scherk-Schwarz) compactification of the eleventh dimension. Supersymmetry is spontaneously broken in the gravitational and moduli sector and communicated to the observable sector, living at the end-point of the semicircle, by radiative gravitational interactions. This mechanism sh

Ram Brustein, Merav Hadad

We compute spectra of particles produced during a dilaton-driven kinetic inflation phase within string cosmology models. The resulting spectra depend on the parameters of the model and on the type of particle and are quite varied, some increasing and some decreasing with frequency. We use an approximation scheme in which all spectra can be expressed in a nic

Kaj Roland, Haru-Tada Sato

We show how the multiloop amplitudes of $Φ^3$ theory (in the worldline formulation of Schmidt and Schubert) are recovered from the N-tachyon $(h+1)$-loop amplitude in bosonic string theory in the $α&#39; \to 0$ limit, if one keeps the tachyon coupling constant fixed. In this limit the integral over string moduli space receives contributions only from those c

Hiroshi Suzuki, Hirofumi Yasuta

It is well-known that the quantum tunneling makes conventional perturbation series non-Borel summable. We use this fact reversely and attempt to extract the decay width of the false-vacuum from the actual perturbation series of the vacuum energy density (vacuum bubble diagrams). It is confirmed that, at least in quantum mechanical examples, our proposal prov

Ashok Das, Jnanadeva Maharana, Shibaji Roy

It is well-known that the conjectured SL(2, Z) invariance of type IIB string theory in ten dimensions also persists in lower dimensions when the theory is compactified on tori. By making use of this recent observation, we construct an infinite family of magnetically charged black hole solutions of type II superstring theory in four space-time dimensions. The

X. M. Ding, B. Y. Hou, B. Yuan Hou, L. Zhao

We construct a realization of the Yangian double DY_\hbar(gl_N) and DY_\hbar(sl_N) of an arbitrary level k in terms of free boson fields with a continuous parameter. In the \hbar \to 0 limit this realization becomes the Wakimoto realization of kac-Moody algebra gl_N and sl_N, respectively. The vertex operators and the screening currents are also constructed

C. A. Dominguez, M. S. Fetea, M. Loewe

Vector Meson Dominance ideas together with a Finite Energy QCD sum rule allows for the determination of the $q^{2}$- and the $T$- dependence of the effective hadronic coupling constant $g_{ρππ}$ in the space-like region. It turns out that $g_{ρππ}(q^{2},T)$ vanishes at the critical temperature $T_{c}$, independently of $q^{2}$. A comparison with a previous i

H. G. Dosch

After some general remarks on non-perturbative QCD I present shortly models which lead to a color-electric flux tube formation. The implications of such a flux tube formation especially on high energy scattering are discussed.

Hyun-Chul Kim, Maxim V. Polyakov, Michal Praszalowicz, Klaus Goeke

Based on the recent study of the magnetic moments and axial constants within the framework of the chiral quark-soliton model, we investigate the baryon semileptonic decay constants $(f_1,f_2)$ and $(g_1, g_2)$. Employing the relations between the diagonal transition matrix elements and off-diagonal ones in the vector and axial-vector channels, we obtain the

Finn Ravndal

Photons in blackbody radiation have non-zero interactions due to their couplings to virtual electron-positron pairs in the vacuum. For temperatures much less than the electron mass $m$ these effects can be described by an effective theory incorporating the Uehling and Euler-Heisenberg interactions as dominant terms. By a redefinition of the electromagnetic f

A. A. Gvozdev, N. V. Mikheev, L. A. Vassilevskaya

Radiative transition of massless neutrino $ν_l \to ν_l + γ$ ($l = e, μ, τ$) in a strong magnetic field is investigated in the framework of the Standard Model. The process probability and the mean values of the neutrino energy and momentum loss are presented. Possible astrophysical manifestation of the process considered is analysed.

Uma Mahanta

New interactions appearing at a scale $Λ$ larger than the weak interaction scale v can affect physical processes at energies below $Λ$ through non-renormalizable $SU(3)\times SU(2)\times U(1)_y$ invariant operators added to the standard model Lagrangian. In this article we investigate the effect of flavor conserving contact interactions on the total cross-se

M. F. Watson, N. K. Watson

This report summarises experimental aspects of the phenomena of colour reconnection in W+W- production, concentrating on charged multiplicity and event shapes, which were carried out as part of the Phenomenology Workshop on LEP2 Physics, Oxford, Physics Department and Keble College, 14-18 April, 1997. The work includes new estimates of the systematic uncerta

V. N. Baier, V. M. Katkov

Bremsstrahlung of photons from highly relativistic electrons is investigated. The cross section of the processes, which is suppressed due to a multiple scattering of an emitting electron in dense media (LPM effect) and due to photon interaction with electrons of a medium, is calculated with an accuracy up to &#34;next to leading logarithm&#34; and with the C

D. A. Johnston, P. Plechac

The statistical mechanics of spin models, such as the Ising or Potts models, on generic random graphs can be formulated economically by considering the N --> 1 limit of Hermitian matrix models. In this paper we consider the N --> 1 limit in complex matrix models, which describes vertex models of different sorts living on random graphs. From the graph theoret

N. Eicker, J. Fingberg, S. Güsken, H. Hoeber

We present results for the b \bar b spectrum obtained using an O(M_bv^6)-correct non-relativistic lattice QCD action, where M_b denotes the bare b-quark mass and v^2 is the mean squared quark velocity. Propagators are evaluated on SESAM&#39;s three sets of dynamical gauge configurations generated with two flavours of Wilson fermions at beta = 5.6. These resu

Yasufumi Kojima

Quasi-toroidal oscillations in slowly rotating stars are examined in the framework of general relativity. The oscillation frequency to first order of the rotation rate is not a single value even for uniform rotation unlike the Newtonian case. All the oscillation frequencies of the r-modes are purely neutral and form a continuous spectrum limited to a certain

Wayne Rossman, Masaaki Umehara, Kotaro Yamada

In this work we give a method for constructing a one-parameter family of complete CMC-1 (i.e. constant mean curvature 1) surfaces in hyperbolic 3-space that correspond to a given complete minimal surface with finite total curvature in Euclidean 3-space. We show that this one-parameter family of surfaces with the same symmetry properties exists for all given

Shin Kato, Masaaki Umehara, Kotaro Yamada

For each end of complete minimal surface in the Euclidean 3-space, the flux vector is defined. It is well-known that the sum of the flux vector over all ends are zero. Consider the following inverse problem: For each balanced n-vectors, find an n-end catenoid which realizes these vectors as flux. Here, an n-end catenoid is a complete minimal surface of genus

Shin Kato, Masaaki Umehara, Kotaro Yamada

For a complete minimal surface in the Euclidean 3-space, the so-called flux vector corresponds to each end. The flux vectors are balanced, i.e., the sum of those over all ends are zero. Consider the following inverse problem: For each balanced n vectors, find an n-end catenoid which attains given vectors as flux. Here, an n-end catenoid is a complete minimal

E. A. Jagla

The pressure-temperature phase diagram of a one-component system, with particles interacting through a spherically symmetric pair potential is studied. It is shown that if the pair potential allows for a discontinuous reduction of the volume of the system when pressure is increased (at zero temperature), then the phase diagram obtained has many ``water like&

Kirill N. Alekseev, Ethan H. Cannon, Jonathan C. McKinney, Feodor V. Kusmartsev

We study a resistively shunted semiconductor superlattice subject to a high-frequency electric field. Using a balance equation approach that incorporates the influence of the electric circuit, we determine numerically a range of amplitude and frequency of the ac field for which a dc bias and current are generated spontaneously and show that this region is li

Pep Español

We present a mechanistic model for a Newtonian fluid called fluid particle dynamics. By analyzing the concept of ``fluid particle&#39;&#39; from the point of view of a Voronoi tessellation of a molecular fluid, we propose an heuristic derivation of a dissipative particle dynamics algorithm that incorporates shear forces between dissipative particles. The inc

Boris Levitan, Eytan Domany

We present a systematic quasi-mean field model of the Ostwald ripening process in two dimensions. Our approach yields a set of dynamic equations for the temporal evolution of the minority phase droplets&#39; radii. The equations contain only pairwise interactions between the droplets; these interactions are evaluated in a mean- field type manner. We proceed

Madan Rao, Surajit Sengupta

Martensites are long-lived nonequilibrium structures produced following a quench across a solid state structural transition. In a recent paper (Phys. Rev. Lett. 78, 2168 (1997)), we had described a mode-coupling theory for the morphology and nucleation kinetics of the equilibrium ferrite phase and twinned martensites. Here we calculate nucleation rates withi

Boris Levitan, Eytan Domany

We present a systematic extension of mean field models for Ostwald ripening in two dimensions. We derived, using a mean field type approximation, an analytic expression for pairwise interactions between the minority phase droplets. These interactions appear in dynamic equations for the droplets&#39; radii and positions, which are solved numerically for syste

Yue Yu, Wenjun Zheng, Zhongyuan Zhu

We derive a microscopic theory of the composite fermions describing the low-lying edge excitations in the fractional quantum Hall liquid. Using the composite fermion transformation, one finds that the edge states of the $ν=1/m$ system in a disc sample are described by, in one dimensional limit, the Calogero-Sutherland model with other interactions between th

M. Chertkov, G. Falkovich, I. Kolokolov

Probability density function (PDF) of passive scalar dissipation ${\cal P} (ε)$ is found analytically in the limit of large Peclet and Prandtl numbers (Batchelor-Kraichnan regime) in two dimensions. The tail of PDF at $ε\gg<ε>$ is shown to be stretched exponent $\ln{\cal P}(ε)\proptoε^{1/3}$. At $ε\ll<ε>$, ${\cal P}\propto 1/\sqrtε$.

G. Gallavotti, G. Gentile, V. Mastropietro

An exact expression for the determinant of the splitting matrix is derived: it allows us to analyze the asympotic behaviour needed to amend the large angles theorem proposed in Ann. Inst. H. Poincaré, B-60, 1, 1994. The asymptotic validity of Melnokov&#39;s formulae is proved for the class of models considered, which include polynomial perturbations.

Ilaria Cagnoni, Roberto Della Ceca, Tommaso Maccacaro

In this paper we report the first results on a medium survey program conducted in the 2-10 keV energy band using data from the GIS2 instrument onboard the ASCA satellite. We have selected from the ASCA public archive (as of February 14, 1996) 87 images which are suitable for this project. 60 serendipitous X-ray sources, with a snr greater than 3.5, were foun

G. Michalek, M. Ostrowski, R. Schlickeiser

The acceleration of energetic particle transport in high amplitude magnetosonic and Alfvenic turbulence is considered using the method of Monte Carlo particle simulations, involving integration of particle equations of motion. We derive the momentum diffusion coefficient in the presence of anisotropic turbulent wave in the high-magnetized plasma, for a flat

A. Caccianiga, T. Maccacaro

We present and discuss new spectroscopic observations of the unusual galaxy J2310-43. The observations cover a wide wavelength range, from 3700 A to 9800 A allowing the study of both the regions where H alpha and the Ca II ``contrast&#39;&#39; are expected. No evidence for H alpha in emission is found and we thus confirm the absence of emission lines in the

B. Hauck, D. Ballereau, J. Chauville

We publish here the second part of our spectroscopic survey at high dispersion of some known and suspected lambda Bootis stars with a view to detecting circumstellar shell features. Eight stars of our sample exhibit such features. These stars are fast rotators, a result which is in line with Holweger and Rentzsch-Holm&#39;s study (1995). The analysis of the

Priyamvada Natarajan, Max Pettini

We use the relationships between galactic HI mass and B-band luminosity determined by Rao & Briggs to recalculate the mass density of neutral gas at the present epoch based on more recent measures of the galaxy luminosity function than were available to those authors. We find $Ω_{gas}(z=0) \simeq 5 \times 10^{-4}$ in good agreement with the original Rao & Br

H. -Th. Janka

The observation of neutrinos from Supernova~1987A has confirmed the theoretical conjecture that these particles play a crucial role during the collapse of the core of a massive star. Only one per cent of the energy they carry away from the newly formed neutron star may account for all the kinetic and electromagnetic energy responsible for the spectacular dis

H. -Th. Janka, W. Keil

The observation of neutrinos from Supernova 1987A has confirmed the theoretical conjecture that these particles play a crucial role during the collapse of the core of a massive star. Only one per cent of the energy they carry away from the newly formed neutron star may account for all the kinetic and electromagnetic energy responsible for the spectacular dis

Kyoko Matsushita, Kazuo Makishima, Etsuko Rokutanda, Noriko Y. Yamasaki

High quality X-ray spectra of NGC 4636 are obtained with ASCA. Theoretical models are found unable to reproduce the data in the Fe-L line region. Spectral data above 1.4 keV indicate that Mg to Si abundance ratio is $\sim 1$ solar. Assuming that the abundance ratios among $α$-elements are the same with the solar ratios, spectral fit with increased systematic

David A. Lowe

A formulation of new six-dimensional theories with (1,0) supersymmetry and E_8 global symmetry is proposed. The model is based on the large n theory describing n D-strings interacting with parallel D-fivebranes in Type I string theory.

H. Flenner, M. Zaidenberg

In the previous paper [E-print alg-geom/9507004] we classified the rational cuspidal plane curves C with a cusp of multiplicity deg C - 2. In particular, we showed that any such curve can be transformed into a line by Cremona transformations. Here we do the same for the rational cuspidal plane curves C with a cusp of multiplicity deg C - 3.

K. Foerger, S. Stieberger

For the gauge couplings, which arise after toroidal compactification of six-dimensional heterotic N=1 string theories from the T^2 torus, we calculate their one-loop corrections. This is performed by considering string amplitudes involving two gauge fields and moduli fields. We compare our results with the equations following from N=2 special geometry and th

P. S. Howe, N. D. Lambert, P. C. West

We obtain a BPS soliton of the M theory fivebrane&#39;s equations of motion representing a supersymmetric self-dual string. The resulting solution is then dimensionally reduced and used to obtain 0-brane and (p-2)-brane solitons on D-p-branes.

Maria Golenishcheva-Kutuzova, Victor Kac

$Γ$-conformal algebra is an axiomatic description of the operator product expansion of chiral fields with simple poles at finitely many points. We classify these algebras and their representations in terms of Lie algebras and their representations with an action of the group $Γ$. To every $Γ$-conformal algebra and a character of $Γ$ we associate a Lie algebr

Oleg A. Starykh, Dmitrii L. Maslov

We consider transport through a one-dimensional conductor subject to an external periodic potential and connected to non-interacting leads (a &#34;Mott quantum wire&#34;). For the case of a strong periodic potential, the conductance is shown to jump from zero, for the chemical potential lying within the Mott-Hubbard gap, to the non-interacting value of 2e^2/

Matthias R. Gaberdiel, Barton Zwiebach

We consider type IIB theory compactified on a two-sphere in the presence of mutually nonlocal 7-branes. The BPS states associated with the gauge vectors of exceptional groups are seen to arise from open strings connecting the 7-branes, and multi-pronged open strings capable of ending on more than two 7-branes. These multi-pronged strings are built from open