April 1998 arXiv papers — page 9

Leonard S. Kisslinger

Using a recently developed three-point formalism within the method of QCD Sum Rules we determine the vacuum susceptibilities needed in the two-point formalism for the coupling of axial, vector, tensor and pseudoscalar currents to hadrons. All susceptibilities are determined by the space-time scale of condensates, which is estimated from data for deep inelast

Robert Fleischer

It has recently been pointed out that the observables of the decay $B^+\to K^+\bar{K^0}$ and its charge conjugate allow us to take into account rescattering effects in constraints on the CKM angle $γ$ arising from $B^\pm\toπ^\pm K$ and $B_d\toπ^\pm K^\pm$ modes, and that they play an important role to obtain insights into final-state interactions. In this pa

A. Erdas, C. W. Kim, T. H. Lee

We calculate the one-loop thermal self-energy of a neutrino in a constant and homogeneous magnetic field to all orders in the magnetic field strength using Schwinger's proper time method. We obtain the dispersion relation under various conditions.

Gabriela Miu

The transverse momentum distribution of W+/- bosons at hadron colliders is well described by a parton-shower model for small pT values, but not for large ones. This article is an attempt to give a better description of the distribution by using corrections derived from the matrix-element formalism. The parton shower for qqbar->W+/- has been modified to resem

S. V. Chekanov

An interpretation of scale-invariant multiplicity fluctuations inside hadronic jets is presented. It is based on the branching mechanism with the angular ordering of soft partons in sequential branchings. A relationship with fractal distributions is demonstrated. The model takes into account the finiteness of the number of particles produced in jets (finite

P. A. Eminov, K. V. Zhukovskii, K. G. Levtchenko

The rate of associative production of Higgs and $Z$--bosons by charged leptons in the field of a plane electromagnetic wave of arbitrary intensity and in the constant crossed field is obtained. The cross section is examined as a function of particle energies and external field intensities for various values of the Higgs boson mass. It is shown, that the phot

B. C. Allanach, G. Amelino-Camelia, O. Philipsen, O. Pisanti

We analyze the symmetry-breaking patterns of grand unified theories from the point of view of a recently-proposed criterion of renormalization-group naturalness. We perform the analysis on simple non-SUSY SU(5) and SO(10) and SUSY SU(5) GUTs. We find that the naturalness criterion can favor spontaneous-symmetry-breaking in the direction of the smallest of th

B. Holdom

We provide an economical description of mass and flavor based on strong interactions and some dynamical assumptions. We include a discussion of CP violation in the quark sector and its relation to neutrino masses.

B. Holdom, F. S. Roux

We show that the next-to-leading corrections to the kernel of the gap equation can be large and of opposite sign to the lowest order kernel, in the presence of a gauge boson mass. This calls into question the reliability of the Most Attractive Channel hypothesis.

J P Bowes, R R Volkas

We account for the solar and atmospheric neutrino problems by introducing maximal mixing between conventional and sterile neutrino partners. We achieve this by invoking a seesaw-like mechanism which not only provides us with maximally mixed neutrino/sterile-neutrino mass eigenstates but also accounts for the relative suppression of the neutrino masses compar

A. A. Prinz, R. Baggs, J. Ballam, S. Ecklund

Particles with electric charge q < 10^(-3)e and masses in the range 1--100 MeV/c^2 are not excluded by present experiments. An experiment uniquely suited to the production and detection of such &#34;millicharged&#34; particles has been carried out at SLAC. This experiment is sensitive to the infrequent excitation and ionization of matter expected from the pa

Gerhard Rein, Alan D. Rendall, Jack Schaeffer

In recent years the threshold of black hole formation in spherically symmetric gravitational collapse has been studied for a variety of matter models. In this paper the corresponding issue is investigated for a matter model significantly different from those considered so far in this context. We study the transition from dispersion to black hole formation in

Djordje Sijacki

World spinors are objects that transform w.r.t. double covering group $\bar{Diff}(4,R)$ of the Group of General Coordinate Transformations. The basic mathematical results and the corresponding physical interpretation concerning these, infinite-dimensional, spinorial representations are reviewed. The role of groups $Diff(4,R)$, $GA(4,R)$, $GL(4,R)$, $SL(4,R)$

Yuval Ne&#39;eman, Djordje Sijacki

The existence of a topological double-covering for the $GL(n,R)$ and diffeomorphism groups is reviewed. These groups do not have finite-dimensional faithful representations. An explicit construction and the classification of all $\bar{SL}(n,R)$, $n=3,4$ unitary irreducible representations is presented. Infinite-component spinorial and tensorial $\bar{SL}(4,R

Alan D. Rendall

Recent progress in understanding the structure of cosmological singularities is reviewed. The well-known picture due to Belinskii, Khalatnikov and Lifschitz (BKL) is summarized briefly and it is discussed what existing analytical and numerical results have to tell us about the validity of this picture. If the BKL description is correct then most cosmological

E. I. Shakhnovich

We review the recent progress in computational approaches to protein design which builds on advances in statistical-mechanical protein folding theory. In particular, we evaluate the degeneracy of the protein code (i.e. how many sequences fold into a given conformation) and outline a simple condition for &#39;&#39;designability`` in a protein model. From this

V. A. Krupenin, D. E. Presnov, M. N. Savvateev, H. Scherer

We have fabricated and examined several Al single electron transistors whose small islands were positioned on top of a counter electrode and hence did not come into contact with a dielectric substrate. The equivalent charge noise figure of all transistors turned out to be surprisingly low, (2.5 - 7)*10E-5 e/sqrt(Hz) at f = 10 Hz. Although the lowest detected

J. M. Pitarke, F. J. Garcia-Vidal, J. B. Pendry

The electronic response of a composite consisting of aligned metallic cylinders in vacuum is investigated, on the basis of photonic band structure calculations. The effective long-wavelength dielectric response function is computed, as a function of the filling fraction. A spectral representation of the effective response is considered, and the surface mode

E. V. Chulkov, I. Sarria, V. M. Silkin, J. M. Pitarke

The lifetime of image states, which represent a key quantity to probe the coupling of surface electronic states with the solid substrate, have been recently determined for quantum numbers $n\le 6$ on Cu(100) by using time-resolved two-photon photoemission in combination with the coherent excitation of several states (U. Höfer et al, Science 277, 1480 (1997))

G. M. Kavoulakis, C. J. Pethick, H. Smith

We present a unified account of damping of low-lying collective modes and of relaxation of temperature anisotropies in a trapped Bose gas in the collisionless regime. By means of variational techniques, we show that the relaxation times for the two situations are closely related to the simplest variational estimate of the viscous relaxation time. We derive r

Alexey B. Pavolotsky, Thomas Weimann, Hansjoerg Scherer, Vladimir A. Krupenin

A reliable process has been developed for the fabrication of all-Nb single-electron circuits, based on spin-on glass planarization. The process steps are the in situ growth of Nb/AlOx/Nb sandwich, definition of the patterns of junctions, base electrodes and wiring by use of reactive ion etching and the planarization of a spin-on glass insulation between base

F. Onufrieva, P. Pfeuty

It is shown that a 2D system of free fermions on a square lattice with hoping between more than nearest neighbours undergoes a fundamental electronic topological transition (ETT) at some electron concentration n_c. The point δ=δ_c, T=0 (δ=1-n) is an exotic quantum critical point with several aspects of criticality. The first trivial one is related to singula

P. Chauve, T. Giamarchi, P. Le Doussal

We study a D-dimensional interface driven in a disordered medium. We derive finite temperature and velocity functional renormalization group (FRG) equations, valid in a 4-D expansion. These equations allow in principle for a complete study of the the velocity versus applied force characteristics. We focus here on the creep regime at finite temperature and sm

T. R. Weikl, M. M. Kozlov, W. Helfrich

Considering two rigid conical inclusions embedded in a membrane subject to lateral tension, we study the membrane-mediated interaction between these inclusions that originates from the hat-shaped membrane deformations associated with the cones. At non-vanishing lateral tensions, the interaction is found to depend on the orientation of the cones with respect

M. Hasenbusch, K. Pinn, S. Vinti

We present results from the simulation of a two-coupling spin-1 model with states 0,+1,-1 and nearest neighbour interaction. By a suitable choice of couplings we are able to drastically reduce the effects of corrections to scaling. Our estimates for the critical exponents are nu= 0.6299(3) and eta = 0.0359(10). For the Binder cumulant related universal ratio

Akira Shimizu

We describe the fundamental equations for description of electron-photon interactions in insulating nanostructures. Since the theory for the nanostructures are based on the theory for the bulk crystals, we shall describe elements of the theory for the bulk crystals \cite{knox}-\cite{b2} in the first three subsections. It is important in discussions on optica

J. L. Alonso, Ph. Boucaud, V. Martin-Mayor, A. J. van der Sijs

We present a lattice field theory of spins coupled to Dirac fermions, as a model for the doped copper oxide compounds. Both the fermionic and spin degrees of freedom are treated dynamically. The influence of the charge carriers on the magnetic ordering follows automatically. The magnetic phase diagram at zero temperature is studied numerically and with Mean-

W. Selke, L. N. Shchur, O. A. Vasilyev

Using Monte Carlo techniques, the two-dimensional site-diluted Ising model is studied. In particular, properties of the specific heat, its critical behaviour and the emergence of a non-singular maximum above the transition temperature at moderate concentration of defects, are discussed.

Rafael Salazar, Raul Toral, Amitabha Chakrabarti

It is found experimentally that the coexistence region of a vapor-liquid system or a binary mixture is substantially narrowed when the fluid is confined in a aerogel with a high degree of porosity (e.g. of the order of 95% to 99%). A Hamiltonian model for this system has recently been introduced (J.Donley PRE 55:539, 1997}. We have performed Monte-Carlo simu

Tomotoshi Nishino, Kouichi Okunishi

We generalize the corner transfer matrix renormalization group, which consists of White&#39;s density matrix algorithm and Baxter&#39;s method of the corner transfer matrix, to three dimensional (3D) classical models. The renormalization group transformation is obtained through the diagonalization of density matrices for a cubic cluster. A trial application

Martin Greiter

The ground state of the two-leg Heisenberg ladder is identified as an RVB type spin liquid, which is generated by Gutzwiller projection of tight-binding bands with flux pi per plaquet. Explicit trial wave functions for the magnon and hole excitations are formulated in terms of spinons and holons.

Juan J. Abad, Hans Koch, Peter Wittwer

We describe a renormalization group transformation that is related to the breakup of golden invariant tori in Hamiltonian systems with two degrees of freedom. This transformation applies to a large class of Hamiltonians, is conceptually simple, and allows for accurate numerical computations. In a numerical implementation, we find a nontrivial fixed point and

J. Delabrouille, R. Gispert, J. -L. Puget

We address the problem of map-making with data from the Planck Surveyor High Frequency Instrument, with an emphasis on the understanding and modelling of instrumental effects, and in particular that of sidelobe straylight. We propose a map-making method which takes advantage of the very special properties of the Planck scanning strategy along circular scans.

Christopher W. Mauche, John C. Raymond

Six high-resolution (λ/Δλ~ 3000) far-UV (λλ= 910-1210 Å) spectra of the magnetic cataclysmic variable AM Herculis were acquired in 1996 November during the flight of the ORFEUS-SPAS II mission. AM Her was in a high optical state at the time of the observations, and the spectra reveal emission lines of O VI λλ1032, 1038, C III λ977, λ1176, and He II λ1085 sup

N. Renaud, G. Henri

We present numerical simulation of bulk Lorentz factor of relativistic electron-positron jet driven by Compton rocket effect from accretion disc radiation. The plasma is assumed to have a power-law distribution $n_{e}(γ) \propto γ^{-s}$ whith $1 < γ< γ_{max}$ and is continuously reheated to compensate for radiation losses. We include full Klein-Nishina (here

C. Henkel, Y. P. Wang, H. Falcke, A. S. Wilson

A systematic search for 22 GHz H2O megamaser emission is reported for 50 nearby (z < 0.15) FR I galaxies. No detection was obtained, implying that ultraluminous H2O masers (L_H2O>10^3 L_sun) must be rare in early-type galaxies with FR I radio morphology. Despite higher radio core luminosities the detection rate for our sample is much lower than in similar su

Michael E. Jones, P. F. Scott

We are contructing an interferometric telescope, the Very Small Array, to study the cosmic microwave background on angular scales 0.2--4.5 degrees. The physical layout and electronic design of the telescope are optimised to give maximum protection from systematic effects, while still providing sufficient sensitivity to make high signal-to-noise images. A pro

C. Adami, A. Mazure, P. Katgert, A. Biviano

We have analyzed the projected galaxy distributions in a subset of the ENACS/ COSMOS cluster sample. We made Maximum-Likelihood fits to the distribution of COSMOS galaxies for 4 theoretical profiles, with `cores&#39; (generalized King- and Hubble-profiles) and with `cusps&#39; (generalized Navarro et al., or NFW, and de Vaucouleurs profiles). We use the Like

T. KAJINO, M. ORITO

Observations of clusters and super clusters of galaxies have indicated that the Universe is more dominated by baryons than ever estimated in the homogeneous cosmological model for primordial nucleosynthesis. Recent detections of possibly low deuterium abundance in Lyman-$α$ clouds along the line of sight to high red-shift quasars have raised another potentia

Joseph B. Jensen, John L. Tonry, Gerard A. Luppino

Surface brightness fluctuations (SBFs) are much brighter in the IR than they are at optical wavelengths, making it possible to measure greater distances using IR SBFs. We report new K&#39; (2.1 micron) SBF measurements of 9 galaxies in the Fornax and Eridanus clusters using a 1024^2-pixel HgCdTe array. We used improved analysis techniques to remove contribut

David B. Kaplan, Martin J. Savage, Mark B. Wise

Making use of the effective field theory expansion recently developed by the authors, we compute the electromagnetic form factors of the deuteron analytically to next-to-leading order (NLO). The computation is rather simple, and involves calculating several Feynman diagrams, using dimensional regularization. The results agree well with data and indicate that

R. K. P. Zia, Z. Toroczkai

We study, on a $d$ dimensional hypercubic lattice, a random walk which is homogeneous except for one site. Instead of visiting this site, the walker hops over it with arbitrary rates. The probability distribution of this walk and the statistics associated with the hop-overs are found exactly. This analysis provides a simple approach to the problem of tagged

C. L. Fryer, S. E. Woosley

We present a model for gamma-ray bursts (GRB&#39;s) in which a stellar mass black hole acquires a massive accretion disk by merging with the helium core of its red giant companion. The black hole enters the helium core after it, or its neutron star progenitor, first experiences a common envelope phase that carries it inwards through the hydrogen envelope. Ac

Shigeki Sugimoto

We clarify some ambiguous points in a derivation of duality via brane exchange using M-theory language, and propose a ``proof&#39;&#39; of duality in MQCD. Actually, duality in MQCD is rather trivial and does not need a complicated proof. The problem is how to interpret it in field theory language. We examine BPS states in N=2 theory and find the particle co

Uri Sarid

If the universe is trapped and cooled in a metastable false vacuum state, that state will eventually decay by bubble nucleation and expansion. For example, many extensions of the standard model incorporate new scalar fields whose potential has a local minimum at the origin but a global minimum elsewhere, to which the vacuum will eventually tunnel. I calculat

Paul Fendley

I show that physical quantities in several two-dimensional condensed-matter models are related to the Seiberg-Witten calculation of exact quantities in supersymmetric gauge theory. In particular, the magnetization in the Kondo problem and the current in the boundary sine-Gordon model can each be expressed in the form $\int dx/y$, where for example in the lat

G. Moortgat-Pick, H. Fraas, A. Bartl, W. Majerotto

We study the production of charginos e^+ e^- -> chi^+_i chi^-_j, (i,j=1,2) with polarized beams and the subsequent decays chi^+_i -> chi^0_k ell^+ nu and chi^-_j -> chi^0_l ell^- nu, (k,l=1,...,4), including the complete spin correlations between production and decay. Analytical formulae are presented for the joint spin-density matrix of the charginos, for t

Zurab Kakushadze

We construct a four dimensional chiral N=1 space-time supersymmetric Type I vacuum corresponding to a compactification on a toroidal Z_2 X Z_2 X Z_3 orbifold. Using recent results in four dimensional orientifolds, we argue that this model has a well defined world-sheet description. An interesting feature of this model is that the gauge group contains an SU(6

Biswajoy Brahmachari

We study leptonic CKM mixing matrices when the neutrino Yukawa matrices are antisymmetric which gives rise to mass patterns suitable to explain solar, atmospheric and LSND neutrino oscillation experiments. Taking diagonal leptonic matrices which can give rise to hierarchical lepton masses, we compute the leptonic CKM matrix.

F. Ciesielski, J. Carbonell

The Faddeev-Yakubowsky equations in configuration space have been solved for the four nucleon system. The results with an S-wave interaction model in the isospin approximation are presented. They concern the bound and scattering states below the first three-body threshold. The elastic phase-shifts for the N+NNN reaction in different ($S,T$) channels are give

N. M. R. Peres, P. D. Sacramento, D. K. Campbell, J. M. P. Carmelo

Combining the Bethe Ansatz with a functional deviation expansion and using an asymptotic expansion of the Bethe Ansatz equations, we compute the curvature of levels D_n at any filling for the one-dimensional lattice spinless fermion model. We use these results to study the finite temperature charge stiffness D(T). We find that the curvature of the levels obe

M. Hess, F. Karsch, E. Laermann, I. Wetzorke

We present first results for diquark correlation functions calculated in Landau gauge on the lattice. Masses have been extracted from the long distance behaviour of these correlation functions. We find that the ordering of diquark masses with spin 0 and 1 states in colour anti-triplet and sextet channels is in accordance with instanton motivated interaction

Sergio Scopetta, Vicente Vento, Marco Traini

Using a simple picture of the constituent quark as a composite system of point-like partons, we construct the polarized parton distributions by a convolution between constituent quark momentum distributions and constituent quark structure functions. Using unpolarized data to fix the parameters we achieve good agreement with the polarization experiments for t

Masahiro Nagashima, Naoteru Gouda, Norimasa Sugiura

We investigate the effects of the UV background radiation on galaxy formation by using the semi-analytic model including the photoionization process. The semi-analytic model is based on Cole et al. (1994) and we use almost the same parameters of their `fiducial&#39; model. We find that the UV background mainly affects the formation of dwarf galaxies. Because

V. A. Naumov, L. Perrone

We discuss a simple approach to solve the transport equation for high-energy neutrinos in media of any thickness. We present illustrative results obtained with some specific models for the initial spectra of muon neutrinos and antineutrinos propagating through a normal cold medium.

Kevin M. Obenland, Alvin M. Despain

A Quantum Computer is a new type of computer which can efficiently solve complex problems such as prime factorization. A quantum computer threatens the security of public key encryption systems because these systems rely on the fact that prime factorization is computationally difficult. Errors limit the effectiveness of quantum computers. Because of the expo

Kevin M. Obenland, Alvin M. Despain

A Quantum Computer is a new type of computer which can solve problems such as factoring and database search very efficiently. The usefulness of a quantum computer is limited by the effect of two different types of errors, decoherence and inaccuracies. In this paper we show the results of simulations of a quantum computer which consider both decoherence and i

L. J. Boya, H. Rosu, A. J. Segui-Santonja, F. J. Vila

The connection between the strictly isospectral construction in supersymmetric quantum mechanics and the general zero mode solutions of the Schroedinger equation is explained by introducing slightly generalized first-order intertwining operators. We also present a multiple-parameter generalization of the strictly isospectral construction in the same perspect

Didier A. Depireux, Jonathan Z. Simon, Shihab A. Shamma

We review recent developments in the measurement of the dynamics of the response properties of auditory cortical neurons to broadband sounds, which is closely related to the perception of timbre. The emphasis is on a method that characterizes the spectro-temporal properties of single neurons to dynamic, broadband sounds, akin to the drifting gratings used in

Toru Ohira

We propose here a new model of encryption of binary data taking advantage of the complexity associated with delayed dynamics. In this scheme, the encryption process is a coupling dynamics with various time delays between different bits in the original data. It is shown that decoding of the encrypted data is extremely difficult without a complete knowledge of

J. E. Amaro, J. A. Caballero, T. W. Donnelly, E. Moya de Guerra

The inclusive quasielastic response functions that appear in the scattering of polarized electrons from polarized nuclei are computed and analyzed for several closed-shell-minus-one nuclei with special attention paid to 39K. Results are presented using two models for the ejected nucleon --- when described by a distorted wave in the continuum shell model or b

Alexander Krasulin

This article is a summary of a series of papers to be published where I examine a special kind of geometric objects that can be defined in space-time --- five-dimensional tangent vectors. Similar objects exist in any other differentiable manifold, and their dimension is one unit greater than that of the manifold. Like ordinary tangent vectors, the considered

Liu Zhao

Two general families of new quantum deformed current algebras are proposed and identified both as infinite Hopf family of algebras, a structure which enable one to define ``tensor products&#39;&#39; of these algebras. The standard quantum affine algebras turn out to be a very special case of both algebra families, in which case the infinite Hopf family struc

Tien-Cuong Dinh

Let $D\subset\subset\mathbb{C}^n$ be a complex manifold of dimension $p\geq 2$ with $\C^2$ boundary in $\mathbb{C}^n$. Let $f$ be a $\C^1$ function on $bD$ and $V$ a generic and large enough family of complex $(n-p+1)$-planes. Let suppose that for $ν\in V$, no connected component of $bD\cap \mathbb{C}^{n-p+1}_ν$ is &#34;almost&#34; real analytic and that $f$

Yordan P. Mishev

We show that the well known identity for the Wronskian of squared solutions of a Sturm-Liouville equation follows from the Fay identity. We also study some odd-order (($2^n -1$)-order, $ n = 2, 3, ...$) identities which are specific for tau functions, related to the KdV hierarchy.

Franck Barthe, Matthieu Fradelizi, Bernard Maurey

A unified analytic solution to the Busemann-Petty problem was recently found by Gardner, Koldobsky and Schlumprecht. We give an elementary proof of their formulas for the inverse Radon transform.

Sean M. Bates, William B. Johnson, Joram Lindenstrauss, D. Preiss

New concepts related to approximating a Lipschitz function between Banach spaces by affine functions are introduced. Results which clarify when such approximations are possible are proved and in some cases a complete characterization of the spaces $X$, $Y$ for which any Lipschitz function from $X$ to $Y$ can be so approximated is obtained. This is applied to

V. D. Ivashchuk

A multidimensional gravitational model with several scalar fields, fields of forms and cosmological constant is considered. When scalar fields are constant and composite p-brane monopole-like ansatz for the fields of forms is adopted, a wide class of solutions on product of n+1 Einstein spaces is obtained. These solutions are the composite p-brane generaliza

J. LaChapelle, M. Legare

Super-matrix KdV and super-generalized non-linear Schrodinger equations are shown to arise from a symmetry reduction of ordinary self-dual Yang-Mills equations with supergauge groups

G. Leibbrandt

We use a gauge-invariant regularization procedure, called ``split dimensional regularization&#39;&#39;, to evaluate the quark self-energy $Σ(p)$ and quark-quark-gluon vertex function $Λ_μ(p^\prime,p)$ in the Coulomb gauge, $\vec{\bigtriangledown}\cdot\vec{A}^a = 0$. The technique of split dimensional regularization was designed to regulate Coulomb-gauge Feyn

Konstantin Zyablyuk

We consider the compactification of N=1, D=10 supergravity with E_8 x E_8 Yang-Mills matter to N=1, D=4 model with 3 generations. With help of embedding SU(5)->SO(10)->E_6->E_8 we find the value of the top Yukawa coupling $λ_t=\sqrt{16πα_{GUT}/3}$ at the GUT scale.

Harm Jan Boonstra, Bas Peeters, Kostas Skenderis

We construct a class of intersecting brane solutions with horizon geometries of the form adS_k x S^l x S^m x E^n. We describe how all these solutions are connected through the addition of a wave and/or monopoles. All solutions exhibit supersymmetry enhancement near the horizon. Furthermore we argue that string theory on these spaces is dual to specific super

T. Hambye, R. B. Mann, U. Sarkar

A violation of Local Lorentz Invariance (VLI) and hence the special theory of relativity or a violation of equivalence principle (VEP) in the Kaon system can, in principle, induce oscillations between $K^0$ and $\bar{K}^0$. We construct a general formulation in which simultaneous pairwise diagonalization of mass, momemtum, weak or gravitational eigenstates i

Carl E. Carlson, Christopher D. Carone

We consider the electromagnetic decays of the orbitally-excited SU(6) 70-plet baryons, to compare the predictions of the naive quark model with those of large-N_c QCD. The helicity amplitudes measured in N^* photoproduction are computed in a large-N_c effective field theory, based on a Hartree approximation, and the amplitudes are fit to the current experime

Holger Gies, Walter Dittrich

Within the geometric optics approximation, we derive the light cone condition for a class of homogeneous non-trivial QED vacua using the effective action approach. Our result generalizes the ``unified formula&#39;&#39; suggested by Latorre, Pascual and Tarrach which turns out to be a low-energy limit. We calculate the velocity shifts induced by electromagnet

Helmut Kröger, Norbert Scheu

We present a non-perturbative study of the massive Schwinger model. We use a Hamiltonian approach, based on a momentum lattice corresponding to a fast moving reference frame, and equal time quantization. We present numerical results for the mass spectrum of the vector and scalar particle. We find good agreement with chiral perturbation theory in the strong c

F. Halzen

With an effective telescope area of order 10^4 m^2, a threshold of ~50 GeV and a pointing accuracy of 2.5 degrees, the AMANDA detector represents the first of a new generation of high energy neutrino telescopes, reaching a scale envisaged over 25 years ago. We describe its performance, focussing on the capability to detect halo dark matter particles via thei

L. Herrera, A. Di Prisco, J. Martinez

For slowly rotating fluids, we establish the existence of a critical point similar to the one found for non-rotating systems. As the fluid approaches the critical point, the effective inertial mass of any fluid element decreases, vanishing at that point and changing of sign beyond it. This result implies that first order perturbative method is not always rel

Eanna E Flanagan

In the coming decade, the LIGO/VIRGO/GEO network of ground-based kilometer-scale laser interferometer gravitational wave detectors will open up a new astronomical window on the Universe: gravitational waves in the frequency band 10 to 10^4 Hz. In addition, if the proposed, 5 million kilometer long, space based interferometer LISA flies, another window will b

John Toner, Yuhai Tu

We present a quantitative continuum theory of ``flocking&#39;&#39;: the collective coherent motion of large numbers of self-propelled organisms. Our model predicts the existence of an ``ordered phase&#39;&#39; of flocks, in which all members of the flock move together with the same mean velocity. This coherent motion of the flock is an example of spontaneous

Da-Jiang Liu, John D. Weeks, Daniel Kandel

We model an apparent instability seen in recent experiments on current induced step bunching on Si(111) surfaces using a generalized 2D BCF model, where adatoms have a diffusion bias parallel to the step edges and there is an attachment barrier at the step edge. We find a new linear instability with novel step patterns. Monte Carlo simulations on a solid-on-

Josh P. Kemp, Zheng Yu Chen

We propose a potential for wormlike polymer chains which can be used to model the low-temperature conformational structures. We successfully reproduced helix ground states up to 6.5 helical loops, using the multicanonical Monte Carlo simulation method. We demonstrate that the coil-helix transition involves four distinct phases: coil(gaslike), collapsed globu

S. Sanvito, C. J. Lambert, J. H. Jefferson, A. M. Bratkovsky

We present a numerical study of conductance oscillations of transition metal multilayers as a function of layer thickness. Using a material-specific tight-binding model, we show that for disorder-free layers with random thicknesses but clean interfaces, long-period oscillations in the conductance can occur, which are reminiscent of those found in structures

D. A. Tikhonov, R. V. Polozov, E. G. Timoshenko, Yu. A. Kuznetsov

We propose an efficient numerical algorithm for solving integral equations of the theory of liquids in the Reference Interaction Site Model (RISM) approximation for infinitely dilute solution of macromolecules with a large number of atoms. The algorithm is based on applying the nonstationary iterative methods for solving systems of linear algebraic equations

W. Clauss, D. J. Bergeron, A. T. Johnson

We present atomically-resolved STM images of single-wall carbon nanotubes (SWNTs) embedded in a crystalline nanotube rope. Although they may be interpreted as of a chiral nanotube, the images are more consistently explained a an achiral armchair tube with a quenched twist distortion. The existence of quenched twists in SWNTs in ropes might explain the fact t

P. Singha Deo, V. A. Schweigert, F. M. Peeters

The magnetization behavior of mesoscopic superconducting disks can show hysteretic behavior which we explain by using the Ginzburg-Landau (GL) theory and properly taking into account the de-magnetization effects due to geometrical form factors. In large disks the Bean-Livingston surface barrier is responsible for the hysteresis. While in small disks a volume

P. Fendley, H. Saleur

We establish the existence of an exact non-perturbative self-duality in a variety of quantum impurity problems, including the Luttinger liquid or quantum wire with impurity. The former is realized in the fractional quantum Hall effect, where the duality interchanges electrons with Laughlin quasiparticles. We discuss the mathematical structure underlying this

Martin Holthaus, Eva Kalinowski, Klaus Kirsten

We study the fluctuation of the number of particles in ideal Bose-Einstein condensates, both within the canonical and the microcanonical ensemble. Employing the Mellin-Barnes transformation, we derive simple expressions that link the canonical number of condensate particles, its fluctuation, and the difference between canonical and microcanonical fluctuation

R. Barlovic, L. Santen, A. Schadschneider, M. Schreckenberg

Measurements on real traffic have revealed the existence of metastable states with very high flow. Such states have not been observed in the Nagel-Schreckenberg (NaSch) model which is the basic cellular automaton for the description of traffic. Here we propose a simple generalization of the NaSch model by introducing a velocity-dependent randomization. We in

Mauro Sellitto

We investigate by Montecarlo simulation the linear response function of three dimensional structural glass models defined by short-range kinetic constraints and a trivial equilibrium Boltzmann-Gibbs measure. The breakdown of the fluctuation-dissipation theorem in the glassy phase follows the prediction of mean field low temperature mode-coupling theory.

K. H. Kim, J. H. Jung, T. W. Noh

Temperature dependent optical conductivity spectra of a La0.7Ca0.3MnO3 (LCMO) sample were measured. In the metallic regime at very low temperatures, they clearly showed two types of absorption features, i.e., a sharp Drude peak and a broad mid-infrared absorption band, which could be explained as coherent and incoherent bands of a large lattice polaron. This

O. K. Andersen, C. Arcangeli, R. W. Tank, T. Saha-Dasgupta

We describe the screened Korringa-Kohn-Rostoker (KKR) method and the third-generation linear muffin-tin orbital (LMTO) method for solving the single-particle Schroedinger equation for a MT potential. The simple and popular formalism which previously resulted from the atomic-spheres approximation (ASA) now holds in general, that is, it includes downfolding an

Leonid B. Litinsky

A set of fixed points of the Hopfield type neural network is under investigation. Its connection matrix is constructed with regard to the Hebb rule from a highly symmetric set of the memorized patterns. Depending on the external parameter the analytic description of the fixed points set has been obtained.

Aiichi Iwazaki

Under quite plausible assumptions on double-layer quantum Hall states with strong interlayer correlation, we show in general framwork that coherent tunneling of a single electron between two layers is possible. It yields Josephson effects with unit charge tunneling. The origin is that Halperin states in the quantum Hall states are highly degenerate in electr

P. J. Hirschfeld, P. Wölfle

We consider, within BCS weak coupling theory, the instability of a $d_{x^2-y^2}$-wave superconductor to a state of mixed symmetry $d+iq$, $q=d_{xy},s$. In zero magnetic field we show that there is a large and physically reasonable range of interaction strengths for which a pure $d_{x^2-y^2}$ state is stable down to T=0. In this case a magnetic field, assumed

Piero Olla, Paolo Paradisi

We use multiscale-multispace correlations and Fourier transform techniques, to study some intermittent random field properties, which escape analysis by structure function scaling. These properties are parametrized in terms of a set of scale ratios, giving the typical interaction distances in space and scale of the random field fluctuations, and the characte

Martin Greiner, Juergen Schmiegel, Felix Eickemeyer, Peter Lipa

The n-point statistics of singularity strength variables for multiplicative branching processes is calculated from an analytic expression of the corresponding multivariate generating function. The key ingredient is a branching generating function which can be understood as a natural generalisation of the multifractal mass exponents. Various random multiplica

Nils Berglund

We give a nontechnical description of the behaviour of dynamical systems governed by two distinct time scales. We discuss in particular memory effects, such as bifurcation delay and hysteresis, and comment the scaling behaviour of hysteresis cycles. These properties are illustrated on a few simple examples.

A. Lazarian, Ethan T. Vishniac

We discuss the role of tearing instabilities in magnetic reconnection. In three dimensions this instability leads to the formation of strong Alfvenic waves that remove plasma efficiently from the reconnection layer. As a result the instability proceeds at high rates while staying close to the linear regime. Our calculations show that for a resistive fluid th

Crystal L. Martin

Images and longslit, echelle spectra of the \Ha emission from 14 dwarf galaxies and M82 have been used to identify expanding shells of ionized gas. Supershells (radius $>~300$ pc) are found in 12 of the dwarfs. The measured shell sizes and expansion speeds constrain the ages and power requirements of the bubbles. The dynamical age of the larger bubbles is ty