September 1997 arXiv papers — page 7

Markus Eidemueller, Matthias Jamin

The gauge invariant two-point correlation function of the gauge field strength tensor is calculated in perturbation theory at the next-to-leading order. Besides a direct calculation in perturbative QCD we also present a derivation of the correlation function in the heavy quark effective theory. Our results are briefly compared with recent determinations of t

Khalil M. Bitar

We present further data in search of a parity-flavor-breaking phase in simulations of dynamical QCD with two flavors of light Wilson fermions in the strong coupling region. This is done on lattice sizes of 4^4 an up to 10^4 for a variety of values of beta and kappa as well as the coefficient, h, of an explicit breaking term included in the action. We confirm

V. Gimenez

The B-$\bar B$ mixing, B-meson lifetimes, the $B_{s}$-$\bar{B}_{s}$ lifetime difference and SUSY FCNC effects in $ΔB=2$ processes are very important measurable quantities in B-meson phenomenology whose theoretical predictions depend on unknown matrix elements of several four-fermion operators. We present preliminary results for the matrix elements of the rel

G. DiCecio, A. Hart, R. W. Haymaker

We derive an Ehrenfest theorem for SU(2) lattice gauge theory which, after Abelian projection, relates the Abelian field strength and a dynamical electric current and defines these operators for finite lattice spacing. Preliminary results from the ongoing numerical test of the relation are presented, including the contributions from gauge fixing and the Fadd

R. W. Johnson, M. Teper

The spectrum for the pure gauge sector is calculated for an extended Isgur-Paton model in 2+1 and 3+1 dimensions and compared to recent lattice calculations of the glueball spectrum. The IP model is extended by inclusion of a rigidity (curvature) term and, in D=2+1, mixing through a higer topological contribution. For a choice of parameterizations, near quan

Stephen M. Pickles, UKQCD Collaboration

Computing quark propagators in lattice QCD is equivalent to solving large, sparse linear systems with multiple right-hand sides. Block algorithms attempt to accelerate the convergence of iterative Krylov-subspace methods by solving the multiple systems simultaneously. This paper compares a block generalisation of the quasi-minimal residual method (QMR), Bloc

Claude Roiesnel

We present and discuss the results of a Monte-Carlo simulation of the phase transition in pure compact U(1) lattice gauge theory with Wilson action on a hypercubic lattice with periodic boundary conditions. The statistics are large enough to make a thorough analysis of the size dependence of the gap. In particular we find a non-zero latent heat in the infini

I. Montvay

The motivation and perspectives of numerical simulations of supersymmetric Yang-Mills theories are reviewed.

H. G. Ballesteros, L. A. Fernandez, V. Martin-Mayor, A. Munoz Sudupe

We study the four dimensional site-diluted Ising model using finite-size scaling techniques. We explore the whole parameter space (density-coupling) in order to determine the Universality Class of the transition line. Our data are compatible with Mean Field behavior plus logarithmic corrections.

Stefan Soldner-Rembold

The structure of the photon is studied in photon interactions at high energies using photons radiated by the electron and positron beams at LEP. The current status of these measurements is reviewed.

Radu Ionicioiu

In this letter we show that in a Kaluza-Klein framework we can have arbitrary topology change between the macroscopic (i.e. noncompactified) spacelike 3-hypersurfaces. This is achieved by using the compactified dimensions as a catalyser for topology change. In the case of odd-dimensional spacetimes (such as the 11-dimensional M-theory) this is always possibl

Philippe Jetzer, David Scialom

We discuss spherically symmetric static solutions of the Einstein-Klein-Gordon equations for a real scalar field with a mass and a quartic self-interaction term. As for the massless case the solutions have a naked singularity at the origin. However, linear stability analysis shows that these solutions as well as the massless ones are dynamically unstable.

Takashi Tamaki, Takashi Torii, Kei-ichi Maeda

We find a black hole solution with non-Abelian field in Brans-Dicke theory. It is an extension of non-Abelian black hole in general relativity. We discuss two non-Abelian fields: "SU(2)" Yang-Mills field with a mass (Proca field) and the SU(2)$\times$SU(2) Skyrme field. In both cases, as in general relativity, there are two branches of solutions, i.e

Josef Dorfmeister, Guido Haak

We investigate the dressing action on surfaces of constant mean curvature (CMC surfaces) in Euclidean space. In particluar, we show that for CMC surfaces with umbilics the isotropy group under dressing is always trivial. This result is applied to the investigation of CMC surfaces whose metric is invariant under a group of automorphisms of the parameter domai

Yutaka Hosotani

An S=1/2 anti-ferromagnetic spin chain is mapped to the two-flavor massless Schwinger model, which admits a gapless mode. In a spin ladder system rung interactions break the chiral invariance. These systems are solved by bosonization. If the number of legs in a cyclically symmetric ladder system is even, all of the gapless modes of spin chains become gapful.

Subir Sachdev

In an earlier work, Damle and the author (Phys. Rev. B in press; cond-mat/9705206) demonstrated the central role played by incoherent, inelastic processes in transport near two-dimensional quantum critical points. This paper extends these results to the case of a quantum transition in an anyon gas between a fractional quantized Hall state and an insulator, i

F. Marsiglio, J. P. Carbotte

We compute the single-particle inverse lifetime, along with the conductivity-derived scattering rate, for a metallic system in an s-wave superconducting state. When both electron-phonon and electron-impurity scattering are included, we find that while these scattering rates are in qualitative agreement, in general quantitative agreement is lacking. We also d

G. Wellein, B. B"auml, H. Fehske

We examine the effects of hole-phonon interaction on the formation of hole pairs in the 2D Holstein t--J model. Using finite-lattice diagonalization techniques, we present exact results for the two-hole binding energy and the s-- and d-wave pairing susceptibilities.

Murray T. Batchelor

A set of fixed boundary weights for both the critical dense and dilute A_L face models is constructed from the known boundary weights of the related loop model. The surface operator content and the conformal partition functions then follow from the results obtained via the Bethe equations.

M. R. Jarvis, I. D. White, R. W. Godby, M. C. Payne

We study the behaviour of total-energy supercell calculations for dipolar molecules and charged clusters. Using a cutoff Coulomb interaction within the framework of a plane-wave basis set formalism, with all other aspects of the method (pseudopotentials, basis set, exchange-correlation functional) unchanged, we are able to assess directly the interaction eff

Caroline Lyon, Stephen Brown

This paper introduces an objective metric for evaluating a parsing scheme. It is based on Shannon's original work with letter sequences, which can be extended to part-of-speech tag sequences. It is shown that this regular language is an inadequate model for natural language, but a representation is used that models language slightly higher in the Chomsky

Ramakrishna Ramaswamy

Strange nonchaotic attractors (SNAs), which are realized in many quasiperiodically driven nonlinear systems are strange (geometrically fractal) but nonchaotic (the largest nontrivial Lyapunov exponent is negative). Two such identical independent systems can be synchronized by in-phase driving: because of the negative Lyapunov exponent, the systems converge t

Matthew A. Bershady, Steven R. Majewski, David C. Koo, Richard G. Kron

Through use of multiband (U, B, R, I) photometry we have isolated high redshift (3.0<z<3.5) galaxy candidates in a survey of 1.27 deg^2 to R = 21.25 and a survey of 0.02 deg^2 to R = 23.5. Our pool of candidates constrains the nature of the 3.0 < z < 3.5 luminosity function over the range L* < L < 100 L*, if we grant a similar level of completeness to these

Mark W. Sincell, Julian H. Krolik

We present an improved calculation of the vertical structure and ultraviolet spectrum of a dissipative accretion disk in an AGN. We calculate model spectra in which the viscous stress is proportional to the total pressure, the gas pressure only and the geometric mean of the radiation and gas pressures (cf. Laor & Netzer 1989: LN89). As a result of a more com

J. A. Tomsick, I. Lapshov, P. Kaaret

An x-ray dip was observed during a 1996 Rossi X-Ray Timing Explorer observation of the recurrent x-ray transient 4U 1630-47. During the dip, the 2-60 keV x-ray flux drops by a factor of about three, and, at the lowest point of the dip, the x-ray spectrum is considerably softer than at non-dip times. We find that the 4U 1630-47 dip is best explained by absorp

Michael J. Ledlow, Frazer N. Owen, William C. Keel

We report the discovery of a powerful (~10^{24} Watts/Hz) FR I radio source in a highly flattened disk-dominated galaxy. Half of the radio flux from this source is concentrated within the host galaxy, with the remainder in a pair of nearly symmetrical lobes with total extent ~200kpc nearly perpendicular to the disk. The traditional wisdom maintains that powe

Philippe Jetzer

One of the most important problems in astrophysics concerns the nature of the dark matter in galactic halos, whose presence is implied mainly by the observed flat rotation curves in spiral galaxies. In the framework of a baryonic scenario the most plausible candidates are brown dwarfs, M-dwarfs or white dwarfs and cold molecular clouds (mainly of $H_2$). The

A. W. Strong, I. V. Moskalenko

An extensive program for the calculation of galactic cosmic-ray propagation has been developed. This is a continuation of the work described in Strong & Youssefi (1995). The main motivation for developing this code is the prediction of diffuse Galactic gamma rays for comparison with data from the CGRO instruments EGRET, COMPTEL, and OSSE. The basic spatial p

V. G. Gurzadyan, A. Mazure

The results of the analysis of the subclustering in a sample of ESO Nearby Abell Cluster Survey (ENACS) galaxy clusters, with data complemented from other studies, are presented. The analysis is performed by using the S-tree method enabling one to study the hierarchical properties of clusters, namely by the detection of the main physical cluster and of its s

Kazuhiro Yamamoto, Naoshi Sugiyama, Humitaka Sato

The fluid equations for the baryon-electron system in an expanding universe are derived from the Boltzmann equation. The effect of the Compton interaction is taken into account properly in order to evaluate the photon-electron collisional term. As an application, the acoustic motions of the baryon-electron system after recombination are investigated. The eff

H. Ezawa, Y. Fukazawa, K. Makishima, T. Ohashi

A large-scale gradient in the metal abundance has been detected with ASCA from an X-ray bright cluster of galaxies AWM7. The metal abundance shows a peak of 0.5 solar at the center and smoothly declines to <~ 0.2 solar at a radius of 500 kpc. The gas temperature is found to be constant at 3.8 keV. The radial distribution of iron can be fit with a beta-model

Simon Portegies Zwart, Marco Kouwenhoven, Alastair Reynolds

The absence or presence of extremely wide binaries with a radio pulsar and an optical counterpart imposes a strong constraint on the existence and magnitude of kicks in supernova explosions. We search for such systems by comparing the positions of radio pulsars which are not known to be in binaries with the positions of visible stars, and find that the numbe

S. C. Tripathy, J. Christensen-Dalsgaard

Despite recent major advances, the opacity remains a source of substantial uncertainty in the calculation of solar models, and hence of solar oscillation frequencies. Hence it is of substantial interest to investigate the sensitivity of solar structure to changes in the opacity. Furthermore, we may hope from the precise helioseismic inferences of solar struc

Audra Baleisis, Ofer Lahav, Andrew J. Loan, Jasper V. Wall

(Abridged Abstract) We calculate the expected amplitude of the dipole and higher spherical harmonics in the angular distribution of radio galaxies. The median redshift of radio sources in existing catalogues is z=1, which allows us to study large scale structure on scales between those accessible to present optical and infrared surveys, and that of the Cosmi

M. Kachelriess

We considered recently as a new axion production mechanism the process $e^- \to e^- +a$ in a strong magnetic field $B$. Requiring that for a strongly magnetized neutron star the axion luminosity is smaller than the neutrino luminosity we obtained the bound $g_{ae} \lsim 10^{-10}$ for the axion electron coupling constant. This limit is considerably weaker tha

Hironobu Ishihara

A new genus $g=g(X,\ce)$ is defined for the pairs $(X,\ce)$ that consist of $n$-dimensional compact complex manifolds $X$ and ample vector bundles $\ce$ of rank $r$ less than $n$ on $X$. In case $r=n-1$, $g$ is equal to curve genus. Above pairs $(X,\ce)$ with $g$ less than two are classified. For spanned $\ce$ it is shown that $g$ is greater than or equal to

Yoshiaki Fukuma, Hironobu Ishihara

Let $X$ be a compact complex manifold of dimension $n\ge 2$ and $\ce$ an ample vector bundle of rank $r<n$ on $X$. As the continuation of Part I, we further study the properties of $g(X,\ce)$ that is an invariant for pairs $(X,\ce)$ and is equal to curve genus when $r=n-1$. Main results are the classifications of $(X,\ce)$ with $g(X,\ce)=2$ (resp. 3) when $\

Igor R. Klebanov

We review two types of D-branes processes where open strings are created. In the first type, a closed string incident on a collection of D-branes is converted into a number of open strings running along them. For the case of threebranes we compare the leading absorption rate with that in semiclassical gravity, and find exact agreement. A supersymmetric non-r

John C. Baez

While the use of spin networks has greatly improved our understanding of the kinematical aspects of quantum gravity, the dynamical aspects remain obscure. To address this problem, we define the concept of a `spin foam&#39; going from one spin network to another. Just as a spin network is a graph with edges labeled by representations and vertices labeled by i

B. Alles, G. Boyd, M. D&#39;Elia, A. Di Giacomo

We present preliminary results on the proton spin structure function in full QCD. The measurement has been done using 4 flavours of staggered fermions and an improved definition of the lattice topological charge density.

Duane A. Dicus, Chung Kao, Wayne W. Repko

We use the behavior of the photon-photon scattering for photon energies $ω$ less than the electron mass, $m_e$, to examine the implications of treating the Euler-Heisenberg Lagrangian as an effective field theory. Specifically, we determine the $ω^2/m_e^2$ behavior of the scattering amplitude predicted by including one-loop corrections to the Euler-Heisenber

James L. Anderson

Approximate asymptotic conditions on the motion of compact, electrically charged particles are derived within the framework of general relativity using the Einstein- Infeld-Hoffmann (EIH) surface integral method. While superficially similar to the Abraham-Lorentz and Lorentz-Dirac (ALD) equations of motion, these conditions differ from them in several fundam

Ovidiu Costin

We extend the technique of asymptotic series matching to exponential asymptotics expansions (transseries) and show that the extension provides a method of finding singularities of solutions of nonlinear differential equations, using asymptotic information. This transasymptotic matching method is applied to Painlevé&#39;s first equation. The solutions of P1 t

Gustavo Dotti

The matching of global anomalies of a supersymmetric gauge theory and its dual is seen to follow from similarities in their classical chiral rings. These similarities provide a formula for the dimension of the dual gauge group. As examples we derive &#39;t Hooft consistency conditions for the duals of supersymmetric QCD and SU(N) theories with matter in the

Ashoke Sen

We show how F-theory on a Calabi-Yau (n+1)-fold, in appropriate limit, can be identified as an orientifold of type IIB string theory compactified on a Calabi-Yau n-fold.

H. Ghafarnejad, H. Salehi

The Hadamard renormalization prescription is used to derive a two dimensional analog of the renormalized stress tensor for a minimally coupled scalar field in Schwarzschild-de Sitter space time. In the two dimensional analog the minimal coupling reduces to the conformal coupling and the stress tensor is found to be determined by the (nonlocal) contribution o

Hadi Salehi

A dynamical theory is studied in which a scalar field $ϕ$ in Einstein- Minkowski space is coupled to the four-velocity $N_μ$ of a preferred inertial observer in that space. As a consistent requirement on this coupling we study a principle of duality invariance of the dynamical mass- term of $ϕ$ at some universal length in the small-distance regime. In the la

Dmitri V. Shirkov

General aspects of fundamental physics are considered. We comment the Wigner&#39;s logical scheme and modify it to adjust to modern theoretical physics. Then, we discuss the role and indicate the place of renormalization group in the logic of fundamental physics.

S. Oda, N. Tsuda, T. Yukawa

The string susceptibility exponents of dynamically triangulated 2-dimensional surfaces with various topologies, such as a sphere, torus and double-torus, were calculated by the grand-canonical Monte Carlo method. These simulations were made for surfaces coupled to $d$-Ising spins ($d$=0,1,2,3,5). In each simulation the area of surface was constrained to with

T. Hotta, T. Izubuchi, J. Nishimura

We study the domain-wall formalism with additional Majorana mass term for the unwanted zero mode, which has recently been proposed for lattice construction of 4D N=1 super Yang-Mills theory without fine-tuning. Switching off the gauge field, we study the dispersion relation of the energy eigenstates numerically, and find that the method works for reasonable

G. Sardanashvily

Dirac fermion fields are responsible for spontaneous symmetry breaking in gauge gravitation theory because the spin structure associated with a tetrad field is not preserved under general covariant transformations. Two solutions of this problem can be suggested. (i) There exists the universal spin structure $S\to X$ such that any spin structure $S^h\to X$ as

Andrey V. Chubukov, Dirk K. Morr

We revisit the problem of the dispersion of a single hole injected into a quantum antiferromagnet. We applied a spin-density-wave formalism extended to a large number of orbitals and obtained an integral equation for the full quasiparticle Green&#39;s function in the self-consistent &#34;non-crossing&#34; Born approximation. We found that for $t/J \gg 1$, th

H. Srikanth, S. Sridhar, D. A. Gajewski, M. B. Maple

We report measurements of the surface impedance $Z_s=R_s+iX_s$ of $(Pr_xY_{1-x})Ba_2Cu_3O_{7-δ}$, $(x=0,0.15,0.23,0.3,0.4,0.5)$. Increasing $Pr$ concentration leads to some striking results not observed in samples doped by non-magnetic constituents. The three principal features of the $R_s(T)$ data - multiple structure in the transition, a high residual resi

D. C. Ralph, V. Ambegaokar

The Adriatico Research Conference on Superconductivity, Andreev Reflection, and Proximity Effect in Mesoscopic Structures took place at the International Center for Theoretical Physics in Trieste, Italy, July 8-11, 1997. The organizers were Elias Burstein, Leonid Glazman, Teun Klapwijk, and Subodh R. Shenoy. We describe some of the central issues discussed a

Bozhidar Z. Iliev

A geometric interpretation of curvature and torsion of linear transports along paths is presented. A number of (Bianchi type) identities satisfied by these quantities are derived. The obtained results contain as special cases the corresponding classical ones concerning curvature and torsion of linear connections.

Bozhidar Z. Iliev

Generalized are the investigated in other works of the author transports along paths in fibre bundles to transports along arbitrary maps in them. Their structure and some properties are studied. Special attention is paid to the linear case and the case when the map&#39;s domain is a Cartesian product of two sets. Also considered are the consistency with bund

Wenjun Zheng, Yue Yu, Zhao-bin Su

In this paper, we present a phenomenological picture based on the composite fermion theory, in responding to the recent discovery by Shahar et al. of a new transport regime near the transition from a $ν=1$ quantum Hall liquid to a Hall insulator(ref[8]). In this picture, the seemingly unexpected reflection symmetry in the longitudinal resistivity $ρ_{xx}$ ca

Paolo Aschieri, Leonardo Castellani, Antonio Maria Scarfone

We construct differential calculi on multiparametric quantum orthogonal planes in any dimension N. These calculi are bicovariant under the action of the full inhomogeneous (multiparametric) quantum group ISO_{q,r}(N), and do contain dilatations. If we require bicovariance only under the quantum orthogonal group SO_{q,r}(N), the calculus on the q-plane can be

M. Lakshmanan, R. Myrzakulov, S. Vijayalakshmi, A. K. Danlybaeva

It is shown that a class of important integrable nonlinear evolution equations in (2+1) dimensions can be associated with the motion of space curves endowed with an extra spatial variable or equivalently, moving surfaces. Geometrical invariants then define topological conserved quantities. Underlying evolution equations are shown to be associated with a tria

D. Cule, T. Hwa

The pinning of an inhomogeneous elastic medium by a disordered substrate is studied analytically and numerically. The static and dynamic properties of a $D$-dimensional system are shown to be equivalent to those of the well known problem of a $D$-dimensional random manifold embedded in $(D+D)$-dimensions. The analogy is found to be very robust, applicable to

Ziqiang Wang

We study the phase structure and Hall conductance quantization in weakly coupled multi-layer electron systems in the integer quantum Hall regime. We derive an effective field theory and perform a two-loop renormalization group calculation. It is shown that (i) finite interlayer tunnelings (however small) give rise to successive metallic and insulating phases

Stephane Courteau

We present optical long-slit rotation curves (RCs) for 304 northern Sb-Sc UGC galaxies originally selected for Tully-Fisher (TF) applications. 20% of the galaxies were observed twice or more, allowing for a proper determination of systematic errors. Various measures of maximum rotational velocity to be used as input in the TF relation are tested on the basis

Hai-Yang Cheng, Chi-Yee Cheung, Chien-Wen Hwang, Wei-Min Zhang

In this paper we construct a covariant light-front model of heavy mesons within the framework of heavy quark effective theory (HQET). The covariant model consists of the light-front heavy meson bound states constructed in the heavy quark limit with heavy quark symmetry and heavy quark effective theory as its basis. Within this model, the Isgur-Wise function

Jonathan L. Feng, Takeo Moroi, Hitoshi Murayama, Erhard Schnapka

We study the physics of spontaneously broken family symmetries acting on the third generation. Massless familons (or Majorons) $f$ associated with such broken symmetries are motivated especially by cosmological scenarios with decaying tau neutrinos. We first note that, in marked contrast with the case for the first two generations, constraints on third gener

M. Lakshmanan

Integrability and chaos are two of the main concepts associated with nonlinear physical systems which have revolutionized our understanding of them. Highly stable exponentially localized solitons are often associated with many of the important integrable nonlinear systems while motions which are sensitively dependent on initial conditions are associated with

D. J. Broadhurst

A rational Ansatz is proposed for the generating function $\sum_{j,k} β_{2j+k,2j}x^j y^k$, where $β_{m,u}$ is the number of primitive chinese character diagrams with $u$ univalent and $2m-u$ trivalent vertices. For $P_m:=\sum_{u\ge2}β_{m,u}$, the conjecture leads to the sequence $$1,1,1,2,3,5,8,12,18,27,39,55,\underline{78,108,150,207,284,388,532,726}$$ for

Teiji Kunihiro

We give a comprehensive review of the renormalization group method for global and asymptotic analysis, putting an emphasis on the relevance to the classical theory of envelopes and the existence of invariant manifolds of the dynamics under consideration. We clarify that an essential point of the method is to convert the problem from solving differential equa

Oe. Elgaroey, L. Engvik, E. Osnes, M. Hjorth-Jensen

We present solutions of the coupled, non-relativistic $^3S_1$-$^3D_1$ gap equations for neutron-proton pairing in symmetric nuclear matter, and estimate relativistic effects by solving the same gap equations modified according to minimal relativity and using single-particle energies from a Dirac-Brueckner-Hartree-Fock calculation. As a main result we find th

A. Bonanno, D. Zappala&#39;

A momentum dependent projection of the Wegner-Hougton equation is derived for a scalar theory coupled to an external field. This formalism is useful to discuss the phase diagram of the theory. In particular we study some properties of the Gaussian fixed point.

Elisabeth Kraus

We give the renormalization of the standard model of electroweak interactions to all orders of perturbation theory by using the method of algebraic renormalization, which is based on general properties of renormalized perturbation theory and not on a specific regularization scheme. The Green functions of the standard model are uniquely constructed to all ord

Martin Haft

On basis of an algebraic analysis of symmetry breaking in general and the Higgs mechanism in the standard model of elementary particles we generalize the concept of symmetry breaking to systems with non-compact groups but not necessarily caused by a potential. Thereto we give some simple, but unfamiliar examples of symmetry breaking with and without potentia

Tohru Eguchi, Masao Jinzenji, Chuan-Sheng Xiong

In our previous article we have proposed that the Virasoro algebra controls the quantum cohomology of Fano varieties at all genera. In this paper we construct a free field description of Virasoro operators and quantum cohomology. We shall show that to each even (odd) homology class of a Kähler manifold we have a free bosonic (fermionic) field and Virasoro op

V. P. Maslov, O. Yu. Shvedov

Semiclassical approximation based on extracting a c-number classical component from quantum field is widely used in the quantum field theory. Semiclassical states are considered then as Gaussian wave packets in the functional Schrodinger representation and as Gaussian vectors in the Fock representation. We consider the problem of divergences and renormalizat

F. Berends, T. Bowcock, D. Charlton, P. Clarke

The working group discussed several aspects of triple gauge coupling analysis viewed in the light of experiences with the first high energy data recorded at energies above the W pair threshold. Some analysis methods were reviewed briefly, and consideration given to better ways of characterising the data. The measurement of CP violating parameters was discuss

H. Leutwyler

Talk given at QCD 97, Montpellier, July 1997. In the first part of the talk, I presented a review of the results for the light quark masses obtained on the basis of chiral perturbation theory. As this material is described elsewhere, the following notes only concern the second part, which dealt with the behaviour of the effective theory in the large N_c limi

H. Leutwyler

The available experimental information is consistent with the Weinberg predictions for the threshold parameters of pi-pi-scattering. The data, however, only test those relations that are insensitive to the quark masses m_u and m_d. Recent theoretical progress leads to remarkably sharp predictions for the behaviour of the S- and P-wave phase shifts in the ela

B. Alles, M. D&#39;Elia, A. Di Giacomo, R. Kirchner

New results on the topology of the SU(2) Yang-Mills theory are presented. At zero temperature we obtain the value of the topological susceptibility by using the recently introduced smeared operators as well as a properly renormalized geometric definition. Both determinations are in agreement. At non-zero temperature we study the behaviour of the topological

T. Hotta, T. Izubuchi, J. Nishimura

We study four-dimensional simplicial gravity through numerical simulation with special attention to the existence of singular vertices, in the strong coupling phase, that are shared by abnormally large numbers of four-simplices. We attempt to cure this disease by adding a term to the action which suppresses such singular vertices. For a sufficiently large co

G. Thorleifsson, B. Petersson

We introduce a simple model of touching random surfaces, by adding a chemical potential rho for ``minimal necks&#39;&#39;, and study this model numerically coupled to a Gaussian model in d-dimensions (for central charge c = d = 0, 1 and 2). For c <= 1, this model has a phase transition to branched polymers, for sufficiently large rho. For c = 2, however, the

Bozhidar Z. Iliev

We investigate the validity of the equivalence principle along paths in gravitational theories based on derivations of the tensor algebra over a differentiable manifold. We prove the existence of local bases, called normal, in which the components of the derivations vanish along arbitrary paths. All such bases are explicitly described. The holonomicity of th

B. Schnurr, F. Gittes, F. C. MacKintosh, C. F. Schmidt

We have developed a new technique to measure viscoelasticity in soft materials such as polymer solutions, by monitoring thermal fluctuations of embedded probe particles using laser interferometry in a microscope. Interferometry allows us to obtain power spectra of fluctuating beads from 0.1 Hz to 20 kHz, and with sub-nanometer spatial resolution. Using linea

Yuji Aoki, Jun Urakawa, Hitoshi Sugawara, Hideyuki Sato

To investigate the non-Fermi liquid (NFL) behavior in a nonalloyed system CeNi_2Ge_2, we have measured the temperature and field dependences of the specific heat C on a CeNi_2Ge_2 single crystal. The distinctive temperature dependence of C/T (~a-b*T^(1/2)) is destroyed in almost the same manner for both field directions of B//c-axis and B//a-axis. The overal

F. Gittes, B. Schnurr, P. D. Olmsted, F. C. MacKintosh

We describe a high-resolution, high-bandwidth technique for determining the local viscoelasticity of soft materials such as polymer gels. Loss and storage shear moduli are determined from the power spectra of thermal fluctuations of embedded micron-sized probe particles, observed with an interferometric microscope. This provides a passive, small-amplitude me

H. M. Ohlenbusch, T. Aste, B. Dubertret, N. Rivier

We analyze the structure of two dimensional disordered cellular systems generated by extensive computer simulations. These cellular structures are studied as topological trees rooted on a central cell or as closed shells arranged concentrically around a germ cell. We single out the most significant parameters that characterize statistically the organization

M. L. Lyra, C. Tsallis

Power-law sensitivity to initial conditions at the edge of chaos provides a natural relation between the scaling properties of the dynamics attractor and its degree of nonextensivity as prescribed in the generalized statistics recently introduced by one of us (C.T.) and characterized by the entropic index $q$. We show that general scaling arguments imply tha

Jay J. Jiang, David W. Conrath

This paper presents a new approach for measuring semantic similarity/distance between words and concepts. It combines a lexical taxonomy structure with corpus statistical information so that the semantic distance between nodes in the semantic space constructed by the taxonomy can be better quantified with the computational evidence derived from a distributio

K. Murali, M. Lakshmanan

By considering generalized synchronizable chaotic systems, the drive-auxiliary system variables are combined suitably using encryption key functions to obtain a compound chaotic signal. An appropriate feedback loop is constructed in the response-auxiliary system to achieve synchronization among the variables of the drive-auxiliary and response-auxiliary syst

Todd A. Small, Wallace L. W. Sargent, Charles C. Steidel

(abridged) Steidel & Sargent (1991a) found that the spectra of the components of the close quasar pairs Q1634+267A,B and Q2345+007A,B were in each case remarkably similar but that individual broad emission lines due to Ly_alpha, Si IV, C IV, and C III] exhibited differences in profile or equivalent width between the A and B components. If the A and B compone

T. Minezaki, Y. Kobayashi, Y. Yoshii, B. A. Peterson

We present new K-band galaxy number counts from K=13 to 20.5 obtained from $K&#39;$-band surveys in the south galactic pole region, which cover 180.8 arcmin$^2$ to a limiting magnitude of K=19, and 2.21 arcmin$^2$ to K=21. These are currently the most precise K-band galaxy counts at $17.5<K<19.0$ because the area of coverage is largest among the existing sur

Jounghun Lee, Sergei F. Shandarin

An analytic approximation to the mass function for gravitationally bound objects is presented. We base on the Zel&#39;dovich approximation to extend the Press-Schechter formalism to a nonspherical dynamical model. A simple extrapolation of that approximation suggests that the gravitational collapse along all three directions which eventually leads to the for

Tanmay Vachaspati

It is shown that purely bosonic field theories can have configurations with half-integral angular momentum even when the topological magnetic charge of the configuration vanishes. This result is applicable whenever there is a non-Abelian gauge theory with particles that transform in the fundamental representation of the non-Abelian symmetry group.

Ori J. Ganor

We study consistency conditions on a M(atrix)-model which would describe M-theory on $T^6$. We argue that there is a limit in moduli space for which it becomes a 6+1D theory and study the low-energy description of extended objects in the decompactified limit. We discuss the requirements from a M(atrix)-model which would describe such an $E_{6(6)}$ theory. We

David H. Adams

The semiclassical approximation for the partition function in Chern-Simons gauge theory is derived using the invariant integration method. Volume and scale factors which were undetermined and had to be fixed by hand in previous derivations are automatically taken account of in this framework. Agreement with Witten&#39;s exact expressions for the partition fu

Laurent Lellouch

We derive rigorous lower bounds for the combinations of light quark masses (m_s+m_u) and (m_d+m_u).

J. -M. Gerard, G. Lopez Castro

The gamma^* --> gamma pi^0 transition measured at different photon virtualities already provides us with a clean test for the behaviour of the pi^0 gamma^* gamma off-shell axial anomaly at large time-like squared momenta. It also allows reliable predictions for the branching ratio of heavy quarkonium decays into omega pi^0.

Simon Schultz, Alessandro Treves

The information that a pattern of firing in the output layer of a feedforward network of threshold-linear neurons conveys about the network&#39;s inputs is considered. A replica-symmetric solution is found to be stable for all but small amounts of noise. The region of instability depends on the contribution of the threshold and the sparseness: for distribute

A. Juozapavicius, S. Caprara, A. Rosengren

The spin-1/2 quantum Ising chain in a transverse random magnetic field is studied by means of the density-matrix renormalization group. The system evolves from an ordered to a paramagnetic state as the amplitude of the random field is increased. The dependence of the magnetization on a uniform magnetic field in the z direction and the spontaneous magnetizati

J. W. van Holten

In this paper we consider classical point particles in full interaction with an arbitrary number of dynamical scalar and (abelian) vector fields. It is shown that the requirement of stability ---vanishing self-force--- is sufficient to remove the well-known inconsistencies of the classical theory: the divergent self-energy, as well as the failure of Lorentz-

Jun-ichiro Kishine, Kenji Yonemitsu

Effects of the interladder one-particle hopping, $t_{\perp}$, on the low-energy asymptotics of a weakly coupled Hubbard ladder system have been studied, based on the perturbative renormalization-group approach. We found that for finite intraladder Hubbard repulsion, $U$, there exists a crossover value of the interladder one-particle hopping, $t_{\perp c}$. F

Hongsu Kim

In the homogeneous and isotropic Friedmann-Robertson-Walker minisuperspace model, it is known that there are no Euclidean wormhole solutions in the pure gravity system. Here it is demonstrated explicitly that in Taub cosmology, which is one of the simplest anisotropic cosmology models, wormhole solutions do exist in pure general relativity in both classical