November 1996 arXiv papers — page 9

Leith Cooper, Ian I. Kogan, Kai-Ming Lee

In this letter we show how string winding modes can be constructed using topological membranes. We use the fact that monopole-instantons in compact topologically massive gauge theory lead to charge non-conservation inside the membrane which, in turn, enables us to construct vertex operators with different left and right momenta. The amount of charge non-cons

Jacques Distler, Amihay Hanany

Type IIB strings compactified on K3 have a rich structure of solitonic strings, transforming under SO(21,5,Z). We derive the BPS tension formula for these strings, and discuss their properties, in particular, the points in the moduli space where certain strings become tensionless. By examining these tensionless string limits, we shed some further light on th

A. V. Anisovich, V. V. Anisovich, A. V. Sarantsev

Basing on the results of the K-matrix fit of $(IJ^{PC}=00^{++})$ wave, we analyze the analytic structure of the amplitude and $q \bar q$/glueball content of resonances in the mass region 1200-1900 MeV, where an extra state for $q \bar q$-systematics exists being a good candidate for the lightest scalar glueball. Our analysis shows that the pure glueball stat

U. Baur, S. Keller, D. Wackeroth

We present some results of a new calculation of the O(alpha) electroweak radiative corrections to W boson production at hadron colliders with special emphasis on the transverse mass distribution.

John F. Donoghue, Antonio F. Perez

We use the Cottingham method to calculate the pion and kaon electromagnetic mass differences with as few model dependent inputs as possible. The constraints of chiral symmetry at low energy, QCD at high energy and experimental data in between are used in the dispersion relation. We find excellent agreement with experiment for the pion mass difference. The ka

Alec J. Schramm, Daniel H. Reeves

We estimate the production cross sections for $η_c$ and $η_b$ mesons via pomeron-pomeron fusion in peripheral heavy-ion collisions. Total and elastic PP cross sections are calculated in an equivalent pomeron approximation.

Gilberto Colangelo, Markus Finkemeier, Erwin Mirkes, Res Urech

We review a variety of topics related to hadronic structure functions in exclusive semihadronic tau decays. We introduce the concept of structure functions and summarize the most important concepts. We then calculate the decay $τ\to 3 πν_τ$ for very small hadronic invariant mass to one loop in Chiral Perturbation Theory. New interesting features emerge with

J. Murray, W. Bauer, K. Haglin

We use a simple QCD-based model to study particle production in S+Au collisions at 200 GeV/n. A requisite consistency is met for the hadronic observables (pi0 and pi- spectra) while pursuing estimates for e+e- production. Since radiative decays of initially produced hadrons has accounted for only a portion of the observed dileptons at the CERN SPS, we search

S. Keller, J. Womersley

We explore the ability of the Large Hadron Collider to measure the mass of the W boson. We believe that a precision better than ~ 15 MeV could be attained, based on a year of operation at low luminosity (10^(33)cm^(-2)s^(-1)). If this is true, this measurement will be the world's best determination of the W mass. We feel this interesting opportunity warr

L. Mankiewicz, G. Piller, A. Saalfeld

The gluon polarization $ΔG$ in a nucleon can be defined in a gauge invariant way as the integral over the Ioffe-time distribution of polarized gluons. We argue that for sufficiently regular polarized gluon distributions $ΔG$ is dominated by contributions from small and moderate values of the Ioffe-time z < 10. As a consequence $ΔG$ can be estimated with 20%

Matteo Cacciari, Mario Greco, Michael Krämer

The associated production of a J/psi and a photon in photon-hadron collisions is considered, and shown to be a good probe of the presence of colour-octet mediated channels in quarkonia production, as predicted by the factorization approach within NRQCD. Total and differential cross sections for photoproduction at fixed target experiments and at HERA are pres

M. I. Krivoruchenko

The explicit one-dimensional integral representations for isovector nucleon form factors are constructed by solving the unitarity relations in terms of the pion form factor and imaginary parts of the t-channel p-wave $πN$-scattering amplitudes. The possibility of computation of the high-energy parts of the integrals with the use of the information on the low

J. Pech, A. Tarancon, C. L. Ullod

We present a parallel machine, based on programmable devices, dedicated to simulate spin glass models with Z2 variables and short range interaction. A working prototype is described for two lattices containing 312x312 spins each with an update time of 50 ns per spin. The final version of the three dimensional parallel machine is discussed with spin update ti

M. Kuhlen

Measurements of structure functions and of the hadronic final state in deep inelastic scattering at HERA are presented. The results comprise the extraction of parton densities, measurements of the strong coupling, and the search for novel QCD effects in the new kinematic regime at HERA.

Ulises Nucamendi, Daniel Sudarsky

We define spacetimes that are asymptotically flat, except for a deficit solid angle $α$, and present a definition of their ``ADM&#39;&#39; mass, which is finite for this class of spacetimes, and, in particular, coincides with the value of the parameter $M$ of the global monopole spacetime studied by Vilenkin and Barriola . Moreover, we show that the definiti

Mattias Marklund, Zoltan Perjes

Stationary rotating matter configurations in general relativity are considered. A formalism for general stationary space times is developed. Axisymmetric systems are discussed by the use of a nonholonomic and nonrigid frame in the three-space of the time-like Killing trajectories. Two symmetric and trace-free tensors are constructed. They characterize a clas

Derik Wolvaardt, Roy Maartens

We find exact solutions of the Einstein-Boltzmann equations with relaxational collision term in FRW and Bianchi I spacetimes. The kinematic and thermodynamic properties of the solutions are investigated. We give an exact expression for the bulk viscous pressure of an FRW distribution that relaxes towards collision-dominated equilibrium. If the relaxation is

Boris S. Kruglikov

In this paper we consider three deeply connected classificational problems on four-dimensional manifolds. First we consider and describe locally regular distributions. Second we give a classification of almost complex structures of general position in terms of distributions. Finally we classify nondegenerate Monge-Ampere equations with two variables in terms

Boris S. Kruglikov

In this paper we present some approaches to classification of almost complex structures and to construction of local or formal pseudoholomorphic mapping from one almost complex manifold to another. The corresponding criteria are given in terms of Nijenhuis tensors and their generalizations. We deal with the prolongations of the Cauchy-Riemann equation in 1-j

Andrzej Biś, Paweł Walczak

We show that the entropy of a finitely generated pseudogroup (resp., of a foliation of a compact Riemannian manifold) can be calculated by suitable counting separated pseudo-orbits (resp., pseudoleaves).

V. Popkov, B. Nienhuis

Solvable via Bethe Ansatz (BA) anisotropic statistical model on cubic lattice consisting of locally interacting 6-vertex planes, is studied. Symmetries of BA lead to infinite hierarchy of possible phases, which is further restricted by numerical simulations. The model is solved for arbitrary value of the interlayer coupling constant. Resulting is the phase d

L. O. Manuel, C. J. Gazza, A. E. Trumper, H. A. Ceccatto

We present a Schwinger-boson approach to the Heisenberg model with Dzyaloshinskii-Moriya interaction. We write the anisotropic interactions in terms of Schwinger bosons keeping the correct symmetries present in the spin representation, which allows us to perform a conserving mean-field approximation. Unlike previous studies of this model by linear spin-wave

Oded Agam, Ned S. Wingreen, Boris L. Altshuler, D. C. Ralph

We explain the observation of clusters in the tunneling resonance spectra of small metallic particles of few nanometer size. Each cluster of resonances is identified with one excited single--electron state of the metal particle, shifted as a result of the different nonequilibrium occupancy configurations of the other single--electron states. Assuming the und

R. Chitra, T. Giamarchi

An interesting feature of spin-1/2 chains with a gap is that they undergo a commensurate-incommensurate transition in the presence of an external magnetic field $H$. The system is in a gapless incommensurate regime for all values of the magnetic field between the lower critical field $H_{c1}$ and an upper critical field $H_{c2}$, where it is gapless and has

Roberto Iengo, Giancarlo Jug

We investigate the phenomenon of decay of a supercurrent in a superconducting thin film in the absence of an applied magnetic field. The resulting zero-temperature resistance derives from two equally possible mechanisms: 1) quantum tunneling of vortices from the edges of the sample; and 2) homogeneous quantum nucleation of vortex-antivortex pairs in the bulk

Robert Graham, Dan Walls

The linearised time dependent coupled Gross-Pitaevskii equations describing the long wavelength excitations of Bose-condensed binary mixtures are solved, in the bulk and in harmonic traps for the case where only the binary phase is present. In the former case we obtain two zero-sound branches.In the latter case the dispersion law also contains two branches w

Rens Bod, Remko Scha

During the last few years, a new approach to language processing has started to emerge, which has become known under various labels such as &#34;data-oriented parsing&#34;, &#34;corpus-based interpretation&#34;, and &#34;tree-bank grammar&#34; (cf. van den Berg et al. 1994; Bod 1992-96; Bod et al. 1996a/b; Bonnema 1996; Charniak 1996a/b; Goodman 1996; Kaplan

Martin Sieber

Semiclassical approximations often involve the use of stationary phase approximations. This method can be applied when $\hbar$ is small in comparison to relevant actions or action differences in the corresponding classical system. In many situations, however, action differences can be arbitrarily small and then uniform approximations are more appropriate. In

MIA Collaboration

We have carried out a high statistics (2 Billion events) search for ultra-high energy gamma-ray emission from the X-ray binary sources Cygnus X-3 and Hercules X-1. Using data taken with the CASA-MIA detector over a five year period (1990-1995), we find no evidence for steady emission from either source at energies above 115 TeV. The derived upper limits on s

Neta A. Bahcall

How is the universe organized on large scales? How did this structure evolve from the unknown initial conditions of a rather smooth early universe to the present time? The answers to these questions will shed light on the cosmology we live in, the amount, composition and distribution of matter in the universe, the initial spectrum of density fluctuations tha

M. A. Pahre, S. G. Djorgovski

We review the concept of the Fundamental Plane (FP), and present new results on the near-infrared FP. We show that the K-band FP differs both from the optical form and the virial expectation under the assumption of constant (M/L) and homology. Systematic variations of only the stellar populations parameters (age, metallicity, IMF) cannot reproduce the slopes

R. N. Ogley, S. J. Bell Burnell, R. P. Fender

Modelling of the point spread function of the UKIRT IRCAM3 array was conducted in order to test any extended emission around the X-ray binary Cyg X-3. We found that the point spread function cannot be represented by a simple Gaussian, but modelling of the stars required additional functions namely Lorrentzian and exponential components. After modelling for t

Ramesh Narayan

Recent work on advection-dominated accretion flows (ADAFs) is reviewed. The article concentrates on an optically thin branch of ADAFs which is present at mass accretion rates below a critical value $\sim(10^{-2}-10^{-1})$ the Eddington rate. Models based on this branch have been quite successful at explaining a number of low-luminosity X-ray binaries and gal

C. Motch, P. Guillout, F. Haberl, M. Pakull

We present the analysis of the point source content of a low galactic latitude region selected from the ROSAT all-sky survey. The test field is centered at l = 90deg, b = 0deg and has an area of 64.5 deg2. A total of 128 soft X-ray sources are detected above a maximum likelihood of 8. Catalogue searches and optical follow-up observations show that in this di

Annalisa Celotti, Paolo Padovani, Gabriele Ghisellini

We present evidence in favour of a link between the luminosity radiatively dissipated in the central engine of radio-loud Active Galactic Nuclei and the kinetic power in their jets. This piece of evidence is based on the relation we find between the luminosity in broad emission lines and the kinetic power in pc-scale radio jets, for a sample of radio-loud qu

Hideki Asada

We investigate the cosmological test recently proposed by B. Fort, Y. Mellier and M. Dantel-Fort (FMD), where the observed location of the critical line in gravitational lensing is used to determine the cosmological parameters, $Ω$ and $λ$. Applying this method to the cluster of galaxies Cl0024+1654, FMD obtained a constraint on the cosmological constant, $λ

Michael D. Gregg, Dante Minniti

In February, 1997, the second Space Shuttle servicing mission to the Hubble Observatory will install the Space Telescope Imaging Spectrograph (STIS). This new instrument will greatly enhance the spectroscopic capabilities of the Hubble Space Telescope by providing a longslit format and CCD detector technology. STIS can also be used as an imager, providing an

Marco Andreatta, Jaroslaw A. Wiśniewski

In this paper we discuss some recent results about extremal contractions of complex algebraic varieties. These are proper surjective maps, $ϕ: X\longrightarrow Z$, of normal varieties with connected fibers such that $X$ has mild singularities (in particular $X$ is $Q$-Gorenstein) and the anticanonical divisor of $X$ is $ϕ$ ample. It will appear on the Procee

W. W. M. Allison, G. J. Alner, D. S. Ayres, W. L. Barrett

The atmospheric neutrino flavour ratio measured using a 1.52 kton-year exposure of Soudan 2 is found to be 0.72 +- 0.19 +0.05 -0.07 relative to the expected value from a Monte Carlo calculation. The possible background of interactions of neutrons and photons produced in muon interactions in the rock surrounding the detector has been investigated and is shown

Julio F. Navarro, Carlos S. Frenk, Simon D. M. White

We use high-resolution N-body simulations to study the equilibrium density profiles of dark matter halos in hierarchically clustering universes. We find that all such profiles have the same shape, independent of halo mass, of initial density fluctuation spectrum, and of the values of the cosmological parameters. Spherically averaged equilibrium profiles are

Phillial Oh, Chaiho Rim

We derive the Holstein-Primakoff oscillator realization on the coadjoint orbits of the $SU(N+1)$ and $SU(1,N)$ group by treating the coadjoint orbits as a constrained system and performing the symplectic reduction. By using the action-angle variables transformations, we transform the original variables into Darboux variables. The Holstein-Primakoff expressio

A. A. Rosly, K. G. Selivanov

Self-dual perturbiner in the Yang-Mills theory is constructed by the twistor methods both in topologically trivial and topologically nontrivial cases. Maximally helicity violating amplitudes and their instanton induced analogies are briefly discussed.

H. C. Rosu, J. Socorro

We show that closed, radiation-filled Friedmann-Robertson-Walker quantum universes of arbitrary factor ordering obey the Whittaker equation. We also present the formal Witten factorization as well as the double Darboux strictly isospectral scheme for the Whittaker equation

Thomas Mehen

I compute the leading color-octet contributions to the process $γ+ p \to J/ψ+ γ(+ X)$ within the non-relativistic QCD (NRQCD) factorization formalism. In the color-singlet model, $J/ψ+ γ$ can only be produced when the photon interacts through its structure function, while the color-octet mechanism allows for production of $J/ψ+ γ$ via direct photon-gluon fus

F. Csikor, Z. Fodor

We discuss the perturbative running of alpha_s in a model independent way. Our analysis contains data on the hadronic tau decay and hadronic cross sections in e+e- annihilation between 5 GeV and M_Z. We determine the color coefficients and the perturbative beta-function of the strong interaction. The results are in agreement with QCD and rule out the QCD+lig

Gert-Ludwig Ingold, Astrid Lambrecht

On the basis of a macroscopic ground state population it was argued recently that Bose-Einstein condensation should occur in a one-dimensional harmonic potential. We examine this situation by drawing analogies to Bosons in a two-dimensional box, where the thermodynamic limit is well-defined. We show that in both systems although the ground state populations

W. S. Chung, G. Q. Li, C. M. Ko

Phi meson production in pion-baryon and baryon-baryon interactions near the production threshold is studied in a boson-exchange model. Parameters in this model are either taken from the Bonn model for the nucleon-nucleon potential or determined from the measured phi meson decay width and the experimental data for the reactions $π^-p\arr ϕn$ and $pp\arr ppϕ$.

M. E. Kazarian, B. Shapiro

Let us consider a generic n-dimensional subbundle V of the tangent bundle TM on some given manifold M. Given V one can define different degeneracy loci S_r(CV), r=(r_1<= r_2<= r_3<=...<=r_k) on M consisting of all points x in M for which the dimension of the subspace V^j(x) in TM(x) spanned by all length <= j commutators of vector fields tangent to V at x is

P. Fraundorf

This paper presents some ideas which might assist teachers incorporating special relativity into an introductory physics curriculum. One can define the proper-time/velocity pair, as well as the coordinate-time/velocity pair, of a traveler using only distances measured with respect to a single ``map&#39;&#39; frame. When this is done, the relativistic equatio

Jose-Luis Rosales

The semiclassical approach to quantum gravity would yield the Schroedinger formalism for the wave function of metric perturbations or gravitons plus quantum gravity correcting terms in pure gravity; thus, in the inflationary scenario, we should expect correcting effects to the relic graviton (Zel&#39;dovich) spectrum of the order (H/mPl)^2.

Takuhiro Kitao

We derive the singularity conditions of the N=1 generalized (general yukawa couplings and quark masses) form of hyperelliptic curves of SU(N_c) with N_f flavors. The results reproduce the known form of N=2 curves when the yukawa couplings and the quark masses reduce to those of N=2. We obtained these curves by determining the dependence of the unbroken SU(2)

Kenji Suzuki

We construct a four-dimensional BPS saturated heterotic string solution from the Taub-NUT solution. It is a non-extremal black hole solution since its Euler number is non-zero. We evaluate its black hole entropy semiclassically. We discuss the relation between the black hole entropy and the degeneracy of string states. The entropy of our string solution can

Tad Hogg, J. Geoffrey Chase

The development of small-scale sensors and actuators enables the construction of smart matter in which physical properties of materials are controlled in a distributed manner. In this paper, we describe how quantum computers could provide an additional capability, programmable control over some quantum behaviors of such materials. This emphasizes the need fo

Almut Beige, Gerhard C. Hegerfeldt

The quantum Zeno effect (QZE) predicts a slow-down of the time development of a system under rapidly repeated ideal measurements, and experimentally this was tested for an ensemble of atoms using short laser pulses for non-selective state measurements. Here we consider such pulses for selective measurements on a single system. Each probe pulse will cause a b

Boris F. Samsonov

Parasupersymmetry of the one dimensional time-dependent Schrödinger equation is established. It is intimately connected with a chain of the time-dependent Darboux transformations. As an example a parasupersymmetric model of nonrelativistic free particle with threefold degenerate discrete spectrum of an integral of motion is constructed.

G. Iannaccone

The theory of weak measurement, proposed by Aharonov and coworkers, has been applied by Steinberg to the long-discussed traversal time problem. The uncertainty and ambiguity that characterize this concept from the perspective of von Neumann measurement theory apparently vanish, and joint probabilities and conditional averages become meaningful concepts. We e

A. Chakrabarti

A two-parametric generalization of the Jordanian deformation $U_h (sl(2))$ of $sl(2)$ is presented. This involves Jacobian elliptic functions. In our deformation $U_{(h,k)}(sl(2))$, for $k^2=1$ one gets back $U_h(sl(2))$. The constuction is presented via a nonlinear map on $sl(2)$. This invertible map directly furnishes the highest weight irreducible represe

A. Chakrabarti

Shiraishi&#39;s two parameter generalization of $U_{q}(sl(2))$ to $U_{q,p}(sl(2))$ involving an elliptic function is considered. The generators are mapped non-linearly on those of $U_{q}(sl(2))$. This gives directly the irreducible representations and an induced Hopf structure. This is one particular example of the scope of a class of non-linear maps introdu

I Tsohantjis, A Paolucci, P D Jarvis

Certain types of generalized undeformed and deformed boson algebras which admit a Hopf algebra structure are introduced, together with their Fock-type representations and their corresponding $R$-matrices. It is also shown that a class of generalized Heisenberg algebras including those algebras including those underlying physical models such as that of Caloge

F. Schmid, H. Lange

A model of rods with heads of variable size, which are confined to a planar surface, is used to study the influence of the head group size on tilted phases in Langmuir monolayers. Simple free energy considerations as well as exact zero temperature calculations indicate that molecules with small head groups tilt towards next nearest neighbors, and molecules w

Paul J. Ellis, Vesteinn Thorsson

We investigate the contribution of zero-point motion, arising from fluctuations in kaon modes, to the ground state properties of neutron star matter containing a Bose condensate of kaons. The zero-point energy is derived via the thermodynamic partition function, by integrating out fluctuations for an arbitrary value of the condensate field. It is shown that

G. Casini, P. R. Maurenzig, A. Olmi, M. Bini

Primary and secondary masses of heavy reaction products have been deduced from kinematics and E-ToF measurements, respectively, for the direct and reverse collisions of 100Mo with 120Sn at 14.1 A MeV. Direct experimental evidence of the correlation of energy-sharing with net mass transfer and model-independent results on the evolution of the average excitati

Andres Villaveces

Large cardinals arising from the existence of arbitrarily long end elementary extension chains over models of set theory are studied here. In particular, we show that the large cardinals obtained that way (`Unfoldable cardinals&#39;) behave as a `boundary&#39; between properties consistent with `V=L&#39; and existence of indiscernibles. We also provide an `e

Andres Villaveces

The existence of End Elementary Extensions of models M of ZFC is related to the ordinal height of M, according to classical results due to Keisler, Morley and Silver. In this paper, we further investigate the connection between the height of M and the existence of End Elementary Extensions of M. In particular, we prove that the theory `ZFC + GCH + there exis

Paolo Pasti, Dmitri Sorokin, Mario Tonin

We demonstrate how a Lorentz covariant formulation of the chiral p-form model in D=2(p+1) containing infinitely many auxiliary fields is related to a Lorentz covariant formulation with only one auxiliary scalar field entering a chiral p-form action in a nonpolynomial way. The latter can be regarded as a consistent Lorentz-covariant truncation of the former.

E. Bergshoeff

We consider solutions to the string effective action corresponding to p-Branes, D-Branes and M-Branes and discuss some of their properties.

C. D. Fosco, R. C. Trinchero

We study the relationship between the continuum overlap and its corresponding chiral determinant, showing that the former amounts to an unregularised version of the latter. We then construct a regularised continuum overlap, and consider the chiral anomalies that follow therefrom. The relation between these anomalies and the ones derived from the formal (i.e.

Renata Kallosh, Arvind Rajaraman, Wing Kai Wong

Five-dimensional stringy rotating black holes are embedded into N=2 supergravity interacting with one vector multiplet. The existence of an unbroken supersymmetry of the rotating solution is proved directly by solving the Killing spinor equations. The asymptotic enhancement of supersymmetry near the horizon in the presence of rotation is established via the

Kamran Saririan

This talk is a brief review of gaugino condensation in superstring effective field theories and some related issues (such as renormalization of the gauge coupling in the effective supergravity theories and modular anomaly cancellation). As a specific example, we discuss a model containing perturbative (1-loop) corrections to the Kähler potential and approxim

T. Blazek, S. Raby

We present a self-consistent $χ^2$ analysis of several supersymmetric (SUSY) grand unified theories recently discussed in the literature. We obtain global fits to low energy data, including gauge couplings, fermion masses and mixing angles, gauge boson masses and $BR(b\rightarrow sγ)$. One of the models studied provides an excellent fit to the low energy dat

A. V. Kisselev, V. A. Petrov

We argue that the difference between the structure functions corresponding to deep inelastic scattering with and without heavy quarks in the current fragmentation region scales at high $Q^2$ and fixed (low) $x_{Bj}$. The lower bound on charm contribution to the total structure function, $F_2^c(Q^2,x)$, is calculated and compared with the recent data on $F_2^

A. V. Kisselev, V. A. Petrov

Total hadron multiplicities and multiplicities of hadrons in events with heavy quarks in $e^+e^-$ annihilation at the energies of LEP-1.5 and LEP-2 are calculated on the basis of QCD.

H. -J. He, Y. -P. Kuang, C. -P. Yuan

Based upon our recent study, we reveal the profound physical content of the longitudinal-Goldstone boson equivalence theorem as being able to discriminate physical processes which are sensitive/insensitive to probing the electroweak symmetry breaking (EWSB) sector. We then develop a precise electroweak power counting rule (a generalization from Weinberg&#39;

Philip D. Mannheim

Our long experience with Newtonian potentials has inured us to the view that gravity only produces local effects. In this paper we challenge this quite deeply ingrained notion and explicitly identify some intrinsically global gravitational effects. In particular we show that the global cosmological Hubble flow can actually modify the motions of stars and gas

Philip D. Mannheim

We show that the gravitational modification of the phase of a neutron beam (the COW experiment) has a classical origin, being due to the time delay which classical particles experience in traversing a background gravitational field. Similarly, we show that classical light waves also undergo a phase shift in traversing a gravitational field. We show that the

David Langlois

The observed CMBR dipole, generally interpreted as the consequence of the peculiar motion of the Sun with respect to the reference frame of the CMBR, can also be explained by the presence of ultra large scale (of the order of $100H_0^{-1}$) isocurvature perturbations. Moreover, the simplest model of inflation with several scalar fields, namely that of double

Alejandro Corichi, Jose A. Zapata

We consider the role of the diffeomorphism constraint in the quantization of lattice formulations of diffeomorphism invariant theories of connections. It has been argued that in working with abstract lattices, one automatically takes care of the diffeomorphism constraint in the quantum theory. We use two systems in order to show that imposing the diffeomorph

Wei Bao, J. D. Axe, C. H. Chen, S-W. Cheong

Single crystalline (Bi,Ca)MnO3 (74< %Ca <82) were studied with neutron scattering, electron diffraction and bulk magnetic measurement. We discovered dynamic ferromagnetic spin correlations at high temperatures, which are replaced by antiferromagnetic spin fluctuations at a concomitant charge ordering and structural transition. Our results indicate that therm

Wei Bao, C. Broholm, G. Aeppli, P. Dai

Spin correlations in metallic and insulating phases of $V_2O_3$ and its derivatives are investigated using magnetic neutron scattering. Metallic samples have incommensurate spin correlations varying little with hole doping. Paramagnetic insulating samples have spin correlations only among near neighbors. The transition from either of these phases into the lo

Brad Lee Holian, Raphael Blumenfeld, Peter Gumbsch

We propose a minimal nonlinear model of brittle crack propagation by considering only the motion of the crack-tip atom. The model captures many essential features of steady-state crack velocity and is in excellent quantitative agreement with many-body dynamical simulations. The model exhibits lattice-trapping. For loads just above this, the crack velocity ri

G. Iori, E. Marinari

We study the dynamics of the SK model modified by a small non-hamiltonian perturbation. We study aging, and we find that on the time scales investigated by our numerical simulations it survives a small perturbation (and is destroyed by a large one). If we assume we are observing a transient behavior the scaling of correlation times versus the asymmetry stren

Mark Bowick, Olivier Golinelli, Emmanuel Guitter, Shintaro Mori

We study the folding of the regular two-dimensional triangular lattice embedded in the regular three-dimensional Face-Centred Cubic lattice, a discrete model for the crumpling of membranes. Possible folds are complete planar folds, folds with the angle of a regular tetrahedron (71 degrees) or with that of a regular octahedron (109 degrees). We study this mod

David S. Dean

We present a simple derivation of the stochastic equation obeyed by the density function for a system of Langevin processes interacting via a pairwise potential. The resulting equation is considerably different from the phenomenological equations usually used to describe the dynamics of non conserved (Model A) and conserved (Model B) particle systems. The ma

D. D. Sarma, N. Shanthi, Priya Mahadevan

We present calculated electron excitation spectra for the LaMO_3 series (M=Cr-Ni) obtained within ab-initio band structure calculations for the real geometric and magnetic structures. The calculated results show good agreement with the experimentally obtained spectra. This suggests that the transition metal-transition metal interactions via the oxygen atom p

S. Hikami, K. Minakuchi

The quantum Hall system in the lowest Landau level with Zeeman term is studied by a two-state model, which has a chiral invariance. Using a diagrammatic analysis, we examine this two-state model with random impurity scattering, and find the exact value of the conductivity at the Zeeman energy $E = Δ$. We further study the conductivity at the another extended

T. Wong, M. J. Collett, S. M. Tan, D. F. Walls

We present an elementary model of the collapses and revivals in the visibility of the interference between two atomic Bose-Einstein condensates. We obtain different predictions of the revival times whether we conserve or break atom number conservation from the outset. The validity of Bose-broken symmetry can be tested by observations of these collapses and r

D. L. Shepelyansky

A possibility that in the FPU problem the critical energy for chaos goes to zero with the increase of the number of particles in the chain is discussed. The distribution for long linear waves in this regime is found and an estimate for new border of transition to energy equipartition is given.

Avishai Dekel, David Burstein, Simon D. M. White

We were asked to debate the value of the cosmological mass-density parameter Omega. Is Omega_m=1 in accordance with the simplest model? Is Omega_m much smaller as indicated by some observations? There is conflicting evidence. We lay out the various methods for measuring Omega_m, mention new developments and current estimates, and focus on prospects versus th

James S. Bullock, Joel R. Primack

We explore the role of non-Gaussian fluctuations in primordial black hole (PBH) formation and show that the standard Gaussian assumption, used in all PBH formation papers to date, is not justified. Since large spikes in power are usually associated with flat regions of the inflaton potential, quantum fluctuations become more important in the field dynamics,

Myungshin Im, Richard E. Griffiths, Kavan U. Ratnatunga

We have identified seven (field) elliptical galaxies acting as strong gravitational lenses and have used them to measure cosmological parameters. To find the most likely value for Omega_m (= Omega_matter) and Lambda, we have used the combined probabilities of these lens systems having the observed critical radii (or image deflection) for the measured or esti

Roelof S. de Jong, Roger L. Davies

In this paper we investigate the relation between the detailed isophotal shape of elliptical galaxies and the strength of the H beta absorption in their spectra. We find that disky galaxies have higher H beta indices. Stellar population synthesis models show that the H beta line is a good age indicator, hence disky galaxies tend to have younger mean ages tha

S. Ghigna, S. Borgani, M. Tucci, S. A. Bonometto

We apply several statistical estimators to high-resolution N-body simulations of two currently viable cosmological models: a mixed dark matter model, having $Ω_ν=0.2$ contributed by two massive neutrinos (C+2\nuDM), and a Cold Dark Matter model with Cosmological Constant (\LambdaCDM) with $Ω_0=0.3$ and h=0.7. Our aim is to compare simulated galaxy samples wi

A. Karle, T. Mikolajski, S. Cichos, S. Hundertmark

New LED-transmitters have been used to develop a new method of fast analog transmission of PMT pulses over large distances. The transmitters, consisting basically of InGaAsP LEDs with the maximum emission of light at 1300 nm, allow the transmission of fast photomultiplier pulses over distances of more than 2 km. The shape of the photomultiplier pulses is mai

M. A. Abramowicz, A. Lanza, M. J. Percival

We re-derive the equation for vertical hydrodynamical equilibrium of stationary thin and slim accretion disks in the Kerr spacetime. All the previous derivations have been unsatisfactory, yielding unphysical singularities. Our equation is non-singular, more general, and simpler than those previously derived.

S. Borgani, L. Moscardini, M. Plionis, K. M. Gorski

(Shortened Abstract). We analyze a redshift sample of Abell/ACO clusters and compare them with numerical simulations based on the truncated Zel&#39;dovich approximation (TZA), for a list of eleven dark matter (DM) models. For each model we run several realizations, on which we estimate cosmic variance effects. We analyse correlation statistics, the probabili

R. C. Kraan-Korteweg, P. A. Woudt, P. A. Henning

We report here on extragalactic large-scale structures uncovered by a deep optical survey for galaxies behind the southern Milky Way. Systematic visual inspection of the ESO/SRC-survey revealed over 10000 previously unknown galaxies in the region 265 < l < 340, |b| < 10. With subsequently obtained redshifts of more than 10% of these galaxies, new structures

Y. -Z. Qian

We discuss various neutrino-nucleus interactions in connection with the supernova r-process nucleosynthesis, which possibly occurs in the neutrino-driven wind of a young neutron star. These interactions include absorptions of electron neutrinos and antineutrinos on free nucleons, electron-neutrino captures on neutron-rich nuclei, and neutral-current interact

R. D. Hoffman, S. E. Woosley, Y. -Z. Qian

During the first 20 seconds of its life, the enormous neutrino luminosity of a neutron star drives appreciable mass loss from its surface. This neutrino-driven wind has been previously identified as a likely site for the r-process. Qian & Woosley (1996) have derived, both analytically and numerically, the physical conditions relevant for heavy element synthe

William G. Mathews

The temperature of hot interstellar gas at large radii in elliptical galaxies can be lower than the mean galactic virial temperature. If so, a nonlinear cooling wave can form in the hot interstellar gas and propagate slowly toward the galactic core. If the cooling wave survives hydrodynamic instabilities, it can intermittently deposit cold gas within about 1

C. R. Stephens, H. Waelbroeck

An evolution equation for a population of strings evolving under the genetic operators: selection, mutation and crossover is derived. The corresponding equation describing the evolution of schematas is found by performing an exact coarse graining of this equation. In particular exact expressions for schemata reconstruction are derived which allows for a crit