October 1996 arXiv papers — page 10

The E142 Collaboration, P. L. Anthony et al

The neutron longitudinal and transverse asymmetries $A^n_1$ and $A^n_2$ have been extracted from deep inelastic scattering of polarized electrons by a polarized $^3$He target at incident energies of 19.42, 22.66 and 25.51 GeV. The measurement allows for the determination of the neutron spin structure functions $g^n_1 (x,Q^2)$ and $g^n_2(x,Q^2)$ over the rang

Ian G. Moss, Pedro J. Silva

A systematic way of generating sets of local boundary conditions on the gauge fields in a path integral is presented. These boundary conditions are suitable for one--loop effective action calculations on manifolds with boundary and for quantum cosmology. For linearised gravity, the general proceedure described here leads to new sets of boundary conditions.

Jaroslav Fabian

The interaction between three localized vibrational modes is shown to be as relevant for the lifetimes of localized modes as the interaction involving two localized and one extended, and one localized and two extended modes. This contrasts with previous views. I support my arguments by a numerical study of a strongly disordered linear atomic chain.

E. Pitard, H. Orland

We study the dynamics of a polymer when it is quenched from a $θ$ solvent into a good or bad solvent by means of a Langevin equation. The variation of the radius of gyration is studied as a function of time. For the first stage of collapse or swelling, the characteristic time-scale is found to be independent of the number of monomers. Other scaling laws are

V. Kagalovsky, B. Horovitz, Y. Avishai

We study dynamics of electrons in a magnetic field using a network model with two channels per link with random mixing in a random intrachannel potential; the channels represent either two Landau levels or two spin states. We consider channel mixing as function of the energy separation of the two extended states and show that its effect changes from repulsio

Karol Kalna, Martin Mosko

Electron capture times due to the electron-electron (e-e), electron-hole (e-h) and electron-polar optical phonon (e-pop) interactions are calculated in the GaAs quantum well (QW) with electron and hole densities 10^11 cm^-2. The calculated capture times oscillate as a function of the QW width with the same period but with different amplitudes. The e-h captur

S. Brehmer, H. -J. Mikeska, S. Yamamoto

We study the low-temperature properties of S=1 and 1/2 alternating spin chains with antiferromagnetic nearest-neighbor exchange couplings using analytical techniques as well as a quantum Monte Carlo method. The spin-wave approach predicts two different low-lying excitations, which are gapped and gapless, respectively. The structure of low-lying levels is als

T. Nishino, K. Okunishi

We review the variational principle in the density matrix renormalization group (DMRG) method, which maximizes an approximate partition function within a restricted degrees of freedom; at zero temperature, DMRG mini- mizes the ground state energy. The variational principle is applied to two-dimensional (2D) classical lattice models, where the density matrix

Gregor Tanner

The impression gained from the literature published to date is that the spectrum of the stadium billiard can be adequately described, semiclassically, by the Gutzwiller periodic orbit trace formula together with a modified treatment of the marginally stable family of bouncing ball orbits. I show that this belief is erroneous. The Gutzwiller trace formula is

R. Benzi, L. Biferale, R. Tripiccione, E. Trovatore

A class of dynamical models of turbulence living on a one-dimensional dyadic-tree structure is introduced and studied. The models are obtained as a natural generalization of the popular GOY shell model of turbulence. These models are found to be chaotic and intermittent. They represent the first example of (1+1)-dimensional dynamical systems possessing non t

M. J. Sawicki, H. Lin, H. K. C. Yee

This paper presents the results of a photometric redshift study of galaxies in the Hubble Deep Field (HDF). The method of determining redshifts from broadband colors is described, and the dangers inherent in using it to estimate redshifts, particularly at very high z, are discussed. In particular, the need for accurate high-z spectral energy distributions is

Heino Falcke

Compact radio cores are not only common in radio galaxies and quasars but also in many nearby galaxies with low-active, supermassive black holes. One famous example is the Galactic Center source Sgr A*. Recent studies of proper motions and radial velocities of stars in the inner parsec of the Galaxy convincingly demonstrate the presence of a compact dark mas

C. S. Reynolds, T. Di Matteo, A. C. Fabian, U. Hwang

It is believed that most giant elliptical galaxies possess nuclear black holes with masses in excess of $10^8\Msun$. Bondi accretion from the interstellar medium might then be expected to produce quasar-like luminosities from the nuclei of even quiescent elliptical galaxies. It is a puzzle that such luminosities are not observed. Motivated by this problem, F

Joachim Wambsganss, Renyue Cen, Jeremiah P. Ostriker

Gravitational lensing directly measures mass density fluctuations along the lines of sight to very distant objects. No assumptions need to be made concerning bias, the ratio of fluctuations in galaxy density to mass density. Hence, lensing is a very useful tool to study the universe at low to moderate redshifts. We describe in detail a new method to trace li

P. A. Thomas, H. M. P. Couchman, F. R. Pearce

We intend to make sets of cosmological simulations available, with a large number of different output times that may be placed side-by-side to produce a complete history of the universe stretching back to high redshift. Currently there is only one series of runs under preparation as a trial. Gauging by the response, we will consider further releases. The fir

Max Tegmark

For power spectrum estimation it's important that the pixelization of a CMB sky map be smooth and regular to high degree. With this criterion in mind the ``COBE sky cube" was defined. This paper has as central theme to further improve on this elegant scheme which uses a cube as projective base -- here an icosahedron is used in its place. Although the

Paolo Padovani, Paolo Giommi, Fabrizio Fiore

We study the X-ray spectra of 114 flat-spectrum radio quasars (FSRQ) using the hardness ratios as given in the WGA catalogue of ROSAT sources. This sample includes all WGA FSRQ with high-quality data and comprises about 20 per cent of presently known such objects, which makes this the largest FSRQ sample ever studied in the X-ray band. We find that FSRQ have

L. Dolan

We present a mechanism to construct four-dimensional charged massless Ramond states using the discrete states of a fivebrane Liouville internal conformal field theory. This conformal field theory has background charge, and admits an inner product which allows positive norm states. A connection among supergravity soliton solutions, Liouville conformal field t

Y. S. Kim

The underlying mathematics of the wavelet formalism is a representation of the inhomogeneous Lorentz group or the affine group. Within the framework of wavelets, it is possible to define the ``window'' which allows us to introduce a Lorentz-covariant cut-off procedure. The window plays the central role in tackling the problem of photon localization.

Maurizio Martellini, Mauro Zeni

The deformation of a topological field theory, namely the pure BF theory, gives the first order formulation of Yang-Mills theory; Feynman rules are given and the standard uv-behaviour is recovered. In this formulation new non local observables can be introduced following the topological theory and giving an explicit realization of `t Hooft algebra.

A. M. Semikhatov

We formulate the general construction for singular vectors in Verma modules of the affine sl(2|1) superalgebra. We then construct sl(2|1) representations out of the fields of the non-critical N=2 string. This allows us to extend naturally to sl(2|1) several crucial properties of the N=2 superconformal algebra, first of all the construction of extremal states

S. Boldyrev

In this note the Polyakov equation [Phys. Rev. E {\bf 52} (1995) 6183] for the velocity-difference PDF, with the exciting force correlation function $κ(y)\sim1-y^α$ is analyzed. Several solvable cases are considered, which are in a good agreement with available numerical results. Then it is shown how the method developed by A. Polyakov can be applied to turb

M. Bastero-Gil

More precise unification predictions require going beyond the lowest order, including 2-loop running of the couplings and a correct treatment of threshold effects. Here we revised two different approaches to deal with light thresholds, based on different choices of the renormalization scheme, \bar{MS} and effective couplings. We show the equivalence of both

P. I. Krastev

The most popular solutions of the solar neutrino problem which assume massive neutrinos predict varying with time signals in the solar neutrino detectors. The variations represent a distinctive feature of these solutions and do not depend on the theoretically predicted total flux of neutrinos from the Sun. The sensitivity of SuperKamiokande and SNO to day-ni

Steven R. White, D. J. Scalapino

Using the density matrix renormalization group, we study domain wall structures in the t-J model at a hole doping of x=1/8. We find that the domain walls are composed of d_{x^2-y^2} pairs and that the regions between the domain walls have antiferromagnetic correlations that are pi phase shifted across a domain wall. At x=1/8, the hole filling corresponds to

S. -Z. Zhang, E. Louis, O. Pla, F. Guinea

The first stages of finger formation in a Hele-Shaw cell with lifting plates are investigated by means of linear stability analysis. The equation of motion for the pressure field (growth law) results to be that of the directional solidification problem in some unsteady state. At the beginning of lifting the square of the wavenumber of the dominant mode resul

M. Lemoine, D. N. Schramm, J. W. Truran, C. J. Copi

We explore possible depletion factors for Li6 in the three stars where it has been detected. To this end, we assume that 6Li/H scales as 16O/H throughout the galactic evolution, an assumption motivated by the observations of a similar scaling for 9Be. We examine the uncertainties attached to this modeling of 6Li galactic evolution; we also incorporate a rece

Luis Gonzalez-Mestres

The apparent Lorentz invariance of the laws of physics does not imply that space-time is indeed minkowskian. We consider a scenario where Lorentz invariance is only an approximate property of equations of matter above a certain distance scale, and superluminal sectors of matter exist related to new degrees of freedom not yet discovered experimentally. The ne

Maret Einasto, Erik Tago, Jaak Jaaniste, Jaan Einasto

We investigate the distribution of superclusters and voids using a new catalogue of superclusters of rich clusters of galaxies which extends up to a redshift of z=0.12. The new catalogue contains 220 superclusters of rich clusters, of which 90 superclusters have been determined for the first time. Two thirds of those superclusters with eight or more member c

Yi-Yen Wu

We study dynamical gaugino condensation in superstring effective theories using the linear multiplet representation for the dilaton superfield. An interesting necessary condition for the dilaton to be stabilized, which was first derived in generic models of static gaugino condensation, is shown to hold for generic models of dynamical gaugino condensation. We

Ch. Elster, W. Gloeckle

Optical potentials for elastic p-d scattering and the coupled processes p+$^3$He $\rightarrow$ p+$^3$He and p+$^3$He $\rightarrow$ d+d are derived in the Faddeev-Yakubovsky framework with special emphasis on leading order terms, which are expected to be valid at intermediate energies. In addition, equations for the fragmentations $^3$He(p,ppp)n and $^3$He(p,

Domingo Louis-Martinez

It is shown that the recently obtained quantum wave functionals in terms of the CJZ variables for generic 2d dilaton gravity are equivalent to the previously reported exact quantum wave functionals in geometrical variables. A third representation of these exact quantum states is also presented.

Iain W. Stewart, Peter G. Blunden

We examine the effect of one loop quantum corrections on the formation of nontopological solitons in a strongly coupled scalar-fermionic Yukawa theory. The exact one fermion loop contribution is incorporated by using a nonlocal method to correct the local derivative expansion approximation (DE) of the effective action. As the Yukawa coupling is increased we

A. Carlini, J. Greensite

The classical field equations of general relativity can be expressed as a single geodesic equation, describing the free fall of a point particle in superspace. Based on this formulation, a ``worldline'' quantization of gravity, analogous to the Feynman-Schwinger treatment of particle propagation, is proposed, and a hidden mass-shell parameter is iden

E. Shimshoni, S. L. Sondhi, D. Shahar

A recent experiment by Shahar et al, on the phase transitions between quantum Hall states and the insulator, found that the current-voltage characteristics in the two phases are related by symmetry. It was suggested in this work that this is evidence for charge-flux duality near quantum Hall transitions. Here we provide details of this analysis. (Appearances

J. Richard Bond, Andrew H. Jaffe

We describe the Bayesian-based signal-to-noise eigenmode method for cosmological parameter estimation, show how it can be used to optimally compress large CMB anisotropy data sets to manageable sizes, and apply it to the DMR 4-year, South Pole and Saskatchewan data, individually and in combination. A simple prior probability method is used to include large s

Ue-Li Pen

We show how the virial theorem can be applied to the hot gas in clusters of galaxies to obtain a yardstick, which could then be used to determine cosmological parameters. This yardstick relies on the assumptions of hydrostatic equilibrium and that the gas fraction is approximately constant. The constancy is checked empirically from a local population of clus

Edvige Corbelli, Stephen E. Schneider

To determine the actual HI distribution and the velocity field in the outermost disk of the spiral galaxy M33, a tilted-ring model is fitted to 21-cm line data taken with the Arecibo Telescope. Since M33 is one of the main calibrators for the extragalactic distance scale derived through the Tully-Fisher relation, the outer disk warping is of interest for a c

Carl R. Gwinn, T. Marshall Eubanks, Ted Pyne, Mark Birkinshaw

We report observational upper limits on the mass-energy of the cosmological gravitational-wave background, from limits on proper motions of quasars. Gravitational waves with periods longer than the time span of observations produce a simple pattern of apparent proper motions over the sky, composed primarily of second-order transverse vector spherical harmoni

Jesper Sommer-Larsen, Henrik Vedel, Uffe Hellsten

A theory for the structure of isothermal, self-gravitating gas spheres in pressure equilibrium in a softened gravitational field is developed. The one parameter spline softening proposed by Hernquist & Katz (1989) is used. We show that the addition of this extra scale parameter implies that the set of equilibrium solutions constitute a one-parameter family,

H. U. Boden, K. Yokogawa

This paper concerns the moduli spaces of rank two parabolic Higgs bundles and parabolic K(D) pairs over a smooth curve. Precisely which parabolic bundles occur in stable K(D), pairs and stable Higgs bundles is determined. Using Morse theory, the moduli space of parabolic Higgs bundles is shown to be a non-compact, connected, simply connected manifold, and a

H. U. Boden, K. Yokogawa

The moduli space of parabolic bundles with fixed determinant over a smooth curve of genus greater than one is proved to be rational whenever one of the multiplicities associated to the quasi-parabolic structure is equal to one. It follows that if rank and degree are coprime, the moduli space of vector bundles is stably rational, and the bound obtained on the

Mikhail Shubin

We prove an analogue of the de Rham theorem for the extended L^2-cohomology introduced by M. Farber. This is done by establishing that the de Rham complex over a compact closed manifold with coefficients in a flat Hilbert bundle E of A-modules over a finite von Neumann algebra A is chain-homotopy equivalent (with bounded morphisms and homotopy operators) to

Ken D. Olum

We call a state "vacuum-bounded" if every measurement performed outside a specified interior region gives the same result as in the vacuum. We compute the maximum entropy of a vacuum-bounded state with a given energy for a one-dimensional model, with the aid of numerical calculations on a lattice. The maximum entropy is larger than it would be for ri

Robert S. Thorne

We present calculations of structure functions using a renormalization scheme consistent expansion which is leading order in both ln(1/x) and α_s(Q^2). There is no factorization scheme dependence, and the ``physical anomalous dimensions'' of Catani naturally appear. A relationship between the small x forms of the inputs F_2(x,Q_0^2) and F_L(x,Q_0^2)

M. J. E. Richardson, M. R. Evans

We study the reaction-diffusion process $A+B\to \emptyset$ with injection of each species at opposite boundaries of a one-dimensional lattice and bulk driving of each species in opposing directions with a hardcore interaction. The system shows the novel feature of phase transitions between localised and delocalised reaction zones as the injection rate or rea

S. Bellucci, G. Isidori

We consider the rare decay $η\toπ^0π^0γγ$ and calculate the non-resonant contribution to the amplitude to one loop in Chiral Perturbation Theory. We display our result as both a diphoton energy spectrum and a partial decay rate as a function of the photon energy cut. It turns out that the one-loop correction can be numerically very important and could be det

Frank Göhmann, Shuichi Murakami

We reconsider the quantum inverse scattering approach to the one-dimensional Hubbard model and work out some of its basic features so far omitted in the literature. It is our aim to show that $R$-matrix and monodromy matrix of the Hubbard model, which are known since ten years now, have good elementary properties. We provide a meromorphic parametrization of

H. C. Rosu, J. Socorro

The strictly isospectral double Darboux method is applied to the quantum Taub model in order to generate a one-parameter family of strictly isospectral potentials for this case. The family we build is based on a scattering Wheeler-DeWitt solution first discussed by Ryan and collaborators that we slightly modified according to a suggestion due to Dunster. The

D. M. Cole, D. E. Vanden Berk, S. A. Severson, M. C. Miller

We present results from a series of optical (g and r-band) and near-infrared (K'-band) observations of the region of the sky including the entire XTE and ROSAT error circles for the ``Bursting Pulsar'' GRO J1744-28. These data were taken with the Astrophysical Research Consortium's 3.5-m telescope at Apache Point Observatory and with the 2.2-

A. F. Kracklauer

It is shown that correlations of dichotomic functions can not conform to results from Quantum Mechanics. Also, it is seen that the assumptions attendant to optical tests of Bell's Inequalities actually are consistent with classical physics so that in conclusion, Bell's Theorems do not preclude hidden variable interpretations of Quantum Mechanics.

Oleg V. Prezhdo, Vladimir V. Kisil

Using a group theoretical approach we derive an equation of motion for a mixed quantum-classical system. The quantum-classical bracket entering the equation preserves the Lie algebra structure of quantum and classical mechanics: The bracket is antisymmetric and satisfies the Jacobi identity, and, therefore, leads to a natural description of interaction betwe

Patrick M. Gilmer

Given an oriented knot K in S^3 and a TQFT, Turaev and Viro defined modules somewhat analogous to the Alexander module. We work with the (V_p,Z_p) theories of Blanchet, Habegger, Masbaum and Vogel {BHMV} for p \ge 3, and consider the associated modules. In {G}, we defined modules which also depend on the extra data of a color c which is assigned to a meridia

K. Mimachi, M. Noumi

We present a new formula of Cauchy type for the nonsymmetric Macdonald polynomials which are joint eigenfunctions of q-Dunkl operators. This gives the explicit formula for a reproducing kernel on the polynomial ring of n variables.

Fuqiang Wang

We demonstrate that coulomb interaction between a static charge source and K+ and K- from phi-meson decay could introduce systematic shift in the phi invariant mass reconstructed from the K+K- pair.

A. J. Buchmann, H. Henning, P. U. Sauer

The existing experimental data for the deuteron charge radius are discussed. The data of elastic electron scattering are inconsistent with the value obtained in a recent atomic physics experiment. Theoretical predictions based on a nonrelativistic description of the deuteron with realistic nucleon-nucleon potentials and with a rather complete set of meson-ex

Peter L. Polyakov

We prove that the integral operators $R_r$ and $H_r$ constructed in \cite{P} and such that $$f = \bar\partial_{\bold M} R_r(f) + R_{r+1}(\bar\partial_{\bold M} f) + H_r(f),$$ for a differential form $f \in C_{(0,r)}^{\infty}({\bold M})$ on a regular q-concave CR manifold ${\bold M}$ admit sharp estimates in the Lipschitz scale.

R. S. Dunne, A. J. Macfarlane, J. A. de Azcárraga, J. C. Pérez Bueno

A deformed $q$-calculus is developed on the basis of an algebraic structure involving graded brackets. A number operator and left and right shift operators are constructed for this algebra, and the whole structure is related to the algebra of a $q$-deformed boson. The limit of this algebra when $q$ is a $n$-th root of unity is also studied in detail. By mean

Sergio Ferrara

We report on recent advances in the understanding of non-perturbative phenomena in the quantum theory of fields and strings.

J. Alfaro, K. Bering, P. H. Damgaard

We show that constraints on the generating functional have direct BRST-extensions in terms of nilpotent operators $Δ$ that annihilate this generating functional, and which may be of arbitrarily high order. The free energy $F$ in the presence of external sources thus satisfies a ``Master Equation'' which is described in terms of a tower of higher anti

Ulf H. Danielsson, Gabriele Ferretti

We study the dynamics of D-particles (D0-branes) in type I' string theory and of the corresponding states in the dual heterotic description. We account for the presence of the two 8-orientifolds (8 dimensional orientifold planes) and sixteen D8-branes by deriving the appropriate quantum mechanical system. We recover the familiar condition of eight D8-bra

M. B. Halpern, N. A. Obers

We supplement the discussion of Moore and Reshetikhin and others by finding new semiclassical nonabelian vertex operators for the chiral, antichiral and nonchiral primary fields of WZW theory. These new nonabelian vertex operators are the natural generalization of the familiar abelian vertex operators: They involve only the representation matrices of Lie $g$

Michio Jimbo, Hitoshi Konno, Tetsuji Miwa

We consider an algebraic structure of the $XXZ$ model in the gapless regime. We argue that a certain degeneration limit of the elliptic algebra $A_{q,p}(\widehat{sl_2})$ is a relevant object. We give a free boson realization of this limiting algebra and derive an integral formula for the correlation function. The result agrees with the one obtained by solvin

A. A. Deriglazov

It is shown that the phase space of a dynamical system subject to second class constraints can be extended by ghost variables in such a way that some formal analogies of the $Ω$-charge and the unitarizing Hamiltonian can be constructed. Then BFV-type path integral representation for the generating functional of Green's functions is written and shown to c

J. F. Gunion, H. E. Haber, T. Moroi

We demonstrate that there are regions of parameter space in the next-to-minimal (i.e. two-Higgs-doublet, one-Higgs-singlet superfield) supersymmetric extension of the SM for which none of the Higgs bosons are observable either at LEP2 with $\sqrt{s}=192 GeV$ and an integrated luminosity of $L=1000 inverse pb$ or at the LHC with $L=600 inverse fb$.

D. -U. Jungnickel, C. Wetterich

We review the formalism of the effective average action in quantum field theory which corresponds to a coarse grained free energy in statistical mechanics. The associated exact renormalization group equation and possible nonperturbative approximations for its solution are discussed. This is applied to QCD where one observes the consecutive emergence of meson

W. Buchmuller

The presently observed cosmological baryon asymmetry has been finally determined at the time of the electroweak phase transition, when baryon and lepton number violating interactions fell out of thermal equilibrium. We discuss the thermodynamics of the phase transition based on the free energy of the SU(2) Higgs model at finite temperature, which has been st

A. Ali

We discuss the electromagnetic-penguin-dominated radiative B decays $B \to X_s + γ, ~B^{\pm (0)} \to K^{*\pm (0)} + γ$, and $B_s \to ϕ+ γ$ in the context of the standard model (SM) and their Cabibbo-Kobayashi-Maskawa (CKM)-suppressed counterparts, $B \to X_d + γ$, $B^\pm \to ρ^\pm + γ, ~B^{0} \to (ρ^{0}, ω) + γ$, and $B_s \to K^{* 0} + γ$, using QCD sum rule

S. Wallon

In this contribution we apply the QCD dipole picture combined with $k_T$-factorization to get predictions for deep-inelastic scattering on an onium. Assuming renormalization-group factorization, we get predictions for the $F_2, F_G$ and $R= F_L/F_T$ proton structure functions. We obtain a three-parameter fit of the 1994 H1 data in the low-$x_{bj}$, moderate-

W. Melnitchouk, M. Malheiro

Strange matrix elements of the nucleon are calculated within the light-cone formulation of the meson cloud model. The $Q^2$ dependence of the strange vector and axial vector form factors is computed, and the strangeness radius and magnetic moment extracted, both of which are found to be very small and slightly negative. Within the same framework one finds a

John C. Collins

I give an overview of what our present knowledge of QCD predicts and does not predict for polarized hard scattering. For experimental programs, a big issue is how much further we can expect our theoretical understanding of QCD to improve.

Yi-Jin Pei

We show that, based on the idea of string fragmentation, the production rates of light flavored mesons and baryons originating from fragmentation can be described by the spin, the binding energy of the particle, and a strangeness suppression factor. Apart from a normalization factor, $e^+ e^-$ data at different center-of-mass energies can be described simult

Martin Erdmann, Dirk Graudenz, Leif Lonnblad, Katsuo Tokushuku

The working group on jets and high-Et phenomena of the Future physics at HERA Workshop studied subjects ranging from next-to-leading order (NLO) corrections in deeply inelastic scattering (DIS) and photoproduction with the corresponding determinations of physical quantities, to the physics of instanton-induced processes, where a novel non-perturbative manife

M. Y. Ishida

The iso-singlet scalar resonance σ(600), found in the recent ππphase shift analysis, is pointed out to have the properties of the σmeson in the σmodel. The role of the λϕ^4 interaction as a source of the ``background phase", which was essential there, is also discussed.

Markus Heusler

The critical steps leading to the uniqueness theorem for the Kerr-Newman metric are reexamined in the light of the new black hole solutions with Yang-Mills and scalar hair. Various methods -- including scaling techniques, arguments based on energy conditions, conformal transformations and divergence identities -- are reviewed, and their range of application

V. S. Shumeiko, E. N. Bratus', G. Wendin

We present a consistent theory of superconductive tunneling in single-mode junctions within a scattering formulation of Bogoliubov-de Gennes quantum mechanics. Both dc Josephson effect and dc quasiparticle transport in voltage biased junctions are considered. Elastic quasiparticle scattering by the junction determines equilibrium Josephson current. We discus

Shaojin Qin, Yu-Liang Liu, Lu Yu

In this paper we study the finite size scaling for low energy excitations of $S=1$ and $S=2$ Heisenberg chains, using the density matrix renormalization group technique. A crossover from $1/L$ behavior (with $L$ as the chain length) for medium chain length to $1/L^2$ scaling for long chain length is found for excitations in the continuum band as the length o

Udo Seifert, Wolfgang Wintz, Philip Nelson

We investigate the propagation of a suddenly applied tension along a thermally excited semi-flexible polymer using analytical approximations, scaling arguments and numerical simulation. This problem is inherently non-linear. We find sub-diffusive propagation with a dynamical exponent of 1/4. By generalizing the internal elasticity, we show that tense strings

A. K. Kolezhuk, H. -J. Mikeska, Shoji Yamamoto

We propose a new version of the matrix product (MP) states approach to the description of quantum spin chains, which allows one to construct MP states with certain total spin and its z-projection. We show that previously known MP wavefunctions for integer-spin antiferromagnetic chains and ladders correspond to some particular cases of our general ansatz. Our

J. -S. Huang, L. L. Cowie, J. P. Gardner, E. M. Hu

We present the results of a wide-field K-selected galaxy survey with complementary optical I- and B-band imaging in six fields with a total coverage of 9.8 square degrees. This survey establishes the bright-end K-band galaxy number counts in the magnitude range 13<K<16 with high precision. We find that our bright-end counts have a significantly steeper slope

G. S. Da Costa, T. E. Armandroff, Nelson Caldwell, Patrick Seitzer

Images have been obtained with the Hubble Space Telescope WFPC2 camera of Andromeda I, a dwarf spheroidal (dSph) galaxy that lies in the outer halo of M31. The resulting color-magnitude diagrams reveal for the first time the morphology of the horizontal branch in this system. We find that, in a similar fashion to many of the galactic dSph companions, the hor

Marco Scodeggio, Riccardo Giovanelli, Martha P. Haynes

The Tully-Fisher and Fundamental Plane relations are used to obtain two independent estimates of the relative distance between the clusters A2634 and Coma. Previously published studies of A2634 showed a large discrepancy between the distance estimates obtained with the TF and the Dn-sigma relations, questioning the reliability of redshift-independent distanc

Jeff Skibo

In the local Galactic interstellar medium there is approximate energy equipartition between cosmic rays, magnetic fields and radiation. If this holds in the central regions of AGN, in particular Seyfert galaxies, then consideral nuclear spallation of Fe occurs, resulting in enhanced abundances of the sub-Fe elements Ti, V, Cr and Mn. These elements produce a

Shiho Kobayashi, Shin Sasaki, Yasushi Suto

We performed a systematic and comprehensive estimate of the Hubble constant $H_0$ via the Sunyaev-Zel&#39;dovich temperature decrement and the X-ray measurements for clusters up to the redshift $z=0.541$, with particular attention to its dependence on the density parameter $Ω_0$, and the cosmological constant $λ_0$. The resulting values of $H_0$ are largely

Dave Bayer, Irena Peeva, Bernd Sturmfels

Call a monomial ideal M &#34;generic&#34; if no variable appears with the same nonzero exponent in two distinct monomial generators. Using a convex polytope first studied by Scarf, we obtain a minimal free resolution of M. Any monomial ideal M can be made generic by deformation of its generating exponents. Thus, the above construction yields a (usually nonmi

Bas Edixhoven

We prove, assuming the Generalized Riemann Hypothesis for imaginary quadratic fields, that irreducible curves in the product of two modular curves that contain infinitely many complex multiplication points are either a Hecke correspondence or a fibre for one of the two projections. This gives evidence for a conjecture of Oort that says that irreducible compo

John McDonald

We consider nucleosynthesis constraints on models which use chiral symmetry breaking as a basis for understanding very small Dirac neutrino masses. We show that present big-bang nucleosynthesis constraints impose a well-defined upper bound of 0.1eV on the neutrino masses. This bound may become several orders of magnitude more stringent in the future as our u

J. McDonald

We consider the possibility of a successful Affleck-Dine mechanism along the u^c d^c d^c direction in R-parity symmetric extensions of the minimal supersymmetric Standard Model (MSSM) which contain a gauge singlet superfield phi. Such gauge singlets commonly occur in extensions of the MSSM, for example in models which seek to account for neutrino masses. We

Vijay Balasubramanian, Finn Larsen

The supersymmetric p-branes of Type II string theory can be interpreted after compactification as extremal black holes with zero entropy and infinite temperature. We show how the p-branes avoid this apparent, catastrophic instability by developing an infinite mass gap. Equivalently, these black holes behave like elementary particles: they are dressed by effe

Joel Primack

I have been asked to make the case here that CHDM is the best theory of cosmic structure formation, and indeed I believe that it is the best of all those I have considered if the cosmological matter density is near critical and if the expansion rate is not too large (i.e. $h \equiv H_0/(100 \kmsMpc) \lsim 0.6$). I discuss CHDM together with its chief competi

T. L. Trueman

Coulomb-nuclear interference in the single transverse spin asymmetry A_N is often considered as a possible absolute polarimeter for proton beams. The main uncertainty in this is the unknown hadronic spin-flip amplitude. This uncertainty is analyzed here in the context of the challenge of a 5% polarization measurement at RHIC. Possible constraints on the spin

Sergio Caracciolo, Andrea Pelissetto

We discuss the connection between various types of improved actions in the context of the two-dimensional sigma-model. We also discuss spectrum-improved actions showing that these actions do not have any improved behaviour. An O(a^2) on-shell improved action with all couplings defined on a plaquette and satisfying reflection positivity is also explicitly con

W. Cui, S. N. Zhang, K. Jahoda, W. Focke

We reported previously that for Cyg X-1 there is a settling period following the transition from hard to soft state (astro-ph/9610071). During the transiton, The low energy spectrum (below ~10 keV) varies significantly from observation to observation while the high energy portion changes little. The source reaches nominal soft-state brightness during the set

M S Yang, K H Mütter

We present numerical results on the zero temperature magnetization curve and the static structure factors of the two dimensional antiferromagnetic Heisenberg model in the presence of an external field. The impact of frustration is also studied.

B. Linet

We give an analysis of the spin-weighted Green&#39;s functions well-defined in a conical space. We apply these results in the case of a straight cosmic string and in the Rindler space in order to determine generally the Euclidean Green&#39;s functions for the massless spin 1/2 field and for the electromagnetic field. We give also the corresponding Green&#39;

Itzhak Bars

The Beckenstein-Hawking black hole entropy in string theory and its extensions, as expressed in terms of charges that correspond to central extensions of the supersymmetry algebra, has more symmetries than U-duality. It is invariant under transformations of the charges, involving a 12th (or 13th) ``dimension&#39;&#39;. This is an indication that the secret t

E. J. Kerins

Hubble Space Telescope (HST) limits on the amount of halo dark matter (DM) in the form of very low-mass (VLM) stars close to the hydrogen-burning limit have been interpreted as excluding such stars as viable candidates. However, these limits assume that the stars are smoothly distributed and have at least the metallicity of Population II stars, whilst some b

C. Adloff, H1 Collaboration

Transverse momentum spectra of charged particles produced in deep inelastic scattering are measured as a function of the kinematic variables x_B and Q2 using the H1 detector at the ep collider HERA. The data are compared to different parton emission models, either with or without ordering of the emissions in transverse momentum. The data provide evidence for

A. A. Rosly, K. G. Selivanov

The paper is withdrawn because we realized triviality of the main considered example. Less trivial examples are provided in other our papers on the subject.

Y. Hashimoto, Y. Yasui, S. Miyagi, T. Otsuka

The Ashtekar-Mason-Newman equations are used to construct the hyperkähler metrics on four dimensional manifolds. These equations are closely related to anti self-dual Yang-Mills equations of the infinite dimensional gauge Lie algebras of all volume preserving vector fields. Several examples of hyperkähler metrics are presented through the reductions of anti