September 1999 arXiv papers — page 11

The E864 Collaboration, Zhangbu Xu

Light nuclei can be produced in the central reaction zone via coalescence in relativistic heavy ion collisions. E864 at BNL has measured the production of ten stable light nuclei with nuclear number of A=1 to A=7 at rapidity $y\simeq1.9$ and $p_{T}/A\leq300MeV/c$. Data were taken with a Au beam of momentum of 11.5 A $GeV/c$ on a Pb or Pt target with differen

I. V. Krasovsky

We obtain the asymptotic distribution of eigenvalues of real symmetric tridiagonal matrices as their dimension increases to infinity and whose diagonal and off-diagonal elements asymptotically change with the index n as J_{nt+i nt+i}\sim a_iϕ(n), J_{nt+i nt+i+1}\sim b_iϕ(n), i=0,1,...,t-1, where a_i and b_i are finite, and ϕ(n) belongs to a certain class of

I. V. Krasovsky

We propose a way to find the asymptotic distribution of zeros of orthogonal polynomials p_n(x) satisfying a difference equation of the form B(x)p_n(x+δ)-C(x,n)p_n(x)+D(x)p_n(x-δ)=0. We calculate the asymptotic distribution of zeros and asymptotics of extreme zeros of the Meixner and Meixner-Pollaczek polynomials. The distribution of zeros of Meixner polynomi

G. I. Barenblatt, A. J. Chorin, A. Kast

The classical problem of thermal explosion is modified so that the chemically active gas is not at rest but is flowing in a long cylindrical pipe. Up to a certain section the heat-conducting walls of the pipe are held at low temperature so that the reaction rate is small and there is no heat release; at that section the ambient temperature is increased and a

G. I. Barenblatt, J. B. Bell, W. Y. Crutchfield

The classical problem of the thermal explosion in a long cylindrical vessel is modified so that only a fraction $\a$ of its wall is ideally thermally conducting while the remaining fraction $1-\a$ is thermally isolated. Partial isolation of the wall naturally reduces the critical radius of the vessel. Most interesting is the case when the structure of the bo

A. J. Chorin, A. Kast, R. Kupferman

We present a theoretical framework and numerical methods for predicting the large-scale properties of solutions of partial differential equations that are too complex to be properly resolved. We assume that prior statistical information about the distribution of the solutions is available, as is often the case in practice. The quantities we can compute condi

Shinar Kouranbaeva, Steve Shkoller

This paper presents a geometric-variational approach to continuous and discrete {\it second-order} field theories following the methodology of \cite{MPS}. Staying entirely in the Lagrangian framework and letting $Y$ denote the configuration fiber bundle, we show that both the multisymplectic structure on $J^3Y$ as well as the Noether theorem arise from the f

Jerrold E. Marsden, Sergey Pekarsky, Steve Shkoller

In this paper, discrete analogues of Euler-Poincaré and Lie-Poisson reduction theory are developed for systems on finite dimensional Lie groups $G$ with Lagrangians $L:TG \to {\mathbb R}$ that are $G$-invariant. These discrete equations provide ``reduced'' numerical algorithms which manifestly preserve the symplectic structure. The manifold $G \times

Jordan S. Ellenberg

The ABC conjecture of Masser and Oesterle&#39; states that if (a,b,c) are coprime integers with a + b + c = 0, then sup(|a|,|b|,|c|) < c_e (rad(abc))^{1+e} for any e > 0. Oesterle&#39; has observed that if the ABC conjecture holds for all (a,b,c) with 16 | abc, then the full ABC conjecture holds. We extend that result to show that, for every integer N, the &

Edi Halyo

We discuss the conditions under which 4D gravity is localized on domain walls in 5D anti-de Sitter spaces. Our approach is based on considering the limits in which the localized gravity decouples. We find that gravity is localized if the wall is located a finite distance from the boundary of the anti-de Sitter space and has a finite tension. In addition, it

Bo Feng, Amihay Hanany, Yang-Hui He

Generalising ideas of an earlier work \cite{Bo-Han}, we address the problem of constructing Brane Box Models of what we call the Z-D Type from a new point of view, so as to establish the complete correspondence between these brane setups and orbifold singularities of the non-Abelian G generated by Z_k and D_d under certain group-theoretic constraints to whic

Romuald A. Janik

We use the AdS/CFT correspondence to study near forward scattering of colourless objects in gauge theory in the high energy limit. We find an unexpected from the gauge theory perspective `gravity-like&#39; s^1 behaviour of the amplitudes coming from bulk graviton exchange. The details of the calculations are presented in hep-th/9907177.

Mitsuaki Fukae, Yasuhiko Yamada, Sung-Kil Yang

We analyze the structure of singularities, Mordell-Weil lattices and torsions of a rational elliptic surface using string junctions in the background of 12 7-branes. The classification of the Mordell-Weil lattices due to Oguiso-Shioda is reproduced in terms of the junction lattice. In this analysis an important role played by the global structure of the surf

V. Emel&#39;yanov, A. Khodinov, S. R. Klein, R. Vogt

The effect of shadowing on the early state of ultrarelativistic heavy ion collisions is investigated along with transverse energy and hard process production, specifically Drell-Yan, $J/ψ$, and $Υ$ production. We choose several parton distributions and parameterizations of nuclear shadowing, as well as the spatial dependence of shadowing, to study the influe

R. D. Amado, M. A. Halasz, P. Protopapas

We present our first results of numerical simulations of two skyrmion dynamics using an $ω$-meson stabilized effective Lagrangian. We consider skyrmion-skyrmion scattering with a fixed initial velocity of $β=0.5$, for various impact parameters and groomings. The physical picture that emerges is surprisingly rich, while consistent with previous results and ge

P. Colangelo, F. De Fazio

The form factors parameterizing the B_c semileptonic matrix elements can be related to a few invariant functions if the decoupling of the spin of the heavy quarks in B_c and in the mesons produced in the semileptonic decays is exploited. We compute the form factors as overlap integral of the meson wave-functions obtained using a QCD relativistic potential mo

H. Spiesberger

The prospects of physics beyond the standard model in deep inelastic scattering are reviewed, emphasizing the search for contact interactions, for leptoquarks and for supersymmetry with R-parity violation. R-parity violating supersymmetry is explored as a speculative source of events with high energy muons and missing transverse momentum, but no convincing e

A. Bialas

It is shown that that Gaussian fluctuations of the string tension can account for the &#34;thermal&#34; distribution of transverse mass of particles created in decay of a colour string.

Jukka Maalampi, Nikolai Romanenko

We investigate the reaction e,e->mu, nu, q, q as a possible place to test the lepton number violating interactions of singly charged scalars (Delta(L)) belonging to a SU(2)L triplet. The existence of such scalars is predicted by some majoron models, as well as by the left-right symmetric extension of the Standard Model. We show that this reaction may be obse

A. H. Hoang

A review on theoretical aspects of top quark physics at the Linear Collider is given with focus on the process $e^+e^-\to t\bar t$ and the presentations given at this conference.

C. Boros, J. T. Londergan, A. W. Thomas

We discuss the momentum distributions of inclusively produced particles in $e^+e^-$ annihilation. We show that the dependence of the position of the maxima of the $\xi=\ln(1/z)$ spectra on the mass of the produced particles follows naturally from the general definition of fragmentation functions when energy-momentum conservation is correctly incorporated.

Prem P. Srivastava

The {\it front form} framework for describing the quantized theory of chiral boson is discussed. It avoids the conflict with the requirement of the principle of microcausality as is found in the conventional equal- time treatment. The discussion of the Floreanini-Jackiw model and its modified version for describing the chiral boson becomes very transparent o

PACS Collaboration, A. Ali Khan, S. Aoki, R. Burkhalter

We report on recent results for the spectrum of heavy quarkonia. Using coarse and anisotropic lattices we achieved an unprecedented control over statistical and systematic errors for higher excited states such as exotic hybrid states. In a parallel study on isotropic lattices we also investigate the effect of two dynamical flavours on the spin structure of c

F. Farchioni, I. Hip, C. B. Lang

We compare the lower edge spectral fluctuations of the staggered lattice Dirac operator for the Schwinger model with the predictions of chiral Random Matrix Theory (chRMT). We verify their range of applicability, checking in particular the role of non-trivial topological sectors and the flavor symmetry of the staggered fermions for finite lattice spacing. Ap

Eamonn Cahill, Alan Irving, Christopher Johnson, James Sexton

The Lanczos algorithm for matrix tridiagonalisation suffers from strong numerical instability in finite precision arithmetic when applied to evaluate matrix eigenvalues. The mechanism by which this instability arises is well documented in the literature. A recent application of the Lanczos algorithm proposed by Bai, Fahey and Golub allows quadrature evaluati

W. Sakuler, S. Thurner, H. Markum

We analyze the topological and fermionic vacuum structure of four-dimensional QCD on the lattice by means of correlators of fermionic observables and topological densities. We show the existence of strong local correlations between the topological charge and monopole density on the one side and the quark condensate, charge and chiral density on the other sid

J. Ambjorn, K. N. Anagnostopoulos, R. Loll

In an extension of earlier work we investigate the behaviour of two-dimensional Lorentzian quantum gravity under coupling to a conformal field theory with c>1. This is done by analyzing numerically a system of eight Ising models (corresponding to c=4) coupled to dynamically triangulated Lorentzian geometries. It is known that a single Ising model couples wea

M. Lefebvre, R. K. Keeler, R. Sobie, J. White

A formula is given for the propagation of errors during matrix inversion. An explicit calculation for a 2 by 2 matrix using both the formula and a Monte Carlo calculation are compared. A prescription is given to determine when a matrix with uncertain elements is sufficiently nonsingular for the calculation of the covariances of the inverted matrix elements t

L P Grishchuk

A recent paper by Martin and Schwarz [1] argues that the ``standard inflationary result&#34; has been finally proven. The result itself is formulated as: ``the closer the inflationary epoch is to the de Sitter space-time, the less important are large-scale gravitational waves in the CMBR today&#34;. Beginning from the basic equations of Grishchuk [2, 3] the

Jan Willemson

Research in the field of electronic signature confirmation has been active for some 20 years now. Unfortunately present certificate-based solutions also come from that age when no-one knew about online data transmission. The official standardized X.509 framework also depends heavily on offline operations, one of the most complicated ones being certificate re

Ron Lifshitz, M. L. Roukes

The importance of thermoelastic damping as a fundamental dissipation mechanism for small-scale mechanical resonators is evaluated in light of recent efforts to design high-Q micrometer- and nanometer-scale electro-mechanical systems (MEMS and NEMS). The equations of linear thermoelasticity are used to give a simple derivation for thermoelastic damping of sma

K. Ø. Rasmussen, T. Cretegny, P. G. Kevrekidis, N. Grønbech-Jensen

Statistical mechanics of the discrete nonlinear Schrödinger equation is studied by means of analytical and numerical techniques. The lower bound of the Hamiltonian permits the construction of standard Gibbsian equilibrium measures for positive temperatures. Beyond the line of $T=\infty$, we identify a phase transition, through a discontinuity in the partitio

Adolfo E. Trumper, Luca Capriotti, Sandro Sorella

We present a finite size spin wave calculation on the Heisenberg antiferromagnet on the triangular lattice focusing in particular on the low-energy part of the excitation spectrum. For s=1/2 the good agreement with the exact diagonalization and quantum Monte Carlo results supports the reliability of the spin wave expansion to describe the low-energy spin exc

G. M. Wysin

The Onsager reaction-field (ORF) theory is extended so that it applies to any three-dimensional Bravais lattice with a basis. The ORF calculation is used to predict the critical temperature for classical Ising, XY, and Heisenberg magnetic models, in particular, on diamond and hexagonal close packed lattices. Results are compared with series extrapolations an

Damien Challet, Matteo Marsili, Yi-Cheng Zhang

Using the Minority Game model we study a broad spectrum of problems of market mechanism. We study the role of different types of agents: producers, speculators as well as noise traders. The central issue here is the information flow : producers feed in the information whereas speculators make it away. How well each agent fares in the common game depends on t

Natalie Pavlenko

The protonic conductivity in the hydrogen bonded chains is investigated theoretically in the framework of the two-stage transport model. The strong interactions with optical phonon stretching mode are considered. We obtain the transition from the insulator to the metal-type state from the temperature dependencies of the hopping conductivity and analyze the i

J. E. McCrone, J. R. Cooper, J. L. Tallon

RuSr_2GdCu_2O_8 (Ru-1212) is a triple perovskite containing both CuO_2 and RuO_2 layers. It has attracted a great deal of interest recently because it displays electronic ferromagnetism and superconductivity coexisting on a microscopic scale, with T_Curie of 135K and T_c up to 50K. We report magnetisation and magnetoresistance (MR) data that exhibit effects

Kazuhisa Kaneda, Yutaka Okabe, Macoto Kikuchi

The finite-size scaling functions for anisotropic three-dimensional Ising models of size $L_1 \times L_1 \times aL_1$ ($a$: anisotropy parameter) are studied by Monte Carlo simulations. We study the $a$ dependence of finite-size scaling functions of the Binder parameter $g$ and the magnetization distribution function $p(m)$. We have shown that the finite-siz

J. Bergenholtz, M. Fuchs

The idealized mode coupling theory (MCT) is applied to colloidal systems interacting via short-range attractive interactions of Yukawa form. At low temperatures MCT predicts a slowing down of the local dynamics and ergodicity breaking transitions. The nonergodicity transitions share many features with the colloidal gel transition, and are proposed to be the

Xiang-Yu Ge

Integrable open-boundary condition for the q-deformed Essler-Korepin-Schoutens extended Hubbard model of strongly correlated electrons, are studied in the framework of the boundary quantum inverse scattering method. Diagonal boundary K-matrices are found, and nine classes of integrable boundary terms are determined.

V. Yu. Irkhin, A. A. Katanin

Isotropic S=1/2 quasi-one-dimensional antiferromagnets are considered within the bosonization method. The 1/zp-corrections to the interchain mean-field theory (zp is the number of nearest neighbors in transverse to chain directions) are obtained for the ground-state sublattice magnetization and Neel temperature T_N. The corrections to T_N make up about 25% o

K. Ramasubramanian, M. S. Sriram

In this paper we make a detailed numerical comparison between three algorithms for the computation of the full Lyapunov spectrum as well as the associated eigen-vectors of general dynamical systems. They are : (a) the standard method, (b) a differential formaulation of the standard method, and (c) a new algorithm which does not require rescaling and reorthog

M. Ipsen, P. G. Soerensen

In this letter, we discuss the effect of slow real modes in reaction-diffusion systems close to a supercritical Hopf bifurcation. The spatio-temporal effects of the slow mode cannot be captured by traditional descriptions in terms of a single complex Ginzburg-Landau equation (CGLE). We show that the slow mode coupling to the CGLE, introduces a novel set of f

Kevork Abazajian, Xiangdong Shi, George M. Fuller

We examine in detail the changes in the production of primordial helium resulting from nonthermal neutrino momentum distributions produced by resonant transformation of electron-type neutrinos to steriles. These transformations, anti-nu_e -> anti-nu_s (nu_e->nu_s), amplify a positive (negative) lepton number asymmetry. We find that the resulting supression r

Robert E. Rutledge, Lars Bildsten, Edward F. Brown, George G. Pavlov

We fit hydrogen atmosphere models to the X-ray data for four neutron stars (three from a previous paper, plus 4U 2129+47) and six black hole candidates (A0620-00, GS 2000+25, GS 1124-68, GS 2023+33, GRO J1655-40, and GRO J0422+32). While the neutron stars are similar in their intrinsic X-ray spectra (similar effective temperatures and emission area radii ~10

Valery M. Nakariakov, Cesar A. Mendoza-Briceno, Miguel H. Ibanez S.

The evolution of quasi-isentropic magnetohydrodynamic waves of small but finite amplitude in an optically thin plasma is analyzed. The plasma is assumed to be initially homogeneous, in thermal equilibrium and with a straight and homogeneous magnetic field frozen in. Depending on the particular form of the heating/cooling function, the plasma may act as a dis

Almudena Alonso-Herrero, Marcia J. Rieke, George H. Rieke, Joseph C. Shields

We present $J$-band ($1.15-1.35 μ$m) spectroscopy of a sample of nine galaxies showing some degree of LINER activity (classical LINERs, weak-[O {\sc i}] LINERs and transition objects), together with $H$-band spectroscopy for some of them. A careful subtraction of the stellar continuum allows us to obtain reliable [Fe {\sc ii}]$1.2567 μ$m/Pa$β$ line ratios. W

T. Wiklind, F. Combes

The use of molecular absorption lines in deriving the timde delay in PKS1830-211 is described, as well as results from a three year monitoring campaign. The time delay and the implied value for the Hubble constant are presented.

T. Shibatsuka, K. Kohno, S. Matsushita, R. Kawabe

We have performed high resolution CO(2-1), CO(1-0), HCN(1-0) and HCO+(1-0) observations of a &#34;low star formation efficiency starburst galaxy&#34; NGC 4527 with the Nobeyama Millimeter Array. The integrated intensity ratios, CO(2-1)/CO(1-0) and HCN(1-0)/CO(1-0), are found to be 0.6 +/- 0.05 and 0.06 +/- 0.007, respectively, at the center. These line ratio

A. R. King, G. A. Wynn

We show that the spin period of the white dwarf in the magnetic CV EX Hydrae represents an equilibrium state in which the corotation radius is comparable with the distance from the white dwarf to the inner Lagrange point. We also show that a continuum of spin equilibria exists at which Pspin is significantly longer than \sim 0.1 Porb. Most systems occupying

Karen B. Kwitter, Richard C. Henry

We previously determined abundances of He, C, N, O, and Ne for a sample of planetary nebulae (PNe) representing a broad range in progenitor mass and metallicity, and we now compare them with theoretical predictions of PNe abundances from a grid of intermediate-mass star models. We find very good agreement between observations and theory, lending strong suppo

John R. Lucey, Russell J. Smith, Michael J. Hudson, David J. Schlegel

Galaxy clusters are important targets for peculiar velocity studies as a direct comparison of the various distance indicators can be made. The potential problem of an environmental effect biasing the distances to clusters of different richness is examined. The level of intrinsic cluster-to-cluster variations is also reviewed. We investigate the claim that th

Joshua C. Kempner, Craig L. Sarazin

The Westerbork Northern Sky Survey (WENSS) and the NRAO/VLA Sky Survey (NVSS) were used to determine an upper limit to the diffuse radio flux from the nearby cluster Abell 2199. For the entire cluster, this limit is <3.25 Jy at 327 MHz from WENSS; for the inner 15&#39; radius, the limit is <168 mJy at 1.4 GHz. These limits are used to constrain the cluster m

Michael J. Hudson, Russell J. Smith, John R. Lucey, David J. Schlegel

We compare the bulk flow of the SMAC sample to the predictions of popular cosmological models and to other recent large-scale peculiar velocity surveys. Both analyses account for aliasing of small-scale power due to the sparse and non-uniform sampling of the surveys. We conclude that the SMAC bulk flow is in marginal conflict with flat COBE-normalized Lambda

Victor P. Debattista, T. B. Williams

We report on absorption-line Fabry-Perot spectroscopy of the SB0 galaxy NGC 7079. Our data allow us to determine velocity and dispersion maps, which compare well with the results of slit observations. Our goals are to obtain a bar pattern speed and to determine the velocity ellipsoid as a function of radius; this is work in progress.

Russell J. Smith, Michael J. Hudson, John R. Lucey, David J. Schlegel

The SMAC project is a Fundamental Plane peculiar velocity survey of 56 clusters of galaxies to a depth of cz ~ 12000 km/s. We present here some results from the analysis of the SMAC velocity field, focussing on three specific features: the best-fitting bulk-flow model for the SMAC data; the agreement between the observed velocity field and predictions from t

O. R. Prouton, S. J. Warren, A. E. Wright

We are surveying the region -87 < delta < -38.5 for multiple imaging at scales 1 < theta < 15 arsec. Candidate gravitational lenses were selected from an existing dataset of Australia Telescope Compact Array measurements of 2178 flat (4.80/8.64 GHz) spectrum PMN sources. Selection criteria were optimised using tests on simulated lens datasets.

Shude Mao

Ongoing microlensing surveys have already yielded more than five hundred microlensing events, most of which have been identified in real-time. In this review I present the basic theory and observational status of these surveys. I highlight the discoveries made so far - these include constraints on the dark matter content of the Galaxy, the structure and mass

Charles H. Lineweaver

The details of the CMB power spectrum are being revealed through the combined efforts of the world&#39;s CMBologists. The current data set constrains several cosmological parameters. A combination with other (non-lensing) constraints yields estimates of the cosmological constant: Omega_Lambda = 0.65 +/- 0.13, the mass density: Omega_m = 0.23 +/- 0.08 and the

M. S. Burgin, A. Chalabaev

When planning new facilities, one is interested to know whether and by how much the new technique is superior to already existing ones. We describe a general approach permitting to evaluate the relative merits of various techniques used in astrophysical observations, following the theory of model parameter estimation. It is applied to compare two-aperture op

E. E. Fenimore, E. Ramirez-Ruiz

Gamma-ray bursts (GRBs) have been thought to originate from internal shocks that occur about 10^{15} cm from a central site. The shells responsible for these shocks merge together and undergo an external shock at about 10^{17} cm, producing the afterglows. We include deceleration in our model of internal shocks and find that, for values of the Lorentz factor

V Guruprasad

Tidal distension of spacecraft electronics due to spin and solar and galactic gravitation elegantly explains all variations in the anomaly reported by Anderson et al. Contrary to their conclusion, a constant residue seems to be present in lunar, terrestrial, and possibly planetary measurements, posing a problem of wider, more fundamental significance.

Matthias Arnsdorf, Sameer Gupta

We present a general procedure for constructing new Hilbert spaces for loop quantum gravity on non-compact spatial manifolds. Given any fixed background state representing a non-compact spatial geometry, we use the Gel&#39;fand-Naimark-Segal construction to obtain a representation of the algebra of observables. The resulting Hilbert space can be interpreted

M. Cvetic, S. S. Gubser, H. Lu, C. N. Pope

A class of conformally flat and asymptotically anti-de Sitter geometries involving profiles of scalar fields is studied from the point of view of gauged supergravity. The scalars involved in the solutions parameterise the SL(N,R)/SO(N) submanifold of the full scalar coset of the gauged supergravity, and are described by a symmetric potential with a universal

Craig J. Hogan

Some properties of the world are fixed by physics derived from mathematical symmetries, while others are selected from an ensemble of possibilities. Several successes and failures of ``anthropic&#39;&#39; reasoning in this context are reviewed in the light of recent developments in astrobiology, cosmology and unification physics. Specific issues raised inclu

Steven W. Rick

Different schemes for the treatment of long-ranged electrostatic interactions will be examined for water simulations using the polarizable fluctuating charge potential. Several different methods are compared, including Ewald sums, potential shifting, spherical truncation and reaction field corrections. For liquid water, properties such as the energy, pressur

E. Gabrielli

The extended Yang-Mills gauge theory in Euclidean space is a renormalizable (by power counting) gauge theory describing a local interacting theory of scalar, vector, and tensor gauge fields (with maximum spin 2). In this article we study the quantum aspects and various generalizations of this model in Euclidean space. In particular the quantization of the pu

Sidney van den Bergh

It is argued that the astronomy of the twenty-first century will be dominated by computer-based manipulation of huge homogeneous surveys of various types of astronomical objects. Furthermore combination of all observations with large telescopes into a single database will allow data mining on an unprecedented scale.

G. Lopez Castro, G. Toledo Sanchez

The contribution of the rho^{\pm} vector meson to the tau -> pi pi nu gamma decay is considered as a potential source for the determination of the magnetic dipole moment of this light vector meson. In order to keep gauge-invariance of the whole decay amplitude, a procedure similar to the fermion loop-scheme for charged gauge bosons is implemented to incorpor

Roger Tribe, Oleg Zaboronski

The decay of Burgers turbulence with compactly supported Gaussian &#34;white noise&#34; initial conditions is studied in the limit of vanishing viscosity and large time. Probability distribution functions and moments for both velocities and velocity differences are computed exactly, together with the &#34;time-like&#34; structure functions . The analysis of

Adam K. Leibovich, Ian Low, I. Z. Rothstein

We present a closed form expression for |V_{ub}|^2/ |V_{tb} V_{ts}^*|^2 in terms of the endpoint photon and lepton spectra from the inclusive decays B -> X_sγand B -> X_u\ellν, respectively, which includes the resummation of the endpoint logs at next to leading order and is completely independent of the B meson structure function. The use of this expression

Q. P. Liu, Manuel Manas

We construct Darboux transformations for the super-symmetric KP hierarchies of Manin--Radul and Jacobian types. We also consider the binary Darboux transformation for the hierarchies. The iterations of both type of Darboux transformations are briefly discussed.

P. Zinn-Justin

In this letter, the 6-vertex model on dynamical random lattices is defined via a matrix model and rewritten (following I. Kostov) as a deformation of the O(2) model. In the large N planar limit, an exact solution is found at criticality. The critical exponents of the model are determined; they vary continously along the critical line. The vicinity of the lat

R. J. Rivers

We examine the Zurek scenario for the production of vortices in quenches of liquid $^{4}He$ in the light of recent experiments. Extending our previous results to later times, we argue that short wavelength thermal fluctuations make vortices poorly defined until after the transition has occurred. Further, if and when vortices appear, it is plausible that that

Jonas Blom, Edwin Langmann

Yang-Mills gauge theory models on a cylinder coupled to external matter charges provide powerful means to find and solve certain non-linear integrable systems. We show that, depending on the choice of gauge group and matter charges, such a Yang-Mills model is equivalent to trigonometric Calogero-Moser systems and certain known spin generalizations thereof. C

A. Minkin

S.G.Krein&#39;s conjecture concerning Birkhoff-regularity of dissipative differential operators has been proved in the even order case. As a byproduct an existence of the limit of characteristic matrix as in the lower half-plane has been established. Up to multiplication by a nonvanishing matrix this limit coincides with the ratio of the matrices of regulari

J. Craig Wheeler, Insu Yi, Peter Hoeflich, Lifan Wang

We outline the possible physical processes, associated timescales, and energetics that could lead to the production of pulsars, jets, asymmetric supernovae, and weak gamma-ray bursts in routine circumstances and to a magnetar and perhaps stronger gamma-ray burst in more extreme circumstances in the collapse of the bare core of a massive star. The production

Adam Doliwa

The asymptotic lattices and their transformations are studied within the line geometry approach. It is shown that the discrete asymptotic nets are represented by isotropic congruences in the Plucker quadric. On the basis of the Lelieuvre-type representation of asymptotic lattices and of the discrete analog of the Moutard transformation, it is constructed the

N. Tsoneva, Ch. Stoyanov, Yu. P. Gangrsky, V. Yu. Ponomarev

The value of an isomeric ratio (IR) in N=81 isotones ($^{137}$Ba, $^{139}$Ce, $^{141}$Nd and $^{143}$Sm) is studied by means of the ($γ, n)$ reaction. This quantity measures a probability to populate the isomeric state in respect to the ground state population. In ($γ, n)$ reactions, the giant dipole resonance (GDR) is excited and after its decay by a neutro

Jeppe R. Andersen

In this paper we describe a renormalon-inspired model of twist--4 power corrections to the light-cone pion distribution amplitude, and compare it to the results obtained using the conformal wave expansion. We find that the overall functional form predicted in this renormalon model is similar to the one predicted in the standard approach to higher twist contr

N. G. Kelkar, B. K. Jain

We present calculations of the invariant mass spectra of the $Λ$p system for the exclusive $p p \to K^+ Λp$ reaction with the aim of studying the final state interaction between the $Λ$-hyperon and the proton. The reaction is described within a meson exchange framework and the final state $Λp$ interaction is incorporated through an off-shell t-matrix for the

L. R. Huiszoon, A. N. Schellekens, N. Sousa

The standard Klein bottle coefficient in the construction of open descendants is shown to equal the Frobenius-Schur indicator of a conformal field theory. Other consistent Klein bottle projections are shown to correspond to simple currents. These observations enable us to generalize the standard open string construction from C-diagonal parent theories to inc

Keita Kishigi, Yasumasa Hasegawa, Mitake Miyazaki

We study the effects of the Zeeman term on the de Haas van Alphen (dHvA) oscillation in two-dimensional two-band systems. We found that the Fourier transform amplitudes of the oscillations are not described by the spin reduction factor in the Lifshitz-Kosevich formalism in two-dimensional systems. The anomalous dependence on the effective $g$-factor can be o

L. D. Paniak

A five-dimensional Chern-Simons gravity theory based on the anti-de Sitter group SO(4,2) is argued to be a useful model in which to understand the details of holography and the relationship between generally covariant and dual local quantum field theories. Defined on a manifold with boundary, conformal geometry arises naturally as a gauge invariance preservi

D. B. Fairlie, A. N. Leznov

A general solution to the Complex Monge-Ampère equation in a space of arbitrary dimensions is constructed.

D. B. Fairlie, A. N. Leznov

A general solution to the Complex Bateman equation in a space of arbitrary dimensions is constructed.

D. B. Fairlie, A. N. Leznov

The general solution to the Complex Monge-Ampère equation in a two dimensional space is constructed.

D. B. Fairlie, A. N. Leznov

The general solution to the Complex Bateman equation is constructed. It is given in implicit form in terms of a functional relationship for the unknown function. The known solution of the usual Bateman equation is recovered as a special case.

A. A. Ketsaris

We develop a new concept of quantum mechanics which is based on a generalized space-time and on an action vector space similar to it. Both spaces are provided by algebraic properties. This allows to calculate the Dirac matrixes and to derive quantum mechanics equations from structure equations of the specified algebras. A new interpretation of the wave funct

K. Banaszek, G. M. D&#39;Ariano, M. G. A. Paris, M. F. Sacchi

We present a universal technique for quantum state estimation based on the maximum-likelihood method. This approach provides a positive definite estimate for the density matrix from a sequence of measurements performed on identically prepared copies of the system. The method is versatile and can be applied to multimode radiation fields as well as to spin sys

A. Rocco, P. Grigolini

We revisit the Markov approximation necessary to derive ordinary Brownian motion from a model widely adopted in literature for this specific purpose. We show that this leads to internal inconsistencies, thereby implying that further search for a more satisfactory model is required.

De-Hone Lin

A method for calculating the relativistic path integral solution via sum over perturbation series is given. As an application the exact path integral solution of the relativistic Aharonov-Bohm-Coulomb system is obtained by the method. Different from the earlier treatment based on the space-time transformation and infinite multiple-valued trasformation of Kus

Thomas R. Lemberger

Thermodynamics of magnetic materials is discussed in practical, lab-oriented terms. In the common experimental configuration in which the external magnetic field comes from a solenoidal coil connected to a power supply, magnetic work is identified unambiguously as the flow of electromagnetic field energy from the power supply into the system via the connecti

Tomoyuki Maruyama, Satoshi Chiba

We study the excited energy of the isoscalar giant quadrupole resonance with the scaling method in the relativistic many-body framework. In this calculation we introduce the momentum-dependent parts of the Dirac self-energies arising from the one-pion exchange on the assumption of the pseudo-vector coupling with nucleon field. It is shown that this momentum-

Russell Lyons

We prove singularity of some distributions of random continued fractions that correspond to iterated function systems with overlap and a parabolic point. These arose while studying the conductance of Galton-Watson trees.

Allen Hatcher

We consider the space of all smooth knots in the 3-sphere isotopic to a given knot, with the aim of finding a small subspace onto which this large space deformation retracts. For torus knots and many hyperbolic knots we show the subspace can be taken to be the orbit of a single maximally symmetric placement of the knot under the action of SO(4) by rotations

Andrei Tyurin

The complex version of Bohr-Sommerfeld conditions is proposed. The BPU-construction (see [D.Borthwick, T. Paul and A. Uribe, Legendrian distributions with applications to the non-vanishing of Poincaré series of large weight, Invent. math, 122 (1995), 359-402, preprint hep-th/9406036] or [Andrei Tyurin, On Bohr-Sommerfeld bases, math.AG/9909084]) is generaliz

Brian Harbourne

Modifying an approach of J. Roe, this paper gives an improved lower bound on the degrees d such that for general points p1,...,pn in P2 and m > 0 there is a plane curve of degree d vanishing at each point pi with multiplicity at least m. In certain cases, for m not too large compared with n, the new bound implies a bound conjectured by Nagata.

E. P. Volokitin, V. V. Ivanov

We study a connection between the isochronicity of a center of a polynomial vector field and the existence of a polynomial commuting system. We demonstrate an isochronous system of degree 4 which does not commute with any polynomial system. We prove that among the Newton polynomial systems only the Lienard and Abel systems may commute with transversal polyno

Anders S. Buch

In our joint paper with W. Fulton (math.AG/9804041) we prove a formula for the cohomology class of a quiver variety. This formula is general enough to give new expressions for all known types of Schubert polynomials. In the present paper we discuss the relationship between this formula and Stanley symmetric functions. We show that the coefficients obtained w