April 2001 arXiv papers — page 12

A. N. Morozov, A. V. Zvelindovsky, J. G. E. M. Fraaije

In this work we incorporate some real-system effects into the theory of orientational phase transitions under shear flow (M. E. Cates and S. T. Milner, Phys. Rev. Lett. v.62, p.1856 (1989) and G. H. Fredrickson, J. Rheol. v.38, p.1045 (1994)). In particular, we study the influence of the shear-cell boundaries on the orientation of the lamellar phase. We pred

G. Caldarelli, Andrea Capocci, Paolo Laureti

In the Stable Marriage Problem two sets of agents must be paired according to mutual preferences, which may happen to conflict. We present two generalizations of its sex-oriented version, aiming to take into account correlations between the preferences of agents and costly information. Their effects are investigated both numerically and analytically.

Andrea Capocci, Yi-Cheng Zhang

We study the role of active and passive investors in an investment market with uncertainties. Active investors concentrate on a single or a few stocks with a given probability of determining the quality of them. Passive investors spread their investment uniformly, resembling buying the market index. In this toy market stocks are introduced as good and bad. I

V. Meden, W. Metzner, U. Schollwoeck, K. Schoenhammer

Using a functional renormalization group we compute the flow of the renormalized impurity potential for a single impurity in a Luttinger liquid over the entire energy range - from the microscopic scale of a lattice-fermion model down to the low-energy limit. The non-perturbative method provides a complete real-space picture of the effective impurity potentia

L. Bellaiche, A. Garcia, David Vanderbilt

Properties of Pb(Zr_{1-x}Ti_x)O_3 (PZT) for compositions x near the morphotropic phase boundary and under an electric field are simulated using an ab-initio based approach. Applying an electric field of [111] orientation to tetragonal PZT (e.g., x=0.50) leads to the expected sequence of tetragonal, A-type monoclinic, and rhombohedral structures. However, the

T. Jungwirth, A. H. MacDonald

We explain the recent observation of resistance spikes and hysteretic transport properties in Ising quantum Hall ferromagnets in terms of the unique physics of their domain walls. Self-consistent RPA/Hartree-Fock theory is applied to microscopically determine properties of the ground state and domain-wall excitations. In these systems domain wall loops suppo

R. Mathieu, P. E. Jönsson, P. Nordblad, H. Aruga Katori

The non-equilibrium dynamics of the model 3d-Ising spin glass - Fe$_{0.55}$Mn$_{0.45}$TiO$_3$ - has been investigated from the temperature and time dependence of the zero field cooled magnetization recorded under certain thermal protocols. The results manifest chaos, rejuvenation and memory features of the equilibrating spin configuration that are very simil

Philip W. Anderson

We propose that early speculations on the nature of the normal state of the $CuO_2$ planes in high $T_c$ superconductors can be revised and brought into agreement with more modern theories, simulations and experimental observations.

Andreas Mielke

We discuss physical and mathematical aspects of the over-damped motion of a Brownian particle in fluctuating potentials. It is shown that such a system can be described quantitatively by fluctuating rates if the potential fluctuations are slow compared to relaxation within the minima of the potential, and if the position of the minima does not fluctuate. Eff

B. Hinnemann, F. Westerhoff, D. E. Wolf

Pulsed laser deposition (PLD) is a popular growth method, which has been successfully used for fabricating thin films. Compared to continuous deposition (like molecular beam epitaxy) the pulse intensity can be used as an additional parameter for tuning the growth behavior, so that under certain circumstances PLD improves layer-by-layer growth. We present kin

D. Matthey, S. Gariglio, B. Giovannini, J. -M. Triscone

We report on measurements of the resistivity and Hall coefficient in underdoped GdBa2Cu3O7-d epitaxial thin films grown by off-axis magnetron sputtering. The films have been lithographically patterned allowing precise measurements of the temperature dependencies of the inverse Hall constant RH-1 and of the Hall angle theta_H. We find that RH-1 is linear in t

Adan Garriga, Jorge Kurchan, Felix Ritort

We consider a one-dimensional gas of two kinds of particles with different masses interacting through short range interactions. The system exhibits an extreme form of the Soret effect: when the ends of the system are in contact with thermal baths of different temperatures, there is complete separation of the species. We show how this separation can be well d

R. Ocaña, P. Esquinazi

We have measured the transverse thermal conductivity $κ_{xy}$ of twinned and untwinned YBa$_2$Cu$_3$O$_7$ single crystals as a function of angle $θ$ between the magnetic field applied parallel to the CuO$_2$ planes and the heat current direction, at different magnetic fields and temperatures. For both crystals we observed a clear twofold variation in the fie

A. I. Olemskoi, A. V. Khomenko, D. O. Kharchenko

The theory of a flux steady-state related to avalanche formation is presented for the simplest model of a sand pile within framework of the Lorenz approach. The stationary values of sand velocity and sand pile slope are derived as functions of control parameter (driven sand pile slope). The additive noises of above values are introduced to build the phase di

M. Rusanen, I. T. Koponen, J. Heinonen, T. Ala-Nissila

We study the onset and development of ledge instabilities during growth of vicinal metal surfaces using kinetic Monte Carlo simulations. We observe the formation of periodic patterns at [110] close packed step edges on surfaces vicinal to fcc(001) under realistic molecular beam epitaxy conditions. The corresponding wavelength and its temperature dependence a

Vitaly A. Gasparov, N. S. Sidorov, I. I. Zver'kova, M. P. Kulakov

We report on syntheses and electron transport properties of polycrystalline samples of diborides (AB2) with different transition metals atoms (A=Zr,Nb,Ta). The temperature dependence of resistivity, ρ(T), and ac susceptibility of these samples reveal superconducting transition of ZrB2 with Tc=5.5 K, while NbB2 and TaB2 have been observed nonsuperconducting u

Jurgen Horbach, Walter Kob

We use molecular dynamics computer simulations to study the relaxation dynamics of a viscous melt of silica. The coherent and incoherent intermediate scattering functions, F_d(q,t) and F_s(q,t), show a crossover from a nearly exponential decay at high temperatures to a two-step relaxation at low temperatures. Close to the critical temperature of mode-couplin

Fei Ye, Guo-Hui Ding, Bo-Wei Xu

In the present paper we utilize the renormalization group(RG) technique to analyse the Ising critical behavior in the double frequency sine-Gordon model. The one-loop RG equations obtained show unambiguously that there exist two Ising critical points besides the trivial Gaussian fixed point. The topology of the RG flows is obtained as well.

J. Q. Li, L. Li, F. M. Liu, C. Dong

Superconductivity and structural properties of Mg1-xAlxB2 materials have been systematically investigated. Evident modifications in both superconductivity and microstructure are identified to originate from the Al ordering along the c-axis direction. The resultant superstructure phase has an optimal composition of MgAlB4 with the superconducting transition a

A. V. Germanenko, G. M. Minkov, O. E. Rut

A weak-localization effect has been studied in macroscopically inhomogeneous 2D system. It is shown, that although the real phase breaking length tends to infinity when the temperature tends to zero, such a system can reveal a saturated behavior of the temperature dependence of that parameter, which is obtained from the standard analysis of the negative magn

Aki-Hiro Sato, Hideki Takayasu

We constructed an analog electrical circuit which generates fluctuations in which probability density function has power law tails. In the circuit fluctuations with an arbitrary exponent of the power law can be obtained by adjusting the resistance. With this low cost circuit the random fluctuations which have the similar statistics to foreign exchang rates c

Kirill Katsov, John D. Weeks

We study thermodynamic and structural properties of a Lennard-Jones liquid at a state very close to the triple point as the radius of a hard sphere solute is varied. Oscillatory profiles arise for small, molecular sized radii while for large radii smooth interfaces with a ``drying layer'' of low vapor density near the solute are seen. We develop a qu

Julia E. Medvedeva, Vladimir I. Anisimov, Michael A. Korotin, Oleg N. Mryasov

A detailed study of the electronic structure and magnetic configurations of the 50 % hole-doped double layered manganite LaSr$_2$Mn$_2$O$_7$ is presented. We demonstrate that the on-site Coulomb correlation (U) of Mn d electrons {\it (i)} significantly modifies the electronic structure, magnetic ordering (from FM to AFM), and interlayer exchange interactions

S. O. Valenzuela, V. Bekeris

We report on the degree of order of the vortex solid in YBa2Cu3O7 single crystals observed in ac susceptibility measurements. We show that when vortices are "shaken" by a temporarily symmetric ac field they are driven into an easy-to-move, ordered structure but, on the contrary, when the ac field is temporarily asymmetric, they are driven into a more

Inanc Adagideli, Paul M. Goldbart

Andreev billiards are finite, arbitrarily-shaped, normal-state regions, surrounded by superconductor. At energies below the superconducting energy gap, single-quasiparticle excitations are confined to the normal region and its vicinity, the mechanism for confinement being Andreev reflection. Short-wave quantal properties of these excitations, such as the con

N. A. Levenson, R. Cid Fernandes,, K. A. Weaver, T. M. Heckman

We present NGC 6221 as a case study of ``X-ray loud composite galaxies,'' which appear similar to starbursts at optical wavelengths and resemble traditional active galactic nuclei in X-rays. The net optical spectrum of NGC 6221 is properly characterized as a starburst galaxy, but in X-rays, NGC 6221 is similar to Seyfert 1 galaxies, exhibiting a powe

Joanne M. Attridge

86 GHz Very Long Baseline Polarimetry probes magnetic field structures within the cores of Active Galactic Nuclei at higher angular resolutions and a spectral octave higher than previously achievable. Observations of 3C273 and 3C279 taken in April 2000 with the Coordinated Millimeter VLBI Array have resulted in the first total intensity (Stokes I) and linear

I. Trujillo, J. A. L. Aguerri, C. M. Gutierrez, J. Cepa

We present broad-band photometry and provide a quantitative analysis of the structure of galaxies in the inner region of the Abell Cluster 2443 (z~0.1). The galaxy parameters have been derived by fitting a two-component model (Sersic r^{1/n} bulge and exponential disk) to a magnitude-limited sample. Using a new method of analysis which takes into account the

J. M. Barr, M. N. Bremer, J. C. Baker

We have obtained multi-colour imaging of a representative, statistically complete sample of low-frequency selected (S_408MHz > 0.95Jy) radio loud quasars at intermediate (0.6 < z < 1.1) redshifts. These sources are found in a variety of environments, from the field through to rich clusters. We show that statistical measures of environmental richness, based u

J. M. Wrobel, C. D. Fassnacht, L. C. Ho

The NRAO VLBA was used at 1.4 GHz to image the inner 550 mas (23 lt-years) of the nearest known Seyfert 1 nucleus, in the Sm galaxy NGC 4395. One continuum source was detected, with flux density $530\pm130 μ$Jy, diameter d<11 mas (0.46 lt-year), and brightness temperature $T_{\rm b} > 2.0\times10^6$ K. The spectral power $P$ of the VLBA source is intermediat

P. B. Tissera, D. G. Lambas M. B. Mosconi, S. A. Cora

We use cosmological hydrodynamical simulations including star formation and metal enrichment to study the evolution of the chemical properties of galaxy-like objects at high redshift in the range $0.25<z< 2.35$ in a hierarchical clustering scenario. As the galactic objects are assembled we find that their gaseous components exhibit neutral Hydrogen column de

M. Lopez-Corredoira, P. L. Hammersley, F. Garzon, A. Cabrera-Lavers

New evidence for a long thin Galactic bar (in contradistinction to the bulge), as well as for the existence of the ring and the truncation of the inner disc, are sought in the DENIS survey. First, we examine DENIS and Two Micron Galactic Survey star counts for the characteristic signatures of an in-plane bar and ring. The star counts in the plane for 30 deg.

A. N. Lasenby, R. B. Barreiro, M. P. Hobson

An overview is given of Bayesian inversion and regularization procedures. In particular, the conceptual basis of the maximum entropy method (MEM) is discussed, and extensions to positive/negative and complex data are highlighted. Other deconvolution methods are also discussed within the Bayesian context, focusing mainly on the comparison of Wiener filtering,

I. L. Tregillis, T. W. Jones, Dongsu Ryu

We present the first three-dimensional MHD radio galaxy simulations that explicitly model transport of relativistic electrons, including diffusive acceleration at shocks as well as radiative and adiabatic cooling in smooth flows. We discuss three simulations of light Mach 8 jets, designed to explore the effects of shock acceleration and radiative aging on th

Christian Theis, Sven Kohle

(abridged) We combined several N-body methods in order to investigate the interaction scenario between NGC 4449 and DDO 125, a close companion in projected space. In a first step fast restricted N-body models are used to confine a region in parameter space reproducing the main observational features. In a second step a genetic algorithm is applied for a uniq

S. B. Kraemer, D. M. Crenshaw, J. R. Gabel

We present observations of the UV absorption lines in the Seyfert 1 galaxy NGC 3783, obtained with the medium resolution echelle gratings of the Space Telescope Imaging Spectrograph(STIS) on the Hubble Space Telescope (HST). The spectra reveal the presence of three kinematic components of absorption in Ly-alpha, C IV, and N V, at radial velocities of -1365,

G. Rüdiger, Y. Zhang

The possibility that the magnetic shear-flow instability (MRI, Balbus-Hawley instability) might give rise to turbulence in a cylindric Couette flow is investigated through numerical simulations. The study is linear and the fluid flow is supposed to be incompressible and differentially rotating with a simple velocity profile with $Ω= a+b/R^2$. The simplicity

Sara L. Ellison, Sean G. Ryan, Jason X. Prochaska

We present the first ever detection of Cobalt in a Damped Lyman Alpha system (DLA) at z = 1.92. In addition to providing important clues to the star formation history of these high redshift galaxies, we discuss how studying the Co abundance in DLAs may also help to constrain models of stellar nucleosynthesis in a regime not probed by Galactic stars.

R. B. Barreiro, M. P. Hobson

We investigate the power of wavelet techniques in detecting non-Gaussianity in the cosmic microwave background (CMB). We use the method to discriminate between an inflationary and a cosmic strings model using small simulated patches of the sky. We show the importance of the choice of a good test statistic in order to optimise the discriminating power of the

Jean in &#39;t Zand

In the last 15 years, 6 dedicated observation programs were carried out to monitor ~20 deg around the galactic center for transient activity above a few keV. Transient activity from low-mass X-ray binaries shows a strong preference for this field. Two programs are currently active, with the Wide Field Cameras on BeppoSAX and the Proportional Counter Array on

Giovanni Vladilo, Miriam Centurion, Piercarlo Bonifacio, J. Christopher Howk

We analyze extant data of Al++, Al+ and other low ions with the aim of studying the ionization properties of Damped Ly alpha systems (DLAs) from the analysis of the ratio R(Al++/Al+) = N(Al++)/N(Al+). We find good correlations logN(Al+)-logN(Si+) and logN(Al+)-logN(Fe+) that we use to indirectly estimate N(Al+) from N(Si+) and/or N(Fe+) measurements. In this

J. Cui, X. -Y. Xia, Z. -G. Deng, S. Mao

We perform photometric measurements on a large HST snapshot imaging survey sample of 97 ultraluminous infrared galaxies (ULIRGs). We select putative nuclei from bright clumps in all the sample targets, mainly based on a quantitative criterion of I-band luminosity as well as the global and local morphological information. All the sources are then classified i

R. De Santis

In this paper, by assuming as correct equilibrium temperatures of RRab Lyrae variables those defined from Carney, Storm & Jones (1992, CSJ), we show that temperatures derived from (B-V) colour (mean colour over the pulsational cycle calculated on the magnitude scale) by Bessel, Castelli & Plez 1998 (BCP) transformations, are consistent with CSJ equilibrium t

James E. Rhoads, Sangeeta Malhotra, Arjun Dey, Buell T. Jannuzi

The Lyman-$α$ line is expected to be strong in the presence of active star formation and the absence of dust, making it a good tool for finding chemically primitive galaxies in the early universe. We report on a new survey for high redshift Lyman-$α$ sources, the Large Area Lyman Alpha (LALA) survey. Our survey achieves an unprecedented combination of volume

Jiliang Jing, Mu-Lin Yan

The quantum entropy of the Kerr black hole arising from gravitational perturbation is investigated by using Null tetrad and t Hooftś brick-wall model. It is shown that effect of the gravitonś spins on the subleading correction is dependent of the square of the spins and the angular momentum per unit mass of the black hole, and contribution of the logarithmic

Prasenjit Sen, S. Ciraci, A. Buldum, Inder P. Batra

First-principles density functional calculations reveal that aluminum can form planar chains in zigzag and ladder structures. The most stable one has equilateral triangular geometry with four nearest neighbors; the other stable zigzag structure has wide bond angle and allows for two nearest neighbors. An intermediary structure has the ladder geometry and is

Shufang Su, Mark B. Wise

We studied the leading supersymmetric contribution to top-antitop threshold production using the NRQCD framework. The one-loop matching to the potential and the Wilson coefficient of the leading production current were considered. We point out that the leading correction to the potential is zero due to SU(3)_c gauge invariance. This is true in general for an

Hong Liu, Jeremy Michelson

We propose the leading couplings, in an alpha&#39; expansion, of noncommutative D-branes to RR potentials in a constant NSNS B-field for an arbitrary choice of noncommutative parameter. The proposal is motivated by some string amplitude computations. The zero momentum couplings are topological in nature and involve Elliott&#39;s noncommutative Chern characte

V. Barger, D. Marfatia, K. Whisnant

We perform an oscillation parameter-independent analysis of solar neutrino flux measurements from which we predict the charged-current rate at SNO relative to Standard Solar Model to be $R_{SNO}^{CC}=0.35^{+0.16}_{-0.09} (0.46^{+0.13}_{-0.11})$ for oscillations to active (sterile) neutrinos. By alternately considering the $^8$B flux normalization fixed and f

Paul S. Aspinwall, Albion Lawrence

We define a particular class of topological field theories associated to open strings and prove the resulting D-branes and open strings form the bounded derived category of coherent sheaves. This derivation is a variant of some ideas proposed recently by Douglas. We then argue that any 0-brane on any Calabi-Yau threefold must become unstable along some path

S. Yi, P. Demarque, Y. -C. Kim, Y. -W. Lee

We have constructed a new set of isochrones, called the Y^2 Isochrones, that represent an update of the Revised Yale Isochrones (RYI), using improved opacities and equations of state. Helium diffusion and convective core overshoot have also been taken into consideration. This first set of isochrones is for the scaled solar mixture. A subsequent paper will co

A. Fotopoulos

In hep-th/9903210 (curvature)$^2$ terms of the effective D-brane action were derived to lowest order in the string coupling. Their results are correct up to ambiguous terms which involve the second fundamental form of the D-brane. We compute five point string amplitudes on the disk. We compare the subleading order in $\alpha'$ of the string amplitudes with t

Weiqiang Wang

For a space X acted by a finite group $\G$, the product space $X^n$ affords a natural action of the wreath product $\Gn$. In this paper we study the K-groups $K_{\tG_n}(X^n)$ of $\Gn$-equivariant Clifford supermodules on $X^n$. We show that $\tFG =\bigoplus_{n\ge 0}K_{\tG_n}(X^n) \otimes \C$ is a Hopf algebra and it is isomorphic to the Fock space of a twist

Karsten Reuter, Matthias Scheffler

We present density-functional theory calculations of Ru 3d and O 1s surface core-level shifts (SCLSs) at an oxygen-rich Ru(0001) surface, namely for the O(1x1)/Ru(0001) chemisorption phase and for two surface terminations of fully oxidized RuO_2(110). Including final-state effects, the computed SCLSs can be employed for the analysis of experimental X-ray pho

M. Ali Alpar, Askin Ankay, Efe Yazgan

Neutron stars may be surrounded by fall-back disks formed from supernova core-collapse. If the disk circumscribes the light-cylinder, the neutron star will be an active radio pulsar spinning down under the propeller spin-down torque applied by the disk as well as the usual magnetic dipole radiation torque. Evolution across the P-P_dot diagram is very rapid w

Arno Riffeser, Juergen Fliri, Claus A. Goessl, Ralf Bender

We present WeCAPP, a long term monitoring project searching for microlensing events towards M 31. Since 1997 the bulge of M 31 was monitored in two different wavebands with the Wendelstein 0.8 m telescope. In 1999 we extended our observations to the Calar Alto 1.23 m telescope. Observing simultaneously at these two sites we obtained a time coverage of 53 % d

P. Saracco, E. Giallongo, S. Cristiani, S. D&#39;Odorico

We present near-IR (J and Ks) number counts and colors of galaxies detected in deep VLT-ISAAC images centered on the Chandra Deep Field and Hubble Deep Field-South for a total area of 13.6 arcmin$^2$. The limiting surface brightness obtained is Ks$\simeq$22.8 mag/arcsec$^2$ and J$\simeq$24.5 (1$σ$) on both fields. A d$log$N/dm relation with a slope of $\sim0

G. M. Minkov, O. E. Rut, A. V. Germanenko, A. A. Sherstobitov

The quantum correction to the conductivity have been studied in two types of 2D heterostructures: with doped quantum well and doped barriers. The consistent analysis shows that in the structures where electrons occupy the states in quantum well only, all the temperature and magnetic field dependencies of the components of resistivity tensor are well describe

Hiroshige Kajiura, Yutaka Matsuo, Tadashi Takayanagi

We construct the exact noncommutative solutions on tori. This gives an exact description of tachyon condensation on bosonic D-branes, non-BPS D-branes and brane-antibrane systems. We obtain various bound states of D-branes after the tachyon condensation. Our results show that these solutions can be generated by applying the gauge Morita equivalence between t

Carlo Acerbi, Dirk Tasche

Expected Shortfall (ES) in several variants has been proposed as remedy for the defi-ciencies of Value-at-Risk (VaR) which in general is not a coherent risk measure. In fact, most definitions of ES lead to the same results when applied to continuous loss distributions. Differences may appear when the underlying loss distributions have discontinuities. In thi

M. Juvela, P. Padoan, A Nordlund

We have computed line emission cooling rates for the main cooling species in models of interstellar molecular clouds. The models are based on numerical simulations of super-sonic magneto-hydrodynamic (MHD) turbulence. Non-LTE radiative transfer calculations have been performed to properly account for the complex density and velocity structures in the MHD sim

Roy Maartens, Bahram Mashhoon, David Matravers

We analyze parallel transport of a vector field around an equatorial orbit in Kerr and stationary axisymmetric spacetimes that are reflection symmetric about their equatorial planes. As in Schwarzschild spacetime, there is a band structure of holonomy invariance. The new feature introduced by rotation is a shift in the timelike component of the vector, which

Y. Tanaka, H. Tanaka, T. Ono, A. Oosawa

The ground state of the stacked triangular antiferromagnet CsFeBr$_3$ is a spin singlet due to the large single ion anisotropy $D(S^z)^2$. The field-induced magnetic ordering in this compound was investigated by the magnetic susceptibility, the magnetization process and specific heat measurements for an external field parallel to the $c$-axis. Unexpectedly,

Wen-Tai Chiang, F. Tabakin, T. -S. H. Lee, B. Saghai

A coupled-channel (CC) approach has been developed to investigate kaon photoproduction on the nucleon. In addition to direct K+ Lambda production, our CC approach accounts for strangeness production including K+ Lambda final state interactions with both pi0 p and pi+ n intermediate states. Calculations for the gamma p --> K+ Lambda reaction have been perform

L. Frankfurt, V. Guzey, M. McDermott, M. Strikman

We derive the major characteristics of inclusive and diffractive final states in deep-inelastic scattering off heavy nuclei for the-high energy (small-x) kinematics in which the limit of complete absorption is reached for the dominant hadronic fluctuations in the virtual photon (the black-body limit of the process). Both the longitudinal and transverse distr

Dong-Uk Hwang, Inbo Kim, Sunghwan Rim, Chil-Min Kim

The mechanism of synchronization in the random Zaslavsky map is investigated. From the error dynamics of two particles, the structure of phase space was analyzed, and a transcritical bifurcation between a saddle and a stable fixed point was found. We have verified the structure of on-off intermittency in terms of a biased random walk. Furthermore, for the ge

Joop Schaye

Straightforward physical arguments are used to derive the properties of Lyman-alpha forest absorbers. It is shown that many aspects of the current physical picture of the forest, in particular the fact that the absorption arises in extended structures of moderate overdensities which contain a large fraction of the baryons in the universe, can be derived dire

P. Seneor, C. -T. Chen, N. -C. Yeh, R. P. Vasquez

Scanning tunneling spectroscopy of superconducting MgB$_2$ ($T_c = 39$ K) were studied on high-density pellets and c-axis oriented films. The sample surfaces were chemically etched to remove surface carbonates and hydroxides, and the data were compared with calculated spectra for all symmetry-allowed pairing channels. The pairing potential ($Δ_k$) is best de

Akira Shimizu, Takayuki Miyadera

We study quantum systems of volume V, which will exhibit the breaking of a U(1) symmetry in the limit of V \to \infty, when V is large but finite. We estimate the energy difference between the `symmetric ground state&#39; (SGS), which is the lowest-energy state that does not breaks the symmetry, and a `pure phase vacuum&#39; (PPV), which approaches a symmetr

V. Bromm, A. Ferrara, P. S. Coppi, R. B. Larson

Recent theoretical investigations have suggested that the formation of the very first stars, forming out of metal-free gas, was fundamentally different from the present-day case. In this paper, we study the effect of metallicity on the evolution of the gas in a collapsing dark matter mini-halo. We model such a system as an isolated 3σpeak of mass 2x10^6 M_su

Gavriel Segre

We introduce and analyze a quantum analogue of the Law of Excluded Gambling Strategies of Classical Decision Theory by the definition of different kind of quantum casinos. The necessity of keeping into account entaglement (by the way we give a staightforward generalization of Schmidt&#39;s entanglement measure) forces us to adopt the general algebraic langua

S. Bruce

We study the basic requirements for neutron confinement in the framework of some 3-D Aharonov-Casher configurations.

T. Yonte, J. J. Monzon, L. L. Sanchez-Soto, J. F. Carinena

We reelaborate on the basic properties of lossless multilayers. We show that the transfer matrices for these multilayers have essentially the same algebraic properties as the Lorentz group SO(2,1) in a (2+1)-dimensional spacetime, as well as the group SL(2,R) underlying the structure of the ABCD law in geometrical optics. By resorting to the Iwasawa decompos

S. Wycech, A. M. Green

The eta-deuteron scattering amplitude is calculated with a recent K-matrix model of eta-N interactions. The existence of a narrow virtual state in the eta-deuteron system is inferred. This state couples strongly to the eta-d channel but its effect on final state interactions in the pn --> eta-d reaction is shown to be rather weak. Fairly large eta-N scatteri

V. A. Delev, A. P. Krekhov

We report experimental and theoretical results on the conductive regime of electroconvection in hybrid aligned nematics. The drifting oblique/normal rolls below/above the Lifshitz frequency are observed at the onset of electroconvection under a.c. voltage. The experimental data on the threshold voltage, wavelength, oblique angle and drift period of the rolls

Darryl D. Holm, Peter Lynch

The swinging spring, or elastic pendulum, has a 2:1:1 resonance arising at cubic order in its approximate Lagrangian. The corresponding modulation equations are the well-known three-wave equations that also apply, for example, in laser-matter interaction in a cavity. We use Hamiltonian reduction and pattern evocation techniques to derive a formula that descr

W. K. Schief

A novel class of discrete integrable surfaces is recorded. This class of discrete O surfaces is shown to include discrete analogues of classical surfaces such as isothermic, `linear&#39; Weingarten, Guichard and Petot surfaces. Moreover, natural discrete analogues of the Gaussian and mean curvatures for surfaces parametrized in terms of curvature coordinates

W. K. Schief, B. G. Konopelchenko

A novel class of integrable surfaces is recorded. This class of O surfaces is shown to include and generalize classical surfaces such as isothermic, constant mean curvature, minimal, `linear&#39; Weingarten, Guichard and Petot surfaces and surfaces of constant Gaussian curvature. It is demonstrated that the construction of a Backlund transformation for O sur

E. Balkovsky, A. Fouxon, V. Lebedev

We investigate high-Reynolds number turbulence in dilute polymer solutions. We show the existence of a critical value of the Reynolds number which separates two different regimes. In the first regime, below the transition, the influence of the polymer molecules on the flow is negligible and they can be regarded as passively embedded in the flow. This case ad

Ed Bueler

The Dirac operator d+delta on the Hodge complex of a Riemannian manifold is regarded as an annihilation operator A. On a weighted space L_mu^2 Omega, [A,A*] acts as multiplication by a positive constant on excited states if and only if the logarithm of the measure density of mu satisfies a pair of equations. The equations are equivalent to the existence of a

L. A. Ibort, M. de Leon, G. Marmo, D. Martin de Diego

Non-holonomic constraints, both in the Lagragian and Hamiltonian formalism, are discussed from the geometrical viewpoint of implicit differential equations. A precise statement of both problems is presented remarking the similarities and differences with other classical problems with constraints. In our discussion, apart from a constraint submanifold, a fiel

Choon Bae Jeon, Gyo Taek Jin

Although there are infinitely many knots with superbridge index n for every even integer n>2, there are only finitely many knots with superbridge index 3.

Sean Sather-Wagstaff

Let (R,m) be a local ring with prime ideals p and q such that p+q is an m-primary ideal. If R is regular and contains a field, and dim(R/p)+dim(R/q)=dim(R), we prove that p^{(r)}\cap q^{(n)}\subseteq m^{m+n} for all positive integers r and s. This is proved using a generalization of Serre&#39;s Intersection Theorem which we apply to a hypersurface R/fR. The

Jonathan Wahl

Theorem: If W is a smooth complex projective variety with h^1 (O-script_W) = 0, then a sufficiently ample smooth divisor X on W cannot be a hyperplane section of a Calabi-Yau variety, unless W is itself a Calabi-Yau. Corollary: A smooth hypersurface of degree d in P^n (n >= 2) is a hyperplane section of a Calabi-Yau variety iff n+2 <= d <= 2n+2. The method i

A. V. Ershov

The aim of this paper is to prove the following result. For any commutative formal group ${\frak F}(x\otimes 1,1\otimes x),$ which is considered as a formal group over $H_\mathbb{Q},$ there exists a homomorphism to a formal group of the form ${\frak c}+x\otimes 1+1\otimes x,$ where $\frak c\in H_\mathbb{Q}{\mathop{\hat{\otimes}} \limits_{R_\mathbb{Q}}}H_\mat

Anders Kock, Gonzalo E. Reyes

Some differential equations are considered in the context of Synthetic Differential Geometry. Here, this means that not only nilpotent infinitesimals, but also the formation of function spaces, is exploited. In particular, we utilize distribution spaces in our study of wave and heat equations.

Roland Speicher

I give a survey about my work on combinatorial and probabilistic aspects of free probability theory. In particular, I present the combinatorial description of freeness in terms of free cumulants and I give some ideas of the main results of my joint work with Philippe Biane on a stochastic integration theory for free Brownian motion.

Olle Haggstrom, Johan Jonasson, Russell Lyons

The random-cluster model is a dependent percolation model that has applications in the study of Ising and Potts models. In this paper, several new results are obtained for the random-cluster model on nonamenable graphs with cluster parameter $q\geq 1$. Among these, the main ones are the absence of percolation for the free random-cluster measure at the critic

Carlos Naón, Mariano Salvay

A quantitative prediction of Conformal Field Theory (CFT), which relates the second moment of the energy-density correlator away from criticality to the value of the central charge, is verified in the sine-Gordon model. By exploiting the boson-fermion duality of two-dimensional field theories, this result also allows to show the validity of the prediction in

Leonidas Sandoval

We effectively sew two vertices with ghosts in order to obtain a third, composite vertex in the most general case of cycling transformations. In order to do this, we separate the vertices into two parts: a bosonic oscillator part and a ghost oscillator part and write them as canonical forms.

G. von Gehlen, Shi-shyr Roan

Finite-dimensional representations of Onsager&#39;s algebra are characterized by the zeros of truncation polynomials. The Z_N-chiral Potts quantum chain hamiltonians (of which the Ising chain hamiltonian is the N=2 case) are the main known interesting representations of Onsager&#39;s algebra and the corresponding polynomials have been found by Baxter and Alb

Balram Rai

We consider the enhancement of SL(2,R) to Virasoro algebra in a system of N particles on AdS2. We restrict our discussion to the case of non-interacting particles, and argue that they must be treated as fermions. We find operators L_n whose commutators on the ground state, |vac>, satisfy relations that are reminisent of c=1 Virasoro algebra, provided N \geq

D. Klemm, A. C. Petkou, G. Siopsis, D. Zanon

We argue that the thermodynamics of conformal field theories with AdS duals exhibits a remarkable universality. At strong coupling, a Cardy-Verlinde entropy formula holds even when R-charges or bulk supergravity scalars are turned on. In such a setting, the Casimir entropy can be identified with a generalized C-function that changes monotonically with temper

H. Y. Guo, Y. Q. Li, K. Wu, S. K. Wang

We study the Euler-Lagrange cohomology and explore the symplectic or multisymplectic geometry and their preserving properties in classical mechanism and classical field theory in Lagrangian and Hamiltonian formalism in each case respectively. By virtue of the Euler-Lagrange cohomology that is nontrivial in the configuration space, we show that the symplectic

V. A. Kazakov, A. A. Tseytlin

Trying to interpret recent matrix model results (hep-th/0101011) we discuss computation of classical free energy of exact dilatonic 2-d black hole from the effective action of string theory. The euclidean space-time action evaluated on the black hole background is divergent due to linear dilaton vacuum contribution, and its finite part depends on a subtracti

Alex Krasnitz, Raju Venugopalan

At very high energies, the high parton densities (characterized by a semi-hard saturation scale Λ_s) ensure that parton distributions can be described by a classical effective field theory with remarkable properties analogous to those of spin glass systems. This color glass condensate (CGC) of gluons also provides the initial conditions for multi-particle pr

D. Bourilkov

For the first time the experiments ALEPH, DELPHI, L3 and OPAL have presented preliminary results for fermion-pair production in e+e- collisions on the full data set above the Z pole. A combined analysis of the Bhabha scattering measurements is performed to search for effects of contact interactions. In the case of two axial-vector (AA) currents the best fit

Alessandro Vicini

A simple algorithm is presented to decompose any 1-loop amplitude for scattering processes of the class 2 fermions -> 4 fermions into a fixed number of gauge-invariant form factors. The structure of the amplitude is simpler than in the conventional approaches and its numerical evaluation is made faster. The algorithm can be efficiently applied also to amplit

M. Musakhanov

We discuss the current mass dependence of the basic quantities of the quark models -- constituent quark mass M and quark condensate i<psi^dagger psi >. The framework of the consideration is QCD instanton vacuum model.

A. Banfi, Yu. L. Dokshitzer, G. Marchesini, G. Zanderighi

We present the QCD analysis of D-parameter distribution in near-to-planar 3-jet e+e- annihilation events. We derive the all-order resummed perturbative prediction and the leading power suppressed non-perturbative corrections both to the mean value and the distribution. Here non-perturbative corrections are larger than in 2-jet shape observables, so that high