June 2000 arXiv papers — page 6

A. I. Onishchenko

In this paper we give a short review of the recently obtained results on inclusive and exclusive decays of doubly heavy baryons.

A. Bialas, M. Kucharczyk, H. Palka, K. Zalewski

Mass dependence of the effective source radii, observed in hadronic $Z^0$ decays by several LEP I experiments, is analyzed in a model which assumes proportionality between four-momentum of a produced particle and the four-vector describing its space-time position at the freeze-out. It is shown that this relation (commonly accepted in description of high-ener

A. A. Khelashvili

Exploiting the explicit mass formulae for logarithmic potential model of Quigg and Rosner it is shown that at least on the level of mass-relations this model reproduces the naive quark model relations and generalizes the last one in case of highly non-trivial potential. Generalization includes the relations for higher values of orbital quantum numbers. In pa

F. Close

Glueball candidates and qqbar mesons have been found to be produced with different momentum and angular dependences in the central region of pp collisions. This talk illustrates this phenomenon and explains the phi and t dependences of mesons with JPC = 0++,0-+, 1++, 2++ and 2-+. For production of 0++ and 2++ mesons the analysis reveals a systematic behaviou

S. M. Troshin, N. E. Tyurin

We consider impact parameter dependence of the polarized and unpolarized structure functions. Unitarity does not allow factorization of the structure functions over the Bjorken x and the impact parameter b variables. On the basis of the particular geometrical model approach we conclude that spin of constituent quark may have a significant orbital angular mom

Shibaji Banerjee, Sanjay K. Ghosh, Sibaji Raha, Debapriyo Syam

The mechanism for the propagation of strangelets with low baryon number through the atmosphere of the Earth has been explored. It has been shown that under suitable initial conditions, such strangelets may indeed reach depths near mountain altitudes with mass numbers and charges close to the observed values in cosmic ray experiments.

M. Stratmann

It is demonstrated that measurements of the spin asymmetry for di-jet production at future polarized colliders appear to be particularly suited for a first determination of the so far unmeasured parton densities of circularly polarized photons.

She-Sheng Xue

The vectorlike doubling of low-energy excitations is in fact a natural consequence of the pair-production around the zero-energy (E=0) due to the quantum field fluctuations of the lattice regularized vacuum. On the 1+1 dimensional lattice, we study an anomaly-free chiral model (11112) of four left-movers and one right-mover with strong interactions. Exact co

NEMO Collaboration

The NEMO collaboration is presently mounting the NEMO-3 detector in the Fréjus Underground Laboratory. This detector, which will be completed by the end of the year 2000, is devoted to the search of neutrinoless double beta decay with various isotopes. Much attention has been focused on ^{100}Mo and ^{82}Se with their large Q_{ββ}-values. The detector is bas

Bela Szilagyi

From Einstein's theory we know that besides the electromagnetic spectrum, objects like quasars, active galactic nuclei, pulsars and black holes also generate a physical signal of purely gravitational nature. The actual form of the signal is impossible to determine analytically, which lead to use of numerical methods. Two major approaches emerged. The fir

Kevin Glynn, Martin Sulzmann, Peter J. Stuckey

Type classes are an elegant extension to traditional, Hindley-Milner based typing systems. They are used in modern, typed languages such as Haskell to support controlled overloading of symbols. Haskell 98 supports only single-parameter and constructor type classes. Other extensions such as multi-parameter type classes are highly desired but are still not off

D. B. Saakian

We investigate the extreme value statistics connected with the dilute Random Energy Model with integer couplings. New universality class is found.

M. Perez, J-C. Barbe, Z. Neda, Y. Brechet

The rheological behavior of metallic alloys containing both solid and liquid phases is investigated in the low solid fraction range (<50%). This behavior depends on both the solid fraction and the shear rate. The concept of Effective Volume Fraction (EVF) is used to decorrelate the influence of these two parameters. At high shear rate the slurry behaves like

A. E. Allahverdyan, Th. M. Nieuwenhuizen

The stationary state of a quantum particle strongly coupled to a quantum thermal bath is known to be non-gibbsian, due to entanglement with the bath. For harmonic potentials, where the system can be described by effective temperatures, thermodynamic relations are shown to take a generalized Gibbsian form, that may violate the Clausius inequality. For the wea

Stefan Kehrein

A continuous sequence of infinitesimal unitary transformations is used to diagonalize the quantum sine-Gordon model for β^2\in(2π,\infty). This approach can be understood as an extension of perturbative scaling theory since it links weak- to strong-coupling behavior in a systematic expansion: a small expansion parameter is identified and this parameter remai

R. Rinaldi, E. Branca, R. Cingolani, R. Di Felice

We report on a new class of hybrid electronic devices based on a DNA nucleoside (deoxyguanosine lipophilic derivative) whose assembled polymeric ribbons interconnect a submicron metallic gate. The device exhibits large conductivity at room temperature, rectifying behaviour and strong current-voltage hysteresis. The transport mechanism through the molecules i

G. I. Japaridze, A. P. Kampf, M. Sekania, P. Kakashvili

The ground state phase diagram of the 1D Hubbard chain with pair-hopping interaction is studied. The analysis of the model is performed using the continuum-limit field theory approach and exact diagonalization studies. At half-filling the phase diagram is shown to consist of two superconducting states with Cooper pair center-of-mass momentum Q=0 (BCS-η_0 pha

S. J. Mitchell, G. Brown, P. A. Rikvold

We examine hysteresis in cyclic voltammetry of Br electrosorption onto single-crystal Ag(100) by dynamic Monte Carlo simulations. At room temperature, this system displays a second-order phase transition from a low-coverage disordered phase to a doubly degenerate $c (2 \times 2)$ phase. The electrochemical potential is ramped back and forth across the phase

C. Grimaldi, E. Cappelluti, L. Pietronero, S. Straessler

We discuss the compatibility of the most accurate experimental data with the ordinary Migdal-Eliashberg theory of superconductivity in the fullerene compound Rb_3C_60. By using different model phonon spectra we conclude that the experimental data can be fitted only by invoking an electron-phonon coupling of order λ\simeq 3. This exceedingly high value is unp

D. Varsano, S. Moroni, G. Senatore

We present a numerical study of magnetic phases of the 2D electron gas near freezing. The calculations are performed by diffusion Monte Carlo in the fixed node approximation. At variance with the 3D case we find no evidence for the stability of a partially polarized phase. With plane wave nodes in the trial function, the polarization transition takes place a

J. Johansson, D. B. Haviland

We have numerically studied the behavior of one dimensional tunnel junction arrays when random background charges are included using the ``orthodox&#39;&#39; theory of single electron tunneling. Random background charge distributions are verified in both amplitude and density. The use of a uniform array as a transistor is discussed both with and without rand

A. V. Uskov, A. -P. Jauho, B. Tromborg, J. Mork

Interpretation of experiments on quantum dot (QD) lasers presents a challenge: the phonon bottleneck, which should strongly suppress relaxation and dephasing of the discrete energy states, often seems to be inoperative. We suggest and develop a theory for an intrinsic mechanism for dephasing in QD&#39;s: second-order elastic interaction between quantum dot c

M. Koshino, H. Aoki, K. Kuroki, S. Kagoshima

For a three-dimensional lattice in magnetic fields we have shown that the hopping along the third direction, which normally tends to smear out the Landau quantization gaps, can rather give rise to a fractal energy spectram akin to Hofstadter&#39;s butterfly when a criterion, found here by mapping the problem to two dimensions, is fulfilled by anisotropic (qu

Jess B. Sturgeon, Brian. B. Laird

Model interaction potentials for real materials are generally optimized with respect to only those experimental properties that are easily evaluated as mechanical averages (e.g., elastic constants (at T=0 K), static lattice energies and liquid structure). For such potentials, agreement with experiment for the non-mechanical properties, such as the melting po

H. Hünnefeld, T. Niemöller, J. R. Schneider, U. Rütt

The depth dependence of the crystallographic parameters mosaicity, lattice parameter variation and integrated reflectivity and of the critical scattering above the 105 K structural phase transition of SrTiO$_3$ have been studied in five different single crystals by means of high resolution triple-crystal diffractometry using 100-120 keV synchrotron radiation

Maddalena Spada, Davide Lazzati, Gabriele Ghisellini, Annalisa Celotti

The development of instabilities leading to the formation of internal shocks is expected in the relativistic outflows of both gamma-ray bursts and blazars. The shocks heat the expanding ejecta, generate a tangled magnetic field and accelerate leptons to relativistic energies. While this scenario has been largely considered for the origin of the spectrum and

M. A. Bautista, T. R. Kallman

We calculate the recombination spectra of the He-like ions He~I, C~V, N~VI, O~VII, Ne~IX, Mg~XI, Si~XIII, S~XV, Ar~XVII, Ca~XIX, and Fe~XXV. We include the following physical processes: radiative recombination, dielectronic recombination, three-body recombination, electron impact ionization, and collisional excitation by electrons, protons, and $α$-particles

M. R. de Oliveira, C. M. Dutra, E. Bica, H. Dottori

An isophotal atlas of 75 star cluster pairs and multiplets in the Small Magellanic Cloud is presented, comprising 176 objects. They are concentrated in the SMC main body. The isophotal contours were made from Digitized Sky Survey images and showed relevant structural features possibly related to interactions in about 25% of the sample. Previous N-body simula

Michael D. Gregg, Robert H. Becker, Michael S. Brotherton, Sally A. Laurent-Muehleisen

We have discovered a remarkable quasar, FIRST J101614.3+520916, whose optical spectrum shows unambiguous broad absorption features while its double-lobed radio morphology and luminosity clearly indicate a classic Fanaroff-Riley Type II radio source. Its radio luminosity places it at the extreme of the recently established class of radio-loud broad absorption

Paul R. Shapiro, Alejandro C. Raga

The first sources of ionizing radiation to condense out of the dark and neutral IGM sent ionization fronts sweeping outward through their surroundings, overtaking other condensed objects and photoevaporating them. This feedback of universal reionization on cosmic structure formation is demonstrated here by gas dynamical simulations, including radiative trans

G. M. Voit

Evolution of the cluster temperature function is extremely sensitive to the mean matter density of the universe. Current measurements based on cluster temperature surveys indicate that Omega_M ~ 0.3 with a 1-sigma statistical error ~0.1, but the systematic errors in this method are of comparable size. Many more high-z cluster temperatures will be arriving fr

R. Siebenmorgen, T. Prusti, A. Natta, Th. Mueller

We present mid IR spectro-photometric imaging of a sample of eight nearby ($D \leq 240$pc) Herbig Ae/Be stars. The spectra are dominated by photospheric emission (HR6000), featureless infrared excess emission (T~Cha), broad silicate emission feature (HR5999) and the infrared emission bands (HD 97048, HD 97300, TY~CrA, HD 176386). The spectrum of HD179218 sho

R. S. Somerville, J. R. Primack, S. M. Faber

Using semi-analytic models of galaxy formation set within the Cold Dark Matter (CDM) merging hierarchy, we investigate several scenarios for the nature of the high-redshift ($z \ga 2$) Lyman-break galaxies (LBGs). We consider a ``collisional starburst&#39;&#39; model in which bursts of star formation are triggered by galaxy-galaxy mergers, and find that a si

Gilles Chabrier, Pierre Brassard, Gilles Fontaine, Didier Saumon

We present new cooling sequences, color-magnitude diagrams, and color-color diagrams for cool white dwarfs with pure hydrogen atmospheres down to an effective temperature $\te=1500$ K. We include a more detailed treatment of the physics of the fully-ionized interior, particularly an improved discussion of the thermodynamics of the temperature-dependent ion-i

Noam Soker

I examine the implications of the recently found extrasolar planets on the planet-induced axisymmetrical mass loss model for the formation of elliptical planetary nebulae (PNs). This model, which was developed in several earlier papers by the author and a few collaborators, attributes low departure from spherical mass loss of upper asymptotic giant branch (A

D. Tsch&#34;oke, G. Hensler, N. Junkes

The late-type galaxy NGC 4303 (M61) is one of the most intensively studied barred galaxies in the Virgo Cluster. Its prominent enhanced star formation throughout large areas of the disk can be nicely studied due to its low inclination of about 27 \degr. We present observations of NGC 4303 with the ROSAT PSPC and HRI in the soft X-ray (0.1-2.4 keV). The bulk

F. -Xavier Desert

I review the present observational status of the SZ effect due to the Compton scattering of the 3K background on the hot electrons of clusters of galaxies. I raise the relevant issues from theoretical and X-ray aspects of the question that challenge the present experiments. Future instruments like powerful radio interferometers and bolometric cameras should

R. Luetticke, R. -J. Dettmar, M. Pohlen

We present a classification for bulges of a complete sample of ~1350 edge-on disk galaxies derived from the RC3 (Third Reference Catalogue of Bright Galaxies, de Vaucouleurs et al. 1991). A visual classification of the bulges using the Digitized Sky Survey (DSS) in three types of b/p bulges or as an elliptical type is presented and supported by CCD images. N

Bertil Dorch, Aake Nordlund

The interaction of magnetic fields and stratified convection was studied in the context of the solar and late type stellar dynamos by using numerical 3D MHD simulations. The topology of stratified asymmetric and over-turning convection enables a pumping mechanism that may render the magnetic flux storage problem obsolete. The inclusion of open boundary condi

Seoktae Koh, Chul H. Lee

Galactic magnetic fields are observed of order $\sim 10^{-6}G$, but their origin is not definitely known yet. In this paper we consider the primordial magnetic fields generated in the early universe and analyse their effects on the density perturbations and the CMBR anisotropy. We assume that the random magnetic fields have the power law spectrum and satisfy

R. Morganti, T. A. Oosterloo, G. van Moorsel, C. N. Tadhunter

Twenty-two powerful radio galaxies have been searched for HI absorption. We find the highest probability of detecting HI in absorption among narrow-line compact (or small) galaxies or galaxies with indication of richer interstellar medium (i.e. with ongoing or recent star-formation). We discuss the difficulty in the interpretation of the origin of the HI abs

D. J. Axon, A. Capetti, R. Fanti, R. Morganti

We present the results of HST narrow band imaging of eleven Compact Steep Spectrum (CSS) radio sources. Five of them (3C 48, 3C 147, 3C303.1, 3C 277.1 and 4C 12.50) were part of a dedicated ``pointed&#39;&#39; program of deep line imaging ([OIII]). For six additional sources (3C 49, 3C 93.1, 3C 138, 3C 268.3, 3C305.1 and 3C343.1) ``snapshot&#39;&#39; images

Shibaji Banerjee, Sanjay K. Ghosh, Amal Mazumdar, Sibaji Raha

There have been several reports of exotic nuclear fragments, with highly unusual charge to mass ratio, in cosmic ray experiments. Although there exist experimental uncertainties which make them, at best, only candidate &#34;exotic&#34; events, it is important to understand what they could be, if they are eventually confirmed. Among other possible explanation

Yi-Ping Qin

In this paper we show explicit and direct relations between the expected quantities and the observed quantities for the components of Galactic superluminal sources. Basic formulas for calculating the real speed and the angle to the line of sight of the components from the data of proper motions and the distance of the source are presented. We point out that

Andrei M. Beloborodov, Andrei F. Illarionov

Gas falling quasi-spherically onto a black hole forms an inner accretion disc if its specific angular momentum $l$ exceeds $\lmin\sim r_gc$ where $r_g$ is the Schwarzschild radius. The standard disc model assumes $l\gg\lmin$. We argue that, in many black-hole sources, accretion flows have angular momenta just above the threshold for disc formation, $l\simgt\

Paul R. Shapiro, Ilian T. Iliev

Observations of a flat density profile in the cores of dark-matter-dominated halos on the two extremes of mass for virialized objects in the universe, dwarf galaxies and galaxy clusters, present a serious challenge to the current standard theory of structure formation involving Cold Dark Matter (CDM). By contrast, N-body simulations of halo formation in the

Andrei F. Illarionov, Andrei M. Beloborodov

In wind-fed X-ray binaries the accreting matter is Compton cooled and falls freely onto the compact object. The matter has a modest angular momentum $l$ and accretion is quasi-spherical at large distances from the compact object. Initially small non-radial velocities grow in the converging supersonic flow and become substantial in the vicinity of the accreto

Navin Khaneja, Roger Brockett, Steffen Glaser

In this paper, we study the design of pulse sequences for NMR spectroscopy as a problem of time optimal control of the unitary propagator. Radio frequency pulses are used in coherent spectroscopy to implement a unitary transfer of state. Pulse sequences that accomplish a desired transfer should be as short as possible in order to minimize the effects of rela

Oleg Lunin, Samir D. Mathur

We develop a method for computing correlation functions of twist operators in the bosonic 2-d CFT arising from orbifolds M^N/S_N, where M is an arbitrary manifold. The path integral with twist operators is replaced by a path integral on a covering space with no operator insertions. Thus, even though the CFT is defined on the sphere, the correlators are expre

J. Alam, A. Hayashigaki, K. Suzuki, T. Hatsuda

The elastic leptoproduction of $ϕ$ measured by the H1 collaboration at HERA is described by a perturbative QCD model, based on open $s\bar{s}$ production and parton hadron duality, proposed by Martin et al. We observe that both the total cross section and the ratio of the longitudinal and transverse cross sections are well reproduced with an effective strang

Yongseok Oh, Alexander I. Titov, T. -S. H. Lee

The role of the nucleon resonances ($N^*$) in $ω$ photoproduction is investigated by using the resonance parameters predicted by Capstick and Roberts [Phys. Rev. D {\bf 46}, 2864 (1992); {\bf 49}, 4570 (1994)]. In contrast with the previous investigations based on the ${SU}(6) \times {O}(3)$ limit of the constituent quark model, the employed $N^* \to γN$ and

Piotr J. Flatau, Jacek Piskozub, J. Ronald V. Zaneveld

We report that the submerged microbubbles are an efficient source of diffuse radiance and may contribute to a rapid transition to the diffuse asymptotic regime. In this asymptotic regime an average cosine is easily predictable and measurable.

Yoram Louzoun, Sorin Solomon, Henri Atlan, Irun. R. Cohen

We study the emergence of the collective spatio-temporal macroscopic properties of the immune system, by representing individually the elementary interactions between its microscopic components (antibodies, antigens, cytokines). The results of this detailed explicit analysis are compared with the traditional procedure of averaging over individuals and repres

Fumiharu Kato

In this article we discuss a certain p-adic analogue of classical Schwarzian triangle groups, an analogue which is related to Mumford&#39;s uniformization of p-adic analytic curves. p-adic Schwarzian triangle groups are defined to be the Galois groups of analytic coverings over projective line with precisely 3 branch points. We say that a p-adic triangle gro

David Eisenbud, Sorin Popescu, Charles Walter

We show that a Gorenstein subcanonical codimension 3 subscheme Z in X = P^N, N > 3, can be realized as the locus along which two Lagrangian subbundles of a twisted orthogonal bundle meet degenerately, and conversely. We extend this result to singular Z and all quasiprojective ambient schemes X under the necessary hypothesis that $Z$ is strongly subcanonical

B. Jun

In this note, we study monodromies of algebraic connections on the trivial vector bundle. We prove that on a smooth complex affine curve, any monodromy arises as the underlying local system of an algebraic connection on the trivial bundle. We give a generalization of this for rank one monodromies in higher dimension.

Mark Andrea de Cataldo, Luca Migliorini

We introduce the notion of lef line bundles on a complex projective manifold. We prove that lef line bundles satisfy the Hard Lefschetz Theorem, the Lefschetz Decomposition and the Hodge-Riemann Bilinear Relations. We study proper holomorphic semismall maps from complex manifolds and prove that, for constant coefficients, the Decomposition Theorem is equival

Fumiharu Kato

This paper is originally designed as a part of revision of the author&#39;s preprint math.AG/9908174 &#34;P-adic Schwarzian triangle groups of Mumford type&#34;. Recently, Yves Andr&#39;e pointed out a flaw in that preprint; more precisely, Proposition II there was not correct, and consequently, as he pointed out, some triangle groups are missing (but only i

D. Kaledin, M. Verbitsky

We study the deformations of a holomorphic symplectic manifold $M$, not necessarily compact, over a formal ring. We show (under some additional, but mild, assumptions on $M$) that the coarse deformation space exists and is smooth, finite-dimensional and naturally embedded into $H^2(M)$. For a holomorphic symplectic manifold $M$ which satisfies $H^1(M,{\cal O

L. Ya. Glozman

It is shown that in the large $N_c$ limit the light baryon spectrum exhibits the chiral restoration phase transition at high enough excitation energy. Such a phase transition is evidenced by the systematical parity doublets observed in the upper part of $N$ and $Δ$ spectra.

H. Kudoh, T. Harada, H. Iguchi

We investigate the causal structure of the Harada-Iguchi-Nakao (HIN)&#39;s exact solution in detail, which describes the dynamical formation of naked singularity in the collapse of a regular spherical cluster of counterrotating particles. There are three kinds of radial null geodesics in the HIN spacetime. One is the regular null geodesics and the other two

A. Venimadhav, M. S. Hegde, V. Prasad, S. V. Subramanyam

Magnanite multilayers have been fabricated using La0.67Ca0.33MnO3 as the ferromagnetic layer and Pr0.7Ca0.3MnO3 and Nd0.5Ca0.5MnO3 as the spacer layers. All the multilayers were grown on LaAlO3 (100) by pulse laser deposition. An enhanced magnetoresistnace (defined (RH- R0)/R0) of more than 98% is observed in these multilayers. Also a low field magnetoresist

A. Heger, R. D. Hoffman, T. Rauscher, S. E. Woosley

We present the first calculations to follow the evolution of all stable isotopes (and their abundant radioactive progenitors) in a finely zoned stellar model computed from the onset of central hydrogen burning through explosion as a Type II supernova. The calculations were performed for a 15 solar mass Pop I star using the most recently available set of expe

S. Kimeswenger, J. Koller, S. Schmeja

The central dust knot V605 Aql (= Nova Aql 1919) in the planetary nebula A58 is the result of a late-helium flash. Previous near infrared (NIR) measurements yield very bright fluxes. This exceeds model predictions, based on other wavelengths and estimates of the visual extinction within the object, by a factor of 100. Using NIR imaging by the DENIS instrumen

I. Fuentes-Guridi, S. Bose, V. Vedral

We propose a scheme for measuring the Berry phase in the vibrational degree of freedom of a trapped ion. Starting from the ion in a vibrational coherent state we show how to reverse the sign of the coherent state amplitude by using a purely geometric phase. This can then be detected through the internal degrees of freedom of the ion. Our method can be applie

Anders Sorensen, Lu-Ming Duan, Ignacio Cirac, Peter Zoller

We propose a method to produce entangled states of several particles starting from a Bose-Einstein condensate. In the proposal, a single fast $π/2$ pulse is applied to the atoms and due to the collisional interaction, the subsequent free time evolution creates an entangled state involving all atoms in the condensate. The created entangled state is a spin-squ

O. E. Kalashev, V. A. Kuzmin, D. V. Semikoz

We considered propagation of Ultra High Energy Cosmic Rays (UHECR) through the galaxy. We investigated models with sources of UHECR distributed in the same way as Cold Dark Matter (CDM) in a self-consistent way, taking into account both extra-galactic and Galactic contributions. Using a very simple toy model of galactic magnetic field we showed that in the c

Yuri O. Popov, Thomas A. Witten

The shape of a liquid surface bounded by an acute or obtuse planar angular sector is considered by using classical analysis methods. For acute angular sectors the two principal curvatures are of the order of the (fixed) mean curvature. But for obtuse sectors, the principal curvatures both diverge as the vertex is approached. The power-law divergence becomes

Anthony Aguirre, Lars Hernquist, Neal Katz, Jeffrey Gardner

The presence of metals in hot cluster gas and in Ly-alpha absorbers, as well as the mass-metallicity relation of observed galaxies, suggest that galaxies lose a significant fraction of their metals to the intergalactic medium (IGM). Theoretical studies of this process have concentrated on metal removal by dynamical processes or supernova-driven winds. Here,

Anthony Aguirre, Lars Hernquist, Joop Schaye, David Weinberg

Studies of quasar absorption lines reveal that the low density intergalactic medium at z ~ 3 is enriched to 0.001-0.01 solar metallicity. This enrichment may have occurred in an early generation of Population III stars at redshift z >~ 10, by protogalaxies at 6 <~ z <~ 10, or by larger galaxies at 3 <~ z <~ 6. This paper addresses the third possibility by ca

Ken Kiers, Amarjit Soni, Guo-Hong Wu

We consider the partial rate asymmetry in the inclusive decay modes b to s gamma and b to d gamma, concentrating on non-standard models with new charged Higgs interactions. We find that the charged Higgs contribution to the asymmetry for b to s gamma is small in such models due to a universal cancellation mechanism. The asymmetry is therefore difficult to di

Anatoly Klypin, Andrey V. Kravtsov, James Bullock, Joel Primack

We study the effects of mass and force resolution on the density profiles of galaxy-size Cold Dark Matter (CDM) halos in a flat, low-density cosmological model with vacuum energy. We show thatalthough increasing the mass and force resolution allows us to probe deeper into the inner halo regions, it does not lead to steeper inner density profiles. Instead, th

Gaston Garcia-Calderon, Alberto Rubio, Jorge Villavicencio

We consider exact time-dependent analytic solutions to the Schrödinger equation for tunneling in one dimension with cut off wave initial conditions at $t=0$. We obtain that as soon as $t \neq 0$ the transmitted probability density at any arbitrary distance rises instantaneously with time in a linear manner. Using a simple model we find that the above nonloca

Shin-ichi Sasa

We numerically study a billiard system with a time-dependent force, and our results suggest the existence of a limitation on possible transitions between steady states in Hamiltonian chaos, in analogy to the limitation on transitions between equilibrium states described by the second law of thermodynamics. This limitation is expressed in terms of irreversibl

Michael J. Gruber

For differential operators which are invariant under the action of an abelian group Bloch theory is the preferred tool to analyze spectral properties. By shedding some new non-commutative light on this we motivate the introduction of a non-commutative Bloch theory for elliptic operators on Hilbert C*-modules. It relates properties of C*-algebras to spectral

Tomoshiro Ochiai

In this paper, we shall give an explicit Gauss diagram formula for the Kontsevich integral of links up to degree four. This practical formula enables us to actually compute the Kontsevich integral in a combinatorial way.

Jorge Cortes, Manuel de Leon, David Martin de Diego, Sonia Martinez

We treat the vakonomic dynamics with general constraints within a new geometric framework which will be appropriate to study optimal control problems. We compare our formulation with Vershik-Gershkovich one in the case of linear constraints. We show how nonholonomic mechanics also admits a new geometrical description wich enables us to develop an algorithm o

U. Guenther, A. Zhuk

The possibility of dynamical stabilization of an internal space is investigated for a multidimensional cosmological model with minimal coupled scalar field as inflaton. It is shown that a successful dynamical compactification crucially depends on the type of interaction between the geometrical modulus field and the inflaton and its decay products. In the con

W. Melnitchouk

Asymmetries in the quark momentum distributions in the proton reveal fundamental aspects of strong interaction physics. Differences between u-bar and d-bar quarks in the proton sea provide insight into the dynamics of the pion cloud around the nucleon and the nature of chiral symmetry breaking. Polarized flavor asymmetries allow the effects of pion clouds to

N. Haba, Tomoharu Suzuki

It has been said that the measurements of $U_{e3}$ in the lepton flavor mixing matrix would help discriminate between the possible solar neutrino solutions under the natural conditions with the neutrino mass hierarchies of $m_1 \ll m_2 \ll m_3$ and $m_1 \sim m_2 \gg m_3$, where $m_i$ is the $i$-th generation neutrino absolute mass. However, it is not true, a

Junichi Iwasaki

A lattice quantum gravity model in 4 dimensional Riemannian spacetime is constructed based on the SU(2) Ashtekar formulation of general relativity. This model can be understood as one of the family of models sometimes called ``spin foam models.&#39;&#39; A version of the action of general relativity in continuum is introduced and its lattice version is defin

Subrata Sanyal, Dmitry Yavich, L. Gary Leal

We present an extensive experimental study of birefringence and velocity-gradient components for a series of high molecular weight, flexible, entangled polystyrene solutions subjected to transient start-up flows in a co-rotating two-mill to several Weissenberg numbers. The time-dependent changes in the polymer microstructure, as measured by a two-color flow

Franz E. Schunck, Eckehard W. Mielke

By using the rather stringent nonlinear second order slow-roll approximation, we reconsider the nonlinear second order Abel equation of Stewart and Lyth. We determine a new blue eigenvalue spectrum. Some of the discrete values of the spectral index $n_s$ have consistent fits to the cumulative COBE data as well as to recent ground-base CMB experiments.

M. J. Page, J. P. D. Mittaz, F. J. Carrera

We present a catalogue of 147 serendipitous X-ray sources selected to have hard spectra (alpha < 0.5) from a survey of 188 ROSAT fields. Such sources must be the dominant contributors to the X-ray background at faint fluxes. We have used Monte Carlo simulations to verify that our technique is very efficient at selecting hard sources: the survey has > 10 time

Jeffrey P. Gardner

I present results from numerical N-body simulations regarding the effect of merging events on the angular momentum distribution of galactic halos as well as a comparison of halo growth in Press-Schechter vs. N-body methods. A total of six simulations are used spanning 3 cosmologies: a standard flat Omega_0=1 model, an open Omega_0=0.3 model and a &#34;tilted

R. Coldea, S. M. Hayden, G. Aeppli, T. G. Perring

The magnetic excitations of the square-lattice spin-1/2 antiferromagnet and high-Tc parent La2CuO4 are determined using high-resolution inelastic neutron scattering. Sharp spin waves with absolute intensities in agreement with theory including quantum corrections are found throughout the Brillouin zone. The observed dispersion relation shows evidence for sub

Alex Barnett, Doron Cohen, Eric J. Heller

We consider the response of a chaotic cavity in d dimensions to periodic driving. We are motivated by older studies of one-body dissipation in nuclei, and also by anticipated mesoscopic applications. For calculating the rate of energy absorption due to time-dependent deformation of the confining potential, we introduce an improved version of the wall formula

Nemanja Kaloper, Eva Silverstein, Leonard Susskind

We discuss the possibility of having gravity ``localized&#39;&#39; in dimension d in a system where gauge bosons propagate in dimension d+1. In such a circumstance - depending on the rate of falloff of the field strengths in d dimensions - one might expect the gauge symmetry in d+1 dimensions to behave like a global symmetry in d dimensions, despite the pres

R. N. Mohapatra, A. Pérez-Lorenzana

The key challenges for models with large extra dimensions, posed by neutrino physics are: first to understand why neutrino masses are small and second, whether one can have a simultaneous explanation of all observed oscillation phenomena. There exist models that answer the first challenge by using singlet bulk neutrinos coupled to the standard model in the b

Mark J. Bowick, Angelo Cacciuto, Gudmar Thorleifsson, Alex Travesset

We present an analysis of extensive large-scale Monte Carlo simulations of self-avoiding fixed-connectivity membranes for sizes (number of faces) ranging from 512 to 17672 (triangular) plaquettes. Self-avoidance is implemented via impenetrable plaquettes. We simulate the impenetrable plaquette model in both three and four bulk dimensions. In both cases we fi

V. Barger, T. Han, T. Li, J. D. Lykken

We examine the cosmology and hierarchy of scales in models with branes immersed in a five-dimensional curved spacetime subject to radion stabilization. When the radion field is time-independent and the inter-brane spacing is stabilized, the universe can naturally find itself in the radiation-dominated epoch. This feature is independent of the form of the sta

E. A. Jagla

A system of identical particles interacting through an isotropic potential that allows for two preferred interparticle distances is numerically studied. When the parameters of the interaction potential are adequately chosen, the system exhibits coexistence between two different liquid phases (in addition to the usual liquid-gas coexistence). It is shown that

Spenta R. Wadia

In these notes we review the theory of the microscopic modeling of the 5-dim. black hole of type IIB string theory in terms of the $D1-D5$ brane system. The emphasis here is more on the brane dynamics rather than on supergravity solutions. We present a discussion of the low energy brane dynamics and account for black hole thermodynamics and Hawking radiation

Claudio Dib, Vladimir Gribanov, Sergey Kovalenko, Ivan Schmidt

Recently an upper bound on the rate of the lepton number violating decay $K^+\to μ^+μ^+π^-$ has been significantly reduced by the E865 experiment at BNL and further improvement is expected in the near future. We study this process as a possible source of information on neutrino masses and mixings. We find that it is insensitive to the light(eV domain) and he

K. M. Mertes, Hairong Zheng, S. A. Vitkalov, M. P. Sarachik

We report measurements of the resistance of silicon MOSFETs as a function of temperature in high parallel magnetic fields where the 2D system of electrons has been shown to be fully spin-polarized. A magnetic field suppresses the metallic behavior observed in the absence of a magnetic field. In a field of 10.8 T, insulating behavior is found for densities up

I. V. Yurkevich, Igor V. Lerner

We suggest a novel nonlinear $σ$-model for the description of disordered superconductors. The main distinction from existing models lies in the fact that the saddle point equation is solved non-perturbatively in the superconducting pairing field. It allows one to use the model both in the vicinity of the metal-superconductor transition and well below its cri

Dmitri V. Gal&#39;tsov, Elena Yu. Melkumova

Recent scenarios of the TeV-scale brane cosmology suggest a possibility of existence in the early universe of two-dimensional topological defects: relativistic membranes. Like cosmic strings, oscillating membranes could emit gravitational radiation contributing to a stochastic background of gravitational waves. We calculate dilaton and gravitational radiatio

Bartomeu Fiol, Marcos Marino

We discuss several aspects of D-brane moduli spaces and BPS spectra near orbifold points. We give a procedure to determine the decay products on a line of marginal stability, and we define the algebra of BPS states in terms of quivers. These issues are illustrated in detail in the case of type IIA theory on C^2/Z_N. We also show that many of these results ca

Anthony Chefles, Claire R. Gilson, Stephen M. Barnett

Collective operations on a network of spatially-separated quantum systems can be carried out using local quantum (LQ) operations, classical communication (CC) and shared entanglement (SE). Such operations can also be used to communicate classical information and establish entanglement between distant parties. We show how these facts lead to measures of the i

E. E. Zabrodin, C. Fuchs, L. V. Bravina, Amand Faessler

The transverse momentum ($p_t$) dependence of hadron flow at SPS energies is studied. In particular, the nucleon and pion flow in S+S and Pb+Pb collisions at 160 AGeV is investigated. For simulations the microscopic quark-gluon string model (QGSM) is applied. It is found that the directed flow of pions $v_1(y, Δp_t)$ changes sign from a negative slope in the