arXiv papers from June 2001

V. Ramakrishna

The reachable set for a finite dimensional quantum system is shown to be the orbit of the group corresponding to the internal and control Hamiltonians, even if this group is not compact.

B. L. Feigin, S. A. Loktev, I. Yu. Tipunin

We propose an alternative definition of q-supernomial coefficients as characters of coinvariants for one dimensional lattice vertex operator algebras. This gives a new formula for q-supernomial coefficients. Along the way we prove that the spaces of coinvariants form a bundle over the configuration space of complex points (the configuration space includes di

Torsten Ekedahl

This paper takes its starting point in an idea of Grothendieck on the representation of homotopy types. We show that any locally finite nilpotent homotopy can be represented by a simplicial set which is a finitely generated free group in all degrees and whose maps are given by polynomials with rational coefficients. Such a simplicial set is in some sense a u

Christian Y. Cardall

The depth of our theoretical understanding of neutrino flavor mixing should match the importance of this phenomenon as a herald of long-awaited empirical challenges to the standard model of particle physics. After reviewing the familiar, simplified quantum mechanical model and its flaws, I sketch the deeper understanding of both vacuum and matter-enhanced fl

M. A. Avila, L. Civale, A. V. Silhanek, R. A. Ribeiro

We have measured the irreversible magnetization M_i of an ErBa_2Cu_3O_7 single crystal with columnar defects (CD), using a technique based on sample rotation under a fixed magnetic field H. This method is valid for samples whose magnetization vector remains perpendicular to the sample surface over a wide angle range - which is the case for platelets and thin

Charles A. Akemann, Joel Anderson

Suppose that c is a linear operator acting on an n-dimensional complex Hilbert Space H, and let tau denote the normalized trace on B(H). Set b_1 = (c+c*)/2 and b_2 = (c-c*)/2i, and write B for the the spectral scale of {b_1, b_2} with respect to tau. We show that B contains full information about (W_k)(c), the k-numerical range of c for each k =1,...,n. We t

Renat Kh. Gainutdinov, Aigul A. Mutygullina

We discuss the problem of renormalization of dynamical equations which arises in an effective field theory description of nuclear forces. By using a toy model of the separable NN potential leading to logarithmic singularities in the Born series, we show that renormalization gives rise to nucleon dynamics which is governed by a generalized dynamical equation

Indira Chatterji

We apply V. Lafforgue's techniques to establish the rapid decay property for cocompact lattices in a finite product of rank one Lie groups with Lie groups whose restricted root system is of type A2.

N. D. Hari Dass, K. V. Shajesh

We present here a manifestly gauge invariant calculation of vacuum polarization to fermions in the presence of a constant Maxwell and a constant Kalb-Ramond field in four dimensions. The formalism is a generalisation of the one used by Schwinger in his famous paper on gauge invariance and vacuum polarization. We get an explicit expression for the vacuum pola

Lorenzo Iorio, Herbert I. M. Lichtenegger, Bahram Mashhoon

The possibility of detecting the gravitomagnetic clock effect using artificial Earth satellites provides the incentive to develop a more intuitive approach to its derivation. We first consider two test electric charges moving on the same circular orbit but in opposite directions in orthogonal electric and magnetic fields and show that the particles take diff

T. Dietl, Jürgen König, A. H. MacDonald

Recent progress in theoretical understanding of magnetic anisotropy and stiffness in III-V magnetic semiconductors is exploited for predictions of magnetic domain characteristics and methods of their tuning. We evaluate the width and the energy of domain walls as well as the period of stripe domains in perpendicular films. The computed stripe width d = 1.1 u

W. F. Thi, E. F. van Dishoeck, G. A. Blake, G. J. van Zadelhoff

We present ISO-SWS observations of H2 pure-rotational line emission from the disks around low and intermediate mass pre-main-sequence stars as well as from young stars thought to be surrounded by debris disks. We detect `warm' (T ~ 100-200 K) H2 gas around many sources, including tentatively the debris-disk objects. The mass of this warm gas ranges from ~1E-

M. Bordag, V. V. Nesterenko, I. G. Pirozhenko

The high temperature asymptotics of the Helmholtz free energy of electromagnetic field subjected to boundary conditions with spherical and cylindrical symmetries are constructed by making use of a general expansion in terms of heat kernel coefficients and the related determinant. For this, some new heat kernel coefficients and determinants had to be calculat

A. Omont, P. Cox, F. Bertoldi, R. G. McMahon

We report 250 GHz (1.2mm) observations of redshift > 3.8 quasars from the Palomar Sky Survey (PSS) sample, using the Max-Planck Millimetre Bolometer (MAMBO) array at the IRAM 30-metre telescope. Eighteen sources were detected and upper limits were obtained for 44 with 3-sigma flux density limits in the range 1.5-4 mJy. Adopting typical dust temperatures of 4

Sen Cheng, Scott Pratt, Peter Csizmadia, Yasushi Nara

The effect of scattering with non-zero impact parameters between consituents in relativistic heavy ion collisions is investigated. In solving the relativistic Boltzmann equation, the characteristic range of the collision kernel is varied from approximately one fm to zero while leaving the mean-free path unchanged. Modifying this range is shown to significant

Chan-Gyung Park, Changbom Park, Bharat Ratra

We study the effects of diffuse Galactic, far-infrared extragalactic source, and radio point source emission on the cosmic microwave background (CMB) anisotropy data anticipated from the MAP experiment. We focus on the correlation function and genus statistics measured from mock MAP foreground-contaminated CMB anisotropy maps generated in a spatially-flat co

Bozhidar Z. Iliev

We propose a fibre bundle formulation of the mathematical base of relativistic quantum mechanics. At the present stage the bundle form of the theory is equivalent to its conventional one, but it admits new types of generalizations in different directions. In the present, second, part of our investigation, we consider a covariant approach to bundle descriptio

Fugao Wang, David. P. Landau

We describe an efficient Monte Carlo algorithm using a random walk in energy space to obtain a very accurate estimate of the density of states for classical statistical models. The density of states is modified at each step when the energy level is visited to produce a flat histogram. By carefully controlling the modification factor, we allow the density of

A. K. Sanyal, B. Modak

The correct quantum description for a curvature squared term in the action can be obtained by casting the action in the canonical form with the introduction of a variable which is the negative of the first derivative of the field variable appearing in the action, only after removing the total derivative terms from the action. We present the Wheeler-DeWitt eq

N. R. Cooper, N. K. Wilkin, J. M. F. Gunn

We investigate the groundstates of weakly interacting bosons in a rotating trap as a function of the number of bosons, $N$, and the average number of vortices, $N_V$. We identify the filling fraction $\nu\equiv N/N_V$ as the parameter controlling the nature of these states. We present results indicating that, as a function of $\nu$, there is a zero temperatu

Deog Ki Hong, Y. J. Sohn

Solving the Schwinger-Dyson equations, we analyze the pairing of quarks in asymmetric quark matter where quarks have different chemical potentials. We show that in the asymmetric quark matter a crystalline color-superconducting gap opens when the quark coupling is stronger than a critical value. The critical coupling is nonzero, since the infrared divergence

Sher Alam, T. Yanagisawa, H. Oyanagi

Keeping in mind the experimental results that indicate local lattice distortions, charge and spin orderings, we have developed a phenomenological approach which allows us to describe the electronic phase diagram of cuprates and related systems in terms of few parameters.In the present work we consider a third-order parameter theory which characterize charge,

Ziqiang Wang, Jan R. Engelbrecht, Shancai Wang, Hong Ding

Recent scanning tunneling microscope (STM) measurements discovered remarkable electronic inhomogeneity, i.e. nano-scale spatial variations of the local density of states (LDOS) and the superconducting energy gap, in the high-Tc superconductor BSCCO. Based on the experimental findings we conjectured that the inhomogeneity arises from variations in local oxyge

W. A. Perkins

The similarity of the commutation relations for bosons and quasibosons (fermion pairs) suggests the possibility that all integral spin particles presently considered to be bosons could be quasibosons. The boson commutation relations for integral spin particles could be just an approximation to the quasiboson commutation relations that contain an extra term.

Lubos Motl

In this short note we construct the DLCQ description of the flux seven-branes in type IIA string theory and discuss its basic properties. The matrix model involves dipole fields. We explain the relation of this nonlocal matrix model to various orbifolds. We also give a spacetime interpretation of the Seiberg-Witten-like map, proposed in a different context f

Masanao Ozawa

An indirect measurement model is constructed for an approximately repeatable, precise position measuring apparatus that violates the assertion, sometimes called the Heisenberg uncertainty principle, that any position measuring apparatus with noise epsilon brings the momentum disturbance no less than hbar/2epsilon in any input state of the apparatus.

Jill Bechtold, Aneta Siemiginowska, Thomas L. Aldcroft, Martin Elvis

We have observed three quasars, PKS 1127-145, Q 1331+171 and Q0054+144, with the ACIS-S aboard the Chandra X-ray Observatory, in order to measure soft X-ray absorption associated with intervening 21-cm and damped Ly$\alpha$ absorbers. For PKS 1127-145, we detect absorption which, if associated with an intervening z_{abs}=0.312 absorber, implies a metallicity

Robert Coquereaux, Gil Schieber

For every ADE Dynkin diagram, we give a realization, in terms of usual fusion algebras (graph algebras), of the algebra of quantum symmetries described by the associated Ocneanu graph. We give explicitly, in each case, the list of the corresponding twisted partition functions

Yuval Oreg, Eugene Demler

We discuss the destruction of superconductivity in quasi-one-dimensional systems due to the interplay between disorder and Coulomb repulsion. We argue that to understand the behavior of the system one has to study both fermionic and bosonic mechanisms of suppression of superconductivity. The former describes reduction in the mean field critical temperature $

J. B. Hutchings, G. A. Kriss, R. F. Green, M. Brotherton

Spectroscopic data in wavelengths 900--3000A have been obtained in a low flux state of the nucleus of the Seyfert 1 galaxy NGC 3516. The line profiles show P Cygni characteristics, particularly in O VI 1032A, and are compared with data from an earlier higher state. The profiles are suggestive of, and consistent with, an accelerating wind driven by a disk con

Kunal Das

We develop a simple analytical model based on a variational method to explain the properties of trapped cylindrically symmetric Bose-Einstein condensates (BEC) of varying degrees of anisotropy well into regimes of effective one dimension (1D) and effective two dimension (2D). Our results are accurate in regimes where the Thomas-Fermi approximation breaks dow

Alexey Anisimov, Tom Banks, Michael Dine, Michael Graesser

It is natural to ask whether non-commutative geometry plays a role in four dimensional physics. By performing explicit computations in various toy models, we show that quantum effects lead to violations of Lorentz invariance at the level of operators of dimension three or four. The resulting constraints are very stringent.

Vasiliki Plerou, Parameswaran Gopikrishnan, Xavier Gabaix, H. Eugene Stanley

We address the question of how stock prices respond to changes in demand. We quantify the relations between price change $G$ over a time interval $\Delta t$ and two different measures of demand fluctuations: (a) $\Phi$, defined as the difference between the number of buyer-initiated and seller-initiated trades, and (b) $\Omega$, defined as the difference in

Paolo Aschieri

We show that noncommutative electromagnetism and Dirac-Born-Infeld (DBI) theory with scalar fields are SL(2,R) self-dual when noncommutativity is light-like and we are in the slowly varying field approximation. This follows from SL(2,R) self-duality of the commutative DBI Lagrangian and of its zero slope limit that we study in detail. We study a symmetry of

Marko B. Popovic

It is shown that the effective Standard Model theory with the physical Higgs mass lighter than $\sim 200$ GeV takes the form of an unbroken electroweak theory already at moderately high, $O(1 TeV)$, energy scales. No such transitional scale exists for the heavier Higgses. This result is independently obtained by two standard regularization methods.

L. V. E. Koopmans, M. A. Garrett, R. D. Blandford, C. R. Lawrence

A single-screen model of the gravitational lens system 2016+112 is proposed, that explains recent Hubble Space Telescope} (HST) infrared (NICMOS-F160W) observations and new high-resolution European VLBI Network (EVN) 5-GHz radio observations, presented in this paper. In particular, we find that a massive `dark' structure at the lens position, previously sugg

Stephan I. Tzenov

Building on the Renormalization Group (RG) method the beam-beam interaction in circular colliders is studied. A regularized symplectic RG beam-beam map, that describes successfully the long-time asymptotic behavior of the original system has been obtained. The integral of motion possessed by the regularized RG map has been used to construct the invariant pha

R. A. Bertlmann, W. Grimus, B. C. Hiesmayr

We give an introduction to an entangled massive system, specifically the neutral kaon system, which has similarities to the entangled two photon system, but, however, also challenging differences.

SangChul Yoon

We work on the relation between the local thermodynamic instability and the dynamical instability of large black holes in four-dimensional anti-de Sitter space proposed by Gubser and Mitra. We find that all perturbations suppressing the metric fluctuations at linear order become dynamically unstable when black holes lose the local thermodynamic stability. We

Jorgen Rasmussen, Mark A. Walton

Affine su(3) and su(4) fusion multiplicities are characterised as discretised volumes of certain convex polytopes. The volumes are measured explicitly, resulting in multiple sum formulas. These are the first polytope-volume formulas for higher-rank fusion multiplicities. The associated threshold levels are also discussed. For any simple Lie algebra we derive

Y. -D. Chuang, A. D. Gromko, D. S. Dessau, T. Kimura

We used high resolution angle-resolved photoemission spectroscopy to reveal the Fermi surface and key transport parameters of the metallic state of the layered Colossal Magnetoresistive (CMR) oxide La1.2Sr1.8Mn2O7. With these parameters the calculated in-plane conductivity is nearly one order of magnitude larger than the measured DC conductivity. This discre

S. G. Djorgovski, D. A. Frail, S. R. Kulkarni, R. Sari

Cosmic gamma-ray bursts are one of the great frontiers of astrophysics today. They are a playground of relativists and observers alike. They may teach us about the death of stars and the birth of black holes, the physics in extreme conditions, and help us probe star formation in the distant and obscured universe. In this review we summarise some of the remar

Travis S. Metcalfe

White dwarf asteroseismology offers the opportunity to probe the structure and composition of stellar objects governed by relatively simple physical principles. The observational requirements of asteroseismology have been addressed by the development of the Whole Earth Telescope, but the analysis procedures still need to be refined before this technique can

P. Baseilhac, G. W. Delius

We present an integrable Hamiltonian which describes the sinh-Gordon model on the half line coupled to a non-linear oscillator at the boundary. We explain how we apply Sklyanin's formalism to a dynamical reflection matrix to obtain this model. This method can be applied to couple other integrable field theories to dynamical systems at the boundary. We also s

T. Uezu

In a previous letter, we studied learning from stochastic examples by perceptrons with Ising weights in the framework of statistical mechanics. Under the one-step replica symmetry breaking ansatz, the behaviours of learning curves were classified according to some local property of the rules by which examples were drawn. Further, the conditions for the exist

M. Suzuki

The Section of charm quark spin conservation is deleted since it involves more dynamical assumptions than previously stated. A few comments are added in view of new experimental results.

Anders Skovsted Buch

We give elementary proofs of the main theorems about (small) quantum cohomology of Grassmannians, including the quantum Giambelli and quantum Pieri formulas, the rim-hook algorithm, Siebert and Tian's presentation, and a recent theorem of Fulton and Woodward about the minimal q-power which appears in a product of two Schubert classes.

Bert Schroer

Recent developments in local quantum physics have led to revolutionary conceptual changes in the thinking about a more intrinsic formulation and in particular about unexpected aspects of localized degrees of freedom. This paradigmatic change is most spectacular in a new rigorous form of ``holography'' and ``transplantation'' as generic properties in QFT beyo

Matthias Beck, Alex J. Feingold, Michael D. Weiner

We study M(n,k,r), the number of orbits of {(a_1,...,a_k)\in Z_n^k | a_1+...+a_k = r (mod n)} under the action of S_k. Equivalently, M(n,k,r) sums the partition numbers of an arithmetic sequence: M(n,k,r) = sum_{t \geq 0} p(n-1,k,r+nt), where p(a,b,t) denotes the number of partitions of t into at most b parts, each of which is at most a. We derive closed for

Michael J. Quist

The application of the Schwinger-boson transformation to quantum Heisenberg magnets is briefly reviewed, beginning with the derivation of a rotationally invariant mean-field theory. The inclusion of Gaussian fluctuations is discussed in some detail for a general (non-Bravais) lattice, extending available results for simple lattices. Numerical results are pre

Nathan Isgur, Alan Kostelecky, Adam Szczepaniak

Photoproduction of neutral-kaon pairs is studied from the perspective of CP and CPT studies. Interference of the P and S waves, with the former due to diffractive phi production and the latter to f_0/a_0 production, is shown to enhance the CPT reach. Results are presented of Monte Carlo studies based on rates expected in future experiments.

Ronald Umble

Let H be a differential graded Hopf algebra over a field k. This paper gives an explicit construction of a triple cochain complex that defines the Hochschild-Cartier cohomology of H. A certain truncation of this complex is the appropriate setting for deforming H as an H(q)-structure. The direct limit of all such truncations is the appropriate setting for def

Edmund J. Copeland, James Gray, Andre Lukas

We construct cosmological solutions of four-dimensional effective heterotic M-theory with a moving five-brane and evolving dilaton and T modulus. It is shown that the five-brane generates a transition between two asymptotic rolling-radii solutions. Moreover, the five-brane motion always drives the solutions towards strong coupling asymptotically. We present

Howard Baer, Javier Ferrandis

Supersymmetric grand unified models based on SO(10) gauge symmetry have many desireable features, including the unification of Yukawa couplings. Using D-term contributions to scalar masses arising from the breakdown of SO(10), Yukawa coupling unification only to 30% can be achieved in models with a positive superpotential Higgs mass. The superparticle mass s

Shu Chen, H. Buettner, J. Voit

We investigate an asymmetric zig-zag spin ladder with different exchange integrals on both legs using bosonization and renormalization group. When the leg exchange integrals and frustration both are sufficiently small, renormalization group analysis shows that the Heisenberg critical point flows to an intermediate-coupling fixed point with gapless excitation

Christopher A. Fuchs

This paper reports three almost trivial theorems that nevertheless appear to have significant import for quantum foundations studies. 1) A Gleason-like derivation of the quantum probability law, but based on the positive operator-valued measures as the basic notion of measurement (see also Busch, quant-ph/9909073). Of note, this theorem also works for 2-dime

Subrata Pal, C. M. Ko, Zi-wei Lin

Using a multiphase transport model, we study the production of multistrange baryons from the hadronic matter formed in relativistic heavy ion collisions. The mechanism we introduce is the strangeness-exchange reactions between antikaons and hyperons. We find that these reactions contribute significantly to the production of multistrange baryons in heavy ion

Goran Johansson, Andreas Kack, Goran Wendin

We calculate the spectral density of voltage fluctuations in a Single Electron Transistor (SET), biased to operate in a transport mode where tunneling events are correlated due to Coulomb interaction. The whole spectrum from low frequency shot noise to quantum noise at frequencies comparable to the SET charging energy $(E_{C}/\hbar)$ is considered. We discus

Ikaros Bigi, Nikolai Uraltsev

We present an elementary introduction to the problem of quark-hadron duality and its practical limitations, in particular as it concerns local duality violation in inclusive B meson decays. We show that the accurate definition of duality violation elaborated over the recent years allows one to derive informative constraints on violations of local duality. Th

M. J. Reid, J. E. Goldston

Mira variables change visual light by up to 8 magnitudes over their roughly yearly cycle. Here we present a simple explanation for the extremely large amplitudes of light curves of oxygen-rich Mira variables. Metallic oxides, such as TiO, form throughout the stellar atmosphere as the star cools when approaching minimum light. When this happens, the visual li

Satoko Itaya, Tatsuya Uezu

We study a dynamical system model of an idiotypic immune network with a small number of degrees of freedom, mainly focusing on the effect of a threshold above which antibodies can recognise antibodies. The response of the system to invasions by antigens is investigated in the both models with and without the threshold and it turns out that the system changes

R. B. Nevzorov, M. A. Trusov

A theoretical analysis of solutions of renormalisation group equations in the MSSM corresponding to the quasi-fixed point conditions shows that the mass of the lightest Higgs boson in this case does not exceed $94\pm 5\text{GeV}$. It means that a substantial part of the parameter space of the MSSM is practically excluded by existing experimental data from LE

R. J. Finkelstein

We have examined the deformation of a generic non-Abelian gauge theory obtained by replacing its Lie group by the corresponding quantum group. This deformed gauge theory has more degrees of freedom than the theory from which it is derived. By going over from point particles in the standard theory to solitonic particles in the deformed theory, it is proposed

Astrid an Huef, Iain Raeburn, Dana P. Williams

We consider a class of proper actions of locally compact groups on imprimitivity bimodules over C*-algebras which behave like the proper actions on C*-algebras introduced by Rieffel in 1988. We prove that every such action gives rise to a Morita equivalence between a crossed product and a generalized fixed-point algebra, and in doing so make several innovati

Ashok Muthukrishnan, C. R. Stroud

We propose a wave packet basis for storing and processing several qubits of quantum information in a single multilevel atom. Using radially localized wave packet states in the Rydberg atom, we construct an orthogonal basis that is related to the usual energy level basis by a quantum Fourier transform. A transform-limited laser pulse that is short compared wi

Andrzej Krasinski, Charles Hellaby

Structure formation within the Lemaitre-Tolman model is investigated in a general manner. We seek models such that the initial density perturbation within a homogeneous background has a smaller mass than the structure into which it will develop, and the perturbation then accretes more mass during evolution. This is a generalisation of the approach taken by B

G. Ghisellini, A. Celotti

In the radio - host galaxy optical luminosity plane FR I and FR II radio-galaxies are clearly divided. Since the optical luminosity of an elliptical galaxy is an indication of the mass of its central black hole, we propose that the FR I - FR II dividing luminosity is a function of the mass of the black hole powering the active nucleus. Furthermore, as the ra

B. G. Sidharth

We argue that it is a fluctuational underpinning of the Quantum vacuum which on the one hand gives a stochastic character to the conservation laws, and on the other is required for explaining the recently observed acceleration of the universe. This also provides us with the arrow of time, in a consistent cosmology.

V. W. Hughes, M. Grosse Perdekamp, D. Kawall, W. Liu

Following a suggestion of Kostelecky et al. we have evaluated a test of CPT and Lorentz invariance from the microwave spectroscopy of muonium. Hamiltonian terms beyond the standard model violating CPT and Lorentz invariance would contribute frequency shifts $\delta\nu_{12}$ and $\delta\nu_{34}$ to $\nu_{12}$ and $\nu_{34}$, the two transitions involving muon

I. V. Moskalenko, A. W. Strong, J. F. Ormes, M. S. Potgieter

High-energy collisions of cosmic-ray nuclei with interstellar gas are believed to be the mechanism producing the majority of cosmic ray antiprotons. Due to the kinematics of the process they are created with a nonzero momentum; the characteristic spectral shape with a maximum at ~2 GeV and a sharp decrease towards lower energies makes antiprotons a unique pr

Eduardo C. Marino, Marcello B. Silva Neto

We propose a model for high-T$_{c}$ superconductors, valid for $0\leq\delta\leq\delta_{SC}$, that includes both the spin fluctuations of the Cu$^{++}$ magnetic ions and of the O$^{--}$ doped holes. Spin-charge separation is taken into account with the charge of the doped holes being associated to quantum skyrmion excitations (holons) of the Cu$^{++}$ spin ba

Miklos Gyulassy

In these lectures aspects of current theory used to interpret the preliminary data on ultra-relativistic nuclear collisions at RHIC energies in terms of the physical properties of QCD matter at extreme densities are introduced. Topics include: What are the physics questions at SPS and RHIC?, Geometrical vs Dynamical features of A+A, The interplay of computab

Kari Enqvist, Esko Keski-Vakkuri, Syksy Rasanen

We study brane matter in the ekpyrotic scenario and observe that in order to obtain standard gravity on the visible brane, the tension of the visible brane should be positive. If the sizes of both the fifth dimension and the Calabi-Yau threefold are fixed, the Israel junction conditions do not allow time-dependent brane matter. Relaxing this constraint, it i

M. Avenier, C. Broggini, J. Busto, C. Cerna

We report on the performance of a 1 m$^{3}$ TPC filled with CF$_{4}$ at 3 bar, immersed in liquid scintillator and viewed by photomultipliers. Particle detection, event identification and localization achieved by measuring both the current signal and the scintillation light are presented. Particular features of $\alpha$ particle detection are also discussed.

Philip Kaaret

Six x-ray point sources, with luminosities of $4 \times 10^{38} - 2 \times 10^{39} \rm ergs s^{-1}$ in the 0.4--7 keV band, were detected in Chandra observations of the spiral galaxy M100. One source is identified with supernova SN 1979C and appears to have roughly constant x-ray flux for the period 16--20 years after the outburst. The x-ray spectrum is soft

R. Torre, A. Taschin, M. Sampoli

The dynamics of the fragile glass-forming o-ter-phenyl is investigated by time-resolved transient grating experiment with an heterodyne detection technique in a wide temperature range. We investigated the dynamics processes of this glass-former over more then 6 decades in time with an excellent signal/noise. Acoustic, structural and thermal relaxations have

Lori M. Lubin, Allan Sandage

We review a sample of the early literature in which the reality of the expansion is discussed, explain Hubble's reticence to accept the expansion as real, and contrast the Tolman surface brightness test with three other modern tests. We search for the Tolman surface brightness depression with redshift using the Hubble Space Telescope (HST) data from Paper II

W Krolikowski

Although the hypothetic sterile neutrino $\nu_s$ is probably not involved significantly in the deficits of solar $\nu_e$'s and atmospheric $\nu_\mu$'s, it may cause the possible LSND effect. In fact, we face such a situation, when the popular nearly bimaximal texture of active neutrinos $\nu_e$, $\nu_\mu$, $\nu_\tau$ is perturbed through a small rotation in

G. T. Birk, A. R. Crusius--Waetzel, H. Lesch

Extremely flat and inverted radio spectra as observed in galactic nuclei and BL Lac sources are still a challenge for fast particle acceleration models. Continuous acceleration by electric fields in reconnection regions can result in almost constant particle distributions and thereby in inverted synchrotron spectra independent from the details of the injecte

V. A. Karmanov

We show that the anomalous quark magnetic moments and relativistic effects in the nucleon wave function result in the correct value of the neutron charge radius.

Raul O. Vallejos, Caio H. Lewenkopf

The standard semiclassical calculation of transmission correlation functions for chaotic systems is severely influenced by unitarity problems. We show that unitarity alone imposes a set of relationships between cross sections correlation functions which go beyond the diagonal approximation. When these relationships are properly used to supplement the semicla

Lori M. Lubin, Allan Sandage

Photometric data for 34 early-type galaxies in the three high-redshift clusters Cl 1324+3011 (z = 0.76), Cl 1604+4304 (z = 0.90), and Cl 1604+4321 (z = 0.92), observed with the Hubble Space Telescope (HST) and with the Keck 10-meter telescopes by Oke, Postman & Lubin, are analyzed to obtain the photometric parameters of mean surface brightness, magnitudes fo

M. Köhl, M. J. Davis, C. W. Gardiner, T. W. Hänsch

We report on a quantitative study of the growth process of $^{87}$Rb Bose-Einstein condensates. By continuous evaporative cooling we directly control the thermal cloud from which the condensate grows. We compare the experimental data with the results of a theoretical model based on quantum kinetic theory. We find quantitative agreement with theory for the si

R. H. M. Smit, C. Untiedt, A. I. Yanson, J. M. van Ruitenbeek

During the fracture of nanocontacts gold spontaneously forms freely suspended chains of atoms, which is not observed for the iso-electronic noble metals Ag and Cu. Au also differs from Ag and Cu in forming reconstructions at its low-index surfaces. Using mechanically controllable break junctions we show that all the 5d metals that show similar reconstruction

Raul O. Vallejos, Caio H. Lewenkopf, Yuval Gefen

We study the orthogonality catastrophe due to a parametric change of the single-particle (mean field) Hamiltonian of an ergodic system. The Hamiltonian is modeled by a suitable random matrix ensemble. We show that the overlap between the original and the parametrically modified many-body ground states, $S$, taken as Slater determinants, decreases like $n^{-k

Pedro Bicudo, Manuel Faria, Gonçalo Marques, J. Emilio Ribeiro

A general expression for the $\pi -N$ and $\pi-\Delta $ scattering lengths is derived in the framework of a microscopic calculation. Annihilation, negative energy wave-functions and spontaneous chiral symmetry are included consistently. The point-like limit is used to calculate the scattering lengths.

G. Siemieniec-Ozieblo, A. Woszczyna

The transition from acoustic noise in the radiation-dominated universe to the density structures in the matter dominated epoch is considered. The initial state is a stochastic field of sound waves moving in different directions. The construction of the initial state is compatible with the hyperbolic type of propagation equation for density perturbations, and

Marcelo Laca, Nadia S. Larsen

We consider group-subgroup pairs in which the group is a semidirect product and the subgroup is contained in the normal part. We give conditions for the pair to be a Hecke pair and we show that the enveloping Hecke algebra and Hecke C*-algebra are canonically isomorphic to semigroup crossed products, generalizing earlier results of Arledge, Laca and Raeburn

Nantel Bergeron, Mike Zabrocki

We introduce two families of non-commutative symmetric functions that have analogous properties to the Hall-Littlewood and Macdonald symmetric functions.

Christian Maes, Frank Redig, Michel Verschuere

The Gallavotti-Cohen fluctuation theorem suggests a general symmetry in the fluctuations of the entropy production, a basic concept in the theory of irreversible processes, based on results in the theory of strongly chaotic maps. We study this symmetry for some standard models of nonequilibrium steady states. We give a general strategy to derive a 'local' fl

Rudiger Schopper, Guido T. Birk, Harald Lesch

Magnetic Reconnection is an efficient and fast acceleration mechanism by means of direct electric field acceleration parallel to the magnetic field. Thus, acceleration of particles in reconnection regions is a very important topic in plasma astrophysics. This paper shows that the conventional analytical models and numerical test particle investigations can b

S. Jordan, P. Schmelcher, W. Becken

In only three of the 61 known magnetic white dwarfs helium has been identified unambiguously while about 20% of all non-magnetic stars of this class are known to contain HeI or HeII. Until recently, data for HeI data were available only for magnetic fields below 20MG. This changed with the publication of extensive data by the group in Heidelberg. The corresp

A. Raouf Chouikha

A. Derdzinki [D] gave examples of Riemannian metrics with harmonic curvature and non parallel Ricci tensor on some compact manifolds $(M,g]$ . We examine their existence as well as their number wich naturally depends on the geometry of the manifolds.

J. J. Halliwell, J. Thorwart

The Klein-Gordon equation is a useful test arena for quantum cosmological models described by the Wheeler-DeWitt equation. We use the decoherent histories approach to quantum theory to obtain the probability that a free relativistic particle crosses a section of spacelike surface. The decoherence functional is constructed using path integral methods with ini

S. Schwieger, W. Nolting

We investigate the influence of s-d or p-d hybridization to d-band ferromagnetism to estimate the importance of hybridization for the magnetic properties of transition metals. To focus our attention to the interplay between hybridization and correlation we investigate a simple model system consisting of two non-degenerated hybridized bands, one strongly corr

R. Arlt, A. Brandenburg

The possibility of non-helical large scale dynamo action is investigated using three-dimensional simulations of global accretion discs as well as idealized local simulations without rotation and only shear. Particular emphasis is placed on a certain correlation between vorticity and azimuthal velocity gradient which has been predicted to drive large scale dy

Yuri L. Dokshitzer

Perturbative QCD predicts and describes various features of multihadron production. An amazing similarity between observable hadron systems and calculable underlying parton ensembles justifies the attempts to use the language of quarks and gluons down to small momentum scales, to approach the profound problems that are commonly viewed as being entirely non-p

Pierre Sens, Hervé Isambert

The influence of an electric field on a poorly conductive membrane such as a lipid bilayer is studied theoretically. The unbalanced electric stress created by an ionic current across a non-perfectly flat membrane gives rise to a destabilizing surface energy enhancing undulations. The deformation of a membrane attached to a frame and the subsequent force on t

Raphael Exartier, Leticia F. Cugliandolo

We study numerically the time evolution of the transport properties of layered superconductors after different preparations. We show that, in accordance with recent experiments in BSCCO performed in the second peak region of the phase diagram (Portier et al, 2001), the relaxation strongly depends on the initial conditions and is extremely slow. We investigat

N. Lehner, A. W. Fullerton, K. R. Sembach, D. L. Massa

A primary goal of the FUSE mission is to understand the origin of the O VI ion in the interstellar medium of the Galaxy and the Magellanic Clouds. Along sightlines to OB-type stars, these interstellar components are usually blended with O VI stellar wind profiles, which frequently vary in shape. In order to assess the effects of this time-dependent blending