September 2001 arXiv papers — page 10

G. J. Gounaris, E. A. Paschos, P. I. Porfyriadis

We calculate the ionization cross sections for H, He or Ne atoms using $ν_e$ and $\bar ν_e$ scattering at keV energies. Such cross sections are useful for e.g. $\bar ν_e$-oscillation experiments using a tritium source. Using realistic atomic wave functions, we find that for $E_ν\lsim 10 ~\rm keV $ the atomic ionization cross sections, normalized to one elect

J. S. Sanders, A. C. Fabian

We present Chandra data from a 31.7 ks observation of the Centaurus cluster, using the ACIS-S detector. Images of the X-ray emission show a plume-like feature at the centre of the cluster, of extent 60 arcsec (20 kpc in projection). The feature has the same metallicity as gas at a similar radius, but is cooler. Using adaptive binning, we generate temperature

Ting-Wai Chiu, Tung-Han Hsieh

A recent proposal suggests that even if a Ginsparg-Wilson lattice Dirac operator does not possess any topological zero modes in topologically-nontrivial gauge backgrounds, it can reproduce correct axial anomaly for sufficiently smooth gauge configurations, provided that it is exponentially-local, doublers-free, and has correct continuum behavior. In this pap

Y. M. Cho

We show that the Skyrme theory actually is a theory of monopoles which allows a new type of solitons, the topological knots made of monopole-anti-monopole pair,which is different from the well-known skyrmions. Furthermore, we derive a generalized Skyrme action from the Yang-Mills action of QCD, which we propose to be an effective action of QCD in the infra-r

J. G. Kirk, Y. Lyubarsky

The spin-down power of a pulsar is thought to be carried away in an MHD wind in which, at least close to the star, the energy transport is dominated by Poynting flux. The pulsar drives a low-frequency wave in this wind, consisting of stripes of toroidal magnetic field of alternating polarity, propagating in a region around the equatorial plane. The current i

G. M. Cicuta, L. Molinari, G. Vernizzi

Two results are presented for reduced Yang-Mills integrals with different symmetry groups and dimensions: the first is a compact integral representation in terms of the relevant variables of the integral, the second is a method to analytically evaluate the integrals in cases of low order. This is exhibited by evaluating a Yang-Mills integral over real symmet

Ivone F. M. Albuquerque, Jodi Lamoureux, George F. Smoot

Spectacular processes in astrophysical sites produce high-energy cosmic rays which are further accelerated by Fermi-shocks into a power-law spectrum. These, in passing through radiation fields and matter, produce neutrinos. Neutrino telescopes are designed with large detection volumes to observe such astrophysical sources. A large volume is necessary because

Masao Jinzenji, Toru Sasaki

We derive the partition function of {\cal N}=4 supersymmetric Yang-Mills theory on orbifold-T^4/{\bf Z}_2 for gauge group SU(N). We generalize the method of our previous work for the SU(2) case to the SU(N) case. The resulting partition function is represented as the sum of the product of G\"ottche formula of singular quotient space $T^4/{\bf Z}_2 $ and of b

Bruce A. Bassett, Marco Peloso, Lorenzo Sorbo, Shinji Tsujikawa

We study gravitational creation of light fermions in the presence of classical scalar metric perturbations about a flat Friedmann-Lemaitre- Robertson-Walker (FLRW) background. These perturbations can be large during preheating, breaking the conformal flatness of the background spacetime. We compute numerically the total number of particles generated by the m

Jaehyun Kim, Yongwook Cheong, Jae-Seung Lee, Soonchil Lee

We present a scheme to store unitary operators with self-inverse generators in quantum states and a general circuit to retrieve them with definite success probability. The continuous variable of the operator is stored in a single-qubit state and the information about the kind of the operator is stored in classical states with finite dimension. The probabilit

H. C. Rosu, J. Torres

The Riccati equation for the Hubble parameter H of barotropic FRW cosmologies in conformal time for κ\neq 0 spatial geometries and in comoving time for the κ=0 geometry, respectively, is generalized to odd Grassmannian time parameters. We obtain a system of simple differential equations for the four supercomponents (two of even type and two of odd type) of t

A. A. Methot, Kai Wicker

In this paper, we propose a new direction of research for the realization of the quantum controlled-not gate based on a technique called ``interaction-free measurement'', where qubits are two-level atoms (or ions) and information is mediated from one qubit to another by lasers in superpositions of $π$ and $2π$ pulses. We investigate the advantages an

Felix M Lev

We consider a version of Shor's quantum factoring algorithm such that the quantum Fourier transform is replaced by an extremely simple one where decomposition coefficients take only the values of $1,i,-1,-i$. In numerous calculations which have been carried out so far, our algorithm has been surprisingly stable and never failed. There are numerical indic

Christoph Simon, Julia Kempe

How common is large-scale entanglement in nature? As a first step towards addressing this question, we study the robustness of multi-party entanglement under local decoherence, modeled by partially depolarizing channels acting independently on each subsystem. Surprisingly, we find that n-qubit GHZ entanglement can stand more than 55 % local depolarization in

Z. Ficek, S. Swain

We discuss the connection between quantum interference effects in optical beams and radiation fields emitted from atomic systems. We illustrate this connection by a study of the first- and second-order correlation functions of optical fields and atomic dipole moments. We explore the role of correlations between the emitting systems and present examples of pr

AAsa Ericsson

A geometrical picture of separability of 2 x 2 composite quantum systems, showing the region of separable density matrices in the space of hermitian matrices, is given. It rests on the criterion of separability given by Peres, and it is an extension of the ``Horodecki diagram'' and the ``stella octangula'' described by Aravind.

K. Ch. Chatzisavvas, C. Daskaloyannis, C. P. Panos

An implementation method of a gate in a quantum computer is studied in terms of a finite number of steps evolving in time according to a finite number of basic Hamiltonians, which are controlled by on-off switches. As a working example, the case of a particular implementation of the two qubit computer employing a simple system of two coupled Josephson juncti

T. C. Ralph

We discuss a quantum key distribution scheme in which small phase and amplitude modulations of quantum limited, CW light beams carry the key information. We identify universal constraints on the level of shared information between the intended receiver (Bob) and any eavesdropper (Eve) and use this to make a general evaluation of the security and efficiency o

Ch. Renner, J. Peinke, R. Friedrich, O. Chanal

The proposed universality of small scale turbulence is investigated for a set of measurements in a cryogenic free jet with a variation of the Reynolds number (Re) from 8500 to 10^6. The traditional analysis of the statistics of velocity increments by means of structure functions or probability density functions is replaced by a new method which is based on t

Alexey K. Mazur, Dimitri E. Kamashev

The macroscopic curvature of double helical DNA induced by regularly repeated adenine tracts is well-known but still puzzling. Its physical origin remains controversial even though it is perhaps the best-documented sequence modulation of DNA structure. We report here the results of comparative theoretical and experimental studies of bending dynamics in 35-me

M. Kleine Berkenbusch, W. Bauer, K. Dillman, S. Pratt

A percolation model of nuclear fragmentation is used to interpret 10.2 GeV/c p+197Au multi-fragmentation data. Emphasis is put on finding signatures of a continuous nuclear matter phase transition in finite nuclear systems. Based on model calculations, corrections accounting for physical constraints of the fragment detection and sequential decay processes ar

M. Grasso, F. Catara

A limitation common to all extensions of random-phase approximation including only particle-hole configurations is that they violate to some extent the energy weighted sum rules. Considering one such extension, the improved RPA (IRPA), already used to study the electronic properties of metallic clusters, we show how it can be generalized in order to eliminat

J. Robert Buchler, Zoltan Kollath

La plupart des etoiles variables qui pulsent avec grande amplitude, telles les cepheides, ont un comportement tres regulier et periodique. Mais juste a cote d'elles dans le diagramme Hertzsprung-Russell, se trouve un groupe d'etoiles variables dotees de courbes de lumiere tres irregulieres. A l'aide d'une technique de reconstruction de flot a

Michael G. Brown, John A. Colosi, Steven Tomsovic, Anatoly Virovlyansky

Recent results relating to ray dynamics in ocean acoustics are reviewed. Attention is focussed on long-range propagation in deep ocean environments. For this class of problems, the ray equations may be simplified by making use of a one-way formulation in which the range variable appears as the independent (time-like) variable. Topics discussed include integr

I. P. Marino, E. Allaria, R. Meucci, S. Boccaletti

In this work we describe a simple method of encoding information at real time in the inter-spike intervals of a homoclinic chaotic system. This has been experimentally tested by means of an instantaneous synchronization between the laser intensity of a CO2 laser with feedback in the regime of Sil'nikov chaos and an external pulsed signal of very low powe

Rainer E. Zimmermann, Anna Soci, Giorgio Colacchio

The conceptual background for a detailed study of the urban form of the city of Bologna is discussed with a view to modern methodological insight as it is being presented by recent results of complexity theory and the theory of self-organized criticality. The basic idea is to visualize the city of Bologna as an example of a massively parallely organized and

Bertrand Eynard

It is known that orthogonal polynomials obey a 3 terms recursion relation, as well as a 2x2 differential system. Here, we give an explicit and concise expression of the differential system in terms of the recursion coefficients. This result is a generalization of an expression of Fokas, Its and Kitaev for the symmetric case.

Ikuo S. Sogami, Kouzou Koizumi

A wide class of q-deformed harmonic oscillators including those of Macfarlane type and of Dubna type is shown to be describable in a unified way. The Hamiltonian of the oscillator is assumed to be given by a q-deformed anti-commutator of the q-deformed ladder operators. By solving $q$-difference equations, explicit coordinate representations of ladder operat

J. Daniel Christensen

An important example of a model category is the category of unbounded chain complexes of R-modules, which has as its homotopy category the derived category of the ring R. This example shows that traditional homological algebra is encompassed by Quillen's homotopical algebra. The goal of this paper is to show that more general forms of homological algebra

Viktor L. Ginzburg, Basak Z. Gurel

We outline the construction of a proper C^2-smooth function on R^4 such that its Hamiltonian flow has no periodic orbits on at least one regular level set. This result can be viewed as a C^2-smooth counterexample to the Hamiltonian Seifert conjecture in dimension four.

Dan Avritzer, Herbert Lange

We study the moduli space M_D of Desargues configurations and how to define a holomorphic map from M_D to M^b_6 the moduli space of stable binary forms of degree 6. The construction of the map goes back to the greek mathematician C. Stephanos who published a paper about this in 1883, using classical geometric invariant theory. We put this in a contemporary c

Tolga Etgu

We consider product 4--manifolds S^1 X M, where M is a closed, connected and oriented 3-manifold. We prove that if S^1 X M admits a complex structure or a Lefschetz or Seifert fibration, then the following statement is true: S^1 X M admits a symplectic structure if and only if M fibers over S^1, under the additional assumption that M has no fake 3-cells. We

Jean-Christophe Aval, Nantel Bergeron

We investigate the quotient ring $R$ of the ring of formal power series $\Q[[x_1,x_2,...]]$ over the closure of the ideal generated by non-constant quasi-\break symmetric functions. We show that a Hilbert basis of the quotient is naturally indexed by Catalan paths (infinite Dyck paths). We also give a filtration of ideals related to Catalan paths from $(0,0)

Bitjong Ndombol, Jean-Claude Thomas

Let $X$ be a simply connected space and ${\Bbb F}_p$ be a prime field. The algebra of normalized singular cochains $N^*(X; {\Bbb F}_p)$ admits a natural homotopy structure which induces natural Steenrod operations on the Hochschild homology $HH_* N^*(X;{\Bbb F}_p)$ of the space $X$. The primary purpose of this paper is to prove that the J. Jones isomorphism

Bitjong Ndombol, Jean-Claude Thomas

Let $X$ be a simply connected space and $\Bbb K$ be any field. The normalized singular cochains $N^*(X; {\Bbb K})$ admit a natural strongly homotopy commutative algebra structure, which induces a natural product on the Hochschild homology $HH_* N^*X$ of the space $X$. We prove that, endowed with this product, $HH_*N^*X$ is isomorphic to the cohomology algebr

Florian Pop

How does the first order language of fields encode birational invariants of varieties?... This question is related to rational points on varieties and effectiveness in algebraic/arithmetic geometry.

J. Martin, L. Mora

Here we show that for a C^2 surface diffeomorphism that satisfy the hypothesis of Hayashi connecting lemma either can be approximated, in the C^1 topology, by a diffeomorphism exhibiting a homoclinic tangency or the diffeomorphism already presented transversal homoclinic orbits.

Teresa Bates, Jeong Hee Hong, Iain Raeburn, Wojciech Szymanski

We classify the gauge-invariant ideals in the C*-algebras of infinite directed graphs, and describe the quotients as graph algebras. We then use these results to identify the gauge-invariant primitive ideals in terms of the structural properties of the graph, and describe the K-theory of the C*-algebras of arbitrary infinite graphs.

A. Kuniba, M. Okado, J. Suzuki, Y. Yamada

We introduce a factorized difference operator L(u) annihilated by the Frenkel-Reshetikhin screening operator for the quantum affine algebra U_q(C^{(1)}_n). We identify the coefficients of L(u) with the fundamental q-characters, and establish a number of formulas for their higher analogues. They include Jacobi-Trudi and Weyl type formulas, canceling tableau s

Jae Choon Cha, Ki Hyoung Ko

The theory of signature invariants of links in rational homology spheres is applied to covering links of homology boundary links. From patterns and Seifert matrices of homology boundary links, an explicit formula is derived to compute signature invariants of their covering links. Using the formula, we produce fused boundary links that are positive mutants of

Jae Choon Cha, Ki Hyoung Ko

A theory of signatures for odd-dimensional links in rational homology spheres is studied via their generalized Seifert surfaces. The jump functions of signatures are shown invariant under appropriately generalized concordance and a special care is given to accommodate 1-dimensional links with mutual linking. Furthermore our concordance theory of links in rat

Anton Deitmar

We give an asymptotic formula for class numbers of orders in cubic number fields.

Arkadii A. Popov

An analytical approximation of $<T_{μν}>$ for a quantized scalar field in a static spherically symmetric spacetime with a topology $S^2 \times R^2$ is obtained. The gravitational background is assumed slowly varying. The scalar field is assumed to be both massive and massless, with an arbitrary coupling $ξ$ to the scalar curvature and in a zero temperature v

H. Skarke

We analyze D-brane states and their central charges on the resolution of C^2/Z_n by using local mirror symmetry. There is a point in the moduli space where all n(n-1)/2 branches of the principal component of the discriminant locus coincide. We argue that this is the point where compactifications of Type IIA theory on a K3 manifold containing such a local geo

Leonardo Castellani, Chiara Pagani

Discrete versions of the Yang-Mills and Einstein actions are proposed for any finite group. These actions are invariant respectively under local gauge transformations, and under the analogues of Lorentz and general coordinate transformations. The case Z_n \times Z_n \times...\times Z_n is treated in some detail, recovering the Wilson action for Yang-Mills th

R. Haeussling

We analyse in detail the quantization of a simple noncommutative model of spontaneous symmetry breaking in zero dimensions taking into account the noncommutative setting seriously. The connection to the counting argument of Feyman diagrams of the corresponding theory in four dimensions is worked out explicitly. Special emphasis is put on the motivation as we

C. Sochichiu

We consider interaction of two lumps corresponding to 0-branes in noncommutative gauge theory

C. Sochichiu

We consider the dynamics of two interacting lumps/solitons in a noncommutative gauge model. We show that equations of motion describing this dynamics can be reduced to ones of a two-dimensional mechanical system which is well studied and was shown to exhibit stochastic behaviour.

Kazuo Fujikawa, Masato Ishibashi

A lattice regularization of the supersymmetric Wess-Zumino model is studied by using Ginsparg-Wilson operators. We recognize a certain conflict between the lattice chiral symmetry and the Majorana condition for Yukawa couplings, or in Weyl representation a conflict between the lattice chiral symmetry and Yukawa couplings. This conflict is also related, thoug

Oleg Lunin, Samir D. Mathur

Near-extremal black holes are obtained by exciting the Ramond sector of the D1-D5 CFT, where the ground state is highly degenerate. We find that the dual geometries for these ground states have throats that end in a way that is characterized by the CFT state. Below the black hole threshold we find a detailed agreement between propagation in the throat and ex

Angel M. Uranga

We consider the construction of fluxbranes in certain curved geometries, generalizing the familiar construction of the Melvin fluxtube as a quotient of flat space. The resulting configurations correspond to fluxbranes wrapped on cycles in curved spaces. The non-trivial transverse geometry leads in some instances to solutions with asymptotically constant dila

Martin J. Savage

I present one-loop level calculations of the Isgur-Wise functions for B -> D^{(*)} + e + nu, of the matrix elements of isovector twist-2 operators in B and D mesons, and the matrix elements for the radiative decays D^* -> D + gamma in partially quenched heavy quark chiral perturbation theory. Such expressions are required in order to extrapolate from the lig

M. Stratmann, W. Vogelsang

We present and use a technique for implementing in a fast way, and without any approximations, higher-order calculations of partonic cross sections into global analyses of parton distribution functions. The approach, which is set up in Mellin-moment space, is particularly suited for analyses of future data from polarized proton-proton collisions at RHIC, but

F. S. Navarra, M. Nielsen, M. E. Bracco

The $D^*Dπ$ form factor is evaluated in a QCD sum rule calculation for both $D$ and $π$ off-shell mesons. We study the Borel sum rule for the three-point function of one pseudoscalar, one axial and one vector meson currents. We find that the momentum dependence of the form factors is very different if the $D$ or the $π$ meson is off-shell, but they lead to t

S. F. Tuan

I review possible resolution of the $J/ψ(ψ^{\prime}) \to ρ-π$ puzzle based on two inputs: the relative phase between the one- photon and the gluonic decay amplitudes, and a possible hadronic excess in the inclusive nonelectromagnetic decay rate of $ψ^{\prime}$. The status of a universal large phase here is examined for its meaning and implications (including

J. C. Anjos, J. Magnin, G. Herrera

We study $Λ_c^\pm$ production in $pN$ and $π^-N$ interactions. Recent experimental data from the SELEX and E791 Collaborations at FNAL provide important information on the production mechanism of charm hadrons. In particular, the production of the $Λ_c$ baryon provides a good test of the intrinsic charm and the recombination mechanisms, which have been propo

M. Kachelriess, M. Plumacher

We consider the high-energy behaviour of processes involving Kaluza-Klein (KK) gravitons of weak-scale string theories. We discuss how form-factors derived within string theory modify the couplings of KK gravitons and thereby lead to an exponential fall-off of cross sections in the high-energy limit. Further, we point out that the assumption of Regge behavio

C. Bloechinger, H. Fraas, T. Mayer

We investigate pair production of selectrons in electron-electron-scattering with subsequent decay into an electron and the LSP including ISR and beamstrahlung. This process can be used at a linear collider to measure the selectron masses and the gaugino mass parameter M_1 very precisely.

Thomas G. Rizzo

We explore the capability of the LHC to distinguish the production of Kaluza-Klein(KK) excitations in Drell-Yan collisions from an ordinary $Z&#39;$ at the LHC in the case of one extra dimension with the fermions localized at the orbifold fixed points. In particular, we demonstrate that this capability is dependent on both the mass of the KK state as well as

Guido Altarelli, Richard D. Ball, Stefano Forte

We discuss the inclusion of running coupling effects in perturbative small x evolution equations. We show that a running coupling BFKL-like x-evolution equation is fully compatible, up to higher twist corrections, with the standard factorized perturbative evolution of parton distributions. We then use this result, combined with the well-known Airy asymptotic

B. N. Kalinkin, Yu. F. Gagarin

The effect of alignment of secondary particles (products of hadron interactions at superhigh energies $E^\mathrm{in}\geq5\cdot10^{6}$ GeV) as a &#34;fan&#34;, which has been observed in cosmic rays, is analysed. It is shown that its main specific features are well described within the model that we proposed twenty years ago to explain sharp anomalies in the

George Triantaphyllou

Is it a mere accident that the weak scale is exactly so much smaller than the Planck scale, and at the same time exactly so much larger than the QCD scale? Or are the experimentally-measured values of the corresponding gauge couplings enough to help us determine dynamically these energy scales? And if nature has indeed offered us the possibility of such a de

Santo Fortunato, Helmut Satz

Many features of spin models can be interpreted in geometrical terms by means of the properties of well defined clusters of spins. In case of spontaneous symmetry breaking, the phase transition of models like the q-state Potts model, O(n), etc., can be equivalently described as a percolation transition of clusters. We study here the behaviour of such cluster

Frithjof Karsch

We discuss recent results on the thermodynamics of QCD in the presence of light dynamical quark degrees of freedom. In particular, we concentrate on an analysis of the flavour and quark mass dependence of the QCD phase diagram, the equation of state and the transition temperature. Moreover, we present recent results on the heavy quark free energy.

Borexino Collaboration, C. Arpesella

The techniques researched, developed and applied towards the measurement of radioisotope concentrations at ultra-low levels in the real-time solar neutrino experiment BOREXINO at Gran Sasso are presented and illustrated with specific results of widespread interest. We report the use of low-level germanium gamma spectrometry, low-level miniaturized gas propor

I. Redondo

Measurements of charmed particle cross sections at HERA in the photoproduction and deep inelastic regimes are reviewed. The status of the comparison with perturbative QCD calculations is discussed.

D. R. M. Crooks, P. Sneddon, G. Cagnoli, J. Hough

Interferometric gravitational wave detectors use mirrors whose substrates are formed from materials of low intrinsic mechanical dissipation. The two most likely choices for the test masses in future advanced detectors are fused silica or sapphire. These test masses must be coated to form mirrors, highly reflecting at 1064nm. We have measured the excess mecha

Jacques L. Rubin

We show in the framework of Pfaff systems theory, the functional dependences of the general analytic solutions of a suitable system of involutive differential equations describing the differences between the analytic solutions of the conformal and &#34;Poincaré&#34; Lie equations. Then we ascribe to the infinitesimal variations of the parametrizing functiona

B. J. Srikanta, Jayant Haritsa, Udaysankar Sen

We have recently built a database system called BODHI, intended to store plant bio-diversity information. It is based on an object-oriented modeling approach and is developed completely around public-domain software. The unique feature of BODHI is that it seamlessly integrates diverse types of data, including taxonomic characteristics, spatial distributions,

John Constable, Hideaki Aoyama

The mathematical distinction between prose and verse may be detected in writings that are not apparently lineated, for example in T. S. Eliot&#39;s &#34;Burnt Norton&#34;, and Jim Crace&#39;s &#34;Quarantine&#34;. In this paper we offer comments on appropriate statistical methods for such work, and also on the nature of formal innovation in these two texts.

Barbara A. Cherry

Successful achievement of public policies requires satisfaction of conditions affecting political feasibility for policy adoption and maintenance as well as economic viability of the desired activity or enterprise. This paper discusses the difficulties of satisfying these joint constraints given the legacy of the common law doctrines of &#34;just price&#34;

Mark A. Lemley

Standard-setting organizations (SSOs) regularly encounter situations in which one or more companies claim to own proprietary rights that cover a proposed industry standard. The industry cannot adopt the standard without the permission of the intellectual property owner (or owners). How SSOs respond to those who assert intellectual property rights is critical

Sheila M. J. Aubin, Ziming Sun, Hilary J. Eppley, Evan M. Rumberger

New Mn12 single-molecule magnets (SMM&#39;s) with the composition [Mn12O12(O2CR)16(H2O)4] were prepared and structurally characterized. Complexes of this type can exhibit two out-of-phase ac magnetic susceptibility signals, one in the 4-7 K region and the other in the 2-3 K region. The origin of the two magnetization relaxation processes was systematically e

Wei Bao, A. D. Christianson, P. G. Pagliuso, J. L. Sarrao

The magnetic structure of Ce0.9La0.1RhIn5 is measured using neutron diffraction. It is identical to the incommensurate transverse spiral for CeRhIn5, with a magnetic wave vector q_M=(1/2,1/2,0.297), a staggered moment of 0.38(2)Bohr magneton per Ce at 1.4K and a reduced Neel temperature of 2.7 K.

J. F. Wambaugh, C. Reichhardt, C. J. Olson

We consider through simulations the behavior of elongated grains on a vibrating ratchet-shaped base. We observe differences in layer velocity profile and in net grain velocity for grains that are composed of one, two, or three colinear spheres. In the case of mixtures of different species of grains, we demonstrate layer-by-layer variation in the average velo

Gabriel Tellez, Lina Merchan

We study a toy model for electrolytic soap films, the two-dimensional two-component plasma. This model is exactly solvable for a special value of the coulombic coupling constant $βq^2=2$. This allows us to compute the disjoining pressure of a film and to study its stability. We found that the Coulomb interaction plays an important role in this stability. Als

Roland Faller, Juan J. de Pablo

New hybrid Molecular Dynamics-Monte Carlo methods are proposed to increase the efficiency of constant-pressure simulations. Two variations of the isobaric Molecular Dynamics component of the algorithms are considered. In the first, we use the extended-ensemble method of Andersen [H. C. Andersen J. Chem. Phys. {\bf 72},2384 (1980)]. In the second, we arrive a

D. Bonamy, F. Daviaud, L. Laurent, M. Bonetti

We investigate steady granular surface flows in a rotating drum and demonstrate the existence of rigid clusters of grains embedded in the flowing layer. These clusters are fractal and their size is power-law distributed from the grain size scale up to the thickness of the flowing layer. The implications of the absence of a characteristic length scale on avai

B. Normand, A. P. Kampf

We show from real-space Hartree-Fock calculations within the extended Hubbard model that next-nearest neighbor (t&#39;) hopping processes act to suppress the formation of static charge stripes. This result is confirmed by investigating the evolution of charge-inhomogeneous corral and stripe phases with increasing t&#39; of both signs. We propose that large t

Antonio M. Puertas, Matthias Fuchs, Michael E. Cates

Using computer simulations, we identify the mechanisms causing aggregation and structural arrest of colloidal suspensions interacting with a short-ranged attraction at moderate and high densities. Two different non-ergodicity transitions are observed. As the density is increased, a glass transition takes place, driven by excluded volume effects. In contrast,

Francois G. Schmitt, Laurent Seuront

A 3D copepod trajectory is recorded in the laboratory, using 2 digital cameras. The copepod undergoes a very structured type of trajectory, with successive moves displaying intermittent amplitudes. We perform a statistical analysis of this 3D trajectory using statistical tools developed in the field of turbulence and anomalous diffusion. We show that the wal

T. He, John M. Rowell, R. J. Cava

The reactivity of MgB2 with powdered forms of common substrate and electronic materials is reported. Reaction temperatures between 600 C and 800 C, encompassing the range commonly employed in thin-film fabrication, were studied. The materials tested for reactivity were ZrO2, yttria stabilized zirconia (YSZ), MgO, Al2O3, SiO2, SrTiO3, TiN, TaN, AlN, Si, and S

John A. Wilson

The paper deals with the many stands that go into creating the unique and complex nature of the HTSC cuprates above Tc as below. Like its predecessors it treats charge, not spin or lattice, as prime mover, but thus taken in the context of the chemical bonding relevant to these copper oxides. The crucial shell filling, negative-U, double-loading fluctuations

Alain Mauger, Noelle Pottier

We report new results related to the two-time dynamics of the coordinate of a quantum free particle, damped through its interaction with a fractal thermal bath (non-ohmic coupling $\simω^δ$ with $0<δ<1$ or $1<δ<2)$. When the particle is localized, its position does not age. When it undergoes anomalous diffusion, only its displacement may be defined. It is sh

Jean Desbois

The spectral determinant of the Schrödinger operator ($ - Δ+ V(x) $) on a graph is computed for general boundary conditions. ($Δ$ is the Laplacian and $V(x)$ is some potential defined on the graph). Applications to restricted random walks on graphs are discussed.

M. A. N. Araujo, N. M. R. Peres, P. D. Sacramento

We study local moment formation in the presence of superconducting correlations among the f-electrons in the periodic Anderson model. Local moments form if the Coulomb interaction U>U_cr. We find that U_cr is considerably stronger in the presence of superconducting correlations than in the non-superconducting system. Our study is done for various values of t

Asimkumar Ghosh

We consider the one-dimensional Ising-like fully anisotropic S=1/2 Heisenberg antiferromagnetic Hamiltonian and study the dynamics of domain wall excitations in the presence of transverse magnetic field $h_x$. We obtain dynamical spin correlation functions along the magnetic field $S^{xx}(q,ω)$ and perpendicular to it $S^{yy}(q,ω)$. It is shown that the line

J. Singleton, N. Harrison, C. H. Mielke, J. Schlueter

Although quasi-two-dimensional organic superconductors such as $κ$-(BEDT-TTF)$_2$Cu(NCS)$_2$ seem to be very clean systems, with apparent quasiparticle mean-free paths of several thousand Å, the superconducting transition is intrinsically broad (e.g $\sim 1$ K wide for $T_c \approx 10$ K). We propose that this is due to the extreme anisotropy of these materi

N. M. R. Peres, P. D. Sacramento, M. A. N. Araujo

We study the temperature dependence of the specific heat in the periodic Anderson model as function of the on-site Coulomb interaction, hybridization, and position of the f-electrons energy level. At strong coupling (U=infinity) we use slave bosons, whereas at weak coupling we use a simple Hartree-Fock decomposition. We find that both in the strong and weak

R. Reigada, A. Sarmiento, Katja Lindenberg

The dynamics of energy relaxation in thermalized one- and two-dimensional arrays with nonlinear interactions depend in detail on the interactions and, in some cases, on dimensionality. We describe and explain these differences for arrays of the Fermi-Pasta-Ulam type. In particular, we focus on the roles of harmonic contributions to the interactions and of br

Alex Kamenev

Lecture notes presented at Windsor NATO school on &#34;Field Theory of Strongly Correlated Fermions and Bosons in Low-Dimensional Disordered Systems&#34; (August 2001). The purpose of these lectures is to give a brief modern introduction to Keldysh non-equilibrium field theory and its classical analog - Doi-Peliti technique. The special emphasis is put on st

Ying-Jer Kao, Andrew P. Iyengar, Qijin Chen, K. Levin

We study the sensitivity of T_c and T^* to low fields, H, within the pseudogap state using a BCS-based approach extended to arbitrary coupling. We find that T^* and T_c, which are of the same superconducting origin, have very different H dependences. This is due to the pseudogap, Δ_{pg}, which is present at the latter, but not former temperature. Our results

F. K. Baganoff, M. W. Bautz, W. N. Brandt, G. Chartas

Most galactic nuclei are now believed to harbour supermassive black holes. Studies of stellar motions in the central few light-years of our Milky Way Galaxy indicate the presence of a dark object with a mass of about 2.6 million solar masses. This object is spatially coincident with Sagittarius A* (Sgr A*), the unique compact radio source located at the dyna

Edward B. Jenkins, David V. Bowen, Kenneth R. Sembach, the FUSE Science Team

Spectra of about 150 early-type stars in the disk of the Milky Way recorded by the Far Ultraviolet Spectroscopic Explorer (FUSE) reveal absorption features from interstellar O VI, a tracer of collisionally ionized gases at temperatures near 300,000 K. (Hotter material is better sensed by its diffuse x-ray emission.) The FUSE survey indicates that hot gas in

Edward B. Jenkins, Todd M. Tripp

It is generally recognized that the interstellar medium has a vast range of densities and temperatures. While these two properties are usually anticorrelated with each other, there are nevertheless variations in their product, i.e., the thermal gas pressure divided by the Boltzmann constant k. In neutral gas, the relative populations of neutral carbon atoms

S. K. Leggett, D. A. Golimowski, X. Fan, T. R. Geballe

We discuss the behaviour of the JHKL&#39;M&#39; colors of L and T dwarfs, based on photometric and spectroscopic data obtained at the United Kingdom Infrared Telescope in Hawaii. We have measured the first accurate M&#39; photometry for L and T dwarfs. The K-M&#39; colors of T dwarfs are much bluer than predicted by published models, suggesting that CO may b

Nicholas E. White, Lorella Angelini

We report an observation by the Chandra X-ray Observatory of 4U2127+119, the X-ray source identified with the globular cluster M15. The Chandra observation reveals that 4U2127+119 is in fact two bright sources, separated by 2.7&#34;. One source is associated with AC211, the previously identified optical counterpart to 4U2127+119, a low mass X-ray binary (LMX

Roberto G. Abraham, Sidney van den Bergh

Many galaxies appear to have taken on their familiar appearance relatively recently. In the distant Universe, galaxy morphology started to deviate significantly (and systematically) from that of nearby galaxies at redshifts, z, as low as z = 0.3. This corresponds to a time ~3.5 Gyr in the past, which is only ~25% of the present age of the Universe. Beyond z

Daniel Wolf Savin

We have calculated the rate coefficients for D(1s) + H^+ <--> D^+ + H(1s) using recently published theoretical cross sections. We present results for temperatures T from 1 K to 2x10^5 K and provide fits to our data for use in plasma modeling. Our calculations are in good agreement with previously published rate coefficients for 25 <= T <= 300 K, which covers

R. Kurosawa, D. J. Hillier

We have developed a 3-D Monte Carlo radiative transfer model which computes line and continuum polarization variability for a binary system with an optically thick non-axisymmetric envelope. This allows us to investigate the complex (phase-locked) line and continuum polarization variability features displayed by many massive binaries: W-R+O, O+O, etc. An 8-w