July 2002 arXiv papers — page 17

Mads Brandbyge, Kurt Stokbro, Jeremy Taylor, Jose-Luis Mozos

We address the microscopic origin of the current-induced forces by analyzing results of first principles density functional calculations of atomic gold wires connected to two gold electrodes with different electrochemical potentials. We find that current induced forces are closely related to the chemical bonding, and arise from the rearrangement of bond char

J. R. Cudell, E. Martynov, G. Soyez

We analyse the consequences of t-channel unitarity for the photon hadronic cross sections. We show that gamma(*)p and gamma(*) gamma(*) elastic amplitudes must include the complex-j plane singularities associated with hadronic elastic amplitudes, and give the characteristics of possible new singularities. We also show that several different models of hadroni

CERES Collaboration

Based on an evaluation of data on pion interferometry and on particle yields at mid-rapidity, we propose a universal condition for thermal freeze-out of pions in heavy-ion collisions. We show that freeze-out occurs when the mean free path of pions lambda_f reaches a value of about 1 fm, which is much smaller than the spatial extent of the system at freeze-ou

Miodrag L. Kulic, Igor M. Kulic

The very intriguing antagonistic interplay of antiferromagnetism (AF) and superconductivity (SC), recently discovered in high-temperature superconductors, is studied in the framework of a microscopic theory. We explain the surprisingly large increase of the magnetic Bragg peak intensity $I_{Q}$ at $Q\sim (π,π)$ in the magnetic field $H\ll H_{c2}$ at low temp

Carl R. Brune

An alternative parameterization of R-matrix theory is presented which is mathematically equivalent to the standard approach, but possesses features which simplify the fitting of experimental data. In particular there are no level shifts and no boundary-condition constants which allows the positions and partial widths of an arbitrary number levels to be easil

David Garber

In this paper we investigate Uludag's method for constructing new curves whose fundamental groups are central extensions of the fundamental group of the original curve by finite cyclic groups. In the first part, we give some generalizations to his method in order to get new families of curves with controlled fundamental groups. In the second part, we dis

Gustavo Dotti

A stronger version of an anomaly matching theorem (AMT) is proven that allows to anticipate the matching of continuous as well as discrete global anomalies. The AMT shows a connection between anomaly matching and the geometry of the null cone of SYM theories. Discrete symmetries are shown to be broken at the origin of the moduli space in Seiberg-Witten theor

S. Covino, D. Lazzati, D. Malesani, G. Ghisellini

We present and discuss polarimetric observations performed with the VLT-UT3 (Melipal) on the afterglow of GRB 011211, ~35 hours after the burst onset. The observations yielded a 3-sigma upper limit of P<2.7%. We discuss this result in combination with the lightcurve evolution, that may show a break approximately at the time of our observation. We show that o

V. P. Gusynin, D. V. Khveshchenko, M. Reenders

We use the radial gauge to calculate the recently proposed ansatz for the physical electron propagator in such effective models of strongly correlated electron systems as the $QED_3$ theory of the pseudogap phase of the cuprates. The results of our analysis help to settle the recent dispute about the sign and the magnitude of the anomalous dimension which ch

Pratip Bhattacharyya, Srutarshi Pradhan, Bikas K. Chakrabarti

We study the phase transition in a class of fiber bundle models in which the fiber strengths are distributed randomly within a finite interval and global load sharing is assumed. The dynamics is expressed as recursion relations for the redistribution of the applied stress and the evolution of the surviving fraction of fibers. We show that an irreversible pha

David Karasik, Aharon Davidson

Within the framework of geodetic brane gravity, the Universe is described as a 4-dimensional extended object evolving geodetically in a higher dimensional flat background. In this paper, by introducing a new pair of canonical fields {lambda, P_{lambda}}, we derive the quadratic Hamiltonian for such a brane Universe; the inclusion of matter then resembles min

Sven Gnutzmann, Burkhard Seif, Felix von Oppen, Martin R. Zirnbauer

The classification of universality classes of random-matrix theory has recently been extended beyond the Wigner-Dyson ensembles. Several of the novel ensembles can be discussed naturally in the context of superconducting-normal hybrid systems. In this paper, we give a semiclassical interpretation of their spectral form factors for both quantum graphs and And

Elisa Di Pietro, Jean-Francois Claeskens

The possibility to unambiguously determine the equation-of-state of the cosmic dark energy with existing and future supernovae data is investigated. We consider four evolution laws for this equation-of-state corresponding to four quintessential models, i.e. i) a cosmological constant, ii) a general barotropic fluid, iii) a perfect fluid with a linear equatio

J. Lukierski, P. C. Stichel, W. J. Zakrzewski

We consider two ways of introducing minimal Abelian gauge interactions into the model presented in [1]. They are different only if the second central charge of the planar Galilei group is nonzero. One way leads to standard gauge transformations and second to a generalized gauge theory with gauge transformations accompanied by time-dependent area-preserving c

Roland J. Kay, Neil F. Johnson

The Parrondo effect describes the seemingly paradoxical situation in which two losing games can, when combined, become winning [Phys. Rev. Lett. 85, 24 (2000)]. Here we generalize this analysis to the case where both games are history-dependent, i.e. there is an intrinsic memory in the dynamics of each game. New results are presented for the cases of both ra

Jong-Phil Lee

In the framework of the factorization and the heavy quark effective theory, $B\to D_2^*π$ modes are analyzed. We adopt the result from the QCD sum rule calculation for the hadronic matrix elements at leading order of $Λ_{\rm QCD}/m_Q$ and $α_s$. The QCD sum rule results are well compatible with the current data, with the prediction on the branching ratios $\

Monica Colpi, Ira Wasserman

If core collapse leads to the formation of a rapidly rotating bar-unstable proto-neutron star surrounded by fall-back material, then we might expect it to cool and fragment to form a double (proto)-neutron star binary into a super-close orbit. The lighter star should survive for awhile, until tidal mass loss propels it toward the minimum stable mass of a (pr

Enrico Perfetto, Gianluca Stefanucci, Michele Cini

We use the Hubbard Hamiltonian $H$ on the honeycomb lattice to represent the valence bands of carbon single-wall $(N,N)$ nanotubes. A detailed symmetry analysis shows that the model allows W=0 pairs which we define as two-body singlet eigenstates of $H$ with vanishing on-site repulsion. By means of a non-perturbative canonical transformation we calculate the

Alois Würger, Andreas Fleischmann, Christian Enss

Recent experiments revealed a most surprising magnetic-field dependence of coherent echoes in amorphous solids. We show that a novel dephasing mechanism involving nuclear quadrupole moments is the origin of the observed magnetic-field dependence.

S. Biswas, I. Chowdhury

The complex time WKB approximation is an effective tool in studying particle production in curved spacetime. We use it in this work to understand the formation of classical condensate in expanding de Sitter spacetime. The CWKB leads to the emergence of thermal spectrum that depends crucially on horizons (as in de Sitter spacetime) or observer dependent horiz

Alessandro Torrielli

We discuss the breakdown of perturbative unitarity of noncommutative quantum field theories in electric-type background in the light of string theory. We consider the analytic structure of string loop two-point functions using a suitable off-shell continuation and then study the zero slope limit of Seiberg and Witten. In this way we pick up how the unphysica

M. E. Soussa, R. P. Woodard

We consider $(3+1)$-dimensional, Dirac electrons of arbitrary mass, propagating in the presence of electric and magnetic fields which are both parallel to the $x^3$ axis. The magnetic field is constant in space and time whereas the electric field depends arbitrarily upon the light-cone time parameter $x^+ = (x^0 + x^3)/\sqrt{2}$. We present an explicit solut

Xiao-Jun Wang, Seng Hu

We consider supergravity configuration of D5 branes wrapped on supersymmetric 2-cycles and use it to calculate one-point and two-point Green functions of some special operators in N=2 super Yang-Mills theory. We show that Green functions obtained from supergravity include two very different parts. One of them corresponds to perturbative results of quantum fi

A. Lima-Santos

We investigate the possible regular solutions of the boundary Yang-Baxter equation for the vertex models associated with the $A_{n-1}^{(1)}$ affine Lie algebra. We have classified them in two classes of solutions. The first class consists of $n(n-1)/2$ K-matrix solutions with three free parameters. The second class are solutions that depend on the parity of

George T. Fleming, Pavlos M. Vranas

A different lattice fermion method is introduced. Staggered domain wall fermions are defined in 2n+1 dimensions and describe 2^n flavors of light lattice fermions with exact U(1) x U(1) chiral symmetry in 2n dimensions. As the size of the extra dimension becomes large, 2^n chiral flavors with the same chiral charge are expected to be localized on each bounda

S. A. Bass, B. Mueller, D. K. Srivastava

We study the microscopic dynamics of quarks and gluons in relativistic heavy ion collisions in the framework of the Parton Cascade Model. We use lowest order perturbative QCD cross sections with fixed lower momentum cutoff p_0. We calculate the time-evolution of the Debye-screening mass for Au+Au collisions at sqrt(s)=200 GeV per nucleon pair. The screening

Giovanna Morigi, Sonja Franke-Arnold, Gian-Luca Oppo

We study a four-level atomic scheme interacting with four lasers in a closed-loop configuration with a $\diamondsuit$ (diamond) geometry. We investigate the influence of the laser phases on the steady state. We show that, depending on the phases and the decay characteristic, the system can exhibit a variety of behaviors, including population inversion and co

John Jeffers, Stephen M. Barnett, David T. Pegg

We use retrodictive quantum theory to describe cavity field measurements by successive atomic detections in the micromaser. We calculate the state of the micromaser cavity field prior to detection of sequences of atoms in either the excited or ground state, for atoms that are initially prepared in the excited state. This provides the POM elements, which desc

Valeri V. Dvoeglazov

In the talk we investigate the question of commutation of the whole-partial derivatives, which should be considered when the function, which is subjected to differentiation, has both explicit and implicit dependence. We apply the results to the quantum theories. -- En la platica investigamos la cuestion de conmutacion de derivadas parciales cuando la funcion

Nilo C. Bobillo-Ares, Carlos Dehesa-Martinez

Starting from a suggestion of Einstein on the construction of the concept of space, we elaborate an intrinsic method to obtain space and time transformations between two inertial spaces of reference, mathematically modeled as affine euclidean spaces. The principal device introduced for relating the space readings in both spaces is the so-called tracer mappin

R. Bittner, M. Wassermeier, A. Wixforth

A novel sensoric technique for the dynamical in situ investigation of a hybridization bio assay is presented, which utilizes a metal bead labeling method. Therein, hybridization results in an increased metal coverage on parts of a substrate, where it takes place. Our sensing principle relies on the measurement of the radio frequency impedance of the hybridiz

Randall D. Peters

Low-level bistability has been observed in the output from a recently developed novel magnetometer. It is not known whether this behavior is associated with the torsion fiber of the instrument or with the Earth&#39;s magnetic field. Whatever its cause, this form of complexity is not widely known.

Randall D. Peters

A magnetometer has been developed by a simple modification of the TEL-Atomic Cavendish balance designed by the author. The usual tungsten wire fiber has been replaced with a silk thread, and a rare earth magnet has been attached to the boom near where the fiber connects. Because of the mechanical common mode rejection feature of the instrument, pendulous noi

Chun-Woo Lee

The transformation introduced by Giusti-Suzor and Fano and extended by Lecomte and Ueda for the study of resonance structures in the multichannel quantum defect theory (MQDT) is used to reformulate MQDT into the forms having one-to-one correspondence with those in Fano&#39;s configuration mixing (CM) theory of resonance for the photofragmentation processes i

Franz Wegner

In a previous paper (physics/0203061) &#39;&#39;Floating bodies of equilibrium I&#39;&#39; I have shown that there exist two-dimensional non-circular cross-sections of bodies of homogeneous densities rho not equal 1/2 which can float in any orientation in water, which have a p-fold rotation axis. For given p they exist for p-2 different densities. However, t

Franz Wegner

A long cylindrical body of circular cross-section and homogeneous density may float in all orientations around the cylinder axis. It is shown that there are also bodies of non-circular cross-sections which may float in any direction. Apart from those found by Auerbach for rho=1/2 there are one-parameter families of cross-sections for rho not= 1/2 which have

Ch. Elster, A. Sibirtsev, S. Schneider, J. Haidenbauer

Very recent data for the reaction gamma{d} --> eta{np} are analyzed within a model that includes contributions from the impulse approximation and next order corrections due to the np and eta{N} interactions in the final state. Comparison between the calculations and data indicate sizable contributions from the np and eta{N} final state interactions close to

Sen Cheng, Scott Pratt

Partition functions, multiplicity distributions, and isospin fluctuations are calculated for canonical ensembles in which additive quantum numbers as well as total isospin are strictly conserved. When properly accounting for Bose-Einstein symmetrization, the multiplicity distributions of neutral pions in a pion gas are significantly broader as compared to th

R. B. Wiringa, Steven C. Pieper

We first define a series of NN interaction models ranging from very simple to fully realistic. We then present Green&#39;s function Monte Carlo calculations of light nuclei to show how nuclear spectra evolve as the nuclear forces are made increasingly sophisticated. We find that the absence of stable five- and eight-body nuclei depends crucially on the spin,

A. Capella

The probabilistic Glauber formula for nuclear absorption used in the literature is only valid at low energies and $x_+ \simeq 0$. Due to energy conservation, $σ_{abs}$ is replaced by an effective cross-section $σ_{abs} + x_+^γ$ ($σ_{c\bar{c}-N} - σ_{abs})$ which increases with $x_+$ and tends to the total $c\bar{c}-N$ cross-section $σ_{c\bar{c}-N}$. Experime

A. Motzke, Ch. Elster, C. Hanhart

The influence of three-particle breakup singularities on s-wave meson production in nucleon-nucleon collisions is studied within the distorted wave Born approximation. This study is based on a simple scalar model for the two-nucleon interaction and the production mechanism. An algorithm for the exact numerical treatment of the inherent three-body cuts, toget

J. A. Niskanen

Chiral effective field theory predicts a charge symmetry violating (CSB) amplitude for pion-nucleon scattering. This mechanism provides a very large contribution also to the CSB forward-backward asymmetry in the angular distribution of the reaction pn --> d pi0. This contribution was so large that it had a potential to cause a large effect also in CSB elasti

N. Itagaki, K. Hagino

We use a microscopic three-cluster model with the $α+α+n$ configuration to analyze with astrophysical interests the photodisintegration cross section of $^9$Be. The valence neutron in $^9$Be is treated in the molecular orbit model (MO), including continuum states by the box discretization method. It is shown that good agreement is achieved with the recently

T. Inakura, S. Mizutori, M. Yamagami, K. Matsuyanagi

With the use of the symmetry-unrestricted cranked Skyrme-Hartree-Fock method in the three-dimensional coordinate-mesh representation, we have carried out a systematic theoretical search for the superdeformed and hyperdeformed rotational bands in the mass A=30-50 region. Along the N=Z line, we have found superdeformed solutions in 32S, 36Ar, 40Ca, 44Ti, and h

Toshio Suzuki, Hiroyuki Sagawa, Kouichi Hagino

We studied firstly the ground state properties of C-isotopes using a deformed Hartree-Fock (HF)+ BCS model with Skyrme interactions. Shallow deformation minima are found in several neutron$-$rich C-isotopes. It is shown also that the deformation minima appear in both the oblate and the prolate sides in $^{17}$C and $^{19}$C having almost the same binding ene

G. Boffetta, F. De Lillo, S. Musacchio

We study the statistics of single particle Lagrangian velocity in a shell model of turbulence. We show that the small scale velocity fluctuations are intermittent, with scaling exponents connected to the Eulerian structure function scaling exponents. The observed reduced scaling range is interpreted as a manifestation of the intermediate dissipative range, a

Rainer Hempel, Olaf Post

We discuss the band-gap structure and the integrated density of states for periodic elliptic operators in the Hilbert space $L_2(\R^m)$, for $m \ge 2$. We specifically consider situations where high contrast in the coefficients leads to weak coupling between the period cells. Weak coupling of periodic systems frequently produces spectral gaps or spectral con

Sergiu Vacaru

The work extends the A. Connes&#39; noncommutative geometry to spaces with generic local anisotropy. We apply the E. Cartan&#39;s anholonomic frame approach to geometrical models and physical theories and develop the nonlinear connection formalism for projective module spaces. Examples of noncommutative generation of anholonomic Riemann, Finsler and Lagrange

C. S. Rajan

We consider the problem of recovering l-adic representations from a knowledge of the character values at the Frobenius elements associated to l-adic representations constructed algebraically out of the original representations. These results generalize earlier results in of the author concerning refinements of strong multiplicity one for $l$-adic represntati

Elliot Benjamin, Franz Lemmermeyer, Chip Snyder

In this article we classify the complex quadratic number fields k with 2-class group of type (2,2,2) whose Hilbert 2-class fields have a 2-class group of rank 2, and then determine the length of their 2-class field towers.

Franz Lemmermeyer

In this article we sketch the development of the principal genus theorem from its conception by Gauss in the case of binary quadratic forms to the cohomological formulation of the principal genus theorem of class field theory by Emmy Noether.

Boris Kalinin, Ralf Spatzier

We investigate rigidity of measurable structure for higher rank abelian algebraic actions. In particular, we show that ergodic measures for these actions fiber over a 0 entropy measure with Haar measures along the leaves. We deduce various rigidity theorems for isomorphisms and joinings as corollaries.

Shmuel Onn

We consider a problem of optimizing convex functionals over matroid bases. It is richly expressive and captures certain quadratic assignment and clustering problems. While generally NP-hard, we show it is polynomial time solvable when a suitable parameter is restricted.

Eric Babson, Shmuel Onn, Rekha Thomas

We provide a polynomial time algorithm for computing the universal Gröbner basis of any polynomial ideal having a finite set of common zeros in fixed number of variables. One ingredient of our algorithm is an effective construction of the state polyhedron of any member of the Hilbert scheme Hilb^d_n of n-long d-variate ideals, enabled by introducing the Hilb

S Addas Zanata

We prove that for a large and important class of $C^1$ twist maps of the torus periodic and quasi-periodic orbits of a new type exist, provided that there are no rotational invariant circles (R.I.C&#39;s). These orbits have a non-zero &#39;&#39;vertical rotation number&#39;&#39; (V.R.N.), in contrast to what happens to Birkhoff periodic orbits and Aubry-Math

Mihai Halic

The goal of this paper is to define families of toric varieties and to study their properties. These families are locally trivial fibrations over some base, whose fibres are isomorphic to a fixed complete toric variety. The study is motivated by the occurence of such families in the context of gauged sigma models for toric varieties.

Gerard Laumon

In their proof of the Drinfeld-Langlands correspondence, Frenkel, Gaitsgory and Vilonen make use of a geometric Fourier transformation. Therefore, they work either with l-adic sheaves in characteristic p>0, or with D-modules in characteristic 0. Actually, they only need to consider the Fourier transforms of homogeneous sheaves for which one expects a uniform

Roberto Paoletti

If a finite group acts holomorphically on a pair (X,L), where X is a complex projective manifold and L a line bundle on it, for every k the space of holomorphic global section of the k-th power of L splits equivariantly according to the irreducible representations of G. We consider the asymptotic growth of these summands, under various positivity conditions

Masanobu Kaneko, Masao Koike

Modular and quasimodular solutions of specific second order differential equation in the upper-half plane which originates from a study of supersingular j-invariants are given explicitly. A characterization of the differential equation is also discussed.

Oliver Klehn

We define local residues of holomorphic 1-forms on an isolated surface singularity that have isolated zeros and prove that a certain residue equals the index of the 1-forms.

David E. Anderson

With an explicit example, we confirm a conjecture by Neumann and Wahl that there exist cusps with no Galois cover by a complete intersection. Some computational techniques are reviewed, and a method for deciding whether a given cusp has a complete intersection Galois cover is developed.

Roberto Paoletti

In the context of almost complex quantization, a natural generalization of algebro-geometric linear series on a compact symplectic manifold has been proposed. Here we suppose given a compatible action of a finite group and consider the linear subseries associated to the irreducible representations of $G$, give conditions under which these are base-point free

Jonathan Brundan, Alexander Kleshchev

Ian Grojnowski has developed a purely algebraic way to connect the representation theory of affine Hecke algebras at an (l+1)-th root of unity to the highest weight theory of the affine Kac-Moody algebra of type A_l^(1). The present article is devoted to extending Grojnowski&#39;s machinery to the twisted case: we replace the affine Hecke algebras with the a

James M. Cline, Hassan Firouzjahi

It has been proposed that the geometry of an extra dimension could automatically adjust itself to compensate for an arbitrary energy density on the 3-D brane which we are presumed to inhabit, such that a static solution to Einstein&#39;s equation results. This would solve the long-standing cosmological constant problem, of why our universe is not overwhelmed

Stefano Arnone, Antonio Gatti, Tim R. Morris

Using a gauge invariant exact renormalization group, we show how to compute the effective action, and extract the physics, whilst manifestly preserving gauge invariance at each and every step. As an example we give an elegant computation of the one-loop SU(N) Yang-Mills beta function, for the first time at finite N without any gauge fixing or ghosts. It is a

Stefano Arnone, Antonio Gatti, Tim R. Morris

A manifestly gauge invariant exact renormalization group for pure SU(N) Yang-Mills theory is proposed, allowing gauge invariant calculations, without any gauge fixing or ghosts. The necessary gauge invariant regularisation which implements the effective cutoff, is naturally incorporated by embedding the theory into a spontaneously broken SU(N|N) super-gauge

V. A. Fateev, E. Onofri

The parametric families of integrable boundary affine Toda theories are considered. We calculate boundary one-point functions and propose boundary S-matrices in these theories. We use boundary one-point functions and S-matrix amplitudes to derive boundary ground state energies and exact solutions describing classical vacuum configurations.

Kohzo Nishida

We propose a five-dimensional standard model which regards the Higgs field as a weak boson associated with the fifth dimension. The kinetic term of the Higgs field is obtained from the fifth components of field strengths defined in five dimension. The coupling constant of the fermion fields and the Higgs field is only the weak coupling constant. However, sin

Marek Rogatko

We derive general formulae for the first order variation of the ADM mass, angular momentum for linear perturbations of a stationary background in Einstein-Maxwell axion-dilaton gravity being the low-energy limit of the heterotic string theory. All these variations were expressed in terms of the perturbed matter energy momentum tensor and the perturbed charge

Xin-zhou Li, Dao-jun Liu, Jian-gang Hao

Although the formulas of tachyon inflation correspond to those of the inflation driven by the ordinary scalar field, there is obvious difference between them, which can not be neglected. We calculate the scalar and tensor perturbation of the string theory inspired tachyon inflation, which has been widely studied recently. We also show, through the Hamilton-J

J. P. B. C. de Melo, Lauro Tomio, T. Frederico

The electromagnetic form factor is extracted from both components of the electromagnetic current: J(plus) and J(minus) with a pseudo-scalar coupling of the quarks to the kaon. In the case of J(plus) there is no pair term contribution in the Drell-Yan frame. However, J(minus) component of the electromagnetic current the pair term contribution is different fro

S. M. H. Wong

In connection with the possibility of skyrmion production from small domain disoriented chiral condensates formation from heavy ion collisions, the direct relation of a classical skyrmion to baryon states is examined. It is argued that a skyrmion is a coherent state of baryons. The collective coordinate approach of quantization means that the physical baryon

S. M. H. Wong

In the Skyrme model, the Lagrangian can be quantized in several ways using the collective coordinate approach. Not all of which produce quantum states that can be interpreted as physical particles. For example the SU(2) collective coordinate approach produces both integral and half-integral spin and isospin states. Only half of these are the physical baryons

P. Zenczykowski

The problem of weak radiative hyperon decays (WRHD) is reviewed. With the recent measurement of the $Ξ^0 \to Λγ$ asymmetry confirming Hara&#39;s theorem, implications from its violation in low-energy theoretical approaches are discussed. It is shown how an underlying symmetry link should be formulated for a successful description of both nonleptonic and radi

B. L. Ioffe

The paper presents the short review of our to-day knowledge of vacuum condensates in QCD. The condensates are defined as vacuum averages of the operators which arise due to nonperturbative effects. The important role of condensates in determination of physical properties of hadrons and of their low-energy interactions in QCD is underlined. The special value

Noboru Kawamoto, Kenji Yotsuji

We numerically investigate the fractal structure of two-dimensional quantum gravity coupled to matter central charge c for $-2 \leq c \leq 1$. We reformulate Q-state Potts model into the model which can be identified as a weighted percolation cluster model and can make continuous change of Q, which relates c, on the dynamically triangulated lattice. The c-de

A. G. Afonine, V. T. Baranov, V. M. Biryukov, V. N. Chepegin

The new results of using short (2-4mm) bent crystals for extraction and collimation of proton beam at IHEP 70 Gev proton synchrotron are reported. A broad range of energies from 6 to 65 GeV has been studied in the same crystal collimation set-up. The efficiency of extraction more than 85% and intensity more than 10E12 were obtained by using crystal with the

D. Zaborov

This document describes a Monte-Carlo simulation of an underwater neutrino telescope with a homogeneous detection volume of a cubic kilometre.

H1 Collaboration, C. Adloff

A search for excited electron e* production is described in which the electroweak decays e*->e gamma, e*->e Z and e*->nu W are considered. The data used correspond to an integrated luminosity of 120 pb^(-1) taken in e^(+-)p collisions from 1994 to 2000 with the H1 detector at HERA at centre-of-mass energies of 300 and 318 GeV. No evidence for a signal is fou

Sawa Manoff, Bogdan Dimitrov

Conditions for the existence of flows with non-null shear-free and expansion-free velocities in spaces with affine connections and metrics are found. On their basis, generalized Weyl&#39;s spaces with shear-free and expansion-free conformal Killing vectors as velocity&#39;s vectors of spinless test particles moving in a Weyl&#39;s space are considered. The n

Sergio De Filippo, Filippo Maimone

Classical instability in fourth order gravity is cured at the expense of unitarity. The appearance of hidden degrees of freedom replicating those of ordinary matter allows for ordinary thermodynamic entropy and black hole entropy to be identified with von Neumann entropy. The emergent picture gives a substantial agreement with B-H entropy and Hawking tempera

Jochen Alber, Michael R. Fellows, Rolf Niedermeier

Dealing with the NP-complete Dominating Set problem on undirected graphs, we demonstrate the power of data reduction by preprocessing from a theoretical as well as a practical side. In particular, we prove that Dominating Set restricted to planar graphs has a so-called problem kernel of linear size, achieved by two simple and easy to implement reduction rule

Dritan Berzati, Bernhard Anrig, Juerg Kohlas

In this paper we present a transformation of finite propositional default theories into so-called propositional argumentation systems. This transformation allows to characterize all notions of Reiter&#39;s default logic in the framework of argumentation systems. As a consequence, computing extensions, or determining wether a given formula belongs to one exte

Eyal Amir

Craig&#39;s interpolation theorem (Craig 1957) is an important theorem known for propositional logic and first-order logic. It says that if a logical formula $β$ logically follows from a formula $α$, then there is a formula $γ$, including only symbols that appear in both $α,β$, such that $β$ logically follows from $γ$ and $γ$ logically follows from $α$. Such

Miroslav Kolesik, M. A. Novotny, Per Arne Rikvold

We study the extreme long-time behavior of the metastable phase of the three-dimensional Ising model with Glauber dynamics in an applied magnetic field and at a temperature below the critical temperature. For these simulations we use the advanced simulation method of projective dynamics. The algorithm is described in detail, together with its application to

Paolo Politi, Claudio Castellano

We study irreversible dimer nucleation on top of terraces during epitaxial growth in one and two dimensions, for all values of the step-edge barrier. The problem is solved exactly by transforming it into a first passage problem for a random walker in a higher-dimensional space. The spatial distribution of nucleation events is shown to differ markedly from th

Paolo Politi, Claudio Castellano

The formation of stable dimers on top of terraces during epitaxial growth is investigated in detail. In this paper we focus on mean-field theory, the standard approach to study nucleation. Such theory is shown to be unsuitable for the present problem, because it is equivalent to considering adatoms as independent diffusing particles. This leads to an overest

Pedro M. Reis, Tom Mullin

We present the results of an experimental study of patterned segregation in a horizontally shaken shallow layer of a binary mixture of dry particles. An order parameter for the segregated structures is defined and the effect of the variation of the combined filling fraction, $C$, of the mixture on the observed pattern formation is systematically studied. The

Jianqi Li, Yimei Zhu, J. M. Tranquada, K. Yamada

We characterize the local structure and correlations of charge stripes in La(1.725)Sr(0.275)NiO(4) using transmission-electron microscopy. We present direct evidence that the stripe modulation is indeed one-dimensional within each NiO(2) plane. Furthermore, we show that individual stripes tend to be either site-centered or bond-centered, with a bias towards

S. Heinze, J. Tersoff, R. Martel, V. Derycke

We show that carbon nanotube transistors operate as unconventional &#34;Schottky barrier transistors&#34;, in which transistor action occurs primarily by varying the contact resistance rather than the channel conductance. Transistor characteristics are calculated for both idealized and realistic geometries, and scaling behavior is demonstrated. Our results e

Eugene V. Kholopov

It is shown that Coulomb series are to be considered within a special mode of summation so as to describe bulk properties of crystals. The translational invariance is then an explicit integral property of Coulomb series that is tantamount to the effect of invariant periodic boundary conditions discussed earlier. Absolute bulk potentials with zero mean value

M. R. Eskildsen, M. Kugler, S. Tanaka, J. Jun

We report scanning tunneling spectroscopy imaging of the vortex lattice in single crystalline MgB2. By tunneling parallel to the c-axis, a single superconducting gap (Delta = 2.2 meV) associated with the pi-band is observed. The vortices in the pi-band have a large core size compared to estimates based on Hc2, and show an absence of localized states in the c

J. Carlos Egues, Guido Burkard, Daniel Loss

We have recently calculated shot noise for entangled and spin-polarized electrons in novel beam-splitter geometries with a local Rashba s-o interaction in the incoming leads. This interaction allows for a gate-controlled rotation of the incoming electron spins. Here we present an alternate simpler route to the shot noise calculation in the above work and foc

Keshav N. Shrivastava

The discovery of the series of minima in the transverse resistivity in the quantum Hall effect as distinguished from the integer quantum Hall effect which gives the value of e^2/h and the fractional value, (1/3)e^2/h, deserves recognition by the American Physical Society. The priorities in performing the experimental work as well as in theoretical understand

Takashi Uchihashi, Urs Ramsperger

Electron conduction through quasi-one-dimensional (1D) indium atomic wires on silicon (the Si(111)-4x1-In reconstruction) is clarified with the help of local structural analysis using scanning tunneling microscopy. The reconstruction has a conductance per square as high as 100 uS, with global conduction despite numerous surface steps. A complete growth of in

David Katz, Tommer Wizansky, Oded Millo, Eli Rothenberg

Photoluminescence excitation spectroscopy and scanning tunneling spectroscopy are used to study the electronic states in CdSe quantum rods that manifest a transition from a zero dimensional to a one dimensional quantum confined structure. Both optical and tunneling spectra show that the level structure depends primarily on the rod diameter and not on length.

Lorenz Bartosch, Marcus Kollar, Peter Kopietz

We study weak itinerant ferromagnetism in one-dimensional Fermi systems using perturbation theory and bosonization. We find that longitudinal spin fluctuations propagate ballistically with velocity v_m << v_F, where v_F is the Fermi velocity. This leads to a large anomalous dimension in the spin-channel and strong algebraic singularities in the single-partic

A. Kohen, G. Deutscher

We have measured the differential Conductance of Au/Y1-xCaxBa2Cu3O7-delta point contacts in the regime where it is dominated by Andreev reflection, which enhances its value at low bias. We find that the characteristics can not be fitted by a pure d-wave Order Parameter (OP). Using the formalism developed by Kashiwaya and Tanaka[1], the best fits are obtained

F. Guinea

We study the dynamics of a quantum particle coupled to dissipative (ohmic) environments, such as an electron liquid. For some choices of couplings, the properties of the particle can be described in terms of an effective mass. A particular case is the three dimensional dirty electron liquid. In other environments, like the one described by the Caldeira-Legge

D. N. H. Nam, L. V. Bau, N. V. Khiem, L. H. Son

While both La$_{0.7}$Sr$_{0.3}$MnO$_3$ and La$_{0.7}$Sr$_{0.3}$CoO$_3$ are ferromagnets with metallic conductivity below $T_\mathrm{c}$ (360K and 220K, respectively), partial substitutions of Co by Mn in La$_{0.7}$Sr$_{0.3}$Co$_{1-y}$Mn$_y$O$_3$ ($y < 0.1$) drastically suppress the ferromagnetic long-range order pre-established by Co-O-Co double exchange and