February 2000 arXiv papers — page 13

Carl H. Albright, S. M. Barr

A complete set of fermion and Higgs superfields is introduced with well-defined SO(10) properties and U(1) x Z_2 x Z_2 family charges from which the Higgs and Yukawa superpotentials are constructed. The structures derived for the four Dirac fermion and right-handed Majorana neutrino mass matrices coincide with those previously obtained from an effective oper

M. Cvetic, H. Lu, C. N. Pope

Several recent papers have made considerable progress in proving the existence of remarkable consistent Kaluza-Klein sphere reductions of D=10 and D=11 supergravities, to give gauged supergravities in lower dimensions. A proof of the consistency of the full gauged SO(8) reduction on S^7 from D=11 was given many years ago, but from a practical viewpoint a red

Christopher J. Miller, David J. Batuski

Recently, there have been numerous analyses of the redshift space power spectrum of rich clusters of galaxies. Some of these analyses indicate a "bump" in the Abell/ACO cluster power spectrum around k= 0.05hMpc^-1. Such a feature in the power spectrum excludes most standard formation models and indicates possible periodicity in the distribution of la

Xinlan Zhou, Debbie W. Leung, Isaac L. Chuang

We present a general method to construct fault-tolerant quantum logic gates with a simple primitive, which is an analog of quantum teleportation. The technique extends previous results based on traditional quantum teleportation (Gottesman and Chuang, Nature {\bf 402}, 390, 1999) and leads to straightforward and systematic construction of many fault-tolerant

William W Menasco

A knot type is exchange reducible if an arbitrary closed n-braid representative can be changed to a closed braid of minimum braid index by a finite sequence of braid isotopies, exchange moves and +/- destabilizations. In the manuscript [J Birman and NC Wrinkle, On transversally simple knots, preprint (1999)] a transversal knot in the standard contact structu

Filipe Freire, Daniel F. Litim

The type-I region of phase transitions at finite temperature of the U(1)-Higgs theory in 3+1 dimensions is investigated in detail using a Wilsonian renormalisation group. We consider in particular the quantitative effects induced through the cross-over of the scale-dependent Abelian charge from the Gaussian to a non-trivial Abelian fixed point. As a result,

C. Lunardini, A. Yu. Smirnov

We find that for small vacuum mixing angle $θ$ and low energies ($s\ll M^2_Z$) the width of matter, $d_{1/2}$, needed to have conversion probability $P\geq 1/2$ should be larger than $d_{min}= π/(2\sqrt{2} G_{F} \tan 2 θ)$: $d_{1/2}\geq d_{min}$. Here $G_F$ is the Fermi constant, $s$ is the total energy squared in the center of mass and $M_Z$ is the mass of

R. Jeannerot, S. Khalil, G. Lazarides, Q. Shafi

We show how hybrid inflation can be successfully realized in a supersymmetric model with gauge group G_{PS}= SU(4)_c x SU(2)_L x SU(2)_R. By including a non-renormalizable superpotential term, we generate an inflationary valley along which G_{PS} is broken to the standard model gauge group. Thus, catastrophic production of the doubly charged magnetic monopol

Mathias Klein, Raul Rabadan

We show how discrete torsion can be implemented in D=4, N=1 type IIB orientifolds. Some consistency conditions are found from the closed string and open string spectrum and from tadpole cancellation. Only real values of the discrete torsion parameter are allowed, i.e. epsilon=+-1. Orientifold models are related to real projective representations. In a simila

F. M. Cucchietti, H. M. Pastawski, R. Jalabert

The decay of the overlap between a wave packet evolved with a Hamiltonian H and the same state evolved with H}+$Σ$ serves as a measure of the decoherence time $τ_ϕ$. Recent experimental and analytical evidence on classically chaotic systems suggest that, under certain conditions, $τ_ϕ$ depends on H but not on $Σ$. By solving numerically a Hamiltonian model w

Qaisar Shafi, Zurab Tavartkiladze

We present a scenario which naturally provides bi-maximal neutrino mixings for a simultaneous explanation of the recent atmospheric and solar neutrino data. A crucial role is played by an anomalous flavor ${\cal U}(1)$ symmetry, which is also important for a natural understanding of charged fermion mass hierarchies and magnitudes of the CKM matrix elements.

ZEUS Collaboration

The e^+ jet invariant mass spectrum produced in the reaction e^+ p -> e^+ X has been studied at a center-of-mass energy of 300 GeV. The data were collected using the ZEUS detector operating at the HERA collider, and correspond to an integrated luminosity of 47.7 pb^{-1}. The observed mass spectrum is in good agreement with Standard Model expectations up to a

I. Hauser, F. J. Ernst

We enunciate and prove here a generalization of Geroch's famous conjecture concerning analytic solutions of the elliptic Ernst equation. Our generalization is stated for solutions of the hyperbolic Ernst equation that are not necessarily analytic, although it can be formulated also for solutions of the elliptic Ernst equation that are nowhere axis-access

Apoorva Patel

Replication of DNA and synthesis of proteins are studied from the view-point of quantum database search. Identification of a base-pairing with a quantum query gives a natural (and first ever) explanation of why living organisms have 4 nucleotide bases and 20 amino acids. It is amazing that these numbers arise as solutions to an optimisation problem. Componen

D. Bolle', D. M. Carlucci, G. M. Shim

Using the replica-symmetric mean-field theory approach the thermodynamic and retrieval properties of extremely diluted {\it symmetric} $Q$-Ising neural networks are studied. In particular, capacity-gain parameter and capacity-temperature phase diagrams are derived for $Q=3, 4$ and $Q=\infty$. The zero-temperature results are compared with those obtained from

Geza Odor, Nora Menyhard

The $A+A\to 0$, $B+B\to 0 $ process with exclusion between the different kinds is investigated here numerically. Before treating this model explicitly, we study the generalized Domany-Kinzel cellular automaton model of Hinrichsen on the line of the parameter space where only compact clusters can grow. The simplest version is treated with two absorbing phases

M. Calixto

Infinite enlargements of finite pseudo-unitary symmetries are explicitly provided in this letter. The particular case of u(2,2)=so(4,2)+u(1) constitutes a (Virasoro-like) infinite-dimensional generalization of the 3+1-dimensional conformal symmetry, in addition to matter fields with all conformal spins. These algebras provide a new arena for integrable field

Kaiki Taro Inoue

In this paper, Gaussianity of eigenmodes and non-Gaussianity in the Cosmic Microwave Background (CMB) temperature fluctuations in two smallest compact hyperbolic (CH) models are investigated. First, it is numerically found that the expansion coefficients of low-lying eigenmodes on the two CH manifolds behave as if they are Gaussian random numbers at almost a

M. B. Gaifullin, Yuji Matsuda, N. Chikumoto, J. Shimoyama

We report the first detailed and quantitative study of the Josephson coupling energy in the vortex liquid, Bragg glass and vortex glass phases of Bi_2Sr_2CaCu_2O_{8+δ} by the Josephson plasma resonance. The measurements revealed distinct features in the T- and H-dependencies of the plasma frequency $ω_{pl}$ for each of these three vortex phases. When going a

Tomasz Brzezinski

Given a ring $A$ and an $A$-coring $\cC$ we study when the forgetful functor from the category of right $\cC$-comodules to the category of right $A$-modules and its right adjoint $-\otimes_A\cC$ are separable. We then proceed to study when the induction functor $-\otimes_A\cC$ is also the left adjoint of the forgetful functor. This question is closely relate

M. Cencini, M. Falcioni, H. Kantz, E. Olbrich

In experiments, the dynamical behavior of systems is reflected in time series. Due to the finiteness of the observational data set it is not possible to reconstruct the invariant measure up to arbitrary fine resolution and arbitrary high embedding dimension. These restrictions limit our ability to distinguish between signals generated by different systems, s

J. E. Avron, A. Elgart, G. M. Graf, L. Sadun

We give a pedestrian interpretation of a formula of Buttiker et. al. (BPT) relating the adiabatically pumped current to the S matrix and its (time) derivatives. We relate the charge in BPT to Berry's phase and the corresponding Brouwer pumping formula to curvature. As applications we derive explicit formulas for the joint probability density of pumping a

Beat Ammon, Masatoshi Imada

Doping of a two-orbital chain with mobile S=1/2 Fermions and strong Hund's rule couplings stabilizing the S=1 spins strongly depends on the presence of a level difference among these orbitals. By DMRG methods we find a finite spin gap upon doping and dominant pairing correlations without level-difference, whereas the presence of a level difference leads

Giuseppe Castagnoli, Dalida Monti, Alexander Sergienko

We provide a justification of the quantum speed-up based on the complementary roles played by the reversible preparation of an entangled state before measurement and by the final measurement action.

I. Rotter, E. Persson, K. Pichugin, P. Seba

The spectroscopic properties of an open quantum system are determined by the eigenvalues and eigenfunctions of an effective Hamiltonian H consisting of the Hamiltonian H_0 of the corresponding closed system and a non-Hermitian correction term W arising from the interaction via the continuum of decay channels. The eigenvalues E_R of H are complex. They are th

Cheuk-Yin Wong, E. S. Swanson, T. Barnes

Using the quark-interchange model of Barnes and Swanson, we evaluate the dissociation cross sections for $J/ψ$ and $ψ'$ by $π$ and $ρ$ at low collision energies. In collisions with $π$ mesons near threshold the $π+ J/ψ$ dissociation cross section is predicted to be small, but the $π+ψ'$ cross section is found to be quite large, in qualitative agreeme

Bambi Hu, Changsong Zhou

We study the dynamics of a lattice of coupled nonidentical Fitz Hugh-Nagumo system subject to independent external noise. It is shown that these stochastic oscillators can lead to global synchronization behavior {\sl without an external signal}. With the increase of the noise intensity, the system exhibits coherence resonance behavior. Coupling can enhance g

Ernst Joachim Weniger

The prediction properties of Aitken's iterated Delta^2 process, Wynn's epsilon algorithm, and Brezinski's iterated theta algorithm for (formal) power series are analyzed. As a first step, the defining recursive schemes of these transformations are suitably rearranged in order to permit the derivation of accuracy-through-order relationships. On th

E. Arrondo, M. Bertolini, C. Turrini

We make a systematic study of the focal surface of a congruence of lines in the projective space. Using differential techniques together with techniques from intersection theory, we reobtain in particular all the invariants of the focal surface (degree, class, class of its hyperplane section, sectional genus and degrees of the nodal and cuspidal curve). We s

Daniel Azagra, Mar Jimenez-Sevilla

We prove the following new characterization of $C^p$ (Lipschitz) smoothness in Banach spaces. An infinite-dimensional Banach space $X$ has a $C^p$ smooth (Lipschitz) bump function if and only if it has another $C^p$ smooth (Lipschitz) bump function $f$ such that $f'(x)\neq 0$ for every point $x$ in the interior of the support of $f$ (that is, $f$ does no

Michael Falk, Richard Randell

In "On the homotopy theory of arrangements," published in 1986, the authors gave a comprehensive survey of the subject. This article updates and continues the earlier article, noting some key open problems.

David Savitt, Richard P. Stanley

In this paper, we prove that the dimension of the space spanned by the characters of the symmetric powers of the standard n-dimensional representation of the symmetric group S_n is asymptotic to n^2/2. This is proved by using generating functions to obtain formulas for upper and lower bounds, both asymptotic to n^2/2, for this dimension. In particular, for n

Kouichi Takemura

It is known that the trigonometric Calogero-Sutherland model is obtained by the trigonometric limit (τ\to \sqrt{-1} \infty) of the elliptic Calogero-Moser model, where (1,τ) is a basic period of the elliptic function. We show that for all square-integrable eigenstates and eigenvalues of the Hamiltonian of the Calogero-Sutherland model, if \exp (2π\sqrt{-1} τ

Khaled Abdel-Khalek

An off-shell formulation for 6 and 10 dimensions simple supersymmetric Yang-Mills theories is presented. While the fermionic fields couple to left action of S^3 and S^7 respectively, the auxiliary ones couple to right action (and vice versa). To close the algebra off-shell, left and right actions must commute. For 6 dimensions quaternions work fine. The 10 d

Alvaro de Souza Dutra, Cesar P. Natividade

In the present paper we introduce a hierarquical class of self-dual models in three dimensions, inspired in the original self-dual theory of Towsend-Pilch-Nieuwenhuizen. The basic strategy is to explore the powerful property of the duality transformations in order to generate a new field. The generalized propagator can be written in terms of the primitive on

V. Latora, D. Bazeia

We investigate the presence of chaos in a system of two real scalar fields with discrete Z_2 x Z_2 symmetry. The potential that identify the system is defined with a real parameter r and presents distinct features for r>0 and for r<0. For static field configurations, the system supports two topological sectors for r>0, and only one for r<0. Under the assumpt

Tristan Hubsch

Supersymmetry and Yang-Mills type gauge invariance are two of the essential properties of most, and possibly the most important models in fundamental physics. Supersymmetry is nearly trivial to prove in the (traditionally gauge-noncovariant) superfield formalism, whereas the gauge-covariant formalism makes gauge invariance manifest. In 3+1-dimensions, the tr

Jorma Louko, Donald Marolf, Simon F. Ross

One of the most challenging technical aspects of the dualities between string theory on anti-de Sitter spaces and conformal field theories is understanding how location in the interior of spacetime is represented in the field theory. It has recently been argued that the interior of the spacetime can be directly probed by using intrinsically non-local quantit

D. Bellisai, F. Fucito, A. Tanzini, G. Travaglini

In this letter we argue that instanton-dominated Green&#39;s functions in N=2 Super Yang-Mills theories can be equivalently computed either using the so-called constrained instanton method or making reference to the topological twisted version of the theory. Defining an appropriate BRST operator (as a supersymmetry plus a gauge variation), we also show that

O. Yu. Shvedov

One of the axioms of quantum field theory is the property of unitarity of the evolution operator. However, if one considers the quantum electrodynamics in the external field in the leading order of perturbation theory, one will find that the evolution transformation is a non-unitary canonical transformation of creation and annihilation operators. This observ

Jens Hoppe, Jan Plefka

The asymptotic form of a SU(3) matrix theory groundstate is found by showing that a recent ansatz for a supersymmetric wavefunction is non-trivial (i.e. non-zero).

Washington Taylor

These lecture notes give a pedagogical and (mostly) self-contained review of some basic aspects of the Matrix model of M-theory. The derivations of the model as a regularized supermembrane theory and as the discrete light-cone quantization of M-theory are presented. The construction of M-theory objects from matrices is described, and gravitational interactio

P. Sikivie

The strong CP problem and its resolution through the existence of an axion are briefly reviewed. The constraints on the axion from accelerator searches, from the evolution of red giants and from supernova SN1987a combine to require $m_a < 3 \cdot 10^{-3}$ eV, where $m_a$ is the axion mass. On the other hand, the constraint that axions do not overclose the un

I. N. Mishustin, L. M. Satarov, H. Stoecker, W. Greiner

Properties of dense quark matter in and out of chemical equilibrium are studied within the SU(3) Nambu-Jona-Lasinio model. In addition to the 4-fermion scalar and vector terms the model includes also the 6-fermion flavour mixing interaction. First we study a novel form of deconfined matter, meso-matter, which is composed of equal number of quarks and antiqua

N. Fornengo, M. C. Gonzalez-Garcia, J. W. F. Valle

A global analysis of all the available atmospheric neutrino data is presented in terms of neutrino oscillations in the nu_mu -> nu_tau and nu_mu -> nu_s channels, where nu_s denotes a sterile neutrino. We perform our analysis of the contained events data as well as the upward-going neutrino-induced muon fluxes. In addition to the previous data samples of Fre

K. Zuber

The current status of non-accelerator based searches for effects of a non-vanishing neutrino mass is reviewed. Beside the direct kinematical methods this includes searches for magnetic moments and a discussion of the solar neutrino problem. Double beta decay is not included.

G. Wilk, Z. Wlodarczyk

Recently we have demostrated that the nonextensitivity parameter q occuring in some applications of Tsallis statistics (known also as index of the corresponding Lévy distribution) is, in the q>1 case, given entirely by the fluctuations of the parameters of the usual exponential distribution. We show here that this interpretation is valid also for the q<1 cas

D. Ashery, H. J. Lipkin

Calculations of the polarization of $Λ$ and $\barΛ$ particles after fragmentation of a polarized quark produced in processes like $Z$-decay and deep inelastic polarized lepton scattering must include $Λ$ and $\barΛ$ produced as decay products of $Σ^0$ and $Σ^*$ as well as those produced directly. These decay contributions are significant and not feasibly inc

M. Maltoni

The main purpose of this thesis is to discuss the impact of electroweak precision measurements on the present knowledge of particle physics, both in the framework of the Standard Model and of its most straightforward extensions. In Chapter 1 we give a general overview of the electroweak sector of the SM and of SUSY phenomenology. In Chapter 2 we deal with di

Fabrizio Gangemi

The dimension-four genuine anomalous quartic couplings are studied in processes of six-fermion production via e+e- collisions. Complete tree-level electroweak calculations are performed including initial-state-radiation and beamstrahlung. The analysis of final-state distributions can be used to find kinematical cuts to enhance the effects of anomalous coupli

Seungwon Baek, Toru Goto, Yasuhiro Okada, Ken-ichi Okumura

Effects of supersymmetric particles on flavor changing neutral current and lepton flavor violating processes are studied in the supersymmetric SU(5) grand unified theory with right-handed neutrino supermultiplets. Using input parameters motivated by neutrino oscillation, it is shown that the time-dependent CP asymmetry of radiative B decay can be as large as

A. Bialas, W. Czyz

An algorithm for measurement of entropy in multiparticle systems, based on recently published proposal of the present authors, is given. Dependence on discretization of the system and effects of multiparticle correlations are discussed in some detail.

Wolfgang Lucha, F. F. Schoberl

In quantum theory, the so-called &#34;spinless Salpeter equation,&#34; the relativistic generalization of the nonrelativistic Schroedinger equation, is used to describe both bound states of scalar particles and the spin-averaged spectra of bound states of fermions. A numerical procedure solves the spinless Salpeter equation by approximating this eigenvalue e

D. de Florian, A. Signer

We present a general purpose Monte Carlo program for the calculation of any infrared safe observable in WGamma and ZGamma production at hadron colliders at next-to-leading order in alpha_s. We treat the leptonic decays of the W and Z-boson in the narrow-width approximation, but retain all spin information via decay angle correlations. The effect of anomalous

J. Ranft

A new striking feature of hadron production in nuclear collisions is the large stopping of the participating nucleons in hadron-nucleus and nucleus-nucleus collisions. This enhanced baryon stopping can be understood introducing new diquark breaking mechanisms in multistring models of hadron production. Here we show, that similar diquark breaking mechanisms o

Yutaka Kouchi, Yoshihiro Takeuchi, S. Y. Tsai

Possible violation of CP, T and/or CPT symmetries in the $\ko$-$\kob$ system is studied from a phenomenological point of view. For this purpose, we first introduce parameters which represent violation of these symmetries in mixing parameters and decay amplitudes in a convenient and well-defined way and, treating these parameters as small, derive formulas whi

Paul H. Frampton, Andrija Rasin

A promising direction to find physics beyond the standard model is to look for violation of $L_{e,μ,τ}$ conservation. In particular the process $e^- e^- \to μ^- μ^-$ with the exchange of a gauge bilepton has a striking signal without background and is predicted in the most economical model to have a cross-section an order of magnitude higher than previous es

Marco Battaglia

A generator for inclusive b -> u l nu decays has been developed. Different prescriptions have been applied to describe the kinematics of the b-quark inside the hadron and the generation of the hadronic final states. Results are presented with particular attention to the invariant mass of the hadronic system recoiling against the lepton and its resonance deco

Tatsuya Nakada

Lectures note for Cargese 99 Summer School Particle Physics: Ideas and Recent Development NATO Advanced Institute, Corsica, July 26-August 7, 1999

L3 Collaboration

A first measurement of the cross section of the process e+e- -> Z gamma gamma is reported using a total integrated luminosity of 231 pb^-1 collected with the L3 detector at centre-of-mass energies of 182.7 GeV and 188.7 GeV. By selecting hadronic events with two isolated photons the e+e- -> Z gamma gamma cross section is measured to be 0.49 +0.20 -0.17 +/- 0

L3 Collaboration

The total and differential cross sections of the process e+e- -> n gamma with n >= 2 are measured using data collected by the L3 experiment at centre-of-mass energies of \sqrt{s}=183 and 189 GeV. The results are in agreement with the Standard Model expectations. Limits are set on deviations from QED, contact interaction cut-off parameters and masses of excit

L3 Collaboration

Bhabha scattering data recorded at \sqrt{s}=189 GeV by the L3 detector at LEP are used to measure the running of the effective fine-structure constant for spacelike momentum transfers. The results are alpha^-1(-2.1 GeV^2) - alpha^-1(-6.25 GeV^2) = 0.78 +/- 0.26 alpha^-1(-12.25 GeV^2) - alpha^-1(-3434 GeV^2) = 3.80 +/- 1.29, in agreement with theoretical pred

L3 Collaboration

We report on measurements of e+e- annihilation into hadrons and lepton pairs. The data have been collected with the L3 detector at LEP at centre-of-mass energies between 130 and 189 GeV. Using a total integrated luminosity of 243.7 pb^-1, 25864 hadronic and 8573 lepton-pair events are selected for the measurement of cross sections and leptonic forward-backwa

M. Bosman, Y. Kulchitsky, M. Nessi

The intrinsic performance of the ATLAS barrel and extended barrel calorimeters for the measurement of charged pions is presented. Pion energy scans (E = 20, 50, 200, 400 and 1000 GeV) at two pseudo-rapidity points ($η$ = 0.3 and 1.3) and pseudorapidity scans ($-0.2 < η< 1.8$) with pions of constant transverse energy ($E_T = 20$ and 50 GeV) are analysed. A si

G. Giacomelli, L. Patrizii

The main aim of this lecture is to give an update on the lectures on Magnetic Monopoles (MMs) of the 1995 Trieste School. The update concerns theoretical developments, searches for GUT monopoles in the penetrating cosmic radiation at ever lower fluxes, study of the energy losses of MMs in the Earth and in detectors,searches for low mass monopoles, and finall

C. Barrabès, G. F. Bressange, P. A. Hogan

When two non-interacting plane impulsive gravitational waves undergo a head-on collision, the vacuum interaction region between the waves after the collision contains backscattered gravitational radiation from both waves. The two systems of backscattered waves have each got a family of rays (null geodesics) associated with them. We demonstrate that if it is

G. F. Bressange, P. A. Hogan

The peeling properties of a lightlike signal propagating through a general Bondi-Sachs vacuum spacetime and leaving behind another Bondi-Sachs vacuum space-time are studied. We demonstrate that in general the peeling behavior is the conventional one which is associated with a radiating isolated system and that it becomes unconventional if the asymptotically

A. M. Gevorkian, R. A. Gevorkian

1. Following Rimman, Minkowski and Einstein, for the first time equations of the inert filed in the covariant form are found geometrically. 2.In the approximation of a weak field for the first time the Law of Inertia in a material space (as opposed to the absolute space) is received. A consequence is the formulation of Mach&#39;s principle. 3. Analogous to E

M. Karlovini, K. Rosquist, L. Samuelsson

Ultra compact stellar models with a two-zone uniform density equation of state are considered. They are shown to provide neat examples of optical geometries exhibiting double necks, implying that the gravitational wave potential has a double well structure.

K. B. Lauritsen, M. J. Alava

We discuss the relation between self-organized criticality and depinning transitions by mapping sandpile models to equations that describe driven interfaces in random media. This equivalence yields a continuum description and gives insight about various ways of reaching the depinning critical point: slow drive (self-organized criticality), fixed density simu

C. W. Chu, Y. Y. Xue, S. Tsui, J. Cmaidalka

We have measured the dc and ac electrical and magnetic properties in various magnetic fields of the recently reported superconducting ferromagnet RuSr2GdCu2O8. Our reversible magnetization measurements demonstrate the absence of a bulk Meissner state in the compound below the superconducting transition temperature. Several scenarios that might account for th

D. F. Agterberg, S. Yunoki

We provide numerical evidence that a spin-flux phase exists as a ground state of the Kondo lattice model with classical local spins on a square lattice. This state manifests itself as a double-Q magnetic order in the classical spins with spin density at both $(0,π)$ and $(π,0)$ and further exhibits fermionic spin currents around an elementary plaquette of th

R. Seviour, A. F. Volkov

We analyse the measured critical current $I_{m\text{}}$ in a mesoscopic 4-terminal S/N/S structure. The current through the S/N interface is shown to consist not only of the Josephson component $I_{c}\sin ϕ,$ but also a phase-coherent part $I_{sg}\cos ϕ$ of the subgap current. The current $I_{m}$ is determined by the both components $I_{c}$ and $I_{sg},$ and

A. Bachtold, M. S. Fuhrer, S. Plyasunov, M. Forero

We use electrostatic force microscopy and scanned gate microscopy to probe the conducting properties of carbon nanotubes at room temperature. Multi-walled carbon nanotubes are shown to be diffusive conductors, while metallic single-walled carbon nanotubes are ballistic conductors over micron lengths. Semiconducting single-walled carbon nanotubes are shown to

D. Alfe`, G. D. Price, M. J. Gillan

We present a new technique which allows the fully {\em ab initio} calculation of the chemical potential of a substitutional impurity in a high-temperature crystal, including harmonic and anharmonic lattice vibrations. The technique uses the combination of thermodynamic integration and reference models developed recently for the {\em ab initio} calculation of

Weimin Chen, J. P. Franck, J. Jung

Normal-state resistance data from Bi_2Sr_2CaCu_2O_8 single crystals were fitted to the (bi)polaronic conduction model, $R=R_0 (T+σ_b T^2)/(1+bT)$, with satisfactory agreement over a wide temperature range. The fluctuating conduction region is found to be much narrower than that in the usual sense, as is the case for a charged Bose-gas. We estimate the effect

L. E. F. Foa Torres, H. M. Pastawski, S. S. Makler

We model the Fock space for the electronic resonant tunneling through a double barrier including the coherent effects of the electron-phonon interaction. The geometry is optimized to achieve the maximal optical phonon emission required by a SASER (ultrasound emitter) device.

Weimin Chen, J. P. Franck, J. Jung

Four regimes of vortex motion were identified in the magnetoresistance of Bi$_2$Sr$_2$CaCu$_2$O$_{8+δ}$ single crystals: (1) thermally activated flux flow (TAFF) in samples with surface defects caused by thermal annealing; (2) TAFF-like plastic motion of highly entangled vortex liquid at low temperatures, with $U_{pl} \sim (1-T/T_c)/H^{1/2}$; (3) pure free f

A. N. Korotkov, D. V. Averin

We consider the problem of continuous quantum measurement of coherent oscillations between two quantum states of an individual two-state system. It is shown that the interplay between the information acquisition and the backaction dephasing of the oscillations by the detector imposes a fundamental limit, equal to 4, on the signal-to-noise ratio of the measur

Jairo Sinova, V. Meden, S. M. Girvin

We present a novel approach to the localization-delocalization transition in the integer quantum Hall effect. The Hamiltonian projected onto the lowest Landau level can be written in terms of the projected density operators alone. This and the closed set of commutation relations between the projected densities leads to simple equations for the time evolution

D. Hinzke, U. Nowak

For the investigations of thermally activated magnetization reversal in systems of classical magnetic moments numerical methods are desirable. We present numerical studies which base on time quantified Monte Carlo methods where the long-range dipole-dipole interaction is calculated with the aid of fast Fourier transformation. As an example, we study models f

Hong Xu, Jean-Pierre Hansen

A mixed classical-quantum density functional theory is used to calculate pair correlations and the free energy of a spin-polarized Hydrogen plasma. A transition to an atomic insulator phase is estimated to occur around r_s=2.5 at T=10^4K, and a pressure $P\approx0.5Mbar$. Spin polarization is imposed to prevent the formation of H_2 molecules.

J. Hove, A. Sudbo

The critical properties of a type-II superconductor model are investigated using a dual vortex representation. Computing the propagators of gauge field $\vec{A}$ and dual gauge field $\vec{h}$ in terms of a vortex correlation function, we obtain the values $η_A=1$ and $η_h=1$ for their anomalous dimensions. This provides support for a dual description of the

A. Knigavko, V. G. Kogan, B. Rosenstein, T. -J. Yang

The transformation of the vortex lattice in a tetragonal superconductor which consists of its 45 degree reorientation relative to the crystal axes is studied using the nonlocal London model. It is shown that the reorientation occurs as two successive second order (continuous) phase transitions. The transition magnetic fields are calculated for a range of par

Bambi Hu, Baowen Li, Hong Zhao

Two classes of 1D nonintegrable systems represented by the Fermi-Pasta-Ulam (FPU) model and the discrete $ϕ^4$ model are studied to seek a generic mechanism of energy transport in microscopic level sustaining macroscopic behaviors. The results enable us to understand why the class represented by the $ϕ^4$ model has a normal thermal conductivity and the class

E. E. Narimanov, C. M. Varma

We develop a variational mean-field theory of the ferromagnetic transition in compounds like Lanthanum-Manganite within the framework of the Double-Exchange Model supplemented by modest disorder. We obtain analytical expressions for the transition temperature, its variation with the valence electron-density and its decrease with disorder. We derive an expres

A. E. Koshelev, L. N. Bulaevskii

We investigate the magnetic field dependence of the plasma resonance frequency in vortex crystal state. We find that low magnetic field induces a small correction to the plasma frequency proportional to the field. The slope of this linear field dependence is directly related to the average distance between the pancake vortices in the neighboring layers, the

D. Argast, M. Samland, O. E. Gerhard, F. -K. Thielemann

We introduce a stochastic halo formation model to compute the early chemical enrichment of the interstellar medium (ISM) of the halo. Contrary to 1-zone chemical evolution models, we are able to resolve local inhomogeneities in the ISM caused by single core-collapse supernovae. These inhomogeneities lead to different element abundance patterns in very metal-

G. Steigman

The physics of the standard hot big bang cosmology ensures that the early Universe was a primordial nuclear reactor, synthesizing the light nuclides (D, 3He, 4He, and 7Li) in the first 20 minutes of its evolution. After an overview of nucleosynthesis in the standard model (SBBN), the primordial abundance yields will be presented, followed by a status report

Brian E. Wood, Margarita Karovska

We present results from an empirical study of the Mg II h & k emission lines of selected Mira variable stars, using spectra from the International Ultraviolet Explorer (IUE). The stars all exhibit similar Mg II behavior during the course of their pulsation cycles. The Mg II flux always peaks after optical maximum near pulsation phase 0.2-0.5, although the Mg

L. I. Rudakov, A. V. Gretchikha, C. S. Liu, G. M. Milikh

The objective of this paper is to apply the recent achievements in understanding of the non-MHD effects in plasma (acquired both in laboratory experiments, as well as in theory), to the interstellar phenomena. Applied to the space plasma, these effects can significantly change the picture of plasma dynamics. Charged dust particles are always present in the i

S. C. Woodworth, W. E. Harris

Using archival \hst WFPC2 data, we derive the metallicity distribution, luminosity function, and spatial structure of the globular cluster system around IC 4051, a giant E galaxy on the outskirts of the Coma cluster core. The metallicity distribution derived from the (V-I) colors has a mean [Fe/H] = -0.3, a near-complete lack of metal-poor clusters, and only

Michael D. Smith, Mordecai-Mark Mac Low, Julia M. Zuev

We here analyse numerical simulations of supersonic, hypersonic and magnetohydrodynamic turbulence that is free to decay. Our goals are to understand the dynamics of the decay and the characteristic properties of the shock waves produced. This will be useful for interpretation of observations of both motions in molecular clouds and sources of non-thermal rad

Achim Weiss, Pavel A. Denissenkov, Corinne Charbonnel

We have calculated the evolution of low metallicity red giant stars under the assumption of deep mixing between the convective envelope and the hydrogen burning shell. We find that the extent of the observed abundance anomalies, and in particular the universal O-Na anticorrelation, can be totally explained by mixing which does not lead to significant helium

Joseph L. Hora, William B. Latter, Aditya Dayal, John Bieging

Images of Hubble 12 were obtained with the HST/NICMOS instrument in the F110W, F164N, and F166N filters of NIC1, and the F160W, F187N, F190N, F212N, F215N filters of NIC2. The images show the structure of the inner ``torus&#39;&#39; and lobes much clearer than previous ground-based images. In particular, the [Fe II] lobes are clearly resolved and shown to be

Jonathan P. Williams, Philip C. Myers

We have mapped the dense gas distribution and dynamics in the NW region of the Serpens molecular cloud in the CS(2-1) and N2H+(1-0) lines and 3 mm continuum using the FCRAO telescope and BIMA interferometer. 7 continuum sources are found. The N2H+ spectra are optically thin and fits to the 7 hyperfine components are used to determine the distribution of velo

A. R. King

I show that the Eddington limit implies a critical orbital period P_crit(BH) = 2d beyond which black-hole LMXBs cannot appear as persistent systems. The unusual behaviour of GRO J1655-40 may result from its location close to this critical period.

G. Lagache, J-L. Puget, A. Abergel, F. R. Bouchet

A Cosmic Far-InfraRed Background (CFIRB) has long been predicted that would traces the intial phases of galaxy formation. It has been first detected by Puget et al.(1996) using COBE data and has been later confirmed by several recent studies (Fixsen et al. 1998, Hauser et al. 1998, Lagache et al. 1999). We will present a new determination of the CFIRB that u

Herve Dole, Richard Gispert, Guilaine Lagache, Jean-Loup Puget

FIRBACK is a one of the deepest surveys performed at 170 microns with ISOPHOT onboard ISO, and is aimed at the study of cosmic far infrared background sources. About 300 galaxies are detected in an area of four square degrees, and source counts present a strong slope of 2.2 on an integral &#34;logN-logS&#34; plot, which cannot be due to cosmological evolutio

D. Cesarsky, A. P. Jones, J. Lequeux, L. Verstraete

We present mid-infrared spectro-imagery and high-resolution spectroscopy of the Orion bar and of a region in the Orion nebula. These observations have been obtained in the Guaranteed Time with the Circular Variable Filters of the ISO camera (CAM-CVF) and with the Short Wavelength Spectrometer (SWS), on board the European Infrared Space Observatory (ISO). Our