October 1999 arXiv papers — page 14

Murat Gunaydin, Seiji Takemae

We study the unitary supermultiplets of the N=4 d=7 anti-de Sitter (AdS_7) superalgebra OSp(8^*|4), with the even subalgebra SO(6,2) X USp(4), which is the symmetry superalgebra of M-theory on AdS_7 X S^4. We give a complete classification of the positive energy doubleton and massless supermultiplets of OSp(8^*|4) . The ultra-short doubleton supermultiplets

C. A. Bertulani, D. S. Dolci

Elastic charge-exchange in relativistic heavy ion collisions is responsible for the non-disruptive change of the charge state of the nuclei. We show that it can be reliably calculated within the eikonal approximation for the reaction part. The formalism is applied to the charge-pickup cross sections of 158 GeV/nucleon Pb projectiles on several targets. The r

Patrick Azaria, Edouard Boulat, Philippe Lecheminant

We study the effect of symmetry breaking perturbations in the one-dimensional SU(4) spin-orbital model. We allow the exchange in spin ($J_1$) and orbital ($J_2$) channel to be different and thus reduce the symmetry to SU(2) $\otimes$ SU(2). A magnetic field $h$ along the $S^z$ direction is also applied. Using the formalism developped by Azaria et al we exten

E. Ramirez-Ruiz, E. E. Fenimore

Many cosmological models of GRBs envision the energy source to be a cataclysmic stellar event leading to a relativistically expanding fireball. Particles are thought to be accelerated at shocks and produce nonthermal radiation. The highly variable temporal structure observed in most GRBs has significantly constrained models. By using different methods of sta

Richard Arens, V. S. Varadarajan

In this paper the notion of an EPR state for the composite S of two quantum systems S1, S2, relative to S2 and a set O of bounded observables of S2, is introduced in the spirit of classical examples of Einstein-Podolsky-Rosen and Bohm. We restrict ourselves mostly to EPR states of finite norm. The main results are contained in Theorem 3,4,5,6 in section III

M. E. Carrington, Hou Defu, R. Kobes

We study shear viscosity in weakly coupled hot $ϕ^4$ theory using the CTP formalism . We show that the viscosity can be obtained as the integral of a three-point function. Non-perturbative corrections to the bare one-loop result can be obtained by solving a decoupled Schwinger-Dyson type integral equation for this vertex. This integral equation represents th

M. R. Gaberdiel, B. Stefanski

The D-brane spectrum of a class of $\Zop_2$ orbifolds of toroidally compactified Type IIA and Type IIB string theory is analysed systematically. The corresponding K-theory groups are determined and complete agreement is found. The charge densities of the various branes are also calculated.

I. Dadic

We study out of equilibrium thermal field theories with switching on the interaction occurring at finite time using the Wigner transforms (in relative space-time) of two-point functions. For two-point functions we define the concept of projected function: it is zero if any of times refers to the time before switching on the interaction, otherwise it depends

Dipankar Chakrabarti, Asmita Mukherjee, Rajen Kundu, A. Harindranath

Issues related with microcausality violation and continuum limit in the context of (1+1) dimensional scalar field theory in discretized light-cone quantization (DLCQ) are addressed in parallel with discretized equal time quantization (DETQ) and the fact that Lorentz invariance and microcausality are restored if one can take the continuum limit properly is em

Adolf N. Witt

This review summarizes the observational characteristics of those interstellar grains which are prevented from entering the solar system by interactions with the heliopause. Such grains are typically less tha 100nm in radius, and they reveal their presence by interstellar absorption at ultraviolet wavelengths and by non-equilibrium emissions in the red and n

D. A. Head

We show that the emergence of criticality in the locally-defined Bak-Sneppen model corresponds to separation over a hierarchy of timescales. Near to the critical point the model obeys scaling relations, with exponents which we derive numerically for a one-dimensional system. We further describe how the model can be related to the glass model of Bouchaud [{\e

Marek Zukowski, Dagomir Kaszlikowski, Adam Baturo, Jan-Åke Larsson

The two-particle correlation obtained from the quantum state used in the Bell inequality is sinusoidal, but the standard Bell inequality only uses two pairs of settings and not the whole sinusoidal curve. The highest to-date visibility of an explicit model reproducing sinusoidal fringes is 2/pi. We conjecture from a numerical approach presented in this paper

Yousuke Itoh, Toshifumi Futamase, Hideki Asada

We derive the equation of motion for the relativistic compact binaries in the post-Newtonian approximation taking explicitly their strong internal gravity into account. For this purpose we adopt the method of the point particle limit where the equation of motion is expressed in terms of the surface integrals. We examine carefully the behavior of the surface

Sheng Li

The disclination in Lorentz space-time is studied in detail by means of topological properties of $ϕ$-mapping. It is found the space-time disclination can be described in term of a Dirac spinor. The size of the disclination, which is proved to be the difference of two sets of su(2)% -like monopoles expressed by two mixed spinors, is quantized topologically i

Makoto Natsuume, Takashi Okamura, Masamichi Sato

Strominger has derived the Bekenstein-Hawking entropy of the BTZ black hole using asymptotic Virasoro algebra. We apply Strominger's method to a black hole solution found by Martinez and Zanelli (MZ). This is a solution of three-dimensional gravity with a conformal scalar field. The solution is not $AdS_3$, but it is asymptotically $AdS_3$; therefore, it

Jac Condella, Carleton DeTar

We model the deconfinement phase transition in quantum chromodynamics at nonzero baryon number density and large quark mass by extending the flux tube model (three-state, three-dimensional Potts model) to nonzero chemical potential. In a direct numerical simulation we confirm mean-field-theory predictions that the deconfinement transition does not occur in a

The Soudan 2 Collaboration, D. Wall

A search for nucleon decay into two-body final states containing K^0 mesons has been conducted using the 963 metric ton Soudan 2 iron tracking calorimeter. The topologies, ionizations, and kinematics of contained events recorded in a 5.52 kiloton-year total exposure (4.41 kton-year fiducial volume exposure) are examined for compatibility with nucleon decays

Frederick A. Harris

This paper summarizes recent results obtained from the BES psi(2S) data, which with 3.8 M events, is the world's largest data set. Distributions for psi(2S) -> pi^+ pi^- J/psi are fit to the Novikov-Shifman model. Preliminary branching fractions are reported for psi(2S) -> gamma f_2(1270) and gamma f_J(1710), as well as for decays into states containing an o

R. G. Carlberg, H. K. C. Yee, S. L. Morris, H. Lin

The redshift evolution of the galaxy two-point correlation function is a fundamental cosmological statistic. To identify similar galaxy populations at different redshifts, we select a strict volume-limited sample culled from the 6100 cataloged CNOC2 galaxies. Our high-luminosity subsample selects galaxies having k-corrected and evolution-compensated R lumino

John C. Baez

We study perturbation theory for spin foam models on triangulated manifolds. Starting with any model of this sort, we consider an arbitrary perturbation of the vertex amplitudes, and write the evolution operators of the perturbed model as convergent power series in the coupling constant governing the perturbation. The terms in the power series can be efficie

W. J. Munro, G. J. Milburn, B. C. Sanders

We show how entangled qubits can be encoded as entangled coherent states of two-dimensional centre-of-mass vibrational motion for two ions in an ion trap. The entangled qubit state is equivalent to the canonical Bell state, and we introduce a proposal for entanglement transfer from the two vibrational modes to the electronic states of the two ions in order f

P. G. Estevez, G. A. Hernáez

In this paper the Singular Manifold Method has allowed us to obtain the Lax pair, Darboux transformations and tau functions for a non-linear Schrödiger equation in 2+1 dimensions. In this way we can iteratively build different kind of solutions with solitonic behavior.

H. J. S. Dorren, J. J. B. van den Heuvel

Pulse broadening for optical solitons due to birefringence is investigated. We present an analytical solution which describes the propagation of solitons in birefringent optical fibers. The special solutions consist of a combination of purely solitonic terms propagating along the principal birefringence axes and soliton-soliton interaction terms. The soliton

Daniel Gottesman

I present a variety of results on the theory of quantum secret sharing. I show that any mixed state quantum secret sharing scheme can be derived by discarding a share from a pure state scheme, and that the size of each share in a quantum secret sharing scheme must be at least as large as the size of the secret. I show that the only constraints on the existen

Fabrizio Cametti, Giovanni Jona-Lasinio, Carlo Presilla, Fabio Toninelli

No abstract available

K. G. H. Vollbrecht, R. F. Werner

We analyze some special properties of a system of two qubits, and in particular of the so-called Bell basis for this system, which have played an important role in recent papers on entanglement of qubits. In particular, we show which of these properties may be generalized to higher dimension. We give a general construction for bases of maximally entangled ve

Reinhard F. Werner, Michael M. Wolf

We study violations of n particle Bell inequalities (as developed by Mermin and Klyshko) under the assumption that suitable partial transposes of the density operator are positive. If all transposes with respect to a partition of the system into p subsystems are positive, the best upper bound on the violation is 2^((n-p)/2). In particular, if the partial tra

Tamas Fulop, Izumi Tsutsui

The quantum dynamics of a free particle on a circle with point interaction is described by a U(2) family of self-adjoint Hamiltonians. We provide a classification of the family by introducing a number of subfamilies and thereby analyze the spectral structure in detail. We find that the spectrum depends on a subset of U(2) parameters rather than the entire U(

Markus Grassl, Thomas Beth

We transfer the concept of linear feed-back shift registers to quantum circuits. It is shown how to use these quantum linear shift registers for encoding and decoding cyclic quantum error-correcting codes.

Markus Grassl, Thomas Beth

After a brief introduction to both quantum computation and quantum error correction, we show how to construct quantum error-correcting codes based on classical BCH codes. With these codes, decoding can exploit additional information about the position of errors. This error model - the quantum erasure channel - is discussed. Finally, parameters of quantum BCH

Markus Grassl, Willi Geiselmann, Thomas Beth

After a brief introduction to both quantum computation and quantum error correction, we show how to construct quantum error-correcting codes based on classical BCH codes. With these codes, decoding can exploit additional information about the position of errors. This error model - the quantum erasure channel - is discussed. Finally, parameters of quantum BCH

C. W. Gardiner, J. Ye, H. C. Nagerl, H. J. Kimble

We solve a stochastic master equation based on the theory of Savard et al. [T.A. Savard, K.M. O'Hara and J.E. Thomas, Phys. Rev. A 56, R1095 (1997)] for heating arising from fluctuations in the trapping laser intensity. We compare with recent experiments of Ye et. al. [J. Ye, D.W. Vernooy and H.J. Kimble, Trapping of single atoms in cavity QED, quant-ph/

J. Oscar Rosas-Ortiz

New exactly solvable problems have already been studied by using a modification of the factorization method introduced by Mielnik. We review this method and its connection with the traditional factorization method. The survey includes the discussion on a generalization of the factorization energies used in the traditional Infeld and Hull method.

Y. Alhassid, S. Liu, H. Nakada

We introduce a particle-number reprojection method in the shell model Monte Carlo that enables the calculation of observables for a series of nuclei using a Monte Carlo sampling for a single nucleus. The method is used to calculate nuclear level densities in the complete $(pf+g_{9/2})$-shell using a good-sign Hamiltonian. Level densities of odd-A and odd-odd

E. O. Alt, T. Csorgo, B. Lorstad, J. Schmidt-Sorensen

The effect of multi-particle Coulomb final state interactions on higher-order intensity correlations is determined in general, based on a scattering wave function which is solution of the n-body Coulomb Schrödinger equation in (a large part of) the asymptotic region of n-body configuration space. In particular, we study Coulomb effects on the n-particle Bose

M. M. Pavan, R. A. Arndt, I. I. Strakovsky, R. L. Workman

Our extraction of the pion-nucleon coupling constant from πp elastic scattering data is outlined. A partial wave analysis (T_π < 2100 MeV) is performed simultaneously with a fixed-t dispersion relation analysis (T_π < 800 MeV). The πNN coupling constant g^2/4πis searched to find the best fit. The result 13.73 \pm 0.01 \pm 0.07 (first error statistical, secon

H. -M. Muller, S. E. Koonin, R. Seki, U. van Kolck

We investigate nuclear matter on a cubic lattice. An exact thermal formalism is applied to nucleons with a Hamiltonian that accommodates on-site and next-neighbor parts of the central, spin- and isospin-exchange interactions. We describe the nuclear matter Monte Carlo methods which contain elements from shell model Monte Carlo methods and from numerical simu

H. Kamada

Using a scale transformation in momentum space a phase equivalent relativistic potential is generated from the nonrelativistic potential. By that transformation a practical method for the relativistic 3N scattering with realistic nucleon-nucleon potentials is introduced. The formalism can be applied to any realistic nonrelativistic potential. We also discuss

J. F. Carinena, A. Ramos

The basic concepts of factorizable problems in one-dimensional Quantum Mechanics, as well as the theory of Shape Invariant potentials are reviewed. The relation of this last theory with a generalization of the classical Factorization Method presented by Infeld and Hull is analyzed in detail. By the use of some properties of the Riccati equation the solutions

Omar Mustafa, Maen Odeh

The quasi-relativistic harmonic oscillator bound states constructed by Znojil (J. Phys. A: Math. Gen. 29 (1999)2905) are investigated via a new methodical proposal. Compared with those obtained by an anonymous referee (from a direct numerical integration method)of Znojil&#39;s paper, our results appear to be more favourable than those obtained by Znojil via

Peter Petersen, Frederick Wilhelm

We show that the unit tangent bundle of S^4 and a real cohomology CP^3 admit Riemannian metrics with positive sectional curvature almost everywhere. These are the only examples so far with positive curvature almost everywhere that are not also known to admit positive curvature.

Ravi Vakil

The following divisors in the space Sym^{12} P^1 of twelve points on P^1 are actually the same: (A) the possible locus of the twelve nodal fibers in a rational elliptic fibration (i.e. a pencil of plane cubic curves); (B) degree 12 binary forms that can be expressed as a cube plus a square; (C) the locus of the twelve tangents to a smooth plane quartic from

Steven Dale Cutkosky, Olivier Piltant

Suppose that $f: Y\to X$ is a proper, dominant, tamely ramified morphism of algebraic surfaces, over a perfect field. We show that it is possible to perform sequences of monoidal transforms $Y&#39;\to Y$ and $X&#39;\to X$ to obtain an induced morphism $Y&#39;\to Y$ which is a monomial morphism.

H. Kurke, O. Teschke

We extend the notion of the spectrum of semistable rank two bundles (initially constructed on ${\bf P}^3$ by Barth and Elencwajg) to a certain class of compact complex algebraic threefolds.

Peter G. Casazza, Niels Jorgen Nielsen

The main result of this paper states that if a Banach space X has the property that every bounded operator from an arbitrary subspace of X into an arbitrary Banach space of cotype 2 extends to a bounded operator on X, then $B(\ell_{\infty},X^*)=Π_2(\ell_{\infty},X^*)$. If in addition X has the Gaussian average property, then it is of type 2. This implies tha

Bernhard Koeck

We prove a certain Riemann-Roch type formula for symmetric powers of Galois modules on Dedekind schemes which, in the number field or function field case, specializes to a formula of Burns and Chinburg for Cassou-Noguès-Taylor operations.

Helmut Prodinger

A reformulation of the path length of binary search trees is given in terms of permutations, allowing to extend the definition to the instance of words, where the letters are obtained by independent geometric random variables (with parameter q). In this way, expressions for expectation and variance are obtained which in the limit for $q\to1$ are the classica

Rafal Ablamowicz

{\sc CLIFFORD} is a Maple package for computations in Clifford algebras $\cl (B)$ of an arbitrary symbolic or numeric bilinear form B. In particular, B may have a non-trivial antisymmetric part. It is well known that the symmetric part g of B determines a unique (up to an isomorphism) Clifford structure on $\cl(B)$ while the antisymmetric part of B changes t

A. N. Dranishnikov

There is a word metric $d$ on countably generated free group $Γ$ such that $(Γ,d)$ does not admit a coarse uniform embedding into a Hilbert space.

Bernhard Köck

Let R be a commutative ring and I an ideal in R which is locally generated by a regular sequence of length d. Then, each projective R/I-module V has an R-projective resolution P. of length d. In this paper, we compute the homology of the n-th Koszul complex associated with the homomorphism P_1 --> P_0 for all n, if d = 1. This computation yields a new proof

Mihail Mihailescu

Six dimensional supergravities on $ADS_3 \times S^3$ present interest due to the role they play in the $AdS/CFT$ correspondence. The correspondence in this case states the equivalence between supergravity on the given background and a still unknown conformal field theory. The conformal field theory in question is expected to appear by deforming of the free c

T. Guhr, T. Wilke, H. A. Weidenmueller

Recent theoretical and numerical developments show analogies between quantum chromodynamics (QCD) and disordered systems in condensed matter physics. We study the spectral fluctuations of a Dirac particle propagating in a finite four dimensional box in the presence of gauge fields. We construct a model which combines Efetov&#39;s approach to disordered syste

A. K. Biswas, J. Maharana

The holographic ratio in Pre-big bang string cosmology is obtained in the presence string sources. An iterative procedure is adopted to solve the equations of motion and derive the ratio in four dimensional world. First the zeroth order ratio is computed in the remote past, i.e. at $t=-\infty$, then the holographic ratio is obtained taking into account the e

Ying Jiang, Yishi Duan

In the light of $ϕ$-mapping method and the topological tensor current theory, the topological structure and the topological quantization of topological defects are obtained under the condition that Jacobian $J(ϕ/v)\neq0$. When $J(ϕ/v)=0$, it is shown that there exists the crucial case of branch process. Based on the implicit function theorem and the Taylor e

El hassan El aaoud, A. N. Kamal

We have carried out an analysis of helicity and partial-wave amplitudes for the process D -> K^* ρin the factorization approximation using several models for the form factors. All the models, with the exception of one, generate partial-wave amplitudes with the hierarchy $\mid S\mid >\mid P\mid >\mid D\mid$. The one exception gives $\mid S \mid >\mid D \mid >

David O. Caldwell

There is a puzzling contradiction: direct observations favor a low-mass-density universe ($0.2\leΩ_m\le0.6$), but the only model which fits universe structure over more than three orders of magnitude in distance scale has a mix of hot (neutrino) and cold dark matter providing a critical density universe. Models of an open universe (low $Ω_m$) or one adding a

Byung-Yoon Park, Mannque Rho, Andreas Wirzba, Ismail Zahed

We discuss the Overhauser effect (particle-hole pairing) versus the BCS effect (particle-particle or hole-hole pairing) in QCD at large quark density. In weak coupling and to leading logarithm accuracy, the pairing energies can be estimated exactly. For a small number of colors, the BCS effect overtakes the Overhauser effect, while for a large number of colo

M. A. Doncheski, R. W. Robinett

In this note, we consider dijet production at gamma gamma colliders as a probe of recently proposed, large extra-dimensional gravity models. The exchange of virtual, spin-2 graviton towers (Kaluza-Klein excitations) significantly modifies the cross section, as compared to the Standard Model predictions. We find that, in order to maximize the value of the eff

K. G. Chetyrkin, R. Harlander, J. H. Kuehn

The calculation of the quartic mass terms at order α_s^3 to the hadronic R ratio is described. It is based on the operator product expansion for the quark current correlator, combined with an application of the renormalization group equation.

V. Antonelli, M. Dasgupta, G. P. Salam

We present preliminary results on the resummation of leading and next-to-leading logarithms for the thrust distribution in deep inelastic scattering. Our predictions, expanded to O(alpha_s^2), are compared to corresponding results from the Monte Carlo programs DISASTER++ and DISENT.

M. A. Ivanov, J. G. Korner, V. E. Lyubovitskij, A. G. Rusetsky

Semileptonic decays of Lambda_b and Lambda_c baryons are studied within the Relativistic Three-Quark Model using finite heavy quark mass values. Employing the same parameters as have been used previously for the description of exclusive decays of heavy baryons in the heavy quark limit we calculate the six form factors of the process and the corresponding dec

F. Déliot, C. Royon, E. Perez, G. Moreau

We consider the single chargino production at Tevatron $p \bar p \to \tilde ν_i \to \tilde χ^{\pm}_1 l_i^{\mp}$ as induced by the resonant sneutrino production via a dominant \RPV coupling of type $ł&#39;_{ijk} L_i Q_j D_k^c$. Within a supergravity model, we study the three leptons final state. The comparison with the expected background demonstrate that thi

W. Grimus

We discuss all possible schemes with four massive neutrinos inspired by the existing experimental indications in favour of neutrino mixing, namely the atmospheric, solar and LSND neutrino experiments. We argue that the scheme with a neutrino mass hierarchy is not compatible with the experimental results, likewise all other schemes with the masses of three ne

K. G. Chetyrkin, R. Harlander, T. Seidensticker, M. Steinhauser

We report on a recent calculation of the top decay rate up to order α_s^2. It is based on asymptotic expansions of the off-shell top propagator, followed by a Padé approximation in order to reach the physically relevant point q^2=Mt^2.

V. S. Fadin, L. N. Lipatov, A. D. Martin, M. Melles

At future linear $e^+e^-$ collider experiments in the TeV range, Sudakov double logarithms originating from massive boson exchange can lead to significant corrections to the cross sections of the observable processes. These effects are important for the high precision objectives of the Next Linear Collider. We use the infrared evolution equation, based on a

Carlo Giunti

It is shown that at least four massive neutrinos are needed in order to accommodate the evidences in favor of neutrino oscillations found in solar and atmospheric neutrino experiments and in the LSND experiment. Among all four-neutrino schemes, only two, with a mass spectrum composed of two pairs of neutrinos with close masses separated by the &#34;LSND gap&

S. T. Petcov

A general exact analytic expression for the probability of matter-enhanced two-neutrino transitions in a medium (MSW, RSFP, generated by neutrino FCNC interactions, etc.) is derived. The probability is expressed in terms of three real functions of the parameters of the transitions: the ``jump&#39;&#39; probability and two phases (angles). The results obtaine

Jianming Qian

This paper discusses supersymmetry discovery potential of the upgraded DØexperiment at the Tevatron $p\bar{p}$ collider. Six final states with large transverse energy (momentum) leptons or photons (with or without large transverse momentum imbalances) are studied. These final states are expected to have small backgrounds and are thereby ideal for new physics

S. Mallik, Krishnendu Mukherjee

Like the even chirality correlation functions of, say, the two vector currents, one can also consider odd chirality correlation functions to write thermal QCD sum rules. They contain fewer non-perturbative corrections, at least to the leading order. Here we write such a sum rule for the correlation function of vector and tensor &#39;currents&#39;. The odd an

D0 collaboration

We describe three recent results from D0 related to the top quark: a preliminary measurement of the t-tbar spin correlation in top quark pair production, a search for top quark decays into charged Higgs bosons, and an improved cross section analysis in the t-tbar -> e mu channel using neural networks.

P. Petroff

The D0 detector at The Fermilab Tevatron is undergoing a major upgrade to prepare for data taking with luminosities reaching 2 x 10^{32} cm^{-2} s^{-1}. The upgrade includes a new central tracking array, new muon detector components and electronic upgrades to many subsystems. The D0 upgraded detector will be operational for RUN II in spring 2000.

L. C. Garcia de Andrade, R. O. Ramos

The role of spin-torsion coupling to gravity is analyzed in the context of a model of chaotic inflation. The system of equations constructed from the Einstein-Cartan and inflaton field equations are studied and it is shown that spin-torsion interactions are effective only at the very first e-folds of inflation, becoming quickly negligible and, therefore, not

Anand Venkataraman

Because of rather fundamental changes to the underlying model proposed in the paper, it has been withdrawn from the archive.

T. K. Kopec, Jorge V. Jose

We study the quantum phase transition properties of a three-dimensional periodic array of Josephson junctions with charging energy that includes both the self and mutual junction capacitances. We use the phase fluctuation algebra between number and phase operators, given by the Euclidean group E_2, and we effectively map the problem onto a solvable quantum g

H. M. Fretwell, A. Kaminski, J. Mesot, J. C. Campuzano

We study the Fermi surface of Bi2Sr2CaCu2O8 (Bi2212) using angle resolved photoemission (ARPES) with a momentum resolution of ~ 0.01 of the Brillouin zone. We show that, contrary to recent suggestions, the Fermi surface is a large hole barrel centered at (pi,pi), independent of the incident photon energy.

V. Podzorov, M. Uehara, M. E. Gershenson, T. Y. Koo

We discovered an unprecedented magnitude of the 1/f noise near the Curie temperature Tc in low-Tc manganites. The scaling behavior of the 1/f noise and the resistance provides strong evidence of the percolation nature of the ferromagnetic transition in the polycrystalline samples. The step-like changes of the resistance with temperature, observed for single

A. Marco Saitta, Michael L. Klein

Common experience tells us that a knot significantly weakens the polymer strand in which it is tied, which in turn leads to more facile chain rupture under tensile loading. Using first-principles molecular dynamics calculations we describe the dynamical evolution of the radicals that form after chain rupture of a single knotted alkane molecule in their very

N. Fertig, A. Tilke, R. H. Blick, J. P. Kotthaus

We investigate the microscopic contact of a cell/semiconductor hybrid. The semiconductor is nanostructured with the aim of single channel recording of ion channels in cell membranes. This approach will overcome many limitations of the classical patch-clamp technique. The integration of silicon-based devices &#39;on-chip&#39; promises novel types of experimen

Philip B. Allen, Vasili Perebeinos

Because the ground state has cooperative Jahn-Teller order, electronic excitations in LaMnO$_3$ are predicted to self-trap by local rearrangement of the lattice. The optical spectrum should show a Franck-Condon series, that is, a Gaussian envelope of vibrational sidebands. Existing data are reinterpreted in this way. The Raman spectrum is predicted to have s

X. Wan, W. J. Kossler, C. E. Stronach, D. R. Noakes

Zero-field muon spin relaxation (ZF-$μ$SR) data for dilute spin magnetic systems have been widely interpreted with what is called a Kubo-Toyabe form based on a Lorentzian distribution of local field components. We derive here the proper magnetic field \textit{magnitude} distribution using independent and uncorrelated \textit{component} distributions. Our res

Hyeonjin Doh, Manfred Sigrist, B. K. Cho, Sung-Ik Lee

The coexistence of the superconductivity and magnetism in the Ho$_{1-x}$Dy$_x$Ni$_2$B$_2$C is studied by using Ginzburg-Landau theory. This alloy shows the coexistence and complex interplay of superconducting and magnetic order. We propose a phenomenological model which includes two magnetic and two superconducting order parameters accounting for the multi-b

B. M. Roehner

In this empirical paper we show that in the months following a crash there is a distinct connection between the fall of stock prices and the increase in the range of interest rates for a sample of bonds. This variable, which is often referred to as the interest rate spread variable, can be considered as a statistical measure for the disparity in lenders&#39;

Erik Aurell, Roberto Baviera, Ola Hammarlid, Maurizio Serva

We introduce a criterion how to price derivatives in incomplete markets, based on the theory of growth optimal strategy in repeated multiplicative games. We present reasons why these growth-optimal strategies should be particularly relevant to the problem of pricing derivatives. We compare our result with other alternative pricing procedures in the literatur

I. Shlimak, S. I. Khondaker, M. Pepper, D. A. Ritchie

Large positive (P) magnetoresistance (MR) has been observed in parallel magnetic fields in a single 2D layer in a delta-doped GaAs/AlGaAs heterostructure with a variable-range-hopping (VRH) mechanism of conductivity. Effect of large PMR is accompanied in strong magnetic fields by a substantial change in the character of the temperature dependence of the cond

Armelle Barelli, Jean Bellissard, Francisco Claro

We study the effect of a perpendicular uniform magnetic field on the dissipative conductivity of a rectangular lattice with anisotropic hopping, $t_x\neq t_y $. We show that the magnetic field may enhance dramatically the directional anisotropy in the conductivity. The effect is a measurable physical realization of Aubry&#39;s duality in Harper systems.

Andrew M. Martin, James F. Annett

We consider a model (100) interface between two d-wave superconductors. By solving the Bogoliubov de Gennes equation on a tight binding lattice, we study the properties of the interface as a function of the interface barrier. We contrast the two scenarios: (i) an order parameter phase difference of $θ=0$ across the interface, and (ii) a phase slip of $θ=π$ a

W. Kang, H. L. Stormer, K. W. Baldwin, L. N. Pfeiffer

The edge of a two-dimensional electron system (2DES) in a magnetic field consists of one-dimensional (1D) edge-channels that arise from the confining electric field at the edge of the specimen$^{1-3}$. The crossed electric and magnetic fields, E x B, cause electrons to drift parallel to the sample boundary creating a chiral current that travels along the edg

A. Anane, B. Raquet, S. von Molnar, L. Pinsard-Godart

Low frequency electrical noise measurements have been used to probe the electronic state of the perovskite-type manganese oxide Pr2/3Ca1/3MnO3 versus temperature and in the vicinity of the field-induced transition from the insulating, charge-ordered state (I-CO) to the metallic, ferromagnetic state (M-F). At high temperature we have observed a high level of

S. C. Glotzer, V. N. Novikov, T. B. Schroeder

Dynamical heterogeneity and the decoupling of diffusion and structural relaxation in a supercooled liquid is investigated in terms of a time-dependent, fourth-order density correlation function. The generalized susceptibility $χ_4(t)$ corresponding to this correlation function has a maximum at an intermediate time $t_4^*$, and both $t_4^*$ and $χ_4(t_4^*)$ g

D. L. Feng, W. J. Zheng, K. M. Shen, D. H. Lu

The Fermi surface of the Bi2212 system is systematically studied using a variety of photon energies. In addition to reconciling the conflicting reports on the Fermi surface of this important material, we identify almost perfectly nested Fermi surface segments parallel to the $(1,0)$ or $(0,1)$ direction. This general yet long overlooked feature of the Fermi

A. Juozapavicius, L. Urba, S. Caprara, A. Rosengren

The spin-1/2 quantum anisotropic XY spin chain in a transverse random magnetic field parallel to the z axis is numerically studied by means of the density-matrix renormalization group. The dependence of the spontaneous magnetization and the energy gap on both the strength of the random magnetic field and the factor of anisotropy is determined. The critical l

Stephen C. Creagh, Niall D. Whelan

We show that the pattern of tunnelling rates can display a vivid and regular pattern when the classical dynamics is of mixed chaotic/regular type. We consider the situation in which the dominant tunnelling route connects to a stable periodic orbit and this orbit is surrounded by a regular island which supports a number of quantum states. We derive an explici

F. K. Diakonos, D. Pingel, P. Schmelcher

We use a recently found parametrization of the solutions of the inverse Frobenius-Perron problem within the class of complete unimodal maps to develop a Monte-Carlo approach for the construction of one-dimensional chaotic dynamical laws with given statistical properties, i.e. invariant density and autocorrelation function. A variety of different examples are

S. R. Majewski, R. J. Patterson, D. I. Dinescu, W. Y. Johnson

We focus on two aspects of Omega Cen that are rather uncharacteristic of globular clusters: its metallicity distribution and its orbit. We use (1) a Washington (M-T_2,M)_o color-magnitude diagram containing 130,000 stars, (2) DDO51 photometry to separate out giants from field dwarfs, and (3) a mapping of (M-T_2,M-DDO51)_o colors to [Fe/H] to derive a metalli

Mikhail V. Medvedev, Ramesh Narayan

All axisymmetric self-similar equilibria of self-gravitating, rotating, isothermal systems are identified by solving the nonlinear Poisson equation analytically. There are two families of equilibria: (1) Cylindrically symmetric solutions in which the density varies with cylindrical radius as R^(-alpha), with 0 <= alpha <= 2. (2) Axially symmetric solutions i

Michael Loewenstein

X-ray observations of galaxy groups and clusters are inconsistent with the predictions of the simplest hierarchical clustering models, wherein non-baryonic and baryonic components are assembled together under the sole influence of gravity. These departures are in the sense that the intergalactic medium is hotter and more extended than expected, and become in

R. P. van der Marel, D. Zurek

We present preliminary results of an HST/NICMOS program to image merger remnants in the J, H and K bands. The nuclear brightness profiles for most sample galaxies are similar to those typical for elliptical galaxies, but some (including the well-studied NGC 3921 and 7252) have an unusually high luminosity density at small radii. This is consistent with the p

Ricardo P. Schiavon, Beatriz Barbuy, Gustavo Bruzual

Synthetic spectra for single-aged stellar populations of metallicities [M/H] = -0.5, 0.0 and +0.5, ages = 3 to 17 Gyrs, and initial mass function exponents x = 0.1 to 2.0 were built in the wavelength range 6000-10200 Angstrons. For such we have employed the grid of synthetic spectra described in Schiavon & Barbuy (1999), computed for the stellar parameters 2

Boudewijn F. Roukema

The significance to which the cosmic microwave background observations by the satellite COBE can be used to refute a specific observationally based hypothesis for the global topology (3-manifold) of the Universe is investigated, by a new method of applying the principle of matched circle pairs. Moreover, it is shown that this can be done without assuming Gau

M. Guainazzi, S. Molendi

Spatially-resolved spectroscopy of the elliptical galaxy M87 with the MECS instrument on board BeppoSAX demonstrates that the hard X-ray power-law tail, originally discovered by ASCA (Matsumoto et al 1996; Allen et al. 1999), originates in the innermost 2&#39;. Our results are consistent with it being produced in an Accretion Dominated Flow, although a subst