January 2001 arXiv papers — page 14

R. Drimmel, D. N. Spergel

We present a three dimensional model for the Milky Way fit to the far-infrared (FIR) and near-infrared (NIR) data from the COBE/DIRBE instrument for Galactic latitudes |b| < 30 degrees and to within 20 degrees of the Galactic center. Because of the low optical depth at 240 microns, the FIR emission traces the distribution of galactic dust in the Galaxy. We m

Chuan-Hung Chen, C. Q. Geng

We investigate the rare baryonic exclusive decays of $Λ_b\to Λl^+ l^- (l=e,μ,τ)$ with polarized $Λ$. Under the approximation of the heavy quark effective theory (HQET), in the standard model we derive the differential decay rates and various polarization asymmetries by including lepton mass effects. We find that with the long-distance effects the decay branc

S. Todo, H. Takayama, N. Kawashima

This is a reply to the comment by A. W. Sandvik (cond-mat/0010433) on our paper Phys. Rev. Lett. 84, 4204 (2000). We show that his data do not conflict with our data nor with our conclusions.

S. Iso, Y. Kimura, K. Tanaka, K. Wakatsuki

We derive a noncommutative U(1) and U(n) gauge theory on the fuzzy sphere from a three dimensional matrix model by expanding the model around a classical solution of the fuzzy sphere. Chern-Simons term is added in the matrix model to make the fuzzy sphere as a classical solution of the model. Majorana mass term is also added to make it supersymmetric. We con

R. Chatterjee, P. Banerjee, R. Shyam

We investigate the Coulomb breakup of the two-neutron halo nucleus 6He by extending the framework of the finite range post form distorted wave Born approximation theory introduced earlier for the description of the breakup of one-neutron halo nuclei. The model can use the realistic three-body wave function for the 6He ground state. Calculations have been per

J. Brian Pitts, W. C. Schieve

The inclusion of a flat metric tensor in gravitation permits the formulation of a gravitational stress-energy tensor and the formal derivation of general relativity from a linear theory in flat spacetime. Building on the works of Kraichnan and Deser, we present such a derivation using universal coupling and gauge invariance. Next we slightly weaken the assum

Ken-ji Hamada

Quantum geometry gives a regularization scheme-independent effective action, whoes equation of motion for the conformal mode has a stable de Sitter solution at the high-energy region where the coupling of the self-interactions of the traceless mode can be neglected because of the asymptotic freedom. However, the dynamics of the traceless mode suggests that i

Robert D. Pisarski

An alternate picture of the deconfined phase of gauge theories is described. Instead of a plasma, the theory is viewed as a condensate of Polyakov lines. The pressure is determined by an elementary mean field theory.

J. -M. Chung, B. K. Chung

We obtain finite parts (as well as $ε$-pole parts) of massive three-loop vacuum diagrams with three-point and/or four-point interaction vertices by reducing them to tetrahedron diagrams with both massive and massless lines, whose finite parts were given analytically in a recent paper by Broadhurst. In the procedure of reduction, the method of integration-by-

Dafang Zheng, Bing-Hong Wang

We study the statistical properties of the attendance time series corresponding to the number of agents making a particular decision in the minority game (MG). We focus on the analysis of the probability distribution and the autocorrelation function of the attendance over a time interval in the efficient phase of the game. In this regime both the probability

Yu. A. Markov, M. A. Markova

On the basis of the Blaizot-Iancu equations, which are a local formulation of the hard thermal loop (HTL) equations of motion for soft fluctuating quark and gluon fields and their induced sources, the coupled kinetic equations for plasminos and plasmons are obtained. The equality of matrix elements for nonlinear scattering of a plasmino by hard particles in

Aaron Bergman, Ori J. Ganor, Joanna L. Karczmarek

We examine the intersections, fluctuations and deformations of codimension two solitons in field theory on noncommutative $R^4$, in the limit of large noncommutativity. We find that holomorphic deformations are zero modes of flat branes, and we show that there is a zero mode localized at the intersection of two solitons.

Hiroto Kubotani

We discuss quantum dynamics in multi-dimensional non-linear systems. It is well-known that wave functions are localized in a kicked rotor model. However, coupling with other degrees of freedom breaks the localization. In order to clarify the difference, we describe the quantum dynamics by deterministic rigid trajectories, which are accompanied with the de Br

Martijn Wubs, L. G. Suttorp

The spontaneous emission rate of a radiating atom reaches its time-independent equilibrium value after an initial transient regime. In this paper we consider the associated relaxation effects of the spontaneous decay rate of atoms in dispersive and absorbing dielectric media for atomic transition frequencies near material resonances. A quantum mechanical des

Christian Kurtsiefer, Markus Oberparleiter, Harald Weinfurter

We report on a method for optimizing the collection of entangled photon pairs in type-II parametric fluorescence. With this technique, we detected 360000 polarization-entangled photon pairs per second in the near-IR region in single-mode optical fibers. The entanglement of the photon pairs was verified by measuring polarization correlations in different base

Peter Foldi, Attila Czirjak, Mihaly G. Benedict

We investigate the time evolution of a superposition of macroscopically distinct quantum states in a system of two-level atoms interacting with a thermal environment of photon modes. We show that the atomic coherent states are robust against decoherence, therefore we call their superpositions atomic Schrödinger cat states. The initial fast regime of the time

M. G. A. Paris, G. M. D&#39;Ariano, M. F. Sacchi

The maximum-likelihood method for quantum estimation is reviewed and applied to the reconstruction of density matrix of spin and radiation as well as to the determination of several parameters of interest in quantum optics.

S. Sivakumar, G. S. Agarwal

We demonstrate that it is possible to use the balanced homodyning with array detectors to measure the quantum state of correlated two-mode signal field. We show the applicability of the method to fields with complex mode functions, thus generalizing the work of Beck (Phys. Rev. Letts. 84, 5748 (2000)) in several important ways. We further establish that, und

Marc-Thierry Jaekel, Serge Reynaud

We study the situation where two point like mirrors are placed in the vacuum state of a scalar field in a two-dimensional spacetime. Describing the scattering upon the mirrors by transmittivity and reflectivity functions obeying unitarity, causality and high frequency transparency conditions, we compute the fluctuations of the Casimir forces exerted upon the

Marc-Thierry Jaekel, Serge Reynaud

A mirror in the vacuum is submitted to a radiation pressure exerted by scattered fields. It is known that the resulting mean force is zero for a motionless mirror, but not for a mirror moving with a non-uniform acceleration. We show here that this force results from a motional modification of the field scattering while being associated with the fluctuations

Marc-Thierry Jaekel, Serge Reynaud

The Casimir force can be understood as resulting from the radiation pressure exerted by the vacuum fluctuations reflected by boundaries. We extend this local formulation to the case of partially transmitting boundaries by introducing reflectivity and transmittivity coefficients obeying conditions of unitarity, causality and high frequency transparency. We sh

Yakir Aharonov, Berthold-Georg Englert

We show how one can ascertain the values of four mutually complementary observables of a spin-1 degree of freedom.

Berthold-Georg Englert, Christian Kurtsiefer, Harald Weinfurter

Upon entangling a spatial binary alternative of a photon with its polarization, one can use single photons to study arbitrary 2-qubit states. Sending the photon through a Mach-Zehnder interferometer, equipped with sets of wave plates that change the polarization, amounts to performing a unitary transformation on the 2-qubit state. We show that any desired un

Andrei Khrennikov

We provide frequency probabilistic analysis of perturbations of physical systems by preparation procedures. We obtained the classification of possible probabilistic transformations connecting input and output probabilities that can appear in physical experiments. We found that so called quantum probabilistic rule is just one of possible rules. Besides the we

J. Rehacek, L. Mista, J. Fiurasek, J. Perina

The coherence properties of two downconversion processes continuously coupled via idler beams are analyzed. We find that the amount of which-way information about a signal photon carried by idler beams periodically attains its maximum and minimum in the course of evolution. In correspondence with the famous experiments by Mandel&#39;s group on the induced co

M. Moseler, H. Hakkinen, R. N. Barnett, U. Landman

The properties of neutral and anionic Pd_N clusters were investigated with spin-density-functional calculations. The ground state structures are three-dimensional for N>3 and they are magnetic with a spin-triplet for 2<=N<=7 and a spin nonet for N=13 neutral clusters. Structural- and spin-isomers were determined and an anomalous increase of the magnetic mome

A. Kuzmich, A. Dogariu, L. J. Wang, P. W. Milonni

We consider pulse propagation in a linear anomalously dispersive medium where the group velocity exceeds the speed of light in vacuum (c) or even becomes negative. A signal velocity is defined operationally based on the optical signal-to-noise ratio, and is computed for cases appropriate to the recent experiment where such a negative group velocity was obser

M. Martinis

The presence of low dimensional chaos in the protein secondary structures, using the binary coded $α$-helices and $β$-sheet motifs, has been investigated. In order to analyse symbolic DNA/RNA sequences the assignment, based on the purine/pyrimidine and strong/wea k H - bond classification sheme, of binary numbers to the nucleotides was made. We have found th

Rajan Dogra

The effect of stellar aberration seems to be one of the simplest phenomena in astronomical observations. But there is a large literature about it betraying a problem of asymmetry between observer motion and source motion. This paper addresses the problem from the point of view of Euclidean space-time, arising from the proposition that stellar aberration (or

Alexander K. Guts

We introduce two time: deterministic Newton time-stream t and stochastic time-epoch $τ$. The relation of uncertainty for time-epoch of physical events $ΔτΔD \geq c_1,\eqno(*)$ where $c_1=const$, is proved. The function $D(t)= - c_1\frac{d}{dt}\ln f_τ(t),$ characterizes {\it velocity of disorganization} of the event-phenomena; $f_τ(t)$ is density of probabili

S. Typel, G. Baur

We investigate higher order effects in electromagnetic dissociation of neutron halo nuclei using a simple and realistic zero range model for the neutron-core interaction. In the sudden (or Glauber) approximation all orders in the target-core interaction are taken into account. Small deviations from the sudden approximation are readily calculated. We obtain v

E. Oset, D. Cabrera, H. C. Chiang, C. Garcia Recio

In this talk we briefly describe some basic elements of chiral perturbation theory, $χPT$, and how the implementation of unitarity and other novel elements lead to a better expansion of the $T$ matrix for meson meson and meson baryon interactions. Applications are then done to the $ ππ$ interaction in nuclear matter in the scalar and vector channels, antikao

A. Ramos, S. Hirenzaki, S. S. Kamalov, T. T. S. Kuo

We present recent progress on the properties of antikaons in nuclei and dense nuclear matter as obtained from two {\bar K}N interaction models: one based on the lowest-order meson-baryon chiral lagrangian and the other derived from a meson-exchange picture.

V. I. Isakov, K. I. Erokhina, H. Mach, M. Sanchez-Vega

By the use of the latest experimental data on the spectra of $^{133}$Sb and $^{131}$Sn and on the analysis of properties of other odd nuclei adjacent to doubly magic closed shells the isospin dependence of a mean spin-orbit potential is defined. Such a dependence received the explanation in the framework of different theoretical approaches.

T. Frick, S. Kaiser, H. Müther, A. Polls

$Δ$ isobar components in the nuclear many-body wave function are investigated for the deuteron, light nuclei (${}^{16}O$) and infinite nuclear matter within the framework of the coupled-cluster theory. The predictions derived for various realistic models of the baryon-baryon interaction are compared to each other. These include local ($V28$) and non-local me

Yang Sun, Jing-ye Zhang, Mike Guidry

Interplay of collective and single-particle degrees of freedom is a common phenomenon in strongly correlated many-body systems. Despite many successful efforts in the study of superdeformed nuclei, there is still unexplored physics that can be best understood only through the nuclear magnetic properties. We point out that study of the gyromagnetic factor (g-

P. D. Miller, S. R. Clarke

Under certain mode-matching conditions, small-amplitude waves can be trapped by coupling to solitons of nonlinear fields. We present a model for this phenomenon, consisting of a linear equation coupled to the Korteweg-de Vries equation. The model has one parameter, a coupling constant. For one value of the coupling constant the model becomes the linearized K

Michael Lassig, Ugo Bastolla, Susanna C. Manrubia, Angelo Valleriani

We study the statistics of ecosystems with a variable number of co-evolving species. The species interact in two ways: by prey-predator relationships and by direct competition with similar kinds. The interaction coefficients change slowly through successful adaptations and speciations. We treat them as quenched random variables. These interactions determine

Niall MacKay, Liu Zhao

A Yang-Baxter relation-based formalism for generalized quantum affine algebras with the structure of an infinite Hopf family of (super-) algebras is proposed. The structure of the infinite Hopf family is given explicitly on the level of $L$ matrices. The relation with the Drinfeld current realization is established in the case of $4\times4$ $R$-matrices by s

L. Kluge, E. Paal, J. Stasheff

In 1963 [Ann. of Math. {\bf 78}, 267-288], Gerstenhaber invented a \emph{comp(osition)} calculus in the Hochschild complex of an associative algebra. In this paper, the first steps of the Gerstenhaber theory are exposed in an abstract (comp system) setting. In particular, as in the Hochschild complex, a graded Lie algebra and a pre-coboundary operator can be

G. Felder, A. Varchenko

This is the talk of the second author at the meeting &#34;Topological Methods in Physical Sciences&#34;, London, November 2000. We review our work on KZB equations.

Ciprian Pop

We show that elements of unital $C^*$-algebras without tracial states are finite sums of commutators. Moreover, the number of commutators involved is bounded, depending only on the given $C^*$-algebra.

Daniel Krob, Ekaterina Vassilieva

This paper is devoted to the presentation of a combinatorial approach for analyzing the performance of an important modulation protocol used in mobile telecommunications. We show in particular that a fundamental formula, in this context, is in fact highly connected with a slight modification of a very classical algorithm of Knuth that realizes a bijection be

Edwin J. Beggs

In this paper we extend the standard differential geometric theory of Hamiltonian dynamics to noncommutative spaces, beginning with symplectic forms. Derivations on the algebra are used instead of vector fields, and interior products and Lie derivatives with respect to derivations are discussed. Then the Poisson bracket of certain algebra elements can be def

Juergen Jost, Yuan-Long Xin

We obtain a Bernstein theorem for special Lagrangian graphs in n-dimensional complex space for arbitrary n only assuming bounded slope, but no quantitative restriction.

Matilde Marcolli, Bai-Ling Wang

We establish the exact triangle in Seiberg-Witten-Floer theory relating the monopoloe homologies of any two closed 3-manifolds which are obtained from each other by $\pm 1$-surgery. We also show that the sum of the modified version of the Seiberg-Witten invariants for any closed rational homology 3-sphere $Y$ over all $Spin^c$ structures equals to $\frac 12

Bernard Shiffman, Mikhail Zaidenberg

In this note we show that there are algebraic families of hyperbolic, Fermat-Waring type hypersurfaces in P^n of degree 4(n-1)^2, for all dimensions n>1. Moreover, there are hyperbolic Fermat-Waring hypersurfaces in P^n of degree 4n^2-2n+1 possessing complete hyperbolic, hyperbolically embedded complements.

Uwe Trittmann

In this note we address the problem of solving for the positronium mass spectrum. We use front-form dynamics together with the method of flow equations. For a special choice of the similarity function, the calculations can be simplified by analytically integrating over the azimuthal angle. One obtains an effective Hamiltonian and we solve numerically for its

A. Fring

We provide a brief characterization of the main features of the homogeneous sine-Gordon models and discuss a general construction principle for colour valued S-matrices, associated to a pair of simply laced Lie algebras, which contain the homogeneous sine-Gordon models as a subclass. We give a brief introduction to the thermodynamic Bethe ansatz and the form

P. B. Gilkey, K. Kirsten, D. V. Vassilevich

We study the spectral geometry of an operator of Laplace type on a manifold with a singular surface. We calculate several first coefficients of the heat kernel expansion. These coefficients are responsible for divergences and conformal anomaly in quantum brane-world scenario.

Massimo Bianchi, Jose F. Morales

We discuss the interplay between IR and UV divergences in vacuum configurations with open and unoriented strings. We establish a general one-to-one correspondence between anomalies and R-R tadpoles associated to sectors with non-trivial Witten index. The result does not require any supersymmetry to be preserved by the configuration. Under very mild condition

Wen-Fa Lu, Chul Koo Kim, Jae Hyung Yee, Kyun Nahm

A Rayleigh-Schrödinger perturbation theory based on the Gaussian wavefunctional is constructed. The method can be used for calculating the energies of both the vacuum and the excited states. A model calculation is carried out for the vacuum state of the $λϕ^4$ field theory.

Yuji Igarashi, Katsumi Itoh, Hiroto So

Recently we made a proposal for realization of an effective BRS symmetry along the Wilsonian renormalization group flow. In this paper we show that the idea can be naturally extended for the most general gauge theories. Extensive use of the antifield formalism is made to reveal some remarkable structure of the effective BRS symmetry. The average action defin

J. -M. Chung, B. K. Chung

Using the Fock-Schwinger proper time method, we calculate the induced Chern-Simons term arising from the Lorentz- and CPT-violating sector of quantum electrodynamics with a $b_μ\barψγ^μγ_5 ψ$ term. Our result to all orders in $b$ coincides with a recent linear-in-$b$ calculation by Chaichian et al. [hep-th/0010129 v2]. The coincidence was pointed out by Chun

M. Cvetic, G. W. Gibbons, H. Lu, C. N. Pope

We obtain regular deformed D2-brane solutions with fractional D2-branes arising as wrapped D4-branes. The space transverse to the D2-brane is a complete Ricci-flat 7-manifold of G_2 holonomy, which is asymptotically conical with principal orbits that are topologically CP^3 or the flag manifold SU(3)/(U(1) x U(1)). We obtain the solution by first constructing

D. A. Demir, Ernest Ma

The recently proposed model of using the dynamical phase of the gluino to solve the strong CP problem is shown to admit a specific realization in terms of fundamental singlet superfields, such that the breaking of supersymmetry occurs only at the TeV scale, despite the large axion scale of 10^{9} to 10^{12} GeV. Phenomenological implications are discussed.

A. S. Khrykin

The energy spectrum for high energy $γ$-rays ($E_γ\geq 10$ MeV) from the process $pp \to γγX$ emitted at $90^0$ in the laboratory frame has been measured at an energy below the pion production threshold, namely, at 216 MeV. The resulting photon energy spectrum extracted from $γ- γ$ coincidence events consists of a narrow peak at a photon energy of about 24 M

P. A. Grassi, T. Hurth

We present an analysis of the two-loop amplitude of the muon decay in the Standard Model (SM) using algebraic renormalization techniques. In addition, we discuss a manifestly BRST invariant IR regulator for the photon within the SM.

I. M. Dremin, O. V. Ivanov, V. A. Nechitailo

This review paper is intended to give a useful guide for those who want to apply discrete wavelets in their practice. The notion of wavelets and their use in practical computing and various applications are briefly described, but rigorous proofs of mathematical statements are omitted, and the reader is just referred to corresponding literature. The multireso

H. B. Nielsen, Y. Takanishi

We present a model based on our favourite gauge group which we call Anti-GUT and which in its extended form to be applied for neutrinos in the see-saw picture consists in that we have for each family separately a set of gauge fields as in the Standard Model plus a gauged (B-L)-charge. It may function as a concrete model manifestation of the type of model sug

J. R. Andersen, V. Del Duca, S. Frixione, C. R. Schmidt

We critically examine the definition of dijet cross sections at large rapidity intervals in hadron-hadron collisions, taking proper account of the various cuts applied in a realistic experimental setup. We argue that the dependence of the cross section on the precise definition of the parton momentum fractions and the presence of an upper bound on the moment

A. Bialas, H. Navelet, R. Peschanski

An explicit analytic formula for the transverse and longitudinal impact factors S_{T,L}(N,γ) of the photon using k_T factorization with exact gluon kinematics is given. Applications to the QCD dipole model and the extraction of the unintegrated gluon structure function from data are proposed.

C. Wetterich

An exact renormalization group equation describes the dependence of the free energy on an infrared cutoff for the quantum or thermal fluctuations. It interpolates between the microphysical laws and the complex macroscopic phenomena. We present a simple unified description of critical phenomena for O(N)-symmetric scalar models in two, three or four dimensions

M. M. Mühlleitner

The heavy Higgs bosons $H,A$ of the minimal supersymmetric extension of the Standard Model can be produced as resonances in high-energy $γγ$ colliders. Prospects of the search for these particles in $b\bar b$ and neutralino-pair final states are studied in this report. Heavy Higgs bosons can be found with masses up to about 70-80% of the initial $e^+e^-$ col

C. Bloechinger, H. Fraas, T. Mayer, G. Moortgat-Pick

We study the different linear collider modes with regard to the determination of the gaugino mass parameter M_1. In a specific mSUGRA inspired scenario we compare four processes with polarized beams: (a) e+ e- --> neutralino_1 neutralino_2 --> neutralino_1 neutralino_1 e+ e-, (b) e- gamma --> neutralino_1 selectron_{L/R} --> neutralino_1 neutralino_1 e-, (c)

Andrea Banfi, Giulia Zanderighi

We present the perturbative (PT) and non-perturbative (NP) analysis of the cumulative out-of-event-plane momentum distribution in e+e- annihilation in the near-to-planar three-jet region. A physical interpretation based on simple QCD considerations and kinematical relations will be given, with the aim of extending the described techniques to other multi-jet

R. Pittau

I review the most recent progresses in the calculation of four-fermion processes in electron-positron collisions

Shingo Kiyoura, Yasuhiro Okada

We calculate the ratio of the two branching ratios, Br(h -> bb-bar) and Br(h -> cc-bar) + Br(h -> gg), in the minimal supersymmetric standard model taking into account the SUSY-loop corrections to the Higgs sector and the hbb-bar vertex. We show that the heavy Higgs mass can be extracted from the ratio, almost independently of other SUSY parameters, in the r

Eung Jin Chun

Lepton flavor violation in various sectors of the theory can bring important effects on neutrino masses and mixing through wave function renormalization. We examine general conditions for flavor structure of radiative corrections producing the atmospheric and solar neutrino mass splittings from degenerate mass patterns. Also obtained are the mixing angle rel

Junegone Chay

I consider nonleptonic decays of B mesons into two light mesons using the light-cone wave functions for the mesons. In the heavy quark limit, nonfactorizable contributions are calculable from first principles in some decay modes. I review the idea of the QCD-improved factorization method and discuss the implications in phenomenology.

M. Battaglia, M. Caccia, S. Borghi, R. Campagnolo

In order to fully exploit the Physics potential of future e+ e- linear collider, a Vertex Detector providing high resolution track reconstruction is required. Hybrid Silicon pixel detectors are an attractive option for the sensor technology due to their read-out speed and radiation hardness but have been so far limited by the achievable single point resoluti

Pedro Marronetti

We present approximate analytical solutions to the Hamiltonian and momentum constraint equations, corresponding to systems composed of two black holes with arbitrary linear and angular momentum. The analytical nature of these initial data solutions makes them easier to implement in numerical evolutions than the traditional numerical approach of solving the e

M. Bojowald, H. A. Kastrup

Symmetric states are defined in the kinematical sector of loop quantum gravity and applied to spherical symmetry and homogeneity. Consequences for the physics of black holes and cosmology are discussed.

Andrey Neronov

We consider ``brane universe&#39;&#39; with nonzero tension in the models with large extra dimensions. We find exact solutions of higher-dimensional Einstein equations with single flat Minkowsky brane of arbitrary large tension (or brane cosmological constant) and compact extra dimensions. The brane curves the bulk space-time in a small region around it. The

Thomas A. Henzinger, Rupak Majumdar, Jean-Francois Raskin

We define five increasingly comprehensive classes of infinite-state systems, called STS1--5, whose state spaces have finitary structure. For four of these classes, we provide examples from hybrid systems.

Paul Hildreth, Chris Kimble, Peter Wright

Modern commercial organisations are facing pressures which have caused them to lose personnel. When they lose people, they also lose their knowledge. Organisations also have to cope with the internationalisation of business forcing collaboration and knowledge sharing across time and distance. Knowledge Management (KM) claims to tackle these issues. This pape

K. Malarz

In this work we investigate influence of substrate temperature on the surface morphology for substrate coverage below one monolayer. The model of film growth is based on random deposition enriched by limited surface diffusion. Also anisotropy in the growth is involved. We found from computer simulations for simple cubic lattice and solid-on-solid model, that

D. Kuhn, N. M. Chtchelkatchev, G. B. Lesovik, G. Blatter

We analyze the transport through a narrow ballistic superconductor-normal- metal-superconductor Josephson contact with non-ideal transmission at the superconductor-normal-metal interfaces, e.g., due to insulating layers, effective mass steps, or band misfits (SIN interfaces). The electronic spectrum in the normal wire is determined through the combination of

Thorsten Emig, Mehran Kardar

The statistical properties of a two dimensional lattice of elastic lines in a random medium are studied using the Bethe ansatz. We present a novel mapping of the dilute random line lattice onto the weak coupling limit of a pure Bose gas with delta-function interactions. Using this mapping, we calculate the cumulants of the free energy in the dilute limit exa

Aditi Mitra, S. M. Girvin

Kang et al. have recently observed a remarkable zero-bias anomaly in the spectrum for electron tunneling between two 2D electron gases separated laterally by a narrow but high barrier in the presence of a perpendicular quantising magnetic field. We argue that this is a result of interedge phase coherence analogous to the interlayer phase coherence in quantum

S. V. Shulga

The interpretation of optical conductivity in the normal and superconducting states is considered in the frame of the standard Isotropic Single wide Band (ISB) model using the theory proposed by Nam. The exact analytical inversion of the normal state Nam equations is performed and applied for the recovery of the reliable information from the experimental dat

A. D. Mirlin, E. Tsitsishvili, P. Woelfle

Commensurability oscillations in the magnetoresistivity of a two-dimensional electron gas in a two-dimensional lateral superlattice are studied in the framework of quasiclassical transport theory. It is assumed that the impurity scattering is of small-angle nature characteristic for currently fabricated high-mobility heterostructures. The shape of the modula

F. Findeis, M. Baier, A. Zrenner, M. Bichler

By use of magneto-photoluminescence spectroscopy we demonstrate bias controlled single-electron charging of a single quantum dot. Neutral, single, and double charged excitons are identified in the optical spectra. At high magnetic fields one Zeeman component of the single charged exciton is found to be quenched, which is attributed to the competing effects o

D. Rodney, A. Finel

We present a general formalism for incorporating dislocations in Phase Field methods. This formalism is based on the elastic equivalence between a dislocation loop and a platelet inclusion of specific stress-free strain related to the loop Burgers vector and normal. Dislocations are thus treated as platelet inclusions and may be coupled dynamically to any ot

H. M. Ronnow, D. F. McMorrow, R. Coldea, A. Harrison

The magnetic excitation spectrum in the two-dimensional (2D) S=1/2 Heisenberg antiferromagnet copper deuteroformate tetradeuterate (CFTD) has been measured for temperatures up to T\sim J/2, where J=6.31+-0.02 meV is the 2D exchange coupling. For T\ll J, a dispersion of the zone boundary energy is observed, which is attributed to a wavevector dependent quantu

Lorenzo Giada, Matteo Marsili

We discuss a new approach to data clustering. We find that maximum likelihood leads naturally to an Hamiltonian of Potts variables which depends on the correlation matrix and whose low temperature behavior describes the correlation structure of the data. For random, uncorrelated data sets no correlation structure emerges. On the other hand for data sets with

A. Weisse, J. Loos, H. Fehske

Inspired by the strong experimental evidence for the coexistence of localized and itinerant charge carriers close to the metal-insulator transition in the ferromagnetic phase of colossal magnetoresistive manganese perovskites, for a theoretical description of the CMR transition we propose a two-phase scenario with percolative characteristics between equal-de

A. Weisse, J. Loos, H. Fehske

Schwinger bosons allow for an advantageous representation of quantum double-exchange. We review this subject, comment on previous results, and address the transition to the semiclassical limit. We derive an effective fermionic Hamiltonian for the spin-dependent hopping of holes interacting with a background of local spins, which is used in a related publicat

M. Heiskanen, T. Torsti, M. J. Puska, R. M. Nieminen

A general real-space multigrid algorithm for the self-consistent solution of the Kohn-Sham equations appearing in the state-of-the-art electronic-structure calculations is described. The most important part of the method is the multigrid solver for the Schroedinger equation. Our choice is the Rayleigh quotient multigrid method (RQMG), which applies directly

I. M. Sokolov

The relaxation to equilibrium in many systems which show strange kinetics is described by fractional Fokker-Planck equations (FFPEs). These can be considered as phenomenological equations of linear nonequilibrium theory. We show that the FFPEs describe the system whose noise in equilibrium funfills the Nyquist theorem. Moreover, we show that for subdiffusive

C. Di Castro, M. Grilli, S. Caprara

We discuss how the quantum-critical-point scenario for high-T_c superconductors with density-driven charge order or stripe formation finds support from recent EXAFS experiments. Our phase diagram has the interesting feature, which is also suggested by the EXAFS experiments, that some cuprates may not show well-formed stripe phase. We also consider the extens

S. K. Ghose, B. N. Dev

Microstructural characterization of synthetic periodic multilayers by x-ray standing waves have been presented. It has been shown that the analysis of multilayers by combined x-ray reflectometry (XRR) and x-ray standing wave (XSW) techniques can overcome the deficiencies of the individual techniques in microstructural analysis. While interface roughnesses ar

Fabio Cecconi, Cristian Micheletti, Paolo Carloni, Amos Maritan

Drug resistance to HIV-1 Protease involves accumulation of multiple mutations in the protein. Here we investigate the role of these mutations by using molecular dynamics simulations which exploit the influence of the native-state topology in the folding process. Our calculations show that sites contributing to phenotypic resistance of FDA-approved drugs are

H. -J. Schmidt, J. Schnack, Marshall Luban

We prove that for a wide class of quantum spin systems with isotropic Heisenberg coupling the energy eigenvalues which belong to a total spin quantum number S have upper and lower bounds depending at most quadratically on S. The only assumption adopted is that the mean coupling strength of any spin w.r.t. its neighbours is constant for all N spins. The coeff

M. Roy, J. F. Mitchell, A. P. Ramirez, P. Schiffer

We present a detailed magnetothermal study of Pr$_{0.7}$Ca$_{0.3}$MnO$_{3}$, a perovskite manganite in which an insulator-metal transition can be driven by magnetic field, but also by pressure, visible light, x-rays, or high currents. We find that the field-induced transition is associated with a large release of energy which accounts for its strong irrevers

P. Benetatos, M. C. Marchetti

We derive a hydrodynamic model for a liquid of arbitrarily curved flux-lines and vortex loops using the mapping of the vortex liquid onto a liquid of relativistic charged quantum bosons in 2+1 dimensions recently suggested by Tesanovic and by Sudbo and collaborators. The loops in the flux-line system correspond to particle-antiparticle fluctuations in the bo

V. J. Goldman, E. V. Tsiper

Comment on A.M.Chang et al, PRL 86, 143 (2001).

Jean-Philippe Bouchaud, Andrew Matacz, Marc Potters

We investigate quantitatively the so-called leverage effect, which corresponds to a negative correlation between past returns and future volatility. For individual stocks, this correlation is moderate and decays exponentially over 50 days, while for stock indices, it is much stronger but decays faster. For individual stocks, the magnitude of this correlation

P. M. Duxbury, J. H. Meinke

Two attractive and often used ideas, namely universality and the concept of a zero temperature fixed point, are violated in the infinite-range random-field Ising model. In the ground state we show that the exponents can depend continuously on the disorder and so are non-universal. However, we also show that at finite temperature the thermal order parameter e

Ralf Klessen

Identifying the processes that determine strength, duration and variability of protostellar mass growth is a fundamental ingredient of any theory of star formation. I discuss protostellar mass accretion rates dM/dt from numerical models which follow molecular cloud evolution from turbulent fragmentation towards the formation of stellar clusters. In a dense c