November 2005 arXiv papers — page 38

V. P. Belavkin, R. L. Stratonovich

A model of quantum noisy channel with input encoding by a classical random vector is described. An equation of optimality is derived to determine a complete set of wave functions describing quantum decodings based on quasi-measurements maximizing the classical amount of transmitted information. A solution of this equation is found for the Gaussian multimode

Faisal Shah Khan, Marek Perkowski

Recent research in multi-valued logic for quantum computing has shown practical advantages for scaling up a quantum computer. Multivalued quantum systems have also been used in the framework of quantum cryptography, and the concept of a qudit cluster state has been proposed by generalizing the qubit cluster state. An evolutionary algorithm based synthesizer

Alberto Carlini, Akio Hosoya, Tatsuhiko Koike, Yosuke Okudaira

We present a general framework for finding the time-optimal evolution and the optimal Hamiltonian for a quantum system with a given set of initial and final states. Our formulation is based on the variational principle and is analogous to that for the brachistochrone in classical mechanics. We reduce the problem to a formal equation for the Hamiltonian which

Vladimir V. Kisil

We provide an answer to the long standing problem of mixing quantum and classical dynamics within a single formalism. The construction is based on p-mechanical derivation (quant-ph/0212101, quant-ph/0304023) of quantum and classical dynamics from the representation theory of the Heisenberg group. To achieve a quantum-classical mixing we take the product of t

Chaohong Lee, Elena A. Ostrovskaya

We propose a scheme for scalable and universal quantum computation using diatomic bits with conditional dipole-dipole interaction, trapped within an optical lattice. The qubit states are encoded by the scattering state and the bound heteronuclear molecular state of two ultracold atoms per site. The conditional dipole-dipole interaction appears between neighb

Jurgen Kroseberg, Alex Grillo, Forest Martinez-McKinney, Gavin Nesom

We report on progress in the development of the LSTFE2 prototype front-end ASIC geared towards the readout of silicon microstrip sensors in a Linear Collider detector. We also discuss progress in the design of the back-end digital architecture for this readout scheme.

Bruce A. Schumm

Basic scaling laws are used to compare the relative capabilities of gaseous and solid-state tracking. Conclusions are drawn in the context of physics processes expected to be at the focus of studies at the International Linear Collider.

A. Bondar, A. Buzulutskov, R. de Oliveira, L. Ropelewski

Controlled etching of copper electrodes in Gas Electron Multiplier foils allows a reduction of the material budget by more than a factor of two for a triple-GEM detector. Detectors making use of thinned foils provide performances similar to those obtained with standard devices: a gain above 10^4 for a double-GEM, with energy resolution of 27 % fwhm for 5.9 k

Ilia A. Solov'yov, Alexander V. Yakubovitch, Andrey V. Solov'yov, Walter Greiner

We have investigated the potential energy surfaces for alanine chains consisting of three and six amino acids. For these molecules we have calculated potential energy surfaces as a function of the Ramachandran angles Phi and Psi, which are widely used for the characterization of the polypeptide chains. These particular degrees of freedom are essential for th

M. Auzinsh, K. Blushs, R. Ferber, F. Gahbauer

The pure electric field level-crossing of m_F Zeeman sublevels of hyperfine F levels at two-step laser excitation was described theoretically and studied experimentally for the nD_3/2 states in Cs with n = 7,9, and 10, by applying a diode laser in the first 6S_1/2 to 6P_3/2 step and a diode or dye laser for the second 6P_3/2 to nD_3/2 step. Level-crossing re

E. Yurtsever, F. Calvo, D. J. Wales

The dynamics and thermodynamics of melting in two-dimensional Coulomb clusters is revisited using molecular dynamics and Monte Carlo simulations. Several parameters are considered, including the Lindemann index, the largest Lyapunov exponent and the diffusion constant. In addition to the orientational and radial melting processes, isomerizations and complex

Marijan Ribaric, Luka Sustersic

In 1892 H.A. Lorentz started the search for a classical equation of motion for pointlike charged particles that takes into account the radiation reaction force. This search culminated in the Lorentz-Abraham-Dirac equation of motion, which is not satisfactory since it exhibits self-acceleration causing runaway solutions. In spite of ongoing efforts for more t

Heiko J. Herrmann

The aim of this article is to show, how computer algebra can be used when applying Liu's procedure. Although Mathematica (a commercial product by Wolfram Research Inc.) is used, it is possible to use other computer algebra systems as well.

J. Rafelski, J. Letessier

We discuss how the dynamics of an exploding hot fireball of quark--gluon matter impacts the actual phase transition conditions between the deconfined and confined state of matter. We survey the chemical conditions prevailing at hadronization.

M. Rafalski, W. Satula, R. Wyss

The global mass dependence of the nuclear symmetry energy and its two basic ingredients due to the mean-level spacing and effective strength of the isovector mean-potential is studied within the Skyrme-Hartree-Fock model. In particular, our study determines the ratio of the surface-to-volume contributions to the nuclear symmetry energy to be ~1.6 and reveals

Jeffery T. Mitchell

The PHENIX Experiment at the Relativistic Heavy Ion Collider has performed a survey of momentum correlations ranging from 200 MeV/c to 7 GeV in $\sqrt{s_{NN}}$ = 200 GeV p+p, d+Au, Au+Au, and $\sqrt{s_{NN}}$ = 62 GeV Au+Au collisions. The correlations are measured separately for like-sign and unlike-sign pairs. Comparisons of the properties of the near-side

L. Yuan, L. Tang

In order to accept very forward angle scattering particles, Jefferson Lab HKS experiment uses an on-target zero degree dipole magnet. The usual spectrometer optics calibration procedure has to be modified due to this on-target field. This paper describes a new method to calibrate HKS spectrometer system. The simulation of the calibration procedure shows the

V. P. Belavkin

We show that the quantum stochastic unitary dynamics Langevin model for continuous in time measurements provides an exact formulation of the Heisenberg uncertainty error-disturbance principle. Moreover, as it was shown in the 80's, this Markov model induces all stochastic linear and non-linear equations of the phenomenological "quantum trajectories&#

O M Kiselev, S G Glebov

In this work we show that the capture into parametric resonance may be explained as the pitchfork bifurcation in the primary parametric resonance equation. We prove that the solution close to the moment of the capture is described by the Painleve-2 equation. We obtain the connection formulas for the asymptotic solution of the primary parametric resonance equ

S. Kupin, F. Peherstorfer, A. Volberg, P. Yuditskii

An original approach to the inverse scattering for Jacobi matrices was suggested in a recent paper by Volberg-Yuditskii. The authors considered quite sophisticated spectral sets (including Cantor sets of positive Lebesgue measure), however they did not take into account the mass point spectrum. This paper follows similar lines for the continuous setting with

Raymond Stora

Talk given at Symposium in Honor of Julius Wess on the Occasion of his 70th Birthday, 10-11 January 2005 at Max Planck Institute for Physics (Werner Heisenberg Institut) Fohringer Ring 6 - D-80805 MUENCHEN

Sonia Natale

We describe the exponent of a group-theoretical fusion category $\mathcal C = \mathcal C(G, ω, F, α)$ associated to a finite group $G$ in terms of group cohomology. We show that the exponent of $\C$ divides both $e(ω) \exp G$ and $(\exp G)^2$, where $e(ω)$ is the cohomological order of the 3-cocycle $ω$. In particular $\exp \C$ divides $(\dim \C)^2$.

K. Diederich

A discussion of methods of nonisotropic fine quantitative complex analysis on lineally convex domains of finite type is given. The needed support functions with best possible estimates are considered together with the estimation of their corresponding Leray sections with respect to nonisotropic pseudodistances. The most recent developments in this subject ar

Vestislav Apostolov, David M. J. Calderbank, Paul Gauduchon, Christina W. Tonnesen-Friedman

We study the construction and classification of weakly Bochner-flat (WBF) metrics (i.e., Kahler metrics with coclosed Bochner tensor) on compact complex manifolds. A Kahler metric is WBF if and only if its `normalized' Ricci form is a hamiltonian 2-form: such 2-forms were introduced and studied in previous papers in the series. It follows that WBF Kahler

Vestislav Apostolov, David M. J. Calderbank, Paul Gauduchon, Christina W. Tonnesen-Friedman

This paper concerns the explicit construction of extremal Kaehler metrics on total spaces of projective bundles, which have been studied in many places. We present a unified approach, motivated by the theory of hamiltonian 2-forms (as introduced and studied in previous papers in the series) but this paper is largely independent of that theory. We obtain a ch

Walter Bergweiler

It is shown that if two transcendental entire functions permute, and if one of them satisfies an algebraic differential equation, then so does the other one.

Patrick Dehornoy

Many natural counting problems arise in connection with the normal form of braids--and seem to have never been considered so far. Here we solve some of them by analysing the normality condition in terms of the associated permutations, their descents and the corresponding partitions. A number of different induction schemes appear in that framework.

Uwe Helmke, Joachim Rosenthal, Alex Wang

This paper studies the problem of pole assignment for symmetric and Hamiltonian transfer functions. A necessary and sufficient condition for pole assignment by complex symmetric output feedback transformations is given. Moreover, in the case where the McMillan degree coincides with the number of parameters appearing in the symmetric feedback transformations,

Fabienne Comte, Marie-Luce Taupin

We consider the regression model with errors-in-variables where we observe $n$ i.i.d. copies of $(Y,Z)$ satisfying $Y=f(X)+ξ, Z=X+σε$, involving independent and unobserved random variables $X,ξ,ε$. The density $g$ of $X$ is unknown, whereas the density of $σε$ is completely known. Using the observations $(Y\_i, Z\_i)$, $i=1,...,n$, we propose an estimator of

Peter Heinzner, Henrik Stoetzel

We consider actions of real Lie subgroups G of complex reductive Lie groups on Kaehlerian spaces. Our main result is the openness of the set of semistable points with respect to a momentum map and the action of G.

K. Diederich, T. Ohsawa

Non-existence theorems for Levi flat hypersurfaces have found great interest in the literature. The question next to this that has to be asked is, when existing Levi flat hypersurfaces are at least rigid under deformations. Here, the case of boundaries of disc bundles over certain compact Riemann surfaces is considered.

David W Farmer

We discuss the idea of a ``family of L-functions'' and describe various methods which have been used to make predictions about L-function families. The methods involve a mixture of random matrix theory and heuristics from number theory. Particular attention is paid to families of elliptic curve L-functions. We describe two random matrix models for el

Christian Dogbe

We derive and analyze the &#8216;SHE&#39; (Spherical Harmonics Expansion) type system of equations coupled in energy. We also show that diffusive behavior occurs on long time and distance scales and we determine the diffusion tensor. The analysis is based on the governing kinetic equations arising in electron transport in semiconductors<br> ----- Nous déduis

Bernard Roynette, Pierre Vallois, Marc Yor

Results of penalization of a one-dimensional Brownian motion $(X_t) $, by its one-sided maximum $\dis (S_t=\sup_{0 \leq u \leq t}X_u)$, which were recently obtained by the authors are improved with the consideration-in the present paper- of the asymptotic behaviour of the likewise penalized Brownian bridges of length $t$, as $t\to \infty$, or penalizations b

Mitsuyasu Hashimoto

Let $R$ be a Dedekind domain, $G$ an affine flat $R$-group scheme, and $B$ a flat $R$-algebra on which $G$ acts. Let $A \to B^G$ be an $R$-algebra map. Assume that $A$ is Noetherian. We show that if the induced map $K\otimes A\to (K\otimes B)^{K\otimes G}$ is an isomorphism for any algebraically closed field $K$ which is an $R$-algebra, then $S\otimes A\to (

Hiromichi Ohno

We prove that the mean entropy and the dynamical entropy are equal for generalized quantum Markov chains on gauge-invariant $C^*$-algebras.

Severino T. Melo, Cintia C. Silva

Let A denote the C*algebra of bounded operators on L2(R) generated by: (i) all multiplications a(M) by functions a\in C[-\infty,+\infty], (ii) all multiplications by 2π-periodic continuous functions and (iii) all Fourier multipliers F^{-1}b(M)F, where F denotes the Fourier transform and b is in C[-\infty,+\infty]. The Fredholm property for operators in A is

Dan Rutherford

We show that the ungraded ruling invariants of a Legendrian link can be realized as certain coefficients of the Kauffman polynomial which are non-vanishing if and only if the upper bound for the Bennequin number given by the Kauffman polynomial is sharp. This resolves positively a conjecture of Fuchs. Using similar methods a result involving the upper bound

J. J. Betancor, O. Ciaurri, T. Martínez, M. Pérez

Given $α> -1$, consider the second order differential operator in $(0,\infty)$, $$L_αf \equiv (x^2 \frac{d^2}{dx^2} + (2α+3)x \frac{d}{dx} + x^2 + (α+1)^2)(f), $$ which appears in the theory of Bessel functions. The purpose of this paper is to develop the corresponding harmonic analysis taking $L_α$ as the analogue to the classical Laplacian. Namely we study

T. D. Browning

This paper surveys recent progress towards the Manin conjecture for (singular and non-singular) del Pezzo surfaces. To illustrate some of the techniques available, an upper bound of the expected order of magnitude is established for a singular del Pezzo surface of degree four.

Trent Yeend

We introduce the notion of a topological higher-rank graph, a unified generalization of the higher-rank graph and the topological graph. Using groupoid techniques, we define the Toeplitz and Cuntz-Krieger algebras of topological higher-rank graphs, and show that the $C^*$-algebras defined are coherent with the existing theory.

R. Martinez Villa, M. Saorin

Killing of supports along subsets $\mathcal{U}$ of a group $G$ and regradings along certain maps of groups $ϕ:G&#39;\longrightarrow G$ are studied, in the context of group-graded algebras. We show that, under precise condition on $\mathcal{U}$ and $ϕ$, the graded module theories over the initial and the final algebras are functorially well-connected. Special

Vestislav Apostolov, David M. J. Calderbank, Paul Gauduchon, Christina W. Tonnesen-Friedman

This paper has been withdrawn in order to replace it by two separate submissions: 1. Hamiltonian 2-forms in Kahler geometry III: Extremal metrics and stability, math.DG/0511118; 2. Hamiltonian 2-forms in Kahler geometry IV: Weakly Bochner-flat Kahler manifolds, math.DG/0511119. As the titles indicate, the first paper covers the parts of this withdrawn submis

H. A. Helfgott, A. Venkatesh

We give new bounds for the number of integral points on elliptic curves. The method may be said to interpolate between approaches via diophantine techniques ([BP], [HBR]) and methods based on quasiorthogonality in the Mordell-Weil lattice ([Sil6], [GS], [He]). We apply our results to break previous bounds on the number of elliptic curves of given conductor a

T. D. Browning

We show that the number of non-trivial rational points of height at most $B$, that lie on the cubic surface $x_1x_2x_3=x_4(x_1+x_2+x_3)^2$, has order of magnitude $B(\log B)^6$. This agrees with the Manin conjecture.

R. Jackiw

Flat-space conformal invariance and curved-space Weyl invariance are simply related in dimensions greater than two. In two dimensions the Liouville theory presents an exceptional situation, which we here examine.

D. S. Kulshreshtha, Usha Kulshreshtha

After a brief introduction to D-brane actions, the constrained dynamics and the constraint quantization of some D-brane actions is considered.

I. Bakas

The geometric evolution equations provide new ways to address a variety of non-linear problems in Riemannian geometry, and, at the same time, they enjoy numerous physical applications, most notably within the renormalization group analysis of non-linear sigma models and in general relativity. They are divided into classes of intrinsic and extrinsic curvature

Yukiko Ohtake, Yuya Wakabayashi

We investigate the Kaluza--Klein (KK) spectrum of N=1 supersymmetric gauge theory compactified on a circle. We concentrate on a model with gauge group SU(2) and four massless matter fields in the fundamental representation. We derive the exact mass formula of KK modes by using Seiberg--Witten theory. From the mass formula and the D3-brane probe realization,

Diego Pavon, Winfried Zimdahl

We review the notion of holographic dark energy and assess its significance in the light of the well documented cosmic acceleration at the present time. We next propose a model of holographic dark energy in which the infrared cutoff is set by the Hubble scale. The model accounts for the aforesaid acceleration and, by construction, is free of the cosmic coinc

Nandinii Barbosa-Cendejas, Alfredo Herrera-Aguilar

We present a comparative analysis of localization of 4D gravity on a non Z_2-symmetric scalar thick brane in both a 5-dimensional Riemannian space time and a pure geometric Weyl integrable manifold. This work was mainly motivated by the hypothesis which claims that Weyl geometries mimic quantum behaviour classically. We start by obtaining a classical 4-dimen

C. I. Lazaroiu

We give a general construction of extended moduli spaces of topological D-branes as non-commutative algebraic varieties. This shows that noncommutative symplectic geometry in the sense of Kontsevich arises naturally in String Theory.

Artem R. Khabibullin, Nail R. Khusnutdinov, Sergey V. Sushkov

We consider the Casimir effect for quantized massive scalar field with non-conformal coupling $ξ$ in a spacetime of wormhole whose throat is rounded by a spherical shell. In the framework of zeta-regularization approach we calculate a zero point energy of scalar field. We found that depending on values of coupling $ξ$, a mass of field $m$, and/or the throat&

Minoru Eto, Muneto Nitta, Keisuke Ohashi, David Tong

Some years ago, Atiyah and Manton described a method to construct approximate Skyrmion solutions from Yang-Mills instantons. Here we present a dynamical realization of this construction using domain walls in a five-dimensional gauge theory. The non-abelian gauge symmetry is broken in each vacuum but restored in the core of the domain wall, allowing instanton

Carlo Ewerz, Otto Nachtmann

Starting from a genuinely nonperturbative formulation of photon-proton scattering we discuss which approximations and assumptions are required to obtain the dipole picture of high energy scattering.

Josip Trampetic

Decay rates of the B-meson are studied through charmless and strangless transitions into pi, rho, omega and gamma systems. The important features of these modes are their clean signatures. The CLEO II collaboration has recently reported the value BR(B^0 --> pi^+ pi^-) = (1.3_{-0.6}^{+0.8} +/- 0.2)x10^{-5}. This value test our approach to nonleptonic B-decays

M. Arneodo, M. Diehl

Diffractive reactions involving a hard scale can be understood in terms of quarks and gluons. These reactions have become a valuable tool for investigating the low-x structure of the proton and the behavior of QCD in the high-density regime, and they may provide a clean environment to study or even discover the Higgs boson at the LHC. In this paper we give a

B. Loiseau, A. Furman, R. Kaminski, L. Lesniak

The interplay of strong and weak decay amplitudes for B -> pion-pion-kaon and B -> kaon-antikaon-kaon, with the pion-pion and kaon-antikaon pairs interacting in isospin-0 S-wave, is analyzed for pion-pion effective mass from threshold to 1.2 GeV. To improve agreement with experiment of a factorization approach with some QCD corrections, addition of long-dist

Marzia Nardi

I discuss the current theoretical interpretation of the anomalous J/psi suppression and their comparison to the most recent experimental data.

T. K. Kuo, Lu-Xin Liu

We identified a set of four rephasing invariant parameters of the CKM matrix. They are found to exhibit hierarchies in powers of $λ^2$, from $λ^2$ to $λ^8$. It is shown that, at the present level of accuracy, only the first three parameters are needed to fit all available data on flavor physics.

Olaf Kittel, Federico von der Pahlen

We study chargino production at a muon collider with longitudinally polarized beams and center of mass energies around the heavy neutral Higgs boson resonances. We show that the interference of the CP even and CP odd Higgs bosons can be analyzed using the energy distributions of the lepton or W boson from the chargino two-body decays \tildeχ^\pm_j\to\ell^\mp

S. Capitani, K. Jansen, M. Papinutto, A. Shindler

We present a first Wilson twisted mass fermion calculation of the matrix element between pion states of the twist-2 operator, which is related to the the lowest moment < x > of the valence quark parton distribution function in a pion. Using Wilson twisted mass fermions in the quenched approximation we demonstrate that < x > can be computed at small pseudosca

Barak Bringoltz

We present a study of bulk thermodynamical quantities in the deconfined phase of pure lattice SU(N) gauge theories. We find that the deficit in pressure and entropy with respect to their free-gas values, for N=4,8, is remarkably close to that of SU(3). Th is suggests that understanding the strongly interacting nature of the deconfined phase, which is crucial

D. J. Antonio, K. C. Bowler, P. A. Boyle, M. A. Clark

We present results for some of the light baryon masses and their excited states in 2+1 flavour domain wall QCD. We considered several lattice spacings, with the DBW2 and Iwasaki gauge actions and different sea quark masses on a volume of $16^3\times32$ and a fifth dimension of size 8. All data were generated on the QCDOC machines. Despite large residual mass

F. De Soto, J. Carbonell, C. Roiesnel, Ph. Boucaud

We present the first results of a quantum field approach to nuclear models obtained by lattice techniques. Renormalization effects for fermion mass and coupling constant in case of scalar and pseudoscalar interaction lagrangian densities are discussed.

Hideo Suganuma, Kyosuke Tsumura, Noriyoshi Ishii, Fumiko Okiharu

We study the manifestly exotic tetraquark D$_{\rm s0}^{++}(cu\bar s \bar d)$ and the scalar tetraquark $f_0(ud \bar u \bar d)$ in SU(3)$_c$ anisotropic quenched lattice QCD with the $O(a)$-improved Wilson (clover) fermion with various quark masses including the idealized SU(4)$_f$ case. For $f_0(ud\bar u \bar d)$ etc., we only consider connected diagrams at

Rainer Bartoldus

In this article I report on new and updated measurements of the CP-violating parameter beta (phi_1), which is related to the phase of the Cabibbo-Kobayashi-Maskawa (CKM) quark-mixing matrix of the electroweak interaction. Over the past few years, beta has become the most precisely known parameter of the CKM unitarity triangle that governs the B system. The r

J. -E. Campagne

An optimization of the CERN-SPL beam line has been performed which leads to better sensitivities to the $θ\_{13}$ mixing angle and to the $δ\_{CP}$ violating phase than those advocated considering baseline scenario.

Thomas Corbitt, David Ottaway, Edith Innerhofer, Jason Pelc

We report on experimental observation of radiation-pressure induced effects in a high-power optical cavity. These effects play an important role in next generation gravitational wave (GW) detectors, as well as in quantum non-demolition (QND) interferometers. We measure the properties of an optical spring, created by coupling of an intense laser field to the

M. Kronberger, P. Teutsch, B. Alessi, M. Steine

An inspection of the DSS and 2MASS images of selected Milky Way regions has led to the discovery of 66 stellar groupings whose morphologies, color-magnitude diagrams, and stellar density distributions suggest that these objects are possible open clusters that do not yet appear to be listed in any catalogue. For 24 of these groupings, which we consider to be

Marc-Thierry Jaekel, Serge Reynaud

Experimental tests of gravity performed in the solar system show a good agreement with general relativity. The latter is however challenged by the Pioneer anomaly which might be pointing at some modification of gravity law at ranges of the order of the size of the solar system. We introduce a metric extension of general relativity which, while preserving the

Charles R. Keeton, A. O. Petters

We are developing a general, unified, and rigorous analytical framework for using gravitational lensing by compact objects to test different theories of gravity beyond the weak-deflection limit. In this paper we present the formalism for computing corrections to lensing observables for static, spherically symmetric gravity theories in which the corrections t

Marc-Thierry Jaekel, Serge Reynaud

Einstein gravitation theory can be extended by preserving its geometrical nature but changing the relation between curvature and energy-momentum tensors. This change accounts for radiative corrections, replacing the Newton gravitation constant by two running couplings which depend on scale and differ in the two sectors of traceless and traced tensors. The me

Bourgade Paul, Croissant Olivier

In this paper, we study a family of stochastic volatility processes; this family features a mean reversion term for the volatility and a double CEV-like exponent that generalizes SABR and Heston&#39;s models. We derive approximated closed form formulas for the digital prices, the local and implied volatilities. Our formulas are efficient for small maturities

Emanuel Diamant

We posit a new paradigm for image information processing. For the last 25 years, this task was usually approached in the frame of Treisman&#39;s two-stage paradigm [1]. The latter supposes an unsupervised, bottom-up directed process of preliminary information pieces gathering at the lower processing stages and a supervised, top-down directed process of infor

Ravi Kannan, Thorsten Theobald

We propose a new hierarchical approach to understand the complexity of the open problem of computing a Nash equilibrium in a bimatrix game. Specifically, we investigate a hierarchy of bimatrix games $(A,B)$ which results from restricting the rank of the matrix $A+B$ to be of fixed rank at most $k$. For every fixed $k$, this class strictly generalizes the cla

Young-Han Kim

We provide a counterexample to Cover&#39;s conjecture that the feedback capacity $C_\textrm{FB}$ of an additive Gaussian noise channel under power constraint $P$ be no greater than the nonfeedback capacity $C$ of the same channel under power constraint $2P$, i.e., $C_\textrm{FB}(P) \le C(2P)$.

Rina Panigrahy

In this paper we study the problem of finding the approximate nearest neighbor of a query point in the high dimensional space, focusing on the Euclidean space. The earlier approaches use locality-preserving hash functions (that tend to map nearby points to the same value) to construct several hash tables to ensure that the query point hashes to the same buck

A. E. Allahverdyan, K. G. Petrosyan

We study a model for a statistical network formed by interactions between its nodes and links. Each node can be in one of two states (Ising spin up or down) and the node-link interaction facilitates linking between the like nodes. For high temperatures the influence of the nodes on the links can be neglected, and we get the Ising ferromagnet on the random (E

Daniel Valdez-Balderas, David Stroud

Using Monte Carlo techniques, we study a simple model which exhibits a competition between superconductivity and other types of order in two dimensions. The model is a site-diluted XY model, in which the XY spins are mobile, and also experience a repulsive interaction extending to one, two, or many shells of neighbors. Depending on the strength and range of

N. A. Frederick, T. A. Sayles, S. K. Kim, M. B. Maple

The double superconducting transition in PrOs$_4$Sb$_{12}$, first observed in specific heat $C(T)$ measurements of single crystal samples, is the subject of an in-depth study. The double superconducting transitions of a batch of single crystals were measured before and after they were annealed for 5 days at $500^{\circ}$C, with no observed change. $C(T)$ mea

M. B. Hastings

We use series expansions to study dynamics of equilibrium and non-equilibrium systems on networks. This analytical method enables us to include detailed non-universal effects of the network structure. We show that even low order calculations produce results which compare accurately to numerical simulation, while the results can be systematically improved. We

Z. Rapti, A. Smerzi, K. Ø. Rasmussen, A. R. Bishop

It appears that thermally activated DNA bubbles of different sizes play central roles in important genetic processes. Here we show that the probability for the formation of such bubbles is regulated by the number of soft AT pairs in specific regions with lengths which at physiological temperatures are of the order of (but not equal to) the size of the bubble

Y. Tokiwa, A. Pikul, P. Gegenwart, F. Steglich

We present temperature and field dependent heat capacity and magnetization data taken at temperatures down to 50 mK and in an applied magnetic field up to 11.5 Tesla for YbAgGe, a heavy-fermion compound with a field induced quantum critical point. These data clearly indicate that the same electronic degrees of freedom are responsible for the features seen in

Cristiano De Michele, Antonio Scala, Rolf Schilling, Francesco Sciortino

We perform event-driven molecular dynamics simulations of a system composed by uniaxial hard ellipsoids for different values of the aspect-ratio and packing fraction . We compare the molecular orientational-dependent structure factors previously calculated within the Percus-Yevick approximation with the numerical results. The agreement between theoretical an

D. Espriu, A. Prats

We present an analysis of the gonihedric loop model, a reformulation of the two dimensional gonihedric spin model, using two different techniques. First, the usual regular lattice statistical physics problem is mapped onto a height model and studied analytically. Second, the gravitational version of this loop model is studied via matrix models techniques. Bo

Wenhao Wu, E. Bielejec

Electron transport and tunneling across the superconductor-insulator (SI) transition have been measured simultaneously for quench-condensed ultrathin amorphous beryllium films. The anomalous negative magnetoresistance previously observed in insulating films disappears when Mn impurities are introduced to the films, restoring a rather clean Efros-Shklovskii t

A. A. Katanin

The problem of the symmetry of the superconducting pairing and the form of the gap function in the electron-doped superconductors is reconsidered within the temperature-cutoff functional renormalization group approach combined with the Bethe-Salpeter equations. The momentum dependence of the order parameter for antiferromagnetic and superconducting instabili

Leonardo Spanu, Alberto Parola

We investigate spin dynamics in antiferromagnetic (AF) molecular rings at finite temperature in the presence of spin-phonon (s-p) interaction. We derive a general expression for the spin susceptibility in the weak s-p coupling limit and then we focus on the low-frequency behavior, in order to discuss a possible microscopic mechanism for nuclear relaxation in

C. Chiorescu, J. J. Neumeier, J. L. Cohn

The dc magnetization (M) and electrical resistivity (ρ) as functions of magnetic field and temperature are reported for a series of lightly electron dopedCa(1-x)La(x)MnO(3) (0<=x<=0.10) specimens for which magnetization [Phys. Rev. B {\bf 61}, 14319 (2000)] and scattering studies [Phys. Rev. B {\bf 68}, 134440 (2003)] indicate an inhomogeneous magnetic groun

K. -Y. Choi, V. P. Gnezdilov, P. Lemmens, L. Capogna

We report an inelastic light scattering study of single-crystalline NaCu$_2$O$_2$, a spin-chain compound known to exhibit a phase with helical magnetic order at low temperatures. Phonon excitations were studied as a function of temperature and light polarization, and the phonon frequencies are compared to the results of ab-initio lattice dynamical calculatio

A. Honecker, J. Richter

Spinless fermions on highly frustrated lattices are characterized by a lowest single-particle band which is completely flat. Concrete realizations are provided by the sawtooth chain and the kagome lattice. For these models a real-space picture is given in terms of localized states. Furthermore, we find a finite zero-temperature entropy for a suitable choice

Satoshi Nishimoto, Thomas Pruschke, Reinhard M. Noack

We investigate static and dynamical ground-state properties of the two-impurity Anderson model at half filling in the limit of vanishing impurity separation using the dynamical density-matrix renormalization group method. In the weak-coupling regime, we find a quantum phase transition as function of inter-impurity hopping driven by the charge degrees of free

J. Derr, G. Knebel, G. Lapertot, B. Salce

The intermediate valent systems TmSe and SmB6 have been investigated up to 16 and 18 GPa by ac microcalorimetry with a pressure (p) tuning realized in situ at low temperature. For TmSe, the transition from an antiferromagnetic insulator for p<3 GPa to an antiferromagnetic metal at higher pressure has been confirmed. A drastic change in the p variation of the

P. Lunkenheimer, R. Wehn, A. Loidl

In the present work, we provide further evidence for the applicability of a modified stretched-exponential behavior, proposed recently for the description of aging-time dependent data below the glass temperature [P. Lunkenheimer et al., Phys. Rev. Lett. 95 (2005) 055702]. We analyze time-dependent dielectric loss data in a variety of aging glasses, including

M. Ricker, F. Affouard, R. Schilling, M. Descamps

We have investigated the glassy behavior of a molecular crystal built up with chloroadamantane molecules. For a simple model of this molecule and a rigid fcc lattice a MD simulation was performed from which we obtained the dynamical orientational correlators $S_{λλ&#39;}({\bf{q}},t)$ and the ``self&#39;&#39; correlators $S_{λλ&#39;}^{(s)}(t)$, with $λ= (\ell

Haizhou Lu, Rong Lü, Bang-fen Zhu

By means of the non-equilibrium Green function and equation of motion method, the electronic transport is theoretically studied through a parallel-coupled double quantum dots(DQD) in the presence of the on-dot Coulomb correlation, with an emphasis put on the quantum interference. It has been found that in the Coulomb blockage regime, the quantum interference

M. Raczkowski, A. M. Oles, R. Fresard

Using a self-consistent Hartree-Fock approximation we investigate the relative stability of various stripe phases in the extended $t$-$t&#39;$-$U$ Hubbard model. One finds that a negative ratio of next- to nearest-neighbor hopping $t&#39;/t<0$ expells holes from antiferromagnetic domains and reinforces the stripe order. Therefore the half-filled stripes not

V. R. Misko, Sergey Savel&#39;ev, Franco Nori

We study the critical depinning current J_c, as a function of the applied magnetic flux Phi, for quasiperiodic (QP) pinning arrays, including one-dimensional (1D) chains and two-dimensional (2D) arrays of pinning centers placed on the nodes of a five-fold Penrose lattice. In 1D QP chains of pinning sites, the peaks in J_c(Phi) are shown to be determined by a

Sourin Das, Sumathi Rao, Diptiman Sen

We show that novel fixed points (characterized by matrices which specify the splitting of the currents at the junction) can be accessed in a system which contains a junction of three quantum Hall line junctions. For such a junction of fractional quantum Hall edge states, we find that it is possible for both the flower (single droplet) and islands (three drop