April 2002 arXiv papers — page 20

Andre de Carvalho, Toby Hall

Global results are proved about the way in which Boyland's forcing partial order organizes a set of braid types: those of periodic orbits of Smale's horseshoe map for which the associated train track is a star. This is a special case of a conjecture introduced in a previous paper, which claims that forcing organizes all horseshoe braid types into lin

J. Scott Carter, Angela Harris, Marina Appiou Nikiforou, Masahico Saito

The theory of quandle (co)homology and cocycle knot invariants is rapidly being developed. We begin with a summary of these recent advances. One such advance is the notion of a dynamical cocycle. We show how dynamical cocycles can be used to color knotted surfaces that are obtained from classical knots by twist-spinning. We also demonstrate relations between

Jan Paseka

The Morita equivalence of m-regular involutive quantales in the context of the theory of Hilbert $A$-modules is presented. The corresponding fundamental representation theorems are shown. We also prove that two commutative m-regular involutive quantales are Morita equivalent if and only if they are isomorphic

Christopher Deninger, Wilhelm Singhof

We construct real polarizable Hodge structures on the reduced leafwise cohomology of Kähler-Riemann foliations by complex manifolds. As in the classical case one obtains a hard Lefschetz theorem for this cohomology. Serre's Kählerian analogue of the Weil conjectures carries over as well. Generalizing a construction of Looijenga and Lunts one obtains poss

Christopher Deninger

We discuss analogies between number theory and the theory of dynamical systems on spaces with a one-codimensional foliation. The emphasis is on comparing the "explicit formulas" of analytic number theory with certain dynamical Lefschetz trace formulas. We also point out a possible relation between an Arakelov-Euler characteristic and an Euler charact

L. Dorcak

This contribution deals with the creation of numerical models for the simulation of the dynamic characteristics of fractional-order control systems and their comparison with analytical models. We give the results of the comparison of dynamic properties in fractional- and integer-order systems with a controller, designed for an integer-order system as the bes

B. V. Rajarama Bhat, Tirthankar Bhattacharyya, Santanu Dey

We introduce a notion called `maximal commuting piece' for tuples of Hilbert space operators. Given a commuting tuple of operators forming a row contraction there are two commonly used dilations in multivariable operator theory. Firstly there is the minimal isometric dilation consisting of isometries with orthogonal ranges and hence it is a noncommuting

Andrey Marenich

Among eight possible geometric structures on three-dimensional manifolds less studied from the differential geometric point of view are those modelled on the Heisenberg group $Heis^3$. We consider the Heisenberg left-invariant metric and use some results on Levi-Civita connection and curvature tensor to present solutions of equations for geodesic lines in th

Victor Kreiman, V. Lakshmibai

The Richardson variety $X_w^v$ is defined to be the intersection of the Schubert variety $X_w$ and the opposite Schubert variety $X^v$. For $X_w^v$ in the Grassmannian, we obtain a standard monomial basis for the homogeneous coordinate ring of $X_w^v$. We use this basis first to prove the vanishing of $H^i(X_w^v,L^m)$, $i > 0 $, $m \geq 0$, where $L$ is the

William H. Rowan

The Dedekind-Birkhoff theorem for finite-height modular lattices has previously been generalized to complete modular lattices using the theory of regular coverings. In this paper, we investigate regular coverings in lattices of filters and lattices of ideals, and the regularization strategy--embedding the lattice into its lattice of filters or lattice of ide

Shinichi Deguchi, Yousuke Kokubo

We discuss a quantum-theoretical aspect of the massive Abelian antisymmetric tensor gauge theory with antisymmetric tensor current. To this end, an Abelian rank-2 antisymmetric tensor field is quantized both in the covariant gauge with an arbitrary gauge parameter and in the axial gauge of the Landau type. The covariant quantization yields the generating fun

Kentaroh Yoshida

We discuss a phase structure of compact QED in four dimensions by considering the theory as a perturbed topological model. In this scenario we use the singular configuration with an appropriate regularization, and so obtain the results similar to the lattice gauge theory due to the effect of topological objects. In this paper we calculate the thermal pressur

Scott Thomas

Gravitational holography is argued to render the cosmological constant stable against divergent quantum corrections. This provides a technically natural solution to the cosmological constant problem. Evidence for quantum stability of the cosmological constant is illustrated in a number of examples including, bulk descriptions in terms of delocalized degrees

N. Okamura

We study physics possibility of Very Long Base-Line (VLBL) Neutrino-Oscillation Experiments with the High Intensity Proton Accelerator, which will be completed by the year 2007 in Tokai-village, Japan. As a target, a 100 kton-level water-Cerenkov detector is considered at 2,100 km away. Assuming the pulsed narrow-band nu_mu beams, we study sensitivity of suc

Ashutosh V. Kotwal, Stefan Hofmann

We analyze the allowed energy levels of Hawking radiation from Schwarzschild surfaces in space-times with large extra dimensions. From the requirement that the wave functions associated with these particles be single-valued and obey radial boundary conditions, we derive an upper bound of their discrete energy spectrum as a function of the number of large ext

Michael Kramer, Davison E. Soper

Calculations of observables in quantum chromodynamics can be performed using a method in which all of the integrations, including integrations over virtual loop momenta, are performed numerically. We use the flexibility inherent in this method in order to perform next-to-leading order calculations for event shape variables in electron-positron annihilation i

Csaba Csaki, Joshua Erlich, Graham D. Kribs, John Terning

We consider a recent proposal by Dimopoulos and Kaplan to embed the electroweak SU(2)_L X U(1)_Y into a larger group SU(3)_W X SU(2) X U(1) at a scale above a TeV. This idea is motivated by the prediction for the weak mixing angle sin^2 theta_W = 1/4, which naturally appears in these models so long as the gauge couplings of the high energy SU(2) and U(1) gro

T. T. Takahashi, H. Suganuma, Y. Nemoto, H. Matsufuru

The static three-quark (3Q) potential is studied in detail using SU(3) lattice QCD with $12^3 \times 24$ at $β=5.7$ and $16^3 \times 32$ at $β=5.8$, 6.0 at the quenched level. For more than 300 different patterns of the 3Q systems, we perform the accurate measurement of the 3Q Wilson loop with the smearing method, which reduces excited-state contaminations,

Holger Stoeck

A proposal for a three-year program of charm and QCD physics with the CLEO detector operating in the range of sqrt{s} = 3 - 5 GeV is presented. The CLEO-c program will include studies of semileptonic and hadronic charm decays, as well as searches for gluonic matter in the area of nonpertubative QCD. In addition, spectroscopy of the Upsilon(1S), Upsilon(2S) a

The D0 Collaboration, V. M. Abazov

We have measured the W boson mass using the D0 detector and a data sample of 82 pb^-1 from the Tevatron collider. This measurement used W -> e nu decays, where the electron is close to a boundary of a central electromagnetic calorimeter module. Such 'edge' electrons have not been used in any previous D0 analysis, and represent a 14% increase in the W

Guowen Peng, Hongya Liu, Qiuyang Zhang

We extend the direct quantum approach of the standard FRW cosmology from 4D to 5D and obtain a Hamiltonian formulation for a wave-like 5D FRW cosmology. Using a late-time approximation we isolate out a y-part from the full wave function of the 5D Universe. Then we find that the compactness of the fifth dimension y yields a quantized spectrum for the momentum

Steven Bird

Phonology, as it is practiced, is deeply computational. Phonological analysis is data-intensive and the resulting models are nothing other than specialized data structures and algorithms. In the past, phonological computation - managing data and developing analyses - was done manually with pencil and paper. Increasingly, with the proliferation of affordable

Christopher Cieri, Steven Bird

Annotation graphs and annotation servers offer infrastructure to support the analysis of human language resources in the form of time-series data such as text, audio and video. This paper outlines areas of common need among empirical linguists and computational linguists. After reviewing examples of data and tools used or under development for each of severa

Maximillian Dornseif, Kay Schumann, Christian Klein

The IEEE 802.11b wireless ethernet standart has several serious security flaws. This paper describes this flaws, surveys wireless networks in the Cologne/Bonn area to get an assessment of the security configurations of fielded networks and analizes the legal protections provided to wireless ethernet operators by german law. We conclude that wireless ethernet

Steven Bird, Gary Simons

The process of documenting and describing the world's languages is undergoing radical transformation with the rapid uptake of new digital technologies for capture, storage, annotation and dissemination. However, uncritical adoption of new tools and technologies is leading to resources that are difficult to reuse and which are less portable than the conve

Karhan Akcoglu, Petros Drineas, Ming-Yang Kao

A universalization of a parameterized investment strategy is an online algorithm whose average daily performance approaches that of the strategy operating with the optimal parameters determined offline in hindsight. We present a general framework for universalizing investment strategies and discuss conditions under which investment strategies are universaliz

G. Papavassiliou, M. Pissas, M. Karayanni, M. Fardis

We report a detailed study of $^{11}$B and $^{27}$Al NMR spin-lattice relaxation rates ($1/T_1$), as well as of $^{27}$Al Knight shift (K) of Mg$_{1-x}$Al$_x$B$_2$, $0\leq x\leq 1$. The obtained ($1/T_1T$) and K vs. x plots are in excellent agreement with ab initio calculations. This asserts experimentally the prediction that the Fermi surface is highly anis

T. Schneider

To provide an understanding of the universal thermodynamic properties of cuprate superconductors, emerging from the empirical correlations and phase diagrams, we analyze them in terms of the scaling theory of finite temperature and quantum critical phenomena. The universal features are traced back to the existence of quantum critical lines, representing the

J. A. Gupta, D. D. Awschalom, Al. L. Efros, A. V. Rodina

Time-resolved Faraday rotation is used to study both transverse and longitudinal spin relaxation in chemically-synthesized CdSe nanocrystals (NCs) 22-80 Angstroms in diameter. The precession of optically-injected spins in a transverse magnetic field occurs at distinct frequencies whose assignment to electron and exciton spins is developed through systematic

J. Mimkes, Th. Fruend, G. Willis

Statistical models of economic distributions lead to Boltzmann distributions rather than a Pareto power law. This result is supported by two facts: 1. the distributions of income, car sales, marriages or jobs are a matter of chances and luck and not of reason! 2. Data for property, automobile sales, marriages and job markets were analyzed by two models: the

Christian Korff, Katherine A. Seaton

The leading excitations of the dilute $A_L$ model in regime 2 are considered using analytic arguments. The model can be identified with the integrable $ϕ_{1,2}$ perturbation of the unitary minimal series $M_{L,L+1}$. It is demonstrated that the excitation spectrum of the transfer matrix satisfies the same functional equations in terms of elliptic functions a

D. C. Hatton, J. A. C. Bland

Recently, there has been a revival of interest in mechanisms for changing the spin polarization of an electron beam on transmission through, or reflection from, a magnetic surface. An understanding of these mechanisms would allow the use of an electron beam as a polarized radiation probe for magnetic characterization, like light in MOKE and neutrons in PNR.

E. A. Shaner, S. A. Lyon

We have used optically excited ultrashort electrical pulses to measure the magnetoplasmon resonance of a two-dimensional electron gas formed in an AlGaAs/GaAs heterostructure at frequencies up to 200 gigahertz. This is accomplished by incorporating the sample into a guided wave probe operating in a pumped (^{3}He) system. We are able to detect the resonance

B Sriram Shastry, Brijesh Kumar

We discuss the recently discovered system $Sr Cu_2 (BO_3)_2$, a realization of an exactly solvable model proposed two decades earlier. We propose its interpretation as a Mott Hubbard insulator. The possible superconducting phase arising from doping is explored, and its nature as well as its importance for testing the RVB theory of superconductivity are discu

K. Kato, E. Nishibori, M. Takata, M. Sakata

In order to explore the origin of the Metal-Insulator (M-I) transition, the precise crystal structures of the hole-doped Mott insulator system, Y1-XCaXTiO3 (x=0.37, 0.39 and 0.41), are studied for the temperature range between 20K and 300K by the synchrotron radiation (SR) X-ray powder diffraction. For both Y0.63Ca0.37TiO3 and Y0.61Ca0.39TiO3 compositions, t

Mikko Alava

The avalanche properties of models that exhibit 'self-organized criticality' (SOC) are still mostly awaiting theoretical explanations. A recent mapping (Europhys. Lett.~53, 569) of many sandpile models to interface depinning is presented first, to understand how to reach the SOC ensemble and the differences of this ensemble with the usual depinning s

V. Krakoviack, C. Alba-Simionesco

We propose a detailed investigation of the schematic mode-coupling approach to experimental data, a method based on the use of simple mode-coupling equations to analyze the dynamics of supercooled liquids. Our aim here is to clarify different aspects of this approach that appeared so far uncontrolled or arbitrary, and to validate the results obtained from pr

D. Ghose, P. Karmakar

The phenomenon of potential sputtering of ultra-thin Pt films due to impact of 20 keV highly charged $Ar^{q+}$ (q = 3 - 8) ions has been investigated. The results show enhanced erosion of the Pt film with the increase of potential energy of the Ar projectile.

Christian Gruber, Séverine Pache

We consider the evolution of a system composed of $N$ non-interacting point particles of mass $m$ in a container divided in two regions by a movable adiabatic wall (adiabatic piston). In this talk we discuss the thermodynamic limit where the area $A$ of the container, the number $N$ of particles, and the mass $M$ of the piston go to infinity keeping $\frac{A

Takashi Kimura, Hiroyuki Tamura, Kazuhiko Kuroki, Kenji Shiraishi

Based on calculations using the local density approximation, we propose quantum wire networks with square and plaquette type lattice structures that form quantum dot superlattices. These artificial structures are well described by the Hubbard model. Numerical analysis reveals a superconducting ground state with transition temperatures $T_c$ of up to 90 mK fo

Ming-Chya Wu, Chin-Kun Hu

The Grassmann path integral approach is used to calculate exact partition functions of the Ising model on MxN square (sq), plane triangular (pt) and honeycomb (hc) lattices with periodic-periodic (pp), periodic-antiperiodic (pa), antiperiodic-periodic (ap) and antiperiodic-antiperiodic (aa) boundary conditions. The partition functions are used to calculate a

Kihong Kim, H. Lim, Dong-Hun Lee

We derive the invariant imbedding equations for plane electromagnetic waves propagating in stratified magnetic media, where both dielectric and magnetic permeabilities vary in one spatial direction in an arbitrary manner. These equations allow us to obtain the reflection and transmission coefficients of the waves and the field amplitudes inside the media exa

Yueh-Nan Chen, Der-San Chuu

We propose to measure Purcell effect by observing the current through a semeiconductor quantum dot embedded in a microcavity. An electron and a hole are injected separately into the quantum structure to form an exciton and then recombine radiatively. The stationary current is shown to be altered if one varies the cavity length or the exciton energy gap. Ther

A. V. Pogrebnyakov, X. H. Zheng, A. Kotcharov, J. E. Jones

The paper has been withdrawn

Yutaka Fujita, Craig L. Sarazin, Joshua C. Kempner, L. Rudnick

We present the analysis of a Chandra observation of the galaxy cluster Abell 133, which has a cooling flow core, a central radio source, and a diffuse, filamentary radio source which has been classified as a radio relic. The X-ray image shows that the core has a complex structure. The most prominent feature is a "tongue" of emission which extends fro

R. Vio, W. Wamsteker

It is the purpose of the paper to describe the virtues of time-frequency methods for signal processing applications, having astronomical time series in mind. Different methods are considered and their potential usefulness respectively drawbacks are discussed and illustrated by examples. As areas where one can hope for a successful application of joint time-f

Chien Y. Peng, Luis C. Ho, Chris D. Impey, Hans-Walter Rix

We present a two-dimensional (2-D) fitting algorithm (GALFIT) designed to extract structural components from galaxy images, with emphasis on closely modeling light profiles of spatially well-resolved, nearby galaxies observed with the Hubble Space Telescope. Our algorithm improves on previous techniques in two areas, by being able to simultaneously fit a gal

Naoto Kobayashi, Hiroshi Terada, Miwa Goto, Alan Tokunaga

1.02-1.16 micron spectra (R ~ 7,000) of the gravitationally lensed QSO APM 08279+5255 at z_em=3.911 were obtained during the commissioning run of IRCS, the 1-5 micron near-infrared camera and spectrograph for the Subaru 8.2 m Telescope. Strong MgII doublet at 2976,2800 angstrom and FeII (2600 angstrom), FeII (2587 angstrom) absorption lines at z_abs=2.974 we

Uma Gorti, David Hollenbach

We present the results of an investigation of the effects of Far Ultraviolet (FUV) radiation from hot early type OB stars on clumps in star-forming molecular clouds. Clumps in Photodissociation regions (PDRs) undergo external heating which, if rapid, creates strong photoevaporative mass flows off the clump surfaces, and drives shocks into the clumps, compres

S. Sembay, R. Edelson, A. Markowitz, R. G. Griffiths

The bright blazar Mkn 421 has been observed four times for uninterrupted durations of ~ 9 - 13 hr during the performance verification and calibration phases of the XMM-Newton mission. The source was strongly variable in all epochs, with variability amplitudes that generally increased to higher energy bands. Although the detailed relationship between soft (0.

Daniel J. Rolfe, Timothy M. C. Abbott, Carole A. Haswell

We present the results of a search for the donor star in the high inclination SU UMa type cataclysmic variable IY UMa. We detect absorption features in the near infrared consistent with an M type dwarf donor star. Using the skew mapping technique to exploit the velocity information provided by the 8183-8194 Angstrom Na I absorption doublet, we locate the abs

Lara Sidoli, Sandro Mereghetti

We present the results of a BeppoSAX observation of the black hole candidate GRS1758-258 carried out in 1997, while the source was in its low/hard state. The X-ray spectrum, simultaneously observed over the broad energy range from 0.1 to 200 keV, can be well described by a Comptonized emission model with electron temperature kT_e = 31.4 keV and optical depth

R. Guenther, W. Kley

We study the evolution of circumbinary disks surrounding classical T Tau stars. High resolution numerical simulations are employed to model a system consisting of a central eccentric binary star within an accretion disk. The disk is assumed to be infinitesimally thin, however a detailed energy balance including viscous heating and radiative cooling is applie

B. F. Liu, S. Mineshige, F. Meyer, E. Meyer-Hofmeister

We extended the disk corona model (Meyer & Meyer-Hofmeister 1994; Meyer, Liu, & Meyer-Hofmeister 2000a) to the inner region of galactic nuclei by including different temperatures in ions and electrons as well as Compton cooling. We found that the mass evaporation rate and hence the fraction of accretion energy released in the corona depend strongly on the ra

S. Pedraz, J. Gorgas, N. Cardiel, P. Sanchez-Blazquez

In this Paper we investigate the kinematical properties of early-type dwarfs by significantly enlarging the scarce observational sample so far available. We present rotation curves and mean velocity dispersions for four bright dwarf ellipticals and two dwarf lenticular galaxies in the Virgo cluster. Most of these galaxies exhibit conspicuous rotation curves.

Raymond E. White, Craig L. Sarazin, Shrinivas R. Kulkarni

The X-ray emission from normal elliptical galaxies has two major components: soft emission from diffuse gas and harder emission from populations of accreting (low-mass) stellar X-ray binaries (LMXB). If LMXB populations are tied to the field stellar populations in galaxies, their total X-ray luminosities should be proportional to the optical luminosities of

Tohru Nagao, Takashi Murayama, Yasuhiro Shioya, Yoshiaki Taniguchi

We investigate gas metallicity of narrow-line regions in narrow-line Seyfert 1 galaxies (NLS1s) and broad-line ones (BLS1s) in order to examine whether or not there is a difference in the gas metallicity between the two populations of Seyfert 1 galaxies. We apply two methods to study this issue. One is to use the emission-line flux ratio of [N II]6583/H_alph

T. Harko, K. S. Cheng

We analyze the general radiation emission mechanism from a charged particle moving in a curved inhomogeneous magnetic field. The consideration of the gradient makes the curved vacuum magnetic field compatible with the Maxwell equations and adds a non-trivial term to the transverse drift velocity and, consequently, to the general radiation spectrum. To obtain

John F. Beacom, Nicole F. Bell

Despite the fact that the solar neutrino flux is now well-understood in the context of matter-affected neutrino mixing, we find that it is not yet possible to set a strong and model-independent bound on solar neutrino decays. If neutrinos decay into truly invisible particles, the Earth-Sun baseline defines a lifetime limit of $τ/m \agt 10^{-4}$ s/eV. However

G. J. Galloway, S. Surya, E. Woolgar

We prove two theorems, announced in hep-th/0108170, for static spacetimes that solve Einstein's equation with negative cosmological constant. The first is a general structure theorem for spacetimes obeying a certain convexity condition near infinity, analogous to the structure theorems of Cheeger and Gromoll for manifolds of non-negative Ricci curvature.

R. Jesseit, T. Naab, A. Burkert

We use high resolution numerical simulations to investigate the adiabatic contraction of dark matter halos with a Hernquist density profile. We test the response of the halos to the growth of additional axisymmetric disk potentials with various central concentrations and the spherically symmetric potential of a softened point mass. Adding the potentials on t

Constantine Yannouleas, Uzi Landman, C. Brechignac, Ph. Cahuzac

Experimental and theoretical studies of fission of doubly-charged Li, Na, and K clusters in the low fissility regime reveal the strong influence of electronic shell effects on the fission products. The electronic entropy controls the quenching of the shell effects and the competition between magic-fragment channels, leading to a transition from favored chann

Jean-Pierre De Villiers, John F. Hawley

This paper presents results of three-dimensional simulations of global hydrodynamic instabilities in black hole tori, extending earlier work by Hawley to Kerr spacetimes. This study probes a three-dimensional parameter space of torus angular momentum, torus size, and black hole angular momentum. We have observed the growth of the Papaloizou-Pringle instabili

Jan Kort, Ralf Laemmel

We study one dimension in program evolution, namely the evolution of the datatype declarations in a program. To this end, a suite of basic transformation operators is designed. We cover structure-preserving refactorings, but also structure-extending and -reducing adaptations. Both the object programs that are subject to datatype transformations, and the meta

Gordon T. Richards, Daniel E. Vanden Berk, Timothy A. Reichard, Patrick B. Hall

Using a sample of 3814 quasars from the Sloan Digital Sky Survey, we confirm that high-ionization, broad, emission lines such as CIV are significantly blueshifted with respect to low-ionization, broad, emission lines such as MgII. CIV emission line peaks have a range of shifts from a redshift of 500 km/s to blueshifts well in excess of 2000 km/s as compared

Alon E. Faraggi, Richard Garavuso, Jose M. Isidro

The evidence for neutrino masses in atmospheric and solar neutrino experiments provides further support for the embedding of the Standard Model fermions in the chiral 16 SO(10) representation. Such an embedding is afforded by the realistic free fermionic heterotic-string models. In this paper we advance the study of these string models toward a non-perturbat

K. V. Krutitsky, K. -P. Marzlin, J. Audretsch

Light-induced nonlinear terms in the Gross-Pitaevskii equation arise from the stimulated coherent exchange of photons between two atoms. For atoms in an optical dipole trap this effect depends on the spatial profile of the trapping laser beam. Two different laser beams can induce the same trapping potential but very different nonlinearities. We propose a sch

Elise Gambetti-Césare, Dietmar Weinmann, Rodolfo A. Jalabert, Philipp Brune

We show that disorder increases the persistent current of a half-filled one-dimensional Hubbard-Anderson ring at strong interaction. This unexpected effect results from a perturbative expansion starting from the strongly interacting Mott insulator ground state. The analytical result is confirmed and extended by numerical calculations.

Thomas J. Maccarone, Paolo S. Coppi

We present the results of 16-s time scale spectral fits for Cygnus X-1 in the soft state and in the transition state, using a Comptonised blackbody plus an iron line. On these timescales, we find that that the continuum source flux can vary by factors 2-3 and that the iron line intensity appears to track these changes well, i.e., the inferred equivalent widt

Robert Fleischer, Joaquim Matias

We investigate allowed regions in observable space of B --> pi K, B_d --> pi^+pi^- and B_s --> K^+K^- decays, characterizing these modes in the Standard Model. After a discussion of a new kind of contour plots for the $B\toπK$ system, we focus on the mixing- induced and direct CP asymmetries of the decays B_d --> pi^+pi^- and B_s--> K^+K^-. Using experimenta

C. R. Allton, S. Ejiri, S. J. Hands, O. Kaczmarek

We propose a new method to investigate the thermal properties of QCD with a small quark chemical potential $μ$. Derivatives of the phase transition point with respect to $μ$ are computed at $μ=0$ for 2 flavors of p-4 improved staggered fermions with $ma=0.1,0.2$ on a $16^3\times4$ lattice. The resulting Taylor expansion is well behaved for the small values o

Jairo Sinova, T. Jungwirth, S. - R. Eric Yang, J. Kučera

We present a theory of the infrared conductivity and absorption coefficients of metallic (III,Mn)V ferromagnetic semiconductors. We find that the conductivity is dominated by inter-valence-band transitions that produce peaks at $\hbar ω\sim 220 {\rm meV}$ and obscure the broadened Drude peak. We demonstrate that transverse f-sum rule measurements can be used

Thomas J. Maccarone, Paolo S. Coppi

To better constrain the emission mechanism underlying the hard state of galactic black hole candidates, we use high-time resolution RXTE lightcurves for Cyg X-1 and GX 399-4 to compute two higher order variability statistics for these objects, the skewness and the Fourier bispectrum. Similar analyses, in particular using the skewness measure, have been attem

B. F. L. Ward

We present a new approach to quantum gravity starting from Feynman's formulation for the simplest example, that of a scalar field as the representative matter. We show that we extend his treatment to a calculable framework using resummation techniques already well-tested in other problems. Phenomenological consequences for Newton's law are described.

Fei Xue, Jiangfeng Du, Xianyi Zhou, Rongdian Han

Recently quantum states discrimination has been frequently studied. In this paper we study them from the other way round, the likeness of two quantum states. The fidelity is used to describe the likeness of two quantum states. Then we presented a scheme to obtain the fidelity of two unknown qubits directly from the integral area of the spectra of the assista

Wojciech Broniowski, Wojciech Florkowski

We show, by means of a simple compilation of the available experimental results, that the pT-spectra obtained at RHIC and SPS are strikingly similar up to pT ~ 1.5-2 GeV. In fact, the discrepancies between various experimental groups working at the same experiment are of the same size as the differences between RHIC and SPS. Our observation is complementary

O. Elgaroy, O. Lahav, W. J. Percival, J. A. Peacock

We constrain f_nu = Omega_nu / Omega_m, the fractional contribution of neutrinos to the total mass density in the Universe, by comparing the power spectrum of fluctuations derived from the 2dF Galaxy Redshift Survey with power spectra for models with four components: baryons, cold dark matter, massive neutrinos and a cosmological constant. Adding constraints

R. Skibinski, J. Golak, H. Kamada, H. Witala

Faddeev calculations have been performed for nucleon-deuteron photodisintegration of 3He(3H) and proton-deuteron radiative capture. The bulk of the results is based on the AV18 nucleon-nucleon force and the Urbana IX three-nucleon force together with explicit exchange currents or applying the Siegert approach. Three-nucleon force effects are predicted for bo

Josep Elgueta

We define a cohomology for an arbitrary $K$-linear semistrict semigroupal 2-category $(\mathfrak{C},\otimes)$ (called in the paper a Gray semigroup) and show that its first order (unitary) deformations, up to the suitable notion of equivalence, are in one-one correspondence with the elements of the second cohomology group. Fundamental to the construction is

S. Ciliberti, G. Caldarelli, V. Loreto, L. Pietronero

We address the problem of the role of the concept of local rigidity in the family of sandpile systems. We define rigidity as the ratio between the critical energy and the amplitude of the external perturbation and we show, in the framework of the Dynamically Driven Renormalization Group (DDRG), that any finite value of the rigidity in a generalized sandpile

Abha Dev, Margarita Safonova, Deepak Jain, Daksh Lohiya

A strictly linear evolution of the scale factor is a characteristic feature in several classes of alternative gravity theories. In this article we investigate the overall viability of an open linear coasting cosmological model. We report that this model is consistent with gravitational lensing statistics (within $1σ$) and accomodates old high-redshift galaxi

Takehiro Azuma, Hikaru Kawai

We present a formulation of a matrix model which manifestly possesses the general coordinate invariance when we identify the large $N$ matrices with differential operators. In order to build a matrix model which has the local Lorentz invariance, we investigate how the $so(9,1)$ Lorentz symmetry and the $u(N)$ gauge symmetry are mixed together. We first analy

H. J. Lee, J. H. Jung, K. W. Kim, M. W. Kim

We investigated the magnetic field (H)-dependent optical conductivity spectra of MgB2 thin film in the far-infrared region. The H-dependences can be explained by the increase of normal metallic regions embedded in the superconducting background. The area fraction of the normal metallic region increases rather quickly at low field, but slowly at high field. I

E. Cuevas

The system size dependence of the fluctuations in generalized inverse participation ratios (IPR's) $I_α(q)$ at criticality is investigated numerically. The variances of the IPR logarithms are found to be scale-invariant at the macroscopic limit. The finite size corrections to the variances decay algebraically with nontrivial exponents, which depend on th

O. Vilhu

A scenario for a periodic filling and emptying of the accretion disc of the microquasar GRS 1915+105 is proposed, by computing the mass transfer rate from the evolving low mass red giant donor (Greiner at al. 2001) and comparing it with the observed accretion rate onto the primary black hole. We propose a duty-cycle with (5-10)(eta/0.1) per cent active ON-st

S. Varlamov, G. Seibold

The recently observed bilayer splitting in high-T$_c$ cuprates is analyzed within a model where the charge carriers are coupled to a phenomenological bosonic spectrum which interpolates between the marginal Fermi liquid structure and collective mode type behavior as a function of temperature. We argue that the origin of the collective mode is probably associ

P. P. Rajeev, P. Taneja, P. Ayyub, A. S. Sandhu

We demonstrate a 13-fold increase in hard x-ray bremsstrahlung (10 - 200 keV) emitted by a copper plasma created by 100 fs, 806 nm pulses at $10^{14}-10^{15}$ Wcm$^{-2}$. This enhancement is achieved by roughening the target surface with copper nanoparticles of ~15 nm size. A simple model that invokes local field modifications by surface plasmon excitation a

Charanjit S. Aulakh

We discuss the embedding of R-Parity preserving Minimal Left Right Supersymmetric models into Pati-Salam and SO(10) GUTs.

Charanjit S. Aulakh, Aarti Girdhar

We present rules for rewriting SO(10) tensor and spinor invariants in terms of invariants of its ``Pati-Salam'' maximal subgroup (SU(4)$\times \rm{SU(2)}_L\times \rm{SU(2)}_R)$ supplemented by the discrete symmetry called D parity. Explicit decompositions of quadratic and cubic invariants relevant to GUT model building are presented and the role of D

Sergiy Libert, Vyacheslav Gorshkov, Vladimir Privman, Dan Goia

Monodispersed spherical cadmium sulfide particles were used as a model system in order to explain the size selection in the formation of colloids by aggregation of nanosize subunits. Several procedures of mixing the reactants were employed to precipitate these solids and follow the kinetics of particle growth. Efficient numerical simulation techniques for th

J. Raufeisen, J. -C. Peng, G. C. Nayak

In the kinematical region where the center of mass energy is much larger than all other scales, the Drell-Yan process can be formulated in the target rest frame in terms of the same color dipole cross section as low Bjorken-x deep inelastic scattering. Since the mechanisms for heavy dilepton production appear very different in the dipole approach and in the

Saurya Das, Randy Kobes, Gabor Kunstatter

We present the results of a detailed analysis of a general, unstructured adiabatic quantum search of a data base of $N$ items. In particular we examine the effects on the computation time of adding energy to the system. We find that by increasing the lowest eigenvalue of the time dependent Hamiltonian {\it temporarily} to a maximum of $\propto \sqrt{N}$, it

G. Mauro D'Ariano, Paoloplacido Lo Presti, Matteo G. A. Paris

We consider the problem of discriminating among a set of unitaries by means of measurements performed on the state undergoing the transformation. We show that use of entangled probes improves the discrimination in the two following cases: i) for a set of unitaries that are the UIR of a group and, ii) for any pair of transformations provided that multiple use

Dong Ruan, Weicheng Huang

Based upon the general supercharges which involve not only generators C_j of the Clifford algebra C(4,0) with positive metric, but also operators of third order, C_j C_k C_l, the general form of N=4 supersymmetric quantum mechanics (SSQM), which brings out the richer structures, is realized. Then from them, an one-dimensional physical realization and a new m

Aeysha Khalique, Farhan Saif

We suggest a quantum nondemolition scheme to measure a quantized cavity field state using scattering of atoms in general Bragg regime. Our work extends the QND measurement of a cavity field from Fock state, based on first order Bragg deflection [9], to any quantum state based on Bragg deflection of arbitrary order. In addition a set of experimental parameter

Iwo Bialynicki-Birula, Zofia Bialynicka-Birula

The method of generating a family of new solutions starting from any wave function satisfying the nonlinear Schrödinger equation in a harmonic potential proposed recently [ J. J. Garc\'ıa-Ripoll, V. M. Pérez-Garc\'ıa, and V. Vekslerchik, Phys. Rev. E {\bf 64}, 056602 (2001)] is extended to many-body theory of mutually interacting particles. Our metho

D. W. Leung

Nielsen [quant-ph/0108020] showed that universal quantum computation is possible given quantum memory and the ability to perform projective measurements on up to 4-qubits. We describe an improved method that requires only 2-qubit measurements, which are both sufficient and necessary. We present a method to partially collapse the $C_k$-hierarchy in the indire

H. Jeong, M. S. Kim

We suggest an entanglement purification scheme for mixed entangled coherent states using 50-50 beam splitters and photodetectors. This scheme is directly applicable for mixed entangled coherent states of the Werner type, and can be useful for general mixed states using additional nonlinear interactions. We apply our scheme to entangled coherent states decohe

Yao A. Houndonougbo, Brian B. Laird

We present a set of second-order, time-reversible algorithms for the isothermal (NVT) molecular-dynamics (MD) simulation of systems with mixed hard-core/continuous potentials. The methods are generated by combining real-time Nose' thermostats with our previously developed Collision Verlet algorithm [Mol. Phys. 98, 309 (1999)] for constant energy MD simul

V. A. Roudnev, S. L. Yakovlev, S. A. Sofianos

A method to calculate the bound states of three-atoms without resorting to an explicit partial wave decomposition is presented. The differential form of the Faddeev equations in the total angular momentum representation is used for this purpose. The method utilizes Cartesian coordinates combined with the tensor-trick preconditioning for large linear systems