March 2002 arXiv papers — page 4

Fredrick Michael, M. D. Johnson

An open quantum system consists of leads connected to a device of interest. Within the nonequilibrium Green's function technique, we examine the replacement of leads by self-energies in continuum calculations. Our starting point is a formulation of the problem for continuum systems by T.E. Feuchtwang. In this approach there is considerable flexibility in

Eugene B. Kolomeisky, Robert M. Konik, Xiaoya Qi

We analyze ground-state properties of a large gated quantum dot coupled via a quantum point contact to a reservoir of one-dimensional interacting spinless electrons. We find that the classical step-like dependence of the dot population on the gate voltage is preserved under certain conditions. We point out that the problem is related to the classical one-dim

A. Lucarelli, S. Lupi, M. Ortolani, P. Calvani

The in-plane optical conductivity of seven La(2-x)Sr(x)CuO(4) single crystals with x between 0 and 0.15 has been studied from 30 to 295 K. All doped samples exhibit strong peaks in the far-infrared, which closely resemble those observed in Cu-O "ladders" with one-dimensional charge-ordering. The behavior with doping and temperature of the peak energy

R. D. Duncan, R. W. Cherng, C. A. R. Sa de Melo

We perform calculations relating the order parameter symmetry of organic quasi-one-dimensional superconductors to the bulk quasiparticle density of states and the bulk uniform spin susceptibility tensor at finite temperatures. Current experimental results suggest that some organic quasi-one-dimensional superconductors may exhibit triplet pairing symmetry. Th

Patrick N. McGraw, Michael Menzinger

We examine the large-network, low-loading behaviour of an attractor neural network, the so-called bistable gradient network (BGN). We use analytical and numerical methods to characterize the attractor states of the network and their basins of attraction. The energy landscape is more complex than that of the Hopfield network and depends on the strength of the

J. Wosnitza, J. Hagel, J. S. Qualls, J. S. Brooks

The magnetic-field, temperature, and angular dependence of the interlayer magnetoresistance of two different quasi-two-dimensional (2D) organic superconductors is reported. For $κ$-(BEDT-TTF)$_2$I$_3$ we find a well-resolved peak in the angle-dependent magnetoresistance at $Θ= 90^\circ$ (field parallel to the layers). This clear-cut proof for the coherent na

Ronald Dickman, Tania Tome, Mario J. de Oliveira

We study stochastic sandpile models with a height restriction in one and two dimensions. A site can topple if it has a height of two, as in Manna's model, but, in contrast to previously studied sandpiles, here the height (or number of particles per site), cannot exceed two. This yields a considerable simplification over the unrestricted case, in which th

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

A thin film technology compatible with multilayer device fabrication is critical for exploring the potential of the 39-K superconductor magnesium diboride for superconducting electronics. Using a Hybrid Physical-Chemical Vapor Deposition (HPCVD) process, it is shown that the high Mg vapor pressure necessary to keep the MgB$_2$ phase thermodynamically stable

Egidijus Anisimovas, F. M. Peeters

We calculate the equilibrium properties and the dynamic response of two vertically coupled circular quantum dots populated by particles of different electrical charge sign, i.e. electrons and holes. The equilibrium density profiles are obtained and used to compute the frequencies and oscillator strengths of magnetoplasma excitations. We find a strong couplin

Alvise De Col, Tanniemola B. Liverpool

We introduce a simple geometric model for a double-stranded and double-helical polymer. We study the statistical mechanics of such polymers using both analytical techniques and simulation. Our model has a single energy-scale which determines both the bending and twisting rigidity of the polymer. The helix melts at a particular temperature T_c below which the

G. Busiello, R. V. Saburova, V. G. Sushkova

The real part of the time-dependent ac susceptibility of the short-range Ising spin glass in a transverse field has been investigated at very low temperatures. We have used the quantum linear response theory and domain coarsening ideas of quantum droplet scaling theory. It is found that after a temperature quench to a temperature which is less than the spin

Steven C. Erwin, Sung-Hoon Lee, Matthias Scheffler

We use density-functional theory to describe the initial stages of Fe film growth on GaAs(001), focusing on the interplay between chemistry and magnetism at the interface. Four features appear to be generic: (1) At submonolayer coverages, a strong chemical interaction between Fe and substrate atoms leads to substitutional adsorption and intermixing. (2) For

C. Grimaldi, P. Ryser, S. Straessler

The piezoresistive response of granular metals under uniaxial strain is strongly dependent on the concentration of the conducting phase. Here we show that the piezoresistive anisotropy is reduced as the system approaches its percolation thresold, following a power law behavior in the critical region. We propose a simple relation between the conductance and t

A. A. Kordyuk, V. V. Nemoshkalenko

The discovery of high temperature superconductors (HTS) has led to understanding that, in order to explain and utilize the phenomenon, completely new physical approaches should be introduced at all scales: microscopic, mesoscopic, macroscopic. Leaving first two scales beyond the scope of the present paper we focus in the upper limit of the last one, the stud

F. A. Pinheiro, B. A. van Tiggelen

We have investigated multiple scattering of light in systems subject to magneto-chiral (MC) effects. Our medium consists of magneto-optically active dipoles placed in a chiral geometry under the influence of an external magnetic field. We have calculated, for the first time, the total and the differential scattering MC cross sections of this system, explicit

Serge Galam

The dynamics of spreading of the minority opinion in public debates (a reform proposal, a behavior change, a military retaliation) is studied using a diffusion reaction model. People move by discrete step on a landscape of random geometry shaped by social life (offices, houses, bars, and restaurants). A perfect world is considered with no advantage to the mi

J. Oviedo, D. R. Bowler, M. J. Gillan

Experimental observations of heteroepitaxial growth of Ge on Si(001) show a (2xn) reconstruction for sub-monolayer coverages, with dimer rows crossed by missing-dimer trenches. We present first-principles density-functional calculations designed to elucidate the energetics and relaxed geometries associated with this reconstruction. We also address the proble

C. Beneduce, H. L. Suo, P. Toulemonde, N. Musolino

The influence of the initial MgB2 grain size on critical current density, upper critical fields and irreversibility has been studied on Fe sheathed monofilamentary MgB2 tapes prepared by the Powder-In-Tube technique. The effect of the reduction of MgB2 grain size by ball milling was mainly to enhance both the critical current density, jc, and the irreversibi

Shi-JIe Yang, Yue Yu, Jin-Bin Li

We study the fractional quantum Hall states in the tilted magnetic field. A many-particle wavefunction of the ground state, which is similar to that of Laughlin's, is constructed in the Landau gauge. We show that in the limit of thermodynamics, the concept of composite fermion is still valid in presence of the in-plane field.

Roberto Trasarti-Battistoni

I introduce a new geometrical approach to thermo--statistical mechanics. Here I highlight the main physical ideas, and how do they translate into geometrical language. I contrast the present approach with previous thermo--statistical--geometrical formalisms, (pseudo-)Riemannian [Weinhold 1975; Ruppeiner 1979] as well as Euclidean [Gilmore 1984; Gross& Votyak

A. A. Clerk, S. M. Girvin, A. K. Nguyen, A. D. Stone

We study the quantum charge noise and measurement properties of the double Cooper pair resonance point in a superconducting single-electron transistor (SSET) coupled to a Josephson charge qubit. Using a density matrix approach for the coupled system, we obtain a full description of the measurement back-action; for weak coupling, this is used to extract the q

J. E. Gizis, I. N. Reid, S. L. Hawley

We present high-resolution echelle spectroscopy of 676 nearby M dwarfs. Our measurements include radial velocities, equivalent widths of important chromospheric emission lines, and rotational velocities for rapidly rotating stars. We identify several distinct groups by their H alpha properties, and investigate variations in chromospheric activity amongst ear

Matthew J. Lewis, Katherine Freese

We use the technique of wavelet analysis to quantitatively investigate the role of solar variability in forcing terrestrial climate change on solar cycle timescales (roughly 11 years). We examine the connection between mean annual solar irradiance, as reconstructed from sunspot and isotope records, and the climate, as proxied by two Northern Hemisphere surfa

Philip R. Maloney

Luminous water maser emission in the 6_(16)-5_(23) line at 22 GHz has been detected from two dozen galaxies. In all cases the emission is confined to the nucleus and has been found only in AGN, in particular, in Type 2 Seyferts and LINERs. I argue that most of the observed megamaser sources are powered by X-ray irradiation of dense gas by the central engine.

Almudena Alonso-Herrero, George H. Rieke, Marcia J. Rieke

We have used HST/NICMOS H-band narrow-band Pa-alpha (at rest 1.87micron) images to identify star clusters and HII regions respectively in a sample of 8 luminous infrared galaxies (LIRGs). These observations have revealed the presence of a large population of super star clusters (SSC) and bright HII regions. A significant fraction of the HII regions shows H-a

M. Rampp, R. Buras, H. -Th. Janka, G. Raffelt

Spherically symmetric simulations of stellar core collapse and post-bounce evolution are used to test the sensitivity of the supernova dynamics to different variations of the input physics. We consider a state-of-the-art description of the neutrino-nucleon interactions, possible lepton-number changing neutrino reactions in the neutron star, and the potential

S. Michael Fall

We review progress in understanding the formation of galactic disks in the standard cosmogonic scenario involving gravitational clustering of baryons and dark matter and dissipative collapse of the baryons. This scenario accounts remarkably well for the observed properties of galactic disks if they have retained most of the specific angular momentum they acq

Mario Hamuy, Jose Maza, Philip A. Pinto, M. M. Phillips

We report optical and infrared spectroscopic observations of the Type Ia SN 1999ee and the Type Ib/c SN 1999ex, both of which were hosted by the galaxy IC 5179. For SN 1999ee we obtained a continuous sequence with an unprecedented wavelength and temporal coverage beginning 9 days before maximum light and extending through day 42. Before maximum light SN 1999

S. Demers M. Dallaire P. Battinelli

We matched spectroscopically identified C stars (from low resolution objective prism surveys) in the Magellanic Clouds with 2MASS sources. We confirm that C stars show a large spread in absolute magnitudes, even in the Ks band. We show that the I and Ks magnitude distributions of a population of C stars (in the LMC) have a similar narrow dispersion if the C

T. Beckert, W. J. Duschl

We have calculated stationary models for accretion disks around super-massive black holes in galactic nuclei. Our models show that below a critical mass flow rate of ~3 10**-3 M_Edd advection will dominate the energy budget while above that rate all the viscously liberated energy is radiated. The radiation efficiency declines steeply below that critical rate

Douglas Swartz, Kajal Ghosh, Valery Suleimanov, Allyn Tennant

A Chandra ACIS-S imaging observation of the nearby galaxy M81 (NGC 3031) reveals 9 luminous soft X-ray sources. The local environments, X-ray spectral properties, and X-ray light curves of the sources are presented and discussed in the context of prevailing physical models for supersoft sources. It is shown that the sample falls within expectations based on

D. Herranz, J. Gallegos, J. L. Sanz, E. Martinez-Gonzalez

Wavelet-related techniques have proven useful in the processing and analysis of one and two dimensional data sets (spectra in the former case, images in the latter). In this work we apply adaptive filters, introduced in a previous work (Sanz et al. 2001), to optimize the detection and extraction of point sources from a one-dimensional array of time-ordered d

S. V. Bogovalov, D. V. Khangoulyan

We interpret the observed X-ray morphology of the central part of the Crab Nebula (torus + jets) in terms of the standard theory by Kennel and Coroniti (1984). The only new element is the inclusion of anisotropy in the energy flux from the pulsar in the theory. In the standard theory of relativistic winds, the Lorentz factor of the particles in front of the

Richard P. Nelson, John C. B. Papaloizou

We investigate the possible commensurabilities to be expected when two protoplanets in the Jovian mass range, gravitationally interacting with each other and an external protoplanetary disc, are driven by disc induced orbital migration of the outer protoplanet into a commensurability which is then maintained in subsequent evolution. We find that for a variet

Rubina Kotak, Marten H. van Kerkwijk, J. Christopher Clemens

We present a detailed analysis of time-resolved optical spectra of the ZZ Ceti white dwarf, HS 0507+0434B. Using the wavelength dependence of observed mode amplitudes, we deduce the spherical degree, l, of the modes, most of which have l=1. The presence of a large number of combination frequencies (linear sums or differences of the real modes) enabled us not

S. Nagataki, K. Kohri, S. Ando, K. Sato

We estimate the flux of the GRB neutrino background and compute the event rate at SK and TITAND in the collapsar model, assuming that GRB formation rate is proportional to the star formation rate. We find that the flux and the event rate depend sensitively on the mass-accretion rate. Although the detection of signals from GRBs seems to be difficult by SK, we

D Lynden-Bell

It is argued that jet modelers have given insufficient study to the natural magneto-static configurations of field wound up in the presence of a confining general pressure. Such fields form towers whose height grows with each twist at a velocity comparable to the circular velocity of the accretion disk that turns them. A discussion of the generation of such

M. Breger, K. M. Bischof

The majority of the well-studied Delta Scuti stars show frequency pairs in the power spectra with frequency separations less than 0.06 c/d(0.7 microHz) as well as amplitude variability. We examine the interpretation in terms of separate excited stellar pulsation modes,single modes with variable amplitudes, and observational problems. The variable-phase techn

M. Breger, A. A. Pamyatnykh

We examine the severe disagreement between the number of predicted and observed pulsation modes for Delta Scuti stars. The selection of nonradial modes trapped in the outer envelope is considered on the basis of kinetic energy arguments. The trapped l=1 modes for the star 4 CVn are in good, but not perfect agreement with the observations. The trapping of the

M. Jaroszynski

We present 18 binary lens candidates from OGLE-II database for seasons 1997-1999. The candidates have been selected by visual light curves inspection from the subsample of strong transient events; the same procedure gives 215 single lens candidates. Among the double lenses there are 12 cases interpreted as caustic crossing events. We compare the mass ratio a

R. Barnard, U. C. Kolb, J. P. Osborne

The XMM-Newton satellite has made four observations of the core of M31 as part of a survey that will span the entire galaxy. The majority of the X-ray emission is contributed by point sources, chiefly X-ray Binaries (XB). Exciting early results from a survey of time variability in three XMM exposures of the M31 core reveal XB exhibiting Sco X-1 like flaring,

Xinwu Cao

The limits on the mass of the black hole in 23 BL Lac objects are obtained from their luminosities of the broad emission line Hβon the assumption that broad emission lines are emitted from clouds ionized by the radiation of the accretion disk surrounding a black hole. The distribution of line luminosity L_{Hβ} of all these BL Lac objects suggests a bimodal n

Dmitry V. Strekalov, Matt Stowe, Maria V. Chekhova, Jonathan P. Dowling

The goal of this research is to determine and study a physical system that will enable a fast and intrinsically two-photon detector, which would be of interest for quantum information and metrology applications. We consider two types of two-photon processes that can be observed using a very faint, but quantum-correlated biphoton field. These are optical up-c

S. Mendelson, R. Vershynin

We solve Talagrand's entropy problem: the L_2-covering numbers of every uniformly bounded class of functions are exponential in its shattering dimension. This extends Dudley's theorem on classes of {0,1}-valued functions, for which the shattering dimension is the Vapnik-Chervonenkis dimension. In convex geometry, the solution means that the entropy o

Laura Ferrarese

The possibility that the masses of supermassive black holes (SBHs) correlate with the total gravitational mass of their host galaxy, or the mass of the dark matter halo in which they presumably formed, is investigated using a sample of 16 spiral and 20 elliptical galaxies. The bulge velocity dispersion, typically defined within an aperture of size less than

I. Horvath, S. J. Dong, T. Draper, F. X. Lee

We consider the lattice topological charge density introduced by Hasenfratz, Laliena and Niedermayer and propose its eigenmode expansion as a tool to investigate the structure of topological charge fluctuations in QCD. The resulting effective density is built from local chiralities studied previously. At every order of the expansion the density exactly sums

Atish Dabholkar, Shahrokh Parvizi

Dirichlet p-branes in the background of pp waves are constructed using the massive Green-Schwarz worldsheet action for open strings. These branes are localized at the origin and only for $p=7, 5, 3$ preserve half the supersymmetries. The spectrum of the brane theory is analyzed and is found to be in agreement with the spectrum of the small fluctuations of th

Yves André, Bruno Kahn, Peter O'Sullivan

For $K$ a field, a Wedderburn $K$-linear category is a $K$-linear category $\sA$ whose radical $\sR$ is locally nilpotent and such that $\bar \sA:=\sA/\sR$ is semi-simple and remains so after any extension of scalars. We prove existence and uniqueness results for sections of the projection $\sA\to \bar\sA$, in the vein of the theorems of Wedderburn. There ar

V. Moretti

Connes' functional formula of the Riemannian distance is generalized to the Lorentzian case using the so-called Lorentzian distance, the d'Alembert operator and the causal functions of a globally hyperbolic spacetime. As a step of the presented machinery, a proof of the almost-everywhere smoothness of the Lorentzian distance considered as a function

M. Lopez-Corredoira, Carlos M. Gutierrez

We present new spectroscopic observations of an old case of anomalous redshift--NGC 7603 and its companion. The redshifts of the two galaxies which are apparently connected by a luminous filament are z=0.029 and z=0.057 respectively. We show that in the luminous filament there are two compact emission line objects with z=0.243 and z=0.391. They lie exactly o

Manish Kumar

The existing methods to obtain an exact-fit polynomial does not give the resulting polynomial in its standard form, and further manipulations are needed to obtain that. The new method presented here gives the coefficients of the polynomial in the standard form directly. It is also possible to obtain the exact-fit exponential using a similar method. Part I of

Juan Garcia-Bellido, Raul Rabadan

In this paper we present a classification of possible dynamics of closed string moduli within specific toroidal compactifications of Type II string theories due to the NS-NS tadpole terms in the reduced action. They appear as potential terms for the moduli when supersymmetry is broken due to the presence of D-branes. We particularise to specific construction

K. Langanke, G. Martinez-Pinedo

Recent experimental data and progress in nuclear structure modeling have lead to improved descriptions of astrophysically important weak-interaction processes. The review discusses these advances and their applications to hydrostatic solar and stellar burning, to the slow and rapid neutron-capture processes, to neutrino nucleosynthesis, and to explosive hydr

S. Goette

We derive a formula for the eta invariants of equivariant Dirac operators on quotients of compact Lie groups, and for their infinitesimally equivariant extension. As an example, we give some computations for spheres.

L. Jonke, S. Meljanac

The algebra of observables of an N-body Calogero model is represented on the S_N-symmetric subspace of the positive definite Fock space. We discuss some general properties of the algebra and construct four different realizations of the dynamical symmetry algebra of the Calogero model. Using the fact that the minimal algebra of observables is common to the Ca

Yosuke Uehara

We present a mini-review of present constraints of the large extra dimension scenario. We show many experiments and considerations that can constrain the fundamental scale of the large extra dimension. We observe that constraints come from collider experiments are much weaker than those of astrophysical and cosmological considerations. When the number of ext

I. Galanakis, P. H. Dederichs, N. Papanikolaou

We study the origin of the gap and the role of chemical composition in the half-ferromagnetic Heusler alloys using the full-potential screened KKR method. In the paramagnetic phase the C1_b compounds, like NiMnSb, present a gap. Systems with 18 valence electrons, Z_t, per unit cell, like CoTiSb, are semiconductors, but when Z_t > 18 antibonding states are al

Raul Rabadan, Joan Simon

We discuss the lift of certain D6-antiD6-brane systems to M-theory. These are purely gravitational configurations with a bolt singularity. When reduced along a trivial circle, and for large bolt radius, the bolt is related to a non-supersymmetric orbifold type of singularity where some closed string tachyons are expected in the twisted sectors. This is a kin

Emmanuel Kohlprath, Gabriele Veneziano

Using a recent technique, proposed by Eardley and Giddings, we extend their results to the high-energy collision of two beams of massless particles, i.e. of two finite-front shock waves. Closed (marginally) trapped surfaces can be determined analytically in several cases even for collisions at non-vanishing impact parameter in D\ge 4 space-time dimensions. W

I. Galanakis

The development of new techniques such as the molecular beam epitaxy have enabled the growth of thin films of materials presenting novel properties. Recently it was made possible to grow a CrAs thin-film in the zinc-blende structure. In this contribution, the full-potential screened KKR method is used to study the electronic and magnetic properties of bulk C

R. Coquereaux, G. Schieber

We show that the Ocneanu algebra of quantum symmetries, for an ADE diagram (or for higher Coxeter-Dynkin systems, like the Di Francesco - Zuber system) is, in most cases, deduced from the structure of the modular T matrix in the A series. We recover in this way the (known) quantum symmetries of su(2) diagrams and illustrate our method by studying those assoc

G. E. Volovik

There is a discussion between L. B. Okun, G. Veneziano and M. J. Duff, concerning the number of fundamental dimensionful constants in physics (physics/0110060). They advocated correspondingly 3, 2 and 0 fundamental constants. Here we consider this problem on example of the effective relativistic quantum field theory, which emerges in the low energy corner of

L. Feher, I. Marshall

A family of special cases of the integrable Euler equations on $so(n)$ introduced by Manakov in 1976 is considered. The equilibrium points are found and their stability is studied. Heteroclinic orbits are constructed that connect unstable equilibria and are given by the orbits of certain 1-parameter subgroups of SO(n). The results are complete in the case $n

Sergei Igonin

We consider multidimensional systems of PDEs of generalized evolution form with t-derivatives of arbitrary order on the left-hand side and with the right-hand side dependent on lower order t-derivatives and arbitrary space derivatives. For such systems we find an explicit necessary condition for existence of higher conservation laws in terms of the system&#3

P. Belli, R. Cerulli, N. Fornengo, S. Scopel

The DAMA/NaI Collaboration has observed a 4-sigma C.L. model independent effect investigating the annual modulation signature in the counting rate of an NaI(Tl) set-up (total exposure of 57986 kg day) and the implications of this effect have been studied under different model-dependent assumptions. In this paper we extend one of the previous analyses, the ca

A. Chenaghlou, H. Fakhri

An appropriate generalization of the unitary parasupersymmetry algebra of Beckers-Debergh to arbitrary order is presented in this paper. A special representation for realizing of the even arbitrary order unitary parasupersymmetry algebra of Beckers-Debergh is analyzed by one dimensional shape invariance solvable models, 2D and 3D quantum solvable models obta

N. S. Deger, A. Kaya

We consider world-volume description of M2-branes ending on an M5-brane. The system can be described either as a solitonic solution of the M5-brane field equations or in terms of an effective string propagating in 6-dimensions. We show that the zeroth order scalar scattering amplitudes behave similarly in both pictures. The soliton solution appears to have a

S. M. Kuzenko, I. N. McArthur

In gauge theories, not all rigid symmetries of the classical action can be maintained manifestly in the quantization procedure, even in the absence of anomalies. If this occurs for an anomaly-free symmetry, the effective action is invariant under a transformation that differs from its classical counterpart by quantum corrections. As shown by Fradkin and Palc

T. Saha-Dasgupta, R. Valenti

We have performed an {\it ab initio} study of the electronic structure of two isostructural quantum spin systems, KCuCl$_{3}$ and TlCuCl$_{3}$, which have recently attracted much attention due to their unconventional magnetic properties. Our first-principles analysis shows unambiguously the role of Tl, as opposed to structural differences between the two com

Holger F. Hofmann

Quantum teleportation is possible because entanglement allows a definition of precise correlations between the non-commuting properties of a local system and corresponding non-commuting properties of a remote system. In this paper, the exact causality achieved by maximal entanglement is analyzed and the results are applied to the transfer of effects acting o

Abraham Loeb

We show that X-ray clusters would have cooled substantially over a Hubble time by transport of heat from their hot interior to the their envelope, if the heat conductivity had not been heavily suppressed relative to the Spitzer value due to magnetic fields. The suppression is required in order for the observed abundance of hot X-ray clusters to be consistent

D. Mozyrsky, I. Martin

A model of an electrical point contact coupled to a mechanical system (oscillator) is studied to simulate the dephasing effect of measurement on a quantum system. The problem is solved at zero temperature under conditions of strong non-equilibrium in the measurement apparatus. For linear coupling between the oscillator and tunneling electrons, it is found th

Peter Ozsvath, Zoltan Szabo

We calculate the Heegaard Floer homologies for three-manifolds obtained by plumbings of spheres specified by certain graphs. Our class of graphs is sufficiently large to describe, for example, all Seifert fibered rational homology spheres. These calculations can be used to determine also these groups for other three-manifolds, including the product of a circ

A. Kozlov, A. J. Sarty

New, high-precision measurements of the 3He(e,e'p) reaction using the A1 collaboration spectrometers at the Mainz microtron MAMI are presented. These were performed in parallel kinematics at energy transfers below the quasi-elastic peak, and at a central momentum transfer of 685 MeV/c. Cross sections and distorted momentum distributions were extracted an

Jean P. Brodie, Soeren S. Larsen

Using spectra obtained with the Keck I telescope we have demonstrated conclusively that the faint (23<V<24 mag.) and unusually extended objects we discovered in HST images of the lenticular galaxies, NGC 1023 and NGC 3384, are star clusters associated with their respective galaxies. In the case of NGC 1023 we were further able to establish that these objects

I. L. Garzon, J. A. Reyes-Nava, J. I. Rodriguea-Hernandez, I. Sigal

Chiral structures have been found as the lowest-energy isomers of bare (Au$_{28}$ and Au$_{55}) and thiol-passivated (Au$_{28}(SCH$_{3})$_{16}$ and Au$_{38}(SCH_{3})_{24}) gold nanoclusters. The degree of chirality existing in the chiral clusters was calculated using the Hausdorff chirality measure. We found that the index of chirality is higher in the passi

J. M. Moran-Mirabal, H. C. Rosu

We present the statistics of the significant nouns and adjectives of social impact figuring in the nominations of the Nobel prizes in Physics and Chemistry over the period of the awards from 1901 to 2001

R. Bijker, F. Iachello

A new method is introduced to study three-body clusters. Triangular configurations with ${\cal D}_{3h}$ point-group symmetry are analyzed. The spectrum, transition form factors and $B(Eλ)$ values of $^{12}$C are investigated. It is concluded that the low-lying spectrum of $^{12}$C can be described by three alpha-particles at the vertices of an equilateral tr

Jan Pisut, Neva Pisutova

We propose an alternative way of looking at data on anomalous J/psi suppression. The proposed method is in principle equivalent to the one used by the NA50 Collaboration, but it permits to visualize separate contributions of individual processes responsible for the disintegration of J/psi&#39;s produced by a hard process in nuclear collisions. The method can

S. G. Bondarenko, V. V. Burov, A. V. Molochkov, G. I. Smirnov

Recent developments of the covariant Bethe-Salpeter (BS) approach with the use of the separable interaction for the deuteron are reviewed. It is shown that the BS formalism allows a covariant description of various electromagnetic reactions like the lepton-deuteron scattering, deuteron electro-disintegration, deep inelastic scattering (DIS) of leptons on lig

A. M. Mancho, H. Riecke

We consider surface-tension driven convection in a rotating fluid layer. For nearly insulating boundary conditions we derive a long-wave equation for the convection planform. Using a Galerkin method and direct numerical simulations we study the stability of the steady hexagonal patterns with respect to general side-band instabilities. In the presence of rota

Carlos R. Fadragas, Ruben Orozco-Morales, Juan V. Lorenzo-Ginori

The DFT representation is applied, to a ordered-chaotic finite-duration sequences set generated by the Hénon mapping, for describing the order-chaos transition. This representation has the advantage that it may be applied to a relatively shorter discret-time series. The bifurcation diagram is produced and the largest Lyapounov exponent is calculated for each

Denis Krutikov

We study the distribution of the eigenvalues inside of the essential spectrum for discrete one-dimensional Schrödinger operators with potentials of Coulomb type decay.

E. Aldrovandi

We outline a cohomological treatment for multivalued (classical) action functionals. We point out that an application of Takens&#39; theorem, after Zuckerman, Deligne and Freed, allows to conclude that multivalued functionals yield globally defined variational equations.

Yves André

We show how the Galois-Picard_Vessiot theory of differential equations and difference equations, and the theory of holonomy groups in differential geometry, are different aspects of a unique Galois theory. The latter is based upon the construction and study of the tensor product of non commutative connections over a commutative base, without any curvature as

Luis Fuentes Garcia, Manuel Pedreira Perez

Given a smooth curve X of genus g we compute de dimension of the family of curves C which have an involution over X. Moreover we distinguish when the curve C is hyperelliptic.

T. W. Dawson, J. F. Feinstein

We examine the condition that a complex Banach algebra $A$ have dense invertible group. We show that, for commutative algebras, this property is preserved by integral extensions. We also investigate the connections with an old problem in the theory of uniform algebras.

Daniel Didt

We show that a large class of finite dimensional pointed Hopf algebras is quasi-isomorphic to their associated graded version coming from the coradical filtration, i.e. they are 2-cocycle deformations of the latter. This supports a slightly specialized form of a conjecture of Masuoka.

Aroldo Kaplan, Gregory J. Pearlstein

We prove that a variation of graded-polarizable mixed Hodge structure over a punctured disk with unipotent monodromy, has a limiting mixed Hodge structure at the puncture (i.e., it is admissible in the sense of [SZ]) which splits over $\R$, if and only if certain grading of the complexified weight filtration, depending smoothly on the Hodge filtration, exten

Luis Fuentes Garcia, Manuel Pedreira Perez

The aim of this paper is to get some results about ruled surfaces which configure a projective theory of scrolls and ruled surfaces. Our ideas follow the viewpoint of Corrado Segre, but we employ the contemporaneous language of locally free sheaves. The results complete the exposition given by R. Hartshorne and they have not appeared before in the contempora

Nathan Berkovits

A quantizable worldsheet action is constructed for the superstring in a supersymmetric plane wave background with Ramond-Ramond flux. The action is manifestly invariant under all isometries of the background and is an exact worldsheet conformal field theory.

Oleg Lebedev, Stephen Morris

We find that dilaton dominated supersymmetry breaking and spontaneous CP violation can be achieved in heterotic string models with superpotentials singular at the fixed points of the modular group. A semi--realistic picture of CP violation emerges in such models: the CKM phase appears due to a complex VEV of the T-modulus, while the soft supersymmetric CP ph

Arshad Momen, Tapobrata Sarkar

We examine the Cardy-Verlinde formula for finite temperature N=4 Super Yang-Mills theory on $R\times S^3$, and its AdS dual. We find that curvature effects introduce non-trivial corrections to thermodynamic quantities computed on both sides. We find a modified version of the Cardy-Verlinde formula for the SYM theory, incorporating these. On the gravity side,

G. A. Diamandis, B. C. Georgalas, N. E. Mavromatos, E. Papantonopoulos

Presently there is preliminary observational evidence that the cosmological constant might be non zero, and hence that our Universe is eternally accelerating (de Sitter). This poses fundamental problems for string theory, since a scattering matrix is not well defined in such Universes. In a previous paper we have presented a model, based on (non-equilibrium)

Marco Cariglia, Kurt Lechner

We construct a gravitational-anomaly-free effective action for the coupled system of IIA D=10 dynamical supergravity interacting with an NS5-brane. The NS5-brane is considered as elementary in that the associated current is a delta-function supported on its worldvolume. Our approach is based on a Chern-kernel which encodes the singularities of the three-form

Edi Halyo

Using the de Sitter/CFT correspondence we describe a scenario of holographic inflation which is driven by a three dimensional boundary field theory. We find that inflationary constraints severely restrict the $β$--function, the anomalous dimensions and the value of the $C$--function of the boundary theory. The scenario has model independent predictions such

Everton M. C. Abreu, Alvaro de Souza Dutra, Clovis Wotzasek

We have devoted an effort to study some nonlinear actions, characteristics of the ${\cal W}$-theories, in the framework of the soldering formalism. We have disclosed interesting new results concerning the embedding of the original chiral ${\cal W}$-particles in different metrical spaces in the final soldered action, i.e., the metric gets modified by the sold

Shijong Ryang

We study the IR dynamics of the type IIB supergravity solution describing N D3-branes and M fractional D3-branes on the resolved conifold. The baryon mass and the tension of domain wall in the dual gauge theory are evaluated and compared with those for the deformed conifold. The IR behavior of the solution for the general conifold is also discussed. We show

Skuli Gudmundsson, Charles B. Thorn

In earlier work, the planar diagrams of $SU(N_c)$ gauge theory have been regulated on the light-cone by a scheme involving both discrete $p^+$ and $τ=ix^+$. The transverse coordinates remain continuous, but even so all diagrams are rendered finite by this procedure. In this scheme quartic interactions are represented as two cubics mediated by short lived fic

E. Garcia-Reyes, A. Hernandez-Galeana, A. Vargas, A. Zepeda

In a model with a gauge group $G_{SM}\otimes U(1)_X$, where $G_{SM} \equiv SU(3)_C \otimes SU(2)_L \otimes U(1)_Y$ is the standard model gauge group and $U(1)_X$ is a horizontal local gauge symmetry, the spectrum of charged fermion masses and mixing angles are obtained from radiative contributions with the aim to reproduce the fermion masses and the Cabibbo-