May 2002 arXiv papers — page 5

Bo Pang, Lillian Lee, Shivakumar Vaithyanathan

We consider the problem of classifying documents not by topic, but by overall sentiment, e.g., determining whether a review is positive or negative. Using movie reviews as data, we find that standard machine learning techniques definitively outperform human-produced baselines. However, the three machine learning methods we employed (Naive Bayes, maximum entr

Kunal K. Das, M. D. Girardeau, E. M. Wright

A nonzero temperature generalization of the Fermi-Bose mapping theorem is used to study the exact quantum statistical dynamics of a one-dimensional gas of impenetrable bosons on a ring. We investigate the interference produced when an initially trapped gas localized on one side of the ring is released, split via an optical-dipole grating, and recombined on t

E. R. P. Alves, C. H. Lewenkopf

We study the conductance statistical features of ballistic electrons flowing through a chaotic quantum dot. We show how the temperature affects the universal conductance fluctuations by analyzing the influence of dephasing and thermal smearing. This leads us to two main findings. First, we show that the energy correlations in the transmission, which were ove

A. J. Blattner, B. W. Wessels

In1-xMnxAs diluted magnetic semiconductor (DMS) thin films have been grown using metalorganic vapor phase epitaxy (MOVPE). Tricarbonyl(methylcyclopentadienyl)manganese was used as the Mn source. Nominally single-phase, epitaxial films were achieved with Mn content as high as x=0.14 using growth temperatures Tg>475 C. For lower growth temperatures and higher

Paolo Crucitti, Vito Latora, Massimo Marchiori, Andrea Rapisarda

The concept of network efficiency, recently proposed to characterize the properties of small-world networks, is here used to study the effects of errors and attacks on scale-free networks. Two different kinds of scale-free networks, i.e. networks with power law P(k), are considered: 1) scale-free networks with no local clustering produced by the Barabasi-Alb

G. Brocks, J. H. Snoeijer, P. J. Kelly, H. J. W. Zandvliet

The initial stages of growth of Ge and Si on the Ge(001) surface are studied and compared to growth on the Si(001) surface. Metastable rows of diluted ad-dimers exist on both surfaces as intermediate stages of epitaxial growth. Unexpectedly, for Ge(001) these rows are found exclusively in the <310> directions, whereas on Si(001) the preferred direction is <1

Pavel A. Kossyrev, Jun Qi, Nikolai V. Priezjev, Robert A. Pelcovits

The critical field of the Freedericksz transition and switching dynamics are investigated for polymer stabilized nematic liquid crystals as a function of polymer concentration. A simple phenomenological model is proposed to describe the observed critical field and dynamic response time behaviors as a function of concentration. In this model the polymer fibri

Gyorgy Szabo, Tibor Antal, Peter Szabo, Michel Droz

We study the emergency of mutual cooperation in evolutionary prisoner&#39;s dilemma games when the players are located on a square lattice. The players can choose one of the three strategies: cooperation (C), defection (D) or &#34;tit for tat&#34; (T), and their total payoffs come from games with the nearest neighbors. During the random sequential updates th

F. Wegner, V. Hankevych

We present a stability analysis of the 2D t-t&#39; Hubbard model on a square lattice for t&#39; = -t/6. We find possible phases of the model (d-wave Pomeranchuk and superconducting states, band splitting, singlet and triplet flux phases), and study the interplay of them.

A. Perucchi, L. Degiorgi, J. Jun, M. Angst

We present magneto-optical reflectivity results in the basal-plane of the hexagonal $MgB_2$. The data were collected on a mosaic of $MgB_2$ single crystals with $T_{c}=38 ~K$ from the ultraviolet down to the far infrared as a function of temperature and magnetic field oriented along the c-axis. In the far infrared there is a clear signature of the supercondu

T. Antal, H. J. Hilhorst, R. K. P. Zia

We consider the average number B_m(t) of bonds traversed exactly m times by a t step simple random walk. We determine B_m(t) explicitly in the scaling limit t -> oo with m/sqrt(t) fixed in dimension d=1 and m/log(t) fixed in dimension d=2. The scaling function is an erfc in d=1 and an exponential in d=2.

S. Reymond, L. Antognazza, M. Decroux, E. Koller

We have investigated the resistive response of high Tc thin films submitted to a high density of current. For this purpose, current pulses were applied into bridges made of Nd(1.15)Ba(1.85)Cu3O7 and Bi2Sr2CaCu2O8. By recording the time dependent voltage, we observe that at a certain critical current j*, a highly dissipative domain develops somewhere along th

Tania Tome, Alberto Petri

The critical behavior of two-dimensional stochastic lattice gas models with C3v symmetry is analyzed. We study the cumulants of the order parameter for the three state (equilibrium) Potts model and for two irreversible models whose dynamic rules are invariant under the symmetry operations of the point group C3v. By means of extensive numerical analysis of th

L. Salasnich, A. Parola, L. Reatto

We study the tunneling properties of a cigar-shaped Bose-Einstein condensate by using an effective 1D nonpolynomial nonlinear Schrödinger equation (NPSE). First we investigate a mechanism to generate periodic pulses of coherent matter by means of a Bose condensate confined in a potential well with an oscillating height of the energy barrier. We show that is

M. Leadbeater, D. C. Samuels, C. F. Barenghi, C. S. Adams

The elementary processes involved in the decay of superfluid turbulence in the limit of low temperature are studied by numerical simulations of vortex ring collisions. We find that small vortex rings produced by reconnections eventually annihilate in a collision where all their energy is converted into Kelvin waves and sound. We show that sound emission due

M. Evangelisti, J. Bartolome, L. J. de Jongh, G. Filoti

We report on the magnetic properties of the supra-molecular compound iron(II) phthalocyanine in its alpha-form. dc- and ac-susceptometry measurements and Mossbauer experiments show that the iron atoms are strongly magnetically coupled into ferromagnetic Ising chains with very weak antiferromagnetic interchain coupling. The transition to 3D magnetic ordering

J. Fortagh, H. Ott, G. Schlotterbeck, C. Zimmermann

We describe the production and characterization of microelectromagnets made for trapping and manipulating atomic ensembles. The devices consist of 7 fabricated parallel copper conductors 3 micrometer thick, 25mm long, with widths ranging from 3 to 30 micrometer, and are produced by electroplating a sapphire substrate. Maximum current densities in the wires u

Patrick Ilg, Iliya V. Karlin, Martin Kröger, Hans Christian Öttinger

The quasi--equilibrium approximation is employed as a systematic tool for solving the problem of deriving constitutive equations from kinetic models of liquid--crystalline polymers. It is demonstrated how kinetic models of liquid--crystalline polymers can be approximated in a systematic way, how canonical distribution functions can be derived from the maximu

Patrick Ilg, Iliya V. Karlin, Hans Christian Öttinger

The quasi--equilibrium or maximum entropy approximation is applied in order to derive constitutive equations from kinetic models of polymer dynamics. It is shown in general and illustrated for an example how canonical distribution functions are obtained from the maximum entropy principle, how macroscopic and constitutive equations are derived therefrom and h

Y. S. Lee, T. W. Noh, J. H. Park, K. -B. Lee

We investigated the temperature-dependence of the Raman spectra of a nine-layer BaRuO$_3$ single crystal and a four-layer BaRuO$_3$ epitaxial film, which show pseudogap formations in their metallic states. From the polarized and depolarized spectra, the observed phonon modes are assigned properly according to the predictions of group theory analysis. In both

Satya N. Majumdar, P. L. Krapivsky

An intriguing connection between extreme value statistics and traveling fronts has been found recently in a number of diverse problems. In this brief review we outline a few such problems and consider their various applications.

Yong-Hoon Kim, Andreas Goerling

We present an exact expression for the frequency-dependent Kohn-Sham exact-exchange (EXX) kernel for periodic insulators, which can be employed for the calculation of electronic response properties within time-dependent (TD) density-functional theory. It is shown that the EXX kernel has a long-wavelength divergence behavior of the exact full exchange-correla

Chiaki Yamaguchi, Naoki Kawashima, Yutaka Okabe

We discuss Monte Carlo methods based on the cluster (graph) representation for spin models. We derive a rigorous broad histogram relation (BHR) for the bond number; a counterpart for the energy was derived by Oliveira previously. A Monte Carlo dynamics based on the number of potential moves for the bond number is proposed. We show the efficiency of the BHR f

Sujeet Chaudhary, M. K. Chattopadhyay, Kanwal Jeet Singh, S. B. Roy

The intermetallic compound SmMn$_2$Ge$_2$, displaying multiple magnetic phase transitions, is being investigated in detail for its magnetization behavior near the 145 K first order ferromagnetic to antiferromagnetic transition occuring on cooling, in particular for thermomagnetic history effects in the magnetization data. The most unusual finding is that the

C. S. M. Bastos, M. Bahiana, W. C. Nunes, M. A. Novak

The effect of grain size, easy magnetization axis and anisotropy constant distributions in the irreversible magnetic behavior of granular alloys is considered. A simulated granular alloy is used to provide a realistic grain structure for the Monte Carlo simulation of the ZFC-FC curves. The effect of annealing and external field is also studied. The simulatio

Alessandro Silva, Shimon Levit

In this work we analyze how coherent transport through a Quantum Dot (QD) in the Kondo regime is affected by the weak capacitive interaction with a nearby biased Quantum Point Contact (QPC). We find that when the QD-QPC interaction is weak the width of the Kondo resonance is hardly affected by it. However, the spectral weight of the Kondo peak is reduced lea

David R. Alves, Marina Rejkuba, Dante Minniti, Kem H. Cook

The Hipparcos I-band calibration of horizontal-branch red clump giants as standard candles has lead to controversial results for the distance to the Large Magellanic Cloud (LMC). In an attempt to properly ascertain the corrections for interstellar extinction and clump age and metallicity, we analyze new multi-wavelength luminosity functions of the LMC red cl

David S. Meier, Jean L. Turner, Sara C. Beck

We report the detection of CO(2-1) and 3.1 mm and 1.3 mm continuum emission towards the extremely young starburst in NGC 5253, with data taken from the Owens Valley Millimeter Array. Faint CO emission originates in five molecular clouds distributed along the prominent dust lane seen in visual images. With the gas, the morphology of NGC 5253 looks much like a

M. Karovska, G. Fabbiano, F. Nicastro, M. Elvis

We describe results from our initial study of the diffuse X-ray emission structures in NGC 5128 (Cen A) using the Chandra X-ray Observatory observations. The high-angular resolution Chandra images reveal multi-scale X-ray struct ures with unprecedented detail and clarity. The large scale structures suggest complex symmetry, including a component possibly ass

Eliot Quataert, William Dorland, Greg Hammett

We consider the linear axisymmetric stability of a differentially rotating collisionless plasma in the presence of a weak magnetic field; we restrict our analysis to wavelengths much larger than the proton Larmor radius. This is the kinetic version of the magnetorotational instability explored extensively as mechanism for magnetic field amplification and ang

N. Mirabal, J. Halpern, R. Mukherjee, E. Gotthelf

3EG J1835+5918 is the brightest of the so-called unidentified EGRET sources at intermediate galactic latitude (l,b)=(89,25). We obtained complete radio, optical, and X-ray coverage of its error box, discovering a faint ultrasoft X-ray source in the ROSAT All-Sky Survey. Deep optical imaging at the location of this source, as pinpointed by an observation with

Tehani K. Finch, Lisa P. Carlivati, Joshua N. Winn, Paul L. Schechter

We derive an analytic expression for the mean magnification due to strong gravitational lensing, using a simple lens model, a singular isothermal sphere embedded in an external shear field. We compute separate expressions for 2-image and 4-image lensing. For 4-image lensing, the mean magnification takes a particularly simple form: <mu>_4 = 3.6/(gamma*(1-gamm

Pawan Kumar, Ramesh Narayan

X-ray lines have been recently detected in the afterglows of a few gamma-ray bursts. We derive constraints on the physical conditions in the line-emitting gas, using as an example the multiple K$_α$ lines detected by Reeves et al. (2002) in GRB 011211. We argue that models previously discussed in the literature require either a very extreme geometry or too m

Siming Liu, Fulvio Melia

Sgr A* is a compact radio source at the Galactic Center, thought to be the radiative manifestation of a $2.6\times 10^6 M_\odot$ supermassive black hole. At least a portion of its spectrum--notably the mm/sub-mm ``bump&#39;&#39;--appears to be produced within the inner portion ($r< 10 r_S$) of a hot, magnetized Keplerian flow, whose characteristics are also

T. Totani, W. Kawasaki, N. Kawai

We report a deep optical imaging observation by the Subaru telescope for a very soft X-ray source RX J1836.2+5925, which has been suspected to be an isolated neutron star associated with the brightest as-yet unidentified EGRET source outside the Galactic plane, 3EG J1835+5918. An extended source having a complex, bipolar shape is found at B ~ 26, and this mi

Jorick S. Vink, Janet E. Drew, Tim H. Harries, Rene D. Oudmaijer

H_alpha spectropolarimetry on Herbig Ae/Be stars shows that the innermost regions of intermediate mass (2 -- 15 M_sun) Pre-Main Sequence stars are flattened. This may be the best evidence to date that the higher mass Herbig Be stars are embedded in circumstellar discs. A second outcome of our study is that the spectropolarimetric signatures for the lower mas

Diego Harari, Silvia Mollerach, Esteban Roulet

The next generation of ultra high energy cosmic ray experiments will probably detect several dozens of events clustered around the direction towards each of the most powerful extragalactic sources. We develop a method which could make possible to reconstruct, from the arrival directions and energies of the clustered events, the strength and coherence propert

M. Beijersbergen, W. E. Schaap, J. M. van der Hulst

We use a simple analytic model to deproject 2-d luminosity functions (LF) of galaxies in the Coma cluster measured by Beijersbergen et al. 2002. We demonstrate that the shapes of the LFs change after deprojection. It is therefore essential to correct LFs for projection effects. The deprojected LFs of the central area have best-fitting Schechter parameters of

Patrick Slane

While supernova remnants (SNRs) have long been considered prime candidates for the source of cosmic rays, at least to energies up to ~10^14 eV, it is only over the past several years that direct evidence of such energetic particles in SNRs has been uncovered. X-ray observations of several shell-type SNRs have now revealed sites dominated by nonthermal emissi

J. S. Dunlop, R. J. McLure, T. Yamada, M. Kajisawa

Despite extensive observational efforts, the brightest sub--mm source in the Hubble Deep Field, HDF850.1, has failed to yield a convincing optical/infrared identification almost 4 years after its discovery. This failure is all the more notable given the availability of supporting multi-frequency data of unparalleled depth, and sub-arcsec positional accuracy

Massimo Villata, Claudia M. Raiteri

We present UBVRI light curves of BL Lacertae from May 2000 to January 2001, obtained by 24 telescopes in 11 countries. More than 15000 observations were performed in that period, which was the extension of the Whole Earth Blazar Telescope (WEBT) campaign originally planned for July-August 2000. Rapid flux oscillations are present all the time, involving vari

Harald Krueger, Eberhard Gruen

Spacecraft investigations during the last ten years have vastly improved our knowledge about dust in the Jovian system. All Galilean satellites, and probably all smaller satellites as well, are sources of dust in the Jovian system. In-situ measurements with the dust detectors on board the Ulysses and Galileo spacecraft have for the first time demonstrated th

J. Brand, J. G. A. Wouterloot, A. L. Rudolph, E. J. de Geus

We discuss the results of high-resolution (~0.1-0.2 pc) BIMA CO observations of the central regions of 3 molecular clouds in the far-outer Galaxy (FOG). We identify clumps and investigate their stability by using the virial theorem, including terms due to gravity, turbulence, magnetic field, and interclump gas pressure, and make a comparison with clumps in l

R. Pain, S. Fabbro, M. Sullivan, R. S. Ellis

We present a measurement of the rate of distant Type Ia supernovae derived using 4 large subsets of data from the Supernova Cosmology Project. Within this fiducial sample, which surveyed about 12 square degrees, thirty-eight supernovae were detected at redshifts 0.25--0.85. In a spatially-flat cosmological model consistent with the results obtained by the Su

Sujan Sengupta

The spectral distortion in the Cosmic Microwave Background Radiation (CMBR) caused from the inverse Compton scattering of low energy CMB photons by thermally distributed hot electrons in massive clusters of galaxies - better known as the thermal Sunyaev-Zel&#39;dovich effect is usually estimated by the analytical or semi-analytical solutions of Kompaneets eq

Max Pettini, Sara L. Ellison, Jacqueline Bergeron, Patrick Petitjean

We take a fresh look at the abundance of nitrogen in DLAs with oxygen abundances between 1/10 and 1/100 of solar. This is a metallicity regime poorly sampled in the local universe and where QSO absorbers may hold clues to both the nucleosynthetic origin of N and the chemical evolution of high redshift galaxies. We combine new VLT UVES observations with other

David A. Buote, Tesla E. Jeltema, Claude R. Canizares, Gordon P. Garmire

(Abridged) We present an analysis of a Chandra ACIS-S observation of the elliptical galaxy NGC 720 to verify the existence of a dark matter (DM) halo and to measure its ellipticity. The ACIS-S3 image reveals over 60 point sources. For semi-major axes a<~150&#34; (18.2h_{70}^{-1} kpc) the ellipticity of the diffuse emission is ex ~0.15, which is less than the

J. A. Peacock, M. Colless, I. Baldry, C. Baugh

The 2dF Galaxy Redshift Survey is the first to observe more than 100,000 redshifts. This allows precise measurements of many of the key statistics of galaxy clustering, in particular redshift-space distortions and the large-scale power spectrum. This paper presents the current 2dFGRS results in these areas. Redshift-space distortions are detected with a high

Fulvio Melia, Siming Liu, Marco Fatuzzo

PAPER WITHDRAWN. The recent detection of Sgr A* in the X-ray band, together with the radio polarization measurements conducted over the past few years, offer the best constraints yet for understanding the nature of the emitting gas within several Schwarzschild radii ($r_S$) of this supermassive black hole candidate at the Galactic Center. Earlier, we showed

J. Bougie, Sung Joon Moon, J. B. Swift, Harry L. Swinney

We study shock formation in vertically oscillated granular layers, using both molecular dynamics simulations and numerical solutions of continuum equations to Navier-Stokes order. A flat layer of grains is thrown up from an oscillating plate during each oscillation cycle and collides with the plate later in the cycle. The collisions produce layer compaction

V. G. Vaks

The earlier-described cluster methods are used to generalize the Ginzburg-Landau gradient expansion for the free energy of an inhomogeneous alloy to the case of not small values of order parameters and variations of composition. The results obtained reveale a number of important differences with the expressions used in the phenomenological phase-field approa

Eiichiro Komatsu, Uros Seljak

The angular power spectrum of the SZ effect, C_l, is a powerful probe of cosmology. It is easier to detect than individual clusters in the field, is insensitive to observational selection effects and does not require a calibration between cluster mass and flux, reducing the systematic errors which dominate the cluster-counting constraints. It receives a domi

Alistair Savage, Olivier Schiffmann

We construct the fusion product of finite-dimensional sl_2-modules in the homology of (or in the space of constructible functions on) a certain subvariety L_l(w_1, ..., w_r) of Nakajima&#39;s tensor product variety L(w_1,..., w_r). We also give a combinatorial description of the irreducible components of this subvariety using the notions of graphical calculu

S. L. A. de Queiroz

We show how to use properties of the vectors which are iterated in the transfer-matrix approach to Anderson localization, in order to generate the statistical distribution of electronic wavefunction amplitudes at arbitary distances from the origin of $L^{d-1} \times \infty$ disordered systems. For $d=1$ our approach is shown to reproduce exact diagonalizatio

Gilbert P. Holder

Radio point sources are strongly correlated with clusters of galaxies, so a significant fraction of the thermal Sunyaev-Zel&#39;dovich (SZ) effect signal could be affected by point source contamination. Based on empirical estimates of the radio galaxy population, it is shown that the rms temperature fluctuations of the thermal SZ effect could be underestimat

A. Armoni, J. L. F. Barbon, A. C. Petkou

Following Gubser, Klebanov and Polyakov [hep-th/0204051], we study strings in AdS black hole backgrounds. With respect to the pure AdS case, rotating strings are replaced by orbiting strings. We interpret these orbiting strings as CFT states of large spin similar to glueballs propagating through a gluon plasma. The energy and the spin of the orbiting string

Youngjai Kiem, Yoonbai Kim, Sangmin Lee, Jaemo Park

We present an explicit evidence that shows the correspondence between the type IIB supergravity in the pp-wave background and its dual supersymmetric Yang-Mills theory at the interaction level. We first construct the cubic term of the light-cone interaction Hamiltonian for the dilaton-axion sector of the supergravity. Our result agrees with the corresponding

P. Faccioli, A. Schwenk, E. V. Shuryak

We study the instanton contribution to the proton and neutron electric form factors. Using the single instanton approximation, we perform the calculations in a mixed time-momentum representation in order to obtain the form factors directly in momentum space. We find good agreement with the experimentally measured electric form factor of the proton. For the n

Elliott H. Lieb, Robert Seiringer, Jakob Yngvason

A commonly used theoretical definition of superfluidity in the ground state of a Bose gas is based on the response of the system to an imposed velocity field or, equivalently, to twisted boundary conditions in a box. We are able to carry out this program in the case of a dilute interacting Bose gas in a trap. We prove that a gas with repulsive interactions i

A. Tasitsiomi

The Cold Dark Matter model describes successfully our Universe on large scales, as has been verified by a wide range of observations. Nevertheless, in the last years, and especially with the advances in numerical simulations, a number of apparent inconsistencies arose between what is observed and what the CDM model predicts on small scales. In this work, the

Chuan-Hung Chen, C. Q. Geng

We propose to use T-odd momentum correlations as physical observables to study T violation in $B\to K^{*}l^{+}l^{-} (l=e,μ)$ decays. We show that these observables are zero in the standard model but sizable at the level of 10% in the supersymmetric model. These large T violating effects are measurable at the B-factories in KEK and SLAC and future hadron coll

Laurent Freidel, Etera R. Livine

Spin networks are natural generalization of Wilson loops functionals. They have been extensively studied in the case where the gauge group is compact and it has been shown that they naturally form a basis of gauge invariant observables. Physically the restriction to compact gauge group is enough for the study of Yang-mills theories, however it is well known

N. A. Lima, L. N. Oliveira, K. Capelle

We study the Mott insulating phase of the one-dimensional Hubbard model using a local-density approximation (LDA) that is based on the Bethe Ansatz (BA). Unlike conventional functionals, the BA-LDA has an explicit derivative discontinuity. We demonstrate that as a consequence of this discontinuity the BA-LDA yields the correct Mott gap, independently of the

F. L. Schoeier, J. K. Jorgensen, E. F. van Dishoeck, G. A. Blake

A detailed radiative transfer analysis of the observed continuum and molecular line emission toward the deeply embedded young stellar object IRAS 16293-2422 is performed. The continuum modelling is used to constrain the temperature and density distributions in the envelope, enabling quantitative estimates of various molecular abundances. The molecular excita

Ludde Edgren, Niclas Sandstrom

Recently, Batalin and Marnelius proposed a superfield algorithm for master actions in the BV-formulation for a class of first order gauge field theories. Possible theories are determined by a ghost number prescription and a simple local master equation. We investigate consistent solutions of these local master equations with emphasis on four and six dimensio

Joerg Schumacher, Bruno Eckhardt

We study the formation of clusters of passive Lagrangian tracers in a non-smooth turbulent flow in a flat free-slip surface as a model for particle dynamics on free surfaces. Single particle and pair dispersion show different behavior for short and large times: on short times particles cluster exponentially rapidly until patches of the size of the divergence

Wade Naylor, Misao Sasaki

The vacuum energy for a massless conformally coupled scalar field in a brane world set up, corresponding to de Sitter branes in a bulk anti-de Sitter spacetime, is calculated. We use the Euclidean version of the metric which can be conformally related to a metric similar in form to the Einstein universe (S^4 times R). Employing zeta-function regularisation w

J. Gegenberg, S. Vaidya, J. F. Vazquez-Poritz

In three dimensions, a `master theory&#39; for all Thurston geometries requires imaginary flux. However, these geometries can be obtained from physical three-dimensional theories with various additional scalar fields, which can be interpreted as moduli in various compactifications of a higher-dimensional `master theory&#39;. Three Thurston geometries are of

Janusz Jedrzejewski, Volodymyr Derzhko

We consider a classical lattice gas that consists of more than one &#34;species&#34; of particles (like a spin-3/2 Ising model or the atomic limit of the extended Hubbard model), whose ground-state phase diagram is macroscopically degenerate. This gas is coupled component-wise and in the Falicov-Kimball-like manner to a multicomponent free-fermion gas. We sh

Alain Barrat, Emmanuel Trizac

We analyze the deviations from Maxwell-Boltzmann statistics found in recent experiments studying velocity distributions in two-dimensional granular gases driven into a non-equilibrium stationary state by a strong vertical vibration. We show that in its simplest version, the ``stochastic thermostat&#39;&#39; model of heated inelastic hard spheres, contrary to

Isao Kishimoto, Tomohiko Takahashi

We study the physical spectrum of cubic open string field theory around universal solutions, which are constructed using the matter Virasoro operators and the ghost and anti-ghost fields. We find the cohomology of the new BRS charge around the solutions, which appear with a ghost number that differs from that of the original theory. Considering the gauge-unf

R. Pezer, A. Ventura, D. Vretenar

A new model for calculating nuclear level densities is investigated. The single-nucleon spectra are calculated in a relativistic mean-field model with energy-dependent effective mass, which yields a realistic density of single-particle states at the Fermi energy. These microscopic single-nucleon states are used in a fast combinatorial algorithm for calculati

Kimyeong Lee, Sang-Heon Yi

We explore the 1/4 BPS configurations of the supersymmetric gauge theories on $R^{1+3} \times S^1$. The BPS bound for energy and the BPS equations are obtained and the characteristics of the BPS solutions are studied. These BPS configurations describe electrically charged calorons, which are constituted of dyons and carry linear momentum along the compact di

K. A. Muttalib, Victor A. Gopar

Electronic transport properties in a disordered quantum wire are very well described by the Dorokhov-Mello-Pereyra-Kumar (DMPK) equation, which describes the evolution of the transmission eigenvalues as a function of the length of a multichannel conductor. However, the DMPK equation is restricted to quasi one dimensional systems only. We derive a generalized

Z. C. Tu, Z. C. Ou-Yang

The structures and symmetries of single-walled carbon nanotubes (SWNTs) are introduced in detail. The physical properties of SWNTs induced by their symmetries can be described by tensors in mathematical point of view. It is found that there are 2, 4, and 5 different parameters in the second, third, and fourth rank tensors representing electronic conductivity

G. Arutyunov, E. Sokatchev

The pp-wave (Penrose limit) in conformal field theory can be viewed as a special contraction of the unitary representations of the conformal group. We study the kinematics of conformal fields in this limit in a geometric approach where the effect of the contraction can be visualized as an expansion of space-time. We discuss the two common models of space-tim

Nayantara Gupta

The muon neutrinos from the Gamma Ray Bursts(GRBs) during their propagation oscillate to tau neutrinos. The tau neutrinos can be identified by the appearance of tau leptons which decay to muons below the detector. We examine the prospect of detecting these tau neutrinos from individual GRBs in a large area muon detector. We investigate for what range of valu

Dietrich Dehlinger, M. W. Mitchell

We present detailed instructions for constructing and operating an apparatus to produce and detect polarization-entangled photons. The source operates by type-I spontaneous parametric downconversion in a two-crystal geometry. Photons are detected in coincidence by single-photon counting modules and show strong angular and polarization correlations. We observ

Dietrich Dehlinger, M. W. Mitchell

We use polarization-entangled photon pairs to demonstrate quantum nonlocality in an experiment suitable for advanced undergraduates. The photons are produced by spontaneous parametric downconversion using a violet diode laser and two nonlinear crystals. The polarization state of the photons is tunable. Using an entangled state analogous to that described in

Jian-Qi Shen, Hong-Yi Zhu, Pan Chen

There exist a number of typical and interesting systems or models which possess three-generator Lie-algebraic structure in atomic physics, quantum optics, nuclear physics and laser physics. The well-known fact that all simple 3-generator algebras are either isomorphic to the algebra $sl(2,C)$ or to one of its real forms enables us to treat these time-depende

Jaromir Fiurasek, Ladislav Mista,, Radim Filip

We propose two probabilistic entanglement concentration schemes for a single copy of two-mode squeezed vacuum state. The first scheme is based on the off-resonant interaction of a Rydberg atom with the cavity field while the second setup involves the cross Kerr interaction, auxiliary mode prepared in a strong coherent state and a homodyne detection. We show

Timur F. Kamalov

It is supposed the alternative to Quantum Mechanics Axiomatic. Fluctuational Theory save the Mathematics of Quantum Mechanic without change, naming this Mathematics as Method of Indirect Computation. Fluctuational Theory is delete the axiomatic of Quantum Mechanics and replaces it by the assumption of Gravitational Noise. This assumption is connects the Meth

S. Lerma, S. Jesgarz, P. O. Hess, O. Civitarese

The simplest version of a class of toy models for QCD is presented. It is a Lipkin-type model, for the quark-antiquark sector, and, for the gluon sector, gluon pairs with spin zero are treated as elementary bosons. The model restricts to mesons with spin zero and to few baryonic states. The corresponding energy spectrum is discussed. We show that ground stat

Marcus Bleicher, Jörg Aichelin

The excitation function of the in-plane directed flow of nucleons is studied within a non-equilibrium transport approach. It is demonstrated that a local minimum in the excitation function of the directed flow develops, which is not related to a transition into a quark-gluon plasma (QGP) phase. It is a consequence of the dynamical softening of the underlying

J. Arrington

Recent recoil polarization measurements in Hall A at Jefferson Lab show that the ratio of the electric to magnetic form factors for the proton decreases significantly with increasing Q^2. This contradicts previous Rosenbluth measurements which indicate approximate scaling of the form factors. The cross section measurements were reanalyzed to try and understa

M. Guttormsen, M. Hjorth-Jensen, J. Rekstad, S. Siem

A method to extract primary $γ$-ray spectra from particle-$γ$ coincidences at excitation energies up to the neutron binding energy is described. From these spectra, the level density and $γ$-ray strength function can be determined. From the level density, several thermodynamical quantities are obtained within the microcanonical and canonical ensemble. Also m

T. Kanna, M. Lakshmanan

Soliton interactions in systems modelled by coupled nonlinear Schroedinger (CNLS) equations and encountered in phenomena such as wave propagation in optical fibers and photorefractive media possess unusual features : shape changing intensity redistributions, amplitude dependent phase shifts and relative separation distances. We demonstrate these properties i

E. Sh. Gutshabash

The two-dimensional generalization of the Polyelectolite model of DNA is proposed. It is reduced to the boundary problem for nonlinear completely integrable equation $\sh$-Gordon. In the linearisible version the exact solution is constructed and its asymptotic is found. The soliton solutions of nonlinear equation are calculated that allowed tells about the p

Pierluigi Contucci

In this short note we study the fourth order consequences of the stochastic stability property for mean field spin glass models introduced in previous paper by Aizenman and Contucci. We show that due to a remarkable cancellation mechanism it reduces to the well known second order version as predicted by Parisi&#39;s replica-equivalent ansatz.

M. Balazs, P. Van

We prove by symmetry properties that the Lagrangian of a free point-mass is a quadratic function of the speed in the non-relativistic case, and that the action of the free point-mass between two spacetime points is the proper time passed in the relativistic case. These well known facts are proved in a mathematically rigorous way with a frame independent trea

Zakaria Giunashvili

Some cohomology classes associated with an ideal in a Lie algebra, a Poisson structure on the basic functions algebra of contact structure, its Poisson cohomology and geometric (pre)quantization are considered from the algebraic point of view.

Gerardo Morsella

After a brief account of the algebraic version of renormalization group developed by Buchholz and Verch, and of the main results of the Doplicher-Haag- Roberts theory of superselection sectors, we introduce the notion of asymptotic charge transfer chain, through which it is possible to reconstruct the scaling limit theory&#39;s superselection structure entir

Alfons Van Daele

Any multiplier Hopf *-algebra} with positive integrals gives rise to a locally compact quantum group (in the sense of Kustermans and Vaes). As a special case of such a situation, we have the compact quantum groups (in the sense of Woronowicz) and the discrete quantum groups (as introduced by Effros and Ruan). In fact, the class of locally compact quantum gro

Ann Maes, Alfons Van Daele

The classical duality theory associates to an abelian group a dual companion. Passing to a non-abelian group, a dual object can still be defined, but it is no longer a group. The search for a broader category which should include both the groups and their duals, points towards the concept of quantization. Classically, the regular representation of a group co

Bertram Kostant

We give a branching law for subgroups fixed by an involution. As an application we give a generalization of the Cartan-Helgason theorem and a noncompact analogue of the Borel-Weil theorem.

Ali Sinan Sertoz

We determine the necessary and sufficient conditions on the entries of the intersection matrix of the transcendental lattice of a K3 surface for the K3 surface to doubly cover an Enriques surface.

B. Feigin, E. Feigin

Using the fusion product of the representations of the Lie algebra $\mathfrak{sl}_2$ we construct a set of the integrable highest weight $\hat{\mathfrak{sl}_2}$-modules $L^D$, depending on the vector $D\in\mathbb{N}^{k+1}$. In a special cases of $D$ our modules are isomorphic to the irreducible $\hat{\mathfrak{sl}_2}$-modules $L_{i,k}$. We construct a basis

A. R. Alimov

A subset M of a normed linear space X is said to be a {\it strict sun} if, for every point $x\in X\setminus M$, the set of its nearest points from~$M$ is non-empty and if $y\in M$ is a nearest point from M to x, then y is a nearest point from M to all points from the ray $\{λx+(1- λ)y | λ>0\}$. In the paper there obtained a geometrical characterisation of st

Alberto Del Lungo, Andrea Frosini, Maurice Nivat, Laurent Vuillon

This paper studies the problem of reconstructing binary matrices that are only accessible through few evaluations of their discrete X-rays. Such question is prominently motivated by the demand in material science for developing a tool for the reconstruction of crystalline structures from their images obtained by high-resolution transmission electron microsco

Pablo A. Parrilo, Ronen Peretz

A geometric inequality among three triangles, originating in circle packing problems, is introduced. In order to prove it, we reduce the original formulation to the nonnegativity of a particular polynomial in four real indeterminates. Techniques based on sum of squares decompositions, semidefinite programming, and symmetry reduction are then applied to provi