August 2001 arXiv papers — page 10

A B Yanovski

We consider some special type extensions of an arbitrary Lie algebra, which we call universal extensions. We show that these extensions are in one-to-one correspondence with finite dimensional associative commutative algebras. We also construct a special kind of these extensions, that correspond to a finite commutative monoids.

Brooke Shipley

Greenlees defined an abelian category A whose derived category is equivalent to the rational S^1-equivariant stable homotopy category whose objects represent rational S^1-equivariant cohomology theories. We show that in fact the model category of differential graded objects in A (dgA) models the whole rational S^1-equivariant stable homotopy theory. That is,

Arthur Bartels, Tom Farrell, Lowell Jones, Holger Reich

The Isomorphism Conjecture is a conceptional approach towards a calculation of the algebraic K-theory of a group ring RG, where G is an infinite group. In this paper we prove the conjecture in dimensions n<2 for fundamental groups of closed Riemannian manifolds with strictly negative sectional curvature and an arbitrary coefficient ring R. If R is regular th

B. Durhuus, C. -W. H. Lee

Motivated by the formalism of string bit models, or quantum matrix models, we study a class of simple Hamiltonian models of quantum gravity type in two space-time dimensions. These string bit models are special cases of a more abstract class of models defined in terms of the sl(2) subalgebra of the Virasoro algebra. They turn out to be solvable and their sca

C. Klimcik

We give the bare-bone description of the quasitriangular chiral WZW model for the particular choice of the Lu-Weinstein-Soibelman Drinfeld double of the affine Kac-Moody group. The symplectic structure of the model and its Poisson-Lie symmetry are completely characterized by two $r$-matrices with spectral parameter. One of them is ordinary and trigonometric

Bang-Rong Zhou

We give an explicit proof of equivalence of the two-point function to one-loop order in the two formalisms of thermal $λϕ^3$ theory based on the expressions in the real-time formalism. It is indicated that the key-point of completing the proof is to separate carefully the imaginary part of the zero-temperature loop integral from relevant expressions and this

K. Bardakci, A. Konechny

We compute the one-loop partition function for quadratic tachyon background in open string theory. Both closed and open string representations are developed. Using these representations we study the one-loop divergences in the partition function in the presence of the tachyon background. The divergences due to the open and closed string tachyons are treated

A. Majumder, C. Gale

We investigate the effects of a charge asymmetry on the spectrum of dileptons radiating from a quark gluon plasma. We demonstrate the existence of a new set of processes in this regime. The dilepton production rate from the corresponding diagrams is shown to be as important as that obtained from the Born-term quark-antiquark annihilation.

Ilja Dorsner, S. M. Barr

The large mixing angle (LMA) MSW solution to the solar neutrino problem seems favored by the data at the moment over the small mixing angle (SMA) MSW solution and the vacuum (VAC) solution. In this paper the various main types of models of neutrino masses and mixings are studied from the point of view of how naturally they can give the LMA solution. Special

Rathin Adhikari, Ernest Ma, G. Rajasekaran

We propose the novel lepton-number relationship $L_τ= L_e + L_μ$, which is uniquely realized by the interaction $(\hat ν_e \hat μ- \hat e \hat ν_μ) \hat τ^c$ in supersymmetry and may account for a possibly large muon anomalous magnetic moment. Neutrino masses (with bimaximal mixing) may be generated from the spontaneous and soft breaking of this lepton symme

Xiao-Gang He

In this talk I review theoretical predictions for CP violation in non-leptonic hyperon decays in the Standard Model and models beyond. In the Standard Model the CP violating observable $A$ in the polarization asymmetries of $Λ\to p π^-$ and $Ξ^- \to Λπ^-$ decays are predicted to be in the ranges $(-0.61\sim 6.8)\times 10^{-5}$ and $-(0.1\sim 1)\times 10^{-5}

Otto C. W. Kong

The generic supersymmetric standard model is a model built from a supersymmetrized standard model field spectrum the gauge symmetries only. The popular minimal supersymmetric standard model differs from the generic version in having R-parity imposed by hand. We review an efficient formulation of the model and some of the recently obtained interesting phenome

S. Dubnicka, A. Z. Dubnickova, P. Strizenec

After two decades of a development of the unitary and analytic models of the electromagnetic structure of hadrons and nuclei their main principles are briefly formulated, then a general scheme of their applications to the electromagnetic, weak and strong interaction processes are traced out and finally, some results of their successful applications are revie

Yi-Zhong Fang, Xiang-Qian Luo

Hamiltonian lattice QCD with Wilson fermions is investigated systematically by strong-coupling expansion up to the second order. The effective Hamiltonian is diagonalized by Bogoliubov transformation. The vacuum energy, chiral condensate, pseudo-scalar and vector meson masses are calculated. The comparison with the unitary transformation method by Luo and Ch

Alfred K. Mann

This brief note outlines a detector for the Homestake Laboratory and the physics experiments that might be done with it. The note might go on record as a letter of intent to be converted to a formal proposal at a later time.

H1 Collaboration, C. Adloff

A measurement of the derivative (d ln F_2 / d lnx)_(Q^2)= -lambda(x,Q^2) of the proton structure function F_2 is presented in the low x domain of deeply inelastic positron-proton scattering. For 5*10^(-5)<=x<=0.01 and Q^2>=1.5 GeV^2, lambda(x,Q^2) is found to be independent of x and to increase linearly with ln(Q^2).

Horst von Borzeszkowski, Michael B. Mensky

It is discussed how systems of quantum-correlated (entangled)particles or atoms behave in external gravitational fields and what gravitational effects may exist in such systems. An experimental setup is proposed which improves the sensitivity of the Ramsey interferometer by the usage of quantum-correlated atoms. Entanglement of $n$ atoms improves the sensiti

Christian Igel, Marc Toussaint

In a recent paper it was shown that No Free Lunch results hold for any subset F of the set of all possible functions from a finite set X to a finite set Y iff F is closed under permutation of X. In this article, we prove that the number of those subsets can be neglected compared to the overall number of possible subsets. Further, we present some arguments wh

Alexander Bockmayr, Nicolai Pisaruk

Assembly line balancing problems consist in partitioning the work necessary to assemble a number of products among different stations of an assembly line. We present a hybrid approach for solving such problems, which combines constraint programming and integer programming.

J. P. Butler, R. W. Mair, S. Patz, D. Hoffmann

We demonstrate a minimally invasive nuclear magnetic resonance (NMR) technique that enables determination of the surface-area-to-volume ratio (S/V) of soft porous materials from measurements of the diffusive exchange of laser-polarized 129Xe between gas in the pore space and 129Xe dissolved in the solid phase. We apply this NMR technique to porous polymer sa

P. V. Parimi, N. Hakim, F. C. Chou, S. W. Cheong

New dielectric transitions are observed at common temperatures 32K and 245K, in isostructural $La_{2}CuO_{4+x}$ and $La_{5/3}Sr_{1/3}NiO_{4},$ that are signatures of local lattice (octahedral) instabilities. The present dielectric transitions reveal new aspects of the phase diagram of the perovskite cuprates and nickelates. They suggest that competition and

J. L. B. Faria, C. W. A. Paschoal, P. T. C. Freire, A. P. Ayala

The structural changes in Sr(0.66)Ba(0.34)Nb2O6 single crystal fibers when the temperature decreases from 295 to 10 K is investigated by dielectric constant measurements and Raman spectroscopy. The anomaly observed in the plot of e is associated to the variation in the intensity and frequency of some Raman modes. We observe that the intensity of some low ene

Rita Claudia Iotti, Fausto Rossi

The first global quantum simulation of semiconductor-based quantum-cascade lasers is presented. Our three-dimensional approach allows to study in a purely microscopic way the current-voltage characteristics of state-of-the-art unipolar nanostructures, and therefore to answer the long-standing controversial question: is charge transport in quantum-cascade las

Eliana Biolatti, Irene D&#39;Amico, Paolo Zanardi, Fausto Rossi

A detailed analysis of the electro-optical response of single as well as coupled semiconductor quantum dots is presented. This is based on a realistic ---i.e., fully tridimensional--- description of Coulomb-correlated few-electron states, obtained via a direct-diagonalization approach. More specifically, we investigate the combined effect of static electric

M. Windt, J. J. McGuire, T. Room, A. Pronin

We present optical conductivity data for Lu(Ni$_{1-x}$Co$_x$)$_2$B$_2$C over a wide range of frequencies and temperatures for x=0 and x=0.09. Both materials show evidence of being good Drude metals with the infrared data in reasonable agreement with dc resistivity measurements at low frequencies. An absorption threshold is seen at approximately 700 cm-1. In

Y. N. Chen, D. S. Chuu

The superradiant decay rate of Wannier exciton in one dimensional system is studied. The crossover behavior from 1D chain to 2D film is also examined. It is found that the decay rate shows oscillatory dependence on channel width L. When the quasi 1-D channel is embeded with planar microcavities, it is shown that the dark mode exciton can be examined experime

G. Litak

We study the effect of site diagonal disorder on the pairing amplitude by a perturbation method. Using an extended Hubbard model with the intersite attraction we analyze fluctuations of order parameter in presence of non-magnetic disorder and discuss the instability of various solutions with p-wave paring.

G. Litak

We study the effect of site diagonal, non-magnetic, disorder on the a pairing amplitude in an extended Hubbard model with the intersite attraction. Analyzing fluctuations of a pairing potential we discuss the instability of mixed solutions, &#39;s+d&#39; and &#39;s+id&#39;, in presence of disorder. The influence of disorder on extended s- and d-wave supercon

M. A. Vesaghi, A. Shafiekhani, K. Horiuchi

The visible band (band A) of Photoluminescence spectra of high-purity synthesized diamond is analyzed by deconvolution technique. A set of eight lines with distinct peak energy are found. The peak energy and the width of these lines were either constant or varies very slightly with temperature. The amplitude of the lines are significantly temperature. The cl

S. Viefers, T. H. Hansson, J. M. Leinaas

We briefly explain the notion of exclusion statistics and in particular discuss the concept of an ideal exclusion statistics gas. We then review a recent work where it is demonstrated that a {\em two-dimensional} Bose gas with repulsive delta function interactions obeys ideal exclusion statistics, with a fractional parameter related to the interaction streng

K. Takahata, I. Terasaki

We prepared polycrystalline samples of the A_xBO_2 type layered oxides Na_0.77MnO_2 and LiCoO_2, and measured thermal conductivity from 15 to 280 K. Na0.77MnO_2 shows a low thermal conductivity of 15 mW/cmK, while LiCoO_2 shows a much higher value of 40 mW/cmK at 280 K. By comparing them with the data of NaCo_2O_4, we have found that the low thermal conducti

A. G. Mal&#39;shukov, K. A. Chao

We have shown that electron spin density can be generated by a dc current flowing across a $pn$ junction with an embedded asymmetric quantum well. Spin polarization is created in the quantum well by radiative electron-hole recombination when the conduction electron momentum distribution is shifted with respect to the momentum distribution of holes in the spi

Ulrich Hohenester

We show how to describe Coulomb renormalization effects and dielectric screening in semiconductors and semiconductor nanostructures within a first-principles density-matrix description. Those dynamic variables and approximation schemes which are required for a proper description of dielectric screening are identified. It is shown that within the random-phase

Luca Marinelli, B. I. Halperin

The quasiparticle spectrum of a two-dimensional d-wave superconductor in the mixed state, H_c1 << H << H_c2, is studied for large values of the ``anisotropy ratio&#39;&#39; alpha_D = v_F/v_Delta. For a square vortex lattice rotated by 45 degrees from the quasiparticle anisotropy axes (and the usual choice of Franz--Tesanovic singular gauge transformation) we

Y. Kafri, D. Mukamel, L. Peliti

Experimental studies of the thermal denaturation of DNA yield a strong indication that the transition is first order. This transition has been theoretically studied since the early sixties, mostly within an approach in which the microscopic configurations of a DNA molecule are given by an alternating sequence of non-interacting bound segments and denaturated

Ryuichi Shindou, Naoto Nagaosa

The Berry phase due to the spin wavefunction gives rise to the orbital ferromagnetism and anomalous Hall effect in the non-coplanar antiferromagnetic ordered state on face centered cubic (fcc) lattice once the crystal is distorted perpendicular to (1,1,1) or (1,1,0)- plane. The relevance to the real systems $γ$-FeMn and NiS$_2$ is also discussed.

O. M. Stoll, M. I. Montero, J. Guimpel, Johan J. Akerman

We have investigated the periodic pinning of magnetic flux quanta in thin Nb films with rectangular arrays of magnetic dots. In this type of pinning geometry, a change in the periodicity and shape of the minima in the magnetoresistance occurs for magnetic fields exceeding a certain threshold value. This has been explained recently in terms of a reconfigurati

N. Ryzhanova, B. Dieny, C. Lacroix, N. Strelkov

Extraordinary Hall effect (EHE) in bilayer F/S(N) was investigated theoretically. The conductivity tensor $σ_{αβ}$ is calculated in the Kubo formalism with Green functions found as the solutions of the Gorkov equations. We considered diffuse transport in the ferromagnetic layer, taking into account as a main mechanism of electron resistivity s-d scattering.

Hans-Juergen Sommers, Dmitry V. Savin, Valentin V. Sokolov

The probability distribution of the proper delay times during scattering on a chaotic system is derived in the framework of the random matrix approach and the supersymmetry method. The result obtained is valid for an arbitrary number of scattering channels as well as arbitrary coupling to the energy continuum. The case of statistically equivalent channels is

Helmut G. Katzgraber, A. P. Young

We present results from simulations of the gauge glass model in three dimensions using the parallel tempering Monte Carlo technique. Critical fluctuations should not affect the data since we equilibrate down to low temperatures, for moderate sizes. Our results are qualitatively consistent with earlier work on the three and four dimensional Edwards-Anderson I

S. G. Djorgovski, A. Mahabal, R. Brunner, R. Williams

Like every other field of intellectual endeavor, astronomy is being revolutionised by the advances in information technology. There is an ongoing exponential growth in the volume, quality, and complexity of astronomical data sets, mainly through large digital sky surveys and archives. The Virtual Observatory (VO) concept represents a scientific and technolog

Martin A. Guerrero, Luis F. Miranda, You-Hua Chu, Monica Rodriguez

We present high-dispersion echelle spectroscopic observations and a narrow-band [N II] image of the remarkable jet-like features of He 2-90. They are detected in the echelle spectra in the H-alpha and [N II] lines but not in other nebular lines. The [N II]/H-alpha ratio is uniformly high, ~1. The observed kinematics reveals bipolar collimated outflows in the

J. Scott, J. Bechtold, M. Morita, A. Dobrzycki

We present a measurement of the mean intensity of the hydrogen-ionizing background radiation field at low redshift using 906 Ly-alpha absorption lines in 151 quasar spectra from the archives of the Faint Object Spectrograph on the Hubble Space Telescope. Using a maximum likelihood technique and the best estimates possible for each QSO&#39;s Lyman limit flux

Andrea Possenti, Nichi D&#39;Amico, Richard N. Manchester, John Sarkissian

We have discovered 12 new millisecond pulsars in 6 globular clusters in which no pulsars were previously known, in the first two years of a search at 1.4 GHz in progress at the Parkes radio telescope. Here we briefly describe the motivation, the new hardware and software systems adopted for this survey, and we present the results obtained thus far.

P. O. Petrucci, A. Merloni, A. Fabian, F. Haardt

We discuss the effects of a comptonizing corona on the appearance of the reflection components, and in particular of the reflection hump, in the X-rays spectra of accreting black holes. Indeed, in the framework of a thermal corona model, we expect that part (or even all, depending on the coronal covering factor) of the reflection features should cross the ho

Daniela Kirilova, Mihail Chizhov

We present a review of cosmological nucleosynthesis (CN) with neutrino oscillations, discussing the different effects of oscillations on CN, namely: increase of the effective degrees of freedom during CN, spectrum distortion of the oscillating neutrinos, neutrino number density depletion, and growth of neutrino-antineutrino asymmetry due to active-sterile os

M. Villar-Martin, D. De Young, A. Alonso-Herrero, M. Allen

One of the most popular explanations for the so-called alignment effect in high redshift (z>0.7) radio galaxies is the scattering by dust of the hidden quasar light. As shown by De Young (1998) a problem with the dust scattering model is that the short destruction time-scale for dust grains means that they will not survive the passage of the radio jet. We in

Keiichi Wada

Using high-resolution, three-dimensional hydrodynamical simulations, we investigate the structure of the interstellar medium in the central hundred pc region in galaxies, taking into account self-gravity of the gas, radiative cooling from 10 K to $10^8$ K, and energy feedback from supernovae. Similar to the previous two-dimensional results produced by Wada a

W. A. Dziembowski, D. O. Gough, G. Houdek, R. Sienkiewicz

There is growing observational evidence that the variability of red giants could be caused by excitation of global modes of oscillation. The most recent evidence of such oscillations was reported for alpha UMa by Buzasi et al.(2000). We address the problem of radial and nonradial mode excitation in red giants from the theoretical point of view. In particular

L. Di Fabrizio, A. Bragaglia, M. Tosi, G. Marconi

We present CCD BVI photometry of the intermediate age open cluster Pismis 2, covering from the brighter red giants to about 5 magnitudes below the main sequence turn-off. The cluster is heavily reddened and is possibly affected by a differential reddening of Delta E(B-V) ~= 0.04-0.06. Using the synthetic Colour - Magnitude Diagram method, we estimate in a se

T. R. Marsh, L. Morales-Rueda, D. Steeghs, P. Maxted

The 2dF QSO survey is a spectroscopic survey of 48,000 point-sources selected by colour with magnitudes in the range 18.35 < B < 20.95. Amongst QSOs, white dwarfs, narrow-line galaxies and other objects are some cataclysmic variables (CVs). This survey should be sensitive to intrinsically faint CVs. In the standard picture of CV evolution, these form the maj

O. Podladchikova, T. Dudok de Wit, V. Krasnoselskikh, B. Lefebvre

Recent measurements of quiet Sun heating events by Krucker and Benz (1998) give strong support to Parker&#39;s (1988) hypothesis that small scale dissipative events make the main contribution to the quiet heating. Moreover, combining their observations with the analysis by Priest et al. (2000), it can be concluded that the sources driving these dissipative e

Karen T. Lewis, Michael Eracleous, Rita M. Sambruna

In recent surveys of Radio-loud AGN, a new sub-class of objects, known as Weak-Line Radio Galaxies (WLRGs) has emerged. These radio galaxies have only weak, low-ionization optical emission lines. In the X-ray band, these objects are much fainter and have flatter spectra than broad-line and narrow-line radio galaxies. In these respects, WLRGs are reminiscent

S. Schmeja, S. Kimeswenger

Nebulae around symbiotic Miras look very much like genuine planetary nebulae, although they are formed in a slightly different way. We present near infrared photometry of known and suspected symbiotic nebulae obtained with the Deep Near Infrared Southern Sky Survey (DENIS). We demonstrate that the near infrared colours are an excellent tool to distinguish sy

E. Athanassoula, Ch. L. Vozikis, J. C. Lambert

In this paper we measure the two-body relaxation time from the angular deflection of test particles launched in a rigid configuration of field particles. We find that centrally concentrated configurations have relaxation times that can be shorter than those of the corresponding homogeneous distributions by an order of magnitude or more. For homogeneous distr

S. Borgani, F. Governato, J. Wadsley, N. Menci

We present results from high-resolution Tree+SPH simulations of galaxy clusters and groups, aimed at studying the effect of non-gravitational heating on the entropy of the ICM. We simulate three systems, having emission-weighted temperature T=0.6,1 and 3 keV, with spatial resolution better than 1% of the virial radius. We consider the effect of different pre

N. Manset, P. Bastien

We present polarimetric observations of a massive pre-main sequence short-period binary star of the Herbig Ae/Be type, MWC 1080. The mean polarization at 7660 A is 1.60% at 81.6 deg, or 0.6% at 139 deg if an estimate of the interstellar polarization is subtracted. The intrinsic polarization points to an asymmetric geometry of the circumstellar or circumbinar

Amr El-Zant, Isaac Shlosman, Yehuda Hoffman

Coupling the dark matter (DM) and baryonic components in galaxies via dynamical friction (by allowing the latter to be clumpy) leads to energy input into the DM. The resulting expanding tendency in the DM component overcomes the competing effect of adiabatic contraction, resulting from the shrinking gas component, and leads to a nearly constant density core.

Amr El-Zant

The stability of the dynamical trajectories of softened spherical gravitational systems is examined, both in the case of the full $N$-body problem and that of trajectories moving in the gravitational field of non-interacting background particles. In the latter case, for $N \ge 10000$, some trajectories, even if unstable, had exceedingly long diffusion times,

M. Nicklas, R. Borth, E. Lengyel, P. G. Pagliuso

We report measurements of the pressure-dependent superconducting transition temperature $T_c$ and electrical resistivity of the heavy-fermion compound CeCoIn$_5$. Pressure moves CeCoIn$_5$ away from its proximity to a quantum-critical point at atmospheric pressure. Experimental results are qualitatively consistent with theoretical predictions for strong-coup

J. Goldwin, S. B. Papp, B. DeMarco, D. S. Jin

We trap and cool a gas composed of 40K and 87Rb, using a two-species magneto-optical trap (MOT). This trap represents the first step towards cooling the Bose-Fermi mixture to quantum degeneracy. Laser light for the MOT is derived from laser diodes and amplified with a single high power semiconductor amplifier chip. The four-color laser system is described, a

N. Markovic, C. Christiansen, G. Martinez-Arizala, A. M. Goldman

The effect of an electric field on the conductance of ultrathin films of metals deposited on substrates coated with a thin layer of amorphous Ge was investigated. A contribution to the conductance modulation symmetric with respect to the polarity of the applied electric field was found in regimes in which there was no sign of glassy behavior. For films with

Jurgen Schaffner-Bielich, Dmitri Kharzeev, Larry McLerran, Raju Venugopalan

We argue that the transverse mass spectra of identified hadrons as measured in gold-gold collisions at BNL&#39;s Relativistic Heavy-Ion Collider (RHIC) follows a generalized scaling law. Such a scaling behavior is motivated by the idea of a Color Glass Condensate, or more generally, saturation of the gluon density. In particular, we describe the shapes of tr

Amihay Hanany, Amer Iqbal

We study N=1 four dimensional quiver theories arising on the worldvolume of D3-branes at del Pezzo singularities of Calabi-Yau threefolds. We argue that under local mirror symmetry D3-branes become D6-branes wrapped on a three torus in the mirror manifold. The type IIB (p,q) 5-brane web description of the local del Pezzo, being closely related to the geometr

Alex Eremenko, Andrei Gabrielov

We study the map which sends vectors of polynomials into their Wronski determinants. This defines a projection map of a Grassmann variety which we call a Wronski map. Our main result is computation of degrees of the real Wronski maps. Connections with real algebraic geometry and control theory are described.

A. Iqbal, A. H. Toor

We study two forms of a symmetric cooperative game played by three players, one classical and other quantum. In its classical form making a coalition gives advantage to players and they are motivated to do so. However in its quantum form the advantage is lost and players are left with no motivation to make a coalition.

A. Rajantie

When a symmetry gets spontaneously broken in a phase transition, topological defects are typically formed. The theoretical picture of how this happens in a breakdown of a global symmetry, the Kibble-Zurek mechanism, is well established and has been tested in various condensed matter experiments. However, from the viewpoint of particle physics and cosmology,

Alexander K. Hartmann, Federico Ricci-Tersenghi

A method is presented, which allows to sample directly low-temperature configurations of glassy systems, like spin glasses. The basic idea is to generate ground states and low lying excited configurations using a heuristic algorithm. Then, with the help of microcanonical Monte Carlo simulations, more configurations are found, clusters of configurations are d

R. Piffaretti, Ph. Jetzer, D. Puy, S. Schindler

We investigate the influence of the finite extension and the aspherical geometry of a galaxy cluster on the estimate of the Hubble constant through the Sunyaev-Zel&#39;dovich effect. An analysis of a recent CHANDRA image of the galaxy cluster RBS797 indicates a strong ellipticity and thus a pronounced aspherical geometry. We estimate the total mass of RBS797

Enrico Carlon, Enzo Orlandini, Attilio L. Stella

The nature and the universal properties of DNA thermal denaturation are investigated by Monte Carlo simulations. For suitable lattice models we determine the exponent c describing the decay of the probability distribution of denaturated loops of length l, $P \sim l^{-c}$. If excluded volume effects are fully taken into account, c= 2.10(4) is consistent with

Harald Merkel, Peter Bartsch, Dagmar Baumann, Jörg Bermuth

New data are presented on the p(e,e&#39;p)π^0 reaction at threshold at a four-momentum transfer of Q^2=0.05 GeV^2/c^2. The data were taken with the three-spectrometer setup of the A1 Collaboration at the Mainz Microtron MAMI. The complete center of mass solid angle was covered up to a center of mass energy of 4 MeV above threshold. Combined with measurements

A. Belhaj, E. H. Saidi

Using the algebraic geometry method of Berenstein et al (hep-th/0005087), we reconsider the derivation of the non commutative quintic algebra ${\mathcal{A}}_{nc}(5)$ and derive new representations by choosing different sets of Calabi-Yau charges ${C_{i}^{a}}$. Next we extend these results to higher $d$ complex dimension non commutative Calabi-Yau hypersurfac

Sujata Gupta, Alan F. Heavens

The statistical properties of a map of the primary fluctuations in the cosmic microwave background (CMB) may be specified to high accuracy by a few thousand power spectra measurements, provided the fluctuations are gaussian, yet the number of parameters relevant for the CMB is probably no more than about 10-20. There is consequently a large degree of redunda

Shmuel Elitzur, Gor Sarkissian

The algebraic classification of Cardy for boundary states on a $G/H$ coset CFT of a compact group G, is geometrically realized on the corresponding manifold resulting from gauging the WZW model. The branes consist of H orbits of quantized G conjugacy classes shifted by quantized H conjugacy classes.

T. Yamashita, S. Takahashi, H. Imamura, S. Maekawa

We study theoretically the effect of spin relaxation on the spin transport in a ferromagnet/superconductor(FM/SC) tunnel junction. When spin-polarized electrons are injected into the SC from the FM, nonequilibrium spin accumulation as well as spin current are created in the range of the spin diffusion length in the SC. We find that the spin diffusion length

Ali Havare, Taylan Yetkin

In this work the photon equation (massless Duffin-Kemmer-Petiau equation) is written expilicitly for general type of stationary Gödel space-times and is solved exactly for Gödel-type and Gödel space-times. Harmonic oscillator behaviour of the solutions is discussed and energy spectrum of photon is obtained.

A. A. Tseytlin

We discuss some aspects of closed superstrings in Melvin-type magnetic backgrounds. A 2-parameter family of such NS-NS backgrounds are exactly solvable as weakly coupled string models with the spectrum containing tachyonic modes. Magnetic field allows one to interpolate between free superstring theories with periodic and antiperiodic boundary conditions for

Yoshiaki Koma, Miho Koma, Dietmar Ebert, Hiroshi Toki

We perform a path-integral analysis of the string representation of the dual Abelian Higgs (DAH) model beyond the London limit, where the string describing the vortex of a flux tube has a finite thickness. We show that besides an additional vortex core contribution to the string tension, a modified Yukawa interaction appears as a boundary contribution in the

R. Aditi Simha, Sriram Ramaswamy

We construct the hydrodynamic equations for {\em suspensions} of self-propelled particles (SPPs) with spontaneous orientational order, and make a number of striking, testable predictions:(i) SPP suspensions with the symmetry of a true {\em nematic} are {\em always} absolutely unstable at long wavelengths.(ii) SPP suspensions with {\em polar}, i.e., head-tail

Henry P. Stapp

I shall consider each of the 18 claims made by Mohrhoff, and explain, in each case, why I take the path opposite to the one by which he seeks to remove the effects of our thoughts on the activities of our quantum mechanically described brains.

Ioan Sturzu

Using an explicit Euler substitution it was obtained a system of differential equations, which can be used to find the solution of time-dependent 1-dimentional Schrődinger equation for a general form of the time-dependent potential.

A. G. White, D. F. V. James, W. J. Munro, P. G. Kwiat

We report the creation of a wide range of quantum states with controllable degrees of entanglement and entropy using an optical two-qubit source based on spontaneous parametric downconversion. The states are characterised using measures of entanglement and entropy determined from tomographically determined density matrices. The Tangle-Entropy plane is introd

Scott M. Hitchcock

Do quantum computers already exist in Nature? It is proposed that they do. Photosynthesis is one example in which a &#39;quantum computer&#39; component may play a role in the &#39;classical&#39; world of complex biological systems. A &#39;translation&#39; of the standard metabolic description of the &#39;front-end&#39; light harvesting complex in photosynth

Charles Francis

The purpose of this paper is to construct a quantum field theory suitable for describing quantum electrodynamics and Yang-Mills theory in a form which satisfies the conditions of the Millennium prize offered by the Clay Mathematics Institute as described by Jaffe and Witten [12], by showing that it satisfies &#39;axioms at least as strong as those cited by&#

K. Hafidi, T. -S. H. Lee

The $d(e,e&#39;π^+)$ reaction in the parallel kinematics has been investigated using a dynamical model of pion electroproduction on the nucleon. A unitary $πNN$ model has been used in order to examine the effects due to the final two-nucleon interactions, pion rescattering from the second nucleon, and the intermediate $NN$ and $NΔ$ interactions. It has been

W. W. Daehnick, Swapan K. Saha, R. W. Flammang, H. O. Meyer

A first measurement of longitudinal as well as transverse spin correlation coefficients for the reaction $\vec{p}\vec{p}\to pnπ^+$ was made using a polarized proton target and a polarized proton beam. We report kinematically complete measurements for this reaction at 325, 350, 375 and 400 MeV beam energy. The spin correlation coefficients $A_{xx}+A_{yy}, A_{

P. Achenbach, S. Baunack, K. Grimm, T. Hammel

The anticipated use of more than one thousand lead fluoride (PbF2) crystals as a fast and compact Cherenkov calorimeter material in a parity violation experiment at MAMI stimulated the investigation of the light yield (L.Y.) of these crystals. The number of photoelectrons (p.e.) per MeV deposited energy has been determined with a hybrid photomultiplier tube

Koichi Fujimoto, Kunihiko Kaneko

A chain of coupled chaotic elements with different time scales is studied. In contrast with the adiabatic approximation, we find correlations between faster and slower elements when the differences in the time scales of the elements lie within a certain range. For such correlations to occur, three features are essential: strong correlations among the element

Mason A. Porter

Nonlinear dynamics (``chaos theory&#39;&#39;) and quantum mechanics are two of the scientific triumphs of the 20th century. The former lies at the heart of the modern interdisciplinary approach to science, whereas the latter has revolutionized physics. Both chaos theory and quantum mechanics have achieved a fairly large level of glamour in the eyes of the ge

Gerald Kaiser

The representation of solutions of Maxwell&#39;s equations as superpositions of scalar wavelets with vector coefficients developed earlier is generalized to wavelets with polarization, which are matrix-valued. The construction proceeds in four stages: (1) A Hilbert space H of solutions is considered, based on a conformally invariant inner product. (2) The an

Gerald Kaiser

It is shown that any convolution operator in the time domain can be represented exactly as a multiplication operator in the time-scale (wavelet) domain. The Mellin transform gives a one-to-one correspondence between frequency filters (multiplications in the frequency domain) and scale filters (multiplications in the scale domain), subject to the convergence

Gerald Kaiser

The quantum mechanical harmonic oscillator Hamiltonian generates a one-parameter unitary group W(θ) in L^2(R) which rotates the time-frequency plane. In particular, W(π/2) is the Fourier transform. When W(θ) is applied to any frame of Gabor wavelets, the result is another such frame with identical frame bounds. Thus each Gabor frame gives rise to a one-param

Gerald Kaiser, R. F. Streater

The act of measuring a physical signal or field suggests a generalization of the wavelet transform that turns out to be a windowed version of the Radon transform. A reconstruction formula is derived which inverts this transform. A special choice of window yields the &#34;Analytic--Signal transform&#34; (AST), which gives a partially analytic extension of fun

Gerald Kaiser

A new representation for solutions of Maxwell&#39;s equations is derived. Instead of being expanded in plane waves, the solutions are given as linear superpositions of spherical wavelets dynamically adapted to the Maxwell field and well-localized in space at the initial time. The wavelet representation of a solution is analogous to its Fourier representation

Paul Biran, Leonid Polterovich, Dietmar Salamon

The main result asserts the existence of noncontractible periodic orbits for compactly supported time dependent Hamiltonian systems on the unit cotangent bundle of the torus or of a negatively curved manifold whenever the generating Hamiltonian is sufficiently large over the zero section. The proof is based on Floer homology and on the notion of a relative s

A. B. Yanovski

We consider some special type extensions of an arbitrary Lie algebra ${\cal G}$, arising in the theory of Lie-Poisson structures over $({\cal G}^*)^n$, where ${\cal G}^*$ is the dual of ${\cal G}$. We show that some classes of these extensions can be constructed in a natural way using some linear bundles of Lie algebras.

Gabriel Mitric, Izu Vaisman

The paper starts with an interpretation of the complete lift of a Poisson structure from a manifold M to its tangent bundle TM by means of the Schouten- Nijenhuis bracket of covariant symmetric tensor fields defined by the co- tangent Lie algebroid of M. Then, we discuss Poisson structures of TM which have a graded restriction to the fiberwise polynomial alg

A. Iovita, M. Spiess

In this paper we prove a Gross-Zagier type formula for the anticyclotomic p-adic L-function of an elliptic modular form f of higher weight and of multiplicative type at p. For such f we also decribe explicitely the local Galois representation attached to it at p and compare the Fontaine-Mazur and Teitelbaum L-invariants.

Torsten Ekedahl

This paper takes its starting point in an idea of Grothendieck on the representation of homotopy types. We show that any locally finite nilpotent homotopy can be represented by a simplicial set which is a finitely generated free group in all degrees and whose maps are given by polynomials with rational coefficients. Such a simplicial set is in some sense a u

Ulrich Bunke, Martin Olbrich

We consider a geometrically finite discrete group of conformal transformations of the sphere. Further we consider distributions which are supported on the limit set and are invariant with conformal weight. We estimate their regularity in terms of the conformal weight, the Hausdorff dimension of the limit set, and the maximal rank of the cusps of the group.