December 2001 arXiv papers — page 8

P. S. Cornaglia, K. Hallberg, C. A. Balseiro

We study the problem of the low-energy quasiparticle spectrum of the extended t-J model and analyze the coherent hopping between weakly coupled planes described by this model. Starting with a two-band model describing the Cu-O planes and the unoccupied bands associated to the metallic atoms located in between the planes, we obtain effective hopping matrix el

Erik Luijten, Michael E. Fisher, Athanassios Z. Panagiotopoulos

The 1:1 equisized hard-sphere electrolyte or restricted primitive model has been simulated via grand-canonical fine-discretization Monte Carlo. Newly devised unbiased finite-size extrapolation methods using temperature-density, (T, rho), loci of inflections, Q = <m^2>^2/<m^4> maxima, canonical and C_V criticality, yield estimates of (T_c, rho_c) to +- (0.04,

A. Virosztek, K. Maki, B. Dora

It has been proposed, that unconventional density waves (UDW) are possible candidates for systems with hidden order parameter. Unlike in conventional density waves, no periodic modulation of either the charge-, or the spin-density is present in UDW, in spite of a clear thermodynamic signal. Although the unconventional spin density wave (USDW) has been sugges

K. A. Muttalib, Y. Chen, M. E. H. Ismail

Theory of Random Matrix Ensembles have proven to be a useful tool in the study of the statistical distribution of energy or transmission levels of a wide variety of physical systems. We give an overview of certain q-generalizations of the Random Matrix Ensembles, which were first introduced in connection with the statistical description of disordered quantum

L. G. L. Wegener, P. B. Littlewood

We study the motion of free magnetic polarons in a paramagnetic background of fluctuating local moments. The polaron can tunnel only to nearby regions of local moments when these fluctuate into alignment. We propose this fluctuation induced hopping as a new transport mechanism for the spin polaron. We calculate the diffusion constant for fluctuation induced

Marta Sales, Hajime Yoshino

We study the stability of the glassy equilibrium state of a directed polymer in random media against weak perturbations including the intriguing problem of temperature-chaos. The statistical correlation of two real replica systems under perturbations, such as small difference of temperature, is studied using the mapping to a quantum problem of interacting bo

Pierre-Gilles de Gennes

Certain (non polymeric) fluids show an anomalously low friction when flowing against well chosen solid walls. We discuss here one possible explanation, postulating that a gaseous film of small thickness h is present between fluid and wall. When h is smaller than the mean free path l of the gas (Knudsen regime) the Navier length b is expected to be independen

T. Jarlborg

High purity iron, which transforms into the hcp phase under pressure, has recently been reported to be superconducing in the pressure range 150-300 kBar [shim]. The electronic structure and the electron-phonon coupling ($λ_{ph}$) are calculated for hcp iron at different volumes. A parameter-free theory for calculating the coupling constants $λ_{sf}$ from fer

M. Horibe, K. Shigemoto

We give the simple proof of the star-triangle relation of the chiral Potts model. We also give the constructive way to understand the star-triangle relation of the chiral Potts model, which may give the hint to give the new integrable models.

S. J. Youn, B. R. Sahu, Kwang S. Kim

We have performed an all-electron fully relativistic density functional calculation to study the magnetic properties of FeBr2. We show for the first time that the correlation effect enhances the contribution from orbital degrees of freedom of $d$ electrons to the total magnetic moment on Fe$^{2+}$ as opposed to common notion of nearly total quenching of the

K. Schoutens, E. Ardonne, F. J. M. van Lankvelt

We briefly summarize properties of quantum Hall states with a pairing or clustering property. Their study employs a fundamental connection with parafermionic Conformal Field Theories. We report on closed form expressions for the many-body wave functions and on multiplicities of the fundamental quasi-hole excitations.

Masaaki Nakamura, Synge Todo

We propose an order parameter to characterize valence-bond-solid (VBS) states in quantum spin chains, given by the ground-state expectation value of a unitary operator appearing in the Lieb-Schultz-Mattis argument. We show that the order parameter changes the sign according to the number of valence bonds (broken valence bonds) at the boundary for periodic (o

E. Duval, L. Saviot, A. Mermet, L. David

The effects of plasticization of poly(methyl methacrylate) glass on the boson peaks observed by Raman and neutron scattering are compared. In plasticized glass the cohesion heterogeneities are responsible for the neutron boson peak and partially for the Raman one, which is enhanced by the composition heterogeneities. Because the composition heterogeneities h

Takao Morinari

We propose a mechanism of unconventional superconductivity in two-dimensional strongly-correlated electron systems. We consider a two-dimensional Kondo lattice system or double-exchange system with spin-orbit coupling arising from buckling of the plane. We show that a Chern-Simons term is induced for a gauge field describing the phase fluctuations of the loc

M. Ya. Amusia, A. Z. Msezane, V. R. Shaginyan

A many-body system of fermion atoms with a model interaction characterized by the scattering length $a$ is considered. We treat both $a$ and the density as parameters assuming that the system can be created artificially in a trap. If $a$ is negative the system becomes strongly correlated at densities $ρ\sim |a|^{-3}$, provided the scattering length is the do

S. A. Haine, J. J. Hope, N. P. Robins, C. M. Savage

A multimode model of a continuously pumped atom laser is shown to be unstable below a critical value of the scattering length. Above the critical scattering length, the atom laser reaches a steady state, the stability of which increases with pumping. Below this limit the laser does not reach a steady state. This instability results from the competition betwe

Zheng Weihong, C. J. Hamer, J. Oitmaa, R. R. P. Singh

We have developed a series expansion method for calculating the zero-temperature properties of lattice electron models for variable electron density, i.e. for finite doping away from the half-filled case. This is done by introducing particle fluctuation terms in both the unperturbed Hamiltonian and perturbation. The method is demonstrated by application to t

J. B. Marston, A. Sudbo

This preprint has been withdrawn, as the evidence for persistent currents found with the &#34;infinite-size&#34; DMRG algorithm has not been reproduced with the (presumably more accurate) &#34;finite-size&#34; version of the algorithm (M. Troyer and U. Schollwoeck, private communiation). A much clearer example of long-range order in orbital currents is prese

Y. M. Galperin, V. L. Gurevich, V. I. Kozub, A. L. Shelankov

The theory of thermoelectric effects in superconductors is discussed in connection to the recent publication by Marinescu and Overhauser, Phys. Rev. B 55, 11637 (1997). We argue that the charge on-conservation arguments by Marinescu and Overhauser do not require any revision of the Boltzmann transport equation in superconductors, and show that their ``electr

Joel R. Primack, Risa H. Wechsler, Rachel S. Somerville

Data on galaxies at high redshift, identified by the Lyman-break photometric technique, can teach us about how galaxies form and evolve. The stellar masses and other properties of such Lyman break galaxies (LBGs) depend sensitively on the details of star formation. In this paper we consider three different star formation prescriptions, and use semi-analytic

R. Brent Tully

In the local part of the universe, a majority of the total mass is in only a small number of groups with short dynamical times. The Virgo Cluster dominates far out of proportion to its contribution in light. Ninety percent of the total mass is in groups with 12.5 < log (M/M_sun) < 15.

Joseph J. Mohr

Surveys of galaxy clusters provide a promising method of testing models of structure formation in the universe. Within the context of our standard structure formation scenario, surveys provide measurements of the geometry of the universe and the nature of the dark energy and dark matter. Cluster catalogues will be constructed using some combination of X-ray,

J. Richard Bond

I highlight the remarkable advances in the past few years in CMB research on total primary anisotropies, in determining the power spectrum, deriving cosmological parameters from it, and more generally lending credence to the basic inflation-based paradigm for cosmic structure formation, with a flat geometry, substantial dark matter and dark energy, baryonic

N. R. Hausen, R. J. Reynolds, L. M. Haffner, S. L. Tufte

We have used the Wisconsin H-Alpha Mapper (WHAM) facility to measure the interstellar H-Alpha emission toward the high Galactic latitude O star HD 93521 (l = 183.1, b = +62.2). Three emission components were detected having radial velocities of -10 km s^{-1}, -51 km s^{-1}, and -90 km s^{-1} with respect to the local standard of rest (LSR) and H-Alpha intens

A. A. Berezhnoi, E. Bervalds, O. B. Khavroshkin, G. Ozolins

Radioseismology is based on registration and interpretation of radio emission of seismic origin. Non-thermal radio emission of the Moon was detectedat 13 and 21 cm on July 30 - August 2, 1999. Strong oscillations of the non-thermal lunar radio flux at 25 mm were detected during the leonid meteor shower on November 17-18, 2000. The time of maxima of oscillati

Todd J. Henry, Lucianne M. Walkowicz, Todd C. Barto, David A. Golimowski

Broadband optical spectra are presented for 34 known and candidate nearby stars in the southern sky. Spectral types are determined using a new method that compares the entire spectrum with spectra of more than 100 standard stars. We estimate distances to 13 candidate nearby stars using our spectra and new or published photometry. Six of these stars are proba

D. I. Jones, N. Andersson, N. Stergioulas

We present the results of numerical time evolutions of the linearised perturbations of rapidly and rigidly rotating Newtonian polytropes while making the Cowling approximation. The evolution code runs stably for hundreds of stellar rotations, allowing us to compare our results with previously published eigenmode calculations, for instance the f-mode calculat

David E. Harker, Steven J. Desch

Silicate dust grains in the interstellar medium are known to be mostly amorphous, yet crystalline silicate grains have been observed in many long-period comets and in protoplanetary disks. Annealing of amorphous silicate grains into crystalline grains requires temperatures > 1000 K, but exposure of dust grains in comets to such high temperatures is incompati

V. K. Dubrovich

The process of forming an image of a cosmological point source (CPS) in condition of high optical depth is considered accounting for all types of interactions. It is shown that the energy conservation law causes the size of this image which is keeping constant over all redshifts of the CPSs. This effect must be taken into account for the consideration of the

C. L. Carilli, K. Kohno, R. Kawabe, K. Ohta

We present moderate (1&#39;&#39;) and high resolution (0.2&#39;&#39;) observations of the CO(2-1) emission at 43 GHz, and radio continuum emission at 1.47 GHz, from the z=4.7 QSO BRI 1202-0725 and the z=4.4 QSO BRI 1335--0417 using the Very Large Array. The moderate resolution observations show that in both cases the CO emission is spatially resolved into tw

G. A. Tammann, B. Reindl, F. Thim, A. Saha

The local expansion field is mapped using Cepheids, a complete sample of TF distances, and nearby cluster distances. The large-scale field is mapped using Cepheid-calibrated blue SNeIa. These data give Ho(local)=59.2+/-1.4 [km/s Mpc^-1] and Ho(cosmic)=57.4+/-2.3. The intermediate expansion field (1200 < v < 10000km/s) is less well calibrated but fully consis

Jean Kaplan, Jacques Delabrouille

Some sources of systematic errors, specific to polarized CMB measurements using bolometers, are examined. Although the evaluations we show have been made in the context of the Planck mission (and more specifically the Planck HFI), many of our conclusions are valid for other experiments as well.

M. Tafalla, P. C. Myers, P. Caselli, C. M. Walmsley

(Abridged) We present evidence that low-mass starless cores, the simplest units of star formation, are systematically differentiated in their chemical composition. Molecules including CO and CS almost vanish near the core centers, where the abundance decreases by one or two orders of magnitude. At the same time, N2H+ has a constant abundance, and the fractio

S. Campana, L. Stella, T. Belloni, G. L. Israel

We report on the results of a series of X-ray observations of the transient black hole candidate XTE J2012+381 during the 1998 outburst performed with the BeppoSAX satellite. The observed broad-band energy spectrum can be described with the superposition of an absorbed disk black body, an iron line plus a high energy component, modelled with either a power l

J. E. Grindlay, C. O. Heinke, P. D. Edmonds, F. Camilo

We summarize the x-ray properties of the complete samples of millisecond pulsars (MSPs) detected in our Chandra observations of the globular clusters 47 Tuc and NGC 6397. The 47 Tuc MSPs are predominantly soft sources suggestive of thermal emission from the neutron star polar cap and have x-ray luminosities in a surprisingly narrow range (Lx ~--4 x 10^{30} e

Erik Kuulkers

I found one long X-ray flare from the X-ray burster GX 3+1 in almost 6 years of observations with the RXTE All Sky Monitor (ASM). The event had a peak flux of about 1.1 Crab (1.5-12 keV), lasted between 4.4 and 16.2 hours and exhibited a fluence of more than about 5x10^{41} erg for a source distance of 5 kpc. During the exponential-like decay, with an expone

Markus Kissler-Patig

Old, metal-poor globular clusters trace the formation and evolution of early-type galaxies. Their are the best probes, at low redshift, of the building-up of galaxy halos at high redshift. Their properties constrain the characteristics of their progenitors. Recent results suggest that DLAs at z>3 are the likely hosts for their formation. Finally, they shed l

Patrick McDonald, Jordi Miralda-Escudé, Renyue Cen

We present predictions of the correlation between the Lyman-alpha forest absorption in quasar spectra and the mass within \sim 5 Mpc/h (comoving) of the line of sight, using fully hydrodynamic and hydro-PM numerical simulations of the cold dark matter model supported by present observations. The observed correlation based on galaxies and the Lya forest can b

The EAS-TOP, MACRO Collaborations

A measurement of the lateral distribution of Cherenkov light in Extensive Air Showers (EAS) at E0 = 10-100 TeV and a study of the compatibility of the photon number spectra with the expectations from the direct measurements of p and He spectra and the Corsika-QGSJET propagation code in the atmosphere have been performed at the National Gran Sasso Laboratorie

A. A. Watson

Reasons for the current interest in cosmic rays above 10^19 eV are described. The latest results on the energy spectrum, arrival direction distribution and mass composition of cosmic rays are reviewed, including data that were reported after the meeting in Blois in June 2001. The enigma set by the existence of ultra high-energy cosmic rays remains. Ideas pro

The EAS-TOP, MACRO Collaborations

We report the analysis of the Ne-Nmuon coincident events collected by the MACRO/EAS-TOP collaboration at the Gran Sasso Laboratories. The result points to a primary composition becoming heavier around the knee of the primary spectrum (in the energy region 10**15-10**16 eV). The result is in very good agreement with the measurements of EAS-TOP alone at the su

T. Beckert, T. P. Krichbaum, G. Cimo&#39;, L. Fuhrmann

Radio variability on timescales from a few hours to several days in extragalactic flat-spectrum radio sources is generally classified as intra-day variability (IDV). The origin of this short term variability is still controversial and both extrinsic and intrinsic mechanisms must be considered and may both contribute to the observed variations. The measured l

S. Andreon

Using new observations of the galaxy cluster A118 at intermediate redshift (z=0.31) in the Ks band, we were able to detect the cluster from the center to half the Abell radius (1.5 Mpc, Ho=50 km/s/Mpc) and possibly to 2.0 Mpc. The analysis of both the spatial distribution of galaxies of various luminosities and of the luminosity function (LF) of galaxies in

Jayant Murthy, R. C. Henry, L. J. Paxton, S. D. Price

We have observed intense diffuse radiation in the UV (1400 A - 2600 A) from three fields around M42 in Orion. Intensities of 20000 photons cm-2 s-1 sr-1 A-1 were observed to the east and west of M42 with 8000 photons cm-2 s-1 sr-1 A-1 south of the nebula. Enhanced emission, perhaps associated with a nearby complex of molecular clouds observed in CO, was dete

W. A. Heindl, W. Coburn, D. E. Gruber, R. E. Rothschild

Observations of the transient accreting pulsar XTE J1946+274 made with the Rossi X-ray Timing Explorer during the course of the 1998 September-November outburst, reveal a cyclotron resonance scattering feature (or &#34;cyclotron line&#34;) in the hard X-ray spectrum near 35 keV. We determine a centroid energy of 36.2 +0.5/-0.7 keV, which implies a magnetic f

M. Bertolini, P. Di Vecchia, G. Ferretti, R. Marotta

We discuss fractional D3-branes on the orbifold C^3/Z_2*Z_2. We study the open and the closed string spectrum on this orbifold. The corresponding N=1 theory on the brane has, generically, a U(N_1)*U(N_2)*U(N_3)*U(N_4) gauge group with matter in the bifundamental. In particular, when only one type of brane is present, one obtains pure N=1 Yang-Mills. We study

L. Csernai, L. Jenkovszky, K. Kontros, A. Lengyel

We study the interface between Regge behavior and DGLAP evolution in a non-perturbative model for the nucleon structure function based on a multipole pomeron exchange. This model provides the input for a subsequent DGLAP evolution that we calculate numerically. The soft input and its evolution give a good fit to the experimental data in the whole available r

J. L. F. Barbon, E. Rabinovici

We discuss some aspects of the behaviour of a string gas at the Hagedorn temperature from a Euclidean point of view. Using AdS space as an infrared regulator, the Hagedorn tachyon can be effectively quasi-localized and its dynamics controled by a finite energetic balance. We propose that the off-shell RG flow matches to an Euclidean AdS black hole geometry i

Gary N. Felder, Andrei Frolov, Lev Kofman

We study the dynamical equations for extra-dimensional dependence of a warp factor and a bulk scalar in 5d brane world scenarios with induced brane metric of constant curvature. These equations are similar to those for the time dependence of the scale factor and a scalar field in 4d cosmology, but with the sign of the scalar field potential reversed. Based o

E. Comforti, Y. C. Chung, M. Heiblum, V. Umansky

We employ shot noise measurements to characterize the effective charge of quasiparticles, at filling factor nu=1/3 of the fractional quantum Hall regime, as they scatter from an array of identical weak backscatterers. Upon scattering, quasiparticles are known to bunch, e.g., only three e/3 charges, or &#39;electrons&#39; are found to traverse a rather opaque

S. Wakimoto, C. Stock, R. J. Birgeneau, Z. -G. Ye

Neutron scattering measurements of the lowest-energy TO phonons in the relaxor Pb(Mg1/3Nb2/3)O3 (PMN) are reported for 10<=T<=750 K. The soft mode, which is overdamped by the polar nanoregions below the Burns temperature T_d = 620 K, surprisingly recovers below 220 K. The square of the soft mode energy hw0^2 increases linearly with decreasing temperature, an

Luis A. Anchordoqui, Jonathan L. Feng, Haim Goldberg, Alfred D. Shapere

If extra spacetime dimensions and low-scale gravity exist, black holes will be produced in observable collisions of elementary particles. For the next several years, ultra-high energy cosmic rays provide the most promising window on this phenomenon. In particular, cosmic neutrinos can produce black holes deep in the Earth's atmosphere, leading to quasi-horiz

M. Faber, A. N. Ivanov

We construct a consistent quantum field theory of a free massless (pseudo)scalar field in 1+1-dimensional space-times free of infrared divergences. We show that a continuous symmetry of (pseudo)scalar field translations is spontaneously broken. Goldstone bosons appear as quanta of a free massless (pseudo)scalar field. We show that the main inequality between

Nicolas Macris, Stephane Ouvry

The projection of a two dimensional planar system on the higher Landau levels of an external magnetic field is formulated in the language of the non commutative plane and leads to a new class of star products.

Dominic Brecher, Bert Janssen, Yolanda Lozano

Matrix string theory is equivalent to type IIA superstring theory in the light-cone gauge, together with extra degrees of freedom representing D-brane states. It is therefore the appropriate framework in which to study systems of multiple fundamental strings expanding into higher-dimensional D-branes. Starting from Matrix theory in a weakly curved background

S. Abel, S. Khalil, O. Lebedev

We show that string models with low energy supersymmetry which accommodate the fermion mass hierarchy generally give non-universal soft trilinear couplings (A-terms). In conjunction with the apparently large Cabibbo-Kobayashi-Maskawa (CKM) phase, this results in large fermion EDMs even in the absence of CP violating phases in the supersymmetry breaking terms

N. Bartolo, S. Matarrese, A. Riotto

Correlated adiabatic and isocurvature perturbation modes are produced during inflation through an oscillation mechanism when extra scalar degrees of freedom other than the inflaton field are present. We show that this correlation generically leads to sizeable non-Gaussian features both in the adiabatic and isocurvature perturbations. The non-Gaussianity is f

E. M. C. Abreu, J. A. Helayel-Neto, M. Hott, W. A. Moura-Melo

Dirac-like monopoles are studied in three-dimensional Abelian Maxwell and Maxwell-Chern-Simons models. Their scalar nature is highlighted and discussed through a dimensional reduction of four-dimensional electrodynamics with electric and magnetic sources. Some general properties and similarities of them when are considered in Minkowski or Euclidian space are

Lucio Fassarella, Bert Schroer

Wigner&#39;s irreducible positive energy representations of the Poincare group are often used to give additional justifications for the Lagrangian quantization formalism of standard QFT. Here we study another more recent aspect. We explain in this paper modular concepts by which we are able to construct the local operator algebras for all standard positive e

Sergey P. Kuznetsov

The bifurcation transition is studied for the onset of intermittency analogous to the Pomeau-Manneville mechanism of type-I, but generalized for the presence of a quasiperiodic external force. The analysis is concentrated on the torus-fractalization (TF) critical point that occurs at some critical amplitude of driving. (At smaller amplitudes the bifurcation

Rino Bandiera, Roberto Neri, Riccardo Cesaroni

We present the results of 1.3 mm observations of the Crab Nebula, performed with the MPIfR bolometer arrays at the IRAM 30-m telescope. The maps obtained, of unprecedented quality at these wavelengths, allow a direct comparison with high-resolution radio maps. Although the spatial structure of the Crab Nebula does not change much from radio to millimetre wav

S. Yu. Orevkov, V. V. Shevchishin

It is shown that two braids represent transversally isotopic links if and only if one can pass from one braid to another by conjugations in braid groups, positive Markov moves, and their inverses.

A. Nogga, H. Kamada, W. Gloeckle

The hypernuclei $^4_Λ$He and $^4_Λ$H provide important information on the hyperon-nucleon interaction. We present accurate Faddeev-Yakubovsky calculations for the $Λ$ separation energies of the $0^+$ ground and the $1^+$ excited states based on the Nijmegen SC YN interactions. We explicitly take the $Σ$ admixture into account. Mass differences of the baryons

Lauro Moscardini, Matthias Bartelmann, Sabino Matarrese, Paola Andreani

We study the clustering properties of the galaxy clusters detectable for the Planck satellite due to their thermal Sunyaev-Zel&#39;dovich effect. We take the past light-cone effect and the redshift evolution of both the underlying dark matter correlation function and the cluster bias factor into account. A theoretical mass-temperature relation allows us to c

F. La Franca, F. Fiore, C. Vignali, A. Antonelli

We present optical spectroscopic identifications of hard X-ray (5-10 keV) selected sources belonging to the HELLAS sample obtained with BeppoSAX down to a 5-10 keV flux limit of f_{5-10 keV}~3x10^-14 erg cm^-2 s^-1. The sample consists of 118 sources. 25 sources have been identified trough correlations with catalogues of known sources. 49 have been searched

David Hrencecin, Louis H. Kauffman

In this paper, we discuss filamentations on oriented chord diagrams. When a filamentation cannot be realized on an oriented chord diagram, then the corresponding flat virtual knot is non-trivial. If a flat knot diagram is non-trivial, then any virtual diagram whose shadow is the flat diagram must also be non-trivial. We introduce a class of flat diagrams for

Toru Hirayama

In a preceding paper [T. Hirayama, Prog. Theor. Phys. 106 (2001), 71], the power of the classical radiation emitted by a moving charge was evaluated in the Rindler frame. In this paper, we give a simpler derivation of this radiation formula, including an estimation of the directional dependence of the radiation. We find that the splitting of the energy-momen

M. Klasen, B. A. Kniehl, L. N. Mihaila, M. Steinhauser

We present theoretical predictions for the transverse-momentum distribution of J/psi mesons promptly produced in gamma gamma collisions within the factorization formalism of nonrelativistic quantum chromodynamics, including the contributions from both direct and resolved photons, and we perform a conservative error analysis. The fraction of J/psi mesons from

ZEUS Collaboration

The dijet cross section in photoproduction has been measured with the ZEUS detector at HERA using an integrated luminosity of 38.6 pb$^{-1}$. The events were required to have a virtuality of the incoming photon, $Q^2$, of less than 1 GeV$^2$ and a photon-proton centre-of-mass energy in the range $134 < W_{γp} < 277$ GeV. Each event contains at least two jets

C. Dams, R. Kleiss, P. Draggiotis, E. N. Argyres

We introduce a class of self-interacting scalar theories in which the various coupling contants obey a recursive relation. These imply a particularly simple form for the generating function of the Feynman amplitudes with vanishing external momenta, as well as for the effective potential. In addition we discuss an interesting duality inherent in these models.

S. Ferrara, M. A. Lledo

We consider simple superalgebras which are a supersymmetric extension of $\fspin(s,t)$ in the cases where the number of odd generators does not exceed 64. All of them contain a super Poincaré algebra as a contraction and another as a subalgebra. Because of the contraction property, some of these algebras can be interpreted as de Sitter or anti de Sitter supe

Youngjai Kiem, Yeonjung Kim, Cheol Ryou, Haru-Tada Sato

We develop a method to compute the one-loop effective action of noncommutative U(1) gauge theory based on the bosonic worldline formalism, and derive compact expressions for N-point 1PI amplitudes. The method, resembling perturbative string computations, shows that open Wilson lines emerge as a gauge invariant completion of certain terms in the effective act

Julio Chaname, Andrew Gould

We propose a simple test for the existence of a cluster of black hole remnants around Sgr A* that is based on a small sample of any type of Galactic Center objects, provided they are substantially less massive than the black holes and constitute part of an old (> 1 Gyr) population. The test relies on the fact that, under the presence of such a cluster of hea

Igor Batalin, Simon Lyakhovich, Robert Marnelius

We propose a new BRST-like quantization procedure which is applicable to dynamical systems containing both first and second class constraints. It requires no explicit separation into first and second class constraints and therefore no conversion of second class constraints is needed. The basic ingredient is instead an invariant projection operator which proj

A. D. Dolgov

After brief personal recollections of the author&#39;s long-time friendship with Misha Marinov the problem of particle production by classical time- varying scalar field is discussed. In the quasiclassical limit the calculations are done by imaginary time method developed, in particular, in Marinov&#39;s works. The method permits to obtain simple analytical

D. Yu, Y. -X. Gui, X. Ye

Within the framework of thermo-field-dynamics (TFD), the information-entropies associated with the measurements of position and momentum for one-dimensional Rindler oscillator are derived, and the connection between its information-entropy and thermal fluctuation is obtained. A conclusion is drawn that the thermal fluctuation leads to the loss of information

P. Schneider, L. van Waerbeke, Y. Mellier

Weak gravitational lensing by the large scale structure can be used to probe the dark matter distribution in the Universe directly and thus to probe cosmological models. The recent detection of cosmic shear by several groups has demonstrated the feasibility of this new mode of observational cosmology. In the currently most extensive analysis of cosmic shear,

Boris Mergell, Mohammad R. Ejtehadi, Ralf Everaers

We use computer simulations and scaling arguments to investigate statistical and structural properties of a semiflexible ribbon composed of isosceles triangles. We study two different models, one where the bending energy is calculated from the angles between the normal vectors of adjacent triangles, the second where the edges are viewed as semiflexible polym

Kay Hamacher, Claudius Gros, Wolfgang Wenzel

Using the next-nearest neighbor (zig-zag) Hubbard chain as an one dimemensional model, we investigate the influence of interactions on the position of the Fermi wavevectors with the density-matrix renormalization-group technique (DMRG). For suitable choices of the hopping parameters we observe that electron-electron correlations induce very different renorma

Youichi Yamada

Renormalization of two-loop divergent corrections to the vacuum expectation values (v_1, v_2) of the two Higgs doublets in the minimal supersymmetric standard model, and their ratio tan beta=v_2/v_1, is discussed for general R_xi gauge fixings. When the renormalized (v_1, v_2) are defined to give the minimum of the loop-corrected effective potential, it is s

Isao Kishimoto, Kazuki Ohmori

We concretely define the identity string field as a surface state and deal with it consistently in terms of conformal field theory language, never using its formal properties nor oscillator representation of it. The generalized gluing and resmoothing theorem provides us with a powerful computational tool which fits into our framework. Among others, we can pr

Ryushi Goto

We shall obtain unobstructed deformations of four geometric structures: Calabi-Yau, HyperKähler, $\G$ and Spin(7) structures in terms of closed differential forms (calibrations). We develop a direct and unified construction of smooth moduli spaces of these four geometric structures and show that the local Torelli type theorem holds in a systematic way.

Alexei G. Kritsuk, Michael L. Norman

We study the dynamics of phase transitions in the interstellar medium by means of three-dimensional hydrodynamic numerical simulations. We use a realistic cooling function and generic nonequilibrium initial conditions to follow the formation history of a multiphase medium in detail in the absence of gravity. We outline a number of qualitatively distinct stag

M. Sako, S. M. Kahn, G. Branduardi-Raymont, J. S. Kaastra

XMM-Newton RGS spectra of MCG-6-30-15 and Mrk 766 exhibit complex discrete structure, which was interpreted in a paper by Branduardi-Raymont et al. (2001) as evidence for the existence of relativistically broadened Lyman alpha emission from carbon, nitrogen, and oxygen, produced in the inner-most regions of an accretion disk around a Kerr black hole. This su

Luis G. Cabral-Rosetti, Tonatiuh Matos, Dario Nuñez, Roberto A. Sussman

We consider simple hydrodynamical models of galactic dark matter in which the galactic halo is a self-gravitating and self-interacting gas that dominates the dynamics of the galaxy. Modeling this halo as a sphericaly symmetric and static perfect fluid satisfying the field equations of General Relativity, visible barionic matter can be treated as ``test parti

Shelly L Harvey

The question was raised as to whether the cut number of a 3-manifold X is bounded from below by 1/3 beta_1(X). We show that the answer to this question is `no.&#39; For each m>0, we construct explicit examples of closed 3-manifolds X with beta_1(X)=m and cut number 1. That is, pi_1(X) cannot map onto any non-abelian free group. Moreover, we show that these e

Robin Cote, V. Kharchenko, M. D. Lukin

We study the possible formation of large (mesoscopic) molecular ions in an ultracold degenerate bosonic gas doped with charged particles (ions). We show that the polarization potentials produced by the ionic impurities are capable of capturing hundreds of atoms into loosely bound states. We describe the spontaneous formation of these hollow molecular ions vi

Olga V. Man&#39;ko, Vladimir I. Man&#39;ko, Giuseppe Marmo

Tomograms introduced for the description of quantum states in terms of probability distributions are shown to be related to a standard star-product quantization with appropriate kernels. Examples of symplectic tomograms and spin tomograms are presented.

Marko Krco, Prabasaj Paul

We present a multi-party quantum clock synchronization protocol that utilizes shared prior entanglement and broadcast of classical information to synchronize spatially separated clocks. Notably, it is necessary only for any one party to publish classical information. Consequently, the efficacy of the method is independent of the relative location of the part

Olga V. Man&#39;ko, V. I. Man&#39;ko, G. Marmo

Invertible maps from operators of quantum obvservables onto functions of c-number arguments and their associative products are first assessed. Different types of maps like Weyl-Wigner-Stratonovich map and s-ordered quasidistribution are discussed. The recently introduced symplectic tomography map of observables (tomograms) related to the Heisenberg-Weyl grou

Quentin Thommen, Jean Claude Garreau, Veronique Zehnle

This papers presents a formalism describing the dynamics of a quantum particle in a one-dimensional tilted time-dependent lattice. The description uses the Wannier-Stark states, which are localized in each site of the lattice and provides a simple framework leading to fully-analytical developments. Particular attention is devoted to the case of a time-depend

B. P. Mahapatra, N. Santi, N. B. Pradhan

A self-consistent, non-perturbative scheme of approximation is proposed for arbitrary interacting quantum systems by generalization of the Hartree method.The scheme consists in approximating the original interaction term $λH_I$ by a suitable &#39;potential&#39; $λV(ϕ)$ which satisfies the following two requirements: (i) the &#39;Hartree Hamiltonian&#39; $H_o

Jae-weon Lee, Eok Kyun Lee, Jaewan Kim, Soonchil Lee

We consider a quantum circuit in which shift and rotation operations on qubits are performed by swap gates and controlled swap gates. These operations can be useful for quantum computers performing elementary arithmetic operations such as multiplication and a bit-wise comparison of qubits.

Tobias Kramer, Christian Bracher, Manfred Kleber

Localized scattering phenomena may result in the formation of stationary matter waves originating from a compact region in physical space. Mathematically, such waves are advantageously expressed in terms of quantum sources that are introduced into the Schrödinger equation. The source formalism yields direct access to the scattering wave function, particle di

Thomas Kunert, Ruediger Schmidt

A generalized formalism of the so-called non-adiabatic quantum molecular dynamics is presented, which applies for atomic many-body systems in external laser fields. The theory treats the nuclear dynamics and electronic transitions simultaneously in a mixed classical-quantum approach. Exact, self-consistent equations of motion are derived from the action prin

S. V. Sukhov, K. V. Krutitsky

The boundary problem of linear classical optics about the interaction of electromagnetic radiation with a thin dielectric film has been solved under explicit consideration of its discrete structure. The main attention has been paid to the investigation of the near-zone optical response of dielectrics. The laws of reflection and refraction for discrete struct

Randall D. Peters

A Stirling engine of the type used for demonstration purposes has been outfitted with a pair of sensors that measure pressure and piston displacement when the engine is operating with a small temperature difference between the hot and cold reservoirs. Measured variables are compared against computer generated output based on a simple theory that involves non

A. S. Arychev, A. P. Potylitsyn, M. N. Strikhanov

The circularly polarized gamma-quanta with energy > 10 MeV are formed during Compton backscattering of circularly polarized laser photons on an electron beam with energy 1.26 GeV. The contribution of nonlinear processes for planned parameters of a laser flash[T. Okugi, Y. Kurihara and M. Chiba, Jpn. J. Appl. Phys. 35, p. 3677 (1996).] can be rather significa

Massimo Mella, Maria Carola Colombo, Gabriele Morosi

We present a quantum Monte Carlo study of the structure and energetics of silver doped helium clusters AgHe$_n$ for $n$ up to 100. Our simulations show the first solvation shell of the Ag atom to be composed by roughly 20 He atoms, and to possess a structured angular distribution. Moreover, the electronic $^2$P$_{1/2}\leftarrow ^2$S$_{1/2}$ and $^2$P$_{3/2}\

P. Arun, Naveen Gaur

The motion of a pendulum is described as Simple Harmonic Motion (SHM) in case the initial displacement given is small. If we relax this condition then we observe the deviation from the SHM. The equation of motion is non-linear and thus difficult to explain to under-graduate students. This manuscript tries to simplify things.