February 2003 arXiv papers — page 2

Terence Hwa, Enzo Marinari, Kim Sneppen, Lei-han Tang

We study the thermodynamic and dynamic behaviors of twist-induced denaturation bubbles in a long, stretched random sequence of DNA. The small bubbles associated with weak twist are delocalized. Above a threshold torque, the bubbles of several tens of bases or larger become preferentially localized to \AT-rich segments. In the localized regime, the bubbles ex

M. Matsukawa, M. Narita

We have undertaken a systematic study of thermal conductivity as a function of temperature and magnetic field of single crystals of the compound (La$_{1-z}$Pr$_{z}$)$_{1.2}$Sr$_{1.8}$Mn$_{2}$O$_{7}$ for $z$(Pr) =0.2,0.4. and 0.6. The lattice distortion due to Pr-substitution and anisotropic thermal conductivity in bilayer manganites are discussed on the basi

Jun-ichi Igarashi, Tatsuya Nagao

We study the resonant x-ray scattering (RXS) spectra at the Dy $L_{\rm III}$ absorption edge in the quadrupole ordering phase of DyB$_2$C$_2$. Analyzing the buckling of sheets of B and C atoms, we construct an effective model that the crystal field is acting on the $5d$ and $4f$ states with the principal axes different for different sublattices. Treating the

A. R. Denton, M. Schmidt

We consider a model mixture of hard colloidal spheres and non-adsorbing polymer chains in a theta solvent. The polymer component is modelled as a polydisperse mixture of effective spheres, mutually noninteracting but excluded from the colloids, with radii that are free to adjust to allow for colloid-induced compression. We investigate the bulk fluid demixing

A. R. Denton

Counterion distributions and effective electrostatic interactions between spherical macroions in polyelectrolyte solutions are calculated via second-order perturbation (linear response) theory. By modelling the macroions as continuous charge distributions that are permeable to counterions, analytical expressions are obtained for counterion profiles and effec

Yoshihiko Nonomura, Xiao Hu

Vortex states in high-$T_{\rm c}$ superconductors with point defects are studied by large-scale Monte Carlo simulations of the three-dimensional frustrated XY model. A critical point is observed on the first-order phase boundary between the vortex slush and vortex liquid phases. A step-like anomaly of the specific heat is detected in simulations of finite sy

Ken Wang, Zhen Ye

We study the propagation and scattering of electromagnetic waves by random arrays of dipolar cylinders in a uniform medium. A set of self-consistent equations, incorporating all orders of multiple scattering of the electromagnetic waves, is derived from first principles and then solved numerically for electromagnetic fields. For certain ranges of frequencies

M. K. Mukhopadhyay, M. K. Sanyal, M. D. Mukadam, S. M. Yusuf

Magnetic properties of materials confined to nanometer length scales are providing important information regarding low dimensional physics. Using gadolinium based Langmuir-Blodgett films, we demonstrate that two-dimensional ferromagnetic order can be induced by applying magnetic field along the in-plane (perpendicular to growth) direction. Field dependent ex

P. W. Anderson, W. F. Brinkman

In this paper we discuss some general concepts regarding the recent experiments of Mani et al and Zudov et al regarding the appearance of large resistance variations in the presence of a rf field. The possibility of negative resistance is also discussed.

Andres Santos

The homogeneous steady state of a fluid of inelastic hard spheres immersed in a bath of elastic hard spheres kept at equilibrium is analyzed by means of the first Sonine approximation to the (spatially homogeneous) Enskog--Boltzmann equation. The temperature of the granular fluid relative to the bath temperature and the kurtosis of the granular distribution

Alec Maassen van den Brink

A recent Letter [1] has proposed a device, consisting of an rf SQUID with the junction replaced by a double one, i.e. a Bloch transistor. For symmetric Josephson couplings, and for specific flux bias and gate voltage applied to the transistor's island, the tunneling of encircled flux between its two local potential minima is claimed to be suppressed comp

Igor F. Vasconcelos, Reginaldo S. de Figueiredo

We propose and develop a model as an attempt to describe the local mechanism of mechanical alloying. This model is based on the observation of global parameters, such as the volumes of the various phases present in the material, and their transformations during the process. The model is applied to milled Fe-Cu and Fe-N experimental results obtained in previo

C. Comito, P. Schilke, M. Gerin, T. G. Phillips

We report the detection, with the Caltech Submillimeter Observatory, of the 894-GHz HDO(111-000) transition, observed in absorption against the background continuum emission of the SgrB2 cores M and N. Radiative transfer modeling of this feature, together with the published data set of mm and submm HDO and H2O-18 transitions, suggests that ground-state absor

B. J. Mochejska, K. Z. Stanek, J. Kaluzny

We present the results of a long-term variability survey of the old open cluster NGC 6791. The BVI observations, collected over a time span of 6 years, were analyzed using the ISIS image subtraction package. The main target of our observations were two cataclysmic variables B7 and B8. We have identified possible cycle lenghts of about 25 and 18 days for B7 a

V. Luridiana, E. Perez, M. Cervino

We determine the physical conditions in NGC 6543, obtaining two different estimates of the electron temperature (T_e) and one estimate of the electron density (N_e). The electron temperature is computed by means of the [O III] ratio lambda 5007/lambda 4363, and of the diagnostic diagram combining lambda 5007 to the [O III] infrared lines 52m and 88m. The con

V. Luridiana, A. Peimbert, M. Peimbert

We discuss the effects of collisional enhancement of Balmer lines on the determination of the primordial helium abundance. To this aim, we present a photoionization model of the metal-poor extragalactic HII region SBS 0335--052. We show that the derived helium abundance (Y) of this HII region depends on the amount of collisional excitation affecting the Balm

Michael P. Muno, Feryal Ozel, Deepto Chakrabarty

We examine the energy-resolved pulse profiles of 51 flux oscillations observed during the decline of thermonuclear X-ray bursts from accreting weakly- magnetized neutron stars with the Rossi X-ray Timing Explorer. We find that the fractional rms amplitudes of the oscillations increase as a function of energy by 0.25%/keV to 0.9%/keV between 3-20 keV, and are

J. S. Greaves, W. S. Holland, T. Jenness, A. Chrysostomou

A polarimeter has been built for use with the Submillimetre Common-User Bolometer Array (SCUBA), on the James Clerk Maxwell Telescope (JCMT) in Hawaii. SCUBA is the first of a new generation of highly sensitive submillimetre cameras, and the UK/Japan Polarimeter adds a polarimetric imaging/photometry capability in the wavelength range 350 to 2000 microns. Ea

Dmitrijs Docenko, Karlis Berzins

We describe the spline histogram algorithm which is useful for visualization of the probability density function setting up a statistical hypothesis for a test. The spline histogram is constructed from discrete data measurements using tensioned cubic spline interpolation of the cumulative distribution function which is then differentiated and smoothed using

Guido Barbiellini, Annalisa Celotti, Francesco Longo

We note that if the GRB phenomenon follows from the collapse of a massive object forming a black hole and a torus accreting into it, the resulting ejecta can be only related to the mass and angular momentum that characterize the black hole. The opening angle of the fireball then corresponds to a black hole spin. If indeed the fireballs opening angles are as

P. Marigo, L. Girardi, C. Chiosi

Carbon stars are known to exhibit systematically redder near-infrared colours with respect to M-type stars. In the near-infrared colour-magnitude diagrams provided by the 2MASS and DENIS surveys, the LMC C-type stars draw a striking red tail, well separated from the sequences of O-rich giants. So far, this conspicuous feature has been absent from any set of

Allan Sacha Brun

Many stars exhibit strong magnetic fields, some of which are thought to be of primordial origin and others a sign of magnetic dynamo processes. We briefly review the results of observational studies of solar-type stars seeking to evaluate the linkage between rotation rate and possible magnetic cycles of activity. Clearly turbulent convection and rotation wit

Allan Sacha Brun, Matthew Browning, Juri Toomre

The advent of massively parallel supercomputing has begun to permit explicit 3--D simulations of turbulent convection occurring within the cores of early-type main sequence stars. Such studies should complement the stellar structure and evolution efforts that have so far largely employed 1--D nonlocal mixing length descriptions for the transport, mixing and

J. V. Clausen, J. Storm, S. S. Larsen, A. Gimenez

We present new accurate CCD uvby light curves for the LMC eclipsing binaries HV982 and HV12578, and for the SMC systems HV1433 and HV11284 obtained at the Danish 1.5m telescope at ESO, La Silla. The light curves were derived from DoPHOT photometry, and typical accuracies are between 0.007 and 0.012 mag per point. Standard uvby indices have also been establis

Allan Sacha Brun, Juri Toomre

We discuss recent advances made in modelling the complex magnetohydrodynamics of the Sun using our anelastic spherical harmonics (ASH) code. We have conducted extensive 3--D simulations of compressible convection in rotating spherical shells with and without magnetic fields, to study the coupling between global-scale convection and rotation in seeking to und

Dainis Dravins

Accuracies reached in space astrometry now permit the accurate determination of astrometric radial velocities, without any use of spectroscopy. Knowing this true stellar motion, spectral shifts intrinsic to stellar atmospheres can be identified, for instance gravitational redshifts and those caused by velocity fields on stellar surfaces. The astrometric accu

Dainis Dravins

For hydrodynamic model atmospheres, absolute lineshifts are becoming an observable diagnostic tool beyond the classical ones of line-strength, -width, -shape, and -asymmetry. This is the wavelength displacement of different types of spectral lines away from the positions naively expected from the Doppler shift caused by stellar radial motion. Caused mainly b

G. Trinchieri, J. Sulentic, D. Breitschwerdt, W. Pietsch

Chandra observations of the compact galaxy group known as Stephan's Quintet (SQ) are presented. The major morphological features that were discovered with the ROSAT HRI are now imaged with higher resolution and S/N. The large scale shock (1.5', ~40kpc if at 85 Mpc) is resolved into a narrow NS feature embedded in more extended diffuse emission (D>=3&

B. W. Stappers, B. M. Gaensler, V. M. Kaspi, M. van der Klis

We have detected an x-ray nebula around the binary millisecond pulsar B1957+20. A narrow tail, corresponding to the shocked pulsar wind, is seen interior to the known H-alpha bow shock and proves the long-held assumption that the rotational energy of millisecond pulsars is dissipated through relativistic winds. Unresolved x-ray emission likely represents the

Steve Warren, Simon Dye

We describe a new method for analyzing gravitational lens images, for the case where the source light distribution is pixelized. The method is suitable for high resolution, high S/N data of a multiply-imaged extended source. For a given mass distribution, we show that the step of inverting the image to obtain the deconvolved pixelized source light distributi

MACRO Collaboration

Using data collected by the MACRO experiment from 1989 to the end of its operations in 2000, we have studied in the underground muon flux the shadowing effects due to both the Moon and the Sun. We have observed the Moon shadowing effect with a significance of 6.5 sigma and the Sun shadowing effect with a significance of 4.3 sigma. The observed displacement o

A. Krawczyk, A. G. Lyne, J. A. Gil, B. C. Joshi

About 76 glitches in 25 pulsars have been reported to date. Most glitches are `giant', with fractional increases of frequency dnu_0/nu_0 ~ 10^{-6}. 25 glitches were analysed and presented by Shemar & Lyne (1996) who detected them mainly at Jodrell Bank during the monitoring of a sample of 279 pulsars in a regular timing programme up to MJD 49500. This pa

Andrew J. Willes, Kinwah Wu

By analogy to Jovian radio emissions powered by the electromagnetic interaction between Jupiter and its moons, we propose that close magnetic-nonmagnetic white-dwarf pairs and white-dwarf planetary systems are strong radio sources. A simple model is developed to predict the flux densities of radio emission generated by a loss-cone-driven electron-cyclotron m

Yutaka Fujita

The population and population composition of galaxies in galaxy clusters at present reflect the mass of the clusters and the mass growth of the galaxies in the past. We investigate them for six clusters. We show that galaxies in massive clusters stopped growing at redshifts of ~4. Moreover, we find that some small galaxy clusters (groups) have too many massi

Roeland P. van der Marel

This paper reviews the subject of intermediate-mass black holes (IMBHs) with masses between those of "stellar-mass" and "super-massive" black holes. The existence of IMBHs is a real possibility: they might plausibly have formed as remnants of the first generation of stars (Population III), as the result of dense star cluster evolution, or as

R. Brandenberger, G. Geshnizjani, S. Watson

String theory gives rise to various mechanisms to generate primordial inflation, of which ``brane inflation'' is one of the most widely considered. In this scenario, inflation takes place while two branes are approaching each other, and the modulus field representing the separation between the branes plays the role of the inflaton field. We study the

Uros Seljak, Patrick McDonald, Alexey Makarov

The WMAP team has recently highlighted the usefulness of combining the Ly-alpha forest constraints with those from the cosmic microwave background (CMB). This combination is particularly powerful as a probe of the primordial shape of the power spectrum. Converting between the Ly-alpha forest observations and the linear mass power spectrum requires a careful

D. Lust, S. Stieberger

We calculate the one-loop corrections to gauge couplings in N=1 supersymmetric brane world models, which are realized in an type IIA orbifold/orientifold background with several stacks of D6 branes wrapped on 3-cycles with non-vanishing intersections. Contributions arise from both N=1 and N=2 open string subsectors. In contrast to what is known from ordinary

Davide Fioravanti, Marco Rossi

With the aim of exploring a massive model corresponding to the perturbation of the conformal model [hep-th/0211094] the nonlinear integral equation for a quantum system consisting of left and right KdV equations coupled on the cylinder is derived from an integrable lattice field theory. The eigenvalues of the energy and of the transfer matrix (and of all the

R. Sekhar Chivukula, Duane A. Dicus, Hong-Jian He, Satyanarayan Nandi

We study the unitarity of the standard model (SM) in higher dimensions. We show that the essential features of SM unitarity remain after compactification, and place bounds on the highest Kaluza-Klein (KK) level N_KK and the Higgs mass m_H in the effective four-dimensional (4d) low-energy theory. We demonstrate these general observations by explicitly analyzi

R. G. Melko, A. W. Sandvik, D. J. Scalapino

We calculate the superfluid stiffness of 2D lattice hard-core bosons at half-filling (equivalent to the S=1/2 XY-model) using the squared winding number quantum Monte Carlo estimator. For L_x x L_y lattices with aspect ratio L_x/L_y=R, and L_x,L_y -> infinity, we confirm the recent prediction [N. Prokof'ev and B.V. Svistunov, Phys. Rev. B 61, 11282 (1999

Kasper K. S. Andersen, Jesper Grodal, Jesper M. Møller, Antonio Viruel

A p-compact group, as defined by Dwyer and Wilkerson, is a purely homotopically defined p-local analog of a compact Lie group. It has long been the hope, and later the conjecture, that these objects should have a classification similar to the classification of compact Lie groups. In this paper we finish the proof of this conjecture, for p an odd prime, provi

F. Ginelli, V. Ahlers, R. Livi, D. Mukamel

A simple one-dimensional microscopic model of the depinning transition of an interface from an attractive hard wall is introduced and investigated. Upon varying a control parameter, the critical behaviour observed along the transition line changes from a directed-percolation to a multiplicative-noise type. Numerical simulations allow for a quantitative study

Sergio L. Cacciatori, Dietmar Klemm, Wafic A. Sabra

We present new supersymmetric domain wall and string solutions of five-dimensional N = 2 gauged supergravity coupled to an arbitrary number of vector multiplets. Using the techniques of very special geometry allows to obtain the most general domain wall preserving half of the supersymmetries. This solution, which describes a renormalization group flow in the

Amit Giveon, Ari Pakman

We study superstring theories on AdS(3) x N backgrounds yielding N=2,3,4 extended superconformal symmetries in the dual boundary CFT. In each case the necessary constraints on the internal worldsheet theory N are found.

A. Levinson, D. Eichler

It is proposed that the baryons in gamma ray burst (GRB) fireballs originate as "pick-up" neutrons that leak in sideways from surrounding baryonic matter and convert to protons in a collision avalanche. The asymptotic Lorentz factor is estimated, and, in the absence of collimation, is shown to be angle dependent. Reasonable agreement is obtained with

Jack Lidmar

We introduce a model describing vortices in strongly disordered three-dimensional superconductors. The model focuses on the topological defects, i.e., dislocation lines, in an elastic description of the vortex lattice. The model is studied using Monte Carlo simulations, revealing a glass phase at low temperatures, separated by a continuous phase transition t

Jesper Dall, Paolo Sibani

We present a statistical method for complex energy landscape exploration which provides information on the metastable states--or valleys--actually explored by an unperturbed aging process following a quench. Energy fluctuations of record size are identified as the events which move the system from one valley to the next. This allows for a semi-analytical des

Karol Zyczkowski, Hans-Juergen Sommers

We compute the volume of the convex N^2-1 dimensional set M_N of density matrices of size N with respect to the Hilbert-Schmidt measure. The hyper--area of the boundary of this set is also found and its ratio to the volume provides an information about the complex structure of M_N. Similar investigations are also performed for the smaller set of all real den

J. R. Forshaw, A. Sabio Vera, B. E. White

We perform an analysis of the Renormalization Group evolution of the couplings in an extension to the Standard Model which contains a real triplet in the Higgs sector. Insisting that the model remain valid up to 1 TeV allow us to map out the region of allowed mass for the Higgs bosons. We conclude that it is possible for there to be no light Higgs bosons wit

S. Mei, J. G. Bartlett

We discuss the angular correlation function of Sunyaev-Zel'dovich (SZ)-detected galaxy clusters as a cosmological probe. As a projection of the real-space cluster correlation function, the angular function samples the underlying SZ catalog redshift distribution. It offers a way to study cosmology and cluster evolution directly with the two-dimensional ca

K. Matsuda, T. Fukuyama, H. Nishiura

We reanalyze the constraints in neutrino masses and MNS lepton mixing parameters using the new data from the terrestrial (KamLAND) and astrophysical (WMAP) observations together with the HEIDELBERG-MOSCOW double beta decay experiment. It leads us to the almost degenerate or inverse hierarchy neutrino mass scenario. We discuss the possibility of getting the b

Paulo M. Sá

Differential rotation of r-modes is investigated within the nonlinear theory up to second order in the mode amplitude in the case of a slowly-rotating, Newtonian, barotropic, perfect-fluid star. We find a nonlinear extension of the linear r-mode, which represents differential rotation that produces large scale drifts of fluid elements along stellar latitudes

Udo Hartmann, Frank K. Wilhelm

We analyze the decoherence of charge states in double quantum dots due to cotunneling. The system is treated using the Bloch-Redfield generalized master equation for the Schrieffer-Wolff transformed Hamiltonian. We show that the decoherence, characterized through a relaxation $τ_{r}$ and a dephasing time $τ_ϕ$, can be controlled through the external voltage

Tomohiro Matsuda

In conventional scenario of thermal inflation, the requirement that the reheating temperature must be larger than the temperature of the nucleosynthesis puts a lower bound on the mass of the inflaton field. At the same time, the mass of the inflaton field and the height of the potential during thermal inflation are intimately related. With these conditions,

H L. Morgan, M G. Edmunds

We investigate the sources and amount of dust in early galaxies. We discuss dust nucleation in stellar atmospheres using published extended atmosphere models, stellar evolution tracks and nucleation conditions and conclude that the (TPAGB) phase of intermediate mass stars is likely to be the most promising site for dust formation in stellar winds. The implic

B. Silvestre-Brac, F. Brau, C. Semay

Electromagnetic splittings for mesons and baryons are calculated in a formalism where the constituent quarks are considered as dressed quasiparticles. The electromagnetic interaction, which contains coulomb, contact, and hyperfine terms, is folded with the quark electrical density. Two different types of strong potentials are considered. Numerical treatment

Hui Hu, Xia-Ji Liu

By using the Hartree-Fock-Bogoliubov equations within the Popov approximation, we investigate the thermodynamic properties of a dilute binary Bose-Fermi mixture confined in an isotropic harmonic trap. For mixtures with an attractive Bose-Fermi interaction we find a sizable enhancement of the condensate fraction and of the critical temperature of Bose-Einstei

David J. Green

Let G be the Sylow 2-subgroup of the unitary group $SU_3(4)$. We find two essential classes in the mod-2 cohomology ring of G whose product is nonzero. In fact, the product is the ``last survivor'' of Benson-Carlson duality. Recent work of Pakianathan and Yalcin then implies a result about connected graphs with an action of G. Also, there exist essen

R. Fiore, L. L. Jenkovszky, A. Kotikov, F. Paccanoni

Ultra-high energy ($E_ν>10^8 $ GeV) neutrino-nucleon total cross sections $σ^{νN}$ are estimated from a soft non-perturbative model complemented by an approximate QCD evolution, explicitly calculated. The resulting asymptotic energy behavior of the neutrino-nucleon charged-current total cross section is derived analytically and predictions concerning the obs

Andrei Khrennikov

The notion of context (complex of physical conditions) is basic in this paper. We show that the main structures of quantum theory (interference of probabilities, Born's rule, complex probabilistic amplitudes, Hilbert state space, representation of observables by operators) are present in a latent form in the classical Kolmogorov probability model. Howeve

Kenji Sakamoto, Kiyoshi Shiraishi

We discuss the quantum scattering process in the moduli space consisting of two maximally charged dilaton black holes. The black hole moduli space geometry has different structures for arbitrary dimensions and various values of dilaton coupling. We study the quantum effects of the different moduli space geometries with scattering process. Then, it is found t

Guo-meng Zhao

We have identified several important features in the neutron scattering data of cuprates, which are difficult to be explained in terms of d-wave and isotropic s-wave order parameters. Alternatively, we show that the neutron data are in quantitative agreement with an order parameter that has an extended s-wave (A_1g) symmetry and opposite sign in the bonding

Minchul Lee, Mahn-Soo Choi, M. Y. Choi

In this work we study quantum phase transitions and persistent currents in capacitively coupled one-dimensional Josephson-junction arrays. We will focus particularly on the roles of exciton-like pairs in the strong coupling limit in the presence of external gate charges and magnetic fluxes. We use the numerical density-matrix renormalization group method for

Tiago C. Ribeiro, Xiao-Gang Wen

The SU(2) slave-boson mean-field theory for the tt&#39;J model is analyzed. The role of next-nearest-neighbor hopping t&#39; on the phase-diagram is studied. We find a pseudogap phase in hole-doped materials (where t&#39;<0). The pseudo-gap phase is a U(1) spin liquid (the staggered-flux phase) with a U(1) gauge interaction and no fractionalization. This agr

L. Capriotti, D. J. Scalapino, R. D. Sedgewick

A weak scattering potential imposed on a $CuO_2$ layer of a cuprate superconductor modulates the local density of states $N(x,ω)$. In recently reported experimental studies scanning-tunneling maps of $N(x,ω)$ have been Fourier transformed to obtain a wave-vector power spectrum. Here, for the case of a weak scattering potential, we discuss the structure of th

Miklos Gyulassy, Ivan Vitev, Xin-Nian Wang, Ben-Wei Zhang

We review recent finite opacity approaches (GLV, WW, WOGZ) to the computation of the induced gluon radiative energy loss and their application to the tomographic studies of the density evolution in ultra-relativistic nuclear collisions.

Kurusch Ebrahimi-Fard

In this brief note we would like to give the construction of a free commutative unital associative Nijenhuis algebra on a commutative unital associative algebra based on an augmented modified quasi-shuffle product.

A. A. Burkov, Leon Balents

We present a theory of the Anomalous Hall Effect (AHE) in ferromagnetic (Ga,Mn)As in the regime when conduction is due to phonon-assisted hopping of holes between localized states in the impurity band. We show that the microscopic origin of the anomalous Hall conductivity in this system can be attributed to a phase that a hole gains when hopping around close

Fulvio Baldovin, Edgardo Brigatti, Constantino Tsallis

We address a simple connection between results of Hamiltonian nonlinear dynamical theory and thermostatistics. Using a properly defined dynamical temperature in low-dimensional symplectic maps, we display and characterize long-standing quasi-stationary states that eventually cross over to a Boltzmann-Gibbs-like regime. As time evolves, the geometrical proper

D. Budker, J. E. Stalnaker

The authors suggest that atomic experiments measuring the interference between magnetic-dipole and electric-field-induced electric-dipole transition amplitudes provide a valuable system to study magnetoelectric Jones effects.

Daniel A. Lidar, Lian-Ao Wu

Decoherence is the main obstacle to the realization of quantum computers. Until recently it was thought that quantum error correcting codes are the only complete solution to the decoherence problem. Here we present an alternative that is based on a combination of a decoherence-free subspace encoding and the application of strong and fast pulses: ``encoded re

S. Castelletto, I. P. Degiovanni, M. L. Rastello

In this report we discuss the insecurity with present implementations of the Ekert protocol for quantum-key distribution based on the Wigner Inequality. We propose a modified version of this inequality which guarantees safe quantum-key distribution.

Chong Li, He-Shan Song, Ling Zhou, Chun-Feng Wu

We proposed a new scheme for quantum key distribution based on entanglement swapping. By this protocol \QTR{em}{Alice} can securely share a random quantum key with \QTR{em}{Bob}, without transporting any particle.

Marco Frasca

The paradigm of the two-level atom is revisited and its perturbative analysis is discussed in view of the principle of duality in perturbation theory. The models we consider are a two-level atom and an ensemble of two-level atoms both interacting with a single radiation mode. The aim is to see how the latter can be actually used as an amplifier of quantum fl

Vivek V. Shende, Aditya K. Prasad, Igor L. Markov, John P. Hayes

Reversible or information-lossless circuits have applications in digital signal processing, communication, computer graphics and cryptography. They are also a fundamental requirement in the emerging field of quantum computation. We investigate the synthesis of reversible circuits that employ a minimum number of gates and contain no redundant input-output lin

A. Schwenk, B. Friman, G. E. Brown

The application of renormalization group methods to microscopic nuclear many-body calculations is discussed. We present the solution of the renormalization group equations in the particle-hole channels for neutron matter and the application to S-wave pairing. Furthermore, we point out that the inclusion of tensor and spin-orbit forces leads to spin non-conse

M. C. M. Rentmeester, R. G. E. Timmermans, J. J. de Swart

As a first result of two new partial-wave analyses, one of the pp and another one of the np scattering data below 500 MeV, we report a study of the long-range chiral two-pion exchange interaction which contains the chiral coupling constants c1, c3, and c4. By using as input a theoretical value for c1 we are able to determine in pp as well as in np scattering

S. Mickevicius, G. P. Kamuntavicius

We present an investigation of six quarks system kinematics, independent on quark-quark interactions. There has been created and investigated basis of six quarks antisymmetrical and translationally invariant functions, applying formalism with spin, isospin, and color degrees of freedom and many-particle harmonic oscillator (HO) functions, dependent on Jacobi

W. A. Friedman, M. B. Tsang

A method is proposed for the experimental measurement of neutron separation energies for nuclei far from stability. The procedure is based on determining cross sections for the production of nuclei, by projectile fragmentation, for which only protons are removed but for which the number of neutrons is left unchanged. A simple Abrasion-Ablation analysis leads

Z. Popowicz, F. Toppan

Manifest N=2 supersymmetric Toda systems are constructed from the $sl(n,n+1)$ superalgebras by taking into account their complex structure. In the $n\to \infty$ continuum limit an N=2 extension of the $(2+1)$-dimensional heavenly equation is obtained. The integrability is guaranteed by the existence of a supersymmetric Lax pair. We further analyze the proper

Sebastian Goncalves, Marcelo Kuperman, Marcelo Ferreira da Costa Gomes

We study the relation between different social behaviors and the onset of epidemics in a model for the dynamics of sexual transmitted diseases. The model considers the society as a system of individual sexuated agents that can be organized in couples and interact with each other. The different social behaviors are incorporated assigning what we call a promis

Andrey A. Sukhorukov, Yuri S. Kivshar

We analyze nonlinear collective effects in periodic systems with multi-gap transmission spectra such as light in waveguide arrays or Bose-Einstein condensates in optical lattices. We demonstrate that the inter-band interactions in nonlinear periodic gratings can be efficiently managed by controlling their geometry, and predict novel types of discrete vector

G. Sardanashvily

Conservation laws related to the gauge invariance of Lagrangians and Euler-Lagrange operators in finite and infinite order Lagrangian formalisms are analyzed.

D. Burns, V. Guillemin

Let M be a Kaehler manifold with a free, holomorphic and Hamiltonian action of the standard n-torus T. We give a simple, explicit and canonical formula for the Kaehler potential on the Kaehler reduction of M. As a consequence we can derive improvements of several classical results known for more general Hamiltonian reductions. Among these are a forms-level p

G. I. Barenblatt, J. L. Vazquez

The theory of degenerate parabolic equations of the forms \[ u_t=(Φ(u_x))_{x} \quad {\rm and} \quad v_{t}=(Φ(v))_{xx} \] is used to analyze the process of contour enhancement in image processing, based on the evolution model of Sethian and Malladi. The problem is studied in the framework of nonlinear diffusion equations. It turns out that the standard initia

Irene M. Gamba, Vladislav Panferov, Cedric Villani

We study the Boltzmann equation for a space-homogeneous gas of inelastic hard spheres, with a diffusive term representing a random background forcing. Under the assumption that the initial datum is a nonnegative $L^2$ function, with bounded mass and kinetic energy (second moment), we prove the existence of a solution to this model, which instantaneously beco

R. M. Green

Motivated by work of Stembridge, we study rank functions for Viennot&#39;s heaps of pieces. We produce a simple and sufficient criterion for a heap to be a ranked poset and apply the results to the heaps arising from fully commutative words in Coxeter groups.

Oliver C. Schnuerer, Hartmut R. Schwetlick

We consider strictly convex hypersurfaces which are evolving by the non-parametric logarithmic Gauss curvature flow subject to a Neumann boundary condition. Solutions are shown to converge smoothly to hypersurfaces moving by translation. In particular, for bounded domains we prove that convex functions with prescribed normal derivative satisfy a uniform osci

Sebastien Desreux, Martin Matamala, Ivan Rapaport, Eric Remila

We first prove that the set of domino tilings of a fixed finite figure is a distributive lattice, even in the case when the figure has holes. We then give a geometrical interpretation of the order given by this lattice, using (not necessarily local) transformations called {\em flips}. This study allows us to formulate an exhaustive generation algorithm and a

Wolter Groenevelt

Spectral analysis of a certain doubly infinite Jacobi operator leads to orthogonality relations for confluent hypergeometric functions, which are called Laguerre functions. This doubly infinite Jacobi operator corresponds to the action of a parabolic element of the Lie algebra $\mathfrak{su}(1,1)$. The Clebsch-Gordan coefficients for the tensor product repre

Julien Bichon

We formulate and prove a free quantum analogue of the first fundamental theorems of invariant theory. More precisely, the polynomial functions algebras are replaced by free algebras, while the universal cosovereign Hopf algebras play the role of the general linear group.

G. J. Chaitin

Two philosophical applications of the concept of program-size complexity are discussed. First, we consider the light program-size complexity sheds on whether mathematics is invented or discovered, i.e., is empirical or is a priori. Second, we propose that the notion of algorithmic independence sheds light on the question of being and how the world of our exp

P. Deligne, A. B. Goncharov

We define the category of mixed Tate motives over the ring of S-integers of a number field. We define the motivic fundamental group (made unipotent) of a unirational variety over a number field. We apply this to the study of the motivic fundamental group of the projective line punctured at zero, infinity and all N-th roots of unity.

Alexandre d&#39;Aspremont

Using techniques developed in [Lasserre02], we show that some minimum cardinality problems subject to linear inequalities can be represented as finite sequences of semidefinite programs. In particular, we provide a semidefinite representation of the minimum rank problem on positive semidefinite matrices. We also use this technique to cast the problem of find

David Garber

In this note we prove a decomposition related to the affine fundamental group and the projective fundamental group of a line arrangement and a reducible curve with a line component. We give some applications to this result.

Zhiqing Yang

I give a construction of compact group action on a finite dimensional space Y, whose orbit space is infinite dimensional.

William J. Ugalde

For a pseudodifferential operator $S$ of order 0 acting on sections of a vector bundle $B$ on a compact manifold $M$ without boundary, we associate a differential form of order dimension of $M$ acting on $C^\infty(M)\times C^\infty(M)$. This differential form $Ω_{n,S}$ is given in terms of the Wodzicki 1-density $\wres([S,f][S,h])$. In the particular case of

William J. Ugalde

On a 6-dimensional, conformal, oriented, compact manifold $M$ without boundary, we compute a whole family of differential forms $Ω_6(f,h)$ of order 6, with $f,h \in C^\infty(M).$ Each of these forms will be symmetric on $f,$ and $h,$ conformally invariant, and such that $\int_M f_0 Ω_6(f_1,f_2)$ defines a Hochschild 2-cocycle over the algebra $C^\infty(M).$

M. Khalkhali, B. Rangipour

We define a noncommutative analogue of invariant de Rham cohomology. More precisely, for a triple $(A,\mathcal{H},M)$ consisting of a Hopf algebra $\mathcal{H}$, an $\mathcal{H}$-comodule algebra $A$, an $\mathcal{H}$-module $M$, and a compatible grouplike element $σ$ in $\mathcal{H}$, we define the cyclic module of invariant chains on $A$ with coefficients