June 1999 arXiv papers — page 9

P. Stovicek

We make a couple of remarks on ``Comments'' due to A. Moroz which were addressed to our recent letter "Differential cross section for Aharonov-Bohm effect with non standard boundary conditions", Europhys. Lett. 44 (1998) 403.

Gilles Brassard, Tal Mor, Barry C. Sanders

The use of quantum bits (qubits) in cryptography holds the promise of secure cryptographic quantum key distribution schemes. It is based usually on single-photon polarization states. Unfortunately, the implemented ``qubits'' in the usual weak pulse experiments are not true two-level systems, and quantum key distribution based on these imperfect qubit

Tal Mor

[Shortened abstract:] This thesis investigates the importance of quantum memory in quantum cryptography, concentrating on quantum key distribution schemes. In the hands of an eavesdropper -- a quantum memory is a powerful tool, putting in question the security of quantum cryptography; Classical privacy amplification techniques, used to prove security against

T. C. Ralph

We suggest a self-testing teleportation configuration for photon q-bits based on a Mach-Zehnder interferometer. That is, Bob can tell how well the input state has been teleported without knowing what that input state was. One could imagine building a "locked" teleporter based on this configuration. The analysis is performed for continuous variable te

Jan M. L. Martin, Kim K. Baldridge, Timothy J. Lee

From large basis set coupled cluster calculations and a minor empirical adjustment, an anharmonic force field for silane has been derived that is consistently of spectroscopic quality ($\pm 1 cm^{-1}$ on vibrational fundamentals) for all isotopomers of silane studied. Inner-shell polarization functions have an appreciable effect on computed properties and ev

A. A. Apolonsky, S. A. Babin, S. I. Kablukov, R. V. Markov

A new method is proposed to produce population inversion on transitions involving the ground state of atoms. The method is realized experimentally with sodium atoms. Lasing at the frequency corresponding to the sodium D_2 line is achieved in the presence of pump radiation resonant to the D_1 line with helium as a buffer gas.

Stefano Sello

The problem of prediction of a given time series is examined on the basis of recent nonlinear dynamics theories. Particular attention is devoted to forecast the amplitude and phase of one of the most common solar indicator activity, the international monthly smoothed sunspot number. It is well known that the solar cycle is very difficult to predict due to th

E. V. Shuryak

UU collisions can provide about 30% larger densities compared to central PbPb ones. New aspect is generation of rather deformed initial states. We show that those can be effectively used to resolve a number of outstanding issues, from corrections to hard processes, elliptic flow (the QGP push issue), and the mechanism of $J/ψ$ suppression. UU collisions are

H. S. Zong, J. Z. Gu, X. F. Zhang, Y. X. Liu

The mass spectra and binding radii of heavy quark bound states are studied on the basis of the reduced Bethe-Salpeter equation. The critical values of screening masses for $c\bar{c}$ and $b\bar{b}$ bound states at a finite temperature are obtained and compared with the previous results given by non-relativistic models.

J. Z. Gu, H. A. Weidenmueller

Using a statistical model for the normally deformed states and for their coupling to a member of the superdeformed band, we calculate the ensemble average and the fluctuations of the intensity for decay out of the superdeformed band and of the intraband decay intensity. We show that both intensities depend on two dimensionless variables: The ratio $Γ^{\downa

Fl. Stancu, L. Ya. Glozman

The previous analysis of the short-range $NN$ repulsion originating from the Goldstone boson exchange hyperfine interaction between constituent quarks is revisited. We study in which respects the repulsion depends on the radial form of the spin-spin quark-quark force. We show that while the radial form affects the structure of the 6Q wave function, the short

Dinesh Kumar Srivastava, Bikash Chandra Sinha

We reanalyze the production of single photons in S+Au collisions at CERN SPS to investigate: i) the consequences of using a much richer equation of state for hadrons than the one used in an earlier study by us; and, ii) to see if the recent estimates of photon production in quark-matter (at two loop level) by Aurenche et al. are consistent with the upper lim

Song Gao, Charles Gale, Christoph Ernst, Horst Stöcker

The modification of the width of rho mesons due to in-medium decays and collisions is evaluated. The decay width is calculated from the imaginary part of the one-loop self-energy at finite temperature. The collision width is related to the cross sections of the $ρ$ + pion and the $ρ$ + nucleon reactions. A calculation based on an effective Lagrangian shows t

P. Ara, K. R. Goodearl, K. C. O'Meara, R. Raphael

For any (unital) exchange ring $R$ whose finitely generated projective modules satisfy the separative cancellation property ($A\oplus A\cong A\oplus B\cong B\oplus B$ implies $A\cong B$), it is shown that all invertible square matrices over $R$ can be diagonalized by elementary row and column operations. Consequently, the natural homomorphism $GL_1(R) \to K_

Vadim V. Varlamov

Spinor fields on surfaces of revolution conformally immersed into 3-dimensional space are considered in the framework of the spinor representations of surfaces. It is shown that a linear problem (a 2-dimensional Dirac equation) related with a modified Veselov- Novikov hierarchy in the case of the surface of revolution reduces to a well-known Zakharov-Shabat

Nandor Simanyi

The connected configuration space of a so called cylindric billiard system is a flat torus minus finitely many spherical cylinders. The dynamical system describes the uniform motion of a point particle in this configuration space with specular reflections at the boundaries of the removed cylinders. It is proven here that under a certain geometric condition -

Eli Appleboim

In this paper we introduce two theories of finite type invariants for framed links with fixed linking matrix. We show that these thepries are related to the theory of Vassiliev invariants of framed links. We also study the corresponding spaces of ``chord diagrams''.

Vladimir Tchernov

As it is well-known, all Vassiliev invariants of degree one of a knot $K\subset R^3$ are trivial. There are nontrivial Vassiliev invariants of degree one, when the ambient space is not $R^3$. Recently, T. Fiedler introduced such invariants of a knot in an $R^1$-fibration over a surface $F$. They take values in the free $Z$-module generated by all the free ho

P. P. Kulish, A. I. Mudrov

We study quantization of a class of inhomogeneous Lie bialgebras which are crossproducts in dual sectors with Abelian invariant parts. This class forms a category stable under dualization and the double operations. The quantization turns out to be a functor commuting with them. The Hopf operations and the universal R-matrices are given in terms of generators

Nikolai Neumaier

In this paper we explicitly construct local $ν$-Euler derivations $\mathsf E_α= ν\partial_ν+ \Lie{ξ_α} + \mathsf D_α$, where the $ξ_α$ are local, conformally symplectic vector fields and the $\mathsf D_α$ are formal series of locally defined differential operators, for Fedosov star products on a symplectic manifold $(M,ω)$ by means of which we are able to co

James Propp, Richard Stanley

In this paper, we continue the study of domino-tilings of Aztec diamonds. In particular, we look at certain ways of placing ``barriers'' in the Aztec diamond, with the constraint that no domino may cross a barrier. Remarkably, the number of constrained tilings is independent of the placement of the barriers. We do not know of a combinatorial explanat

Tim R. Morris, John F. Tighe

We investigate the convergence of the derivative expansion of the exact renormalization group, by using it to compute the beta function of scalar field theory. We show that the derivative expansion of the Polchinski flow equation converges at one loop for certain fast falling smooth cutoffs. The derivative expansion of the Legendre flow equation trivially co

Osvaldo Chandia, Jorge Zanelli

We respond to the comment by Kreimer et. al. about the torsional contribution to the chiral anomaly in curved spacetimes. We discuss their claims and refute its main conclusion.

Bani Mitra Sodermark

A pedagogical presentation of integrable models with special reference to the Toda lattice hierarchy has been attempted. The example of the KdV equation has been studied in detail, beginning with the infinite conserved quantities and going on to the Lax formalism for the same. We then go on to symplectic manifolds for which we construct the Lax operator. Thi

N. D. Hari Dass

This article gives a review of the topic of regularising chiral gauge theories and is aimed at a general audience. It begins by clarifying the meaning of chirality and goes on to discussing chiral projections in field theory, parity violation and the distinction between vector and chiral field theories. It then discusses the standard model of electroweak int

E. V. Shuryak

The talk is a mini-review of the current status of the field, with emphasis on SPS heavy ion program, now and beyond 2000 (as asked by the organizers). The main question is, of course, whether we can convince ourselves and the community at large that the QGP is in fact produced at SPS. We came a long way toward the positive answer, and are definitely on stro

T. Carli, J. Gerigk, A. Ringwald, F. Schrempp

We investigate possible search strategies for QCD-instanton induced processes at HERA in the deep-inelastic scattering (DIS) regime. Our study is based on the Monte Carlo generator QCDINS for instanton-induced events and the standard generators for normal DIS events. It appears possible to isolate an instanton enriched data sample via an optimized multi-dime

I. V. Andreev

Estimation of the back-to-back pi-pi correlations arising due to evolution of the pionic field in the course of pion production process is given for central heavy nucleus collisions at moderate energies.

K. J. Eskola, K. Tuominen

Final state average transverse energy and charged particle multiplicity at the central rapidity unit of central Au-Au collisions at RHIC are studied within a framework of lowest order perturbative QCD and Bjorken's hydrodynamical picture. In particular, effects of initial minijet production and the $pdV$ work during the subsequent evolution of the QGP ar

E. Gotsman

We show that when screening corrections are included $ \frac{\partial F_{2}(x,Q^{2})}{\partial \ln Q^{2}}$ is consistent with the behaviour that one expects in pQCD. Screening corrections explain the enigma of the Caldwell plot.

Katri Huitu, Tatsuo Kobayashi

We study the gauge coupling unification with extra dimensions. We take into account corrections due to the higher dimensional operators. We show the prediction of $α_3(M_Z)$ is sensitive to such corrections, even if $c<Φ>/M=O(0.01)$. We also discuss the $b-τ$ Yukawa unification.

J. W. Moffat

A unified field theory based on the compactification of a higher D-dimensional Einstein-Yang-Mills-Higgs action is developed. The extra D-4 dimensions form a compact internal space with scale size R. An anomaly-free unified chiral model of quarks and leptons, described by SO(18) in twelve dimensions, breaks down to $SO(10)\times SO(8)\to SO(10)$ with a non-t

H. Markum, R. Pullirsch, T. Wettig

In quantum chromodynamics (QCD) at nonzero chemical potential, the eigenvalues of the Dirac operator are scattered in the complex plane. Can the fluctuation properties of the Dirac spectrum be described by universal predictions of non-Hermitian random matrix theory? We introduce an unfolding procedure for complex eigenvalues and apply it to data from lattice

P. Marronetti, G. J. Mathews, J. R. Wilson

We report on numerical results from an independent formalism to describe the quasi-equilibrium structure of nonsynchronous binary neutron stars in general relativity. This is an important independent test of controversial numerical hydrodynamic simulations which suggested that nonsynchronous neutron stars in a close binary can experience compression prior to

J. M. M. Senovilla

A purely algebraic construction of super-energy tensors for arbitrary fields is presented in any dimensions. These tensors have good mathematical and physical properties, and they can be used in any theory having as basic arena an n-dimensional manifold with a metric of Lorentzian signature. In general, the completely timelike component of these s-e tensors

Christoph Durr, Marek Chrobak

We address a discrete tomography problem that arises in the study of the atomic structure of crystal lattices. A polyatomic structure T can be defined as an integer lattice in dimension D>=2, whose points may be occupied by $c$ distinct types of atoms. To ``analyze&#39;&#39; T, we conduct ell measurements that we call_discrete X-rays_. A discrete X-ray in di

Igor E. Smolyarenko, Ned S. Wingreen

We consider the role of static disorder in the spin sector of the one- and two-channel Kondo models. The distribution functions of the disorder-induced effective energy splitting between the two levels of the Kondo impurity are derived to the lowest order in the concentration of static scatterers. It is demonstrated that the distribution functions are strong

Olexei Motrunich, Siun-Chuon Mau, David A. Huse, Daniel S. Fisher

We examine the ground state of the random quantum Ising model in a transverse field using a generalization of the Ma-Dasgupta-Hu renormalization group (RG) scheme. For spatial dimensionality d=2, we find that at strong randomness the RG flow for the quantum critical point is towards an infinite-randomness fixed point, as in one-dimension. This is consistent

Loic Vanel, Daniel Howell, D. Clark, R. P. Behringer

We report experiments on cohesionless granular piles to determine the effect of construction history on the static stress distribution. The stresses beneath the piles are monitored using a very sensitive capacitive technique. The piles are formed either by release of granular material from a relatively small output (localized source), or from a large diamete

Rafael Ramírez, Telesforo López-Ciudad

New physical insight into the correspondence between path integral concepts and the Schrödinger formulation is gained by the analysis of the effective classical potential, that is defined within the Feynman path integral formulation of statistical mechanics. This potential is related to the quasi-static response of the equilibrium system to an external force

Rafael Ramírez, Telesforo López-Ciudad

We present an analysis of the Feynman path centroid density that provides new insight into the correspondence between the path integral and the Schrödinger formulations of statistical mechanics. The path centroid density is a central concept for several approximations (centroid molecular dynamics, quantum transition state theory, and pure quantum self-consis

Bruce M. Boghosian

For a wide class of applications of the Monte Carlo method, we describe a general sampling methodology that is guaranteed to converge to a specified equilibrium distribution function. The method is distinct from that of Metropolis in that it is sometimes possible to arrange for unconditional acceptance of trial moves. It involves sampling states in a local r

J. Demsar, K. Biljakovic, D. Mihailovic

Ultrafast transient reflectivity changes caused by collective and single particle excitations in the quasi one-dimensional charge-density wave (CDW) semiconductor K0.3MoO3 are investigated with optical pump-probe spectroscopy. The temperature-dependence of non-equilibrium single particle excitations across the CDW gap and their recombination dynamics are rep

Natalie Pavlenko

Peierls-type instabilities in quarter-filled ($\bar{n}=1/2$) and half-filled ($\bar{n}=1$) quantum double-well hydrogen-bonded chain are investigated analytically in the framework of two-stage orientational-tunnelling model with additional inclusion of the interactions of protons with two different optical phonon branches. It is shown that when the energy of

Masato Koashi, Masahito Ueda

The exact eigenspectra and eigenstates of spin-1 and spin-2 vectorial Bose-Einstein condensates (BECs) are found, and their response to a weak magnetic field is studied and compared with their mean-field counterparts. Whereas mean-field theory predicts the vanishing population of the zero magnetic-quantum-number component of a spin-1 antiferromagnetic BEC, t

P. Grassberger

In [G. Baker et al., Phys. Rev. Lett. 81, 554 (1998)] a number of supposedly novel and surprising features were observed in a system composed of two periodically driven and asymmetrically coupled pendula. In particular it was claimed that `permanent synchronization ... does not occur except as a numerical artifact&#39;. It was suggested that this might be re

P. Grassberger, T. Schreiber

We argue that Gaspard and coworkers [Nature 394, 865 (1998)] do not give evidence for microscopic chaos in the sense in which they use the term. The effectively infinite number of molecules in a fluid can generate the same macroscopic disorder without any intrinsic instability. But we argue also that the notion of chaos in infinitely extended systems needs c

I. M. Abu-Shiekah, O. O. Bernal, A. A. Menovsky, H. B. Brom

Stripe fluctuations in La2NiO4.17 have been studied by 139La NMR using the field and temperature dependence of the linewidth and relaxation rates. In the formation process of the stripes the NMR line intensity is maximal below 230K, starts to diminish around 140K, disappears around 50K and recovers at 4K. These results are shown to be consistent with, but co

Aquiles Ilarraza-Lomelí, C. M. Arizmendi, A. L. Salas-Brito

We apply the Ott, Grebogy and Yorke mechanism for the control of chaos to the analytical oscillator model of a leaky tap obtaining good results. We exhibit the robustness of the control against both dynamical noise and measurement noise.A possible way of controlling experimentally a leaky tap using magnetic-field-produced variations in the viscosity of a mag

H. Alt, C. Dembowski, H. -D. Graef, R. Hofferbert

We compare the statistical properties of eigenvalue sequences for a gamma=1 Bunimovich stadium billiard. The eigenvalues have been obtained by two ways: one set results from a measurement of the eigenfrequencies of a superconducting microwave resonator (real system) and the other set is calculated numerically (ideal system). The influence of the mechanical i

A. V. Olinto, R. I. Epstein, P. Blasi

The absence of the expected GZK cutoff strongly challenges the notion that the highest-energy cosmic rays are of distant extragalactic origin. We discuss the possibility that these ultra-high-energy events originate in our Galaxy and propose that they may be due to iron nuclei accelerated from young, strongly magnetic neutron stars. Newly formed pulsars acce

J. A. Stepanian, V. H. Chavushyan, L. Carrasco, H. M. Tovmassian

The results of spectroscopic observations of 363 star-like objects from the Second Byurakan Survey (SBS) are reported. This SBS&#39;s subsample has proven to be a rich source of newly identified quasars, Seyfert type galaxies, degenerate stars and hot subdwarfs. In the subsample here studied, we identified 35 new QSOs, 142 White Dwarfs (WDs) the majority of

Cornelia C. Lang, Mark Morris, Luis Echevarria

Multi-frequency, polarimetric VLA observations of the non-thermal filaments (NTF&#39;s), G0.08+0.15, and G359.96+0.09, also known as the Northern and Southern Threads are presented at 20, 6, 3.6 and 2 cm, with high enough spatial resolution to be resolved for the first time at 6 and 3.6 cm. The 20 cm image reveals a wealth of new detail in the radio sources

A. M. Koekemoer, C. P. O&#39;Dea, C. L. Sarazin, B. R. McNamara

We present results from detailed imaging of the centrally dominant radio elliptical galaxy in the cooling flow cluster Abell 2597, using data obtained with the Wide Field and Planetary Camera 2 (WFPC2) on the Hubble Space Telescope (HST). This object is one of the archetypal &#34;blue-lobed&#34; cooling flow radio elliptical galaxies, also displaying a lumin

Mordecai-Mark Mac Low, Volker Ossenkopf

Modeling the structure of molecular clouds depends on good methods to statistically compare simulations with observations in order to constrain the models. Here we characterize a suite of hydrodynamical and magnetohydrodynamical (MHD) simulations of supersonic turbulence using an averaged wavelet transform, the Delta-variance, that has been successfully used

Jose M. Marti, Ewald Mueller

This review is concerned with a discussion of numerical methods for the solution of the equations of special relativistic hydrodynamics (SRHD). Particular emphasis is put on a comprehensive review of the application of high-resolution shock-capturing methods in SRHD. Results obtained with different numerical SRHD methods are compared, and two astrophysical a

Antonaldo Diaferio

We present a technique for estimating the mass in the outskirts of galaxy clusters where the usual assumption of dynamical equilibrium is not valid. The method assumes that clusters form through hierarchical clustering and requires only galaxy redshifts and positions on the sky. We apply the method to dissipationless cosmological N-body simulations where gal

Stefanie Komossa, Dieter Breitschwerdt, Jochen Greiner, Janek Meerschweinchen

The Narrow-line Seyfert 1 galaxy RXJ0134.3-4258 was detected during the ROSAT all-sky survey with an ultrasoft spectrum (Greiner 1996). Our later pointed observation led to the discovery of drastic spectral variability. Here, we present the first detailed analysis of the soft X-ray properties of this peculiar source.

Klaus Dolag, Matthias Bartelmann, Harald Lesch

We perform cosmological, hydrodynamic simulations of magnetic fields in galaxy clusters. The computational code combines the special-purpose hardware Grape for calculating gravitational interaction, and smooth-particle hydrodynamics for the gas component. We employ the usual MHD equations for the evolution of the magnetic field in an ideally conducting plasm

C. S. Möller, U. Fritze-v. Alvensleben, K. J. Fricke, D. Calzetti

As a tool to interpret nearby and high redshift galaxy data from optical to K-band we present our chemically consistent spectrophotometric evolutionary synthesis models. These models take into account the increasing initial metallicity of successive stellar generations using recently published metallicity dependent stellar evolutionary tracks, stellar yields

E. Pian, C. M. Urry, L. Maraschi, G. Madejski

The gamma-ray blazar 3C 279 was monitored on a nearly daily basis with IUE, ROSAT and EGRET for three weeks between December 1992 and January 1993. During this period, the blazar was at a historical minimum at all wavelengths. Here we present the UV data obtained during the above multiwavelength campaign. A maximum UV variation of ~50% is detected, while dur

S. Darbon, J. -M. Perrin, J. -P. Sivan

Empirical relationships on the properties of the Extended Red Emission (ERE) are presented. They are based on published observational data and on new results obtained on reflection nebulae illuminated by cold stars. The plot of the width versus the central wavelength of the ERE band is in agreement with laboratory properties of the materials commonly propose

Galina V. Lipunova

We consider supercritical accretion onto a compact object when the accretion rate exceeds its value derived from the Eddington limit: L_{Edd}/c^2. We use the scenario that was proposed by Shakura and Sunyaev (1973) for the supercritical regime, according to which matter flows out of the gas-disk surface under radiation pressure. An analytic solution of the a

Vipul Periwal

Physics in the vicinity of an ultraviolet stable fixed point of a quantum field theory is parametrized by a renormalization group invariant macroscopic length scale, the correlation length $ξ,$ with the quantum effective action a function of this length scale. Numerical simulations of quantum gravity suggest the existence of just such a fixed point. Since th

T. Hambye, G. O. Koehler, E. A. Paschos, P. H. Soldan

We present a new analysis of the ratio ε&#39;/εwhich measures the direct CP violation in K\toππdecays. We use the 1/N_c expansion within the framework of the effective chiral lagrangian for pseudoscalar mesons. The 1/N_c corrections to the hadronic matrix elements of all operators are calculated at leading order in the chiral expansion. Numerically, doing a

H. Kleinert, A. Chervyakov

We demonstrate the reparametrization invariance of perturbatively defined one-dimensional functional integrals up to the three-loop level for a path integral of a quantum-mechanical point particle in a box. We exhibit the origin of the failure of earlier authors to establish reparametrization invariance which led them to introduce, superfluously, a compensat

Kim Whittlesey

We construct the first known examples of nontrivial, normal, all pseudo-Anosov subgroups of mapping class groups of surfaces. Specifically, we construct such subgroups for the closed genus two surface and for the sphere with five or more punctures. Using the branched covering of the genus two surface over the sphere and results of Birman and Hilden, we prove

M. X Shao, Z. Y. Zhu

In order to get the classical analogue of quantum interaction picture in classical symplectic geometric description, the space of solutions of free equations of motion is suggested to replace the phase space in $T^{*}Q$ description or the space of motions in usual classical symplectic geometric description. The way to determine measured values of observables

David H. Bailey, David J. Broadhurst

Cohen, Lewin and Zagier found four ladders that entail the polylogarithms ${\rm Li}_n(α_1^{-k}):=\sum_{r>0}α_1^{-k r}/r^n$ at order $n=16$, with indices $k\le360$, and $α_1$ being the smallest known Salem number, i.e. the larger real root of Lehmer&#39;s celebrated polynomial $α^{10}+α^9-α^7-α^6-α^5-α^4-α^3+α+1$, with the smallest known non-trivial Mahler me

James Propp

Past efforts to classify impartial three-player combinatorial games (the theories of Li and Straffin) have made various restrictive assumptions about the rationality of one&#39;s opponents and the formation and behavior of coalitions. One may instead adopt an agnostic attitude towards such issues, and seek only to understand in what circumstances one player

O. Borisenko, V. Kushnir

The thermodynamic limit of certain exponential corrections to the weak coupling expansion of two-dimensional models is investigated. The expectation values of operators contributing to the first order coefficient of the low-temperature expansion of the free energy are calculated for the order O(e^{-β}). They are proven to diverge logarithmically with the vol

J. -F. Pascual-Sánchez

Due to the resemblance between Maxwell and the gravitomagnetic equations obtained in the weak field and slow motion limit of General Relativity, one can ask if it is possible to amplify a seed intrinsic rotation or spin motion by a gravitomagetic dynamo, in analogy with the well-known dynamo effect. Using the Galilean limits of the gravitomagnetic equations,

P. Grassberger

We present high statistics data on the distribution of shortest path lengths between two near-by points on the same cluster at the percolation threshold. Our data are based on a new and very efficient algorithm. For $d=2$ they clearly disprove a recent conjecture by M. Porto et al., Phys. Rev. {\bf E 58}, R5205 (1998). Our data also provide upper bounds on t

Niels Boye Olsen, Tage Christensen, Jeppe C. Dyre

Dielectric beta-relaxation in a pyridine-toluene solution is studied close to the glass transition. In the equilibrium liquid state the beta loss peak frequency is not Arrhenius (as in the glass) but virtually temperature-independent, while the maximum loss is strongly temperature-dependent. Both loss peak frequency and maximum loss exhibit thermal hysteresi

Marcos R. S. Tavares, Guo-Qiang Hai

We report a theoretical study on the inelastic Coulomb scattering rate of an injected electron in two coupled quantum wires in quasi-one-dimensional doped semiconductors. Two peaks appear in the scattering spectrum due to the optical and the acoustic plasmon scattering in the system. We find that the scattering rate due to the optical plasmon mode is similar

Guo-Qiang Hai, Marcos R. S. Tavares

We show that a weak non-resonant tunneling between two quantum wires leads to splitting of the acoustic plasmon mode at finite wavevector. Two gaps open up in the dipersion of the acoustic plasmon mode when its frequency is close to the frequencies of the quasiparticle excitations. In contrast to the Laudau damping of the collective excitations, these gaps a

Barak Galanti, Zeev Olami

In this paper we propose that phonons, free diffusive electrons, and diffusion in two-and three--dimensional disordered lattice problems belong to a different class of localization than bonded electrons. This is manifested by three effects that can be observed numerically. First, there are extended states even at two dimensions, whereas there are no extended

Hans J. Witt, Shude Mao

We present a new method of studying quadruple lenses in elliptical power-law potentials parameterized by $ψ(x,y) \propto (x^2+y^2/q^2)^{β/2}/β(0 \leq β< 2)$. For this potential, the moments of the four image positions weighted by signed magnifications (magnification times parity) have very simple properties. In particular, we find that the zeroth moment -- t

Miguel Preto, Scott Tremaine

Symplectic integration algorithms are well-suited for long-term integrations of Hamiltonian systems because they preserve the geometric structure of the Hamiltonian flow. However, this desirable property is generally lost when adaptive timestep control is added to a symplectic integrator. We describe an adaptive-timestep symplectic integrator that can be use

Sean Fleming, Thomas Mehen, Iain W. Stewart

The 3S1-3D1 mixing angle for nucleon-nucleon scattering, epsilon_1, is calculated to next-to-next-to-leading order in an effective field theory with perturbative pions. Without pions, the low energy theory fits the observed epsilon_1 well for momenta less than $\sim 50$ MeV. Including pions perturbatively significantly improves the agreement with data for mo

Paolo Aluffi, Carel Faber

The `linear orbit&#39; of a plane curve of degree d is its orbit in P^{d(d+3)/2} under the natural action of PGL(3). We classify curves with positive dimensional stabilizer, and we compute the degree of the closure of the linear orbits of curves supported on unions of lines. Together with the results of math.AG/9805020, this encompasses the enumerative geome

K. Matsuda, H. Nishiura, T. Fukuyama

The phenomenological model that all quark and lepton mass matrices have the same zero texture, namely their (1,1), (1,3) and (3,1) components are zeros, is discussed in the context of SO(10) Grand Unified Theories (GUTs). The mass matrices of type I for quarks are consistent with the experimental data in the quark sector. For the lepton sector, consistent fi

W. Mueck, K. S. Viswanathan

We expand on Klebanov and Witten&#39;s recent proposal for formulating the AdS/CFT correspondence using irregular boundary conditions. The proposal is shown to be correct to any order in perturbation theory.

H. Garcia-Compean, O. Obregon, C. Ramirez, M. Sabido

We study 2+1 Chern-Simons gravity at the classical action level. In particular we rederive the linear combinations of the ``standard&#39;&#39; and ``exotic&#39;&#39; Einstein actions, from the (anti) self-duality of the ``internal&#39;&#39; Lorentzian indices. The relation to a genuine four-dimensional (anti)self-dual topological theory greatly facilitates t

Rolando Alvarado, Maximo Aguero

In this paper we prove an algebraic criterion which characterizes singular quasi-bi-hamiltonian structures constructed on the lines of a general, simple, new formal procedure proposed by the authors. This procedure shows that for the definition of a quasi-bi-hamiltonian system the requirement of non-singular Poisson tensors, contained in the original definit

Ralph Greenberg, Vinayak Vatsal

Let p be an odd prime. Suppose that E is a modular elliptic curve/Q with good ordinary reduction at p. Let Q_{oo} denote the cyclotomic Z_p-extension of Q. It is conjectured that Sel_E(Q_{oo}) is a cotorsion Lambda-module and that its characteristic ideal is related to the p-adic L-function associated to E. Under certain hypotheses we prove that the validity

Curtis G. Callan, Alberto Guijosa

We study some dynamical aspects of the correspondence between strings in AdS space and external heavy quarks in N=4 SYM. Specifically, by examining waves propagating on such strings, we make some plausible (and some surprising) inferences about the time-dependent fields produced by oscillating quarks in the strongly-coupled gauge theory. We point out a puzzl

Juan P. Garrahan, Martin Schvellinger, Norberto N. Scoccola

We study non-adiabatic corrections to multibaryon systems within the bound state approach to the SU(3) Skyrme model. We use approximate ansatze for the static background fields based on rational maps which have the same symmetries of the exact solutions. To determine the explicit form of the collective Hamiltonians and wave functions we only make use of thes

Michael Hapke

A short overview of the QCD program at LEP~2 is given. Studies of final state interactions in e+e- -> WW -> qqqq decays are discussed.

Andreas Warburton

We report on studies of three types of B-meson decay that can contribute to an understanding of fundamental intergenerational quark mixing, charge-conjugation--parity violation, and long-distance quantum chromodynamics. Specifically, we discuss a selection of analyses related to the Cabibbo-Kobayashi-Maskawa (CKM) parameters Vcb, Vub, alpha, and gamma, and t

L. C. Garcia de Andrade

Four classes of exact solutions of Einstein-Cartan dilatonic inflationary de Sitter cosmology are given.The first is obtained from the equation of state of massless dilaton instead of an unpolarized fermion fluid used previously by Gasperini.Repulsive gravity is found in the case where dilatons are constraint by the presence of spin-torsion effects.The secon

Stephen Fahy, Claudia Filippi

A quantum Monte Carlo method of determining Jastrow-Slater wave functions for which the energy is stationary with respect to variations in the single-particle orbitals is presented. A potential is determined by a least-squares fitting of fluctuations in the energy with a linear combination of one-body operators. This potential is used in a self-consistent sc

Akira Oguri

Transport through a Hubbard chain of size N (=1,2,3,...) connected to reservoirs is studied at T = 0 in an electron-hole symmetric case based on the second-order perturbation theory in U. The result shows a typical even-odd property corresponding to a Kondo or Mott-Hubbard physics. In this report, specifically, we study the dependence of the conductance on t

Bang-Gui Liu, Jing Wu, E. G. Wang, Zhenyu Zhang

The effects of a surfactant on two-dimensional pattern formation in epitaxial growth are explored theoretically using a simple model, in which an adatom becomes immobile only after overcoming a large energy barrier as it exchanges positions with a surfactant atom, and subsequent growth from such a seed is further shielded. Within this model, a fractal-to-com

R. Mélin, O. Bourgeois

We consider Andreev reflection in ferromagnet-superconductor junctions and extend the treatment by de Jong and Beenakker to incorporate the effect of a repulsive potential at the interface. We show the existence of a spin accumulation at a finite voltage in this model.

K. K. Dyer, S. P. Reynolds

Radio-bright, presumably young supernova remnants offer the opportunity of studying strong-shock physics and the nature of the interaction of ejected material with the surrounding medium. We use VLA and ROSAT images of the radio-bright supernova remnant 3C 397 (G41.1--0.3) to examine the shock structure in both thermal X-ray emission and nonthermal radio emi

Robert Myers

This paper gives an algebraic conjecture which is shown to be equivalent to Thurston&#39;s Geometrization Conjecture for closed, orientable 3-manifolds. It generalizes the Stallings-Jaco theorem which established a similar result for the Poincare Conjecture. The paper also gives two other algebraic conjectures; one is equivalent to the finite fundamental gro

L. Wilets, B. G. Giraud, M. J. Watrous, J. J. Rehr

The fusion enhancement factor due to screening in the solar plasma is calculated. We use the finite temperature Green&#39;s function method and a self consistent mean field approximation. We reduce this to one center problems, because in the collision of two fusing ions, the turning point where tunneling may occur lies far inside the screening radius. The nu

Hong Liu, A. A. Tseytlin

We address the question of AdS/CFT correspondence in the case of the 3-point function <O_4 O_4 O_8>. O_4 and O_8 are particular primary states represented by F^2 + ... and F^4 + ... operators in \N=4 SYM theory and dilaton ϕand massive `fixed&#39; scalar νin D=5 supergravity. While the value of <O_4 O_4 O_8> computed in large N weakly coupled SYM theory is n

Bernard Haisch, Alfonso Rueda

It has been proposed that the scattering of electromagnetic zero-point radiation by accelerating objects results in a reaction force that may account, at least in part, for inertia [1,2,3]. This arises because of asymmetries in the electromagnetic zero-point field (ZPF) or electromagnetic quantum vacuum as perceived from an accelerating reference frame. In s