August 2003 arXiv papers — page 17

L. S. Lucena, J. E. Freitas, G. Corso, R. F. Soares

Recently a multifractal object, $Q_{mf}$, was proposed to study percolation properties in a multifractal support. The area and the number of neighbors of the blocks of $Q_{mf}$ show a non-trivial behavior. The value of the probability of occupation at the percolation threshold, $p_{c}$, is a function of $ρ$, a parameter of $Q_{mf}$ which is related to its an

S. Yunoki, S. Sorella

Using a recently developed variational quantum Monte Carlo method, magnetic properties of high-$T_{\rm C}$ superconductors are studied at zero temperature ($T$), by numerical simulations on the 2D t-J model. Our focus here is to explore the difference in the properties of $p$-type and $n$-type cuprates as a function of the carrier concentrations close to hal

Dmitri Krioukov, Kevin Fall, Xiaowei Yang

The Thorup-Zwick (TZ) routing scheme is the first generic stretch-3 routing scheme delivering a nearly optimal local memory upper bound. Using both direct analysis and simulation, we calculate the stretch distribution of this routing scheme on random graphs with power-law node degree distributions, $P_k \sim k^{-γ}$. We find that the average stretch is very

Martin Gmitra, Denis Horvath

The remagnetization dynamics of monolayer dot array superlattice XY 2-D spin model with dipole-dipole interactions is simulated. Within the proposed model of array, the square dots are described by the spatially modulated exchange-couplings. The dipole-dipole interactions are approximated by the hierarchical sums and spin dynamics is considered in regime of

D. L. Huber

We investigate spin diffusion in geometrically frustrated Heisenberg antiferromagnets. It is found that the diffusion constant gradually increases from its high temperature limit as the temperature approaches the peak temperature of the susceptibility. Below the peak, the exponential decrease in the susceptibility leads to a rapid increase in the rate of spi

T. Hanney, M. R. Evans

We study condensation transitions in the steady state of a zero-range process with two species of particles. The steady state is exactly soluble -- it is given by a factorised form provided the dynamics satisfy certain constraints -- and we exploit this to derive the phase diagram for a quite general choice of dynamics. This phase diagram contains a variety

N. R. Cooper

We study the groundstates of rotating Bose gases when interactions are affected by a nearby Feshbach resonance. We show that exact groundstates at high angular momentum can be found analytically for a general and realistic model for the resonant interactions. We identify parameter regimes where the exact groundstates are exotic fractional quantum Hall states

Roger G. Melko, Matthew Enjalran, Byron C. den Hertog, Michel. J. P. Gingras

We present a detailed theoretical overview of the thermodynamic properties of the dipolar spin ice model, which has been shown to be an excellent quantitative descriptor of the Ising pyrochlore materials Dy_2Ti_2O_7 and Ho_2Ti_2O_7. We show that the dipolar spin ice model can reproduce an effective quasi macroscopically degenerate ground state and spin-ice b

H. Schmaljohann, M. Erhard, J. Kronjäger, M. Kottke

We experimentally investigate and analyze the rich dynamics in F=2 spinor Bose-Einstein condensates of Rb87. An interplay between mean-field driven spin dynamics and hyperfine-changing losses in addition to interactions with the thermal component is observed. In particular we measure conversion rates in the range of 10^-12 cm^3/s for spin changing collisions

Lorenz Bartosch

We describe a formally exact method to calculate the optical conductivity of a one-dimensional system with fluctuating order. For classical phase fluctuations we explicitly determine the optical conductivity by solving two coupled Fokker-Planck equations numerically. Our results differ considerably from perturbation theory and in contrast to Gaussian order p

Itsuko S. Suzuki, Masatsugu Suzuki

Static and dynamic behavior of short-range Ising-spin glass Cu$_{0.5}$Co$_{0.5}$Cl$_{2}$-FeCl$_{3}$ graphite bi-intercalation compounds (GBIC) has been studied with SQUID DC and AC magnetic susceptibility. The $T$ dependence of the zero-field relaxation time $τ$ above a spin-freezing temperature $T_{g}$ (= 3.92 $\pm$ 0.11 K) is well described by critical slo

H. B. Nie, S. Y. Xu, C. K. Ong, Q. Zhan

We have fabricated Fe(N) thin films with varied N2 partial pressure and studied the microstructure, morphology, magnetic properties and resistivity by using X-ray diffraction, atomic force microscopy, transmission electron microscopy, vibrating-sample magnetometer and angle-resolved M-H hysteresis Loop tracer and standard four-point probe method. In the pres

G. Caimi, L. Degiorgi, N. N. Kovaleva, P. Lemmens

We report results on the electrodynamic response of $TiOCl$, a low-dimensional spin-1/2 quantum magnet that shows a spin gap formation for T$<T_{c1}$= 67 $K$. The Fano-like shape of a few selected infrared active phonons suggests an interaction between lattice vibrations and a continuum of low frequency (spin) excitations. The temperature dependence of the p

G. Banach, W. M. Temmerman

Self-interaction corrected local spin density approximation calculations were performed for La$_{(1-x)}$Sr$_x$MnO$_3$ (LSMO) ($0.0<x<0.5$). The influence and inter-relationship of Sr doping, magnetic structure, O displacements and phase segregation on the Mn charge state were studied. A half-metallic state was obtained for LSMO with manganese configuration M

Andrea Marini, Rodolfo Del Sole

The dynamics of an electron--hole pair induced by the time--dependent screened Coulomb interaction is discussed. In contrast to the case where the static electron--hole interaction is considered we demonstrate the occurrence of important dynamical excitonic effects in the solution of the Bethe--Salpeter equation.This is illustrated in the calculated absorpti

Andreas Wensauer, Ulrich Rössler

We present a new approach how to calculate the scalar exchange-correlation potentials and the vector exchange-correlation potentials from current-carrying ground states of two-dimensional quantum dots. From these exchange-correlation potentials we derive exchange-correlation energy densities and examine their vorticity (or current) dependence. Compared with

E. L. Garwin, Mario Rabinowitz

Resistivity measurements have been made on Nb cavities, as well as on Pb and Cu, at 296, 77, and 4.2 K by means of a contactless induced-current method. For superconductors, a constant magnetic field drives the material normal below the transition temperature. These measurements provide a simple means for initial material evaluation as well as a direct means

S. X. Dou, V. Braccini, S. Soltanian, R. Klie

The effect of nanoscale-SiC doping of MgB2 was investigated using transport and magnetic measurements. It was found that there is a clear correlation between the critical temperature Tc, the resistivity r, the residual resistivity ratio, RRR = R(300K)/R(40K), the irreversibility field H* and the alloying state in the samples. SiC-doping introduced many nano-

Hisatoshi Yokoyama, Yukio Tanaka, Masao Ogata, Hiroki Tsuchiura

Superconductivity in the Hubbard model on a square lattice near half filling is studied using an optimization (or correlated) variational Monte Carlo method. Second-order processes of the strong-coupling expansion are considered in the wave functions beyond the Gutzwiller factor. Superconductivity of d_x^2-y^2-wave is widely stable, and exhibits a crossover

M. Fellhauer, D. N. C. Lin, M. Bolte, S. J. Aarseth

In Galactic open clusters, there is an apparent paucity of white dwarfs compared to the number expected assuming a reasonable initial mass function and that main-sequence stars with initial mass <= 8 M_sun become white dwarfs. We suggest that this lack of white dwarfs is due at least in part to dynamical processes. Non-spherically symmetric mass loss during

B. R. Johnson, M. E. Abroe, P. Ade, J. Bock

We discuss MAXIPOL, a bolometric balloon-borne experiment designed to measure the E-mode polarization anisotropy of the cosmic microwave background radiation (CMB) on angular scales of 10 arcmin to 2 degrees. MAXIPOL is the first CMB experiment to collect data with a polarimeter that utilizes a rotating half-wave plate and fixed wire-grid polarizer. We prese

Letizia Stanghellini, Eva Villaver, Richard A. Shaw, Max Mutchler

We present Space Telescope Imaging Spectrograph (STIS) broad band imagery and optical slitless spectroscopy of three young star clusters in the Small Magellanic Cloud (SMC). MA 1796 and MG 2 were previously known as Planetary Nebulae, and observed as such within our Hubble Space Telescope (HST) survey. With the HST spatial resolution, we show that they are i

Ian M. Hoffman, W. M. Goss, Patrick Palmer, A. M. S. Richards

The 6 cm formaldehyde (H2CO) maser sources in the compact HII regions NGC 7538-IRS1 and G29.96-0.02 have been imaged at high resolution (beams < 50 mas). Using the VLBA and MERLIN, we find the angular sizes of the NGC 7538 masers to be ~10 mas (30 AU) corresponding to brightness temperatures ~10^8 K. The angular sizes of the G29.96-0.02 masers are ~20 mas (1

E. O&#39;Sullivan, J. M. Vrtilek, A. M. Read, L. P. David

We present an X-ray study of the galaxy group or poor cluster MKW 4. Working with XMM data we examine the distribution and properties of the hot gas which makes up the group halo. The inner halo shows some signs of structure, with circular or elliptical beta models providing a poor fit to the surface brightness profile. This may be evidence of large scale mo

Y. X. Feng, A. F. Tennant, S. N. Zhang

Cyg X-1 was observed in the high state at the conjunction orbital phase (0) with HETG/Chandra. Strong and asymmetric absorption lines of highly ionized species were detected, such as Fe XXV, Fe XXIV, Fe XXIII, Si XIV, S XVI, Ne X, and etc. In the high state the profile of the absorption lines are composed of an extended red wing and a less extended blue wing

M. C. Wyatt

This paper describes a model which can explain the observed clumpy structures of debris disks. Clumps arise because after a planetary system forms its planets migrate due to angular momentum exchange with the remaining planetesimals. Outward migration of the outermost planet traps planetesimals outside its orbit into its resonances and resonant forces cause

B. T. Draine

Scattering and absorption of X-rays by interstellar dust is calculated for a model consisting of carbonaceous grains and amorphous silicate grains. The calculations employ realistic dielectric functions with structure near X-ray absorption edges, with resulting features in absorption, scattering, and extinction. Differential scattering cross sections are cal

P. Englmaier, O. E. Gerhard, N. Bissantz

We present new gas flow models for the Milky Way inside the solar circle. Using a mass model derived from the COBE/DIRBE maps and clump giant star counts, and using a parametric model for the spiral arm pattern in the disk, we calculate the gas flow and compare with 12CO observations. We find that models with 4 spiral arms fit the observations better then 2-

R. Cornils, S. Gillessen, I. Jung., W. Hofmann

Mirror facets of the H.E.S.S. imaging atmospheric Cherenkov telescopes are aligned using stars imaged onto the closed lid of the PMT camera, viewed by a CCD camera. The alignment procedure works reliably and includes the automatic analysis of CCD images and control of the facet alignment actuators. On-axis, 80% of the reflected light is contained in a circle

K. Bernloehr, O. Carrol, R. Cornils, S. Elfahem

H.E.S.S. -- the High Energy Stereoscopic System -- is a new system of large imaging atmospheric Cherenkov telescopes, with about 100 m^2 mirror area for each of four telescopes, and photomultiplier cameras with a large field of view (5 degr.) and small pixels (0.16 degr.). The dish and reflector are designed to provide good imaging properties over the full f

R. Much, P. Barr, L. Hansson, E. Kuulkers

The INTEGRAL ground segment is divided into operational and scientific components. The operational component consists of the Mission Operations Centre, the ground stations and communications lines while the scientific component comprises of a Science Operations Centre and Science Data Centre. The overall architecture of the ground segment is described paying

Kenji Bekki

We numerically investigate dynamical and chemical properties of star clusters (open and globular clusters, and ``super star clusters&#39;&#39;, SSC) formed in interacting/merging galaxies. The investigation is two-fold: (1) large-scale (100pc-100kpc) SPH simulations on density and temperature evolution of gas in interacting/merging galaxies and (2) small-sca

K. Bekki, W. J. Couch, M. J. Drinkwater, Y. Shioya

A recent all-object spectroscopic survey centred on the Fornax cluster of galaxies, has discovered a population of sub-luminous and extremely compact members, called ``ultra-compact dwarf&#39;&#39; (UCD) galaxies. In order to clarify the origin of these objects, we have used self-consistent numerical simulations to study the dynamical evolution a nucleated d

Alister W. Graham, Helmut Jerjen, Rafael Guzman

We report the discovery of (stellar) spiral-like structure in Hubble Space Telescope images of two dwarf galaxies (GMP 3292 and GMP 3629) belonging to the Coma cluster. GMP 3629 is the faintest such galaxy detected in a cluster environment, and it is the first such galaxy observed in the dense Coma cluster. The large bulge and the faintness of the broad spir

Glenn Barnich, Friedemann Brandt, Maxim Grigoriev

We analyze in detail the recursive construction of the Seiberg-Witten map and give an exhaustive description of its ambiguities. The local BRST cohomology for noncommutative Yang-Mills theory is investigated in the framework of the effective commutative Yang-Mills type theory. In particular, we show how some of the conformal symmetries get obstructed by the

Laurent Bartholdi, Said N. Sidki

The group of isometries W of a regular rooted tree, and many of its subgroups with branching structure, have groups of automorphisms induced by conjugation in W. This fact has stimulated the computation of the group of automorphisms of such well-known examples as the group G studied by R. Grigorchuk, and the group H studied by N. Gupta and the second author.

Soebur Razzaque, Peter Meszaros, Eli Waxman

We calculate the TeV-PeV neutrino fluxes of gamma-ray bursts associated with supernovae, based on the observed association between GRB 030329 and supernova SN 2003dh. The neutrino spectral flux distributions can test for possible delays between the supernova and the gamma-ray burst events down to much shorter timescales than what can be resolved with photons

Matthew J. Case, Babak H. Seradjeh, Igor F. Herbut

We consider three dimensional quantum electrodynamics (cQED3) with massless relativistic fermions coupled to a compact gauge field using a combined perturbative variational approach. Coupling to matter renders the bare interaction between magnetic monopoles logarithmic at large distances, suggesting the possibility of a confinement-deconfinement transition o

Jordan L. Hovdebo, Robert C. Myers

Recently, interesting braneworld cosmologies in the Randall-Sundrum scenario have been constructed using a bulk spacetime which corresponds to a charged AdS black hole. In particular, these solutions appear to `bounce&#39;, making a smooth transition from a contracting to an expanding phase. By considering the spacetime geometry more carefully, we demonstrat

Louise Dolan, Chiara R. Nappi, Edward Witten

We make contact between the infinite-dimensional non-local symmetry of the typeIIB superstring on AdS5xS5 worldsheet theory and a non-abelian infinite-dimensional symmetry algebra for the weakly coupled superconformal gauge theory. We explain why the planar limit of the one-loop dilatation operator is the Hamiltonian of a spin chain, and show that it commute

Marijan Koštrun, Juha Javanainen

We model an atom-molecule Bose-Einstein condensate (AMBEC) using simplified set of coupled Gross-Pitaevskii equations (GPE), where we neglect the background (elastic) scattering length of the atoms. We analyze the ground state numerically and analytically, and construct its twin state through transformation $δ\rightarrow-δ, K\rightarrow-K$. We find that the

Sergiu Klainerman, Igor Rodnianski

One of the central difficulties of settling the $L^2$-bounded curvature conjecture for the Einstein -Vacuum equations is to be able to control the causal structure of spacetimes with such limited regularity. In this paper we show how to circumvent this difficulty by showing that the geometry of null hypersurfaces of Enstein-Vacuum spacetimes can be controlle

M. C. Sullivan, D. R. Strachan, T. Frederiksen, R. A. Ott

We report on the normal-superconducting phase transition in thick $\mathrm{YBa_{2}Cu_{3}O_{7-δ}}$ films in zero magnetic field. We find significant finite-size effects at low currents even in our thickest films ($d = 3200$ Å). Using data at higher currents, we can unambiguously find $T_c$ and $z$, and show $z = 2.1 \pm 0.15$, as expected for the three-dimens

Marco A. C. Kneipp

We study the Z_N flux tubes and monopole confinement in deformed N=2* super Yang-Mills theories. In order to do that we consider an N=4 super Yang-Mills theory with an arbitrary gauge group G and add some N=2, N=1 and N=0 deformation terms. We analyze some possible vacuum solutions and phases of the theory, depending on the deformation terms which are added.

Johannes Berg, Michael Lässig

Interaction networks are of central importance in post-genomic molecular biology, with increasing amounts of data becoming available by high-throughput methods. Examples are gene regulatory networks or protein interaction maps. The main challenge in the analysis of these data is to read off biological functions from the topology of the network. Topological m

C. D. Froggatt, H. B. Nielsen

We stress the importance of the circa 20 parameters in the Standard Model, which are not fixed by the model but only determined experimentally, as a window to the physics beyond the Standard Model. However, it is a tiny window in as far as these numbers contain only the information corresponding to about one line of text. Looking for a method to study these

S. Yunoki, S. Sorella

The unconventional low-lying spin excitations, recently observed in neutron scattering experiments on ${\rm Cs_2 Cu Cl_4}$, are explained with a spin liquid wave function. The dispersion relation as well as the wave vector of the incommensurate spin correlations are well reproduced within a projected BCS wave function with gapless and fractionalized spin-1/2

Naohito Nakazawa

The gauge fixing procedure for N=1 supersymmetric Yang-Mills theory (SYM) is proposed in the context of the stochastic quantization method (SQM). The stochastic gauge fixing, which was formulated by Zwanziger for Yang-Mills theory, is extended to SYM_4 in the superfield formalism by introducing a chiral and an anti-chiral superfield as the gauge fixing funct

D. McGloin, A. E. Carruthers, K. Dholakia, E. M. Wright

Counter-propagating light fields have the ability to create self-organized one-dimensional optically bound arrays of microscopic particles, where the light fields adapt to the particle locations and vice versa. We develop a theoretical model to describe this situation and show good agreement with recent experimental data (Phys. Rev. Lett. 89, 128301 (2002))

Andre Miemiec

We discuss the holographic c-function and describe an algorithm for the practical computation of the changing central charge in arbitrary RG-flows. One example is worked out in detail. The renormalisation procedure of [hep-th/0112150]necessary to obtain the central charge is reviewed.

A. Bartl, H. Fraas, O. Kittel, W. Majerotto

We study two CP sensitive triple-product asymmetries for neutralino production e+e- \to\tildeχ^0_i \tildeχ^0_j and the subsequent leptonic two-body decay \tildeχ^0_i \to \tilde l l, \tilde l \to \tildeχ^0_1 l, for ł= e,μ,τ. We calculate the asymmetries, cross sections and branching ratios in the Minimal Supersymmetric Standard Model with complex parameters μ

J. E. Avron, O. Gat, O. Kenneth, U. Sivan

Deformations can induce rotation with zero angular momentum where dissipation is a natural ``cost function&#39;&#39;. This gives rise to an optimization problem of finding the most effective rotation with zero angular momentum. For certain plastic and viscous media in two dimensions the optimal path is the orbit of a charged particle on a surface of constant

A. Geralico, G. Landolfi, G. Ruggeri, G. Soliani

We develop a theoretical frame for the study of classical and quantum gravitational waves based on the properties of a nonlinear ordinary differential equation for a function $σ(η)$ of the conformal time $η$, called the auxiliary field equation. At the classical level, $σ(η)$ can be expressed by means of two independent solutions of the &#39;&#39;master equa

X. Zheng

We have measured the neutron spin asymmetry $A_1^n$ with high precision at three kinematics in the deep inelastic region at $x=0.33$, 0.47 and 0.60, and $Q^2=2.7$, 3.5 and 4.8 (GeV/c)$^2$, respectively. Our results unambiguously show, for the first time, that $A_1^n$ crosses zero around $x=0.47$ and becomes significantly positive at $x=0.60$. Combined with t

K. S. Cheng, Ronald E. Taam

The observed spectra and X-ray luminosities of millisecond pulsars in 47 Tuc can be interpreted in the context of theoretical models based on strong, small scale multipole fields on the neutron star surface. For multipole fields that are relatively strong as compared to the large scale dipole field, the emitted X-rays are thermal and likely result from polar

Esteban Moreno, F. J. Garcia-Vidal, Daniel Erni, J. Ignacio Cirac

The recent surface plasmon entanglement experiment [E. Altewischer et al., Nature (London) 418, 304 (2002)] is theoretically analyzed. The entanglement preservation upon transmission in the non-focused case is found to provide information about the interaction of the biphoton and the metallic film. The entanglement degradation in the focused case is explaine

A. A. Grib, A. Yu. Khrennikov, K. Starkov

Examples of games between two partners with mixed strategies, calculated by the use of the probability amplitude are given. The first game is described by the quantum formalism of spin one half system for which two noncommuting observables are measured. The second game corresponds to the spin one case. Quantum logical orthocomplemented nondistributive lattic

William Adamczak, Kevin Andrew, Peter Hernberg, Christino Tamon

Continuous-time quantum walks on graphs is a generalization of continuous-time Markov chains on discrete structures. Moore and Russell proved that the continuous-time quantum walk on the $n$-cube is instantaneous exactly uniform mixing but has no average mixing property. On complete (circulant) graphs $K_{n}$, the continuous-time quantum walk is neither inst

Tomoyuki Yamakami

We shed new light on entanglement measures in multipartite quantum systems by taking a computational-complexity approach toward quantifying quantum entanglement with two familiar notions--approximability and distinguishability. Built upon the formal treatment of partial separability, we measure the complexity of an entangled quantum state by determining (i)

Siu A. Chin

Current molecular dynamic simulations of biomolecules using multiple time steps to update the slowingly changing force are hampered by an instability occuring at time step equal to half the period of the fastest vibrating mode. This has became a critical barrier preventing the long time simulation of biomolecular dynamics. Attemps to tame this instability by

Claudio Conti, Stefano Trillo

We predict that an ultra-cold Bose gas in an optical lattice can give rise to a new form of condensation, namely matter X waves. These are non-spreading 3D wave-packets which reflect the symmetry of the Laplacian with a negative effective mass along the lattice direction, and are allowed to exist in the absence of any trapping potential even in the limit of

George Chavchanidze

In the present paper the non-Noether symmetries of the Toda model, nonlinear Schodinger equation and Korteweg-de Vries equations (KdV and mKdV) are discussed. It appears that these symmetries yield the complete sets of conservation laws in involution and lead to the bi-Hamiltonian realizations of the above mentioned models.

Lev Borisov, Evgeny Mukhin

A space of polynomials V of dimension 7 is called self-dual if the divided Wronskian of any 6-subspace is in V. A self-dual space V has a natural inner product. The divided Wronskian of any isotropic 3-subspace of V is a square of a polynomial. We call V self-self-dual if the square root of the divided Wronskian of any isotropic 3-subspace is again in V. We

G. Lusztig

We continue the attempt to develop a theory of character sheaves on a not necessarily connected reductive algebraic group. In this paper we introduce and study the generalized Green functions.

John G. Ratcliffe, Steven T. Tschantz

In this paper, we classify all the orientable hyperbolic 5-manifolds that arise as a hyperbolic space form $H^5/Γ$ where $Γ$ is a torsion-free subgroup of minimal index of the congruence two subgroup $Γ^5_2$ of the group $Γ^5$ of positive units of the Lorentzian quadratic form $x_1^2+...+x_5^2-x_6^2$. We also show that $Γ^5_2$ is a reflection group with resp

Federico Camia, Charles M. Newman

We analyze a deterministic cellular automaton $σ^{\cdot} = (σ^n : n \geq 0)$ corresponding to the zero-temperature case of Domany&#39;s stochastic Ising ferromagnet on the hexagonal lattice $\mathbb H$. The state space ${\cal S}_{\mathbb H} = \{-1, +1 \}^{\mathbb H}$ consists of assignments of -1 or +1 to each site of $\mathbb H$ and the initial state $σ^0 =

Federico Camia, Charles M. Newman

Substantial progress has been made in recent years on the 2D critical percolation scaling limit and its conformal invariance properties. In particular, chordal SLE6 (the Stochastic Loewner Evolution with parameter k=6) was, in the work of Schramm and of Smirnov, identified as the scaling limit of the critical percolation ``exploration process.&#39;&#39; In t

Rene Brandenberg

This paper deals with the three types of regular polytopes which exist in all dimensions -- regular simplices, cubes and regular cross-polytopes -- and their outer and inner radii. While the inner radii of regular simplices are well studied, only a few cases are solved for the outer radii. We give a lower bound on these radii, and show that this bound is tig

Yiannis N. Petridis, Morten Skarsholm Risager

We prove that the modular symbols appropriately normalized and ordered have a Gaussian distribution for all cofinite subgroups of SL_2(R). We use spectral deformations to study the poles and the residues of Eisenstein series twisted by power of modular symbols.

Ben Cox, Vyacheslav Futorny

We construct certain boson type realizations of affine sl(n+1) that depend on a parameter r. When r=0 we get a Fock space realization of Imaginary Verma modules appearing in the work of the first author and when r=n they are the Wakimoto modules described in the work of Feigin and Frenkel.

Simon Brendle

We describe a glueing construction for a certain self-dual reduction of the Yang-Mills equations in dimension 8.

Simon Brendle

We describe a glueing construction for the Yang-Mills equations in dimension $n > 4$. Our method is based on a construction of approximate solutions, and a detailed analysis of the linearized operator near an approximate solution.

Simon Brendle

We establish a glueing theorem for the Ginzburg-Landau equations in dimension $n > 2$. To this end, we consider a nondegenerate minimal submanifold of codimension 2, and construct a one-parameter family of solutions to the Ginzburg-Landau equations such that the energy density concentrates near this submanifold. The proof is based on a construction of suitab

Craig A. Jensen

The holomorph of a free group $F_n$ is the semidirect product $F_n \rtimes Aut(F_n)$. Using the methods of Hatcher and Vogtmann, we derive stability results and calculate the mod-$p$ homology of these holomorphs for odd primes $p$ in dimensions 1 and 2, and their rational homology in dimensions 1 through 5. Calculations of the twisted (where $Aut(F_n)$ acts

Adam D. Helfer

For linear bose field theories, I show that if a classical Hamiltonian function is strictly positive, then there is a canonical transformation making the evolution orthogonal. This structure theorem is used to analyze the corresponding quantum theories. It is shown that there is an intimate connection between boundedness-below and self-adjoint implementabili

Adam D. Helfer

For linear scalar field theories, I characterize those classical Hamiltonian vector fields which have self-adjoint operators as their quantum counterparts. As an application, it is shown that for a scalar field in curved space-time (in a Hadamard representation), a self-adjoint Hamiltonian for evolution along the unit timelike normal to a Cauchy surface exis

Harry Schiff

The exact Li$\acute{e}$nard-Wiechert solutions for the point charge in arbitrary motion are shown to be null fields everywhere. These are used as a basis to introduce extended electromagnetic field equations that have null field solutions with fractional charges that combine with absolute confining potentials.

M. C. B. Abdalla, A. A. Bytsenko, M. E. X. Guimaraes

By means of an identity that equates elliptic genus partition function of a supersymmetric sigma model on the $N$-fold symmetric product $S^N X$ of $X$ ($S^N X=X^N/S_N$, $S_N$ is the symmetric group of $N$ elements) to the partition function of a second quantized string theory, we derive the asymptotic expansion of the partition function as well as the asymp

Steffen Metzger

This diploma thesis has three major objectives. Firstly, we give an elementary introduction to M-theory compactifications, which are obtained from an analysis of its low-energy effective theory, eleven-dimensional supergravity. In particular, we show how the requirement of N=1 supersymmetry in four dimensions leads to compactifications on G_2-manifolds. We a

N. MacKay, B. Short

We investigate the $g_2$-invariant bulk (1+1D, factorized) $S$-matrix constructed by Ogievetsky, using the bootstrap on the three-point coupling of the vector multiplet to constrain its CDD ambiguity. We then construct the corresponding boundary $S$-matrix, demonstrating it to be consistent with $Y(g_2,a_1\times a_1)$ symmetry.

Yun-Song Piao, E Zhou

In this paper we construct an expanding phase with phantom matter, in which the scale factor expands very slowly but the Hubble parameter increases gradually, and assume that this expanding phase could be matched to our late observational cosmology by the proper mechanism. We obtain the nearly scale-invariant spectrum of adiabatic fluctuations in this scenar

D. Aleksandrova, P. Bozhilov

We classify almost all classical string configurations, considered in the framework of the semi-classical limit of the string/gauge theory duality. Then, we describe a procedure for obtaining the conserved quantities and the exact classical string solutions in general string theory backgrounds, when the string embedding coordinates depend non-linearly on the

G. E. Brown, L. Grandchamp, C. -H. Lee, M. Rho

As the chirally restored phase ends with T coming down to T_c, a phase resembling a mixed phase is realized, during which the hadrons (which are massless at T_c in the chiral limit) get their masses back out of their kinetic energy. The gluon condensation energy is fed into the system to keep the temperature (nearly) constant. Lattice results for the gluon c

C. Weber, H. Eberl, W. Majerotto

We calculate the full electroweak one-loop corrections to the decay of the CP-odd Higgs boson A^0 into scalar fermions in the minimal supersymmetric extension of the Standard Model. For this purpose many parameters of the MSSM have to be properly renormalized in the on-shell renormalization scheme. We have also included the SUSY-QCD corrections. For the deca

Paul Langacker

The results of high precision weak neutral current (WNC), Z-pole, and high energy collider electroweak experiments have been the primary prediction and test of electroweak unification. The electroweak program is briefly reviewed from a historical perspective. Current changes, anomalies, and things to watch are summarized, and the implications for the standar

A. Bartl, H. Fraas, O. Kittel, W. Majerotto

We study two CP sensitive triple-product asymmetries for neutralino production e+e- \to \tildeχ^0_i \tildeχ^0_j and the subsequent leptonic two-body decays \tildeχ^0_i \to \tilde{l} l of one of the neutralinos and of the slepton \tilde{l} \to \tildeχ^0_1 l at an e+e--linear collider with \sqrt{s} = 500 GeV. We calculate the asymmetries in the Minimal Supersy

Niels Meyer

This study investigates the potential of the TESLA Linear Collider for measuring resonance parameters of Higgs bosons beyond the mass range studied so far. The analysis is based on the reconstruction of events from the Higgsstrahlung process e+e- -> HZ. It is shown that the total width, the mass and the event rate for Higgs production can be measured from th

S. V. Goloskokov, P. Kroll, B. Postler

Deep virtual vector meson leptoproduction at small $\xbj$ is analyzed in the framework of generalized parton distributions. It is shown that the inclusion of transverse degrees of freedom leads to reasonable agreement with the cross section data for light mesons.

Werner M. Sun

We present constraints on the CKM parameter gamma=arg(Vub*) formed within the framework of SU(3) symmetry and based on charmless hadronic B decays to K*+- pi-+ and other pseudoscalar-vector final states. For strong phases of O(10 degrees), our analysis weakly favors cos(gamma)<0. We also estimate that a determination of $γ$ with an experimental uncertainty o

Gunnar S. Bali

Recent lattice studies of hadron properties, in particular of exotic states and charmonia are reviewed. Sea quark and quark mass effects are discussed as well as decays and mixing.

C. -J. D. Lin, G. Martinelli, E. Pallante, C. T. Sachrajda

We present a study of the finite-volume two-pion matrix elements and correlation functions of the I=0 scalar operator, in full and partially quenched QCD, at one-loop order in chiral perturbation theory. In partially quenched QCD, when the sea and valence light quark masses are not equal, the lack of unitarity leads to the same inconsistencies as in quenched

M. N. Chernodub

We study gluodynamics in an external Abelian electromagnetic field within the dual superconductor approach. We show that the SU(2) gluodynamics should possess a deconfining phase transition at zero temperature at certain value of the external field. A dual superconductor model for the SU(3) gauge theory in external field predicts a rich phase structure conta

V. M. Abazov

We present the results of a search for the production of new particles decaying into two jets in pbarp collisions at sqrt{s} = 1.8 TeV, using the DZero 1992-1995 data set corresponding to 109 pb^-1. We exclude at the 95% confidence level the production of excited quarks (q*) with masses below 775 GeV/c^2, the most restictive limit to date. We also exclude st

D0 collaboration, V. M. Abazov

Using the D0 detector, we have observed events produced in pbar-p collisions that contain W or Z bosons in conjunction with very little energy deposition (``rapidity gaps&#39;&#39;) in large forward regions of the detector. The fraction of W boson events with a rapidity gap (a signature for diffraction) is 0.89\pm^{0.19}_{0.17}%, and the probability that the

M. J. Benacquista, J. DeGoes, D. Lunder

Gravitational radiation from the galactic population of white dwarf binaries is expected to produce a background signal in the LISA frequency band. At frequencies below 1 mHz, this signal is expected to be confusion-limited and has been approximated as gaussian noise. At frequencies above about 5 mHz, the signal will consist of separable individual sources.

Victor H. Cardenas, Sergio del Campo, Ramon Herrera

Scalar density cosmological perturbations, spectral indices and reheating in a chaotic inflationary universe model, in which a higher derivative term is added, are investigated. This term is supposed to play an important role in the early evolution of the Universe, specifically at times closer to the Planck era.

Dariush Heidarian, Nandini Trivedi

We find that isoelectronic disorder destroys the spectral gap in a Mott-Hubbard insulator in 2D leading, most unexpectedly, to a new metallic phase. This phase is spatially inhomogeneous with metallic behavior coexisting with antiferromagnetic long range order. Even though the Mott gap in the pure system is much larger than antiferromagnetic exchange, the sp

F. Marty Ytreberg, Susan R. McKay

An ordered hexagonal array of aggregates can form in thin ferrofluid layers when an external magnetic field is applied. Using the Helmholtz free energy for this system, we calculate the optimum spacing for these aggregates. Results show excellent agreement with experimental findings as a function of field strength and layer thickness. Our analysis yields a c

Miguel Rey, Fernando Sols

We present a scattering theory of the electromotive force and internal resistance of an electron pump. The characterization of the device performance in terms of only two parameters requires the assumption of incoherent multiple scattering within the circuit and complete thermalization among electrons moving in a given direction. The electromotive force is s

V. N. Zavaritsky, J. Vanacken, V. V. Moshchalkov, A. S. Alexandrov

Magnetoresistance (MR) of Bi-2212 single crystals with T$_{c}$ $\approx 87-92 K$ is studied in pulsed magnetic fields up to 50T along the c-axis in a wide temperature range. The negative out-of-plane and the positive in-plane MRs are measured in the normal state. Both MRs have similar magnitudes, exceeding any orbital contribution by two orders in magnitude.