arXiv papers from February 1998

Vasiliki Plerou, Ziqiang Wang

The transport properties on the two-dimensional surface of coupled multilayer heterostructures are studied in the integer quantum Hall states. We emphasize the criticality of the surface state and the phase coherent transport properties in the thermodynamic limit. A new, stable numerical algorithm for large scale conductance calculations in the transfer matr

Maximo Banados

It has been recently pointed out that black holes of constant curvature with a "chronological singularity" can be constructed in any spacetime dimension. These black holes share many common properties with the 2+1 black hole. In this contribution we give a brief summary of these new black holes and consider them as solutions of a Chern-Simons gravity theory.

Rainer Dick

A model is introduced with a massive scalar coupling to the Yang--Mills term in four--dimensional gauge theory. It is shown that the resulting potential of colour sources consists of a short range Coulomb interaction and a long range confining part. Far away from the source the scalar vanishes $\sim r^{-1}$ while the potential diverges linearly $\sim r$. Up

Ernest Ma

I review the various mechanisms for obtaining nonzero neutrino masses. I focus on the possibility of adding one light singlet neutrino to the three known doublet neutrinos nu_e, nu_mu, and nu_tau to accommodate the totality of neutrino-oscillation experiments. I review the various theoretical suggestions for this singlet. I discuss also a scenario in which t

Ernest Ma

Given the particle content of the standard model without and with a right-handed neutrino, the requirement that all anomalies cancel singles out a set of possible global symmetries which can be gauged. I review this topic and propose a new gauge symmetry B - 3L_tau in the context of the minimal standard model consisting of the usual three families of quarks

Ernest Ma

The interplay between neutrino masses and the interactions of neutrinos with matter is discussed with an eye to extending the latter to include possible new interactions. This conjecture may resolve the conundrum posed by the present experimental data on neutrino oscillations which suggest the existence of four neutrinos, whereas Z decay and Big Bang Nucleos

E. Keith, Ernest Ma

If there exists an arbitrary supersymmetric U(1) gauge factor at the TeV scale, under which the two Higgs superfields H_{1,2} of the standard model are nontrivial, and if there is also a singlet superfield S such that the H_1 H_2 S term is allowed in the superpotential, then the structure of the two-doublet Higgs sector at the electroweak scale is more gener

G. G. Emch, A Jadczyk

It is shown that the quaternionic Hilbert space formulation of quantum mechanics allows a quantization, based on a generalized system of imprimitivity, that leads to a description of the motion of a quantum particle in the field of a magnetic monopole. The corresponding Hamilton operator is linked to the theory of projective representations in the weakened f

Gernot Haager, Marc Mars

A detailed study of an inhomogeneous dust cosmology contained in a $\gamma$-law family of perfect-fluid metrics recently presented by Mars and Senovilla is performed. The metric is shown to be the most general orthogonally transitive, Abelian, $G_2$ on $S_2$ solution admitting an additional homothety such that the self-similar group $H_3$ is of Bianchi type

P. M. Hajac, S. Majid

The Dirac q-monopole connection is used to compute projector matrices of quantum Hopf line bundles for arbitrary winding number. The Chern-Connes pairing of cyclic cohomology and K-theory is computed for the winding number -1. The non-triviality of this pairing is used to conclude that the quantum principal Hopf fibration is non-cleft. Among general results,

Mark Hovey

A monoidal model category is a model category with a compatible closed monoidal structure. Such things abound in nature; simplicial sets and chain complexes of abelian groups are examples. Given a monoidal model category, one can consider monoids and modules over a given monoid. We would like to be able to study the homotopy theory of these monoids and modul

Enrico Arbarello, Maurizio Cornalba

We compute the first, second, third, and fifth rational cohomology groups of the moduli space of stable n-pointed genus g curves, for all g and n, using (mostly) algebro-geometric techniques.

G. A. Kozlov

The strongly interacting matter under extreme conditions of temperature for the conjectured deconfined phase of the quark-gluon plasma is investigated. A systematic study of the form of the thermal ratio of the disorder deviation (TRDD) is presented with the emphasis on the degree of deviation of the TRDD-function from unity. The space-time evolution of quar

L. Fu, E. Yaschenko, L. Resca, R. Resta

Within an ab-initio HF scheme, we use both Berry-phase calculations and supercell calculations in order to compute the dynamical charges for lattice dynamics and the electronic dielectric constant for KNbO_3 and BaTiO_3. Comparison with experimental data indicates that HF provides a description of the electronic properties of this material whose accuracy is

Pankaj Agrawal

We examine the potential signatures of the Higgs boson when it decays into a tau-lepton pair. We show that with the proper identification of the tau-jet, this decay mode can lead to the identification of the Higgs boson over most of the intermediate mass range (\mW $<$ \mH $<$ 2 \mW).

Thierry Dauxois, Stefano Ruffo, Alessandro Torcini

An analytical expression for the maximal Lyapunov exponent $\lambda_1$ in generalized Fermi-Pasta-Ulam oscillator chains is obtained. The derivation is based on the calculation of modulational instability growth rates for some unstable periodic orbits. The result is compared with numerical simulations and the agreement is good over a wide range of energy den

N. Kashikawa, M. Sekiguchi, M. Doi, Y. Komiyama

We carry out CCD photometry of galaxies in the 5.25 square region centered on Coma cluster down to $M_R=-16.0$, beyond the limit of conventional morphological classification. We use the angular two-point correlation function as well as radial profiles in order to characterize the luminosity segregation. We find strong luminosity segregation for our total sam

Hsiang-nan Li

We show that the Collins-Soper-Sterman resummation approach to the derivation of the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi equation is gauge invariant. The special gauge-dependent parton distribution function employed in the resummation technique is expressed as the convolution of an infrared finite function with the standard distribution function. By m

I. Joichi, Sh. Matsumoto, M. Yoshimura

Time evolution of unstable particles that occur in the expanding universe is investigated. The off-shell effect not included in the Boltzmann-like equation is important for the decay process when the temperature becomes much below the mass of unstable particle. When the off-shell effect is taken into account, the thermal abundance of unstable particles at lo

Guang-jiong Ni

What is the momentum spectrum of a particle moving in an infinite deep square well? Einstein, Pauli and Yukawa had adopted different point of view than that in usual text books. The theoretical and experimental implication of this problem is discussed.

Soo-Jong Rey, Jung-Tay Yee

We study some aspects of Maldacena's large $N$ correspondence between N=4 superconformal gauge theory on D3-brane and maximal supergravity on AdS_5xS_5 by introducing macroscopic strings as heavy (anti)-quark probes. The macroscopic strings are semi-infinite Type IIB strings ending on D3-brane world-volume. We first study deformation and fluctuation of D3-br

Eric Bergshoeff, Eduardo Eyras, Yolanda Lozano

We construct the (bosonic) effective worldvolume action of an M-theory Kaluza-Klein monopole in a background given by the bosonic sector of eleven-dimensional massive supergravity, i.e. a "massive Kaluza-Klein monopole". As a consistency check we show that the direct dimensional reduction along the isometry direction of the Taub-NUT space leads to the massiv

V. Balasubramanian, F. Larsen

A large class of extremal and near-extremal four dimensional black holes in M-theory feature near horizon geometries that contain three dimensional asymptotically anti-de Sitter spaces. Globally, these geometries are derived from AdS_3 by discrete identifications. The microstates of such black holes can be counted by exploiting the conformal symmetry induced

W. Slominski, J. Szwed

Advantages of introducing the electron structure function in electron induced processes are demonstrated. At present energies the same experiment gives more precise description of the electron than photon structure. The momentum scales entering the process are better controlled. At very high momenta probabilistic (partonic) interpretation can be preserved de

V. Kidambi, A. Widom

There have been several experiments which hint at evidence for superluminal transport of electromagnetic energy through a material slab. On the theoretical side, it has appeared evident that acausal signals are indeed possible in quantum electrodynamics. However, it is unlikely that superluminal signals can be understood on the basis of a purely classical el

Lee Lindblom

The properties of the mass-radius curves of relativistic stellar models constructed from an equation of state with a first-order phase transition are examined. It is shown that the slope of the mass-radius curve is continuous unless the discontinuity in the density at the phase transition point has a certain special value. The curve has a cusp if the discont

Siddhartha Sahi

We describe a new formula for weight multiplicities and characters of semisimple Lie algebras. Our formula expresses these weight multiplicities as sums of positive rational numbers. In fact, the formula works more generally for the Jacobi polynomials of Heckman and Opdam, which are a one parameter deformation of these characters. As a consequence we prove t

Marco Spaans, Marcella Carollo

Effective star formation rates in tabular form are computed which yield a prescription for the star formation activity in model galaxies as a function of ambient density, metallicity, and stellar feedback. The effects of supernova explosions on the thermal balance of the Interstellar Medium (ISM) and the presence of a multi-phase ISM are explicitly included.

Vladimir S. Mashkevich

We assume that an event caused by a correlation between outcomes of two causally separated measurements is, by definition, a manifestation of quantum nonlocality, or superluminal influence. An example of the Alice-Bob type is given, with the characters replaced. The relationship between quantum nonlocality and relativity theory is touched upon.

Alexander I. Bobenko, Udo J. Hertrich-Jeromin

A Clifford algebra model for M"obius geometry is presented. The notion of Ribaucour pairs of orthogonal systems in arbitrary dimensions is introduced, and the structure equations for adapted frames are derived. These equations are discretized and the geometry of the occuring discrete nets and sphere congruences is discussed in a conformal setting. This way,

A. Gammal, T. Frederico

The nuclear sigma term is calculated including the nuclear matrix element of the derivative of the NN interaction with respect to the quark mass, $m_q\frac{\partial V_{NN}}{\partial m_q}$. The NN potential is evaluated in the skyrmion-skyrmion picture within the quantized product ansatz. The contribution of the NN potential to the nuclear sigma term provides

H. Vucetich, J. E. Horvath

We study in this work the fate of strangelets injected as a contamination in the tail of a "strange matter-driven" supernova shock. A simple model for the fragmentation and braking of the strangelets when they pass through the expanding oxygen shell is presented and solved to understand the reprocessing of this component. We find that the escaping spectrum i

Norman H. Shakespeare, Howard D. Trottier

We make a comparison of two tadpole renormalization schemes in the context of the quarkonium hyperfine splittings in lattice NRQCD. Improved gauge-field and NRQCD actions are analyzed using the mean-link $u_{0,L}$ in Landau gauge, and using the fourth root of the average plaquette $u_{0,P}$. Simulations are done for $c\bar c$, $b\bar c$, and $b\bar b$ system

Shu-Yuan Chu

Experimental tests of the suggestion that the generalization of Wheeler and Feynman's time symmetric system is the dynamical basis underlying quantum mechanics are considered. In a time-symmetric system, the instantaneous correlations exhibited by two spatially separated particles in an entangled state can be established through other particles, and can reve

P. S. Custodio, J. E. Horvath

We reconsider in this work the effects of an energy absorption term in the evolution of primordial black holes (hereafter PBHs) in the several epochs of the Universe. A critical mass is introduced as a boundary between the accreting and evaporating regimes of the PBHs. We show that the growth of PBHs is negligible in the Radiation-dominated Era due to scarci

F. Yusef-Zadeh, W. D. Cotton, S. P. Reynolds

Sub-arcsecond radio continuum observations of the Galactic center region at $\lambda$6 and 2cm reveal a 0.5$^{\prime\prime}$ diameter source with a shell-like morphology. This source is linearly polarized at a level of 16% at $\lambda$6cm and has a steep nonthermal spectrum with spectral index 1.6 between $\lambda$6 and 2 cm. The distance to this source is n

Spencer R. Klein

The environment in which bremsstrahlung and pair creation occurs can strongly affect cross sections for these processes. Because ultra-relativistic electromagnetic interactions involve very small longitudinal momentum transfers, the reactions occur gradually, spread over long distances. During this time, even relatively weak factors can accumulate enough to

E. Baron, John J. Cowan, Tamara Rogers, Kris Gutierrez

Until we can more carefully assess the validity of the physical assumptions made we withdraw this paper.

V. I. Dokuchaev, Yu. N. Eroshenko, L. M. Ozernoy

A new cosmological scenario for the origin of gamma ray bursts (GRBs) is proposed. In our scenario, a highly evolved central core in the dense galactic nucleus is formed containing a subsystem of compact stellar remnants (CSRs), such as neutron stars and black holes. Those subsystems result from the dynamical evolution of dense central stellar clusters in th

A. A. van Ballegooijen, P. Nisenson, R. W. Noyes, M. G. Lofdahl

The interaction of magnetic fields and convection is investigated in the context of the coronal heating problem. We study the motions of photospheric magnetic elements using filtergrams obtained at the Swedish Vacuum Solar Telescope at La Palma. We use potential-field modeling to extrapolate the magnetic and velocity fields to larger height. We find that the

Chao Tang

The Hausdorff dimensions of the Julia sets for non-analytic maps: f(z) = z^2 + epsilon z^* and f(z) = {z^*}^2 + epsilon are calculated perturbatively for small epsilon. It is shown that Ruelle's formula for Hausdorff dimensions of analytic maps can not be generalized to non-analytic maps.

M. E. Foglio, M. S. Figueira

``Completeness'' (i.e. probability conservation) is not usually satisfied in the cumulant expansion of the Anderson lattice when a reduced state space is employed for $U\to \infty $. To understand this result, the well known ``Chain'' approximation is first calculated for finite $U$, followed by taking $U\to \infty $. Completeness is recovered by this proced

E. Marinari, C. Naitza, F. Zuliani, G. Parisi

We introduce a new parameter to investigate replica symmetry breaking transitions using finite-size scaling methods. Based on exact equalities initially derived by F. Guerra this parameter is a direct check of the self-averaging character of the spin-glass order parameter. This new parameter can be used to study models with time reversal symmetry but its gre

Beatriz Gato-Rivera

The Topological N=2 Superconformal algebra has 29 different types of singular vectors (in complete Verma modules) distinguished by the relative U(1) charge and the BRST-invariance properties of the vector and of the primary on which it is built. Whereas one of these types only exists at level zero, the remaining 28 types exist for general levels and can be c

Sergio Ferrara, Christian Fronsdal, Alberto Zaffaroni

We discuss the spectrum of states of IIB supergravity on $AdS_5\times S^5$ in a manifest $SU(2,2/4)$ invariant setting. The boundary fields are described in terms of N=4 superconformal Yang-Mills theory and the proposed correspondence between supergravity in $AdS_5$ and superconformal invariant singleton theory at the boundary is formulated in an N=4 superfi

B. Andreas

In this note we derive the net number of generations of chiral fermions in heterotic string compactifications on Calabi-Yau threefolds with certain SU(n) vector bundles, for n odd, using the parabolic approach for bundles. We compare our results with the spectral cover construction for bundles and make a comment on the net number interpretation in F-theory.

J. M. Evans, J. O. Madsen

We consider conformal non-Abelian Toda theories obtained by hamiltonian reduction from Wess-Zumino-Witten models based on general real Lie groups. We study in detail the possible choices of reality conditions which can be imposed on the WZW or Toda fields and prove correspondences with sl(2,R) embeddings into real Lie algebras and with the possible real form

Zong-Chao Yan, J. F. Babb

Polarizabilities, dispersion coefficients, and long-range atom-surface interaction potentials are calculated for the n=2 triplet and singlet states of helium using highly accurate, variationally determined, wave functions.

Jun'ichi Yokoyama

It is shown that in a number of scalar potentials with an unstable local maximum at the origin chaotic inflation is followed by new inflation if model parameters are appropriately chosen. In this model density fluctuation can have a large-amplitude peak on the comoving Hubble scale at the onset of the slow-roll new inflation and can result in formation of ap

Eric M. Rains

The most powerful technique known at present for bounding the size of quantum codes of prescribed minimum distance is the quantum linear programming bound. Unlike the classical linear programming bound, it is not immediately obvious that if the quantum linear programming constraints are satisfiable for dimension K, that the constraints can be satisfied for a

Stefan Forste

Cosmological solutions are obtained by continuation of black D-brane solutions into the region between the horizons. It is investigated whether one can find exponential expansion when probing the cosmology with D-branes. A unique configuration exhibiting exponential expansion is discussed.

Shu-Yuan Chu

Quantization of the time symmetric system of interacting strings requires that gravity, just as electromagnetism in Wheeler-Feynman's time symmetric electro- dynamics, also be an "adjunct field" instead of an independent entity. The "adjunct field" emerges, at a scale large compared to that of the strings, as a "statistic" that summarizes how the string posi

E. R. Tracy, X. Z. Tang

A general algorithm is presented for estimating the nonlinear instability threshold, $\sigma_c$, for subcritical transitions in systems where the linearized dynamics is significantly non-normal (i.e. subcritical bifurcations of {\em Takens-Bogdanov} type). The $N$-dimensional degenerate node is presented as an example. The predictions are then compared to nu

A. E. Jacobs, Tetsuro Nikuni

CsCuCl3 is a quantum triangular antiferromagnet, ferromagnetically stacked, with an incommensurate (IC) structure due to a Dzyaloshinskii-Moriya interaction. Because of the classical degeneracy caused by the frustration, fluctuations in CsCuCl3 have extraordinarily large effects, such as the phase transition in longitudinal magnetic field (normal to the plan

Rex A. Saffer, Mario Livio, Lev R. Yungelson

We describe radial velocity observations of a large sample of apparently single white dwarfs (WDs), obtained in a long-term effort to discover close, double-degenerate (DD) pairs which might comprise viable Type Ia Supernova (SN Ia) progenitors. We augment the WD sample with a previously observed sample of apparently single subdwarf B (sdB) stars, which are

Jim Bryan, Naichung Conan Leung

Let X be an Abelian surface and C a holomorphic curve in X representing a primitive homology class. The space of genus g curves in the class of C is g dimensional. We count the number of such curves that pass through g generic points and we also count the number of curves in the fixed linear system |C| passing through g-2 generic points. These two numbers, (

K. Farakos, G. Koutsoumbas, N. E. Mavromatos

We perform a lattice study, in the quenched approximation, of dynamical mass generation in a system of relativistic (Dirac) fermions, coupled to an Abelian gauge field in (2+1)-dimensions, in the presence of an external (constant) magnetic field, perpendicular to the spatial planes. It is shown that a strong magnetic field catalyzes chiral symmetry breaking,

Marco Picariello, Alessandro Strumia

We compute the next-to-leading order corrections to the gaugino masses $M_i$ in gauge-mediated models for generic values of the messenger masses M and discuss the predictions of unified messenger models. If M<100 TeV there can be up to 10% corrections to the leading order relations $M_i\propto \alpha_i$. If the messengers are heavier there are only few % cor

Ashok Das

We derive the Dirac brackets for the O(N) nonlinear sigma model in the lightfront description with and without the constraint. We bring out various subtleties that arise including the fact that anti-periodic boundary condition seems to be preferred.

Arthur G. Sergheyev

We show that the number of symmetry operators of order not higher that q of the nonstationary n-dimensional (n=1,2,3,4) Schroedinger equation (SE) with nonvanishing potentials is finite and does not exceed that of SE with zero potentials for arbitrary q=0,1,2,... . This result is applied for the determination of the general form of time dependance of the sym

Philippos Papadopoulos, Edward Seidel, Lee Wild

We construct a class of linear partial differential equations describing general perturbations of non-rotating black holes in 3D Cartesian coordinates. In contrast to the usual approach, a single equation treats all radiative $\ell -m$ modes simultaneously, allowing the study of wave perturbations of black holes with arbitrary 3D structure, as would be prese

Naihuan Jing, Yoshitaka Koyama, Kailash Misra

We give explicit constructions of quantum symplectic affine algebras at level 1 using vertex operators.

Carlos Allende Prieto, Basilio Ruiz Cobo, Ramon J. Garcia Lopez

An inversion technique has been developed to recover LTE one-dimensional model photospheres for late-type stars from very high resolution, high signal-to-noise stellar line profiles. It is successfully applied to the Sun by using a set of clean Ti I, Ca I, Cr I, and Fe I normalized line profiles with accurate transition probabilities and taking advantage of

A. W. Jones, S. Hancock, A. N. Lasenby, R. D. Davies

The complete set of data from the Tenerife 10 GHz (8 degree FWHM) twin-horn, drift scan experiment is described. These data are affected by both long-term atmospheric baseline drifts and short term noise. A new maximum entropy procedure, utilising the time invariance and spatial continuity of the astronomical signal, is used to achieve a clean separation of

Yan V. Fyodorov, Mikhail Titov, H. -J. Sommers

In the framework of a random matrix description of chaotic quantum scattering the positions of $S-$matrix poles are given by complex eigenvalues $Z_i$ of an effective non-Hermitian random-matrix Hamiltonian. We put forward a conjecture on statistics of $Z_i$ for systems with broken time-reversal invariance and verify that it allows to reproduce statistical c

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

A review is given of the various determinations of the different piNN coupling constants in analyses of the low-energy pp, np, pbarp, and pi-p scattering data. The most accurate determinations are in the energy-dependent partial-wave analyses of the NN data. The recommended value is f^2 = 0.075 . A recent determination of f^2 by the Uppsala group from backwa

Eduardo de Rafael

Contents: 1. Introduction. 2. Sum rules prior to QCD. 3. Dispersion relations. 4. Types of two point function sum rules. 5. Non-perturbative power corrections. 6. Some examples of QCD sum rules.

M. Davier, L. Girlanda, A. Hoecker, J. Stern

A combination of finite energy sum rule techniques and Chiral Perturbation Theory (ChPT) is used in order to exploit recent ALEPH data on the non-strange tau vector (V) and axial-vector (A) spectral functions with respect to an experimental determination of the ChPT quantity L_{10}. A constrained fit of R_{\tau,V-A}^(k,l) inverse moments (l<0) and positive s

C. Bruin

Wetting and drying of a rigid substrate by a Lennard-Jones fluid in molecular dynamics simulations is reported. The size of the substrate particles, being smaller than the fluid particles in former simulations, is now taken to be equal to, respectively larger than, that of the fluid particles. Recently, for the latter type of system a first order drying tran

J. Alexander

Using a data sample of $\Upsilon(2S)$ events collected with the CLEO II detector at the Cornell Electron Storage Ring, we have investigated the hadronic transitions between the $\Upsilon(2S)$ and the $\Upsilon(1S)$. The charged dipion transition $\Upsilon(2S)\to \Upsilon(1S)\pi^+\pi^-$ was studied using two different analysis techniques. Selecting events in

H. Stein, K. Morawetz, G. Röpke

Medium modification of scattering properties in interacting Bose systems are considered by solving the Bethe-Salpeter equation. An equation of state for the normal phase (generalized Beth-Uhlenbeck formula) is given using the in-medium phase shifts to include two-particle correlations. Conclusions are drawn for systems of bosonic atoms with repulsive interac

K. Stokbro, C. Thirstrup, M. Sakurai, U. Quaade

We report STM-induced desorption of H from Si(100)-H(2$\times1$) at negative sample bias. The desorption rate exhibits a power-law dependence on current and a maximum desorption rate at -7 V. The desorption is explained by vibrational heating of H due to inelastic scattering of tunneling holes with the Si-H 5$\sigma$ hole resonance. The dependence of desorpt

V. R. Eke, S. Cole, C. S. Frenk, J. P. Henry

The evolution of the galaxy cluster abundance depends sensitively on the value of the cosmological density parameter, Omega_0. Recent ASCA data are used to quantify this evolution as measured by the X-ray temperature function. A chi^2 minimisation fit to the cumulative temperature function, as well as a maximum likelihood estimate (which requires additional

K. Morawetz, V. Spička, P. Lipavský

A kinetic equation which combines the quasiparticle drift of Landau's equation with a dissipation governed by a nonlocal and noninstant scattering integral in the spirit of Snider's equation for gases is derived. Consequent balance equations for the density, momentum and energy include quasiparticle contributions and the second order quantum virial correctio

Metin Gurses

A connection is established between the soliton equations and curves moving in a three dimensional space $V_{3}$. The sign of the self-interacting terms of the soliton equations are related to the signature of $V_{3}$. It is shown that there corresponds a moving curve to each soliton equations.

K. Morawetz, V. Špička, P. Lipavský

The formation of binary correlations in plasma is studied from the quantum kinetic equation. It is shown that this formation is much faster than dissipation due to collisions. In a hot (dense) plasma the correlations are formed on the scale of inverse plasma frequency (Fermi energy). We derive analytical formulae for the time dependency of the potential ener

Jorma Louko, Donald Marolf

Several approaches to Hawking radiation on Schwarzschild spacetime rely in some way or another on the fact that the Kruskal manifold has two causally disconnected exterior regions. We investigate the Hawking(-Unruh) effect for a real scalar field on the $\RPthree$ geon: an inextendible, globally hyperbolic, space and time orientable eternal black hole spacet

K. Morawetz

The quantum kinetic equation for charged particles in strong electric fields is used to derive the nonlinear particle flux. The relaxation field is calculated quantum mechanically up to any order in the applied field provided a given Maxwellian plasma. The classical limit is given in analytical form. In the range of weak fields the deformation of the screeni

Klaus Morawetz, Václav Špička, Pavel Lipavský

The formation of binary correlations in plasma is studied from the quantum kinetic equation. It is shown that this formation is much faster than dissipation due to collisions, in hot (dense) plasma the correlations form on the timescale of inverse plasma frequency (Fermi energy). This hierarchy of characteristic times is used to derive analytical formulae fo

Ethan M. Coven, Aaron D. Meyerowitz

A set is said to tile the integers if and only if the integers can be written as a disjoint union of translates of that set. We consider the problem of finding necessary and sufficient conditions for a finite set to tile the integers. For sets of prime power size, it was solved by D. Newman [J. Number Theory 9 (1977), 107--111]. We solve it for sets of size

G. Date, Pijush K. Ghosh, M. V. N. Murthy

The classical ground state of a D- dimensional many body system with two and three body interactions is studied as a function of the strength of the three body interaction. We prove exactly that beyond a critical strength of the three body interaction, the classical ground state of the system is one in which all the particles are on a line. The positions of

Gerard van der Geer, René Schoof

We introduce the notion of an effective Arakelov divisor for a number field and the arithmetical analogue of the dimension of the space of sections of a line bundle. We study the analogue of the theta divisor for a number field.

K. Stokbro, Ben Yu-Kuang Hu, C. Thirstrup, X. C. Xie

A first principles theory of inelastic tunneling between a model probe tip and an atom adsorbed on a surface is presented, extending the elastic tunneling theory of Tersoff and Hamann. The inelastic current is proportional to the change in the local density of states at the center of the tip due to the addition of the adsorbate. We use the theory to investig

J. Cruz, A. Mikovic, J. Navarro-Salas

Cylindrically reduced Einstein gravity can be regarded as an $SL(2,R)/SO(2)$ sigma model coupled to 2D dilaton gravity. By using the corresponding 2D diffeomorphism algebra of constraints and the asymptotic behaviour of the Ernst equation we show that the theory can be mapped by a canonical transformation into a set of free fields with a Minkowskian target s

K. Morawetz, R. Walke, U. Fuhrmann

Starting from a nonmarkovian conserving relaxation time approximation for collisions we derive coupled dispersion relations for asymmetric nuclear matter. The isovector and isoscalar modes are coupled due to asymmetric nuclear meanfield acting on neutrons and protons differently. A further coupling is observed by collisional correlations. The latter one lead

Esteban Moro, Angel Sanchez

The synchronized phase of globally coupled nonlinear oscillators subject to noise fluctuations is studied by means of a new analytical approach able to tackle general couplings, nonlinearities, and noise temporal correlations. Our results show that the interplay between coupling and noise modifies the effective frequency of the system in a non trivial way. W

K. Morawetz, H. S. Köhler

The formation of correlations due to collisions in an interacting nucleonic system is investigated. Results from one-time kinetic equations are compared with the Kadanoff and Baym two-time equation with collisions included in Born approximation. A reasonable agreement is found for a proposed approximation of the memory effects by a finite duration of collisi

M. N. Chernodub, F. V. Gubarev, M. I. Polikarpov, A. I. Veselov

We discuss some properties of the abelian monopoles in compact U(1) gauge theory and in the SU(2) gluodynamics both on the lattice and in the continuum.

T. J. O'Brien, Judith G. Cohen

Recently, it has been claimed that the recurrent nova T Pyx exhibits oppositely directed jets of ejecta apparent in features seen in H alpha emission. Here we demonstrate that these features are in fact emission in the [N II] lines which lie either side of H alpha and arise from the expanding shell associated with this object rather than from collimated jets

Yuri G. Prokhorov

We study the local structure of Mori contractions $f\colon X\to Z$ of relative dimension one under an additional assumption that there exists a reduced divisor $S$ such that $K_X+S$ is plt and anti-ample.

Ernest Ma, Utpal Sarkar

A simple and economical extension of the minimal standard electroweak gauge model (without right-handed neutrinos) by the addition of two heavy Higgs scalar triplets would have two significant advantages. \underline {Naturally} small Majorana neutrino masses would become possible, as well as leptogenesis in the early universe which gets converted at the elec

M. Bonini, F. Vian

We extend the Wilson renormalization group (RG) to supersymmetric theories. As this regularization scheme preserves supersymmetry, we exploit the superspace technique. To set up the formalism we first derive the RG flow for the massless Wess-Zumino model and deduce its perturbative expansion. We then consider N=1 supersymmetric Yang-Mills and show that the l

Harald Fritzsch

In view of the observed strong hierarchy of the quark and lepton masses and of the flavor mixing angles it is argued that the description of flavor mixing must take this into account. One particular interesting way to describe the flavor mixing, which, however, is not the one used today, emerges, which is best suited for models of quark mass matrices based o

T. F. A. Muller, T. M. Rice

The 2-leg t-J ladder forms a spin liquid at half-filling which evolves to a Luther-Emery liquid upon doping. Our aim is to obtain a complete phase diagram for isotropic coupling (i.e. rungs and legs equal) as a function of electron density n and the ratio J/t (>0). Two known limiting cases are: n<1/2 which is a single band Luttinger liquid and small hole dop

Gilles Montambaux

The stability of a Charge Density Wave (CDW) in a one-dimensional ring pierced by a Aharonov-Bohm flux is studied in a mean-field picture. It is found that the stability depends on the parity of the number $N$ of electrons. When the size of the ring becomes as small as the coherence length $\xi$, the CDW gap increases for even $N$ and decreases for odd $N$.

William H. Kinney, Antonio Riotto

In models of cosmological inflation motivated by dynamical supersymmetry breaking, the potential driving inflation may be characterized by inverse powers of a scalar field. These models produce observables similar to those typical of the hybrid inflation scenario: negligible production of tensor (gravitational wave) modes, and a blue scalar spectral index. I

V. A. Kashurnikov, N. V. Prokof'ev, B. V. Svistunov, M. Troyer

We demonstrate that the ``worm'' algorithm allows very effective and precise quantum Monte Carlo (QMC) simulations of spin systems in a magnetic field, and its auto-correlation time is rather insensitive to the value of H at low temperature. Magnetization curves for the $s=1/2$ and $s=1$ chains are presented and compared with existing Bethe ansatz and exact

A. G. Percus, O. C. Martin

We study the random link traveling salesman problem, where lengths l_ij between city i and city j are taken to be independent, identically distributed random variables. We discuss a theoretical approach, the cavity method, that has been proposed for finding the optimal tour length over this random ensemble, given the assumption of replica symmetry. Using fin

Aleksandrs Mihailovs

The space of invariants of a tensor product of representations of SL(n) is provided with the basis parametrized by wave graphs introduced here especially for this purpose. The proof utilizes a game similar to Tetris, named here L-tris.

B. J. Feenstra, C. P. Vlahacos, Ashfaq S. Thanawalla, D. E. Steinhauer

We describe the near-field microwave microscopy of microwave devices on a length scale much smaller than the wavelength used for imaging. Our microscope can be operated in two possible configurations, allowing a quantitative study of either material properties or local electric fields.