August 1996 arXiv papers — page 13

J. -L. Alonso, Ph. Boucaud, A. J. van der Sijs

We present results concerning a lattice study of the electroweak $ρ$-parameter. We have used an SU(2)$\times$U(1) symmetric chiral Yukawa model built with Zaragoza fermions. The decoupling of the species doublers in this model is verified numerically. We find that the numerical data for $Δρ$ are well described by one-loop perturbation theory with the same fi

P. Bialas, Z. Burda, B. Petersson, J. Tabaczek

We discuss a general mechanism that drives the phase transition in the canonical ensemble in models of random geometries. As an example we consider a solvable model of branched polymers where the transition leading from tree- to bush-like polymers relies on the occurrence of vertices with a large number of branches. The source of this transition is a combina

P. Bialas

We compare two definitions of connected correlation functions in fluctuating geometries. We show results of the MC simulations for 4D dynamical triangulation in the elongated phase and compare them with the exact calculations of correlation functions in the branched polymer model.

H. Banerjee, Asit K. De

We propose a formulation of lattice fermions with one-sided differences that is hermitian, chirally symmetric (barring a bare mass term) and completely free of doubling. To obtain the axial anomaly in perturbation theory it was necessary to break chiral symmetry on the lattice only through a bare mass term for the physical fermion. The chiral limit may be ta

S. Bilke, Z. Burda, A. Krzywicki, B. Petersson

We present data indicating that the recent evidence for the phase transition being of first order does not result from a breakdown of the ergodicity of the algorithm. We also present data showing that the thermodynamical limit of the model is independent of topology.

Annalisa Calini, Thomas Ivey

The Backlund transformation for pseudospherical surfaces, which is equivalent to that of the sine-Gordon equation, can be restricted to give a transformation on space curves that preserves constant torsion. We study its effects on closed curves (in particular, elastic rods) that generate multiphase solutions for the vortex filament flow (also known as the Lo

G. Medeiros-Ribeiro, F. G. Pikus, P. M. Petroff, A. L. Efros

Sequential single-electron charging is observed in InAs Self-Assembled Quantum Dots using capacitance spectroscopy. In this system, the Coulomb energy is smaller than the inter-level energy spacings due to the quantum confinement and both effects can be separately identified. A theoretical model is proposed for this system and the capacitance experiments wer

R. A. Hyman, Kun Yang

Using an asymptotically exact real space renormalization procedure, we find that the Heisenberg antiferromagnetic spin-1 chain undergoes an impurity driven second order phase transition from the Haldane phase to the random singlet phase, as the bond distribution is broadened. In the Haldane phase and near the critical point, there is a Griffiths region in wh

A. V. Smirnov, A. M. Bratkovsky

We have performed ab initio studies to elucidate the unusual magnetic behavior recently observed in epitaxial Co films upon absorption of submonolayers of Cu and other materials. We find that a submonolayer amount of Cu on a stepped Co/Cu (100) film changes dramatically the electronic and magnetic structure of the system. The effect is mainly due to hybridiz

F. Süss, U. Krey, S. Krompiewski

Within a spin-polarized LMTO approach in the Atomic-Sphere approximation we calculate ab initio the magnetic properties of various binary and ternary multilayers composed of Fe, Co, Ni, Cr, V and Cu. The emphasis lies on the indirect exchange interaction of the magnetic sandwiches across the antiferromagnetic or non-magnetic spacers, and on the profiles of t

Ronald Fisch

Monte Carlo simulations have been used to study the Z6 ferromagnet in a random field on simple cubic lattices, which is a simple model for randomly pinned charge-density waves. The random field is chosen to have infinite strength on a fraction x of the sites of the lattice, and to be zero on the remaining sites. For x= 1/16 there are two phase transitions. A

J. Lorenzana, R. Eder

We use numerical and analytical results to construct a simple ansatz for the energy dynamical correlation function of the 1D antiferromagnetic Heisenberg model. This is applied to compute the phonon assisted absorption spectra of magnetic excitations (spinons) in quasi-one dimensional spin 1/2 insulators and show to reproduce very well recent infrared measur

R. W. Ruhwandl, E. M. Terentjev

The flow of a liquid crystal around a particle does not only depend on its shape and the viscosity coefficients but also on the direction of the molecules. We studied the resulting drag force on a sphere moving in a nematic liquid crystal (MBBA) in a low Reynold's number approach for a fixed director field (low Ericksen number regime) using the computati

Hernan A. Makse, Sergey Buldyrev, Heiko Leschhorn, H. Eugene Stanley

We introduce a model describing the paths that pin an elastic interface moving in a disordered medium. We find that the scaling properties of these ``elastic pinning paths'' (EPP) are different from paths embedded on a directed percolation cluster, which are known to pin the interface of the ``directed percolation depinning'' class of surface

Klaus Kirsten, David J. Toms

We discuss how it is possible to obtain a reliable approximation for the density of states for a system of particles in an anisotropic harmonic oscillator potential. A direct application of the result to study Bose-Einstein condensation of atomic gases in a potential trap can be given. In contrast to a previous study, our method involves only analytic calcul

S. Krompiewski, U. Krey

Oscillations of magnetoresistance and thermo-electric power (TEP) vs. both nonmagnetic spacer as well as ferromagnetic slab thicknesses are studied in the current-perpendicular-to-plane (CPP) geometry, in terms of a single-band tight-binding model. The spin-dependent conductance has been calculated from the Kubo formula by means of a recursion Green's fu

T. Husslein, I. Morgenstern, D. M. Newns, P. C. Pattnaik

We implement a Quantum Monte Carlo calculation for a repulsive Hubbard model with nearest and next-nearest neighbor hopping interactions on clusters up to 12x12. A parameter region where the Fermi level lies close to the van Hove singularity at the Saddle Points in the bulk band structure is investigated. A pairing tendency in the $d_{x^2-y^2}$ symmetry chan

Eric G. Blackman

Standard magnetohydrodynamic theories, such as the mean field dynamo theory, have been criticized when the back reaction of the magnetic field on turbulent motions is neglected. For the dynamo, this back reaction has been argued to suppress the turbulent motions required for optimal mean field production. Here it is suggested that if the magnetic field is sp

K. P. Levenfish, D. G. Yakovlev

Calculations are performed of the cooling of neutron stars with standard and enhanced neutrino energy losses in the presence of neutron and proton superfluidities in the stellar cores. The effects of superfluidity on the heat capacity and the neutrino luminosity produced by the direct and modified Urca processes and by the neutrino bremsstrahlung emission in

Martin G. Haehnelt

The recently approved COBRAS/SAMBA cosmic microwave background mission will also have a major impact on measurements of the Sunyaev-Zeldovich effect. The frequency of three of the channels (150 GHz, 217 GHz, 353 GHz) are chosen to optimize measurements of the thermal and kinetic SZ effect mainly caused by hot gas in clusters of galaxies. Estimates of the num

David A. Buote, Claude R. Canizares

We present spectral analysis of $ASCA$ observations of the early-type galaxies NGC 720 (E4) and NGC 1332 (E7/S0) with emphasis on constraining the relative contribution to the X-ray emission from hot gas and the integrated emission from X-ray binaries. Single-temperature spectral models yield poor fits to the spectrum ($χ^2_{red}\sim 3$) over the $\sim 0.5 -

Bianca Maria Poggianti

$K$ and evolutionary corrections are given for the E, Sa and Sc Hubble types for the $U, B, V, R, I, J, H, K$ filters of the Johnson -- Bessell \& Brett photometric system and the $gri$ filters of the modified Thuan \& Gunn system up to the redshift $z=3$. Their dependence on the time scale of star formation in ellipticals is investigated. The corrections ar

Richard J. Greatbatch, K. Andrew Peterson

Changes in the strength of the thermohaline overturning circulation are associated, by geostrophy, with changes in the east-west pressure difference across an ocean basin. The tropical-polar density contrast and the east-west pressure difference are connected by an adjustment process. In flat-bottomed ocean models the adjustment is associated with viscous, b

F. J. Gallego, B. P. Purnaprajna

In this article we prove some strong vanishing theorems on K3 surfaces. As an aplication of them, we obtain higher syzygy results for K3 surfaces and Fano varieties.

M. Bowick, V. John, G. Thorleifsson

Within the framework of string field theory the intrinsic Hausdorff dimension d_H of the ensemble of surfaces in two-dimensional quantum gravity has recently been claimed to be 2m for the class of unitary minimal models (p = m+1,q = m). This contradicts recent results from numerical simulations, which consistently find d_H approximatly 4 in the cases m = 2,

Michael Creutz

I conjecture on the phase structure expected for lattice gauge theory with two flavors of Wilson fermions, concentrating on large values of the hopping parameter. Numerous phases are expected, including the conventional confinement and deconfinement phases, as well as an Aoki phase with spontaneous breaking of flavor and parity and a large hopping phase corr

A. R. Calderbank, E. M Rains, P. W. Shor, N. J. A. Sloane

The problem of finding quantum error-correcting codes is transformed into the problem of finding additive codes over the field GF(4) which are self-orthogonal with respect to a certain trace inner product. Many new codes and new bounds are presented, as well as a table of upper and lower bounds on such codes of length up to 30 qubits.

Juan Carlos D'Olivo, Manuel Torres, Eduardo Tututi

We study the discrete and gauge symmetries of Quantum Electrodynamics at finite temperature within the real-time formalism. The gauge invariance of the complete generating functional leads to the finite temperature Ward identities. These Ward identities relate the eight vertex functions to the elements of the self-energy matrix. Combining the relations obtai

Axel Voelker, Peter Kopietz

We use the Lanczos method to calculate the variance of the number of energy levels in an energy window of width E below the Fermi energy for non-interacting disordered electrons on a thin three-dimensional ring threaded by an Aharonov-Bohm flux . We find that for small E the flux-dependent part of the variance is well described by a well-known Feynman diagra

Agnieszka Zalewska, Kacper Zalewski

Simple and plausible rules are used to correlate the masses of the ground-state baryons containing single heavy ($b$ or $c$) quarks. A comparison with the experimental data shows that the observed mass difference between the $Σ_b$ and the $Σ^*_b$ is unexpectedly large. Predictions for the masses of the yet undiscovered heavy baryons are given.

Sang Pyo Kim, Sung Ku Kim, Kwang-Sup Soh, Jae Hyung Yee

We study the ultraviolet divergent structures of the matter (scalar) field in a higher D-dimensional Reissner-Nordström black hole and compute the matter field contribution to the Bekenstein-Hawking entropy by using the Pauli-Villars regularization method. We find that the matter field contribution to the black hole entropy does not, in general, yield the co

P. Chiappetta, J. -M. Virey

The absence of deviations from the Standard Model for the differential cross section ${dσ}/{dQ^2}$ at HERA is used to set limits on electron quark compositeness scale and on new vector bosons, especially the hadrophilic one recently introduced as a possible explanation for LEP/SLC and CDF anomalies.

Cai-Dian Lu, Han-Wen Huang

We give a more complete calculation of $b \to s e^+e^- $ decay including leading log QCD corrections from $m_{top}$ to $M_W$ in addition to corrections from $M_{W}$ to $m_b$. The differential decay rate is found to be slightly suppressed for a large invariant mass of the $e^+e^- $ pair; while the integrated width is slightly enhanced comparing with the resul

Zeev Olami, Barak Galanti, Oleg Kupervasser, Itamar Procaccia

The problem of flame propagation is studied as an example of unstable fronts that wrinkle on many scales is studied. The analytic tool of pole expansion in the complex plane is emloyed to address the interaction of the unstable growth process with random initial conditions and perturbations. We argue that the effect of random noise is immense and that it can

Brien C. Nolan

The effect of the existence of tails on the propagation of scalar waves in curved space-time is considered via an analysis of flux integrals of the energy-stress-momentum tensor of the waves. The geometric optics approximation is formulated in terms of such flux integrals, and three examples are investigated in detail in order to determine the possible effec

Shaojin Qin, Michele Fabrizio, Lu Yu

The behavior of a single impurity in a one-dimensional Luttinger liquid is numerically investigated by means of the density matrix renormalization group. By analyzing the finite size scaling behavior of the low energy spectrum, we confirm the theoretical prediction of Kane and Fisher [Phys. Rev. Lett. {\bf 68}, 1220 (1992)] both for attractive and repulsive

S. Kalyana Rama

We present a class of graviton-dilaton models in which a homogeneous isotropic universe, such as our observed one, evolves with no singularity at any time. Such models may stand on their own as interesting models for singularity free cosmology, and may be studied further accordingly. They may also arise from string theory. We discuss critically a few such po

Kazunobu Haga, Hiroshi Igarashi, Kiyoshi Okuyama, Hiroshi Suzuki

It is interesting to superimpose the Pauli-Villars regularization on the lattice regularization. We illustrate how this scheme works by evaluating the axial anomaly in a simple lattice fermion model, the Pauli-Villars Lagrangian with a gauge non-invariant Wilson term. The gauge non-invariance of the axial anomaly, caused by the Wilson term, is remedied by a

Wen-Xiu Ma, Qing Ding, Wei-Guo Zhang, Bao-Qun Lu

Kaup-Newell soliton hierarchy is derived from a kind of Lax pairs different from the original ones. Binary nonlinearization procedure corresponding to the Bargmann symmetry constraint is carried out for those Lax pairs. The proposed Lax pairs together with adjoint Lax pairs are constrained as a hierarchy of commutative, finite dimensional integrable Hamilton

Masako Bando, Katsuya Hasebe, Ken Nakanishi, Akihiro Nakayama

We demonstrate that in Optimal Velocity Model (OVM) delay times of vehicles coming from the dynamical equation of motion of OVM almost explain the order of delay times observed in actual traffic flows without introducing explicit delay times. Delay times in various cases are estimated: the case of a leader vehicle and its follower, a queue of vehicles contro

Philip Welch

Let D = { d_n } be a countable collection of Delta^1_3 degrees. Assuming that all co-analytic games on integers are determined (or equivalently that all reals have ``sharps''), we prove that either D has a Delta^1_3-minimal upper bound, or that for any n, and for every real r recursive in d_n, games in the pointclasses Delta^1_2(r) are determined. Th

Ian I. Kogan

We discuss the $2+1$ dimensional description of the $Φ_{1,3}$ deformation of the minimal model $M_p$ leading to a transition $M_p \rightarrow M_{p-1}$. The deformation can be considered as an addition of the charged matter to the Chern-Simons theory describing a minimal model. The $N=1$ superconformal case is also considered.

Swapna Mahapatra

We study string propagation in an exact, four-dimensional dyonic black hole background. The general solutions describing string configurations are obtained by solving the string equations of motion and constraints. By using the covariant formalism, we also investigate the propagation of physical perturbations along the string in the given curved background.

John R. Klauder, Sergei V. Shabanov

The coordinate-free formulation of canonical quantization, achieved by a flat-space Brownian motion regularization of phase-space path integrals, is extended to a special class of closed first-class constrained systems that is broad enough to include Yang-Mills type theories with an arbitrary compact gauge group. Central to this extension are the use of cohe

Otto C. W. Kong

We give a detailed description of the model construction procedures about our new approach to the family structure of the standard model. SM-like chiral fermion spectra, largely "derivable" from the gauge anomaly constraints, are formulated in a $SU(N)\otimes SU(3)\otimes SU(2)\otimes U(1)$ symmetry framework as an extension of the SM symmetry. The $

T. Binoth, J. J. van der Bij

To investigate the possible effects of a light hidden sector on Higgs boson detection, we discuss a model of scalar singlets coupled to the Standard Model. The model effectively makes the Higgs width a free parameter due to additional invisible decay modes. This width can become arbitrarily large. Theoretical and experimental bounds on model parameters are p

Mohammad Ali Yusuf, Pervez Hoodbhoy

A systematic gauge-invariant method is used to calculate the rate for an upsilon meson to decay inclusively into a prompt photon. An expansion is made in the quark relative velocity v, which is a small natural parameter for heavy quark systems. Inclusion of these O(v^2) corrections tends to increase the photon rate in the middle z range and to lower it for l

T. E. Clark, S. T. Love

A nonlinearly realized supersymmetric action describing the invariant couplings of the Goldstino to matter is constructed. Using the Akulov-Volkov Lagrangian, any operator can be made part of a supersymmetric invariant action. Of particular interest are interaction terms which include the product of the Akulov-Volkov Lagrangian with the ordinary matter Lagra

R. D. Amado, Yang Lu

The probability distribution of neutral pion fraction from independent domains of disoriented chiral condensate is characterized. The signal for the condensate is clear for a small number of domains but is greatly reduced for more than three.

V. A. Bednyakov, S. G. Kovalenko, H. V. Klapdor-Kleingrothaus

We address the question of how light can be the lightest supersymmetric particle neutralino to be a reliable cold dark matter (CDM) particle candidate. To this end we have performed a combined analysis of the parameter space of the Minimal Supersymmetric Standard Model (MSSM) taking into account cosmological and accelerator constraints including those from t

P. Chiappetta

Precise measurements of weak vector bosons self couplings give a hint on the electroweak symmetry breaking sector. We first stress that present data from LEP and TEVATRON clearly indicate that weak bosons are self interacting. We then review the limits on the trilinear and quadrilinear couplings expected at LEP2, $e^+e^-$ linear colliders and LHC.

Dan Mønster Jensen, Jes Madsen, Michael B. Christiansen

When considering strangelets at finite temperature it is important to obey the constraint that any observed state must be color singlet. This constraint results in an increase in strangelet masses as calculated at fixed entropy per baryon. We use the color singlet partition function for an MIT bag, derived using the group theoretical projection method, to ca

Pietro Santorelli

The non-leptonic two body decays of D mesons are studied in the framework of an improved factorization approximation. The final state interaction effects are taken into account assuming them dominated by nearby resonances. The agreement with experimental data is quite good. CP-violating asymmetries are predicted.

D. P. Roy

I report on a systematic analysis of the MSSM parameter space to obtain the best SUSY solution to the $R_b$ anomaly within the constraint of top quark decay. Phenomenological implications for top decay and direct stop production at the Tevatron collider are discussed.

Yoshiharu Kawamura, Tatsuo Kobayashi

We derive formula of soft supersymmetry breaking scalar masses from 4-dimensional string models within a more generic framework. We consider effects of extra gauge symmetry breakings including an anomalous $U(1)$ breaking through flat directions, that is, $D$-term and $F$-term contributions, particle mixing effects and heavy-light mass mixing effects. Some p

C. Bernard, T. Blum, C. E. DeTar, Steven Gottlieb

We conclude our analysis of the N_t=6 equation of state for two flavor QCD, first described at last year's conference. We have obtained new runs at am_q=0.025 and improved runs at am_q=0.0125. The results are extrapolated to m_q=0, and we extract the speed of sound as well. We also present evidence for a restoration of the SU(2) X SU(2) chiral symmetry j

Y. Meurice, S. Niermann, G. Ordaz

We calculate 800 coefficients of the high-temperature expansion of the magnetic susceptibility of Dyson's hierarchical model with a Landau-Ginzburg measure. Log-periodic corrections to the scaling laws appear as in the case of a Ising measure. The period of oscillation appears to be a universal quantity given in good approximation by the logarithm of the

Y. Meurice, G. Ordaz

We present a two-parameter family of recursion formulas for scalar field theory. The first parameter is the dimension $(D)$. The second parameter ($ζ$) allows one to continuously extrapolate between Wilson's approximate recursion formula and the recursion formula of Dyson's hierarchical model. We show numerically that at fixed $D$, the critical expon

J. Ambjorn, K. N. Anagnostopoulos, U. Magnea, G. Thorleifsson

We perform Monte Carlo simulations of 2-d dynamically triangulated surfaces coupled to Ising and three--states Potts model matter. By measuring spin-spin correlation functions as a function of the geodesic distance we provide substantial evidence for a diverging correlation length at $β_c$. The corresponding scaling exponents are directly related to the KPZ

M. Pillai, E. Hayashi, K. Maeshima, C. Pilcher

A search for a neutral heavy vector gauge boson, Zprime, was conducted in pbar-p collisions using 110pb$^{-1}$ of data obtained at the Collider Detector at Fermilab. We present preliminary 95% CL limits on the production of Zprime in different models using its e+e- and mu+mu- decay modes.

Pekka K. Sinervo

The techniques used to study top quarks at hadron colliders are presented. The analyses that discovered the top quark are described, with emphasis on the techniques used to tag b-quark jets in candidate events. The most recent measurements of top quark properties by the CDF and DZero collaborations are reviewed, including the top quark cross section, mass, b

Ursula Becker

Several recent results of the ALEPH Collaboration covering different aspects of baryon production on the Z resonance are presented. In particular production rates of hyperons, the full kinematical reconstruction of the Lambda_b, observation of Xi_b in its semileptonic decay, and the measurements of the polarization of Lambda and Lambda_b baryons are discusse

Abhay Ashtekar, Alejandro Corichi

It is shown that there is an interesting interplay between self-duality, loop representation and knots invariants in the quantum theory of Maxwell fields in Minkowski space-time. Specifically, in the loop representation based on self-dual connections, the measure that dictates the inner product can be expressed as the Gauss linking number of thickened loops.

Jose' P. S. Lemos

The two-dimensional theory of Teitelboim and Jackiw has constant and negative curvature. In spite of this, the theory admits a black hole solution with no singularities. In this work we study the thermodynamics of this black hole using York's formalism.

Y. B. Grinkevich

W.Lawvere suggested a approach to differential geometry and to others mathematical disciplines closed to physics, which allows to give definitions of derivatives, tangent vectors and tangent bundles without passages to the limits. This approach is based on a idea of consideration of all settings not in sets but in some cartesian closed category E, particular

V. Tsemekhman, K. Tsemekhman, C. Wexler, J. H. Han

Breakdown of the Quantum Hall Effect at high values of injected current is explained as a consequence of an abrupt formation of a metallic ``river'' percolating from one edge of the sample to the other. Such river is formed when lakes of compressible liquid, where the long-range disorder potential is screened, get connected with each other due to the

L. W. Bernardi, S. Prakash, I. A. Campbell

We propose a numerical criterion which can be used to obtain accurate and reliable values of the ordering temperatures and critical exponents of spin glasses. Using this method we find an value of the ordering temperature for the $\pm J$ Ising spin glass in three dimensions which is definitely non-zero and in good agreement with previous estimates. We show t

J. T. Liu, D. F. Wang

We study the one-dimensional supersymmetric t-J model with 1/r2 interaction threaded by magnetic flux. Because of the long range interaction, the effect of this flux leads to a modification of the electron hopping term. We present an exact solution of this model for all values of the flux, concisely formulated as a set of Bethe-ansatz-like equations. This al

A. T. Costa, M. T. Thomaz

The dynamical evolution of a two-site Hubbard model is derived in the presence of an uniform external magnetic field for a general initial state. The time evolution of the half-filled (two-particle) case has a complex behaviour. Under certain initial conditions, the average number of fermions in one-particle state, in the half-filled case, is not necessarily

Kent Baekgaard Lauritsen, Rodolfo Cuerno, Hernan A. Makse

We derive the continuum equation for a discrete model for ion sputtering. We follow an approach based on the master equation, and discuss how it can be truncated to a Fokker-Planck equation and mapped to a discrete Langevin equation. By taking the continuum limit, we arrive at the Kuramoto-Sivashinsky equation with a stochastic noise term.

H. Kajueter, G. Kotliar, D. D. Sarma, S. Barman

We discuss the experimental photoemission and inverse photoemission of early transition metal oxides, in the light of the dynamical mean field theory of correlated electrons which becomes exact in the limit of infinite dimensions. We argue that a comprehensive description of the experimental data requires spatial inhomogeneities and present a calculation of

J. A. Verges

Level and wavefunction statistics have been studied for two dimensional clusters of the square lattice in the presence of random magnetic fluxes. Fluxes traversing lattice plaquettes are distributed uniformly between - (1/2) Phi_0 and (1/2) Phi_0 with Phi_0 the flux quantum. All considered statistics start close to the corresponding Wigner-Dyson distribution

Rolf Backofen

There have been two different methods for checking the satisfiability of feature descriptions that use the functional uncertainty device, namely~\cite{Kaplan:88CO} and \cite{Backofen:94JSC}. Although only the one in \cite{Backofen:94JSC} solves the satisfiability problem completely, both methods have their merits. But it may happen that in one single descrip

Alessandro Torcini

The maximal conserved phase gradient is introduced as an order parameter to characterize the transition from phase- to defect-turbulence in the complex Ginzburg-Landau equation. It has a finite value in the phase-turbulent regime and decreases to zero when the transition to defect-turbulence is approached. Solutions with a non-zero phase gradient are studied

Sascha Hilgenfeldt, Detlef Lohse, Michael Brenner

Sound driven gas bubbles in water can emit light pulses. This phenomenon is called sonoluminescence (SL). Two different phases of single bubble SL have been proposed: diffusively stable and diffusively unstable SL. We present phase diagrams in the gas concentration vs forcing pressure state space and also in the ambient radius vs gas concentration and vs for

James M. Cordes, T. Joseph W. Lazio

Radio-wave scattering is enhanced dramatically for Galactic center sources in a region with radius >~ 15 arc min. Using scattering from Sgr A* and other sources, we show that pulse broadening for pulsars in the Galactic center is {\em at least} 6.3 ν^{-4} seconds (ν= radio frequency in GHz) and is most likely 50--200 times larger because the relevant scatter

H. J. A. Röttgering, Y. Tang, M. A. R. Bremer, A. G. de Bruyn

An FRII radio source with an angular extension of 18.4 arcminutes has been discovered in the Westerbork Northern Sky Survey that is being carried out at 325 MHz. This source is identified with Mrk 1498 at $z=0.056$ indicating that its projected extension is 1.6 \h50\ Mpc. The optical spectrum of Mrk 1498 has the typical emission lines of a narrow line radio

Michael R. Douglas, Daniel Kabat, Philippe Pouliot, Stephen H. Shenker

We study the behavior of D-branes at distances far shorter than the string length scale~$l_s$. We argue that short-distance phenomena are described by the IR behavior of the D-brane world-volume quantum theory. This description is valid until the brane motion becomes relativistic. At weak string coupling $\gs$ this corresponds to momenta and energies far abo

Craig Pryor

Paper withdrawn. A revised version may appear later.

N. G. Deshpande, B. Dutta, Sechul Oh

We consider the origin of new phases in supersymmetric grand unification model, and show how significant new contributions arise from the gluino mediated diagram. We then present a more general model independent analysis of various modes of B-decays suggested previously for measurement of the CKM phases and point out what they really measure. It is in princi

Attila Csoto, G. M. Hale

We study the low-energy 3/2- and 1/2- states of He-5 and Li-5 in a microscopic cluster model. The scattering phase shifts of Bond (alpha+n) and of Schwandt (alpha+p), respectively, are reproduced well. We determine the resonance parameters by localizing the poles of the analytically continued S-matrix at complex energies. Our results differ from conventional

Siegfried Grossmann, Detlef Lohse, Achim Reeh

Developed Navier-Stokes turbulence is simulated with varying wavevector mode reductions. The flatness and the skewness of the velocity derivative depend on the degree of mode reduction. They show a crossover towards the value of the full numerical simulation when the viscous subrange starts to be resolved. The intermittency corrections of the scaling exponen

Hagai El-Ad, Tsvi Piran, Luiz Nicolaci da Costa

Using the VOID FINDER algorithm we have compiled a catalogue of voids in the IRAS 1.2-Jy sample. The positions of the voids correspond well to underdense regions seen in the IRAS smoothed density map. However, since in our analysis no smoothing is used, all structures appear much sharper: walls are not smeared and the voids are not artificially reduced by th

Max Tegmark, Angelica de Oliveira-Costa, Marc Devlin, Barth Netterfield

We present a Wiener filtered map of the Cosmic Microwave Background (CMB) fluctuations in a disk with 15 degree diameter, centered at the North Celestial Pole. The map is based on the 1993-1995 data from the Saskatoon (SK) experiment, with an angular resolution around 1 degree in the frequency range 27.6-44.1 GHz. The signal-to-noise ratio in the map is of o

David R. Morrison

The recent result of Strominger, Yau and Zaslow relating mirror symmetry to the quantum field theory notion of T-duality is reinterpreted as providing a way of geometrically characterizing which Calabi-Yau manifolds have mirror partners. The geometric description---that one Calabi-Yau manifold should serve as a compactified, complexified moduli space for spe

M. Hayakawa

The behavior of the $V^0$-$\pi^+$ scattering amplitude (where $V^0 = \rho^0 , \omega$ , or $\phi$) in the low pion momentum limit is studied motivated by its relevance to the theory of muon $g - 2$. Current algebra analysis shows that its S-wave component must vanish in the chiral limit under general physical assumptions. We confirm this result with various

Stephen P. Martin

We investigate the sparticle spectrum in models of gauge-mediated supersymmetry breaking. In these models, supersymmetry is spontaneously broken at an energy scale only a few orders of magnitude above the electroweak scale. The breakdown of supersymmetry is communicated to the standard model particles and their superpartners by "messenger" fields thr

H. C. Rosu

A small collection of general facts related to DNA is presented

D. B. Fairlie

A large class of first order partial nonlinear differential equations in two independent variables which possess an infinite set of polynomial conservation laws derived from an explicit generating function is constructed. The conserved charge densities are all homogeneous polynomials in the unknown functions which satisfy the differential equations in questi

T. Mor

We show two new aspects of teleportation based on generalized measurements: I. We present an alternative approach to teleportation based on ``generating $ρ$-ensembles at spacetime separation''; This approach provides a better understanding of teleportation. II. We define the concept of {\em conclusive teleportation} and we show how to teleport a quan

Ruediger Schack, Todd A. Brun

Quantum trajectory methods can be used for a wide range of open quantum systems to solve the master equation by unraveling the density operator evolution into individual stochastic trajectories in Hilbert space. This C++ class library offers a choice of integration algorithms for three important unravelings of the master equation. Different physical systems

A. A. Nepomnyashchy, L. M. Pismen

Interaction of a vortex in a circularly polarized superfluid component of a 2d complex vector field with the phase boundary between superfluid phases with opposite signs of polarization leads to a resonant excitation of a ``capillary'' wave on the boundary. This leads to energy losses by the vortex--image pair that has to cause its eventual annihilat

Namyoung Lee, Hong Jung, Dongwoo Cha

We analyze the recent data on the non-mesonic decays of light Lambda-hypernuclei up to ^12_Lambda C using the phenomenological model of Block and Dalitz. Fitting the spin-isospin dependent Lambda N -> NN reaction rates to six data points, we predict the remaining data in reasonable consistency. We find that despite the short-range nature of the Lambda N -> N

K. Yaman, P. Pincus, F. Solis, T. A. Witten

We apply results derived in other contexts for the spectrum of the Laplace operator in curved geometries to the study of an ideal polymer chain confined to a spherical annulus in arbitrary space dimension D and conclude that the free energy compared to its value for an uncurved box of the same thickness and volume, is lower when $D < 3$, stays the same when

Guangbin Ren, Jihuai Shi

In the paper, we discuss on the egg domains: $$ Ω_a=\left\{ξ=(z,w)\in\bold C^{n+m}: \ z\in\bold C^n, \ w\in\bold C^m, |z|^2+|w|^{2/a}<1\right\}, \qquad 0<a\le 2. $$ We show that Gleason&#39;s problem can be solved in the weight Bergman space on theegg domains. The proof will need the help of the recent work of the second named author on the weighted Bergman

P. J. Hodges, Noureddine Mohammedi

The act of implementing non-Abelian duality in two dimensional sigma models results unavoidably in an additional reducible symmetry. The Batalin-Vilkovisky formalism is employed to handle this new symmetry. Valuable lessons are learnt here with respect to non-Abelian duality. We emphasise, in particular, the effects of the ghost sector corresponding to this

Andrea Pasquinucci, Kaj Roland

We study the CPT theorem for a two-dimensional conformal field theory on an arbitrary Riemann surface. On the sphere the theorem follows from the assumption that the correlation functions have standard hermiticity properties and are invariant under the transformation $z \rightarrow 1/z$. The theorem can then be extended to higher genus surfaces by sewing. We

J. D. Correia, J. F. Wheater

We consider a simple model of d families of scalar field interacting with geometry in two dimensions. The geometry is locally flat and has only global degrees of freedom. When d<0 the universe is locally two dimensional but for d>0 it collapses to a one dimensional manifold. The model has some, but not all, of the characteristics believed to be features of t

Kazuo Ghoroku

Quantum theory of 2d gravity is examined by including a special quantum correction, which corresponds to the open string loop corrections and provides a new conformal anomaly for the corresponding $σ$ model. This anomaly leads to the condensation of the tachyon, and the resultant effective theory implies a possibility of extending the 2d gravity to the case

Petr Horava

Strongly coupled heterotic $E_8\times E_8$ string theory, compactified to four dimensions on a large Calabi-Yau manifold ${\bf X}$, may represent a viable candidate for the description of low-energy particle phenomenology. In this regime, heterotic string theory is adequately described by low-energy $M$-theory on ${\bf R}^4\times{\bf S}^1/{\bf Z}_2\times{\bf