June 1997 arXiv papers

Philip Candelas, Harald Skarke

We show that the F-theory dual of the heterotic string with unbroken Spin(32)/Z_2 symmetry in eight dimensions can be described in terms of the same polyhedron that can also encode unbroken E_8\times E_8 symmetry. By considering particular compactifications with this K3 surface as a fiber, we can reproduce the recently found `record gauge group' in six d

Kathleen Streets

Results from analyses of events with W and Z bosons are presented for the D0 Tevatron run 1B data samples. From the leptonic decays of the W and Z, the W and Z production cross sections and the W width are determined. Events in which the W decays into a tau and neutrino are used to determine the ratio of the electroweak gauge coupling constants as a measure

Miao Li, Yong-Shi Wu

We derive, in path integral approach, the (anomalous) master Ward identity associated with an infinite set of nonlocal conservation laws in two-dimensional principal chiral models

V. Emel'yanov, A. Khodinov, S. R. Klein, R. Vogt

The effect of gluon shadowing on charm quark production in large impact parameter ultrarelativistic heavy ion collisions is investigated. Charm production cross sections are calculated for a range of non-central impact parameters which can be accurately inferred from the global transverse energy distribution. We show that charm production is a good probe of

A. Jevicki, M. Mihailescu, J. P. Nunes

We explore the quantum properties of self-dual gravity formulated as a large $N$ two-dimensional WZW sigma model. Using a non-trivial classical background, we show that a $(2,2)$ space-time is generated. The theory contains an infinite series of higher point vertices. At tree level we show that, in spite of the presence of higher than cubic vertices, the on-

Markus A. Luty

We describe a simple class of supersymmetric gauge theories that can act as supersymmetry-breaking sectors for gauge-mediated supersymmetry breaking. The models have a local supersymmetry-breaking minimum along a direction in field space where a singlet gets a large expectation value. The potential along this direction has a runaway behavior stabilized by su

L. Saminadayar, D. C. Glattli, Y. Jin, B. Etienne

The existence of fractional charges carrying the current is experimentally demonstrated. Using a 2-D electron system in high magnetic field, we measure the shot noise associated with tunneling in the fractional quantum Hall regime at Landau level filling factor 1/3. The noise gives a direct determination of the quasiparticle charge, which is found to be e*=e

A. Buonanno, K. A. Meissner, C. Ungarelli, G. Veneziano

We generalize previous work on inhomogeneous pre-big bang cosmology by including the effect of non-trivial moduli and antisymmetric-tensor/axion fields. The general quasi-homogeneous asymptotic solution---as one approaches the big bang singularity from perturbative initial data---is given and its range of validity is discussed, allowing us to give a general

P. Nielaba, J. L. Lebowitz

We use Monte Carlo techniques and analytical methods to study the phase diagram of the M--component Widom-Rowlinson model on the bcc-lattice: there are M species all with the same fugacity z and a nearest neighbor hard core exclusion between unlike particles. Simulations show that for M greater or equal 3 there is a ``crystal phase'' for z lying betw

L. L. Bonilla, F. G. Padilla, F. Ritort

The low temperature Monte Carlo dynamics of an ensemble of linear harmonic oscillators shows some entropic barriers related to the difficulty of finding the directions in configurational space which decrease the energy. This mechanism is enough to observe some typical non-equilibrium features of glassy systems like activated-type behavior and aging in the co

M. Blasone, T. S. Evans, D. A. Steer, G. Vitiello

We look at a real scalar field in thermal equilibrium in the context of the new normal ordering and field split defined by Evans and Steer. We show that the field split defines a natural canonical transformation, but that this transformation differs from others known in thermal field theory.

Timo Aspelmeier, Götz Giese, Annette Zippelius

We present results of simulations for a dilute gas of inelastically colliding particles. Collisions are modelled as a stochastic process, which on average decreases the translational energy (cooling), but allows for fluctuations in the transfer of energy to internal vibrations. We show that these fluctuations are strong enough to suppress inelastic collapse.

T. Blum, A. Soni

We present lattice calculations of kaon matrix elements with domain wall fermions. Using lattices with beta=5.85, 6.0, and 6.3, we estimate B_K(approx 2 GeV)=0.628(47) in quenched QCD which is consistent with previous calculations. At beta=6.0 and 5.85 we find the ratio f_K/m_rho in agreement with the experimental value, within errors. These results support

H. -P. Pavel, V. N. Pervushin

We quantize massive vector theory in such a way that it has a well-defined massless limit. In contrast to the approach by Stückelberg where ghost fields are introduced to maintain manifest Lorentz covariance, we use reduced phase space quantization with nonlocal dynamical variables which in the massless limit smoothly turn into the photons, and check explici

A. Smilga, A. Veselov

We study the domain walls connecting different chirally asymmetric vacua in supersymmetric QCD. We show that BPS - saturated solutions exist only in the limited range of mass. When m exceeds some critical value, the domain wall either ceases to be BPS - saturated or disappears altogether. In any case, the properties of the system are qualitatively changed.

Kiyoshi Higashijima, Muneto Nitta, Kazutoshi Ohta, Nobuyoshi Ohta

In N=1 supersymmetric theories, quasi Nambu-Goldstone (QNG) bosons appear in addition to ordinary Nambu-Goldstone (NG) bosons when the global symmetry G breaks down spontaneously. We investigate two-body scattering amplitudes of these bosons in the low-energy effective Lagrangian formalism. They are expressed by the curvature of Kahler manifold. The scatteri

Giulio Magli

New, simple models of ``black hole interiors&#39;&#39;, namely spherically symmetric solutions of the Einstein field equations in matter matching the Schwarzschild vacuum at spacelike hypersurfaces ``R<2M&#39;&#39; are constructed. The models satisfy the weak energy condition and their matter content is specified by an equation of state of the elastic type.

S. Dawson, S. Alam, R. Szalapski

It is possible to place constraints on non-Standard-Model gauge-boson self-couplings and other new physics by studying their one-loop contributions to precisely measured observables. We extend previous analyses which constrain such nonstandard couplings, and we present the results in a compact and transparent form. Particular attention is given to comparing

G. F. Giudice, R. Rattazzi

We show that in theories in which supersymmetry breaking is communicated by renormalizable perturbative interactions, it is possible to extract the soft terms for the observable fields from wave-function renormalization. Therefore all the information about soft terms can be obtained from anomalous dimensions and beta functions, with no need to further comput

Kwei-Chou Yang

A varying external field approach in QCD sum rules is formulated in a systematic way to treat the weak decay form factors and their $q^2$ dependence in the process of $B \to ρ\ell \barν_\ell$. From the form factor sum rules, we can also obtain the mass sum rules for B and $ρ$ mesons, which can help us determine the reliable Borel windows in studying the rele

M. A. Nielsen, Carlton M. Caves, Benjamin Schumacher, Howard Barnum

Quantum operations provide a general description of the state changes allowed by quantum mechanics. The reversal of quantum operations is important for quantum error-correcting codes, teleportation, and reversing quantum measurements. We derive information-theoretic conditions and equivalent algebraic conditions that are necessary and sufficient for a genera

A. Ohnishi, Y. Nara, V. Koch

We investigate in-medium corrections to the branching ratio in K- absorption at rest and their effect on the (positively and negatively) charged pion spectrum. The in-medium corrections are due to Pauli blocking, which arises if the Lambda(1405) is assumed to be a $\bar{K}$-nucleon bound state and leads to a density and momentum dependent mass shift of the L

Michael Freedman, Hugh Howards, Ying-Qing Wu

An incompressible surface $F$ on the boundary of a compact orientable 3-manifold $M$ is arc-extendible if there is an arc $γ$ on $\partial M - $ Int $F$ such that $F \cup N(γ)$ is incompressible, where $N(γ)$ is a regular neighborhood of $γ$ in $\partial M$. Suppose for simplicity that $M$ is irreducible, and $F$ has no disk components. If $M$ is a product $

Elisabeth Werner

Let $K$ be a convex body in ${\bf R}^n$ and $B$ be the Euclidean unit ball in ${\bf R}^n$. We show that $$\mbox{lim}_{t\rightarrow 0} \frac{|K| -|K_t|}{|B| - |B_t|}= \frac{as(K)}{as(B)},$$ where $as(K)$ respectively $as(B)$ is the affine surface area of $K$ respectively $B$ and $\{K_t\}_{t\geq 0}$, $\{B_t\}_{t\geq 0}$ are general families of convex bodies co

Matthias Blau, George Thompson

Euclidean supersymmetric theories are obtained from Minkowskian theories by performing a reduction in the time direction. This procedure elucidates certain mysterious features of Zumino&#39;s N=2 model in four dimensions, provides manifestly hermitian Euclidean counterparts of all non-mimimal SYM theories, and is also applicable to supergravity theories. We

Martin Schaden, Alexander Rozenberg

We examine the weak coupling limit of Euclidean SU(n) gauge theory in covariant gauges. Following an earlier suggestion, an equivariant BRST-construction is used to define the continuum theory on a finite torus. The equivariant gauge fixing introduces constant ghost fields as moduli of the model. We study the parameter- and moduli- space perturbatively. For

M. T. Grisaru, M. Massar, A. Sevrin, J. Troost

We consider a general N=(2,2) non-linear sigma-model in (2,2) superspace. Depending on the details of the complex structures involved, an off-shell description can be given in terms of chiral, twisted chiral and semi-chiral superfields. Using superspace techniques, we derive the conditions the potential has to satisfy in order to be ultra-violet finite at on

Ioseph Buchbinder, Ahmed Hindawi, Burt A. Ovrut

A two-form formulation for the N=2 vector-tensor multiplet is constructed using superfield methods in central charge superspace. The N=2 non-Abelian standard supergauge multiplet in central charge superspace is also discussed, as is with the associated Chern-Simons form. We give the constraints, solve the Bianchi identities and present the action for a theor

D. Pocanic, E. Frlez

pi-N and pi-pi interactions near threshold are uniquely sensitive to the chiral symmetry breaking part of the strong interaction. The pi-N sigma-term value with its implications for nucleon quark structure and the recent controversy concerning the size of the scalar quark condensate have renewed the experimental interest in these two fundamental systems. We

Vittorio Del Duca

We summarize the state of the art of resummation techniques in the small-$x$ limit of perturbative QCD.

G. Hellstern, R. Alkofer, H. Reinhardt

In a Nambu-Jona-Lasinio model supplemented with an infrared cutoff in addition to the ultraviolet cutoff we study the issue whether diquarks are confined when the model is extended beyond the rainbow-ladder approximation. The gap equation, obtained in a truncation scheme motivated via a nontrivial quark-gluon vertex function, is solved to determine the const

Robin G. Stuart

It is shown how to construct exactly gauge-invariant S-matrix elements for processes involving unstable gauge particles such as the $Z^0$ boson. The results are applied to derive a physically meaningful expression for the cross-section $σ(e^+e^-\to Z^0Z^0)$ and thereby provide a solution to the long-standing problem of the unstable particle.

Eugene Golowich

To provide focus to my review of charm theory at the B-Physics and CP-Violation conference, I consider theoretical issues related to possible charm studies at B-factories. A few topics of interest to the author are stressed -- rare decays, CP-violating asymmetries and ${\bar D}^0 - D^0$ mixing.

Alan R. White

If dynamical electroweak symmetry breaking is due to a flavor doublet of color sextet quarks, enhanced electroweak scale QCD instanton interactions may produce a large top mass, raise the $η_6$ axion mass, and also explain the excesses in the DIS cross-section at HERA and jet cross-sections at the Tevatron.

Osamu Yasuda

Using the published Kamiokande binned data for sub-GeV and multi-GeV atmospheric neutrinos, we have searched for the optimum set of three flavor neutrino oscillation parameters within the constraints of reactor experiments. It is found that chi^2 is minimized for (Delta m_{21}^2, Delta m_{32}^2, theta_{12}, theta_{13}, theta_{23}) = (7.4x10^{-1} eV^2, 2.6x 1

S. Frixione

I illustrate a general formalism based upon the subtraction method for the calculation of next-to-leading order QCD cross sections for any number of jets in any type of hard collisions. I discuss the implementation of this formalism in a numerical program which generates partonic kinematical configurations with an appropriate weight, thus allowing the defini

Massimo Pietroni

I describe an application of Wilson Renormalization group to the real time formalism of finite temperature field theory. The approach has two nice features: 1) the RG flow equations describe non-perturbatively the effect of thermal fluctuations only, and, 2) the flow is gauge invariant. I then describe the application of the method to the study of the gluon

Frank E. Close, Andrew Kirk

The application of our glueball-qqbar filter to the centrally produced KKbarpi system shows that the f1(1285) and f1(1420) have the same behaviour; namely consistent with the f1(1420) being the partner to the f1(1285) in the 3P1 nonet of axial mesons. We determine a flavour singlet-octet mixing angle of approximately 50 degrees for this nonet and highlight t

Sourendu Gupta, Prakash Mathews

We study doubly polarised asymmetries of c-cbar and b-bbar mesons in hadro- and photo-production at low transverse momentum in non-relativistic QCD to high orders in the relative velocity of the pair, v. We give the complete set of expressions required for the asymmetries up to order v^9. The asymmetries in the production of eta_{c,b} states are a stable mea

Z. Bern, P. Gondolo, M. Perelstein

We compute the annihilation cross-section of two neutralinos at rest into two photons, which is of importance for the indirect detection of neutralino dark matter in the galactic halo through a quasi-monochromatic gamma-ray line. We include all diagrams to one-loop level in the minimal supersymmetric extension of the standard model. We use the helicity forma

D. Norman

We present in this paper the current status of searches for leptoquarks at D0. These results include the use of next leading order theoretical predictions for the cross section for pair production of leptoquarks at hadron colliders. We also present a new optimized analysis for first generation leptoquarks with significant increase in sensitivity relative to

M. P. Sarachik, D. Simonian, S. V. Kravchenko, S. Bogdanovich

The zero-temperature magnetoconductivity of just-metallic Si:P scales with magnetic field, H, and dopant concentration, n, lying on a single universal curve. We note that Si:P, Si:B, and Si:As all have unusually large magnetic field crossover exponents near 2, and suggest that this anomalously weak response to a magnetic field is a common feature of uncompen

P. Monthoux

We consider an expansion of the ground state wavefunction of quantum lattice many-body systems in a basis whose states are tensor products of block-spin wavefunctions. We demonstrate by applying the method to the antiferromagnetic spin-1/2 chain that by selecting the most important many-body states the technique affords a severe truncation of the Hilbert spa

G. Vignale, C. A. Ullrich, S. Conti

In the current density functional theory of linear and nonlinear time-dependent phenomena, the treatment of exchange and correlation beyond the level of the adiabatic local density approximation is shown to lead to the appearance of viscoelastic stresses in the electron fluid. Complex and frequency-dependent viscosity/elasticity coefficients are microscopica

Serge Galam, Alain Mauger

In a recent paper, we have reported a universal power law for both site and bond percolation thresholds in any Bravais lattice with q equivalent nearest neighbors in dimension d. We now extend it to three different classes of lattices which are, respectively, anisotropic lattices whith not equivalent nearest neighbors, non-Bravais lattices with two atom unit

Torsten Henning, D. B. Haviland, P. Delsing

Niobium thin film wires were fabricated using electron beam lithography with a four layer liftoff mask system, and subsequently thinned by anodisation. The resistance along the wire was monitored in situ and trimmed by controlling the anodisation voltage. Depending on the room temperature sheet resistance, samples showed either superconducting or insulating

F. C. Alcaraz, R. Z. Bariev

A new generalization of the t-J model with a nearest-neigbour hopping is formulated and solved exactly by the Bethe-ansatz method in the thermodymanic limit. The model describes the dymanics of fermions with different spins and with isotropic and anisotropic interactions.

D. J. J. Farnell, S. E. Krueger, J. B. Parkinson

We study quantum spin systems in the 1D, 2D square and 3D cubic lattices with nearest-neighbour XY exchange. We use the coupled-cluster method (CCM) to calculate the ground-state energy, the T=0 sublattice magnetisation and the excited state energies, all as functions of the anisotropy parameter $γ$. We consider $S=1/2$ in detail and give some results for hi

C. Meyers, Y. Meurdesoif, Y. Leroyer, O. Kahn

We analyse a specific two dimensional mixed spin Heisenberg model with exchange anisotropy, by means of high temperature expansions and Monte Carlo simulations. The goal is to describe the magnetic properties of the compound (NBu_{4})_{2}Mn_{2}[Cu(opba)]_{3}\cdot 6DMSO\cdot H_{2}O which exhibits a ferromagnetic transition at $T_{c}=15K$. Extrapolating our an

B. Chopard, M. Droz, J. Magnin, Z. Racz

The A+B --> C reaction-diffusion process is studied in a system where the reagents are separated by a semipermeable wall. We use reaction-diffusion equations to describe the process and to derive a scaling description for the long-time behavior of the reaction front. Furthermore, we show that a critical localization-delocalization transition takes place as a

O. Cepas, J. Kurchan

We present a canonically invariant form for the generalized Langevin and Fokker-Planck equations. We discuss the role of constants of motion, and the construction of conservative stochastic processes.

N. V. Brilliantov, J. P. Valleau, C. Bagnuls, C. Bervillier

We indicate that Coulombic systems could correspond to Wilson effective Hamiltonians similar to that of the ordinary (nonionic) fluids but with a negative $ϕ^4$-coefficient. In that case, solving the ``exact&#39;&#39; renormalization group equation in the local potential approximation, we show that close initial Hamiltonians may lead either to a first order

Ph. Ghosez, X. Gonze, J. -P. Michenaud

The phonon dispersion curves of cubic BaTiO_3 have been computed within a first-principles approach and the results compared to the experimental data. The curves obtained are very similar to those reported for KNbO_3 by Yu and Krakauer [Phys. Rev. Lett. 74, 4067 (1995)]. They reveal that correlated atomic displacements along <100> chains are at the origin of

Jacek Miekisz

We constructed an uncountable family of classical lattice-gas models with unique ground-state measures which are not uniquely ergodic measures of any tiling system, or more generally, of any system of finite type. Therefore, we have shown that the family of structures which are unique ground states of some translation-invariant, finite-range interactions is

Boris A. Ivanov, Alexei K. Kolezhuk

Theoretical foundations of the problem of quantum spin tunneling in magnetic nanostructures are presented. Several model problems are considered in detail, including recent new results on tunneling in antiferromagnetic nanoparticles and topologically nontrivial magnetic structures in systems with reduced dimension.

George Kirczenow, Brad L. Johnson, P. J. Kelly, C. Gould

We explain the experimentally observed Aharonov-Bohm (AB) resonance patterns of an antidot cluster by means of quantum and classical simulations and Feynman path integral theory. We demonstrate that the observed behavior of the AB period signals the crossover from a low B regime which can be understood in terms of electrons following classical orbits to an i

Ulf Hermjakob

We propose a system for parsing and translating natural language that learns from examples and uses some background knowledge. As our parsing model we choose a deterministic shift-reduce type parser that integrates part-of-speech tagging and syntactic and semantic processing. Applying machine learning techniques, the system uses parse action examples acquire

Hector Giacomini, Sebastien Neukirch

In this paper, we study the bifurcation of limit cycles in Lienard systems of the form dot(x)=y-F(x), dot(y)=-x, where F(x) is an odd polynomial that contains, in general, several free parameters. By using a method introduced in a previous paper, we obtain a sequence of algebraic approximations to the bifurcation sets, in the parameter space. Each algebraic

Markus Kissler-Patig, Tom Richtler, Jesper Storm, Massimo Della Valle

We investigated the globular cluster system of the S0 galaxy NGC 1380 in the Fornax cluster with deep BVR photometry. We identified two, presumably old, populations of globular clusters. The blue globular clusters seem to be counterparts to the halo globular clusters in our Milky Way. They have comparable colors and magnitudes, are spherically distributed ar

J. Perea, A. del Olmo, L. Verdes-Montenegro, M. S. Yun

Through the study of a carefully selected sample of isolated spiral galaxies, we have established that two important global physical quantities for tracing star forming activities, L(FIR) and M(H2), have non-linear dependence on another commonly cited global quantity L(B). Furthermore we show that simple power law relations can effectively describe these non

Gregory A. Shields

Novae have been proposed as the explanation of high reported abundances of heavy elements in the gas producing the broad absorption lines (BALs) of QSOs. High abundances of odd numbered elements, including aluminum, are predicted. Available data contains hints that the Al/Si ratio may be high both in the BAL gas and in the broad emission-line gas.

Elena Pian, C. Megan Urry, Aldo Treves, Laura Maraschi

PKS 2155-304, the brightest BL Lac object in the ultraviolet sky, was monitored with the IUE satellite at ~1 hour time-resolution for ten nearly uninterrupted days in May 1994. The campaign, which was coordinated with EUVE, ROSAT, and ASCA monitoring, along with optical and radio observations from the ground, yielded the largest set of spectra and the riches

Luis Masperi, Guillermo Silva

The flux of high energy cosmic rays coming from the decay of vortons is estimated. If the abundance of loops corresponding to a superconductivity scale coincident with that of the string formation is corrected to be compatible with the critical density of universe, it is found that the emission of one carrier per vorton may produce a flux of one cosmic ray e

Gerald D. Quinlan, Lars Hernquist

We use a hybrid N-body program to study the evolution of massive black hole binaries in the centers of galaxies, mainly to understand the factors affecting the binary eccentricity, the response of the galaxy to the binary merger, and the effect of loss-cone depletion on the merger time. The scattering experiments from paper I showed that the merger time is n

R. Scaramella, E. Cascone, F. Cortecchia, R. S. Ellis

We present the concept and preliminary design of the Galileo OH Subtracted Spectrograph [GOHSS], a multifibre NIR spectrograph for faint objects. The instrument represents a collaboration between the Institute of Astronomy, Cambridge and the Observatories of Naples and Rome and will be a second-light instrument for the 3.6m Galileo telescope located on La Pa

Martin G. Haehnelt, Matthias Steinmetz

The Doppler parameter distribution of Lyman-alpha absorption is calculated for a set of different reionization histories. The differences in temperature between different reionization histories are as large as a factor three to four depending on the spectrum of the ionizing sources and the redshift of helium reionization. These temperature differences result

M. Montuori, F. Sylos-Labini

We study the angular correlations of various galaxy catalogs (CfA1, SSRS1, Perseus-Pisces, APM Bright Galaxies and Zwicky). We find that the angular correlation exponent is $γ_a= 0.1 \pm 0.1$ rather than $γ_a=0.7$ as usually found by the standard correlation function $ω(θ)$. We identify the problem in the artificial decay of $ω(θ)$. Moreover we find that no

T. Rauscher, F. -K. Thielemann, K. -L. Kratz

The prediction of cross sections for nuclei far off stability is crucial in the field of nuclear astrophysics. We discuss the model mostly employed for such calculations: the statistical model (Hauser-Feshbach). Special emphasis is put on the uncertainties arising from nuclear level density descriptions and an improved global description is presented. Furthe

Michael Feast, Patricia Whitelock

The Hipparcos proper motions of 220 galactic Cepheids, together with relevant ground-based photometry, have been analysed. The effects of galactic rotation are very clearly seen. Mean values of the Oort constants, A = 14.82 +/- 0.84 km/s/kpc, and B = -12.37 +/- 0.64 km/s/kpc, and of the angular velocity of circular rotation at the Sun, Omega_0 = 27.19 +/- 0.

C. Alcock, R. A. Allsman, D. R. Alves, T. S. Axelrod

We measure the zero point of the Stanek (1996) extinction map by comparing the observed (V-K) colors of 20 RR Lyrae stars (type ab) found in the MACHO survey with their intrinsic (V-K)_0 colors as a function of period as determined from nearby RR Lyrae stars. We find that the zero point of the Stanek map should be changed by ΔA_V = -0.11 +/- 0.05 mag, in exc

Karsten Jedamzik, Jason X. Prochaska

We employ observationally determined intrinsic velocity widths and column densities of damped Lyman-alpha systems at high redshift to investigate the distribution of baryons in protogalaxies within the context of a standard cold dark matter model. We proceed under the assumption that damped Lyman alpha systems represent a population of cold, rotationally sup

James T. Wheeler

A new 8-dimensional conformal gauging avoids the unphysical size change, third order gravitational field equations, and auxiliary fields that prevent taking the conformal group as a fundamental symmetry. We give the structure equations, gauge transformations and intrinsic metric structure for the new biconformal spaces. We prove that a torsion-free biconform

James T. Wheeler

A new 8-dim conformal gauging solves the auxiliary field problem and eliminates unphysical size change from Weyl&#39;s electromagnetic theory. We derive the Maurer-Cartan structure equations and find the zero curvature solutions for the conformal connection. By showing that every one-particle Hamiltonian generates the structure equations we establish a corre

A. Kempf

We study functional analytic aspects of two types of correction terms to the Heisenberg algebra. One type is known to induce a finite lower bound $Δx_0$ to the resolution of distances, a short distance cutoff which is motivated from string theory and quantum gravity. It implies the existence of families of self-adjoint extensions of the position operators wi

Stanislaw D. Glazek

We outline an ultraviolet renormalization procedure for hamiltonians acting in the light-front Fock space. The hamiltonians are defined and calculated using creation and annihilation operators with no limitation of the space of states. Both, the regularization of the initial hamiltonian and the definition of the renormalized effective hamiltonians, preserve

N. Z. Scoville, M. S. Yun, R. A. Windhorst, W. C. Keel

We report a sensitive search for redshifted CO (3-2) emission from the weak radio galaxy 53W002 at z=2.394. Maps at resolutions of 3 arcsec and 235km/s show a significant emission peak within 0.5 arcsec of the optical and radio continuum peaks. The measured narrow band flux is approximately ten times the extrapolated cm-wavelength non-thermal radio continuum

Zong-Hong Zhu, Xiang-Ping Wu, Li-Zhi Fang

The theoretically expected amplitude of the associations of background quasars with foreground galaxies as a result of gravitational lensing has been updated in this paper. Since the galactic matter alone yields an amplitude of quasar overdensity smaller than that observed, a special attention has been paid to the examination or re-examination of the uncerta

G. D. Lythe, M. R. E. Proctor

Recent research on the dynamics of certain fluid dynamical instabilities shows that when there is a slow invariant manifold subject to fast timescale instability the dynamics are extremely sensitive to noise. The behaviour of such systems can be described in terms of a one-dimensional map, and previous work has shown how the effect of noise can be modelled b

Kyungsik Kang, Sin Kyu Kang, Jihn E. Kim, Pyungwon Ko

We suggest mass matrices for neutrinos and charged leptons that can explain solar and atmospheric neutrino data. The resulting flavor mixing matrix $V_ν$ has a property that $(V_ν)_{13}=0$, thus making $ν_e \leftrightarrow ν_μ$ and $ν_μ \leftrightarrow ν_τ$ oscillations to be effectively a two-channel problem. Phenomenological consequences of the lepton mass

V. N. Soshnikov

We propose a new and effective method to find plasma oscillatory and wave modes. It implies searching a pair of poles of two-dimensional (in coordinate $x$ and time $t$) Laplace transform of self-consistent plasma electric field $E(x,t) \to E_{p_1p_2}$, where $p_1 \equiv -i ω$, $p_2 \equiv i k$ are Laplace transform parameters, that is determining a pair of

B. Abdesselam, A. Chakrabarti, R. Chakrabarti

A class of transformations of $R_q$-matrices is introduced such that the $q\to 1$ limit gives explicit nonstandard $R_{h}$-matrices. The transformation matrix is singular itself at $q\to 1$ limit. For the transformed matrix, the singularities, however, cancel yielding a well-defined construction. Our method can be implemented systematically for R-matrices of

K. Hagino, N. Takigawa, M. Dasgupta, D. J. Hinde

The effects of higher order coupling of surface vibrations to the relative motion on heavy-ion fusion reactions at near-barrier energies are investigated. The coupled channels equations are solved to all orders, and also in the linear and the quadratic coupling approximations. It is shown that the shape of fusion barrier distributions and the energy dependen

N. Takigawa, K. Hagino, S. Kuyucak

Describing fusion reactions between ^{16}O and ^{154}Dy and, between ^{16}O and ^{144}Sm by the $sd-$ and $sdf-$ interacting boson model, we show that heavy-ion fusion reactions are strongly affected by anharmonic properties of nuclear surface vibrations and nuclear shape, and thus provide a powerful method to study details of nuclear structure and dynamics.

I. Antoniadis, H. Partouche, T. R. Taylor

We present a review of heterotic-type I string duality. In particular, we discuss the effective field theory of six- and four-dimensional compactifications with N>1 supersymmetries. We then describe various duality tests by comparing gauge couplings, N=2 prepotentials, as well as higher-derivative F-terms. Based on invited lectures delivered at: 33rd Karpacz

E. Di Salvo, M. M. Musakhanov

A low energy theorem concerning a matrix element of the QCD axial anomaly between vacuum and two-photons states is tested against different instanton models. In the chiral limit the theorem is fulfilled by the Diakonov&Petrov model, whereas it is violated by single-instanton approximations. Beyond the chiral limit the theorem, and two relations established f

Debajyoti Choudhury, Sreerup Raychaudhuri, K. Sridhar

We interpret the reported disagreement between the measured ratio, R_{10}, of the W + 1 jet cross-section to the W + 0 jet cross-section at the Tevatron and the Standard Model (SM) prediction, as the effect of interactions mediated by a colour-octet analogue of the W-boson, the W_8. The presence of a W_8 with mass O(300) GeV, and with couplings to quarks and

A. L. Kataev, A. V. Kotikov, G. Parente, A. V. Sidorov

We present the results of the next-to-next-to-leading order QCD analysis of the recently revised experimental data of the CCFR collaboration for the $xF_3$ structure function using the Jacobi polynomial expansion method. The effects of the higher twist contributions are included into the fits following the infrared renormalon motivated model. The special att

C. J. A. P. Martins, E. P. S. Shellard

We extend the quantititative string evolution model of Martins and Shellard to superconducting strings by introducing a simple toy model for the evolution of the currents. This is based on the dynamics of a `superconducting correlation length&#39;. We derive the relevant evolution equations and discuss the importance of plasma effects. Some consequences of o

Guo-Hong Wu

Measurements of the polarization of the lepton and D* in the exclusive semileptonic B decays, B to D l nu and B to D* l nu, can be used to separate and identify the non-standard model sources of T violation. These T-odd effects, estimated in both supersymmetric and non-supersymmetric models, could be within the reach of the planned B factories.

Sasha Dukan, Zlatko Tesanovic

We have calculated the density of states $N(ω)$ of a dirty but homogeneous superconductor in a high magnetic field. We assume a dilute concentration of scalar impurities and find how $N(ω)$ behaves as one crosses from the weak scattering to the strong scattering limit. At low energies, $N(ω)\sim ω^2$ for small values of the impurity concentration and scatter

Takashi Kimura, Kazuhiko Kuroki, Hideo Aoki

In order to shed light whether the `even-odd conjecture&#39; (even numbers of legs will superconduct accompanied by a spin gap while odd ones do not) for correlated electrons in ladder systems, the pairing correlation is studied for the Hubbard model on a two- and three-leg ladders. We have employed both the weak-coupling renormalization group and the quantu

John C. L. Wang

The unidentified X-ray source RX J0720.4-3125 is a candidate isolated neutron star showing evidence for pulsed emission with an 8.39 s period and a spectrum consistent with a blackbody at kT=80 eV (Haberl et al. 1996, 1997). We show that this source is most likely an old isolated neutron star accreting from surrounding media. We then argue that unless it was

Hyun-Chul Kim, Michał Praszałowicz, Klaus Goeke

Magnetic moments of baryons are studied within the chiral quark soliton model with special emphasis on the decuplet of baryons. The model is used to identify all symmetry breaking terms proportional to $m_{\rm s}$. Sum rules for the magnetic moments are derived. A ``model-independent&#39;&#39; analysis of the symmetry breaking terms is performed and finally

G. Amelino-Camelia, J. D. Bjorken, S. E. Larsson

We study the various stages of the evolution of chiral condensates disoriented via the ``baked-alaska&#39;&#39; mechanism, in which the condensates are described as the products of external sources localized on the light cone. Our analysis is based on the classical equations of motion of either the linear or the nonlinear sigma model. We use the associated f

Lynne H. Orr, W. J. Stirling

The production in high-energy hadron collisions of a pair of jets with large rapidity separation is studied in an improved BFKL formalism. By recasting the analytic solution of the BFKL equation as an explicit order-by-order sum over emitted gluons, the effects of phase space constraints and the running coupling are studied. Particular attention is paid to t

D. S. Berman

We reformulate the Born-Infeld action, coupled to an axion and a dilaton in a duality manifest way. This action is the generalization of the Schwarz-Sen action for non-linear electrodynamics. We show that this action may be obtained by dimensional reduction on a torus of a self-dual theory in 6 dimensions. The dilaton-axion being identified with the complex

G. W. Gibbons, G. Papadopoulos, K. S. Stelle

We consider Shiraishi&#39;s metrics on the moduli space of extreme black holes. We interpret the simplification in the pattern of N-body interactions that he observed in terms of the recent picture of black holes in four and five dimensions as composites, made up of intersecting branes. We then show that the geometry of the moduli space of a class of black h

H. -P. Pavel, D. Blaschke, V. N. Pervushin, G. Roepke

The relation between the large mass of the $η&#39;$ and the structure of the gluon vacuum via the $U_A(1)$ anomaly is discussed. A squeezed gluon vacuum is considered as an alternative to existing models. Considering Witten&#39;s formula for the $η_0$ mass we show that the contact term can give a sizable contribution and relate it to the physical gluon conde

Amand Faessler, M. I. Krivoruchenko, B. V. Martemyanov

We consider the thermodynamics of the matter made up of equal number of neutrons and protons and of scalar dibaryons. They interact via the exchange of scalar and vector mesons. The interaction is taken into account in the mean field approximation. The condensation of dibaryons in this matter and the phase transition of matter to quark matter are considered.

David P. DiVincenzo, Peter W. Shor, John A. Smolin

We present a family of additive quantum error-correcting codes whose capacities exceeds that of quantum random coding (hashing) for very noisy channels. These codes provide non-zero capacity in a depolarizing channel for fidelity parameters $f$ when $f> .80944$. Random coding has non-zero capacity only for $f>.81071$; by analogy to the classical Shannon codi