September 1999 arXiv papers — page 3

M. Traving, C. Kreis, R. Adelung, L. Kipp

Cluster research so far only dealt with either 3D free clusters or clusters on substrates with strong electronic coupling at the interface. Preparation of free and orientated 2D clusters is usually not possible because one of these conditions generally excludes the other. We demonstrate a new way to grow 2D clusters of transition metal dichalcogenides which

Vadim Ponomarenko, Naoto Nagaosa

A low energy crossover (see cond-mat/9711167) induced by Fermi liquid reservoirs in transport through a 1D Mott-Hubbard insulator of finite length $L$ is examined in the presence of impurity pinning. Under the assumption that the Hubbard gap 2M is large enough: $M > T_L \equiv v_c/L$ ($v_c$: charge velocity in the wire) and the impurity backscattering rate $

Tae-Hyoung Gimm, Sung-Ho Suck Salk

We investigate the phase diagram of phase separation for the hole-doped two dimensional system of antiferromagnetically correlated electrons based on the U(1) slave-boson functional integral approach to the t-J model. We show that the phase separation occurs for all values of J/t, that is, whether $0 < J/t < 1$ or $J/t \geq 1$ with J, the Heisenberg coupling

L. Braginsky

The generalized boundary conditions for the envelope wave function that take into account the real structure of an interface were used to investigate the hole spectrum of the semiconductor quantum dot embedded in an insulator matrix. An essential influence of the interface levels, which could exist at the top of the valence band, on the hole spectrum has bee

Zhou Haijun, Ou-Yang Zhong-can

The folding angle distribution of stretched and negatively supercoiled DNA double-helix is investigated based on a theoretical model we proposed earlier [H. Zhou et al., Phys. Rev. Lett. 82, 4560 (1999)]. It is shown that pulling can transit a negatively supercoiled DNA double-helix from the right-handed B-form to a left-handed configuration which resembles

A. Celani, A. Lanotte, A. Mazzino, M. Vergassola

The statistical properties of a scalar field advected by the non-intermittent Navier-Stokes flow arising from a two-dimensional inverse energy cascade are investigated. The universality properties of the scalar field are directly probed by comparing the results obtained with two different types of injection mechanisms. Scaling properties are shown to be univ

J. A. Panei, L. G. Althaus, O. G. Benvenuto

The purpose of this work is to present accurate and detailed mass-radius relations for white dwarf (WD) models with helium, carbon, oxygen, silicon and iron cores, by using a fully updated stellar evolutionary code. We considered masses from 0.15 to 0.5 Mo for the case of helium core, from 0.45 to 1.2 Mo for carbon, oxygen and silicon cores and from 0.45 to

Menas Kafatos, Prasad Subramanian

We examine here the inner region accretion flows onto black holes. A variety of models are presented. We also discuss viscosity mechanisms under a variety of circumstances, for standard accretion disks onto galactic black holes and supermassive black holes and hot accretion disks. Relevant work is presented here on unified aspects of disk accretion onto supe

J. L. Sanz, R. B. Barreiro, L. Cayon, E. Martinez-Gonzalez

We consider the 2D wavelet transform with two scales to study sky maps of temperature anisotropies in the cosmic microwave background radiation (CMB). We apply this technique to simulated maps of small sky patches of size 12.8 \times 12.8 square degrees and 1.5&#39; \times 1.5&#39; pixels. The relation to the standard approach, based on the cl&#39;s is estab

L. Spinoglio, T. Giannini, B. Nisini, M. E. van den Ancker

The first complete far-infrared spectrum of T Tau has been obtained with the LWS spectrometer on-board the Infrared Space Observatory, which detected strong emission from high-J (J=14-25) CO, para- and ortho-H2O and OH transitions over the wavelength range from 40 to 190 micron. Most of the observed molecular emission can be explained by a single emission re

Enrique Perez, Isabel Marquez, Ignacio Marrero, Florence Durret

A study is presented of the central structure and kinematics of the galaxy NGC 6951, by means of broad band B&#39;IJK images and high resolution high dispersion longslit spectroscopy, together with archival HST WFPC2 V and NICMOS2 J and H images. We find that there is evidence of two modes of star formation, in bursts and continuously. The equivalent width o

Claire J. Chandler, John S. Richer

High dynamic range imaging of submillimeter dust emission from the envelopes of eight young protostars in the Taurus and Perseus star-forming regions has been carried out using the SCUBA submillimeter camera on the James Clerk Maxwell Telescope. Good correspondence between the spectral classifications of the protostars and the spatial distributions of their

A. Aparicio, N. Tikhonov, I. Karachentsev

If dwarf galaxies are primeval objects in the Universe, as hierarchical galaxy formation scenarios predict, they should show traces of their old stellar populations, perhaps distributed in extended, differentiated structures. The working hypothesis that such a structure could exist is tested for the case of DDO 187, a field dIrr galaxy showing a high gas fra

A. I. Diaz, E. Perez-Montero

We present an empirical calibration of nebular abundances based on the strong emission lines of [SII] and [SIII] in the red part of the spectrum through the definition of a sulphur abundance parameter S23. This calibration presents two important advantages against the commonly used one based on the optical oxygen lines: it remains single-valued up to abundan

F. Favata, F. Reale, G. Micela, S. Sciortino

We present a long (150 ks elapsed time) ASCA X-ray observation of the dM3.5e star EV Lac, during which an exceptionally intense flaring event (lasting approximately 12 ks) was observed: at the flare&#39;s peak, the X-ray count rate in the ASCA GIS detectors was approx. 300 times the quiescent value. The physical parameters of the flaring region have been der

Yvonne Simis, Carsten Dominik, Vincent Icke

We have developed an implementation for the momentum transfer force in numerical two fluid hydrodynamics. This form of the frictional coupling between gas and grains is consistent with the microscopic interactions between the two components. The coupling force gives rise to a drift velocity of the grains with respect to the gas. We apply this mechanism to th

J. A. Sellwood

Having once thought that we understood how some galaxies were barred and had difficulty accounting for the absence of bars in others, it now seems that we have the opposite problem. Most real galaxies have centres dense enough to inhibit bar formation, even if they have massive discs. This is also true for barred galaxies, which therefore could not have acqu

A. K. H. Kong, L. Homer, E. Kuulkers, P. A. Charles

We report results from the first simultaneous X-ray (RXTE) and optical (SAAO) observations of the low-mass X-ray binary GS 1826-24 in June 1998. A type-I burst was detected in both X-ray and optical wavelengths. Its energy-dependent profile, energetics and spectral evolution provide evidence for an increase in the X-ray but not fpr photospheric radius expans

Idit Zehavi, Avishai Dekel

The power spectrum of mass density fluctuations is evaluated from the Mark III and the SFI catalogs of peculiar velocities by a maximum likelihood analysis, using parametric models for the power spectrum and for the errors. The applications to the two different data sets, using generalized CDM models with and without COBE normalization, give consistent resul

Richard P. Nelson, John C. B. Papaloizou, F. Masset, Willy Kley

We investigate the gravitational interaction of a Jovian mass protoplanet with a gaseous disc with aspect ratio and kinematic viscosity expected for the protoplanetary disc from which it formed. Different disc surface density distributions have been investigated. We focus on the tidal interaction with the disc with the consequent gap formation and orbital mi

R. X. Xu, G. J . Qiao, B. Zhang

Similar to the terrestrial collision accelerators of electron-antielectron, another kind of accelerator is above a positively or negatively charged pulsar polar cap. In the case of pulsars with magnetic axis parallel (anti-parallel) to rotational axis, relativistic antielectron (electron) with Lorentz factor about 10^6 hit the electrons in the polar caps. Th

R. X. Xu, G. J, . Qiao, B. Zhang

It is believed that pulsars are neutron stars or strange stars with crusts. However we suggest here that pulsars may be bare strange stars (i.e., strange stars without crust). Due to rapid rotation and strong emission, young strange stars produced in supernova explosions should be bare when they act as radio pulsars. Because of strong magnetic field, two pol

M. Beijersbergen, W. J. G. de Blok, J. M. van der Hulst

We present results of broad band {BVRI} observations of a sample of galaxies with a low surface brightness (LSB) disk and a bulge. These galaxies are well described as exponential disks and exponential bulges with no preferred value for either scale length or central surface brightness. The median {B} band disk scale length is 12.6 kpc (H_(0) = 75 km s^{-1}

G. Maubon, Ph. Prugniel

We have studied the population-density relation in very sparse environments, from poor clusters to isolated galaxies, and we find that early-type galaxies with a young stellar population are preferably found in the lowest density environments. We show a marginal indication that this effect is due to an enhancement of the stellar formation independent of the

J. Hwang, H. Noh

A generic form of low-energy effective action of superstring theories with one-loop quantum correction is well known. Based on this action we derive the complete perturbation equations and general analytic solutions in the cosmological spacetime. Using the solutions we identify conserved quantities characterizing the perturbations: the amplitude of gravitati

Christopher D. Matzner, Christopher F. McKee

We demonstrate that magnetically-collimated protostellar winds will sweep ambient material into thin, radiative, momentum-conserving shells whose features reproduce those commonly observed in bipolar molecular outflows. We find the typical position-velocity and mass-velocity relations to occur in outflows in a wide variety of ambient density distributions, r

Andrew J. Bunker, Leonidas A. Moustakas, Marc Davis

We present deep near-infrared Keck/NIRC imaging of a recently-discovered z=4.04 galaxy (Frye & Broadhurst 1998). This is lensed by the rich foreground cluster Abell~2390 (z~0.23) into highly-magnified arcs 3-5arcsec in length. Our H- and K&#39;-band NIRC imaging allows us to map the Balmer+4000Ang break amplitude. In combination with high-quality archival HS

P. Valageas, J. Silk

Using a unified analytic model for quasars, galaxies, Lyman-alpha absorbers and the IGM, we obtain the redshift evolution of the temperature and the entropy of the gas and the corresponding cluster temperature - X-ray luminosity relation. We show that although quasars can easily reheat the IGM and raise its entropy up to the level required by current cluster

Akikazu Hashimoto, Koji Hashimoto

Taking advantage of the equivalence between supersymmetric Yang-Mills theory on non-commutative spaces and the field theory limit of D3-branes in the background of NSNS 2-form field, we investigate the static properties of magnetic monopoles and dyons using brane construction techniques. When parallel D3-branes are separated by turning on a Higgs vacuum expe

Gaetano Bertoldi, Alon E. Faraggi, Marco Matone

We show that the recently formulated Equivalence Principle (EP) implies a basic cocycle condition both in Euclidean and Minkowski spaces, which holds in any dimension. This condition, that in one-dimension is sufficient to fix the Schwarzian equation [6], implies a fundamental higher dimensional Moebius invariance which in turn univocally fixes the quantum v

Levon Pogosian, Tanmay Vachaspati

We study the interaction of magnetic monopoles and domain walls in a model with SU(5)\times Z_2 symmetry by numerically evolving the field equations. We find that the monopoles unwind and dissipate their magnetic energy on collision with domain walls within which the full SU(5) symmetry is restored.

Alan Chodos, Erich Poppitz

We study the solutions of the Einstein equations in (d+2)-dimensions, describing parallel p-branes (p=d-1) in a space with two transverse dimensions of positive gaussian curvature. These solutions generalize the solutions of Deser and Jackiw of point particle sources in (2+1)-dimensional gravity with cosmological constant. Determination of the metric is redu

S. Heinemeyer, W. Hollik, G. Weiglein

We investigate the possibilities for constraining tan beta within the MSSM by combining the theoretical result for the upper bound on the lightest Higgs-boson mass as a function of tan beta with the informations from the direct experimental search for this particle. We discuss the commonly used ``benchmark&#39;&#39; scenario, in which the parameter values m_

S. E. Derkachov, G. P. Korchemsky, A. N. Manashov

We study the scale dependence of the twist-3 quark-gluon parton distributions using the observation that in the multi-color limit the corresponding QCD evolution equations possess an additional integral of motion and turn out to be effectively equivalent to the Schrodinger equation for integrable open Heisenberg spin chain model. We identify the integral of

Thomas Dent

We investigate the stability of the hidden sector gaugino condensate in a SL(2,Z)-invariant supergravity model inspired by the E8*E8 heterotic string, using the chiral superfield formalism. We calculate the Planck-suppressed corrections to the ``truncated approximation&#39;&#39; for the condensate value and the scalar potential. A transition to a phase with

Darwin Chang, We-Fu Chang, Ernest Ma

The 1999 precision electroweak data from LEP and SLC persist in showing some slight discrepancies from the assumed standard model, mostly regarding $b$ and $c$ quarks. We show how their mixing with exotic heavy quarks could result in a more consistent fit of all the data, including two unconventional interpretations of the top quark.

P. Singha Deo, M. V. Moskalets

When a one dimensional (1D) ring-stub system is coupled to an electron reservoir, the states acquire a width (or broadening characterized by poles in the complex energy plane) due to finite life time effects. We show that this broadening is limited by anti-resonances due to the stub. The differences in level broadening in presence and absence of anti-resonan

Y. Durga Devi, Shadow Robinson, Larry Zamick

We find that the excitation energies of single analog states for odd-even nuclei in the f$_{7/2}$ shell with J=j=7/2$^{-}$ and the J=0$^{+}$ double analog states in the even-even nuclei are well described by the formulas $E^{*}(j,T+1) = b (T+X)$ and $E^{*}(0^{+},T+2) = 2b (T+X+0.5)$,respectively, where $T=\mid N-Z\mid /2$ is usually the ground state isospin.

Chih-Lung Chou, Michael E. Peskin

We study phenomenologically the scenario in which the scalar top quark is lighter than any other standard supersymmetric partner and also lighter than the top quark, so that it decays to the gravitino via stop -> W^+ b G. In this case, scalar top quark events would seem to be very difficult to separate from top quark pair production. However, we show that, e

G. Rosensteel, J. Troupe

The classical theory of Riemann ellipsoids is formulated naturally as a gauge theory based on a principal G-bundle ${\cal P}$. The structure group G=SO(3) is the vorticity group, and the bundle ${\cal P}=GL_+(3, R})$ is the connected component of the general linear group. The base manifold is the space of positive-definite real $3\times 3$ symmetric matrices

Ulrich Gerland, Jan von Delft, Theo Costi, Yuval Oreg

We study the effects of Kondo correlations on the transmission phase shift of a quantum dot in an Aharonov-Bohm ring. We predict in detail how the development of a Kondo resonance should affect the dependence of the phase shift on transport voltage, gate voltage and temperature. This system should allow the first direct observation of the well-known scatteri

Michel H. G. Tytgat

We consider QCD at Theta ~ Pi with two, one and zero light flavours Nf, using the Di Vecchia-Veneziano-Witten effective lagrangian. For Nf=2, we show that CP is spontaneously broken at Theta = Pi for finite quark mass splittings, z= Md/Mu \not= 1. In the z-Theta plane, there is a line of first order transitions at Theta = Pi with two critical endpoints, z1*

T. Bergfeld, CLEO Collaboration

Using 4.68 fb^{-1} of e^+e^- annihilation data collected with the CLEO II detector at the Cornell Electron Storage Ring (CESR) we have studied tau radiative decays tau -> mu nu nu gamma and tau -> e nu nu gamma. For a 10 MeV minimum photon energy in the tau rest frame, the branching fraction of radiative tau decay to a muon or electron is measured to be (3.6

Ph. Blanchard, A. Jadczyk, R. Olkiewicz

Departing from classical concepts of ergodic theory, formulated in terms of probability densities, measures describing the chaotic behavior and the loss of information in quantum open systems are proposed. As application we discuss the chaotic outcomes of continuous measurement processes in the EEQT framework. Simultaneous measurement of four noncommuting sp

Sergey N. Solodukhin

The recently proposed technique to regularize the divergences of the gravitational action on non-compact space by adding boundary counterterms is studied. We propose prescription for constructing the boundary counterterms which are polynomial in the boundary curvature. This prescription is efficient for both asymptotically Anti-de Sitter and asymptotically f

M. I. Levchuk, A. I. L&#39;vov

Deuteron Compton scattering below pion photoproduction threshold is considered in the framework of the nonrelativistic diagrammatic approach with the Bonn OBE potential. A complete gauge-invariant set of diagrams is taken into account which includes resonance diagrams without and with NN-rescattering and diagrams with one- and two-body seagulls. The seagull

Yuji Ohta

Instanton correction of prepotential of one-dimensional SL(2) Ruijsenaars model is presented with the help of Picard-Fuchs equation of Pakuliak-Perelomov type. It is shown that the instanton induced prepotential reduces to that of the SU(2) gauge theory coupled with a massive adjoint hypermultiplet.

Yu-Li Lee, Yu-Wen Lee

We study the effects of a uniform magnetic field on the one-dimensional spin-orbital model in terms of effective field theories. Two regions are examined: one around the SU(4) point (J=K/4) and the other with K<<J. We found that when $J\leq K/4$, the spin and orbital correlation functions exhibit power-law decay with nonuniversal exponents. In the region wit

J. Kluson

In this paper we would like to show simple mechanisms how from the action for non-BPS D-brane we can obtain action describing BPS D(p-1)-brane in Type IIA theory.

Yasuharu Honda, Masaki Yasue

Responding to the recent claim that the origin of moduli space may be unstable in &#34;magnetic&#34; supersymmetric quantum chromodynamics (SQCD) with N_f <= 3N_c/2 (N_c>2) for N_f flavors and N_c colors of quarks, we explore the possibility of finding nonperturbative physics for &#34;electric&#34; SQCD. We present a recently discussed effective superpotenti

Jizhong Lou, Shaojin Qin, Tai-Kai Ng, Zhaobin Su

We report our density matrix renormalization-group and analytical work on S=1 antiferromagnetic Heisenberg spin chains. We study the finite size behavior within the framework of the non-linear sigma model. We study the effect of magnon-magnon interactions on the finite size spectrum and on the magnetization curve close to the critical magnetic field, determi

Samir Salim, Andrew Gould

The Space Interferometry Mission (SIM) is the instrument of choice when it comes to observing astrometric microlensing events where nearby, usually high-proper-motion stars (``lenses&#39;&#39;), pass in front of more distant stars (``sources&#39;&#39;). Each such encounter produces a deflection in the source&#39;s apparent position that when observed by SIM

S. Dodelson, L. Knox

We find that current Cosmic Microwave Background (CMB) anisotropy data strongly constrain the mean spatial curvature of the Universe to be near zero, or, equivalently, the total energy density to be near critical-as predicted by inflation. This result is robust to editing of data sets, and variation of other cosmological parameters (totaling seven, including

A. A. Ketsaris

We develop an unified algebraic approach to the description of gauge interactions within the framework of a new concept of quantum mechanics. The next step in generalizing the space-time and the action vector space is made. The gauge field is defined through linear mappings in the generalized space-time and the action space. Relativistic quantum mechanics eq

Ph. Blanchard, A. Jadczyk, R. Olkiewicz

In the framework of Event Enhanced Quantum Theory (EEQT) a probabilistic construction of the piecewise deterministic process associated with a dynamical semigroup is presented. The process generates sample histories of individual systems quantums systems continuously coupled to classical measuring devices; it gives a unique algorithm generating time series o

Charles Francis

In &#34;A Theory of Quantum Space-time&#34; we constructed a form of field theory in which Feynman diagrams describe real particle interactions, not virtual ones. In this paper we outline a theory of discrete interactions based on hadron field operators which bind quark in co- ordinate space, but not momentum space, and offer explanations for the strong forc

Charles Francis

The k-calculus was advocated by Hermann Bondi as a means of explaining special relativity using only GCSE level mathematics and ideas. We review the central derivations, using proofs which are only a little more elegant than those in Bondi&#39;s books, and extend his development to include the scalar product and the mass shell condition. As used by Bondi, k

L. Tiator, D. Drechsel, S. S. Kamalov

We present predictions for the spin structure functions of the proton and the neutron in the framework of a unitary isobar model for one-pion photo- and electroproduction. Our results are compared with recent experimental data from SLAC. The first moments of the calculated structure functions fulfill the Gerasimov-Drell-Hearn and Burkhardt-Cottingham sum rul

V. Yu. Ponomarev

Correlation between B($E1, 1^-_1 \to 0^+_{g.s.}$) and B($E1, 3^-_1 \to 2^+_{1}$) values are considered within microscopic QRPA approach. General arguments for a dependence of a ratio between these values on a collectivity of the $2^+_1$ and $3^-_1$ phonons and ground state correlations are provided.

P. Narayana Swamy

Several examples are used to illustrate how we deal cavalierly with infinities and unphysical systems in physics. Upon examining these examples in the context of infinities from Cantor&#39;s theory of transfinite numbers, the only known mathematical theory of infinities, we conclude that apparent inconsistencies in physics are a result of unfamiliar and unus

S. P. Novikov

Topology of levels of the quasiperiodic functions with m=n+2 periods on the plane is studied. For the case of functions with m=4 periods full description is obtained for the open everywhere dense family of functions. This problem is equivalent to the study of Hamiltonian systems on the (n+2)-torus with constant rank 2 Poisson bracket. In the cases under inve

P. T. Leung, Alec Maassen van den Brink, W. M. Suen, C. W. Wong

Quasinormal modes are the counterparts in open systems of normal modes in conservative systems; defined by outgoing-wave boundary conditions, they have complex eigenvalues. The conditions are studied for a system to have a supersymmetric(SUSY) partner with the same complex quasinormal-mode spectrum (or the same except for one eigenvalue). The discussion natu

Alexander R. Its, Craig A. Tracy, Harold Widom

It is proved that the limiting distribution of the length of the longest weakly increasing subsequence in an inhomogeneous random word is related to the distribution function for the eigenvalues of a certain direct sum of Gaussian unitary ensembles subject to an overall constraint that the eigenvalues lie in a hyperplane.

Diane Maclagan

The main result of this paper is that all antichains are finite in the poset of monomial ideals in a polynomial ring, ordered by inclusion. We present several corollaries of this result, both simpler proofs of results already in the literature and new results. One natural generalization to more abstract posets is shown to be false.

Anatoly M. Vershik

The entropy of the random walk on the discrete contable group could be used for comparison of the system of the generators. Fundamental inequality between growth, entropy and escape gives the possibility to define &#34;the best&#34; system of the generators. We formulate a new circle of the problems related to the various growth and asymptotics on the groups

Victor M. Buchstaber, Taras E. Panov

An n-dimensional polytope P^n is called simple if exactly n codimension-one faces meet at each vertex. The lattice of faces of a simple polytope P^n with m codimension-one faces defines an arrangement of even-dimensional planes in R^{2m}. We construct a free action of the group R^{m-n} on the complement of this arrangement. The corresponding quotient is a sm

Vicente Muñoz

We find the shape of the Donaldson invariants of a 4-manifold with b_1=0 and b^+>1, which may be not of simple type. The invariants appear as the q^0 coefficient of a expression given in terms of modular forms (as was predicted by Moore and Witten). We re-express the formula using complete elliptic integrals to prove a conjecture of Kronheimer and Mrowka on

M. Jarnicki, P. Pflug, W. Zwonek

We study the problem of the boundary behaviour of the Bergman kernel and the Bergman completeness in some classes of bounded pseudoconvex domains, which contain also non-hyperconvex domains. Among the classes for which we prove the Bergman completeness and the convergence of the Bergman kernel to infinity while tending to the boundary are all bounded pseudoc

M. M. Skriganov

In the present paper we introduce and study finite point subsets of a special kind, called optimum distributions, in the n-dimensional unit cube. Such distributions are closely related with known (delta,s,n)-nets of low discrepancy. It turns out that optimum distributions have a rich combinatorial structure. Namely, we show that optimum distributions can be

V. L. Vereschagin

The paper concerns asymptotic studies for the sixth Painlevé transcendent as independent variable tends to infinity. The primary tool is averaging and the Whitham method. Elliptic ansatz, appropriate modulation equation and asymptotics for some partial solution to PVI are found.

J. Scott Carter, Daniel Jelsovsky, Seiichi Kamada, Masahico Saito

Lower bounds of betti numbers for homology groups of racks and quandles will be given using the quotient homomorphism to the orbit quandles. Exact sequences relating various types of homology groups are analyzed. Geometric methods of proving non-triviality of cohomology groups are also given, using virtual knots. The results can be applied to knot theory as

L. Chekhov, V. V. Fock

We describe explicitly a noncommutative deformation of the *-algebra of functions on the Teichmüller space of Riemann surfaces with holes equivariant w.r.t. the mapping class group action.

Peter Brinkmann

We prove that an automorphism $ϕ:F\to F$ of a finitely generated free group $F$ is hyperbolic in the sense of Gromov if it has no nontrivial periodic conjugacy classes.

M. Morara, R. Soldati, G. McCartor

It is shown how to obtain the consistent light front form quantization of a non-Abelian pure Yang-Mills theory (gluondynamics) in the framework of the standard perturbative approach. After a short review of the previous attempts in the light cone gauge $A_-=0$, it is explained how the difficulties can be overcome after turning to the anti light cone gauge $A

J. Ambjorn, B. Durhuus, T. Jonsson

We point out some misconceptions in a recent paper by H. Aoki et al. [hep-th/9909060]. In particular, the claim that the two-point function of branched polymers behaves as 1/p^4 instead of 1/p^2 for large p is mistaken and in no way a precondition for the Hausdorff dimension of branched polymers having the well known value four.

Noriaki Kitazawa

It is shown that the auxiliary field in the low-energy effective theory of the supersymmetric QCD (SU(N_c) gauge symmetry with flavors N_f < N_c) can be understood as a physical degree of freedom, once the supersymmetry is explicitly broken. Although the vacuum expectation value of the auxiliary field is just a measure of the supersymmetry breaking in the pe

Davoud Kamani

In this article the interaction of branes at angles with respect to each other with non-zero internal gauge fields are calculated by construction of the boundary states in spacetime in which some of its directions are compact on tori. The interaction depends on both angle and fields.

Alan Kostelecky, Charles Lane

A method is presented for deriving the nonrelativistic quantum hamiltonian of a free massive fermion from the relativistic lagrangian of the Lorentz-violating standard-model extension. It permits the extraction of terms at arbitrary order in a Foldy-Wouthuysen expansion in inverse powers of the mass. The quantum particle hamiltonian is obtained and its nonre

B. Dressler, K. Goeke, M. V. Polyakov, C. Weiss

The $1/N_c$-expansion of QCD suggests large flavor asymmetries of the polarized antiquark distributions in the nucleon. This is confirmed by model calculations in the large-$N_c$ limit (chiral quark-soliton model), which give sizable results for $Δ\bar u (x) - Δ\bar d (x)$ and $Δ\bar u (x) + Δ\bar d (x) - 2 Δ\bar s (x)$. We compute the contributions of these

Panagiota Kanti

We extend the idea of assisted inflation to the case of power-law potentials and demonstrate the simultaneous resolution of two major problems that plague chaotic inflation. The implementation of the same idea in the framework of a 5-dimensional, scalar field theory leads to a model of chaotic inflation free of fine-tuning.

Josef Pochodzalla, Lech Mankiewicz, Murray Moinester, Gunther Piller

We explore the feasibility to study exclusive meson production (EMP) in hard muon-proton scattering at the COMPASS experiment. These measurements constrain the off-forward parton distributions (OFPD&#39;s) of the proton, which are related to the quark orbital contribution to the proton spin.

A. A. Arkhipov

The fundamental relations in the dynamics of single diffraction dissociation and elastic scattering at high energies are discussed.

M. Ciuchini, E. Franco, G. Martinelli, L. Silvestrini

We briefly introduce the Wick-contraction parametrization of hadronic matrix elements and discuss some applications to B and K physics.

H. G. Dosch, A. Hebecker, A. Metz, H. J. Pirner

The interaction of the partonic fluctuation of the virtual photon in deep inelastic scattering with soft color fields describing the hadron is treated in an eikonal approximation. It is known that, in this approach, the small-x limit of the leading-order gluon distribution xg(x,Q^2) is a constant characterizing the averaged local field strength in the target

V. V. Ianovski, I. V. Kolokolov, P. V. Vorob&#39;ev

Numerous and all unsuccessful attempts of experimental search for monopole in cosmic rays and on accelerators in high energy particle collisions have been done since the possibility of existence of a magnetic monopole has been surveyed in 1931. Also the searches have been carried out in mica for monopole tracks as well as for relict monopoles, entrapped by f

O. Nachtmann, C. Schwanenberger

We analyse CP-violating effects in Z -> 4 jet decays, assuming the presence of a CP-violating effective triple gluon coupling. We discuss the influence of this coupling on the decay width. Furthermore, we analyse different CP-odd observables and propose strategies of a direct search for such a CP-violating GGG coupling. The present data of LEP 1 should give

A. Dedes, S. Moretti

We study neutral and charged Higgs boson production in association with stop and sbottom squarks at the Large Hadron Collider (LHC), within the so-called M-SUGRA scenario, i.e., the Supergravity (SUGRA) inspired Minimal Supersymmetric Standard Model (MSSM). For low values of \tanβonly the cases \tilde{t}_1\tilde{t}_1^* H, \tilde{t}_1\tilde{t}_1^* h and \tild

Stefan Weinzierl

We consider a U(1) x SU(2) gauge theory on the four-dimensional manifold S^1 x S^3. If we make the assumption that only gauge transformations connected to the identity are allowed, the winding numbers of U(1) around S^1 and of SU(2) around S^3 become topological conserved quantities. We derive the effective theory for non-trivial winding numbers if all dista

J. Edelmann, G. Piller, N. Kaiser, W. Weise

We present a detailed analysis of resonance contributions in the context of higher twist effects in the moments of the proton spin structure function g_1. For each of these moments, it is found that there exists a characteristic Q^2 region in which (perturbative) higher twist corrections coexist with (non-perturbative) resonance contribution of comparable ma

A. A. Bel&#39;kov, G. Bohm, A. V. Lanyov, A. A. Moshkin

We have combined a new systematic calculation of mesonic matrix elements at O(p^6) from an effective chiral lagrangian approach with Wilson coefficients taken from paper by G.Buchalla et al. Rev.Mod.Phys. 68 (1996) 1125, derived in the framework of perturbative QCD, and restricted partly by experimental data. We derive complete expressions for K-->2pi amplit

Stefan Weinzierl

The calculation of loop amplitudes with parity violation or spin effects within dimensional regularization needs a consistent definition of gamma5. Also loop calculations in supersymmetric theories need a consistent definition of gamma5. In this paper we develop a new formalism, which allows us to define consistent regularization schemes. We use Grothendieck

R. Kenna, C. Pinto, J. C. Sexton

A new method to analytically determine the partition function zeroes of weakly coupled theories on finite-size lattices is developed. Applied to the lattice Schwinger model, this reveals the possible absence of a phase transition at fixed weak coupling. We show how finite-size scaling techniques on small or moderate lattice sizes may mimic the presence of a

M. Goeckeler, R. Horsley, D. Petters, D. Pleiter

We present results for the mass spectrum and decay constants using non-perturbatively O(a) improved Wilson fermions. Three values of $β$ and 30 different quark masses are used to obtain the chiral and continuum limits. Special emphasis will be given to the question of taking the chiral limit and the existence of non-analytic behavior predicted by quenched ch

K-I. Ishikawa, T. Onogi, N. Yamada

We present a calculation of the perturbative matching coefficients including mixing with higher dimensional operators for the temporal component of the heavy-light axial current, $A_{4}$, and the $ΔB=2$ operator, $O_S$. For $A_{4}^{\scriptsize static, NRQCD}$, calculations with various RG-improved gauge actions are peformed. Matching coefficients with NRQCD

Pierre Midy, Jean-Pierre Petit

An attempt is made here to extend to the microscopic domain the scale invariant character of gravitation - which amounts to consider expansion as applying to any physical scale. Surprisingly, this hypothesis does not prevent the redshift from being obtained. It leads to strong restrictions concerning the choice between the presently available cosmological mo

John Ellis, N. E. Mavromatos, D. V. Nanopoulos

We review the possibility that quantum fluctuations in the structure of space-time at the Planck scale might be subject to experimental probes. We study the effects of space-time foam in an approach inspired by string theory, in which solitonic D-brane excitations are taken into account when considering the ground state. We model the properties of this mediu

Olivier Devillers, Pierre-Maris Gandoin

The compression of geometric structures is a relatively new field of data compression. Since about 1995, several articles have dealt with the coding of meshes, using for most of them the following approach: the vertices of the mesh are coded in an order such that it contains partially the topology of the mesh. In the same time, some simple rules attempt to p

A. V. Izyumov, K. V. Samokhin

Based on the analogy with the quantum mechanics of a particle propagating in a {\em complex} potential, we develop a field-theoretical description of the statistical properties of a self-avoiding polymer chain in a random environment. We show that the account of the non-Hermiticity of the quantum Hamiltonian results in a qualitatively different structure of

Ilya Grinberg, Nicholas J. Ramer, Andrew M. Rappe

We present a method for constructing a scalar-relativistic pseudopotential which provides exact agreement with relativistic Dirac-Slater all-electron eigenvalues at the reference configuration. All-electron wave functions are self-consistently computed in the valence region at the exact all-electron scalar relativistic eigenvalues. This method improves tr an

Hannu Hakkinen, Robert N. Barnett, Uzi Landman

Equilibrium structure, local densities of states, and electronic transport in a gold nanowire made of a four-atom chain supported by two gold electrodes, which has been imaged recently by high-resolution electron microscopy, and chemical modification of the wire via the adsorption of a methylthiol molecule, are investigated with ab-initio local density funct