April 1999 arXiv papers — page 12

L. V. Il'ichov

An effective force induced by spatially depending decoherence is predicted. The phenomenon is illustrated by a simple model of a 1/2-spin particle subjected to distributed unselective measurement of noncommuting spin components.

Joel M. Williams

In the particle in the box problem, the particle is not in both boxes at the same time as some would have you believe. It is a set definition situation with the two boxes being part of a set that also contains a particle. Set and subset differences are explored. Atomic electron orbitals can be mimicked by roulette wheel probability; thus ELECTRONIC ROULETTE.

A. Sibirtsev, W. Cassing

We analyse the experimental data on near threshold $π$, $η$, $ω$, $η'$ and $K^+$ production from $pp$ collisions and show that all information gained so far is compatible with approximately constant production matrix elements when including the rescattering between the baryons in the final states. Different methods to include the final state interactions

Piotr Magierski, Ramon Wyss

In this paper we analyze the possibility of the appearance of quadrupole vibrational states in superdeformed nuclei from the $A\approx 150$ region. We discuss the role of pairing correlations for a proper description of quadrupole vibrations, especially of the $β$ type.

Philip R. Page

We construct (hybrid) baryons in the flux-tube model of Isgur and Paton. In the limit of adiabatic quark motion, we build proper eigenstates of orbital angular momentum and indicate the flavour, spin, chirality and J^P of (hybrid) baryons. The adiabatic potential is calculated as a function of the quark positions.

Philip R. Page

We construct baryons and hybrid baryons in the non-relativistic flux-tube model of Isgur and Paton. The motion of the flux-tube with the three quark positions fixed, except for centre of mass corrections, is discussed. It is shown that the problem can to an excellent approximation be reduced to the independent motion of a junction and strings.

Simon Capstick, Philip R. Page

Hybrid baryon states are described in quark potential models as having explicit excitation of the gluon degrees of freedom. Such states are described in a model motivated by the strong coupling limit of Hamiltonian lattice gauge theory, where three flux tubes meeting at a junction play the role of the glue. The adiabatic approximation for the quark motion is

Guillaume van Baalen, Alain Schenkel, Peter Wittwer

We analyze the long time behavior of initial value problems that model a process where particles of type A and B diffuse in some substratum and react according to $nA+nB\to C$. The case n=1 has been studied before; it presents nontrivial behavior on the reactive scale only. In this paper we discuss in detail the cases $n>3$, and prove that they show nontrivi

A. Sevostyanov

In 1978 Kostant suggested the Whittaker model of the center of the universal enveloping algebra U(g) of a complex simple Lie algebra g. The main result is that the center of U(g) is isomorphic to a commutative subalgebra in U(b), where b is a Borel subalgebra in g. This observation is used in the theory of principal series representations of the correspondin

Jaroslaw Wlodarczyk

In this paper we develop a Morse-like theory in order to decompose birational maps and morphisms of smooth projective varieties defined over a field of characteristic zero into more elementary steps which are locally étale isomorphic to equivariant flips, blow-ups and blow-downs of toric varieties. A crucial role in the considerations is played by K^*-action

Helmut Prodinger

In problem 10621 of the American Mathematical Monthly the question was raised whether it is possible to explicitly compute Cantor's singular moment of order -1. This is answered in the affirmative.

Stephan Endrass

The aim of this article is to introduce standard bases of ideals in polynomial rings with respect to a class of orderings which are not necessarily semigroup orderings. Our approach generalises the concept of standard bases with respect to semigroup orderings described by Graebe and Greuel/Pfister. To compute these standard bases we give a slightly modified

J. R. Links, M. D. Gould, Y. -Z. Zhang

The construction of link polynomials associated with finite dimensional representations of ribbon quasi-Hopf algebras is discussed in terms of the formulation of an appropriate Markov trace. We then show that this Markov trace is invariant under twisting of the quasi-Hopf structure, which in turn implies twisting invariance of the associated link polynomials

Bruno Gauthier

Following suggestions of T. H. Koornwinder, we give a new proof of Kummer's theorem involving Zeilberger's algorithm, the WZ method and asymptotic estimates. In the first section, we recall a classical proof given by L. J. Slater. The second section discusses the new proof, in the third section sketches of similar proofs for Bailey's and Dixon&#3

P. Berglund, P. Mayr

We use a recently proposed formulation of stable holomorphic vector bundles $V$ on elliptically fibered Calabi--Yau n-fold $Z_n$ in terms of toric geometry to describe stability conditions on $V$. Using the toric map $f: W_{n+1} \to (V,Z_n)$ that identifies dual pairs of F-theory/heterotic duality we show how stability can be related to the existence of holo

Koushik Ray

We find, from the toric description of the moduli space of D3-branes on non-compact six-dimensional singularities $\C^3/\Z_3$ and $\C^3/\Z_5$ in the blown-down limit, the four-dimensional bases on which these singular spaces are complex cones, and prove the existence of K\"ahler-Einstein metrics on these four-dimensional bases. This shows, in particular, tha

Matthias Staudacher

We discuss aspects of recent novel approaches towards understanding the large N limit of matrix field theories with local or global non-abelian symmetry.

S. Kalyana Rama

A closed universe containing pressureless dust, more generally perfect fluid matter with pressure-to-density ratio w in the range (1/3, - 1/3), violates holographic principle applied according to the Fischler-Susskind proposal. We show, first for a class of two-fluid solutions and then for the general multifluid case, that the closed universe will obey the h

Igor Bandos, Jerzy Lukierski, Dmitri Sorokin

A generalization of the Ferber-Shirafuji formulation of superparticle mechanics is considered. The generalized model describes the dynamics of a superparticle in a superspace extended by tensorial central charge coordinates and commuting twistor-like spinor variables. The D=4 model contains a continuous real parameter $a\geq 0$ and at a=0 reduces to the SU(2

Satish D. Joglekar, Bhabani Prasad Mandal

We formulate a superspace field theory which is shown to be equivalent to the $c-\bar{c}$ symmetric BRS/Anti-BRS invariant Yang-Mills action. The theory uses a 6-dimensional superspace and one OSp(3,1|2) vector multiplet of unconstrained superfields. We establish a superspace WT identity and show that the formulation has an asymptotic OSp(3,1|2) invariance a

Nicolao Fornengo

We investigate the effect induced by neutrino oscillation on the dark matter indirect detection signal which consists in a muon neutrino flux produced by neutralino annihilation in the Earth core. We consider the neutrino oscillation parameters relevant to the atmosferic neutrino deficit, both in the nu_mu -> nu_tau and nu_mu -> nu_s cases.

Sheldon Stone

I review several topics pertaining to Weak decays of b and c quarks, including measurements of Vcb, |Vub/Vcb|, fDs and b->s gamma.

G. Belanger, F. Boudjema, K. Sridhar

We revisit the effect of the large stop mixing on the decay and production of the lightest SUSY Higgs at the LHC. We stress that whenever the inclusive 2-photon signature is substantially reduced, associated production, $Wh$ and $t\bar t h$, with the subsequent decay of the Higgs into photons is enhanced and becomes an even more important discovery channel.

O. A. Battistel, G. Dallabona, M. C. Nemes, B. Hiller

An implicit four dimensional regularization is applied to calculate the axial-vector-vector anomalous amplitude. The present technique always complies with results of Dimensional Regularization and can be easily applied to processes involving odd numbers of $γ_5$ matrices. This is illustrated explicitely in the example of this letter.

Nils A. Tornqvist

The lightest scalar and pseudoscalar nonets are discussed within the framework of the broken U3$\times$U3 linear sigma model, and it is shown that already at the tree level this model works remarkably well predicting scalar masses and couplings not far from present experimental values, when all parameters are fixed from the pseudoscalar masses and decay cons

P. Shukla, S. K. Gupta A. K. Mohanty

First order quark hadron phase transition is considered in scaling hydrodynamics including the Csernai-Kapusta model of nucleation of hadronic bubbles leading to supercooling. The effect of viscosity on the entropy production is studied in ideal as well as in viscous hydrodynamics with and without supercooling. It is found that the excess entropy produced du

A. van Hameren, R. Kleiss

For the Lego discrepancy with M bins, which is equivalent with a chi^2-statistic with M bins, we present a procedure to calculate the moment generating function of the probability distribution perturbatively if M and N, the number of uniformly and randomly distributed data points, become large. Furthermore, we present a phase diagram for various limits of th

I. Lazanu, S. Lazanu

A comparative theoretical study of the damages produced by protons and pions, in the energy range 50 MeV - 50 GeV, in diamond, is presented. The concentration of primary defects (CPD) induced by hadron irradiation is used to describe material degradation. The CPD has very different behaviours for protons and pions: the proton degradation is important at low

W. Grimus, S. Mohanty, P. Stockinger

We discuss the field-theoretical approach to neutrino oscillations. This approach includes the neutrino source and detector processes and allows to obtain the neutrino transition or survival probabilities as cross sections derived from the Feynman diagram of the combined source -- detection process. In this context, the neutrinos which are supposed to oscill

S. Fajfer, D. Horvatic, D. Tadic, S. Zganec

Two photon decay widths of the $J^P = O^+$ scalar mesons $a_{0} (980)$, $f_{0}(980)$, $f_{0}(1370)$ and $χ_{c0}$ are calculated in a covariant model which is characterized by the quark - antiquark structure. Previously such models were used to calculate current form factors. Here a different application is tried. A simple version of the model uses adjusted n

S. Lazanu, I. Lazanu, E. Borchi

The energy dependence of the concentration of primary displacements induced by protons and pions in diamond has been calculated in the energy range 50 MeV - 50 GeV, in the frame of the Lindhard theory. The concentrations of primary displacements induced by protons and pions have completely different energy dependencies: the proton degradation is very importa

R. Foot, R. R. Volkas

The Exact Parity Model (EPM) is, in part, a theory of neutrino mass and mixing that can solve the atmospheric, solar and LSND anomalies. The central feature of the neutrino sector is three pairs of maximally mixed ordinary and mirror neutrinos. It has been shown that ordinary-mirror neutrino oscillations can generate large neutrino asymmetries in the epoch o

P. C. Rowson

Preliminary SLD electroweak results based on essentially the complete 550K Z dataset are presented and interpreted, and some historical background is provided.

W. Rudnicki, P. Zieba

It has previously been shown [W. Rudnicki, Phys. Lett. A 224, 45 (1996)] that a generic gravitational collapse cannot result in a naked singularity accompanied by closed timelike curves. An important role in this result plays the so-called inextendibility condition, which is required to hold for certain incomplete null geodesics. In this paper, a theorem is

S. Q. Wu, X. Cai

The separated radial part of a sourceless massive complex scalar field equation on the Kerr-Newman black hole background is shown to be a generalized spin-weighted spheroidal wave equation of imaginary number order. While the separated angular part is an ordinary spheroidal wave equation. General exact solutions in integral forms and in power series expansio

Holger Lyre

The purpose of this paper is to present a generalized hole argument for gauge field theories and their geometrical setting in terms of fiber bundles. The generalized hole argument is motivated and extended from the spacetime hole arguments which appear in spacetime theories based on differentiable manifolds such as general relativity. Analogously, the genera

Mark Lee, Yorick Wilks

The two principal areas of natural language processing research in pragmatics are belief modelling and speech act processing. Belief modelling is the development of techniques to represent the mental attitudes of a dialogue participant. The latter approach, speech act processing, based on speech act theory, involves viewing dialogue in planning terms. Uttera

Dale Gerdemann, Gertjan van Noord

Context sensitive rewrite rules have been widely used in several areas of natural language processing, including syntax, morphology, phonology and speech processing. Kaplan and Kay, Karttunen, and Mohri & Sproat have given various algorithms to compile such rewrite rules into finite-state transducers. The present paper extends this work by allowing a limited

A. A. Louis, N. W. Ashcroft

Linear response methods applied to electron systems often display a level of accuracy which is notable when viewed in terms of the strengths of perturbing interactions. Neglect of higher response terms is in fact justifiable in many cases and it can be shown to stem from an intrinsic interference between atomic and electronic length scales. For fluid metalli

A. A. Louis, N. W. Ashcroft

We show that electron-ion structure factors in fluid metallic systems can be well understood from an application of linear response in the electron system, combined with hard-sphere like correlation for the ionic component. In particular, we predict that electron-ion structure factors fall into two general classes, one for high ($Z>3$) and one for low ($Z\le

A. A. Louis, R. Finken, J-P. Hansen

We investigate the structure of colloid-polymer mixtures by calculating the structure factors for the Asakura-Oosawa model in the PY approximation. We discuss the role of potential range, polymer concentration and polymer-polymer interactions on the colloid-colloid structure. Our results compare reasonably well with the recent experiments of Moussaïd et. al.

L. O. Manuel, H. A. Ceccatto

We study, within the Schwinger-boson approach, the ground-state structure of two Heisenberg antiferromagnets on the triangular lattice: the J1-J2 model, which includes a next-nearest-neighbor coupling J2, and the spatially-anisotropic J1-J'1 model, in which the nearest-neighbor coupling takes a different value J'1 along one of the bond directions. Th

Anders W. Sandvik, Chris J. Hamer

We present high-precision quantum Monte Carlo results for the S=1/2 XY model on a two-dimensional square lattice, in the ground state as well as at finite temperature. The energy, the spin stiffness, the magnetization, and the susceptibility are calculated and extrapolated to the thermodynamic limit. For the ground state, we test a variety of finite-size sca

A. V. Lopatin, L. B. Ioffe

We develop a general technique to calculate the probability of transitions over the barriers in spin-glasses in the framework of the dynamical theory. We use Lagrangian formulation of the instanton dynamics in which the transitions are represented by instantons. We derive the full set of the equations that determine the instantons but instead of solving them

V. Becker, H. K. Janssen

We present a field theoretic renormalization group study for the critical behaviour of a uniformly driven diffusive system with quenched disorder, which is modelled by different kinds of potential barriers between sites. Due to their symmetry properties, these different realizations of the random potential barriers lead to three different models for the phas

C. Joerger, S. J. Cheng, H. Rubel, W. Dietsche

We report on the first measurements of the drag effect between coupled 2D-hole gases. We investigate the coupling by changing the carrier densities in the quantum wells, the widths of the barriers between the gases and the perpendicular magnetic field. From the data we are able to attribute the frictional drag to phonon coupling, because the non-parabolicity

T. Rizk, A. Yulius, W. I. Yoo, P. F. Bagwell

We have formed superconducting contacts in which Cooper pairs incident from a thick In layer must move through a thin Nb layer to reach a semiconductor, either InAs or low temperature grown (LTG) GaAs. The effect of pair tunneling through the Nb layer can be seen by varying the temperature through the critical temperature of In. Several of the In/Nb-InAs dev

Richard Riedel, Philip F. Bagwell

In a point contact NS junction, perfect Andreev reflection occurs over a range of voltages equal to the superconducting energy gap, producing an excess current of $I_{exc} = (4/3)(2eΔ/h)$. If the superconductor has a finite width, rather than the infinite width of the point contact, one cannot neglect superfluid flow inside the superconducting contact. The e

Masaki Oshikawa, Ian Affleck

A theory of low temperature (T) electron spin resonance (ESR) in half-integer spin antiferromagnetic chains is developed using field theory methods and avoiding previous approximations. It is compared to experiments on Cu benzoate. Power laws are predicted for the line-width broadening due to various types of anisotropy. At T -> 0, zero width absorption peak

Shlomo Argamon, Ido Dagan, Yuval Krymolowski

Recognizing shallow linguistic patterns, such as basic syntactic relationships between words, is a common task in applied natural language and text processing. The common practice for approaching this task is by tedious manual definition of possible pattern structures, often in the form of regular expressions or finite automata. This paper presents a novel m

Weinan E, Eric Vanden Eijnden

A statistical theory is developed for the stochastic Burgers equation in the inviscid limit. Master equations for the probability density functions of velocity, velocity difference and velocity gradient are derived. No closure assumptions are made. Instead closure is achieved through a dimension reduction process, namely the unclosed terms are expressed in t

Lynn D. Matthews, John S. Gallagher, III, John E. Krist

We have used the Wide Field Planetary Camera 2 aboard the Hubble Space Telescope to image the compact star cluster nuclei of the nearby, late-type, low-luminosity spiral galaxies NGC 4395, NGC 4242, and ESO 359-029. We also analyze archival WFPC2 observations of the compact star cluster nucleus of M33. A comparative analysis of the structural and photometric

Markus Landgraf, Michael Müller, Eberhard Grün

We predict the amount of cometary, interplanetary, and interstellar cosmic dust that is to be measured by the Cometary and Interstellar Dust Analyzer (CIDA) and the aerogel collector on-board the Stardust spacecraft during its fly-by of comet P/Wild 2 and during the interplanetary cruise phase. We give the dust flux on the spacecraft during the encounter wit

J. W. Sulentic, P. Marziani

As a consequence of improved S/N, spectral resolution and wavelength coverage various authors have introduced, without strong justification, new emitting regions to account for various emission line profile differences in AGN. The so-called CIVlambda1549 intermediate line region (ILR) appears to be especially ill-defined. We present observational evidence th

Joseph L. Hora, William B. Latter, Lynne K. Deutsch

We present medium-resolution (R~700) near-infrared (lambda = 1 - 2.5 micron) spectra of a sample of planetary nebulae (PNe). A narrow slit was used which sampled discrete locations within the nebulae; observations were obtained at one or more positions in the 41 objects included in the survey. The PN spectra fall into one of four general categories: H I emis

A. D. Kudryashov, N. N. Chugai, A. V. Tutukov

We carried out kinetic calculations of thermonuclear burning in the hydrogen-rich matter to simulate nucleosynthesis yields in nova outbursts. These results are used to calculate the light curves of annihilation gamma-ray line from N, O and F radioactive isotopes.

Herman J. Mosquera Cuesta

If neutrino flavor changes really exist, to say: $μ$-neutrino oscillating into a sterile neutrino, then, it can be expected that due to neutrino oscillations and non-spherical distortion of the resonance surface induced by the magnetic field, some asymmetric emission of sterile neutrinos can occur during the protoneutron star formation at the onset of a supe

S. Capozziello, G. Iovane, G. Lambiase, C. Stornaiolo

We show that in theories of gravitation with torsion the helicity of fermion particles is not conserved and we calculate the probability of spin flip, which is related to the anti-symmetric part of affine connection. Some cosmological consequences are discussed.

J. Alberto Lobo, M. Angeles Serrano

Apart from omnidirectional, a solid elastic sphere is a natural multimode and multifrequency device for the detection of Gravitational Waves (GW). Motion sensing in a spherical GW detector thus requires a multiple set of transducers attached to it at suitable locations. Resonant transducers exert a significant back action on the larger sphere, and as a conse

N. L. Homeier, J. S. Gallagher

The morphology and kinematics of the luminous blue starburst galaxy NGC 7673 are explored using the WIYN 3.5m telescope. Signs of a past kinematic disturbance are detected in the outer galaxy; the most notable feature is a luminous ripple located 1.55 arc minutes from the center of NGC 7673. Sub-arc second imaging in B and R filters also reveals red dust lan

Francesco R. Ferraro, Barbara Paltrinieri, Robert T. Rood, Ben Dorman

Using HST-WFPC2 observations in two ultraviolet (UV) filters (F225W and F336W) of the central region of the high density Galactic Globular cluster (GGC) M80 we have identified 305 Blue Straggler Stars (BSS) which represents the largest and most concentrated population of BSS ever observed in a GGC. We also identify the largest, clean sample of evolved BSS ye

M. A. Aloy, J. A. Pons, J. M. Ibanez

We derive and analyze a simplified formulation of the numerical viscosity terms appearing in the expression of the numerical fluxes associated to several High-Resolution Shock-Capturing schemes. After some algebraic pre-processing, we give explicit expressions for the numerical viscosity terms of two of the most widely used flux formulae, which implementatio

Piercarlo Bonifacio

Sagittarius, the nearest external galaxy, will be amenable to detailed abundance studies with VLT and other 8m class telescopes. Such data, in conjuction with the similar data of our own galaxy, will allow a deeper understanding of chemical evolution. Our study conducted with NTT shows the presence of metal-rich stars with radial velocities compatible with S

Guido Kruse, Peter Schneider

Due to gravitational instability, an initially Gaussian density field develops non-Gaussian features as the Universe evolves. The most prominent non-Gaussian features are massive haloes, visible as clusters of galaxies. The distortion of high-redshift galaxy images due to the tidal gravitational field of the large-scale matter distribution, called cosmic she

Th. Boller

A sample of 323 Ultraluminous IRAS galaxies (ULIRGs) has been correlated with the ROSAT All-Sky Survey and ROSAT public pointed observations. 22 objects are detected in ROSAT survey observations, and 6 ULIRGs are detected in addition in ROSAT public pointed observations. The detection is based on a visual inspection of the X-ray contour maps overlaid on opti

M. Zielinsky, J. Stutzki

This paper is understood as a supplement to the paper by [Stutzki et al, 1998], where we have shown the usefulness of the Allan-variance and its higher dimensional generalization, the Delta-variance, for the characterization of molecular cloud structures. In this study we present the connection between the Allan- and Delta-variance and a more popular structu

Amir Levinson

The time dependent synchrotron emission from relativistic jets, and the relation between the synchrotron and ERC emission is considered within the framework of the radiative front model. The timescale and profile of the optically thin emission are shown to be determined, in this model, by the shock formation radius, the thickness of expelled fluid slab and t

Abhas Mitra

The only instance when the General Relativistic (GTR) collapse equations have been solved (almost) exactly to explicitly find the metric coefficients is the case of a homogeneous spherical dust (Oppenheimer and Snyder in 1939 in Phy. Rev. 56, 455). The equation (37) of their paper showed the formation of an event horizon for a collapsing homogeneous dust bal

Abhas Mitra

Schwarzschild coordinates (r,t) fail to describe the region within the event horizon (EH), (r <= 2 M), of a Black Hole (BH) because the metric coefficients exhibit singularity at r=2 M, and the radial geodesic of a particle appears to be null (ds^2 =0) when actually it must be timelike (ds^2 >0), if, indeed, r_g =2 M >0. Thus, both the exterior and the inter

O. Almaini, A. Lawrence, B. J. Boyle

A great deal of interest has been generated recently by the results of deep submillimetre surveys, which in principle allow an unobscured view of dust-enshrouded star formation at high redshift. The extragalactic far-infrared and submillimetre backgrounds have also been detected, providing further constraints on the history of star formation. In this paper w

R. Balbinot, A. Fabbri

Minimally coupled 4D scalar fields in Schwarzschild space-time are considered. Dimensional reduction to 2D leads to a well known anomaly induced effective action, which we consider here in a local form with the introduction of auxiliary fields. Boundary conditions are imposed on them in order to select the appropriate quantum states (Boulware, Unruh annd Isr

David Berenstein, Robert G. Leigh

We consider perturbative Type II superstring theory in the covariant NSR formalism in the presence of NSNS and RR backgrounds. A concrete example that we have in mind is the geometry of D3-branes which in the near-horizon region is AdS_5 x S_5, although our methods may be applied to other backgrounds as well. We show how conformal invariance of the string pa

Amand Faessler, T. S. Kosmas, Sergey Kovalenko, J. D. Vergados

The flavor violating $μ^--e^-$ conversion in nuclei is studied within the minimal supersymmetric standard model. We focus on the R-parity violating contributions at tree level including the trilinear and the bilinear terms in the superpotential as well as in the soft supersymmetry breaking sector. The nucleon and nuclear structure have consistently been take

S. M. Natanzon

The simplest non-trivial solutions of WDVV equations are A_n and B_n-potentials, which describe metrics of K.Saito on spaces of versal deformation of A_n and B_n-singularities. These are some polynomials, which were known for $n\leqslant$ 4. We find some recurrence relations, which give a possibility to find all A_n and B_n-potentials. In passing we give rec

T. P. Devereaux, A. P. Kampf

Calculations are presented for electronic Raman scattering and infrared conductivity in a $d_{x^{2}-y^{2}}$ superconductor including the effects of elastic scattering via anisotropic impurities and inelastic spin-fluctuation scattering. A consistent description of experiments on optimally doped Bi-2212 is made possible by considering the effects of correlati

Valery P. Dmitriyev

An exact analogy of electromagnetic fields and particles can be found in continuum mechanics of a turbulent perfect fluid with voids. Deviations of the turbulence from a homogeneous isotropic state correspond to electromagnetic fields: with the average pressure as electrostatic potential, the average fluid velocity as magnetic vector potential and the densit

Matteo Palassini, A. P. Young

We study how the ground state of the two-dimensional Ising spin glass with Gaussian interactions in zero magnetic field changes on altering the boundary conditions. The probability that relative spin orientations change in a region far from the boundary goes to zero with the (linear) size of the system L like L^{-lambda}, where lambda = -0.70 +/- 0.08. We ar

P. J. Bardroff, S. Stenholm

We analyze the excess noise in the framework of the conventional quantum theory of laser-like systems. Our calculation is conceptually simple and our result also shows a correction to the semi-classical result derived earlier.

V. Skalozub, M. Bordag

Electroweak phase transition in a magnetic field is investigated within the one-loop and ring diagram contributions to the effective potential in the minimal Standard Model. All fundamental fermions and bosons are included with their actual values of masses and the Higgs boson mass is considered in the range $75 GeV \leq m_H \leq 115 GeV$. The effective pote

T. T. Nguyen, I. Rouzina, B. I. Shklovskii

Bending rigidity of a charged membrane or a charged polyelectrolyte screened by monovalent counterions is known to be enhanced by electrostatic effects. We show that in the case of screening by multivalent counterions the electrostatic effects reduce the bending rigidity. This inversion of the sign of the electrostatic contribution is related to the formatio

Aleksander Filip Zarnecki

Data from HERA, LEP and the Tevatron, as well as from low energy experiments are used to constrain the scale of possible electron-quark contact interactions. Different models are considered, including the most general one, in which all new couplings can vary independently. Limits on couplings and mass scales are extracted and upper limits on possible effects

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

The results of the more detailed NNLO QCD analysis of the CCFR data for $xF_3$ SF are presented. The factorization scale uncertainties are analysed. The NNLO results for $alpha_s(M_Z)$ and twist-4 contributions are obtained. Despite the fact that the amplitude of the $x$-shape of the twist-4 factor is consequently decreasing at the NLO and NNLO, our new QCD

Philippe Ruelle

Conformally invariant boundary conditions for minimal models on a cylinder are classified by pairs of Lie algebras $(A,G)$ of ADE type. For each model, we consider the action of its (discrete) symmetry group on the boundary conditions. We find that the invariant ones correspond to the nodes in the product graph $A \otimes G$ that are fixed by some automorphi

J. A. S. Lima, J. S. Alcaniz

We propose a simple method for determining the redshift $z_{m}$ at which the angular size of an extragalactic source with fixed proper diameter takes its minimal value. A closed analytical expression, which is quite convenient for numerical evaluation is derived. The method is exemplified with the following FRW type expanding universes: the open matter domin

Jose Luis Gruver

We show that an infinite set of q-deformed relevant operators close a partial q-deformed Lie algebra under commutation with the Arik-Coon oscillator. The dynamics is described by the multicommutator: [H,..., [H, O]...], that follows a power law which leads to a dynamical scaling. We study the dynamics of the Arik-Coon and anharmonic oscillators and analyze t

R. C. Rashkov

In this letter the boundary problem for massless and massive Rarita-Schwinger field in the AdS/CFT correspondence is considered. The considerations are along the lines of a paper by Henneaux (hep-th/9902137) and are based on the requirement the solutions to be a stationary point for the action functional. It is shown that this requirement, along with a defin

Y. Uchiyama, Y. Sasago, I. Tsukada, K. Uchinokura

Magnetic susceptibility, high-field magnetization and inelastic neutron scattering experiments are used to study the magnetic properties of a new S=1 quasi-1-dimensional antiferromagnet PbNi2V2O8. Inter-chain interactions are shown to be almost, but not quite, strong enough to destroy the nonmagnetic singlet ground state and the energy gap in the magnetic ex

Yoshihisa Ohshima, Kiyoshi Okuyama, Hiroshi Suzuki, Hirofumi Yasuta

We present a direct field theoretical calculation of the consistent gauge anomaly in the superfield formalism, on the basis of a definition of the effective action through the covariant gauge current. The scheme is conceptually and technically simple and the gauge covariance in intermediate steps reduces calculational labors considerably. The resultant super

Bruce Hunt, Rolf Schimmrigk

A construction of Calabi-Yaus as quotients of products of lower-dimensional spaces in the context of weighted hypersurfaces is discussed, including desingularisation. The construction leads to Calabi-Yaus which have a fiber structure, in particular one case has K3 surfaces as fibers. These Calabi-Yaus are of some interest in connection with Type II -heteroti

Bruno Eckhardt, Joerg Schumacher

The structure function of a scalar $θ({\bf x},t)$, passively advected in a two-dimensional turbulent flow ${\bf u}({\bf x},t)$, is discussed by means of the fractal dimension $δ^{(1)}_g$ of the passive scalar graph. A relation between $δ^{(1)}_g$, the scaling exponent $ζ_1^{(θ)}$ of the scalar structure function $D_1^{(θ)}(r)$, and the structure function D_2

Igor Bray

Using the electron-hydrogen scattering Temkin-Poet model we investigate the behavior of the cross sections for excitation of all of the states used in the convergent close-coupling (CCC) formalism. In the triplet channel, it is found that the cross section for exciting the positive-energy states is approximately zero near-threshold and remains so until a fur

S. Sergeev

Equations of motion for a classical 3d discrete model, whose auxialiary system is a linear system, are investigated. The Lagrangian form of the equations of motion is derived. The Lagrangian variables are a triplet of &#34;tau functions&#34;. The equations of motion for the Triplet of Tau functions are Three Trilinear equations. Simple solitons for the trili

P. J. Bardroff, S. Stenholm

In an earlier work [P. J. Bardroff and S. Stenholm], we have derived a fully quantum mechanical description of excess noise in strongly damped lasers. This theory is used here to derive the corresponding quantum Langevin equations. Taking the semi-classical limit of these we are able to regain the starting point of Siegman&#39;s treatment of excess noise [Ph

M. G. Benedict, A. Czirjak

We consider a class of states in an ensemble of two-level atoms: a superposition of two distinct atomic coherent states, which can be regarded as atomic analogues of the states usually called Schrodinger cat states in quantum optics. According to the relation of the constituents we define polar and nonpolar cat states. The properties of these are investigate

A. Acin, J. I. Latorre, P. Pascual

Positive operator valued measurements on a finite number of N identically prepared systems of arbitrary spin J are discussed. Pure states are characterized in terms of Bloch-like vectors restricted by a SU(2 J+1) covariant constraint. This representation allows for a simple description of the equations to be fulfilled by optimal measurements. We explicitly f

A. E. Karpelson

An approximate method to compute mean velocity profiles in turbulent flows is developed. This approach is based on the equation connecting the Reynolds stress and mean velocity. By using the measured values of pressure drop and average (bulk) flow velocity, such characteristics of a turbulent flow as the mean velocity and Reynolds stress distributions were c

M. L. Schinkeev

In this work a method of spectroscopy without monochromators for the undulator radiation (UR) source is proposed. This method is based of changing the magnetic field in the undulator. Different variations of field modulations and corresponding object reaction for the case of a dipole regime of UR exitation were considered. The results of a numerical experime

Gideon Gilat

Chirality is not just a structural artifact in biology but it may provide for a genuine biological advantage. This is due to the phenomenon of chiral interaction (CI) which is described here for mechanical-chiral devices. The main mechanical feature of chiral interaction is its mode of selecting one direction of rotation out of two possible and opposite ones

J. J. Garcia-Ripoll, V. M. Perez-Garcia

In this paper we develop a new approximation method valid for a wide family of nonlinear wave equations of Nonlinear Schrödinger type. The result is a reduced set of ordinary differential equations for a finite set of parameters measuring global properties of the solutions, named momenta. We prove that these equations provide exact results in some relevant c

K. Nakayama, J. W. Durso, J. Haidenbauer, C. Hanhart

The production of $ϕ$-mesons in proton-proton collisions is investigated within a relativistic meson-exchange model of hadronic interactions. The experimental prerequisites for extracting the $NNϕ$ coupling strength from this reaction are discussed. In the absence of a sufficient set of data, which would enable an accurate determination of the $NNϕ$ coupling