September 1997 arXiv papers — page 8

Joel Parriott, Charles Alcock

The accretion of comets onto DA white dwarfs can produce observable metal absorption lines. We show here that comet systems around the progenitor main sequence star are vulnerable to being lost during asymptotic giant branch mass loss, if the mass loss is sufficiently asymmetric to impart modest linear momentum to the white dwarf. This may have bearing on th

Peter Nattermann

We review a possible framework for (non)linear quantum theories, into which linear quantum mechanics fits as well, and discuss the notion of ``equivalence'' in this setting. Finally, we draw the attention to persisting severe problems of nonlinear quantum theories.

M. Ardehali

A correlation inequality is derived from local realism and a supplementary assumption. Unlike Clauser-Horne (CH) inequality [or Clauser-Horne-Shimony-Holt (CHSH) inequality] which is violated by quantum mechanics by a factor of $\sqrt 2$, this inequality is violated by a factor of 1.5. Thus the magnitude of violation of this inequality is approximately 20.7%

S. Schneider, H. M. Wiseman, W. J. Munro, G. J. Milburn

We investigate in detail the effects of a QND vibrational number measurement made on single ions in a recently proposed measurement scheme for the vibrational state of a register of ions in a linear rf trap [C. D'Helon and G.J. Milburn, Phys. Rev. A 54, 5141 (1996)]. The performance of a measurement shows some interesting patterns which are closely relat

Yan Soibelman

We introduce the notion of meromorphic tensor category and illustrate it in several examples. They include representations of quantum affine algebras, chiral algebras of Beilinson and Drinfeld, G-vertex algebras of Borcherds, and representations of GL over a local field. Hopefully the formalism will accomodate various tensor structures arising in relation to

Su-Win Yang

The universal Vassiliev invariant from the perturbative Chern-Simons theory is actually a knot invariant without any correction term. The anomaly considered by Bott and Taubes is proved to be zero.

M. Grigorescu

The effects of a voltage pulse on the localization probability for a Xe atom prepared in a pure state localized on the STM surface at 0 temperature is investigated by numerically integrating the time-dependent Schroedinger equation. In these calculations the environmental interactions are neglected, and voltage pulses of 20 and 7 ns with symmetric triangular

B. Lauss, P. Ackerbauer, W. H. Breunlich, B. Gartner

We report the first direct observation of excited state muon transfer in hydrogen/deuterium mixtures by direct measurement of q_1s, the probability that a mu-p atom, which is initially formed in an excited state, reaches the 1s ground state. The dependence of q_1s on deuterium concentration c_d was measured for two different densities at cryogenic temperatur

B. Lauss, P. Ackerbauer, W. H. Breunlich, B. Gartner

We report our investigations of X rays emitted during the muonic cascade in hydrogen employing charge coupled devices as X-ray detectors. The density dependence of the relative X-ray yields for the muonic hydrogen lines (K_alpha, K_beta, K_gamma) has been measured at densities between 0.00115 and 0.97 of liquid hydrogen density. In this density region collis

F. Ghio, B. Girolami, M. Capogni, L. Casano

We describe the electromagnetic calorimeter built for the GRAAL apparatus at the ESRF. Its monitoring system is presented in detail. Results from tests and the performance obtained during the first GRAAL experiments are given. The energy calibration accuracy and stability reached is a small fraction of the intrinsic detector resolution.

H. Feldmeier, T. Neff, R. Roth, J. Schnack

The short range repulsion between nucleons is treated by a unitary correlation operator which shifts the nucleons away from each other whenever their uncorrelated positions are within the replusive core. By formulating the correlation as a transformation of the relative distance between particle pairs, general analytic expressions for the correlated wave fun

R. V. Jolos, A. I. Muminov, A. K. Nasirov

The role of the entrance channel in the fusion-fission reactions leading to nearly the same superheavy compound nucleus is studied in the framework of dynamic model. The calculations are done for $^{48}$Ca + $^{244}$Pu and $^{74,76}$Ge + $^{208}$Pb reactions which could lead to formation of superheavy element Z=114. It is shown that for these reactions there

Terence Tao

We prove local well-posedness results for the semi-linear wave equation for data in $H^γ$, $0 < γ< \frac{n-3}{2(n-1)}$, extending the previously known results for this problem. The improvement comes from an introduction of a two-scale Lebesgue space $X^{r,p}_k$.

L. R. Baboukhadia, A. A. Khelashvili, N. A. Kiknadze

It is shown that, in QED$_{3}$, the Pauli-Villars regularization involving a pair of auxiliary fermion fields with masses of opposite sign leads to results that are consistent with those obtained using all other parity-preserving schemes of regularization. At the same time, ambiguity problems remain unsolved in non-Abelian models (QCD$_{3}$).

N. Berkovits, M. M. Leite

Using the manifestly spacetime supersymmetric description of the four-dimensional open superstring, we construct the vertex operator in superspace for the first massive state. This construction provides an N=1 D=4 superspace representation of the massive spin-2 multiplet.

Wolfgang Lerche

We show how certain non-perturbative superpotentials W, which are the two-dimensional analogs of the Seiberg-Witten prepotential in 4d, can be computed via geometric engineering from 4-folds. We analyze an explicit example for which the relevant compact geometry of the 4-fold is given by $P^1$ fibered over $P^2$. In the field theory limit, this gives an effe

J. M. Gracia-Bondia, B. Iochum, T. Schucker

The link between chirality in the fermion sector and (anti-)self-duality in the boson sector is reexamined in the light of Connes&#39; noncommutative geometry approach to the Standard Model. We find it to impose that the noncommutative Yang-Mills action be symmetrized in an analogous way to the Dirac-Yukawa operator itself.

Alfredo T. Suzuki, Alexandre G. M. Schmidt

In this work we calculate two two-loop massless Feynman integrals pertaining to self-energy diagrams using NDIM (Negative Dimensional Integration Method). We show that the answer we get is 36-fold degenerate. We then consider special cases of exponents for propagators and the outcoming results compared with known ones obtained via traditional methods.

L. O&#39;Raifeartaigh, V. V. Sreedhar

The path integral description of the Wess-Zumino-Witten $\to$ Liouville reduction is formulated in a manner that exhibits the conformal invariance explicitly at each stage of the reduction process. The description requires a conformally invariant generalization of the phase space path integral methods of Batalin, Fradkin, and Vilkovisky for systems with firs

Cl. Gabriel, M. Rooman, Ph. Spindel

We describe solutions of type IIA (N=2, D=10) supergravity built under the assumption of the existence of at least one residual chiral supersymmetry. Their geometry is of pp-wave type. Explicit parametrization of the metric and matter field components, in terms of Killing spinors and arbitrary functions, is provided.

A. Niégawa

Through introducing a notion of renormalization of particle-number density, a simple perturbation scheme of nonequilibrium quantum-field theory is proposed. In terms of the renormalized particle-distribution functions, which characterize the system, the structure of the scheme (and then also the structure of amplitudes and reaction rates) are the same as in

P. Suranyi

Gauge theories induced by scalars in the fundamental representation of the $U(N_c)_{gauge}\times U(N_f)_{global}$ group are investigated in the large $N_c$ and $N_f$ limit. A master field is defined from bilinears of the scalar field following an Eguchi-Kawai type reduction of spacetime. The density function for the master field satisfies an integral equatio

Francesco Vissani

The hierarchy problem of the scalar sector of the standard model is reformulated, emphasizing the role of experimental facts that may suggest the existence of a new physics large mass scale, for instance indications of the instability of the matter, or indications in favor of massive neutrinos. In the see-saw model for the neutrino masses a hierarchy problem

Patricia Ball

I review currently discussed methods to determine the CKM mixing matrix element $|V_{ub}|$ from experimental data. Although the theory of inclusive decays and their spectra has entered a model-independent stage, its predictions are still sensitive to various input parameters, in particular the poorly known $b$ quark mass. At present, determinations from excl

F. M. Renard, C. Verzegnassi

It is shown that, at a 500 GeV LC, a number of different theoretical models would be unambigously identified by their virtual effects. Negative limits in case of no signal identification are also derived.

Ulf-G. Meißner

I review the present status of three flavor baryon chiral perturbation theory in the heavy fermion formalism. It is argued that precise calculations have to include all terms quadratic in the quark masses. As examples, I consider the chiral expansion of the octet baryon masses, the baryon magnetic moments and kaon photoproduction off nucleons.

B. J. Nauta, Ch. G. van Weert

We discuss the extension of dimensional reduction in thermal field theory at high temperature to real-time correlation functions. It is shown that the perturbative corrections to the leading classical behavior of a scalar bosonic field theory are determined by an effective contour propagator. On the real-time-branch of the time-path contour the effective pro

Feng Yuan, Cong-Feng Qiao, Kuang-Ta Chao

J/psi production in top quark rare decays is investigated under the framework of NRQCD factorization formalism. Various production channels are studied, and we find that the contributions from the color-singlet quark fragmentation and the color-octet gluon fragmentation are both over 3 orders larger than that from the leading order color-singlet process. The

G. Burdman, F. Halzen, R. Gandhi

It has been argued that the observations of cosmic particles with energies in excess of $10^8$ TeV represent a puzzle. Its solution requires new astrophysics or new particle physics. We show that the latter is unlikely given that the scale associated with a new particle physics threshold must be of order 1 GeV, not TeV and above, in order to resolve the prob

F. Karsch, E. Laermann, M. Oevers, P. Schmidt

We present first results of a study of two flavour QCD with Wilson fermions at finite temperature. We have used tree level Symanzik improvement in both the gauge and fermion part of the action. In a first step we explore the phase diagramm on an $8^3 \times 4$ lattice, with particular emphasis on checking Aoki&#39;s conjecture with an improved action.

Shoichi Sasaki, Osamu Miyamura

We study topological aspects of the QCD vacuum structure in SU(2) lattice gauge theory with the abelian gauge fixing. The index of the Dirac operator is measured by using the Wilson fermion in the quenched approximation. We find chiral-asymmetric zero modes in background fields dominated by QCD-monopoles without any cooling.

Joao D. Correia, John F. Wheater

A model of complex spins (corresponding to a non-minimal model in the language of CFT) coupled to the binary branched polymer sector of quantum gravity is considered. We show that this leads to new behaviour.

N. S. Ananikian, S. K. Dallakian, N. Sh. Izmailian, K. A. Oganessyan

We investigate the Z(2) gauge model on a generalized Bethe lattice with three plaquette representation of the action. We obtain the cascade of phase transitions according to Feigenbaum scheme leading to chaotic states for some values of parameters of the model. The duality between this gauge model and three site Ising spin model on Husimi tree is shown. The

J. B. Kogut, J. F. Lagae, D. K. Sinclair

We extend our earlier results concerning the breaking of the U_A(1) symmetry in finite temperature QCD. In particular, we use topological arguments to investigate the chiral limit.

Wataru Ootani, Makoto Minowa, Takayuki Watanabe, Yutaka Ito

The First results of the Tokyo dark matter search programme using a 21-g lithium fluoride bolometer are presented. The background spectrum was measured in the surface laboratory. We derive an exclusion plot for the spin-dependently coupled Weakly Interacting Massive Particles (WIMPs) cross section.

John T. Whelan

Construction of skeletonized path integrals for a particle moving on a curved spatial manifold is considered. As shown by DeWitt, Kuchar and others, while the skeletonized configuration space action can be written unambiguously as a sum of Hamilton principal functions, different choices of the measure will lead to different Schrodinger equations. On the othe

A. J. Millis, S. M. Grivin, L. B. Ioffe, A. I. Larkin

We present fermi liquid expressions for the low temperature behavior of the superfluid stiffness, explain why they differ from those suggested recently by Lee and Wen, and discuss their applicability to data on high-$T_c$ superconductors. We find that a consistent description requires a strong, doping dependent anisotropy, which affects states near the zone

Andrey V. Chubukov

We present the theory of the leading edge gap in the normal state of underdoped high-$T_c$ materials. The consideration is based on a magnetic scenario for cuprates. We show that as doping decreases, the increasing interaction with paramagnons gives rise to a near destruction of the Fermi liquid and this in turn yields precursors to $d-$wave pairing. We argu

Carson C. Chow

We examine analytically the existence and stability of phase-locked states in a weakly heterogeneous neuronal network. We consider a model of N neurons with all-to-all synaptic coupling where the heterogeneity is in the firing frequency or intrinsic drive of the neurons. We consider both inhibitory and excitatory coupling. We derive the conditions under whic

Muktish Acharyya

The dynamics of a random (quenched) field Ising model (in two dimension) at zero temperature in the presence of an additional sinusoidally oscillating homogeneous (in space) magnetic field has been studied by Monte Carlo simulation using the Metropolis single spin flip dynamics. The instantaneous magnetisation is found to be periodic with the same periodicit

T. Böske, K. Maiti, O. Knauff, K. Ruck

We present an experimental study of the dynamics of holes in the valence bands of 0, 1, and 2 dimensional undoped model cuprates, as expressed via the screening of a Cu 2p core hole. The response depends strongly upon the dimensionality and the details of the Cu-O-Cu network geometry and clearly goes beyond the present theoretical state-of-the-art descriptio

C. J. Olson, C. Reichhardt, Franco Nori

Using large-scale simulations on parallel processors, we analyze in detail the dynamical behavior of superconducting vortices undergoing avalanches. In particular, we quantify the effect of the pinning landscape on the macroscopic properties of vortex avalanches and vortex plastic flow. These dynamical instabilities are triggered when the external magnetic f

A. J. Bray, P. N. Rapapa, S. J. Cornell

The leading correction to scaling associated with departures of the initial condition from the scaling morphology is determined for some soluble models of phase-ordering kinetics. The result for the pair correlation function has the form C(r,t) = f_0(r/L) + L^{-ω} f_1(r/L) + ..., where L is a characteristic length scale extracted from the energy. The correct

P. G. Akishin, M. V. Altaisky, A. D. Budnik, V. V. Ivanov

The seismic processes are well known to be self-similar in both spatial and temporal behavior. At the same time, the Burridge-Knopoff (BK) model of earthquake fault dynamics, one of the basic models of theoretical seismicity, does not posses self-similarity. In this article an extension of BK model, which directly accounts for the self-similarity of earth cr

Eli Waxman, Shri R. Kulkarni, Dale A. Frail

Radio observations of the afterglow of the gamma-ray burst GRB970508 provide unique new constraints on afterglow models. The quenching of diffractive scintillation at 4 week delay provides the first direct estimate of source size and expansion rate. It implies an apparent size $R\sim10^{17}$cm and expansion at a speed comparable to that of light at 4 weeks d

T. Yaqoob, B. McKernan, A. Ptak, K. Nandra

We present a new, simple method for analysing gapped time-series which is particularly suited to probe the X-ray power spectra of active galactic nuclei (AGN).The method is applied to a four-day observation of the Seyfert 1 galaxy MCG -6-30-15 with ASCA. MCG -6-30-15 is well-known for rapid, large amplitude X-ray variability. In this source, our method probe

J. Christopher Howk, Blair D. Savage

We present high-resolution (<0.65&#34;) optical broad-band images of the edge-on Sb galaxy NGC 891 obtained with the WIYN 3.5-m telescope. These BVR images reveal a complex network of hundreds of dust absorbing structures far from the mid-plane of the galaxy. The dust structures have a wide range of morphologies and are clearly visible to |z|<1.5 kpc from th

Y. K. Ng

An overview is given of the results obtained about Galactic Structure studies towards the Galactic Centre from star counts. The results indicate the presence of an old, metal-rich population (Z=0.005-0.08; t=13-15 Gyr), presumably the old Galactic Bulge. In addition, a younger, less metal-rich population was found (Z=0.005-0.03}; t=8-9 Gyr), likely related t

P. N. Best, M. S. Longair, H. J. A. R&#34;ottgering

Hubble Space Telescope images of 3CR radio galaxies at redshifts 0.6 < z < 1.8 have shown a remarkable variety of structures, generally aligned along the radio axis, indicating that the radio source strongly influences the optical appearance of these galaxies. In this paper we investigate the host galaxies underlying this aligned emission, combining the HST

F. P. Israel

H2 column densities towards CO clouds in the LMC and SMC are estimated from their far-infrared surface brightness and HI column density. N(H2)/I(CO) conversion factors are X(LMC) = 1.3 and X(SMC) = 12 (unit: 10**21 mol cm**-2 (K km/s)**-1). LMC and SMC contain total (warm) H2 masses of 1.0 and 0.75 x 10**8 M(sun) respectively. Similar local H2/HI mass ratios

Eon-Chang Sung, Cheongho Han, Barbara, S. Ryden

We measure the apparent shapes for a sample of 62 blue compact dwarf galaxies (BCDs), and compare them with the apparent shapes for a sample of 80 dwarf elliptical galaxies (dEs). The BCDs are flatter, on average, than the dEs, but the difference is only marginally significant. We then use both non-parametric and parametric techniques to determine possible d

L. Raul Abramo

We study the back reaction of cosmological perturbations on the evolution of the universe. The object usually employed to describe the back reaction of perturbations is called the effective energy-momentum tensor (EEMT) of cosmological perturbations. In this formulation, the problem of the gauge dependence of the EEMT must be tackled. We advance beyond tradi

Mark B. Wise

Applications of HQET and NRQCD to fragmentation are briefly reviewed. The special role of the b-quark in applications of heavy quark symmetry is discussed. Predictions of HQET for semileptonic B decays to excited charmed mesons are considered.

Judith G. Cohen, John P. Blakeslee, Anton Ryzhov

A subset of 150 globular clusters in M87 has been selected on the basis of S/N ratio for abundance and age determinations from the sample of Paper I. Indices measuring the strength of the strongest spectral features were determined for the M87 GCs and from new data for twelve galactic GCs. Combining the new and existing data for the galactic GCs and comparin

H. A. Fertig

A microscopic model for analyzing the microwave absorption properties of a pinned, two-dimensional Wigner crystal in a strong perpendicular magnetic field is developed. The method focuses on excitations within the lowest Landau level, and corresponds to a quantum version of the harmonic approximation. For pure systems (no disorder), the method reproduces kno

Tohru Koma, Bruno Nachtergaele

We show that the well-known translation invariant ground states and the recently discovered kink and antikink ground states are the complete set of pure infinite-volume ground states (in the sense of local stability) of the spin-S ferromagnetic XXZ chains with Hamiltonian H=-sum_x [ S^1_x S^1_{x+1} + S^2_x S^2_{x+1} + Delta S^3_x S^3_{x+1} ], for all Delta >

C. Nash

This is an article on the interaction between topology and physics which will appear in 1998 in a book called: A History of Topology, edited by Ioan James and published by Elsevier-North Holland.

L. V. Avdeev, D. I. Kazakov, I. N. Kondrashuk

The supergraph technique for calculations in supersymmetric gauge theories where supersymmetry is broken in a &#34;soft&#34; way (without introducing quadratic divergencies) is reviewed. By introducing an external spurion field the set of Feynman rules is formulated and explicit connections between the UV counterterms of a softly broken and rigid SUSY theori

Adam D. Helfer

I show that a quantized Klein-Gordon field in Minkowski space obeys an `operational&#39; weak energy condition: the energy of an isolated device constructed to measure or trap the energy in a region, plus the energy it measures or traps, cannot be negative. There are good reasons for thinking that similar results hold locally for linear quantum fields in cur

A. Iarrobino, J. Yameogo

The nonsingular variety G_T parametrizes all graded ideals I of R=k[x,y] for which the Hilbert function H(R/I)=T. The variety G_T has a natural cellular decomposition: each cell V(E) corresponds to a monomial ideal E for which H(R/E)=T. Given a monomial ideal E, the quotient R/E has a basis of monomials in the shape of a partition P(E), having &#34;diagonal

Gautam Bhattacharyya

I review the upper limits on the R-parity-violating Yukawa couplings from indirect searches. Some limits have been updated using recent data.

Jens Hoppe

For the SU(N) invariant supersymmetric matrix model related to membranes in 4 space-time dimensions, the general solution to the equation(s) $Q^{\dagger}Ψ=0$ $(Qχ=0)$ is determined for N odd. For any such (bosonic) solution of $Q^{\dagger}Ψ=0$, a (fermionic) $Φ$ is found that (formally) satisfies $Q^{\dagger}Φ=Ψ$. For the analogous model in 11 dimensions the

Thierry Cretegny, Thierry Dauxois, Stefano Ruffo, Alessandro Torcini

The evolution towards equipartition in the $β$-FPU chain is studied considering as initial condition the highest frequency mode. Above an analytically derived energy threshold, this zone-boundary mode is shown to be modulationally unstable and to give rise to a striking localization process. The spontaneously created excitations have strong similarity with m

Yuri B. Suris

We develop the approach to the problem of integrable discretization based on the notion of $r$--matrix hierarchies. One of its basic features is the coincidence of Lax matrices of discretized systems with the Lax matrices of the underlying continuous time systems. A common feature of the discretizations obtained in this approach is non--locality. We demonstr

Biswarup Mukhopadhyaya, Sourov Roy

We investigate the signal $γγ$ + missing energy in a high-energy linear $e^+e^-$ collider, with a view to differentiating between gauge-mediated supersymmetry breaking and the conventional supersymmetric models. Prima facie, there is considerable chance of confusion between the two scenarios if the assumption of gaugino mass unification is relaxed. We show t

D. A. Smith, V. S. Dhillon, T. R. Marsh

We present spectrophotometry of the eclipsing old nova BT Mon (Nova Mon 1939). By detecting weak absorption features from the secondary star, we find its radial velocity semi-amplitude to be K_R = 205+/-5 km/s and its rotational velocity to be vsin i = 138+/-5 km/s. We also measure the radial velocity semi-amplitude of the primary star to be K_R = 170+/-10 k

M. Fukugita, M. Tanimoto, T. Yanagida

We propose simple phenomenological lepton mass matrices which describe the three neutrinos almost degenerate in mass, leading to a very large mixing angle between $ν_μ$ and $ν_τ$, as consistent with a recent report on atmospheric neutrino oscillation from the Superkamiokande collaboration. Our matrix model also gives $ν_e-ν_μ$ mixing in agreement with the va

M. S. Baek, Jungil Lee, Chun Liu, H. S. Song

At the order of 1/m_b^3, the B meson lifetimes are controlled by the hadronic matrix elements of some four-quark operators. The nonfactorizable magnitudes of these four-quark operator matrix elements are analyzed by QCD sum rules in the framework of heavy quark effective theory. The vacuum saturation for color-singlet four-quark operators is justified at had

Shuichi Murakami, Frank Göhmann

We develop the quantum inverse scattering method for the one-dimensional Hubbard model on the infinite line at zero density. This enables us to diagonalize the Hamiltonian algebraically. The eigenstates can be classified as scattering states of particles, bound pairs of particles and bound states of pairs. We obtain the corresponding creation and annihilatio

Q. P. Liu, Manuel Manas

Sequences of discrete Levy and adjoint Levy transformations for the multidimensional quadrilateral lattices are studied. After a suitable number of iterations we show how all the relevant geometrical features of the transformed quadrilateral lattice can be expressed in terms of multi-Casorati determinants. As an example we dress the Cartesian lattice.

Boris F. Samsonov

Coordinate atypical representation of the orthosymplectic superalgebra osp(2/2) in a Hilbert superspace of square integrable functions constructed in a special way is given. The quantum nonrelativistic free particle Hamiltonian is an element of this superalgebra which turns out to be a dynamical superalgebra for this system. The supercoherent states, defined

Vladislav G. Bagrov, Boris F. Samsonov

The well-known supersymmetric constructions such as Witten&#39;s supersymmetric quantum mechanics, Spiridonov-Rubakov parasupersymmetric quantum mechanics, and higher-derivative SUSY of Andrianov et al. are extended to the nonstationary Schrödinger equation. All these constructions are based on the time-dependent Darboux transformation. The superalgebra over

Boris F. Samsonov, L. A. Shekoyan

New exactly solvable quantum models are obtained with the help of the supersymmetric extencion of the nonstationary Schr/&#34;odinger equation.

C. Fronsdal, A. Galindo

We study the vertex operators $Φ(z)$ associated with standard quantum groups. The element $Z = RR^{t}$ is a &#34;Casimir operator&#34; for quantized Kac-Moody algebras and the quantum Knizhnik-Zamolodchikov (q-KZ) equation is interpreted as the statement $:ZΦ(z): = Φ(z)$. We study the covariance of the q-KZ equation under twisting, first within the category

G. Thorleifsson, M. Falcioni

The physics of crystalline membranes, i.e. fixed-connectivity surfaces embedded in three dimensions and with an extrinsic curvature term, is very rich and of great theoretical interest. To understand their behavior, numerical simulations are commonly used. Unfortunately, traditional Monte Carlo algorithms suffer from very long auto-correlations and critical

Edward Odell, Thomas Schlumprecht

It is shown that a separable Banach space $X$ can be given an equivalent norm $|\!|\!|\cdot |\!|\!|$ with the following properties:\quad If $(x_n)\subseteq X$ is relatively weakly compact and $\lim_{m\to\infty} \lim_{n\to\infty}\break |\!|\!| x_m + x_n |\!|\!| = 2\lim_{m\to\infty} |\!|\!| x_m|\!|\!|$ then $(x_n)$ converges in norm. This yields a characteriza

S. Gukov

As another evidence for the matrix Discrete Light Cone formulation of M theory, we show how general integrable Hamiltonian systems emerge from BPS bound states of k longitudinal fivebranes. Such configurations preserve eight supercharges and by chain of dualities can be related to the solution of N=2 four-dimensional gauge theories. Underlying Hitchin system

M. A. Shifman, M. B. Voloshin

A family of degenerate domain wall configurations, partially preserving supersymmetry, is discussed in a generalized Wess-Zumino model with two scalar superfields. We establish some general features inherent to the models with continuously degenerate domain walls. For instance, for purely real trajectories additional &#34;integrals of motion&#34; exist. The

Viktor Dotsenko, Vladimir Dotsenko, Marco Picco

Averaged spin-spin correlation function squared $\overline{<σ(0)σ(R)>^{2}}$ is calculated for the ferromagnetic random bond Potts model. The technique being used is the renormalization group plus conformal field theory. The results are of the $ε$ - expansion type fixed point calculation, $ε$ being the deviation of the central charge (or the number of compone

V. D. Skarzhinsky, J. Audretsch, Ulf. Jasper

In the framework of QED we evaluate the cross section for electron-positron pair production by a single photon in the presence of the external Aharonov-Bohm potential in first order of perturbation theory. We analyse energy, angular and polarization distributions at different energy regimes: near the threshold and at high photon energies.

J. Audretsch, Ulf. Jasper, V. D. Skarzhinsky

We investigate the scattering of an electron by an infinitely thin and infinitely long straight magnetic flux tube in the framework of QED. We discuss the solutions of the Dirac and Maxwell fields in the related external pure AB potential and evaluate matrix elements and differential probabilities for the bremsstrahlung process. The dependence of the resulti

Eduardo Ramos

The reduced covariant phase space associated with the three-dimensional Euclidean Nambu-Goto action can be identified, via the Enneper-Weierstrass representation of minimal surfaces, with the space of complex analytic functions plus three translational zero modes. The symplectic structure induced trough the Enneper-Weierstrass map can be explicitly computed.

S. A. Garnov

The 3-loop effective action and effective potential in Nambu - Jona-Lasinio model are calculated. The problem of vanishing contributions in the higher orders is discussed. The general form of such contributions is obtained.

Zoltan Ligeti

Exclusive semileptonic B decays to the lightest excited charmed mesons are investigated at order $Λ_{QCD}/m_Q$ in the heavy quark effective theory. At zero recoil, $Λ_{QCD}/m_Q$ corrections to the matrix elements of the weak currents can be written in terms of the leading Isgur-Wise functions for the corresponding transition and meson mass splittings. The di

K. Suzuki, T. Shigetani

We study the chiral-odd transversity spin-dependent quark distribution function $h_1 (x)$ of the nucleon in a constituent quark model. The twist-2 structure functions, $f_1(x)$, $g_1(x)$ and $h_1(x)$ are calculated within the diquark spectator approximation. Whereas an inequality $f_1(x) > h_1(x) > g_1(x)$ holds with the interaction between quark and diquark

Peter Kroll

The role of power corrections and higher Fock-state contributions to exclusive charmonium decays will be discussed. It will be argued that the J/Psi (Psi&#39;) decays into baryon-antibaryon pairs are dominated by the valence Fock-state contributions. P-wave charmonium decays, on the other hand, receive strong contributions from the c cbar g Fock states since

N. D. Hari Dass, V. Soni

We show that a recently proposed extension of QCD by the addition of a multiplet of scalars transforming as (2,2,1) under $SU(2)_L\times SU(2)_R\times SU(3)_ {colour}$ provides a natural and parameter-free explanation for many observed features of the excess 4 jet events reported by ALEPH.

Marcello Ciafaloni

I review recent results by Fadin,Lipatov and collaborators and by our group,leading to the almost complete calculation of the next-to-leading BFKL kernel,of its eigenvalues,and of the resummed gluon anomalous dimension. Qualitative implications for small-x structure functions include consistent running coupling effects and a sizeable decrease of the Pomeron

J. Layssac, F. M. Renard, C. Verzegnassi

We have computed the contribution to the observables of the final two fermion channel at LEP2, at the limiting energy $\sqrt{q^2}=200 GeV$, coming from boxes with two neutralinos of purely gaugino type, of mass $M=100 GeV$. We find a potentially visible effect only for the muon channel, in the cross section and, to a lesser extent, in the forward-backward as

Krzysztof Pachucki, Savely G. Karshenboim

We have completed theoretical predictions for positronium energy levels through order alpha^6 m by the calculation of the spin independent, radiative recoil correction. This contribution is significant and amounts to 10.64 MHz for the 1S state. We further perform detailed comparison of theoretical predictions to experimental results for 1S-2S and 2S-2P trans

Alan R. White

Workshop presentations on elastic and diffractive scattering and other recent advances in hadron physics are summarized. The role of ``factorization&#39;&#39; in determining parton properties of the pomeron is particularly discussed.

Pierre van Baal

We review issues involved in understanding the vacuum, long-distance and low-energy structure of non-Abelian gauge theories and QCD. The emphasis will be on the role played by instantons.

U. M. Heller, F. Karsch, J. Rank

From the long-distance behaviour of gluon and Polyakov loop correlation functions we extract masses resp. energies in the electric and magnetic sectors. We discuss their dependence on the temperature and on the momentum as well as the relevance of an improvement of the lattice discretization of the action.

G. Damm, W. Kerler, V. K. Mitrjushkin

We investigate the propagators of 4D SU(2) gauge theory in Landau gauge by Monte Carlo simulations. To be able to compare with perturbative calculations we use large $β$ values. There the breaking of the Z(2) symmetry causes large effects for all four lattice directions and doing the analysis in the appropriate state gets important. We find that the gluon pr

J. Ambjorn, K. N. Anagnostopoulos, T. Ichihara, L. Jensen

We couple c=-2 matter to 2-dimensional gravity within the framework of dynamical triangulations. We use a very fast algorithm, special to the c=-2 case, in order to test scaling of correlation functions defined in terms of geodesic distance and we determine the fractal dimension d_H with high accuracy. We find d_H=3.58(4), consistent with a prediction coming

F. Gliozzi

It is pointed out that one-component ϕ^4 lattice theory in four dimensions has a non-perturbative sector which can be studied by means of an exact duality transformation of its Ising limit. This duality maps it to a membrane model. As a consequence, the ϕ^4-theory turns out to have, in the broken symmetry phase, a remarkably rich spectrum of physical states

G. Damm, W. Kerler

We investigate critical properties of the phase transition in the four-dimensional compact U(1) lattice gauge theory supplemented by a monopole term for values of the monopole coupling $λ$ such that the transition is of second order. It has been previously shown that at $λ= 0.9$ the critical exponent is already characteristic of a second-order transition and

D. Espriu, V. Koulovassilopoulos, A. Travesset

We study the phase diagram of the $U(2) \times U(2)$ scalar model in $d=4$ dimensions. We find that the phase transition is of first order in most of the parameter space. The theory can still be relevant to continuum physics (as an effective theory) provided the transition is sufficiently weakly first order. This places restrictions on the allowed coupling c

Jan C. Plefka, Stuart Samuel

A theta-term, which couples to topological charge, is added to the two-dimensional lattice CP^3 model and U(1) gauge theory. Monte Carlo simulations are performed and compared to strong-coupling character expansions. In certain instances, a flattening behavior occurs in the free-energy at sufficiently large theta, but the effect is an artifact of the simulat

S. Aoki, K. Nagai, S. V. Zenkin

We analyse stability of almost massless Dirac mode in gauge models with boundary (domain wall) fermions, and consider the possibility of decoupling one of its chiral component by giving it a Majorana mass of the order of the inverse lattice spacing. We argue that the chiral spectrum in such models is always uncharged, so they can be implemented for defining