July 1997 arXiv papers — page 13

D. V. Antonov, D. Ebert

Perturbation theory in the nonperturbative QCD vacuum and the non-Abelian Stokes theorem, representing a Wilson loop in the SU(2) gluodynamics as an integral over all the orientations in colour space, are applied to a derivation of the correction to the string effective action in the lowest order in the coupling constant $g$. This correction is due to the in

Jan Ambjorn, Domenec Espriu, Naoki Sasakura

We discuss the physics of four-dimensional compact U(1) lattice gauge theory from the point of view of softly broken N=2 supersymmetric SU(2) Yang-Mills theory. We provide arguments in favor of (pseudo-)critical mass exponents 1/3, 5/11 and 1/2, in agreement with the values observed in the computer simulations. We also show that the J^{CP} assignment of some

M. Bonini, F. Vian

We extend the Wilson renormalization group (RG) formulation to chiral gauge theories and show that local gauge symmetry can be implemented by a suitable choice of the RG flow boundary conditions. Since the space-time dimension is four, there is no ambiguity in handling the matrix $\g_5$ and left and right fermions are not coupled. As a result the ultraviolet

L. D. Paniak

In a solvable model of two dimensional SU(N) (N \to \infty) gauge fields interacting with matter in both adjoint and fundamental representations we investigate the nature of the phase transition separating the strong and weak coupling regions of the phase diagram. By interpreting the large N solution of the model in terms of SU(N) representations it is shown

Michael Luke, Martin J. Savage

We present a scheme for calculating in NRQCD with consistent power counting in the heavy quark velocity v. As an example, we perform the systematic matching of an external current onto NRQCD at subleading order in v, a calculation relevant for the process e^+e^- -> hadrons near threshold. Consistent velocity power counting in dimensional regularization is ac

Masaki Yasue

Properties of extra weak bosons are discussed in a gauge model based on SU(2)_LXU(1)_YXSU(2)'_L. The physics of SU(2)'_L respects the duality in the Higgs and confining phases, where massive gauge bosons in the Higgs phase are equivalently represented by composite vector bosons in the confining phase below the scale of SU(2)'_L . interactions for

Alon E. Faraggi

The objective of superstring phenomenology is to develop the models and methodology needed to connect quantitatively between Planck scale physics and electroweak scale experimental data. I review the present status of this endeavor with a focus on the three generation free fermionic models.

D. Kharzeev, M. Nardi, H. Satz

We study the characteristic features of J/Psi suppression by deconfinement. A first order phase transition leads to an essentially discontinuous onset of anomalous J/Psi suppression. The different energy densities required for the dissociation of different charmonium states result in a two-step suppression pattern, in which first the J/Psi's from chi dec

D. Jido, M. Oka, A. Hosaka

Meson-baryon couplings between positive and negative parity baryons are investigated using two point correlation functions in the soft meson limit. We find that the pi NN^* coupling vanishes due to chiral symmetry, while the eta NN^* coupling remains finite. We perform an analysis based on the algebraic method for SU(2) and SU(3) chiral symmetry, and find th

Alexander Kusenko

Q-balls are generically present in models with softly broken low-energy supersymmetry. We discuss the properties of these non-topological solitons, which can precipitate a new kind of first-order phase transition in the early Universe and have other important implications for cosmology and experiment.

B. Ananthanarayan, P. Buttiker

A family of threshold parameters which probe the stability of chiral predictions is considered. The relevant criteria for the choice of threshold parameters are discussed. Sum rules for these quantities are derived from dispersion relations and evaluated from effective range formulae. Good agreement with two-loop chiral estimates for many of these quantities

Tadeusz Wibig

In the paper the extension of the Geometrical Two-Chain model to higher energies is presented. The agreement with experimental data is achieved using pre-hadronization chain breakups due to coloured dipole radiation mechanism and the discretization of the soft gluon emission process.

Greg Kilcup, Rajan Gupta, Stephen Sharpe

We investigate the use of two kinds of staggered fermion operators, smeared and unsmeared. The smeared operators extend over a $4^4$ hypercube, and tend to have smaller perturbative corrections than the corresponding unsmeared operators. We use these operators to calculate kaon weak matrix elements on quenched ensembles at $β=6.0$, 6.2 and 6.4. Extrapolating

The OPAL Collaboration, K. Ackerstaff et al

We have searched for decays of the tau lepton into seven or more charged particles, using data collected with the OPAL detector from 1990 to 1995 in e^+e^- collisions at sqrt(s) ~ M_Z. No candidate events were found and an upper limit on the branching ratio for tau decays into seven charged particles of 1.8 x 10^-5 at the 95% confidence level was determined.

Luis A. Anchordoqui, A. G. Grunfeld, Diego F. Torres

A simple Lorentzian vacuum wormhole solution of Brans-Dicke gravitation is presented and analysed. It is shown that such solution holds for both, the Brans-Dicke theory endowed with torsion (for a value of the coupling parameter $ω> 1/2$) and for the vacuum -no torsion- case (for $ω< -2$).

William A. Hiscock

The expectation value of the stress-energy tensor of a free conformally invariant scalar field is computed in a two-dimensional reduction of the Alcubierre ``warp drive&#39;&#39; spacetime. The stress-energy is found to diverge if the apparent velocity of the spaceship exceeds the speed of light. If such behavior occurs in four dimensions, then it appears im

Pietro Menotti

We show that the structure of the Liouville action on a two dimensional Regge surface of the topology of the sphere and of the torus is determined by the invariance under the transformations induced by the conformal Killing vector fields and under modular transformations.

Peter K. S. Dunsby

Starting from the exact non-linear description of matter and radiation, a fully covariant and gauge-invariant formula for the observed temperature anisotropy of the cosmic microwave background (CBR) radiation, expressed in terms of the electric ($E_{ab}$) and magnetic ($H_{ab}$) parts of the Weyl tensor, is obtained by integrating photon geodesics from last

Wolfgang Lueck

We define for arbitrary modules over a finite von Neumann algebra $\cala$ a dimension taking values in $[0,\infty]$ which extends the classical notion of von Neumann dimension for finitely generated projective $\cala$-modules and inherits all its useful properties such as additivity, cofinality and continuity. This allows to define $L^2$-Betti numbers for ar

Wolfgang Lueck, Thomas Schick, Thomas Thielmann

We study the behaviour of analytic torsion under smooth fibrations. Namely, let F \to E \to^{f} B be a smooth fiber bundle of connected closed oriented smooth manifolds and let $V$ be a flat vector bundle over $E$. Assume that $E$ and $B$ come with Riemannian metrics and $V$ comes with a unimodular (not necessarily flat) Riemannian metric. Let $ρ_{an}(E;V)$

Christian Baer

We prove that the nodal set (zero set) of a solution of a generalized Dirac equation on a Riemannian manifold has codimension 2 at least. If the underlying manifold is a surface, then the nodal set is discrete. We obtain a quick proof of the fact that the nodal set of an eigenfunction for the Laplace-Beltrami operator on a Riemannian manifold consists of a s

J. Eichhorn

On an open manifold, the spaces of metrics or connections of bounded geometry, respectively, split into an uncountable number of components. We show that for a pair of metrics or connections, belonging to the same component, relative $ζ$-functions, determinants, torsion for pairs of generalized Dirac operators are well defined.

Jean Paul Dufour, Nguyen Tien Zung

We classify linear Nambu structures (which are generalized Poisson structures in Hamiltonian dynamics and which give rise to integrable differential forms and singular foliations), then give a linearization for Nambu structures anf integrable differential forms near a nondegenerate singular point.

D. Sornette, J. V. Andersen

We revisit a simple dynamical model of rupture in random media with long-range elasticity to test whether rupture can be seen as a first-order or a critical transition. We find a clear scaling of the macroscopic modulus as a function of time-to-rupture and of the amplitude of the disorder, which allows us to collapse neatly the numerical simulations over mor

Pengcheng Dai, H. A. Mook, F. Dogan

We use inelastic neutron scattering to demonstrate that at low temperatures, the low frequency magnetic fluctuations in YBa_2Cu_3O_{6.6} ($T_c=62.7$ K) are incommensurate, being found at positions displaced by $\pmδ$ ($0.057\pm 0.006$ r.l.u.) along the $[π,π]$ direction from the wave vector $(π,π)$ associated with the antiferromagnetic order of the parent in

Martin Bonsager, Karsten Flensberg, Ben Yu-Kuang Hu, Allan H. MacDonald

We use the Kubo formalism to evaluate the contribution of acoustic phonon exchange to the frictional drag between nearby two-dimensional electron systems. In the case of free phonons, we find a divergent drag rate ($τ_{D}^{-1}$). However, $τ_{D}^{-1}$ becomes finite when phonon scattering from either lattice imperfections or electronic excitations is account

Robert M. Ziff, Paul N. Suding

The hull-gradient method is used to determine the critical threshold for bond percolation on the two-dimensional Kagome lattice (and its dual, the dice lattice). For this system, the hull walk is represented as a self-avoiding trail, or mirror-model trajectory, on the (3,4,6,4)-Archimedean tiling lattice. The result pc = 0.524 405 3(3) (one standard deviatio

F. Becca, F. Bucci, M. Grilli

The infinite-U three-band Hubbard model is considered in order to describe the CuO_2 planes of the high temperature superconducting cuprates. The charge instabilities are investigated when the model is extended with a nearest-neighbor repulsion between holes on copper d and oxygen p orbitals and in the presence of a long-range Coulombic repulsion. It is foun

Michael Brunner, Alejandro Muramatsu

Numerical simulations of the two-dimensional t-J model in the limit $J/t \ll 1$ are performed for rather large systems (up to $N = 12 \times 12$) using a world-line loop-algorithm. It is shown that in the one-hole case with J=0, where no minus signs appear, very low temperatures ($βt \sim 3000$) are necessary in order to reach Nagaoka&#39;s state. $J/t \ltsi

A. B. Kuz&#39;menko, E. A. Tishchenko, A. S. Krechetov

An extension of the Kramers-Kronig method for treatment of polarized infrared reflectance spectra from the face of low-symmetry crystals, where directions of principal dielectric axes depend on frequency, is proposed. It is shown, how to obtain the frequency dependencies of the complex reflectivity tensor components, using three reflectance spectra measured

D. C. Brody, A. Ritz

Using real-space renormalisation techniques we analyse the Ising model on a Sierpiński gasket with anisotropic microscopic couplings, and observe a restoration of isotropy on macroscopic scales. In particular, via use of a decimation procedure directly on the fractal lattice, we calculate explicitly the exponential anisotropy decay coefficients near the isot

Antimo Angelucci, Arturo Tagliacozzo

We study a two dimensional electron system in a parabolic confining potential and constant magnetic field for the case of harmonic electron-electron interaction. We present analytic results for the electrochemical potential versus magnetic field and discuss the effects of correlation in connection with the addition energy of a Quantum Dot with few electrons.

K. B. Lauritsen, K. Sneppen, M. Markosova, M. H. Jensen

We consider directed percolation with an absorbing boundary in 1+1 and 2+1 dimensions. The distribution of cluster lifetimes and sizes depend on the boundary. The new scaling exponents can be related to the exponents characterizing standard directed percolation in 1+1 dimension. In addition, we investigate the backbone cluster and red bonds, and calculate th

J. F. Buell, R. B. C. Henry, E. Baron, K. B. Kwitter

We examine two scenarios for formation of the planetary nebula K648: a prompt scenario where the planetary nebula is ejected and formed immediately after a helium shell flash and a delayed scenario where a third dredge up occurs and the envelope is ejected during the following interpulse phase. We present models of both scenarios and find that each can produ

J. Robert Buchler

We briefly review the evolutionary status of the classical Cepheid variables, their structure, and the properties of the linear modes. Then we discuss the current status of the nonlinear hydrodynamical modelling, including modern adaptive mesh techniques, and the sensitivity to opacity. We stress the importance of resonances among the normal modes of pulsati

G. S. Bisnovatyi-Kogan

The neutron star formation during the collapse with the strong magnetic field may lead to a mirror symmetry violation and formation of an asymmetric magnetic field. Dependence of the week interaction cross-section on the magnetic field strength lead to the asymmetric neutrino flux and formation of rapidly mooving pulsars due to the recoil action as well as r

E. J. C. Bowers, W. P. S. Meikle, T. R. Geballe, N. A. Walton

We present near-infrared (NIR) spectra for Type Ia supernovae at epochs of 13 to 338 days after maximum blue light. Some contemporary optical spectra are also shown. All the NIR spectra exhibit considerable structure throughout the J-, H- and K-bands. In particular they exhibit a flux `deficit&#39; in the J-band which persists as late as 175 days. This is re

S. Corbel, R. P. Fender, P. Durouchoux, R. K. Sood

The black hole candidate GX 339-4 was first detected as a variable radio source by Sood & Campbell-Wilson in May 1994 with the Molonglo Observatory Synthesis Telescope (MOST). Since then, several observations have been obtained with the Australian Telescope Compact Array (ATCA) in order to study the radio behavior of this source in relation to its soft and h

Carla Dionisi

Let $MI_{Simp,P^{2n+1}}(k)$ be the moduli space of stable symplectic instanton bundles on $P^{2n+1}$ with second Chern class $c_2=k$ (it is a closed subscheme of the moduli space $MI_{P^{2n+1}}(k)$), We prove that the dimension of its Zariski tangent space at a special (symplectic) instanton bundle is $2k(5n-1)+4n^2-10n+3, k\geq 2$. It follows that special s

Fernando Cornet, Javier Rico

We obtain bounds on the mass scales characterizing four-fermion contact interactions in charged current processes. The bounds arise from the Q^2 and x distributions in the processes e p -> νX measured by the two HERA experiments, H1 and ZEUS.

John T. Whelan

This paper has been withdrawn, as the explicit form of the propagator can be found in: V.V.Dodonov, I.A.Malkin and V.I.Man&#39;ko, J.Phys.A 8 (1975) L19 V.V.Dodonov, I.A.Malkin and V.I.Man&#39;ko, Int.J.Theor.Phys. 14 (1975) 37, Sec.3 V.V.Dodonov, I.A.Malkin and V.I.Man&#39;ko, Theor.Math.Phys. 24 (1975) 746, Sec.2 I am grateful to Professor Victor Dodonov f

M. Alimohammadi, M. Khorrami, A. Aghamohammdi

Using the standard saddle-point method, we find an explicit relation for the large-N limit of the free energy of an arbitrary generalized 2D Yang-Mills theory in the weak ($A<A_c$) region. In the strong ($A>A_c$) region, we investigate carefully the specific fourth Casimir theory, and show that the ordinary integral equation of the density function is not ad

Kenneth Intriligator

We review some recent results concerning gauge theories in various dimensions. In particular, we discuss RG fixed points and ``mirror&#39;&#39; symmetry duality in 3d N=4 supersymmetric gauge theories and a classification of non-trivial RG fixed points in 5d N=1 supersymmetric theories.

Michael Finkelberg, Ivan Mirković

The Semiinfinite Flag Space appeared in the works of B.Feigin and E.Frenkel, and under different disguises was found by V.Drinfeld and G.Lusztig in the early 80-s. Another recent discovery (Beilinson-Drinfeld Grassmannian) turned out to conceal a new incarnation of Semiinfinite Flags. We write down these and other results scattered in folklore. We define the

P. M. H. Wilson

We investigate Gromov-Witten invariants associated to exceptional classes for primitive birational contractions on a Calabi-Yau threefold X. It was observed in a previous paper that these invariants are locally defined, in that they can be calculated from knowledge of an open neighbourhood of the exceptional locus of the contraction; in this paper, we make t

Haiqing Wei, Xin Xue, S. D. Morgera

Clusters of solid-state quantum devices have long-living metastable states of local energy minima which may be used to store quantum information. The low to vanishing rate of dissipation fulfils the prerequisite to maintain quantum coherence. Then physical symmetrization of the devices could minimize the couplings of the clusters to environmental degrees of

Gautam Bhattacharyya

If R-parity violation turns out to be a true aspect of Nature, a speculation about its possible origin could add a new dimension to the supersymmetric flavour problem. It has been shown in the past by Barbieri, Hall and their collaborators that the small breaking parameters of an approximate non-abelian flavour symmetry could govern the light quark and lepto

Andrzej Krasinski

This is the third and last part of a series of 3 papers. Using the same method and the same coordinates as in parts 1 and 2, rotating dust solutions of Einstein's equations are investigated that possess 3-dimensional symmetry groups, under the assumption that each of the Killing vectors is linearly independent of velocity $u^{\alpha}$ and rotation $w^{\alpha

M. W. Wu, E. M. Conwell

Optical excitation of a chain in a polymer film may result in formation of an excimer, a superposition of on-chain excitons and charge-transfer excitons on the originally excited chain and a neighboring chain. The excimer emission is red-shifted compared to that of an on-chain exciton by an amount depending on the interchain coupling $t_\perp$. Setting up th

M. W. Wu, E. M. Conwell

In a pair of coupled donor-acceptor conjugated polymer chains, it is possible for an exciton photoexcited on either polymer to decay into a hole in the donor polymer&#39;s valence band and an electron in the conduction band of the acceptor polymer. We calculate the corresponding exciton decay rate and its dependence on inter-polymer distance. For a pair of d

D. C. Cabra, A. Honecker, P. Pujol

Magnetization processes of spin-1/2 Heisenberg ladders are studied using strong-coupling expansions, numerical diagonalization of finite systems and a bosonization approach. We find that the magnetization exhibits plateaux as a function of the applied field at certain rational fractions of the saturation value. Our main focus are ladders with 3 legs where pl

Remi Monasson

A formalism capable of handling the first step of hierarchical replica symmetry breaking in finite-connectivity models is introduced. The emerging order parameter is claimed to be a probability distribution over the space of field distributions (or, equivalently magnetisation distributions) inside the cluster of states. The approach is shown to coincide with

Adolfo Avella, Ferdinando Mancini, Dario Villani, Hideki Matsumoto

The addition to the Hubbard Hamiltonian of a t&#39; diagonal hopping term, which is considered to be material dependent for high-Tc cuprate superconductors, is generally suggested to obtain a model capable to describe the physics of high-Tc cuprate materials. In this line of thinking, the two-dimensional t-t&#39;-U model has been studied by means of the Comp

G. Amoros, F. J. Botella, S. Noguera, J. Portoles

The D^0-D^0(bar) mixing is analyzed in a weak gauged U(4)_L x U(4)_R chiral lagrangian model where the electroweak interaction is introduced as a gauge theory over the meson degrees of freedom. This model allows a particular realization of the G.I.M. mechanism and then could be useful in the study of processes where G.I.M. suppression is effective. As a test

Shiro Kawabata, Katsuhiro Nakamura

We study the quantum interference effect for the single ballistic Aharonov-Bohm billiard in the presence of a weak magnetic field B. The diagonal part of the wave-number averaged reflection coefficient $δ{\cal R}_D$ is calculated by use of semi-classical scattering theory. In addition to the appearance of &#34;h/2e oscillation&#34; that are caused by interfe

I. Montvay

Quadratically optimized polynomials are described which are useful in multi-bosonic algorithms for Monte Carlo simulations of quantum field theories with fermions. Algorithms for the computation of the coefficients and roots of these polynomials are described and their implementation in the algebraic manipulation language Maple is discussed. Tests of the eva

Th. Lippert, G. Bali, N. Eicker, L. Giusti

Results from two studies of full QCD with two flavours of dynamical Wilson fermions are presented. At beta=5.6, the region 0.83 > m_pi/m_rho > 0.56 at m_pia > 0.23 L^{-1} is explored. The SESAM collaboration has generated ensembles of about 200 statistically independent configurations on a 16^3 x 32-lattice at three different kappa-values and is entering the

J. McDonald

We show that, for all values of $Tan β$ and the light right-handed stop mass for which the electroweak phase transition is strong enough to avoid washout following electroweak baryogenesis, the electroweak vacuum is stable over the lifetime of the observed Universe. Cosmological stability of the electroweak vacuum is violated only if the light right-handed s

Y. P. Jing, H. J. Mo, G. Boerner

We show, with the help of large N-body simulations, that the real-space two-point correlation function and pairwise velocity dispersion of galaxies can both be measured reliably from the Las Campanas Redshift Survey. The real-space correlation function is well fitted by the power law $ξ(r)=(r_0/r)^γ$ with $r_0=(5.06\pm0.12)\mpc$ and $γ=1.862\pm 0.034$, and t

Gia Dvali, Zurab Kakushadze

In the Standard Model one of the generations is much heavier than the other two. We propose a simple mechanism where all three generations are treated on the equal footing to begin with, and one heavy and two light families emerge from supersymmetric strong dynamics. The Yukawa mass matrix is identified with vevs of the meson fields of some additional gauge

Igor Halperin, Ariel Zhitnitsky

We suggest that the topological susceptibility in gluodynamics can be found in terms of the gluon condensate using renormalizability and heavy fermion representation of the anomaly. Analogous relations can be also obtained for other zero momentum correlation functions involving the topological density operator. Using these relations, we find the theta depend

Shinya Kanemura, Haru-Tada Sato, Hiroshi Tochimura

Analyzed is the effective potential of D-dimensional thermodynamic Gross-Neveu model (defined by large-N leading order, $2\leq D<4$) under constant electromagnetic field ($\vec{E}\cdot\vec{B}=0$). The potential is derived from a thermal analogy of the worldline formalism. In the magnetic case, the potential is expressed in terms of a discretized momentum sum

Shigeki Matsutani

In this letter, I have considered one-dimensional quantum system with different masses $m$ and $M$, which does not appear integrable in general. However I have found an exact two-body wave function and due to the extension of the integrable system to more general system, it was concluded that the rapidity or quasi-momentum in the integrable system should be

A. Yu. Kitaev

A two-dimensional quantum system with anyonic excitations can be considered as a quantum computer. Unitary transformations can be performed by moving the excitations around each other. Measurements can be performed by joining excitations in pairs and observing the result of fusion. Such computation is fault-tolerant by its physical nature.

C. Brif, A. Mann, M. Revzen

We consider quantum systems, whose dynamical symmetry groups are semisimple Lie groups, which can be split or decay into two subsystems of the same symmetry. We prove that the only states of such a system that factorize upon splitting are the generalized coherent states. Since Bell&#39;s inequality is never violated by the direct product state, when the syst

V. A. Yerokhin, A. N. Artemyev, V. M. Shabaev

The two-electron self-energy contribution to the ground state energy of heliumlike ions is calculated both for a point nucleus and an extended nucleus in a wide interval of Z. All the two-electron contributions are compiled to obtain most accurate values for the two-electron part of the ground state energy of heliumlike ions in the range Z=20-100. The theore

Alexey K. Mazur

The Stoermer-Verlet-leapfrog group of integrators commonly used in molecular dynamics simulations has long become a textbook subject and seems to have been studied exhaustively. There are, however, a few striking effects in performance of algorithms which are well-known but have not received adequate attention in the literature. A closer view of these unclea

Yuri V. Lvov, Alan C. Newell

In this article, we make a prima facie case that there could be distinct advantages to exploiting a new class of finite flux equilibrium solutions of the Quantum Boltzmann equation in semiconductor lasers.

V. Brazhnikov, S. Lukyanov

We discuss an application of the method of the angular quantization to reconstruction of form-factors of local fields in massive integrable models. The general formalism is illustrated with examples of the Klein-Gordon, sinh-Gordon and Bullough-Dodd models. For the latter two models the angular quantization approach makes it possible to obtain free field rep

Michael Flohr

Null vectors are generalized to the case of indecomposable representations which are one of the main features of logarithmic conformal field theories. This is done by developing a compact formalism with the particular advantage that the stress energy tensor acting on Jordan cells of primary fields and their logarithmic partners can still be represented in fo

D. L. Bennett, H. B. Nielsen, R. P. Woodard

We study the initial value problem for actions which contain non-trivial functions of integrals of local functions of the dynamical variable. In contrast to many other non-local actions, the classical solution set of these systems is at most discretely enlarged, and may even be restricted, with respect to that of a local theory. We show that the solutions ar

L. Andrianopoli, R. D&#39;Auria, S. Ferrara, P. Fre&#39;

We study the general equations determining BPS Black Holes by using a Solvable Lie Algebra representation for the homogenous scalar manifold U/H of extended supergravity. In particular we focus on the N=8 case and we perform a general group theoretical analysis of the Killing spinor equation enforcing the BPS condition. Its solutions parametrize the U-dualit

E. L. Gubankova

Modified similarity renormalization of Hamiltonians is proposed, that performes by means of flow equations the similarity transformation of Hamiltonian in the particle number space. This enables to renormalize in the energy space the field theoretical Hamiltonian and makes possible to work in a severe trancated Fock space for the renormalized Hamiltonian.

H-T. Sato

The one-loop effective potential of a thermodynamic fermion loop under constant magnetic field is studied. As expected, it can be interpreted literally as a discretized sum of $(D-2)$-dimensional energy density above the Dirac sea. Large/small mass expansions of the potential are also examined.

Frank Thuillier

We show that the method of S. Wu to study topological 4d-gravity can be understood within a now standard method designed to produce equivariant cohomology classes. Next, this general framework is applied to produce some observables of the topological 4d-gravity.

E. Elizalde, M. Bordag, K. Kirsten

The vacuum energies corresponding to massive Dirac fields with the boundary conditions of the MIT bag model are obtained. The calculations are done with the fields occupying the regions inside and outside the bag, separately. The renormalization procedure for each of the situations is studied in detail, in particular the differences occurring with respect to

Thomas Nowotny, Manfred Requardt

Starting from the working hypothesis that both physics and the corresponding mathematics have to be described by means of discrete concepts on the Planck-scale, one of the many problems one has to face in this enterprise is to find the discrete protoforms of the building blocks of continuum physics and mathematics. A core concept is the notion of dimension.

A. Aghamohammadi, M. Alimohammadi, M. Khorrami

There has been some controversies at the large $N$ behaviour of the 2D Yang-Mills and chiral 2D Yang-Mills theories. To be more specific, is there a one parameter family of minima of the free energy in the strong region, or the minimum is unique. We show that there is a missed equation which, added to the known equations, makes the minimum unique.

U. Baur, S. Keller, W. K. Sakumoto

The ${\cal O}(α)$ radiative corrections to the process $p\,p\hskip-7pt\hbox{$^{^{(\!-\!)}}$} \rightarrow γ^*, \, Z \rightarrow \ell^+ \ell^-$ ($\ell=e,\,μ$) are calculated. Factorizing the collinear singularity associated with initial state photon bremsstrahlung into the parton distribution functions, we find that initial state corrections have a much smalle

Walter T. Giele

In this contribution we explore one of the many possibilities of determining the strong coupling constant $α_S$ at hadron colliders. The method considered is quite unique compared to other methods in that the value of $α_S$ is determined by the ``evolution rate&#39;&#39; of the parton density functions rather than by the ``event rate&#39;&#39;.

V. Pleitez, M. D. Tonasse

Two models with $SU(3)_C\otimes SU(3)_L\otimes U(1)_N$ gauge symmetry are considered. We show that the masslessness of the photon does not prevent the neutrinos from acquiring Majorana masses. That is, there is no relation between the VEVs of Higgs fields and the electromagnetic gauge invariance contrary to what has been claimed recently.

G. Lazarides, N. D. Vlachos

We perform a numerical investigation of the fields evolution in the supersymmetric inflationary model based on radiative corrections. Supergravity corrections are also included. We find that, out of all the examined initial data, only about 10% give an adequate amount of inflation and can be considered as &#39;&#39;natural&#39;&#39;. Moreover, these successf

Adam F. Falk

I discuss the theory of heavy baryon spectroscopy, emphasizing predictions which follow from light and heavy quark symmetries.

Xiao-Fei Zhang, Wei-Qin Chao

The definition of thermal relaxation time is extended to chemically non-equilibrated quark-gluon plasma and the chemical non-equilibrated thermal relaxation times for partons are calculated using the non-equilibrium Debye mass as the infrared regulator. The dependence of the thermal relaxation time on the fugacity is given and the influence of the chemical n

M. A. J. Botje

Results are presented of a study of the experimental and theoretical accuracy one may achieve at HERA in measuring the strong coupling constant alpha_s and the gluon distribution from scaling violations of F2 structure functions.

J. Bijnens, G. Colangelo, G. Ecker, J. Gasser

We present technical details of the evaluation of the elastic pi-pi scattering amplitude to two loops in chiral perturbation theory. In particular, we elaborate on the renormalization procedure at the two-loop order and on the evaluation of the relevant Feynman diagrams that can all be expressed in terms of elementary functions. For the sake of clarity, we d

M. A. J. Botje

Preliminary results are presented on the gluon density obtained from a QCD analysis of ZEUS and NMC F2 structure function data. Also given is an estimate of the experimental error on the positron-proton NC Born cross-section at large x and Q2.

Xiao-Fei Zhang, Han-Wen Huang, Xue-Qian Li, Wei-Qin Chao

We consider the contributions of both color-singlet and octet $c\bar c$ bound states for studying the suppression of $J/ψ$ production in quark gluon plasma (QGP) and have found that the existence of the color-octet $c\bar c$ may cause the $p_T-$distribution of $J/ψ$ a decrease with $p_T$ after a critical value $(p_T)_{max}$, which is quite different from the

The WA102 Collaboration, D. Barberis et al

Results are presented of an analysis of the reactions pp -> pf(k0k+pi-)ps and pp -> pf(K0K0pi0)ps at 450 GeV/c. Clear f1(1285) and f1(1420) signals are seen and a spin parity analysis shows that both have IG JPC=0+ 1++. The f1(1285) decays to a0(980)pi and the f1(1420) decays to K* Kbar. Both states have a similar dependence as a function of dPT consistent w

The WA102 Collaboration, D. Barberis et al

The reaction pp -> pf (pi+pi-pi+pi-) ps has been studied at 450 GeV/c in an experiment designed to search for gluonic states. A spin analysis has been performed and the dPT filter applied. In addition to the well known f1(1285) there is evidence for two JPC=2-+ states called the eta2(1620) and eta2(1875) and a broad scalar called the f0(2000). The production

P. R. Newman

Results presented at the DIS97 workshop by the H1, ZEUS and E665 collaborations on processes yielding large rapidity gaps and energetic leading baryons are reviewed. A consistent picture begins to emerge in which diffractive processes dominate when the fractional longitudinal momentum loss at the baryon vertex $\xpom$ is small, with substantial contributions

The OPAL Collaboration, K. Ackerstaff et al

Using approximately 4.3 million hadronic Z^0 decays collected with the OPAL detector at LEP between 1990 and 1995, we measure the branching fractions of the Z^0 into up-type and down-type light quarks, R_q, and the forward-backward asymmetries, A_FB(q), using high-momentum stable particles as a tag. Adopting a method that employs double tagged events to dete

P. Hajicek, J. Kijowski

The barotropic ideal fluid with step and delta-function discontinuities coupled to Einstein&#39;s gravity is studied. The discontinuities represent star surfaces and thin shells; only non-intersecting discontinuity hypersurfaces are considered. No symmetry (like eg. the spherical symmetry) is assumed. The symplectic structure as well as the Lagrangian and th

U. Bunke

We show that J. Lott&#39;s equivariant higher analytic torsion for compact group actions depends only on the equivariant Euler characteristic.

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

We note that data on Si/SiGe heterostructures, reported in the Comment of Ismail et al. (cond-mat/9707061) on our recent Letter (cond-mat/9608101), are insufficient to establish the claim for a transition to a metallic phase.

Robert Shrock, Shan-Ho Tsai

Denoting $P(G,q)$ as the chromatic polynomial for coloring an $n$-vertex graph $G$ with $q$ colors, and considering the limiting function $W(\{G\},q) = \lim_{n \to \infty}P(G,q)^{1/n}$, a fundamental question in graph theory is the following: is $W_r(\{G\},q) = q^{-1}W(\{G\},q)$ analytic or not at the origin of the $1/q$ plane? (where the complex generalizat

V. B. Shenoy, R. Miller, E. B. Tadmor, R. Phillips

Microscopic models of the interaction between grain boundaries (GBs) and both dislocations and cracks are of importance in understanding the role of microstructure in altering the mechanical properties of a material. A recently developed mixed atomistic and continuum method is extended to examine the interaction between GBs, dislocations and cracks. These ca

Th. Jolicoeur

The pi electrons of isolated fullerene anions C60^{n-} (n betwen 1 and 6) are a quite unique finite system of electrons with an attractive interaction due to exchange of intramolecular phonons. This interaction may overwhelm Hund&#39;s rule and lead to an ordering of levels that can be interpreted as on-ball pairing, in a manner similar to the pairing in ato

E. M. Conwell, M. W. Wu

Conduction in pristine conjugated polymers (other than polyacetylene) is by polaron hopping between sites corresponding to conjugation lengths. The strong increase of current $I$ with voltage $V$ observed for both emission-limited and ohmic contacts is due in large part to mobility increase as increasing field makes it more possible to overcome internal barr

M. H. Pedersen, S. A. van Langen, M. Buttiker

We analyze the frequency-dependent current fluctuations induced into a gate near a quantum point contact or a quantum chaotic cavity. We use a current and charge conserving, effective scattering approach in which interactions are treated in random phase approximation. The current fluctuations measured at a nearby gate, coupled capacitively to the conductor,