December 1994 arXiv papers — page 7

Erik Koelink, J. Verding

The Haar functional on the quantum $SU(2)$ group is the analogue of invariant integration on the group $SU(2)$. If restricted to a subalgebra generated by a self-adjoint element the Haar functional can be expressed as an integral with a continuous measure or with a discrete measure or by a combination of both. These results by Woronowicz and Koornwinder have

Pradipta Bandyopadhyay, A. K. Roy

In this paper, we show that the projective tensor product of a two-dimen\-sional $\ell^p$ space with a two-dimensional $\ell^q$ space never has the Mazur Intersection Property for a large range of values of $p$ and $q$. For this purpose, we characterise the extreme contractions from $\ell^p_2$ to $\ell^q_2$ and obtain their closure.

Dirk Werner

Let $T\dopu C(S)\to C(S)$ be a bounded linear operator. We present a necessary and sufficient condition for the so-called Daugavet equation $$ \|\Id+T\| = 1+\|T\| $$ to hold, and we apply it to weakly compact operators and to operators factoring through $c_{0}$. Thus we obtain very simple proofs of results by Foias, Singer, Pelczynski, Holub and others.

Paul Aspinwall

We review the structure of the moduli space of particular N = (2,2) superconformal field theories. We restrict attention to those of particular use in superstring compactification, namely those with central charge c = 3d for some integer d and whose NS fields have integer U(1) charge. The cases d = 1, 2 and 3 are analyzed. It is shown that in the case d >= 3

Chongying Dong, Geoffrey Mason

Let $V$ be a simple vertex operator algebra and $G$ be a finite nilpotent group of automorphisms of $V.$ We prove the following in this paper: (1) There is a Galois correspondence between subgroups of $G$ and the vertex operator subalgebras of $V$ which contain $V^G$ given by the map $H\mapsto V^H.$ (2) Assume that for every G\in G$ there is unique simple $g

R. Jackiw

These days, as high energy particle colliders become unavailable for testing speculative theoretical ideas, physicists are looking to other environments that may provide extreme conditions where theory confronts physical reality. One such circumstance may arise at high temperature $T$, which perhaps can be attained in heavy ion collisions or in astrophysical

Alexander Belopolsky

We calculate the effective tachyonic potential in closed string field theory up to the quartic term in the tree approximation. This involves an elementary four-tachyon vertex and a sum over the infinite number of Feynman graphs with an intermediate massive state. We show that both the elementary term and the sum can be evaluated as integrals of some measure

A. Borderies, P. Grangé, E. Werner

The solution of the O$(N) ϕ^4$ scalar field theory in the broken phase is given in the framework of light cone quantization and a 1/N expansion. It involves the successive building of operator solutions to the equation of motion and constraints including operator zero modes of the fields which are the LC counterpart to the equal time non trivial vacuum effec

G. H. Gadiyar

In this paper a fundamental length is introduced into physics. This is done in a way which respects special relativity and quantum field theory. The theory has formal similarity to quantum field theory though its properties are far better: divergences are got rid of. The problem of quantizing gravity is straightforward in the approach.

S. Zakrzewski

General framework for Poisson homogeneous spaces of Poisson groups is introduced. Poisson Minkowski spaces are discussed as a particular example.

S. Zakrzewski

Extended phase space of an elementary (relativistic) system is introduced in the spirit of the Souriau's definition of the `space of motions' for such system. Our formulation is generally applicable to any homogeneous space-time (e.g. de Sitter) and also to Poisson actions. Calculations concerning the Minkowski case for non-zero spin particles show a

S. Zakrzewski

We present almost complete list of normal forms of classical $r$-matrices on the Poincaré group.

S. Zakrzewski

The dependence of velocity on momentum for the free massive particle obeying the $κ$-Poincaré Poisson symmetry is calculated in terms of intrinsic non-commuting space-time coordinates and shown to have a monotonic character, with upper limit of velocity equal to 1.

C. Bartocci, U. Bruzzo, M. Carfora, A. Marzuoli

We discuss the counting of minimal geodesic ball coverings of $n$-dimensional riemannian manifolds of bounded geometry, fixed Euler characteristic and Reidemeister torsion in a given representation of the fundamental group. This counting bears relevance to the analysis of the continuum limit of discrete models of quantum gravity. We establish the conditions

Werner Ruehl

We evaluate the partition functions in the neighbourhood of catastrophes by saddle point integration and express them in terms of generalized Airy functions.

D. R. Davidson

Certain criteria are demonstrated for a spatial derivation of a von Neumann algebra to generate a one-parameter semigroup of endomorphisms of that algebra. These are then used to establish a converse to recent results of Borchers and of Wiesbrock on certain one-parameter semigroups of endomorphisms of von Neumann algebras (specifically, Type III_1 factors) t

Hideaki Aoyama, Toshiyuki Harano

The complex-time formalism is developed in the framework of the path-integral formalism, to be used for analysis of the quantum tunneling phenomena. We show that subleading complex-time saddle-points do not account for the right WKB result. Instead, we develop a reduction formula, which enables us to construct Green functions from simple components of the po

K. D. Lane, F. E. Paige, T. Skwarnicki, W. J. Womersley

The Standard Model of particle physics makes it possible to simulate complete events for physics signatures and their backgrounds in high energy collisions. Knowledge of how the produced particles interact with the materials in a detector makes it possible to simulate the response of any particular detector design to these events and so determine whether the

Graciela Gelmini, Esteban Roulet

This is a review for Reports of Progress in Physics. After an introduction we start by explaining the different neutrino masses corresponding to different types of neutrinos, Dirac or Majorana, in section 2. In section 3 we discuss the main elementary particle models for neutrino masses and their distinctive phenomenological consequences. In section 4 we des

V. Barger, R. J. N. Phillips, D. Zeppenfeld

The distinct color flow of the $qq\to qqH,\; H\to W^+W^-$ process leads to suppressed radiation of soft gluons in the central region, a feature which is not shared by major background processes like $t\bar t$ production or $q\bar q \to W^+W^-$. For the leptonic decay of a heavy Higgs boson, $H\to W^+W^- \to \ell^+ν\ell^-\barν$, it is shown that these backgro

Michael S. Chanowitz, William B. Kilgore

Because of inevitable blind spots at high rapidity and low transverse momentum, the process $\overline qq \rightarrow l^+ l^- \ l^{+} ν$ provides a surprisingly large background to the $W^+W^+ \rightarrow l^+ ν\ l^+ ν$ signal associated with strong $WW$ scattering. Previous calculations of the total background are approximately doubled, and the estimate of t

A. Pich

What follows is an updated version of the lectures given at the CERN Academic Training (November 1993) and at the Jaca Winter Meeting (February 1994). The aim is to provide a pedagogical introduction to the Standard Model of electroweak interactions. After briefly reviewing the empirical considerations which lead to the construction of the Standard Model Lag

A. Pich

The total $τ$ hadronic width can be accurately calculated using analyticity and the operator product expansion. The theoretical analysis of this observable is updated to include all available perturbative and non-perturbative corrections. The experimental determination of $α_s(M_τ^2)$ and its actual uncertainties are discussed.

W. Beenakker, R. Höpker, M. Spira, P. M. Zerwas

We have determined the QCD corrections to the production of squark-antisquark pairs in $p\bar p$ collisions at the Tevatron. If the next-to-leading order corrections are taken into account, the renormalization/factorization scale dependence of the theoretical prediction for the cross section is reduced considerably. The higher order corrections increase the

C. Korthals Altes, A. Michels, M. Stephanov, M. Teper

We calculate on the lattice the interface tension in the SU(2) pure gauge theory in d=2+1 at high temperature. The result is compared to the perturbative prediction. The agreement confirms applicability of the perturbation theory in this case.

Shao-Jing Dong, Keh-Fei Liu

We report results of our calculation on the $πNσ$ term and quark spin content of the nucleon on the quenched $16^3 \times 24$ lattice at $β= 6.0$. The disconnected insertions which involve contributions from the sea quarks are calculated with the stochastic $Z_2$ noise algorithm. As a physical test of the algorithm, we show that the forward matrix elements o

T. DeGrand, A. Hasenfratz, P. Hasenfratz, F. Niedermayer

We present an overview of the construction and testing of actions for SU(3) gauge theory which are approximate fixed points of renormalization group equations (at $β\rightarrow \infty$). Such actions are candidates for use in numerical simulations on coarse lattices.

Ryoji Enomoto, Takayuki Sumiyoshi, Yoshio Fujita

A test of various photocathodes was carried out. The tested materials were CsI, CsTe, their multi-layers and so on. The quantum efficiencies of the various materials were measured under a vacuum and/or after exposure to several kinds of gases.

Arkady Kheyfets, Warner A. Miller

We advance here a new gravity quantization procedure that explicitly utilizes York's analysis of the geometrodynamic degrees of freedom. This geometrodynamic procedure of quantization is based on a separation of the true dynamic variables from the embedding parameters and a distinctly different treatment of these two kinds of variables. While the dynamic

Michael Reisenberger

The evolution operator for states of gauge theories in the graph representation (closely related to the loop representation of Gambini and Trias, and Rovelli and Smolin) is formulated as a weighted sum over worldsheets interpolating between initial and final graphs. As examples, lattice $SU(2)$ BF and Yang-Mills theories are expressed as worldsheet theories,

Pedro F. Gonzalez-Diaz

Enforcing the spacetime of supermassive cosmic strings to satisfy the symmetry of a gravitational topological defect, that is a spacetime kink, it is shown that the energy of these strings becomes quantized so that only defects whose internal geometry is that of a hemisphere (critical string) and that of a sphere (extreme string) are allowed. In the latter c

David Crocker, Alex Kumjian, Iain Raeburn, Dana Williams

Suppose that $(G,T)$ is a second countable locally compact transformation group given by a homomorphism $\ell:G\to\Homeo(T)$, and that $A$ is a separable continuous-trace \cs-algebra with spectrum $T$. An action $α:G\to\Aut(A)$ is said to cover $\ell$ if the induced action of $G$ on $T$ coincides with the original one. We prove that the set $\brgt$ of Morita

Juan Jose Palacios, Pawel Hawrylak

The electronic properties of semiconductor, vertical, double quantum dot systems with few electrons are investigated by means of analytic, configuration-interaction, and mean-field methods. The combined effect of a high magnetic field, electrostatic confinement, and inter-dot coupling, induces a new class of few-electron ground states absent in single quantu

M. V. Sadovskii

It is shown that the Josephson current in $S-I-S$---geometry is zero, if one or both superconductors possess the gap odd over $p-p_{F}$. For the odd-frequency pairing the Josephson current is zero in case of the tunneling between the traditional and odd-gap superconductor and is finite for the tunneling between two odd-gap superconductors.

J. H. Oaknin, L. Martin-Moreno, J. J. Palacios, C. Tejedor

We present the adequate circular representation of charge density excitations in Quantum Hall droplets at filling factor 1. A novel set of operators describes magnetoexcitons with well defined both total and center-of-mass angular momentum. The accuracy of this description is shown by the high overlap of the magnetoexcitons with the exact eigenstates of a qu

Herve M. Carruzzo, Clare C. Yu

We investigate whether or not Kondo insulators undergo a magnetic field induced metal-insulator transition in one dimension at half filling using both a density matrix formulation of the numerical renormalization group and a new analytical approach. Contrary to expectations, the quasiparticle gap never vanishes at any field and no metal-insulator transition

Frank C. van den Bosch, Roeland P. van der Marel

We present high spatial resolution ground-based broad-band imaging, H-alpha +[NII] narrow-band imaging and long-slit spectroscopy for the E4 radio galaxy NGC 7052, which has a nuclear dust disc. We detect ionized gas with a LINER spectrum, residing also in a nuclear disc. The gas rotates rapidly and the emission line widths increase towards the nucleus. The

P. Saracco, P. Ciliegi

A search for X-ray emission from compact groups revealed detection from 8 out of the 12 HCG images extracted from the ROSAT public archive. For two of them the X-ray emission originates from galaxies in the group. On the contrary, three groups show an extended emission clearly caused by hot intracluster gas. A Raymond-Smith hot plasma model provides an excel

Nicola Maggiore

N=2 supersymmetric Yang--Mills theories coupled to matter are considered in the Wess--Zumino gauge. The supersymmetries are realized nonlinearly and the anticommutator between two susy charges gives, in addition to translations, gauge transformations and equations of motion. The difficulties hidden in such an algebraic structure are well known: almost always

H. C. Rosu

I comment on a number of theoretical issues related to magnetobremsstrahlung, and especially on synchrotron radiation and Unruh (temperature) radiation, that I consider of importance for the current progress towards a better understanding of the stationary features of such fundamental radiation patterns both in an accelerator context and, more generally, in

You-Quan Li, Zhan-Ning Hu

It is shown that a kind of solutions of n-simplex equation can be obtained from representations of braid group. The symmetries in its solution space are also discussed.

David Thomas

There is continued interest in the possibility that big bang nucleosynthesis may produce significant quantities of Be and B. In this paper we reevaluate the primordial abundances taking into account uncertainties in reactions rates. We discuss the implications for primordial nucleosynthesis, and for galactic cosmic ray spallation.

M. Goeckeler, R. Horsley, M. Ilgenfritz, H. Perlt

We have initiated a programme to compute the lower moments of the unpolarised and polarised deep inelastic structure functions of the nucleon in the quenched approximation. We review our progress to date.

M. Khorrami

Considering one-dimensional nonminimally-coupled lattice gauge theories, a class of nonlocal one-dimensional systems is presented, which exhibits a phase transition. It is shown that the transition has a latent heat, and, therefore, is a first order phase transition.

S. I. Eidelman, E. A. Kuraev, Z. K. Silagadze

The decay modes $ρ^0 \to 2π^+ 2π^-$ and $ρ^0 \to 2π^0 π^+ π^-$ are considered in the framework of the low energy effective chiral Lagrangian. The obtained values of the decay widths $Γ(ρ^0\to 2 π^+ 2 π^-)=$ $(16 \pm 1){\rm keV}$ and $Γ(ρ^0\to 2 π^0 π^+ π^-)= (6.0 \pm 0.2)$keV do not contradict the existing upper limits and seem to be big enough for the corre

J. B. Kogut, M-P Lombardo, D. K. Sinclair

We report on our ongoing effort to understand quenched lattice QCD at finite baryon number density. The quenched theory is sensitive to the baryon mass both at strong coupling and in the scaling region. However, we find that the quenched model is pathological for $μ> m_π/2$ at $β= 6.0$, in agreement with past Lanczos analyses of the Dirac operator.

M-P Lombardo A. Kocic, J. B. Kogut

We explore the possibility of a trivial continuum limit of strongly coupled quenched QED4 by contrasting our results with a Nambu--Jona Lasinio equation of state. The data does not compare favorably with such scenario. We study in detail the interplay of chiral symmetry breaking with the Goldstone mechanism, and clarify some puzzling features of past results

Y. Iwasaki, K. Kanaya, S. Sakai, T. Yoshie

The finite temperature transition or crossover in QCD with two degenerate Wilson quarks is investigated using a renormalization group improved action. At $β=2.0$ and 2.1 where $a^{-1} \sim 1.0-1.2$ GeV, the expectation value of the Polyakov loop and the pion screening mass on an $8^3 \times 4$ lattice vary smoothly with the hopping parameter through the tran

M. Swartz, H. R. Band, F. J. Decker, P. Emma

In 1992, L.G. Levchuk noted that the asymmetries measured in Møller scattering polarimeters could be significantly affected by the intrinsic momenta of the target electrons. This effect is largest in devices with very small acceptance or very high resolution in laboratory scattering angle. We use a high resolution polarimeter in the linac of the polarized SL

J. Kowalski-Glikman

There are several regimes in chaotic inflationary cosmology where some part of the system is classical and some other quantum. I describe how to deal with such systems and how to disentangle their dynamics into classical behaviour and quantum corrections. I also discuss the conditions for quantum corrections to be small.

Ulvi Yurtsever

The now-famous Majumdar-Papapetrou exact solution of the Einstein-Maxwell equations describes, in general, $N$ static, maximally charged black holes balanced under mutual gravitational and electrostatic interaction. When $N=2$, this solution defines the two-black-hole spacetime, and the relativistic two-center problem is the problem of geodesic motion on thi

Marc Light, Lenhart Schubert

Natural language understanding applications such as interactive planning and face-to-face translation require extensive inferencing. Many of these inferences are based on the meaning of particular open class words. Providing a representation that can support such lexically-based inferences is a primary concern of lexical semantics. The representation languag

D. Edidin, W. Graham

We study the ring of characteristic classes with values in the Chow ring for principal $G$-bundles over schemes. If we consider bundles which are locally trivial in the Zariski topology, then we show, for $G$ reductive, that this ring is isomorphic to the Weyl group invariants in the algebra generated by characters of the maximal torus. For general principal

Mohan Rajagopal, Roger W. Romani

For massive black hole binaries produced in galactic mergers, we examine the possibility of inspiral induced by interaction with field stars. We model the evolution of such binaries for a range of galaxy core and binary parameters, using numerical results from the literature to compute the binary's energy and angular momentum loss rates due to stellar en

E. Ben-Naim

We study the density of clustered immobile reactants in the diffusion-controlled single species annihilation. An initial state in which these impurities occupy a subspace of codimension d' leads to a substantial enhancement of their survival probability. The Smoluchowski rate theory suggests that the codimensionality plays a crucial role in determining t

Glennys R. Farrar, John W. McIntosh,

We study the interaction of particles with a domain wall at a symmetry-breaking phase transition by perturbing about the domain wall solution. We find the particulate excitations appropriate near the domain wall and relate them to the particles present far from the wall in the uniform broken and unbroken phases. For a quartic Higgs potential we find analytic

A. Ballesteros, N. A. Gromov, F. J. Herranz, M. A. del Olmo

Lie bialgebra contractions are introduced and classified. A non-degenerate coboundary bialgebra structure is implemented into all pseudo-orthogonal algebras $so(p,q)$ starting from the one corresponding to $so(N+1)$. It allows to introduce a set of Lie bialgebra contractions which leads to Lie bialgebras of quasi-orthogonal algebras. This construction is exp

Bodo Pareigis

Representations of a group $G$ in vector spaces over a field $K$ form a category. One can reconstruct the given group $G$ from its representations to vector spaces as the full group of monoidal automorphisms of the underlying functor. This is a special example of Tannaka-Krein theory. This theory was used in recent years to reconstruct quantum groups (quasit

Boqi Wang

We study steady, radial gas outflows from galaxies in an effort to understand the way tenuous and hot gas is transported to large distances away from galaxies. In particular, we obtain solutions for outflow problems, and study the outflow topology, effects of the galaxy mass, the size of outflow regions, the efficiency of radiative cooling, and the fate of t

Suresh Govindarajan

We formulate the uniformisation problem underlying the geometry of W_n-gravity using the differential equation approach to W-algebras. We construct W_n-space (analogous to superspace in supersymmetry) as an (n-1) dimensional complex manifold using isomonodromic deformations of linear differential equations. The W_n-manifold is obtained by the quotient of a F

NRQCD collaboration

We present new results on $\Upsilon$ and $J/\Psi$ spectroscopy using Lattice NRQCD. Charmonium results at quenched $\beta$ = 5.7 show agreement with experiment within understood systematic errors. We compare bottomonium results at quenched $\beta$s 6.0 and 5.7 and show that the $1P-1S$ splitting scales with $\Lambda_V$, provided a correction is applied for t

Matthias Neubert

We present a formalism to evaluate QCD diagrams with a single virtual gluon using a running coupling constant at the vertices. This method, which corresponds to an all-order resummation of certain terms in a perturbative series, provides a description of the momentum flow through the gluon propagator. It can be viewed as a generalization of the scale-setting

Rolf Schimmrigk

In Calabi--Yau compactifications of the heterotic string there exist quantities which are universal in the sense that they are present in every Calabi--Yau string vacuum. It is shown that such universal characteristics provide numerical information, in the form of scaling exponents, about the space of ground states in string theory. The focus is on two physi

S. J. Poletti, J. Twamley, D. L. Wiltshire

The properties of static spherically symmetric black holes, which are either electrically or magnetically charged, and which are coupled to the dilaton in the presence of a cosmological constant, are considered. It is shown that such solutions do not exist if the cosmological constant is positive (in arbitrary spacetime dimension >= 4). However, asymptotical

W. M. Koo

Based on transfer matrix techniques and finite size scaling, we study the oriented polymer (self-avoiding walk) with nearest neighbor interaction. In the repulsive regime, various critical exponents are computed and compared with exact values predicted recently. The polymer is also found to undergo a spiral transition for sufficiently strong attractive inter

P. A. Clarkson, E. L. Mansfield, A. E. Milne

We investigate the classical and nonclassical reductions of the $2+1$-dimensional sine-Gordon system of Konopelchenko and Rogers, which is a strong generalisation of the sine-Gordon equation. A family of solutions obtained as a nonclassical reduction involves a decoupled sum of solutions of a generalised, real, pumped Maxwell-Bloch system. This implies the e

Peter A. Clarkson, Andrew P. Bassom

In this paper we describe Bäcklund transformations and hierarchies of exact solutions for the fourth Painlevé equation (PIV) $${\d^2 w\over\d z^2}={1\over2w}\left(\d w\over\d z\right)^2 + {3\over2}w^3 + 4zw^2 + 2(z^2-α)w+{β\over w},\eqno(1){\hbox to 16pt{\hfill}}$$ with $α$, $β$ constants. Specifically, a nonlinear superposition principle for PIV, hierarchie

A. J. Roberts

I argue that ``good'' mathematical models of spatio-temporal dynamics in two-dimensions require non-local operators in the nonlinear terms. Consequently, the often used Swift-Hohenberg equation requires modification as it is purely local. My aim here is to provoke more critical examination of the rationale for using the Swift-Hohenberg equations as a

Hungchong Kim, J. Piekarewicz, C. J. Horowitz

Charged-current cross sections are calculated for quasielastic neutrino and antineutrino scattering using a relativistic meson-nucleon model. We examine how nuclear-structure effects, such as relativistic random-phase-approximation (RPA) corrections and momentum-dependent nucleon self-energies, influence the extraction of the axial form factor of the nucleon

M. -C. Chu, S. Schramm

We investigate the temperature dependence of the instanton content of gluon fields and their contribution to quark correlation using quenched lattice QCD and the cooling method. We found a suppression of the topological susceptibility at finite temperature, agreeing with the PCAC expectation at low temperature and enhanced suppression for temperatures at and

C. Barbero, F. Krmpotić, A. Mariano

We examine the contributions of odd-parity nuclear operators to the two-neutrino double beta decay $0^+\rightarrow 0^+$ amplitude, which come from the $P$-wave Coulomb corrections to the electron wave functions and the recoil corrections to the nuclear currents. Although they are formally of higher order in $αZ/2$ or $v/c$ of the nucleon than the usual Fermi

V. F. Dmitriev, I. B. Khriplovich, V. B. Telitsin

The hypothesis of a large weak matrix element between single-particle states in heavy nuclei ($\sim 100$ eV) contradicts the results of atomic PNC experiments.

Jeongnim Kim, Francesco Mauri, Giulia Galli

An energy functional for orbital based $O(N)$ calculations is proposed, which depends on a number of non orthogonal, localized orbitals larger than the number of occupied states in the system, and on a parameter, the electronic chemical potential, determining the number of electrons. We show that the minimization of the functional with respect to overlapping

Herbert W. Hamber, Ruth M. Williams

A model for quantum gravity in one (time) dimension is discussed, based on Regge's discrete formulation of gravity. The nature of exact continuous lattice diffeomorphisms and the implications for a regularized gravitational measure are examined. After introducing a massless scalar field coupled to the edge lengths, the scalar functional integral is perfo

M. De Francia, H. Falomir, M. Loewe, E. M. Santangelo

We introduce the chemical potential in a system of two-dimensional massless fermions, confined to a finite region, by imposing twisted boundary conditions in the Euclidean time direction. We explore in this simple model the application of functional techniques which could be used in more complicated situations.

R. Kirschner, L. Szymanowski

The multi-Regge effective action is derived directly from the linearized gravity action. After excluding the redundant field components we separate the fields into momentum modes and integrate over modes which correspond neither to the kinematics of scattering nor to the one of exchanged particles. The effective vertices of scattering and of particle product

J. -P. Derendinger

Quantum symmetries of four-dimensional superstrings are frequently realized in an anomaly-cancellation mode in the effective low-energy supergravity. The massless antisymmetric tensor plays an important rôle in this mechanism and the choice of its supersymmetric description, using either a chiral or a linear multiplet, appears to introduce significant concep

M. R. Kibler, R. M. Asherova, Yu. F. Smirnov

A set of compatible formulas for the Clebsch-Gordan coefficients of the quantum algebra $U_{q}({\rm su}_2)$ is given in this paper. These formulas are $q$-deformations of known formulas, as for instance: Wigner, van der Waerden, and Racah formulas. They serve as starting points for deriving various realizations of the unit tensor of $U_{q}({\rm su}_2)$ in te

H. J. de Vega, I. Giannakis, A. Nicolaidis

We study quantum strings in strong gravitational fields. The relevant small parameter is $g=R_c{\sqrt T_0}$, where $R_c$ is the curvature of the spacetime and $T_0$ is the string tension. Within our systematic expansion we obtain to zeroth order the null string (string with zero tension), while the first order correction incorporates the string dynamics. We

G. M. Cicuta, L. Molinari, E. Montaldi, S. Stramaglia

A matrix model to describe dynamical loops on random planar graphs is analyzed. It has similarities with a model studied by Kazakov, few years ago, and the O(n) model by Kostov and collaborators. The main difference is that all loops are coherently oriented and empty. The free energy is analytically evaluated and the two critical phases are analyzed, where t

Ingo Gaido, Dieter Lust

String effective theories with N=1 supersymmetry in four dimensions are subject of the discussion. Gaugino condensation in the chiral representation of the dilaton is reviewed in the truncated formalism in the $U_{K}(1)$-superspace. Using the supersymmetric duality of the dilaton the same investigation is made in the linear representation of the dilaton. We

L. Rozansky

We derive the large k asymptotics of the surgery formula for SU(2) Witten's invariants of general Seifert manifolds. The contributions of connected components of the moduli space of flat connections are identified. The contributions of irreducible connections are presented in a residue form. This form is similar to the one used by A. Szenes, L. Jeffrey a

J. Zeng, J. W. Van Orden, W. Roberts

Motivated by the present interest in the heavy quark effective theory, we use the spectator equation to treat the mesonic bound states of heavy quarks. The kernel we use is based on scalar confining and vector Coulomb potentials. Wave functions are treated to leading order and energies to order $1/m_Q$ in the heavy-light systems, and order $1/m_Q^2$ in heavy

W. Bernreuther, G. W. Botz, D. Bruss, P. Haberl

We discuss the effect of CP-violating $Zb\bar{b}$, $Zb\bar{b}G$ and $Zb\bar{b}γ$ couplings on the width $Γ(Z\rightarrow b\bar bX)$. The presence of such couplings leads in a natural way to an increase of this width relative to the prediction of the standard model. Various strategies of a direct search for such CP-violating couplings by using CP-odd observabl

Markus Finkemeier

We consider $K_{l2}$ decays to the order $O(α)$. We perform a matching calculation, using a specific model with vector meson dominance in the long distance part and the parton model in the short distance part. By considering the dependence on the matching scale and on the hadronic parameters, and by comparing with the leading model independent predictions, w

M. Trodden, A-C. Davis, R. Brandenberger

We demonstrate the viability of electroweak baryogenesis scenarios in which the necessary departure from equilibrium is realized by the evolution of a network of topological defects. We consider several effective models of TeV physics, each addressing a fundamental particle physics problem, and in which the conditions necessary for defect-mediated electrowea

Alick L. Macpherson, James L. Pinfold

The detectability of charged SLAC-bag type structures is considered. These objects, known as Fermi balls, arise from the spontaneous symmetry breaking of a biased discrete symmetry in the early universe. Two classes of experimental searches are discussed. Since Fermi balls in the theoretically favoured mass range are absorbed by the atmosphere, direct experi

Haret C. Rosu

We survey at the general level, and in a rather wide and historical context, some less known mathematical details of various mean free path statistics in nuclear emulsion as applied to relativistic projectile fragmentations. A number of comments are provided on Feller's paradox, ordered, censored, and truncated statistics, Erlang and Poisson observers of

Gudmar Thorleifsson

The q=10 and q=200 state Potts models coupled to 2d gravity are investigated numerically and shown to have continuous phase transitions, contrary to their behavior on a regular lattice. Critical exponents are extracted and possible critical behavior for general q-state Potts models coupled to gravity is discussed.

F. Karsch, T. Neuhaus, A. Patkós

This talk summarizes results obtained from simulating a three dimensional pure Order Parameter (OP) model of the Electroweak Phase Transition (EWPT). Its detailed presentation appears in \cite{karsch}.

J. Jersák, C. B. Lang, T. Neuhaus

We present evidence about a critical behavior of $4D$ compact QED (CQED) pure gauge theory. Regularizing the theory on lattices homotopic to a sphere, we present evidence for a critical, i.e. second order like behavior at the deconfinement phase transition for certain values of the coupling parameter $γ$.

M. Crisafulli, V. Gimenez, G. Martinelli, C. T. Sachrajda

We present the first lattice calculation of the B-meson binding energy $\labar$ and of the kinetic energy $λ_1/2 m_Q$ of the heavy-quark inside the pseudoscalar B-meson. In order to cancel the ambiguities due to the ultraviolet renormalons present in the operator matrix elements, this calculation has required the non-perturbative subtraction of the power div

T. D. Kieu, J. F. Markham, C. B. Paranavitane

The lattice fermion determinants, in a given background gauge field, are evaluated for two different kinds of random lattices and compared to those of naive and wilson fermions in the continuum limit. While the fermion doubling is confirmed on one kind of lattices, there is positive evidence that it may be absent for the other, at least for vector interactio

T. D. Kieu, P. S. Hawkins

The chiral Schwinger model is formulated in the wilson-fermion formulation on the lattice and then simulated by the complex langevin algorithm. The simulation is done both without and with gauge fixing to the Lorentz gauge for the compact gauge links. Some preliminary results are presented which indicate that the complex langevin is well behaving with the co

Sandro S. Costa, George E. A. Matsas

We consider inertial and accelerated Unruh-DeWitt detectors moving in a background thermal bath and calculate their excitation rates. It is shown that for fast moving detectors such a thermal bath does not affect substantially the excitation probability. Our results are discussed in connection with a possible proposal of testing the Unruh effect in high ener

R. Beig, N. Ó Murchadha

Transverse-tracefree (TT-) tensors on $({\bf R}^3,g_{ab})$, with $g_{ab}$ an asymptotically flat metric of fast decay at infinity, are studied. When the source tensor from which these TT tensors are constructed has fast fall-off at infinity, TT tensors allow a multipole-type expansion. When $g_{ab}$ has no conformal Killing vectors (CKV's) it is proven t

Hugh Luckock, Chris Oliwa

Nicolai's theorem suggests a simple stochastic interpetation for supersymmetric Euclidean quantum theories, without requiring any inner product to be defined on the space of states. In order to apply this idea to supergravity, we first reduce to a one-dimensional theory with local supersymmetry by the imposition of homogeneity conditions. We then make th

A. H. Castro Neto

I show that when non-linearities are taken into account the Landau theory of Fermi liquids predicts the existence of hyperbolic waves in fermionic systems. The zero sound is described by a infinite set of coupled non-linear partial differential equations, one for each harmonic of oscillation of the Fermi surface. When just a few harmonics are included it is

L. A. N. Amaral, A. -L. Barabasi, S. V. Buldyrev, S. T. Harrington

We study the recently-introduced directed percolation depinning (DPD) model for interface roughening with quenched disorder for which the interface becomes pinned by a directed percolation (DP) cluster for $d = 1$, or a directed surface (DS) for $d > 1$. The mapping to DP enables us to predict some of the critical exponents of the growth process. For the cas

G. Paladin, M. Pasquini, M. Serva

The quenched free energy of spin glasses is estimated by means of annealed averages where the frustration is constrained to its average value. We discuss the case of d-dimensional Ising models with random nearest neighbour coupling, and we introduce a new method to obtain constrained annealed averages without recurring to Lagrange multipliers. It requires to