October 1994 arXiv papers — page 7

Herbert Edelsbrunner, Ernst Mücke

This paper describes a general-purpose programming technique, called the Simulation of Simplicity, which can be used to cope with degenerate input data for geometric algorithms. It relieves the programmer from the task to provide a consistent treatment for every single special case that can occur. The programs that use the technique tend to be considerably s

Herbert Edelsbrunner, Ernst Mücke

Frequently, data in scientific computing is in its abstract form a finite point set in space, and it is sometimes useful or required to compute what one might call the ``shape'' of the set. For that purpose, this paper introduces the formal notion of the family of $α$-shapes of a finite point set in $\Real^3$. Each shape is a well-defined polytope, d

Vladimir A. Kazakov, Thomas Wynter

The large N phase transition point is investigated in the heat kernel on the $U(N)$ group with respect to arbitrary boundary conditions. A simple functional relation is found relating the density of eigenvalues of the boundary field to the saddle point shape of the typical Young tableaux in the large $N$ limit of the character expansion of the heat kernel. B

G. Modanese

The vacuum correlations of the gravitational field are highly non-trivial to be defined and computed, as soon as their arguments and indices do not belong to a background but become dynamical quantities. Their knowledge is essential however in order to understand some physical properties of quantum gravity, like virtual excitations and the possibility of a c

H. Dorn

Based on considerations in conformal gauge I derive up to nextleading order a relation between the coefficients of beta-functions in 2D renormalizable field theories before and after coupling to gravity. The result implies a coupling constant dependence of the ratio of both beta-functions beyond leading order.

J. Loffelholz, G. Morchio, F. Strocchi

A functional integral representation is given for a large class of quantum mechanical models with a non--L2 ground state. As a prototype the particle in a periodic potential is discussed: a unique ground state is shown to exist as a state on the Weyl algebra, and a functional measure (spectral stochastic process) is constructed on trajectories taking values

Andrei Linde

A general overview of the history and present status of inflationary cosmology is given. Recent developments discussed in this paper include the hybrid inflation scenario, the theory of reheating, and the theory of inflating tolopogical defects. We also discuss the theory of a stationary self-reproducing inflationary universe, and its possible implications f

Xiangdong Ji

{}From the deep-inelastic momentum sum rule and the trace anomaly of the energy-momentum tensor, I derive a separation of the nucleon mass into the contributions of the quark and gluon kinetic and potential energies, the quark masses, and the trace anomaly.

M. Genovese, N. N. Nikolaev, B. G. Zakharov

We present microscopic QCD calculation of the cross section of diffractive DIS and of the partonic structure of the pomeron from the dipole approach to the generalized BFKL pomeron. We show that the pomeron can not be treated as a particle with uniquely defined structure function and flux in the proton. We find strong factorization breaking which can approxi

M. Genovese, N. N. Nikolaev, B. G. Zakharov

We present a unified direct calculation of the triple-pomeron coupling $A_{3\Pom}(Q^{2})$ for diffractive real photoproduction ($Q^{2}=0$) and deep inelastic scattering at large $Q^{2}$ in the framework of the dipole approach to the generalized BFKL pomeron. The small phenomenological value of $A_{3\Pom}(0)\approx 0.16$\,GeV$^{2}$, which was a mystery, is re

I. I. Balitsky, V. M. Braun

We consider the instanton contributions for the production of a gluon jet with large transverse momentum in QCD. We find that Mueller's corrections corresponding to the rescattering of hard quanta are likely to remove contributions of large instantons, making this cross section well defined. This observation generalizes the previous discussion of instant

T. Kobayashi, M. Konmura, D. Suematsu, K. Yamada

The electric dipole moment of the neutron (EDMN) is re-examined in a general framework of the soft supersymmetry breaking. We point out some features of the relation between the EDMN and non-universal soft supersymmetry breaking terms. We give the constraints on the soft scalar masses and the soft CP phases, which have the rather large dependence on the non-

B R Webber

The current status of the QCD coupling constant $α_S$ and experimental and theoretical studies of hadronic jets are reviewed.

Aaron K. Grant

Constraints on the two Higgs doublet model are presented, assuming a top mass of 174 $\pm$ 17 GeV. We concentrate primarily on the ``type II'' model, where up--type quarks receive their mass from one Higgs doublet, and down--type quarks receive their mass from the second doublet. High energy constraints derived from the $W$ mass, the full width of th

Krzysztof GENSER, D0 Collaboration

Preliminary results from a search for high mass ttbar quark pair production in ppbar collisions at sqrt(s)=1.8TeV with the D0 detector in the ee+jets, emu+jets, and mumu+jets decay channels are presented. No conclusive evidence for top quark production for an integrated luminosity of 13.5+/-1.6pb-1 is observed.

Renaud Parentani, Joseph Katz, Isao Okamoto

We present a unified thermodynamical description of the configurations consisting on self-gravitating radiation with or without a black hole. We compute the thermal fluctuations and evaluate where will they induce a transition from metastable configurations towards stable ones. We show that the probability of finding such a transition is exponentially small.

Siegfried Echterhoff, Dana Williams

We characterize when the primitive ideal space of a crossed product $\acg$ of a \cs-algebra $A$ by a locally compact abelian group $G$ is a $σ$-trivial $\ghat G$-space for the dual $\ghat G$-action. Specifically, we show that $\Prim(\acg)$ is $σ$-trivial if and only if the quasi-orbit space is Hausdorff, the map which assigns to each quasi-orbit $\w$ a certa

M. M. Fogler, B. I. Shklovskii

We calculate the probability to find exactly $n$ eigenvalues in a spectral interval of a large random $N \times N$ matrix when this interval contains $s \ll N$ eigenvalues on average. The calculations exploit an analogy to the problem of finding a two-dimensional charge distribution on the interface of a semiconductor heterostructure under the influence of a

M. Zirnbauer

A careful study of the supersymmetric version of Pruisken's nonlinear sigma model for the integer quantum Hall effect is presented. The lattice regularized model is cast in Hamiltonian form by taking the anisotropic limit and interpreting the topological density as an alternating sum of Wess-Zumino terms. It is argued that the relevant large-scale physic

Karl Strobl, Thomas J. Weiler

We present analytic solutions to the spatially homogeneous axion field equation, using a model potential which strongly resembles the $(1-\cos θ)$ standard anharmonic potential. We find that the anharmonicity amplifies early universe axion density fluctuations, but only significantly so for relatively large initial misalignment angles. Enhancements of $\sim$

L. Toffolatti

We examine the extent to which galactic and extragalactic foregrounds can hamper the detection of primordial Cosmic Microwave Background (CMB) anisotropies. We limit our discussion to intermediate angular scales, $10^{\prime}\lsim θ\lsim 2^{\circ}$, since many current as well as future experiments have been designed to map CMB anisotropies at these angular s

Eric G. Blackman, George B. Field

Reconnection shocks in a magnetically dominated plasma must be compressive. Non-thermal ion acceleration can occur across built-in slow shocks, and across outflow fast shocks when the outflow is supermagnetosonic and the field is line-tied. Electron acceleration may be initiated by injection from the dissipation region. Reconnection and shock acceleration th

Andreas Reisenegger

The core of a neutron star contains several species of particles, whose relative equilibrium concentrations are determined by the local density. As the star spins down, its centrifugal force decreases continuously, and the star contracts. The density of any given fluid element increases, changing its chemical equilibrium state. The relaxation towards the new

Rosemary F. G. Wyse

Invited review given at special session on Digitizing the Sky at 1994 Summer AAS meeting, Minnesota.

Oliver Küchle

Given a smooth complex projective surface $S$ and an ample divisor $H$ on $S$, consider the blow up of $S$ along $k$ points in general position. Let $H'$ be the pullback of $H$ and $E_1,..., E_k$ be the exceptional divisors. We show that $L = nH' -E_1 - ... -E_k$ is ample if and only if $L^2$ is positive provided the integer $n$ is at least 3.

David B. Jaffe

We study the units in a tensor product of rings. For example, let k be an algebraically closed field. Let A and B be reduced rings containing k, having connected spectra. Let u \in A tensor_k B be a unit. Then u = a tensor_k b for some units a \in A and b \in B. Here is a deeper result, stated for simplicity in the affine case only. Let k be a field, and let

David B. Jaffe

Let A be a commutative noetherian ring. Call a functor <<commutative A-algebras>> --> <<sets>> coherent if it can be built up (via iterated finite limits) from functors of the form B \mapsto M tensor_A B, where M is a f.g. A-module. When such a functor F in fact takes its values in <<abelian groups>>, we show that there are only finitely many prime numbers p

David B. Jaffe

Let S, T be surfaces in P3. Suppose that S intersect T is set-theoretically a smooth curve C of degree d and genus g. Suppose that S and T have no common singular points. Then if C is not a complete intersection, then deg(S), deg(T) < 2d^4. Fixing (d,g), one can form a finite (shorter) list of all possible pairs (deg(S),deg(T)). For instance, when (d,g) = (4

Robert Friedman, Zhenbo Qin

We study the change of moduli spaces of Gieseker-semistable torsion free rank-$2$ sheaves on algebraic surfaces as we vary the polarizations. When the surfaces are rational with an effective anti-canonical divisor, the moduli spaces are linked by a series of flips (blowups and blowdowns). Using these results, we compute the transition formulas for Donaldson

L. Maiani, M. Testa

The problem of causality is analyzed in the context of Local Quantum Field Theory. Contrary to recent claims, it is shown that apparent noncausal behaviour is due to a lack of the notion of sharp localizability for a relativistic quantum system. (Replaced corrupted file)

J. Rembielinski

A consistent quantization scheme for imaginary-mass field is proposed. It is related to an appriopriate choice of the synchronization procedure (definition of time), which guarantee an absolute causality. In that formulation a possible existence of field exctitations (tachyons) distinguish an inertial frame (tachyon privileged frame of reference) via spontan

Franz Embacher

It is shown -- using a FRW model with ${\bf S}^3 \times {\bf S}^6$ as spatial sections and a positive cosmological constant -- that classical signature change implies a new compactification mechanism. The internal scale factor is of the order $Λ^{-1/2}$, and the solutions are stable against small perturbatons. In the case of compactified ${\bf S}^6$, it is s

R. Decker, M. Finkemeier, P. Heiliger, H. H. Jonsson

We compute branching ratios and invariant mass distributions of the tau decays into four pions. The hadronic matrix elements are obtained by starting from the structure of the hadronic current in chiral limit and then implementing low-lying resonances in the different channels. Reasonable agreement with experiment is obtained both for the $τ\to ν_τ + (4 π) $

Anjan S. Joshipura, Jose W. F. Valle

We present a model where an unstable MeV Majorana tau \neu can naturally reconcile the cold dark matter model (CDM) with cosmological observations of large and small scale density fluctuations and, simultaneously, with data on solar and atmospheric neutrinos. The solar \neu deficit is explained through long wavelength, so-called {\sl just-so} oscillations in

Giuliano Preparata, Philip G. Ratcliffe

In the framework of Anisotropic Chromodynamics, a non-perturbative realization of QCD, we develop the Low-Nussinov picture of the Pomeron. In this approach all the usual problems of low pT perturbative calculations (infrared divergence) are naturally absent. Thus, we are able to perform an ab initio calculation of the hadron-hadron total cross section. The r

J J C NIMMO

The use of effective Darboux transformations for general classes Lax pairs is discussed. The general construction of ``binary&#39;&#39; Darboux transformations preserving certain properties of the operator, such as self-adjointness, is given. The classes of Darboux transformations found include the multicomponent BKP and CKP reductions of the KP hierarchy.

Joannis Papavassiliou, Kostas Philippides, Martin Schaden

We propose a decomposition of the S-matrix into individually gauge invariant sub-amplitudes, which are kinematically akin to propagators, vertices, boxes, etc. This decompsition is obtained by considering limits of the S-matrix when some or all of the external particles have masses larger than any other physical scale. We show at the one-loop level that the

J. Gamboa

A model of two-dimensional quantum gravity that is the analog of the tensionless string is proposed. The gravitational constant ($k$) is the analog of the Regge slope ($α^{&#39;}$) and it shows that when $k \rightarrow \infty$, $2D$ quantum gravity can be understood as a tensionless string theory embeded in a two-dimensional target space. The temporal coordi

Wolfgang Eholzer, Nils-Peter Skoruppa

We describe the construction of vector valued modular forms transforming under a given congruence representation of the modular group SL(2,Z) in terms of theta series. We apply this general setup to obtain closed and easily computable formulas for conformal characters of rational models of W-algebras.

Yoonbai Kim

The first-order phase transition of $O(3)$ symmetric model is considered in the limit of high temperature. It is shown that this model supports a new bubble solution where the global monopole is formed at the center of the buble in addition to the ordinary $O(3)$ bubble. Though the free energy of it is larger than that of normal bubble, the production rate c

M. Yoshimura

Dynamical evolution of the quantum ground state (vacuum) is analyzed for time variant harmonic oscillators characterized by asymptotically constant frequency. The oscillatory density matrix in the asymptotic future is uniquely determined by a constant number of produced particles, independent of other details of transient behavior at intermediate times. Time

L. Susskind, J. Uglum

We give some examples in which neglecting the interactions between particles or truncating the description of a black hole to the spherically symmetric mode leads to unphysical results. The restoration of the interactions and higher angular momentum modes resolves these problems. It is argued that mathematical consistency of the description of black holes in

Anirban Kundu, Sreerup Raychaudhuri

We investigate the fine-tuning problem in the Standard Model and show that Higgs boson and top quark masses consistent with current experimental bounds cannot be obtained unless one extends the particle spectrum. A minimal extension which achieves this involves addition of a singlet real scalar and one generation of vectorlike fermions. We show that this lea

U. Baur, T. Han, J. Ohnemus

The process $p\,\pbar \rightarrow W^{\pm}Z + X \rightarrow \ell^\pm_1 ν_1 \ell_2^+ \ell_2^- + X$ is calculated to ${\cal O}(α_s)$ for general $C$ and $P$ conserving $WWZ$ couplings. At the Tevatron center of mass energy, the QCD corrections to $WZ$ production are modest. At Large Hadron Collider (LHC) energies, the inclusive QCD corrections are large, but ca

Yung Su Tsai

We consider the production of tau pairs by electron-positron colliding beams at the maximum cross section near the threshold. At this energy tau pairs are produced mostly in the s-wave which implies that the spin of the tau pairs are almost always pointing in the beam direction independent of the production angle. When both electrons and positrons are longit

H. J. Pirner, B. -J. Schaefer

We analyse the QCD chiral phase transition in the nonlinear and linear $σ$-model. The strategy is the same in both cases. We fix the parameters of the effective meson theory at temperature $T=0$ and extrapolate the models to temperatures in the vicinity of the phase transition. The linear $σ$-model in $SU(3)\times SU(3)$ gives a crossover around $T_c\approx1

J. Hartmann, F. Beck, W. Bentz

We show a practical way based on the Källén-Lehmann representation for the two-point functions to eliminate the instability of the vacuum against formation of small sized meson configurations in the chiral $σ$ model.

M. Nowakowski, S. D. Rindani

We calculate exotic cooling rates of stars due to photo-production of light particles (mostly scalars and pseudoscalars) which originate from the hidden sector of no scale supergravity theories. Using this we can restrict the gravitino mass $m_{3/2}$. The range of eliminated values of $m_{3/2}$ stretches over six orders of magnitude and is given by $\display

S. Barshay, P. Heiliger

We investigate the dynamical possibility for the formation of a transient new coherent condition of matter in high--energy hadronic collisions. The coherent bosonic amplitude is characterized by a non--zero momentum and is sustained by $P $--wave interactions of quasi--pions in a dense fermionic medium. We make quantitative estimates of several essential pro

Mikhail Bilenky, Germán Rodrigo, Arcadi Santamaria

We consider the possibility of extracting the bottom quark mass from LEP data. The inclusive decay rate for $\zbb +\cdots$ is obtained at order $\as$ by summing up the one-loop two-parton decay rate to the tree-level three-parton rate. We calculate the decay width of the $Z$-boson into two and three jets containing the $b$-quark including complete quark mass

the SLD Collaboration

We present the first measurement of the left-right asymmetry in Bhabha scattering with a polarized electron beam. The effective electron vector and axial vector couplings to the Z0 are extracted from a combined analysis of the polarized Bhabha scattering data and the left-right asymmetry previously published by this collaboration.

J. Fernando Barbero

I suggest in this letter a new strategy to attack the problem of the reality conditions in the Ashtekar approach to classical and quantum general relativity. By writing a modified Hamiltonian constraint in the usual $SO(3)$ Yang-Mills phase space I show that it is possible to describe space-times with Lorentzian signature without the introduction of complex

J. Fernando Barbero

We give in this paper a modified self-dual action that leads to the $SO(3)$-ADM formalism without having to face the difficult second class constraints present in other approaches (for example if one starts from the Hilbert-Palatini action). We use the new action principle to gain some new insights into the problem of the reality conditions that must be impo

Kjell Rosquist

It is shown that the Lax pair equation dL/dt = [L,A] can be given a neat tensorial interpretation for finite-dimensional quadratic Hamiltonians. The Lax matrices L and A are shown to arise from third rank tensors on the configuration space. The second Lax matrix A is related to a connection which characterizes the Hamiltonian system. The Toda lattice system

Daniel Loss, Dmitrii L. Maslov

We study the spin stiffness of a one-dimensional quantum antiferromagnet in the whole range of system sizes $L$ and temperatures $T$. We show that for integer and half-odd integer spin case the stiffness differs fundamentally in its $L$ and $T$ dependence, and that in the latter case the stiffness exhibits a striking dependence on the parity of the number of

F. Wichmann, H. W. Diehl

The dynamic surface critical behavior of macroscopic systems whose dynamic bulk critical behavior is described by model $B$ is investigated. The semi-infinite extensions of bulk model $B$ introduced in a previous treatment [Phys. Rev. B 49, 2846 (1994)] and called models $B_A$ and $B_B$ are studied in detail by means of field-theoretic RG methods. The distin

G. De Zotti, A. Franceschini, P. Mazzei, L. Toffolatti

Current limits on the intensity of the extragalactic infrared background are consistent with the expected contribution from evolving galaxies. Depending on the behaviour of the star formation rate and of the initial mass function, we can expect that dust extinction during early evolutionary phases ranges from moderate to strong. An example of the latter case

Pedro Ferreira

We study the effects of cosmic strings on structure formation in open universes. We calculate the power spectrum of density perturbations for two class of models: one in which all the dark matter is non baryonic (CDM) and one in which it is all baryonic (BDM). Our results are compared to the 1 in 6 IRAS QDOT power spectrum. The best candidates are then used

Brad K. Gibson

The fundamental tenet of the classical supernovae-driven wind model of elliptical galaxies is that the residual thermal energy of all supernovae remnants (SNRs) provide sufficient energy to overcome the binding energy of the remaining interstellar gas, thereby driving a global galactic wind. We re-examine model predictions of this epoch of wind ejection t_GW

Luigi Guzzo

We discuss the rationale and the present status of a large redshift survey aiming at measuring distances for all the clusters of galaxies detected by the ROSAT X--ray All--Sky Survey in the southern hemisphere, with flux larger than $\sim 2\times 10^{-12}$ erg s$^{-1}$ cm$^{-2}$. The survey is being performed using three ESO telescopes in parallel. The final

Barbara Fantechi, Rita Pardini

By a recent result of Viehweg, projective manifolds with ample canonical class have a coarse moduli space, which is a union of quasiprojective varieties. In this paper, we prove that there are manifolds with ample canonical class that lie on arbitrarily many irreducible components of the moduli; moreover, for any finite abelian group $G$ there exist infinite

H. C. Rosu

I discuss the digital disorder introduced by Rosu and Canessa [Phys. Rev. E 47, R3818 (1993)] in the Davydov model of energy diffusion along α-helix protein chains. The digitally disordered Davydov beta kinks display self-organized features, i.e., power law correlations both in time and space, that may be attributed to incipient dynamic structural changes of

G. W. Gibbons, Gary T. Horowitz, P. K. Townsend

We show that the four-dimensional extreme dilaton black hole with dilaton coupling constant $a= \sqrt{p/(p+2)}$ can be interpreted as a {\it completely non-singular}, non-dilatonic, black $p$-brane in $(4+p)$ dimensions provided that $p$ is {\it odd}. Similar results are obtained for multi-black holes and dilatonic extended objects in higher spacetime dimens

Anthony J. Bracken, Mark D. Gould, Jon R. Links, Yao-Zhong Zhang

A new lattice model is presented for correlated electrons on the unrestricted $4^L$-dimensional electronic Hilbert space $\otimes_{n=1}^L{\bf C}^4$ (where $L$ is the lattice length). It is a supersymmetric generalization of the Hubbard model, but differs from the extended Hubbard model proposed by Essler, Korepin and Schoutens. The supersymmetry algebra of t

Marilyn A. Walker

In order to take steps towards establishing a methodology for evaluating Natural Language systems, we conducted a case study. We attempt to evaluate two different approaches to anaphoric processing in discourse by comparing the accuracy and coverage of two published algorithms for finding the co-specifiers of pronouns in naturally occurring texts and dialogu

Igor G. Korepanov

The transfer matrix of the 6-vertex model of two-dimensional statistical physics commutes with many (more complicated) transfer matrices, but these latter, generally, do not commute between each other. The studying of their action in the eigenspaces of the 6-vertex model transfer matrix becomes possible due to a ``multiplicative property'' of the {\em vacuum

Denis V. Juriev

This paper contains a summary of mathematical researches of stochastic properties of the long time behavior of a continuously observed (and interactively controlled) quantum--field top. Applications to interactively controlled stochastic computer-graphic dynamical systems are also discussed.

R. J. Radtke, K. Levin

Experiments on the cuprate superconductors demonstrate that these materials may be viewed as a stack of Josephson junctions along the c-direction. In this paper, we present a model which describes this intrinsic Josephson coupling in terms of incoherent quasiparticle hopping along the c-axis arising from wave-function overlap, impurity-assisted hopping, and

C. M. Yung, M. T. Batchelor

The procedure for obtaining integrable vertex models via reflection matrices on the square lattice with open boundaries is reviewed and explicitly carried out for a number of two- and three-state vertex models. These models include the six-vertex model, the 15-vertex $A_2^{(1)}$ model and the 19-vertex models of Izergin-Korepin and Zamolodchikov-Fateev. In e

M. Pitkänen

TGD suggests the existence of two new branches of physics, namely M_{89} hadron physics and M_{127} leptohadron physics. Leptons and U type quarks are predicted to have light colored excitations. The anomalous production of e^+e^- pairs in heavy ion collisions sup- ports the existence of light leptomeson but there are objections against light exotics. a) Asy

M. Pitkänen

This paper belongs to a series devoted to the calculation of particle masses in p-adic conformal field theory limit of TGD. In paper III elementary particle masses were calculated. In this paper the results are analyzed. One can reproduce lepton and gauge boson masses exactly by taking into account Coulomb self energy associated with the interior of 3-surfac

M. Pitkänen

This paper belongs to the series devoted to the calculation of particle masses in the framework of p-adic conformal field theory limit of Topological GeometroDynamics. In paper II the general formulation of p-adic Higgs mechanism was given. In this paper the calculation of the fermionic and bosonic masses is carried out. The calculation of the masses necessi

M. Pitkänen

This paper belongs to the series devoted to the calculation of particle masses in p-adic conformal field theory limit of TGD. The concept of topological condensate generalizes the concept of 3-space. Various hierarchically ordered levels of the condensate obey effective p-adic topology and fractal considerations motivate the hypothesis that physically intere

M. Pitkänen

This paper is the first one in the series devoted to the calculation of particle mass spectrum in Topological GeometroDynamics. TGD Universe is critical at quantum level and an attractive idea to realize criticality is via conformal invariance. Ordinary real numbers do not allow this but if one assumes that in long length scales p-adic topology replaces real

Viqar Husain

Self-dual gravity may be reformulated as the two dimensional principal chiral model with the group of area preserving diffeomorphisms as its gauge group. Using this formulation, it is shown that self-dual gravity contains an infinite dimensional hidden symmetry whose generators form the Affine (Kac-Moody) algebra associated with the Lie algebra of area prese

Gabriel Lopes Cardoso, Dieter Lüst, Burt A. Ovrut

It is pointed out that massive states in D=4, N=1 supergravity-matter theories can, in general, at the 1-loop level contribute non-holomorphic terms to quadratic gravitational couplings. It is then shown in the context of $(2,2)$-symmetric $Z_N$-orbifold theories that, for constant moduli backgrounds, the inclusion of such contributions can result in the can

D. Van Neck, A. E. L. Dieperink, E. Moya de Guerra

The spectral function for finite nuclei is computed within the framework of the Local Density Approximation, starting from nuclear matter spectral functions obtained with a realistic nucleon-nucleon interaction. The spectral function is decomposed into a single-particle part and a &#39;&#39;correlated&#39;&#39; part; the latter is treated in the local densit

W. Melnitchouk, A. W. Thomas

An explicit pionic component of the nucleon may be identified by measuring polarized $Δ^{++}$ fragments produced in deep-inelastic scattering off polarized protons. The pion-exchange model predicts highly correlated polarizations of the $Δ^{++}$ and target proton, in marked contrast with the competing diquark fragmentation process.

Avinash Dhar, Gautam Mandal, Spenta R. Wadia

We consider 2-dimensional QCD on a cylinder, where space is a circle. We find the ground state of the system in case of massless quarks in a $1/N$ expansion. We find that coupling to fermions nontrivially modifies the large $N$ saddle point of the gauge theory due to the phenomenon of `decompactification&#39; of eigenvalues of the gauge field. We calculate t

M. J. Martins, P. B. Ramos

We construct two $Osp(n|2m)$ solutions of the graded Yang-Baxter equation by using the algebraic braid-monoid approach. The factorizable S-matrix interpretation of these solutions is also discussed.

M. J. Martins

We present the exact solution of the $Osp(1|2)$ invariant magnet by the Bethe ansatz approach. The associated Bethe ansatz equation exhibit a new feature by presenting an explicit and distinct phase behaviour in even and odd sectors of the theory. The ground state, the low-lying excitations and the critical properties are discussed by exploiting the Bethe an

Tomás Ortín

We study the effect of S-duality and target-space duality tranformations of $N=4,d=4$ and $N=1,d=10$ supersymmetric configurations on their Killing spinors. We find that, under reasonable assumptions, the dual configurations are also supersymmetric and that the Killing spinors transform in a simple way.

Alok Kumar, Koushik Ray

Thermodynamic relations for a class of 2D black holes are obtained corresponding to observations made from finite spatial distances. We also study the thermodynamics of the charged version of the Jackiw-Teitelboim black holes found recently by Lowe and Strominger. Our results corroborate, in appropriate limits, to those obtained previously by other methods.

Ian I. Kogan, Alex Kovner

We apply a simple mean field like variational calculation to compact QED in 2+1 dimensions. Our variational ansatz explicitly preserves compact gauge invariance of the theory. We reproduce in this framework all the known results, including dynamical mass generation, Polyakov scaling and the nonzero string tension. It is hoped that this simple example can be

Gerald Dunne

In these lectures I review classical aspects of the self-dual Chern-Simons systems which describe charged scalar fields in $2+1$ dimensions coupled to a gauge field whose dynamics is provided by a pure Chern-Simons Lagrangian. These self-dual models have one realization with nonrelativistic dynamics for the scalar fields, and another with relativistic dynami

Vadim Zeitlin

A general expression for the conductivity in the QED$_{2+1}$ with nonzero fermion density in the uniform magnetic field is derived. It is shown that the conductivity is entirely determined by the Chern-Simons coefficient: $σ_{ij}=\varepsilon_{ij}~{\cal C}$ and is a step-function of the chemical potential and the magnetic field.

Robert Carroll

Dispersionless Hirota type equations are extracted from the dispersionless limit of the Fay differential identity due to Takasaki- Takebe. A few other results are sketched between inverse scattering, dKdV, and gravity.

Taejin Lee, Hyunsoo Min

Without assuming rotational invariance, we derive Bogomol&#39;nyi equations for the solitons in the abelian Chern-Simons gauge theories with the anomalous magnetic moment interaction. We also evaluate the number of zero modes around a static soliton configuration.

B. M. A. G. Piette, B. J. Schroers, W. J. Zakrzewski

Baby Skyrmions are topological solitons in a (2+1)-dimensional field theory which resembles the Skyrme model in important respects. We apply some of the techniques and approximations commonly used in discussions of the Skyrme model to the dynamics of baby Skyrmions and directly test them against numerical simulations. Specifically we study the effect of spin

D. B. Stamenov

A new representation of the next to leading QCD corrections to the nucleon structure functions is given in terms of parton distributions. All $~α_{s}~$ corrections to the leading logarithmic approximation (LLA) are included. In contrast to the similar representations in the literature terms of order $~O(α_{s}^{2})~$ do not attend in our expressions for the n

Niels R. Walet

We study the construction of the collective-coordinate manifold in the baryon number two sector of the Skyrme model. To that end we use techniques of adiabatic large amplitude collective motion, which treat potential and kinetic energy on an equal footing. In this paper the starting point is the Ansatz proposed by Atiyah and Manton (Phys.~Lett.~{\bf 438B}, 2

Lincoln Wolfenstein, Yue-Liang Wu

In the most general two-Higgs doublet model with an approximate family symmetry and CP violation being originated solely from the relative phase of two vacuum expectation values, CP asymmetry in the decay $b\rightarrow sγ$ may arise from the CP violation of the charged Higgs boson interactions with fermions. This asymmetry may be larger than in the standard

B. V. Geshkenbein, V. L. Morgunov

We computed the hadronic vacuum-polarization contributions to the muon anomalous magnetic moment $a_μ(hadr.)$ by using the QCD model with infinite number of vector mesons [1,2]. The result is $a_μ(hadr.) = 663(23) \times 10^{-10}$. }

I. G. Enting, A, J. Guttmann, I. Jensen

The finite lattice method of series expansion has been used to extend low-temperature series for the partition function, order parameter and susceptibility of the spin-1 Ising model on the square lattice. A new formalism is described that uses two distinct transfer matrix approaches in order to significantly reduce computer memory requirements and which perm

HENRYK PIEKARZ, D0 Collaboration

Properties of events originating from proton--antiproton interactions in which the total transverse energy of the event exceeded 400 GeV are presented. Based on a data sample of 5.45 pb-1, the topology of these hard scattering events as well as preliminary results for the cross--section versus total transverse energy are presented and discussed.

Junichi Iwasaki

We reformulate the Ponzano-Regge quantum gravity model in terms of surfaces on a 3-dimensional simplex lattice. This formulation (1) has a clear relation to the loop representation of the canonical quantum general relativity in 3-dimensions, (2) may have a 4-dimensional analogue, in contrast to the 6-j symbolic formalism of the Ponzano-Regge model, and (3) i

Rafe Mazzeo, Frank Pacard

The aim of this paper is to prove the existence of weak solutions to the equation $Δu + u^p = 0$ which are positive in a domain $Ω\subset {\Bbb R}^N$, vanish at the boundary, and have prescribed isolated singularities. The exponent $p$ is required to lie in the interval $(N/(N-2), (N+2)/(N-2))$. We also prove the existence of solutions to the equation $Δu +

K. I. Wysokinski, W. Park, D. Belitz, T. R. Kirkpatrick

We consider the mobility of electrons in an environment of static hard-sphere scatterers, which provides a realistic description of electrons in Helium gas. A systematic expansion in the scatterer density is carried to second order relative to the Boltzmann result, and the analytic contribution at this order is derived, together with the known logarithmic te

S. L. Sondhi, M. P. Gelfand, H. Q. Lin, D. K. Campbell

We have studied the effect of including nearest-neighbor, electron-electron interactions, in particular the off-diagonal (non density-density) terms, on the spectra of truncated tetrahedral and icosahedral ``Hubbard molecules,&#39;&#39; focusing on the relevance of these systems to the physics of doped C$_{60}$. Our perturbation theoretic and exact diagonali

V. Subrahmanyam

An $L \times \infty$ system of odd number of coupled Heisenberg spin chains is studied using a degenerate perturbation theory, where $L$ is the number of coupled chains. An effective chain Hamiltonian is derived explicitly in terms of two spin half degrees of freedom of a closed chain of $L$ sites, valid in the regime the inter-chain coupling is stronger tha