January 1995 arXiv papers — page 5

B. Grzadkowski, J. F. Gunion

We demonstrate that decay angle correlations in $\taum\taup$ and $t\anti t$ decay modes could allow a determination of whether or not a neutral Higgs boson is a CP eigenstate. Sensitivity of the correlations is illustrated in the case of the $\epem\rta Z \hn$ and $\mupmum\rta \hn$ production processes for a two-doublet Higgs model with CP-violating neutral s

S. Titard, F. J Yndurain

By relating fine and hyperfine spittings for l=1 states in bottomium we can factor out the less tractable part of the perturbative and nonperturbative effects. Reliable predictions for one of the fine splittings and the hyperfine splitting can then be made calculating in terms of the remaining fine splitting, which is then taken from experiment; perturbative

Zurab Berezhiani, Csaba Csaki, Lisa Randall

The doublet-triplet splitting problem is perhaps the most problematic aspect of supersymmetric grand unified theories. It can be argued that the most natural reason for the Higgs doublets to be light is that they are pseudo-Goldstone bosons associated with the spontaneous breakdown of an accidental global symmetry. In this paper we discuss the possibility of

R. Barbieri, L. Hall, A. Strumia

As a consequence of the large top quark Yukawa coupling, supersymmetric unified theories with soft supersymmetry breaking terms generated at the Planck scale predict lepton flavour and CP violating processes with significant rates. The flavour violating parameters of the low energy theory are derived in both SU(5) and SO(10) theories, and are used to calcula

R. Friedrich, H. Reinhardt

The $ρω$--mixing generated by the isospin breaking of the current quark masses $m_{u} \neq m_{d}$ is studied within the bosonized NJL model in the gradient expansion. The resulting effective meson lagrangian naturally incorperates vector meson dominance. By including pion loops an excellent description of both the pion electromagnetic form factor and of the

A. Capella

The enhancement of strange particle production observed in nucleus-nucleus collisions at CERN is explained by the combined effect of the increase in the relative number of strings containing strange constitutents at the ends, and the final state interaction of co-moving secondaries~: $π+ N \to K + Λ/Σ$.

L. Motyka, K. Zalewski

Experimental data for $b\bar{b}$ quarkonia have been compared with the predictions of a variety of nonrelativistic quark models. It is found that a potential $a\sqrt{r} - b/r +$ const gives good agreement, while many others do not. Some implications of this observation are discussed.

Sourendu Gupta

At the LHC, where hard multi-jet events are common, large imbalances in the total jet-\pt{} can arise due to the interaction of jets with the plasma formed in heavy-ion collisions. We find that this missing-\pt{} spectrum yields a measurement of the initial temperature of the plasma. Using commonly accepted guesses for this temperature, and ISAJET estimates

J. C. D'Olivo, J. F. Nieves

We use the method of finite temperature field theory to examine the propagation of mixed neutrinos through dense media, putting the emphasis in those situations in which the neutrinos themselves are in the background. The evolution equation for the flavor amplitudes is deduced, and the expressions for the corresponding hamiltonian matrix are given explicitly

T. Dasgupta, P. Mamales, Pran Nath

Limits on gravitational smearing from the dominant dimension 5 operator (with strength characterised by $cM/2M_{Planck}$) are obtained using the LEP data in supersymmetric SU(5) grand unification. Effects of c on the quasi infrared fixed point solutio ns of $m_b/m_τ$ unification are also analysed. It is found that $c>0$ softens and $c<0$ stiffens the fixed p

Neven Bilic, Jean Cleymans

The entropy per baryon is studied in the strong coupling large dimension $d$ limit of lattice QCD with staggered fermions. The partition function is calculated for non-zero chemical potential and temperature using the $1/d$ expansion. It is found that the entropy per baryon ratio is almost continuous across the transition from the the quark-gluon to the hadr

Hans - Jürgen Schmidt

An alternate Hamiltonian H different from Ostrogradski&#39;s one is found for the Lagrangian L = L(q, \dot q, \ddot q). We add a suitable divergence to L and insert a=q and b=\ddot q. Contrary to other approaches no constraint is needed because \ddot a = b is one of the canonical equations. Another canonical equation becomes equivalent to the fourth-order Eu

V. M. Manuilov

We show that elements of Hilbert $A$-module obtained by completion of the space of square-integrable functions on a space with measure $X$ taking values in a $C^*$-algebra $A$ cannot be viewed as $A$-valued functions on $X$ defined almost everywhere

R. Monasson, R. Zecchina

We analytically derive the geometrical structure of the weight space in multilayer neural networks (MLN), in terms of the volumes of couplings associated to the internal representations of the training set. Focusing on the parity and committee machines, we deduce their learning and generalization capabilities both reinterpreting some known properties and fin

A. S. Goldhaber, J. K. Jain

Composite fermions in a partially filled quasi-Landau level may be viewed as quasielectrons of the underlying fractional quantum Hall state, suggesting that a quasielectron is simply a dressed electron, as often is true in other interacting electron systems, and as a result has the same intrinsic charge and exchange statistics as an electron. This paper disc

Joachim Stolze, Angela Nöppert, Gerhard Müller

Dynamic spin correlation functions $<S_i^x (t)S_j^x>$ for the 1D $S=1/2$ $XX$ model $H = -JΣ_i \{S_i^x S_{i+1}^x + S_i^y S_{i+1}^y \}$ are calculated exactly for finite open chains with up to N=10000 spins. Over a certain time range the results are free of finite-size effects and thus represent correlation functions of an infinite chain (bulk regime) or a se

J. Casulleras, J. Boronat

A Monte Carlo algorithm for computing quantum mechanical expectation values of coordinate operators in many body problems is presented. The algorithm, that relies on the forward walking method, fits naturally in a Green&#39;s Function Monte Carlo calculation, i.e., it does not require side walks or a bilinear sampling method. Our method evidences stability r

Jongbae Hong, Hae-Young Kee

The Mott-Hubbard transition in the half-filled Hubbard model is studied analytically for the paramagnetic ground state and the classical Néel state. The single-particle density of states is obtained by calculating the Green&#39;s function represented by the infinite continued fraction. The paramagnetic solution shows that the Mott-Hubbard transition is signa

Ross H. McKenzie

A wide range of quasi-one-dimensional materials, consisting of weakly coupled chains, undergo three-dimensional phase transitions that can be described by a complex order parameter. A Ginzburg-Landau theory is derived for such a transition. It is shown that intrachain fluctuations in the order parameter play a crucial role and must be treated exactly. The ef

J. Joachim Quantz

In this paper I present a parser based on Description Logics (DL) for a German HPSG -style fragment. The specified parser relies mainly on the inferential capabilities of the underlying DL system. Given a preferential default extension for DL disambiguation is achieved by choosing the parse containing a qualitatively minimal number of exceptions.

Sangeeta D. Gadre, V. S. Varma

We demonstrate that chaos can be controlled using a multiplicative exponential feedback control. All three types of unstable orbits - unstable fixed points, limit cycles and chaotic trajectories can be stabilized using this control. The control is effective both for maps and flows. The control is significant, particularly for systems with several degrees of

Stefan Ebenfeld, Florian Scheck

Asymptotic behaviour of a tippe top, under the action of gliding friction. Liapunov stability analysis of the asymptotics of states with arbitrary initial conditions.

F. W. Stecker, O. C. De Jager

Following our previously proposed technique, we have used the recent gamma-ray observations of Mrk 421 to place theoretically significant constraints on and possible estimates of the intergalactic infrared radiation field (IIRF) which are consistent with normal galactic IR production by stars and dust and rule out exotic mechanisms proposed to produce a larg

F. W. Stecker, M. H. Salamon

We review and clarify the assumptions of our basic model for neutrino production in the cores of quasars, as well as those modifications to the model subsequently made by other workers. We also present a revised estimate of the neutrino background flux and spectrum obtained using more recent empirical studies of quasars and their evolution. We compare our re

Vincent Banchet, Gary A. Mamon, Matthieu Contensou

Using simulated images, we test various methods, for the homogeneous detection of objects in DENIS images. The optimal detection limits depend on the object type and the sky background, but little on the PSF or the smoothing filter used to increase the signal-to-noise of the images.

Gary A. Mamon

Near-infrared surveys have very promising cosmological applications. The DENIS 2 micron survey, currently in camera-testing, is scheduled to begin in early 1995, and to map the entire southern sky in the $I$, $J$, and $K&#39;$ bands. The steps for the near-homogeneous extraction of $\sim 10^5$ galaxies are outlined, some pitfalls are given, and the estimated

M. G. Olsson, S. Veseli, K. Williams

We formulate the description of the dynamic confinement of a single fermion by a flux tube. The range of applicability of this model extends from the relativistic corrections of a slowly moving quark to the ultra-relativistic motion in a heavy-light meson. The reduced Salpeter equation, also known as the no-pair equation, provides the framework for our discu

Ted von Hippel, Gerard Gilmore, D. H. P. Jones

The white dwarf luminosity function of a stellar cluster will have a sharp truncation at a luminosity which is determined by the time since formation of the first white dwarfs in that cluster. Calculation of the dependence of this limiting luminosity on age requires relatively well-understood physics and is independent of stellar evolutionary models. Thus, m

Eugene Golowich, Joachim Kambor

We perform a calculation of the isospin and hypercharge vector current propagators ($Δ_{V33}^{μν}(q^2)$ and $Δ_{V88}^{μν}(q^2)$) to two loops in chiral perturbation theory. The analysis is carried out with straightforward Feynman diagram methods by making appropriate use of external vector sources. Counterterms from the ${\cal O}(q^6)$ chiral lagrangian, req

Gerd Dethloff, Mikhail Zaidenberg

The general problem which initiated this work is: What are the quasiprojective varieties which can be uniformized by means of bounded domains in $\cz^n$ ? Such a variety should be, in particular, C--hyperbolic, i.e. it should have a Carathéodory hyperbolic covering. We study here the plane projective curves whose complements are C--hyperbolic. For instance,

Luca Peliti

Contents: 1. Introduction 2. Amphiphilic molecules and the phases they form 3. Isolated membranes: the Helfrich hamiltonian 4. Vesicle shapes 5. Shape fluctuations in vesicles 6. Interacting fluid membranes 7. Conclusions A. Differential equations for vesicle shapes B. The Faddeev-Popov determinant C. One-loop calculation of the renormalization group D. The

Saburo Kakei, Narimasa Sasa, Junkichi Satsuma

A generalized derivative nonlinear Schrödinger equation, \ii q_t + q_{xx} + 2\ii γ|q|^2 q_x + 2\ii (γ-1)q^2 q^*_x + (γ-1)(γ-2)|q|^4 q = 0 , is studied by means of Hirota&#39;s bilinear formalism. Soliton solutions are constructed as quotients of Wronski-type determinants. A relationship between the bilinear structure and gauge transformation is also discusse

Aephraim M. Steinberg

The question in the title may be answered by considering the outcome of a ``weak measurement&#39;&#39; in the sense of Aharonov et al. Various properties of the resulting time are discussed, including its close relation to the Larmor times. It is a universal description of a broad class of measurement interactions, and its physical implications are unambiguo

J. Katriel, B. Abdesselam, A. Chakrabarti

The irreducible representations (irreps) of the Hecke algebra $H_n(q)$ are shown to be completely characterized by the fundamental invariant of this algebra, $C_n$. This fundamental invariant is related to the quadratic Casimir operator, ${\cal{C}}_2$, of $SU_q(N)$, and reduces to the transposition class-sum, $[(2)]_n$, of $S_n$ when $q\rightarrow 1$. The pr

Jianming Zhang, Rahma Tabti, Charles Gale, Kevin Haglin

We compare different formalisms for the calculation of lepton pair emission in hadron-hadron collisions and discuss the consequences of the approximations inherent to each of them. Using a Lorentz-covariant and gauge-invariant formalism proposed by Lichard, we calculate lepton pair emission via bremsstrahlung in proton-proton and neutron-proton reactions at

Jicai Pan, Subal Das Gupta

We develop here a simple yet versatile model for nuclear fragmentation in heavy ion collisions. The model allows us to calculate thermodynamic properties such as phase transitions as well as the distribution of fragments at disassembly. In spite of its simplicity the model gives very good fit to recent data taken at the Michigan National Superconducting Cycl

Jicai Pan, Subal Das Gupta

We propose a model that provides a unified description of nuclear equation of state and fragmentations. The equation of state is evaluated in Bragg-Williams as well as in Bethe-Peierls approximations and compared with that in the mean field theory with Skyrme interactions. The model shows a liquid-gas type phase transition. The nuclear fragment distributions

M. Granzow, H. L. Harney, H. Kalka

The calculation of the spreading width of a compound nuclear reaction caused by a symmetry breaking $K$-body force acting in an $A$-body system ($K << A$, usually $K=2$) involves the determination of the local average square matrix element in $A$-body space. This problem is reduced to finding the global mean square matrix element $v^2$ in $K$-body space. The

Mark J. Stevens, Gary S. Grest

We examine two aspects of Stockmayer fluids which consists of point dipoles that additionally interact via an attractive Lennard-Jones potential. We perform Monte Carlo simulations to examine the effect of an applied field on the liquid-gas phase coexistence and show that a magnetic fluid phase does exist in the absence of an applied field. As part of the se

A. A. Kehagias, E. Papantonopoulos

We examine here discontinuities in the metric, the antisymmetric tensor and the dilaton field which are allowed by conformal invariance. We find that the surfaces of discontinuity must necessarily be null surfaces and shock and impulsive waves are both allowed. We employ our results for the case of colliding plane gravitational waves and we discuss the SL(2,

G. Papadopoulos, P. K. Townsend

We derive a bound on the energy of the general (p,q)-supersymmetric two-dimensional massive sigma model with torsion, in terms of the topological and Noether charges that appear as central charges in its supersymmetry algebra.The bound is saturated by soliton solutions of first-order Bogomol&#39;nyi-type equations. This generalizes results obtained previousl

P. K. Townsend

It is argued that the type IIA 10-dimensional superstring theory is actually a compactified 11-dimensional supermembrane theory in which the fundamental supermembrane is identified with the the solitonic membrane of 11-dimensional supergravity. The charged extreme black holes of the 10-dimensional type IIA string theory are interpreted as the Kaluza-Klein mo

E. Elizalde, S. D. Odintsov

Two models of dilatonic gravity are investigated: (i) dilaton-Yang-Mills gravity and (ii) higher-derivative dilatonic gravity. Both are renormalizable in $2+ε$ dimensions and have a smooth limit for $ε\rightarrow 0$. The corresponding one-loop effective actions and beta-functions are found. Both theories are shown to possess a non-trivial ultraviolet fixed p

R. Brustein, M. Gasperini, M. Giovannini, V. F. Mukhanov

We compute the spectrum of scalar and tensor metric perturbations generated, as amplified vacuum fluctuations, during an epoch of dilaton-driven inflation of the type occurring naturally in string cosmology. In the tensor case the computation is straightforward while, in the scalar case, it is made delicate by the appearance of a growing mode in the familiar

Alejandro Ayala, Jamal Jalilian-Marian, Larry McLerran, Raju Venugopalan

We carefully compute the gluon propagator in the background of a non--Abelian Weizsäcker--Williams field. This background field is generated by the valence quarks in very large nuclei. We find contact terms in the small fluctuation equations of motion which induce corrections to a previously incorrect result for the gluon propagator in such a background fiel

Axel de la Macorra

We consider the low energy phenomenology of superstrings. In particular we analyse supersymmetry breaking via gaugino condensate and we compare the phenomenology of the two different approaches to stabilize the dilaton field. We study the cosmological constant problem and we show that it is possible to have supersymmetry broken and zero cosmological constant

Dan Moenster Jensen, Jes Madsen

A description of strange quark matter at finite temperature is given, with emphasis on the inclusion of finite size effects. For massless quarks all thermodynamic quantities can be evaluated analytically, while the case of massive quarks must be treated numerically. The resulting model is applied to the phase equilibrium between strange hadronic matter and s

Howard E. Haber

In models with a non-minimal Higgs sector, a decoupling limit can be defined. In this limit, the masses of all the physical Higgs states are large (compared to the scale of electroweak symmetry breaking) except for one neutral CP-even Higgs scalar, whose properties are indistinguishable from the Higgs boson of the minimal Standard Model. The decoupling limit

B. L. Ioffe

The calculation method of the hadron interaction vertex with constant external fields in QCD sum rules is discussed. The representation of the polarization operator in terms of physical states contributions is considered and the most suitable form of this representation is suggested. The estimates of uncertainties in the previous calculations of hadron inter

J. Kripfganz, A. Laser, M. G. Schmidt

We calculate the high-temperature two-loop effective potential using a general &#39;t~Hooft background gauge. The dependence on the gauge-fixing parameter $ξ$ is investigated. The effective coupling constant at the critical temperature $g_3(T_c)^2$ is decreased considerably compared to the one-loop result, independent of $ξ$.

Harald Fritzsch

A simple breaking of the subnuclear democracy of the quarks leads to a mixing between the secons and the third family, in agreement with observation. Introducing the mixing between the first and the second family, one finds an interesting pattern of maximal CP-violation as well as complete determination of the elements of the CKM matrix and of the unitarity

Marco A. Diaz, Tonnis A. ter Veldhuis

We study one loop electroweak corrections to the production of a pair of charged Higgs bosons through an intermediate $Z$-boson or photon. In particular, we consider the effects of graphs with top and bottom quarks and squarks in the loop within the context of the Minimal Supersymmetric Model. We find that the corrections can be considerable, and typically a

J. Bartels, H. Lotter, M. Wuesthoff

The small-$t$ behaviour of the deep inelastic diffractive dissociation cross section in the triple Regge region is investigated, using the BFKL approximation in perturbative QCD. We show that the cross section is finite at $t=0$, but the diffusion in $\ln{k_t^2}$ leads to a large contribution of small momenta at the triple Pomeron vertex. We study the depend

R. Kobayashi, S. Kumano, M. Miyama

Nuclear modification of the structure function $F_3$ is investigated. Although it could be estimated in the medium and large $x$ regions from the nuclear structure function $F_2^A$, it is essentially unknown at small $x$. The nuclear structure function $F_3^A$ at small $x$ is investigated in two different theoretical models: a parton-recombination model with

Tetsuya Shiromizu, Masahiro Morikawa, Jun&#39;ichi Yokoyama

We estimate the amplitude of thermal fluctuations by calculating the typical size of subcritical bubbles in cosmological electroweak phase transition and show that this thermal fluctuation effect drastically changes dynamics of the phase transition from the ordinary first order type with supercooling. From this fact, we conclude that the standard electroweak

H. Kroger, S. Lantagne, K. J. M. Moriarty, B. Plache

We measure the propagator length in imaginary time quantum mechanics by Monte Carlo simulation on a lattice and extract the Hausdorff dimension $d_{H}$. We find that all local potentials fall into the same universality class giving $d_{H}=2$ like the free motion. A velocity dependent action ($S \propto \int dt \mid \vec{v} \mid^α$) in the path integral (e.g.

Rajan Gupta

The recent woes of the supercomputer industry and changes in federal funding have caused some scientists to re-evaluate the means by which they hope to solve Grand Challenge problems. I evaluate the potential of Massively Parallel Processors (MPP) within this context and the state of today&#39;s MPP. I stress that for solving large-scale problems MPP are cru

J. M. Izquierdo, P. K. Townsend

We find a class of (2+1)-dimensional spacetimes admitting Killing spinors appropriate to (2,0) adS-supergravity. The vacuum spacetimes include anti-de Sitter (adS) space and charged extreme black holes, but there are many others, including spacetimes of arbitrarily large negative energy that have only conical singularities, and the spacetimes of fractionally

J. Gegenberg, G. Kunstatter, D. Louis-Martinez

A unified description is presented of the physical observables and thermodynamic variables associated with black hole solutions in generic 2-D dilaton gravity. The Dirac quantization of these theories is reviewed and an intriguing relationship between the entropy of the black hole and the WKB phase of the corresponding physical wave functionals is revealed.

Mark Goulian, Scott T. Milner

We consider the shear flow of well-aligned one-component smectic phases, such as thermotropic smectics and lamellar diblock copolymers, below the critical region. We show that, as a result of thermal fluctuations of the layers, parallel ($c$) alignment is generically unstable and perpendicular ($a$) alignment is stable against long-wavelength undulations. We

Vladimir E. Kravtsov, Igor V. Lerner

We consider the two-level correlation function in two-dimensional disordered systems. In the non-ergodic diffusive regime, at energy $ε>E_{c}$ ($E_{c}$ is the Thouless energy), it is shown to be completely determined by the weak localization effects, thus being extremely sensitive to time-reversal and spin symmetry breaking: it decreases drastically in the p

Arkady G. Aronov, Vladimir E. Kravtsov, Igor V. Lerner

We use the semiclassical approach combined with the scaling results for the diffusion coefficient to consider the two-level correlation function $R(\varepsilon)$ for a disordered electron system in the crossover region, characterized by the appearance of a macroscopic correlation or localization length, $ξ$, that diverges at the metal-insulator transition. W

A. D. Rutenberg

Scaling violations are found in the phase-ordering two-dimensional Heisenberg [$O(3)$] model, which has non-singular topological textures, under dissipative non-conserved dynamics. Three separate length-scales are found: $L_T$ characterizes the scale of individual textures, $L_N$ characterizes the separation between textures, and $L_C$ characterizes the dist

D. A. Stariolo, E. M. F. Curado, F. A. Tamarit

Using Grassmann variables and an analogy with two dimensional electrostatics, we obtain the average eigenvalue distribution $ρ(ω)$ of ensembles of $N \times N$ asymmetrically diluted Hopfield matrices in the limit $N \rightarrow \infty$. We found that in the limit of strong dilution the distribution is uniform in a circle in the complex plane.

C. De Dominicis, H. Orland, T. Temesvari

The stability of the random field Ising model (RFIM) against spin glass (SG) fluctuations, as investigated by Mézard and Young, is naturally expressed via Legendre transforms, stability being then associated with the non-negativeness of eigenvalues of the inverse of a generalized SG susceptibility matrix. It is found that the signal for the occurrence of the

Wlodek Zadrozny, Marcin Szummer, Stanislaw Jarecki, David E. Johnson

We present an approach to natural language understanding based on a computable grammar of constructions. A &#34;construction&#34; consists of a set of features of form and a description of meaning in a context. A grammar is a set of constructions. This kind of grammar is the key element of Mincal, an implemented natural language, speech-enabled interface to

Alex Lazarian

Paramagnetic alignment of suprathermally rotating grains is discussed in view of recent progress in understanding subtle processes taking place over grain surface. It is shown that in typical ISM conditions, grains with surfaces of amorphous H$_{2}$O ice, defected silicate or polymeric carbonaceous material are likely to exhibit enhanced alignment, while tho

Robin Tuluie, Pablo Laguna

We investigate the imprint of nonlinear matter condensations on the Cosmic Microwave Background (CMB) in an $Ω=1$, Cold Dark Matter (CDM) model universe. Temperature anisotropies are obtained by numerically evolving matter inhomogeneities and CMB photons from the beginning of decoupling until the present epoch. The underlying density field produced by the in

Brian Chaboyer, P. Demarque, D. B. Guenther, M. H. Pinsonneault

We have studied the importance of the combined effects of rotation, diffusion, and convective overshoot on the p-mode oscillation spectrum and the neutrino flux of the standard solar model. To isolate the various physical affects included in the new rotation plus diffusion models we also constructed solar models to test the significance of diffusion and of o

J. F. L. Simmons, A. M. Newsam, J. P. Willis

Microlensing of extended stellar sources in the LMC and Galaxy by low mass lenses can produce variable polarisation. The characteristics of the polarisation and flux profiles can provide considerable information about the lens geometry, and help determine the importance of such low mass objects as a dark matter component.

Takahiko Matsubara

We develop technique concerning statistical analyses of the large-scale structure of the universe in the presence of biasing in the structure formation. We formulate the diagrammatic method to calculate the correlation functions of the nonlocally biased field from a generally non-Gaussian density field. Our method is based on generalized Wiener-Hermite expan

Takahiko Matsubara

The peculiar velocities of galaxies distort the clustering pattern anisotropically in redshift space. This effect on the statistics of isodensity contours is examined by linear theory. The statistics considered in this paper are the three- and two-dimensional genus of isodensity contours, the area of isodensity contours, the length of isodensity contours in

C. M. Carollo, P. T. de Zeeuw, R. P. van der Marel

A simple algorithm is presented for the calculation of the projected line-of-sight velocity profiles (VPs) of non-rotating anisotropic spherical stellar dynamical models with a phase-space distribution function of the Osipkov-Merritt type. The velocity distribution in these models is isotropic inside the anisotropy radius r_a and becomes increasingly radiall

Barbara Fantechi, Rita Pardini

In this paper we prove that, for any $n\ge 3$, there exist infinitely many $r\in \N$ and for each of them a smooth, connected curve $C_r$ in $¶^r$ such that $C_r$ lies on exactly $n$ irreducible components of the Hilbert scheme $\hilb(¶^r)$. This is proven by reducing the problem to an analogous statement for the moduli of surfaces of general type.

Arnaud Beauville

The quantum cohomology algebra of a projective manifold X is the cohomology H(X,Q) endowed with a different algebra structure, which takes into account the geometry of rational curves in X. We show that this algebra takes a remarkably simple form for complete intersections when the dimension is large enough w.r.t. the degree. As a reward we get a number of s

Carson C. Chow, J. J. Collins

A phenomenological model of human posture control is posited. The dynamics are modelled as an elastically pinned polymer under the influence of noise. The model accurately reproduces the two-point correlation functions of experimental posture data and makes predictions for the response function of the postural control system. The physiological and clinical s

Mijo Batinic, Ivo Slaus, Alfred Svarc, B. M. K. Nefkens

The pi N --> eta N and eta N --> eta N partial wave T-matrices for the eight lowest partial waves have been obtained in a three coupled channel model with unitarity manifestly imposed. The two physical channels are pi_N and eta_N, and the third channel, pi_pi_N is an effective, but unphysical two body channel which represents all remaining processes. The pi_

H. -J. Kwon, A. Houghton, J. B. Marston

We develop a general theory of fermion liquids in spatial dimensions greater than one. The principal method, bosonization, is applied to the cases of short and long range longitudinal interactions, and to transverse gauge interactions. All the correlation functions of the system may be obtained with the use of a generating functional. Short-range and Coulomb

John Baez, Javier P. Muniain, Dardo Piriz

In canonical quantum gravity, when space is a compact manifold with boundary there is a Hamiltonian given by an integral over the boundary. Here we compute the action of this `boundary Hamiltonian&#39; on observables corresponding to open Wilson lines in the new variables formulation of quantum gravity. In cases where the boundary conditions fix the metric o

Claudio de C. Chamon, Christopher Mudry, Xiao-Gang Wen

Recently, in an attempt to study disordered criticality in Quantum Hall systems and $d$-wave superconductivity, it was found that two dimensional random Dirac fermion systems contain a line of critical points which is connected to the pure system. We use bosonization and current algebra to study properties of the critical line and calculate the exact scaling

Seb Oliver

There has been some disagreement about the strength of evolution exhibited by IRAS galaxies. With a parameterisation such that the co-moving density increases as $(1+z)^P$ measurements of $P$ range from $2\pm3$ to $6.7\pm2.3$. We have recently completed a deep IRAS redshift survey which should help to clarify the situation. Paying particular attention to pos

F. A. Smirnov

In terms of the form factor bootstrap we describe all the local fields in SG theory and check the agreement with the free fermion case. We discuss the interesting structure responsible for counting the local fields.

Elijah Liflyand

This is an attempt of a comprehensive survey of the results in which estimates of the norms of linear means of multiple Fourier series, the Lebesgue constants, are obtained by means of estimating the Fourier transform of a function generating such a method. Only few proofs are given in order to illustrate a general idea of techniques applied. Among the resul

V. P. Gusynin, V. A. Miransky, I. A. Shovkovy

It is shown that the chiral symmetry is spontaneously broken by a constant magnetic field in QED. The dynamical mass of fermions (energy gap in the fermion spectrum) is $m_{dyn}\simeq C\sqrt{eB}\exp\left[-\left(π/α\right) ^{1/2}\right]$, where $B$ is the magnetic field, the constant $C$ is of order one and $α=e^2/4π$ is the renormalized coupling constant. Po

Zvi Schreiber

This MSc dissertation surveys nine interpretations of non-relativistic quantum mechanics. Extensive references are given. The interpretations covered are: the orthodox interpretation, Bohr&#39;s interpretation, the idea that the mind causes collapse, hidden variables, the many-worlds interpretation, the many-minds interpretation, Bohm&#39;s interpretation an

Aephraim M. Steinberg, Raymond Y. Chiao

Using a two-photon interference technique, we measure the delay for single-photon wavepackets to be transmitted through a multilayer dielectric mirror, which functions as a ``photonic bandgap&#39;&#39; medium. By varying the angle of incidence, we are able to confirm the behavior predicted by the group delay (stationary phase approximation), including a vari

T. D. Palev, J. Van der Jeugt

We recall the relation between the Lie superalgebra $osp(1/2n)$ and para-Bose operators. The quantum superalgebra $U_q[osp(1/2n)]$, defined as usual in terms of its Chevalley generators, is shown to be isomorphic to an associative algebra generated by so-called pre-oscillator operators satisfying a number of relations. From these relations, and the analogue

A. A. Balinsky, Yu. M. Burman

Quadratic Poisson brackets on associative algebras are studied. Such a bracket compatible with the multiplication is related to a differentiation in tensor square of the underlying algebra. Jacobi identity means that this differentiation satisfies a classical Yang--Baxter equation. Corresponding Lie groups are canonically equipped with a Poisson Lie structur

J. A. Eden, M. F. Gari

We present pp-bremsstrahlung cross section calculations at the $π$-production threshold to search for kinematics that best differentiate model-dependent descriptions of the NN $t$-matrix and accentuate the contributions of isoscalar meson-exchange currents. Existing optimization procedures are shown to be completely unreliable due to the neglect of meson-exc

L. L. Frankfurt, W. R. Greenberg, G. A. Miller, M. M. Sargsyan

High momentum transfer electrodisintegration of polarized and unpolarized deuterium targets, $d(e,e&#39;p)n$ is studied. We show that the importance of final state interactions-FSI, occuring when a knocked out nucleon interacts with the other nucleon, depends strongly on the momentum of the spectator nucleon. In particular, these FSI occur when the essential

K. Kirsten, M. Bordag

We consider the heat-kernel expansion of the massive Laplace operator on the three dimensional ball with Dirichlet boundary conditions. Using this example, we illustrate a very effective scheme for the calculation of an (in principle) arbitrary number of heat-kernel coefficients for the case where the basis functions are known. New results for the coefficien

Detlev Buchholz, Rainer Verch

For any given algebra of local observables in Minkowski space an associated scaling algebra is constructed on which renormalization group (scaling) transformations act in a canonical manner. The method can be carried over to arbitrary spacetime manifolds and provides a framework for the systematic analysis of the short distance properties of local quantum fi

Zhan-Ning Hu

Using the restricted star-triangle relation, it is shown that the $N$-state spin integrable model on a three-dimensional lattice with spins interacting round each elementary cube of the lattice proposed by Mangazeev, Sergeev and Stroganov is a particular case of the Bazhanov-Baxter model.

Ch. Devchand, V. Ogievetsky

The N-extended supersymmetric self-dual Poincaré supergravity equations provide a natural local description of supermanifolds possessing hyperkähler structure. These equations admit an economical formulation in chiral superspace. A reformulation in harmonic superspace encodes self-dual supervielbeins and superconnections in a graded skew-symmetric supermatri

Nathan Weiss

In this talk I discuss both the present status and some recent work on the Kazakov--Migdal Model which was originally proposed as a soluble, large $N$ realization of QCD. After a brief description of the model and a discussion of its solubility in the large $N$ limit I discuss several of the serious problems with the model which lead to the conclusion that i

N. ~Shtykov, D. ~V. ~Vassilevich

We compute the Casimir energy for a free scalar field on the spaces $\,R^{m+1}\,\times\,\tilde S^2\,$ where $,\tilde S^2\,$ is two-dimensional deformed two-sphere.

Wolfgang Ochs

Predictions for angular correlations between an arbitrary number of partons are derived in the high energy limit. The quantities considered depend on angles and primary energy through a single variable $ε$ which implies certain scaling properties and relations between quite different observables. These asymptotic predictions derived in the double log approxi

M. F. McDermott, J. R. Forshaw, G. G. Ross

We outline a general method for obtaining the solution to the ($t=0$) BFKL equation in the presence of transverse momentum cutoffs. A lower cutoff allows one to avoid integration over nonperturbative momenta and an upper one is needed from energy-momentum conservation. Our method allows for the inclusion of an arbitrary number of poles in the kernel and is a

WOLFGANG OCHS

We compare QCD predictions with experimental data on inclusive multiparticle observables whereby we discuss various realizations of the idea of parton hadron duality which is related to a soft confinement mechanism. Special emphasis is given on effects from the running $α_s$, the soft gluon interference, scaling properties and the role of the limiting scale

G. T. Gabadadze

The value of the proton singlet axial constant is estimated. It has been shown that the axial anomaly plays a crucial role in this calculation. Obtained result is sufficiently suppressed in comparison with the naively expected one. The magnitude of the strange quark contribution for the proton state is also computed approximately.