October 1994 arXiv papers — page 2

Timothy Banks, D. J. Sullivan, M. C. Forbes, R. J. Dodd

The Vilnius Photometric system has been used with a CCD system only once before this study. Preliminary crowded field reductions of Vilnius CCD observations of the star clusters NGC~2004 and NGC~4755 (the $κ$ Crucis cluster) are presented, demonstrating the feasibility of using the filter set in this manner.

Philip Nelson, Thomas Powers, Udo Seifert

We give a simple theory for recent experiments of Bar-Ziv and Moses% Phys. Rev. Lett. {\bf73} (1994) 1392, in which tubular vesicles are excited using laser tweezers to a ``peristaltic'' state. Considering the hydrodynamics of a bilayer membrane under tension, we reproduce some of the qualitative behavior seen and find a value for the wavelength of t

S. Ogut, K. M. Rabe

The structural stability and electronic properties of the ternary intermetallic compounds NiSnM (M = Ti, Zr, Hf) and the closely related Heusler compounds Ni$_2$SnM are discussed using the results of ab initio pseudopotential total energy and band-structure calculations performed with a plane wave basis set using the conjugate gradients algorithm. The result

M. J. Duff

String theory requires two kinds of loop expansion: classical $(α&#39;)$ worldsheet loops with expansion parameter $<T>$ where $T$ is a modulus field, and quantum $(\hbar)$ spacetime loops with expansion parameter $<S>$ where $S$ is the dilaton field. Four-dimensional string/string duality (a corollary of ten-dimensional string/fivebrane duality) interchange

G. Aldazabal, A. Font, L. E. Ibanez, A. M. Uranga

Standard SUSY-GUTs such as those based on $SU(5)$ or $SO(10)$ lead to predictions for the values of $α_s$ and $sin^2θ_W$ in amazing agreement with experiment. In this article we investigate how these models may be obtained from string theory, thus bringing them into the only known consistent framework for quantum gravity. String models with matter in standar

G. W. Botz, P. Haberl, O. Nachtmann

We discuss the production of soft photons in high energy hadron-hadron collisions. We present a model where quarks and antiquarks in the hadrons emit ``synchrotron light&#39;&#39; when being deflected by the chromomagnetic fields of the QCD vacuum, which we assume to have a nonperturbative structure. This gives a source of prompt soft photons with frequencie

F. Delduc, L. Feher

Generalized KdV hierarchies associated by Drinfeld-Sokolov reduction to grade one regular semisimple elements from non-equivalent Heisenberg subalgebras of a loop algebra $\G\otimes{\bf C}[λ,λ^{-1}]$ are studied. The graded Heisenberg subalgebras containing such elements are labelled by the regular conjugacy classes in the Weyl group ${\bf W}(\G)$ of the sim

C. S. Lim, H. Nunokawa

It is emphasized that the $E_ν$ (neutrino energy) spectrum of the $ν_e$ survival probability in the Resonant Spin-Flavor Precession (RSFP) scenario has very desirable shape to reconcile all existing solar neutrino data. As the result, the RSFP scenario is shown to have rather broad allowed region to reconcile the data in the ($B,\ Δm^2$) plane, with $B$ bein

R. D. Benguria, M. C. Depassier

We show that the minimal speed for the existence of monotonic fronts of the equation $u_t = (u^m)_{xx} + f(u)$ with $f(0) = f(1) = 0$, $m >1$ and $f>0$ in $(0,1)$ derives from a variational principle. The variational principle allows to calculate, in principle, the exact speed for arbitrary $f$. The case $m=1$ when $f&#39;(0)=0$ is included as an extension o

Nicole Marshall, Gordon W. Semenoff, Richard J. Szabo

We study the large-$N$ limit of adjoint fermion one-matrix models. We find one-cut solutions of the loop equations for the correlators of these models and show that they exhibit third order phase transitions associated with $m$-th order multi-critical points with string susceptibility exponents $γ_{\rm str}=-1/m$. We also find critical points which can be in

David J. Fernández C

The cyclic evolutions and associated geometric phases induced by time-independent Hamiltonians are studied for the case when the evolution operator becomes the identity (those processes are called {\it evolution loops}). We make a detailed treatment of systems having equally-spaced energy levels. Special emphasis is made on the potentials which have the same

E. Kiritsis, C. Kounnas

We construct a new class of exact and stable superstring solutions in which our four-dimensional spacetime is taken to be curved . We derive in this space the full one-loop partition function in the presence of non-zero $\langle F^a_{μν}F_a^{μν}\rangle=F^2$ gauge background as well as in an $\langle R_{μνρσ}R^{μνρσ}\rangle=\R^2$ gravitational background and

J. L. Jacquot, J. Richert, M. Umezawa

In comparison with the $WT$ chiral identity which is indispensable for renormalization theory, relations deduced from the non-linear chiral transformation have a totally different physical significance. We wish to show that non-linear chiral transformations are powerful tools to deduce useful integral equations for propagators. In contrast to the case of lin

V. B. Petkova, J. -B. Zuber

Structure constants of minimal conformal theories are reconsidered. It is shown that {\it ratios} of structure constants of spin zero fields of a non-diagonal theory over the same evaluated in the diagonal theory are given by a simple expression in terms of the components of the eigenvectors of the adjacency matrix of the corresponding Dynkin diagram. This i

Pavel Etingof

In this note we prove the Davies-Foda-Jimbo-Miwa-Nakayashiki conjecture on the asymptotics of the composition of n quantum vertex operators for the quantum affine algebra U_q(\hat sl_2), as n goes to infinity. For this purpose we define and study the leading eigenvalue and eigenvector of the product of two components of the quantum vertex operator. This eige

M. Pitkänen

The concept of $Diff^4$ invariant Poincare transformations is a cornerstone of T(opological) G(eometro)D(ynamics). This concept makes it possible to understand the concept of subjective time and irreversibelity as well as nontriviality of S-matrix at quantum level. In this paper the possibility of identifying $Diff^4$ invariant Poincare transformations as th

Z. Lalak, A. Niemeyer, H. P. Nilles

The principle of S-duality is used to incorporate gaugino condensates into effective supergravity (superstring) Lagrangians. We discuss two implementations of S-duality which differ in the way the coupling constant is transformed. Both solve the problem of the runaway dilaton and lead to satisfactory supersymmetry breaking in models with a {\em single} gaugi

J. S. Dowker, J. S. Apps

Some calculational errors in expressions derived previously by the first author for the effective action, or equivalently for the functional determinant, on sectors of a spherical cap are corrected. The formula for the change in the effective action under Weyl rescalings in the three dimensional case is also amended.

S. Catani, F. Hautmann

We discuss the role of sub-leading corrections to deep inelastic processes in the small-x regime, and report recent results on the calculation of coefficient functions and quark anomalous dimensions. *To appear in the proceedings of the workshop QCD94, Montpellier, July &#39;94.

S. Catani, F. Hautmann

The perturbative QCD approach to quarkonium decay into a photon and hadrons is reconsidered. It is shown that a consistent treatment within perturbative QCD calls for the introduction of a fragmentation contribution which has been neglected so far. The ensuing phenomenological implications are discussed, and, in particular, the possibility of measuring the g

Alan Chodos

A formalism is developed to enable the construction of the effective action and related quantities in QED for the case of time-varying background electric fields. Some examples are studied and evidence is sought for a possible transition to a phase in which chiral symmetry is spontaneously broken. YCTP-P14-94

Bernd A. Kniehl

We review recent theoretical progress in the computation of radiative corrections beyond one loop within the standard model of electroweak interactions, both in the gauge and Higgs sectors. In the gauge sector, we discuss universal corrections of $Ø(G_F^2M_H^2M_W^2)$, $Ø(G_F^2m_t^4)$, $Ø(α_sG_FM_W^2)$, and those due to virtual $t\bar t$ threshold effects, as

Vladimir Privman, Enrique Burgos, Marcelo D. Grynberg

We study the effect of anisotropic diffusion on the one-dimensional annihilation reaction kA->inert with partial reaction probabilities when hard-core particles meet in groups of k nearest neighbors. Based on scaling arguments, mean field approaches and random walk considerations we argue that the spatial anisotropy introduces no appreciable changes as compa

F Cecconi, A Crisanti, M Falcioni A Vulpiani

A one-dimensional chain of sporadic maps with asymmetric nearest neighbour couplings is numerically studied. It is shown that in the region of strong asymmetry the system becomes spatially fully synchronized, even in the thermodinamic limit, while the Lyapunov exponent is zero. For weak asymmetry the synchronization is no more complete, and the Lyapunov expo

Damien Genthial, Jacques Courtin, Jacques Menezo Equipe Trilan

We first present our view of detection and correction of syntactic errors. We then introduce a new correction method, based on heuristic criteria used to decide which correction should be preferred. Weighting of these criteria leads to a flexible and parametrable system, which can adapt itself to the user. A partitioning of the trees based on linguistic crit

M. White, E. Bunn

We use a Maximum Entropy technique to reconstruct a map of the microwave sky near the star Gamma Ursae Minoris, based on data from flights 2, 3 and 4 of the Millimeter-wave Anisotropy eXperiment (MAX).

R. Zylka, P. G. Mezger, D. Ward-Thompson, W. J. Duschl

We present submm images of Sgr A* and its surroundings obtained at 800, 600 and 450 $μ$m with the JCMT and derive flux densities of Sgr A* at all three wave- lengths. Combined with upper limits by Gezari and associates at MIR wavelengths a time averaged radio spectrum is obtained which increases $\propto ν^{1/3}$, attains a maximum at $ν_max \ga 600 GHz$ and

F. A. Rasio, S. L. Shapiro

In addition to their possible relevance to gamma-ray bursts, coalescing binary neutron stars have long been recognized as important sources of gravitational radiation that should become detectable with the new generation of laser interferometers such as LIGO. Hydrodynamics plays an essential role near the end of the coalescence when the two stars finally mer

Garrelt Mellema, Adam Frank

This paper looks into various aspects brought to light by numerical work on the generalized interacting winds model for planetary nebulae. First, a detailed comparison between radiative and non-radiative models is made, showing that one&#39;s naive expectations of the effects of radiative heating and cooling are not always true. Secondly, we consider the evo

Andrew R Liddle

An examination is made of the widely held belief that inflation is the only possible causal mechanism capable of generating density perturbations on scales well in excess of the Hubble radius. A simple proof is given, which relies only on the assumption that our understanding of the universe from nucleosynthesis onwards is correct. No assumption of the under

Annapurni Subramaniam, Ram Sagar

We compare the observed colour-magnitude diagrams (CMD) and the main sequence luminosity functions (LFs) of four Large Magellanic Cloud (LMC) star clusters namely, NGC 1711, NGC 2004, NGC 2164 and NGC 2214 with the synthetic ones derived from the stellar evolutionary models. Four different types of stellar evolutionary models have been used for comparison. T

M. Andreatta, M. Mella

A complex manifold $X$ of dimension $n$ together with an ample vector bundle $E$ on it will be called a {\sf generalized polarized variety}. The adjoint bundle of the pair $(X,E)$ is the line bundle $K_X + det(E)$. We study the positivity (the nefness or ampleness) of the adjoint bundle in the case $r := rank (E) = (n-2)$. If $r\geq (n-1)$ this was previousl

Bruce Crauder, Rick Miranda

In this article formulas for the quantum product of a rational surface are given, and used to give an algebro-geometric proof of the associativity of the quantum product for strict Del Pezzo surfaces, those for which $-K$ is very ample. An argument for the associativity in general is proposed, which also avoids resorting to the symplectic category. The enume

Deshpande, He, Trampetic

We study elelctroweak penguin contributions in pure hadronic $B$ decays in the Standard and two-Higgs-doublet models. We find that in $B_s\rightarrow π^0 (η\;, ϕ)$ and $B_s\rightarrow ρ^0 (η\;, ϕ)$ decays, the electroweak penguin contributions dominate over all other contribuitons. These processes provide unique signatures of electroweak penguin in pure hadr

Bernardo A. Huberman, Tad Hogg

We present a detailed model of collaboration in communities of practice and we examine its dynamical consequences for the group as a whole. We establish the existence of a novel mechanism that allows the community to naturally adapt to growth, specialization, or changes in the environment without the need for central controls. This mechanism relies on the ap

Z. N. C. Ha

One-dimensional fractional statistics is studied using the Calogero-Sutherland model (CSM) which describes a system of non-relativistic quantum particles interacting with inverse-square two-body potential on a ring. The inverse-square exchange can be regarded as a pure statistical interaction and this system can be mapped to an ideal gas obeying the fraction

Simon Davis

The four-point function arising in the scattering of closed bosonic strings in their tachyonic ground state is evaluated on a surface of infinite genus. The amplitude has poles corresponding to physical intermediate states and divergences at the boundary of moduli space, but no new types of divergences result from the infinite number of handles. The implicat

Oscar Diego

In this letter I study the universality of the nonperturbative effects and the vacua structure of the stochastic stabilization of the matrix models which defines Pure 2D Quantum Gravity. I show also that there is not tunneling, in the continuum limit, between the one-arc and three-arc solutions of the simplest matrix model which defines the flow between Pure

M. Caselle

We solve the Dorokhov-Mello-Pereyra-Kumar equation which describes the evolution of an ensamble of disordered wires of increasing length in the three cases $β=1,2,4$. The solution is obtained by mapping the problem in that of a suitable Calogero-Sutherland model. In the $β=2$ case our solution is in complete agreement with that recently found by Beenakker an

C. Bourrely, F. Buccella, G. Miele, G

We propose to use Fermi-Dirac distributions for quark and antiquark partons. It allows a fair description of the $x$-dependence of the very recent NMC data on the proton and neutron structure functions $F_2^p(x)$ and $F_2^n(x)$ at $Q^2=4$ GeV$^2$, as well as the CCFR antiquark distribution $x\overline q(x)$. We show that one can also use a corresponding Bose

Piotr G. Grinevich, Roman G. Novikov

For the two-dimensional Schrödinger equation $$ [- Δ+v(x)]ψ=Eψ,\ x\in \R^2,\ E=E_{fixed}>0 \ \ \ \ \ (*)$$ at a fixed positive energy with a fast decaying at infinity potential $v(x)$ dispersion relations on the scattering data are given.Under &#34;small norm&#34; assumption using these dispersion relations we give (without a complete proof of sufficiency) a

Andrew Strominger

Hawking has proposed non-unitary rules for computing the probabilistic outcome of black hole formation. It is shown that the usual interpretation of these rules violates the superposition principle and energy conservation. Refinements of Hawking&#39;s rules are found which restore both the superposition principle and energy conservation, but leave completely

T. Schaefer, E. V. Shuryak

We study correlation functions and Bethe Salpeter amplitudes for the scalar, the pseudoscalar and the tensor glueballs using an instanton-based model of the QCD vacuum. We consider both the pure gauge case and the situation for real QCD with two light quark flavors. We show that instantons lead to a strong modification of the correlation functions as compare

M. C. Guclu, J. C. Wells, A. S. Umar, M. R. Strayer

In relativistic heavy-ion collisions, the strong Lorentz-contracted electromagnetic fields are capable of producing copious numbers of lepton pairs through the two-photon mechanism. Monte Carlo techniques have been developed that allow the exact calculation of production by this mechanism when a semi-classical approximation is made to the motion of the two i

Kevin Cattell, Michael J. Dinneen, Michael R. Fellows

We described a simple algorithm running in linear time for each fixed constant $k$, that either establishes that the pathwidth of a graph $G$ is greater than $k$, or finds a path-decomposition of $G$ of width at most $O(2^{k})$. This provides a simple proof of the result by Bodlaender that many families of graphs of bounded pathwidth can be recognized in lin

Krzysztof Ciesielski, Arnold W. Miller

A function f from reals to reals (f:R->R) is almost continuous (in the sense of Stallings) iff every open set in the plane which contains the graph of f contains the graph of a continuous function. Natkaniec showed that for any family F of continuum many real functions there exists g:R->R such that f+g is almost continuous for every f in F. Let AA be the sma

Geoffrey Dixon

The octonionic X-product gives the octonions a flexibility not found in the other real division algebras. The pattern of that flexibility is investigated here.

J. Mourad

A construction is proposed for linear connections on non-commutative algebras. The construction relies on a generalisation of the Leibnitz rules of commutative geometry and uses the bimodule structure of $Ω^1$. A special role is played by the extension to the framework of non-commutative geometry of the permutation of two copies of $Ω^1$. The construction of

Michel Dubois-Violette, John Madore, Thierry Masson, Jihad Mourad

A general definition has been proposed recently of a linear connection and a metric in noncommutative geometry. It is shown that to within normalization there is a unique linear connection on the quantum plane and there is no metric.

Luis J. Boya, E. C. G. Sudarshan

We show that the physical requirement of flux conservation can substitute for the usual matching conditions in point interactions. The study covers an arbitrary superposition of $δ$ and $δ&#39;$ potentials on the real line and can be easily applied to higher dimensions. Our procedure can be seen as a physical interpretation of the deficiency index of some sy

Gary McCartor

The mechanism by which the physical vacuum can be different from the perturbative vacuum in the light-cone representation is described and illustrated.

J. Rasmussen, M. Weis

A new topology is proposed on the space of holonomy equivalence classes of loops, induced by the topology of the space $Σ$ in which the loops are embedded. The possible role for the new topology in the context of the work by Ashtekar et al. is discussed.

J. Abad, M. Rios

The Hoft structure of the central extension of the $U_q \left( \widehat{sl\left( n \right) }\right)$ algebra is considered. The intertwine matrix induces new integrable spin chain models. We show the relation of these models and the biparametric spin chain $\widehat{sl_{p,q} \left( n \right)}$ models. The cases $n=2$ are $n=3$ are discussed and for $n=2$ we

Sergei D. Odintsov, August Romeo

We discuss the conformal factor dynamics in $D=6$. Accepting the proposal that higher-derivative dimensionless terms in the anomaly-induced effective action may be dropped, we obtain a superrenormalizable (like in $D=4$) effective theory for the conformal factor. The one-loop analysis of this theory gives the anomalous scaling dimension for the conformal fac

G. Bandelloni, S. Lazzarini

We study the 1-form diffeomorphism cohomologies within a local conformal Lagrangian Field Theory model built on a two dimensional Riemann surface with no boundary. We consider the case of scalar matter fields and the complex structure is parametrized by Beltrami differential. The analysis is first performed at the Classical level, and then we improve the qua

A. Harindranath

The emergence of parton model from field theory in the context of light-front current algebra and naive canonical manipulations is reviewed. Shortcomings of the naive canonical picture, especially concerning renormalization issues are discussed. To illustrate the novel aspects of the renormalization problem in light-front dynamics, the scaling behavior of di

Michael Luke, Martin J. Savage, Mark B. Wise

We compute the $α_s^2 n_f$ perturbative QCD contribution to semileptonic B decay, including the finite mass of the charm quark. This result provides an estimate of the size of the two-loop correction, which is found to be about 50\% of the one-loop correction. We use these results to set the scale for the one-loop correction using the scheme of Brodsky, Lepa

F. Halzen

Doing astronomy with photons of energies in excess of a GeV has turned out to be extremely challenging. Efforts are underway to develop instruments that may push astronomy to wavelengths smaller than $10^{-14}$~cm by mapping the sky in high energy neutrinos instead. Neutrino astronomy, born with the identification of thermonuclear fusion in the sun and the p

Joannis Papavassiliou

The connection between the pinch technique and the background field method is further explored. We show by explicit calculations that the application of the pinch technique in the framework of the background field method gives rise to exactly the same results as in the linear renormalizable gauges. The general method for extending the pinch technique to the

T. K. Gaisser, F. Halzen, T. Stanev

The topic of this review is the particle astrophysics of high energy neutrinos. High energy is defined as $E_ν > 100$~MeV. Main topics include: -- atmospheric neutrinos and muons from $π$, $K$ and charm decay. They probe uncharted territory in neutrino oscillations and constitute both the background and calibration of high energy neutrino telescopes, -- sour

G. M. Shore

Recent work by the author in collaboration with S. Narison and G. Veneziano on the EMC-SMC-SLAC `proton spin&#39; effect is reviewed. This uses a novel approach to deep inelastic scattering in which the matrix elements arising from the OPE are factorised into composite operator propagators and proper vertices. For polarised $μp$ scattering, the composite ope

Mauro Anselmino, M. E. Boglione, F. Murgia

It is shown how the single spin asymmetry observed in inclusive pion production is related, in the helicity basis, to the imaginary part of the product of two different distribution amplitudes, rather than to the usual quark and gluon distribution functions; there is then no reason why it should be zero even in massless perturbative QCD, provided the quark i

S. Pastor, V. Semikoz, Jose W. F. Valle

{Large enough random magnetic fields may affect in an important way neutrino conversion rates, even in the case where neutrinos have zero transition magnetic moments. We consider their effect in the case of active to sterile \neu conversions in a supernova and show that for KeV neutrino masses these limits may overcome those derived for the case of zero magn

José W. F. Valle

Review at session Pa7, Glasgow ICHEP conference

Jose W. F. Valle

Invited review talk at Glasgow ICHEP Conference, session Pa4

S. M. Roy, V. Singh

De Broglie and Bohm formulated a causal quantum mechanics with a phase space density whose integral over momentum reproduces the position probability density of usual statistical quantum theory. We propose a causal quantum theory with a joint probability distribution such that the separate probability distributions for position and momentum agree with usual

L. Anichini, R. Casalbuoni, S. De Curtis

In this paper the low energy limit of the BESS model is studied in a systematic way. The method consists in eliminating the heavy vector field, by use of its classical equations of motion, in the infinite mass limit. After the elimination of the heavy degrees of freedom we get additional terms to the Standard Model lagrangian. After a finite renormalization

R. Peschanski, S. Wallon

We consider a system of evolution equations for quark and gluon structure functions satisfying the leading-logarithmic behaviour due to both QCD collinear $ \left(LLQ^2 \right) $ and infrared $ (LL1/x) $ singularities. We show that these equations leave undetermined an arbitrary regular function of $j$ in the Mellin-transformed weights. We consider the const

A. P. Martin, A. C. Davis

We analyse the evolution of scalar and gauge fields during a second order phase transition using a Langevin equation approach. We show that topological defects formed during the phase transition are stable to thermal fluctuations. Our method allows the field evolution to be followed throughout the phase transition, for both expanding and non-expanding Univer

S. Boettcher

We use a one-dimensional random walk on $D$-dimensional hyper-spheres to determine the critical behavior of statistical systems in hyper-spherical geometries. First, we demonstrate the properties of such walk by studying the phase diagram of a percolation problem. We find a line of second and first order phase transitions separated by a tricritical point. Th

Wolfhard Janke, Stefan Kappler

We use Monte Carlo simulations to measure the spin-spin correlation function in the disordered phase of two-dimensional $q$-state Potts models with $q=10,15$, and $20$ at the first-order transition point $β_t$. To extract the correlation length $ξ_d$ from the exponential decay of the correlation function over several decades with the desired accuracy we make

Karl Jansen

We review the status of the domain wall fermion approach to construct chiral gauge theories on the lattice. In this model an extra, fifth dimension is added and our 4-dimensional world lives on a domainwall induced by a soliton shaped mass defect that depends on the extra dimension only. We demonstrate that the domain wall model gives the correct anomaly str

Lajos Diosi

We showed several years ago that the density operator of Markovian open systems can be diagonalized continuously in time. The resulting pure state jump processes correspond to quantum trajectories proposed in recent quantum optics calculations or, at fundamental level, to exact consistent histories.

Lajos Diosi

A possible mathematical model has been proposed for motion of illuminated quantum particles seen by eyes or similar devices mapping the scattered light.

Piljin Yi

Pair-production of magnetic Reissner-Nordström black holes (of charges $\pm q$) is studied in the next-to-leading WKB approximation. We consider generic quantum fluctuations in the corresponding instanton geometry, a detailed study of which suggests that, for sufficiently weak field $B$, the problem can be reduced to that of quantum fluctuations around a sin

Elliott Lieb, Bruno Nachtergaele

We investigate the conventional tight-binding model of $L$ $π$-electrons on a ring-shaped mol\-e\-cule of $L$ atoms with nearest neighbor hopping. The hopping amplitudes, $t(w)$, depend on the atomic spacings, $w$, with an associated distortion energy $V(w)$. A Hubbard type on-site interaction as well as nearest-neighbor repulsive potentials can also be incl

Manfred Sigrist, Yong Baek Kim

A new experiment is proposed to probe the time-reversal symmetry of a superconductor. It is shown that a time-reversal symmetry breaking superconductor can be identified by the observation of a fractional flux in connection with a Josephson junction in a special geometry.

F. Dominguez-Adame

We calculate interface states in semiconductor heterostructures with band inversion using a Green function approach and the so called {\em point interaction potentials}. Effects of external fields can be included in a straightforward fashion.

G. S. Uhrig, R. Vlaming

We focus on the ground state phase diagram of a system of spinless fermions with repulsion on a hypercubic lattice in the limit of infinite dimensions. It occurs spontaneous symmetry breaking into a charge density wave (CDW). Using an ansatz for the order parameter which includes the homogeneous, the AB- and a large class of incommensurate phases we are able

Mats Wallin, Hans Weber

We study the linear resistance at the Kosterlitz-Thouless transition by Monte Carlo simulation of vortex dynamics. Finite size scaling analysis of our data show excellent agreement with scaling properties of the Kosterlitz-Thouless transition. We also compare our results for the linear resistance with experiments. By adjusting the vortex chemical potential t

E. Alfinito, M. Leo, R. A. Leo, G. Soliani

We carry out a group-theoretical study of the pair of nonlinear Schrödinger equations describing the propagation of waves in nonlinear birefringent optical fibers. We exploit the symmetry algebra associated with these equations to provide examples of specific exact solutions. Among them, we obtain the soliton profile, which is related to the coordinate trans

Enrique Diez, Francisco Dominguez-Adame, Angel Sánchez

We study resonant tunnelling through double-barrier structures under an applied bias voltage, in which nonlinearities due to self-interaction of electrons in the barrier regions are included. As an approximation, we concern ourselves with thin barriers simulated by $δ$-function potentials. This approximation allows for an analytical expression of the transmi

Koo-Chul Lee

We present a generalized circle theorem which includes the Lee-Yang theorem for symmetric transitions as a special case. It is found that zeros of the partition function can be written in terms of discontinuities in the derivatives of the free energy. For asymmetric transitions, the locus of the zeros is tangent to the unit circle at the positive real axis i

B. A. Hockey, B. Srinivas

Using feature-based Tree Adjoining Grammar (TAG), this paper presents linguistically motivated analyses of constructions claimed to require multi-component adjunction. These feature-based TAG analyses permit parsing of these constructions using an existing unification-based Earley-style TAG parser, thus obviating the need for a multi-component TAG parser wit

Aravind K. Joshi, B. Srinivas

In a lexicalized grammar formalism such as Lexicalized Tree-Adjoining Grammar (LTAG), each lexical item is associated with at least one elementary structure (supertag) that localizes syntactic and semantic dependencies. Thus a parser for a lexicalized grammar must search a large set of supertags to choose the right ones to combine for the parse of the senten

Scott Dodelson, Arthur Kosowsky

Anisotropies in the temperature of the cosmic microwave background have been detected on a range of scales by several different experiments. These anisotropies reflect the primordial spectrum of metric perturbations in the early universe. In principle, the largest barrier to a clean interpretation of the experimental results is contamination by foreground so

Heath Martin, Juan Migliore

In its most basic form, Dubreil&#39;s Theorem states that for an ideal $I$ defining a codimension $2$, arithmetically Cohen--Macaulay subscheme of projective $n$-space, the number of generators of $I$ is bounded above by the minimal degree of a minimal generator plus $1$. By introducing a new ideal $J$ which is the complete intersection of $n-1$ general line

Severinas Zube

The main purpose in this paper is to study exceptional vector bundles on Enriques surfaces.

Deshpande, He, Oh

We study amplitude zeros in radiative decay processes with a photon or a gluon emission of all possible scalar particles(e.g. scalar leptoquarks) which may interact with the usual fermions in models beyond the standard model. For the decays with a photon emission, the amplitudes clearly exhibit the factorization property and the differential decay rates vani

Jonathan Beck, Victor G. Kac

We describe explicitly the canonical map $χ:$ Spec $\ue(\a{g})\ \rightarrow \ $Spec $\ze$, where $\ue(\a{g})$ is a quantum loop algebra at an odd root of unity $\ve$. Here $\ze$ is the center of $\ue(\a{g})$ and Spec $R$ stands for the set of all finite--dimensional irreducible representations of an algebra $R$. We show that Spec $\ze$ is a Poisson proalgebr

O. F. Dayi, I. H. Duru

The realizations of the Lie algebra corresponding to the dynamical symmetry group SO(2,1) of the Kepler and oscillator potentials are q-deformed. The q-canonical transformation connecting two realizations is given and a general definition for q-canonical transformation is deduced. q-Schrödinger equation for a Kepler like potential is obtained from the q-osci

E. Farhi, J. Goldstone, S. Gutmann, K. Rajagopal

We investigate fermion production in the background of Minkowski space solutions to the equations of motion of $SU(2)$ gauge theory spontaneously broken via the Higgs mechanism. First, we attempt to evaluate the topological charge $Q$ of the solutions. We find that for solutions $Q$ is not well-defined as an integral over all space-time. Solutions can profit

Omri Gat, Itamar Procaccia, Reuven Zeitak

We present an analytic and numerical analysis of the Gledzer-Ohkitani-Yamada (GOY) cascade model for turbulence. We concentrate on the dynamic correlations, and demonstrate both numerically and analytically, using resummed perturbation theory, that the correlations do not follow a dynamic scaling ansatz. The basic reason for this is the existence of a second

D. Buchholz, C. D&#39;Antoni

Within the setting of algebraic quantum field theory a relation between phase-space properties of observables and charged fields is established. These properties are expressed in terms of compactness and nuclearity conditions which are the basis for the characterization of theories with physically reasonable causal and thermal features. Relevant concepts and

R. D. Amado, F. Cannata, J-P. Dedonder, M. P. Locher

We study the effect of isospin projections on a two source picture of coherent pions coming from nucleon-antinucleon annihilation. We show that important Hanbury-Brown Twiss correlations among like charge pion pairs compared with unlike arise from these isospin projections.

P. Magierski, K. Burzynski, J. Dobaczewski, W. Nazarewicz

The origin of the Delta I=4 staggering effect which has recently been observed in several superdeformed bands is discussed. The Hamamoto and Mottelson model, which is based on a phenomenological parametrization of the hamiltonian as a quartic function of angular momentum, is analyzed. A stability of the description with respect to the C_4 - symmetry breaking

Dmitry Fuchs, Albert Schwarz

We consider generalizations of the Vieta formula (relating the coefficients of an algebraic equation to the roots) to the case of equations whose coefficients are order-$k$ matrices. Specifically, we prove that if $X_1,\dots ,X_n$ are solutions of an algebraic matrix equation $X^n+A_1X^{n-1}+\dots +A_n=0,$ independent in the sense that they determine the coe

R. Amorim, J. Barcelos-Neto

We study an extension of the axial model where local gauge symmetries are taken into account. The anomaly of the axial current is calculated by the Fujikawa formalism and the model is also solved. Besides the well known features of the particular models (axial and Schwinger) it was obtained an effective interaction of scalar and gauge fields via a topologica

Ivan Cherednik

Recently a new technique in the harmonic analysis on symmetric spaces was suggested based on certain remarkable representations of affine and double affine Hecke algebras in terms of Dunkl and Demazure operators instead of Lie groups and Lie algebras. In the classic case it resulted (among other applications) in a new theory of radial part of Laplace operato

Katsuyuki Sugiyama

We study a two parameter family of Calabi-Yau d-fold by means of mirror symmetry. We construct mirror maps and calculate correlation functions associated with {\kae} moduli in the original manifold. We find there are more complicated instanton corrections of these couplings than threefolds, which is expected to reflect families of instantons with continous p