April 1996 arXiv papers — page 7

P. F. Mastinu, M. Belkacem, D. R. Bowman, M. Bruno

Multifragment events resulting from peripheral Au + Au collisions at 35 MeV/nucleon are analysed in terms of critical behavior. The analysis of most of criticality signals proposed so far (conditional moments of charge distributions, Campi scatter plot, fluctuations of the size of the largest fragment, intermittency analysis) is consistent with the occurrenc

Juan M. Aguirregabiria

It is shown that the scattering of a charged test particle by a system of four extreme Reissner-Nordtröm black holes is chaotic in some cases. The fractal structure of the scattering angle and time delay functions is another manifestation of the existence of a nonattracting chaotic set: fractal basin boundaries were previously known.

Matthias Otto, Thomas A. Vilgis

The statistical mechanics of polymer loops entangled in the two-dimensional array of randomly distributed obstacles of infinite length is discussed. The area of the loop projected to the plane perpendicular to the obstacles is used as a collective variable in order to re-express a (mean field) effective theory for the polymer conformation. It is explicitly s

Priyamvada Natarajan, Donald Lynden-Bell

We present a useful analytic approximation to the solution of the Lane-Emden equation for infinite polytropic index - the isothermal sphere. The optimized expression obtained for the density profile can be accurate to within 0.04% within 5 core-radii and to 0.1% within 10 core-radii.

A. V. Belitsky

We calculate the leading twist valence quark distribution in the pion in the framework of QCD sum rules with nonlocal condensates. Particular attention has been paid to the correct account for the bilocal power corrections.

E. Alfinito, G. Soliani, L. Solombrino

We show that excitations of physical interest of the heavenly equation are generated by symmetry operators which yields two reduced equations with different characteristics. One equation is of the Liouville type and gives rise to gravitational instantons, including those found by Eguchi-Hanson and Gibbons-Hawking. The second equation appears for the first ti

G. F. Filippov, A. D. Bazavov, K. Kato, S. V. Korennov

In the harmonic oscillator representation, the Schrodinger equation has a form of a set of infinite number of algebraical equations which are labeled by the radial quantum number "n". It is shown that at n>>1 these equations are significantly simplified and become an algebraical analogue of the original differential Schrodinger equation. This result

Elena Accomando, Alessandro Ballestrero, Giampiero Passarino

The programs WPHACT and WTO, which are designed for computing cross sections and other relevant observables in the $e^+e^-$ annihilation into four fermions, are used to make detailed and complete predictions for the semi-leptonic and fully hadronic channels $e^+e^- \to \barq q lν, \barq q \barq q$. Both the total cross sections in the LEP~2 energy range and

Hirofumi Yamada

Unconventional way of handling the perturbative series is presented with the help of Heaviside transformation with respect to the mass. We apply Heaviside transform to the effective potential in the massive Gross-Neveu model and carry out perturbative approximation of the massless potential by dealing with the resulting Heaviside function. We find that accur

Hsien-chung Kao, Shih-Chang Lee, Wen-Jer Tzeng

We solved the Frenkel-Kontorova model with the potential $V(u)= -\frac{1}{2} |λ|(u-{\rm Int}[u]-\frac{1}{2})^2$ exactly. For given $|λ|$, there exists a positive integer $q_c$ such that for almost all values of the tensile force $σ$, the winding number $ω$ of the ground state configuration is a rational number in the $q_c$-th level Farey tree. For fixed $ω=p

P. Busch

We explore the sense in which the state of a physical system may or may not be regarded (an) observable in quantum mechanics. Simple and general arguments from various lines of approach are reviewed which demonstrate the following no-go claims: (1) the structure of quantum mechanics precludes the determination of the state of a single system by means of meas

Z. Aouissat, G. Chanfray, P. Schuck, J. Wambach

Using a non-perturbative method based on the selfconsistent Quasi-particle Random-Phase Approximation (QRPA) we describe the properties of the pion in the linear $σ$-model. It is found that the pion is massless in the chiral limit, both at zero- and finite temperature, in accordance with Goldstone's theorem.

Y. Suzuki, K. Arai, Y. Ogawa, K. Varga

We present a new and simple method of calculating the occupation probability of the number of total harmonic-oscillator quanta for a microscopic cluster-model wave function. Examples of applications are given to the recent calculations including $α+n+n$-model for $^6$He, $α+t+n+n$-model for $^9$Li, and $α+α+n$-model for $^9$Be as well as the classical calcul

Teiji Kunihiro

It should be a typical subject in this workshop to explore possible change of hadron properties in association with that of QCD vacuum due to an environmental change. In this report, we first summarize what hadrons are expected to show such a change and how they do. Then we propose several experiments including the ones utilizing electron and photon beams fo

Stefano Trapani

Let $S$ be a generic submanifold of $C^N$ of real codimension m. In this work we continue the study, carried over by various authors, of the set of analytic discs attached to S. Let $M$ be the set of analytic discs attached to $S.$ Given $q \in S$ let $M_q$ be the set of discs $ϕ$ in M such that $ϕ_(1).$ B. Trepreau and other authors gave sufficient conditio

L. Sriramkumar, T. Padmanabhan

In this paper, we probe the validity of the tunnelling interpretation that is usually called forth in literature to explain the phenomenon of particle production by time independent classical electromagnetic backgrounds. We show that the imaginary part of the effective lagrangian is zero for a complex scalar field quantized in a time independent, but otherwi

Michael B. Green, Michael Gutperle

$D$-brane boundary states for type II superstrings are constructed by enforcing the conditions that preserve half of the space-time supersymmetry. A light-cone coordinate frame is used where time is identified as one of the coordinates transverse to the brane's (euclidean) world-volume so that the $p$-brane is treated as a $(p+1)$-instanton. The boundary

Mirjam Cvetic, Harald H. Soleng

We review the status of domain walls in $N=1$ supergravity theories for both the vacuum domain walls as well as dilatonic domain walls. We concentrate on a systematic analysis of the nature of the space-time in such domain wall backgrounds and the special role that supersymmetry is playing in determining the nature of such configurations.

V. Ya. Fainberg, N. K. Pak, M. S. Shikakhwa

The cvariant path integral quantization of the theory of the scalar and spinor particles interacting through the abelian and non-Abelian Chern-Simons gauge fields is carried out and is shown to be mathematically ill defined due to the absence of the transverse components of these gauge fields. This is remedied by the introduction of the Maxwell or the Maxwel

R. Brustein, M. Gasperini, G. Veneziano

Using general arguments we determine the allowed region for the end point frequency and the peak energy density of the stochastic background of gravity waves expected in string cosmology. We provide an accurate estimate of the minimal experimental sensitivity required to detect a signal in the Hz to GHz range.

Ayse Humeyra Bilge

We show that the two sets of self-dual Yang-Mills equations in 8-dimensions proposed in (E.Corrigan, C.Devchand, D.B.Fairlie and J.Nuyts, {\it Nuclear Physics} {\bf B214}, 452-464, (1983)) form respectively elliptic and overdetermined elliptic systems under the Coulomb gauge condition. In the overdetermined case, the Yang-Mills fields can depend at most on $

Kazuhiko Odaka, Kazuya Satoh

By using the spherical coordinates in 3+1 dimensions we study the self-adjointness of the Dirac Hamiltonian in an Aharonov-Bohm gauge field of an infinitely thin magnetic flux tube. It is shown that the angular part of the Dirac Hamiltonian requires self-adjoint extensions as well as its radial one. The self-adjoint extensions of the angular part are paramet

Ken Kiers, John N. Ng, Guohong Wu

High energy electron-photon colliders provide unique opportunities for probing physics beyond the standard model. We have studied the experimental signatures for two supersymmetric scenarios, with the lightest supersymmetric particle (LSP) being either the lightest neutralino or the gravitino. In the ``neutralino LSP'' scenario favored by the minimal

C. S. Lam, K. F. Liu

In the presence of a large parameter, such as mass or energy, leading behavior of individual Feynman diagrams often get cancelled in the sum. This is known to happen in large-$N_c$ QCD in the presence of a baryon, and also in the case of high-energy electron-electron as well as quark-quark scatterings. We present an exact combinatorial formula, involving mul

N. G. Deshpande, Xiao-Gang He, Sechul Oh

We present a method to measure the CKM phase $α$ and the tree and penguin (strong and electroweak) amplitudes in $B \rightarrow ππ$ decays, based on isospin consideration and the weak assumption that all tree amplitudes have a common strong phase and all penguin amplitudes have a different common phase. The method needs only the time-independent measurements

V. Barger, M. S. Berger, J. F. Gunion, T. Han

We discuss the capabilities of future muon colliders to resolve important particle physics questions. A collider with c.m. energy $\sqrt s = 100$ to 500~GeV offers the unique opportunity to produce Higgs bosons in the $s$-channel and thereby measure the Higgs masses, total widths and several partial widths to high precision. At this same machine, $t\bar t$ a

Adrian Ghinculov

I describe a method to calculate a class of three-loop selfenergy diagrams for arbitrary internal masses and external momentum. This method combines analytical results and numerical integration, and is suitable for implementation in a computer program to produce fast and accurate results. For the class of Feynman diagrams considered in this paper this method

S. Bethke, M. L. Mangano, P. Nason

We discuss some topics in QCD studies at 2 TeV. Particular emphasis is given to the separation of pure QCD events from the WW and the t-tbar backgrounds

P. Taxil, J. M. Virey

We show that the measurement of some parity violating asymmetry in the production of a large ET jet could reveal the presence of a new hadrophilic Z' such as the one recently introduced to interpret possible departures from the Standard Model predictions both at LEP and at CDF. Such a measurement could be perform within a few years by the RHIC Spin Colla

Stefan Herrlich, Ulrich Nierste

We present the complete next-to-leading order short-distance QCD corrections to the effective \dstwo -hamiltonian in the Standard Model. The calculation of the coefficient $\eta_3$ is described in great detail. It involves the two-loop mixing of bilocal structures composed of two \dsone\ operators into \dstwo\ operators. The next-to-leading order corrections

R. Harlander, M. Jezabek, J. H. Kuehn, M. Peter

Top quark polarization in $e^+e^-$ annihilation into $t\bar t$ is calculated for linearly polarized beams. The Green function formalism is applied to this reaction near threshold. The Lippmann--Schwinger equations for the $S$-wave and $P$-wave Green functions are solved numerically for the QCD chromostatic potential given by the two-loop formula for large mo

R. Baier, Yu. L. Dokshitzer, A. H. Mueller, S. Peigne

The calculation of the radiative energy loss encountered by a fast charged particle which undergoes multiple scattering is being investigated. A detailed derivation of the Landau-Pomeranchuk-Migdal coherent effect in QED is given, focusing on the specific feature of the Coulomb interaction. As a result the radiation intensity per unit length in the coherent

E. Ben-Naim, S. Redner, P. L. Krapivsky

The kinetics of single-species annihilation, $A+A\to 0$, is investigated in which each particle has a fixed velocity which may be either $\pm v$ with equal probability, and a finite diffusivity. In one dimension, the interplay between convection and diffusion leads to a decay of the density which is proportional to $t^{-3/4}$. At long times, the reactants or

G. Gomila, A. Perez-Madrid, J. M. Rubi

The methods of non-equilibrium thermodynamics of systems with an interface have been applied to the study of thermionic emission processes in abrupt semiconductor junctions, including the effects of surface states . Our analysis covers different situations of interest, concerning unipolar and bipolar systems, either degenerate or not, with or without interfa

W. Atkinson, J. P. Carbotte, C. O'Donovan

The zero temperature in plane penetration depth in an untwinned single crystal of optimally doped YBa_2Cu_3O_6.93 is highly anisotropic. This fact has been interpreted as evidence that a large amount of the condensate resides in the chains. On the other hand, the temperature dependence of lambda_a(T)/lambda_a(0) and lambda_b(T)/lambda_b(0) (where the b-direc

Steven H. Simon, Ady Stern, Bertrand I. Halperin

For quantum Hall systems, in the limit of large magnetic field (or equivalently small electron band mass $m_b$), the static response of electrons to a spatially varying magnetic field is largely determined by kinetic energy considerations. This response is not correctly given in existing approximations based on the Fermion Chern-Simons theory of the partiall

Simona Cocco, Remi Monasson, Riccardo Zecchina

We study the weight space structure of the parity machine with binary weights by deriving the distribution of volumes associated to the internal representations of the learning examples. The learning behaviour and the symmetry breaking transition are analyzed and the results are found to be in very good agreement with extended numerical simulations.

E. Hofstetter

The critical behaviour of 3-dimensional disordered systems in a strong magnetic field is investigated by analysing the spectral fluctuations of the energy spectrum. The level spacing distribution $P(s)$ as well the Dyson-Mehta statistics $Δ_{3}(L)$ are considered. Except for the small $s$ behaviour of $P(s)$, which depends on the presence or absence of a mag

P. I. Tamborenea, R. J. Radtke, S. Das Sarma

We study the magnetic phases of two coupled two-dimensional electron gases in order to determine under what circumstances these phases may occur in real semiconductor quantum wells and what the experimental properties of the broken-symmetry ground states may be. Within the local-density-approximation to time-dependent density functional theory (DFT), we find

M. Watzlawek, G. Naegele

We investigate the combined effects of electrostatic interactions and hydrodynamic interactions on the short-time rotational self-diffusion coefficient in charge-stabilized suspensions. We calculate this coefficient as a function of volume fraction for various effective particle charges and amounts of added electrolyte. The influence of the hydrodynamic inte

T. Ala-Nissila, S. Herminghaus, T. Hjelt, P. Leiderer

We study the diffusion and submonolayer spreading of chainlike molecules on surfaces. Using the fluctuating bond model we extract the collective and tracer diffusion coefficients D_c and D_t with a variety of methods. We show that D_c(theta) has unusual behavior as a function of the coverage theta. It first increases but after a maximum goes to zero as theta

H. Perez Rojas

Arbitrarily large ground state population is a general property of any ideal bose gas when conditions of degeneracy are satisfied; it occurs at any dimension D. For $D = 1$, the condensation is diffuse, at $D = 2$ it is a sort of quasi-condensate. The discussion is made by following a microscopic approach and for finite systems. Some astrophysical consequenc

U. Nowak, J. Esser, K. D. Usadel

We investigate the dynamics of two-dimensional site-diluted Ising antiferromagnets. In an external magnetic field these highly disordered magnetic systems have a domain structure which consists of fractal domains with sizes on a broad range of length scales. We focus on the dynamics of these systems during the relaxation from a long-range ordered initial sta

J. Schmalian, M. Langer, S. Grabowski, K. H. Bennemann

Using the fluctuation exchange approximation of the one band Hubbard model, we discuss the origin of the changing Fermi surface volume in underdoped cuprate systems due to the transfer of occupied states from the Fermi surface to its shadow, resulting from the strong dynamical antiferromagnetic short range correlations. The momentum and temperature dependenc

Z. Hens, X. de Hemptinne

The thermodynamic approach to non-equilibrium dynamics describes the state of macroscopic systems by means of a collection of intensities or intensive variables. The latter are by definition the differentials of the entropy with respect to the set of extensive constraints. The environment is directly involved in controlling the intensities. The isolation par

Pilar Ruiz-Lapuente

The subject of late-time emission of Type Ia supernovae and its implications for the understanding of the explosions of C+O WDs is reviewed.

Karl Gebhardt, Douglas Richstone, Edward Ajhar, Tod Lauer

We have non-parametrically determined the luminosity density profiles and their logarithmic slopes for 42 early-type galaxies observed with HST. Assuming that the isodensity contours are spheroidal, then the luminosity density is uniquely determined from the surface brightness data through the Abel equation. For nearly all the galaxies in our sample, the log

S. Michael Fall, Stephane Charlot, Yichuan C. Pei

We present a new method to compute the cosmic emissivity $\E_ν$ and background intensity $J_ν$. Our method is based entirely on data from quasar absorption-line studies, namely, the comoving density of HI and the mean metallicity and dust-to-gas ratio in damped Ly$α$ galaxies. These observations, when combined with models of cosmic chemical evolution, are su

Ulrich Lindner, Uta Fritze - von Alvensleben, Klaus J. Fricke

A comprehensive set of all available magnitudes, colors and redshifts for optically identified QSO absorbers is compiled from the literature. This results in a largely unbiased sample of galaxies at high redshifts, the size of the sample being reasonably large to allow for a first comparison with galaxy evolution models. We use our evolutionary spectral synt

D. Q. Lamb, M. Coleman Miller, R. E. Taam

We argue that the bursting, transient X-ray source GRO J1744-28 is a binary consisting of a very low-mass ($M \approx 0.2 M_\sun$), highly evolved giant star that is transferring mass by Roche lobe overflow onto a high-mass ($M \approx 1.8 M_\sun$) neutron star. We explore a picture in which the bursts are due to thermonuclear flashes in matter that has accr

W. Steffen, A. J. Holloway, A. Pedlar

We examine models in which jets are responsible for the formation of the emission-line spiral structure in IRAS 04210+0400. The kiloparsec-scale radio lobes in this active galaxy appear to be related to its extended emission-line spiral structure. The radio structure consists mainly of extended symmetrically bent, FR\,I-type lobes, which follow the emission-

L. Pozzetti, G. Bruzual A., G. Zamorani

We have examined a set of pure luminosity evolution (PLE) models in order to explore up to what extent the rapidly increasing observational constraints from faint galaxy samples can be understood in this simple framework. We find that a PLE model, in which galaxies evolve mildly in time even in the rest frame UV, can reproduce most of the observed properties

M. Szymanski, A. Udalski, M. Kubiak, J. Kaluzny

This paper presents the first part of the Optical Gravitational Lensing Experiment (OGLE) General Catalog of Stars in the Galactic bulge. The Catalog is based on observations collected during the OGLE microlensing search. This part contains 33196 stars brighter than I=18mag identified in the Baade's Window BWC field. Stars from remaining 20 OGLE fields w

R. Bandiera, F. Pacini, M. Salvati

The plerion inside the composite Supernova Remnant G11.2-0.3 appears to be dominated by the magnetic field to an extent unprecedented among well known cases. We discuss its evolution as determined by a central pulsar and the interaction with the surrounding thermal remnant, which in turn interacts with the ambient medium. We find that a plausible scenario ex

N. Aghanim, F. X. Desert, J. L. Puget, R. Gispert

We discuss the photoionization of the intergalactic medium by early formed quasars and propose a mechanism which could generate measurable temperature fluctuations $δ_{T }~=~ΔT/T$ of the cosmic microwave background (CMB). Early quasars produce individual ionized regions around themselves. We evaluate both thermal and kinetic (first-order Doppler) Sunyaev-Zel

D. R. Alves, D. W. Hoard

We have obtained near-infrared imaging and an optical spectrum of the proto-planetary nebula IRAS~07131-0147, a highly polarized bipolar reflection nebula believed to be in evolutionary transition from the asymptotic giant branch to the planetary nebula phase. Our images reveal point reflection symmetry in the lobes - a relatively rare morphological feature.

M. P. Grabowski, P. Mathieu

We study the local conserved charges in integrable spin chains of the XYZ type with nontrivial boundary conditions. The general structure of these charges consists of a bulk part, whose density is identical to that of a periodic chain, and a boundary part. In contrast with the periodic case, only charges corresponding to interactions of even number of spins

I. Krichever, O. Lipan, P. Wiegmann, A. Zabrodin

Functional relation for commuting quantum transfer matrices of quantum integrable models is identified with classical Hirota's bilinear difference equation. This equation is equivalent to the completely discretized classical 2D Toda lattice with open boundaries. The standard objects of quantum integrable models are identified with elements of classical nonli

Xuemin Jin, B. K. Jennings

The quark-meson coupling model for nuclear matter, which describes nuclear matter as non-overlapping MIT bags bound by the self-consistent exchange of scalar and vector mesons, is modified by introducing medium modification of the bag constant. We model the density dependence of the bag constant in two different ways: one invokes a direct coupling of the bag

Stefan Jordan, Werner Schmutz, Burkhard Wolff, Klaus Werner

We present a consistent model for the UV and supersoft X-ray emission from the symbiotic nova SMC3 (=RX J0048.4-7332). Following the present picture of symbiotic stars, the model consists of radiation from a hot star and an emission nebula excited by that star. The observations were compared to theoretical models in which the hot star's emission is calculate

A. P. Balachandran, G. Bimonte, G. Landi, F. Lizzi

Conventional approaches to lattice gauge theories do not properly consider the topology of spacetime or of its fields. In this paper, we develop a formulation which tries to remedy this defect. It starts from a cubical decomposition of the supporting manifold (compactified spacetime or spatial slice) interpreting it as a finite topological approximation in t

Christian von Ferber

We prove to all orders of renormalized perturbative polymer field theory the existence of a short chain expansion applying to polymer solutions of long and short chains. For a general polymer network with long and short chains we show factorization of its partition sum by a short chain factor and a long chain factor in the short chain limit. This corresponds

Jonathan L. Rosner

(1) A simple transversity analysis permits one to separate the P-even and P-odd partial waves in such decays as $B_s \to J/ψϕ$ and $B \to J/ψK^*$. This method is relevant to the separation of contributions of CP-even and CP-odd final states in $B_s$ decays, and hence to the measurement of a possible lifetime difference between mass eigenstates. (2) The enhan

Mario Atance, Jose Luis Cortes

The general structure of the renormalization group equations for the low energy effective field theory formulation of pure gravity is presented. The solution of these equations takes a particular simple form if the mass scale of the effective theory is much smaller than the Planck mass (a possibility compatible with the renormalization of the effective theor

A. V. Radyushkin

I outline a perturbative QCD approach to the analysis of the deeply virtual Compton scattering process $γ^* p \to γp'$ in the limit of vanishing momentum transfer $t= (p' - p)^2$. The DVCS amplitude in this limit exhibits a scaling behaviour described by a two-argument distributions $F(x,y)$ which specify the fractions of the initial momentum $p$ and

P. Busch, A. Shimony

The quantum mechanical measurement problem is the difficulty of dealing with the indefiniteness of the pointer observable at the conclusion of a measurement process governed by unitary quantum dynamics. There has been hope to solve this problem by eliminating idealizations from the characterization of measurement. We state and prove two `insolubility theorem

M. Penttinen

The generalization of the conformal scattering method for small-angle scattering processes involving magnetic monopoles and ordinary charges is constructed. Using this generalization we show that introducing of magnetic charges corresponds to analytical continuation of the eikonal amplitude in the complex charge plane (the imaginary part is proportional to t

Xiao-Biao Lin

We discuss a diffusively perturbed predator-prey system. Freedman and Wolkowicz showed that the corresponding ODE can have a periodic solution that bifurcates from a homoclinic loop. When the diffusion coefficients are large, this solution represents a stable, spatially homogeneous time-periodic solution of the PDE. We show that when the diffusion coefficien

W. Florkowski, B. Friman

The spatial dependence of static meson correlation functions at finite baryon density is studied in the Nambu -- Jona - Lasinio model. In contrast to the finite temperature case, we find that the correlation functions at finite density are not screened but exhibit long-range oscillations. The observed phenomenon is analogous to the Friedel oscillations in a

Eric Rosen, Saharon Shelah, Scott Weinstein

This paper investigates the class of k-universal finite graphs, a local analog of the class of universal graphs, which arises naturally in the study of finite variable logics. The main results of the paper, which are due to Shelah, establish that the class of k-universal graphs is not definable by an infinite disjunction of first-order existential sentences

Saharon Shelah

We continue [Sh:b, Ch XIII] and [Sh:410]. Let W be an inner model of ZFC. Let kappa be a cardinal in V. We say that kappa-covering holds between V and W iff for all X in V with X subseteq ON and V models |X|< kappa, there exists Y in W such that X subseteq Y subseteq ON and V models |Y|< kappa. Strong kappa-covering holds between V and W iff for every struct

Kecheng Liu, Saharon Shelah

Let 0<n^*< omega and f:X-> n^*+1 be a function where X subseteq omega backslash (n^*+1) is infinite. Consider the following set S_f= {x subset aleph_omega : |x| <= aleph_{n^*} & (for all n in X)cf(x cap alpha_n)= aleph_{f(n)}}. The question, first posed by Baumgartner, is whether S_f is stationary in [alpha_omega]^{< aleph_{n^*+1}}. By a standard result, the

Saharon Shelah

We continue the work of [KlSh:362] and prove that for lambda successor, a lambda-categorical theory T in L_{kappa^*, omega} is mu-categorical for every mu, mu <= lambda which is above the (2^{LS(T)})^+-beth cardinal.

Marco Martens

It will be shown that the renormalization operator, acting on the space of smooth unimodal maps with critical exponent greater than 1, has periodic points of any combinatorial type.

Chi-Kwong Li, Beata Randrianantoanina

Let $X_0, X_1, ..., X_k$ with $k \in \IN\cup\{\infty\}$ be sequence spaces $($finite or infinite dimensional$)$ over $\IC$ or $\IR$ with absolute norms $N_i$ for $i = 0, ..., k$, $($i.e., with 1-unconditional bases$)$ such that $\dim X_0 = k$. Define an absolute norm on the cross product space $($also known as the $X_0$ 1-unconditional sum$)$ $X_1 \times ...

Edward Odell, Thomas Schlumprecht

A reflexive Banach space $X$ with a basis $(e_i)$ is constructed having the property that every monotone basis is block finitely representable in each block basis of $X$.

A. Gorsky, A. Marshakov, A. Mironov, A. Morozov

We discuss the construction of the spectral curve and the action integrals for the ``elliptic&#34; $XYZ$ spin chain of the length $N_c$. Our analysis can reflect the integrable structure behind the ``elliptic&#34; ${\cal N}=2$ supersymmetric QCD with $N_f=2N_c$.

I. Antoniadis, E. Gava, K. S. Narain, T. R. Taylor

We show that certain heterotic string amplitudes are given in terms of correlators of the twisted topological (2,0) SCFT, corresponding to the internal sector of the N=1 spacetime supersymmetric background. The genus g topological partition function $F^g$ corresponds to a term in the effective action of the form $W^{2g}$, where W is the gauge or gravitationa

Dirk Schlingemann

Several two-dimensional quantum field theory models have more than one vacuum state. Familiar examples are the Sine-Gordon and the $ϕ^4_2$-model. It is known that these models possess states, called kink states, which interpolate different vacua. A general construction scheme for kink states in the framework of algebraic quantum field theory is developed in

A. A. Deriglazov, A. V. Galajinsky

For a rather broad class of dynamical systems subject to mixed fermionic first and second class constraints or infinitely reducible first class constraints (IR1C), a manifestly covariant scheme of supplementation of IR1C to irreducible ones is proposed. For a model with IR1C only, an application of the scheme leads to a system with covariantly splitted and i

Ryuichi Nakayama, Toshiya Suzuki

New loop equations for all genera in $c = \frac{1}{2}$ non-critical string theory are constructed. Our loop equations include two types of loops, loops with all Ising spins up (+ loops) and those with all spins down ( $-$ loops). The loop equations generate an algebra which is a certain extension of $W_3$ algebra and are equivalent to the $W_3$ constraints d

C. Weiss

We discuss the evaluation of the nucleon isoscalar axial coupling, $g_A^{(0)}$, in the instanton vacuum, using the $1/N_c$ expansion. This approach allows a fully consistent treatment of the $U(1)_A$ anomaly. We compute the nucleon matrix element of the topological charge density, $\langle N | F\widetilde{F} | N \rangle$, and show that it reduces to the matr

U. Ornik, M. Plümer, B. R. Schlei, D. Strottman

We present a coherent theoretical study of ultrarelativistic heavy-ion data obtained at the CERN/SPS by the NA35/NA49 Collaborations using 3+1-dimensional relativistic hydrodynamics. We find excellent agreement with the rapidity spectra of negative hadrons and protons and with the correlation measurements in two experiments: $S+S$ at 200 $AGeV$ and $Pb+Pb$ a

D. Ebert, T. Feldmann

Starting from the approximate symmetries of QCD, namely chiral symmetry for light quarks and spin and flavor symmetry for heavy quarks, we investigate the low-energy properties of heavy hadrons. For this purpose we construct a consistent picture of quark-antiquark and quark-diquark interactions as a low-energy approximation to the flavor dynamics in heavy me

A. Leike, S. Riemann

Constraints on extra neutral gauge bosons are obtained from $e^+e^-\rightarrow f\bar f$ at NLC energies. Model independent limits on the $Z&#39;f\bar f$ couplings and lower limits on the $Z&#39;$ mass are discussed. Typical GUTs with $M_{Z&#39;}$ up to (3 -- 6) $\sqrt{s}$ can be excluded. A distinction between different GUT scenarios is possible if $M_{Z&#39

J. R. Espinosa

We show that two-loop corrections to the finite temperature effective potential in the MSSM can have a dramatic effect on the strength of the electroweak phase transition, making it more strongly first order. The change in the order parameter $v/T_c$ can be as large as 75\% of the one-loop daisy improved result. This effect can be decisive to widen the regio

Yuri Kubyshin, Jerome Martin

Contributions of primordial gravitational waves to the large-angular-scale anisotropies of the cosmic microwave background radiation in multidimensional cosmological models (Kaluza-Klein models) are studied. We derive limits on free parameters of the models using results of the COBE experiment and other astrophysical data. It is shown that in principle there

Michael R. Geller

I derive new sum rules for the electronic oscillator strengths in a periodic or nearly periodic potential, which apply within a single energy band and between any two bands. The physical origin of these sum rules is quite unlike that of conventional sum rules, and is shown to be associated with a solid-state counterpart to the principle of spectroscopic stab

Valery L. Pokrovsky

This is a Review of experimental observations and theoretical developments on the c-axis plasma oscillations in High-temperature superconductors.

A. Gramada, M. E. Raikh

We study the tunneling into the edge of the Luttinger liquid with periodically modulated concentration of electrons. It is shown that the modulation,by causing a gap in the spectrum of plasmons, leads to an additional anomaly in the density of states at frequency corresponding to the center of the gap. The shape of the anomaly depends strongly on the {\em ph

M K Hassan, G J Rodgers

We consider two models (A and B) which can describe both two dimensional fragmentation and stochastic fractals. Model A exhibits multifractality on a unique support when describing a fragmentation process and on one of infinitely many possible supports when describing stochastic fractals. Model B obeys simple scaling.

Adriaan M. J. Schakel

The quantum critical behavior of an interacting, non-relativistic Bose theory with quenched disorder randomly distributed in space is investigated. The renormalization group is carried out in a double $ε$ expansion, where one $ε$ is the deviation of the effective space-time dimensionality from 4, while the other denotes the number of time dimensions. The dis

Peter Lenz, Franz Wegner

A recently proposed method of continuous unitary transformations is used to eliminate the interaction between electrons and phonons. The differential equations for the couplings represent an infinitesimal formulation of a sequence of Fröhlich-transformations. The two approaches are compared. Our result will turn out to be less singular than Fröhlich&#39;s. F

G J Rodgers, M K Hassan

We introduce three models of fragmentation in which the largest fragment in the system can be broken at each time step with a fixed probability, p. We solve these models exactly in the long time limit to reveal stable time invariant (scaling) solutions which depend on p and the precise details of the fragmentation process. Various features of these models ar

A Fledderjohann, C Gerhardt, K H Mutter, A Schmitt

In the presence of a uniform field the one-dimensional spin-$\frac{1}{2}$ antiferromagnetic Heisenberg model develops zero frequency excitations at field-dependent &#39;soft mode&#39; momenta. We determine three types of critical quantities, which we extract from the finite-size dependence of the lowest excitation energies, the singularities in the static st

Patrizia Castiglione, Giovanni Jona-Lasinio, Carlo Presilla

We present numerical evidence that in a system of interacting bosons there exists a correspondence between the spectral properties of the exact quantum Hamiltonian and the dynamical chaos of the associated mean field evolution. This correspondence, analogous to the usual quantum-classical correspondence, is related to the formal parallel between the second q

Markus P. Pfannmüller, Holger Frahm

Four dimensional irreducible representations of the superalgebra gl(2,1) carry a free parameter. We compute the spectra of the corresponding transfer matrices by means of the nested algebraic Bethe ansatz together with a generalized fusion procedure.

Xun Xue, Alvaro Ferraz

The fermionic and bosonic electron-hole low lying excitations in a semiconductor are analyzed at finite temperature in a unified way following Nambu&#39;s quasi-supersymmetric approach for the BCS model of superconductivity. The effective lagrangian for the fermionic modes and for the bosonic low lying collective excitations in the semiconductor is no longer

I Jensen, A J Guttmann, I G Enting

We derive low-temperature series (in the variable $u = \exp[-βJ/S^2]$) for the spontaneous magnetisation, susceptibility and specific heat of the spin-$S$ Ising model on the square lattice for $S=\frac32$, 2, $\frac52$, and 3. We determine the location of the physical critical point and non-physical singularities. The number of non-physical singularities clo

I Jensen, A J Guttmann

The finite-lattice method of series expansions has been combined with a new extrapolation procedure to extend the low-temperature series for the specific heat, spontaneous magnetisation and susceptibility of the spin-1 Ising model on the square lattice. The extended series were derived by directly calculating the series to order 99 (in the variable $u=\exp[-