March 1994 arXiv papers — page 6

M. Caselle, F. Gliozzi, P. Provero, S. Vinti

It is shown that finite size effects in the free energy of a rough interface of the 3D Ising and three--state Potts models are well described by the capillary wave model at {\em two--loop} order. The agreement between theoretical predictions and Monte Carlo simulations strongly supports the idea of the universality of this description of order--order interfa

Tonatiuh Matos, Nora Breton

Geodesics for a 5D magnetized Schwarzschild-like solution are analyzed by reducing the problem to the motion of a test particle in an effective potential. In absence of magnetic field comparison is established with Schwarzschild's geometry. Embedding diagrams are constructed in order to visualize the geometry of the metric. The study performed here is al

Lee Samuel Finn

Gravitational radiation from a binary neutron star or black hole system leads to orbital decay and the eventual coalescence of the binary's components. During the last several minutes before the binary components coalesce, the radiation will enter the bandwidth of the United States Laser Inteferometer Gravitational-wave Observatory (LIGO) and the French/

H. D. Zeh

It is argued that Hawking's `greatest mistake' may not have been a mistake at all. According to the canonical quantum theory of gravity for Friedmann type universes, any time arrows of general nature can only be correlated with that of the expansion. For recollapsing universes this seems to be facilitated in part by quantum effects close to their max

A. Bonanno, S. Droz, W. Israel, S. M. Morsink

We review the evidence for and against the possibility that the inner singularity of a black hole contains a lightlike segment which is locally mild and characterized by mass inflation.

P. L. Krapivsky

A diffusion-limited aggregation process, in which clusters coalesce by means of 3-particle reaction, A+A+A->A, is investigated. In one dimension we give a heuristic argument that predicts logarithmic corrections to the mean-field asymptotic behavior for the concentration of clusters of mass $m$ at time $t$, $c(m,t)~m^{-1/2}(log(t)/t)^{3/4}$, for $1 << m << \

L. F. Cugliandolo, J. Kurchan

We review the long-time off-equilibrium dynamical behaviour of two representative mean-field spin-glass models, namely the $p$-spin spherical and the Sherrington-Kirkpatrick models. We show how both models capture aging phenomena but with rather different characteristics. We discuss a scenario that allows for interpreting our results.

S. Fujimoto, N. Kawakami, S. -K. Yang

The finite-size spectrum in the Kondo problem is obtained from the Bethe-ansatz solution of the exactly solved models. We investigate the Anderson model, the highly correlated SU($ν$) Anderson model and the {\it s-d} exchange model. For all these models we find that the spectra exhibit the properties characteristic of the Fermi liquid fixed point, and hence

Leonid Pryadko, Shou-Cheng Zhang

We study the phase transition between the quantum Hall liquid state and the insulating state within the framework of the Chern-Simons-Landau-Ginzburg theory of the quantum Hall effect. For the transition induced by a background periodic potential in the absence of disorder, the model is described by a relativistic scalar field coupled to the Chern-Simons gau

Thomas V. Russo, Richard L. Martin, P. Jeffrey Hay

The excitation energies and ionization potentials of the atoms in the first transition series are notoriously difficult to compute accurately. Errors in calculated excitation energies can range from 1--4 eV at the Hartree-Fock level, and errors as high as 1.5eV are encountered for ionization energies. In the current work we present and discuss the results of

C. H. Lineweaver, G. F. Smoot, C. L. Bennett, E. L. Wright

The {\it COBE} DMR sky maps contain low-level correlated noise. We obtain estimates of the amplitude and pattern of the correlated noise from three techniques: angular averages of the covariance matrix, Monte Carlo simulations of two-point correlation functions, and direct analysis of the DMR maps. The results from the three methods are mutually consistent.

F. Bernardeau

It has been shown that the large--scale correlation functions of the density field (and velocity divergence field) follow a specific hierarchy in the quasilinear regime and for Gaussian initial conditions (Bernardeau 1992). The exact relationships between the cumulants of the probability distribution functions (the so-called $S_p$ parameters) are however sen

T. Foglizzo, M. Tagger

We present a detailed study of the growth of the Parker instability in a differentially rotating disk embedded in an azimuthal equilibrium magnetic field, such as the interstellar gas or an accretion disk. Basic properties of the instability without shear are first recalled. Differential rotation is modeled in the shearing sheet approximation, classical in t

R. A. Battye, E. P. S. Shellard

We study the production of cosmological axions in the standard scenario in which a global string network forms at the Peccei-Quinn phase transition. We make detailed calculations of the axions produced by string loops (a previously overlooked source), comparing these with estimates of other contributions from long strings and domain walls. We dilineate key u

Matthias Steinmetz, Matthias Bartelmann

The study by White (1984) on the growth of angular momentum in dark haloes is extended towards a more detailed investigation of the spin parameter $λ\equiv L\sqrt{E}/{G M^{2.5}}$. Starting from the Zel&#39;dovich approximation to structure formation, a dark halo is approximated by a homogeneous ellipsoid with the inertial tensor of the (highly irregular) Lag

Edmund Bertschinger, A. J. S. Hamilton

We derive the evolution equations for the electric and magnetic parts of the Weyl tensor for cold dust from both general relativity and Newtonian gravity. In a locally inertial frame at rest in the fluid frame, the Newtonian equations agree with those of general relativity. We give explicit expressions for the electric and magnetic parts of the Weyl tensor i

Aaron Bertram

The intuitive notion of the Gromov invariant for maps from a Riemann surface to a Grassmannian is shown to agree with the definition in \cite{BDW}. Also, an induction on the genus is proved, which extends the results of \cite{BDW} to a computation of all Gromov invariants associated to G(2,k). This is shown to agree with the conjectured formula of Vafa and I

Dieter Brill, Geoff Hayward

The gravitational action is not always additive in the usual sense. We provide a general prescription for the change in action that results when different portions of the boundary of a spacetime are topologically identified. We discuss possible implications for the superposition law of quantum gravity. We present a definition of `generalized additivity&#39;

M. Baker, J. S Ball, F. Zachariasen

We review the assumptions leading to the description of long distance QCD by a Lagrangian density expressed in terms of dual potentials. We find the color field distribution surrounding a quark anti-quark pair to first order in their velocities. Using these distributions we eliminate the dual potentials from the Lagrangian density and obtain an effective int

Gary G. Hoffman, Lawrence R. Pratt

Presented here are calculations of the distortion of the density of an electron gas due to the electrostatic field of a proton. Several models based upon the local density approximation (LDA) of density functional theory [linear response theory, Kohn-Sham (KS), optimized Thomas-Fermi theory (OTF), and OTF plus perturbation corrections] are compared with one

A. H. Mueller, Bimal Patel

Onium-onium scattering at high energy is used to illustrate a dipole picture of high energy hard scattering in the large $N_c$ limit. Single and double BFKL pomeron exchanges are calculated in the leading logarithmic approximation. An expression is given for the triple pomeron coupling when one of the pomeron&#39;s momentum is zero while the other two have m

Patrick Huet, Michael E. Peskin

We reconsider the model of quantum mechanics violation in the $\ko$--$\kob$ system, due to Ellis, Hagelin, Nanopoulos, and Srednicki, in which \cp- and \cpt-violating signatures arise from the evolution of pure states into mixed states. We present a formalism for computing time-dependent asymmetries in this model and show that present data constrains its par

Javier Satulovsky, Tania Tome

We propose a stochastic lattice gas model to describe the dynamics of two animal species population, one being a predator and the other a prey. This model comprehends the mechanisms of the Lotka-Volterra model. Our analysis was performed by using a dynamical mean-field approximation and computer simulations. Our results show that the system exhibits an oscil

M. V. Feigelman, L. B. Ioffe

We show that the recent experiments \cite{safar} reporting the onset of the non-local conductivity in the vortex state of $YBaCuO$ single crystals indicate the presence of a new liquid phase of vortices. This phase is intermediate between the normal metal and the Abrikosov lattice. We use the mapping of the vortex problem to the problem of bose liquid to det

N. Banerjee, R. Banerjee, S. Ghosh

We review the Batalin-Tyutin approach of quantising second class systems which consists in enlarging the phase space to convert such systems into first class. The quantisation of first class systems, it may be mentioned, is already well founded. We show how the usual analysis of Batalin-Tyutin may be generalised, particularly if one is dealing with nonabelia

R. Brustein, G. Veneziano

Isotropic string cosmology solutions can be classified into two duality related branches: one can be connected smoothly to an expanding Friedman-Robertson-Walker Universe, the other describes accelerated inflation or contraction. We show that, if the dilaton potential has certain generic properties, the two branches can evolve smoothly into each other. We fi

S. V. Kozyrev

An operation of a coproduct of representations of a bialgebra is defined. The coproduct operation for representations of the Hopf algebra of functions on the quantum group $SU_{q}(2)$ is investigated. A notion of a stable representation $Π$ is introdused. This means that the representation $Π$ is invariant under coproduct by arbitrary representation. Algebra

James H. Horne, Gregory Moore

We examine some novel physical consequences of the general structure of moduli spaces of string vacua. These include (1) finiteness of the volume of the moduli space and (2) chaotic motion of the moduli in the early universe. To fix ideas we examine in detail the example of the (conjectural) dilaton-axion ``$S$-duality&#39;&#39; of four-dimensional string co

Tomoyuki Inui, Akika Nakamichi

We develop a perturbation theory of four-dimensional topological 2-form gravity without cosmological constant. A 2-form and an $SU(2)$ connection 1-form are used as fundamental variables instead of metric. There is no quantum correction from two-loop and higher orders in covariant gauge, in Landau gauge and in background covariant gauge. We improve naive dim

Igor V. Barashenkov, Alexander O. Harin

We propose a new nonrelativistic Chern-Simons theory based on a simple modification of the standard Lagrangian. This admits asymptotically nonvanishing field configurations and is applicable to the description of systems of repulsive bosons. The new model supports topological vortices and has a self-dual limit, both in the pure Chern-Simons and in the mixed

Xiangdong Ji

In this talk, I will concentrate on $Q^2$-dependence of deep inelastic sum rules. I will first give a modern definition of deep-inelastic sum rules and then discuss physical origins of their scaling violation at finite $Q^2$. Following this, I discuss a few well-known examples, in particular, the Bjorken sum rule, which is at the center of interest of this s

Sacha Davidson, Hitoshi Murayama, Keith A. Olive

One of the most efficient mechanisms for producing the baryon asymmetry of the Universe is the decay of scalar condensates in a SUSY GUT as was first suggested by Affleck and Dine. We show that given a large enough asymmetry, the baryon number will be preserved down to low temperatures even if B - L = 0, because the baryon number carrying scalars form bose c

Hitoshi Yamamoto

It is shown that the existing data on two-body B decays, some of them only upper limits, are precise enough to perform an isospin analysis to extract the phase shifts due to final state interaction. Unlike charm decays, no significant final state interaction is observed in decays $B\to Dπ, Dρ$, and $D^*π$ supporting the factorization hypothesis in these deca

S. Narison

We present a compact analytic two-loop expression of the $SU(3)_f$ breaking effects on the ratio of the pseudoscalar decay constants $R_P \equiv f_{P_S}/f_P$ ($P \equiv D,B $), from which, we extract the precise values : $R_D = 1.15 \pm .04$, $R_B = 1.16 \pm .05 $, where the errors are mainly due to the uncalculated $α_s^2$-corrections. We also scan carefull

S. Narison

We estimate the sum of the $Υ\bar BB $ couplings using QCD Spectral Sum Rules (QSSR). Our result implies the phenomenological bound $ξ&#39;(vv&#39;=1) \geq -1.04$ for the slope of the Isgur-Wise function. An analytic estimate of the (physical) slope to two loops within QSSR leads to the accurate value $ξ&#39;(vv&#39;=1) \simeq -(1.00 \pm 0.02)$ due to the (a

Zhihua Dong, Herman J. Munczek, Craig D. Roberts

We discuss the chirally symmetric solution of the massless, quenched, Dyson-Schwinger equation for the fermion propagator in three and four dimensions. The solutions are manifestly gauge covariant. We consider a gauge covariance constraint on the fermion--gauge-boson vertex, which motivates a vertex Ansatz that both satisfies the Ward identity when the fermi

R. D. Ball, V. Barone, S. Forte, M. Genovese

We calculate the scale dependence of nonsinglet nucleon structure functions. Due to anomalous axial symmetry breaking a large flavour asymmetry of the quark--antiquark sea is generated nonperturbatively. This produces a strong scale dependence of the nonsinglet structure function in an intermediate range of $Q^2$. Evolving nonperturbatively a pure valence di

G. Degrassi, S. Fanchiotti, P. Gambino

The $O(G^2_μm_t^4)$ correction to the $ρ$ parameter is computed within the Standard Model using the current algebra formulation of radiative corrections. This approach is proved to be equivalent to the effective Lagrangian method proposed by Barbieri {\em et al.} Using the same framework, the $O(G^2_μm_t^2 m_z^2)$ correction to the ratio of neutral-to-charge

Thomas Mannel

The general structure of the $1/m$ corrections at zero recoil is studied. The relevant matrix elements are forward matrix elements of local higher dimensional operators and their time ordered products with higher order terms from the Lagrangian. These matrix elements may be classified in a simple way and the analysis at the non recoil point for the form fact

C. Ruge, P. Zhu, F. Wagner

We simulated the fourier transform of the correlation function of the Ising model in two and three dimensions using a single cluster algorithm with improved estimators. The simulations are in agreement with series expansion and the available exact results in $d=2$, which shows, that the cluster algorithm can succesfully be applied for correlations. We show a

Steven Corley, Ted Jacobson

Kaluza-Klein theory admits ``bubble" configurations, in which the circumference of the fifth dimension shrinks to zero on some compact surface. A three parameter family of such bubble initial data at a moment of time-symmetry (some including a magnetic field) has been found by Brill and Horowitz, generalizing the (zero-energy) ``Witten bubble" solution. Some

Jennie Traschen

The issues of scaling symmetry and critical point behavior are studied for fluctuations about extremal charged black holes. We consider the scattering and capture of the spherically symmetric mode of a charged, massive test field on the background spacetime of a black hole with charge $Q$ and mass $M$. The spacetime geometry near the horizon of a $|Q|=M$ bla

Miquel Dorca, Enric Verdaguer

We use wave packet mode quantization to compute the creation of massless scalar quantum particles in a colliding plane wave spacetime. The background spacetime represents the collision of two gravitational shock waves followed by trailing gravitational radiation which focus into a Killing-Cauchy horizon. The use of wave packet modes simplifies the problem of

Y. C. Chen, A. Moreo, F. Ortolani, E. Dagotto

The spin and density correlation functions of the two-dimensional Hubbard model at low electronic density $<n>$ are calculated in the ground state by using the power method, and at finite temperatures by using the quantum Monte Carlo technique. Both approaches produce similar results, which are in close agreement with numerical and high temperature expansion

Albert Diaz-Guilera

Two different models exhibiting self-organized criticality are analyzed by means of the dynamic renormalization group. Although the two models differ by their behavior under a parity transformation of the order parameter, it is shown that they both belong to the same universality class, in agreement with computer simulations. The asymptotic values of the cri

E. Granato

A one-dimensional quantum version of the frustrated XY (planar rotor) model is considered which can be physically realized as a ladder of Josephson-junctions at half a flux quantum per plaquette. This system undergoes a superconductor to insulator transition at zero temperature as a function of charging energy. The critical behavior is studied using a Monte

C. W. J. Beenakker, J. A. Melsen

This is a study of phase-coherent conduction through a ballistic point contact with disordered leads. The disorder imposes mesoscopic (sample-to-sample) fluctuations and weak-localization corrections on the conductance, and also leads to time-dependent fluctuations (shot noise) of the current. These effects are computed by means of a mapping onto an unconstr

C. W. J. Beenakker

Recent developments are reviewed in the scaling theory of phase-coherent conduction through a disordered wire. The Dorokhov-Mello-Pereyra-Kumar equation for the distribution of transmission eigenvalues has been solved exactly, in the absence of time-reversal symmetry. Comparison with the previous prediction of random-matrix theory shows that this prediction

Matthew B. Kennel, Henry D. I. Abarbanel, J. J. &#34;Sid&#34; Sidorowich

It is frequently asserted that in a chaotic system two initially close points will separate at an exponential rate governed by the largest global Lyapunov exponent. Local Lyapunov exponents, however, are more directly relevant to predictability. The difference between the local and global Lyapunov exponents, the large variations of local exponents over an at

V. Delgado

An alternative for the Higgs mechanism is proposed. It predicts the appearance in the broken phase of a scalar background field which may be interpreted as describing an almost uniform (i.e., homogeneous and isotropic) superfluid condensate of decoupled Higgs bosons. Quantum fields acquire mass as a consequence of nonperturbative interactions with those part

Robert Q. Topper, David L. Freeman

Monte Carlo methods are used to study the phase transition in ammonium chloride from the orientationally ordered $δ$ phase to the orientationally disordered $γ$ phase. An effective pair potential is used to model the interaction between ions. Thermodynamic properties are computed in the canonical and isothermal-isobaric ensembles. Each ammonium ion is treate

Avinash Dhar, Gautam Mandal, Spenta R. Wadia

We consider the formulation of two dimensional QCD in terms of gauge invariant bilocal operators (string field) which satisfy a $W_\infty$ algebra. In analogy with our work on the $c=1$ string field theory we derive an action and associated constraints for the bilocal field using the method of coadjoint orbits. The $1/N$ perturbation theory around a classica

D. Juriev

The interaction of various algebraic structures describing fusion, braiding and group symmetries in quantum projective field theory is an object of an investigation in the paper. Structures of projective Zamolodchikov al- gebras, their represntations, spherical correlation functions, correlation characters and envelopping QPFT-operator algebras, projective W

G. Delfino, G. Mussardo, P. Simonetti

The factorization condition for the scattering amplitudes of an integrable model with a line of defect gives rise to a set of Reflection-Transmission equations. The solutions of these equations in the case of diagonal $S$-matrix in the bulk are only those with $S =\pm 1$. The choice $S=-1$ corresponds to the Ising model. We compute the transmission and refle

N. N. Nikolaev, B. G. Zakharov

We discuss corrections to the Leading-Log$Q^{2}$ relationships between the gluon density $g(x,Q^{2})$ and $F_{L}(x,Q^{2}),\,\partial F_{T}(x,Q^{2}) /\partial \log Q^{2}$ in the HERA range of large ${1\over x}$. We find that the above quantities probe the gluon density $g(x,Q_{T,L}^{2})$ at $Q_{T,L}^{2}=C_{T,L}Q^{2}$, with the $Q^{2}$-rescaling factors $C_{T}

Serge Rudaz, Ajit M. Srivastava, Shikha Varma

Superconductors are the only experimentally accessible systems with spontaneously broken gauge symmetries which support topologically nontrivial defects, namely string defects. We propose two experiments whose aim is the observation of the dense network of these strings thought to arise, via the Kibble mechanism, in the course of a spontaneous symmetry break

R. D. Benguria, M. C. Depassier

We consider the problem of the speed selection mechanism for the one dimensional nonlinear diffusion equation $u_t = u_{xx} + f(u)$. It has been rigorously shown by Aronson and Weinberger that for a wide class of functions $f$, sufficiently localized initial conditions evolve in time into a monotonic front which propagates with speed $c^*$ such that $2 \sqrt

Michael R. Frank

The electromagnetic interaction with quarks is investigated through a relativistic, electromagnetic gauge-invariant treatment. Gluon dressing of the quark-photon vertex and the quark self-energy functions is described by the inhomogeneous Bethe-Salpeter equation in the ladder approximation and the Schwinger-Dyson equation in the rainbow approximation respect

Mihai Horoi, B. Alex Brown, Aurel Sandulescu

A recently proposed scaling law for the decay time of alpha particles is generalized for cluster decay. It is shown that for the decay of even-even parents, $logT_{1/2}$ depends linearly on the scaling variable S=(Z$_{c}$Z$_{d})^{0.6}/\sqrt{Q_{c}}$ and on the square root of the reduced mass of cluster and daughter.

Mihai Horoi, Günther Clausnitzer, B. Alex Brown, Ernie K. Warburton

A new calculation of the predominantly isoscalar PNC matrix element between the $J^πT$ $0^{+}1,0^{-}1$ (E$_{x} \approx$ 8.7 MeV) states in $^{14}$N has been carried out in a (0+1+2+3+4)$\hbar ω$ model space with the Warburton-Brown interaction. The magnitude of the PNC matrix element of 0.22 to 0.34 eV obtained with the DDH PNC interaction is substantially s

Ezra Getzler, J. D. S. Jones

This paper provides some background to the theory of operads, used in the first author&#39;s papers on 2d topological field theory (hep-th/921204, CMP 159 (1994), 265-285; hep-th/9305013). It is intended for specialists.

Eva Silverstein, Edward Witten

We derive a condition under which (0,2) linear sigma models possess a ``left-moving&#39;&#39; conformal stress tensor in $\bq$ cohomology (i.e. which leaves invariant the ``right-moving&#39;&#39; ground states) even away from their critical points. At the classical level this enforces quasihomogeneity of the superpotential terms. The persistence of this stru

Daniel Altschuler, Laurent Freidel

Using properties of ordered exponentials and the definition of the Drinfeld associator as a monodromy operator for the Knizhnik-Zamolodchikov equations, we prove that the analytic and the combinatorial definitions of the universal Vassiliev invariants of links are equivalent.

Frank W. Nijhoff, Gen-Di Pang

We introduce an integrable time-discretized version of the classical Calogero-Moser model, which goes to the original model in a continuum limit. This discrete model is obtained from pole solutions of a discretized version of the Kadomtsev-Petviashvili equation, leading to a finite-dimensional symplectic mapping. Lax pair, symplectic structure and sufficient

Nemanja Kaloper

The purpose of this work is to show that there exists an additional invariance of the $β$-function equations of string theory on $d+1$-dimensional targets with $d$ toroidal isometries. It corresponds to a shift of the dilaton field and a scaling of the lapse function, and is reminiscent of string field redefinitions. While it preserves the form of the $β$-fu

U. Baur, T. Han, J. Ohnemus

We demonstrate that the Standard Model amplitude for $f_1 \bar f_2 \rightarrow W^\pm Z $ at the Born-level exhibits an approximate zero located at $\cosθ= (g^{f_1}_{-} + g^{f_2}_{-}) / (g^{f_1}_{-} - g^{f_2}_{-})$ at high energies, where the $g^{f_i}_{-}$ ($i=1,2$) are the left-handed couplings of the $Z$-boson to fermions and $θ$ is the center of mass scatt

V. S. Fadin, V. A. Khoze, M. I. Kotsky

We study the spin properties of top quarks produced in collisions of polarized photons in the threshold region. For a relatively heavy top quark the influence of non-perturbative effects is small and its polarization parameters can be predicted in perturbative QCD. The measurements of the top polarization may allow a novel test of QCD in the $t\bar{t}$ syste

S. Hegyi

Properties of cumulant- and combinant ratios are studied for multihadron final states composed of Poisson distributed clusters. The application of these quantities to ``detect&#39;&#39; clusters is discussed. For the scaling laws which hold in hierarchical clustering models (void scaling, combinant scaling) a generalization is provided. It is shown that test

A. Ballestrero, E. Maina

We propose a new helicity formalism based on the formal insertion in spinor lines of a complete set of states build up with unphysical spinors. The method is developed both for massless and massive fermions for which it turns out to be particularly fast. All relevant formulae are given.

N. N. Nikolaev, B. G. Zakharov

Determination of the intercept of the BFKL pomeron is one of the pressing issues in the high energy physics. Earlier we have shown that, at the dipole size $r=r_Δ=(0.1-0.2)$f, the dipole cross section $σ(x,r)$ which is a solution of the generalized BFKL equation, exhibits a precocious asymptotic behavior $σ(x,r)\propto \left({1\over x}\right)^{Δ_{\Pom}}$. In

L. Gamberale, G. Preparata, She-Sheng XUE

A general discussion is presented of the response of a gauge-field system to external magnetic fields, in the light of a theorem due to S. Elitzur. As a result a natural understanding emerges of some recent puzzling results from lattice MC simulations, as well as of the phenomenon of ``perfect diamagnetism&#39;&#39; of non-abelian gauge theories, discovered

M. Caselle, F. Gliozzi, S. Vinti

A gas of self-avoiding surfaces with an arbitrary polynomial coupling to the gaussian curvature and an extrinsic curvature term can be realized in a three-dimensional Ising bcc lattice with only three local couplings. Similar three parameter realizations are valid also in other lattices. The relation between the crumpling transition and the roughening is dis

M. D. Johnson, O. Heinonen

We present an approach to steady-state mesoscopic transport based on the maximum entropy principle formulation of nonequilibrium statistical mechanics. This approach is valid in the nonlinear regime of high current, and yields the quantization observed in the integer quantum Hall effect at large currents. A key ingredient of this approach, and its success in

Claudius Gros

We consider the Hubbard model on the infinite-dimensional Bethe lattice and construct a systematic series of self-consistent approximations to the one-particle Green&#39;s function, $G^{(n)}(ω),\ n=2,3,\dots\ $ . The first $n-1$ equations of motion are exactly fullfilled by $G^{(n)}(ω)$ and the $n$&#39;th equation of motion is decoupled following a simple se

Ferenc Igloi

We present a general method to calculate the connected correlation function of random Ising chains at zero temperature. This quantity is shown to relate to the surviving probability of some one-dimensional, adsorbing random walker on a finite intervall, the size of which is controlled by the strength of the randomness. For different random field and random b

Ajit M. Srivastava

We propose a simple experiment to investigate the intercommutation of flux tubes in type II superconductors. Using this method the intercommutation of strings can be observed directly and the dependence of intercommutation on the angle of crossing of strings can also be analyzed.

David R. Wolf, David H. Wolpert

We present estimators for entropy and other functions of a discrete probability distribution when the data is a finite sample drawn from that probability distribution. In particular, for the case when the probability distribution is a joint distribution, we present finite sample estimators for the mutual information, covariance, and chi-squared functions of

David H. Wolpert, David R. Wolf

We present estimators for entropy and other functions of a discrete probability distribution when the data is a finite sample drawn from that probability distribution. In particular, for the case when the probability distribution is a joint distribution, we present finite sample estimators for the mutual information, covariance, and chi-squared functions of

Jean-Marc Richard

We present a simple proof of the stability of the hydrogen molecule $(M^+M^+m^-m^-)$. It does not rely on the proton-to-electron mass ratio $M/m$ being very large, and actually holds for arbitrary values of $M/m$. Some asymmetric molecules of the type $(m_1^+m_2^+m_3^-m_4^-)$ are also stable. Possible applications to molecules containing antiparticles and to

David L. Freeman, J. D. Doll

Using a Hubbard-Stratonovich transformation coupled with Fourier path integral methods, expressions are derived for the numerical evaluation of the microcanonical density of states for quantum particles obeying Boltzmann statistics. A numerical algorithmis suggested to evaluate the quantum density of states and illustrated on a one-dimensional model system.

H. Kjeldsen, T. R. Bedding

There are no good predictions for the amplitudes expected from solar-like oscillations in other stars. In the absence of a definitive model for convection, which is thought to be the mechanism that excites these oscillations, the amplitudes for both velocity and luminosity measurements must be estimated by scaling from the Sun. In the case of luminosity meas

E. Pian, R. Falomo, R. Scarpa, A. Treves

Near--infrared, optical and ultraviolet quasi--simultaneous observations of 11 BL Lacertae objects are reported. For all but one source the dereddened spectral flux distribution in the $8\cdot10^{13}-2\cdot10^{15}$ Hz frequency range can be described by a single power law f$_ν\propto ν^{-α}$ with average spectral index $<α>$ = 0.88 $\pm$ 0.42 (standard devia

D. Nemeschansky, N. P. Warner

We show how special forms of an $N=2$ Landau-Ginzburg potential directly imply the presence of an $N=2$ super-$W$ algebra. If the Landau-Ginzburg model has a super-$W$ algebra, we show how the elliptic genus can be refined so as to give much more complete information about the structure of the model. We study the super-$W_3$ model in some detail, and present

M. Novello, J. M. Salim, M. C. Motta da Silva, S. E. Joras

The theory of perturbation of Friedman-Robertson-Walker (FRW) cosmology is analysed exclusively in terms of observable quantities. Although this can be a very complete and general procedure we limit our presentation here to the case of irrotational perturbations for simplicity. We show that the electric part of Weyl conformal tensor {\bf $E$} and the shear {

Alex C. Kalloniatis, Hans-Christian Pauli, Stephen Pinsky

We consider light-cone quantized ${\rm{QCD}}_{1+1}$ on a `cylinder&#39; with periodic boundary conditions on the gluon fields. This is the framework of discretized light-cone quantization. We review the argument that the light-cone gauge $A^+=0$ is not attainable. The zero mode is a dynamical and gauge invariant field. The attainable gauge has a Gribov ambig

Johan Bijnens, Joaquim Prades

The two-point functions in generalized Nambu--Jona-Lasinio models are calculated to all orders in momenta and quark masses to leading order in $1/N_c$. The use of Ward identities and the heat-kernel expansion allows for a large degree of regularization independence. We also show how this approach works to the same order for three-point functions on the examp

Roberto Zucchini

Developing upon the ideas of ref. \ref{6}, it is shown how the theory of classical $W$ algebras can be formulated on a higher genus Riemann surface in the spirit of Krichever and Novikov. The basic geometric object is the Drinfeld--Sokolov principal bundle $L$ associated to a simple complex Lie group $G$ equipped with an $SL(2,\Bbb C)$ subgroup $S$, whose pr

R. Jackiw

Topological Structures in the Standard Model at high $T$ are discussed.

D. Cangemi, R. Jackiw

We construct quantum states for a (1+1) dimensional gravity-matter model that is also a gauge theory based on the centrally extended Poincaré group. Explicit formulas are found, which exhibit interesting structures. For example wave functionals are gauge invariant except for a gauge non-invariant phase factor that is the Kirillov-Kostant 1-form on the (co-)

S. Boukraa, J-M. Maillard, G. Rollet

We describe birational representations of discrete groups generated by involutions, having their origin in the theory of exactly solvable vertex-models in lattice statistical mechanics. These involutions correspond respectively to two kinds of transformations on $q \times q$ matrices: the inversion of the $q \times q$ matrix and an (involutive) permutation o

E. Ramos

In a recent paper Dargis and Mathieu introduced integrodifferential odd flows for the supersymmetric KdV equation. These flows are obtained from the nonlocal conservation laws associated with the fourth root of its Lax operator. In this note I show that only half of these flows are of the standard Lax form, while the remaining half provide us with hamiltonia

Sergey V. Shabanov

It is shown that q-deformed quantum mechanics (q-deformed Heisenberg algebra) can be interpreted as quantum mechanics on Kaehler manifolds, or as a quantum theory with second (or first-) class constraints. (Saclay, T93/027).

A. A. Kehagias, P. A. A. Meessen

A WZW model for the non-semi-simple D-dimensional Heisenberg group, which directly generalizes the E_{2}^{c} group, is constructed. It is found to correspond to an D-dimensional string background of plane-wave type with physical Lorentz signature D-2. Perturbative and non-perturbative considerations lead both to an integer central charge c=D.

Michael B. Green

This paper considers closed-string states of type 2b superstring theory in which the whole string is localized at a single point in superspace. Correlation functions of these (scalar and pseudoscalar) states possess an infinite number of position-space singularities inside and on the light-cone as well as a space-like singularity outside the light-cone.\foot

A. Liguori, M. Mintchev

We develop a rigorous framework for constructing Fock representations of quantum fields obeying generalized statistics associated with certain solutions of the spectral quantum Yang-Baxter equation. The main features of these representations are investigated. Various aspects of the underlying mathematical structure are illustrated by means of explicit exampl

Toshihiro Sasada

We study the condition for the appearance of space-time supercharges in twisted sectors of asymmetric orbifold models. We present a list of the asymmetric $Z_N$-orbifold models which satisfy a simple condition necessary for the appearance of space-time supercharges in twisted sectors. We investigate whether or not such asymmetric orbifold models possess $N=1

Satoshi Matsuda

The representation theories of the SU(2)$_k$-extended $N$=4 superconformal algebras (SCAs) with $arbitrary$ level $k$ are developed being based on their Feigin-Fuchs representations found recently by the present author. A basic unit of the representation blocks consisting of eight \lq\lq boson-like\rq\rq\ and eight \lq\lq fermion-like\rq\rq\ conformal fields

Thomas G. Rizzo

The implications of the recent measurement of the left-right asymmetry, $A_{LR}$, by the SLD Collaboration for theories with extended gauge sectors is examined. We show that it is possible to arrange for large, negative values of $S$, based on an analysis of leptonic data, without serious side effects for other observables in certain classes of models. The i

Damien Pierce, Aris Papadopoulos

We determine the radiative corrections to the masses of the gauginos and Higgsinos in the MSSM, including all sectors of the theory in a one-loop calculation in the on-mass-shell renormalization scheme. We find that a gluino which is massless at tree level receives a mass of between 0 and 3 GeV, primarily due to the top/stop contribution. This radiatively ge

L. Bergstrom, J. Kaplan

We calculate, using unitarity, a lower bound on the branching ratio $χχ\to γγ$ and $χχ\to γZ$, where $χ$ is any halo dark matter particle that has $W^+W^-$ as one of the major annihilation modes. Examples of such particles are supersymmetric particles with a dominant Higgsino component, or heavy triplet neutrinos. A substantial branching ratio is found for t