arXiv papers from January 1994

Brian H. Smith, M. B. Voloshin

We point out that, contrary to some recent claims, there is no intrinsic long-distance uncertainty in perturbative calculation of the QCD effects in the $t \tb$ and $t \bb$ loops giving the electroweak corrections proportional to $m_t^2$. If these corrections are expressed in terms of the ``on-shell" mass $m_t$, the only ambiguity arising is that associated

Miroslav Doresic

We construct the number operator for particles obeying infinite statistics, defined by a generalized q-deformation of the Heisenberg algebra, and prove the positivity of the norm of linearly independent state vectors.

X. Song, J. S. McCarthy

Deep inelastic polarized and unpolarized structure functions for a free nucleon are obtained in a modified Center-of-Mass bag model, which includes the symmetry breaking effects from spin-dependent interactions. The quark distribution functions, calculated at $Q_0^2\simeq$ (0.9GeV/c)$^2$, are evolved to higher $Q^2$ region and compared with the data and othe

Thomas C. Halsey

I present a first-principles theory of diffusion-limited aggregation in two dimensions. A renormalized mean-field approximation gives the form of the unstable manifold for branch competition, following the method of Halsey and Leibig [Phys. Rev. A {\bf 46}, 7793 (1992)]. This leads to a result for the cluster dimensionality, D \approx 1.66, which is close to

Per Arne Rikvold, H. Tomita, S. Miyashita, Scott W. Sides

The lifetimes of metastable states in kinetic Ising ferromagnets are studied by droplet theory and Monte Carlo simulation, in order to determine their dependences on applied field and system size. For a wide range of fields, the dominant field dependence is universal for local dynamics and has the form of an exponential in the inverse field, modified by univ

Adel Bilal

I prove the recently conjectured relation between the $2\times 2$-matrix differential operator $L=\partial^2-U$, and a certain non-linear and non-local Poisson bracket algebra ($V$-algebra), containing a Virasoro subalgebra, which appeared in the study of a non-abelian Toda field theory. Here, I show that this $V$-algebra is precisely given by the second Gel

D. A. R. Dalvit, F. D. Mazzitelli

We consider a quantum scalar field on an arbitrary gravitational background. We obtain the effective {\it in-in} equations for the gravitational fields using a covariant and non-local approximation for the effective action proposed by Vilkovisky and collaborators. {}From these equations, we compute the quantum corrections to the Newtonian potential. We find

Carlberg, Pritchet, Infante

A sample of faint, V magnitude selected, galaxy pairs, having physical separations less than approximately 20\hkpc, is used to examine the rise in the merger rate with redshift and the statistical relations between close pairs and the field galaxy population. Redshifts have been obtained for 14 galaxies ($V \le 22.5$) that are in close ($\theta < 6\arcs$) pa

Pavel Šmilauer, Miroslav Kotrla

A simple model of epitaxial growth proposed by Wolf and Villain is investigated using extensive computer simulations. We find an unexpectedly complex crossover behavior of the original model in both 1+1 and 2+1 dimensions. A crossover from the effective growth exponent $\beta_{\rm eff}\!\approx\!0.37$ to $\beta_{\rm eff}\!\approx\!0.33$ is observed in 1+1 di

Dirk Kreimer

We discuss the consistency of a new \gf -scheme with renormalization. In particular we study the power-counting behaviour of multiloop graphs to prove its consistency. As a side effect we obtain a short proof of the Adler-Bardeen theorem. Further we show that this \gf-scheme does not modify the BRST identities at any loop orders in contrast to BM type scheme

Rainer Sommer

We summarize the present status of lattice gauge theory computations of the leptonic decay constants $f_D$ and $f_B$. The various sources of systematic errors are explained in a manner easily understood by the non--expert. The results obtained by the different groups are then systematically compared. As a result, we derive estimates for $f_D$ and $f_B$ in th

M. Gaberdiel

An explicit transformation formula for chiral conformal fields under arbitrary holomorphic coordinate transformations is established. As an application I calculate the transformation law of the general quasiprimary field at level 4.

M. Alimohammadi, F. Ardalan

By boosting the vertex operators of Witten's $SL(2,R)/U(1)$ black hole, we show that in the region V they lead to the primary fields of $c=1$ matter coupled to gravity at nonzero cosmological constant, while there is no such correspondence in the region I, showing that Witten's black hole corresponds to $2d$ gravity only in a certain region and in a specific

B. Eynard

A recursive method is derived to calculate all eigenvalue correlation functions of a random hermitian matrix in the large size limit, and after smoothing of the short scale oscillations. The property that the two-point function is universal, is recovered and the three and four-point functions are given explicitly. One observes that higher order correlation f

H. J. Boonstra

We study the cohomology of the critical $W_4$ string using the $W_4$ BRST charge in a special basis in which it contains three separately nilpotent BRST charges. This allows us to obtain the physical operators in three steps. In the first step we obtain the cohomology associated to a spin-four constraint only, and it contains operators of the $c={4\over5}$ $

P. Di Francesco, M. Gaudin, C. Itzykson, F. Lesage

In the context of the fractional quantum Hall effect, we investigate Laughlin's celebrated ansatz for the groud state wave function at fractional filling of the lowest Landau level. Interpreting its normalization in terms of a one component plasma, we find the effect of an additional quadrupolar field on the free energy, and derive estimates for the thermody

Viacheslav V. Nikulin

We prove the general diagram method theorem valid for the quite large class of 3-folds with Q-factorial singularities (see Basic Theorem 1.3.2 and also Theorem 2.2.6). This gives the generalization of our results about Fano 3-folds with Q-factorial terminal singularities (Preprint alg-geom/9311007). As an application, we get the following result about 3-dime

She-Sheng Xue

Considering a self-interaction only of mirror fermions in the context of a lattice-regularized fermion field theory, we show that the system undergoes spontaneous breaking of chiral symmetry and mirror-fermion masses are generated. However, it is explicitly shown that there are no Goldstone bosons appearing together with this spontaneous symmetry breaking ph

Joaquim Gomis, Jordi París

Quantization of anomalous gauge theories with closed, irreducible gauge algebra within the extended Field-Antifield formalism is further pursued. Using a Pauli-Villars (PV) regularization of the generating functional at one loop level, an alternative form for the anomaly is found which involves only the regulator. The analysis of this expression allows to co

J. W. Goodison, D. J. Toms

We consider the forced harmonic oscillator quantized according to infinite statistics ( a special case of the `quon' algebra proposed by Greenberg ). We show that in order for the statistics to be consistently evolved the forcing term must be identically zero for all time. Hence only the free harmonic oscillator may be quantized according to infinite statist

Orit Levin, Asher Peres

There is a large class of classical null-fronted metrics in which a free scalar field has an infinite number of conservation laws. In particular, if the scalar field is quantized, the number of particles is conserved. However, with more general null-fronted metrics, field quantization cannot be interpreted in terms of particle creation and annihilation opera

Ulf-G. Meißner

I consider some selected topics in chiral perturbation theory (CHPT). For the meson sector, emphasis is put on processes involving pions in the isospin zero S-wave which require multi-loop calculations. The advantages and shortcomings of heavy baryon CHPT are discussed. Some recent results on the structure of the baryons are also presented.

J. S. Dowker

The recently discussed notion of geometric entropy is shown to be related to earlier calculations of thermal effects in Rindler space. The evaluation is extended to de Sitter space and to a two-dimensional black hole.

H. Nakamure, M. Takahashi

A nonlinear susceptibilities (the third derivative of a magnetization $m_S$ by a magnetic field $h$ ) of the $S$=1/2 ferromagnetic Heisenberg chain and the classical Heisenberg chain are calculated at low temperatures $T.$ In both chains the nonlinear susceptibilities diverge as $T^{-6}$ and a linear susceptibilities diverge as $T^{-2}.$ The arbitrary spin $

V. F. Dmitriev, I. B. Khriplovich, V. B. Telitsin

Nuclear anapole moments of $\;^{133}$Cs, $\;^{203,205}$Tl, $\;^{207}$Pb, $\;^{209}$Bi are treated in the single-particle approximation. Analytical results are obtained for the oscillator potential without spin-orbit interaction. Then the anapole moments are calculated numerically in a Woods-Saxon potential which includes spin-orbit interaction. The results o

Kazumasa Miyake, Osamu Narikiyo

Comment on `Anomalously Large Gap Anisotropy in the a-b Plane of Bi$_{\bf 2}$Sr$_{\bf 2}$CaCu$_{\bf 2}$O$_{{\bf 8+}δ}$&#39;, Kazumasa Miyake and Osamu Narikiyo, In a recent Letter, Shen and collaborators [Phys. Rev. Lett. {\bf 70}, 1555 (1993)] reported that angle-resolved photoemission spectra (ARPES) in Bi-2212 cuprate superconductor far below $T_{\rm c}$

Oscar F. Hernandez, Brian R. Hill

Lattice calculations of matrix elements involving heavy-light quark bilinears are of interest in calculating a variety of properties of B and D mesons, including decay constants and mixing parameters. A large source of uncertainty in the determination of these properties has been uncertainty in the normalization of the lattice-regularized operators that appe

Marc Potters, William Bialek

The nervous system solves a wide variety of problems in signal processing. In many cases the performance of the nervous system is so good that it apporaches fundamental physical limits, such as the limits imposed by diffraction and photon shot noise in vision. In this paper we show how to use the language of statistical field theory to address and solve prob

X. Song, V. Gupta

We suggest a general formalism to treat a baryon as a composite system of three quarks and a `sea'. In this formalism, the sea is a cluster which can consists of gluons and quark-antiquark pairs. The hadron wave function with a sea component is given. The magnetic moments, related sum rules and axial weak coupling constants are obtained. The data seems to fa

M. V. N. Murthy, R. Shankar

We show that Haldanes new definition of statistics, when generalised to infinite dimensional Hilbert spaces, is equal to the high temperature limit of the second virial coefficient. We thus show that this exclusion statistics parameter, g , of anyons is non-trivial and is completely determined by its exchange statistics parameter $\alpha$. We also compute g

M. M. Tsypin

We study the low-energy effective action $S_{eff}[\varphi]$ for the one-component real scalar field theory in three Euclidean dimensions in the symmetric phase, concentrating on its static part --- effective potential $V_{eff}(\varphi)$. It characterizes the approach to the phase transition in all systems that belong to the 3d Ising universality class. We co

Ashok Das, Jnanadeva Maharana

The evolution of a closed NSR string is considered in the background of constant graviton and antisymmetric fields. The $\sigma$-model action is written in a manifestly supersymmetric form in terms of superfields. The first order formalism adopted for the closed bosonic string is generalised to implement duality transformations and the constant dual backgrou

Jnanadeva Maharana, Lambodhar P. Singh

We have presented canonical and path integral formulations of a theory of loops and closed strings with the matter field quanta transforming in the adjoint representation of the SU(N) gauge group. The physical processes arising out of the interactions of loops and closed strings are discussed.

Henk Bruin, Gerhard Keller, Tomasz Nowicki, Sebastian van Strien

In this paper we shall show that there exists a polynomial unimodal map f: [0,1] -> [0,1] which is 1) non-renormalizable(therefore for each x from a residual set, $\omega(x)$ is equal to an interval), 2) for which $\omega(c)$ is a Cantor set, and 3) for which $\omega(x)=\omega(c)$ for Lebesgue almost all x. So the topological and the metric attractor of such

G. M. Zhang, S. Feng, L. Yu

Using the fermion-spin transformation to implement spin-charge separation of constrained electrons, a model of two $t-J$ chains with interchain single-electron hopping is studied by abelian bosonization. After spin-charge decoupling the charge dynamics can be trivially solved, while the spin dynamics is determined by a strong-coupling fixed point where the c

Andrew L. Berkin, Ronald W. Hellings

We consider multiple scalar fields coupled to gravity, with special attention given to two-field theories. First, the conditions necessary for these theories to meet solar system tests are given. Next, we investigate the cosmological evolution of the fields to see if these conditions can be met. Solutions are found in the dust era, as well as radiation and c

Michael Joyce, Tomislav Prokopec, Neil Turok

One mechanism for generating a baryon asymmetry at the electroweak phase transition involves propagation of particle asymmetries generated by reflection from the bubble walls into the unbroken phase. Hitherto attention has focussed on top quarks because of their large mass and thus effective scattering from bubble walls. In this paper we point out that lepto

M. Joyce, T. Prokopec, N. Turok

In unconstrained thermal equilibrium a local potential for total or fermionic hypercharge does not bias electroweak anomalous processes. We consider two proposed mechanisms for electroweak baryogenesis in this light. In `spontaneous' baryogenesis, which was argued to apply in the `adiabatic' limit of thick, slow walls, a non-zero result was obtained by setti

Ana Lopez, A. G. Rojo, Eduardo Fradkin

We consider the anisotropic quantum Heisenberg antiferromagnet (with anisotropy $\lambda$) on a square lattice using a Chern-Simons (or Wigner-Jordan) approach. We show that the Average Field Approximation (AFA) yields a phase diagram with two phases: a Ne{\`e}l state for $\lambda>\lambda_c$ and a flux phase for $\lambda<\lambda_c$ separated by a second orde

Sean M. Carroll, Daniel Z. Freedman, Miguel E. Ortiz, Don N. Page

We discuss the canonical quantization of $N=1$ supergravity in the functional Schrodinger representation. Although the form of the supersymmetry constraints suggests that there are solutions of definite order $n$ in the fermion fields, we show that there are no such states for any finite $n$. For $n=0$, a simple scaling argument definitively excludes the pur

Raphael Blumenfeld

I show that the evolution of a two dimensional surface in a Laplacian field can be described by Hamiltonian dynamics. First the growing region is mapped conformally to the interior of the unit circle, creating in the process a set of mathematical zeros and poles that evolve dynamically as the surface grows. Then the dynamics of these quasi-particles is analy

Raphael Blumenfeld

It is shown that the dynamics of the growth of a two dimensional surface in a Laplacian field can be mapped onto Hamiltonian dynamics. The mapping is carried out in two stages: first the surface is conformally mapped onto the unit circle, generating a set of singularities. Then the dynamics of these singularities are transformed to Hamiltonian action-angle v

K. G. Wilson, T. Walhout, A. Harindranath, W. M. Zhang

In this work the determination of low-energy bound states in Quantum Chromodynamics is recast so that it is linked to a weak-coupling problem. This allows one to approach the solution with the same techniques which solve Quantum Electrodynamics: namely, a combination of weak-coupling diagrams and many-body quantum mechanics. The key to eliminating necessaril

Kareljan Schoutens

We show that the $SU(N)$, level-1 Wess-Zumino-Witten conformal field theory provides a natural realization of the Yangian $Y(sl_N)$ for $N\geq 3$. We also construct a hamiltonian $H_2$ which commutes with the Yangian generators and study its spectrum. Our results, which generalize work by Haldane et al.\ \cite{hhtbp}, provide the field theory extension of th

S. Hou, J. Sterling, S. Chen, G. D. Doolen

A subgrid turbulence model for the lattice Boltzmann method is proposed for high Reynolds number fluid flow applications. The method, based on the standard Smagorinsky subgrid model and a single-time relaxation lattice Boltzmann method, incorporates the advantages of the lattice Boltzmann method for handling arbitrary boundaries and is easily implemented on

Shuling Hou, Qisu Zou, Shiyi Chen, Gary D. Doolen

A detailed analysis is presented to demonstrate the capabilities of the lattice Boltzmann method. Thorough comparisons with other numerical solutions for the two-dimensional, driven cavity flow show that the lattice Boltzmann method gives accurate results over a wide range of Reynolds numbers. Studies of errors and convergence rates are carried out. Compress

Lotfi Belkhir

We calculate exactly, using finite size techniques, the quantum mechanical and many-body effects to the self-capacitance of a spherical quantum dot in the regime of extreme confinement, where the radius of the sphere is much smaller than the effective Bohr radius. We find that the self-capacitance oscillates as a function of the number of electrons close to

Michele Cook

It is a result of Gruson and Peskine that the invariants of a set points in $\ptwo$ in general position are connected. Associated to a space curve there are sequences of invariants which generalize the invariants of points in $\ptwo$. The main result of this paper is to show that the invariants of reduced, irreducible, non-degenerate curves in $\pthree$ also

R. Bar-Kana

We compute energy density and strain induced by a primordial spectrum of gravitational waves on terrestrial- and space-based detectors (e.g., LIGO) as constrained by the COBE detection of microwave background anisotropy. For the case where the spectrum is created during inflation, we find new, stricter upper bounds on the induced strain, making detection unl

Daniel Martinez, Shiyi Chen, William Matthaeus

Lattice gas and lattice Boltzmann methods are recently developed numerical schemes for simulating a variety of physical systems. In this paper a new lattice Boltzmann model for modeling two-dimensional incompressible magnetohydrodynamics (MHD) is presented. The current model fully utilizes the flexibility of the lattice Boltzmann method in comparison with pr

Gerhard Buchalla

The calculation of QCD corrections beyond the leading logarithmic approximation for the short-distance dominated rare decay $K^+\to\pi^+\nu\bar\nu$ is summarized. This analysis requires the complete ${\cal O}(\alpha_s)$ corrections to the top contribution to all orders in the top-quark mass and a two-loop renormalization group (RG) calculation for the charm

F. M"uller-Hoissen

For the two-parameter matrix quantum group GLp,q(2) all bicovariant differential calculi (with a four-dimensional space of 1-forms) are known. They form a one-parameter family. Here, we give an improved presentation of previous results by using a different parametrization. We also discuss different ways to obtain bicovariant calculi on the quantum subgroup S

A. Dimakis, F. M"uller-Hoissen

We explore a differential calculus on the algebra of smooth functions on a manifold. The former is `noncommutative' in the sense that functions and differentials do not commute, in general. Relations with bicovariant differential calculus on certain quantum groups and stochastic calculus are discussed. A similar differential calculus on a superspace is shown

A. Dimakis, F. M"uller-Hoissen

There is a deformation of the ordinary differential calculus which leads from the continuum to a lattice (and induces a corresponding deformation of physical theories). We recall some of its features and relate it to a general framework of differential calculus on discrete sets. This framework generalizes the usual (lattice) discretization.

Henar Herrero, Hermann Riecke

Localized traveling wave trains or pulses have been observed in various experiments in binary mixture convection. For strongly negative separation ratio, these pulse structures can be described as two interacting fronts of opposite orientation. An analytical study of the front solutions in a real Ginzburg-Landau equation coupled to a mean field is presented

A. Dimakis, F. M"uller-Hoissen

We develop differential calculus and gauge theory on a finite set G. An elegant formulation is obtained when G is supplied with a group structure and in particular for a cyclic group. Connes' two-point model (which is an essential ingredient of his reformulation of the standard model of elementary particle physics) is recovered in our approach. Reductions of

O. F. Dayi

The recently proposed generalized field method for solving the master equation of Batalin and Vilkovisky is applied to a gauge theory of quadratic Lie algebras in 2-dimensions. The charge corresponding to BRST symmetry derived from this solution in terms of the phase space variables by using the Noether procedure, and the one found due to the BFV-method are

Wolfram Freudling, Luiz Nicolaci da Costa, Paulo S. Pellegrini

The reconstruction of the peculiar velocity field from the 1.936~Jy iras selected sample of galaxies is compared to a similar reconstruction from an optically selected sample. A general method for combining different samples to reconstruct a self-consistent density and peculiar velocity field is presented. The method is applied to determine how sensitive the

I. Jack, D. R. T. Jones, K. L. Roberts

For some years there has been uncertainty over whether regularisation by dimensional reduction (DRED) is viable for non-supersymmetric theories. We resolve this issue by showing that DRED is entirely equivalent to standard dimensional regularisation (DREG), to all orders in perturbation theory and for a general renormalisable theory. The two regularisation s

D. Juriev

The universal deformation of the complex disk is studied from the viewpoint of infinite-dimensional geometry. The structure of a subsymmetric space on the universal deformation is described. The foliation of the universal deformation by subsymmetry mirrors is shown to determine a real polarization. The subject of the paper maybe of interest to specialists in

Andrzej Sitarz

We build a toy model of differential geometry on the real line, which includes derivatives of the second order. Such construction is possible only within the framework of noncommutative geometry. We introduce the metric and briefly discuss two simple physical models of scalar field theory and gauge theory in this geometry.

Andrzej Sitarz

We introduce the linear connection in the noncommutative geometry model of the product of continuous manifold and the discrete space of two points. We discuss its metric properties, define the metric connection and calculate the curvature. We define also the Ricci tensor and the scalar curvature. We find that the latter differs from the standard scalar curva

J. -P. Kownacki, A. Krzywicki

The grand-canonical ensemble of dynamically triangulated surfaces coupled to four species of Ising spins (c=2) is simulated on a computer. The effective string susceptibility exponent for lattices with up to 1000 vertices is found to be $\gamma = - 0.195(58)$. A specific scenario for $c > 1$ models is conjectured.

Jacek Pawełczyk

An effective sigma model describing behavior of the 3d rigid string with a $\theta$-term at $\theta=\pi$ is proposed. It contains non-perturbative corrections resulting from summation over different genera of the 2d surfaces. The effective theory is the SU(2) WZW model coupled to the Nambu-Goto action. RG analysis shows the existence of a IR fixed point at w

V. G. Gurzadyan, A. A. Kocharyan

As was shown before (Gurzadyan and Kocharyan, 1992, 1993ab) the statistical properties (exponential mixing) of motion of CMB photon beams in Friedmann Universe with negative curvature can have definite observable consequences including the decrease of the CMB anisotropy amplitude after the last scattering, distortion of images on CMB sky maps. Here we consid

V. A. Kudryavtsev

In the paper the nilpotent conditions of BRST operator for new superconformal string model were found. This string includes anticommutation $2-d$ fields additional to the standard Neveu-Schwarz superconformal set which carry quark quantum numbers. In this case the superconformal symmetry is realized by a non-linear way. In the superconformal composite string

V. V. Kiselev, A. K. Likhoded, M. V. Shevlyagin

The cross-section for the production of $b{\bar b} c{\bar c}$ quarks in $e^+e^-$ annihilation, that proves to be at a level of $\sigma (e^+e^- \rightarrow b{\bar b} c{\bar c})/ \sigma (e^+e^- \rightarrow b{\bar b}) \sim 10^{-2}$ for ${\sqrt s}=M_Z$ is calculated within the frames of the QCD perturbation theory. The cross sections for the associated productio

D. V. Khveshchenko

Applying the transformation of fermion operators to new fermion quasiparticles introduced by Halperin, Lee, and Read we estimate a scaling behavior of the ground state energy and quasiparticle gaps as a function of filling fraction for a "principal sequence" of FQHE $\nu={N\over{2N\pm 1}}$ states converging towards the gapless state at half filling. The expo

C. Chryssomalakos, Peter Schupp, Bruno Zumino

The non-commutative differential calculus on quantum groups can be extended by introducing, in analogy with the classical case, inner product operators and Lie derivatives. For the case of $\GL$ we show how this extended calculus induces by coaction a similar extended calculus, covariant under $\GL$, on the quantum plane. In this way, inner product operators

C. Bruder, Rosario Fazio, Gerd Schön

Charging effects in mesoscopic junctions suppress the tunneling of electrons. In normal metal - superconductor systems they also suppress the proximity effect, thereby revealing the nature of the microscopic processes and of the ground state of the system. The effect can be made visible since the charging and proximity effect and hence the transport properti

D. Atwood, A. Soni

We consider CP violating effects in decays of the type $B\rightarrow k_i\gamma \rightarrow K\pi\gamma$, $K^*\pi\gamma$ and $K\rho\gamma$, where $k_i$ represents a strange meson resonance. We include in our calculations five of the low-lying resonances with quantum numbers ($J^P$) $1^-$, $1^+$ and $2^+$. At the quark level these decays are driven by the pengu

F. V. Kusmartsev, J. F. Weisz, R. Kishore, Minoru Takahashi

The influence of the interaction between electrons on the Aharonov-Bohm effect is investigated in the framework of the Hubbard model. The repulsion between electrons associated with strong correlation is compared with the case of attraction such as $U$-center pairing. The most interesting case, when two electrons are located on a ring, is investigated in det

S. Emery, O. Piguet

The field equations of the Chern-Simons theory quantized in the axial gauge are shown to be completely determined by supersymmetry Ward identities which express the invariance of the theory under the topological supersymmetry of Delduc, Gieres and Sorella together with the usual Slavnov identity without requiring any action principle.

S. A. Grossman, M. A. Nowak

Possibly the only unambiguous verification that gamma-ray bursts (GRBs) are at cosmological distances would be the observation of multiple images of a gravitationally lensed burst. Each images would arrive at a different time, but exhibit identical light curves. We improve upon previous calculations of GRB lensing by using revised cosmological burst models b

Martin J. Savage

The magnetic moment of the $\Lambda_c$, $\Xi_{c1}^+$ and $\Xi_{c1}^0$ vanish when the charm quark mass is taken to infinity because the light degrees of freedom are in a spin zero configuration. The heavy quark spin-symmetry violating contribution from the light degrees of freedom starts at order $1/m_c$, the same order as the contribution from the heavy cha

M. A. Nowak, S. A. Grossman

A gravitationally lensed gamma-ray burst (GRB) would appear as multiple bursts with identical light curves, separated in time and differing only by the scaling of their amplitudes. However, noise may make them difficult to identify as lensed images. Furthermore, faint, intrinsically similar, yet distinct light curves may be falsely identified as lensing even

C. Adami

We suggest that ensembles of self-replicating entities such as biological systems naturally evolve into a self-organized critical state in which fluctuations, as well as waiting-times between phase transitions are distributed according to a 1/f power law. We demonstrate these concepts by analyzing a population of self-replicating strings (segments of compute

Chris Adami

We describe and investigate the learning capablities displayed by a population of self-replicating segments of computer-code subject to random mutation: the tierra environment. We find that learning is achieved through phase transitions that adapt the population to whichever environment it encounters, with a learning rate characterized by the environmental v

P. Chiappetta, P. Colangelo, P. De Felice, G. Nardulli

We show that neural network classifiers can be used to discriminate Higgs production from background at LHC for $ 150< M_H<200$ GeV. The results compare favourably with ordinary multivariate analysis.

Thomas E. Clark, Tonnis A. ter Veldhuis

A non-linear sigma model effective lagrangian is analyzed for theories in which supersymmetry is softly broken at scales below the electroweak symmetry breaking scale. Besides the gauge and matter supermultiplets, the low energy theory contains only three Goldstone chiral multiplets. The higgsino, gaugino as well as the charged and neutral Higgs bosons have

A. Giveon, M. Porrati, E. Rabinovici

A review article submitted to Physics Report: Target space duality and discrete symmetries in string theory are reviewed in different settings.

H. J. Weber

Deep inelastic structure functions for the nucleon are obtained in a constituent quark model on the light cone. Parton model formulas are derived. The negative slope of $F_{2}^{n}/F_{2}^{p} requires attraction between scalar quark pairs. Color magnetism leads to a positive slope. 6 Figures are available from author. Typeset in REVTEX.

Ashok Das

We construct a class of quantum mechanical theories which are invariant under fermionic transformations similar to supersymmetry transformations. The generators of the transformations in this case, however, satisfy a BRST-like algebra.

She-Sheng Xue, Giuliano Preparata

In the framework of the recently proposed electroweak theory on a Planck lattice, we are able to solve approximately the lattice Dyson equation for the fermion self-energy functions and show that the large difference of charged lepton and neutrino masses is caused by their very different gauge couplings. The predicted mass ratio ($10^{-5}\sim 10^{-6}$) betwe

Ulf H. Danielsson

In this paper the $c=1$ string theory is studied from the point of view of topological field theories. Calculations are done for arbitrary genus. A change in the prescription is proposed, which reproduces the results of the $1/x^2$ deformed matrix model. It is proposed that the deformed matrix model is related to a D-series Landau-Ginzburg superpotential.

J. Ambjorn, B. Durhuus, T. Jonsson

We consider a model of discretized 2d gravity interacting with Ising spins where phase boundaries are restricted to have minimal length and show analytically that the critical exponent $\gamma= 1/3$ at the spin transition point. The model captures the numerically observed behavior of standard multiple Ising spins coupled to 2d gravity.

N. A. Papadopoulos, J. Plass, F. Scheck

Alain Connes' construction of the standard model is based on a generalized Dirac-Yukawa operator and the K-cycle $(\HD ,D)$, with $\HD$ a fermionic Hilbert space. If this construction is reformulated at the level of the differential algebra then a direct comparison with the alternative approach by the Marseille-Mainz group becomes possible. We do this for th

Werner Kerler, Peter Rehberg

The cluster algorithm in the fully frustrated Ising model on the square lattice is essentially different from the ones used in other systems. Thus its better understanding is particularly important for finding new lines of development. Therefore we investigate it in detail. In our simulations of high statistics more appropriate choices of the probability for

H. A. Kastrup, T. Thiemann

It is shown - in Ashtekar's canonical framework of General Relativity - that spherically symmetric (Schwarzschild) gravity in 4 dimensional space-time constitutes a finite dimensional completely integrable system. Canonically conjugate observables for asymptotically flat space-times are masses as action variables and - surprisingly - time variables as angle

Zenrō Hioki

Based on recent $W$-mass measurements, the electroweak theory is tested at non-trivial quantum correction level, i.e., beyond the Born approximation with $\alpha(M_Z)$ instead of $\alpha$. We can conclude that some non-Born type corrections must exist at more than 92 % confidence level, and the non-decoupling top-quark corrections are required at 97 % confid

V. Azcoiti, G. Di Carlo, A. Galante, A. F. Grillo

The Microcanonical Fermionic Average method has been used so far in the context of lattice models with phase transitions at finite coupling. To test its applicability to Asymptotically Free theories, we have implemented it in QED$_2$, \it i.e.\rm the Schwinger Model. We exploit the possibility, intrinsic to this method, of studying the whole $\beta, m$ plane

V. V. Kiselev

Sum rules for exclusive production of heavy meson pairs in $e^+e^-$ annihilation are used to evaluate the $\Upsilon(4S) \to B \bar B$ and $\psi(3770) \to D \bar D$ decay widths. Infinitely heavy quark limit is discussed, so that scaling law for the quarkonium-meson coupling constant is derived. A value of the $B\bar B$ pair contribution into the leptonic con

V. A. Novikov, L. B. Okun, A. N. Rozanov, M. I. Vysotsky

A set of equations representing the $W/Z$ mass ratio and various observables of $Z$ decays in terms of $\bar\alpha \equiv\alpha (m_Z)$, $G_{\mu}$, $m_Z$, $m_t$, $m_H$, $\bar\alpha_{s} \equiv\alpha_{s} (m_Z)$, $m_b$ and $m_\tau$ (all other fermion masses being neglected) are compared with the latest data of the four LEP detectors, which at the level of one st

Miao Li, Chung-I Tan

High energy scattering in 2+1 QCD is studied using the recent approach of Verlinde and Verlinde. We calculate the color singlet part of the quark-quark scattering exactly within this approach, and discuss some physical implication of this result. We also demonstrate, by two independent methods, that reggeization fails for the color singlet channel. We briefl

Julie D. Blum

A supersymmetric collective coordinate expansion of the monopole solution of $N=4$ Yang-Mills theory is performed resulting in an $N=4$ supersymmetric quantum mechanics on the moduli space of monopole solutions.

Abdellatif Abada

By using the product ansatz as an approximation for the two-baryon system we investigate the isoscalar nucleon-nucleon spin-orbit potential in an extended Skyrme model including both fourth- and sixth-order terms. As it is the case for the Skyrme model, we still obtain the wrong sign for this interaction. Nevertheless, concerning the order of magnitude, the

A. Mishra, H. Mishra, P. K. Panda, S. P. Misra

We consider here quark matter equation of state including strange quarks and taking into account a nontrivial vacuum structure for QCD with gluon condensates. The parameters of condendsate function are determined from minimisation of the thermodynamic potential. The scale parameter of the gluon condensates is fixed from the SVZ parameter in the context of QC

L. S. Borkowski, P. J. Hirschfeld

We present a self-consistent theory of superconductors in the presence of Kondo impurities, using large-$N$ slave-boson methods to treat the impurity dynamics. The technique is tested on the s-wave case and shown to give good results compared to other methods for $T_K > T_c$. We calculate low temperature thermodynamic and transport properties for various sup

Kyung-Hyun Cho, Chaiho Rim

We present the anyon equation on a cylinder and in an infinite potential wall from the abelian Chern-Simons theory coupled to non-relativistic matter field by obtaining the effective hamiltonian through the canonical transformation method used for the theory on a plane and on a torus. We also give the periodic property of the theory on the cylinder.

Hao Li, Thomas C. Halsey, Alexander Lobkovsky

Beyond a threshold, electric or magnetic fields cause a dielectric or ferromagnetic fluid drop respectively to develop conical tips. We analyze the appearance of the conical tips and the associated shape transition of the drop using a local force balance as well as a global energy argument. We find that a conical interface is possible only when the dielectri