December 1994 arXiv papers — page 4

Takeshi Nihei, Jiro Arafune

We calculate the two loop long range effect on the proton decay effective Lagrangian. Numerical calculation for suppression factor gives $ A_L($2-loop$) = 0.321$ for the value of the strong coupling constant $ α_s(m_Z) = 0.116 $. Two loop effect to more general effective Lagrangian is also given.

T. Csorgo

The rapidity dependence of the low-$p_t$ enhancement is shown to be a sensitive measure of the longitudinal source size for longitudinally expanding finite systems.

Igor V. Arsenin

We discuss the hardware design choices made in our 16K-node 0.8 Teraflops supercomputer project, a machine architecture optimized for full QCD calculations. The efficiency of the conjugate gradient algorithm in terms of balance of floating-point operations, memory handling and utilization, and communication overhead is addressed. We also discuss the technolo

G. Martinelli, C. Pittori, C. T. Sachrajda, M. Testa

We propose a general renormalization method, which avoids completely the use of lattice perturbation theory. We present the results from its numerical applications to two-fermion operators on a $16^3 \times 32$ lattice, at $β=6.0$.

K. Farakos, K. Kajantie, K. Rummukainen, M. Shaposhnikov

We discuss a framework relying on both perturbative and non-perturbative lattice computations which will be able to reliably determine the parameters of the EW phase transition. A motivation for the use of 3d effective theory in the lattice simulations, rather than the complete 4d one, is provided. We introduce and compute on the 2-loop level a number of gau

P. Rossi, E. Vicari

An explicit solution is found for the most general independent correlation functions in lattice QCD$_2$ with Wilson action. The large-$N$ limit of these correlations may be used to reconstruct the eigenvalue distributions of Wilson loop operators for arbitrary loops. Properties of these spectral densities are discussed in the region $β<β_c={1\over 2}$.

Harald H. Soleng

An exact solution of Einstein&#39;s field equations for a point mass surrounded by a static, spherically symmetric fluid of strings is presented. The solution is singular at the origin. Near the string cloud limit there is a $1/r$ correction to Newton&#39;s force law. It is noted that at large distances and small accelerations, this law coincides with the ph

H. Dehnen, E. Hitzer

We propose a Lorentz-covariant Yang-Mills ``spin-gauge&#39;&#39; theory, where the function valued Pauli matrices play the role of a non-scalar Higgs-field. As symmetry group we choose $SU(2) \times U(1)$ of the 2-spinors describing particle/antiparticle states. After symmetry breaking a non-scalar Lorentz-covariant Higgs-field gravity appears, which can be

Erik Sorensen, Ian Affleck

The $s=1$ Heisenberg Antiferromagnet is studied in the presence of two kinds of local impurities. First, a perturbed antiferromagnetic bond with $J&#39;\ne J$ at the center of an even-length open chain is considered. Using the density matrix renormalization group method we find that, for sufficiently strong or weak $J&#39;$, a bound state is localized at the

Eberhard O. Tüngler, Thilo Kopp

We discuss problems of functional integral formalisms in a constrained fermionic Fock space. A functional integral is set up for the Hubbard model using generalized coherent states which lie either in the constrained or in the full Fock space. The projection for the latter states is implemented through a reduction of the charge fluctuations which induce tran

Robert A. Pelcovits, Robert B. Meyer

We consider theoretically the properties of piezoelectricity in cholesteric elastomers. We deduce using symmetry considerations the piezoelectric contributions to the free energy in the context of a coarse-grained description of the material. In contrast to previous work we find that compressions or elongations of the material along the pitch axis do not pro

Eugene Kogan, Moshe Kaveh

The distribution function for the intensity of radiation propagating in a random medium is analyzed for arbitrary multiplicity of scattering (for arbitrary relation between the distance of propagation and mean free path), including as limiting cases purely ballistic and purely diffusive regimes. The calculation is fulfilled in the framework of diagram techni

R. Preuss, W. von der Linden, W. Hanke

On the basis of Quantum-Monte-Carlo results the evolution of the spectral weight $A(\vec k, ω)$ of the two-dimensional Hubbard model is studied from insulating to metallic behavior. As observed in recent photoemission experiments for cuprates, the electronic excitations display essentially doping-independent features: a quasiparticle-like dispersive narrow b

G. Hackenbroich, H. A. Weidenmueller

We study random-matrix ensembles with a non-Gaussian probability distribution $P(H) \sim \exp (-N {\rm tr }\, V(H))$ where $N$ is the dimension of the matrix $H$ and $V(H)$ is independent of $N$. Using Efetov&#39;s supersymmetry formalism, we show that in the limit $N \rightarrow \infty$ both energy level correlation functions and correlation functions of $S

Antimo Angelucci

We present an exact, unconstrained representation of the electron operators in terms of operators of opposite statistics. We propose a path--integral representation for the $t$-$J$ model and introduce a parameter controlling the semiclassical behaviour. We extend the functional approach to the Hubbard model and show that the mean--field theory is equivalent

Karl B. Fisher

The relation between the galaxy correlation function in real and redshift-space is derived in the linear regime by an appropriate averaging of the joint probability distribution of density and velocity. The derivation recovers the familiar linear theory result on large scales but has the advantage of clearly revealing the dependence of the redshift distortio

James E. Gunn, David H. Weinberg

We summarize the plans for and the current status of the Sloan Digital Sky Survey, a digital imaging and spectroscopic survey of $π$ steradians in the northern Galactic cap. The CCD photometric survey will produce images in five bands to limiting magnitudes of order 23. The spectroscopic survey will obtain redshifts of $10^6$ galaxies (a complete sample to a

Mark Hindmarsh

Some aspects of the theory of cosmological perturbations from cosmic strings and other topological defects are outlined, with particular reference to a simple example: a spatially flat CDM-dominated universe. The conserved energy-momentum pseudo-tensor is introduced, and the equation for the density perturbation derived from it. It is shown how the scaling h

Steinn Sigurdsson, E. S. Phinney

We model the dynamics of test binaries in isotropic, multi-mass models of galactic globular clusters. The evolution of binary orbits through the cluster potentials is modeled, including second order diffusion terms, and probabilities for close encounters with field stars are calculated. We carry out Monte Carlo simulations of the effects of the binary--singl

Jens Hjorth, Jes Madsen

The light profiles of elliptical (E) galaxies are known to display small systematic deviations (0.1-0.2 mag.) from the R^1/4 law. In this paper we show that the senses and amplitudes of these departures can be naturally accounted for by a simple distribution function constructed on the basis of statistical mechanics of violent relaxation. As a consequence, d

T. Buchert, A. L. Melott, A. G. Weiss

Approximations to the exact solutions for gravitational instability in the expanding Universe are extremely useful for understanding the evolution of large--scale structure. We report on a series of tests of Newtonian Lagrangian perturbation schemes using N--body simulations for various power--spectra with scale--independent indices in the range $-3$ to $+1$

Jens Hjorth, Frank Grundahl, Kari Nilsson, Leif Festin

The large-redshift (z=3.8) quasar 1208+1011 has recently been discovered to be a gravitational lens candidate with a separation of 0.47&#34; between the two imaged components (A and B). NOT (Nordic Optical Telescope) and HST (Hubble Space Telescope) studies from 1992 probing primarily the continuum light show that the amplification of A relative to B is almo

Paolo Padovani, Paolo Giommi

We explain the properties of X-ray selected BL Lacertae objects, under the assumption that they constitute the small minority of the BL Lac population with energy cutoff located in the UV/X-ray band, as suggested by their multifrequency spectra. In particular, we derive their X-ray luminosity function, log N-log S, and radio flux distribution starting from r

Y. P. Jing, H. J. Mo, G. Boerner, L. Z. Fang

In this paper we investigate, using high resolution N-body simulations, the density profiles and the morphologies of galaxy clusters in seven models of structure formation. We show that these properties of clusters are closely related to the occurrence of a significant merging event in the recent past. The seven models are: (1) the standard CDM model (SCDM)

A. Lecavelier des Etangs, M. Deleuil, A. Vidal-Madjar et al

We have analyzed Beta Pictoris photometric measurements obtained from La Silla by the Geneva Observatory from 1975 to 1992. These data show evidence of variations in the brightness of the star, with no color dependency. Here, we demonstrate that the light variations are present on long as well as on short time scales. On a long time scale, we show that the a

V. Pascalutsa

Lagrangian of a massive particle with spin 3/2 is considered in the Rarita-Schwinger formalism. We discuss implications of the contact- and the gauge-transformation on the physical content of free and interacting theories. It is shown that the ``contact-invariance&#39;&#39; is trivial and has no physical relevance. The requirement of the gauge-invariance of

J. Gomis, J. M. Pons, F. Zamora

Reducible off-shell anomalous gauge theories are studied in the framework of an extended Field-Antifield formalism by introducing new variables associated with the anomalous gauge degrees of freedom. The Wess-Zumino term for these theories is constructed and new gauge invariances appear. The quantum effects due to the extra variables are considered.

Jay Watson

It is shown how the S-matrix pinch technique may be extended to the cases of external scalar and gauge boson fields. Using this extension, the universality of the pinch technique gauge-independent one-loop gauge boson self-energy in a general unbroken SU($N$) gauge theory is demonstrated explicitly.

C. Glenn Boyd, Benjamin Grinstein, Richard F. Lebed

We use rigorous QCD dispersion relations to derive model-independent bounds on the B -> pi l nu, D -> pi l nu and D -> K l nu form factors. These bounds are particularly restrictive when the value of the observable form factor at one or more kinematic points is assumed. With reasonable assumptions we find f_B < 195 MeV and that the shape of the form factor b

Erik A. Martinez

The microcanonical functional integral for an eternal black hole system is considered. This requires computing the microcanonical action for a spatially bounded spacetime region when its two disconnected timelike boundary surfaces are located in different wedges of the Kruskal diagram. The path integral is a sum over Lorentzian geometries and is evaluated se

Stephen J. Montgomery-Smith

Orlicz-Lorentz spaces provide a common generalization of Orlicz spaces and Lorentz spaces. In this paper, we investigate their Boyd indices. Bounds on the Boyd indices in terms of the Matuszewska-Orlicz indices of the defining functions are given. Also, we give an example to show that the Boyd indices and Zippin indices of an Orlicz-Lorentz space need not be

Stephen J. Montgomery-Smith

We give necessary and sufficient conditions for the Hardy operator to be bounded on a rearrangement invariant quasi-Banach space in terms of its Boyd indices.

L. Grafakos, Stephen J. Montgomery-Smith

We precisely evaluate the operator norm of the uncentered Hardy-Littlewood maximal function on $L^p(\Bbb R^1)$. We also compute the operator norm of the uncentered Hardy-Littlewood maximal function over rectangles on $L^p(\Bbb R^n)$, and we show that the operator norm of the uncentered Hardy-Littlewood maximal function over balls on $L^p(\Bbb R^n)$ grows exp

Heinz-Dieter Conradi

The Wheeler-DeWitt equation for a class of Kantowski-Sachs like models is completely solved. The generalized models include the Kantowski-Sachs model with cosmological constant and pressureless dust. Likewise contained is a joined model which consists of a Kantowski-Sachs cylinder inserted between two FRW half--spheres. The (second order) WKB approximation i

A. Kempf, G. Mangano, R. B. Mann

The existence of a minimal observable length has long been suggested, in quantum gravity, as well as in string theory. In this context a generalized uncertainty relation has been derived which quantum theoretically describes the minimal length as a minimal uncertainty in position measurements. Here we study in full detail the quantum mechanical structure whi

M. R. Niedermaier

An associative $*$-algebra is introduced (containing a $TTR$-algebra as a subalgebra) that implements the form factor axioms, and hence indirectly the Wightman axioms, in the following sense: Each $T$-invariant linear functional over the algebra automatically satisfies all the form factor axioms. It is argued that this answers the question (posed in the func

Mico Durdevic

A noncommutative-geometric generalization of the classical concept of spinor structure is presented. This is done in the framework of the formalism of quantum principal bundles. In particular, analogs of the Dirac operator and the Laplacian are introduced and analyzed. A general construction of examples of quantum spaces with a spinor structure is presented.

Mico Durdevic

A general noncommutative-geometric theory of principal bundles is presented. Quantum groups play the role of structure groups. General quantum spaces play the role of base manifolds. A differential calculus on quantum principal bundles is studied. In particular, algebras of horizontal and verticalized differential forms on the bundle are introduced and inves

Mico Durdevic

A constructive approach to differential calculus on quantum principal bundles is presented. The calculus on the bundle is built in an intrinsic manner, starting from given graded (differential) *-algebras representing horizontal forms on the bundle and differential forms on the base manifold, together with a family of antiderivations acting on horizontal for

Mico Durdevic

A braided generalization of the concept of Hopf algebra (quantum group) is presented. The generalization overcomes an inherent geometrical inhomogeneity of quantum groups, in the sense of allowing completely pointless objects. All braid-type equations appear as a consequence of initial axioms. Braided counterparts of basic algebraic relations between fundame

Mico Durdevic, Zbigniew Oziewicz

General braided counterparts of classical Clifford algebras are introduced and investigated. Braided Clifford algebras are defined as Chevalley-Kahler deformations of the corresponding braided exterior algebras. Analogs of the spinor representations are studied, generalizing classical Cartan&#39;s approach. It is shown that, under certain assumptions concern

Ralf A. Engeldinger

Twisted tensor powers of quasitriangular Hopf algebras with diagonal sub-Hopf-algebras (self-diagonal tensor powers) are introduced together with their duals and their mutual *-structures as generalizations of the Drinfel&#39;d double as given by Reshetikhin and Semenov-Tian-Shansky. R-Matrices for tensor products of representations are derived.

Alan J. Sommerer, A. Abd El-Hady, John R. Spence, James P. Vary

We extend our earlier model of $q\bar q$ mesons using relativistic quasipotential (QP) wave equations to include open-flavor states and running quark-gluon coupling effects. Global fits to meson spectra are achieved with rms deviations from experiment of 43-50 MeV. We examine in-medium effects through their influence on the confining interaction and predict

V. V. Flambaum, V. G. Zelevinsky

A nucleus with octupole deformation of the mean field reveals rotational doublets with the same angular momentum and opposite parity. Mediated by the Coriolis-type interaction, the doublet structure leads to a strong regular component in the parity violation caused by weak interaction. This can explain sign correlations observed in polarized neutron scatteri

William B. Johnson, M. Zippin

It is proved that every operator from a weak$^*$-closed subspace of $\ell_1$ into a space $C(K)$ of continuous functions on a compact Hausdorff space $K$ can be extended to an operator from $\ell_1$ to $C(K)$.

P. K. Lin

For any complex Banach space $X$, let $J$ denote the duality mapping of $X$. For any unit vector $x$ in $X$ and any ($C_0$) contraction semigroup $(T_t)_{t>0}$ on $X$, Baillon and Guerre-Delabriere proved that if $X$ is a smooth reflexive Banach space and if there is $x^* \in J(x)$ such that $|\langle T(t) \, x,J(x)\rangle| \to 1 $ as $t \to \infty$, then th

Kevin M. Pilgrim

We prove: If $f(z)$ is a critically finite rational map which has exactly two critical points and which is not conjugate to a polynomial, then the boundary of every Fatou component of $f$ is a Jordan curve. If $f(z)$ is a hyperbolic critically finite rational map all of whose postcritical points are periodic, then there exists a cycle of Fatou components who

P. Demkin

Stability of some solutions of the equations of motion of bosonic p-branes in curved and flat spacetimes is stated.

F. W. Nijhoff, O. Ragnisco, V. B. Kuznetsov

An exactly integrable symplectic correspondence is derived which in a continuum limit leads to the equations of motion of the relativistic generalization of the Calogero-Moser system, that was introduced for the first time by Ruijsenaars and Schneider. For the discrete-time model the equations of motion take the form of Bethe Ansatz equations for the inhomog

K. S. Stelle

We review the origin of anomaly-induced dynamics in theories of $d=2$ gravity from a BRST viewpoint and show how quantum canonical transformations may be used to solve the resulting Liouville or Toda models for the anomalous modes.

S. Randjbar-Daemi, J. Strathdee

The overlap formula proposed by Narayanan and Neuberger in chiral gauge theories is examined. The free chiral and Dirac Green&#39;s functions are constructed in this formalism. Four dimensional anomalies are calculated and the usual anomaly cancellation for one standard family of quarks and leptons is verified.

S. A. Frolov, A. A. Slavnov, C. Sochichiu

A consistent quantization procedure of anomalous chiral models is discussed. It is based on the modification of the classical action by adding Wess-Zumino terms. The $SO(3)$ invariant WZ action for the $SO(3)$ model is constructed. Quantization of the corresponding modified theory is considered in details.

E. Sezgin, Y. Tanii

Rigidly superconformal sigma models in higher than two dimensions are constructed. These models rely on the existence of conformal Killing spinors on the $p+1$ dimensional worldvolume $(p\le 5)$, and homothetic conformal Killing vectors in the $d$--dimensional target space. In the bosonic case, substituting into the action a particular form of the target spa

Klaus Behrndt

The chiral null model is a generalization of the fundamental string and gravitational wave background. It is an example of a conformally invariant model in all orders in $α&#39;$ and has unbroken supersymmetries. In a Kaluza--Klein approach we start in 10 dimensions and reduce the model down to 4 dimensions without making any restrictions. The 4-D field cont

D. V. Fursaev

Attention is paid to the fact that temperature of a classical black hole can be derived from the extremality condition of its free energy with respect to variation of the mass of a hole. For a quantum Schwarzschild black hole evaporating massless particles the same condition is shown to result in the following one-loop temperature $T=(8\pi M)^{-1} (1+\sigma

Carlos Castro

Exact instanton solutions to $D=11$ spherical supermembranes moving in flat target spacetime backgrounds are construted. Our starting point is Super Yang-Mills theories, based on the infinite dimensional $SU(\infty)$ group, dimensionally reduced to one time dimension. In this fashion the super-Toda molecule equation is recovered preserving only one supersymm

Steven B. Giddings

Unitarity and locality imply a remnant solution to the information problem, and also imply that Reissner-Nordstrom black holes have infinite numbers of internal states. Pair production of such black holes is reexamined including the contribution of these states. It is argued that the rate is proportional to the thermodynamic quantity Tr e^{-beta H}, where th

Kimball A. Milton

In this letter it will be demonstrated explicitly that the finite-element formulation of quantum electrodynamics is free from fermion doubling. We do this by (1) examining the lattice fermion propagator and using it to compute the one-loop vacuum polarization on the lattice, and (2) by an explict computation of vector and axial-vector current anomalies for a

V. L. Eletsky

Correlation functions of QCD currents with quantum numbers of nucleon and $Δ$-isobar are considered at finite temperatures. Corrections of order $T^4$ to the correlators are calculated and interpreted in terms of thermal mass shifts using a QCD sum rules type of argument. In both cases the masses decrease with $T$.

M. J. Herrero, E. Ruiz Morales

Using effective field theory methods, we integrate out the standard model Higgs boson to one loop and represent its non-decoupling effects by a set of gauge invariant effective operators of the electroweak chiral Lagrangian. We briefly discuss the relation between the renormalization of both the standard model and the effective theory, which is crucial for a

Jes Madsen

After a brief introduction to the physics of bulk strange quark matter (SQM) this review focuses on the properties of low baryon number strangelets presently searched for in ultra-relativistic heavy-ion experiments at CERN and Brookhaven. Shell-model calculations reveal interesting (meta)stability properties in the experimentally accessible regime. A liquid

N. E. Ligterink, B. L. G. Bakker

In this paper we discuss the relation between the standard covariant quantum field theory and light-front field theory. We define covariant theory by its Feynman diagrams, whereas light-front field theory is defined in terms of light-cone time-ordered diagrams. A general algorithm is proposed that produces the latter from any Feynman diagram. The procedure i

Michael Engelhardt

QCD in 1+1 dimensions is examined in the limit of a large number of colors and flavors. The Hamiltonian matrix is given in a Fock space spanned by &#39;t Hooft meson states and, for the case of zero fermion mass, a submatrix is diagonalized numerically to give the low-lying spectrum as a function of $N_F /N_C $. Pair creation effects generate bound states wh

C. Alexandrou, A. Borrelli, S. Guesken, F. Jegerlehner

We present lattice estimates of the mass of the heavy-light baryons $Λ_b$ and $Ξ_b$ obtained using propagating heavy quarks. For $Λ_b$ our result is $M_{Λ_b}=5.728 \pm 0.144 \pm 0.018$ GeV, after extrapolation to the continuum limit and in the quenched approximation.

David Henty, Richard Kenway, Brian Pendleton, Jon Ivar Skullerud

Using chiral Ward identities, we determine the renormalisation constants of bilinear quark operators for the Sheikholeslami-Wohlert action lattice at beta=6.2. The results are obtained with a high degree of accuracy. For the vector current renormalisation constant we obtain Z_V=0.817(2)(8), where the first error is statistical and the second is due to mass d

C. Michael, A. McKerrell

We discuss fitting hadronic Green functions versus time $t$ to extract mass values in quenched lattice QCD. These data are themselves strongly correlated in $t$. With only a limited number of data samples, the method of minimising correlated $χ^2$ is unreliable. We explore several methods of modelling the correlations among the data set by a few parameters w

E. Nakano

We have measured, with electron tagging, the forward-backward asymmetries of charm- and bottom-quark pair productions at $<\sqrt{s} >$=58.01GeV, based on 23,783 hadronic events selected from a data sample of 197pb$^{-1}$ taken with the TOPAZ detector at TRISTAN. The measured forward-backward asymmetries are $A_{FB}^c = -0.49 \pm 0.20(stat.) \pm 0.08 (sys.)$

B. Linet

We determine generally the spinor Green&#39;s function and the twisted spinor Green&#39;s function in an Euclidean space with a conical-type line singularity. In particular, in the neighbourhood of the point source, we expree them as a sum of the usual Euclidean spinor Green&#39;s functin and a regular term. In four dimensions, we use these determinations to

Briscoe, Ted, Waegner, Nick

The paper describes a parser of sequences of (English) part-of-speech labels which utilises a probabilistic grammar trained using the inside-outside algorithm. The initial (meta)grammar is defined by a linguist and further rules compatible with metagrammatical constraints are automatically generated. During training, rules with very low probability are rejec

Rosemary F. G. Wyse

Invited Review at IAU Symp 164 on Stellar Populations. The Milky Way Galaxy offers a unique opportunity for testing theories of galaxy formation and evolution. The study of the spatial distribution, kinematics and chemical abundances of stars in the Milky Way Galaxy allows one to address specific questions pertinent to this meeting such as When was the Galax

Chung-Pei Ma

We report the most recent results from high-resolution numerical simulations of structure formation in two flat cold+hot dark matter models with neutrino mass densities $\onu=0.2$ and 0.3. We find that structure forms too late in all CDM+HDM models with $\onu>0.2$ to account for the amount of dense neutral gas in high-redshift damped Lyman-$α$ systems. The $

E. E. Qian, P. T. de Zeeuw, R. P. van der Marel, C. Hunter

The contour integral method of Hunter & Qian is applied to axisymmetric galaxy models in which the distribution function (DF) is of the form f=f(E,L_z), where E and L_z are the classical integrals of motion in an axisymmetric potential. A practical way to construct the unique even part of the DF for such systems is presented. It is applied to models, both ob

T. Buchert

The problem of formation of generic structures in the Universe is addressed, whereby first the kinematics of inertial continua for coherent initial data is considered. The generalization to self--gravitating continua is outlined focused on the classification problem of singularities and metamorphoses arising in the density field. Self--gravity gives rise to

R. Fabbri, V. Natale

We investigate the existence and meaning of a preferred length in the large-scale distribution of 60-micron IRAS sources applying three tests to the 2-dimensional distribution on the celestial sphere, involving respectively the rms fluctuation and the correlation function of the source number density, and the peak number statistics. For HDM models we find a

G. K. Sankaran

The toroidal compactification of the moduli space of complex abelian surfaces with a polarisation of type (1,p), p a prime, is of general type if p is at least 173. Happy Christmas.

Max Tegmark

A method for extracting maximal resolution power spectra from microwave sky maps is presented and applied to the 2 year COBE data, yielding a power spectrum that is consistent with a standard n=1, Q=20 micro-Kelvin model. By using weight functions that fall off smoothly near the galactic cut, it is found that the spectral resolution Δl can be more than doubl

A. Klemm, W. Lerche, S. Theisen, S. Yankielowicz

We review the generalization of the work of Seiberg and Witten on N=2 supersymmetric SU(2) Yang-Mills theory to SU(n) gauge groups. The quantum moduli spaces of the effective low energy theory parametrize a special family of hyperelliptic genus n-1 Riemann surfaces. We discuss the massless spectrum and the monodromies.

I. Ya. Aref&#39;eva, K. S. Viswanathan, I. V. Volovich

In a series of papers Amati, Ciafaloni and Veneziano and &#39;t Hooft conjectured that black holes occur in the collision of two light particles at planckian energies. In this paper we discuss a possible scenario for such a process by using the Chandrasekhar-Ferrari-Xanthopoulos duality between the Kerr black hole solution and colliding plane gravitational w

S. Graffi, V. R. Manfredi, L. Salasnich

In order to highlight the onset of chaos in the Pullen-Edmonds model a quantal analog of the resonance overlap criterion has been examined. A quite good agreement between analytical and numerical results is obtained.

I. Ya. Aref&#39;eva, I. V. Volovich

Recently E.Verlinde and H.Verlinde have suggested an effective two-dimensional theory describing the high-energy scattering in QCD. In this report we attempt to clarify some issues of this suggestion. We consider {\it anisotropic asymptotics} of correlation functions for scalar and gauge theories in four dimensions. Anisotropic asymptotics describe behaviour

Ezer Melzer

The Gordon-Andrews identities, which generalize the Rogers-Ramanujan-Schur identities, provide product and fermionic forms for the characters of the minimal conformal field theories (CFTs) M(2,2k+1). We discuss/conjecture identities of a similar type, providing two different fermionic forms for the characters of the models SM(2,4k) in the minimal series of N

P. Hajicek, A. Higuchi, J. Tolar

The method of group quantization described in the preceeding paper I is extended so that it becomes applicable to some parametrized systems that do not admit a global transversal surface. A simple completely solvable toy system is studied that admits a pair of maximal transversal surfaces intersecting all orbits. The corresponding two quantum mechanics are c

Victor V. Batyrev, Lev A. Borisov

We investigate Hodge-theoretic properties of Calabi-Yau complete intersections $V$ of $r$ semi-ample divisors in $d$-dimensional toric Fano varieties having at most Gorenstein singularities. Our main purpose is to show that the combinatorial duality proposed by second author agrees with the duality for Hodge numbers predicted by mirror symmetry. It is expect

Max Tegmark

One of the main challenges in cosmology is to quantify how small density fluctuations at the recombination epoch z around 1000 evolved into the galaxies and the large-scale structure we observe in the universe today. This thesis discusses ways of probing the intermediate epoch, focusing on the thermal history. The main emphasis is on the role played by non-l

P. Hajicek

A method of quantizing parametrized systems is developed that is based on a kind of ``gauge invariant&#39;&#39; quantities---the so-called perennials (a perennial must also be an ``integral of motion&#39;&#39;). The problem of time in its particular form (frozen time formalism, global problem of time, multiple choice problem) is met, as well as the related d

Hitoshi Nishino

We present an alternative $N=(4,0)$ superstring theory, with field content different from that of previously-known $N=(4,0)$ superstring theories. This theory is presented as a non-linear $\s$-model on the coset $SU(n,1) / SU(n) \otimes U(1)$ as the target space-time with torsion, which is coupled to $N=(4,0)$ world-sheet superconformal gravity. Our result i

Wolfram Koepf

This article describes the REDUCE package ZEILBERG implemented by Gregor Stölting and the author. The REDUCE package ZEILBERG is a careful implementation of the Gosper and Zeilberger algorithms for indefinite, and definite summation of hypergeometric terms, respectively. An expression $a_k$ is called a {\sl hypergeometric term} (or {\sl closed form}), if $a_

Wolfram Koepf

The celebrated Zeilberger algorithm which finds holonomic recurrence equations for definite sums of hypergeometric terms $F(n,k)$ is extended to certain nonhypergeometric terms. An expression $F(n,k)$ is called a hypergeometric term if both $F(n+1,k)/F(n,k)$ and $F(n,k+1)/F(n,k)$ are rational functions. Typical examples are ratios of products of exponentials

Wolfram Koepf

Ich möchte in diesem Bericht algorithmische Methoden vorstellen, die im wesentlichen in diesem Jahrzehnt Einzug in die Computeralgebra gefunden haben. Die hauptsächlichen Ideen gehen auf Stanley \cite{Sta} und Zeilberger \cite{Zei1}--\cite{Zei4} zurück, vgl.\ die Beschreibung \cite{Strehl1}, und haben ihre Wurzeln teilweise bereits im letzten Jahrhundert (si

Randall Dougherty, Vance Faber

We address the degree-diameter problem for Cayley graphs of Abelian groups (Abelian graphs), both directed and undirected. The problem turns out to be closely related to the problem of finding efficient lattice coverings of Euclidean space by shapes such as octahedra and tetrahedra; we exploit this relationship in both directions. In particular, we find the

Paul Watts

The differential geometry on a Hopf algebra is constructed, by using the basic axioms of Hopf algebras and noncommutative differential geometry. The space of generalized derivations on a Hopf algebra of functions is presented via the smash product, and used to define and discuss quantum Lie algebras and their properties. The Cartan calculus of the exterior d

Mauro Anselmino

Spin effects in strong interaction high energy processes are subtle phenomena which involve both short and long distance physics and test perturbative and non perturbative aspects of QCD. Moreover, depending on quantities like interferences between different amplitudes and relative phases, spin observables always test a theory at a fundamental quantum mechan

Wolfhard Janke, Tilman Sauer

We report results of a Monte Carlo simulation of the $ϕ^4$ quantum field theory using multigrid simulation techniques and a refined discretization scheme. The resulting accuracy of our data allows for a significant test of an analytical approximation based on a variational ansatz. While the variational approximation is well reproduced for a large range of pa

Wolfhard Janke, Tilman Sauer

We discuss the recently proposed multicanonical multigrid Monte Carlo method and apply it to the scalar $ϕ^4$-model on a square lattice. To investigate the performance of the new algorithm at the field-driven first-order phase transitions between the two ordered phases we carefully analyze the autocorrelations of the Monte Carlo process. Compared with standa

Wolfgang Bock, James E. Hetrick

We examine the question of how baryogenesis can occur in lattice models of the Standard Model where there is a global $U(1)$ symmetry which is accompanied by an exactly conserved fermion number. We demonstrate that fermion creation and annihilation can occur in these models {\em despite} this exact fermion number conservation, by explicitly computing the spe

G. Sardanashvily

In classical field theory, the composite fibred manifolds Y -> Z -> X provides the adequate mathematical formulation of gauge models with broken symmetries, e.g., the gauge gravitation theory. This work is devoted to connections on composite fibred manifolds. In particular, we get the horizontal splitting of the vertical tangent bundle of a composite fibred

T. H. Yang, C. S. Wang, J. C. Huang, Y. S. Gou

The crucial formulas to determine the non-chaotic states in the rf-biased nonlinear oscillators are derived from the numerical experiments. The nature of these formulas, which depends on symmetrical properties of the potential well, in terms of the driven-frequency as a function of the damping constant k is investigated. All these ones provide crucial guide

P. Crehan

Dynamical systems can be quantised only if they are Hamiltonian. This prompts the question from which our talk gets its title. We show how the simple predator-prey equation and the damped harmonic oscillator can be considered to be Hamiltonian with respect to an infinite number of non-standard Poisson brackets. This raises some interesting questions about th

P. Crehan

We derive a canonical form for smooth vector fields on $\Re^{n+1}$. We use this to demonstrate the local multi-Hamiltonian nature of the corresponding flows. Associated with the canonical form is an inhomogenious linear PDE whose solutions provide conserved measures. These can be used to construct the local Hamiltonians.

Shaun Cole, Karl B. Fisher, David H. Weinberg

We measure the anisotropy of the redshift-space power spectrum in the 1.2-Jy and QDOT redshift surveys of IRAS-selected galaxies. On large scales, this anisotropy is caused by coherent peculiar motions, and gravitational instability theory predicts a distortion of the power spectrum that depends only on the ratio $β\equiv f(Ω)/b \approx Ω^{0.6}/b$, where Ome