December 1993 arXiv papers — page 3

Charles H. Walter

Let S be a ruled surface without sections of negative self-intersection. We classify the irreducible components of the moduli stack of torsion-free sheaves of rank 2 sheaves on S. We also classify the irreducible components of the Brill-Noether loci in Hilb^N(P1xP1) given by W_N^0(D)={[X] | h^1(I_X(D)) >= 1 } for D an effective divisor class. Our methods are

Charles H. Walter

Let E be a torsion-free sheaf on P2. We give an effective method which uses the Hilbert function of E to construct a weak version of the Harder-Narasimhan filtration of a torsion-free sheaf on P2 subject only to the condition that E be sufficiently general among sheaves with that Hilbert function. This algorithm uses on a generalization of Davis' decompo

Tanmoy Bhattacharya, Rajan Gupta

We present a status report on simulations being done on $32^3 \times 64$ lattices at $β= 6.0$ using quenched Wilson fermions. Results for the spectrum, decay constants, the kaon B-parameter $B_K$, and semi-leptonic form factors are given based on the current statistical sample of 28 configurations. These ``Grand Challenge'' calculations are being don

Hai-Yang Cheng, Chi-Yee Cheung, Guey-Lin Lin, Y. C. Lin

In previous publications we have analyzed the strong and electromagnetic decays of heavy mesons and heavy baryons in a formalism which incorporates heavy-quark and chiral symmetries. There are two possible symmetry-breaking effects on the chiral dynamics of heavy hadrons: the finite-mass effects from light quarks and the $1/ m_Q$ corrections from heavy quark

G. F. Giudice, S. Mollerach, E. Roulet

Models of our galaxy based on dynamical observations predict a spheroid component much heavier than accounted for by direct measurements of star counts and high velocity stars. If, as first suggested by Caldwell and Ostriker, this discrepancy is due to a large population of faint low-mass stars or dark objects in the spheroid, the spheroid could be responsib

She-Sheng XUE

Considering relevant and irrelevant high-dimension operators for ordinary and mirror fermions respectively, we show that the Wilson lattice fermion can originate from a spontaneous symmetry breaking phenomenon. Ward identities, due to symmetries at the cutoff, guarantee the cancellation of mirror-fermion contributions and the infrared limit can be achieved.

B. K. Agrawal, A. Ansari

Angular momentum dependence of nuclear level densities at finite temperatures are investigated in the static path approximation(SPA) to the partition function using a cranked quadrupole interaction Hamiltonian in the following three schemes: (i) cranking about x-axis, (ii) cranking about z-axis and (iii) cranking about z-axis but correcting for the orientati

J. Ambjorn, G. Thorleifsson

We investigate the fractal structure of $2d$ quantum gravity coupled to matter by measuring the distributions of so-called baby universes. We demonstrate that the method works well as long as $c \leq 1$. For $c >1$ it is not clear what distribution to expect. However, we observe strikingly similar distributions for various kinds of matter fields with the sam

O. V. Selyugin

A careful analysis of the new data of the UA4/2 collaboration reveals that these data give an essentially large value of the $ρ= Re T(s,t)/Im(s,t)$ that does not contradict the early UA4 experiment. There is the reason to think also that this experiment reveals for the first time a real possibility of the existence of the spin-flip amplitude at superhigh ene

J. Ambjorn, G. Thorleifsson

We investigate the fractal structure of $2d$ quantum gravity coupled to matter by measuring the distributions of so-called baby universes. We demonstrate that the method works well as long as $c \leq 1$. For $c >1$ it is not clear what distribution to expect. However, we observe strikingly similar distributions for various kinds of matter fields with the sam

P. B Wiegmann, A. V. Zabrodin

We present a new approach to the problem of Bloch electrons in magnetic ( sometimes called Azbel-Hofstadter problem) field, by making explicit a natural relation between the group of magnetic translations and the quantum group $U_{q}(sl_2)$. The approach allows us to express the "mid" band spectrum of the model and the Bloch wave function as solution

M. L. Plumer, A. Mailhot, A. Caillé

Histogram Monte-Carlo simulation results are presented for the magnetic-field -- temperature phase diagram of the XY model on a stacked triangular lattice with antiferromagnetic intraplane and ferromagnetic interplane interactions. Finite-size scaling results at the various transition boundaries are consistent with expectations based on symmetry arguments. A

Maria de Sousa Vieira

We investigate the nonlinear properties of a system introduced by Burridge and Knopoff to model the dynamics of earthquakes. We find that a two-block system in a completely homogeneous configuration presents a complex behavior characterized by the presence of periodic, quasiperiodic and chaotic orbits. We have found routes to chaos via two types of intermitt

S. Pellegrini, G. Fabbiano

A recent re-analysis of Einstein data, and new ROSAT observations, have revealed the presence of at least two components in the X-ray spectra of X-ray faint early-type galaxies: a relatively hard component (kT>1.5 keV), and a very soft component (kT\sim 0.2-0.3 keV). We address the problem of the nature of the very soft component, and whether it can be due t

F. A. Aharonian, P. S. Coppi, H. J. Voelk

Recent high energy gamma-ray observations (E>100 MeV) of blazar AGN show emission spectra with no clear upper energy cutoff. AGN, considered to be possible sources for the highest energy cosmic rays, may have emission extending well into the VHE (very high energy, E>100 GeV) domain. Because VHE gamma-rays are absorbed by pair production on the intergalactic

Masahiro IMACHI, Hiroshi YONEYAMA

We study the two dimensional Hubbard model by use of the ground state algorithm in the Monte Carlo simulation. We employ complex wave functions as trial function in order to have a close look at properties such as chiral spin order ($χ$SO) and flux phase. For half filling, a particle-hole transformation leads to sum rules with respect to the Green's func

I. L. Aleiner, B. I. Shklovskii

We study variable range hopping in the quantum Hall effect regime in the presence of a metallic gate parallel to the plane of a two-dimensional electron gas. Screening of the Coulomb interaction by the gate causes the partial ``filling'' of the Coulomb gap in the density of localized states. At low enough temperatures this leads to a substantial enha

A. L. Melott, T. F. Pellman, S. F. Shandarin

We have recently learned that the Zeldovich approximation can be successfully used for a far wider range of gravitational instability scenarios than formerly proposed; we study here how to extend this range. In previous work we studied the accuracy of several analytic approximations to gravitational clustering in the mildly nonlinear regime. We found that th

Kingman Cheung, Tzu Chiang Yuan

Gluons cannot directly fragment into $B_c$ mesons until at order $α_s^3$. However, the Altarelli-Parisi evolution of the $\bar b$-quark fragmentation functions $D_{\bar b \to B_c}(z)$ and $D_{\bar b \to B_c^*}(z)$ from the heavy quark mass scales up to the collider energy scale $Q$ can induce the gluon fragmentation functions $D_{g \to B_c}(z)$ and $D_{g \to

M. -C. Chu, J. Grandy, S. Huang, J. W. Negele

Cooling is used as a filter on a set of gluon fields sampling the Wilson action to selectively remove essentially all fluctuations of the gluon field except for the instantons. The close agreement between quenched lattice QCD results with cooled and uncooled configurations for vacuum correlation functions of hadronic currents and for density-density correlat

C. Greub, W. Fetscher, D. Wyler

We investigate the combined effect of neutrino masses and non-standard couplings on the various lepton spectra in $μ$ and $τ$ decays. We emphasize the energy spectra of the neutrinos, which can be measured in the new KARMEN experiment and hence will yield novel information on deviations from the $V-A$ structure. To constrain these couplings, QED radiative co

Kiyoshi Ezawa

Chern-Simons formulation of the 2+1 dimensional Einstein gravity with negative cosmological constant is investigated when the spacetime has the topology ${\bf R}\times T^{2}$. The physical phase space is shown to be a direct product of two sub-phase spaces having symplectic structures with opposite signs. Each sub-phase space is found to be a non-Hausdorff m

W. M. Koo, H. Saleur

We investigate in details how the Virasoro algebra appears in the scaling limit of the simplest lattice models of XXZ or RSOS type. Our approach is straightforward but to our knowledge had never been tried so far. We simply formulate a conjecture for the lattice stress-energy tensor motivated by the exact derivation of lattice global Ward identities. We then

P. Kleban, I. Vassileva

We examine the correspondence between the conformal field theory of boundary operators and two-dimensional hyperbolic geometry. By consideration of domain boundaries in two-dimensional critical systems, and the invariance of the hyperbolic length, we motivate a reformulation of the basic equation of conformal covariance. The scale factors gain a new, physica

David Gershon

Using the algebraic Hamiltonian approach, we derive the exact to all orders O(d,d) transformations of the metric and the dilaton field in WZW and WZW coset models for both compact and non-compact groups. It is shown that under the exact $O(d)\times O(d)$ transformation only the leading order of the inverse metric $G^{-1}$ is transformed. The quantity $\sqrt{

J. Lukierski, H. Ruegg, W. J. Zakrzewski

We consider the Hamiltonian and Lagrangian formalism describing free \k-relativistic particles with their four-momenta constrained to the \k-deformed mass shell. We study the modifications of the formalism which follow from the introduction of space coordinates with nonvanishing Poisson brackets and from the redefinitions of the energy operator. The quantum

Preeti Parashar

We investigate a two parameter quantum deformation of the universal enveloping orthosymplectic superalgebra U(osp(2/2)) by extending the Faddeev-Reshetikhin-Takhtajan formalism to the supersymetric case. It is shown that $U_{p,q}(osp(2/2))$ possesses a non-commutative, non-cocommutative Hopf algebra structure. All the results are expressed in the standard fo

Christopher D. Carone, Mitchell Golden

We consider the detection of the technirho in technicolor models that include a weak scalar doublet. In these models, the scalar develops a vacuum expectation value when the technifermions condense, and fermion masses are generated through Yukawa couplings, as in the standard model. Unlike ordinary technicolor models, the technicolor scale is generally small

M. Creutz, I. Horvath, R. Mendris

After a short review of the Method of Recursive Counting we introduce a general algebraic description of recursive lattice building. This provides a rigorous framework for discussion of method's limitations.

The NRQCD Collaboration

We present results from a high precision NRQCD simulation of the quenched $Υ$ system at $β= 6$. We demonstrate a variety of important lattice techniques, including the perturbative improvement of actions, tadpole improvement, and multicorrelated fits for extracting the spectrum of excited states. We present new determinations of $α_s(M_Z)$ and $M_b$, two fun

Suzhou Huang, A. R. Levi

As a prelude to a truly non-perturbative evaluation of the effective potential in terms of lattice QCD, the one loop effective potential for a non-Abelian gauge configuration is calculated using the background field method. Through a non-trivial correlation between the space and color orientations the new background field avoids the possible coordinate singu

Michael Creutz, Ivan Horvath

We give a Hamiltonian discussion of surface states in an extra dimension as a basis for chiral fermions in lattice models. Such modes appear with the Wilson fermion action when the hopping parameter exceeds a critical value. The association of such states with the closing and reopening of a band gap was noted by Shockley in 1939. Poster presented by Michael

James N. Labrenz, Stephen R. Sharpe

We develop quenched chiral perturbation theory for baryons using the graded-symmetry formalism of Bernard and Golterman and calculate non-analytic contributions to the baryon masses coming from quenched chiral loops. The usual term proportional to $m_{q}^{3/2}$ is substantially altered due to the cancellation of diagrams with internal quark loops. In additio

C. Di Bartolo, R. Gambini, J. Griego, J. Pullin

We propose a new representation for gauge theories and quantum gravity. It can be viewed as a generalization of the loop representation. We make use of a recently introduced extension of the group of loops into a Lie Group. This extension allows the use of functional methods to solve the constraint equations. It puts in a precise framework the regularization

Herbert Balasin, Herbert Nachbagauer

Using the Kerr-Schild decomposition of the metric tensor that employs the algebraically special nature of the Kerr-Newman space-time family, we calculate the energy-momentum tensor. The latter turns out to be a well-defined tensor-distribution with disk-like support.

W. G. Unruh

Time plays different roles in quantum mechanics and gravity. These roles are examined and the problems that the conflict in the roles presents for quantum gravity are briefly summarised.

M. A. Moore, S. Murphy

Removed according to the author's request : Dear Administrator, Please,please could you remove the paper,tentatively assigned the number 9312070, with title "A calculation of the exponent mu for the gauge glass model" and just submitted to the cond-mat board as it contains an important error. Mike Moore

H. H. Lee, M. A. Moore

Monte Carlo simulations are performed to study the properties of type-II superconducting films in a magnetic field in which the vortices move in the two-dimensional geometry represented by the surface of a sphere. No numerical evidence is found for any melting transition, although the correlation length over which vortex crystalline order exists grows as the

Joshua A. Frieman, Román Scoccimarro

We study the prospects for the current microlensing searches, which have recently discovered several candidates, to yield useful information about the flattening of the Galaxy dark matter halo. Models of HI warps and N-body simulations of galaxy formation suggest that disks commonly form in oblate halos with a tilt between the disk and halo symmetry axes. Th

Enrico V. Held, Jeremy R. Mould

We present the results of spectroscopic observations of 10 nucleated dwarf elliptical galaxies (dE's) in the Fornax cluster. The blue spectra of Fornax dE galaxies indicate a wide range of metallicities at a given luminosity, similar to those of intermediate to \it metal-rich globular clusters. Metal abundances derived in this paper are well correlated w

Yoshiaki SOFUE

The edge-on Sc galaxy NGC 5907 has been observed in the 12CO(1-0)-line emission using the Nobeyama 45-m telescope. The radial density distribution between 2 and 13 kpc is well represented by a superposition of an exponential-law disk of scale radius 3.5 kpc and a ring of 7 kpc radius. However, no concentration of gas has been observed in the central 2 kpc. T

F. Yusef-Zadeh W. Cotton M. Wardle F. Melia, D. Roberts

We present the results of a $λ$20 cm VLA observation of the compact Galactic center radio source Sgr A$^*$. The scatter-broadened image is elongated in the East-West direction, with an axial ratio of 0.6$\pm$0.05 and a position angle of 87$^0\pm$3$^0$. A similar shape and orientation has been found previously at shorter wavelengths using VLBI and VLBA. Both

Juan Garcia-Bellido, Andrei Linde, Dmitri Linde

According to the Brans--Dicke theory, the value of the gravitational constant G which we measure at present is determined by the value of the Brans--Dicke scalar field \phi at the end of inflation. However, due to quantum fluctuations of the scalar fields produced during inflation, the gravitational constant G(\phi) may take different values in different exp

Sheldon Katz

This note is a survey of the enumerative geometry of rational curves on Calabi-Yau threefolds, based on a talk given by the author at the May 1991 Workshop on Mirror Symmetry at MSRI. An earlier version appeared in "Essays on Mirror Manifolds"; this version corrects typographical errors that appeared in print, gives a brief update of related progress

S. V. Ketov, O. Lechtenfeld, A. J. Parkes

The most general homogeneous monodromy conditions in $N{=}2$ string theory are classified in terms of the conjugacy classes of the global symmetry group $U(1,1)\otimes{\bf Z}_2$. For classes which generate a discrete subgroup $\G$, the corresponding target space backgrounds ${\bf C}^{1,1}/\G$ include half spaces, complex orbifolds and tori. We propose a gene

Brian Davies

We review some of the recent developments in two dimensional statistical mechanics in which corner transfer matrices provide the vital link between the physical system and the representation theory of quantum affine algebras. This opens many new possibilities, because the eigenstates may be described using the properties of q-vertex operators.

A. Brignole, J. R. Espinosa, M. Quiros, F. Zwirner

We study the finite-temperature effective potential of the Minimal Supersymmetric Standard Model in the full (mA, tan(beta)) parameter space. As for the features of the electroweak phase transition, we identify two possible sources of significant differences with respect to the Standard Model: a stop sector with little supersymmetry breaking makes the phase

E. G. Gurvich, G. G. Leptoukh

We apply the Area Decay Law (ADL) straightforwardly to simulate a quark string hadronization and compare the results with the explicit analytic calculations. We show that the usual "inclusive" Monte--Carlo simulations do not correspond to the ADL because of two mistakes: not proper simulation of two--dimensional probability density and lack of an imp

S. Chakravarti, B. K. Jennings

A relativistic $π$-nucleon potential is extended to $m^* \neq m$ to investigate the possibility of generating s-wave $π$-nucleus repulsion. We find that relativity does indeed generate significant repulsion, the exact amount depending on the details of the calculation. In contradistinction the $tρ$ approximation gives very little repulsion.

S. Alexander Ridgway

I investigate solutions to the Euclidean Einstein-matter field equations with topology $S^1 \times S^2 \times R$ in a theory with a massless periodic scalar field and electromagnetism. These solutions carry winding number of the periodic scalar as well as magnetic flux. They induce violations of a quasi-topological conservation law which conserves the produc

Adam M. Bincer

Expressions are given for the Casimir operators of the exceptional group $F_4$ in a concise form similar to that used for the classical groups. The chain $B_4\subset F_4\subset D_{13}$ is used to label the generators of $F_4$ in terms of the adjoint and spinor representations of $B_4$ and to express the 26-dimensional representation of $F_4$ in terms of the

Bas Peeters, Peter van Nieuwenhuizen

Instead of imposing the Schrödinger equation to obtain the configuration space propagator $\csprop$ for a quantum mechanical nonlinear sigma model, we directly evaluate the phase space propagator $\psprop$ by expanding the exponent and pulling all operators $\hat p$ to the right and $\hat x$ to the left. Contrary to the widespread belief that it is sufficien

Bernhard Meister

In this paper alternative formulations of the conventional uncertainty relation are studied in the context of decoherent histories. The results are given in terms of Shannon information. A variety of methods are developed to evaluate the upper bound for the probability of two or more projection histories. The methods employed give improved limits for the max

M. Dobroliubov, A. Morozov, G. Semenoff, N. Weiss

We examine the properties of observables in the Kazakov-Migdal model. We present explicit formulae for the leading asymptotics of adjoint Wilson loops as well as some other observables for the model with a Gaussian potential. We discuss the phase transiton in the large $N$ limit of the $d=1$ model. One of appendices is devoted to discussion of the $N =\infty

H. Aratyn, L. A. Ferreira, A. H. Zimerman

We show that the multi-boson KP hierarchies possess a class of discrete symmetries linking them to the discrete Toda systems. These discrete symmetries are generated by the similarity transformation of the corresponding Lax operator. This establishes a canonical nature of the discrete transformations. The spectral equation, which defines both the lattice sys

E. Kiritsis, C. Kounnas, D. Lust

A large class of new 4-D superstring vacua with non-trivial/singular geometries, spacetime supersymmetry and other background fields (axion, dilaton) are found. Killing symmetries are generic and are associated with non-trivial dilaton and antisymmetric tensor fields. Duality symmetries preserving N=2 superconformal invariance are employed to generate a larg

Hideaki Hiro-Oka, Satoru Saito

The Laughlin function of quantum Hall effect is shown to satisfy Hirota's bilinear difference equation with certain coefficients a little different from the KP hierarchy. Vertex operators which constitute blocks of solutions generate a Bäcklund transformation. Besides the Laughlin function, the equation admits soliton solutions.

Su Houng Lee

We look at the contribution of Quark-Mass-dependent twist-4 operators to the second moments of spin averaged structure functions and the Bjorken sum rule. Its contribution is non-negligible in the former case due to large Wilson coefficients. We also discuss the values of the twist- 4 spin-2 nucleon matrix element within present experimental constraints.

G. Gianini, I. M. Dremin, V. A. Nechitailo, B. B. Levchenko

The ratio of cumulant to factorial moments of multiplicity distribu- tions has been calculated for e+e- and hh data in a wide range of energies. As a function of the rank it exhibits a regular behaviour with a steep descent and two negative minima. This behaviour is not accounted for by NBD, that leads to a monotonically decreasing positive-defined ratio. A

Stefan Resag, Michael Beyer

We investigate the quark structure of D and B mesons in the framework of a constituent quark model. To this end, we assume a scalar confining and a one gluon exchange (OGE) potential. The parameters of the model are adopted to reproduce the meson mass spectrum. From a fit to ARGUS and CLEO data on B->D*lv semileptonic decay we find for the Cabbibo Kobayashi

A. Pich

An overview of the phenomenology of CP violation is presented. The Standard Model mechanism of CP violation and its main experimental tests, both in the kaon and bottom systems, are discussed. (Lectures given at the 1993 Trieste Summer School and at the Escuela Latinoamericana de Fisica, ELAF'93, Argentina).

L. Burakovsky, L. P. Horwitz

The low-temperature form of the equilibrium relativistic mass distribution is subject to the Galilean limit by taking $c\rightarrow \infty .$ In this limit the relativistic Maxwell-Boltzmann distribution passes to the usual nonrelativistic form and the Dulong-Petit law is recovered.

Margarita Garcia Perez, Antonio Gonzalez-Arroyo, Pablo Martinez

We study the spatial volume dependence of electric flux energies for SU(2) Yang-Mills fields on the torus with twisted boundary conditions. The results approach smoothly the rotational invariant Confinement regime. The would-be string tension is very close to the infinite volume result already for volumes of $(1.2 \ {\rm fm.})^3$. We speculate on the consequ

APE Collaboration

The decay constants of the heavy-light pseudoscalar mesons are studied in a high statistics run using the Wilson action at $β=6.0$ and $β=6.2$, and the clover action at $β=6.0$. The systematics of $O(a)$ discretisation errors are discussed. Our best estimates of the decay constants are: $f_D$ = 218(9) MeV, $f_D/f_{Ds}$ = 1.11(1) and we obtain preliminary val

APE Collaboration

Recent results for semi-leptonic decays of $D$ and $B$ mesons at $β=6.4$, using the Wilson action, and at $β=6.0$, using the Clover action, are reported.

APE Collaboration

The light quark results from three different simulations are summarized. We get consistent results, within our statistics, between smeared and non smeared data. A comparison is performed with similar results from the UKQCD collaboration. All runs have been performed on two 6.4 GF APE computers \cite{tubo}.

A. Krasnitz, R. Potting

We measure the diffusion rate of Chern-Simons number in the (1+1)-dimensional Abelian Higgs model interacting with a realistic heat bath for temperatures between 1/13 and 2/3 times the sphaleron energy. It is found that the measured rate is close to that predicted by the sphaleron approximation at the lower end of the temperature range considered but falls a

C. F. Baillie, D. A. Johnston

We investigate numerically the behaviour of damage spreading in a Kauffman cellular automaton with quenched rules on a dynamical $ϕ^3$ graph, which is equivalent to coupling the model to discretized 2D gravity. The model is interesting from the cellular automaton point of view as it lies midway between a fully quenched automaton with fixed rules and fixed co

James E. Lidsey

The Wheeler-DeWitt equation is derived from the bosonic sector of the heterotic string effective action assuming a toroidal compactification. The spatially closed, higher dimensional Friedmann-Robertson-Walker (FRW) cosmology is investigated and a suitable change of variables rewrites the equation in a canonical form. Real- and imaginary-phase exact solution

Ajit M. Srivastava, Michael Stone

We investigate the propagation of electromagnetic waves in the core of a winding number one string defect with isotropic core in nematic liquid crystals. We numerically solve wave equations for the TE mode and show the existence of guided modes arising due to the variation of the refractive index as a function of the scalar order parameter.

A. Houghton, H. -J. Kwon, J. B. Marston, R. Shankar

We investigate the effects of the Coulomb two-body interaction on Fermi liquids via bosonization. The Coulomb interaction is singular in the limit of low momentum transfer, and recent interest in the possibility that some singular interactions might destroy the Fermi liquid state motivate us to reexamine it. We calculate the exact boson correlation function

Y. Leroyer, E. Pommiers

We study the percolative properties of bi-dimensional systems generated by a random sequential adsorption of line-segments on a square lattice. As the segment length grows, the percolation threshold decreases, goes through a minimum and then increases slowly for large segments. We explain this non-monotonic behaviour by a structural change of the percolation

Iwan Jensen

In a recent letter [J. Phys. A26, L801 (1993)], Yaldram et al. studied the critical behaviour of a simple lattice gas model of the CO-NO catalytic reaction. The model exhibits a second order nonequilibrium phase transition from an active state into one out of infinitely many absorbing states. Estimates for the critical exponent $β$ suggested that the model b

I. L. Aleiner, L. I. Glazman

We investigate the low-energy spectrum of excitations of a compressible electron liquid in a strong magnetic field. These excitations are localized at the periphery of the system. The analysis of a realistic model of a smooth edge yields new branches of acoustic excitation spectrum in addition to the well known edge magnetoplasmon mode. The velocities are fo

Hume A. Feldman, Richard Watkins

We calculate the theoretical expectation for the bulk motion of a large scale survey of the type recently carried out by Lauer and Postman. Included are the effects of survey geometry, errors in the distance measurements, clustering properties of the sample, and different assumed power spectra. We consider the power spectrum calculated from the IRAS--QDOT su

James E. Lidsey

Within the context of the cold dark matter model, current observations suggest that inflationary models which generate a tilted primordial power spectrum with negligible gravitational waves provide the most promising mechanism for explaining large scale clustering. The general form of the inflationary potential which produces such a spectrum is a hyperbolic

Gary A. Mamon

Massive multicolor digital surveys in the near infrared provide new opportunities for statistical analyses of the properties of groups and clusters. These galaxy systems provide a natural laboratory for studying dynamical processes and galaxy evolution, and serve as powerful cosmological diagnostics. The immediate scientific returns to be expected from near-

Richard A. Frewin, James E. Lidsey

There exists a growing body of observational evidence supporting a non-vanishing cosmological constant at the present epoch. We examine the possibility that such a term may arise directly from the potential energy which drove an inflationary expansion of the very early universe. To avoid arbitrary alterations in the shape of this potential at various epochs

J. I. Katz

Particles with energies below the mean energy $E_0$ in relativistic shocked plasmas should assume an equilibrium energy distribution. This leads to a synchrotron spectrum $F_ν\propto ν^{1/3}$ up to approximately the critical frequency $ν_0$ of an electron with the energy $E_0$. Application to GRBs implies that a burst with $10^{-5}$ erg/cm$^2$s of soft gamma

Shahn Majid

We obtain an R-matrix or matrix representation of the Artin braid group acting in a canonical way on the vector space of every (super)-Lie algebra or braided-Lie algebra. The same result applies for every (super)-Hopf algebra or braided-Hopf algebra. We recover some known representations such as those associated to racks. We also obtain new representations s

Ted Jacobson, Gungwon Kang, Robert C. Myers

Two techniques for computing black hole entropy in generally covariant gravity theories including arbitrary higher derivative interactions are studied. The techniques are Wald's Noether charge approach introduced recently, and a field redefinition method developed in this paper. Wald's results are extended by establishing that his local geometric exp

G. Frichter, D. Robson

We investigate (2+1)-d Hamiltonian lattice gauge theory using a class of Hamiltonians having exactly known vacuum states. These theories are shown to have a wide range of possible classical continuum limits which differ from that of the standard Kogut-Susskind Hamiltonian. This conclusion is at variance with some previously published results. We examine the

F. Bonechi, R. Giachetti, E. Sorace, M. Tarlini

A *-product compatible with the comultiplication of the Hopf algebra of the functions on the Heisenberg group is determined by deforming a coboundary Lie-Poisson structure defined by a classical r-matrix satisfying the modified Yang-Baxter equation. The corresponding quantum group is studied and its R-matrix is explicitly calculated.

Saharon Shelah

We prove that in the product of kappa many Boolean algebras we cannot find an independent set of more than 2^kappa elements solving a problem of Monk (earlier it was known that we cannot find more than 2^{2^kappa} but can find 2^kappa).

Alexander Koldobsky

Let $ n\geq 2, A=(a_{ij})_{i,j=1}^{n}$ be a real symmetric matrix, $a=(a_i)_{i=1}^{n}\in \Bbb R^n.$ Consider the differential operator $D_A = \sum_{i,j=1}^n a_{ij}{\partial^2 \over \partial x_i \partial x_j}+ \sum_{i=1}^n a_i{\partial \over \partial x_i}.$ Let $E$ be a bounded domain in $\Bbb R^n,$ $p>0.$ Denote by $L_{D_A}^p(E)$ the space of solutions of th

P. P. Kulish

The properties of the quantum Minkowski space algebra are discussed. Its irreducible representations with highest weight vectors are constructed and relations to other quantum algebras: $su_{q}(2)$, $q$-oscillator, $q$-sphere are pointed out.

E. I. Guendelman, A. Leonidov, V. Nechitailo, D. A. Owen

The first three coefficients in an expansion of the heat kernel of a nonminimal nonabelian kinetic operator taken in an arbitrary background gauge in arbitrary space-time dimension are calculated

K. Scharnhorst

Based on a methodological analysis of the effective action approach certain conceptual foundations of quantum field theory are reconsidered to establish a quest for an equation for the effective action. Relying on the functional integral formulation of Lagrangian quantum field theory a functional integral equation for the complete effective action is propose

Michael Crescimanno

Black hole spacetimes are semiclassically not static. For black holes whose lifetime is larger than the age of the universe we compute, in leading order, the power spectrum of deviations of the electromagnetic charge from it's average value, zero. Semiclassically the metric itself has a statistical interpretation and we compute a lowerbound on its varian

Michael Crescimanno

For the series associated to a group or coset R.C.F.T. there is a simple universal form for the inverse of the handle operator in the ring of fusions. These formulae may be easily understood from the quantization of the associated Chern-Simons theory. (Transcript of talk given at STRINGS '93 (Berkeley) Conference)

Michael Crescimanno

Several interesting features of coset models "without fixed points" are easily understood via Chern-Simons theory. In this paper we derive explicit formulae for the handle-squashing operator in these cosets. These operators are fixed, linear combinations of the irreducible representations of the coset. As a simple application of these curious formula

L. D. Faddeev, R. M. Kashaev

The problem of diagonalization of the quantum mechanical Hamiltonian, governing dynamics of an electron on a two-dimensional triangular or square lattice in external uniform magnetic field, applied perpendicularly to the lattice plane, the flux through lattice cell, divided by the elementary quantum flux, being rational number, is reduced to generalized Beth

E. Elizalde, S. D. Odintsov, A. Romeo

The formalism of Greensite for treating the spacetime signature as a dynamical degree of freedom induced by quantum fields is considered for spacetimes with nontrivial topology of the kind ${\bf R}^{D-1} \times {\bf T}^1$, for varying $D$. It is shown that a dynamical origin for the Lorentzian signature is possible in the five-dimensional space ${\bf R}^4 \t

Y. Aharonov, S. Coleman, A. S. Goldhaber, S. Nussinov

We investigate the phase accumulated by a charged particle in an extended quantum state as it encircles one or more magnetic fluxons, each carrying half a flux unit. A simple, essentially topological analysis reveals an interplay between the Aharonov-Bohm phase and Berry's phase.

L. Hlavaty

Algebraic framework for construction of a commuting set of operators that can be interpreted as integrals of motion of the open spin chain with boundary conditions and nearest neighbour interaction is investigated.

J. Ignatius

Physical processes related to cosmological first-order phase transitions are discussed and reviewed in this introductory part of dissertation. I first describe cosmological phase transitions on a general level, concentrating on bubble nucleation, phase change, and related phenomena. I point out that especially the onset of a cosmological phase transition sho

A. I. Bochkarev, J. I. Kapusta

We use an effective low energy field theory to describe the coupling between glueballs and mesons as an analog of the quenched approximation in lattice QCD. This allows us to study the temperature dependence of mesonic screening masses at temperatures below the deconfinement phase transition.

C. P. Burgess, S. Godfrey, H. König, D. London

Using effective-lagrangian techniques we perform a systematic survey of the lowest-dimension effective interactions through which heavy physics might manifest itself in present experiments. We do not restrict ourselves to special classes of effective interactions (such as `oblique' corrections). We compute the effects of these operators on all currently

Tatsuya Nakada

A phenomenological description of the neutral K and B meson systems is presented. The situation of the current CP violation experiments is described and a detailed discussion of their results is given, followed by some future prospects.

R. J. Furnstahl, T. Hatsuda

In a recent Physical Review Letter, Kondo and Morimatsu present a QCD sum rule calculation of nucleon-nucleon scattering lengths. They also relate the empirical scattering lengths to the nucleon mass shift in nuclear matter to cast doubt on the "linear density approximation." In this Comment, we point out flaws in both parts of their analysis and dra