January 1996 arXiv papers — page 10

A. Gramada, M. E. Raikh

The effect of a short--range impurity on the transmission through a saddle--point potential for an electron, moving in a strong magnetic field, is studied. It is demonstrated that for a random position of an impurity and random sign of its potential the impurity--induced mixing of the Landau levels diminishes {\em on average} the transmission coefficient. Th

Andrew F. Heckler

We show that once a black hole surpasses some critical temperature $T_{crit}$, the emitted Hawking radiation interacts with itself and forms a nearly thermal photosphere. Using QED, we show that the dominant interactions are bremsstrahlung and electron-photon pair production, and we estimate $T_{crit} \sim m_{e}/α^{5/2}$, which when calculated more precisely

Ivan O'Brien, L O'C Drury

The observed H$_2$ line ratios in OMC--1 and IC443 are not satisfactorily explained by conventional shock excitation models. We consider the microscopic collisional processes implicit in ambipolar diffusion models of magnetised C-shocks and show that non-LTE level populations and emission line ratios are an inevitable consequence of such models. This has imp

Marc Kamionkowski, Gerard Jungman, Arthur Kosowsky, David N. Spergel

We discuss what can be learned about the baryon density from an all-sky map of the cosmic microwave background (CMB) with sub-degree angular resolution. With only minimal assumptions about the primordial spectrum of density perturbations and the values of other cosmological parameters, such a CMB map should be able to distinguish between a Universe with a ba

Rien van de Weygaert

The role of tidal shear in the formation of structure in the Universe is explored. To illustrate the possible and sometimes dramatic impact of tidal fields we focus on the evolution of voids. We firstly analyze the role of tidal fields both in the highly symmetric situation of an initially homogeneous ellipsoidal underdensity embedded in an artificially impo

K. Maki, T. Mitsui, S. Orito

We investigate low-energy cosmic-ray antiprotons ($\bar{p}$'s) arising from the fragmentation of quarks and gluons emitted from evaporating primordial black holes (PBHs). To calculate the local interstellar flux of these $\bar{p}$'s, their propagation in the Galaxy is described by a 3-D Monte Carlo simulation based on the diffusion model. This flux i

Robert Treger

We use Harer's stability theorem to give another proof of his fundamental theorem: The rank of the Picard group of the moduli space of smooth projective curves of genus g > 2 equals one.

Vijay Balasubramanian

I define a natural measure of the complexity of a parametric distribution relative to a given true distribution called the {\it razor} of a model family. The Minimum Description Length principle (MDL) and Bayesian inference are shown to give empirical approximations of the razor via an analysis that significantly extends existing results on the asymptotics o

D. Anselmi, M. Grisaru, A. Johansen

We discuss several aspects of superconformal field theories in four dimensions (CFT_4), in the context of electric-magnetic duality. We analyse the behaviour of anomalous currents under RG flow to a conformal fixed point in N=1, D=4 supersymmetric gauge theories. We prove that the anomalous dimension of the Konishi current is related to the slope of the beta

Grigori Olshanski, Anatoli Vershik

Let $H$ be the space of all Hermitian matrices of infinite order and $U(\infty)$ be the inductive limit of the chain $U(1)\subset U(2)\subset...$ of compact unitary groups. The group $U(\infty)$ operates on the space $H$ by conjugations, and our aim is to classify the ergodic $U(\infty)$-invariant probability measures on $H$ by making use of a general asympt

A. Dimakis, F. Mueller-Hoissen

A construction of conservation laws for $σ$-models in two dimensions is generalized in the framework of noncommutative geometry of commutative algebras. This is done by replacing the ordinary calculus of differential forms with other differential calculi and introducing an analogue of the Hodge operator on the latter. The general method is illustrated with s

I. Ya. Aref'eva

Recently it was shown that an asymptotic behaviour of $SU(N)$ gauge theory for large $N$ is described by q-deformed quantum field. The master fields for large N theories satisfy to standard equations of relativistic field theory but fields satisfy $q$-deformed commutation relations with $q=0$. These commutation relations are realized in the Boltzmannian Fock

M. C. Land, L. P. Horwitz

More than twenty years have passed since the threads of the `proper time formalism' in covariant classical and quantum mechanics were brought together to construct a canonical formalism for the relativistic mechanics of many particles. Drawing on the work of Fock, Stueckelberg, Nambu, Schwinger, and Feynman, the formalism was raised from the status of a

K. Melnikov, V. G. Serbo

The cross section for the reactions of the type $μ^-μ^+ \to e\barν_e X$ can not be calculated by the standard methods due to the $t$--channel singularity in the physical region. In this letter we show that accounting for the finite sizes of the colliding beams results in the regularization of this singularity. The finite cross section, which is obtained in t

Jorge Griego

In the loop representation the quantum constraints of gravity can be solved. This fact allowed significant progress in the understanding of the space of states of the theory. The analysis of the constraints over loop dependent wavefunctions has been traditionally based upon geometric (in contrast to analytic) properties of the loops. The reason for this pref

Jean-Louis Barrat, Jean-Francois Joanny

1. Introduction 2. Charged chains at infinite dilution - asymptotic properties 2.1 Definition of the model and Flory-like calculation 2.2 Variational approaches 2.3 Renormalization group calculations 2.4 Screening of electrostatic interactions 2.5 Annealed and quenched polyelectrolytes 3. Local aspects of screening 3.1 Counterion condensation 3.2 Poisson Bol

Yuval Oreg, Alexander M. Finkel'stein

The problem of the Fermi--edge singularity in a one--dimensional Tomonaga--Luttinger liquid is reconsidered. The backward scattering of the conduction band electrons on the impurity--like hole in the valence band is analyzed by mapping the problem onto a Coulomb gas theory. For the case when the electron--electron interaction is repulsive the obtained expone

Yuval Oreg, Alexander M. Finkel'stein

We have calculated the tunneling density of states (DOS) at the location of a backward scattering defect for quantum wires and for edge state electrons in quantum Hall systems. A singular enhancement of the DOS arises as a result of the combined effect of multiple backward scattering together with a repulsive electron---electron interaction.

Iftah Gideoni

Computational difficulties in the general application of Bretthorsts formalism to time-series problems, posed by the large number of possible models and the use of models with nonorthogonal base-functions are discussed. The specific problem under consideration is a Bayesian procedure for model selection, parameter estimation, and classification, that was app

A. M. Khokhlov, E. S. Oran, J. C. Wheeler

Turbulent combustion is three-dimensional. Turbulence in a Type Ia supernova is driven on large scales by the buoyancy of burning products. The turbulent cascade penetrates down to very small scales, and makes the rate of deflagration independent of the microphysics. The competition between the turbulent cascade and the freeze-out of turbulent motions due to

A. Clocchiatti, J. C. Wheeler

The Type Ic supernovae are probably "nearly-nude" core collapse events. They are thus of special interest in terms of their evolutionary origin, but also as the source of potential clues to the explosion process that may not be obtained from other supernovae. Study of Type Ic shows that they are distinct from Type Ia, even those of the dimmer, redder

W-Y. P. Hwang

By matching the world of hadrons to that of some effective chiral quark theory, we determine the induced condensates for QCD sum rules in the presence of an external pion field. The observed values of the strong and weak $πNN$ coupling constants are understood.

H. S. Somal, B. J. Feenstra, J. Schützmann, Jae Hoon Kim

Infrared reflectivity measurements, using p-polarized light at a grazing angle of incidence, show an increased sensitivity to the optical conductivity of highly reflecting superconducting materials. We demonstrate that when this measurement technique is applied to the conventional s-wave superconductor NbN, the results are in perfect agreement with BCS theor

Taksu Cheon

A novel scheme to solve the quantum eigenvalue problem through the imaginary-time Green function Monte Carlo method is presented. This method is applicable to the excited states as well as to the ground state of a generic system. We demonstrate the validity of the method with the numerical examples on three simple systems including a discretized sine-Gordon

H. Kleinert, G. Lambiase, V. V. Nesterenko

We point out that in infinite spacetime dimensions, the singularity in the interquark potential at small distances disappears if the string is anchored at one end to a heavy quark, at the other end to a light quark. This suggests that if quarks are placed at the end of strings some unphysical features such as tachyon states may be absent also in in finite di

A. Frydryszak

We briefly review models of relativistic particles with spin. Departing from the oldest attempts to describe the spin within the lagrangian framework we pass through various non supersymmetric models. Then the component and superfield formulations of the spinning particle and superparticle models are reviewed. Our focus is mainly on the classical side of the

Taejin Lee

Lee replies to the comment on "Statistical Mechanics of Non-Abelian Chern-Simons Particles" by C. R. Hagen

G. P. Salam

A Monte Carlo simulation program is presented which can be used to determine the small-$x$ evolution of a heavy onium using Mueller's colour dipole formulation, giving the full distribution of dipoles in rapidity and impact parameter. Routines are also provided which calculate onium-onium scattering amplitudes between individual pairs of onium configurat

A. A. El-Zant

Complications arising from the non-compact nature of the phase space of N-body systems prevent any asymptotic characterization of chaotic behaviour (since no equilibrium final states can exist). This leads us to revisit some of the old results concerning geodesic stability on Lagrangian manifolds. These cannot be applied directly but may be useful when prope

Yongbin Ruan, Gang Tian

We define higher genus Gromov-Witten invariants and establish a mathematical theory of sigma model coupled with gravity over any semi-positive symplectic manifolds. As applications, we verify the stablizing conjecture of symplectic 4-manifolds for simply connected elliptic surfaces and construct smooth 6-manifolds admitting infinitely many deformation classe

Thomas. D. Cohen

Inequalities for QCD functional integrals are used to establish that up to certain technical assumptions. the high temperature chirally restored phase of QCD is effectively symmetric under $U(N_f) \times U(N_f)$ rather than $SU(N_f) \times SU(N_f)$. If these assumptions are correct, there are no effects due to anomalous breaking of $U(1)_A$ on correlation fu

A. Klemm, P. Mayr

We study a class of extremal transitions between topological distinct Calabi--Yau manifolds which have an interpretation in terms of the special massless states of a type II string compactification. In those cases where a dual heterotic description exists the exceptional massless states are due to genuine strong (string-) coupling effects. A new feature is t

Pijush K. Ghosh

It is shown that a gauged nonlinear $O(3)$ sigma model with anomalous magnetic moment interaction in $2+1$ dimensions is exactly integrable for static, self-dual field configurations. The matter fields are exactly equivalent to those of the usual ungauged nonlinear $O(3)$ sigma model. These static soliton solutions can be mapped into an Abelian purely magnet

J. C. Brunelli

We study from a Hamiltonian point of view the generalized dispersionless KdV hierarchy of equations. From the so called dispersionless Lax representation of these equations we obtain three compatible Hamiltonian structures. The second and third Hamiltonian structures are calculated directly from the r-matrix approach. Since the third structure is not related

Fusun Akman, Alex J. Feingold, Michael D. Weiner

The fusion rules for the $(p,q)$-minimal model representations of the Virasoro algebra are shown to come from the group $G = \boZ_2^{p+q-5}$ in the following manner. There is a partition $G = P_1 \cup ...\cup P_N$ into disjoint subsets and a bijection between $\{P_1,...,P_N\}$ and the sectors $\{S_1,...,S_N\}$ of the $(p,q)$-minimal model such that the fusio

K. Zioutas

Conventional physics cannot explain bioeffects caused by ELF fields [1]. A (double) resonance interaction of ELF radiation with the highly sub-thermal coherent motion of spiral waves in living matter (LM) is suggested. The (geo)magnetic cyclotron resonance (CR) absorption by the constituent ions can drastically change their non-thermal degrees of freedom in

G. A. Chekomazov, S. E. Muraviev, M. H. Urin

A semimicroscopical approach is formulated to describe the direct nucleon decay of various giant resonances in intermediate and heavy mass spherical nuclei. The approach consists in: (i) the exact continuum-RPA calculations for amplitudes of the reactions accompanied by excitation and the nucleon decay of the collective particle-hole states (doorway states);

Kai Hencken, Dirk Trautmann, Gerhard Baur

We apply the Equivalent Photon Approximation to calculate cross sections for the simultaneous excitation of two heavy ions in relativistic collisions. We study especially the excitation of two nuclei to a 1- - state and show that the equations are symmetric with respect to both ions. We also examine the limit in which the excitation energy of one of the nucl

V. S. Gorovoy, I. T. Obukhovsky

The nucleon-nucleon interaction at short range is analyzed in terms of six-quark configurations on a base of numerical solutions of modified RGM equations. It is shown that in low partial waves L=0,1 the system has a two-channel character: the $NN$ channel and the inner six-quark state ("bag") with specific color-spin structure. Starting from this an

Andreas Bette

Twistor phase spaces are used to provide a general description of the dynamics of a finite number of directly interacting massless spinning particles forming a closed relativistic massive and spinning system with an internal structure. A Poincare invariant canonical quantization of the so obtained twistor phase space dynamics is performed.

M. R. Gaberdiel

We analyse abelian T-duality for WZW models of simply-connected groups. We demonstrate that the dual theory is a certain orbifold of the original theory, and check that it is conformally invariant. We determine the spectrum of the dual theory, and show that it agrees with the spectrum of the original theory.

Dirk Schlingemann

We consider the properties of massive one particle states on a translation covariant Haag-Kastler net in Minkowski space. In two dimensional theories, these states can be interpreted as soliton states and we are interested in the existence of antisolitons. It is shown that for each soliton state there are three different possibilities for the construction of

Hitoshi Yamamoto

We review the physics of rare, leptonic, and hadronic decays of charmed mesons based on the results submitted to this conference (EPS 95, Brussles).

Witold Skiba

We investigate the production and the decays of pseudo-Goldstone bosons (PGBs) predicted by technicolor theories with the GIM mechanism (TC-GIM). The TC-GIM models contain exotic fermion families that do not interact under weak $SU(2)$, but they do have color and hypercharge interactions. These fermions form PGBs, which are the lightest exotic particles in t

Wing Kai Wong

We use the BLM procedure to eliminate the renormalization scale ambiguity in the evolution equation for the non-singlet deep-inelastic structure function $F_2^{\text NS}(x,Q).$ The scale of the QCD coupling in the $\overline{\text{MS}}$ scheme has the form $Q^*(x) = Q (1-x)^{1/2} / x~f(x) $, where $x$ is the Bjorken variable and $f(x)$ is a smoothly varying

C. O. Lousto

We review and correct the classical critical exponents characterizing the transition from negative to positive black hole's heat capacity at high charge--angular momentum. We discuss the stability properties of black holes as a thermodynamic system in equilibrium with a radiation bath (canonical ensamble) by using the Helmholtz free energy potential. We

D. A. Kalinin

Hamilton flows on Kähler manifold for which all trajectories are $H$-planar curves (complex analog of geodesics) are considered. These flows are called $H$-planar. The equation which has to obey the Hamiltonian of $H$-planar Hamilton flow is received and the method of finding general solution of this equation is proposed. Trajectories of charged particles in

A. Cabo, A. Perez Martinez

We consider the Bethe Salpeter Equation (BSE) for a fractionally filled Landau level. A phenomenological discussion of the $1/3$ Laughlin's state is performed by assuming an ansatz for the one-particle propagator. The BSE is solved in this approach and it predicts an instability under the formation of charge density oscillations for a wide range of the o

D. Z. Liu, H. A. Fertig, S. Das Sarma

We develop a method to compute shakeup effects on photoluminescence from a strong magnetic field induced two-dimensional Wigner crystal. Only localized holes are considered. Our method treats the lattice electrons and the tunneling electron on an equal footing, and uses a quantum-mechanical calculation of the collective modes that does not depend in any way

Y. Zha, V. Barzykin, D. Pines

We show that it is possible to reconcile NMR and neutron scattering experiments on both LSCO and YBCO, by making use of the Millis-Monien-Pines mean field phenomenological expression for the dynamic spin-spin response function, and reexamining the standard Shastry-Mila-Rice hyperfine Hamiltonian for NMR experiments. The recent neutron scattering results of A

T. A. Luce, W. Huebner, K. H. Bennemann

We present a theory for the electron-temperature dependence $T_{el}$ of optical second harmonic generation (SHG). Such an analysis is required to study the dynamics of metallic systems with many hot electrons not at equilibrium with the lattice. Using a tight-binding theory for the nonlinear susceptibility \cwtel and the Fresnel coefficients we present resul

Alain Comtet, Cécile Monthus, Marc Yor

The paper deals with exponential functionals of the linear Brownian motion which arise in different contexts such as continuous time finance models and one-dimensional disordered models. We study some properties of these exponential functionals in relation with the problem of a particle coupled to a heat bath in a Wiener potential. Explicit expressions for t

Supriya Krishnamurthy, Mustansir Barma

We study a dynamically generated pattern in height gradients, centered around the active growth site, in the steady state of a self-organised interface depinning model. The pattern has a power-law tail and depends on interface slope. An approximate integral equation relates the profile to local interface readjustments and long-ranged jumps of the active site

Jeremiah P. Ostriker, Renyue Cen

We compute, including a current state-of-the-art treatment of hydrodynamical processes, heating and cooling, a variety of cosmological models into the extreme nonlinear phase to enable comparisons with observations. First, we note the common, model independent results. All have a mean ($z=0$) temperature of $10^{4.5}-10^{5.5}$\Kel, set essentially by photohe

T. A. Smecker-Hane, P. B. Stetson, J. E. Hesser, D. A. VandenBerg

We present photometry for stars in the Carina dwarf spheroidal galaxy that is unprecedented in depth, accuracy and spatial coverage. Our data demonstrate that Carina has had a surprisingly complex evolution dominated by episodic bursts of star formation. Comparing the color-magnitude diagram with new theoretical isochrones, we determine that the ages of the

V. Ripepi, F. Barone, L. Milano, G. Russo

We have refined the CORS method, introduced in 1980 for the computation of the cepheid radii, in order to extend its applicability to recent and extensive sets of observations. The refinement is based on the computation, from observational data only, of one of the terms of the solving equation, previously based only on precise calibrations of photometric col

Paolo Salucci, Massimo Persic

We show that the high local baryonic fraction, M(bar) ~ 1/3 M(tot), found in groups and clusters of galaxies does not reconcile the observed cosmological baryon density with the standard Big-Bang prediction. Taking into account recent measurements on the hot-gas content and temperature functions of clusters and groups, we get Omega(gas) = 0.0023 h_{50}^{-1.5

Cheryl Frost, John Lattanzio

We present a review of AGB star evolution, with emphasis on the nucleosynthesis occurring in these stars. In particular, we discuss hot and cool bottom burning, observational constraints, and analysis of meteoritic grains. This paper was presented at the 32nd Liege Colloquium "Stellar Evolution: What Should Be Done ?"

S. P. Ellingsen, M. L. von Bibra, P. M. McCulloch, R. P. Norris

We report the results of the first complete survey of an area of the Galactic Plane for maser emission from the 6.7-GHz transition of methanol. The survey covers a 10.6-square-degree region of the Galactic Plane in the longitude range 325-335 degrees and latitude range -0.53-0.53 degrees. The survey is sensitive to masers with a peak flux density greater tha

M. Catelan

It has recently been suggested that the discrepancy between the "long" and "short" distance moduli of the Large Magellanic Cloud (LMC), as inferred from the properties of the Cepheid and RR Lyrae variables, respectively, might be due to the action of "third parameters" between the Galaxy and the LMC, which would make the RR Lyraes in

Patricia L. Pacelli

We extend an earlier result by Dan Abramovich, showing that a conjecture of S. Lang's implies the existence of a uniform bound on the number of $K$-rational points over all smooth curves of genus $g$ defined over $K$, where $K$ is any number field of fixed degree $d$, and $g$ is an integer greater than 1. The bound depends only on the genus $g$ and the d

Atsushi Moriwaki

Let M_g be the moduli space of stable curves of genus g >= 2. Let D_i be the irreducible component of the boundary of M_g such that general points of D_i correspond to stable curves with one node of type i. Let M_g^0 be the set of stable curves that have at most one node of type i>0. Let d_i be the class of D_i in Pic(M_g)_Q and h the Hodge class on M_g. In

S. Vandoren

In this thesis we give an overview of the antifield formalism and show how it must be used to quantise arbitrary gauge theories. The formalism is further developed and illustrated in several examples, including Yang-Mills theory, chiral $W_3$ and $W_{2,5/2}$ gravity, strings in curved backgrounds and topological field theories. All these models are character

Ofer Aharony, Shimon Yankielowicz

We analyze the Coulomb phase of theories of $N=2$ SQCD with $SU(N_c)$ gauge groups which are conjectured to have exact electric-magnetic duality. We discuss the duality transformation of the particle spectrum, emphasizing the differences between the general case and the $SU(2)$ case. Some difficulties associated with the definition of the duality transformat

Kikuo Harigaya

The optical excitations in $\rug$ and higher fullerenes, including isomers of C$_{76}$, C$_{78}$, and C$_{84}$, are theoretically investigated. We use a tight binding model with long-range Coulomb interactions, treated by the Hartree-Fock and configuration-interaction methods. We find that the optical excitations in the energy region smaller than about 4 eV

M. Kirchbach, L. Tiator

The pseudoscalar and pseudovector $ηN$ coupling constants are calculated from an effective vertex associated with the $a_0(980)πN$ triangle diagram. The predicted values are in agreement with the ones concluded from fitting $η$ photoproduction amplitudes. In this context we stress the importance of the properties of the scalar meson octet for $η$ meson physi

E. J. Copeland, H. J. de Vega, A. Vázquez

The quantum energy-momentum tensor ${\hat T}^{μν}(x)$ is computed for strings in Minkowski space-time. We compute its expectation value for different physical string states both for open and closed bosonic strings. The states considered are described by normalizable wave-packets in the center of mass coordinates. We find in particular that ${\hat T}^{μν}(x)$

Klaus Behrndt, Renata Kallosh

Supersymmetric monopoles of the heterotic string theory associated with arbitrary non-negative number of the left moving modes of the string states are presented. They include H monopoles and their T dual partners F monopoles (ALE instantons). Massive F = H monopoles are T self-dual. Solutions include also an infinite tower of generic T duality covariant non

V. A. Kudryavtsev, G. Weidl

We consider a critical composite superconformal string model to desribe hadronic interactions. We present a new approach of introducing hadronic quantum numbers in the scattering amplitudes. The physical states carry the quantum numbers and form a common system of eigenfunctions of the operators in this string model. We give explicit constructions of the qua

W. Cassing, W. Ehehalt, I. Kralik

We present a nonperturbative dynamical study of $μ^+μ^-$ production in proton-nucleus and nucleus-nucleus collisions at SPS energies on the basis of the covariant transport approach HSD. For p + W reactions at 200 GeV bombarding energy the dimuon yield for invariant masses m $\leq $ 1.6 GeV is found to be dominated by the decays of the $η, ρ, ω$ and $Φ$ meso

A. N. Kamal, A. B. Santra, F. Ghoddoussi

Through a specific example of two-body color-favored charm decay, $D_s ^+ \rightarrow ϕπ^+$, we illustrate how an effective and complex (unitarized) $a_1$, denoted by $a_1^{U,eff}$, may be defined such that it includes nonfactorized, annihilation and inelastic final state interaction (fsi) effects. The procedure can be generalized to color-suppressed process

I. G. Knowles, T. Sjostrand, A. Blondel, A. Boehrer

This report is a survey on QCD Event Generator issues of relevance for LEP 2. It contains four main sections: a summary of experience from LEP 1, extrapolations to LEP 2 energies, Monte Carlo descriptions and standardization issues.

Vittorio Del Duca

Using the helicity formalism, we compute the corrections to the tree-level multigluon amplitudes in the high-energy limit, induced by the corrections to the multi-Regge kinematics, and we show that they coincide with the corresponding Fadin-Lipatov amplitudes at fixed helicities.

Torbjorn Sjostrand

Several topics of interest in soft photoproduction physics are discussed. These include jet universality issues (particle flavour composition), the subdivision into event classes, the buildup of the total photoproduction cross section and the effects of multiple interactions.

Dae Sung Hwang, Gwang-Hee Kim

We derive formulas for the decay constants $f_P$ and $f_V$ of pseudoscalar and vector mesons in the relativistic mock meson model. Using these formulas, we obtain $f_P$ and $f_V$ of $B_s$, $B_d$, $D_s$, and $D_d$ mesons as functions of the mock meson parameter $β$. Then by using the values of $β$ which are obtained by the variational method in the relativist

M. A. Stephanov

A recent Monte Carlo study of {\em quenched} QCD showed that the chiral condensate is non-vanishing above $T_c$ in the phase where the average of the Polyakov loop $P$ is complex. We show how this is related to the dependence of the spectrum of the Dirac operator on the boundary conditions in Euclidean time. We use a random matrix model to calculate the dens

E. M. Aitala, S. Amato, J. C. Anjos, J. A. Appel

We present asymmetries between the production of D+ and D- mesons in Fermilab experiment E791 as a function of xF and pt**2. The data used here consist of 74,000 fully-reconstructed charmed mesons produced by a 500 GeV/c pi- beam on C and Pt foils. The measurements are compared to results of models which predict differences between the production of heavy-qu

Pawel Walczak

Some curvature estimates are derived from geometrical data concerning quasi-conformality properties of some commuting linearly independent vector fields on a compact Riemannian manifold.

Cécile Monthus, Jean-Philippe Bouchaud

We study various models of independent particles hopping between energy `traps' with a density of energy barriers $ρ(E)$, on a $d$ dimensional lattice or on a fully connected lattice. If $ρ(E)$ decays exponentially, a true dynamical phase transition between a high temperature `liquid' phase and a low temperature `aging' phase occurs. More general

A. A. Odintsov, A. Vourdas

A mesoscopic Josephson junction interacting with a mode of non-classical microwaves with frequency $ω$ is considered. Squeezing of the electromagnetic field drastically affects the dynamics of Cooper tunneling. In particular, Bloch steps can be observed even when the microwaves are in the squeezed vacuum state with {\em zero} average amplitude of the field $

M. Vekic, S. R. White

We apply recently developed smooth boundary conditions to the quantum Monte Carlo simulation of the two-dimensional Hubbard model. At half-filling, where there is no sign problem, we show that the thermodynamic limit is reached more rapidly with smooth rather than with periodic or open boundary conditions. Away from half-filling, where ordinarily the simulat

Petra Barg

This paper presents an approach for the automatic acquisition of linguistic knowledge from unstructured data. The acquired knowledge is represented in the lexical knowledge representation language DATR. A set of transformation rules that establish inheritance relationships and a default-inference algorithm make up the basis components of the system. Since th

C. W. Shepherd, R. G. Carlberg, H. K. C. Yee, E. Ellingson

We present the results of a study of the two-point correlation function for a sample of field galaxies taken from the CNOCI cluster survey. The sample consists of 144 galaxies within a contiguous region of space subtending 225 square arcminutes. The objects have r-band magnitudes 17.0 < r < 21.7 and redshifts 0.21 < z < 0.53. The median redshift of the sampl

Nicholas B. Suntzeff, Robert P. Kraft

We present spectroscopic abundances and radial velocities for giant stars in the Galactic globular cluster omega Centauri based on the CaII infrared triplet. Two samples of stars were observed: 234 stars at M_V = 1.25 on the lower giant branch at radial distances between 8 and 23arcmin, and 145 stars at M_V = -1.3 at radial distances between 3 and 22arcmin.

Jordi Miralda-Escude, Eli Waxman

We derive observational consequences of the hypothesis that cosmic rays (CR&#39;s) of energy $>10^{19}eV$ originate in the same cosmological objects producing gamma-ray bursts (GRB&#39;s). Inter-galactic magnetic fields $\gtrsim 10^{-12} G$ are required in this model to allow CR&#39;s to be observed continuously in time by producing energy dependent delays i

Matthias Bartelmann, Ramesh Narayan, Stella Seitz, Peter Schneider

We present a novel method to recontruct the mass distribution of galaxy clusters from their gravitational lens effect on background galaxies. The method is based on a least-chisquare fit of the two-dimensional gravitational cluster potential. The method combines information from shear and magnification by the cluster lens and is designed to easily incorporat

Nicholas B. Suntzeff, Alistair R. Walker

The CTIO Prime Focus CCD instrument with an RCA CCD was in operation at the CTIO 4-m telescope for six years between 1982-1988. A large body of literature has been published based on CCD images taken with this instrument. We review the general properties of the now-retired PFCCD system to aid astronomers in the interpretation of the photometric data in the l

T. R. Kirkpatrick, D. Belitz

The quantum ferromagnetic transition at zero temperature in disordered itinerant electron systems is considered. Nonmagnetic quenched disorder leads to diffusive electron dynamics that induces an effective long-range interaction between the spin or order parameter fluctuations of the form r^{2-2d}, with d the spatial dimension. This leads to unusual scaling

Kenneth Dalton

We show that the energy-momentum four-vector of a planet, p = mu, is conserved during geodesic motion. Therefore, there is no exchange of energy-momentum with the gravitational field. We discuss the meaning of a gravitational field which is free of energy, momentum, and stress.

D. A. Verner, G. J. Ferland, K. T. Korista, D. G. Yakovlev

We present a complete set of analytic fits to the non-relativistic photoionization cross sections for the ground states of atoms and ions of elements from H through Si, and S, Ar, Ca, and Fe. Near the ionization thresholds, the fits are based on the Opacity Project theoretical cross sections interpolated and smoothed over resonances. At higher energies, the

F. X Lee, L. E. Wright, C. Bennhold, L. Tiator

Quasifree $η$ photoproduction from nuclei is studied in the Distorted Wave Impulse Approximation (DWIA). The elementary eta production operator contains Born terms, vector meson and nucleon resonance contributions and provides an excellent description of the recent low energy Mainz measurements on the nucleon. The resonance sector includes the $S_{11}(1535)$

Jeong-Man Park, T. C. Lubensky

We model membrane proteins as anisotropic objects characterized by symmetric-traceless tensors and determine the coupling between these order-parameters and membrane curvature. We consider the interactions between transmembrane proteins that respect up-down (reflection) symmetry of bilayer membranes and that have circular or non-circular cross-sectional area

Gang Su

Magnetic and superconducting pairing correlation functions in a general class of Hubbard models, the t-J model and a single-band Hubbard model with additional bond-charge interaction are investigated, respectively. Some rigorous upper bounds of the corresponding correlation functions are obtained. It is found that the decay of the spin-spin correlation funct

Matei Toma

We consider Poncelet pairs $(S,C)$, where $S$ is a smooth conic and $C$ is a degree$-c$ plane curve having the Poncelet property with respect to $S$. We prove that for $c>4$ the projection $(S,C)\mapsto C$ is generically one-to-one and use this to describe a birational model of the variety of Poncelet curves for $c$ odd.

Giovanni Felder, Alexander Varchenko

We describe representation theory of the elliptic quantum group $E_{τ,η}(sl_2)$. It turns out that the representation theory is parallel to the representation theory of the Yangian $Y(sl_2)$ and the quantum loop group $ U_q(\widetilde { sl }_2)$.

Gary T. Horowitz, Tsukasa Tada

We construct a new extreme black hole solution in toroidally compactified heterotic string theory. The black hole saturates the Bogomol&#39;nyi bound, has zero angular momentum, but nonzero electric dipole moment. It is obtained by starting with a higher dimensional rotating charged black hole, and compactifying one direction in the plane of rotation.

S. R. Vatsya

An extension of the classical action principle obtained in the framework of the gauge transformations, is used to describe the motion of a particle. This extension assigns many, but not all, paths to a particle. Properties of the particle paths are shown to impart wave like behaviour to a particle in motion and to imply various other assumptions and conjectu

L. S. F. Olavo

In this tenth paper of the series we aim at showing that our formalism, using the Wigner-Moyal Infinitesimal Transformation together with classical mechanics, endows us with the ways to quantize a system in any coordinate representation we wish. This result is necessary if one even think about making general relativistic extensions of the quantum formalism.

B. D. Anderson, L. A. C. Garcia, D. J. Millener, D. M. Manley

We report observations from the (p,n) reaction on 12C at 135 MeV. The experiment was performed with the beam-swinger neutron time-of-flight system at the Indiana University Cyclotron Facility. Neutrons were detected in large-volume plastic scintillation detectors located in three detector stations at 0 deg, 24 deg, and 45 deg with respect to the undeflected

Alexei G. Poltoratski

We use recent results on the boundary behavior of Cauchy integrals to study the Krein spectral shift of a rank one perturbation problem for self-adjoint operators. As an application, we prove that all self-adjoint rank one perturbations of a self-adjoint operator are pure point if and only if the spectrum of the operator is countable. We also study pairs of