December 1995 arXiv papers — page 11

David H. Weinberg, Lars Hernquist, Neal Katz, Jordi Miralda-Escude

Cosmological simulations with gas dynamics suggest that the Lyman-alpha forest is produced mainly by "small scale structure" --- filaments and sheets that are the high redshift analog of today's galaxy superclusters. There is no sharp distinction between Lyman-alpha clouds and "Gunn-Peterson" absorption produced by the fluctuating IGM --

A. Jadczyk, G. Kondrat, R. Olkiewicz -

We prove that, contrary to the standard quantum theory of continuous observation, in the formalism of Event Enhanced Quantum Theory the stochastic process generating individual sample histories of pairs (observed quantum system, observing classical apparatus) is unique. This result gives a rigorous basis to the previous heuristic argument of Blanchard and Ja

C. Gomez, R. Hernandez, E. Lopez

The action of the $S$-duality $Sl(2,Z)$ group on the moduli of the Calabi-Yau manifold $W\IP^{12}_{11226}$ appearing in the rank two dual pair $(K^{3}\times T^{2}/W\IP^{12}_{11226})$ is defined by interpreting the $N\!=\!4$ to $N\!=\!2$ flow, for $SU(2)$ supersymmetric Yang-Mills, in terms of the Calabi-Yau moduli. The different singularity loci are mapped i

Hugo Garcia-Compean, Jerzy F. Plebanski, Maciej Przanowski

It is shown how some results on harmonic maps within the chiral model can be carried over to self-dual gravity. The WZW-like action for self-dual gravity is found.

Oleg A. Soloviev

It is shown that there exists a truly marginal deformation of the direct sum of two $G_k$ WZNW models at $k=-2c_V(G)$ (where $c_V(G)$ is the eigenvalue of the quadratic Casimir operator in the adjoint representation of the group $G$) which does not seem to fit the Chaudhuri-Schwartz criterion for truly marginal perturbations. In addition, a continuous family

D. Zanchi, H. J. Schulz

The problem of weakly correlated electrons on a square lattice is formulated in terms of one-loop renormalization group. Starting from the action for the entire Brillouin zone (and not with a low-energy effective action) we reduce successively the cutoff $Λ$ about the Fermi surface and follow the renormalization of the coupling $U$ as a function of three ene

W. Hollik

In this conference report a summary is given on the recent theoretical work that has contributed to improve the theoretical predictions for testing the standard model in present and future experiments. Precision calculations for the $Z$ resonance are reviewed and the status of the standard model is discussed in the light of the recent top discovery and of th

Ferenc Kun, Hans J. Herrmann

We present a model of solids made from polygonal cells connected via beams. We calculate the macroscopic elastic moduli from the beam and cell parameters. This modellisation is particularly suited for the simulation of fragmentation processes. We study the effects of an explosion inside a circular disk and the impact of a projectile and obtain the fragment s

Kenneth Dalton

We show that Einstein's gravitational field has zero energy, momentum, and stress. This conclusion follows directly from the gravitational field equations, in conjunction with the differential law of energy-momentum conservation $ T^{μν}_{;ν} = 0 $. Einstein rejected this conservation law despite the fact that it is generally covariant. We trace his reje

Z-M Sheng, H-B Gao

In this paper, the relationship between the sine-Gordon model with an integrable boundary condition and the Thirring model with boundary is discussed and the reflection $R$-matrix for the massive Thirring model, which is related to the physical boundary parameters of the sine-Gordon model, is given. The relationship between the the boundary parameters and th

Diptiman Sen

Motivated by the concept of ideal mutual statistics, we study a multispecies Calogero-Sutherland model in which the interaction parameters and masses satisfy some specific relations. The ground state is exactly solvable if those relations hold, both on a circle and on a line with a simple harmonic potential. In the latter case, the one-particle densities can

M. Dubois-Violette, J. Madore, T. Masson, J. Mourad

A general definition of a bimodule connection in noncommutative geometry has been recently proposed. For a given algebra this definition is compared with the ordinary definition of a connection on a left module over the associated enveloping algebra. The corresponding curvatures are also compared.

V. V. Mangazeev

In this paper we construct a discrete linear operator $K$ which transforms $A_2$ Macdonald polynomials into the product of two basic $3ϕ_2$ hypergeometric series with known arguments. The action of the operator $K$ on power sums in two variables can be reduced to a generalization of one particular case of the Bailey's summation formula for a very-well-po

George C. John, Vijay A. Singh

We propose a dual scale drift-diffusion model for interfacial growth and etching processes. The two scales are: (i) a depletion layer width surrounding the aggregate and (ii) a drift length.The interplay between these two antithetical scales yields a variety of distinct morphologies reported in electrochemical deposition of metals, viscous fingering in fluid

S. Gardner

I discuss the diffractive production of charmonium from nuclei and the anomalous nuclear attenuation --- termed ``color transparency'' --- attributed to such processes, focusing on the few tens of GeV energy regime germane to the ELFE project. A critical review of color transparency calculations is presented, and the major sources of uncertainty are

G. Kortemeyer, F. Daffin, W. Bauer

We investigate the stochastic Direct Simulation Monte Carlo method (DSMC) for numerically solving the collision-term in heavy-ion transport theories of the Boltzmann-Uehling-Uhlenbeck (BUU) type. The first major modification we consider is changes in the collision rates due to excluded volume and shadowing/screening effects (Enskog theory). The second effect

P. Magierski

The possibility of the appearance of the C$_{4}$ symmetry in the rotational bands is studied within the particle-rotor model. Allowing for a slight triaxiality of the rotor it is shown that the lowest states of the system for a sufficiently high spin possess the symmetry which allows to distinguish states differing by two units of angular momentum.

Carroll Guillory

We give several conditions on certain families of Douglas algebras that imply that the minimal envelope of the given algebra is the algebra itself. We also prove that the minimal envelope of the intersection of two Douglas algebras is the intersection of their minimal envelope.

J. W. Moffat

It is shown that the new version of nonsymmetric gravitational theory (NGT) corresponds in the linear approximation to linear Einstein gravity theory and antisymmetric field equations with a non-conserved string source current. The Hamiltonian for the antisymmetric field equations is bounded from below and describes the exchange of a spin $1^+$ massive vecto

David R. Morrison

If $X$ and $Y$ are a mirror pair of Calabi--Yau threefolds, mirror symmetry should extend to an isomorphism between the type IIA string theory compactified on $X$ and the type IIB string theory compactified on $Y$, with all nonperturbative effects included. We study the implications which this proposal has for the structure of the semiclassical moduli spaces

Felix M. Lev

It is shown that in the general case the canonical construction of the current operators in quantum field theory does not render a bona fide vector field since Lorentz invariance is violated by Schwinger terms. We argue that the nonexistence of the canonical current operators for spinor fields follows from a very simple algebraic consideration. As a result,

Tetsuyuki Ochiai

Using a contour integral representation we analyze the multi-instanton sector in two dimensional $U(N)$ Yang-Mills theory on a sphere and argue the role of multi-instanton in the large $N$ phase transition. In the strong coupling region at the large $N$ , we encounter ``singular saddle point''. Because of this situation, ``neutral'' configura

James V. Steele, Hidenaga Yamagishi, Ismail Zahed

The pion-nucleon sigma term is shown to be equal to the Goldberger-Treiman discrepancy at tree level. Its value estimated this way is very sensitive to the pion-nucleon coupling constant g_{pi NN}. This relation, when combined with the pion-nucleon S-wave scattering lengths, yields a new determination of g_{pi NN} at tree level. The results of a one-loop ana

S. R. Beane

The algebraic content of chiral symmetry constrains the strong interactions of mesons containing a single heavy quark. We show that the S-wave single-pion transition amplitudes of all heavy meson states are determined as a consequence of the participation of these states in reducible multiplets of unbroken $SU(2)_L\times SU(2)_R$. We find this representation

Youichi Yamada, Kaoru Hagiwara, Seiji Matsumoto

We discuss supersymmetric contributions to the electroweak precision measurements in the Minimal Supersymmetric Standard Model for two cases: the quark-lepton universality violation $δ_{q\ell}$ in charged currents and the ratio $R_b=Γ(Z\rightarrow b\bar{b})/Γ(Z\rightarrow \rm hadrons)$. The recent experimental data suggest deviations from the Standard Model

R. S. Willey

We provide an alternative derivation of a lower bound on the mass of the Higgs boson which is somewhat simpler and more direct than the derivation based on the effective potential. For one TeV cutoff, the result is the same. For high scale cutoff, the lower bound is increased by slightly more than the expected uncertainty of the calculation.

Zoltan Ligeti, Mark B. Wise

We propose a model-independent method to determine the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element $|V_{ub}|$ from exclusive $B$ and $D$ decays. Combining information obtainable from $B\to ρ\ell\barν_\ell$, $B\to K^*ν\barν$, $D\to ρ\bar\ellν_\ell$ and $D\to K^*\bar\ellν_\ell$, a determination of $|V_{ub}|$ is possible, with an uncertainty from

Loyal Durand, Kurt Riesselmann

The calculation of the leading electroweak corrections to physical transition matrix elements in powers of $M_H^2/v^2$ can be greatly simplified in the limit $M_H^2\gg M_W^2,\, M_Z^2$ through the use of the Goldstone boson equivalence theorem. This theorem allows the vector bosons $W^\pm$ and $Z$ to be replaced by the associated scalar Goldstone bosons $w^\p

J. Kwiecinski

The perturbative QCD predictions concerning deep inelastic scattering at low $x$ are summarized. The theoretical framework based on the leading log $1/x$ resummation and $k_t$ factorization theorem is described. The role of studying final states in deep inelastic scattering for revealing the details of the underlying dynamics at low $x$ is emphasised and som

C. S. Kim, S. Y. Choi

We study in detail the kinematics of semileptonic $M_{l3}$ ($M \rightarrow M^\prime l ν$) decay, considering only the new models preserving all the gauge symmetries of the Standard Model (SM), and assuming that neutrinos are massless and left-handed as in the SM. And we present a brief review of the recent theoretical progress on model independent constraint

Bernard Frois, Bernard Pire

A 15-30 GeV continuous beam electron facility has been proposed by nuclear physicists in Europe to study how color forces build up hadrons from quarks and gluons. This project and its physics case are briefly reviewed. The recommendations of NuPECC, the Nuclear Physics Committee of the European Science Foundation are presented.

A. Halprin, C. N. Leung, J. Pantaleone

We consider the effect of a long range, flavor changing tensor interaction of possible gravitational origin. Neutrino mixing experiments provide the most sensitive probe to date for such forces---testing the equivalence principle at levels below $10^{-20}$. Here we justify and generalize a formalism for describing such effects. The constraints from neutrino

M. N. Chernodub, M. I. Polikarpov, A. I. Veselov

We show that the monopole confinement mechanism in lattice gluodynamics may be a particular feature of the maximal abelian projection. We give an explicit example of the $SU(2) \rightarrow U(1)$ projection (the minimal abelian projection), in which the confinement is due to topological objects other than monopoles. We also discuss the string representation o

Tanmoy Bhattacharya, Rajan Gupta

We present preliminary results from simulations done on 170 $32^3 \times 64$ lattices at $β= 6.0$ using quenched Wilson fermions. This talk focuses on the $Q^2$ behavior of the form-factors, extrapolation in quark masses, dependence on renormalization scheme, and comparison with heavy-quark effective theory (HQET). Even though we cannot estimate errors due t

Rajan Gupta, Tanmoy Bhattacharya

This talk presents results of weak matrix elements calculated from simulations done on 170 $32^3 \times 64$ lattices at $β= 6.0$ using quenched Wilson fermions. We discuss the extraction of pseudoscalar decay constants $f_π$, $f_K$, $f_D$, and $f_{D_s}$, the form-factors for the rare decay $B \to K^* γ$, and the matrix elements of the 4-fermion operators rel

Tanmoy Bhattacharya, Rajan Gupta, Stephen Sharpe

We analyze the chiral behavior of the hadron spectrum obtained with quenched Wilson fermions on 170 $32^3 \times 64$ lattices at $β= 6.0$. We calculate masses of hadrons composed of both degenerate and non-degenerate quarks. We reduce the statistical errors in mass splittings by directly fitting to the ratio of correlation functions. We find significant devi

Margarita Garcia Perez, Pierre van Baal

We study the properties of the electroweak sphaleron on a finite lattice. The cooling algorithm for saddle points is used to obtain the static classical solutions of the SU(2)-Higgs field theory. Results are presented for $M_H=\infty, M_W, 0.75M_W$. After performing finite size scaling we find good agreement with the results obtained from variational approac

H. Suman, K. Schilling

We present a numerical study of the ghost propagators in Landau gauge for SU(2) and SU(3) gauge theories at $β$=2.7 and $β$=6.0, respectively. Analyzing different lattice sizes up to $32^4$, we find small finite size effects. Down to the smallest available momenta, we observe no evidence for dipole behaviour of the ghost propagators.

Rob Kusner, Nick Schmitt

The spinor representation is developed and used to investigate minimal surfaces in ${\bfR}^3$ with embedded planar ends. The moduli spaces of planar-ended minimal spheres and real projective planes are determined, and new families of minimal tori and Klein bottles are given. These surfaces compactify in $S^3$ to yield surfaces critical for the Möbius invaria

Hernán A. Makse, Albert-László Barabási, H. Eugene Stanley

We consider a one dimensional elastic string as a set of massless beads interacting through springs characterized by anisotropic elastic constants. The string, driven by an external force, moves in a medium with quenched disorder. We present evidence that the consideration of longitudinal fluctuations leads to nonlinear behavior in the equation of motion whi

A. W. Sandvik, E. Dagotto, D. J. Scalapino

The $S=1/2$ Heisenberg antiferromagnet in the ladder geometry is studied as a model for the spin degrees of freedom of SrCu$_2$O$_3$. The susceptibility and the spin echo decay rate are calculated using a quantum Monte Carlo technique, and the spin-lattice relaxation rate is obtained by maximum entropy analytic continuation of imaginary time correlation func

Hernán A. Makse, Glenn W. Davies, Shlomo Havlin, Plamen Ch. Ivanov

Sedimentary rocks have complicated permeability fluctuations arising from the geological processes that formed them. These permeability fluctuations significantly affect the flow of fluids through the rocks. We analyze data on two sandstone samples from different geological environments, and find that the permeability fluctuations display long-range power-la

Hernán A. Makse, Shlomo Havlin, Moshe Schwartz, H. Eugene Stanley

We propose a new method to generate a sequence of random numbers with long-range power-law correlations that overcomes known difficulties associated with large systems. The new method presents an improvement on the commonly-used methods. We apply the algorithm to generate enhanced diffusion, isotropic and anisotropic self-affine surfaces, and isotropic and a

A. W. Sandvik, D. J. Scalapino

A two-layer Heisenberg antiferromagnet is studied as a model of the bilayer cuprate YBa$_2$Cu$_3$O$_6$. Quantum Monte Carlo results are presented for the temperature dependence of the spin correlation length, the static structure factor, the magnetic susceptibility, and the $^{63}$Cu NMR spin-echo decay rate $1/T_{2G}$. As expected, when the ratio $J_2/J_1$

Xiaohui Wang, Hermann Grabert

We discuss the suppression of Coulomb charging effects on a small metallic island coupled to an electrode by a tunnel junction. At high temperatures the quantum corrections to the classical charging energy $E_c=e^2/2C$, where $C$ is the island capacitance, are evaluated. At low temperatures the large quantum fluctuations of the island charge cause a strong r

X. C. Xie, D. Z. Liu, J. K. Jain

In the composite fermion model of the fractional quantum Hall effect, composite fermions experience, in addition to the usual potential disorder, also a magnetic flux disorder. Motivated by this, we investigate the localization properties of a single fermion in two dimensions, moving in the presence of both potential and magnetic flux disorders, but with a n

Arthur P. Smith, George F. Bertsch

The transition strengths for the four infrared-active vibrations of charged C$_{60}$ molecules are evaluated in self-consistent density functional theory using the local density approximation. The oscillator strengths for the second and fourth modes are strongly enhanced relative to the neutral C$_{60}$ molecule, in good agreement with the experimental obser

Carlos J. Camacho

We solve a model that takes into account entropic barriers, frustration, and the organization of a protein-like molecule. For a chain of size $M$, there is an effective folding transition to an ordered structure. Without frustration, this state is reached in a time that scales as $M^λ$, with $λ\simeq 3$. This scaling is limited by the amount of frustration w

X. C. Xie, D. Z. Liu

We study disorder induced transition between quantum Hall states and insulator state in a {\it lattice} model. We find the positions of the extended states do not change as disorder strength is varied. As a consequence, there are direct transitions from all Landau level quantum Hall states to insulator states, in contrast to the global phase diagram from ear

Darren J Wilkinson

In this thesis, a Bayes linear methodology for the adjustment of covariance matrices is presented and discussed. A geometric framework for quantifying uncertainties about covariance matrices is set up, and an inner-product for spaces of random matrices is motivated and constructed. The inner-product on this space captures aspects of our beliefs about the rel

M. Kibler, Yu. F. Smirnov

A purely group-theoretical approach (for which the symmetric group plays a central rôle), based upon the use of properties of fractional-parentage coefficients and isoscalar factors, is developed for the derivation of the Coulomb energy averaged over the states, with a definite spin, arising from an atomic configuration $n \ell^N$.

Puragra Guhathakurta, Brian Yanny, Donald P. Schneider, John N. Bahcall

We describe images of the center of the dense globular cluster M15 (NGC 7078) obtained with the Hubble Space Telescope Wide Field and Planetary Camera 2 (WFPC2). Data taken in the F336W, F439W, and F555W filters (approximately U, B, and V) are used to study the surface density distribution of the $\sim3\times10^4$~stars detected in a 5~arcmin$^2$ region with

Xiang-Ping Wu, Shude Mao

Using a singular isothermal sphere model for the matter distribution of foreground clusters of galaxies, we study the statistics of giant arcs in flat cosmologies with and without a cosmological constant. We find that the relative number of arcs predicted within $z=1$ in a universe with $Ω_0=0.3$ and $λ_0 \equiv Λ/(3H_0^2)=0.7$ is a factor of $\sim2$ larger

Matthias Steinmetz

A review on numerical simulations of galaxy formation is given. Different numerical methods to solve collisionless and gas dynamical systems are outlined and one particular simulation technique, Smoothed Particle Hydrodynamics, is discussed in some detail. After a short discussion of the most relevant physical processes which affect the dynamics of the gas,

P. C. Schmidtke, A. P. Cowley, T. K. McGrath, J. B. Hutchings

Photometric observations of the supersoft X-ray source 1E 0035.4-7230 obtained during two years reveal that the very blue optical counterpart (V (maximum)=20.2, B-V=-0.15, U-B=-1.06) undergoes nearly sinusoidal variations with a period of 0.1719256 days and an amplitude of Delta V~0.3 mag. ROSAT observations show the X-rays vary with approximately the same p

C. M. Baugh

We present a determination of the real space correlation function for galaxies in the APM Survey, with magnitudes in the range $17 < b_J < 20$. We recover a power law form for the correlation function $ξ(r) = (r/4.5)^{-1.7}$ on scales $r < 4 Mpc/h$, for a flat universe and clustering that is fixed in comoving coordinates.If we assume that clustering evolves

J. Greiner, R. Danner, N. Bade, G. A. Richter

We have discovered four AGN in the ROSAT all-sky-survey data with very steep X-ray spectra. We apply several models to these X-ray spectra with emphasis on warm absorber models which give an adequate description of the data. We report on the follow-up optical and radio observations which allow the identification of three of these objects as Narrow Line Seyfe

Guinevere Kauffmann, Adi Nusser, Matthias Steinmetz

We outline a simple approach to understanding the physical origin of bias in the distribution of galaxies relative to that of dark matter. The first step is to specify how collapsed, virialized halos of dark matter trace the overall matter distribution. The next step is to make a connection between halos and the luminous galaxies we observe. We appeal to the

Bumsig Kim

Using Quot schemes and a localization theorem we study Gromov-Witten invariants for partial flag varieties. The strategy is to extend A. Bertram&#39;s result of Gromov-Witten invariants for special Schubert varieties of Grassmannians to the case of partial flag varieties. To do so a Grothendieck&#39;s Quot scheme is generalized for flags and proven to be an

Mark Gross

A primitive Calabi-Yau threefold is a non-singular Calabi-Yau threefold which cannot be written as a crepant resolution of a singular fibre of a degeneration of Calabi-Yau threefolds. These should be thought as the most basic Calabi-Yau manifolds; all others should arise through degenerations of these. This paper first continues the study of smoothability of

E. Gaztanaga, P. Mahonen

A basic ingredient to understand large scale fluctuations in our present day Universe is the initial conditions. Using N-body simulations, we compare the clustering that arises from Gaussian and non-Gaussian initial conditions. The latter is motivated by a global texture model which has initial $J$-order correlations $\xibar_J$ close to the strongly non-Gaus

W. Vogelsang

We perform a new calculation of the polarized next-to-leading order splitting functions, using the method developed by Curci, Furmanski and Petronzio. We confirm the results of the recent calculation by Mertig and van Neerven.

B. Sarel, L. P. Horwitz

We present a formulation for the construction of first order equations which describe particles with spin, in the context of a manifestly covariant relativistic theory governed by an invariant evolution parameter; one obtains a consistent quantized formalism dealing with off-shell particles with spin. Our basic requirement is that the second order equation i

Zhi-zhong Xing

$D^0-\bar{D}^0$ mixing leads to the mass and width differences in the mass eigenstates of $D^0$ and $\bar{D}^0$ mesons (measured by parameters $x^{~}_D$ and $y^{~}_D$ respectively), but their magnitudes cannot be reliably predicted by the standard model. We show that it is possible to separately determine $x^{~}_D$ and $y^{~}_D$ through {\it time-integrated}

Zhi-zhong Xing

We calculate the time-dependent and time-integrated decay rates of $(D^0\bar{D}^0)\rightarrow (K^{\pm}π^{\mp})(l^{\pm}X^{\mp})$ at the $ψ(3.77)$ and $ψ(4.14)$ resonances. The possibilities to distinguish between the effects of $D^0-\bar{D}^0$ mixing and doubly Cabibbo suppressed decay (DCSD) are illustrated, and the signal of $CP$ violation induced by the in

M. Alishahiha, F. Ardalan, F. Mansouri

We present the hyper-elliptic curve describing the moduli space of the N=2 supersymmetric Yang-Mills theory with the $G_2$ gauge group. The exact monodromies and the dyon spectrum of the theory are determined. It is verified that the recently proposed solitonic equation is also satisfied by our solution.

A. Dimakis, F. Mueller-Hoissen

A construction of conservation laws for chiral models (generalized sigma-models on a two-dimensional space-time continuum using differential forms is extended in such a way that it also comprises corresponding discrete versions. This is achieved via a deformation of the ordinary differential calculus. In particular, the nonlinear Toda lattice results in this

I. Antoniadis, H. Partouche, T. R. Taylor

We study spontaneous supersymmetry breaking in N=2 globally supersymmetric theories describing a system of abelian vector multiplets. We find that the most general form of the action admits, in addition to the usual Fayet-Iliopoulos term, a magnetic Fayet-Iliopoulos term for the auxiliary components of dual vector multiplets. In a generic case, N=2 supersymm

N. G. Deshpande, Xiao-Gang He

Contrary to the conventional belief, time integrated asymmetry are measurable in selected final states in the neutral $B$ system at symmetric $e^+e^-$ colliders. They occur due to the interplay of weak and strong phases of two different amplitudes in addition to the $B^0 - \bar B^0$ mixing. Observation of these asymmetries would be evidence for direct CP vio

Zhi-zhong Xing

$D^0-\bar{D}^0$ mixing at a detectable level requires the presence of new physics and may lead to some observable effects in weak decays of $B$ mesons. We show that $CP$ violation induced by $D^0-\bar{D}^0$ mixing can manifest itself in the decay-rate asymmetry of $B^+_u\rightarrow D_{L(H)}l^+ν^{~}_l$ vs $B^-_u\rightarrow D_{L(H)}l^-\barν^{~}_l$. A rephasing

A. V. Smirnov, A. M. Bratkovsky

We have performed the first ab-initio calculations of a possible complex non-collinear magnetic structure in aluminium-rich Al-Mn liquids within the real-space tight-binding LMTO method. In our previous work we predicted the existence of large magnetic moments in Al-Mn liquids [A.M. Bratkovsky, A.V. Smirnov, D. N. Manh, and A. Pasturel, \prb {\bf 52}, 3056 (

Eric G. Blackman

Many extended extragalactic radio sources require a local {\it in situ\/} acceleration mechanism for electrons, in part because the synchrotron lifetimes are shorter than the bulk travel time across the emitting regions. If the magnetic field in these sources is localized in flux tubes, reconnection may occur between regions of plasma $\be$ (ratio of particl

Kyungsik Kang, Pierre Valin

We find that the UA4/2 measurements on the real part of the forward $p \bar p$ scattering amplitude and total cross section are consistent with each other and also with the standard picture of the Pomeron of either ${\it ln} ^2 s$ or ${\it ln} s$ type. However the asymptotic $σ_T (s)$ behavior obtained from the {\it ad hoc} parametrization fit to the $p \bar

Eugene Demler, Shou-Cheng Zhang, Nejat Bulut, Douglas J. Scalapino

In this series of papers we present a detailed study of the particle--particle collective excitations of the Hubbard model, and their contribution to the density and spin excitation spectrum. In the first paper, we shall investigate the singlet particle--particle pair with momentum $(π,π)$, the $η$ particle, of the negative--$U$ Hubbard model. We review thre

M. B. Plenio, P. L. Knight

We investigate the time T a quantum computer requires to factorize a given number dependent on the number of bits L required to represent this number. We stress the fact that in most cases one has to take into account that the execution time of a single quantum gate is related to the decoherence time of the qubits that are involved in the computation. Althou

N. V. Krasnikov, A. A. Pivovarov

We propose a parameterization for contributions of an infinite set of diagrams (bubble chains) into physical observables represented as integrals of running coupling constant over the finite region in momentum space. The perturbation theory part of contributions is rendered well-defined by the principal value prescrition for treating the Landau pole while th

V. Celebonovic

The chemical potential of the electron gas on a one-dimensional lattice is determined within the discrete Hubbard model. The result will have applications in studies of transport properties of quasi one-dimensional organic conductors such as the Bechgaard salts.

Michael Stone

The topological solitons, or ``skyrmions&#39;&#39;, in a planar ferromagnet experience a Magnus force proportional to the product of their velocity and the surrounding magnetization. It has been suggested that the charged quasiparticles near filling factor $ν=1$ in the $GaAs$ quantum Hall effect are skyrmions. If so we might expect this spin-induced Magnus f

M. Meierovich, A. Mushinski, M. P. Nightingale

In a previous paper (http://www.phys.uri.edu/people/nightingale/publications.html, chem-ph/9406003) we developed a form of variational trial wave function and applied it to van der Waals clusters: five or less atoms of Ar and Ne modeled by the Lennard-Jones potential. In addition, we tested the trial functions for a hypothetical, light atom resembling Ne but

T. Negadi, M. Kibler

The $D$-dimensional Coulomb system serves as a starting point for generating generalized atomic shells. These shells are ordered according to a generalized Madelung rule in $D$ dimensions. This rule together with an {\it Aufbau Prinzip} is applied to produce a $D$-dimensional periodic table. A model is developed to rationalize the ordering of the shells pred

D. J. Fixsen, E. S. Cheng, D. A. Cottingham, W. C. Folz

We report on the characteristics and design details of the Medium Scale Anisotropy Measurement (MSAM), a millimeter-wave, balloon-borne telescope that has been used to observe anisotropy in the Cosmic Microwave Background Radiation (CMBR) on 0\fdg5 angular scales. The gondola is capable of determining and maintaining absolute orientation to a few arcminutes

Ted von Hippel

Modern instrumentation makes it possible to measure the mass to radius ratio for main sequence stars in open clusters from gravitational redshifts. For stars where independent information is available for either the mass or the radius, this application of general relativity directly determines the other quantity. Applicable examples are: 1) measuring the rad

Edmond L. Berger, Harry Contopanagos

A calculation of the total cross section for top quark production in hadron-hadron collisions is presented based on an all-orders perturbative resummation of initial-state gluon radiative contributions to the basic quantum chromodynamics subprocesses. Principal-value resummation is used to evaluate all relevant large threshold contributions. In this method t

Richard Hain

This is a significant revision of the early version of this paper which was posted last December. The speculative section has been removed in light of some recent results of Morita and Kawazumi. Numerous typos have been fixed. The companion paper &#34;The Hodge de Rham Theory of Relative Malcev Completion&#34; has just been posted.

Katherine Freese, Tony Gherghetta, Hideyuki Umeda

It is tempting to inflate along one of the many flat directions that arise in supersymmetric theories. The required flatness of the potential to obtain sufficient inflation and to not overproduce density fluctuations occurs naturally. However, the density perturbations (in the case of a single moduli field) that arise from inflaton quantum fluctuations are t

E. V. Shuryak

Recent experiments with trapped cooled atoms have produced evidences for Bose-Einstein condensation. Among the atoms used are $^7Li$ ones, with attractive low energy interaction. Stability of their condensate is studied, with a conclusion that for a number of atoms below the critical value there exist a metastable minimum, separated from collapse by a potent

M. Rugers, C. J. Hogan

We present a new analysis of a Keck spectrum of Q0014+813, with a new model of the $z=3.32$ absorbing cloud. We fit Lyman series absorption of the dominant HI components, including components identified with hydrogen and associated deuterium at two discrete velocities, with thermal line broadening of each species. The deuterium features are too narrow to be

Craig J. Hogan

Quasar absorption lines now permit a direct probe of deuterium abundances in primordial material, with the best current estimate $ (D/H)=1.9\pm 0.4 \times 10^{-4}$. If this is the universal primordial abundance $(D/H)_p$, Standard Big Bang Nucleosynthesis yields an estimate of the mean cosmic density of baryons, $η_{10}= 1.7\pm 0.2$ or $ Ω_b h^2= 6.2\pm 0.8\

Thierry Giamarchi, Pierre Le Doussal

We study periodic lattices, such as vortex lattices, driven by an external force in a random pinning potential. We show that effects of static disorder persist even at large velocity. It results in a novel moving glass state with topological order analogous to the static Bragg glass. The lattice flows through well-defined, elastically coupled, {\it % static}

German Sierra

The well known Haldane map from spin chains into the $O(3)$ non linear sigma model is generalized to the case of spin ladders. This map allows us to explain the different qualitative behaviour between even and odd ladders, exactly in the same way it explains the difference between integer and half-integer spin chains. Namely, for even ladders the topological

M. D. Maia

It is shown that a space-time hypersurface of a 5-dimensional Ricci-flat space-time has its energy momentum tensor algebrically related to its extrinsic curvature and to the Riemann curvature of the embedding space. It is also seen that the Einstein-Maxwell field does not arise naturally from this geometry, so that a Kaluza-Klein model based on it would requ

G. I. Smirnov

It is shown that the latest results from the NMC (CERN) and E665 (Fermilab) groups on $F_2^A(x)/F_2^D(x)$ obtained in the shadowing region bring new evidence of the universal $A$ dependence of distortions made in a free-nucleon structure function by a nuclear medium. The observed universality implies that one can consider separately hard ($A\leq$ 4) and soft

Anton Deitmar

Using the Arthur-Selberg trace formula we express the index of a Dirac operator on an arithmetic quotient over a totally real field with at least two real embeddings as the integral over the index form plus a sum of orbital integrals. For the Euler operator these orbital integrals are shown to vanish for products of rank one spaces. In this case the index th

G. Grunberg

The connection between renormalons and power corrections is investigated for the typical infrared renormalon integral assuming the effective coupling constant has an infrared fixed point of an entirely perturbative origin. It is shown that even then the full answer differs from the Borel sum by a power correction. A comparaison with the analogue results when

I. Heckenberger, K. Schmuedgen

For bicovariant differential calculi on quantum groups various notions on connections and metrics (bicovariant connections, invariant metrics, the compatibility of a connection with a metric, Levi-Civita connections) are introduced and studied. It is proved that for the bicovariant differential calculi on $SL_{q}(N)$, $O_{q}(N)$ and $Sp_{q}(N)$ from the clas

A. C. Avram, P. Candelas, D. Jancic, M. Mandelberg

We show that the moduli space of all Calabi-Yau manifolds that can be realized as hypersurfaces described by a transverse polynomial in a four dimensional weighted projective space, is connected. This is achieved by exploiting techniques of toric geometry and the construction of Batyrev that relate Calabi-Yau manifolds to reflexive polyhedra. Taken together

S. Kachru, E. Silverstein

We study a class of four-dimensional N=1 heterotic string theories which have nontrivial quantum dynamics arising from asymptotically free gauge groups. These models are obtained by orbifolding 4d N=2 heterotic/type II dual pairs by symmetries which leave unbroken products of nonabelian gauge groups (without charged matter) in a ``hidden sector&#39;&#39; on

Jose M Figueroa-O&#39;Farrill, Sonia Stanciu

We present a derivation of the N=1 and N=2 superconformal coset constructions starting from a supersymmetric WZW model where a diagonal subgroup has been gauged. We work in the general framework of self-dual (not necessarily reductive) Lie algebras; but even in the reductive case these results are new. We show that the BRST cohomology of the gauged supersymm

Yuri B. Suris

A discretization of the peakons lattice is introduced, belonging to the same hierarchy as the continuous--time system. The construction examplifies the general scheme for integrable discretization of systems on Lie algebras with $r$--matrix Poisson brackets. An initial value problem for the difference equations is solved in terms of a factorization problem i

Thang T. Q. Le, Jun Murakami, Tomotada Ohtsuki

We construct an invariant of 3-manifolds using a modification of the Kontsevich integral and Kirby&#39;s calculus. This invariant, as expected in perturbative Chern-Simon theory, takes values in the algebra of oriented 3-valent graphs. This algebra is a Hopf algebra, graded by half the number of vertices in 3-valent graphs. The degree 1 term of the invariant