October 1998 arXiv papers — page 13

Maria Papatriantafillou

A-manifolds and A-bundles are manifolds and vector bundles modelled on a projective finitely generated module over a topological algebra A. In this paper we investigate the conditions under which an A-bundle is provided with an A-valued hermitian structure and a compatible connection, in case A is a commutative complete locally m-convex C*-algebra with unit.

C. Maes, F. Redig, A. Van Moffaert

We discuss the status of recent Gibbsian descriptions of the restriction (projection) of the Ising phases to a layer. We concentrate on the projection of the two-dimensional low temperature Ising phases for which we prove a variational principle.

C. Maes, F. Redig, E. Saada, A. Van Moffaert

Considering the standard abelian sandpile model in one dimension, we construct an infinite volume Markov process corresponding to its thermodynamic (infinite volume) limit. The main difficulty we overcome is the strong non-locality of the dynamics. However, using similar ideas as in recent extensions of the standard Gibbs formalism for lattice spin systems,

Georgia Benkart, Seok-Jin Kang, Masaki Kashiwara

We develop a crystal base theory for the general linear Lie superalgebra $gl(m,n)$. We prove that any irreducible $U_q(gl(m,n))$-module in some category has a crystal base, and prove that its associated crystal base is parameterized by semistandard tableaux.

Krystyna Kuperberg

This paper contains a construction of a finite set X in the boundary of the unit 3-ball in R^3 whose minimal tree is knotted. The example answers Problem 5.17 in ''Problems in Low-dimensional Topology'' by Rob Kirby posed by Michael Freedman: ''Given a finite set of points X in the boundary of B^3, let T be a tree in B^3 of minimal le

Dave Bayer, Hara Charalambous, Sorin Popescu

In this short note we introduce a notion of extremality for Betti numbers of a minimal free resolution, which can be seen as a refinement of the notion of Mumford-Castelnuovo regularity. We show that extremal Betti numbers of an arbitrary submodule of a free S-module are preserved when taking the generic initial module. We relate extremal multigraded Betti n

Antun Balaz, Aleksandar Belic, Aleksandar Bogojevic

In a recently developed approximation technique for quantum field theory the standard one-loop result is used as a seed for a recursive formula that gives a sequence of improved Gaussian approximations for the generating functional. In this paper we work with the generic $ϕ^3+ϕ^4$ model in $d=0$ dimensions. We compare the first, and simplest, approximation i

Aleksandar Bogojevic, Dragan S. Popovic

We review a new prescription for calculating the Lagrangian path integral measure directly from the Hamiltonian Schwinger-Dyson equations. The method agrees with the usual way of deriving the measure in which one has to perform the path integration over momenta.

Aleksandar Bogojevic, Branislav Sazdovic, Olivera Miskovic

We show equivalence between the massive Thirring model and the sine-Gordon theory by gauge fixing a wider gauge invariant theory in two different ways. The exact derivation of the equivalence hinges on the existence of an underlying conformal symmetry. Previous derivations were all perturbative in mass (althought to all orders).

Fiorenzo Bastianelli, Olindo Corradini

The path integral representation of the transition amplitude for a particle moving in curved space has presented unexpected challenges since the introduction of path integrals by Feynman fifty years ago. In this paper we discuss and review mode regularization of the configuration space path integral, and present a three loop computation of the transition amp

D. G. C. McKeon, T. N. Sherry

The simplest supersymmetry (SUSY) algebra in four dimensional Euclidean space ($4dE$) has been shown to closely resemble the $N = 2$ SUSY algebra in four dimensional Minkowski space ($4dM$). The structure of the former algebra is examined in greater detail in this paper. We first present its Clifford algebra structure. This algebra shows that the momentum Ca

K. Schalm, P. van Nieuwenhuizen

We consider quantum-mechanical path integrals for non-linear sigma models on a circle defined by the string-inspired method of Strassler, where one considers periodic quantum fluctuations about a center-of-mass coordinate. In this approach one finds incorrect answers for the local trace anomalies of the corresponding $n$-dimensional field theories in curved

Z. Haba

We consider a quantization of relativistic wave equations which allows to treat quantum fields together with interacting particles at a finite time. We discuss also a dissipative interaction with the environment. We introduce a stochastic wave function whose dynamics is determined by a non-linear Schrödinger-type evolution equation in an additional time para

A. T. Filippov, A. P. Isaev

A path-integral representation for the kernel of the evolution operator of general Hamiltonian systems is reviewed. We study the models with bosonic and fermionic degrees of freedom. A general scheme for introducing boundary conditions in the path-integral is given. We calculate the path-integral for the systems with quadratic first class constraints and pre

Yishi Duan, Ying Jiang, Guohong Yang

In the light of $ϕ$-mapping method and topological current theory, the topological structure and the topological quantization of arbitrary dimensional topological defects are obtained under the condition that the Jacobian $J(ϕ/v) \neq 0$. When $J(ϕ/v)=0$, it is shown that there exist the crucial case of branch process. Based on the implicit function theorem

Kimyeong Lee

We show that the BPS configurations of uniform field strength can be interpreted as those for sheets of infinite number of BPS magnetic monopoles, and found that the number of normalizable zero modes per each magnetic monopole charge is four. We identify monopole sheets as the intersecting planes of D3 branes. Similar analysis on self-dual instanton configur

Won Tae Kim, Myung Seok Yoon

We study a three-dimensional symmetric Chern-Simons field theory with a general covariance and it turns out that the original Chern-Simons theory is just a gauge fixed action of the symmetric Chern-Simons theory whose constraint algebra belongs to fully first class constraint system. The Abelian Chern-Simons theory with matter coupling is studied for the con

Fred Cooper

We review our work on initial value problems in Quantum Field Theory which is based on using Schwinger's Closed Time Path formalism and a large-N expansion of the Path Integral.

A. M. Bernstein

It is demonstrated that there is a dynamic isospin breaking effect in the near threshold $γ^{*} N\to πN$ reaction due to the mass difference of the up and down quarks, which also causes isospin breaking in the $πN$ system. The photopion reaction is affected through final state $πN$ interactions (formally implemented by unitarity and time reversal invariance)

Harry J. Lipkin

Direct CP violation beyond the standard model can be produced in charged D decays to final states with a $K_S$ by small new physics contributions to the transitions $D^+ \to K^o X^+$, where $X^+$ denotes any positively charged hadronic state or transitions $D^+ \to K^o \bar K^o K^{(*)+}$, where $K^{(*)+}$ denotes any positive strange state. These transitions

Y. M. Cho, Y. -Y. Keum

We study the possibility that the dilaton -- the fundamental scalar field which exists in all the existing unified field theories -- plays the role of the dark matter of the universe. We find that the condition for the dilaton to be the dark matter strongly restricts its mass to be around 0.5 keV or 270 MeV. For the other mass ranges, the dilaton either unde

Dieter Schildknecht, Gerhard A. Schuler, Bernd Surrow

Including destructively interfering off-diagonal transitions of diffraction-dissociation type, we arrive at a formulation of GVD for exclusive vector-meson production in terms of a continuous spectral representation of dipole form. The transverse cross-section sigma_T for gamma* p -> V p behaves asymptotically as 1/Q^4, while R_V = sigma_L/sigma_T becomes as

Sanjay K. Ghosh, Sibaji Raha

The Jacobi polynomial has been advocated by many authors as a useful tool to evolve non-singlet structure functions to higher $Q^2$. In this work, it is found that the convergence of the polynomial sum is not absolute, as there is always a small fluctuation present. Moreover, the convergence breaks down completely for large $N$.

Ji-Ho Jang, Yeong Gyun Kim, Pyungwon Ko

We consider the branching ratios and CP asymmetry in the B meson decays into two pseudoscalar mesons in the generalized factorization approximation. We also investigate the possible effects of the enhanced chromomagnetic interaction b --> s g on these exclusive B meson decays that was suggested as a possible solution to the semileptonic branching ratio of B

Alan Kostelecky

A short review is given of some theoretical approaches to CPT violation. A potentially realistic possibility is that small apparent breaking of CPT and Lorentz symmetry could arise at the level of the standard model from spontaneous symmetry breaking in an underlying theory. Some experimental constraints are described.

Ian D Lawrie

I summarize the derivation of a set of Feynman rules appropriate for the perturbative description of the nonequilibrium dynamics of the symmetry-breaking phase transition in $λϕ^4$ theory in a Robertson-Walker universe. The approximation scheme I develop provides for a treatment of dissipative effects which are essential to an adequate description of the non

Balint Joo, Alan C Irving, James C. Sexton, Brian Pendleton

We present details of our investigation of the Parallel Tempering algorithm. We consider the application of action matching technology to the selection of parameters. We then present a simple model of the autocorrelations for a particular parallel tempered system. Finally we present numerical results from applying the algorithm to lattice QCD with O(a)-impro

Sunao Sakai, Atsushi Nakamura, Takuya Saito

Numerical results for the transport coefficients of quark gluon plasma are obtained by lattice simulations on on $16^3 \times 8$ lattice with the quench approximation where we apply the gauge action proposed by Iwasaki. The bulk viscosity is consistent with zero, and the shear viscosity is slightly smaller than the typical hadron masses. They are not far fro

Aleksandar Bogojevic, Dejan Stojkovic

We study the properties of a completely integrable deformation of the CGHS dilaton gravity model in two dimensions. The solution is shown to represent a singularity free black hole that at large distances asymptoticaly joins to the CGHS solution.

Inyong Cho, Alexander Vilenkin

It has been recently shown that topological defects can arise in symmetry breaking models where the scalar field potential $V(ϕ)$ has no minima and is a monotonically decreasing function of $|ϕ|$. Here we study the gravitational fields produced by such vacuumless defects in the cases of both global and gauge symmetry breaking. We find that a global monopole

A. S. Issaenko, A. B. Harris, T. C. Lubensky

We study the effective chiral interaction between molecules arising from quantum dispersion interactions within a model in which a) the dominant excited states of a molecule form a band whose width is small compared to the average excitation energy and b) biaxial orientational correlation between adjacent molecules can be neglected. Previous treatments of qu

Masaru Kato, Kazumi Maki

Making use of the Bogoliubov-de Gennes equation, we study the quasi-particle spectrum and the vortex core structure of a single vortex in quasi 2D s-wave superconductors for small $p_Fξ_0$, where $p_F$ is the Fermi momentum and $ξ_0=v_F/Δ_0$ is the coherence length($\hbar=1$). In particular we find that the number of bound states decreases rapidly for decrea

J. Cserti

We propose a consistent treatment of the applied external stress on a two-dimensional dislocation systems by using the analogy between our model and the layered superconductors. Using the results of a mathematically rigorous, real-space renormalization-group (RG) calculations in the latter model we extend the original model developed by Khantha {\it et al.}

Patrizia Benedetti, Roland Zeyher

The formation of a long-range Jahn-Teller distortion in undoped manganites is studied within the dynamical mean-field theory taking both electron-phonon and electron-electron interactions into account. We find that the observed insulating behavior at temperatures above the Jahn-Teller transition and the bond-length changes below it can most naturally by expl

Wolfgang Knospe, Ludger Santen, Andreas Schadschneider, Michael Schreckenberg

For single-lane traffic models it is well known that particle disorder leads to platoon formation at low densities. Here we discuss the effect of slow cars in two-lane systems. Surprisingly, even a small number of slow cars can initiate the formation of platoons at low densities. The robustness of this phenomenon is investigated for different variants of the

D. Neri, E. Silva, S. Sarti, R. Marcon

We discuss the excess conductivity above Tc due to renormalized order-parameter fluctuations in YBCO at microwave frequencies. We calculate the effects of the uniaxial anisotropy on the renormalized fluctuations in the Hartree approximation, extending the isotropic theory developed by Dorsey [Phys. Rev. B 43, 7575 (1991)]. Measurements of the real part of th

D. A. Garanin

Effects of the surface exchange anisotropy on ordering of ferromagnetic films are studied for the exactly solvable classical spin-vector model with D \to \infty components. For small surface anisotropy η&#39;_s << 1 (defined relative to the exchange interaction), the shift of T_c in a film consisting of N >> 1 layers behaves as T_c^{\rm bulk} - T_c(N) ~ (1/N

V. Drchal, V. Janis, J. Kudrnovsky

We study electronic properties of solids with correlated d electrons which could be described by a multiband Hubbard Hamiltonian in the weak-interaction case, $U/w<1$. The one-electron part of the many-body Hamiltonian is described by a tight-binding LMTO method. The many-body part is treated by non-selfconsistent FLEX-type approximations with adjusted chemi

Roberto Franzosi, Lapo Casetti, Lionel Spinelli, Marco Pettini

Certain geometric properties of submanifolds of configuration space are numerically investigated for classical lattice phi^4 models in one and two dimensions. Peculiar behaviors of the computed geometric quantities are found only in the two-dimensional case, when a phase transition is present. The observed phenomenology strongly supports, though in an indire

E. Hascoet, V. Loreto, H. J. Herrmann

We numerically solve the propagation of a shock wave in a chain of elastic beads with no restoring forces under traction (no-tension elasticity). We find a sequence of peaks of decreasing amplitude and velocity. Analyzing the main peak at different times we confirm a recently proposed scaling law for its decay.

G. Oron, H. J. Herrmann

We present exact results for the contact forces in a three dimensional static piling of identical, stiff and frictionless spheres. The pile studied is a pyramid of equilateral triangular base (``stack of cannonballs&#39;&#39;) with a FCC (face centered cubic) structure. We show in particular that, as for the two dimensional case, the pressure on the base of

G. D&#39;Anna, V. Berseth, L. Forro, A. Erb

In his the Comment, P. Ao affirms that his vortex many-body theory explains the observations reported in G. D&#39;Anna et al., Phys. Rev. Lett. 81, 2530 (1998). Indeed, we provide here some arguments to show the lack of a satisfactory explanation within the known theoretical frameworks.

Sune Jespersen, Ralf Metzler, Hans C. Fogedby

We consider Levy flights subject to external force fields. This anomalous transport process is described by two approaches, a Langevin equation with Levy noise and the corresponding generalized Fokker-Planck equation containing a fractional derivative in space. The cases of free flights, constant force and linear Hookean force are analyzed in detail, and we

Vaclav Janis

Single-band Hubbard model at criticality of the metal-insulator transition is studied using approximations derived from parquet theory. It is argued that only the electron-hole and interaction two-particle channels in the parquet algebra are relevant. A scheme is proposed how to reduce the parquet equations to a manageable form the complexity of which is com

Giovanni B. Bachelet, Andrea C. Cosentini

We discuss the main aspects of the fixed-node quantum Monte Carlo method for lattice fermions and its recent application to the problem of phase separation in the 2D Hubbard model, along with virtues, limitations and perspectives of this kind of approach.

M. Hilke, D. Shahar, S. H. Song, D. C. Tsui

Quite generally, an insulator is theoretically defined by a vanishing conductivity tensor at the absolute zero of temperature. In classical insulators, such as band insulators, vanishing conductivities lead to diverging resistivities. In other insulators, in particular when a high magnetic field (B) is added, it is possible that while the magneto-resistance

Koji Fukao, Yoshihisa Miyamoto

The glass transition temperature $T_g$ and the temperature $T_α$ corresponding to the peak in the dielectric loss due to the $α$-process have been simultaneously determined as functions of film thickness $d$ through dielectric measurements for thin films of polystyrene. A decrease of $T_g$ was observed with decreasing film thickness, while $T_α$ was found to

A. Mourachkine

We present electron-tunneling spectroscopy of oxygen over- and under-doped Bi-2212 single crystals in a temperature range between 14 K and 290 K using a break-junction technique. In over- and under-doped samples we observe a pseudogap with T* = 280 - 290 K and T* > 290 K, respectively. In order to explain the data we consider possible models for the pseudoga

Fotis K. Diakonos, Peter Schmelcher, O. Biham

We show that a recently proposed numerical technique for the calculation of unstable periodic orbits in chaotic attractors is capable of finding the least unstable periodic orbits of any given order. This is achieved by introducing a modified dynamical system which has the same set of periodic orbits as the original chaotic system, but with a tuning paramete

Victor S. L&#39;vov, Daniela Pierotti, Anna Pomyalov, Itamar Procaccia

We present a model of hydrodynamic turbulence for which the program of computing the scaling exponents from first principles can be developed in a controlled fashion. The model consists of $N$ suitably coupled copies of the &#34;Sabra&#34; shell model of turbulence. The couplings are chosen to include two components: random and deterministic, with a relative

Monica Cerruti-Sola, Roberto Franzosi, Marco Pettini

The exact form of the Jacobi -- Levi-Civita (JLC) equation for geodesic spread is here explicitly worked out at arbitrary dimension for the configuration space manifold M_E = {q in R^N | V(q) < E} of a standard Hamiltonian system, equipped with the Jacobi (or kinetic energy) metric g_J. As the Hamiltonian flow corresponds to a geodesic flow on (M_E,g_J), the

I. Kolokolov, V. Lebedev, M. Stepanov

We consider advection of a passive scalar theta(t,r) by an incompressible large-scale turbulent flow. In the framework of the Kraichnan model the whole PDF&#39;s (probability distribution functions) for the single-point statistics of theta and for the passive scalar difference theta(r_1)-theta(r_2) (for separations r_1-r_2 lying in the convective interval) a

Idit Zehavi

The power spectrum of mass density fluctuations is estimated from the Mark III and the SFI catalogs of peculiar velocities by applying a maximum likelihood analysis, using parametric models for the power spectrum and for the errors. Generalized CDM models with and without COBE normalization are used. The applications to the two different data sets give consi

Henry A. Kobulnicky, John Dickey

We report a detection of cold atomic hydrogen in the Magellanic Bridge using 21-cm absorption spectroscopy toward the radio source B0312-770. With a column density of N_HI=1.2E20 cm^-2, a maximum absorption optical depth of tau=0.10 and a maximum 21-cm emission brightness temperature of 1.4 K, this line of sight yields a spin temperature, T_s, between 20 K a

S. A. Laurent-Muehleisen, R. H. Becker, W. Brinkmann, J. Siebert

The advent of large area deep radio and X-ray surveys is leading to the creation of many new BL Lac samples. In particular, the ROSAT All-Sky, Green Bank and FIRST surveys are proving to be rich sources of new BL Lacs. We will discuss the methods used in four independent BL Lac searches based on these surveys. Comparison of the broadband spectral energy dist

A. P. Lobanov, T. P. Krichbaum, A. Witzel, A. Kraus

The luminous high-redshift (z=2.17) quasar S5 0836+710 has been observed at 5GHz with the VSOP. We compare the properties of three images obtained from the observation: a low-resolution ground array image (dynamic range 4600:1), a full-resolution VSOP image (900:1), and an image made with only the space baselines (200:1). The space baselines alone are suffic

M. P. Hobson, R. B. Barreiro, L. Toffolatti, A. N. Lasenby

We study the effect of extragalactic point sources on satellite observations of the cosmic microwave background (CMB). In order to separate the contributions due to different foreground components, a maximum-entropy method is applied to simulated observations by the Planck Surveyor satellite. In addition to point sources, the simulations include emission fro

MP Hobson, AN Lasenby

The maximum entropy method has been used to reconstruct images in a wide range of astronomical fields, but in its traditional form it is restricted to the reconstruction of strictly positive distributions. We present an extension of the standard method to include distributions that can take both positive and negative values. The method may therefore be appli

Arbab I. Arbab

We have investigated the cosmological implications of the bulk viscous cosmological model with variable G and $Λ$. These results are found to be compatible with the present observations. The classical cosmological tests for this model encompass the Freese et al ones. The model has some sprits of the Standard Model. The inflationary solution which solves the

James Chiang

We show that the spectral shape of the low energy tails found for the time-integrated spectra of gamma-ray bursts, even in the absence of strong synchrotron cooling, can be significantly softer than the $νF_ν\propto ν^{4/3}$ asymptote predicted by synchrotron shock models. As we have noted in a previous work, blast wave deceleration via interaction with ambi

C. P. Dullemond

The conditions for disk evaporation by electron thermal conduction are examined, using a simplified semi--analytical 1-D model. The model is based on the mechanism proposed by Meyer & Meyer-Hofmeister (1994) in which an advection dominated accretion flow evaporates the top layers from the underlying disk by thermal conduction. The evaporation rate is calcula

A. W. Jones, M. P. Hobson, A. N. Lasenby

Simulated observations of a $10\dg \times 10\dg$ field by the Microwave Anisotropy Probe (MAP) are analysed in order to separate cosmic microwave background (CMB) emission from foreground contaminants and instrumental noise and thereby determine how accurately the CMB emission can be recovered. The simulations include emission from the CMB, the kinetic and t

A. W. Jones, M. P. Hobson, P. Mukherjee, A. N. Lasenby

We study the effect of Galactic foregrounds with spatially varying spectral indices on analysis of simulated data from the Planck Satellite. We also briefly mention the effect the extra-galactic point sources have on the data analysis and summarise the most recent constraints on Galactic emission at GHz frequencies.

A. J. Norton, A. P. Beardmore

We present the results of a long ROSAT HRI observation of the candidate intermediate polar TW Pic. The power spectrum shows no sign of either the previously proposed white dwarf spin period or the proposed binary orbital period (1.996 hr and 6.06 hr respectively). The limits to the X-ray modulation are less than 0.3% in each case. In the absence of a coheren

Crystal L. Martin

Properties of starburst-driven outflows in dwarf galaxies are compared to those in more massive galaxies. Over a factor of roughly 10 in galactic rotation speed, supershells are shown to lift warm ionized gas out of the disk at rates up to several times the star formation rate. The amount of mass escaping the galactic potential, in contrast to the disk, does

David Montes, Lawrence W. Ramsey

We report the possible detection of a Li I 6708 AA line enhancement during an unusual long-duration optical flare in the recently discovered, X-ray/EUV selected, chromospherically active binary 2RE J0743+224. The Li I equivalent width (EW) variations follow the temporal evolution of the flare and large changes are observed in the intensity of the line. The m

Gabriele Ghisellini

Recent observational and theoretical results on blazars are presented and discussed. We are beginning to understand the rich phenomenology of blazars, and we are finding trends which will hopefully lead us to unveil the physics of these extreme sources. Limits and constraints on how jets originate can be derived by their intense and variable $γ$--ray emissio

Heino Falcke, Luis C. Ho, James S. Ulvestad, Andrew S. Wilson

A VLA survey of nearby LINER galaxies at 15 GHz has revealed the presence of a compact radio core in many sources. The cores seem to be correlated with the optical activity. Follow-up VLBA observations of the ten brightest sources confirm that these cores have brightness temperatures >10^8 Kelvin, thus confirming their AGN nature. The two brightest radio sou

M. Yu. Khlopov, R. V. Konoplich, R. Mignani, S. G. Rubin

The existence of macroscopic regions with antibaryon excess in the baryon asymmetric Universe with general baryon excess is the possible consequence of practically all models of baryosynthesis. Diffusion of matter and antimatter to the border of antimatter domains defines the minimal scale of the antimatter domains surviving to the present time. A model of d

Ari Laor

The ionizing continuum shape of quasars is generally not directly observable, but indirect arguments, based on photoionization models and thin accretion disk models suggest that it should peak in the extreme UV, and drop steeply into the soft X-ray regime. However, recent observations of very soft X-ray emission in low z quasars, and far UV emission of high

Heino Falcke, Peter L. Biermann

We have derived simplified equations for a freely expanding, pressure driven jet model as a function of jet power and applied it successfully to the radio cores in the black hole candidates GRS 1915+105, NGC 4258, and M81 which are observationally well defined systems, and to Sgr A*. By using equipartition assumptions, the model has virtually no free paramet

Edward A. Spiegel, Louis Tao

Beginning from a relatively simple set of dynamical equations for a fluid permeated by a radiative field strong enough to produce significant forces, we find the structure of plane-parallel equilibria and study their stability to small acoustic disturbances. In doing this, we neglect viscous effects and complications of nongreyness. We find that acoutic inst

Sanjay Jain, Sandeep Krishna

We consider the population dynamics of a set of species whose network of catalytic interactions is described by a directed graph. The relationship between the attractors of this dynamics and the underlying graph theoretic structures like cycles and autocatalytic sets is discussed. It is shown that when the population dynamics is suitably coupled to a slow dy

Andrew S. Fruchter

The optical transient (OT) associated with GRB~980329 was remarkably red. It has previously been concluded that this was the result of dust extinction in the host galaxy. However, an extinction model can only agree with the data if the $I$ band observations taken about 0.8 days after outburst are discounted; the flux density ratio between the $I$ and the $R$

Daniel Brace, Bogdan Morariu, Bruno Zumino

We investigate in the Matrix theory framework, the subgroup of dualities of the DLCQ of M-theory compactified on three-tori, which corresponds to T-duality in the auxiliary Type II string theory. We show how these dualities are realized in the supersymmetric Yang-Mills gauge theories on dual noncommutative three-tori.

A. A. Aligia

I generalize the concept of Berry&#39;s geometrical phase for quasicyclic Hamiltonians to the case in which the ground state evolves adiabatically to an excited state after one cycle, but returns to the ground state after an integer number of cycles. This allows to extend the charge Berry phase gamma_c related to the macroscopic polarization, to many-body sy

C. Glenn Boyd, Adam K. Leibovich, Ira Z. Rothstein

We present the leading order differential and total rates for J/ψproduction at LEP. By leading order we mean all terms of the form alpha_s[alpha_s log(M_Z^2/M_{psi}^2)]^n and alpha_s^{n+1} log^l(z^2) log^m(M_Z^2/M_{psi}^2), (l+m=2n-1), in the regions z=2E_psi/M_Z ~ O(1) and z << 1, respectively. In the intermediate region we interpolate using the available d

Jonathan Bagger, Alexander Galperin

In this talk we use nonlinear realizations to study the spontaneous partial breaking of rigid and local supersymmetry.

Peter Olsson, S. Teitel

We use the three dimensional uniformly frustrated XY model, as a model for a high temperature superconductor in an applied magnetic field, to explicitly measure the longitudinal correlation length xi_z in the vortex line liquid phase. We determine the scaling of xi_z with magnetic field and system anisotropy close to the vortex lattice melting transition. We

T. J. Allen, M. G. Olsson, S. Veseli

It is well known that a straight Nambu-Goto string is an exact solution of the equations of motion when its end moves in a circular orbit. In this paper we investigate the shape of a confining relativistic string for a general motion of its end. We determine analytically the shape of the curved string to leading order in deviation from straightness, and show

Felix Finster, Joel Smoller, Shing-Tung Yau

We consider for j=1/2, 3/2,... a spherically symmetric, static system of (2j+1) Dirac particles, each having total angular momentum j. The Dirac particles interact via a classical gravitational and electromagnetic field. The Einstein-Dirac-Maxwell equations for this system are derived. It is shown that, under weak regularity conditions on the form of the hor

S. L. Collier, W. R. Gibbs

We examine the scattering of charged pions from the trinucleon system at a pion energy of 180 MeV. The motivation for this study is the structure seen in the experimental angular distribution of back-angle scattering for pi+ 3He and pi- 3H but for neither pi- 3He nor pi+ 3H. We consider the addition of a double spin flip term to an optical model treatment an

D. R. Alves, A. Basu, K. H. Cook, D. L. Welch

This paper has been withdrawn

Jose Gaite

The relative entropy in two-dimensional field theory is studied on a cylinder geometry, interpreted as finite-temperature field theory. The width of the cylinder provides an infrared scale that allows us to define a dimensionless relative entropy analogous to Zamolodchikov's $c$ function. The one-dimensional quantum thermodynamic entropy gives rise to anothe

A. Cappelli, L. S. Georgiev, I. T. Todorov

The wave functions of the Haldane-Rezayi paired Hall state have been previously described by a non-unitary conformal field theory with central charge c=-2. Moreover, a relation with the c=1 unitary Weyl fermion has been suggested. We construct the complete unitary theory and show that it consistently describes the edge excitations of the Haldane-Rezayi state

John Ellis, Toby Falk, Keith A. Olive

We consider the effects of neutralino-stau coannihilations on the cosmological relic density of the lightest supersymmetric particle (LSP) $χ$ in the minimal supersymmetric extension of the Standard Model (MSSM), particularly in the constrained MSSM in which universal supergravity inputs at the GUT scale are assumed. For much of the parameter space in these

Thomas M. Brown, Henry C. Ferguson, Jean-Michel Deharveng, Robert I. Jedrzejewski

The ``UV upturn&#39;&#39; is a sharp rise in spectra of elliptical galaxies shortward of rest-frame 2500 A. It is a ubiquitous phenomenon in nearby giant elliptical galaxies, and is thought to arise primarily from low-mass evolved stars on the extreme horizontal branch and beyond. Models suggest that the UV upturn is a very strong function of age for these o

J. A. Casado

A model of multiparticle production in hadronic collisions at ultra-relativistic energies, based on the assumption of independent string fragmentation, reproduces the rapidity spectra of $Λ$ and $\barΛ$ in sulphur-sulphur collisions reported by the NA35 Collaboration. This is achieved after a reconsideration of the intermediate multi-string states and the st

Klaus Molmer, Anders Sorensen

We propose an efficient method to produce multi-particle entangled states of ions in an ion trap for which a wide range of interesting effects and applications have been suggested. Our preparation scheme exploits the collective vibrational motion of the ions, but it works in such a way that this motion need not be fully controlled in the experiment. The ions

Debashish Chowdhury, Dietrich Stauffer

We reformulate the Cont-Bouchaud model of financial markets in terms of classical &#34;super-spins&#34; where the spin value is a measure of the number of individual traders represented by a portfolio manager of an investment agency. We then extend this simplified model by switching on interactions among the super-spins to model the tendency of agencies gett

P. C. Stichel

We revisit Wigner&#39;s question about the admissible commutation relations for coordinate and velocity operators given their equations of motion (EOM). In more general terms we want to consider the question of how to quantize dynamically equivalent Hamiltonian structures. A unique answer can presumably be given in those cases, where we have a dynamical symm

Anders Sorensen, Klaus Molmer

We propose an implementation of quantum logic gates via virtual vibrational excitations in an ion trap quantum computer. Transition paths involving unpopulated, vibrational states interfere destructively to eliminate the dependence of rates and revolution frequencies on vibrational quantum numbers. As a consequence quantum computation becomes feasible with i

Sunao Sakai, Atsushi Nakamura, Takuya Saito

The $Λ$ parameter on the anisotropic lattice, the spatial and temperature coupling constant $g_σ$, $g_τ$ and their derivative with respaect to the the anisotropy parameter $ξ$ are studied perturbatively for the class of improved actions, which cover tree level Symanzik&#39;s, Iwasaki&#39;s and QCDTARO&#39;s improved actions. The $η(=g_τ/g_σ)$ becomes less th

E. L. Bratkovskaya, W. Cassing, L. A. Kondratyuk, A. Sibirtsev

Within the meson-exchange model we calculate $f_0$-meson production cross section in $\piN$ and $NN$ reactions and investigate the possibility for $f_0$ observation via the $K\bar{K}$ decay mode in $pp$ collisions. Our studies indicate that an extraction of the $f_0$ signal is unlikely due to the large background from other reaction channels.

Klaus Morawetz, Václav Špička, Pavel Lipavský, Gerd Kortemeyer

Within QMD simulations we demonstrate the effect of virial corrections on heavy ion reactions. Unlike in standard codes, the binary collisions are treated as non-local so that the contribution of the collision flux to the reaction dynamics is covered. A comparison with standard QMD simulations shows that the virial corrections lead to a broader proton distri

Ken-ji Hamada, Fumihiko Sugino

Using the background-metric independence for the traceless mode as well as the conformal mode, 4D quantum gravity is described as a quantum field theory defined on a non-dynamical background-metric. The measure then induces an action with 4 derivatives. So we think that 4-th order gravity is essential and the Einstein-Hilbert term should be treated like a ma

Tomonori Totani

We argue that gamma-ray bursts (GRBs) may be the origin of the cosmic gamma-ray background radiation observed in GeV range. It has theoretically been discussed that protons may carry a much larger amount of energy than electrons in GRBs, and this large energy can be radiated in TeV range by synchrotron radiation of ultra-high-energy protons (\sim 10^{20} eV)

Tomonori Totani

Some recent experiments detecting very high energy (VHE) gamma-rays above 10-20 TeV independently reported VHE bursts for some of bright gamma-ray bursts (GRBs). If these signals are truly from GRBs, these GRBs must emit a much larger amount of energy as VHE gamma-rays than in the ordinary photon energy range of GRBs (keV-MeV). We show that such extreme phen

Michael N. Leuenberger, Daniel Loss

We present a comprehensive derivation of the magnetization relaxation in a Mn12-acetate crystal based on thermally assisted spin tunneling induced by quartic anisotropy and weak transverse magnetic fields. The overall relaxation rate as function of the magnetic field is calculated and shown to agree well with data including all resonance peaks. The Lorentzia

V. J. Emery, S. A. Kivelson, O. Zachar

The classification of the ground-state phases of complex one-dimensional electronic systems is considered in the context of a fixed-point strategy. Examples are multichain Hubbard models, the Kondo-Heisenberg model, and the one-dimensional electron gas in an active environment. It is shown that, in order to characterize the low-energy physics, it is necessar