December 1997 arXiv papers — page 10

W. D. Heiss, R. G. Nazmitdinov

Shell structure in the single particle spectrum of deformed harmonic oscillator potentials when a term proportional to $(\vec L)^2$ is added is analyzed for a large particle number. A scaling law which gives a dividing line between regular and chaotic behavior in terms of energy, deformation and strength of the $(\vec L)^2$ term has been found. According to

R. Seviour, C. J. Lambert, M. Leadbeater

Experiments on hybrid superconducting normal-metal structures have revealed that even in the absence of tunnel junctions the onset of superconductivity can lead to a decrease in the electrical conductance by an amount many orders of magnitude greater than $e^2/h$. In this Letter we provide a theory of this phenomenon which shows that it originates from an in

M. A. Muñoz, A. Gabrielli, H. Inaoka, L. Pietronero

We introduce a new simple hierarchically constrained model of slow relaxation. The configurational energy has a simple form as there is no coupling among the spins defining the system; the associated stationary distribution is an equilibrium, Gibbsian one. However, due to the presence of hierarchical constraints in the dynamics the system is found to relax t

J. -P. Bouchaud, N. Sagna, R. Cont, N. El-Karoui

This paper contains a phenomenological description of the whole U.S. forward rate curve (FRC), based on an data in the period 1990-1996. We find that the average FRC (measured from the spot rate) grows as the square-root of the maturity, with a prefactor which is comparable to the spot rate volatility. This suggests that forward rate market prices include a

Sumio Ishihara, Sadamichi Maekawa

We study theoretically the anomalous X-ray scattering as a new probe to observe the orbital orderings and excitations in perovskite manganites. The scattering matrix is given by the virtual electronic excitations from Mn $1s$ level to unoccupied Mn $4p$ level. We find that orbital dependence of the Coulomb interaction between Mn $3d$ and Mn $4p$ electrons is

Sumio Ishihara, Satoshi Okamoto, Sadamichi Maekawa

Pressure effects on the charge and spin dynamics in the bilayer manganite compounds $La_{2-2x}Sr_{1+2x}Mn_2O_7$ are studied theoretically by taking into account the orbital degrees of freedom. The orbital degrees are active in the layered crystal structure, and applied hydrostatic pressure stabilizes the $3d_{x^2-y^2}$ orbital in comparison with $3d_{3z^2-r^

Edward McCann, Igor V. Lerner

We consider the distribution of conductance fluctuations in disordered quantum dots with single channel leads. Using a perturbative diagrammatic approach, valid for continuous level spectra, we describe dephasing due to processes within the dot by considering two different contributions to the level broadening, thus satisfying particle number conservation. I

Miguel A. Muñoz

We present a comparison of three different types of Langevin equation exhibiting absorbing states: the Langevin equation defining the Reggeon field theory, one with multiplicative noise, and a third type in which the noise is complex. Each one is found to describe a different underlying physical mechanism; in particular, the nature of the different absorbing

Paolo Politi, Maria Gloria Pini

We study the effect of dipolar interactions on a magnetic striped monolayer with a microscopic unit cell of square symmetry, and of size $(N_x\times N_y)$ spins. Even if the aspect ratio $r=N_x/N_y$ is very large, an in-plane shape anisotropy is always negligible, except if $N_y$ is fairly small $(N_y<40)$. In-plane domains are not possible, except for value

Walter Genovese, Miguel A. Muñoz, J. M. Sancho

A new simple model exhibiting a noise-induced ordering transition (NIOT) and a noise-induced disordering transition (NIDT), in which the noise is purely multiplicative, is presented. Both transitions are found in two as well as in one dimension (where they had not been previously reported). We show analytically and numerically that the critical behavior of t

J. M. Pitarke, A. G. Eguiluz

We report an ab initio evaluation of the surface energy of a simple metal, performed via a coupling-constant integration over the dynamical density-response function. The rapid rate of change of the electron density at the surface is treated exactly. Long-range correlations are treated self-consistently in the random-phase approximation; short range correlat

Andras Czirok, Albert-Laszlo Barabasi, Tamas Vicsek

We demonstrate that a system of self-propelled particles (SPP) exhibits spontaneous symmetry breaking and self-organization in one dimension, in contrast with previous analytical predictions. To explain this surprising result we derive a new continuum theory that can account for the development of the symmetry broken state and belongs to the same universalit

C. Basu, C. M. Canali, V. E. Kravtsov, I. V. Yurkevich

The level curvature distribution function is studied both analytically and numerically for the case of T-breaking perturbations over the orthogonal ensemble. The leading correction to the shape of the curvature distribution beyond the random matrix theory is calculated using the nonlinear supersymmetric sigma-model and compared to numerical simulations on th

F. Y. Wu, Wentao T. Lu

Duality relations for the correlation functions of $n$ sites on the boundary of a planar lattice are derived for the $(N_α, N_β)$ model of Domany and Riedel for $n=2,3$. Our result holds for arbitrary lattices which can have nonuniform interactions.

S. N. Dorogovtsev

Spiral (gyrotropic) percolation which is related to the behavior of an electron system in strong magnetic fields is studied. It is shown that the scaling behavior area near the percolation threshold is anomalously narrow. The percolation threshold is higher than in a system with usual isotropic percolation (i.e., it is at higher concentrations of undamaged s

James S. Graber

The interior of gravitationally collapsed objects in alternate theories of gravity in which event horizons and singularities do not occur in strong field gravity were generically investigated. These objects, called red holes, were found to contain dynamic configurations of matter, radiation and spacetime similar to inside out accretion disks well inside the

F. Rigaut, D. Salmon, R. Arsenault, J. Thomas

Extensive results from the commissioning phase of PUEO, the adaptive optics instrument adaptor for the Canada-France-Hawaii telescope, are presented and discussed. Analyses of more than 750 images recorded with a CCD and a near-IR camera on 16 nights in wavelengths from B to H are used to derive the properties of the compensated wavefront and images in a var

Demosthenes Kazanas, Xin-Min Hua

We present model light curves, Power Spectral Densities (PSD) and time lags of accreting Black Hole Candidates (BHC) based on a recent model of these sources. According to our model the observed variability is due, to a large extent, to the stochastic nature of Comptonization, the basic process responsible also for the emission of high energy radiation. Our

David L. Band

Gamma-ray bursts are transient events from beyond the solar system. Besides the allure of their mysterious origin, bursts are physically fascinating because they undoubtedly require exotic physics. Optical transients coincident with burst positions show that some, and probably all, bursts originate at cosmological distances, and not from a large Galactic hal

Robert J. Scherrer, David H. Weinberg

While it is well-known that &#34;biased galaxy formation&#34; can increase the strength of galaxy clustering, it is less clear whether straightforward biasing schemes can change the shape of the galaxy correlation function on large scales. Here we consider &#34;local&#34; biasing models, in which the galaxy density field $δ_g$ at a point is a function of the

P. T. Zycki, C. Done, D. A. Smith

We present results of modelling Ginga data of a number of Soft X-ray Transient sources performed with the aim of constraining the geometry of accretion during various stages of the sources&#39; evolution. Assuming a generic geometry of a central, extended X-ray source with an external, optically thick accretion disk, we use consistent models of X-ray reproce

S. Ehlerova, J. Palous, Ch. Theis, G. Hensler

Conditions for the fragmentation of expanding shells due to gravitational instability are discussed. The self-similar analytical solution is compared with the results of 3-dimensional computer simulations for the expansion into homogeneous media. For realistic galactic disks we show that the formation of fragments is influenced by the amount of energy supply

Rudy Wijnands, Michiel van der Klis

We have discovered kiloHertz quasi-periodic oscillations (kHz QPOs) in five Z sources: GX 340+0, Cygnus X-2, GX 17+2, GX 5-1, and Scorpius X-1. In all sources the properties of these kHz QPOs are very similar and closely related to the position of the sources on the Z track traced out in the X-ray color-color diagram and the hardness-intensity diagram. The f

John K. Cannizzo

I review recent advances in our understanding of accretion disks in transient systems - the dwarf novae and the soft X-ray transients. The primary theme will be the ongoing development of theory in response to the observations. The accretion disk limit cycle model appears to provide a unifying framework within which we may begin to understand what is seen in

A. Comastri, F. Fiore, M. Guainazzi, G. Matt

We report on the first spectrum up to 10 keV of the bright narrow-line Seyfert 1 galaxy Ton S 180, obtained with the imaging instruments onboard BeppoSAX. This is the first observed source in a sample of a dozen narrow-line Seyfert 1 galaxies in the BeppoSAX Core Program. We also present and discuss a high quality optical spectrum taken at the 1.5 m telescop

Giorgio Matt

The contributions that BeppoSAX is expected to give and, after one and a half year of operation, has already given to our knowledge of both type 1 and type 2 Seyfert galaxies are outlined and reviewed.

The BAIKAL Collaboration

We review the present status of the Baikal Underwater Neutrino Experiment and report on neutrino events recorded with the detector stages NT-36 and NT-96.

L. Bergstrom

The need for dark matter is briefly reviewed. A wealth of observational information points to the existence of a non-baryonic component. To the theoretically favoured candidates today belong axions, supersymmetric particles, and to some extent massive neutrinos. The theoretical foundation and experimental situation for each of these is reviewed. In particula

Ue-Li Pen, Abraham Loeb, Neil Turok

The standard unbroken electroweak theory is known to erase baryon number. The baryon number symmetry can be restored in the core of a neutron star as its density diverges via gravitational instability due to a binary merger event. We argue that for certain double Higgs models with discrete symmetries, this process may result in an expanding self-sustained bu

Doerte Mehlert, Roberto P. Saglia, Ralf Bender, Gary Wegner

The Coma cluster is one of the richest known cluster of galaxies, spanning about 4 dex in density. Hence it is the ideal place to study the structure of galaxies as a function of environmental density in order to constrain the theories of galaxy formation and evolution. For a magnitude limited sample of 35 E and S0 galaxies we obtained long slit spectra to d

Yum-Tong Siu

The following conjecture on the deformation invariance of plurigenera is proved. For a smooth projective holomorphic family of compact complex manifolds over the open unit 1-disk such that all the fibers are of general type, every plurigenus of the fiber is independent of the fiber. The proof uses Nadel&#39;s multiplier ideal sheaves, Skoda&#39;s result on t

Hélène Esnault, V. Srinivas, Eckart Viehweg

We show the existence of a regular universal quotient as a smooth commutative algebraic group of the Chow group of 0-cycles on a projective reduced variety, and give over the field of complex numbers an analytic description of it. This generalizes the classical theory of the Albanese. The Chow group of 0-cycles is then isomorphic to this smooth algebraic gro

Yujiro Kawamata

We extend a subadjunction formula of log canonical divisors as in [K3] to the case when the codimension of the minimal center is arbitrary by using the positivity of the Hodge bundles.

M. E. J. Newman, Robin Engelhardt

We introduce a new model of evolution on a fitness landscape possessing a tunable degree of neutrality. The model allows us to study the general properties of molecular species undergoing neutral evolution. We find that a number of phenomena seen in RNA sequence-structure maps are present also in our general model. Examples are the occurrence of &#34;common&

HongSheng Zhao, P. Tim de Zeeuw

With the steady increase of the sample size of observed microlenses towards the central regions of the Galaxy, the main source of the uncertainty in the lens mass will shift from the simple Poisson noise to the intrinsic non-uniqueness of our dynamical models of the inner Galaxy, particularly, the Galactic bar. We use a set of simple self-consistent bar mode

A. Ali, J. Chay, C. Greub, P. Ko

We compute the decay rates for the exclusive decays $B^{\pm} \to (η^{\prime},η) (K^{\pm}, K^{*\pm})$ and $B^{0}\to (η^{\prime},η) (K^{0}, K^{*0})$ in a QCD-improved factorization framework by including the contribution from the process $b\to sgg \to s (η^{\prime}, η)$ through the QCD anomaly. This method provides an alternative estimate of the contribution $

S. Baez, A. P. Balachandran, A. Stern, A. Travesset

It is well known that the Fractional Quantum Hall Effect (FQHE) may be effectively represented by a Chern-Simons theory. In order to incorporate QH Skyrmions, we couple this theory to the topological spin current, and include the Hopf term. The cancellation of anomalies for chiral edge states, and the proviso that Skyrmions may be created and destroyed at th

W. Kilian, O. Nachtmann

Exclusive pseudoscalar meson production in ep scattering at high energies is a direct probe for a possible &#34;odderon&#34; exchange in soft hadronic processes. Using a simple phenomenological ansatz for the odderon, we demonstrate how it can be separated from the contribution due to photon-photon fusion, and the relevant parameters be measured. Total cross

Kazuyuki Kanaya

I report on some recent developments in nonperturbative studies of finite temperature QCD with dynamical quarks on the lattice. I discuss new studies of improved lattice actions and their application to finite temperature QCD. I also summarize the status of lattice investigations about the order of the finite temperature QCD transition for the case of two fl

Vladimir V. Kisil

We explore a function theory connected with the principal series representation of SL(2,R) in contrast to standard complex analysis connected with the discrete series. We construct counterparts for the Cauchy integral formula, the Hardy space, the Cauchy-Riemann equation and the Taylor expansion. Keywords: Complex analysis, Cauchy integral formula, Hardy spa

Seiji Yunoki, Adriana Moreo

The phase diagram of the Kondo lattice Hamiltonian with ferromagnetic Hund&#39;s coupling in the limit where the spin of the localized $t_{2g}$ electrons is classical is analyzed in one dimension as a function of temperature, electronic density, and a direct antiferromagnetic coupling $J&#39;$ between the localized spins. Studying static and dynamical proper

Y. S. Jain

This paper reports the unified microscopic theory of a system of interacting bosons such as liquid $^4He$.Each particle in the system represents a $(q;-q)$ pair moving with a centre of mass momentum K.Particles form bound pairs below $λ$-point and have a kind of collection binding between them.The binding is idenified as an energy gap between the superfluid

V. E. Kravtsov, V. I. Yudson

We demonstrate the danger of a naive identification of kinetic coefficients in the free-electron response expansion in powers of an external electric field and coefficients in the expansion of the corresponding equilibrium quantity in powers of the fluctuating intrinsic electric field. A particular example of the direct current generation by an AC electric f

A. J. Bunker, L. A. Moustakas, M. Davis, B. L. Frye

We have recently obtained deep near-IR Keck imaging of a newly-discovered z=4.04 galaxy (Frye & Broadhurst 1998). This is lensed by the rich foreground cluster Abell 2390 (z=0.23) into highly-magnified arcs 3-5&#34; in length. Our H- and K&#39;-band Keck/NIRC imaging allows us to map the Balmer+4000Ang break amplitude. In combination with high-quality archiv

Shude Mao, H. J. Mo, Simon D. M. White

We use recent observations of high-redshift galaxies to study the evolution of galactic disks over the redshift range 0<z<1. The data are inconsistent with models in which disks were already assembled at z=1 and have evolved only in luminosity since that time. Assuming that disk properties change with redshift as powers of 1+z and analysing the observations

Sharad Agnihotri, Chris Woodward

We describe the inequalities on the possible eigenvalues of products of unitary matrices in terms of quantum Schubert calculus. Related problems are the existence of flat connections on the punctured two-sphere with prescribed holonomies, and the decomposition of fusion product of representations of SU(n), in the large level limit. In the second part of the

Marek Gazdzicki

A method to study event--by--event fluctuations of the `chemical&#39; (particle type) composition of the final state of high energy collisions is proposed.}

Kwei-Chou Yang, Hoi-Lai Yu

Quark mass effects are clarified in the parton model approach to the transversely polarized nucleon structure function. The special propagator technique is employed to obtain manifestly gauge invariant results and extract the buried short-distance contributions inside the soft part after momentum factorization in the collinear expansion approach. A generaliz

Shou Hua Zhu, Chong Sheng Li, Chong Shou Gao

We calculate the squarks one-loop corrections to the cross sections of the chared Higgs boson pair production in photon-photon collisions in the minimal supersymmetric extension of standard model(MSSM). In general, in case of the large splitting in the masses of left-top squark and the right-top squark and for $\tanβ$ near 1.5, the corrections can reduce the

H. F. Chau

I report two general methods to construct quantum convolutional codes for $N$-state quantum systems. Using these general methods, I construct a quantum convolutional code of rate 1/4, which can correct one quantum error for every eight consecutive quantum registers.

Petr Horava

We suggest that M-theory could be non-perturbatively equivalent to a local quantum field theory. More precisely, we present a ``renormalizable&#39;&#39; gauge theory in eleven dimensions, and show that it exhibits various properties expected of quantum M-theory, most notably the holographic principle of &#39;t~Hooft and Susskind. The theory also satisfies Ma

A. Ya. Maltsev

Paper is devoted to the construction of averaging procedure of Hamiltonian structures in discrete Whitham method. The procedure is analogous to Dubrovin-Novikov procedure of averaging of local field-theoretical Poisson brackets and gives the Poisson bracket of Hydrodynamic Type starting from Poisson bracket for a discrete chain.

Luca Salasnich

We study analytically the ground-state stability of a Bose-Einstein condensate (BEC) confined in an harmonic trap with repulsive or attractive zero-range interaction by minimizing the energy functional of the system. In the case of repulsive interaction the BEC mean radius grows by increasing the number of bosons, instead in the case of attractive interactio

Vladimir D. Tonchev

This paper has been withdrawn since a Gilbert-Varshamov bound for general quantum codes has already appeared in Ekert and Macchiavello, Prys. Rev. Lett. 77, p. 2585, and a Gilbert-Varshamov bound for stabilizer codes connected with orthogonal geometry, or equivalently, with symmetric matrices as in this paper, has been proved by Calredbank, Rains, Shor and S

Yi-Zhi Huang

In [H5] (q-alg/9512024) and [H7] (q-alg/9704008), the author introduced the notion of intertwining operator algebra, a nonmeromorphic generalization of the notion of vertex operator algebra involving monodromies. The problem of constructing intertwining operator algebras from representations of suitable vertex operator algebras were solved implicitly earlier

Feng Pan, Lianrong Dai

A new method for deriving universal Ř matrices from braid group representation is discussed. In this case, universal Ř operators can be defined and expressed in terms of products of braid group generators. The advantage of this method is that matrix elements of Ř are rank independent, and leaves multiplicity problem concerning coproducts of the corresponding

Wick Haxton

The sun and core-collapse supernovae produce neutrino spectra that are sensitive to the effects of masses and mixing. Current results from solar neutrino experiments provide perhaps our best evidence for such new neutrino physics, beyond the standard electroweak model. I discuss this evidence as well as the limited possibilities for more conventional explana

Sungbok Hong, Darryl McCullough

Mapping class groups of Haken 3-manifolds enjoy many of the homological finiteness properties of mapping class groups of 2-manifolds of finite type. For example, H(M) has a torsionfree subgroup of finite index, which is geometrically finite (i. e. is the fundamental group of a finite aspherical complex). This was proven by J. Harer for 2-manifolds and by the

Jim Bryan, Jason Fulman

Generating functions for the number of commuting m-tuples in the symmetric groups are obtained. We define a natural sequence of ``orbifold Euler characteristics&#39;&#39; for a finite group G acting on a manifold X. Our definition generalizes the ordinary Euler characteristic of X/G and the string-theoretic orbifold Euler characteristic. Our formulae for com

Peter Leifer

It is shown that some analog of the ``second quantization&#39;&#39; exists in the framework of CP(N) theory. I analyse conditions under that ``geometrical bosons&#39;&#39; may be identified with real physical fields. The compact character of a state manifold should preserve the quantities of dynamical variables from divergences.

C. A. Dominguez, L. Pirovano, K. Schilcher

QCD Laplace transform sum rules, involving the axial-vector current divergences, are used in order to determine the strange quark mass. The two-point function is known in QCD up to four loops in perturbation theory, and up to dimension-six in the non-perturbative sector. The hadronic spectral function is reconstructed using threshold normalization from chira

G. Altarelli, R. Barbieri, F. Caravaglios

1. Introduction 2. Status of the Data 3. Precision Electroweak Data and the Standard Model 4. A More General Analysis of Electroweak Data 4.1 Basic Definitions and Results 4.2 Experimental Determination of the Epsilon Variables 4.3 Comparing the Data with the Minimal Supersymmetric Standard Model 5. Theoretical Limits on the Higgs Mass 6. Conclusion

Hoi-Lai Yu

We develop the perturbative QCD formalism for inclusive heavy hadron decays. Transverse degrees of freedom of partons are introduced to facilitate the factorization of the heavy hadron decays.

Martin Rocek, Robert Shrock, Shan-Ho Tsai

We calculate the chromatic polynomials $P((G_s)_m,q)$ and, from these, the asymptotic limiting functions $W(\{G_s\},q)=\lim_{n \to \infty}P(G_s,q)^{1/n}$ for families of $n$-vertex graphs $(G_s)_m$ comprised of $m$ repeated subgraphs $H$ adjoined to an initial graph $I$. These calculations of $W(\{G_s\},q)$ for infinitely long strips of varying widths yield

Wei Cui

We present further observational evidence of the effects of a centrifugal barrier in GRO J1744-28, based on continued monitoring of the source with RXTE. For X-ray pulsars, the centrifugal barrier manifests itself in the cessation of pulsed emission when the source becomes faint. We show that such phenomenon occurred repeatedly for GRO J1744-28, following th

V. Castellani, S. Degl&#39;Innocenti, W. A. Dziembowski, G. Fiorentini

We present our results concerning a systematical analysis of helioseismic implications on solar structure and neutrino production. We find Y$_{ph}=0.238-0.259$, $R_b/R_\odot=0.708-0.714$ and $ρ_b=(0.185-0.199)$ gr/cm$^3$. In the interval $0.2<R/R_\odot<0.65$, the quantity $U=P/ρ$ is determined with and accuracy of $\pm 5$\permille~or better. At the solar cen

George Chapline

In this paper we consider the question whether a distributed network of sensors and data processors can form &#34;perceptions&#34; based on the sensory data. Because sensory data can have exponentially many explanations, the use of a central data processor to analyze the outputs from a large ensemble of sensors will in general introduce unacceptable latencie

Nino Boccara, Henryk Fuks

This paper shows how to determine all the unidimensional two-state cellular automaton rules of a given number of inputs which conserve the number of active sites. These rules have to satisfy a necessary and sufficient condition. If the active sites are viewed as cells occupied by identical particles, these cellular automaton rules represent evolution operato

Christopher Mudry, Xiao-Gang Wen

Effective theories for random critical points are usually non-unitary, and thus may contain relevant operators with negative scaling dimensions. To study the consequences of the existence of negative dimensional operators, we consider the random-bond XY model. It has been argued that the XY model on a square lattice, when weakly perturbed by random phases, h

Gordon Chalmers

We generalize to the case of compactified superstrings a construction given previously for critical superstrings of finite one loop amplitudes that are well-defined for all external momenta. The novel issues that arise for compactified strings are the appearance of infrared divergences from the propagation of massless strings in four dimensions and, in the c

V. V. Dodonov, V. I. Man&#39;ko, L. Rosa

Following the paper by M. Combescure [Ann. Phys. (NY) 204, 113 (1990)], we apply the quantum singular time dependent oscillator model to describe the relative one dimensional motion of two ions in a trap. We argue that the model can be justified for low energy excited states with the quantum numbers $n\ll n_{max}\sim 100$, provided that the dimensionless con

E. Arrigoni, W. Hanke

We study the occurrence of SO(5) symmetry in the low-energy sector of two-chain Hubbard-like systems by analyzing the flow of the running couplings ($g$-ology) under renormalization group in the weak-interaction limit. It is shown that SO(5) is asymptotically restored for low energies for rather general parameters of the bare Hamiltonian. This holds also wit

Friedemann Brandt, Joaquim Gomis, Joan Simón

We analyse completely the BRST cohomology on local functionals for two dimensional sigma models coupled to abelian world sheet gauge fields, including effective bosonic D-string models described by Born-Infeld actions. In particular we prove that the rigid symmetries of such models are exhausted by the solutions to generalized Killing vector equations which

Bert Schroer

In this paper I continue the study of the new framework of modular localization and its constructive use in the nonperturbative d=1+1 Karowski-Weisz-Smirnov formfactor program. Particular attention is focussed on the existence of semilocal generators of the wedge-localized algebra without vauum polarization (FWG-operators) which are closely related to object

V. P. Gusynin, M. Reenders

The gauged Nambu-Jona-Lasinio model in the quenched-ladder approximation has non-trivial dynamics near a critical scaling region (critical curve) separating a chiral symmetric and a dynamically chiral symmetry broken phase. Scalar and pseudoscalar composites corresponding to the four-fermion interaction become relevant degrees of freedom at short distances,

T. Wegner, M. Potthoff, W. Nolting

The infinite-dimensional Hubbard model is studied by means of a modified perturbation theory. The approach reduces to the iterative perturbation theory for weak coupling. It is exact in the atomic limit and correctly reproduces the dispersions and the weights of the Hubbard bands in the strong-coupling regime for arbitrary fillings. Results are presented for

Elliott H. Lieb, Jakob Yngvason

Now that the properties of low temperature Bose gases at low density, $ρ$, can be examined experimentally it is appropriate to revisit some of the formulas deduced by many authors 4-5 decades ago. One of these is that the leading term in the energy/particle is $2π\hbar^2 ρa/m$, where $a$ is the scattering length. Owing to the delicate and peculiar nature of

Thibault Damour, Viatcheslav F. Mukhanov

We draw attention to the possibility that inflation (i.e. accelerated expansion) might continue after the end of slow roll, during a period of fast oscillations of the inflaton field ϕ. This phenomenon takes place when a mild non-convexity inequality is satisfied by the potential V(ϕ). The presence of such a period of ϕ-oscillation-driven inflation can subst

J. Ducree, J. Mrogenda, E. Reckels, M. Ruether

We present autoionization spectra of metastable Ar(8+) and C(4+), N(5+), O(6+) and Ne(8+) scattering off an Al(111) surface with incident energies down to 5 eV. The unprecedented quality of the experimental data permits the observation of a unique, yet undiscovered peak in the structures originating from the metastable projectiles compared to corresponding g

H. C. Chiang, E. Oset, M. J. Vicente Vacas

The s-wave isoscalar amplitude for pion-pion scattering in a nuclear medium is evaluated using a nonperturbative unitary coupled channels method and the standard chiral Lagrangians. The method has proved successful to describe the pion-pion properties in the scalar isoscalar channel up to 1.2 GeV giving rise to poles in the t matrix for the f0(980) and the s

Massimo Giovannini

We construct some examples of analytic solutions of the low energy (i.e. tree-level) string cosmological effective action. We work with the ``minimal&#39;&#39; field content (i.e. graviton and dilaton) in the absence of any dilaton potential. Provided the metric is sufficiently inhomogeneous we find solutions whose curvature invariants are bounded and everyw

K. Schertler, C. Greiner, P. K. Sahu, M. H. Thoma

We investigate the influence of medium effects on the structure of hybrid stars, i.e. neutron stars possessing a quark matter core. We found that medium effects reduce the extent of a pure quark matter phase in the interior of a hybrid star significantly in favor of a mixed phase of quark and hadronic matter. Over a wide range of the strong coupling constant

M. A. Skvortsov

Motivated by the recent observation of the metal-insulator transition in Si-MOSFETs we consider the quantum interference correction to the conductivity in the presence of the Rashba spin splitting. For a small splitting, a crossover from the localizing to antilocalizing regime is obtained. The symplectic correction is revealed in the limit of a large separat

A. Parreño, A. Ramos, C. Bennhold, K. Maltman

Violations of the $Δ$I=1/2 rule are investigated in the nonmesonic weak hypernuclear decay using a weak $Λ$N$\to$NN transition potential based on meson exchange. While the weak $Δ$I=3/2 matrix elements of baryons with pseudoscalar mesons are known to be very small, the same matrix elements of baryons with vector mesons, evaluated in the factorization approxi

Christof Gattringer, Ivan Hip

We study characteristic features of the eigenvalues of the Wilson-Dirac operator in topologically non-trivial gauge field configurations by examining complete spectra of the fermion matrix. In particular we discuss the role of eigenvectors with real eigenvalues as the lattice equivalents of the continuum zero-modes. We demonstrate, that those properties of t

K. Tsushima, K. Saito, A. W. Thomas, S. V. Wright

The properties of the kaon, $K$, and antikaon, $\kbar$, in nuclear medium are studied in the quark-meson coupling (QMC) model. Employing a constituent quark-antiquark (MIT bag model) picture, their excitation energies in a nuclear medium at zero momentum are calculated within mean field approximation. The scalar, and the vector mesons are assumed to couple d

Marsha Weaver, James Isenberg, Beverly K. Berger

Numerical investigation of a class of inhomogeneous cosmological spacetimes shows evidence that at a generic point in space the evolution toward the initial singularity is asymptotically that of a spatially homogeneous spacetime with Mixmaster behavior. This supports a long-standing conjecture due to Belinskii et al. on the nature of the generic singularity

M. Hirayama, S. Matsubara

A simple analytic proof of the formula known as the non-Abelian Stokes theorem is given. It is explicitly shown that the consistency of the formula is guaranteed by the Bianchi identity for the gauge field. An attempt is made to construct the Lagrangian for the gauge field in terms of loop variables.

B. Grzadkowski, Z. Hioki, M. Szafranski

Effects of four-Fermi-type new interactions are studied in top-quark pair production and their subsequent decays at future e^+e^- colliders. Secondary-lepton-energy distributions are calculated for arbitrary longitudinal beam polarizations. An optimal-observables procedure is applied for the determination of new parameters.

D. Arnaudon, E. Buffenoir, E. Ragoucy, Ph. Roche

We construct a universal trigonometric solution of the Gervais-Neveu-Felder equation in the case of finite dimensional simple Lie algebras and finite dimensional contragredient simple Lie superalgebras.

Timothy J. Hodges

A direct proof is given of the fact that the Cremmer-Gervais R-matrices satisfy the Yang-Baxter equation.

K. Mimachi

We construct a solution of Cherednik&#39;s quantum Knizhnik Zamolodchikov equation associated with the root system of type $C_n$. This solution is given in terms of a restriction of a $q$-Jordan-Pochhammer integral. As its applicaton, we give an explicit expression of a special case of the Macdonald polynomial of the $C_n$ type. Finally we explain the connec

J. C. Flores

A simple mathematical homogeneous model of competition is used to describe Neanderthal extinction in Europe. It considers two interacting species, Neanderthals and Early Modern Men, in the same ecological niche. Using paleontological data we claim that the parameter of similarity, between both species, fluctuates between 0.992 and 0.997. An extension of the

R. Brinkmann, A. K. Ciftci, S. Sultansoy, S. Turkoz

The present status of suggested linac-ring type ep and gamma-p colliders is reviewed. The main parameters of these machines as well as e-nucleus and gamma-nucleus colliders are considered. It is shown that sufficiently high luminosities may be achieved with a reasonable improvement of proton and electron beam parameters.

V. I. Man&#39;ko, R. Vilela Mendes

The characterization of non-stationary signals requires joint time and frequency information. However, time (t) and frequency (omega) being non-commuting variables there cannot be a joint probability density in the (t,omega) plane and the time-frequency distributions, that have been proposed, have difficult interpretation problems arising from negative or co

W. Hackl, M. Barmann, E. Sackmann

We report the self-assembly of thin actin shells beneath the membranes of giant vesicles. Ion-carrier mediated influx of Mg2+ induces actin polymerization in the initially spherical vesicles. Buckling of the vesicles and the formation of blisters after thermally induced bilayer expansion is demonstrated. Bilayer flickering is dominated by tension generated b

G. Q. Li, G. E. Brown, C. Gale, C. M. Ko

Dilepton and photon production in heavy-ion collisions at SPS energies is studied in the relativistic transport model that incorporates self-consistently the change of hadron masses in dense matter. It is found that the dilepton spectra in proton-nucleus reactions can be well described by the conventional mechanisms of Dalitz decay, primary vector meson deca

E. L. Bratkovskaya, W. Cassing, U. Mosel

We perform systematical studies on transverse-mass spectra of $π^0$, $η$, $ω$, $ϕ$, $K^+$ and $K^-$ mesons for C + C, Ni + Ni, Au + Au collisions at SIS energies within the HSD transport approach. We find that the $m_T$-spectra sensitively reflect the in-medium properties of the mesons. The &#39;bare mass&#39; scenario leads to a general scaling behaviour fo

B. D. Milbrath, J. I. McIntyre, C. S. Armstrong, D. H. Barkhuff

Recoil proton polarization observables were measured for both the p($\vec {\rm e}$,e$^\prime\vec{\rm p}\,$) and d($\vec {\rm e}$,e$^\prime\vec{\rm p}\,)$n reactions at two values of Q$^2$ using a newly commissioned proton Focal Plane Polarimeter at the M.I.T.-Bates Linear Accelerator Center. The hydrogen and deuterium spin-dependent observables $D_{\ell\ell}

James Ellis Colliander, Robert L. Jerrard

The initial value problem for the Ginzburg-Landau-Schrödinger equation is examined in the $ε\rightarrow 0$ limit under two main assumptions on the initial data $ϕ^ε$. The first assumption is that $ϕ^ε$ exhibits $m$ distinct vortices of degree $\pm 1$; these are described as points of concentration of the Jacobian $[Jϕ^ε]$ of $ϕ^ε$. Second, we assume energy b