October 1996 arXiv papers — page 12

R. Jakob, P. J. Mulders

The combination of transverse momentum and polarization effects in hard scattering processes, e.g polarized deep-inelastic leptoproduction, results in a rich variety of information on the hadronic structure. This information is encoded in a correspondingly large number of functions depending on both, longitudinal fractional momenta $x$ and transverse momenta

Vincent Lucas, Stuart Raby

In this paper, we calculate neutron and proton decay rates and branching ratios in a predictive SO(10) SUSY GUT which agrees well with low energy data. We show that the nucleon lifetimes are consistent with the experimental bounds. The nucleon decay rates are calculated using all one-loop chargino and gluino dressed diagrams regardless of their chiral struct

A. M. Green, C. Michael, P. S. Spencer

The spatial distribution of the action and energy in the colour fields of flux-tubes is studied in lattice SU(2) field theory for static quarks at separations up to 1 fm. Special attention is paid to the structure of the colour fields associated with an excited flux-tube with E_u symmetry. We compare our results with hadronic string and flux-tube models. Sum

Jonathan Flynn

I review the status of lattice calculations of heavy-light weak matrix elements, concentrating on semileptonic B decays to light mesons, B -> K* gamma, the B meson decay constant, f_B, and the mixing parameter B_B.

Piotr T. Chruściel

We establish global extendibility (to the domain of outer communications) of locally defined isometries of appropriately regular analytic black holes. This allows us to fill a gap in the Hawking-Ellis proof of black-hole rigidity.

Piotr T. Chruściel

In recent years there has been some progress in the understanding of the global structure of stationary black hole space-times. In this paper we review some new results concerning the structure of stationary black hole space-times. In particular we prove a corrected version of the ``black hole rigidity theorem'', and we prove a uniqueness theorem for

T. Asselmeyer

In this paper the relation between the choice of a differential structure and a smooth connection in the tangential bundle is discussed. For the case of an exotic $S^7$ one obtains corrections to the curvature after the change of the differential structure, which can not be neglected by a gauge transformation. In the more interesting case of four dimensions

George Kamberov, Franz Pedit, Ulrich Pinkall

In this note we classify all Bonnet pairs on a simply connected domain. Our main intent was to apply what we call a quaternionic function theory to a concrete problem in differential geometry. The ideas are simple: conformal immersions into quaternions or imaginary quaternions take the place of chart maps for a Riemann surface. Starting from a reference imme

Igor F. Herbut

The superconducting transition in presence of strong columnar disorder parallel to the magnetic field is considered. A solvable model appropriate for description of the broad crossover regime towards the true "glassy" critical behavior is constructed, and the behavior of the thermodynamic quantities and of the Edwards-Anderson order-parameter is obta

A. O. Parry, C. J. Boulter, P. S. Swain

Recent work on the complete wetting transition has emphasized the role played by the coupling of fluctuations of the order parameter at the wall and at the depinning fluid interface. Extending this approach to the wetting transition itself we predict a novel crossover effect associated with the decoupling of fluctuations as the temperature is lowered towards

Masanori Kohno

The two-dimensional $t$-$J$ model in the ground state is investigated by the power Lanczos method. The pairing-pairing correlation function for $d_{x^2-y^2}$-wave symmetry is enhanced in the realistic parameter regime for high-$T_c$ superconductors. The charge susceptibility $χ_c$ shows divergent behavior as $χ_c\proptoδ^{-1}$ near half-filling for the dopin

Dragi Karevski, Malte Henkel

Thermal and magnetic effects in a system consisting of thin layers of coupled Ising spins with $S=1/2$ and $S=1$ are considered. The specific heat and the correlation length display maxima at two different temperatures. It is discussed in what sense these maxima can be interpreted as a finite-size rounding of a thermodynamic singularity associated with a pha

Enrique Diez, Angel Sanchez, Francisco Dominguez-Adame

We study the dynamical behavior of disordered quantum-well-based semiconductor superlattices where the disorder is intentional and short-range correlated. We show that, whereas the transmission time of a particle grows exponentially with the number of wells in an usual disordered superlattice for any value of the incident particle energy, for specific values

N. B. Kopnin, G. E. Volovik

In d-wave superconductors, the electronic density of states (DOS) induced by a vortex exhibits 1/|E| divergency at low energies. It is the result of gap nodes in the excitations spectrum outside the vortex core. The heat capacity in two regimes, (T/T_c)^2 >> B/B_{c2} and (T/T_c)^2 << B/B_{c2}, is discussed.

Antoine Georges, Laurent Laloux

A physical picture of normal liquid $^3$He, which accounts for both ``almost localized&#39;&#39; and ``almost ferromagnetic&#39;&#39; aspects, is proposed and confronted to experiments.

Eric J. Bakker, Ewine F. van Dishoeck, L. B. F. M. Waters, Ton Schoenmaker

We present optical high-resolution spectra of a sample of sixteen post-AGB stars and IRC +10216. Of the post-AGB stars, ten show C2 Phillips and Swan and CN Red System absorption, one CH+ emission, one CH+ absorption, and four without any molecules. We find typically Trot=43-399, 155-202, and 18-50 K, log N = 14.90-15.57, 14.35, and 15.03-16.47 cm-2 for C2,

J. Greiner, E. H. Morgan, R. A. Remillard

The galactic superluminal motion source GRS 1915+105 was observed with RXTE at several occasions during its ongoing active state. The observed X-ray intensity changes drastically on a variety of time scales ranging from sub-seconds to days. In particular, the source exhibits quasi-periodic brightness sputters with varying duration and repetition time scale.

Guohong Xu

The theory and application of numerical methods for unstructured meshes have been improved significantly in recent years. Because the grids can be place arbitrarily in space, unstructured meshes can provide much higher spatial resolution than regular meshes. The built-in nature of mesh adaptivity for unstructured meshes gives one way to simulate highly dynam

V. Berezinsky, A. Bottino, G. Mignola

The microlensing objects, Machos, recently observed in the halo of our Galaxy, can be interpreted as dense neutralino objects, neutralino stars, produced by the gravitational instability of neutralino gas. Taking the mass and radius of these objects from microlensing observations we calculated the diffuse gamma-ray flux produced in neutralino--neutralino ann

F. Matteucci, B. K. Gibson

In this paper we discuss the chemical evolution of elliptical galaxies and its consequences on the evolution of the intracluster medium (ICM). We use chemical evolution models taking into account dark matter halos and compare the results with previous models where dark matter was not considered. In particular, we examine the evolution of the abundances of so

A. Mastichiadis, J. G. Kirk

We present a model of the spectra of gamma-ray emitting blazars in which a single homogeneous emission region both emits synchrotron photons directly and scatters them to high (gamma-ray) energy before emission (a ``synchrotron self-Compton&#39;&#39; or SSC model). In contrast to previous work, we follow the full time dependent evolution of the electron and

Claus Grupen

Neutrino astronomy offers the prospect to be able to look into the interior of compact astrophysical objects which may be the sources of cosmic radiation. This paper describes the results on neutrino observations from the sun and the supernova SN1987A along with an outlook on neutrino astronomy beyond the TeV scale.

V. G. Gurzadyan, A. Mazure

We report the results of an analysis of the hierarchical properties of the cluster of galaxies Abell 119. Observational data from the ESO Nearby Abell Cluster Survey (ENACS) are used, complemented by data from previous studies, while the analysis is performed with the S-tree method. The main physical system and its three subgroups with truncated Gaussian vel

Taoling Xie, L. Mundy, S. Vogel, P. Hofner

It has been proposed recently that the small size and long lifetime of ultra-compact HII regions (UCHIIs) could be due to pressure confinement if the thermal pressure of the ambient gas is higher than previous estimates. We point out that confinement by thermal pressure alone implies emission measures in excess of observed values. We show that turbulent pres

Misha Verbitsky

Let $M$ be a compact complex manifold equipped with a hyperkähler metric, and $X$ be a closed complex analytic subvariety of $M$. In alg-geom/9403006, we proved that $X$ is trianalytic, i. e., complex analytic with respect to all complex structures induced by the hyperkähler structure, provided that $M$ is generic in its deformation class. Here we study the

Ragnar-Olaf Buchweitz, Qun Chen

We determine the Hilbert-Kunz function of plane elliptic curves in odd characteristic, as well as over arbitrary fields the generalized Hilbert-Kunz functions of nodal cubic curves. Together with results of K. Pardue and P. Monsky, this completes the list of Hilbert-Kunz functions of plane cubics. Combining these results with the calculation of the (generali

Jim Bryan, Marc Sanders

Let $\M_{k}^{n}$ be the moduli space of based (anti-self-dual) instantons on $\cpbar$ of charge $k$ and rank $n$. There is a natural inclusion of rank $n$ instantons into rank $n+1$. We show that the direct limit space is homotopy equivalent to $BU(k)\times BU(k)$. The moduli spaces also have the following algebro-geometric interpretation: Let $\linf$ be a l

J. Feinberg, A. Zee

We analyze the 1+1 dimensional Nambu-Jona-Lasinio model non-perturbatively. We study non-trivial saddle points of the effective action in which the composite fields $\sigx=<\barψψ>$ and $\pix=<\bar\psii\gam_5ψ>$ form static space dependent configurations. These configurations may be viewed as one dimensional chiral bags that trap the original fermions (``qua

Patrick Suppes, J. Acacio de Barros, Gary Oas

The purpose of this article is to formulate a number of probabilistic hidden-variable theorems, to provide proofs in some cases, and counterexamples to some conjectured relationships. The first theorem is the fundamental one. It asserts the general equivalence of the existence of a hidden variable and the existence of a joint probability distribution of the

Sheldon Stone

In these lectures I review what has been learned from studies of b-quark decays, including semileptonic decays ($V_{ub}$ and $V_{cb}$), $B^o-\overline{B}^o$ mixing and rare B decays. Then a discussion on CP violation follows, which leads to a summary of plans for future experiments and what is expected to be learned from them. (Presented at NATO Advanced Stu

J. David Moroz, Philip Nelson

Zhelev and Needham have recently created large, quasi-stable pores in artificial lipid bilayer vesicles [Biochim. Biophys. Acta 1147 (1993) 89]. Initially created by electroporation, the pores remain open for up to several seconds before quickly snapping shut. This result is surprising in light of the large line tension for holes in bilayer membranes and the

A. Brandhuber, S. Stieberger

We show how BPS states of supersymmetric SU(2) Yang-Mills with matter -both massless and massive- are described as self-dual strings on a Riemann surface. This connection enables us to prove the stability and the strong coupling behaviour of these states. The Riemann surface naturally arises from type-IIB Calabi-Yau compactifications whose three-branes wrapp

E. Knill, R. Laflamme, W. Zurek

We have previously (quant-ph/9608012) shown that for quantum memories and quantum communication, a state can be transmitted over arbitrary distances with error $ε$ provided each gate has error at most $cε$. We discuss a similar concatenation technique which can be used with fault tolerant networks to achieve any desired accuracy when computing with classical

P. G. Silvestrov

A method of resummation of infinite series of perturbation theory diagrams is applied for studying the properties of random band matrices. The topological classification of Feynman diagrams, which was actively used in last years for matrix model regularization of 2d-gravity, turns out to be very useful for band matrices. The critical behavior at the edge of

Malte Henkel, Enzo Orlandini, Jaime Santos

One-dimensional reaction-diffusion systems are mapped through a similarity transformation onto integrable (and a priori non-stochastic) quantum chains. Time-dependent properties of these chemical models can then be found exactly. The reaction-diffusion processes related to free fermion systems with site-independent interactions are classified. The time-depen

Samwel Apikyan, Costas Efthimiou

The conformal field theory on a Z_N-surface is studied by mapping it on the branched sphere. Using a coulomb gas formalism we construct the minimal models of the theory.

A. Frink, U. Kilian, D. Kreimer

We calculate the two-loop vertex function for the crossed topology, and for arbitrary masses and external momenta. We derive a double integral representation, suitable for a numerical evaluation by a Gaussian quadrature. Real and imaginary parts of the diagram can be calculated separately.

G. Sierra

We review the non linear sigma model approach (NLSM) to spin chains and spin ladders, presenting new results. The generalization of the Haldane&#39;s map to ladders in the Hamiltonian approach, give rise to different values of the $θ$ parameter depending on the spin S, the number of legs $n_{\ell}$ and the choice of blocks needed to built up the NLSM fields.

J. Grunhaus, S. Kananov

We have designed and carried out simulation studies of a two layer Shower Maximum Detector diagonally off-set (SMD-dos) optimized for the separation of π^0 showers from γshowers in the 30 to 150 GeV energy range. For 90% γacceptance the SMD-dos yields π^0 rejection efficiency of 92+-4%, 87+-4% and 32+-2%, respectively, for 30, 50 and 150 GeV incident energie

J. M. Pawlowski

Within the framework of generalized functions a general consistent definition of double commutators is given. This definition respects the Jacobi identity even if the regularization is removed. The double commutator of fermionic currents is calculated in this limit. We show that BJL--type prescriptions and point--splitting prescriptions for calculating doubl

G. E. Arutyunov, S. A. Frolov

We propose an algebraic scheme for quantizing the rational Ruijsenaars-Schneider model in the R-matrix formalism. We introduce a special parameterization of the cotangent bundle over GL(N,C). In new variables the standard symplectic structure is described by a classical (Frobenius) r-matrix and by a new dynamical $\bar{r}$-matrix. Quantizing both of them we

Hai-Yang Cheng

The new measurements of $B\to J/ψK(K^*)$ decays by CDF and CLEO indicate that the production ratio $R$ and the fraction of longitudinal polarization $Γ_L/Γ$ are smaller than the previous results. In conjunction with the new result of parity-odd transverse polarization in $B\to J/ψK^*$, we found a minimal modification to the factorization hypothesis: While th

Jerome P. Gauntlett, Tsukasa Tada

The known BPS dyon black hole solutions of the N=4 heterotic string in four dimensions with non-zero angular momentum all have naked singularities. We show that it is possible to modify a certain class of these solutions by the addition of massive Kaluza-Klein fields in such a way that the solutions decompactify near the core to five-dimensional black hole s

Esko Keski-Vakkuri, Per Kraus

We compare the emission rates from excited D-branes in the microcanonical ensemble with back reaction corrected emission rates from black holes in field theory. In both cases, the rates in the high energy tail of the spectrum differ markedly from what a canonical ensemble or free field theory approach would yield. Instead of being proportional to a Bose-Eins

I. Ichinose, A. Sekiguchi

Topological excitations in Chern-Simons gauge theories which describe double-layer fractional quantum Hall effct are studied. There are two types of solitons; one is vortex and the other is nontrivial pseudospin textures which are so-called skyrmion or meron. Effective field theory which describes these solitons is derived by duality transformation.

K. Maruno, K. Kajiwara, S. Nakao, M. Oikawa

Bilinear forms for some nonlinear partial difference equations(discrete soliton equations) are derived based on the results of singularity confinement. Using the bilinear forms, the N-soliton and algebraic solutions of the discrete potential mKdV equation are constructed.

N. A. Gromov, I. V. Kostyakov, V. V. Kuratov

The contraction is applied to obtaining of integrable systems associated with nonsemisimple algebras. The effect of contraction is splitting off some components from initial system without loss of integrability.

S. P. Brumby, G. C. Joshi

Analysis of the logical foundations of quantum mechanics indicates the possibility of constructing a theory using quaternionic Hilbert spaces. Whether this mathematical structure reflects reality is a matter for experiment to decide. We review the only direct search for quaternionic quantum mechanics yet carried out and outline a recent proposal by the prese

N. A. Gromov, I. V. Kostyakov, V. V. Kuratov

The similarity transformations of quantum orthogonal groups are developed and FRT theory is reformulated to the Cartesian basis. The quantum orthogonal Cayley-Klein groups are introduced as the algebra functions over an associative algebra with the nilpotent generators. The quantum orthogonal Cayley-Klein algebras are obtained as the dual objects to the corr

N. A. Gromov, I. V. Kostyakov, V. V. Kuratov

The contraction method applied to the construction of the nonsemisimple quantum symplectic Cayley-Klein groups $ Fun(Sp_q(n;j)) $. This groups has been realised as Hopf algebra of the noncommutative functions over the algebra with nilpotent generators. The dual quantum algebras $ sp_q(n;j) $ are constructed.

J. I. Katz

When an asymmetric bubble collapses it generally produces a well defined high velocity jet. This is remarkable because one might expect such a collapse to produce a complex or chaotic flow rather than an ordered one. I present a dimensional argument for the ubiquity of jets from collapsing bubbles, and model the aspherical collapse of a bubble with pieces of

Ken-ichi Matsuba, Kenji Imai, Kazuhiro Nozaki

Modulational dynamics of oscillatory travelling rolls in magnetoconvection is studied near the onset of a Hopf bifurcation. Using weakly nonlinear analysis, we derive an envelope equation of oscillatory travelling rolls in the plane perpendicular to an ambient vertical magnetic field.The envelope equation is the Davey-Stewartson (DS) equation with complex co

H. W. Mueller, H. Wittmer, C. Wagner, J. Albers

We present an analytical stability theory for the onset of the Faraday instability, applying over a wide frequency range between shallow water gravity and deep water capillary waves. For sufficiently thin fluid layers the surface is predicted to occur in harmonic rather than subharmonic resonance with the forcing. An experimental confirmation of this result

Jae Hwang Lee, Young Jae Lee, Suk-Joon Lee

It is shown that the equation of state of nuclear matter can be determined within the mean-field theory of $σω$ model provided only that the nucleon effective mass curve is given. We use a family of the possible nucleon effective mass curves that reproduce the empirical saturation point in the calculation of the nuclear binding energy curves in order to obta

J. Jurkiewicz, A. Krzywicki

We propose a classification of critical behaviours of branched polymers for arbitrary topology. We show that in an appropriately defined double scaling limit the singular part of the partition function is universal. We calculate this partition function exactly in the generic case and perturbatively otherwise. In the discussion section we comment on the relat

C. Adam

We derive the (matrix-valued) Feynman rules of mass perturbation theory of the massive Schwinger model for non-zero vacuum angle theta. Further, we discuss the properties of the three-boson bound state and compute -- by a partial resummation of the mass perturbation series -- its mass and its partial decay widths.

Holger Ewen, Kristin Foerger

We give an explicit derivation of the Picard-Fuchs equations for N=2 supersymmetric SU(3) Yang-Mills theory with $N_f<6$ massive hypermultiplets in the fundamental representation. We determine the instanton corrections to the prepotential in the weak coupling region using the relation between $\tr<ϕ^2>$ and the prepotential. This method can be generalized to

Masaomi Kimura

Geometric quantization on a coset space $G/H$ is considered, intending to recover Mackey&#39;s inequivalent quantizations. It is found that the inequivalent quantizations can be obtained by adopting the symplectic 2-form which leads to Wong&#39;s equation. The irreducible representations of $H$ which label the inequivalent quantizations arise from Weil&#39;s

Anne-Christine Davis, Warren B. Perkins

We investigate the standard model in a cosmic string background and show that the electroweak symmetry is partially restored. For a range of parameters the electroweak Higgs field can wind in this region, producing an electroweak string stabilised by the cosmic string background. In this case there are quark and lepton zero modes that result in the string be

W. M. Alberico, S. M. Bilenky, C. Giunti

The inclusive NC and CC neutrino(antineutrino)-nucleus scattering for the case of a nucleus with isotopic spin equal to zero is considered. It is shown that the measurement of the neutrino-antineutrino asymmetry at relatively small energies could allow to obtain model-independent information about the contribution of the axial strange current to the cross se

J. Rodriguez-Quintero

We investigate the scope of a previous result concerning the behaviour of fermions hitting a general wall caused by a first-order phase transition. The wall profile function was considered to be analytic in the real axis. The previous result is valid for analytic functions in the whole complex plane except in certain isolated singularities located out of the

D. Boer, R. D. Tangerman

We discuss a higher-twist factorization procedure of the hadron tensor in deep inelastic scattering, proposed by Qiu, and extend it to include quark mass terms. Its property that the hard scattering parts are electromagnetic gauge invariant separately, is manifestly preserved. Using an auxiliary parton, a so-called spurion, to generate the quark mass terms,

R. Jakob, A. Kotzinian, P. J. Mulders, J. Rodrigues

The role of transverse momentum of quarks in semi-inclusive leptoproduction will be discussed. It involves generalized distribution and fragmentation functions which depend on both the longitudinal lightcone momentum fraction of the quarks and on the transverse momentum. Constraints on these functions and relations between them arise as a consequence of the

Dirk Graudenz

The prospects for a determination of the strong coupling constant $α_s$ via scaling violations of fragmentation functions in deeply inelastic scattering are studied. The statistical error in the case of an integrated luminosity of $250 pb^{-1}$, and the theoretical errors due to the various parton density parametrizations and to the factorization scale depen

M. Arneodo, L. Lamberti, M. Ryskin

We present a Monte Carlo generator for exclusive vector meson production in charged lepton-proton interactions, l+p --> l+p+V, based on a QCD leading logarithm model calculation according to which the cross section for this process is proportional to the square of the gluon momentum density in the proton. The generator can be used for both fixed target and c

A. B. Lahanas, V. C. Spanos

We calculate the one-loop supersymmetric QCD corrections to the width of the $W$-boson. We find that these are of order $\sim {{ α_s} \over π} {1 \over 20} { {M^2_W} \over {M_S^2}} Γ_{u {\bar d}}$, where $M_S$ is the supersymmetry breaking scale and $ Γ_{u {\bar d}}$ the tree level hadronic width for $W^+ \rightarrow u {\bar d} $. Due to the appearance of th

N. N. Achasov, V. V. Gubin, E. P. Solodov

We describe the interference between amplitudes $e^+e^- \to ρ\to γπ^+π^-$ and $e^+e^- \to ϕ\to γf_0 \to γπ^+π^-$, where $f_0$ meson is considered in the frameworks of the four-quark model and the model of the scalar $K\bar K$ molecule. The general expressions for the differential cross section with the radiative corrections and two angle cuts are given. The

R. Engel, J. Ranft, S. Roesler

High energy photoproduction off nuclear targets is studied within the Glauber-Gribov approximation. The photon is assumed to interact as a $q\bar{q}$-system according to the Generalized Vector Dominance Model and as a ``bare photon&#39;&#39; in direct scattering processes with target nucleons. We calculate total cross sections for interactions of photons wit

Frank E. Close, Glennys R. Farrar, Zhenping Li

We develop tools to determine the gluonic content of a resonance of known mass, width and $J^{PC}$ from its branching fraction in radiative quarkonium decays and production cross section in $γγ$ collisions. We test the procedures by applying them to known $q\bar{q}$ mesons, then analyze four leading glueball candidates. We identify inconsistencies in data fo

M. Kuhlen

In order to probe the dynamics of parton evolution in deep inelastic scattering at small x, high-p_T particles produced centrally in pseudorapidity are studied. In the BFKL mechanism gluon radiation is expected to be more abundant than for DGLAP evolution with strong ordering of the gluon transverse momenta, leading to harder p_T spectra. The proposed measur

Abhay Ashtekar

3-dimensional gravity coupled to Maxwell (or Klein-Gordon) fields is exactly soluble under the assumption of axi-symmetry. The solution is used to probe several quantum gravity issues. In particular, it is shown that the quantum fluctuations in the geometry are large unless the number and frequency of photons satisfy the inequality $\N(\hbar Gω)^2 << 1$. Thu

Rob Kusner, Nick Schmitt

The spinor representation is developed for conformal immersions of Riemann surfaces into space. We adapt the approach of Dennis Sullivan, which treats a spin structure on a Riemann surface M as a complex line bundle S whose square is the canonical line bundle K=T(M). Given a conformal immersion of M into \bbR^3, the unique spin strucure on S^2 pulls back via

K. Brauckmann, R. Kusner

We give necessary conditions on complete embedded \cmc surfaces with three or four ends subject to reflection symmetries. The respective submoduli spaces are two-dimensional varieties in the moduli spaces of general \cmc surfaces. We characterize fundamental domains of our \cmc surfaces by associated great circle polygons in the three-sphere.

Swapan K. Pati, S. Ramasesha, Diptiman Sen

We report spin wave and DMRG studies of the ground and low-lying excited states of uniform and dimerized alternating spin chains. The DMRG procedure is also employed to obtain low-temperature thermodynamic properties of the system. The ground state of a 2N spin system with spin-1 and spin-1/2 alternating from site to site and interacting via an antiferromagn

Derek K. K. Lee, Patrick A. Lee

We propose that the normal-state transport in the cuprate superconductors can be understood in terms of a two-fluid model of spinons and holons. In our scenario, the resistivity is determined by the properties of the holons while magnetotransport involves the recombination of holons and spinons to form physical electrons. Our model implies that the Hall tran

R. Badrinarayanan, Jorge V. José

We investigate the classical and quantum dynamics of an electron confined to a circular quantum dot in the presence of homogeneous $B_{dc}+B_{ac}$ magnetic fields. The classical motion shows a transition to chaotic behavior depending on the ratio $ε=B_{ac}/B_{dc}$ of field magnitudes and the cyclotron frequency ${\tildeω_c}$ in units of the drive frequency.

Gary Oas

Random matrix models consisting of normal matrices, defined by the sole constraint $[N^†,N]=0$, will be explored. It is shown that cubic eigenvalue repulsion in the complex plane is universal with respect to the probability distribution of matrices. The density of eigenvalues, all correlation functions, and level spacing statistics are calculated. Normal mat

P. Chandra, M. V. Feigelman, M. E. Gershenson, L. B. Ioffe

We summarize recent work on a frustrated periodic long-range Josephson array in a parameter regime where its dynamical behavior is identical to that of the $p=4$ disordered spherical model. We also discuss the physical requirements imposed by the theory on the experimental realization of this superconducting network.

Roy Bar-Ziv, J. David Moroz, Elisha Moses, Philip Nelson

Irradiation of a giant unilamellar lipid bilayer vesicle with a focused laser spot leads to a tense pressurized state which persists indefinitely after laser shutoff. If the vesicle contains another object it can then be gently and continuously expelled from the tense outer vesicle. Remarkably, the inner object can be almost as large as the parent vesicle; i

Udo Seifert, Julian Shillcock, Philip Nelson

Lipid bilayer membranes below their main transition have two tilt order parameters, corresponding to the two monolayers. These two tilts may be strongly coupled to membrane shape but only weakly coupled to each other. We discuss some implications of this observation for rippled and saddle phases, bilayer tubules, and bicontinuous phases. Tilt difference intr

R. Mélin, B. Doucot

We study the effect of an electric charge in the middle of a ring of electrons in a magnetic field such as $ν= 1/2$. In the absence of the central charge, a residual current should appear due to an Aharanov-Bohm effect. As the charge varies, periodic currents should appear in the ring. We evaluate the amplitude of these currents, as well as their period as t

Douglas Davidson, Marcel den Nijs

The staggered 6-vertex model describes the competition between surface roughening and reconstruction in (100) facets of CsCl type crystals. Its phase diagram does not have the expected generic structure, due to the presence of a fully-packed loop-gas line. We prove that the reconstruction and roughening transitions cannot cross nor merge with this loop-gas l

J. Horbach, W. Kob, K. Binder, C. A. Angell

We present the results of a molecular dynamics computer simulation in which we investigate the dynamics of silica. By considering different system sizes, we show that in simulations of the dynamics of this strong glass former surprisingly large finite size effects are present. In particular we demonstrate that the relaxation times of the incoherent intermedi

A. S. Alexandrov

The resonance Wigner scattering of charged bosons (small bipolarons) in a random potential leads to logarithmically divergent low-temperature resistivity as observed in several cuprates. Unusual temperature dependence of resistivity of $La_{2-x}Sr_{x}CuO_{4}$ as well as of the Hall effect is quantitatively described in a wide temperature range providing an e

Martin Zapotocky, Dmitrii L. Maslov, Paul M. Goldbart

It is shown, within the framework of the Ginzburg-Landau theory for a superconductor with d_{x^2-y^2} symmetry, that the passing of a supercurrent through the sample results, in general, in the induction of order-parameter components of distinct symmetry. The induction of s-wave and d_{xy(x^2-y^2)-wave components are considered in detail. It is shown that in

Alon Drory

I consider a one dimensional system of particles which interact through a hard core of diameter $\si$ and can connect to each other if they are closer than a distance $d$. The mean cluster size increases as a function of the density $ρ$ until it diverges at some critical density, the percolation threshold. This system can be mapped onto an off-lattice genera

D. P. Chu, M. G. Dowsett, G. A. Cooke

The noise in the depth profiles of secondary ion mass spectrometry (SIMS) is studied using different samples under various experimental conditions. Despite the noise contributions from various parts of the dynamic SIMS process, its overall character agrees very well with the Poissonian rather than the Gaussian distribution in all circumstances. The Poissonia

Zbigniew Koza

We examine the long-time behaviour of A+B \to 0 reaction-diffusion systems with initially separated species A and B. All of our analysis is carried out for arbitrary (positive) values of the diffusion constant D_A of particles A and initial concentrations a_0 and b_0 of A&#39;s and B&#39;s. We derive general formulae for the location of the reaction zone cen

Assa Auerbach

Buckminsterfullerene compounds exibit remarkable physics at low temperatures, e.g. high temperature superconductivity in alkali-fullerenes, and ferromagnetism in TDAE -C60. Here we review recent theoretical studies of electron correlations in these compounds. In particular, we discuss models of electron-vibron interactions, electron-electron interactions, an

F. Vistulo de Abreu, B. Doucot

We derive a general set of Poor Man&#39;s scaling equations and analyze the stability of the Luttinger state in a system composed of a finite number N of one dimensional spinless fermionic chains, coupled through a general two body interaction. The effect of processes with momentum transfer parallel to the Fermi surface in destroying massless states is inves

R. Oppermann, B. Rosenow

This article reviews recent progress of the analytical theory of quantum spin glasses (QSG). Exact results for infinite range and one loop renormalisation group calculations for finite range models of either insulating or metallic type are presented. We describe characteristics of fermionic spin glass transitions and of fermionic correlations which are affec

R. H. M. Schoenmakers

A new method for measuring deviations from axisymmetry in the velocity fields of gas disks is presented. The method is an extension of the method that Franx, van Gorkom and de Zeeuw developed for a single orbit gas ring. The measurement is based upon a higher order harmonic expansion of the full velocity field. Epicyclic theory is used to calculate the effec

A. Del Popolo, M. Gambera

We solve numerically the equations of motion for the collapse of a shell of baryonic matter, made of galaxies and substructure of $ 10^{6} M_{\odot}- 10^{9} M_{\odot}$, falling into the central regions of a cluster of galaxies taking account of dynamical friction. We calculate the evolution of the expansion parameter, a(t), of the perturbation using a coeffi

A. Kashlinsky, J. C. Mather, S. Odenwald

We measure the smoothness of the infrared sky using the COBE DIRBE maps, and obtain interesting limits on the production of the diffuse cosmic infrared background (CIB) light by matter clustered like galaxies. The predicted fluctuations of the CIB with the DIRBE beam size of 0.7° are of the order of 10\%, and the maps are smooth at the level of $δνI_ν\sim $

Piercarlo Bonifacio, Paolo Molaro

Lithium abundances in a selected sample of halo stars have been revised by using new accurate Teff. From 41 plateau stars we found no evidence for intrinsic dispersion, a tiny trend with Teff and no trend with [Fe/H]. These results argue against depletion by either stellar winds, diffusion or rotational mixing. Therefore the Li observed in PopII stars provid

Heino Falcke, Alok Patnaik, William Sherwood

We present VLBI (EVN+MERLIN) observations of a sample of three low-redshift radio-intermediate PG quasars (RIQ) with flat and variable radio spectrum (III Zw 2, PG 1309+355, PG 2209+184). Their radio-to-optical flux ratio (R) is slightly lower than the average R for steep-spectrum quasars, but their radio spectral properties are those of core-dominated quasa

Abraham Loeb, Alexandre Refregier

The Sunyaev-Zel&#39;dovich (SZ) effect of a cluster of galaxies is usually measured after background radio sources are removed from the cluster field. Gravitational lensing by the cluster potential leads to a systematic deficit in the residual intensity of unresolved sources behind the cluster core relative to a control field far from the cluster center. As

Onuttom Narayan

A model for domain wall motion in ferromagnets is analyzed. Long-range magnetic dipolar interactions are shown to give rise to self-similar dynamics when the external magnetic field is increased adiabatically. The power spectrum of the resultant Barkhausen noise is of the form $1/ω^α$, where $α\approx 1.5$ can be estimated from the critical exponents for int

H. C. Rosu

I report a study of the nonstationary one-dimensional Fokker-Planck solutions by means of the strictly isospectral method of supesymmetric quantum mechanics. The main conclusion is that this technique can lead to a space-dependent (modulational) damping of the spatial part of the nonstationary Fokker-Planck solutions, which I call strictly isospectral dampin

Hao-wen Xi, Xiao-jun Li, J. D. Gunton

We present the first large scale numerical simulation of three-dimensional Rayleigh-Bénard convection near onset, under free-free boundary conditions for a fluid of Prandtl number $σ=0.5$. We find that a spatiotemporally chaotic state emerges immediately above onset, which we investigate as a function of the reduced control parameter $ε$. We conclude that th