February 2000 arXiv papers — page 12

V. Avila-Reese, C. Firmani, A. Klypin, A. V. Kravtsov

We present results of extensive model calculations of disk galaxy evolution within an hierarchical inside-out formation scenario. We first compare properties of the dark halos identified in a cosmological N-body simulation with predictions of a seminumerical method based on an extended collapse model and find a good agreement. We also study the properties of

L. Bergstrom, U. Danielsson

The observational evidence for the existence of a non-zero cosmological constant is getting stronger. It is therefore timely to address the question of its eventual effect on the dynamics of galaxies, clusters and larger structures in the Universe. We find, contrary to a recent claim, that the influence of the cosmological constant has to be negligible for,

Seiji Terashima

We consider the supersymmetric field theories on the noncommutative $R^4$ using the superspace formalism on the commutative space. The terms depending on the parameter of the noncommutativity $Θ$ are regarded as the interactions. In this way we construct the N=1 supersymmetric action for the U(N) vector multiplets and chiral multiplets of the fundamental, an

Shamit Kachru, Michael Schulz, Eva Silverstein

We discuss maximally symmetric curved deformations of the flat domain wall solutions of five-dimensional dilaton gravity that appeared in a recent approach to the cosmological constant problem. By analyzing the bulk field configurations and the boundary conditions at a four-dimensional maximally symmetric curved domain wall, we obtain constraints on such sol

Ola Tornkvist

In this talk, I review a number of particle-physics models that lead to the creation of magnetic fields in the early universe and address the complex problem of evolving such primordial magnetic fields into the fields observed today. Implications for future observations of the Cosmic Microwave Background (CMB) are discussed. Focussing on first-order phase tr

Vatche Sahakian

We review the de Boer-Verlinde-Verlinde formalism for the renormalization group in the context of Dp brane vacua. We comment on various aspects of the dictionary between bulk and boundary and relate the discussion to the Randall-Sundrum scenario. We find that the gravitational coupling for the Randall-Sundrum gravity on the Dp brane worldvolume is proportion

David A. Brown, Sergei Y. Panitkin, George F. Bertsch

The space-averaged phase-space density and entropy per particle are both fundamental observables which can be extracted from the two-particle correlation functions measured in heavy-ion collisions. Two techniques have been proposed to extract the densities from correlation data: either by using the radius parameters from Gaussian fits to meson correlations o

Hai-Yang Cheng

The proton spin puzzle inspired by the EMC experiment and its present status are closely examined. Recent experimental progress is reviewed. Various factorization schemes due to the ambiguity arising from the axial anomaly are discussed. Some misconceptions in the literature about the $\MS$ factorization scheme are clarified. It is stressed that the polarize

P. Mukherjee, A. W. Jones, R. Kneissl, A. N. Lasenby

Recently correlation analyses between Galactic dust emission templates and a number of CMB data sets have led to differing claims on the origin of the Galactic contamination at low frequencies. de Oliviera-Costa {\em et al} (1999) have presented work based on Tenerife data supporting the spinning dust hypothesis. Since the frequency coverage of these data is

P. Jankowski, M. Krawczyk, A. De Roeck

A high energy linear e^+e^- collider (LC) can also be used as a Photon Collider (PC), using Compton scattering of laser photons on the e^+/e^- beams. The leading order cross-section for the production of heavy quarks, e^+e^- -> e^+e^- Q(\bar{Q}) X, at high transverse momenta is calculated for both LC and PC modes. The sensitivity of this process to the parto

D. A. Contreras-Solorio, S. T. Pavlov, L. I. Korovin, I. G. Lang

The method of detection and investigation of the magnetopolaron effect in the semiconductor quantum wells (QW) in a strong magnetic field, based on pulse light irradiation and measuring the reflected and transmitted pulses, has been proposed. It has been shown that a beating amplitude on the frequencies, corresponding to the magnetopolaron energy level split

Luca Bombelli

I introduce a family of closeness functions between causal Lorentzian geometries of finite volume and arbitrary underlying topology. When points are randomly scattered in a Lorentzian manifold, with uniform density according to the volume element, some information on the topology and metric is encoded in the partial order that the causal structure induces am

Yosef Nir

Three of the viable solutions of the solar neutrino problem are consistent with close to maximal leptonic mixing: $\sin^2θ_{12}={1\over2}(1-ε_{12})$ with $|ε_{12}|\ll1$. Flavor models can naturally explain close to maximal mixing if approximate horizontal symmetries force a pseudo-Dirac structure on the neutrino mass matrix. An experimental determination of

John Toth, Steve Zelditch

The standard eigenfunctions $ϕ_λ = e^{i < λ, x >}$ on flat tori $\R^n / L$ have $L^{\infty}$-norms bounded independently of the eigenvalue. In the case of irrational flat tori, it follows that $L^2$-normalized eigenfunctions have uniformly bounded $L^{\infty}$-norms. Similar bases exist on other flat manifolds. Does this property characterize flat manifolds?

V. Skalsky

In the standard model of universe the increase in mass of our observed expansive and isotropic relativistic Universe is explained by the hypothetical assumption of matter objects emerging on the horizon (of the most remote visibility). However, the mathematical-physical analysis of the increase of Universe gauge factor shows that this hypothetical assumption

Catherine Pepin, Patrick A. Lee

We present a method to compute the density of states induced by N non magnetic impurities in a d-wave superconductor, in the unitary limit of very strong scatering centers. For frequencies very small as compared to the superconducting gap ($ω\ll Δ_0$) the additional density of states has the leading divergence ${\displaystyle δρ(ω) \simeq n_i / [ | 2 ω| (\ln

Marc-Andre Lewis, Yvan Saint-Aubin

Langlands recently constructed a map that factorizes the partition function of a free boson on a cylinder with boundary condition given by two arbitrary functions in the form of a scalar product of boundary states. We rewrite these boundary states in a compact form, getting rid of technical assumptions necessary in his construction. This simpler form allows

J. G. Koerner, F. Krajewski, A. A. Pivovarov

We extract a numerical value for the strong coupling constant α_s from the τ-lepton decay rate into nonstrange particles. A new feature of our procedure is the explicit use of renormalization scheme invariance in analytical form in order to perform the actual analysis in a particular renormalization scheme. For the reference coupling constant in the \MSsch-s

Bert-Jan Nauta

We calculate the effect of two CP-violating (dimension-eight) operators of the SU(2)-Higgs model on the motion along a particular path from the vacuum to the sphaleron. It turns out that CP-violation may introduce a difference between the sphaleron rate towards larger Chern-Simons number and the rate towards smaller Chern-Simons number. Such a difference ind

Zdzislaw A. Golda, Andrzej Woszczyna

Appealing to classical methods of order reduction, we reduce the Lifshitz system to a second order differential equation. We demonstrate its equivalence to well known gauge-invariant results. For a radiation dominated universe we express the metric and density corrections in their exact forms and discuss their acoustic character.

Zdzislaw A. Golda, Andrzej Woszczyna

A simple perturbation description unique for all signs of curvature, and based on the gauge-invariant formalisms is proposed to demonstrate that: (1) The density perturbations propagate in the flat radiation-dominated universe in exactly the same way as electromagnetic or gravitational waves propagate in the epoch of the matter domination. (2) In the open un

E. Cappelluti, C. Grimaldi, L. Pietronero, S. Strässler

This paper has been withdrawn. An extended version of this work can be found in E. Cappelluti, C. Grimaldi, L. Pietronero, S. Straessler: Phys. Rev. Lett. 85, 4771 (2000) [cond-mat/0105560] and E. Cappelluti, C. Grimaldi, L. Pietronero, S. Straessler, G.A. Ummarino: Eur. Phys. J. B 21, 383 (2001) [cond-mat/0104457]

Akihisa Tomita, Osamu Hirota

We examine security of a protocol on cryptographic key distribution via classical noise proposed by Yuen and Kim (Phys. Lett. A 241 135 (1998)). Theoretical and experimental analysis in terms of the secure key distribution rate shows that secure key distribution is possible even if the eavesdropper could receive more photons than the legitimate receiver, as

B. Roy, P. Roy

We study phase properties of a displacement operator type nonlinear coherent state. In particular we evaluate the Pegg-Barnett phase distribution and compare it with phase distributions associated with the Husimi Q function and the Wigner function. We also study number- phase squeezing of this state.

Yasuhiro Fujii, Miki Wadati

Correlation functions of the XXZ spin chain in the critical regime is studied at zero-temperature. They are exactly represented in the Fredholm determinant form and are related with an operator-valued Riemann-Hilbert problem. Analyzing this problem we prove that a two-point correlation function consisting of sufficiently separated spin operators is expressed

Nadia Fettes, Ulf-G. Meißner

We analyse elastic-pion nucleon scattering to fourth order in heavy baryon chiral perturbation theory, extending the third order study published in Nucl. Phys. A640 (1998) 199. We use various partial wave analyses to pin down the low-energy constants from data in the physical region. The S-wave scattering lengths are consistent with recent determinations fro

Christian W. Bauer, Zoltan Ligeti, Michael Luke

It is shown that measuring the lepton invariant mass spectrum in inclusive semileptonic B -> X_u l nu decay yields a model independent determination of |V_{ub}|. Unlike the lepton energy and hadronic invariant mass spectra, nonperturbative effects are only important in the resonance region, and play a parametrically suppressed role when dΓ/dq^2 is integrated

Michael I. Eides, Howard Grotch, and Valery A. Shelyuto

The present status and recent developments in the theory of light hydrogenic atoms, electronic and muonic, are extensively reviewed. The discussion is based on the quantum field theoretical approach to loosely bound composite systems. The basics of the quantum field theoretical approach, which provide the framework needed for a systematic derivation of all h

M. V. Karasev, T. A. Osborn

A gauge invariant quantization in a closed integral form is developed over a linear phase space endowed with an inhomogeneous Faraday electromagnetic tensor. An analog of the Groenewold product formula (corresponding to Weyl ordering) is obtained via a membrane magnetic area, and extended to the product of N symbols. The problem of ordering in quantization i

Alexander Yu. Vlasov

The canonical anticommutation relations (CAR) for fermion systems can be represented by finite-dimensional matrix algebra, but it is impossible for canonical commutation relations (CCR) for bosons. After description of more simple case with representation of CAR and (bounded) quantum computational networks via Clifford algebras in the paper are discussed CCR

Vladimir N. Serkin, Akira Hasegawa

The nonlinear pulse propagation in an optical fibers with varying parameters is investigated. The capture of moving in the frequency domain femtosecond colored soliton by a dispersive trap formed in an amplifying fiber makes it possible to accumulate an additional energy and to reduce significantly the soliton pulse duration. Nonlinear dynamics of the chirpe

P. A. Barton, C. J. S. Donald, D. M. Lucas, D. A. Stevens

We report a measurement of the lifetime of the 3d 2D_{5/2} metastable level in 40Ca+, using quantum jumps of a single cold calcium ion in a linear Paul trap. The 4s S_{1/2} - 3d D_{5/2} transition is significant for single-ion optical frequency standards, astrophysical references, and tests of atomic structure calculations. We obtain tau = 1.168 +- 0.007 s f

K. B. Korotchenko

The object of this laboratory work: to explore dependence mass point oscillatory motion parameters in the following cases: - without resistance (free oscillations); - the resistance force is proportional to the velocity vector; - the resistance force is proportional to the velocity squared. Used equipment: the work have doing on a personal computer. The osci

Eugenio DelRe, Mario Tamburrini, Aharon J. Agranat

The combination of charge separation induced by the formation of a single photorefractive screening soliton and an applied external bias field in a paraelectric is shown to lead to a family of useful electro-optic guiding patterns and properties.

J. A. Belinchon

A model with flat FRW symmetries and G and Lambda variable,is considered in such a way that the momentum-energy tensor that describes the model is characterized by a bulk viscosity parameter. In this paper it is showed how to apply the dimensional method in order to solve the outlined equations in a trivial way.

P. Huovinen, V. Koch

Transport and hydrodynamical models used to describe the expansion stage of a heavy-ion collision at the CERN SPS give different dilepton spectrum even if they are tuned to reproduce the observed hadron spectra. To understand the origin of this difference we compare the dilepton emission from transport and hydrodynamical models using similar initial states i

Jutta Escher, Amiram Leviatan

The relevance of the partial dynamical symmetry concept for an interacting fermion system is demonstrated. Hamiltonians with partial SU(3) symmetry are presented in the framework of the symplectic shell-model of nuclei and shown to be closely related to the quadrupole-quadrupole interaction. Implications are discussed for the deformed light nucleus $^{20}$Ne

H. Yamamura, K. Miyagawa, T. Mart, C. Bennhold

We analyze the reaction gamma + d --> K^+ + Lambda (Sigma) + N using the Nijmegen soft core hyperon-nucleon interactions NSC97f and NSC89 and a recently updated production operator for the gamma + N --> K^+ + Lambda(Sigma) processes. Significant effects of the YN final state interaction are found near both the K^+ Lambda N and K^+ Sigma N thresholds.

T. Mart, S. Sumowidagdo, C. Bennhold, H. Haberzettl

Using an isobar model which can reproduce the existing experimental data of kaon photoproduction on the nucleon we investigate some related phenomenological aspects, i.e. the hadronic form factors, contributions of kaon-hyperon final states to the anomalous magnetic moment of the nucleon, and missing nucleon resonances. By reggeizing the appropriate propagat

K. Miyagawa, H. Kamada, W. Gloeckle, H. Yamamura

This paper summarizes our studies of the hypertriton and describes our findings on the hyperon-nucleon interaction, especially on the role of the $ΛN-ΣN$ coupling and the strengths of the $S$-wave $YN$ interactions. We briefly comment on our ongoing analyses with electromagnetic probes.

Piotr G. Grinevich

It is shown, that any sufficiently smooth periodic solution of the self-focusing Nonlinear Schrödinger equation can be approximated by periodic finite-gap ones with an arbitrary small error. As a corollary an analogous result for the motion of closed curves in ${\Bbb R}^3$ guided by the Filament equation is proved. This equation describes the dynamics of ver

Nenad Manojlovic, Aleksandar Mikovic

We show that \a < 0, \b > 0, \g=\d=0 Painleve III equation arises as a zero-curvature condition in the Belinskii-Zakharov inverse-scattering formulation for Bianchi cosmological models. For special values of the parameters this Painleve III equation becomes the dynamical equation for Bianchi I, II, VI_0 and VII_0 models.

Sharon Schaffer, Eric Weber

All wavelets can be associated to a multiresolution like structure, i.e. an incr easing sequence of subspaces of L^2(R). We consider the interaction of a wavel et and the translation operator in terms of which of the subspaces in this multi resolution like structure are invariant under the translation operator. This ac tion defines the notion of the translat

Alexander Gorokhovsky

We give a construction of cyclic cocycles representing the equivariant characteristic classes of equivariant bundles. Our formulas generalize Connes&#39; Godbillon-Vey cyclic cocycle. An essential tool of our construction is Connes-Moscovici&#39;s theory of cyclic cohomology of Hopf algebras.

Alain Connes, Henri Moscovici

Cyclic cohomology has been recently adapted to the treatment of Hopf symmetry in noncommutative geometry. The resulting theory of characteristic classes for Hopf algebras and their actions on algebras allows to expand the range of applications of cyclic cohomology. It is the goal of the present paper to illustrate these recent developments, with special emph

Ignasi Mundet i Riera

Let X be a compact manifold with a smooth action of a compact connected Lie group G. Let $L\to X$ be a complex line bundle. Using the Cartan complex for equivariant cohomology, we give a new proof of a theorem of Hattori and Yoshida which says that the action of G lifts to L if and only if the first Chern class $c\sb 1(L)$ of L can be lifted to an integral e

Antoine Van Proeyen

The geometry that is defined by the scalars in couplings of Einstein-Maxwell theories in N=2 supergravity in 4 dimensions is denoted as special Kaehler geometry. There are several equivalent definitions, the most elegant ones involve the symplectic duality group. The original construction used conformal symmetry, which immediately clarifies the symplectic st

Ignasi Mundet i Riera

In this paper we introduce invariants of semi-free Hamiltonian actions of $S\sp 1$ on compact symplectic manifolds (which satisfy some technical conditions related to positivity) using the space of solutions to certain gauge theoretical equations. These equations generalize at the same time the vortex equations and the holomorphicity equation used in Gromov-

Krzysztof Fraczek

In this paper we introduce the notion of degree for $C^1$-cocycles over irrational rotations on the circle with values in the group SU(2). It is shown that if a $C^1$-cocycle $ϕ:S^1\to SU(2)$ over an irrational rotation by $α$ has nonzero degree, then the skew product $S^1\times SU(2)\ni(x,g)\mapsto (x+α,gϕ(x))\in S^1\times SU(2)$ is not ergodic and the grou

Angie Chandler, Anne Heyworth

This paper contains introductory material on Petri nets and Groebner basis theory and makes some observations on the relation between the two areas. The aim of the paper is to show how Groebner basis procedures can be applied to the problem of reachability in Petri nets, and to give details of an application to testing models of navigational systems.

Ranee Brylinski

Let M be a Galois cover of a nilpotent coadjoint orbit of a complex semisimple Lie group. We define the notion of a PERFECT Dixmier algebra for M and show how this produces a graded (non-local) equivariant star product on M with several very nice properties. This is part of a larger program we have been developing for working out the orbit method for nilpote

Ranee Brylinski

We construct by geometric methods a noncommutative model E of the algebra of regular functions on the universal (2-fold) cover M of certain nilpotent coadjoint orbits O for a complex simple Lie algebra g. Here O is the dense orbit in the cotangent bundle of the generalized flag variety X associated to a complexified Cartan decomposition g=(p^+)+k+(p^-) where

Dmitri Tamarkin, Boris Tsygan

We define a notion of astrongly homotopy BV algebra and apply it to deformation theory problems. Formality conjectures for Hochschild and cyclic chains are formulated. We prove some partial results supporting these conjectures.

Andrew Hassell, Andras Vasy

Let X be a compact manifold with boundary, and g a scattering metric on X, which may be either of short range or `gravitational&#39; long range type. Thus, g gives X the geometric structure of a complete manifold with an asymptotically conic end. Let H be an operator of the form $H = Δ+ P$, where $Δ$ is the Laplacian with respect to g and P is a self-adjoint

Jason Fulman

Using representation theoretic work on the Whitehouse module, a formula is obtained for the cycle structure of a riffle shuffle followed by a cut. This result will be merged with the paper [F6].

David M. J. Calderbank, Tammo Diemer

We give a simple construction of the Bernstein-Gelfand-Gelfand sequences of natural differential operators on a manifold equipped with a parabolic geometry. This method permits us to define the additional structure of a bilinear differential cup product on this sequence, satisfying a Leibniz rule up to curvature terms. It is not associative, but is part of a

M. Cvetic, H. Lu, J. F. Vazquez-Poritz

The absorption in the extremal D3-brane background is studied for a class of massless fields whose linear perturbations leave the ten-dimensional background metric unperturbed, as well as the minimally-coupled massive scalar. We find that various fields have the same absorption probability as that of the dilaton-axion system, which is given exactly via the M

Tamas Hauer, Amer Iqbal, Barton Zwiebach

Extending earlier results on the duality symmetries of three-brane probe theories we define the duality subgroup of SL(2,Z) as the symmetry group of the background 7-branes configurations. We establish that the action of Weyl reflections is implemented on junctions by brane transpositions that amount to exchanging branes that can be connected by open strings

G. Delfino, John Cardy

The q-state Potts model in two dimensions exhibits a first-order transition for q>4. As q->4+ the correlation length at this transition diverges. We argue that this limit defines a massive integrable quantum field theory whose lowest excitations are kinks connecting 4+1 degenerate ground states. We construct the S-matrix of this theory and the two-particle f

T. A. Ivanova, A. D. Popov

We consider holomorphic BF theories, their solutions and symmetries. The equivalence of Cech and Dolbeault descriptions of holomorphic bundles is used to develop a method for calculating hidden (nonlocal) symmetries of holomorphic BF theories. A special cohomological symmetry group and its action on the solution space are described.

Barak Kol, Michael Kroyter

We study the spatial structure of 1/4 BPS solitons in 4 dimensional N=4 gauge theory. A weak binding approximation is used where the soliton is made of several &#34;ingredient&#34; particles. Some spatial moduli are described which are not accounted for in the (p,q) web picture. These moduli are counted and their effect on the solutions is demonstrated. The

B. Borasoy

We compare two different frameworks which have been proposed to include the eta&#39; in chiral perturbation theory. The equivalence of these two approaches is shown both for the purely mesonic case and in the presence of the ground state baryon octet. The relation between the different sets of parameters in both Lagrangians is clarified.

N. Armesto, C. Pajares

Predictions on central rapidity densities of charged particles at energies of the Relativistic Heavy Ion Collider and the Large Hadron Collider, for central collisions between the largest nuclei that will be available at these accelerators, are reviewed. Differences among the results of the existing models are discussed in relation with their underlying phys

Kenichiro Aoki, Dimitri Kusnezov

Classical $ϕ^4$ theory in weak and strong thermal gradients is studied on the lattice in (1+1) dimensions. Classical $ϕ^4$ theory in weak and strong thermal gradients is studied on the lattice in (1+1) dimensions. The steady state physics of the theory is investigated from first principles and classified into dynamical regimes. We derive the bulk properties

Morimitsu Tanimoto

We have obtained the neutrino mass matrix with the large mixing angle (LMA) MSW solution, $\sin^2 2þ_\odot=0.65\sim 0.97$ and $Δm_{\odot}^2= 10^{-5}\sim 10^{-4}\eV^2$, in the $S_{3L}\times S_{3R}$ flavor symmetry. The structure of our neutrino mass matrix is found to be stable against radiative corrections.

A. Morelos

A summary of the path which lead to a high energy physics group at Instituto de Fisica de la Universidad Autonoma de San Luis Potosi is presented. This group is the result of the initial push made by Leon Lederman at the beginning of the 80's.

D. Pitzl

The design, construction and performance of the H1 silicon vertex detector is described. It consists of two cylindrical layers of double sided, double metal silicon sensors read out by a custom designed analog pipeline chip. The analog signals are transmitted by optical fibers to a custom designed ADC board and are reduced on PowerPC processors. Details of t

L3 Collaboration

A search for charginos nearly mass-degenerate with the lightest supersymmetric particle is performed using the 176 pb^-1 of data collected at 189 GeV in 1998 with the L3 detector. Mass differences between the chargino and the lightest supersymmetric particle below 4 GeV are considered. The presence of a high transverse momentum photon is required to single o

C. Giunti

It is shown that all the Frequentist methods are equivalent from a statistical point of view, but the physical significance of the confidence intervals depends on the method. The Bayesian Ordering method is presented and confronted with the Unified Approach in the case of a Poisson process with background. Some criticisms to both methods are answered. It is

C. N. Ferreira, M. E. X. Guimaraes, J. A. Helayel-Neto

We study the modifications on the metric of an isolated self-gravitating bosonic superconducting cosmic string in a scalar-tensor gravity in the weak-field approximation. These modifications are induced by an arbitrary coupling of a massless scalar field to the usual tensorial field in the gravitational Lagrangian. The metric is derived by means of a matchin

B. Jancovici

The pressure in a classical Coulomb fluid at equilibrium is obtained from the Maxwell tensor at some point inside the fluid, by a suitable statistical average. For fluids in an Euclidean space, this is a fresh look on known results. But, for fluids in a curved space, a case which is of some interest, the unambiguous results from the Maxwell tensor approach h

O. V. Dolgov, N. Schopohl

We show that Abrikosov vortices moving towards the surface of a superconductor emit electromagnetic radiation into free space. The frequency distribution of the radiated intensity displays a pronounced maximum at microwave frequencies around v_x/lambda, where lambda is the magnetic penetration length. Coherent motion of a lattice of flux lines leads to const

Yi Chen, Philip Nelson

Bilayer vesicles form readily from mixtures of charged and neutral surfactants. When such a mixed vesicle binds an oppositely-charged object, its membrane partially demixes: the adhesion zone recruits more charged surfactants from the rest of the membrane. Given an unlimited supply of adhering objects one might expect the vesicle to remain attractive until i

Brian P. Dolan

At low temperatures the phase diagram for the quantum Hall effect has a powerful symmetry arising from the Law of Corresponding States. This symmetry gives rise to an infinite order discrete group which is a generalisation of Kramers-Wannier duality for the two dimensional Ising model. The duality group, which is a subgroup of the modular group, is analysed

S. Luescher, T. Heinzel, K. Ensslin, W. Wegscheider

Coulomb blockade resonances are measured in a GaAs quantum dot in which both shape deformations and interactions are small. The parametric evolution of the Coulomb blockade peaks shows a pronounced pair correlation in both position and amplitude, which is interpreted as spin pairing. As a consequence, the nearest-neighbor distribution of peak spacings can be

T. Tohyama, S. Maekawa

The angle-resolved photoemission (ARPES) technique has been developed rapidly over the last decay, accompanied by the improvement of energy and momentum resolutions. This technique has been established as the most powerful tool to investigate the high Tc cuprate superconductors. We review recent ARPES data on the cuprates from a theoretical point of view, wi

Michael Marek Koza, Helmut Schober, Thomas Hansen, Albert Toelle

We present neutron powder diffraction results which give unambiguous evidence for the formation of the recently identified new crystalline ice phase[Lobban et al.,Nature, 391, 268, (1998)], labeled ice XII, at completely different conditions. Ice XII is produced here by compressing hexagonal ice I_h at T = 77, 100, 140 and 160 K up to 1.8 GPa. It can be main

Asish K. Dhara, S. R. Banerjee

Coherent stochastic resonance is explained in terms of first passage time density functions. Scaling relation between first passage time density functions at resonance for different lengths of the medium is obtained. A formula for first passage time density function at resonance is derived in terms of two universal functions, which demonstrates the universal

Rosario N. Mantegna, Bernardo Spagnolo

We experimentally investigate the escape from a metastable state over a fluctuating barrier of a physical system. The system is switching between two states under electronic control of a dichotomous noise. We measure the escape time and its probability density function as a function of the correlation rate of the dichotomous noise in a frequency interval spa

L. Brey, H. A. Fertig

We present results of a study of double layer quantum Hall systems in which each layer has a high-index Landau level that is half-filled. Hartree-Fock calculations indicate that, above a critical layer separation, the system becomes unstable to the formation of a unidirectional coherent charge density wave (UCCDW), which is related to stripe states in single

Ch. Schwan, F. Martin, G. Jakob, J. C. Martinez

We have investigated the crystal structure and the ferroelectric properties of BaTiO3 thin films with YBa2Cu3O7-d as the bottom and Au as the top electrode. Epitaxial heterostructures of YBa2Cu3O7-d and BaTiO3 were prepared by dc and rf sputtering, respectively. The crystal structure of the films was characterised by x-ray diffraction. The ferroelectric beha

V. Meden, W. Metzner, U. Schollwoeck, O. Schneider

We present a study of the one-particle spectral properties for a variety of models of Luttinger liquids with open boundaries. We first consider the Tomonaga-Luttinger model using bosonization. For weak interactions the boundary exponent of the power-law suppression of the spectral weight close to the chemical potential is dominated by a term linear in the in

Sungchul Kwon, Jysoo Lee, Hyunggyu Park

It has been generally believed that hardcore interaction is irrelevant to absorbing type critical phenomena because the particle density is so low near an absorbing phase transition. We study the effect of hardcore interaction on the N species branching annihilating random walks with two offspring and report that hardcore interaction drastically changes the

Sung-Sik Lee, Sung-Ho Suck Salk

Based on the SU(2) slave-boson approach to the t-J Hamiltonian, we examine the cause of the sharp peaks(&#39;quasiparticle&#39; peaks) in the observed spectral functions in high $T_c$ cuprates. The computed results reveal that the spectral weight of the sharp peaks increases with hole doping rate in agreement with observation. It is shown that the observed s

F. Minardi, C. Fort, P. Maddaloni, M. Inguscio

We have investigated the rf output coupling of a 87Rb condensate from a Ioffe-Pritchard magnetic trap. Multiple condensates in different Zeeman states are produced, their population being varied by playing with the duration and the amplitude of the rf pulse. Both pulsed and continuous outputs (atom laser) have been observed.

Charles D. Dermer, Markus Boettcher

The blast-wave model for gamma-ray bursts (GRBs) has been called into question by observations of spectra from GRBs that are harder than can be produced through optically thin synchrotron emission. If GRBs originate from the collapse of massive stars, then circumstellar clouds near burst sources will be illuminated by intense gamma radiation, and the electro

Ennio Poretti

The results obtained by means of the photometric approach to the study of Delta Sct stars are extensively discussed. The different frequency contents of the three best candidates for asteroseismological studies (FG Vir, 4 CVn and XX Pyx) are presented and compared; the importance of the amplitude variations and of the combination terms is emphasized. The ana

F. Mayet, D. Santos, G. Perrin, Yu. M. Bunkov

MACHe3 (MAtrix of Cells of superfluid He3) is a project of a new detector for direct Dark Matter (DM) search. A cell of superfluid He3 has been developed and the idea of using a large number of such cells in a high granularity detector is proposed. This paper presents, after a brief description of the superfluid He3 cell, the simulation of the response of di

L. C. Garcia de Andrade

Cartan torsion contribution to Sachs-Wolfe effect in the inflationary phase of the Universe is discussed.From the COBE data of the microwave anisotropy is possible to compute the spin-density in the Universe as $10^{16}$ mks units.The spin-density fluctuations at the hadron era is shown to coincide with the anisotropy temperature fluctuations.

Shijun Yoshida, Umin Lee

We investigate the properties of r-mode and inertial mode of slowly rotating, non-isentropic, Newtonian stars, by taking account of the effects of the Coriolis force and the centrifugal force. For the non-isentropic models we consider only two cases, that is, the models with the stable fluid stratification in the whole interior and the models that are fully

T. Liljestrom, C. R. Gwinn

We present spectroscopic results of 146 water maser outbursts in W49 N, obtained with the Metsahovi radio telescope at 22 GHz. Combining this data with Gwinn&#39;s VLBI results, we were able to fix the free parameters in the shock model of Hollenbach and McKee and the maser model of Elitzur, Hollenbach, and McKee. This enabled a straightforward determination

A. Wolter, F. Tavecchio, A. Caccianiga, G. Ghisellini

1ES1101-232 is a bright BL Lac of the High frequency peak class. We present here the results of two BeppoSAX observations in which the source has shown a variation of about 30% in flux with a corresponding spectral variability. We interpret the overall spectral energy distribution in terms of an homogeneous SSC model and, by using also the TeV upper limit fr

Carlos De Breuck, Wil van Breugel, Huub Rottgering, George Miley

Since radio sources with Ultra Steep Spectra (USS; alpha <~ -1.30; S ~ nu^alpha) are efficient tracers of high redshift radio galaxies (HzRGs), we have defined three samples of such USS sources using the recently completed WENSS, TEXAS, MRC, NVSS and PMN radio-surveys. Our combined sample contains 669 sources with S_1400 > 10 mJy and covers virtually the ent

S. M. Molnar, K. Jahoda

The formation and evolution of clusters of galaxies are sensitive to the underlying cosmological model. Constraints on cosmological parameters of cold dark matter models have been derived from mass, temperature and luminosity functions of clusters. We study the importance of including cluster formation history and a correction for collapsed fraction of objec

Mario Vietri

A small error was corrected.

Q. A. Turchette, D. Kielpinski, B. E. King, D. Leibfried

We have investigated motional heating of laser-cooled 9Be+ ions held in radio-frequency (Paul) traps. We have measured heating rates in a variety of traps with different geometries, electrode materials, and characteristic sizes. The results show that heating is due to electric-field noise from the trap electrodes which exerts a stochastic fluctuating force o

G. A. Miller, S. J. Brodsky, M. Karliner

We show that nuclear sigma, omega, and pi mesons can contribute coherently to enhance the electroproduction cross section on nuclei for longitudinal virtual photons at low Q^2 while depleting the cross section for transverse photons. We are able to describe recent HERMES inelastic lepton-nucleus scattering data at low Q^2 and small x using photon-meson and m

Jeffrey A. Harvey, Per Kraus

We construct Dp-branes in bosonic string theory as unstable lumps in a truncated string field theory of open strings on a D25-brane. We find that the lowest level truncation gives good quantitative agreement with the predicted D-brane tension and low-lying spectrum of the D-brane for sufficiently large p and study the effect of the next level corrections for

Irina Mocioiu, Robert Shrock

We calculate matter effects on neutrino oscillations relevant for long baseline experiments. In particular, we compare the results obtained with constant density along the neutrino path versus results obtained by incorporating the actual density profiles in the Earth. We study the dependence of the oscillation signal on both $E/Δm^2_{atm}$ and on the angles

Alexander Soshnikov

The paper contains an exposition of recent as well as old enough results on determinantal random point fields. We start with some general theorems including the proofs of the necessary and sufficient condition for the existence of the determinantal random point field with Hermitian kernel and a criterion for the weak convergence of its distribution. In the s