July 2000 arXiv papers — page 17

Rob Ivison

Most new sub-mm/mm surveys, both deep and shallow, are being targeted at rich cluster fields. I explain why, comparing surveys that have exploited weak lensing by massive foreground clusters with those done in blank fields.

Dario Trevese, Fausto Vagnetti

A new analysis of the variability of the spectral slope of PG QSOs has been performed, on the basis of recent literature data in the B and R photometric bands. Preliminary results confirm our previous findings concerning the increase of variability with the rest-frame observing frequency. We also find a correlation of the spectral slope with luminosity, cons

Kathryn V Johnston

The launching of up to four astrometric missions in the next decade will enable us to make measurements of stars in tidal streamers from Galactic satellites of sufficient accuracy to place strong constraints on the mass distribution in the Milky Way. In this paper we simulate observations of debris populations in order to assess the required properties of an

David J James, Moira M Jardine, Robin D Jeffries, Sofia Randich

A rotation rate and X-ray luminosity analysis is presented for rapidly rotating single and binary M-dwarf systems. X-ray luminosities for the majority of both single & binary M-dwarf systems with periods below $\simeq 5-6$ days (equatorial velocities, V$_{eq}>$ 6 km~s$^{-1}$) are consistent with the current rotation-activity paradigm, and appear to saturate

E. Costantini, F. Nicastro, A. Fruscione, S. Mathur

In this paper we present the analysis of two broad band (0.1-150 keV) BeppoSAX observations of the Seyfert 1 galaxy NGC 3516. The two observations were taken 4 months apart, on 1996 November 8 and 1997 March 12 respectively. We report a dramatic change in the degree of obscuration of the central source between the two observations, and propose, as possible e

I. Baraffe, G. Chabrier, F. Allard, P. Hauschildt

We present evolutionary models for low mass stars and brown dwarfs ($m \le 1.2 \msol$) based on recent improvement of the theory: equation of state, atmosphere models, ... We concentrate on early evolutionary phases from the initial deuterium burning phase to the zero-age Main Sequence. Evolutionary models for young brown dwarfs are also presented. We discus

Michele Pestalozzi

In this work the most spectacular phenomena occurring during the formation of a star are briefly reviewed: accretion through a rotating disc of matter and outflow through the poles of the new stellar object. Magnetic fields have been proposed to be principally responsible for the coexistence of these opposed mechanisms of accretion and outflowing. According

S. Basilakos, M. Plionis, M. Rowan-Robinson

We study the possibility of correctly identifying superclusters, from the smooth galaxy density field of the PSCz redshift catalogue, and of recovering their true shapes in the presence of a bias introduced by the coupling between the selection function and the constant radius smoothing. Using simulations we quantify such systematic biases in the smoothed PS

J. F. Le Borgne, L. Campusano, R. Pello, J. P. Kneib

We present the first results on the VLT/FORS-1 spectroscopic survey of amplified sources and multiple images in the lensing cluster AC114. Background sources were selected in the cluster core, close to the critical lines, using photometric redshifts combined with lensing inversion criteria. Spectroscopic results are given, together with a brief summary of th

G. Golse, J. -P. Kneib, G. Soucail

The knowledge of the redshift of multiple images in cluster-lenses allows to determine precisely the total projected mass within the Einstein radius. The observation of various multiple images in a same cluster is opening new possibilities to constrain the curvature of the universe. Indeed, although the influence of $Ω_m$ and $Ω_λ$ on the images formation is

C. Angelantonj, I. Antoniadis, E. Dudas, A. Sagnotti

In the presence of internal magnetic fields, a D9 brane can acquire a D5 (or anti-D5) R-R charge, and can therefore contribute to the corresponding tadpole. In the resulting vacua, supersymmetry is generically broken and tachyonic instabilities are present. However, suitable choices for the magnetic fields, corresponding to self-dual configurations in the in

Soo-Jong Rey, Rikard von Unge

We examine several aspects of S-duality of four-dimensional noncommutative gauge theory. By making duality transformation explicit, we find that S-dual of noncommutative gauge theory is defined in terms of dual noncommutative deformation. In `magnetic' noncommutative U(1) gauge theory, we show that, in addition to gauge bosons, open D-strings constitute

Irene D'Amico, Giovanni Vignale

We examine the effect of the Coulomb interaction on the mobility and diffusion of spin packets in doped semiconductors. We find that the diffusion constant is reduced, relative to its non-interacting value, by the combined effect of Coulomb-enhanced spin susceptibility and spin Coulomb drag. In ferromagnetic semiconductors, the spin diffusion constant vanish

William T. Reach, Jeonghee Rho

We present Infrared Space Observatory spectroscopy of sites in the supernova remnants W28, W44, and 3C391, where blast waves are impacting molecular clouds. Atomic fine-structure lines were detected from C, N, O, Si, P, and Fe. The S(3) and S(9) lines of H2 were detected for all three remnants. The observations require both shocks into gas with moderate (~ 1

G. A. Blair, W. Porod, P. M. Zerwas

We have studied the reconstruction of supersymmetric theories at high scales by evolving the fundamental parameters from the electroweak scale upwards. Universal minimal supergravity and gauge mediated supersymmetry breaking have been taken as representative alternatives. Pseudo-fixed point structures require the low-energy boundary values to be measured wit

O. Dumbrajs, J. Kontros, A. Lengyel

The maximum entropy method has been applied to investigate the oscillating structure in the pbarp- and pp-elastic scattering differential cross-section at high energy and small momentum transfer. Oscillations satisfying quite realistic reliability criteria have been found.

Frederic Zamora

We study the SO(3)-invariant relevant deformations of N=4 SU(N) gauge theory using the methods of Polchinski and Strassler. We present the region of parameter space where the non-supersymmetric vacuum is still described by stable ``dielectric'' five branes within the supergravity approximation.

R. E. Blanco, C. Gobel, R. Mendez-Galain

A new and simple procedure to measure the angle $γ$ from $B^{\pm} \to π^{\pm}π^+π^-$ and $B^{\pm} \to K^{\pm}π^+π^-$ decays using SU(3) symmetry is presented. It is based on a full Dalitz plot analysis of these decays. All diagrams, including strong and electroweak penguins, are considered in the procedure. The method is also free from final state interactio

Matthias Klein, Raul Rabadan

We construct compact type IIB orientifolds with discrete groups Z_4, Z_6, Z_6', Z_8, Z_12 and Z_12'. These models are N=1 supersymmetric in D=4 and have vector structure. The possibility of having vector structure in Z_N orientifolds with even N arises due to an alternative Omega-projection in the twisted sectors. Some of the models without vector st

Yeong-Ah Soh, G. Aeppli, Frank M. Zimmermann, E. D. Isaacs

We demonstrate that X-ray irradiation can be used to induce an insulator-metal transition in Si-doped Al$_{0.35}$Ga$_{0.65}$As, a semiconductor with {\it DX} centers. The excitation mechanism of the {\it DX} centers into their shallow donor state was revealed by studying the photoconductance along with fluorescence. The photoconductance as a function of inci

S. Shankaranarayanan, K. Srinivasan, T. Padmanabhan

We apply the technique of complex paths to obtain Hawking radiation in different coordinate representations of the Schwarzschild space-time. The coordinate representations we consider do not possess a singularity at the horizon unlike the standard Schwarzschild coordinate. However, the event horizon manifests itself as a singularity in the expression for the

P. Bialas, Z. Burda, B. Petersson, J. Tabaczek

Using the dynamical triangulation approach we perform a numerical study of a supersymmetric random surface model that corresponds to the large N limit of the four-dimensional version of the IKKT matrix model. We show that the addition of fermionic degrees of freedom suppresses the spiky world-sheet configurations that are responsible for the pathological beh

L. A. Pando Zayas, A. A. Tseytlin

We consider a 2-d conformal theory based on (G x G')/ H coset sigma model introduced by Guadagnini, Martellini and Mintchev. It is shown that in the case of {SU(2) x SU(2)}/ U(1) the metric of the corresponding background is of T^{p,q} coset space form (but is not an Einstein one). Similar interpretation is possible for the Lorentzian coset space W_{4,2}

Steve K. Lamoreaux

In a recent paper (M. Bostrom and Bo E. Sernelius, Phys. Rev. Lett. 84, 4757 (2000)) the combined effect of finite conductivity and finite temperature on the Casimir force is analyzed, and significant deviations from other theoretical results and a recent experiment are obtained. In this Comment, I show that the extrapolation to zero frequency is incorrect b

T. Dietl, H. Ohno, F. Matsukura

A mean field model of ferromagnetism mediated by delocalized or weakly localized holes in zinc-blende and wurzite diluted magnetic semiconductors is presented. The model takes into account: (i) strong spin-orbit and kp couplings in the valence band; (ii) the effect of strain upon the hole density-of-states, and (iii) the influence of disorder and carrier-car

P. F. L. Maxted, T. R. Marsh, C. K. J. Moran

We present 594 radial velocity measurements for 71 white dwarfs obtained during our search for binary white dwarfs and not reported elsewhere. We identify three excellent candidate binaries, which require further observations to confirm our preliminary estimates for their orbital periods, and one other good candidate. We investigate whether our data support

Sijie Gao, Robert M. Wald

Two theorems related to gravitational time delay are proven. Both theorems apply to spacetimes satisfying the null energy condition and the null generic condition. The first theorem states that if the spacetime is null geodesically complete, then given any compact set $K$, there exists another compact set $K'$ such that for any $p,q \not\in K'$, if t

Roberto Casalbuoni

In this talk I discuss the relevance of atomic physics in understanding some important questions about elementary particle physics. A particular attention is devoted to atomic parity violation measurements which seem to suggest new physics beyond the Standard Model. Atomic physics might also be relevant in discovering possible violations of the CPT symmetry.

T. Boeker

We summarize the results of a monitoring program which was executed following the cryogen exhaustion of the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) onboard the Hubble Space Telescope. During the subsequent warm-up, detector parameters such as detective quantum efficiency, dark current, bias offsets, and saturation levels have been measure

Matthias Vojta, Ying Zhang, Subir Sachdev

Motivated by the strong, low temperature damping of nodal quasiparticles observed in some cuprate superconductors, we study quantum phase transitions in d_{x^2-y^2} superconductors with a spin-singlet, zero momentum, fermion bilinear order parameter. We present a complete, group-theoretic classification of such transitions into 7 distinct cases (including ca

Antonio Dobado, Antonio L. Maroto

We study, within the recently proposed brane-world scenario, the effective action for the low-energy brane excitations. These modes are understood as Goldstone bosons associated to the spontaneous isometry breaking, induced on the bulk space by the presence of the brane. Starting from the Nambu-Goto action for the brane, we obtain a non-linear sigma model de

Yu. P. Peresun'ko

In the Kaluza - Klein approach the (4+d)-dimensional Einstein--Hilbert gravity action is considered. The extra d-dimensional manifold V_d is a Riemann space with the d-parametric group of isometry $G_d$ which acts on V_d by the left shifts and with arbitrary nondegenerated left-invariant metric g_{ab}. The gauge fields A_μ are introduced as the affine connec

P. Naselsky, D. Novikov, Joseph Silk

We propose a novel method for the extraction of unresolved point sources from CMB maps. This method is based on the analysis of the phase distribution of the Fourier components for the observed signal and unlike most other methods of denoising does not require any significant assumptions about the expected CMB signal. The aim of our paper is to show how, usi

P. Post, K. Schilcher

This paper describes the calculation of the electromagnetic form factor of the K0 meson at order p^6 of chiral perturbation theory which is the next-to-leading order correction to the well-known p^4 result achieved by Gasser and Leutwyler. On the one hand, at order p^6 the chiral expansion contains 1- and 2-loop diagrams which are discussed in detail. Especi

Kazuo Fujikawa

We discuss some formal aspects of quantum anomalies with an emphasis on the regularization of field theory. We briefly review how ambiguities in perturbation theory have been resolved by various regularization schemes. To single out the true quantum anomaly among ambiguities, the combined ideas of PCAC, soft pion limit and renormalizability were essential. A

F. Karsch, M. G. Mustafa, M. H. Thoma

We calculate temporal correlators and their spectral functions with meson quantum numbers in the deconfined phase of QCD using the hard thermal loop (HTL) approximation for the quark propagator. Although this approach does not result in a complete next-to-leading order perturbative calculation it takes into account important medium effects such as thermal qu

Santo Fortunato, Helmut Satz

The deconfinement transition in SU(2) gauge theory and the magnetization transition in the Ising model belong to the same universality class. The critical behaviour of the Ising model can be characterized either as spontaneous breaking of the $Z_2$ symmetry of spin states or as percolation of appropriately defined spin clusters. We show that deconfinement in

Marcel Griesemer, Elliott H. Lieb, Michael Loss

The excited states of a charged particle interacting with the quantized electromagnetic field and an external potential all decay, but such a particle should have a true ground state--one that minimizes the energy and satisfies the Schrödinger equation. We prove quite generally that this state exists for {\it all values} of the fine-structure constant and ul

Eric Burt, Chris Ekstrom, Tom Swanson

Recently a protocol for Quantum Clock Synchronization (QCS) of remote clocks using quantum entanglement was proposed by Jozsa et al. This method has the goal of eliminating the random noise present in classical synchronization techniques. However, as stated QCS depends on the two members of each entangled pair undergoing the same unitary evolution even while

Hitoshi Kitada

Three dimensional time and energy operators are introduced and an uncertainty relation between them is proved.

Volodymyr Krasnoholovets, Valery Byckov

Previously, one of the authors has suggested [Phys. Essays, vol. 6, 554 (1993); vol. 10, 407 (1997)] a mechanism of the particle motion within the framework of a vacuum regarded as an original cellular medium, i.e. quantum aether. The existence of special elementary excitations of the aether medium -- inertons -- around the particle has been the main peculia

J. C. Flores, S. Montecinos

Chapman's model for ozone concentration is studied. In this nonlinear model, the photodissociation coefficients for $O_{2}$ and $O_{3}$ are time-depending due to earth-rotation. From the Kapitsa's method, valid in the high frequency limit, we find the criterion for the existence of equilibrium solutions. These solutions are depending on the frequency

Tomislav Ivezic

Some of the well-known experiments: the ''muon'' experiment, the Michelson-Morley type experiments, the Kennedy-Thorndike type experiments and the Ives-Stilwell type experiments are analyzed using the nonrelativistic theory, the ''apparent transformations (AT) relativity'' and the ''true transformations (TT) relativity

Tomislav Ivezic

It is shown in this paper that the difference between the two forms of relativity - the ''true transformation (TT) relativity'' and - the ''apparent transformation (AT) relativity'' is essentially caused by the difference in the concept of \emph{sameness} of a physical system, i.e., of a physical quantity, for different, relat

P. Corredoura, S. Allison, W. Ross, R. Sass

The PEP-II B Factory Low-Level RF System (LLRF) is a fully programmable VXI based design running under an EPICS control environment. Several RF feedback loops are used to control longitudinal coupled-bunch modes driven by the accelerating mode of the RF cavities. This paper updates the performance of the LLRF system as beam currents reach design levels. Modi

P. Corredoura, C. Adolphsen

The proposed Next Linear Collider (NLC) contains linac systems operating at L,S,C, and X band. This paper describes a wideband modular low-level RF (LLRF) system applicable for all NLC pulsed RF systems. High speed digital IF techniques are used for both arbitrary klystron drive modulation and accurate RF vector detection. Measurement of relative beam to RF

A. Rivero

It is suggested that generations are linked to the need of calculating curvature of space via a deformed or discrete calculus. Quantization would limit the deformation, building three generations, and not four, as other interpretation could imply.

T. Barnes, N. Black, E. S. Swanson

We apply a quark interchange model to spin-dependent and exotic meson-meson scattering. The model includes the complete set of standard quark model forces, including OGE spin-orbit and tensor and scalar confinement spin-orbit. Scattering amplitudes derived assuming SHO and Coulomb plus linear plus hyperfine meson wavefunctions are compared. In I=2 pi pi we f

E. Garrido, E. Moya de Guerra

We investigate inclusive electron scattering reactions on two-neutron halo nuclei in the quasielastic region. Expressions for the cross section and structure functions are given assuming that the halo nucleus can be described as a three-body system (${core}+n+n$). The method is applied to $^6$He. We compute cross sections and structure functions, and investi

Martin J. Savage

I review recent developments in the application of effective field theory to nuclear physics. Emphasis is placed on precision two-body calculations and efforts to formulate the nuclear shell model in terms of an effective field theory.

M. Kirchbach

The Hilbert space H^3q of the three quarks with one excited quark is decomposed into Lorentz group representations. It is shown that the quantum numbers of the reported and ``missing'' resonances fall apart and populate distinct representations that differ by their parity or/and charge conjugation properties. In this way, reported and ``missing'&

E. Sauvan, F. Carstoiu, N. A. Orr, J. C. Angelique

A systematic study of high energy, one-neutron removal reactions on 23 neutron-rich, psd--shell nuclei (Z=5-9, A=12-25) has been carried out. The longitudinal momentum distributions of the core fragments and corresponding single-neutron removal cross sections are reported for reactions on a carbon target. Extended Glauber model calculations, weighted by the

G. Bellini, B. Caccianiga, M. Chen, F. A. Danevich

The unique features (super-low background and large sensitive volume) of the CTF and BOREXINO set ups are used in the CAMEO project for a high sensitivity study of 100-Mo and 116-Cd neutrinoless double beta decay. Pilot measurements with 116-Cd and Monte Carlo simulations show that the sensitivity of the CAMEO experiment (in terms of the half-life limit for

Piotr A. Zolnierczuk

We report the first observation of the doubly-radiative decay mode of pionic hydrogen (pi- p --> gamma gamma n) and and deuterium (pi- d --> gamma gamma X) using the RMC pair spectrometer at TRIUMF. The process is interesting in the context of the pi-Compton scattering and the chiPT predictions of the pion polarizability We present our preliminary values for

Tommaso Toffoli

In spite of their seemingly "obvious" virtues as a search strategy, genetic algorithms have ended up playing only a modest role as design tools in science and engineering. We review the reasons for this apparent failure, and we suggest a more relaxed view of their utility.

Donghak Choi, Nobuko Fuchikami

We study a kind of filtering, an amplitude truncation with upper and lower truncation levels x_max and x_min. This is a generalization of the simple transformation y(t)=sgn[x(t)], for which a rigorous result was obtained recently. So far numerical experiments have shown that a power law spectrum 1/f^alpha seems to be transformed again into a power law spectr

F. Moisy, H. Willaime, J. S. Andersen, P. Tabeling

We report new measurements of turbulent mixing of temperature fluctuations in a low temperature helium gas experiment, spanning a range of microscale Reynolds number, $R_λ$, from 100 to 650. The exponents $ξ_{n}$ of the temperature structure functions $<|θ(x+r)-θ(x)|^n > \sim r^{ξ_{n}}$ are shown to saturate to $ξ_{\infty} \simeq 1.45 \pm 0.1$ for the highes

P. B. Gilkey, K. Kirsten

Let $P$ be an operator of Dirac type on a compact Riemannian manifold with smooth boundary. We impose spectral boundary conditions and study the asymptotics of the heat trace of the associated operator of Laplace type.

Daniel Dugger

Given a small category C, we show that there is a universal way of expanding C into a model category, essentially by formally adjoining homotopy colimits. The technique of localization becomes a method for imposing `relations&#39; into these universal gadgets. The paper develops this formalism and discusses various applications, for instance to the study of

Winfried Bruns, Udo Vetter

Let $R$ be a noetherian ring and $M$ a finite $R$-module. With a linear form $χ$ on $M$ one associates the Koszul complex $K(χ)$. If $M$ is a free module, then the homology of $K(χ)$ is well-understood, and in particular it is grade sensitive with respect to $\Imχ$. In this note we investigate the case of a module $M$ of projective dimension 1 (more precisel

Daniel Dugger

We show that every combinatorial model category can be obtained, up to Quillen equivalence, by localizing a model category of diagrams of simplicial sets. This says that any combinatorial model category can be built up from a category of `generators&#39; and a set of `relations&#39;---that is, any combinatorial model category has a presentation.

Elisabeth Remm, Michel Goze

We give some examples of non-complete invariant affine connections on nilpotent and filiform Lie groups. This permits to describe non-nilpotent faithful representations on the model of filiform n-dimensional Lie algebras and, in particular, on the 3 dimensional Heisenberg algebra.

E. Abbena, S. Garbiero, S. Salamon

The fundamental 2-form of an invariant almost Hermitian structure on a 6-dimensional Lie group is described in terms of an action by SO(4)xU(1) on complex projective 3-space. This leads to a combinatorial description of the classes of almost Hermitian structures on the Iwasawa and other nilmanifolds.

S. M. Khoroshkin, J. Lukierski, V. N. Tolstoy

We show that the quantum affine algebra U_{q}(A_{1}^{(1)}) and the quantum affine superalgebra U_{q}(C(2)^{(2)}) admit unified description. The difference between them consists in the phase factor which is equal to 1 for U_{q}(A_{1}^{(1)}) and is equal to -1 for U_{q}(C(2)^{(2)}). We present such a description for the construction of Cartan-Weyl generators a

Jeff Johannes

Formulas previously presented for the Casson-Walker invariant are generalized to Lescop&#39;s extension. These formulas in terms of linking numbers and surgery coefficients compute the change in Lescop&#39;s invariant under crossing changes in a framed link presenting a 3-manifold. This leads us to revisit an old formula for a coefficient of the Conway polyn

Kingsley Fregene, Diane Kennedy

This paper discusses the systematic design of an adaptive feedback linearizing neurocontroller for a high-order model of the synchronous machine/infinite bus power system. The power system is first modelled as an input-output nonlinear discrete-time system approximated by two neural networks. The approach allows a simple linear pole-placement controller (whi

Ralf Schindler

We indicate that an argument of da Costa and Doria in fact proves P=NP. This observation makes their argument appear dubious. We isolate a weak version of one of their lemmas which would already prove P=NP. We point out that even this weak version is probably false. In fact, a generalized form of this weak version is provably false.

Frederic Chapoton

We define an equivalence of categories, quite similar to the classical Cartier-Milnor-Moore-Quillen theorem, between the category of connected dendriform bialgebras and the category of brace algebras. This equivalence is given by the functors &#34;subspace of primitive elements&#34; and &#34;universal enveloping dendriform algebra&#34;.

Terence Tao

In a recent paper of Wolff the optimal decay of circular L^p means of compactly supported measures of finite energy was given for p>=2, with application to Falconer&#39;s distance problem. The question was then raised in that paper as to whether any non-trivial improvement to these estimates were available for p < 2. We answer this question in the negative.

Semyon Pol&#39;shin

A system of generalized coherent states for the de Sitter group obeying the Klein-Gordon equation and corresponding to the massive spin zero particles over the de Sitter space is considered. This allows us to construct the quantized scalar field by the resolution over these coherent states; the corresponding propagator is computed by the method of analytic c

P. Mathieu, J. Rasmussen, M. A. Walton

Fusion rules for Wess-Zumino-Witten (WZW) models at fractional level can be defined in two ways, with distinct results. The Verlinde formula yields fusion coefficients that can be negative. These signs cancel in coset fusion rules, however. On the other hand, the fusion coefficients calculated from decoupling of singular vectors are non-negative. They produc

George Papadopoulos, David Tong

It is shown that the supergravity moduli spaces of D1-D5 and D2-D6 brane systems coincide with those of the Coulomb branches of the associated non-abelian gauge theories. We further discuss situations in which worldvolume brane actions include a potential term generated by probing certain supergravity backgrounds. We find that in many cases, the appearance o

Keiichi Akama

We show how the gravity, gauge, and matter fields are induced on dynamically localized brane world (domain wall, vortex etc.). Solitonic solutions localized on a curved brane in certain field theories in higher dimensions are given in terms of gravity, gauge and extrinsic curvature fields of the brane. Then we deduce the effective field theory on the brane i

J. M. Gracia-Bondia, S. Lazzarini

Causal perturbative renormalization within the recursive Epstein-Glaser scheme involves extending, at each order, time-ordered operator-valued distributions to coinciding points. This is achieved by a generalized Taylor subtraction on test functions, which is transposed to distributions. We show how the Epstein-Glaser recursive construction can, by means of

Alex Krasnitz, Raju Venugopalan

The initial gluon multiplicity per unit area per unit rapidity, dN/L^2/dη, in high energy nuclear collisions, is equal to f_N (g^2μL) (g^2μ)^2/g^2, with μ^2 proportional to the gluon density per unit area of the colliding nuclei. For an SU(2) gauge theory, we compute f_N (g^2μL)=0.14\pm 0.01 for a wide range in g^2μL. Extrapolating to SU(3), we predict dN/L^

Alexander A. Osipov, Brigitte Hiller

We present a derivation of the low-energy effective meson Lagrangian of the extended Nambu -- Jona-Lasinio (ENJL) model. The case with linear realization of broken $SU(2)\times SU(2)$ chiral symmetry is considered. There are two crucial points why this revision is needed. Firstly it is the explicit chiral symmetry breaking effect. On the basis of symmetry ar

R. Kaiser, H. Leutwyler

The construction of the effective Lagrangian relevant for the mesonic sector of QCD in the large N_c limit meets with a few rather subtle problems. We thoroughly examine these and show that, if the variables of the effective theory are chosen suitably, the known large N_c counting rules of QCD can unambiguously be translated into corresponding counting rules

A. D. Martin, R. G. Roberts, W. J. Stirling, R. S. Thorne

We use the recent estimates of NNLO splitting functions, made by van Neerven and Vogt, to perform exploratory fits to deep inelastic and related hard scattering data. We investigate the hierarchy of parton distributions obtained at LO, NLO and NNLO, and, more important, the stability of the resulting predictions for physical observables. We use the longitudi

O. Bohr, B. -J. Schaefer, J. Wambach

We derive and solve flow equations for a general O(N)-symmetric effective potential including wavefunction renormalization corrections combined with a heat-kernel regularization. We investigate the model at finite temperature and study the nature of the phase transition in detail. Beta functions, fixed points and critical exponents β, ν, δand ηfor various N

R. Casalbuoni, S. De Curtis, M. Redi

We discuss the possible signals of the degenerate BESS model at the LHC. This model describes a strongly interacting scenario responsible of the spontaneous breaking of the electroweak symmetry. It predicts two triplets of extra gauge bosons which are almost degenerate in mass. Due to this feature, the model has the property of decoupling and therefore, at l

M. Ciafaloni, P. Ciafaloni, D. Comelli

High energy observables are characterized by large electroweak radiative corrections of infrared origin; double logarithms are present even for inclusive cross sections, thus violating the Bloch Nordsieck theorem. This effect, related to the initial states carrying nonabelian isospin charges, is here investigated for {\sl any} inclusive cross section in the

D J Miller

Studies of the physics potential of the Future Linear Collider are establishing a broad programme which will start in the region of 350 to 500 GeV C. of M. energy. The main goal is to understand why the standard model works; by studying the properties of the Higgs sector, if it is within reach, and by exploring the complex world of Supersymmetry, if it is re

Ulf-G. Meißner

I review the consequences of the chiral symmetry of QCD for the structure and dynamics of the low-lying baryons, with particular emphasis on the nucleon.

E. Arik, A. Mailov, S. Sultansoy

We present a calculation for a new limit on nu_(e)->nu_(tau) oscillations based on the recent data from CHORUS experiment

E. Mauceli, M. P. McHugh, W. O. Hamilton, W. W. Johnson

We describe the search for a continuous signal of gravitational radiation from a rotating neutron star in the data taken by the ALLEGRO gravitational wave detector in early 1994. Since ALLEGRO is sensitive at frequencies near 1 kHz, only neutron stars with spin periods near 2 ms are potential sources. There are no known sources of this typ e for ALLEGRO, so

J. Alberto Lobo

A spherical gravity wave (GW) detector, unlike interferometers and bars, is a natural multi-mode device, i.e., it is capable of independently gathering information on all five quadrupole and one monopole amplitudes of a general incoming GW. This is because the sphere&#39;s degenerate oscillation eigenmodes are uniquely matched to the structure of the GWs&#39

Mathieu Stricker, Frantz Vichot, Gerard Dreyfus, Francis Wolinski

For the TREC-8 routing, one specific filter is built for each topic. Each filter is a classifier trained to recognize the documents that are relevant to the topic. When presented with a document, each classifier estimates the probability for the document to be relevant to the topic for which it has been trained. Since the procedure for building a filter is t

G. B. Martins, J. C. Xavier, C. Gazza, M. Vojta

The recently discussed tendency of holes to generate nontrivial spin environments in the extended two-dimensional t-J model (G. Martins, R. Eder, and E. Dagotto, Phys. Rev. B{\bf 60}, R3716 (1999)) is here investigated using computational techniques applied to ladders with several number of legs. This tendency is studied also with the help of analytic spin-p

Kyungwha Park, David A. Huse

In classical XY kagome antiferromagnets, there can be a novel low temperature phase where $ψ^3=e^{i3θ}$ has quasi-long-range order but $ψ$ is disordered, as well as more conventional antiferromagnetic phases where $ψ$ is ordered in various possible patterns ($θ$ is the angle of orientation of the spin). To investigate when these phases exist in a physical sy

R. Mathieu, P. Svedlindh, R. A. Chakalov, Z. G. Ivanov

The low field magnetotransport of La$_{0.7}$Sr$_{0.3}$MnO$_3$ (LSMO) films grown on SrTiO$_3$ substrates has been investigated. A high qualtity LSMO film exhibits anisotropic magnetoresistance (AMR) and a peak in the magnetoresistance close to the Curie temperature of LSMO. Bi-epitaxial films prepared using a seed layer of MgO and a buffer layer of CeO$_2$ d

S. Trebst, H. Monien, C. J. Hamer, Z. Weihong

We present a new linked cluster expansion for calculating properties of multiparticle excitation spectra to high orders. We use it to obtain the two-particle spectra for systems of coupled spin-half dimers. We find that even for weakly coupled dimers the spectrum is very rich, consisting of many bound states. The number of bound states depends on both geomet

R. Combescot

We consider the existence of a BCS superfluid phase in $^{6}$Li due to the pairing of two hyperfine states with unequal number of atoms. We show that the domain of existence for this phase will be increased to a very large extent in the vicinity of the threshold for collapse. This is due to the presence of a new phase with anisotropic order parameter. This p

O. V. Danylenko, O. V. Dolgov

We investigate effects of a nonadiabatic electron-phonon(boson) interaction on the quasiparticle self-energy in the lowest order in the coupling constant. Existing approaches either overestimate, or underestimate these effects because of different approximations for momentum and frequency dependences of the vertex corrections. The connection between the nona

Elisa Ercolessi, Giuseppe Morandi, Pierbiagio Pieri, Marco Roncaglia

We present in this paper a nonlinear sigma-model analysis of a spin-1 antiferromagnetic Heisenberg chain in an external commensurate staggered magnetic field. After rediscussing briefly and extending previous results for the staggered magnetization curve, the core of the paper is a novel calculation, at the tree level, of the Green functions of the model. We

V. Garzo

Explicit expressions for the heat and momentum fluxes are given for a low-density multicomponent mixture in a steady state with temperature and velocity gradients. The results are obtained from a formally exact solution of the Gross-Krook model [Phys. Rev. {\bf 102}, 593 (1956)] of the Boltzmann equation for a multicomponent mixture. The transport coefficien

E. del Barco, J. M. Hernandez, J. Tejada, E. M. Chudnovsky

Response to the Comment by Bellessa (arXiv:cond-mat/0006441).

Philip W. Anderson

We argue that spin charge separation holds the key to the understanding of high temperature superconductivity.

M. S. Laad, L. Craco, E. Müller-Hartmann

We investigate the role of orbital degeneracy in the double exchange (DE) model. In the $J_{H}\to\infty$ limit, an effective generalized ``Hubbard&#39;&#39; model incorporating orbital pseudospin degrees of freedom is derived. The model possesses an exact solution in one- and in infinite dimensions. In 1D, the metallic phase off ``half-filling&#39;&#39; is a

M. Plihal, J. W. Gadzuk

We report on a fully nonequilibrium theory of the scanning tunneling microscopy (STM) through resonances induced by impurity atoms adsorbed on metal surfaces. The theory takes into account the effect of the tunneling current and finite bias on the system and is valid for arbitrary intra-adsorbate electron correlation strength. It is thus applicable to the re

Luis Craco, Mukul S. Laad

We study the electron-energy loss spectra of strongly correlated electronic systems doped away from half-filling using dynamical mean-field theory ($d=\infty$). The formalism can be used to study the loss spectra in the optical (${\bf q=0}$) limit, where it is simply related to the optical response, and hence can be computed in an approximation-free way in $