June 2000 arXiv papers — page 2

Jason D. Schmidt, Barbara S. Ryden, Adrian L. Melott

The sizes and shapes of voids in a galaxy survey depend not only on the physics of structure formation, but also on the sampling density of the survey and on the algorithm used to define voids. Using an N-body simulation with a CDM power spectrum, we study the properties of voids in samples with different number densities of galaxies, both in redshift space

S. M. Asida, David Arnett

Two dimensional hydrodynamical simulations of convective oxygen burning shell in the presupernova evolution of a 20 solar-mass star are extended to later times. We used the VULCAN code to simulate longer evolution times than previously possible. Our results confirm the previous work of Bazan and Arnett (98) over their time span of 400s. However, at 1200s, we

Daniel Christlein

We present luminosity functions for galaxies in loose groups in the Las Campanas Redshift Survey, differentiated by their environment (defined by the line-of-sight velocity dispersion sigma of the host groups) and also by their spectral type (emission or non-emission, defined by the equivalent width of the 3727-Angstrom [OII] line). We find systematic variat

D. Boyanovsky, H. J. de Vega

The physics during the inflationary stage of the universe is of quantum nature involving extremely high energy densities. Moreover, it is out of equilibrium on a fastly expanding dynamical geometry.We present in these lectures non-perturbative out of equilibrium field theoretical methods in cosmological universes. We then study the non-linear dynamics of qua

Toshiyuki Kanazawa, Masahiro Kawasaki, Naoshi Sugiyama, T. Yanagida

One of the biggest mystery of the recent observation of cosmic microwave background anisotropies by the boomerang team is insignificance of the second acoustic peak in the angular power spectrum. It is very difficult to explain such a low amplitude without assuming the higher baryon density than predicted by the Big Bang Nucleosynthesis (BBN). Employing the

H. Matsuhara, K. Kawara, Y. Sato, Y. Taniguchi

We investigate the characteristics of FIR brightness fluctuations at 90 micron and 170 micron in the Lockman Hole, which were surveyed with ISOPHOT aboard the Infrared Space Observatory(ISO). We first calculated the angular correlation function of each field and then its Fourier transform(the angular Power Spectral Density: PSD) over the spatial frequency ra

F. Tavecchio, L. Maraschi, G. Ghisellini, A. Celotti

We present BeppoSAX observations of three gamma-ray emitting quasars, namely 0836+710, 1510-089 and 2230+114. The three objects have been detected up to 100 keV showing extremely flat power-law spectra above 2 keV (energy index alpha_{2-10}=0.3-0.5). The soft X-ray spectrum of 0836+710 implies either an absorption column density higher than the galactic one

S. Hamdani, P. North, N. Mowlavi, D. Raboud

Chemical abundances of about fifteen elements from oxygen to europium are measured in seven red giants of the two open clusters NGC 2360 and NGC 2447. The effective temperatures of the giants are determined spectroscopically by taking advantage of their known masses (~2 Mo in NGC 2360 and ~3 Mo in NGC 2447) and bolometric magnitudes. The average iron abundan

M. Kutschera, J. Niemiec

The influence of the nuclear symmetry energy on the formation of a mixed quark-nucleon phase in neutron star cores is studied. We use simple parametrizations of the nuclear matter equation of state, and the bag model for the quark phase. The behavior of nucleon matter isobars, which is responsible for the existence of the mixed phase, is investigated. The ro

S. Capozziello, G. Iovane, G. Lambiase, D. F. Torres

The nature of Galactic Center could be probed by lensing experiments capable of testing the spatial and velocity distributions of stars nearby and beyond it. Several hypotheses are possible (e.g. massive neutrino condensation, boson star) which avoid the shortcomings of the supermassive black hole model.

Mirek Giersz

A revision of Stodółkiewicz's Monte Carlo code is used to simulate evolution of large star clusters. The survey on the evolution of multi-mass N-body systems influenced by the tidal field of a parent galaxy and by stellar evolution is discussed. For the first time, the simulation on the "star-by-star" bases of evolution of 1,000,000 body star clu

J. -P. Macquart, D. B. Melrose

A new theory is presented for the development of circular polarization as radio waves propagate through the turbulent, birefringent interstellar medium. The fourth order moments of the wavefield are calculated and it is shown that unpolarized incident radiation develops a nonzero variance in circular polarization. A magnetized turbulent medium causes the Sto

Andreas S. Kronfeld, James N. Simone

We pursue a new method, based on lattice QCD, for determining the quantities $\barΛ$, $λ_1$, and $λ_2$ of heavy-quark effective theory. We combine Monte Carlo data for the meson mass spectrum with perturbative calculations of the short-distance behavior, to extract $\barΛ$ and $λ_1$ from a formula from HQET. Taking into account uncertainties from fitting the

D. A. Demir

Given a bulk scalar field with sufficient self-interactions in a higher dimensional spacetime, it is shown that the continuous symmetries in four dimensions, induced by the topological structure of the compact manifold, naturally lead to formation of stable nontopological solitons of Q-ball type. The mass per unit charge inside the soliton is bounded by the

Teruhiko Kawano, Seiji Terashima

We study the compactification of OM-theory on tori and show a simple heuristic derivation of the $S$-duals of noncommutative open string theory in diverse dimensions from the OM-theoretical point of view. In particular, we identify the $S$-duality between noncommutative open string theory and noncommutative Yang-Mills theory in $(3+1)$ dimensions as the exch

Per Osland, Geir Vigdel

The Lehmann-Newton-Wu mass matrix, which was recently applied to neutrinos, is further investigated. The analytic results presented earlier are confirmed numerically for the solar density profile of the Standard Solar Model. The combined analysis of atmospheric and solar neutrino data favors the MSW solution over the vacuum-oscillation solution. The total ra

F. Berruto, R. Narayanan, H. Neuberger

We introduce a simple method to find localized exact fermionic zero modes for any local fermionic action. The zero modes are attached to specific local gauge configurations. Examples are provided for staggered and Wilson fermion actions in 2-6 dimensions, at finite and infinite lattice volumes, and for abelian and non-abelian gauge groups. One of our concret

V. M. Krasnov, A. E. Kovalev, A. Yurgens, D. Winkler

Intrinsic tunneling spectroscopy in high magnetic field ($H$) is used for a direct test of superconducting features in a quasiparticle density of states of high-$T_c$ superconductors. We were able to distinguish with a great clarity two co-existing gaps: (i) the superconducting gap, which closes as $H \to H_{c2}(T)$ and $T\to T_c(H)$, and (ii) the $c$-axis p

Charles A. Nelson, L. J. Adler,

Tests of the Lorentz structure of t --> W b decay will be carried out at the Tevatron, and later at the LHC and at a NLC. To quantitatively assay future measurements of competing observables, we consider the (V-A) coupling values of the helicity decay parameters versus "(V-A) + Single Additional Lorentz Structures". Three phase-type ambiguities exist

Joaquim Gomis, Kiyoshi Kamimura, Josep Llosa

Space-time non-commutative theories are non-local in time. We develop the Hamiltonian formalism for non-local field theories in d space-time dimensions by considering auxiliary d+1 dimensional field theories which are local with respect to the evolution time. The Hamiltonian path integral quantization is considered and the Feynman rules in the Lagrangian for

Ofer Aharony, Jaume Gomis, Thomas Mehen

We show that field theories with light-like noncommutativity, that is with $θ^{0i}=-θ^{1i}$, are unitary quantum theories, and that they can be obtained as decoupled field theory limits of string theory with D-branes in a background NS-NS $B$ field. For general noncommutativity parameters, we show that noncommutative field theories which are unitary can be o

Alejandro Perez, Carlo Rovelli

We present a spin foam model in which the fundamental ``bubble amplitudes'' (the analog of the one-loop corrections in quantum field theory) are finite as the cutoff is removed. The model is a natural variant of the field theoretical formulation of the Barrett-Crane model. As the last, the model is a quantum BF theory plus an implementation of the co

Martin Fliesser, Jürgen Reidl, Péter Szépfalusy, Robert Graham

The dielectric formalism is used to set up an approximate description of a spatially homogeneous weakly interacting Bose gas in the collision-less regime, which is both conserving and gap-less, and has coinciding poles of the single-particle Green's function and the density autocorrelation function in the Bose-condensed regime. The approximation takes in

The KLOE collaboration

The KLOE detector at DAFNE, the Frascati Phi-factory, has collected about 8 millions phi decays in 1999. Measurements of Phi decays into pi0, eta, eta', f0(980), a0(980) and pi+pi-pi0 have been performed with statistical accuracy better than previously in a single detector, as well as new decay modes. Phi radiative decays can clarify the nature of f0 and

Ernest Ma, G. Rajasekaran, Utpal Sarkar

An experimentally verifiable Higgs-triplet model of neutrino masses from large extra dimensions was recently proposed. We extend it to accomodate a light sterile neutrino which also mixes with the three active neutrinos. A previously proposed phenomenological model of four neutrinos (\underline {the only viable such model now left}, in view of the latest atm

Matthias Staudacher

This note addresses the question of the number of normalizable vacuum states in supersymmetric quantum mechanics with sixteen supercharges and arbitrary semi-simple compact gauge group, up to rank three. After evaluating certain contour integrals obtained by appropriately adapting BRST deformation techniques we propose novel rational values for the bulk indi

Y. Jack Ng

We show that quantum mechanics and general relativity limit the speed $\tildeν$ of a simple computer (such as a black hole) and its memory space $I$ to $\tildeν^2 I^{-1} \lsim t_P^{-2}$, where $t_P$ is the Planck time. We also show that the life-time of a simple clock and its precision are similarly limited. These bounds and the holographic bound originate f

L. Pozzetti, F. Mannucci

The extremely red galaxies (ERGs) are defined in terms of their very red optical-to-near IR colours (as R-K>5 or I-K>4). Originally this selection was aimed at selecting old (> 1 Gyr) passively evolving elliptical galaxies at intermediate redshift (1<z<2), but it was soon discovered that young star-forming dusty galaxies can show similar colours and therefor

Alex Bunker, Burkhard Duenweg

We have developed a technique to accelerate the acquisition of effectively uncorrelated configurations for off-lattice models of dense polymer melts which makes use of both parallel tempering and large scale Monte Carlo moves. The method is based upon simulating a set of systems in parallel, each of which has a slightly different repulsive core potential, su

M. Bauer, O. Golinelli

We present an exact analysis of two conductor-insulator transitions in the random graph model. The average connectivity is related to the concentration of impurities. The adjacency matrix of a large random graph is used as a hopping Hamiltonian. Its spectrum has a delta peak at zero energy. Our analysis is based on an explicit expression for the height of th

Kari Enqvist, Hannu Kurki-Suonio, Jussi Valiviita

We present the constraints on isocurvature fluctuations for a flat universe implied by the Boomerang and Maxima-1 data on the anisotropy of the cosmic microwave background. Because the new data defines the shape of the angular power spectrum in the region of the first acoustic peaks much more clearly than earlier data, even a tilted pure isocurvature model i

Shin&#39;ichi Nojiri, Sergei D. Odintsov

The general model of higher derivative (HD) gravity is considered. The search of brane-world cosmology in such theory is presented when bulk is d5 AdS and boundary is spherical, hyperbolic or flat (single) brane. It is found the wide range of theory parameters where such cosmology may be realized. Special attention is paid to the version of HD theory represe

Mans Henningson

We describe a class of six-dimensional conformal field theories that have some properties in common with and possibly are related to a subsector of the tensionless string theories. The latter theories can for example give rise to four-dimensional $N = 4$ superconformal Yang-Mills theories upon compactification on a two-torus. Just like the tensionless string

D. B. Gutman, Yuval Gefen

We employ a non-linear sigma model defined on a Keldysh contour to study the current and the current noise in a diffusive micro-bridge in the presence of electron-electron interactions. Out of equilibrium the fluctuation-dissipation theorem (FDT) does not apply, hence these two quantities are not simply interrelated. For a two-dimensional electron gas (2DEG)

Axel Krause

We explore a mechanism to obtain the observational small value for the 4-dimensional vacuum energy through an exponential warp-factor suppression. Intriguingly the required suppression scale relates directly to the GUT scale. We demonstrate the mechanism explicitly in a 5-dimensional brane-world setup with warped geometry. Upon lifting the setup to 10-dimens

L. M. Sehgal, J. van Leusen

We consider the decay K^0 (K^0 bar) -> pi^+ pi^- e^+ e^- of a neutral K meson prepared in a state of strangeness +1 (-1). The time evolution of the state produces remarkable time-dependent effects in the angular distribution of the pi^+ pi^- e^+ e^- system. These effects are correlated with the time-dependence of the photon polarization in the radiative deca

Edmund J Copeland, Andrew R Liddle, James E Lidsey

We propose a scenario for inflation based upon the braneworld picture, in which high-energy corrections to the Friedmann equation permit inflation to take place with potentials ordinarily too steep to sustain it. Inflation ends when the braneworld corrections begin to lose their dominance. Reheating may naturally be brought about via gravitational particle p

Pierre Duclos, Pavel Exner, Bernhard Meller

We discuss the Noeckel model of an open quantum dot, i.e., a straight hard-wall channel with a potential well. If this potential depends on the longitudinal variable only, there are embedded eigenvalues which turn into resonances if the symmetry is violated, either by applying a magnetic field or by deformation of the well. For a weak symmetry breaking we de

Jose Riera, Didier Poilblanc

Charge, spin, as well as lattice instabilities are investigated in isolated or weakly coupled chains of correlated electrons at quarter-filling. Our analysis is based on extended Hubbard models including nearest neighbor repulsion and Peierls coupling to lattice degrees of freedom. While treating the electronic quantum fluctuations exactly, the lattice struc

C. H. Lam, V. K. Horváth

We present a numerical study on the dynamics of imbibition fronts in porous media using a pipe network model. This model quantitatively reproduces the anomalous scaling behavior found in imbibition experiments [Phys. Rev. E {\bf 52}, 5166 (1995)]. Using simple scaling arguments, we derive a new identity among the scaling exponents in agreement with the exper

I. J. R. Aitchison, G. V. Dunne

We show that while the zero temperature induced fermion number in a chiral sigma model background depends only on the asymptotic values of the chiral field, at finite temperature the induced fermion number depends also on the detailed shape of the chiral background. We resum the leading low temperature terms to all orders in the derivative expansion, produci

I. V. Vancea

We derive the finite temperature description of bosonic D-branes in the thermo field approach. The results might be relevant to the study of thermical properties of D-brane systems.

B. Feigin, S. Loktev

In this paper we prove the identity that generalizes the Andrews-Gordon identity. Also we discuss the relation of our formula to the geometry of affine flag varieties and to the geometry of polyhedra.

Soon-Tae Hong, Young-Jai Park, Kuniharu Kubodera, Fred Myhrer

The Batalin-Fradkin-Tyutin (BFT) scheme, which is an improved version of Dirac quantization, is applied to the $CP^1$ model, and the compact form of a nontrivial first-class Hamiltonian is directly obtained by introducing the BFT physical fields. We also derive a BRST-invariant gauge fixed Lagrangian through the standard path-integral procedure. Furthermore,

Lucien Hardy, David D. Song

We consider entanglement swapping schemes with general (rather than maximally) entangled bipartite states of arbitary dimension shared pairwise between three or more parties in a chain. The intermediate parties perform generalised Bell measurements with the result that the two end parties end up sharing a entangled state which can be converted into maximally

R. -M. Vetter, A. Haibel, G. Nimtz

If a quantum mechanical particle is scattered by a potential well, the wave function of the particle can propagate with negative phase time. Due to the analogy of the Schrödinger and the Helmholtz equation this phenomenon is expected to be observable for electromagnetic wave propagation. Experimental data of electromagnetic wells realized by wave guides fill

T. Tyc

I show that there exists a class of inequalities between correlation functions of different orders of a chaotic electron field. These inequalities lead to the antibunching effect and are a consequence of the fact that electrons are fermions -- indistinguishable particles with antisymmetric states. The derivation of the inequalities is based on the known form

A. K. Rajagopal, R. W. Rendell

A general two qubit system expressed in terms of the complete set of unit and fifteen traceless, Hermitian Dirac matrices, is shown to exhibit novel features of this system. The well-known physical interpretations associated with the relativistic Dirac equation involving the symmetry operations of time-reversal T, charge conjugation C, parity P, and their pr

K. Audenaert, F. Verstraete, B. De Moor

In this paper we develop a mathematical framework for the characterisation of separability and entanglement of formation (EoF) of general bipartite states. These characterisations are of the variational kind, meaning that separability and EoF are given in terms of a function which is to be minimized over the manifold of unitary matrices. A major benefit of s

Arul Lakshminarayan

We use the Barnett-Pegg formalism of angle operators to study a rotating particle with and without a flux line. Requiring a finite dimensional version of the Wigner function to be well defined we find a natural time quantization that leads to classical maps from which the arithmetical basis of quantum revivals is seen. The flux line, that fundamentally alter

Matt Mackie, Juha Javanainen

We discuss the role of Bose enhancement of the dipole matrix element in photoassociation, using stimulated Raman adiabatic passage as an example. In a nondegenerate gas the time scale for coherent optical transients tends to infinity in the thermodynamic limit, whereas Bose enhancement keeps this time scale finite in a condensate. Coherent transients are the

Y. Nosochkov, M. Biagini, Y. Cai, F. -J. Decker

The successful commissioning and operation of the PEP-II asymmetric e+e- collider motivated further studies to increase luminosity. In this paper, we discuss a modification of the PEP-II lattice to reduce the vertical beta function at the Interaction Point (IP) from the design value of 1.5cm to 1.0cm. This could potentially reduce the colliding beam size, in

A. M. Ignatov, Sh. G. Amiranashvili

A radiofrequency glow discharge plasma, which is polluted with a certain number of dusty grains, is studied. In addition to various dusty plasma phenomena, several specific colloidal effects should be considered. We focus on radiometric forces, which are caused by inhomogeneous temperature distribution. Aside from thermophoresis, the role of temperature dist

Kirk T. McDonald

Circular orbits of a particle sliding on a frictionless surface of revolution about a vertical axis are unstable below a critical radius if the curvature of the surface satisfies a specified condition. This behavior can be realized in a mechanical model, which give a glimpse of the greater complexity of particle orbits in curved rather than flat spacetime.

S. J. Lee, A. Z. Mekjian

The liquid-gas phase transition is studied in a multi-component nuclear system using a local Skyrme interaction with Coulomb and surface effects. Some features are qualitatively the same as the results of Muller and Serot which uses relativistic mean field without Coulomb and surface effects. Surface tension brings the coexistance binodal surface to lower pr

J. Tõke, W. Gawlikowicz, W. U. Schröder

The importance of a Coulomb correction to the formalism proposed by Albergo et al. for determining the temperatures of nuclear systems at break-up and the ensities of free nucleon gases is discussed. While the proposed correction has no effect on the temperatures extracted based on double isotope ratios, it becomes non-negligible when such temperatures or de

S. Scherer, H. W. Fearing

We consider a simple model and make use of field transformations in Lagrangian field theories to illustrate the impossibility of measuring off-shell effects in nucleon-nucleon bremsstrahlung and related processes.

V. Baru, A. M. Gasparian, J. Haidenbauer, A. E. Kudryavtsev

The influence of the nucleon-nucleon final state interaction (FSI) on properties of the meson production amplitude near threshold is discussed. For the nucleon-nucleon interaction a simple Yamaguchi potential as well as realistic potential models are considered. It is shown that FSI effects cannot be factorized from the production amplitude. The absolute mag

A. Fix, H. Arenhoevel

The interaction of an $η$-meson with two nucleons is studied within a three-body approach. The major features of the $ηNN$-system in the low-energy region are accounted for by using a s-wave separable ansatz for the two-body $ηN$- and $NN$-amplitudes. The calculation is confined to the $(J^π;T)=(0^-;1)$ and $(1^-;0)$ configurations which are assumed to be th

E. Schiller, H. Müther

The Dirac structure of the nucleon self-energy in symmetric nuclear matter as well as neutron matter is derived from a realistic meson exchange model for the nucleon-nucleon (NN) interaction. It is demonstrated that the effects of correlations on the effective NN interaction in the nuclear medium can be parameterized by means of an effective meson exchange.

J. J. Garcia-Ripoll, V. M. Perez-Garcia, W. Krolikowski, Y. S. Kivshar

We study the scattering properties of optical dipole-mode vector solitons recently predicted theoretically and generated in a laboratory. We demonstrate that such a radially asymmetric composite self-trapped state resembles ``a molecule of light&#39;&#39; which is extremely robust, survives a wide range of collisions, and displays new phenomena such as the t

An-Min Li, Yongbin Ruan

We define relative Gromov-Witten invariants and establish a general gluing theory of pseudo-holomorphic curves for symplectic cutting and contact surgery. Then, we use our general gluing theory to study the change of GW-invariants of Calabi-Yau 3-folds tranform under flops and extremal transitions. We prove a complete formula for the change of GW-invariants

Michael Joswig, Volker Kaibel, Marc E. Pfetsch, Guenter M. Ziegler

How much of the combinatorial structure of a pointed polyhedron is contained in its vertex-facet incidences? Not too much, in general, as we demonstrate by examples. However, one can tell from the incidence data whether the polyhedron is bounded. In the case of a polyhedron that is simple and &#34;simplicial,&#34; i.e., a d-dimensional polyhedron that has d

Stephen Parrott

This note studies Arveson&#39;s curvature invariant for d-contractions specialized to the case d=1 of a single contraction operator on a Hilbert space. It establishes a formula which gives an easy-to-understand meaning for the curvature of a single contraction. The formula is applied to give an example of an operator with nonintegral curvature. Under the add

Fumiharu Kato, Hiroyuki Ochiai

We prove that the fake projective planes constructed from the diadic discrete group discovered by Cartwright, Mantero, Steger, and Zappa are connected Shimura varieties associated to a certain unitary group. The necessary Shimura data, as well as the unitary group, are explicitly described. We also give a field of definition of these fake projective planes.

Frederic Chapoton, Muriel Livernet

A Pre-Lie algebra is a vector space L endowed with a bilinear product * : L \times L to L satisfying the relation (x*y)*z-x*(y*z)= (x*z)*y-x*(z*y), for all x,y,z in L. We give an explicit combinatorial description in terms of rooted trees of the operad associated to this type of algebras and prove that it is a Koszul operad.

P. Jacob, P. Mathieu

We study various aspects of parafermionic theories such as the precise field content, a description of a basis of states (that is, the counting of independent states in a freely generated highest-weight module) and the explicit expression of the parafermionic singular vectors in completely irreducible modules. This analysis culminates in the presentation of

C. Adam, B. Muratori, C. Nash

We demonstrate that particle production for fermions coupled chirally to an Abelian gauge field like the hypercharge field is provided by the microscopic mechanism of level crossing. For this purpose we use recent results on zero modes of Dirac operators for a class of localized hypermagnetic knots.

D. Arnaudon, R. Poghossian, A. Sedrakyan, P. Sorba

The generalization of the Yang-Baxter equations (YBE) in the presence of Z_2 grading along both chain and time directions is presented. The XXZ model with staggered disposition along a chain of both, the anisotropy \pmΔ, as well as shifts of the spectral parameters are considered and the corresponding integrable model is constructed. The Hamiltonian of the m

H. V. Klapdor-Kleingrothaus, L. Baudis, G. Heusser, B. Majorovits

To increase by a major step the present sensitivity for dark matter and double beta decay search, a new project is suggested, which would operate &#39;naked&#39; GErmanium detectors in liquid NItrogen as shielding in an Underground Setup (GENIUS). In a first step using 100 kg of natural Ge a large part of the MSSM parameter space for prediction of neutralino

Richard F. Lebed, Nikolai G. Uraltsev

We address numerical aspects of local quark-hadron duality using the example of the exactly solvable &#39;t Hooft model, two-dimensional QCD with N_c --> infinity. The primary focus of these studies is total semileptonic decay widths relevant for extracting |V_{cb}| and |V_{ub}|. We compare the exact channel-by-channel sum of exclusive modes to the correspon

M. B. Gay Ducati, Victor Goncalves

The high density parton effects are strongly dependent of the spatial gluon distribution within the proton, with radius $R$, which cannot be derived from perturbative QCD. In this paper we assume that the unitarity corrections are present in the HERA kinematical region and constrain the value of $R$ using the data for the proton structure function and its sl

J Bordes, HM Chan, ST Tsou

The fermion mass matrix, in addition to having eigenvalues (masses) which run, also changes its orientation (rotates) with changing energy scales. This means that its eigenstates at one scale will no longer be eigenstates at another scale, leading to effects where fermions of different flavours can ``transmute&#39;&#39; into one another. In this paper, the i

K. Boecker

We re-examine the possibility of an astrophysically allowed KSVZ-type axion that has a strongly suppressed coupling to photons. We then investigate the impact of such &#39;&#39;hadronic axions&#39;&#39; on two classes of astrophysical objects: black hole accretion disc (BHAD) based gamma-ray bursts and isolated neutron-stars. Although our results are sensiti

A. F. Zarnecki

Leptoquark searches are considered for future experiments at HERA, Tevatron, LHC, TESLA and THERA. Expected exclusion limits from direct leptoquark searches (leptoquark pair production and single leptoquark production) are compared with indirect limits expected from the contact interaction analysis. Strongest limits on the leptoquark masses and couplings are

Y. Takeuchi, Y. Tazaki, S. Y. Tsai, T. Yamazaki

The wave-packet treatment of neutrino oscillation developed previously is extended to the case in which momentum distribution functions are taken to be a Gaussian form with both central values and dispersions depending on the mass eigenstates of the neutrinos. It is shown among other things that the velocity of the neutrino wave packets does not in general a

Anton V. Ryzhov, Laurence G. Yaffe

For quantum theories with a classical limit (which includes the large N limits of typical field theories), we derive a hierarchy of evolution equations for equal time correlators which systematically incorporate corrections to the limiting classical evolution. Explicit expressions are given for next-to-leading order, and next-to-next-to-leading order time ev

Maarten Golterman, Elisabetta Pallante

The coupling constants of the order $p^2$ low-energy weak effective lagrangian can be determined from the $K\toπ$ and $K\to 0$ weak matrix elements, choosing degenerate quark masses for the first of these. However, for typical values of quark masses in Lattice QCD computations, next-to-leading $O(p^4)$ corrections are too large to be ignored, and will need t

The KLOE Collaboration

The KLOE experiment has collected 2.4 1/pb of integrated luminosity during the commissioning of the DAFNE phi-factory in 1999. The performance of the detector has been studied using phi -> KL KS decays collected during this period, yielding also first measurements of relevant K parameters such as masses and lifetimes. A clean Kshort -> pi+ pi- sample is used

GNO Collaboration, M. Altmann, M. Balata, P. Belli

We report the first GNO solar neutrino results for the measuring period GNOI, solar exposure time May 20, 1998 till January 12, 2000. In the present analysis, counting results for solar runs SR1 - SR19 were used till April 4, 2000. With counting completed for all but the last 3 runs (SR17 - SR19), the GNO I result is [65.8 +10.2 -9.6 (stat.) +3.4 -3.6 (syst.

A. K. Ciftci, S. Sultansoy, O. Yavas

Main parameters and physics goals of different colliders, which can be realized if a special 1 TeV energy linear electron accelerator or corresponding linear collider is constructed tangential to LHC, are discussed. It is shown that L_(ep)=10^(32)cm^(-2)s^(-1) at sqrt(s_(ep))=5.29 TeV can be achieved within moderate upgrade of LHC parameters. Then, Gamma-p c

Fabrizio Tamburini, Bruce A. Bassett, Carlo Ungarelli

We propose a new technique for detecting gravitational waves using Quantum Entangled STate (QUEST) technology. Gravitational waves reduce the non-locality of correlated quanta controlled by Bell&#39;s inequalities, distorting quantum encryption key statistics away from a pure white noise. Gravitational waves therefore act as shadow eavesdroppers. The resulti

T. P. Shestakova

Quantum geometrodynamics (QGD) in extended phase space essentially distinguished from the Wheeler - DeWitt QGD is proposed. The grounds for constructing a new version of quantum geometrodynamics are briefly discussed. The main part in the proposed version of QGD is given to the Schrodinger equation for a wave function of the Universe. The Schrodinger equatio

V. Aldaya, J. L. Jaramillo

A first attempt at adding matter degrees of freedom to the two-dimensional ``vacuum&#39;&#39; gravity model presented in gr-qc/9907071 is analyzed in this paper. Just as in the previous pure gravity case, quantum diffeomorphism operators (constructed from a Virasoro algebra) possess a dynamical content; their gauge nature is recovered only after the classica

J. Alberto Lobo

A general formalism is set up to analyse the response of an arbitrary solid elastic body to an arbitrary metric Gravitational Wave perturbation, which fully displays the details of the interaction antenna-wave. The formalism is applied to the spherical detector, whose sensitivity parameters are thereby scrutinised. A multimode transfer function is defined to

Pankaj S. Joshi

An outstanding problem in gravitation theory and relativistic astrophysics today is to understand the final outcome of an endless gravitational collapse. Such a continual collapse would take place when stars more massive than few times the mass of the sun collapse under their own gravity on exhausting their nuclear fuel. According to the general theory of re

Jordi Atserias, Irene Castellon, Montse Civit, German Rigau

The aim of this work is to explore new methodologies on Semantic Parsing for unrestricted texts. Our approach follows the current trends in Information Extraction (IE) and is based on the application of a verbal subcategorization lexicon (LEXPIR) by means of complex pattern recognition techniques. LEXPIR is framed on the theoretical model of the verbal subca

Jordi Atserias, Irene Castellon, Montse Civit, German Rigau

This paper presents a semantic parsing approach for unrestricted texts. Semantic parsing is one of the major bottlenecks of Natural Language Understanding (NLU) systems and usually requires building expensive resources not easily portable to other domains. Our approach obtains a case-role analysis, in which the semantic roles of the verb are identified. In o

Erik Luijten, Horst Meyer

We present a detailed discussion of the crossover from mean-field to Ising critical behavior upon approach of the critical point, both for He3 and Xe. By combining different sets of experimental data, we are able to cover an unusually large temperature range on either side of the critical temperature T_c. Below T_c, we thus can make an accurate comparison wi

Fernando F. Ferreira, Jose Fernando Fontanari, Peter F. Stadler

The statistical properties of the energy landscape of the low autocorrelated binary string problem (LABSP) are studied numerically and compared with those of several classic disordered models. Using two global measures of landscape structure which have been introduced in the Simulated Annealing literature, namely, depth and difficulty, we find that the lands

Herbert Levine, Wouter-Jan Rappel, Inon Cohen

We investigate a discrete model consisting of self-propelled particles that obey simple interaction rules. We show that this model can self-organize and exhibit coherent localized solutions in one- and in two-dimensions.In one-dimension, the self-organized solution is a localized flock of finite extent in which the density abruptly drops to zero at the edges

M. Degli Esposti, C. Giardina&#39;, S. Graffi, S. Isola

We consider the zero-temperature dynamics for the infinite-range, non translation invariant one-dimensional spin model introduced by Marinari, Parisi and Ritort to generate glassy behaviour out of a deterministic interaction. It is shown that there can be a large number of metatastable (i.e., one-flip stable) states with very small overlap with the ground st

K. Hirose, F. Zhou, N. Wingreen

Using density functional theory, we investigate fluctuations of the ground state energy of spin-polarized, disordered quantum dots in the metallic regime. To compare to experiment, we evaluate the distribution of addition energies and find a convolution of the Wigner-Dyson distribution, expected for noniteracting electrons, with a narrower Gaussian distribut

T. Melin, F. Laruelle

A Fano resonance mechanism is evidenced to control the formation of optical Fermi-edge singularities in multi-subband systems such as remotely doped AlxGa1-xAs heterostructures. Using Fano parameters, we probe the physical nature of the interaction between Fermi-sea electrons and empty conduction subbands. We show that processes of extrinsic origin like allo

D. Meyer, W. Nolting

The ferromagnetic phase diagram of the periodic Anderson model is calculated using dynamical mean-field theory in combination with the modified perturbation theory. Concentrating on the intermediate valence regime, the phase boundaries are established as function of the total electron density, the position of the atomic level and the hybridization strength.

K. S. Brown, A. A. Avanesov, V. Elser

We apply a new technique for ab initio phase determination [Acta Crystallogr. Sect. A, A55, 48 (1999)] to solve for the average structure of the icosahedral (i) phase of AlPdMn. After an introduction to the crystallographic phase problem and a description of the method, we present a brief report of our findings for the structure of i(AlPdMn). Despite the use

G. Jung, B. Savo, Y. Yuzhelevski

The interaction between the telegraph noise and background voltage fluctuations in the current induced dissipative state of high-Tc BiSrCaCuO thin films has been investigated. Experimental time records of the voltage drop across current biased thin film strips show markedly different background noise traces in the up and down telegraph states. Detailed analy

Akinori Awazu

We study the statistical properties of two hard spheres in a two dimensional rectangular box. In this system, the relation like Van der Waals equation loop is obtained between the width of the box and the pressure working on side walls. The auto-correlation function of each particle&#39;s position is calculated numerically. By this calculation near the criti

J. P. Wittmer, P. van der Schoot, A. Milchev, J. -L. Barrat

We investigate by means of a number of different dynamical Monte Carlo simulation methods the self-assembly of equilibrium polymers in dilute, semidilute and concentrated solutions under good-solvent conditions. In our simulations, both linear chains and closed loops compete for the monomers, expanding on earlier work in which loop formation was disallowed.

M. Mueller, J. P. Wittmer, J. -L. Barrat

The interplay of topological constraints, excluded volume interactions, persistence length and dynamical entanglement length in solutions and melts of linear chains and ring polymers is investigated by means of kinetic Monte Carlo simulations of a three dimensional lattice model. In unknotted and unconcatenated rings, topological constraints manifest themsel