March 2000 arXiv papers — page 20

C. Payen, E. Janod, K. Schoumacker, C. D. Batista

Experimental bulk susceptibility X(T) and magnetization M(H,T) of the S=1-Haldane chain system doped with nonmagnetic impurities, Y2BaNi1-xZnxO5 (x=0.04,0.06,0.08), are analyzed. A numerical calculation for the low-energy spectrum of non-interacting open segments describes very well experimental data above 4 K. Below 4 K, we observe power-law behaviors, X(T)

Yu. P. Svirko, Makoto Kuwata-Gonokami

We report the signatures of the exciton correlation effects with finite memory time in frequency domain degenerate four-wave mixing (DFWM) in semiconductor microcavity. By utilizing the polarization selection rules, we discriminate instantaneous, mean field interactions between excitons with the same spins, long-living correlation due to the formation of bie

Mi-Ae Park, Kerim Savran, Yong-Jihn Kim

Weak localization leads to the same correction to both the conductivity and the electron-phonon coupling constant $λ$ (and $λ_{tr}$). Consequently the temperature dependence of the (thermal) electrical resistivity is decreasing as the conductivity is decreasing due to weak localization, which results in the decrease of the temperature coefficient of resistiv

B. Khaykovich, D. T. Fuchs, K. Teitelbaum, Y. Myasoedov

Simultaneous transport and magnetization studies in Bi2Sr2CaCu2O8 crystals at elevated currents reveal large discrepancies, including finite resistivity at temperatures of 40K below the magnetic irreversibility line. This resistivity, measured at the top surface, is non-monotonic in temperature and extremely non-linear. The vortex velocity derived from magne

Ivar Martin, Alexander V. Balatsky

Recent Scanning Tunneling Microscope (STM) experiments offer a unique insight into the inner workings of the superconducting state of high-Tc superconductors. Deliberately placed inside the material impurities perturb the coherent state and produce additional excitations. Superconducting excitations - quasiparticles - are the quantum mechanical mixture of ne

Tetsuo Ohama, Atsushi Goto, Tadashi Shimizu, Emi Ninomiya

23Na NMR spectrum measurements in alpha'-NaV2O5 with a single- crystalline sample are reported. In the charge-ordered phase, the number of inequivalent Na sites observed is more than that expected from the low-temperature structures of space group Fmm2 reported so far. This disagreement indicates that the real structure including both atomic displacement

J. Shumway, L. R. C. Fonseca, J. P. Leburton, Richard M. Martin

We have calculated the exchange, correlation, and total electronic energy of a realistic InAs self-assembled quantum dot embedded in a GaAs matrix as a function of the number of electrons in the dot. The many-body interactions have been treated using the local spin density approximation (LSDA) to density functional theory (DFT) and diffusion quantum Monte Ca

G. Eyink, J. Xin

We study the two-point correlation function of a freely decaying scalar in Kraichnan&#39;s model of advection by a Gaussian random velocity field, stationary and white-noise in time but fractional Brownian in space with roughness exponent $0<ζ<2$, appropriate to the inertial-convective range of the scalar. We find all self-similar solutions, by transforming

D. A. Frail, E. Berger, T. Galama, S. R. Kulkarni

We present wide-band radio observations spanning from 1.4 GHz to 350 GHz of the afterglow of GRB 991216, taken from 1 to 80 days after the burst. The optical and X-ray afterglow of this burst were fairly typical and are explained by a jet fireball. In contrast, the radio light curve is unusual in two respects: (a) the radio light curve does not show the usua

C. Adami, B. Holden, F. J. Castander, R. C. Nichol

This paper presents and gives the COP (COP: CFHT Optical PDCS; CFHT: Canada-France-Hawaii Telescope; PDCS: Palomar Distant Cluster Survey) survey data. We describe our photometric and spectroscopic observations with the MOS multi-slit spectrograph at the CFH telescope. A comparison of the photometry from the PDCS (Postman et al. 1996) catalogs and from the n

T. Kodama, K. Matsushita

We have found the stellar populations of early-type galaxies are homogeneous with no significant difference in color or Mg2 index, despite the dichotomy between X-ray extended early-type galaxies and X-ray compact ones. Since the X-ray properties reflect the potential gravitational structure and hence the process of galaxy formation, the homogeneity of the s

M. Almudena Prieto

ROSAT/HRI observations of the powerful radio-loud galaxy 3C382 reveal extended X-ray emission associated with the source. On the basis of this new spatial component, a previous ROSAT/PSPC spectral analysis of the source is revised. Allowing for the presence of an additional thermal component in the PSPC spectrum, the non-thermal component is found to be comp

Ken&#39;ichi Nomoto, Hideyuki Umeda, Chiaki Kobayashi, Izumi Hachisu

Relatively uniform light curves and spectral evolution of Type Ia supernovae (SNe Ia) have led to the use of SNe Ia as a ``standard candle&#39;&#39; to determine cosmological parameters. Whether a statistically significant value of the cosmological constant can be obtained depends on whether the peak luminosities of SNe Ia are sufficiently free from the effe

Jonathan P. Gardner, Shobita Satyapal

Science objectives for the Next Generation Space Telescope (NGST) include a large component of galaxy surveys, both imaging and spectroscopy. The Hubble Deep Field datasets include the deepest observations ever made in the ultraviolet, optical and near infrared, reaching depths comparable to that expected for NGST spectroscopy. We present the source counts,

Edward B. Jenkins, Przemyslaw R. Wozniak, Ulysses J. Sofia, George Sonneborn

Absorption features from the Lyman and Werner bands of interstellar molecular hydrogen were recorded by the Interstellar Medium Absorption Profile Spectrograph (IMAPS) at a wavelength resolving power R=80,000 in the spectra of delta Ori and epsilon Ori. The objective was to find and study more examples of an unusual phenomenon found for one of the velocity c

L. Origlia, E. Oliva

The classical [CO] index, i.e. the strength of the CO first overtone absorption bands starting at 2.29 micron, is sometimes used to constrain the maximum age of star formation events in galaxies. In this paper we critically analyze - theoretical models which could predict either a factor of >2 drop or a pronounced increase of [CO] at ages older than 100 Myr,

D. Romano, F. Matteucci, P. Salucci, C. Chiappini

We have studied the effect of adopting different values of the total baryonic mass surface density in the local disk at the present time in a model for the chemical evolution of the Galaxy. We have compared our model results with the G-dwarf metallicity distribution, the amounts of gas, stars, stellar remnants, infall rate and SN rate in the solar vicinity,

S. Charlot, S. Michael Fall

We present a new model to compute the effects of dust on the integrated spectral properties of galaxies, based on an idealized prescription of the main features of the interstellar medium (ISM). The model includes the ionization of HII regions in the interiors of the dense clouds in which stars form and the influence of the finite lifetime of these clouds on

Tsutomu T. Takeuchi, Kohji Yoshikawa, Takako T. Ishii

We studied the statistical methods for the estimation of the luminosity function (LF) of galaxies. We focused on four nonparametric estimators: $1/V_{\rm max}$ estimator, maximum-likelihood estimator of Efstathiou et al. (1988), Chołoniewski&#39;s estimator, and improved Lynden-Bell&#39;s estimator. The performance of the $1/V_{\rm max}$ estimator has been r

Makoto Kohno, Jun Yokogawa, Katsuji Koyama

We report on the results of the ASCA and ROSAT observations on RX J0059.2-7138, a transient X-ray pulsar in the Small Magellanic Cloud. The barycentric pulse period has been precisely determined to be 2.763221 +- 0.000004 s. The pulse shape is almost identical in all of the energy bands. The pulse fraction increases with the photon energy below ~2 keV, while

S K Saha

The speckle imaging is a photographic technique that resolves objects viewed through severely distorted media. The results are insensitive to the errors caused by apparent size of the isoplanatic patch and the telescope aberrations. In this article, a short descriptions of the atmospheric turbulence and its effect on the flat wavefront from a stellar source

David S. Graff, Andrew P. Gould

Light-echo measurements show that SN1987A is 425 pc behind the LMC disk. It is continuing to move away from the disk at $18 \kms$. Thus, it has been suggested that SN1987A was ejected from the LMC disk. However, SN1987A is a member of a star cluster, so this entire cluster would have to have been ejected from the disk. We show that the cluster was formed in

Jimmy A. Irwin, Joel N. Bregman

We have derived azimuthally-averaged radial temperature profiles of the X-ray gas contained within 11 clusters of galaxies with redshift z=0.03-0.2 with BeppoSAX. Each of the 11 clusters have had their radial temperature profiles previously determined with ASCA. We find that the temperature profiles of these clusters are generally flat or increase slightly o

K. Hagino, G. F. Bertsch

We study the correlation energy associated with the pair fluctuations in BCS theory. We use a schematic two-level pairing model and discuss the behavior of the correlation energy across shell closures, including the even-odd differences. It is shown that the random phase approximation (RPA) to the ground state energy reproduces the exact solutions quite well

Tejs Vegge, James P. Sethna, Siew-Ann Cheong, Karsten W. Jacobsen

We calculate the widths, migration barriers, effective masses, and quantum tunneling rates of kinks and jogs in extended screw dislocations in copper, using an effective medium theory interatomic potential. The energy barriers and effective masses for moving a unit jog one lattice constant are close to typical atomic energies and masses: tunneling will be ra

Jiunn-Wei Chen, Markus A. Luty, Eduardo Ponton

We consider `brane universe&#39; scenarios with standard-model fields localized on a 3-brane in 6 spacetime dimensions. We show that if the spacetime is rotationally symmetric about the brane, local quantities in the bulk are insensitive to the couplings on the brane. This potentially allows compactifications where the effective 4-dimensional cosmological co

Jamal Jalilian-Marian, Sangyong Jeon, Raju Venugopalan

We propose a new form for the small x effective action in QCD. This form of the effective action is motivated by Wong&#39;s equations for classical, colored particles in non-Abelian background fields. We show that the BFKL equation, which sums leading logarithms in x, is efficiently reproduced with this form of the action. We argue that this form of the acti

Jacek Pawełczyk

Using properties of the DBI action we find D-branes on $S^3$ of the radius $Q_5$ corresponding to the conjugacy classes of SU(2). The branes are stable due to nonzero 2-form NSNS background. In the limit of large $Q_5$ the dynamics of branes is governed by the non-commutative Yang-Mills theory. The results partially overlap with those obtained in the recent

C. A. R. Herdeiro

Supersymmetric, rotating, asymptotically flat black holes with a regular horizon are rare configurations in String Theory. One example is known in five spacetime dimensions, within the toroidal compactification of type IIB string theory. Such special solution is allowed by the existence of a Chern-Simons coupling in the Supergravity theory and by the possibi

Andrés Aguado, José M. López, Julio A. Alonso

An ab initio study of the doping of alkali halide crystals (AX: A = Li, Na, K, Rb; X = F, Cl, Br, I) by ns2 anions (Ag- and Cu-) is presented. Large active clusters with 179 ions embedded in the surrounding crystalline lattice are considered in order to describe properly the lattice relaxation induced by the introduction of substitutional impurities. In all

Masayuki Tanimoto

We show examples which reveal influences of spatial topologies to dynamics, using a class of spatially {\it closed} inhomogeneous cosmological models. The models, called the {\it locally U(1)$\times$U(1) symmetric models} (or the {\it generalized Gowdy models}), are characterized by the existence of two commuting spatial {\it local} Killing vectors. For syst

M. P. Freeman, N. W. Watkins, D. J. Riley

We calculate for the first time the probability density functions (PDFs) P of burst energy e, duration T and inter-burst interval tau for a known turbulent system in nature. Bursts in the earth-sun component of the Poynting flux at 1 AU in the solar wind were measured using the MFI and SWE experiments on the NASA WIND spacecraft. We find P(e) and P(T) to be

M. Pernici, M. Raciti

We renormalize at two loops the axial current and $F \tilde{F}$ in massless QED, using the recently proposed semi-naive dimensional renormalization scheme. We show that the results are in agreement with those in the Breitenlohner-Maison-&#39;t Hooft-Veltman scheme, previously obtained indirectly by making a three-loop computation.

Naresh Dadhich, Roy Maartens, Philippos Papadopoulos, Vahid Rezania

We consider exact solutions for static black holes localized on a three-brane in five-dimensional gravity in the Randall-Sundrum scenario. We show that the Reissner-Nordstrom metric is an exact solution of the effective Einstein equations on the brane, re-interpreted as a black hole without electric charge, but with instead a tidal &#39;charge&#39; arising v

H. Nakao, K. Ohwada, N. Takesue, Y. Fujii

Charge ordering of V4+ and V5+ in NaV2O5 has been studied by an X-ray diffraction technique using anomalous scattering near a vanadium K-absorption edge to critically enhance a contrast between the two ions. A dramatic energy dependence of the superlattice intensities is observed below Tc=35 K. Consequently, the charge ordering pattern is the zigzag-type lad

Martin Sieber

We consider quantum systems with a chaotic classical limit that are perturbed by a point-like scatterer. The spectral form factor K(tau) for these systems is evaluated semiclassically in terms of periodic and diffractive orbits. It is shown for order tau^2 and tau^3 that off-diagonal contributions to the form factor which involve diffractive orbits cancel ex

S. Tsujikawa, B. A. Bassett

Metric perturbations typically strengthen field resonances during preheating. In contrast we present a model in which the super-Hubble field resonances are completely {\em suppressed} when metric perturbations are included. The model is the nonminimal Fakir-Unruh scenario which is exactly solvable in the long-wavelength limit when metric perturbations are in

T. K. Kuo, Guo-Hong Wu, Shao-Hsuan Chiu

For two flavors, the seesaw matrix can be identified with a two dimensional representation of the Lorentz group. This analogy facilitates the computation of physical neutrino parameters, while giving an intuitive understanding of the results. It is found that the induced mixing angle exhibits resonance behavior. For maximal mixing, we derive a precise relati

Jacob D. Bekenstein

A necessary condition for the validity of the holographic principle is the holographic bound: the entropy of a system is bounded from above by a quarter of the area of a circumscribing surface measured in Planck areas. This bound cannot be derived at present from consensus fundamental theory. We show with suitable {\it gedanken} experiments that the holograp

R. A. Janik, R. Peschanski

We address the problem of computing scattering amplitudes related to the correlation function of two Wilson lines and/or loops elongated along light-cone directions in strongly coupled gauge theories. Using the AdS/CFT correspondence in the classical approximation, the amplitudes are shown to be related to minimal surfaces generalizing the {\em helicoid} in

Martin Weigel, Wolfhard Janke

Using an elaborate set of simulational tools and statistically optimized methods of data analysis we investigate the scaling behavior of the correlation lengths of three-dimensional classical O($n$) spin models. Considering three-dimensional slabs $S^1\times S^1\times\mathbb{R}$, the results over a wide range of $n$ indicate the validity of special scaling r

M. Thorwart, L. Hartmann, I. Goychuk, P. Hänggi

By use of external periodic driving sources, we demonstrate the possibility of controlling the coherent as well as the decoherent dynamics of a two-level atom placed in a lossy cavity. The control of the coherent dynamics is elucidated for the phenomenon of coherent destruction of tunneling (CDT), i.e., the coherent dynamics of a driven two-level atom in a q

Ryuichiro Kitano, Katsuji Yamamoto

Lepton flavor violating processes are obtained from the mixing between ordinary leptons and vectorlike SU(2)_L doublet leptons which may originate in E_6. The effects of this lepton mixing are, however, suppressed naturally by the hierarchy of the charged lepton masses. In the supersymmetric model, significant effects of lepton flavor violation may appear ra

A. Takami, T. Hashimoto, M. Horibe, A. Hayashi

We investigate the fermion determinant of a new action on a $(1+D)$-dimensional lattice for SU(2) gauge groups. This action possesses the discrete chiral symmetry and provides $2^D$-component fermions. We also comment on the numerical results on fermion determinants in the $(1+D)$-dimensional SU(3) gauge fields.

Carlos Barcelo, Matt Visser

We describe the different possibilities that a simple and apparently quite harmless classical scalar field theory provides to violate the energy conditions. We demonstrate that a non-minimally coupled scalar field with a positive curvature coupling xi>0 can easily violate all the standard energy conditions, up to and including the averaged null energy condit

Vadim Ponomarenko, Dmitri Averin

We have analyzed Coulomb drag between currents of interacting electrons in two parallel one-dimensional conductors of finite length $L$ attached to external reservoirs. For strong coupling, the relative fluctuations of electron density in the conductors acquire energy gap $M$. At energies larger than $Γ= const \times v_- \exp (-LM/v_-)/L + Γ_{+}$, where $Γ_{

Alex Barnett, Doron Cohen, Eric J. Heller

We consider chaotic billiards in d dimensions, and study the matrix elements M_{nm} corresponding to general deformations of the boundary. We analyze the dependence of |M_{nm}|^2 on ω= (E_n-E_m)/\hbar using semiclassical considerations. This relates to an estimate of the energy dissipation rate when the deformation is periodic at frequency ω. We show that fo

Evan Scannapieco, Tom Broadhurst

We show that the winds identified with high-redshift low-mass galaxies may strongly affect the formation of stars in more massive galaxies that form later. With 3D realizations of a simple linear growth model we track gas shocking, metal enrichment, and cooling, together with dark halo formation. We show that outflows typically strip baryonic material out of

O. Obregon, M. Sabido, V. I. Tkach

Several eigenvalue equations that could describe quantum black holes have been proposed in the canonical quantum gravity approach. In this paper, we choose one of the simplest of these quantum equations to show how the usual Feynman&#39;s path integral method can be applied to obtain the corresponding statistical properties. We get a logarithmic correction t

B. E. Kane

An architecture for a quantum computer is presented in which spins associated with donors in silicon function as qubits. Quantum operations on the spins are performed using a combination of voltages applied to gates adjacent to the spins and radio frequency applied magnetic fields resonant with spin transitions. Initialization and measurement of electron spi

X. X. Yi, J. C. Su

Assuming the validity of grand canonical statistics, we study the properties of a spin-polarized Fermi gas in harmonic traps. Universal forms of Fermi temperature $T_F$, internal energy $U$ and the specific heat per particle of the trapped Fermi gas are calculated as a {\it function} of particle number, and the results compared with those of infinite number

A. S. Chirkin, F. Popescu

The consistent theory of formation of pulsed squeezed states as a result of self-action of ultrashort light pulse in the medium with relaxation Kerr nonlinearity has been developed. A simple method to form the ultrashort light pulse with sub-Poissonian photon statistics is analyzed too.

R. B. Fiorito, D. W. Rule

Diffraction radiation (DR) is produced when a charged particle passes through an aperture or near a discontinuity in the media in which it is traveling. DR is closely related to transition radiation (TR), which is produced when a charged particle traverses the boundary between media with different dielectric constants. In contrast to TR, which is now extensi

A. R. Tumanyan, Yu. L. Martirosyan, V. C. Nikhogosyan, N. Z. Akopov

An asynchronous accelerator is described, in which the principle of its operation permits the active longitudinal bunch compression of accelerated proton beams, to overcome the space charge limitation effects of intense bunches. It is shown that accelerated bunches from an RFQ linac can be adapted for Asynchronac injection for a multiple of choices in the ac

Didier Felbacq, Brahim Guizal, Frederic Zolla

We show numerically for the first time that ultra-refractive phenomena do exist in one-dimensional photonic crystals: we exhibit the main features of ultra-refraction, that is the enlargement and the splitting of an incident beam. We give a very simple explanation of these phenomena in terms of the photonic band structure of these media.

S. Liu, Y. Alhassid, H. Nakada

A particle-number reprojection method is applied in the framework of the shell model Monte Carlo approach to calculate level densities for a family of nuclei using Monte Carlo sampling for a single nucleus. In particular we can also calculate level densities of odd-even and odd-odd nuclei despite a new sign problem introduced by the projection on an odd numb

Jean Letessier, Johann Rafelski

We review the methods and results obtained in an analysis of the experimental heavy ion collision research program at nuclear beam energy of 160-200A GeV. We study strange, and more generally, hadronic particle production experimental data. We discuss present expectations concerning how these observables will perform at other collision energies. We also pres

Madeleine Soyeur, Matthias Lutz, Bengt Friman

The study of the pi^- p -> rho^0 n and pi^- p -> omega n amplitudes close and below the vector meson production threshold (1.2< sqrt(s) <1.8 GeV) reveals a rich dynamics arising from the presence of specific baryon resonances in this energy range. The interference pattern of the e^+e^- decays of the rho^0 and omega mesons produced in pi^- p reactions reflect

B. Friman, M. Lutz, G. Wolf

We employ meson-nucleon scattering data to deduce the properties of the low-mass vector mesons in nuclear matter, and present results for the $ρ$ and $ω$ in-medium spectral functions. The corresponding thermal emission rate for lepton pairs is also discussed.

Didier Felbacq

We analyze electromagnetic waves propagation in one-dimensional periodic media with single or periodic defects. The study is made both from the point of view of the modes and of the diffraction problem. We provide an explicit dispersion equation for the numerical calculation of the modes, and we establish a connection between modes and poles and zeros of the

Anupam Garg

A formalism is developed to study certain five-term recursion relations by discrete phase integral (or Wentzel-Kramers-Brillouin) methods. Such recursion relations arise naturally in the study of the Schrodinger equation for certain spin Hamiltonians. The conditions for the validity of the phase integral approximation are derived. It is shown that in contras

Tatyana Foth, Svetlana Katok

Let G be a semisimple Lie group with no compact factors, K a maximal compact subgroup of G, and $Γ$ a lattice in G. We study automorphic forms for $Γ$ if G is of real rank one with some additional assumptions, using dynamical approach based on properties of the homogeneous flow on $Γ\backslash G$ and a Livshitz type theorem we prove for such a flow. In the H

Benson Farb, Michael Wolf

We give a proof, using harmonic maps from disks to real trees, of Skora&#39;s theorem (Morgan-Otal (1993), Skora (1990), originally conjectured by Shalen): if G is the fundamental group of a surface of genus at least 2, then any small minimal G-action on a real tree is dual to the lift of a measured foliation. Analytic tools like the maximum principle are us

Timo Seppalainen

We study a totally asymmetric simple exclusion process where jumps happen at rate one, except at the origin where the rate is lower. We prove a hydrodynamic scaling limit to a macroscopic profile described by a variational formula. The limit is valid for all values of the slow rate. The only assumption required is that a law of large numbers holds for the in

Manuel Pedreira-Perez, Luis-Eduardo Sola-Conde

In this paper we give the projective generation of congruences of order 1 of r-dimensional projective spaces in P^N from their focal loci. In a natural way, this construction shows that the corresponding surfaces in the grassmannian are the Veronese surface, and rational ruled surfaces eventually with singularities. We characterize when these surfaces are sm

Ruth Britto-Pacumio, Jeremy Michelson, Andrew Strominger, Anastasia Volovich

This contribution to the proceedings of the 1999 NATO ASI on Quantum Geometry at Akureyri, Iceland, is based on notes of lectures given by A. Strominger. Topics include N-particle conformal quantum mechanics, extended superconformal quantum mechanics and multi-black hole moduli spaces.

Hisa-aki Shinkai, Tetsuya Shiromizu

We numerically study classical time evolutions of Kaluza-Klein bubble space-time which has negative energy after a decay of vacuum. As the zero energy Witten&#39;s bubble space-time, where the bubble expands infinitely, the subsequent evolutions of Brill and Horowitz&#39;s momentarily static initial data show that the bubble will expand in terms of the area.

V. A. Kazakov

A new formulation of four dimensional quantum field theories, such as scalar field theory, is proposed as a large N limit of a special NxN matrix model. Our reduction scheme works beyond planar approximation and applies for QFT with finite number of fields. It uses quenched coordinates instead of quenched momenta of the old Eguchi-Kawai reduction known to yi

V. A. Kazakov

We review some old and new methods of reduction of the number of degrees of freedom from ~N^2 to ~N in the multi-matrix integrals.

N. Alonso-Alberca, P. Meessen

We consider cosmological solutions to type II supergravity theories where the spacetime is split into a FRW universe and a Kähler space, which may be taken to be Calabi-Yau. The various 2-forms present in the theories are taken to be proportional to the Kähler form associated to the Kähler space.

Lee Smolin

We review the different proposals which have so far been made for the holographic principle and the related entropy bounds and classify them into the strong, null and weak forms. These are analyzed, with the aim of discovering which may hold at the level of the full quantum theory of gravity. We find that only the weak forms, which constrain the information

J. K. Erickson, G. W. Semenoff, K. Zarembo

Perturbative computations of the expectation value of the Wilson loop in N=4 supersymmetric Yang-Mills theory are reported. For the two special cases of a circular loop and a pair of anti-parallel lines, it is shown that the sum of an infinite class of ladder-like planar diagrams, when extrapolated to strong coupling, produces an expectation value characteri

Yungui Gong

We find that the mixture of Ramond-Ramond fields and Neveu-Schwarz two form are transformed as Majorana spinors under the T-duality group $O(d,d)$. The Ramond-Ramond field transformation under the group $O(d,d)$ is realized in a simple form by using the spinor representation. The Ramond-Ramond field transformation rule obtained by Bergshoeff et al. is shown

Richard Shurtleff

An electron neutrino can have the quantum phase of an electron, i.e. share its internal clock, if the neutrino takes a path in space-time that is not in the direction of its energy-momentum. Each flavor neutrino would then have a different internal clock; a muon neutrino would have a muon clock and a tau neutrino would have a tau clock. Perhaps surprisingly,

David London

The first measurements of CP violation in the B system will probably extract $\sin 2α$, $\sin 2β$ and $\cos 2γ$. Assuming that the CP angles $α$, $β$ and $γ$ are the interior angles of the unitarity triangle, this determines the angle set $(α,β,γ)$ up to a twofold discrete ambiguity. The presence of this discrete ambiguity can make the discovery of new physi

I. Akushevich, E. Kuraev, B. Shaikhatdenov

We calculate DIS cross section under kinematical requirements when a final hadron state is a single proton. The process in the lowest order is known as radiative tail from elastic peak. We take into account correction, coming from emission of virtual and soft real photons, to the amplitude of this process as well as the one, induced by emission of additional

Bin Zhang, Hanqing Zheng

We study the properties of heavy fermions in the vector-like representation of the electro-weak gauge group $SU(2)_W\times U(1)_Y$ with Yukawa couplings to the standard model Higgs boson. Applying the renormalization group analysis, we discuss the effects of heavy fermions to the vacuum stability bound and the triviality bound on the mass of the Higgs boson.

N. A. Korkhmazyan, N. N. Korkhmazyan

The new quantum number σis introduced. It is shown that the conservation of σ-number results in the conservation of difference between baryon and lepton numbers obtained earlier by Georgi and Glashow. The conservation of σ-number also predicts that electron type neutrino mass is exactly zero. The quark-lepton symmetry is discussed. It is shown that the natur

M. Galynsky, E. Kuraev, P. Ratcliffe, B. Shaikhatdenov

We consider double-photon and bremsstrahlung mechanisms for the production of two charged pions in high-energy electron (or proton) scattering off a transversely polarised proton. Interference between the relevant amplitudes generates a charge-odd contribution to the cross-section for the process. In the kinematical configuration with a jet nearly collinear

WA98 Collaboration, M. M. Aggarwal

Two-particle correlations have been measured for identified negative pions from central 158 AGeV Pb+Pb collisions and fitted radii of about 7 fm in all dimensions have been obtained. A multi-dimensional study of the radii as a function of kT is presented, including a full correction for the resolution effects of the apparatus. The cross term Rout-long of the

Richard J. Epp

Owing to its transformation property under local boosts, the Brown-York quasilocal energy surface density is the analogue of E in the special relativity formula: E^2-p^2=m^2. In this paper I will motivate the general relativistic version of this formula, and thereby arrive at a geometrically natural definition of an `invariant quasilocal energy&#39;, or IQE.

Hongya Liu, James Overduin

The classical tests of general relativity - light deflection, time delay and perihelion shift - are applied, along with the geodetic precession test, to the five-dimensional extension of the theory known as Kaluza-Klein gravity, using an analogue of the four-dimensional Schwarzschild metric. The perihelion advance and geodetic precession calculations are gen

Amos Ori, Kip S. Thorne

There are three regimes of gravitational-radiation-reaction-induced inspiral for a compact body with mass mu, in a circular, equatorial orbit around a Kerr black hole with mass M>>mu: (i) The &#34;adiabatic inspiral regime&#34;, in which the body gradually descends through a sequence of circular, geodesic orbits. (ii) A &#34;transition regime&#34;, near the

J. Baker, M. Campanelli

We consider curvature invariants in the context of black hole collision simulations. In particular, we propose a simple and elegant combination of the Weyl invariants I and J, the {\sl speciality index} ${\cal S}$. In the context of black hole perturbations $\cal S$ provides a measure of the size of the distortions from an ideal Kerr black hole spacetime. Ex

A. Tartaglia

Considering the spacetime around a rotating massif body it is seen that the time of flight of a light ray is different whether it travels on one side of the source or on the other. The difference is proportional to the angular momentum of the body. In the case that a compact rapidly rotating object is the source of a gravitational lensing effect, the contrib

Jeffrey Winicour

I describe a new algorithm for solving nonlinear wave equations. In this approach, evolution takes place on characteristic hypersurfaces. The algorithm is directly applicable to electromagnetic, Yang-Mills and gravitational fields and other systems described by second differential order hyperbolic equations. The basic ideas should also be applicable to hydro

J. Baker, B. Bruegmann, M. Campanelli, C. O. Lousto

We present the first results in a new program intended to make the best use of all available technologies to provide an effective understanding of waves from inspiralling black hole binaries in time for imminent observations. In particular, we address the problem of combining the close-limit approximation describing ringing black holes and full numerical rel

Naresh Dadhich

If we consider the spacetime manifold as product of a constant curvature 2-sphere (hypersphere) and a 2-space, then solution of the Einstein equation requires that the latter must also be of constant curvature. There exist only two solutions for classical matter distribution which are given by the Nariai (anti) metric describing an Einstein space and the Ber

Homer G. Ellis

The geometry of three-dimensional space guides the search for a better model than the blackhole with its unwelcome singularity. An elementary construction produces on the 4-manifold of 2-spheres in a Riemannian 3-space a space-time metric invariant under uniform conformal transformations of the 3-space. When the 3-space is Euclidean, the metric reduces to de

Luc Bovens, Stephan Hartmann

We construct a probabilistic coherence measure for information sets which determines a partial coherence ordering. This measure is applied in constructing a criterion for expanding our beliefs in the face of new information. A number of idealizations are being made which can be relaxed by an appeal to Bayesian Networks.

Frances L. Johnson, Stuart C. Shapiro

SNePS is a mature knowledge representation, reasoning, and acting system that has long contained a belief revision subsystem, called SNeBR. SNeBR is triggered when an explicit contradiction is introduced into the SNePS belief space, either because of a user&#39;s new assertion, or because of a user&#39;s query. SNeBR then makes the user decide what belief to

Maarit Hietalahti, Fabio Massacci, Ilkka Niemela

The US Data Encryption Standard, DES for short, is put forward as an interesting benchmark problem for nonmonotonic reasoning systems because (i) it provides a set of test cases of industrial relevance which shares features of randomly generated problems and real-world problems, (ii) the representation of DES using normal logic programs with the stable model

Richard Watson

Over the past decade a considerable amount of research has been done to expand logic programming languages to handle incomplete information. One such language is the language of epistemic specifications. As is usual with logic programming languages, the problem of answering queries is intractable in the general case. For extended disjunctive logic programs,

Uwe Egly, Thomas Eiter, Hans Tompits, Stefan Woltran

In this paper, we outline the prototype of an automated inference tool, called QUIP, which provides a uniform implementation for several nonmonotonic reasoning formalisms. The theoretical basis of QUIP is derived from well-known results about the computational complexity of nonmonotonic logics and exploits a representation of the different reasoning tasks in

Thomas Eiter, Wolfgang Faber, Christoph Koch, Nicola Leone

DLV is an efficient logic programming and non-monotonic reasoning (LPNMR) system with advanced knowledge representation mechanisms and interfaces to classic relational database systems. Its core language is disjunctive datalog (function-free disjunctive logic programming) under the Answer Set Semantics with integrity constraints, both default and strong (or

Gerhard Brewka

In this paper we introduce a nonmonotonic framework for belief revision in which reasoning about the reliability of different pieces of information based on meta-knowledge about the information is possible, and where revision strategies can be described declaratively. The approach is based on a Poole-style system for default reasoning in which entrenchment i

Ilkka Niemela, Patrik Simons, Tommi Syrjanen

The Smodels system implements the stable model semantics for normal logic programs. It handles a subclass of programs which contain no function symbols and are domain-restricted but supports extensions including built-in functions as well as cardinality and weight constraints. On top of this core engine more involved systems can be built. As an example, we h

Henrik Grosskreutz, Gerhard Lakemeyer

High-level robot controllers in realistic domains typically deal with processes which operate concurrently, change the world continuously, and where the execution of actions is event-driven as in ``charge the batteries as soon as the voltage level is low&#39;&#39;. While non-logic-based robot control languages are well suited to express such scenarios, they

Carmen Vodislav, Robert E. Mercer

We propose a new approach to belief revision that provides a way to change knowledge bases with a minimum of effort. We call this way of revising belief states optimal belief revision. Our revision method gives special attention to the fact that most belief revision processes are directed to a specific informational objective. This approach to belief change

Bert Van Nuffelen, Marc Denecker

The goal of the LP+ project at the K.U.Leuven is to design an expressive logic, suitable for declarative knowledge representation, and to develop intelligent systems based on Logic Programming technology for solving computational problems using the declarative specifications. The ID-logic is an integration of typed classical logic and a definition logic. Dif