October 2001 arXiv papers — page 7

Ph. Boucaud, V. Giménez, C. -J. D. Lin, V. Lubicz

We propose an approach for calculating $K\toππ$ decays to the next-to-leading order in chiral expansion. A detailed numerical study of this approach is being performed.

Chuan Liu, Junhua Zhang, Ying Chen, J. P. Ma

Using the tadpole improved clover Wilson quark action on coarse anisotropic lattices, the $ππ$ scattering length in the I=2 channel is calculated within quenched approximation. We show that such a calculation is feasible using small lattices on small computers provided that the finite volume and finite lattice spacing errors are under control. Our results ar

Wolfgang Menges

Future high energy linear electron positron colliders with centre-of-mass enegies between 90 and 1000 GeV offer a unique opportunity to study precisely the Standard Model and phenomena from new physics. Most important, the mechanism of electroweak symmetry breaking can be established in full depth if one or more Higgs bosons are observed. Precision measureme

B. Aubert

The branching fractions of the exclusive decays $B^0\to K^{*0}γ$ and $B^+ \to K^{*+}γ$ are measured from a sample of $(22.74\pm 0.36)\times 10^6$ $B\bar B$ decays collected with the BABAR detector at the PEP II asymmetric $e^{+}e^{-}$ collider. We find ${\cal B}(B^0\to K^{*0}γ) = (4.23\pm 0.40({\rm stat.})\pm 0.22({\rm sys.}))\times 10^{-5}$, ${\cal B}(B^+\t

Giorgio Chiarelli

The Tevatron Run II will provide CDF and D0 with a large dataset of ppbar interactions collected at sqrt(s)=2 TeV. We discuss the opportunity for the two experiments to improve the understanding of electrowek and top physics in the first years of data taking (Run IIa,2fb-1) in view of the upgrades of the detectors. We also discuss the prospectives for a Higg

Stefan Davids

A state sum model based on the group SU(1,1) is defined. Investigations of its geometry and asymptotics suggest it is a good candidate for modelling (2+1) Lorentzian quantum gravity.

A. M. Ignatov

An example of discontinuity of the energy-momentum tensor moving at superluminal velocity is discussed. It is shown that the gravitational Mach cone is formed. The power spectrum of the corresponding Cherenkov radiation is evaluated.

N. Andersson, G. L. Comer

We discuss the possibility that future gravitational-wave detectors may be able to detect various modes of oscillation of old, cold neutron stars. We argue that such detections would provide unique insights into the superfluid nature of neutron star cores, and could also lead to a much improved understanding of pulsar glitches. Our estimates are based on a d

Fabrizio Sebastiani

The automated categorization (or classification) of texts into predefined categories has witnessed a booming interest in the last ten years, due to the increased availability of documents in digital form and the ensuing need to organize them. In the research community the dominant approach to this problem is based on machine learning techniques: a general in

Helen Nissenbaum, Batya Friedman, Edward Felten

This paper focuses on a tension we discovered in the philosophical part of our multidisciplinary project on values in web-browser security. Our project draws on the methods and perspectives of empirical social science, computer science, and philosophy to identify values embodied in existing web-browser security and also to prescribe changes to existing syste

Matt Ratto

This paper uses the software program Linux and the discourse around it in order to examine how software programs can be used to articulate and defend social and economic positions. Although I do not use the term "expression" in a strict legal sense, I claim that in order to make policy decisions involving software, it is important to understand how t

R. Polk Wagner, Catherine T. Struve

In this piece, we take up the case of the domain name system as an example of challenges and solutions for realspace sovereigns in cyberspace. First, we analyze the 'in rem' provision of the US Anticybersquatting Consumer Protection Act (ACPA), which purports to expand the scope of the ACPA to encompass disputes with little direct connection with the

V. Brian Viard

Do switching costs reduce or intensify price competition in markets where firms charge the same price to old and new consumers? Theoretically, the answer could be either "yes" or "no," due to two opposing incentives in firms' pricing decisions. The firm would like to charge a higher price to previous purchasers who are "locked-in"

Xuan P. A. Gao, Allen P. Mills,, Arthur P. Ramirez, Loren N. Pfeiffer

We have investigated the effect of an in plane parallel magnetic field (B_||) on two high mobility metallic-like dilute two-dimensional hole gas (2DHG) systems in GaAs quantum wells. The experiments reveal that, while suppressing the magnitude of the low temperature resistance drop, B_|| does not affect E_a, the characteristic energy scale of the metallic re

R. M. Stroud, A. T. Hanbicki, Y. D. Park, A. G. Petukhov

We report the first experimental demonstration that interface microstructure limits diffusive electrical spin injection efficiency across heteroepitaxial interfaces. A theoretical treatment shows that the suppression of spin injection due to interface defects follows directly from the contribution of the defect potential to the spin-orbit interaction, result

J. Tempere, Isaac F. Silvera, J. T. Devreese

The effect of pressure and negative pressure on the modes of oscillation of a multi-electron bubble in liquid helium is calculated. Already at low pressures of the order of 10-100 mbar, these effects are found to significantly modify the frequencies of oscillation of the bubble. Stabilization of the bubble is shown to occur in the presence of a small negativ

S. V. Stolbov, R. E. Cohen

The electronic structure and total energy were calculated for ordered and disordered MgO-CaO solid solutions within the multiple scattering theory in real space and the local density approximation. Based on the dependence of the total energy on the unit cell volume the equilibrium lattice parameter and formation energy were determined for different solution

P. D. Drummond, K. V. Kheruntsyan

We give an asymptotic analytic solution for the generic atom-laser system with gain in a $D$-dimensional trap, and show that this has a non-Thomas-Fermi behavior. The effect is due to Bose-enhanced condensate growth, which creates a local density maximum and a corresponding outward momentum component. In addition, the solution predicts amplified center-of-ma

P. D. Drummond, K. V. Kheruntsyan, H. He

We analyze the coherent formation of molecular BEC from an atomic BEC, using a parametric field theory approach. We point out the transition between a quantum soliton regime, where atoms couple in a local way - to a classical soliton domain, where a stable coupled-condensate soliton can form in three dimensions. This gives the possibility of an intense, stab

D. J. Heinzen, R. H. Wynar, P. D. Drummond, K. V. Kheruntsyan

We analyze the dynamics of a dilute, trapped Bose-condensed atomic gas coupled to a diatomic molecular Bose gas by coherent Raman transitions. This system is shown to result in a new type of `superchemistry', in which giant collective oscillations between the atomic and molecular gas can occur. The phenomenon is caused by stimulated emission of bosonic a

N. Stefanakis

The tunneling conductance spectra of a normal metal / insulator / singlet superconductor is calculated from the reflection amplitudes using the Blonder-Tinkham-Klapwijk (BTK) formulation. The pairing symmetry of the superconductor is assumed to be $d_{x^2-y^2}+is$, or $d_{x^2-y^2}+id_{xy}$. It is found that in the ($d_{x^2-y^2}+is$)-wave case there is a well

M. E. Foglio, M. C dos Santos, G. E. Barberis, J. M. Rojo

Experiments of Electron Spin Resonance (ESR) were performed on Co$% ^{2+}$ substituting Zn$^{2+}$ or Mg$^{2+}$ in powder samples of Zn$_2$(OH)PO$_4$ and Mg$_2$(OH)AsO$_4$. The observed resonances are described with a theoretical model that considers the departures from the two perfect structures. It is shown that the resonance in the penta-coordinated comple

Murat Tas, Mehmet Tomak

The Singwi, Sjolander, Tosi, Land (SSTL) approach is generalized to study the spin correlation effects in a one dimensional electron gas. It is shown that the SSTL approach is capable of generating results comparable to the more widely used STLS approach.

Olaf Stenull, Hans-Karl Janssen

Focusing on multifractal properties we investigate electric transport on random resistor diode networks at the phase transition between the non-percolating and the directed percolating phase. Building on first principles such as symmetries and relevance we derive a field theoretic Hamiltonian. Based on this Hamiltonian we determine the multifractal moments o

Y. Piskunov, D. Jérome, P. Auban-Senzier, P. Wzietek

(63)Cu-NMR measurements have been performed on two-leg hole-doped spin ladders Sr_{14-x}Ca_{x}Cu_{24}O_{41} single crystals (0-x-12) at several pressures up to the pressure domain where the stabilization of a superconducting ground state can be achieved. The data reveal marked decrease of the spin gap derived from Knight shift measurements upon Ca substituti

Ronald Dickman

Applied to the master equation, the usual numerical integration methods, such as Runge-Kutta, become inefficient when the rates associated with various transitions differ by several orders of magnitude. We introduce an integration scheme that remains stable with much larger time increments than can be used in standard methods. When only the stationary distri

Ronald Dickman, Ronaldo Vidigal

We study the long-time behavior of stochastic models with an absorbing state, conditioned on survival. For a large class of processes, in which saturation prevents unlimited growth, statistical properties of the surviving sample attain time-independent limiting values. We may then define a quasi-stationary probability distribution as one in which the ratios

Roman Karasik, Nir Sapir, Yosef Ashkenazy, Plamen Ch. Ivanov

We study the heartbeat activity of healthy individuals at rest and during exercise. We focus on correlation properties of the intervals formed by successive peaks in the pulse wave and find significant scaling differences between rest and exercise. For exercise the interval series is anticorrelated at short time scales and correlated at intermediate time sca

Falk Scheffler, Philipp Maass

We investigate spin precession in the presence of randomly distributed field sources. Their fields h_i reorient by thermally activated transitions and decrease as r^{-mu} with the distance from the spin probe. Based on analytical calculations and scaling arguments we find that the polarization decay of a spin ensemble exhibits a rich behavior characterized b

S. Drozdz, M. Wojcik

We investigate the origin of order in the low-lying spectra of many-body systems with random two-body interactions. Our study based both on analytical as well as on numerical arguments shows that except for the most $J$-stretched states, the ground states in the higher $J$-sectors are more orderly and develop larger energy gaps than the ones in the J=0-secto

Noboru Fukushima, Yoshio Kuramoto

Thermodynamic properties of the SU($n$) Heisenberg model in one dimension is studied by means of high-temperature expansion for arbitrary $n$. The specific heat up to $O[(βJ)^{23}]$ and the correlation function up to $O[(βJ)^{18}]$ are derived with $βJ$ being the antiferromagnetic exchange in units of temperature. It is found for $n>2$ that the specific heat

Y. Itoh, T. Machi, N. Watanabe, S. Adachi

We estimated the spread of the magnetically enhanced regions (wipeout regions) around Zn ions in high-Tc superconductors YBa2(Cu1-xZnx)4O8 (x=0, 0.005, 0.01, and 0.022) at T=4.2 K, via the planar 63Cu nuclear spin-lattice relaxation study with Cu nuclear quadrupole resonance (NQR) spin-echo technique. From the analysis of nonexponential planar Cu nuclear spi

D. Mihailovic, D. Dvorsek, V. V. Kabanov, J. Demsar

An ultrafast paralell data processor is described in which amplitude mode excitations of a charge density wave (CDW) are used to encode data on the surface of a 1-T TaS_2 crystal. The data are written, manipulated and read using parallel femtosecond laser pulse beams, and the operation of a database search algorithm is demonstrated on a 2-element array.

N. Stefanakis

We calculate the tunneling conductance spectra of a ferromagnetic metal / insulator / triplet superconductor from the reflection amplitudes using the Blonder-Tinkham-Klapwijk (BTK) formula. For the triplet superconductor, we assume one special $p$-wave order parameter, having line nodes, and two two dimensional $f$-wave order parameters with line nodes, brea

T. Tohyama, S. Maekawa

We investigate the electronic states in the antiferromagnetic (AF) phase of electron-doped cuprates by using numerically exact diagonalization technique for a t-t'-t''-J model. When AF correlation develops with decreasing temperature, a gaplike behavior emerges in the optical conductivity. Simultaneously, the coherent motion of carriers due to th

J. E. Hibbard, J. M. van der Hulst, J. E. Barnes, R. M. Rich

We present new VLA C+D-array HI observations and optical and NIR imaging of the well known interacting system NGC 4038/9, ``The Antennae''. The radio data reveal a wealth of gaseous sub-structure both within the main bodies of the galaxies and along the tidal tails. In agreement with previous HI studies, we find that the northern tail has HI along it

A. Del Popolo

In this paper we extend Chandrasekhar and von Neumann's analysis of the statistics of the gravitational field to systems in which particles (e.g. stars, galaxies) are not homogeneously distributed. We derive a distribution function W(F,d F/dt) giving the joint probability that a test particle is subject to a force F and an associated rate of change of F

S. C. Gallagher, W. N. Brandt, G. Chartas, G. Garmire

For the population of QSOs with broad ultraviolet absorption lines, we are just beginning to accumulate X-ray observations with enough counts for spectral analysis at CCD resolution. From a sample of eight QSOs [including four Broad Absorption Line (BAL) QSOs and three mini-BAL QSOs] with ASCA or Chandra spectra with more than 200 counts, general patterns ar

N. Nakasato

In the current most plausible Cold Dark Matter (CDM) cosmology, larger clumps increase their mass by the progressive merger of smaller clumps. During the evolution, a several merger events, e.g., many minor and a few major merger events, strongly affect the morphology of galaxies as assumed in semi-analytic models. With our physically most detailed high reso

A. Collier Cameron, K. Horne, A. Penny, C. Leigh

In data from three clear nights of a WHT/UES run in 2000 Oct/Nov, and using improved Doppler tomographic signal-analysis techniques, we have carried out a deep search for starlight reflected from the innermost of upsilon And's three planets. We place upper limits on the planet's radius R_p as functions of its projected orbital velocity K_p ~ 139 sin

M. Heydari-Malayeri, M. R. Rosa, D. Schaerer, F. Martins

Using Hubble Space Telescope observations with STIS, we study the main exciting stars of N81, a high excitation compact Hii region in the Small Magellanic Cloud (SMC). These far UV observations are the first spectroscopic measurements of stars in such a region and reveal features characteristic of an O6-O8 stellar type. The astonishing weakness of their wind

R. Faraggiana, M. Gerbaldi, P. Bonifacio

We demonstrate that HD 174005, a star recently classified as belonging to the lambda Boo group, is in reality a double lined spectroscopic binary; at some phases, the observed composite spectrum may be similar to that of a single star with weak metal lines.

G. Cusumano, G. Agnetta, B. Biondo, O. Catalano

GAW (Gamma Air Watch) is a new imaging Cherenkov telescope designed for observation of very high-energy gamma-ray sources. GAW will be equipped with a 3 meter diameter Fresnel lens as light collector and with an array of 300 multi-anode photomultipliers at the focal plane. The pixel size will be 4 arcmin wide for a total field of view of 10.5 degrees. Whith

G. Tautvaisiene, B. Edvardsson, I. Tuominen, I. Ilyin

High-resolution spectra of 13 core helium-burning stars in the thick disk of the Galaxy have been obtained with the SOFIN spectrograph on the Nordic Optical Telescope to investigate abundances of up to 22 chemical elements. Abundances of carbon were studied using the C_2 Swan (0,1) band head at 5635.5 A. The wavelength interval 7980-8130 A with strong CN fea

A. M. Hopkins, C. J. Miller, A. J. Connolly, C. Genovese

The False Discovery Rate (FDR) method has recently been described by Miller et al (2001), along with several examples of astrophysical applications. FDR is a new statistical procedure due to Benjamini and Hochberg (1995) for controlling the fraction of false positives when performing multiple hypothesis testing. The importance of this method to source detect

Linpeng Cheng, Jianyan Wei, Yongheng Zhao

In order to understand how the soft X-ray spectra vary we present the Hardness Ratio 1 versus Count Rates (HR1-CTs) correlation of 8 Narrow-line Seyfert 1 Galaxies (NLS1s) and 14 Broad-line Seyfert1 Galaxies (BLS1s) obtained during the ROSAT PSPC pointing observations. According to our criteria, six of the NLS1s show a positive HR1-CTs correlation, and seven

Lindsay J. Bartholomew, James A. Rose, Alejandro E. Gaba, Nelson Caldwell

Galaxies in rich clusters with z $\gtrsim$ 0.3 are observed to have a higher fraction of photometrically blue galaxies than their nearby counterparts. This raises the important question of what environmental effects can cause the termination of star formation between z $\approx$ 0.3 and the present. The star formation may be truncated due to ram-pressure str

Ramesh Narayan, Mikhail V. Medvedev

We estimate the thermal conductivity of a weakly collisional magnetized plasma with chaotic magnetic field fluctuations. When the fluctuation spectrum extends over two or more decades in wave-vector, we find that thermal conduction is very efficient; the conduction coefficient is only a factor ~5 below the classical Spitzer estimate. We suggest that conducti

Manuele Santoprete, Giampaolo Cicogna

In this paper we prove the occurence of chaos for charged particles moving around a Schwarzshild black hole, perturbed by uniform electric and magnetic fields. The appearance of chaos is studied resorting to the Poincare'-Melnikov method.

Siming Liu, Fulvio Melia

The recent detection of a three-hour X-ray flare from Sgr A* by Chandra provides very strong evidence for a compact emitting region near this supermassive black hole at the Galactic center. Sgr A*'s mm/sub-mm spectrum and polarimetric properties, and its quiescent-state X-ray flux density, are consistent with a model in which low angular momentum gas cap

Greg Huey, Stephon Alexander, Levon Pogosian

We study dependence of the CMB temperature anisotropy spectrum on the value of the fine structure constant $α$ and the equation of state of the dark energy component of the total density of the universe. We find that bounds imposed on the variation of $α$ from the analysis of currently available CMB data sets can be significantly relaxed if one also allows f

K. D. Belashchenko, V. P. Antropov

We suggest a workable approach for the description of multiscale magnetization reversal phenomena in nanoscale magnets and apply it to CoPt-type alloys. We show that their hysteretic properties are governed by two effects originating at different length scales: a peculiar splitting of domain walls and their strong pinning at antiphase boundaries. We emphasiz

I. Y. Park, C. N. Pope, A. Sadrzadeh

We obtain new results for consistent braneworld Kaluza-Klein reductions, showing how we can derive four-dimensional N=2 gauged supergravity ``localised on the AdS_4 brane'' as an exact embedding in five-dimensional N=4 gauged supergravity. Similarly, we obtain five-dimensional N=2 gauged supergravity localised on an AdS_5 brane as a consistent Kaluza

K. Redlich, J. Cleymans, H. Oeschler, A. Tounsi

We discuss the role of the conservation laws related with U(1) internal symmetry group in the statistical model description of particle productions in ultrarelativistic heavy ion collisions. We derive and show the differences in particle multiplicities in the canonical and the grand canonical formulation of quantum number conservation. The time evolution and

Lee Lindblom, Benjamin J. Owen

Neutron stars are expected to contain a significant number of hyperons in addition to protons and neutrons in the highest density portions of their cores. Following the work of Jones, we calculate the coefficient of bulk viscosity due to nonleptonic weak interactions involving hyperons in neutron-star cores, including new relativistic and superfluid effects.

Nathan F. Lepora

We show that the correspondence between SU(5) monopoles and the elementary particles, which underlies the construction of a dual standard model, has some simpler analogues associated with the strong, weak and hypercharge interactions. We then discuss how these analogues relate to Bais' generalization of the Montenon-Olive conjecture and find the represen

Jens Fjelstad, Stephen Hwang

We examine the connection between three dimensional gravity with negative cosmological constant and two-dimensional CFT via the Chern-Simons formulation. A set of generalized spectral flow transformations are shown to yield new sectors of solutions. One implication is that the microscopic calculation of the entropy of the Banados-Teitelboim-Zanelli (BTZ) bla

Henry P. Stapp

It is emphasized that a many-worlds interpretation of quantum theory exists only to the extent that the associated basis problem is solved. The core basis problem is that the robust enduring states specified by environmental decoherence effects are essentially Gaussian wave packets that form continua of non-orthogonal states. Hence they are not a discrete se

Rong-Gen Cai, Yun Soo Myung, Yuan-Zhong Zhang

Recently an interesting conjecture was put forward which states that any asymptotically de Sitter space whose mass exceeds that of exact de Sitter space contains a cosmological singularity. In order to test this mass bound conjecture, we present two solutions. One is the topological de Sitter solution and the other is its dilatonic deformation. Although the

A. M. Levin, M. A. Olshanetsky, A. Zotov

The aim of this paper is two-fold. First, we define symplectic maps between Hitchin systems related to holomorphic bundles of different degrees. We call these maps the Symplectic Hecke Correspondence (SHC) of the corresponding Higgs bundles. They are constructed by means of the Hecke correspondence of the underlying holomorphic bundles. SHC allows to constru

T. Inoue, E. Oset, M. J. Vicente Vacas

We study the S-wave interaction of mesons with baryons in the strangeness S=0 sector in a coupled channel unitary approach. The basic dynamics is drawn from the lowest order meson baryon chiral Lagrangians. Small modifications inspired by models with explicit vector meson exchange in the t-channel are also considered. In addition the pi pi N channel is inclu

Ralph Blumenhagen, Volker Braun

We present the construction of exactly solvable superconformal field theories describing Type II string models compactified on compact G_2 manifolds. These models are defined by anti-holomorphic quotients of the form (CY*S^1)/Z_2, where we realize the Calabi-Yau as a Gepner model. In the superconformal field theory the Z_2 acts as charge conjugation implying

A. Morales, C. E. Aalseth, F. T. Avignone, R. L. Brodzinski

One IGEX 76Ge double-beta decay detector is currently operating in the Canfranc Underground Laboratory in a search for dark matter WIMPs, through the Ge nuclear recoil produced by the WIMP elastic scattering. A new exclusion plot, has been derived for WIMP-nucleon spin-independent interactions. To obtain this result, 40 days of data from the IGEX detector (e

Nidal Chamoun, Chao-Shang Huang, Chun Liu, Xiao-Hong Wu

We consider SUSY SO(10) models in which SUSY breaking occurs via an F-term which does not transform as an SO(10) singlet. This results in non-universal GUT-scale gaugino masses leading to a different pattern of sparticle masses from what is expected in the minimal supergravity model (mSUGRA). We study three breaking chains of SO(10) down to the standard mode

K. Golec-Biernat, L. Motyka, A. M. Stasto

The BFKL pomeron in perturbative QCD is plagued by the lack of unitarity and diffusion into the infra-red region of gluon virtualities. These two problems are intimately related. We perform numerical studies of the evolution equation proposed by Balitsky and Kovchegov which unitarizes the BFKL pomeron. We show how diffusion into the infra-red region is suppr

M. I. Krivoruchenko, B. V. Martemyanov, Amand Faessler, C. Fuchs

Relativistic, kinematically complete phenomenological expressions for the dilepton decay rates of nucleon resonances with arbitrary spin and parity are derived in terms of the magnetic, electric, and Coulomb transition form factors. The dilepton decay rates of the nucleon resonances with masses below 2 GeV are estimated using the extended vector meson domina

S. Moch, J. A. M. Vermaseren, A. Vogt

The next-to-next-to-leading order (NNLO) corrections in massless perturbative QCD are derived for the parton distributions of the photon and the deep inelastic structure functions F_1^gamma and F_2^gamma. We present the full photonic coefficient functions at order alpha alpha_s and calculate the first six even-integer moments of the corresponding O(alpha alp

D. A. Ryzhikh, K. A. Ter-Martirosyan

Oscillations of the Dirac neutrinos of three generations in vacuum are considered with allowance made for the effect of the CP-violating leptonic phase (analogue of the quark CP phase) in the lepton mixing matrix. The general formulas for the probabilities of neutrino transition from one sort to another in oscillations are obtained as functions of three mixi

Nikolay M. Nikolov, Yassen S. Stanev, Ivan T. Todorov

Recently established rationality of correlation functions in a globally conformal invariant quantum field theory satisfying Wightman axioms is used to construct a family of soluble models in 4-dimensional Minkowski space-time. We consider in detail a model of a neutral scalar field $ϕ$ of dimension 2. It depends on a positive real parameter c, an analogue of

Riazuddin

The role of gauge invariance in calculating B -> V gamma radiative weak decays is clarified. It is shown that the gauge invariance severely restricts the contributions mediated by the usual weak non-leptonic Hamiltonian dominated by u and c quaks with one photon attachment. Such contributions are found to be almost negligible.

Frederic Zagury

For directions of sufficcient reddening (E(B-V) >~ 0.25), there is a simple relation between the slope of the extinction curve in the far-UV and E(B-V). Regardless of direction, the far-UV extinction curve is proportional to 1/lambda^n exp(-2e(B-V)/lambda) (lambda in micron, n = 4), in accordance with the idea that reddened stars spectra are contaminated by

Elisabeth Kraus

Supersymmetric Yang-Mills-theories with local gauge coupling have a new type of anomalous breaking, which appears as a breaking of supersymmetry in the Wess-Zumino-gauge. The anomalous breaking generates the two-loop order of the gauge $β$-function in terms of the one-loop $β$-function and the anomaly coefficient. We determine the anomaly coefficient in the

Xinwu Cao, D. R. Jiang

We explore the relation between the linear length of radio core and the central black hole mass for a sample of radio-loud active galactic nuclei (AGNs). An empirical relation between the size of the broad line region (BLR) and optical luminosity is used to estimate the size of the BLR. The black hole mass is derived from $\rm H_β$ line width and the radius

John D. Stack, William W. Tucker, Roy J. Wensley

We report on calculations of the heavy quark potential in SU(3) lattice gauge theory. Full SU(3) results are compared to three cases which involve gauge-fixing and projection. All of these start from the maximal abelian gauge (MAG), in its simplest form. The first case is abelian projection to U(1)xU(1). The second keeps only the abelian fields of monopoles

Claudio Altafini

The controllability property of the unitary propagator of an N-level quantum mechanical system subject to a single control field is described using the structure theory of semisimple Lie algebras. Sufficient conditions are provided for the vector fields in a generic configuration as well as in a few degenerate cases.

Wieslaw Leonski, Adam Miranowicz

In the second part of our review (for the first part see quant-ph/0108080), we discuss a physical model for generation of "truncated" coherent and squeezed states in finite-dimensional Hibert spaces.

Iwo Bialynicki-Birula, Zofia Bialynicka-Birula

We extend our previous analysis of the motion of vortex lines [I. Bialynicki-Birula, Z. Bialynicka-Birula and C. Sliwa, Phys. Rev. A 61, 032110 (2000)] from linear to a nonlinear Schroedinger equation with harmonic forces. We also argue that under certain conditions the influence of the contact nonlinearity on the motion of vortex lines is negligible. The pr

Mark S. Byrd, Daniel A. Lidar

Strong, fast pulses, called ``bang-bang'' controls can be used to eliminate the effects of system-environment interactions. This method for preventing errors in quantum information processors is treated here in a geometric setting which leads to an intuitive perspective. Using this geometric description, we clarify the notion of group symmetrization

Alberto Castro, M. A. L. Marques, Julio A. Alonso, George F. Bertsch

The optical response of the lowest energy members of the C20 family is calculated using time-dependent density functional theory within a real-space, real-time scheme. Significant differences are found among the spectra of the different isomers, and thus we propose optical spectroscopy as a tool for experimental investigation of the structure of these import

Alexander Volya

The interplay of pairing and other interactions is addressed in this work using a simple single-j model. We show that enhancements in pairing correlations observed through studies of the spectra of deformed systems, moments of inertia, changes in transitional multipole amplitudes, and direct calculations of the pairing component in the wave function, indicat

K. Hagino, M. Dasgupta, I. I. Gontchar, D. J. Hinde

Recent high precision experimental data for heavy-ion fusion cross sections at energies in the vicinity of the Coulomb barrier systematically show that a strikingly large surface diffuseness parameter for a Woods-Saxon potential is required in order to fit the data. We discuss possible origins for this anomaly, including the effects of dissipation and the se

C. Ciofi degli Atti, L. P. Kaptari

The two nucleon emission process from ^3He, ^3He(e,e'N_2N_3)N_1, has been theoretically analyzed using realistic three-nucleon wave functions and taking the final state interaction into account. Various kinematical conditions have been considered in order to clarify the question whether the effects of the final state interaction could be minimized by a p

G. A. Souliotis, W. Loveland, K. Hanold, G. J. Wozniak

The yields and velocity distributions of heavy residues and fission fragments from the reaction of 20 MeV/nucleon 197Au + 90Zr have been measured using the MSU A1200 fragment separator. A bimodal distribution of residues is observed, with one group, resulting from peripheral collisions, having fragment mass numbers A=160-200, while the other group, resulting

Prot Pakonski, Jakub Zakrzewski

Dynamics of hydrogen atom driven by microwave field of arbitrary polarization is approximated by the discrete mapping. The map describes the change of dynamical variables from an aphelion or a perihelion to the next one. The results are compared with numerical simulation and previous approximations.

Wenfeng Gao, Ján Mináč

A Galois field extension $E/F$ whose Galois group is a pro-2-group of an exponent of at most 8, with a nilpotency class of at most 4, is determined, such that it contains essential information about the Witt rings of all quadratic extensions of $F$.

Louis Mahé, Ján Mináč, Tara L. Smith

One of the fundamental questions in current field theory, related to Grothendieck's conjecture of birational anabelian geometry, is the investigation of the precise relationship between the Galois theory of fields and the structure of the fields themselves. In this paper we initiate the classification of additive properties of multiplicative subgroups of

M. Adler, P. van Moerbeke

In testing the independence of two Gaussian populations, one computes the distribution of the sample canonical correlation coefficients, given that the actual correlation is zero. The "Laplace transform" of this distribution is not only an integral over the Grassmannian of p-dimensional planes in complex n-space, but is also related to a generalized

O. S. M. Alves, F. P. Machado, S. Yu. Popov, K. Ravishankar

We prove a shape theorem for a growing set of simple random walks on Z^d, known as frog model. The dynamics of this process is described as follows: There are active particles, which perform independent discrete time SRWs, and sleeping particles, which do not move. When a sleeping particle is hit by an active particle, the former becomes active as well. Init

Dmitry N. Kozlov

In this paper we represent the Vassiliev model for the homotopy type of the one-point compactification of subspace arrangements as a homotopy colimit of an appropriate diagram over the nerve complex of the intersection semilattice of the arrangement. Furthermore, using a generalization of simplicial collapses to diagrams of topological spaces over simplicial

Dimitrios I. Dais

This paper surveys, in the first place, some basic facts from the classification theory of normal complex singularities, including details for the low dimensions 2 and 3. Next, it describes how the toric singularities are located within the class of rational singularities, and recalls their main properties. Finally, it focuses, in particular, on a toric vers

Dimitrios I. Dais

A necessary condition for the existence of torus-equivariant crepant resolutions of Gorenstein toric singularities can be derived by making use of a variant of the classical Upper Bound Theorem which is valid for simplicial balls.

Mikhail Kudryavtsev

The Jacobi matrices with bounded elements whose spectrum of multiplicity 2 is separated from its simple spectrum and contains an interval of absolutely continuous spectrum are considered. A new type of spectral data, which are analogous for scattering data, is introduced for this matrix. An integral equation that allows us to reconstruct the matrix from this

O. Arratia, M. A. del Olmo

We present a method to construct induced representations of quantum algebras having the structure of bicrossproduct. We apply this procedure to some quantum kinematical algebras in (1+1)--dimensions with this kind of structure: null-plane quantum Poincare algebra, non-standard quantum Galilei algebra and quantum kappa Galilei algebra.

Hartmut Fuehr

In the first part of the paper a general notion of sampling expansions for locally compact groups is introduced, and its close relationship to the discretisation problem for generalised wavelet transforms is established. In the second part, attention is focussed on the simply connected nilpotent Heisenberg group $\HH$. We derive criteria for the existence of

Carlos Simpson

Let $L_n$ denote the Dwyer-Kan localization of the category of weak n-categories divided by the n-equivalences. We propose a list of properties that this simplicial category is likely to have, and conjecture that these properties characterize $L_n$ up to equivalence. We show, using these properties, how to obtain the morphism $n-1$-categories between two poi

Peter M. Makienko

Let R be rational map. Critical point c is called summable if series $\sum_i\frac{1}{(R^i)'(R(c))}$ is absolutely convergent. Under some topological condition on postcritical set we prove that R can not be structurally stable if summable critical point $c \in J(R)$.

N. F. Benschop

Primitive roots of 1 mod p^k (k>2 and odd prime p) are sought, in cyclic units group G_k = A_k B_k mod p^k, coprime to p, of order (p-1)p^{k-1}. 'Core' subgroup A_k has order p-1 independent of k, and p+1 generates 'extension' subgroup B_k of all p^{k-1} residues 1 mod p. Divisors r,t of powerful generator p-1=rs=tu of \pm B_k mod p^k, and of

Dimitrios I. Dais, Marko Roczen

The string-theoretic E-functions E_{str}(X;u,v) of normal complex varieties X having at most log-terminal singularities are defined by means of snc-resolutions. We give a direct computation of them in the case in which X is the underlying space of the 3-dimensional A-D-E singularities by making use of a canonical resolution process. Moreover, we compute the

F. R. Klinkhamer, Y. J. Lee

Real-time anomalous fermion number violation has been investigated for massless chiral fermions in spherically symmetric SU(2) Yang-Mills gauge field backgrounds which can be weakly dissipative or even nondissipative. Restricting consideration to spherically symmetric fermion fields, a relation has been found between the spectral flow of the Dirac Hamiltonia

Pavel Kolar, Jan Fischer

Various forms of derivative dispersion relations, in which the dispersion integral is replaced by a series of derivatives of the imaginary part of a scattering amplitude, are reviewed. Conditions of their validity and practical applicability as well as their relevance to high-energy small-angle hadron-hadron scattering are discussed.