August 2000 arXiv papers — page 19

B. Bagchi, C. Quesne

The powerful group theoretical formalism of potential algebras is extended to non-Hermitian Hamiltonians with real eigenvalues by complexifying so(2,1), thereby getting the complex algebra sl(2,\C) or $A_1$. This leads to new types of both PT-symmetric and non-PT-symmetric Hamiltonians.

M. Herrera, S. A. Hojman

Examples of non-standard construction of Hamiltonian structures for dynamical systems and the respective Hamilton-Jacobi (H-J) equations, without using Lagrangians, are presented. Alternative H-J equations for Euler top are explicitly exhibited and solved. We demonstrate that some stability criterion, relating the slope of a Casimir function parametrized by

D. Gurevich, P. Saponov

As was shown in \cite{GPS} the matrix $L=|| l_i^j||$ whose entries $l_i^j$ are generators of the so-called reflection equation algebra is subject to some polynomial identity looking like the Cayley-Hamilton identity for a numerical matrix. Here a similar statement is presented for a matrix whose entries are generators of a filtered algebra being a "non-c

Walter D. Neumann, Paul Norbury

We classify two-variable polynomials which are rational of simple type. These are precisely the two-variable polynomials with trivial homological monodromy.

Eric M. Rains

In [earlier work by the author], it was shown that if U is a random n x n unitary matrix, then for any p>=n, the eigenvalues of U^p are i.i.d. uniform; similar results were also shown for general compact Lie groups. We study what happens when p<n instead. For the classical groups, we find that we can describe the eigenvalue distribution of U^p in terms of th

Vahagn H. Mikaelian

In this paper we establish some subnormal embeddings of groups into groups with additional properties; in particular embeddings of countable groups into 2-generated groups with some extra properties. The results obtained are generalizations of theorems of P. Hall, R. Dark, B. Neumann, Hanna Neumann, G. Higman on embeddings of that type. Considering subnormal

Bert van Geemen

To a Hodge structure V of weight k with CM by a field K we associate Hodge structures V_{-n/2} of weight k+n for n positive and, under certain circumstances, also for n negative. We show that these `half twists&#39; come up naturally in the Kuga-Satake varieties of weight two Hodge structures with CM by an imaginary quadratic field.

Naoko Kamada

The notion of chckerboard colorability for virtual links and abstract links is introduced. We study the Jones polynomials of virtual links and abstruct links. It is proved that a certain property of the Jones polynomials of classical links is valid for virtual links which admit checkerboard colorings.

Jaya N. Iyer

We show birationality of the morphism associated to line bundles $L$ of type $(1,...,1,2,...,2,4,...,4)$ on a generic $g-$dimensional abelian variety into its complete linear system such that $h^0(L)=2^g$. When $g=3$, we describe the image of the abelian threefold and from the geometry of the moduli space $SU_C(2)$ in the linear system $|2θ_C|$, we obtain an

Vassily Gorbounov, Fyodor Malikov, Vadim Schechtman

Results of our previous note, &#34;Gerbes of chiral differential operators&#34; (Math. Res. Letters, 7(2000), 55-66), are discussed in the algebraic category.

Ezra Getzler

We prove a Darboux theorem for formal deformations of Hamiltonian operators of hydrodynamic type (Dubrovin-Novikov). Not all deformations are equivalent to the original operator: there is a moduli 2-stack of normal forms. The paper utilizes three main concepts: 1) dg Lie algebras concentrated in degrees [-1,\infty) such as the Schouten algebra - these give a

D. Toublan, J. J. M. Verbaarschot

In this lecture we discuss some exact results for the low-lying spectrum of the Dirac operator in adjoint QCD. In particular, we find an analytical expression for the slope of the average spectral density. These results are obtained by means of a generating function which is an extension of the QCD partition function with fermionic and bosonic ghost quarks.

Herman Boos, Vladimir Mangazeev

In this paper we continue the study of the three-layer Zamolodchikov model started in our previous works. We analyse numerically the solutions to the Bethe ansatz equations. We consider two regimes I and II which differ by the signs of the spherical sides (a1,a2,a3)->(-a1,-a2,-a3). We accept the two-line hypothesis for the regime I and the one-line hypothesi

Mariano Cadoni, Marco Cavaglia&#39;

We present a detailed discussion of the duality between dilaton gravity on AdS_2 and open strings. The correspondence between the two theories is established using their symmetries and field theoretical, thermodynamic, and statistical arguments. We use the dual conformal field theory to describe two-dimensional black holes. In particular, all the semiclassic

Z. Chacko, Markus A. Luty

We point out that in supersymmetric theories with extra dimensions, radius stabilization can give rise to a VEV for the $F$ component of the radius modulus. This gives an important contribution to supersymmetry breaking of fields that propagate in the bulk. A particularly attractive class of models is obtained if the standard-model gauge fields propagate in

A. H. Hoang

The effects of the finite charm quark mass on bottom quark mass determinations from $Υ$ sum rules are examined in detail. The charm quark mass effects are calculated at next-to-next-to-leading order in the non-relativistic power counting for the $Υ$ sum rules and at order $α_s^3$ for the determination of the bottom MSbar mass. For the bottom 1S mass, which i

A. H. Hoang

Recent developments for an effective theory for non-relativistic perturbative quark-antiquark systems are reviewed and some applications are discussed.

M. Boz, N. K. Pak

Taking the most general two-doublet models with explicit CP violation in the Higgs sector but no phase in the CKM matrix, we determine the correlation between the Higgs and Kaon sectors using the experimental values of $ΔM_K$ and $ε_K$. It is found that: there is a direct correlation between strength of FCNC couplings and the Higgs masses, and the lightest H

Kirill Melnikov, Alexander Yelkhovsky

We compute O(alpha^3 ln alpha) corrections to the decay rates of para- and orthopositronium into two and three photons, respectively. For this calculation we employ the nonrelativistic QED regularized dimensionally and we explain how in this framework the logarithms of the fine structure constant can be extracted.

Ana Achúcarro

These lectures start with an elementary introduction to the subject of magnetic monopoles which should be accesible from any physics background. In the Weinberg-Salam model of electroweak interactions, magnetic monopoles appear at the ends of a type of non-topological vortices called electroweak strings. These will also be discussed, as well as recent simula

Johannes Blümlein, Alexandre Kryukov

The possibilities to pair-produce leptoquarks in photon-photon collisions are discussed. QCD threshold corrections lead to a strong enhancement of the production cross section. Suitably long-lived leptoquarks ($Γ_Φ\lsim 100 \MeV$) may form Leptoquarkonium states.

V. E. Markushin

The structure of the light scalar mesons is elucidated by the investigation of the S-matrix poles and the q-qbar spectral density in a coupled channel model that includes pi-pi, K-Kbar and q-qbar channels. It is shown that the dynamical origin of the sigma and f0(980) mesons is consistent with the observed spectrum of the scalar states. The K-Kbar molecular

Morimitsu Tanimoto

We have studied the large mixing angle MSW solution for the solar neutrinos in the non-abelian flavor symmetry. We predict the MNS mixing matrix taking account of the symmetry breakings.

T. L. Yoon, R. Foot

We examine one simple mechanism which leads to approximate maximal $ν_μ- ν_τ$ oscillations in the standard see-saw model. In particular, we show that this scheme could be implemented in the Exact Parity Model (also known as the mirror matter model). Within this framework the solar neutrino problem is solved by maximal $ν_e \to ν&#39;_e$ oscillations (with $ν

Arnold Reusken

This paper is concerned with the problem of approximating the determinant of A for a large sparse symmetric positive definite matrix A. It is shown that an efficient solution of this problem is obtained by using a sparse approximate inverse of A. The method is explained and theoretical properties are discussed. A posteriori error estimation techniques are pr

WA98 Collaboration, M. M. Aggarwal

Three-particle correlations have been measured for identified negative pions from central 158 A GeV Pb+Pb collisions by the WA98 experiment at CERN. A substantial contribution of the genuine three-body correlation has been found as expected for a mainly chaotic and symmetric source.

I. Dan Melamed, Philip Resnik

We present methods for evaluating human and automatic taggers that extend current practice in three ways. First, we show how to evaluate taggers that assign multiple tags to each test instance, even if they do not assign probabilities. Second, we show how to accommodate a common property of manually constructed ``gold standards&#39;&#39; that are typically u

Rava da Silveira, Sahraoui Chaieb, L. Mahadevan

When a bubble of air rises to the top of a highly viscous liquid, it forms a dome-shaped protuberance on the free surface. Unlike a soap bubble, it bursts so slowly as to collapse under its own weight simultaneously, and folds into a striking wavy structure. This rippling effect occurs in fact for both elastic and viscous sheets, and a theory for its onset i

Rava da Silveira

The rupture of a medium under stress typifies breakdown phenomena. More generally, the latter encompass the dynamics of systems of many interacting elements governed by the interplay of a driving force with a pinning disorder, resulting in a macroscopic transition. A simple mean-field formalism incorporating these features is presented and applied to systems

Xiao-jun Li, Hao-wen Xi, J. D. Gunton

We present a phenomenological theory for phase turbulence (PT) in Rayleigh-Bénard convection, based on the generalized Swift-Hohenberg model. We apply a Hartree-Fock approximation to PT and conjecture a scaling form for the structure factor $S(k)$ with respect to the correlation length $ξ_2$. We hence obtain {\it analytical} results for the time-averaged con

J. -F. Palierne

The transient network literature up to now has considered that the connection probability of a free strand does not depend on the strand extension, in contrast with the disconnection probability. We argue that, on thermodynamic grounds, both probabilities must have the same dependence on the strand extension. We propose a model for the pinning/snapping of el

Aiman Al-Omari, A. H. Nayyar

The heat capacity of some ferrimagnets has additional structures like a shoulder in the Schottky-like peak, or emergence of a second peak when an external magnetic field is applied. It is shown here that as long as spin wave-spin wave interactions are ignored in a ferrimagnet, the ferromagnetic and antiferromagnetic elementary excitation spectra give rise to

Chun-Min Chang, A. H. Castro Neto, A. R. Bishop

Positions of protons in DNA hydrogen bonds are fundamental for the fidelity of the replication process. Because the hydrogen bond is partially covalent the electronic structure of DNA plays an important role in the replication process. Current studies of electron transfer in DNA have shown that simple pictures based on independent electron physics are not su

Aiman Al-Omari, A. H. Nayyar

Within the zero-temperature linear spin-wave theory we have investigated the effect of frustration and dimerization of a Heisenberg system with alternating spins $s_{1}$ and $s_{2}$ on one- and two-dimensional lattices. The combined effect most visibly appears in the elementary excitation spectra. In contrast to the ground state energy that decreases with di

S. Mandal, R. Dasgupta

A model for diffusion on a cubic lattice with a random distribution of traps is developed. The traps are redistributed at certain time intervals. Such models are useful for describing systems showing dynamic disorder, such as ion-conducting polymers. In the present model the traps are infinite, unlike an earlier version with finite traps, this model has a pe

Arnaud Buhot, Mirta B. Gordon

The storage capacity of an incremental learning algorithm for the parity machine, the Tilinglike Learning Algorithm, is analytically determined in the limit of a large number of hidden perceptrons. Different learning rules for the simple perceptron are investigated. The usual Gardner-Derrida one leads to a storage capacity close to the upper bound, which is

Alexander I. Olemskoi, Ivan Krakovsky

We represent a theory of polymer gelation as an analogue of liquid-glass transition in which elastic fields of stress and strain shear components appear spontaneously as a consequence of the cross-linking of macromolecules. This circumstance is explained on the basis of obvious combinatoric arguments as well as a synergetic Lorenz system, where the strain ac

L. Bellon, S. Ciliberto, C. Laroche

The relationship between the conductivity and the polarization noise is measured in a gel as a function of frequency in the range $1Hz - 40Hz$. It is found that at the beginning of the transition from a fluid like sol to a solid like gel the fluctuation dissipation theorem is strongly violated. The amplitude and the persistence time of this violation are dec

H. H. Aragao-Rego, J. E. de Freitas, Liacir S. Lucena, G. M. Viswanathan

We find that 2-dimensional (2-D) critical branched polymers with no impurities conclusively belong to the same universality class as 2-D random percolation clusters, although pure critical 3-D branched polymers do not belong to the 3-D percolation universality class. We find, moreover, that the fractal dimension of critical branched polymers in 2-D is indepe

Michiel R. Hogerheijde, Floris F. S. van der Tak

We present a numerical method and computer code to calculate the radiative transfer and excitation of molecular lines. Formulating the Monte Carlo method from the viewpoint of cells rather than photons allows us to separate local and external contributions to the radiation field. This separation is critical to accurate and fast performance at high optical de

Gary D. Schmidt, Paul S. Smith

A tendency for the axes of double-lobed radio quasars to be aligned with the electric vectors of optical polarization in the active galactic nuclei is well-known. However, the origin of the polarization and reason behind its correlation with radio morphology is not yet established. From accurate spectropolarimetry of 7 quasars which show this alignment effec

C. M. Clement, J. Rowe

CCD observations obtained by the OGLE team for 128 RR Lyrae variables in Omega Cen have been analysed. The P-L and P-A plots indicate that, in addition to fundamental (RRab) and first overtone (RRc) pulsators, the Omega Cen RR Lyrae population seems to include second overtone (RRe) and possibly third overtone pulsators. The mean periods derived for the RRab

N. A. Walton, S. J. Smartt

An expert panel initiated discussion on a number of key questions facing the role of 4-m and small telescopes in the new era of 8-m telescopes. The panel and audience agreed that the 4-m class telescope role would necessarily evolve, but would still be important in the coming years. The need for an active development programme of competitive instrumentation

Susanna Steindling, Noah Brosch, Karl Rakos

We use rest-frame Stromgren photometry to observe clusters of galaxies in a self-consistent manner from z=0 to z=0.8. Stromgren photometry of galaxies is an efficient compromise between standard broad-band photometry and spectroscopy, in the sense that it is more sensitive to subtle variations in spectral energy distributions than the former, yet much less t

David Langlois

The purpose of these notes is to give a brief review of superfluidity in neutron stars. After a short presentation explaining why and how superfluidity is expected in the crust and core of neutron stars, consequences on thermal evolution and rotational dynamics are discussed. The second part summarizes a formalism that has been recently developped to describ

Ian Smail, Harald Kuntschner, T. Kodama, G. P. Smith

We present deep optical and near-infrared imaging of the rich cluster A2218 at z=0.17. Our optical imaging comes from new multicolour Hubble Space Telescope WFPC2 observations in the F450W (B), F606W (V) and F814W (I) passbands. These observations are complemented by deep near-infrared, Ks-band, imaging from the new INGRID imager on the 4.2-m William Hersche

M. Amenomori, S. Ayabe, Caidong

We have shown that the Sun&#39;s shadow by high energy cosmic rays moves year by year and its behavior is correlated with a time variation of the large-scale structure of the solar and interplanetary magnetic fields. The solar activity was near minimum in the period from 1996 through 1997. Using the data obtained with the Tibet air shower array, we examined

Geraint F. Lewis, Rodrigo A. Ibata, J. Stuart B. Wyithe

If cluster dark matter is in the form of compact objects it will introduce fluctuations into the light curves of distant sources. Current searches for MACHOs in clusters of galaxies focus on monitoring quasars behind nearby systems. This paper considers the effect of such a compact population on the surface brightness distribution of giant gravitationally le

E. Daddi, A. Cimatti, L. Pozzetti, H. Hoekstra

We present the results of a wide-field survey for extremely red objects (EROs hereafter), the widest so far, based on Ks and R band imaging. The survey covers 701 arcmin^2 and it is 85% complete to Ks\leq18.8 over the whole area and to Ks\leq19.2 over 447.5 arcmin^2. Thanks to the wide field covered, a complete sample of about 400 EROs with R-Ks\geq5 was sel

David Garfinkle

We find an exact solution in closed form for the critical collapse of a scalar field with cosmological constant in 2+1 dimensions. This solution agrees with the numerical simulation done by Pretorius and Choptuik of this system.

Jian-Xin Zhu, C. S. Ting

The Kondo effects of an Anderson impurity embedded into a d-wave superconductor is studied. Within the slave-boson mean-field approach, the derived Bogoliubov-de Gennes equations are solved via exact diagonalization. We show that a critical coupling strength, above which the Kondo effect takes place, exists regardless of whether the band particle-hole symmet

David Atwood, Isard Dunietz, Amarjit Soni

Various methods are discussed for obtaining the CKM angle gamma through the interference of the charged B-meson decay channels B- -> K- D0 and B- -> K- D0-bar where the D0 and D0-bar decay to common final states. It is found that choosing final states which are not CP eigenstates can lead to large direct CP violation which can give significant bounds on gamm

Daniel Gottesman, John Preskill

We prove the security of a quantum key distribution scheme based on transmission of squeezed quantum states of a harmonic oscillator. Our proof employs quantum error-correcting codes that encode a finite-dimensional quantum system in the infinite-dimensional Hilbert space of an oscillator, and protect against errors that shift the canonical variables p and q

Nick Evans, Clifford V. Johnson, Michela Petrini

We study the family of ten dimensional type IIB supergravity solutions corresponding to renormalisation group flows from N=4 to N=2 supersymmetric Yang-Mills theory. Part of the solution set corresponds to a submanifold of the Coulomb branch of the gauge theory, and we use a D3-brane probe to uncover details of this physics. At generic places where supergrav

Elena Gubankova, Chueng-Ryong Ji, Stephen R. Cotanch

The flow-equation method of continuous unitary transformations is used to eliminate the minimal quark-gluon interaction in the light-front quantized QCD Hamiltonian. The coupled differential equations in the two lowest Fock sectors correspond to the renormalization of the light-front gluon mass and the generation of an effective quark-antiquark (as well as g

Anupam Mazumdar

The brane cosmology has invoked new challenges to the usual Big Bang cosmology. In this paper we present a brief account on thermal history of the post-inflationary brane cosmology. We have realized that it is not obvious that the post-inflationary brane cosmology would always deviate from the standard Big Bang cosmology. However, if it deviates some stringe

J. Greensite, P. Olesen

We use the finite temperature AdS/CFT approach to demonstrate logarithmic broadening of the confining QCD3 flux tube as a function of quark separation. This behavior indicates that, unlike lattice QCD, there is no roughening transition in the AdS/CFT formulation, which raises the interesting possibility of extrapolating strong coupling results to weak coupli

J. Dias de Deus, R. Ugoccioni

We analyse recent results on charged particle pseudo-rapidity densities from RHIC in the framework of the Dual String Model, in particular when including string fusion. The model, in a simple way, agrees with all the existing data and is consistent with the presence of the percolation transition to the Quark-Gluon Plasma already at the CERN-SPS.

John A. Gowan

A transformation mechanism is proposed for the &#34;W&#34; weak force IVB particle. The W is a dense &#34;metric&#34; boson which catalyzes transformations by combining reactants with virtual particle-antiparticle pairs created from the virtual vacuum particle-antiparticle &#34;sea&#34;. &#34;W&#34; and &#34;Z&#34; IVB mass functions to recreate the original

A. Deandrea, A. D. Polosa

We point out that a new contribution to B decays to three pions is relevant in explaining recent data from the CLEO and BABAR collaborations, in particular the results on quasi-two-body decays via a rho meson. We also discuss the relevance of these contribution to the measurement of CP violations.

R. A. Schneider, W. Weise

A fireball model with time evolution based on transport calculations is used to examine the dilepton emission rate of an ultra-relativistic heavy-ion collision. We assume a transition from hadronic matter to a quark-gluon plasma at a critical temperature T_C between 130-170 MeV. We include thermal corrections to the hadronic spectra below T_C and use perturb

George Jaroszkiewicz

We discuss the emergence of time dilation as a normal feature expected of any system where a central processor may have to wait one or more clock cycles before concluding a local calculation. We show how the process of causal implication in a typical Newtonian cellular automaton leads naturally to Lorentz transformations and invariant causal structure.

Joseph C. Weingartner, B. T. Draine

We construct size distributions for carbonaceous and silicate grain populations in different regions of the Milky Way, LMC, and SMC. The size distributions include sufficient very small carbonaceous grains (including polycyclic aromatic hydrocarbon molecules) to account for the observed infrared and microwave emission from the diffuse interstellar medium. Ou

Seif Randjbar-Daemi, Mikhail Shaposhnikov

We study localization of bulk fermions on a brane with inclusion of Yang-Mills and scalar backgrounds in higher dimensions and give the conditions under which localized chiral fermions can be obtained.

Tadayuki Kodama, Ian Smail

Hubble Space Telescope observations of distant clusters have suggested a steep increase in the proportion of S0 galaxies between clusters at high redshifts and similar systems the present-day. It has been proposed that this increase results from the transformation of the morphologies of accreted field galaxies from spirals to S0s. We have simulated the evolu

A. D. Martin, J. Outhwaite, M. G. Ryskin

We use the available data on e+ e- -> hadrons to determine the value of the QED coupling at the Z pole. The inclusion of recent preliminary BES-II data in the analysis is found to reduce the ambiguity in the determination of the coupling, particularly that arising from the use of either exclusive or inclusive data in the energy region \sqrt{s} < 2 GeV, in fa

Jan-e Alam, Sourav Sarkar, T. Hatsuda, Tapan K. Nayak

High energy photon emission rate from matter created in Pb + Pb collisions at CERN SPS energies is evaluated. The evolution of matter from the initial state up to freeze-out has been treated within the framework of (3+1) dimensional hydrodynamic expansion. We observe that the photon spectra measured by the WA98 experiment are well reproduced with hard QCD ph

A. I. Karanikas, C. N. Ktorides

Polyakov&#39;s spin factor enters as a weight in the path-integral description of particle-like modes propagating in Euclidean space-times, accounting for particle spin. The Fock-Feynman-Schwinger path integral applied to QCD accomodates Polyakov&#39;s spin factor in a natural manner while, at the same time, it identifies Wilson line (loop) operators as sole

P. Dubos, H. Courtois, B. Pannetier, F. K. Wilhelm

We carry out an extensive experimental and theoretical study of the Josephson effect in S-N-S junctions made of a diffusive normal metal (N) embedded between two superconducting electrodes (S). Our experiments are performed on Nb-Cu-Nb junctions with highly-transparent interfaces. We give the predictions of the quasiclassical theory in various regimes on a p

Jounghun Lee, Ue-Li Pen

We present a theoretical study of galaxy spin correlation statistics, with detailed technical derivations. We also find an expression for the spin-density cross-correlation, and apply that to the Tully galaxy catalog. The observational results appear qualitatively consistent with the theoretical predictions, yet the error bars are still large. However, we ex

Michael Murray

NA44 has measured mid-rapidity deuteron spectra from AA collisions at sqrt{s}=18GeV/A at the CERN SPS. Combining these spectra with published proton, antiproton and antideuteron data allows us to calculate, within a coalescence framework, proton and antiproton source sizes and phase space densities. These results are compared to pion source sizes and densiti

D. G. Enzer, M. M. Schauer, J. J. Gomez, M. S. Gulley

We report an experimental confirmation of the power-law relationship between the critical anisotropy parameter and ion number for the linear-to-zigzag phase transition in an ionic crystal. Our experiment uses laser cooled calcium ions confined in a linear radio-frequency trap. Measurements for up to 10 ions are in good agreement with theoretical and numeric

Anatoly Spitkovsky, Pisin Chen

The physics of energy transfer between the laser and the plasma in laser wakefield accelerators is studied. We find that wake excitation by arbitrary laser shapes can be parameterized using the total pulse energy and pulse depletion length. A technique for determining laser profiles that produce the required plasma excitation is developed. We show that by pr

Anatoly Spitkovsky, Pisin Chen

We study the energetics of wake excitation during the laser-plasma interaction in application to laser wakefield accelerators. We find that both the wake amplitude and the accelerating efficiency (transformer ratio) can be maximized by properly shaping the longitudinal profile of the driving laser pulse. The corresponding family of laser pulse shapes is deri

Boris I. Bondarev, Alexander P. Durkin

Experts in different accelerator laboratories accumulated wide experience in RFQ designing. Nevertheless new tasks on high-power, high-energy CW linac designing (for example, for ADT applications) were appeared recently. Such accelerators must be practically free of beam losses. This main condition placed more stringent requirements upon beam quality at the

Boris Bondarev, Alexander Durkin, Stanislav Vinogradov, Igor Shumakov

Proton linear accelerator is the base Accelerator Driven Power System (ADS). Such ADS are dedicated to various purposes: weapon plutonium conversion, &#34;energy amplifier&#34;, transmutation of radionuclear wastes etc. Solution of these tasks requires proton beams with energy 1 GeV and average current up to 30 mA. At the moment there are no problems of fund

A. K. Popov, S. A. Myslivets, Thomas F. George

Resonant nonlinear-optical interference processes in four-level Doppler-broadened media are studied. Specific features of amplification and optical switching of short-wavelength radiation in a strongly-absorbing resonant gas under coherent quantum control with two longer wavelength radiations, are investigated. The major outcomes are illustrated with virtual

H. Lenske, C. M. Keil, F. Hofmann, S. Briganti

The density dependent relativistic hadron (DDRH) theory is introduced as an effective field theory for nuclei and hypernuclei. A Dirac-Brueckner approach to in-medium nucleon-hyperon interactions is presented. Density dependent meson-baryon vertices are determined from DBHF self-energies in infinite matter. Scaling laws for hyperon vertices are derived from

D. L. Groep, M. F. van Batenburg, Th. S. Bauer, H. P. Blok

Cross sections for the 3He(e,e&#39;pp)n reaction were measured over a wide range of energy and three- momentum transfer. At a momentum transfer q=375 MeV/c, data were taken at transferred energies omega ranging from 170 to 290 MeV. At omega=220 MeV, measurements were performed at three q values (305, 375, and 445 MeV/c). The results are presented as a functi

A. Andronic, G. Stoicea, M. Petrovici, FOPI Collaboration

The incident energy at which the azimuthal distributions in semi-central heavy ion collisions change from in-plane to out-of-plane enhancement, E_tran, is studied as a function of mass of emitted particles, their transverse momentum and centrality for Au+Au collisions. The analysis is performed in a reference frame rotated with the sidewards flow angle, Thet

P. M. Lushnikov

The dispersion-managed (DM) optical system with step-wise periodical variation of dispersion is studied in the framework of path-averaged Gabitov-Turitsyn equation. The soliton solution is obtained by iterating the path-averaged equation. The dependence of soliton parameters on dispersion map strength is investigated together with the oscillating tails of so

Alain M. Dikande

The discrete static properties of a class of deformable double-well potential models are investigated. The Peierls-stress potential of the models is explicitely given. Numerical analysis of the equation of motion reveal different soliton wavetrain profiles, most of which are periodic. Soliton wavetrains are also found analytically in terms of continuum nonli

P. M. Lushnikov

A breathing soliton-like structure in dispersion-managed (DM) optical fiber system is studied. It is proven that for negative average dispersion the breathing soliton is forbidden provided that a modulus of average dispersion exceed a threshold which depends on the soliton amplitude.

Wieslaw Krolikowski, Elena A. Ostrovskaya, Carsten Weilnau, Matthias Geisser

We report on the first experimental observation of a novel type of optical vector soliton, a {\em dipole-mode soliton}, recently predicted theoretically. We show that these vector solitons can be generated in a photorefractive medium employing two different processes: a phase imprinting, and a symmetry-breaking instability of a vortex-mode vector soliton. Th

D. Gurevich, P. Saponov

Quantum sphere is introduced as a quotient of the so-called Reflection Equation Algebra. This enables us to construct some line bundles on it by means of the Cayley-Hamilton identity whose a quantum version was discovered in \cite{PS}, \cite{GPS}. A new way to introduce some elements of &#34;braided geometry&#34; on the quantum sphere is discussed.

Ken Dykema, Florin Radulescu

A reduction formula for compressions of von Neumann algebras arising as free products is proved. This shows that the fundamental group is all of the positive reals for some such algebras. Additionally, by taking a sort of free product with an unbounded semicircular element, continuous one parameter groups of trace scaling automorphisms on II_infinity factors

Estelle L. Basor, Torsten Ehrhardt

In this paper we establish several relations between the determinants of the following structured matrices: Hankel matrices, symmetric Toeplitz + Hankel matrices and Toeplitz matrices. Using known results for the asymptotic behavior of Toeplitz determinants, these identities are used in order to obtain Fisher-Hartwig type results on the asymptotics of certai

Xiaoping Xu

In this paper, we first present a classification theorem of infinite-dimensional simple Novikov algebras over an algebraically closed field with characteristic 0. Then we classify all the irreducible modules of a certain infinite-dimensional simple Novikov algebras with an idempotent element whose left action is locally finite.

Andrew Ranicki

Browder-Novikov-Sullivan-Wall surgery theory investigates the homotopy types of manifolds, using a combination of algebra and topology. It is the aim of these notes to provide an introduction to the more algebraic aspects of the theory (such as the Wall surgery obstruction groups), without losing sight of the geometric motivation.

Steve Ferry, Andrew Ranicki

Wall&#39;s finiteness obstruction is an algebraic K-theory invariant which decides if a finitely dominated space is homotopy equivalent to a finite CW complex. The object of this survey is to describe the invariant (which was first formulated in 1965) and some of its many applications to the surgery classification of manifolds.

Lev A. Borisov, Anatoly Libgober

This paper surveys the authors recent work on two variable elliptic genus of singular varieties. The last section calculates a generating function for the elliptic genera of symmetric products. This generalizes the classical results of Macdonald and Zagier.

Justin R. Smith

This paper proves that the homotopy type of a pointed, simply-connected, 2-reduced simplicial set is determined by the chain-complex augmented by functorial diagonal and higher diagonal maps (a simple generalization of the ones used to define Steenrod operations). The treatment of this problem is completely self-contained, and includes material that simplifi

Go Yamamoto

The algebraic structure on the subspace of the quasi-primary vectors given by the projection of the (n) products of a conformal superalgebra is formulated. As an application the complete list of simple physical conformal superalgebras is given. The list contains a one-parameter family of superconformal algebras with 4 supercharges that is simple for general

Soonkeon Nam

We compute the one loop Casimir energy of an interacting scalar field in a compact noncommutative space of $R^{1,d}\times T^2_\theta$, where we have ordinary flat $1+d$ dimensional Minkowski space and two dimensional noncommuative torus. We find that next order correction due to the noncommutativity still contributes an attractive force and thus will have a

A. Schwimmer, S. Theisen

Using the Weyl transfomations induced by diffeomorphisms we set up a cohomological problem for the Fefferman-Graham coefficients. The cohomologically nontrivial solutions remove the ambiguity and give the nonlocal terms in the effective action responsible for the trace anomalies.

Pushan Majumdar, H. S. Sharatchandra

An explicit canonical transformation is constructed to relate the physical subspace of Yang-Mills theory to the phase space of the ADM variables of general relativity. This maps 3+1 dimensional Yang-Mills theory to local evolution of metrics on 3 manifolds.

Alex Buchel, Amanda W. Peet, Joseph Polchinski

We investigate some properties of a recent supergravity solution of Pilch and Warner, which is dual to the N=4 gauge theory softly broken to N=2. We verify that a D3-brane probe has the expected moduli space and its effective action can be brought to N=2 form. The kinetic term for the probe vanishes on an enhancon locus, as in earlier work on large-n N=2 the

G. Hiller

We briefly review the status of rare radiative and semileptonic $b \to s (γ, \ell^+ \ell^-)$, ($\ell=e,μ$) decays. We discuss possible signatures of new physics in these modes and emphazise the role of the exclusive channels. In particular, measurements of the Forward-Backward asymmetry in $B \to K^* \ell^+ \ell^-$ decays and its zero provide a clean test of

Eric Braaten, Sean Fleming, Adam K. Leibovich

Recent data from the CDF collaboration on the production of spin-triplet bottomonium states at the Tevatron p \bar p collider are analyzed within the NRQCD factorization formalism. The color-singlet matrix elements are determined from electromagnetic decays and from potential models. The color-octet matrix elements are determined by fitting the CDF data on t

J. C. Peng

Recent deep inelastic scattering and Drell-Yan experiments have revealed a surprisingly large asymmetry between the up and down sea quark distributions in the nucleon. The current status of the flavor asymmetry of the nucleon sea is reviewed. Implications of various theoretical models and possible future measurements are also discussed.