August 2000 arXiv papers — page 23

F. Bastianelli, O. Corradini, P. van Nieuwenhuizen

We extend dimensional regularization to the case of compact spaces. Contrary to previous regularization schemes employed for nonlinear sigma models on a finite time interval (``quantum mechanical path integrals in curved space'') dimensional regularization requires only a covariant finite two-loop counterterm. This counterterm is nonvanishing and giv

P. Heslop, P. S. Howe

The field strength superfield of IIB supergravity on $AdS_5\xz S^5$ is expanded in harmonics on $S^5$ with coefficients which are $D=5, N=8$ chiral superfields. On the boundary of $AdS_5$ these superfields map to $D=4,N=4$ chiral superfields and both sets of superfields obey additional fourth-order constraints. The constraints on the $D=4,N=4$ chiral fields

O. A. Castro-Alvaredo, A. Fring

We address the general question of how to reconstruct the field content of a quantum field theory from a given scattering theory in the context of the form factor program. For the $SU(3)_2$-homogeneous Sine-Gordon model we construct systematically all $n$-particle form factors for a huge class of operators in terms of general determinant formulae. We investi

Daniel J. Mortlock, Anthony D. Challinor, Michael P. Hobson

Measurement of the angular power spectrum of the cosmic microwave background is most often based on a spherical harmonic analysis of the observed temperature anisotropies. Even if all-sky maps are obtained, however, it is likely that the region around the Galactic plane will have to be removed due to its strong microwave emissions. The spherical harmonics ar

M. D. Albrow, J. An, J. -P. Beaulieu, J. A. R. Caldwell

We search for signatures of planets in 43 intensively monitored microlensing events that were observed between 1995 and 1999. Planets would be expected to cause a short duration (~1 day) deviation on the smooth, symmetric light curve produced by a single-lens. We find no such anomalies and infer that less than 1/3 of the ~0.3 M_sun stars that typically compr

Roger B. M. Clarke, Vivien M. Kendon, Anthony Chefles, Stephen M. Barnett

We present the results of generalized measurements of optical polarization designed to provide one of three or four distinct outcomes. This has allowed us to discriminate between nonorthogonal polarization states with an error probability that is close to the minimum allowed by quantum theory. Employing these optimal detection strategies on sets of three (tr

V. V'yurkov, A. Vetrov

An existence of predominant symmetrical spin configuration (spin polarised phase) and "diluted" density of states (pseudo-gap) in a layer under the Fermi level in a quantum wire is predicted. The condition of cross-over from non-polarised phase to polarised one was derived. The transition occurs for sufficiently low electron density in a wire and is

Joseph L. Birman, Meir Weger

We propose and investigate a model for the coexistence of Superconductivity (SC) and Ferroelectricity (FE) based on the dynamical symmetries $su(2)$ for the pseudo-spin SC sector, $h(4)$ for the displaced oscillator FE sector, and $su(2) \otimes h(4) $ for the composite system. We assume a minimal symmetry-allowed coupling, and simplify the hamiltonian using

W. Rodejohann

In a degenerate scheme with mass m_0 a complete analysis of the allowed range of the effective electron neutrino Majorana mass <m> is performed. Special attention is paid to effects of cancellations caused either by intrinsic CP parities of the eigenstates (CP invariance) or by complex mixing matrix elements (CP violation). We investigate all possibilities a

Ph. Boucaud, A. Le Yaouanc, J. P. Leroy, J. Micheli

We perform an OPE analysis of the flavorless non-perturbative gluon propagator and the symmetric three-gluon vertex in the Landau gauge. The first subdominant operator is $A_μA^μ$ which can condensate in the Landau gauge ``vacuum&#39;&#39; although being a non-gauge invariant operator. We neglect all higher dimension operators. Then the gluon propagator and

Uma Mahanta

In this report we derive the couplings of the Randall-Sundrum radion to the standard model higgs boson. We then use these couplings to determine the J=0 partial wave amplitude for the process $hh\to hϕ$. We find that at very high energies (i.e. $s\gg m_h^2, \mp^2$) the s wave partial wave unitarity is violated if $m_h>m_c\approx \sqrt{16π\vphi v}$ where $\vp

Antonio Alfonso-Faus

The fine structure constant $α$ includes the speed of light as given by $α=\frac{e^{2}}{4πε_{0}c\hbar}$. It is shown here that, following a $THεμ$ formalism, interpreting the permittivity $ε_{0}$ and permeabiliy $μ_{0}$ of free space under Lorentz local and position invariance, this is not the case. The result is a new expression as $α=\frac{e^{2}}{4π\hbar}$

M. Gungormez, H. R. Karadayi

It is known that characters of irreducible representations of finite Lie algebras can be obtained using theWeyl character formula including Weyl group summations which make actual calculations almost impossible except for a few Lie algebras of lower rank. By starting from the Weyl character formula, we show that these characters can be re-expressed without r

Gennady P. Berman, Daniel F. V. James, Dimitry I. Kamenev

Classical and quantum dynamics of a harmonic oscillator in a monochromatic wave is studied in the exact resonance and near resonance cases. This model describes, in particular, a dynamics of a cold ion trapped in a linear ion trap and interacting with two lasers fields with close frequencies. Analytically and numerically a stability of the ``classical ground

J. -F. Muzy, D. Sornette, J. Delour, A. Arneodo

We extend and test empirically the multifractal model of asset returns based on a multiplicative cascade of volatilities from large to small time scales. The multifractal description of asset fluctuations is generalized into a multivariate framework to account simultaneously for correlations across times scales and between a basket of assets. The reported em

Julio Gea-Banacloche

For a simple model of mutually interacting qubits it is shown how the errors induced by mutual interactions can be eliminated using concatenated coding. The model is solved exactly for arbitrary interaction strength, for two well-known codes, one and two levels deep: this allows one to see under which circumstances error amplitudes add coherently or incohere

Juan Leon

The time of arrival at an arbitrary position in configuration space can be given as a function of the phase space variables for the Liouville integrable systems of classical mechanics, but only for them. We review the Jacobi-Lie transformation that explicitly implements this function of positions and momenta. We then discuss the recently developed quantum fo

Howard Barnum, Carlton M. Caves, Christopher A. Fuchs, Richard Jozsa

We consider the problem of optimal asymptotically faithful compression for ensembles of mixed quantum states. Although the optimal rate is unknown, we prove upper and lower bounds and describe a series of illustrative examples of compression of mixed states. We also discuss a classical analogue of the problem.

A. K. Popov, S. A. Myslivets, Gao Jin-yue, Zhang Han-zhuang

Inversionless gain in a three-level system driven by a strong external field and by collisions with a buffer gas is investigated. The mechanism of populating of the upper laser level contributed by the collision transfer as well as by relaxation caused by a buffer gas is discussed in detail. Explicit formulae for analysis of optimal conditions are derived. T

PJ Edwards, W N Cheung, H van Pham, G Ganesharajah

Quantum-correlated photon sources provide a means of suppressing multiple photon emission and thus improving the security and efficiency of quasi single-photon quantum key distribution systems. We present illustrative photon-counting statistics for a Poissonian source conditioned by photon number measurements on a fully correlated twin beam with a non-ideal

Eyal Gruss

We suggest solving the measurement problem by postulating the existence of a special future final boundary condition for the universe. Although this is an extension of the way boundary conditions are usually chosen (in terrestrial laboratories), it is our only deviation from standard quantum mechanics. Using two state vectors, or the &#34;two-state&#34;, to

Dagoberto S Freitas, Jairo R de Oliveira

The properties of pulse propagation in a nonlinear fiber including linear damped term added in the usual nonlinear Schrödinger equation is analyzed analytically. We apply variational modified approach based on the lagrangian that describe the dynamic of system and with a trial function we obtain a solution which is more accuracy when compared with a pertubat

A. Mary Selvam

A cell dynamical system model for deterministic chaos enables precise quantification of the round-off error growth,i.e., deterministic chaos in digital computer realizations of mathematical models of continuum dynamical systems. The model predicts the following: (a) The phase space trajectory (strange attractor) when resolved as a function of the computer ac

J. A. Sheikh, E. Lopes, P. Ring

The numerical solution of the recently formulated number-projected Hartree-Fock-Bogoliubov equations is studied in an exactly soluble cranked-deformed shell model Hamiltonian. It is found that the solution of these number-projected equations involve similar numerical effort as that of bare HFB. We consider that this is a significant progress in the mean-fiel

J. Golak, G. Ziemer, H. Kamada, H. Witala

Inclusive 3He(e,e&#39;) and exclusive 3He(e,e&#39;n) processes with polarized electrons and 3He have been theoretically analyzed and values for the magnetic and electric neutron form factors have been extracted. In both cases the form factor values agree well with the ones extracted from processes on the deuteron. Our results are based on Faddeev solutions,

M. Hasegawa, K. Kaneko, S. Tazaki

The extended pairing plus $QQ$ interaction with the $J$-independent isoscalar proton-neutron force as an average monopole field, which has succeeded in describing collective yrast states of $N \approx Z$ even-$A$ nuclei, is improved. The improvement is accomplished by adding small monopole terms (relevant to spectroscopy) to the average monopole field (indis

Gennady A. El, Alexander L. Krylov, Stephanos Venakides

We develop a unified approach to integrating the Whitham modulation equations. Our approach is based on the formulation of the initial value problem for the zero dispersion KdV as the steepest descent for the scalar Riemann-Hilbert problem, developed by Deift, Venakides, and Zhou, 1997, and on the method of generating differentials for the KdV-Whitham hierar

Louis J. Dube&#39;, Philippe Despres

Following a brief historical introduction of the notions of chaos in dynamical systems, we will present recent developments that attempt to profit from the rich structure and complexity of the chaotic dynamics. In particular, we will demonstrate the ability to control chaos in realistic complex environments. Several applications will serve to illustrate the

Jeffrey H. Schenker, Michael Aizenman

We present a mechanism for the creation of gaps in the spectra of self-adjoint operators defined over a Hilbert space of functions on a graph, which is based on the process of graph decoration. The resulting Hamiltonians can be viewed as associated with discrete models exhibiting a repeated local structure and a certain bottleneck in the hopping amplitudes.

Daniela Bertacchi, Fabio Zucca

We investigate the asymptotical behaviour of the transition probabilities of the simple random walk on the 2-comb. In particular we obtain space-time uniform asymptotical estimates which show the lack of symmetry of this walk better than local limit estimates. Our results also point out the impossibility of getting Jones-type non-Gaussian estimates.

Bethany Marsh

Let U be the quantum group associated to a Lie algebra of type A_n. The negative part U^- of U has a canonical basis B defined by Lusztig and Kashiwara, with favourable properties. We show how the spanning vectors of the cones defined by Lusztig when regarded as monomials in Kashiwara&#39;s root operators, can be described using a remarkable rectangle combin

Bob Coecke, Isar Stubbe

We enlarge the hom-sets of categories of complete lattices by introducing `state transitions&#39; as generalized morphisms. The obtained category will then be compared with a functorial quantaloidal enrichment and a contextual quantaloidal enrichment that uses a specific concretization in the category of sets and partially defined maps ($Parset$).

Nigel Hitchin

We calculate the Wess-Zumino term $Γ(g)$ for a harmonic map $g$ of a closed surface to a compact, simply connected, simple Lie group $G$ in terms of the energy and the holonomy of the Chern-Simons line bundle on the moduli space of flat $G$-connections. In the case of the 2-sphere we deduce that $Γ(g)$ is 0 or $π$ and for the 2-torus and $G=SU(2)$ we give a

Marian Grendar, Marian Grendar

A probabilistic rationale for I-divergence minimization (relative entropy maximization), non-parametric likelihood maximization and J-divergence minimization (Jeffres&#39; entropy maximization) criteria is provided.

Cristopher Moore, David Eppstein

We solve the problem of one-dimensional peg solitaire. In particular, we show that the set of configurations that can be reduced to a single peg forms a regular language, and that a linear-time algorithm exists for reducing any configuration to the minimum number of pegs.

Michael Lachmann, Cristopher Moore, Ivan Rapaport

Using mostly elementary considerations, we find out who wins the game of Domineering on all rectangular boards of width 2, 3, 5, and 7. We obtain bounds on other boards as well, and prove the existence of polynomial-time strategies for playing on all boards of width 2, 3, 4, 5, 7, 9, and 11. We also comment briefly on toroidal and cylindrical boards.

Lorenzo Leal

We quantize the Maxwell Chern Simons theory in a geometric representation that generalizes the Abelian Loop Representation of Maxwell theory. We find that in the physical sector, the model can be seen as the theory of a massles scalar field with a topological interaction that enforces the wave functional to be multivalued. This feature allows to relate the M

P. S. Howe

Some aspects of the $D=6, (2,0)$ tensor multiplet are discussed. Its formulation as an analytic superfield on a suitably defined superspace and its superconformal properties are reviewed. Powers of the field strength superfield define a series of superconformal fields which correspond to the KK multiplets of D=11 supergravity on an $AdS_7\xz S^4$ background.

Vipul Periwal

I construct a map from the Grothendieck group of coherent sheaves to $K$-homology. This results in explicit realizations of $K$-homology cycles associated with D-brane configurations. Non-Abelian degrees of freedom arise in this framework from the deformation quantization of $N$-tuple cycles. The large $N$ limit of the gauge theory on D-branes wrapped on a s

A. Smailagic, E. Spallucci

We show the equivalence between Stuckelberg and Wess-Zumino methods of restoration of gauge symmetries of the anomalous, Abelian, effective action, in arbitrary even dimensions D=2k. We present dual version of Wess-Zumino terms with the compensating field described by a Kalb-Ramond like p=2k-2 form.

J. D. Bjorken

Hadron physics is that part of QCD dealing with hadron structure and vacuum structure, almost all of which is nonperturbative in nature. Some of the open problems in this field are outlined. We argue that hadron physics is a distinct subfield, no longer within particle physics, and not at all the same as classical nuclear physics. We believe that it needs to

N. G. Antoniou, Y. F. Contoyiannis, F. K. Diakonos

We investigate the geometry of a critical system undergoing a second order thermal phase transition. Using a local description for the dynamics characterizing the system at the critical point T=Tc, we reveal the formation of clusters with fractal geometry, where the term cluster is used to describe regions with a nonvanishing value of the order parameter. We

P. H. Chankowski, L. Slawianowska

We present the results of the complete one-loop computation of the $B^0_{d,s}\to l^+l^-$ decay rate in the MSSM. Both sources of the FCNC, the CKM matrix and off-diagonal entries of the sfermion mass matrices are considered. Strong enhancement of the branching ratio (compared to the SM prediction) can be obtained in the large $\tanβ\sim m_t/m_b$ regime in wh

Jong-Phil Lee, Chun Liu, H. S. Song

The mass spectra of the L=1 orbitally excited heavy baryons with light quarks in both the spin-flavor symmetric and the mixed representations are studied by the $1/N_c$ expansion method in the framework of the heavy quark effective theory. The mixing effect between the baryons in the two representations is also considered. The general pattern of the spectrum

T. Asaka, Masaaki Fujii, K. Hamaguchi, T. Yanagida

We perform a detailed analysis on Affleck-Dine leptogenesis taking into account the thermal effects on the dynamics of the flat direction field $ϕ$. We find that an extremely small mass for the lightest neutrino $ν_1$, ${m_ν}_1\lsim 10^{-8}$ eV, is required to produce enough lepton-number asymmetry to explain the baryon asymmetry in the present universe. We

N. E. Ligterink, N. R. Walet, R. F. Bishop

We discuss the application of an extended version of the coupled cluster method to systems exhibiting a quantum phase transition. We use the lattice O(4) non-linear sigma model in (1+1)- and (3+1)-dimensions as an example. We show how simple predictions get modified, leading to the absence of a phase transition in (1+1) dimensions, and strong indications for

V. Rubish

The work is devoted to the description of baryon mass spectrum in the quasy-relativistic quark potential model. For cosidering 3 - quark system advantageous is the use of hyperspherical functions. For obtaining the mass - seguence of $Δ_{33}-$isobar the numerical computations were carryed out with the use of screened QCD - motivated potential, the use of whi

Pietro Slavich

It was recently claimed that single stop production at the Tevatron, occurring via R-parity (and baryon number) violating couplings, could lead to observable signals. In this talk I present some results of a work in progress, showing that rare B decays and K0-K0bar mixing strongly constrain such a possibility.

G. J. McCance

Inclusive event shape variables have been measured in the Breit Frame for neutral current deep-inelastic positron-proton scattering using the H1 and ZEUS detectors at HERA. The variables thrust, jet broadening, C-parameter, jet mass and two kinds of differential two-jet rate have been studied in the kinematic range 7 < Q < 100 GeV. The Q dependence of the sh

Kent Paschke, Brian Quinn

The formalism describing the scattering of two spin-1/2 objects is reviewed for the case of antilambda-lambda production from antiproton-proton annihilation. It is shown that an experiment utilizing a transverse target polarization can, in principle, completely determine the spin structure of the reaction. Additional measurements, even those using both beam

M. Artuso, R. Ayad, A. Efimov, S. Kopp

The CLEO detector has been upgraded to include a state of the art particle identification system, based on the Ring Imaging Cherenkov Detector (RICH) technology, in order to take data at the upgraded CESR electron positron collider. The expected performance is reviewed, as well as the preliminary results from an engineering run during the first few months of

L. I. Men&#39;shikov, I. A. Perevalova, A. N. Pinzul

For the example of an accelerated shell we show that omission of the energy-momentum tensor (EMT) of the body that causes the acceleration and the tensions due to this acceleration can lead to a paradoxical result; Namely, the entrainment of an inertial frame by the accelerated shell in the direction opposite to that of the acceleration. We consider several

Giovanni Amelino-Camelia

This author&#39;s recent proposal of interferometric tests of Planck-scale-related properties of space-time is here revisited from a strictly phenomenological viewpoint. The results announced previously are rederived using elementary dimensional considerations. The dimensional analysis is then extended to the other two classes of experiments (observations of

Rita Maria Zorzenon dos Santos, Sergio Coutinho

We use a cellular automata model to study the evolution of HIV infection and the onset of AIDS. The model takes into account the global features of the immune response to any pathogen, the fast mutation rate of the HIV and a fair amount of spatial localization. Our results reproduce quite well the three-phase pattern observed in T cell and virus counts of in

I. -K. Jeong, F. Mohiuddin-Jacobs, V. Petkov, S. J. L. Billinge

Nearest and higher neighbor distances as well as bond length distributions (static and thermal) of the In_xGa_(1-x)As (0<x<1) semiconductor alloys have been obtained from high real-space resolution atomic pair distribution functions (PDFs). Using this structural information, we modeled the local atomic displacements in In_xGa_(1-x)As alloys. From a supercell

Sorin Solomon

The origin of macroscopic complexity is traced in a wide range of systems (imunology, ecology, finance, marketing, etc) to the discrete and auto-catalytic (i.e. multiplicative) character of their elementary components. Even in the simplest conditions which naively would lead to the complete &#34;death&#34; of any dynamics, these 2 properties lead to the emer

Mikael Fogelstrom

The Josephson coupling of two isotropic s-wave superconductors through a small, magnetically active junction is studied. This is done as a function of junction transparency and of the degree of spin-mixing occurring in the barrier. In the tunneling limit, the critical current shows an anomalous 1/T temperature dependence at low temperatures and for certain m

Peter Borrmann, Jens Harting, Oliver Muelken, Eberhard R. Hilf

We derive an exact recursion formula for the calculation of thermodynamic functions of finite systems obeying Bose-Einstein statistics. The formula is applicable for canonical systems where the particles can be treated as noninteracting in some approximation, e.g. like Bose-Einstein condensates in magnetic traps. The numerical effort of our computation schem

R. Ballagh, C. M. Savage

We review the current theory of atom lasers. A tutorial treatment of second quantisation and the Gross-Pitaevskii equation is presented, and basic concepts of coherence are outlined. The generic types of atom laser models are surveyed and illustrated by specific examples. We conclude with detailed treatments of the mechanisms of gain and output coupling.

M. Titov, C. W. J. Beenakker

The average power spectrum of a pulse reflected by a disordered medium embedded in an N-mode waveguide decays in time with a power law t^(-p). We show that the exponent p increases from 3/2 to 2 after N^2 scattering times, due to the onset of localisation. We compare two methods to arrive at this result. The first method involves the analytic continuation to

R. F. Coker, J. M. Pittard

We present several models for IRS 13E, an infrared, mm and X-ray source in the Galactic Center. Our favored interpretation is that of an early-type binary with strong colliding winds emission. This naturally explains the observed X-ray count rate and the strong infrared emission lines, and has a distinct advantage over competing hypotheses based upon a singl

C. Vignali, A. Comastri, F. Nicastro, G. Matt

BeppoSAX and ASCA observations of the nearby (z=0.184), high-luminosity, radio-quiet quasar PDS456 are presented. The X-ray spectrum is characterized by a prominent ionized edge at 8-9 keV (originally discovered by RXTE, Reeves et al. 2000) and by a soft excess below 1.5 keV. The lack of any significant iron K alpha emission line suggests for the edge an ori

Chris A. Clarkson

This thesis concerns the compatibility of inhomogeneous cosmologies with our present understanding of the universe. It is a problem of some interest to find the class of all relativistic cosmological models which are capable of providing a reasonable `fit&#39; to the universe. This thesis, in some respects, is part of this process. We consider Stephani model

Kartik Sheth, Stuart N. Vogel, Andrew I. Harris, Michael W. Regan

Using a sample of 7 barred spirals from the BIMA Survey of Nearby Galaxies (SONG), we compare the molecular gas distribution in the bar, to recent massive star formation activity. In all 7 galaxies, Halpha is offset azimuthally from the CO on the downstream side. The maximum offset, at the bar ends, ranges from 170-570 pc, with an average of 320 +/- 120 pc.

T. Mazeh, S. Zucker

This paper compares the statistical features of the sample of discovered extrasolar planets with those of the secondaries in nearby spectroscopic binaries, in order to enable us to distinguish between the two populations. Based on 32 planet candidates discovered until March 2000, we find that their eccentricity and period distribution are surprisingly simila

Amina Helmi

In this contribution we discuss the expected properties of our halo if our Galaxy had been built from mergers of smaller systems. Using both analytic arguments and high-resolution simulations, we find that the Galactic halo in the Solar neighbourhood should have a smooth spatial distribution and that its stellar velocity ellipsoid should consist of several h

M. Villar-Martin, R. A. E. Fosbury, J. Vernet, M. Cohen

By modeling the rich emission line spectra of a sample of high redshift (HzRG, z\sim 2.5) radio galaxies we find that solar and supersolar metallicities are common in the extended gas of these objects. Our models and the comparison with high redshift quasars suggest that HzRG at z\sim 2.5 are associated with intense star formation activity. This is consisten

Dongsu Ryu, T. W. Jones, Adam Frank

We investigate through high resolution 3D simulations the nonlinear evolution of compressible magnetohydrodynamic flows subject to the Kelvin-Helmholtz instability. We confirm in 3D flows the conclusion from our 2D work that even apparently weak magnetic fields embedded in Kelvin-Helmholtz unstable plasma flows can be fundamentally important to nonlinear evo

Daniel J. Mortlock, Rachel L. Webster

Gravitationally-lensed quasars can be discovered as a by-product of galaxy redshift surveys. Lenses discovered spectroscopically in this way should require less observational effort per event than those found in dedicated lens surveys. Further, the lens galaxies should be relatively nearby, facilitating a number of detailed observations that are impossible f

Daniel J. Mortlock, Rachel L. Webster

The absence of any wide-separation gravitational lenses in the Large Bright Quasar Survey is used to place limits on the population of cluster-sized halos in the universe, and hence constrain a number of cosmological parameters. The results agree with previous investigations in strongly ruling out the standard cold dark matter model but they are consistent w

Marco Castellani, Giuseppe Bono, Santi Cassisi, Gianni Marconi

Deep (I,V-I) and (I,B-I) color-magnitude diagrams (CMDs) of the Antlia dwarf galaxy, based on Science Verification (SV) data collected with the FORS I camera on the ESO Very Large Telescope (VLT) are presented. By adopting the new calibration of the Tip of the Red Giant Branch (TRGB) provided by Salaris & Cassisi (1998) we estimated that the Antlia distance

Daniel J. Mortlock, Rachel L. Webster

The fraction of high-redshift sources which are multiply-imaged by intervening galaxies is strongly dependent on the cosmological constant, and so can be a useful probe of the cosmological model. However its power is limited by various systematic (and random) uncertainties in the calculation of lensing probabilities, one of the most important of which is the

Alessandro de Angelis

This report summarizes four recent papers on the characteristics of the hadronic decays of the Z by the LEP collaborations ALEPH, DELPHI and OPAL.

Vikram V. Dwarkadas

The evolution of Type Ia supernovae in the surrounding medium is studied using 2-dimensional numerical hydrodynamic simulations. The ejecta are assumed to be described by an exponential density profile, following the work of Dwarkadas & Chevalier (1998). The case of a circumstellar (CS) region formed by mass loss from the progenitor or a companion star is al

Jason X. Prochaska, Sergei O. Naumov, Bruce W. Carney, Andrew McWilliam

We present first results from a program to measure the chemical abundances of a large (N>30) sample of thick disk stars with the principal goal of investigating the formation history of the Galactic thick disk. Our analysis confirms previous studies of O and Mg in the thick disk stars which reported enhancements in excess of the thin disk population. Further

Susan A. Lamb, Nathan C. Hearn

We present a brief overview of some recent observations of colliding galaxies and relevant numerical simulations. These are compared, and details of the locations and history of collision induced star formation are explored, with possible application to star formation at earlier epochs.

J. P. Kneller, J. R. Phillips, T. P. Walker

We calculate the production rates of Li6, Li7, Be9, B10 and B11 via spallation of Carbon, Nitrogen and Oxygen nuclei by protons and alpha-particles and by alpha-alpha fusion reactions. We include recent measurements of the cross sections of alpha-alpha fusion reactions and find that the computations yield rates of Li6 and Li7 production that are nearly a fac

Rafael Millan-Gabet, F. Peter Schloerb, Wesley A. Traub

We have conducted the first systematic study of Herbig Ae/Be stars using the technique of long baseline stellar interferometry in the near-infrared. The principal result of this paper is that the IOTA interferometer resolves the source of infrared excess in 11 of the 15 systems surveyed. The visibility data for all the sources has been interpreted within the

Zurab Kakushadze

We consider a recently proposed setup where a codimension one brane is embedded in the background of a smooth domain wall interpolating between AdS and Minkowski minima. Since the volume of the transverse dimension is infinite, bulk supersymmetry is intact even if brane supersymmetry is completely broken. On the other hand, in this setup unbroken bulk supers

Tsuyoshi Suwada

A beam-energy-spread monitor is under development in order to control and stabilize the energy spread of high-current single-bunch electron beams for producing a sufficient number of positrons. The author has proposed a new monitor using multi-stripline electrodes in order to reinforce this purpose. This report describes the basic design of the monitor based

Sumit Das, Soo-Jong Rey

We study the issue of gauge-invariant observables in d=4, N=4 noncommutative gauge theory and UV-IR relation therein. We show that open Wilson lines form a complete set of gauge invariant operators, which are local in momentum space and, depending on their size, exhibit two distinct behaviors of the UV-IR relation. We next study these properties in a propose

Silvio Rabello, Qimiao Si

We show that the single-particle spectral functions in a magnetic field can be used to probe spin-charge separation of a Luttinger liquid. Away from the Fermi momentum, the magnetic field splits both the spinon peak and holon peak; here the spin-charge separation nature is reflected in the different magnitude of the two splittings. At the Fermi momentum, the

M. Carena, S. Heinemeyer, C. E. M. Wagner, G. Weiglein

We investigate the phenomenological implications of a light scalar bottom quark, with a mass of about the bottom quark mass, within the minimal supersymmetric standard model. The study of such a scenario is of theoretical interest, since, depending on their production and decay modes, light sbottoms may have escaped experimental detection up to now and, in a

Bethany Marsh

We show that for each reduced expression for the longest word in the Weyl group of type A_n, the corresponding cone arising in Lusztig&#39;s description of the canonical basis in terms of tight monomials is simplicial, and construct explicit spanning vectors.

Jerome P. Gauntlett, Chanju Kim, Kimyeong Lee, Piljin Yi

We derive general low energy dynamics of monopoles and dyons in N=2 and N=4 supersymmetric Yang-Mills theories by utilising a collective coordinate expansion. The resulting new kind of supersymmetric quantum mechanics incorporates the effects of multiple Higgs fields, both in the N=2 vector multiplet and hypermultiplets, having non-vanishing expectation valu

D. Belitz, T. R. Kirkpatrick, Maria Teresa Mercaldo, Sharon L. Sessions

An effective field theory is derived that describes the quantum critical behavior of itinerant ferromagnets in the presence of quenched disorder. In contrast to previous approaches, all soft modes are kept explicitly. The resulting effective theory is local and allows for an explicit perturbative treatment. It is shown that previous suggestions for the criti

Patrick Dorey, Clare Dunning, Roberto Tateo

We show that SU(n) Bethe Ansatz equations with arbitrary `twist&#39; parameters are hidden inside certain nth order ordinary differential equations, and discuss various consequences of this fact.

J. M. Figueroa-O&#39;Farrill, S. Stanciu

We reconsider the problem of U(1) flux and D0-charge for D-branes in the WZW model and investigate the relationship between the different definitions that have been proposed recently. We identify the D0-charge as a particular reduction of a class in the relative cohomology of the group modulo the D-submanifold. We investigate under which conditions this clas

Pavel Ivanov

It is shown that the Lame&#39;s equation ${d^{2}\over d z^{2}}X+κ^{2} cn^{2}(z, {1\over \sqrt 2})X=0$ can be reduced to the hyper-geometric equation. The characteristic exponents of this equation are expressed in terms of elementary functions of the parameter $κ$. An analytical condition for parametric amplification is obtained.

Washington Taylor

The level truncation approach to string field theory is used to study the zero-momentum action for vector excitations on a bosonic D-brane which has been annihilated by tachyon condensation. It is shown that in the true vacuum the translation zero modes associated with transverse scalars on the D-brane are lifted by spontaneous generation of mass terms. Simi

M. N. Kiselev, R. Oppermann

We derive a path-integral Schwinger-Keldysh approach for quantum spin systems. This is achieved by means of a semionic representation of spins as fermions with imaginary chemical potential. The major simplifying feature in comparison with other representations (Holstein-Primakoff, Dyson-Maleev, slave bosons/fermions etc) is that the local constraint is taken

P. Mathieu, Y. Xudous

Through an $\hbar$-expansion of the confined Calogero model with spin exchange interactions, we extract a generating function for the involutive conserved charges of the Frahm-Polychronakos spin chain. The resulting conservation laws possess the spin chain yangian symmetry, although they are not expressible in terms of these yangians.

Karol Zyczkowski, Wojciech Slomczynski

Topological and geometrical properties of the set of mixed quantum states in the N-dimensional Hilbert space are analysed. Assuming that the corresponding classical dynamics takes place on the sphere we use the vector SU(2) coherent states and the generalised Husimi distributions to define the Monge distance between arbitrary two density matrices. The Monge

Matthias Vojta, Ying Zhang, Subir Sachdev

We describe a search for renormalization group fixed points which control a second-order quantum phase transition between a d_{x^2-y^2} superconductor and some other superconducting ground state. Only a few candidate fixed points are found. In the finite temperature quantum-critical region of some of these fixed points, the fermion quasiparticle lifetime is

H. Takayasu, M. Takayasu, M. P. Okazaki, K. Marumo

Scaling properties in financial fluctuations are reviewed from the standpoint of statistical physics. We firstly show theoretically that the balance of demand and supply enhances fluctuations due to the underlying phase transition mechanism. By analyzing tick data of yen-dollar exchange rates we confirm two fractal properties: 1 The distribution of rate chan

Aaron J. Romanowsky, Christopher S. Kochanek

We examine the dynamics of the stars and globular clusters in the nearby giant galaxy M87 and constrain the mass distribution, using all the available data over a large range of radii, including higher-order moments of the stellar line-of-sight velocity distributions and the discrete velocities of over two hundred globular clusters. We introduce an extension

A. J. McDonald, M. P. Allen, F. Schmid

We present the first calculations of the pressure tensor profile in the vicinity of the planar interface between isotropic liquid and nematic liquid crystal, using Onsager&#39;s density functional theory and computer simulation. When the liquid crystal director is aligned parallel to the interface, the situation of lowest free energy, there is a large tensio

Tai-Fu Feng, Xue-Qian Li, Wen-Gan Ma, Feng Zhang

We present a complete next-to-leading-order calculation of the QCD corrections to $B^0-\bar{B}^0$ ($K^0-\bar{K}^0$) mixing in the framework of the minimal flavor violating (MFV) supersymmetry. We take into account the contributions from the gluino and find that the gluino-mediated corrections modify the LO result obviously even when the mass of gluino $m_{\t

J. A. Folk, C. M. Marcus, J. S. Harris

Decoherence in nearly-isolated GaAs quantum dots is investigated using the change in average Coulomb blockade peak height upon breaking time-reversal symmetry. The normalized change in average peak height approaches the predicted universal value of 1/4 at temperatures well below the single-particle level spacing, but is greatly suppressed for temperature gre

K. Pottschmidt, J. Wilms, R. Staubert, M. A. Nowak

We present temporal and spectral results from monitoring Cygnus X-1 with the Rossi X-ray Timing Explorer (RXTE) in 1998 and 1999. We concentrate on the long term evolution of the hard state timing properties, comparing it to the 1996 soft state evolution. This leads to the following results: 1. the hard and soft state time lag spectra are very similar, 2. du