March 2001 arXiv papers — page 14

Kingman Cheung, Chung-Hsien Chou, Otto C. W. Kong

The recent measurement on the muon anomalous magnetic moment $a_μ$ shows a $2.6σ$ deviation from the standard model value. We show that it puts strong constraints on the parameter space of the two-higgs doublet model (2HDM) II. The dominant contribution of the Higgses comes at the two-loop level, and in order to explain the data it favors a pseudoscalar $A$

Jeongwon Ho

We investigate the generalized second law for two-dimensional black holes in equilibrium (Hartle-Hawking) and nonequilibrium (Unruh) with the heat bath surrounding the black holes. We obtain a simple expression for the change of total entropy in terms of covariant thermodynamic variables, which is valid not only for the Hartle-Hawking state but also for the

Anirban Roy, Aditi Sen, Ujjwal Sen

We show that in a cloning process, whether deterministic inexact or probabilistic exact, one can take an arbitrary blank state while still using a fixed cloning machine.

H. Ishii, K. Okazaki, A. Fujimori, Y. Nagamoto

We have studied the electronic structure of the skutterudite compounds Co(Sb$_{1-x}$Te$_{x}$)$_3$ (x= 0, 0.02, 0.04) by photoemission spectroscopy. Valence-band spectra revealed that Sb 5p states are dominant near the Fermi level and are hybridized with Co 3d states just below it. The spectra of {\it p}-type CoSb$_3$ are well reproduced by the band-structure

A. -S. Nicollerat

The possibility to observe a Higgs boson having a mass between 300 and 600 GeV and to measure its couplings to vector bosons and top quark with CMS at the LHC is studied. Six different signatures are analyzed. The possibility to separate the Higgs events produced through weak boson fusion from the Higgs produced through gluon fusion using the forward going j

Junzo Chihara, Ichirou Fukumoto, Mitsuru Yamagiwa, Hiroo Totsuji

At first, pressure formulas for the electrons under the external potential produced by fixed nuclei are derived both in the surface integral and volume integral forms concerning an arbitrary volume chosen in the system; the surface integral form is described by a pressure tensor consisting of a sum of the kinetic and exchange-correlation parts in the density

Shinji Komine, Takeo Moroi, Masahiro Yamaguchi

Supersymmetric contribution to the muon anomalous magnetic moment a_μis discussed in the no-scale-type supersymmetry breaking scenarios. Taking the correlation between the supersymmetric contributions to a_μand Br(b\to sγ), it is shown that the precise measurements of these quantities serve an important constraint on the relative sign of the gaugino masses;

R. Burkhalter, M. Imachi, Y. Shinno, H. Yoneyama

The topological charge distribution P(Q) is calculated for lattice ${\rm CP}^{N-1}$ models. In order to suppress lattice cut-off effects we employ a fixed point (FP) action. Through transformation of P(Q) we calculate the free energy $F(θ)$ as a function of the $θ$ parameter. For N=4, scaling behavior is observed for P(Q), $F(θ)$ as well as the correlation l

Kouji Yasui, Takafumi Kita

We present a theoretical study on the de Haas-van Alphen (dHvA) oscillation in the vortex state of type-II superconductors, with a special focus on the connection between the gap anisotropy and the oscillation damping. Numerical calculations for three different gap structures clearly indicate that the average gap along extremal orbits is relevant for the mag

Hideaki Hiro-Oka, Hisakazu Minakata

We investigate the problem of quantum back reactions due to particle production by the parametric resonance mechanism in an environment of nonequilibrium chiral phase transition. We work with the linear sigma model and employ Boyanovsky et al.'s formalism to take account of back reactions under the Hartree-Fock approximation. We calculate the single pion

Carl E. Carlson, Christopher D. Carone

In models with a low quantum gravity scale, one might expect sizable effects from nonrenormalizable interactions that violate the global symmetries of the standard model. While some mechanism must be invoked in such theories to suppress higher-dimension operators that contribute to proton decay, operators that change baryon number by two units are less dange

Daniel E. Reichart, Donald Q. Lamb

We present a possible Cepheid-like luminosity estimator for the long-duration gamma-ray bursts based on the variability of their light curves. We also present a preliminary application of this luminosity estimator to 907 long-duration bursts from the BATSE catalog.

John N. Bahcall, Plamen I. Krastev, Alexei Yu. Smirnov

We present a global analysis of all the available solar neutrino data treating consistently the 8B and hep neutrino fluxes as free parameters. The analysis reveals at 99.7% C.L. eight currently-allowed discrete regions in two-neutrino oscillation space, five regions corresponding to active neutrinos and three corresponding to sterile neutrinos. Most of the a

David P. DiVincenzo, Debbie W. Leung, Barbara M. Terhal

We expand on our work on Quantum Data Hiding -- hiding classical data among parties who are restricted to performing only local quantum operations and classical communication (LOCC). We review our scheme that hides one bit between two parties using Bell states, and we derive upper and lower bounds on the secrecy of the hiding scheme. We provide an explicit b

Xingxiang Zhou, Zheng-Wei Zhou, Marc J. Feldman, Guang-Can Guo

We propose a novel scheme for nondistortion quantum interrogation (NQI), defined as an interaction-free measurement which preserves the internal state of the object being detected. In our scheme, two EPR entangled photons are used as the probe and polarization sensitive measurements are performed at the four ports of the Mach-Zehnder interferometer. In compa

D. Boose, F. Bardou

A small momentum transfer to a particle interacting with a steep potential barrier gives rise to a quantum evaporation effect which increases the transmission appreciably. This effect results from the unexpectedly large population of quantum states with energies above the height of the barrier. Its characteristic properties are studied and an example of phys

Pavel Exner, Milos Tater, David Vanek

We study transport in quantum systems consisting of a finite array of N identical single-channel scatterers. A general expression of the S matrix in terms of the individual-element data obtained recently for potential scattering is rederived in this wider context. It shows in particular how the band spectrum of the infinite periodic system arises in the limi

David Wallace

This is a discussion of how we can understand the world-view given to us by the Everett interpretation of quantum mechanics, and in particular the role played by the concept of `world'. The view presented is that we are entitled to use `many-worlds' terminology even if the theory does not specify the worlds in the formalism; this is defended by means

Pawel Horodecki

The paper has been withdrawn by the author due to crucial error in formula (14) which does not satisfy conditions for S(x,y) domain if only d>2.

C. Giannardi, D. Dominici

This work is an exposure assessment for a population living in an area contaminated by use of depleted uranium (DU) weapons. RESRAD 5.91 code is used to evaluate the average effective dose delivered from 1, 10, 20 cm depths of contaminated soil, in a residential farmer scenario. Critical pathway and group are identified in soil inhalation or ingestion and ch

R. Jáuregui, N. Poli, G. Roati, G. Modugno

We study both experimentally and theoretically the losses induced by parametric excitation in far-off-resonance optical lattices. The atoms confined in a 1D sinusoidal lattice present an excitation spectrum and dynamics substantially different from those expected for a harmonic potential. We develop a model based on the actual atomic Hamiltonian in the latti

G. Labeyrie, C. Miniatura, R. Kaiser

We experimentally studied the Faraday rotation of resonant light in an optically-thick cloud of laser-cooled rubidium atoms. Measurements yield a large Verdet constant in the range of 200 000 degrees/T/mm and a maximal polarization rotation of 150 degrees. A complete analysis of the polarization state of the transmitted light was necessary to account for the

J. Carbonell, M. Mangin-Brinet

Some of the last results on low energy antiproton physics are reviewed. First Faddeev calculations for nd scattering length are presented.

K. Saito, V. Guzey, K. Tsushima, A. W. Thomas

Using a pair of the lightest mirror nuclei, $^3$He and $^3$H, we study the effect of the medium modification of pion fields on the flavor non-singlet structure function. The change of the pion fields leads to an enhancement of the flavor asymmetry of the antiquark distributions in a nucleus.

B. Konopelchenko, L. Martinez Alonso, O. Ragnisco

The dispersionless limit of the scalar nonlocal dbar-problem is derived. It is given by a special class of nonlinear first-order equations. A quasi-classical version of the dbar-dressing method is presented. It is shown that the algebraic formulation of dispersionless hierarchies can be expressed in terms of properties of Beltrami tupe equations. The univers

Goro Hatayama, Atsuo Kuniba, Taichiro Takagi

We present an elementary algorithm for the dynamics of recently introduced soliton cellular automata associated with quantum affine algebra U_q(g_n) at q=0. For g_n = A^{(1)}_n, the rule reproduces the ball-moving algorithm in Takahashi-Satsuma's box-ball system. For non-exceptional g_n other than A^{(1)}_n, it is described as a motion of particles and a

Nir Cohen, Stefano De Leo

The determinant for complex matrices cannot be extended to quaternionic matrices. Instead, the Study determinant and the closely related $q$-determinant are widely used. We show that the Study determinant can be characterized as the unique functional which extends the {\em absolute value} of the complex determinant and discuss its spectral and linear algebra

A. J. Macfarlane

Proceeding in analogy with su(n) work on lambda matrices and f- and d-tensors, this paper develops the technology of the Lie algebra g2, its seven dimensional defining representation gamma and the full set of invariant tensors that arise in relation thereto. A comprehensive listing of identities involving these tensors is given. This includes identities that

Marco Manetti

We introduce a precise notion, in terms of few Schlessinger's type conditions, of extended deformation functors which is compatible with most of recent ideas in the Derived Deformation Theory (DDT) program and with geometric examples. With this notion we develop the (extended) analogue of Schlessinger and obstruction theories. The inverse mapping theorem

Donghi Lee

An endomorphism of a free group is called primitivity preserving if it takes every primitive element to another primitive. In this paper we prove that every primitivity preserving endomorphism of a free group of a finite rank n > 2 is an automorphism.

Torbjörn Lundh

In the near future, all the human genes will be identified. But understanding the functions coded in the genes is a much harder problem. For example, by using block entropy, one has that the DNA code is closer to a random code then written text, which in turn is less ordered then an ordinary computer code; see \cite{schmitt}. Instead of saying that the DNA i

Donghi Lee

Let F_m be a free group of a finite rank m > 1 and X_i, Y_j be elements in F_m. A non-empty word w(x_1,..., x_n) is called a C-test word in n letters for F_m if, whenever w(X_1,..., X_n)=w(Y_1,..., Y_n) not equal to 1, the two n-tuples (X_1,..., X_n) and (Y_1,..., Y_n) are conjugate in F_m. In this paper we construct, for each n > 1, a C-test word v_n(x_1,..

Noam D. Elkies

We give a general recipe for explicitly constructing asymptotically optimal towers of modular curves such as {X_0(l^n): n=1,2,3,...}. We illustrate the method by giving equations for eight towers with various geometric features. We conclude by observing that such towers are all of a specific recursive form, and speculate that perhaps every tower of this form

Renato M. Assuncao, Pablo A. Ferrari

Let N, N' and N'' be point processes such that N' is obtained from N by homogeneous independent thinning and N''= N- N'. We give a new elementary proof that N' and N'' are independent if and only if N is a Poisson point process. We present some applications of this result to test if a homogeneous point process is a Poi

B. Feigin, R. Kedem, S. Loktev, T. Miwa

The spaces of coinvariants are quotient spaces of integrable $\hat{sl_2}$ modules by subspaces generated by actions of certain subalgebras labeled by a set of points on a complex line. When all the points are distinct, the spaces of coinvariants essentially coincide with the spaces of conformal blocks in the WZW conformal field theory and their dimensions ar

Bojko Bakalov, Alessandro D'Andrea, Victor G. Kac

Conformal algebras, recently introduced by Kac, encode an axiomatic description of the singular part of the operator product expansion in conformal field theory. The objective of this paper is to develop the theory of ``multi-dimensional'' analogues of conformal algebras. They are defined as Lie algebras in a certain ``pseudotensor'' category

Nima Arkani-Hamed, Andrew G. Cohen, Howard Georgi

We discuss the form of the chiral anomaly on an S1/Z2 orbifold with chiral boundary conditions. We find that the 4-divergence of the higher-dimensional current evaluated at a given point in the extra dimension is proportional to the probability of finding the chiral zero mode there. Nevertheless the anomaly, appropriately defined as the five dimensional dive

Victor O. Rivelles

We discuss some properties of noncommutative supersymmetric field theories which do not involve gauge fields. We concentrate on the renormalizability issue of these theories.

M. Caselle, M. Hasenbusch, P. Provero, K. Zarembo

We study the spectrum of massive excitations in three-dimensional models belonging to the Ising universality class. By solving the Bethe-Salpeter equation for 3D $ϕ^4$ theory in the broken symmetry phase we show that recently found non-perturbative states can be interpreted as bound states of the fundamental excitation. We show that duality predicts an exact

Stefano De Leo

We formulate Lorentz group representations in which ordinary complex numbers are replaced by linear functions of real quaternions and introduce dotted and undotted quaternionic one-dimensional spinors. To extend to parity the space-time transformations, we combine these one-dimensional spinors into bi-dimensional column vectors. From the transformation prope

P. Kosiński, J. Lukierski, P. Maślanka

We describe the extension of the Wigner`s infinite-dimensional unitary representations of Poincaré group to the case of $κ$-deformed Poincaré group. We show that the corresponding coordinate wave functions on noncommutative space-time are described by free field equations on $κ$-deformed Minkowski space. The cases of Klein--Gordon, Dirac, Proca and Maxwell f

I. Floratos, B. Piette

Following Marleau, we study an extended version of the Skyrme model to which a sixth order term has been added to the Lagrangian and we analyse some of its classical properties. We compute the multi-Skyrmion solutions numerically for up to B=5 and show that they have the same symmetries as the usual Skyrmion solutions. We use the rational map ansatz introduc

Toyoki Matsuyama, Hideko Nagahiro

The restriction of space-time dimensions to "2+1" leads us to a novel quantum field theory which has the Chern-Simons term in its action. This term changes the nature of gauge interaction by giving a so-called topological mass to a gauge field without breaking the gauge symmetry. We investigate how a dynamical mass of fermion is affected by the topol

J. W. Moffat

The unitarity condition for scattering amplitudes in a non-anticommutative quantum field theory is investigated. The Cutkosky rules are shown to hold for Feynman diagrams in Euclidean momentum space and unitarity of amplitudes can be satisfied. An analytic continuation of the diagrams to physical Minkowski spacetime can be performed without invoking unphysic

Mark Burgess, Margaret Carrington, Gabor Kunstatter

The equilibration of two coupled reservoirs is studied using a Green function approach which is suitable for future development with the closed time path method. The problem is solved in two parameterizations, in order to demonstrate the non-trivial issues of parameterization in both the intermediate steps and the interpretation of physical quantities. We us

A. Ringwald

There are definite plans for the construction of X-ray free electron lasers (FEL), both at DESY, where the so-called XFEL is part of the design of the electron-positron linear collider TESLA, as well as at SLAC, where the so-called Linac Coherent Light Source (LCLS) has been proposed. Such an X-ray laser would allow for high-field science applications: One c

D. Yu. Ivanov, L. Szymanowski

We calculate the electromagnetic contribution to the scattering amplitude of pion diffractive dissociation into di-jets which is described by one photon exchange. The result shows that the factorization procedure known for the description of exclusive reactions holds also for this quasi-exclusive process. We find that the longitudinal momentum distribution o

Fedor Simkovic, Pavol Domin, Sergey Kovalenko, Amand Faessler

We study the lepton number violating muon-positron conversion in nuclei mediated by the exchange of virtual light Majorana neutrinos. We found that a previously overlooked imaginary part of this amplitude plays an important role. The numerical calculation has been made for the experimentally interesting muon-positron conversion in Ti48 using realistic renorm

Takeshi Nihei

We study precise calculation of neutralino relic density in the minimal supergravity model. We compare the exact formula for the thermal average of the neutralino annihilation cross section times relative velocity with the expansion formula in terms of the temperature, including all the contributions to neutralino annihilation cross section analytically. We

The DELPHI Collaboration, P. Abreu

Sleptons, neutralinos and charginos were searched for in the context of scenarios where the lightest supersymmetric particle is the gravitino. It was assumed that the stau is the next-to-lightest supersymmetric particle. Data collected with the DELPHI detector at a centre-of-mass energy near 189 GeV were analysed combining the methods developed in previous s

The DELPHI Collaboration, P. Abreu

An analysis of the data collected in 1997 and 1998 with the DELPHI detector at e+e- collision energies close to 183 and 189 GeV was performed in order to extract the hadronic and leptonic fermion-pair cross-sections, as well as the leptonic forward-backward asymmetries and angular distributions. The data are used to put limit on contact interactions between

Ken Takayama, Junichi Kishiro, Makoto Sakuda, Masayoshi Wake

A novel concept of a high luminosity hadron collider is proposed. This would be a typical application of an induction synchrotron being newly developed. Extremely long bunches, referred to as superbunches, are generated by a multi- bunch stacking method employing barrier buckets at the injection into the collider, and are accelerated to the collider energy w

E. Elizalde, Sergi R. Hildebrandt

A family of spacetimes suitable for describing the matter conditions of a static, spherically symmetric quantum vacuum is studied, as well as its reliability for describing a regular model for the interior of a semiclassical, static black hole ---without ever invoking a mass shell for the final object. In paper I, this condition was seen to limit the search

Emilio Elizalde, Sergi R. Hildebrandt

A seemingly natural mechanism is proposed, that could stop the gravitational collapse of a very massive body. Without needing to change the concept of the collapsing process itself, that is, without invoking thin layers nor resorting to asymptoticity (as has been usually done in the literature), it is proven that a model can be built in which the quantum vac

Zeferino Andrade

The trapped $w$-modes of stars with a first order phase transition (a density discontinuity) are computed and the excitation of some of the modes of these stars by a perturbing shell is investigated. Attention is restricted to odd parity (``axial'') $w$-modes. With $R$ the radius of the star, $M$ its mass, $R_{i}$ the radius of the inner core and $M_

N. Obadia, R. Parentani

The Davies-Fulling (DF) model describes the scattering of a massless field by a non-inertial mirror in two dimensions. In this paper, we generalize this model in two different ways. First, we consider partially reflecting mirrors. We show that the Bogoliubov coefficients relating inertial modes can be expressed in terms of the frequency dependent reflection

Tiago C. Charters, Ana Nunes, Jose P. Mimoso

We investigate the general asymptotic behaviour of Friedman-Robertson-Walker (FRW) models with an inflaton field, scalar-tensor FRW cosmological models and diagonal Bianchi-IX models by means of Liapunov's method. This method provides information not only about the asymptotic stability of a given equilibrium point but also about its basin of attraction.

Jiangping Hu, Shou-Cheng Zhang

We study the dispersion of the $π$ resonance in the superconducting state within the projected SO(5) model\cite{project}. Away from the the commensurate momentum, the propagation of the $π$ resonance creates phase slips in the superconducting order parameter. This frustration effect leads to a strong dressing of the $π$ resonance and a downwards dispersion a

J. A. K. Freire, F. M. Peeters, V. N. Freire, G. A. Farias

The lateral magnetic confinement of quasi two-dimensional excitons into wire like structures is studied. Spin effects are take into account and two different magnetic field profiles are considered, which experimentally can be created by the deposition of a ferromagnetic stripe on a semiconductor quantum well with magnetization parallel or perpendicular to th

S. Bilke, C. Peterson

Topological properties of "scale-free" networks are investigated by determining their spectral dimensions $d_S$, which reflect a diffusion process in the corresponding graphs. Data bases for citation networks and metabolic networks together with simulation results from the growing network model \cite{barab} are probed. For completeness and comparison

José Arnaldo Redinz, Marcelo Lobato Martins

We present a numerical study of the self-affine profiles obtained from configurations of the q-state Potts (with q=2,3 and 7) and p=10 clock models as well as from the occupation states for site-percolation on the square lattice. The first and second order static phase transitions of the Potts model are located by a sharp change in the value of the roughness

Krzysztof Tatarczyk, Arno Schindlmayr, Matthias Scheffler

The performance of several common approximations for the exchange-correlation kernel within time-dependent density-functional theory is tested for elementary excitations in the homogeneous electron gas. Although the adiabatic local-density approximation gives a reasonably good account of the plasmon dispersion, systematic errors are pointed out and traced to

S. N. Gordeev, J-M. L. Beaujour, G. J. Bowden, P. A. J. de Groot

Magnetization and magnetoresistance measurements are reported for antiferromagnetically coupled DyFe$_2$/YFe$_2$ multilayers in fields up to 23 T. We demonstrate that the formation of short exchange springs (~ 2 nm) in the magnetically soft YFe$_2$ layers results in a giant magneto-resistance as high as 32% in the spring region. It is shown that both the mag

Vishal Mehra, Jayme De Luca

We perform molecular dynamics simulations on an interacting electron gas confined to a cylindrical surface and subject to a radial magnetic field and the field of the positive background. In order to study the system at lowest energy states that still carry a current, initial configurations are obtained by a special quenching procedure. We observe the format

S. Botti, L. C. Andreani

The linear combination of bulk bands method recently introduced by Wang, Franceschetti and Zunger [Phys. Rev. Lett.78, 2819 (1997)] is applied to a calculation of energy bands and optical constants of (GaAs)$_n$/(AlAs)$_n$ and (GaAs)$_n$/(vacuum)$_n$ (001) superlattices with n ranging from 4 to 20. Empirical pseudopotentials are used for the calculation of t

Y. Moreno, J. B. Gomez, A. F. Pacheco

The possible paralelism existing between phase transitions and fracture in disordered materials, is discussed using the well-known Fiber Bundle Models and a probabilistic approach suited to smooth fluctuations near the critical point. Two limiting cases of load redistribution are analyzed: the global transfer scheme, and the local transfer rule. The models a

M. V. Yakunin, G. A. Alshanskii, Yu. G. Arapov, V. N. Neverov

A negative magnetoresistance under the in-plane magnetic field, reaching maximum 30-40% of its zero-field value in fields higher than ~12 T, has been found in wide Ge_{1-x}Si_x/Ge/p-Ge_{1-x}Si_x quantum wells (QW) containing the quasi-two-dimensional hole gas. In the QWs of intermediate widths and hole densities, this negative magnetoresistance may be explai

L. Moral, Y. Moreno, J. B. Gomez, A. F. Pacheco

A time-dependent global fiber-bundle model of fracture with continuous damage is formulated in terms of a set of coupled non-linear differential equations. A first integral of this set is analytically obtained. The time evolution of the system is studied by applying a discrete probabilistic method. Several results are discussed emphasizing their differences

S. F. Edwards, D. V. Grinev

The simplest solvable problem of stress transmission through a static granular material is when the grains are perfectly rigid and have an average coordination number of $\bar{z}=d+1$. Under these conditions there exists an analysis of stress which is independent of the analysis of strain and the $d$ equations of force balance $\nabla_{j} σ_{ij}({\vec r}) =

Peter Olsson

The anomalous dimension of the lattice London superconductor is determined from finite size scaling of the susceptibility to be η_ϕ= -0.79(1). Indirect determinations of η_ϕfrom properties of the vortex loops in the 3D XY model are also attempted, but it is found that the results are sensitive to details in the simulations related to vortex loop intersection

M. V. Yakunin, G. A. Alshanskii, Yu. G. Arapov, G. I. Harus

We have measured the temperature (0.1 < T < 15 K) and magnetic field (0 < B < 32 T) dependences of longitudinal and Hall resistivities for the p-Ge_{1-x}Si_x/Ge, x=~0.07, multilayers with different Ge layer widths 10 < d_w < 38 nm and hole densities p_s = (1-5)x10^{15} m^{-2}. An extremely high sensitivity of the experimental data [the structure of magnetore

M. Abolfath, T. Jungwirth, A. H. MacDonald

We present a mean-field theory of carrier-induced ferromagnetism in Mn$_x$III$_{1-x}$V diluted magnetic semiconductors with a special emphasis placed on the magnetic anisotropy. The valence band holes are described using the six band Kohn-Luttinger model. We find that the magnetic anisotropy is a complicated function of sample parameters such as hole density

T. Jungwirth, Byounghak Lee, A. H. MacDonald

The mean-field theory represents a useful starting point for studying carrier-induced ferromagnetism in Mn$_x$III$_{1-x}$V diluted magnetic semiconductors. A detail description of these systems requires to include correlations in the many-body hole system. We discuss the effects of correlations among itinerant carriers on magnetic properties of bulk Mn$_x$II

T. Jungwirth, A. H. MacDonald, L. Smrčka, S. M. Girvin

A strong anisotropy in the longitudinal resistivity of a 2D electron system has been observed at half-filled high Landau levels. We report on detailed Hartree-Fock calculations of the unidirectional charge density wave (UCDW) orientation energy induced by a tilted magnetic field. We find that stripes can orient both parallel or perpendicular to the in-plane

K. -I. Goh, B. Kahng, D. Kim

We study the spectra and eigenvectors of the adjacency matrices of scale-free networks when bi-directional interaction is allowed, so that the adjacency matrix is real and symmetric. The spectral density shows an exponential decay around the center, followed by power-law long tails at both spectrum edges. The largest eigenvalue λ_1 depends on system size N a

Zi-Kui Liu, D. G. Schlom, Qi Li, X. X. Xi

We have studied thermodynamics of the Mg-B system with the modeling technique CALPHAD using a computerized optimization procedure. Temperature-composition, pressure-composition, and pressure-temperature phase diagrams under different conditions are obtained. The results provide helpful insights into appropriate processing conditions for thin films of the sup

Rahul Siddharthan, Antoine Georges

We introduce a two dimensional network of corner-sharing triangles with square lattice symmetry. Properties of magnetic systems here should be similar to those on the kagome lattice. Focusing on the spin half Heisenberg quantum antiferromagnet, we generalise the spin symmetry group from SU(2) to SU(N). In the large N limit, we map the model exactly to the ei

Sun Hong Rhie

Galactic Exoplanet Survey Telescope (GEST) was proposed for a discovery mission to search for microlensing terrestrial planets toward the Galactic bulge and also Kuiper Belt Objects (KBOs) that are believed to hold vital information of the early history of the solar system. Earth mass planets require massive survey, angular resolution, temporal resolution, a

M. J. I. Brown, B. J. Boyle, R. L. Webster

Galaxies in the environments of 69 0.2<z<0.7 UBR selected AGN have been imaged to Bj~23.5. By applying photometric redshifts and color selection criteria to the galaxy catalogue, the AGN-galaxy cross-correlation function has been measured as a function of galaxy type. The spatial cross-correlation of AGN with red (early-type) galaxies is comparable to the au

M. S. Marley, A. S. Ackerman

Clouds and hazes are important throughout our solar system and in the atmospheres of brown dwarfs and extrasolar giant planets. Among the brown dwarfs, clouds control the colors and spectra of the L-dwarfs; the disappearance of clouds helps herald the arrival of the T-dwarfs. The structure and composition of clouds will be among the first remote-sensing resu

C. M. Olbert, C. R. Clearfield, N. E. Williams, J. W. Keohane

We present spectra and high resolution images of the hard X-ray feature along the southern edge of the supernova remnant IC443. Data from the Chandra X-ray Observatory reveal a comet-shaped nebula of hard emission, which contains a softer point source at its apex. We also present 20cm, 6cm, and 3.5cm images from the Very Large Array that clearly show the com

J. P. Willis, P. C. Hewett, S. J. Warren

We have compiled a sample of $\sim 9600$ bright, $i\le 18.95$, red, $b_j-r>2$, candidate galaxies in an area of 220 deg$^2$. These are luminous, $L > L^*$, field early-type galaxies with redshifts $0.3 \la z \la 0.6$. We present a redshift catalogue of a sub-sample of 581 targets. The galaxies were selected according to their broadband $b_jri$ colours from U

Andy Thean, Alan Pedlar, Marek J. Kukula, Stefi A. Baum

We discuss the properties of compact nuclear radio components in Seyfert galaxies from the extended 12-micron AGN sample of Rush et al.(1993). Our main results can be summarised as follows. Type 1 and type 2 Seyferts produce compact radio components which are indistinguishable in strength and aspect, indicating that their central engines are alike as propose

Ronak Y. Shah, H. Alwyn Wootten

We report on a survey of \nh2d towards protostellar cores in low-mass star formation and quiescent regions in the Galaxy. Twenty-three out of thirty-two observed sources have significant ($\gsim 5σ$) \nh2d emission. Ion-molecule chemistry, which preferentially enhances deuterium in molecules above its cosmological value of \scnot{1.6}{-5} sufficiently explai

H. R. Schmitt, R. R. J. Antonucci, J. S. Ulvestad, A. L. Kinney

We present a series of statistical tests done to a sample of 29 Seyfert 1 and 59 Seyfert 2 galaxies selected from mostly isotropic properties, their far infrared fluxes and warm infrared colors. Such selection criteria provide a profound advantage over the criteria used by most investigators in the past, such as ultraviolet excess. These tests were done usin

P. R. Young, A. K. Dupree, B. E. Wood, S. Redfield

Far Ultraviolet Spectroscopic Explorer FUSE observations of the bright binary system Capella (Alpha Aurigae; G1 III + G8 III) reveal a rich emission line spectrum containing neutral and ionic species, among them H I, O I, C III, O VI, S VI, Ne V and Ne VI. In addition the Fe XVIII 974.85 A line, formed at temperatures of approx. 6 x 10^6 K, is detected. Wher

S. Randich, R. Pallavicini, G. Meola, J. R. Stauffer

We present lithium abundances for ~50 X-ray selected candidate members of the 30-50 Myr old open clusters IC 2602 and IC 2391. These data enlarge and extend to cooler temperatures previous Li surveys of these clusters by Stauffer et al. (1989) and Randich et al. (1997). We also give for the first time an estimate of the metallicity of the two clusters which

I. A. Steele, J. S. Clark

We present H band (1.53 - 1.69 micron) spectra of 57 isolated Be stars of spectral types O9-B9 and luminosity classes III,IV & V. The HI Brackett (n-4) series is seen in emission from Br 11-18, and FeII emission is also apparent for a subset of those stars with HI emission. No emission from species with a higher excitation temperature, such as He II or CIII

Raul Jimenez, David Band, Tsvi Piran

We determine the distribution of total energy emitted by gamma-ray bursts for bursts with fluences and distance information. Our core sample consists of eight bursts with BATSE spectra and spectroscopic redshifts. We extend this sample by adding four bursts with BATSE spectra and host galaxy R magnitudes. From these R magnitudes we calculate a redshift proba

A. Arellano Ferro, Sunetra Giridhar, P. Mathias

Detailed atmospheric abundances have been calculated for a sample of A-G supergiant stars with IR fluxes and/or high galactic latitudes. HD 172481 and HD 158616 show clear indications of being post-AGB stars that have experienced third dredge-up. HD 158616 is carbon-rich while the abundance pattern of HD 172481 and its large Li enhancement gives support to t

Melinda L. Weil, Ralph E. Pudritz

In an exploration of the birthplaces of globular clusters, we present a careful examination of the formation of self-gravitating gas clouds within assembling dark matter haloes in a hierarchical cosmological model. Our high-resolution smoothed particle hydrodynamical simulations are designed to determine whether or not hypothesized supergiant molecular cloud

Daniel E. Reichart, Donald Q. Lamb

We present a possible Cepheid-like luminosity estimator for the long-duration gamma-ray bursts based on the variability of their light curves.

Sergiu I. Vacaru, D. Singleton, Vitalie A. Botan, Denis A. Dotenco

In this article we examine a class of wormhole and flux tube like solutions to 5D vacuum Einstein equations. These solutions possess generic local anisotropy, and their local isotropic limit is shown to be conformally equivalent to the spherically symmetric 5D solutions of gr-qc/9807086. The anisotropic solutions investigated here have two physically distinc

J. L. Diaz-Cruz, Hong-Jian He, C. -P. Yuan

The squark mass-matrix from the soft supersymmetry (SUSY) breaking sector contains a rich flavor-mixing structure that allows O(1) mixings among top- and charm-squarks while being consistent with all the existing theoretical and experimental bounds. We formulate a {\it minimal} flavor-changing-neutral current scheme in which the squark mixings arise from the

PACS Collaboration, T. Manke, A. Ali Khan, S. Aoki

We present a dynamical lattice calculation with 2 flavours for bottomonium states with an additional gluonic excitation. Using improved actions for the quarks and gauge fields at a lattice spacing of $a \approx 0.1$ fm, we find 10.977(61)(62) GeV for the energy of the lowest lying $b\bar bg$-hybrid, where the first error is statistical and the second denotes

Kayll Lake

The bending of light in Kottler space (the Schwarzschild vacuum with cosmological constant) is examined. Unlike the advance of the perihelion, the cosmological constant produces no change in the bending of light. In this note we examine the conditions under which this statement holds.

A. De Castro, A. Restuccia

A complete analysis of the canonical structure for a gauge fixed PST bosonic five brane action is performed. This canonical formulation is quadratic in the dependence on the antisymmetric field and it has second class constraints. We remove the second class constraints and a master canonical action with only first class constraints is proposed. The nilpotent

Eric Braaten, H. -W. Hammer

An effective field theory for the three-body system with large scattering length a is applied to three-body recombination into deep bound states in a Bose gas. The recombination constant αis calculated to first order in the short-distance interactions that allow the recombination. For a < 0, the dimensionless combination m α/(\hbar a^4) is a periodic functio

Feryal Ozel

We construct radiative equilibrium models for strongly magnetized (B > 10^13 G) neutron-star atmospheres taking into account magnetic free-free absorption and scattering processes computed for two polarization modes. We include the effects of vacuum polarization in our calculations. We present temperature profiles and the angle-, photon energy-, and polariza

S. Franz, M. Leone, F. Ricci-Tersenghi, R. Zecchina

We study the low temperature properties of p-spin glass models with finite connectivity and of some optimization problems. Using a one-step functional replica symmetry breaking Ansatz we can solve exactly the saddle-point equations for graphs with uniform connectivity. The resulting ground state energy is in perfect agreement with numerical simulations. For