July 2001 arXiv papers

D. A. Demir, K. A. Olive

We discuss B -> X_s gamma decay in both constrained and unconstrained supersymmetric models with explicit CP violation within the minimal flavor violation scheme by including tan(beta) -enhanced large contributions beyond the leading order. In this analysis, we take into account the relevant cosmological and collider bounds, as well as electric dipole moment

Lawrence Hall, Yasunori Nomura, David Smith

The electroweak Higgs doublets are identified as components of a vector multiplet in a higher dimensional supersymmetric field theory. We construct a minimal model in 6D where the electroweak $SU(2) \otimes U(1)$ gauge group is extended to SU(3), and unified 6D models with the unified SU(5) gauge symmetry extended to SU(6). In these realistic theories the ex

Bogdan Morariu

We formulate Poisson Chern-Simons gauge theories on compact group manifolds. These describe a sector of the large representation limit of noncommutative Chern-Simons in the same way as the light-cone formulation of the membrane action describe a sector of the large N Matrix model. While the formulation we give is on a group manifold, only excitations that ar

Karl Martel, Eric Poisson

A one-parameter family of time-symmetric initial data for the radial infall of a particle into a Schwarzschild black hole is constructed within the framework of black-hole perturbation theory. The parameter measures the amount of gravitational radiation present on the initial spacelike surface. These initial data sets are then evolved by integrating the Zeri

J. M. Tranquada, K. Nakajima, M. Braden, L. Pintschovius

We report a neutron scattering study of bond-stretching phonons in La(1.69)Sr(0.31)NiO(4), a doped antiferromagnet in which the added holes order in diagonal stripes at 45 deg to the Ni-O bonds. For the highest-energy longitudinal optical mode along the bonds, a softening of 20% is observed between the Brillouin zone center and zone boundary. At 45 deg to th

M. J. Fox, A. Efstathiou, M. Rowan-Robinson, J. S Dunlop

We present the results of a multi-wavelength study of the 19 most significant sub-mm sources detected in the SCUBA 8-mJy survey. As described in Scott et al. (2001), this survey covers ~260 arcmin^2 using the sub-millimetre camera SCUBA, to a limiting source detection limit S(850um) ~ 8 mJy. One advantage of this relatively bright flux-density limit is that

Tarek Ibrahim, Pran Nath

A brief overview is given of recent developments in the analyses of large phases and CP violation in supersymmetric unified models. The problem of experimental electric dipole moment constraints and large phases is discussed. Implications of large phases on supersymmetric phenomena are reviewed. The possibility of generating a muon electric dipole moment muc

Antonio C da Silva, Scott T Kay, Andrew R Liddle, Peter A Thomas

We use hydrodynamical simulations to assess the impact of radiative cooling and `pre-heating' on predictions for the Sunyaev--Zel'dovich (SZ) effect. Cooling significantly reduces both the mean SZ signal and its angular power spectrum, while pre-heating can give a higher mean distortion while leaving the angular power spectrum below that found in a s

J. Portoles, P. D. Ruiz-Femenia

Recently Groote and Pivovarov have given notice of a possible fault in the use of sum rules involving two-point correlation functions to extract information on heavy quark parameters, due to the presence of massless contributions that invalidate the construction of moments of the spectral densities. Here we show how to circumvent this problem through a new d

Lotfi Boubekeur, Gianmassimo Tasinato

In supersymmetric theories, the occurrence of universal singlets is a delicate issue, because they usually induce tadpoles that destabilize the hierarchy. We study the effects of these tadpoles in supersymmetric hybrid inflation models. The resulting scenario is generically modified, but it is still possible to achieve inflation in a natural way. It is argue

Daniel Wojcik, Karol Zyczkowski

We prove the theorem announced in Phys. Rev. Lett. {\bf 85}:5022, 2001 concerning the existence and properties of fractal states for the Schrödinger equation in the infinite one-dimensional well.

Gianguido Dall'Agata

We discuss the compactification of type IIB supergravity on a Calabi-Yau manifold in the presence of both RR and NS fluxes for the three-form fields. We obtain the classical potential both by direct compactification and by using the techniques of N=2 gauged supergravity in four-dimensions. We briefly discuss the properties of such potential and compare the r

Michael Dine

With our current level of understanding, the problem of making string theory predictions is not one of "solving" the theory, but rather of trying to determine whether there are any generic expectations. Within this context, we discuss what it would mean to predict low energy supersymmetry, and consider questions like: what is the form of low energy C

M. G. Santos, A. Balbi, J. Borrill, P. G. Ferreira

We use the measurement of the cosmic microwave background taken during the MAXIMA-1 flight to estimate the bispectrum of cosmological perturbations. We propose an estimator for the bispectrum that is appropriate in the flat sky approximation, apply it to the MAXIMA-1 data and evaluate errors using bootstrap methods. We compare the estimated value with what w

Dong-Sheng Du, Chao-Shang Huang, Zheng-Tao Wei, Mao-Zhi Yang

The end-point singularity is an unsolved problem in BBNS approach. Incorporating the partonic transverse momentum and the Sudakov form factor, this problem can be solved model-independently. We discuss the Sudakov effects in BBNS approach. The BBNS approach is compared with the modified PQCD approach. The main idea of Sudakov form factor is briefly discussed

J. F. de Troconiz, F. J. Yndurain

We perform a new, detailed calculation of the hadronic contributions to the running electromagnetic coupling, $\barα$, defined on the Z particle (91 GeV). We find for the hadronic contribution, including radiative corrections, $$10^5\times \deltav_{\rm had.}α(M_Z^2)= 2740\pm12,$$ or, excluding the top quark contribution, $$10^5\times \deltav_{\rm had.}α^{(5)

J. L. Han, Z. G. Deng, Z. L. Zou, X. B. Wu

The fundamental plane of spiral galaxies was searched from observational data, which can be approximately represented in observational parameters by $ L \propto V^2 R $, where $L$, $R$, and $V$ are the luminosity, the linear size of galactic disk, and the rotation velocity. This plane exists at all optical bands in our samples of more than 500 spiral galaxie

A. Mosk, S. Kraft, M. Mudrich, K. Singer

We present the first simultaneous trapping of two different ultracold atomic species in a conservative trap. Lithium and cesium atoms are stored in an optical dipole trap formed by the focus of a CO$_2$ laser. Techniques for loading both species of atoms are discussed and observations of elastic and inelastic collisions between the two species are presented.

O. Blanch, M. Martinez

The physics potential of the next generation of Gamma Ray Telescopes in exploring the Gamma Ray Horizon is discussed. It is shown that the reduction in the Gamma Ray detection threshold might open the window to use precise determinations of the Gamma Ray Horizon as a function of the redshift to either put strong constraints on the Extragalactic Background Li

M. I. Muradov

The acoustic phonon-mediated drag-contribution to the drag current created in the ballistic transport regime in a one-dimensional nanowire by phonons generated by a current-carrying ballistic channel in a nearby nanowire is calculated. The threshold of the phonon-mediated drag current with respect to bias or gate voltage is predicted.

I. B. Khriplovich, R. V. Korkin

Nonthermal radiation of a Kerr black hole is considered as tunneling of created particles through an effective Dirac gap. In the leading semiclassical approximation this approach is applicable to bosons as well. Our semiclassical results for photons and gravitons do not contradict those obtained previously. For neutrinos the result of our accurate quantum me

A. Djouadi, M. Drees, J. L. Kneur

We perform a complete analysis of the supersymmetric particle spectrum in the Minimal Supergravity (mSUGRA) model where the soft SUSY breaking scalar masses, gaugino masses and trilinear couplings are unified at the GUT scale, so that the electroweak symmetry is broken radiatively. We show that the present constraints on the Higgs boson and superparticle mas

Sven Zschocke, Guenter Plunien, Gerhard Soff

The renormalization method of Bogoljubov-Parasiuk-Hepp-Zimmermann (BPHZ) is used in order to derive the renormalized energy shift due to the gauge invariant Källén-Sabry diagram of the two-photon vacuum polarization (VPVP) as well as the self energy vacuum polarization S(VP)E beyond the Uehling approximation. It is outlined, that no outer renormalization is

J. V. Selinger, P. J. Collings, R. Shashidhar

An unresolved issue in the theory of liquid crystals is the molecular basis of the electroclinic effect in the smectic-A phase. Recent x-ray scattering experiments suggest that, in a class of siloxane-containing liquid crystals, an electric field changes a state of disordered molecular tilt in random directions into a state of ordered tilt in one direction.

Nobuhiro Maekawa

Recently we proposed an attractive scenario of grand unified theories with anomalous $U(1)_A$ gauge symmetry, in which doublet-triplet splitting is naturally realized in SO(10) unification using Dimopoulos-Wilczek mechanism and realistic quark and lepton mass matrices can be obtained in a simple way. In this paper we show that there is a mechanism in which t

Wolfgang Tittel, Gregor Weihs

Entanglement is at the heart of fundamental tests of quantum mechanics like tests of Bell-inequalities and, as discovered lately, of quantum computation and communication. Their technological advance made entangled photons play an outstanding role in entanglement physics. We give a generalized concept of qubit entanglement and review the state of the art of

Frank Verstraete, Jeroen Dehaene, Bart De Moor

The basic question that is addressed in this paper is finding the closest separable state for a given entangled state, measured with the Hilbert Schmidt distance. While this problem is in general very hard, we show that the following strongly related problem can be solved: find the Hilbert Schmidt distance of an entangled state to the set of all partially tr

Dagomir Kaszlikowski, Marek Zukowski, Piotr Gnacinski

We show using a numerical approach that gives necessary and sufficient conditions for the existence of local realism, that the bound entangled state presented in Bennett et. al. Phys. Rev. Lett. 82, 5385 (1999) admits a local and realistic description. We also find the lowest possible amount of some appropriate entangled state that must be ad-mixed to the bo

Rainer E. Zimmermann

Based on the foundational aspects which have been discussed as consequences of ongoing research on loop quantum gravity in the first part of this paper, the holistic aspects of the latter are discussed in this second part, aiming at a consistent and systematic approach to eventually model a hierarchically ordered architecture of the world which is encompassi

A. Feigel, Z. Kotler, B. Sfez

A technique for obtaining efficient bulk second order susceptibility in non centro-symmetric Photonic Crystals (PC) made from centro-symmetric materials is discussed. The effect is based on the electric quadrupole effect, strong electromagnetic mode deformation and non homogeneous contribution to volume polarization from different parts of the PC. The requir

Arvinder Singh Sandhu, Aditya Dharmadhikari, Paramel Pattathil Rajeev, G. Ravindra Kumar

We report the first femtosecond resolved evolution of the giant magnetic field in a solid plasma, produced by a 100 fs, 10^16 W cm^-2, 806 nm laser field, using a pump-probe Faraday rotation technique.

D. Tsiklauri, I. Beresnev

We analyzed effects of elasticity on the dynamics of fluids in porous media by studying a flow of a Maxwell fluid in a tube, which oscillates longitudinally and is subject to oscillatory pressure gradient. The present study investigates novelties brought about into the classic Biot's theory of propagation of elastic waves in a fluid-saturated porous soli

D. Tsiklauri, I. Beresnev

We analyzed the effect of viscoelasticity on the dynamics of fluids in porous media by studying the flow of a Maxwell fluid in a circular tube, in which the flow is induced by a wave traveling on the tube wall. The present study investigates novelties brought about into the classic peristaltic mechanism by inclusion of non-Newtonian effects that are importan

F. V. Andreev, A. V. Kitaev

Compositions of rational transformations of independent variables of linear matrix ordinary differential equations (ODEs) with the Schlesinger transformations ($RS$-transformations) are used to construct algebraic solutions of the sixth Painlevé equation. $RS$-Transformations of the ranks 3 and 4 of $2\times2$ matrix Fuchsian ODEs with 3 singular points into

Dietrich Stauffer, M. E. J. Newman

We study the simple evolutionary process in which we repeatedly find the least fit agent in a population of agents and give it a new fitness which is chosen independently at random from a specified distribution. We show that many of the average properties of this process can be calculated exactly using analytic methods. In particular we find the distribution

H. Arbell, J. Fineberg

We present an experimental investigation of superlattice patterns generated on the surface of a fluid via parametric forcing with 2 commensurate frequencies. The spatio-temporal behavior of 4 qualitatively different types of superlattice patterns is described in detail. These states are generated via a number of different 3--wave resonant interactions. They

Wen-Xiu Ma, Xianguo Geng

Binary symmetry constraints are applied to constructing Bäcklund transformations of soliton systems, both continuous and discrete. Construction of solutions to soliton systems is split into finding solutions to lower-dimensional Liouville integrable systems, which also paves a way for separation of variables and exhibits integrability by quadratures for soli

L. R. U. Manssur, R. Portugal

Computational Group Theory is applied to indexed objects (tensors, spinors, and so on) with dummy indices. There are two groups to consider: one describes the intrinsic symmetries of the object and the other describes the interchange of names of dummy indices. The problem of finding canonical forms for indexed objects with dummy indices reduces to finding do

R. Portugal, B. F. Svaiter

We describe how Computational Group Theory provides tools for manipulating tensors in explicit index notation. In special, we present an algorithm that puts tensors with free indices obeying permutation symmetries into the canonical form. The method is based on algorithms for determining the canonical coset representative of a subgroup of the symmetric group

Peter Scott, Gadde Swarup

We introduce the notion of a `canonical' splitting over Z or ZxZ for a finitely generated group G. We show that when G happens to be the fundamental group of an orientable Haken manifold M with incompressible boundary, then the decomposition of the group naturally obtained from canonical splittings is closely related to the one given by the standard JSJ-

R. M. Green

We introduce tabular algebras, which are simultaneous generalizations of cellular algebras (in the sense of Graham-Lehrer) and table algebras (in the sense of Arad-Blau). We show that if a tabular algebra is equipped with a certain kind of trace map then the algebra has a corresponding asymptotic version whose structure can be explicitly determined. We also

Alexander Soshnikov

We consider a sparse random subraph of the $n$-cube where each edge appears independently with small probability $p(n) =O(n^{-1+o(1)})$. In the most interesting regime when $p(n)$ is not exponentially small we prove that the largest eigenvalue of the graph is asymtotically equal to the square root of the maximum degree.

Robert L. Bryant

This article is an exposition of four loosely related remarks on the geometry of Finsler manifolds with constant positive flag curvature. <p> The first remark is that there is a canonical Kahler structure on the space of geodesics of such a manifold. <p> The second remark is that there is a natural way to construct a (not necessarily complete) Finsler n-mani

Hjalmar Rosengren

We define a natural concept of duality for the h-Hopf algebroids introduced by Etingof and Varchenko. We prove that the special case of the trigonometric SL(2) dynamical quantum group is self-dual, and may therefore be viewed as a deformation both of the function algebra F(SL(2)) and of the enveloping algebra U(sl(2)). Matrix elements of the self-duality in

B. C. Ngô, A. Genestier

We study the relation between the $p$-rank of abelian varieties in characteristic $p$ and the Kottwitz-Rapoport&#39;s stratification of the special fiber modulo $p$ of the moduli space of principally polarized abelian varieties with Iwahori type level structure on $p$. In particular, the density of the ordinary locus in that special fiber is proved.

Iain Raeburn, Aidan Sims, Trent Yeend

We consider the higher-rank graphs introduced by Kumjian and Pask as models for higher-rank Cuntz-Krieger algebras. We describe a variant of the Cuntz-Krieger relations which applies to graphs with sources, and describe a local convexity condition which characterises the higher-rank graphs that admit a nontrivial Cuntz-Krieger family. We then prove versions

Grigory Litvinov, Viktor Maslov, Grigory Shpiz

In this paper we consider Idempotent Functional Analysis, an `abstract&#39; version of Idempotent Analysis developed by V. P. Maslov and his collaborators. We give a review of the basic ideas of Idempotent Analysis. The correspondence between concepts and theorems of the traditional Functional Analysis and its idempotent version is discussed; this correspond

Dominic Joyce

This is the first in a series of papers on special Lagrangian submanifolds in C^m. We study special Lagrangian submanifolds in C^m with large symmetry groups, and give a number of explicit constructions. Our main results concern special Lagrangian cones in C^m invariant under a subgroup G in SU(m) isomorphic to U(1)^{m-2}. By writing the special Lagrangian e

Ping Xu

We provide a general study for triangular dynamical r-matrices using Poisson geometry. We show that a triangular dynamical r-matrix always gives rise to a regular Poisson manifold. Using the Fedosov method, we prove that non-degenerate (i.e., the corresponding Poisson manifolds are symplectic) triangular dynamical r-matrices (over $ \frakh^* $ and valued in

Jacek Pawelczyk, Harold Steinacker

We discuss a matrix model for D0-branes on S^3 \times M^7 based on quantum group symmetries. For finite radius of S^3 (i.e. for finite k), it gives results beyond the reach of the ordinary matrix model. For large k all known static properties of branes on S^3 are reproduced.

Clifford V. Johnson, Kenneth J. Lovis, David C. Page

We study the metrics on the families of moduli spaces arising from probing with a brane the ten and eleven dimensional supergravity solutions corresponding to renormalisation group flows of supersymmetric large n gauge theory. In comparing the geometry to the physics of the dual gauge theory, it is important to identify appropriate coordinates, and starting

Simeon Hellerman, Leonard Susskind

In a recent paper Bernevig, Brodie, Susskind and Toumbas constructed a brane realization of the Quantum Hall fluid. Since then it has been realized that the Quantum Hall system is very closely related to non--commutative Chern Simons theory and this suggests alternative brane constructions which we believe are more reliable and clear. In this paper a brane c

H. Leutwyler

The role of the quark condensate for the low energy structure of QCD is discussed in some detail. In particular, the dependence of M_pi on m_u and m_d and the low energy theorems for the pi-pi scattering amplitude are reviewed. The new data on Ke4 decay beautifully confirm the standard picture, according to which the quark condensate is the leading order par

N. Paver, Riazuddin

We study the D^{+} -> sigma pi^{+}, D^{+} -> rho^0 pi^{+}, B^{-} -> sigma pi^{-}, B^{-} -> rho^0 pi^{-} and \bar{B}^0 -> rho^{\pm} pi^{\mp} decays in a valence quark triangle model, incorporating chiral symmetries. We find a good agreement with recent experimental data for D^{+} -> sigma pi^{+} and for D^{+} -> rho^0 pi^{+}. We point out that a &#34;long-dis

Savely G. Karshenboim, Valery A. Shelyuto

We discuss hadronic effects in the muonium hyperfine structure and derive an expression for the hadronic contribution to the hfs interval in form of the one-dimensional integral of the cross section of e+e- annihilation into hadrons. Higher-order hadronic contributions are also considered.

Andrzej Czarnecki, Simon I. Eidelman, Savely G. Karshenboim

A new result for the hadronic vacuum polarization correction to the muonium hyperfine splitting (HFS) is presented: Delta nu(had - vp) = (0.233 +- 0.003) kHz. Compared with previous calculations, the accuracy is improved by using the latest data on e+e- -> hadrons. The status of the QED prediction for HFS is discussed.

F. Mamedov

The Standard Model amplitudes for processes where one or more gauge bosons are emitted exhibit zeros in the angular distributions. The theoretical and experimental aspects of these radiation amplitude zeros are reviewed and some recent results are discussed. In particular, the zeros of the $WZγ$ and $WZZ$ production amplitudes are analyzed. It is briefly exp

Vicente Vento

The role of models in Quantum Chromodynamics is to produce simple physical pictures that connect the phenomenological regularities with the underlying structure. The static properties of hadrons have provided experimental input to define a variety of very succesful Quark Models. We discuss applications of some of the most widely used of these models to the h

Hakan Ciftci, Saleh Sultansoy

The properties of new heavy mesons containing new heavy quarks have been investigated. As an example, the fourth SM family quarks and weak isosinglet quarks predicted by E_{6} GUT are considered. Production of these hadrons at TeV energy lepton colliders have been analyzed.

N. Armesto, E. G. Ferreiro, F. del Moral, C. Pajares

We study the enhancement of $c \bar c$ pair production that takes place in central heavy ion collisions due to the formation of clusters of strings. These clusters produce heavy flavors more efficiently due to their higher color. We discuss the competition between this mechanism and the well-known screening of color charge, which, above a critical string den

J. Blümlein, H. Böttcher

A QCD analysis of the world data on inclusive polarized deep inelastic scattering of leptons on nucleons is presented in leading and next-to-leading order. New parameterizations are derived for the quark and gluon distributions and the value of $α_s(M_Z)$ is determined. Emphasis is put on the derivation of fully correlated error bands for these distributions

Tomohiro Matsuda

We consider the scenario of electroweak baryogenesis mediated by cosmological defect in models of supersymmetry breaking. When the effective electroweak breaking scale is raised in the defect configuration, the mechanism of electroweak baryogenesis works at a higher energy scale. The baryon charge produced by the mechanism is captured in the defect, protecte

S. Mishima

We calculate the branching ratios and CP asymmetries of the $B\to ϕK$ decays using perturbative QCD approach, which includes $k_T$ and threshold resummations. Our results of branching ratios are consistent with the experimental data and larger than those obtained from the naive factorization assumption and the QCD-improved factorization approach.

Fulvia De Fazio

I briefly describe recent developments in the theoretical analysis of non leptonic and semileptonic B decays. For non leptonic transitions, I focus on factorization, from the naive formulation to the most recent achievements. As for semileptonic decays, I mainly consider B transitions to excited charmed states.

Christopher Kolda, William Lahneman

Recent observations indicate that the universe&#39;s expansion has been accelerating of late. But recent theoretical work has highlighted the difficulty of squaring acceleration with the underlying assumptions of string theory, disfavoring most models of quintessence. because they predict eternal acceleration. We show that one of the simplest and most motiva

Fulvia De Fazio, M. R. Pennington

We use QCD sum-rules to study the decays $ϕ\to ηγ$ and $ϕ\to η^\prime γ$, obtaining ${\cal B}(ϕ\to ηγ)=(1.15 \pm 0.2) 10^{-2}$ and ${\cal B}(ϕ\to η^\prime γ)=(1.18 \pm 0.4) 10^{-4}$, in very good agreement with existing experimental data. We also discuss the issue of $η-η^\prime$ mixing, predicting the $η$ and $η^\prime$ decay constants in a mixing scheme in

K. Jakobs

In the final run in the year 2000 the four experiments at the electron positron collider LEP have accumulated data corresponding to an integrated luminosity of more than 210 pb-1 per experiment at centre-of-mass energies up to 208 GeV. These data have been used to extend the search for supersymmetric particles in the new energy domain. In the present paper t

K. Abe

We present a preliminary measurement of the ratio of $D^0$ decay rates into $K^0_L π^0$ and $K^0_S π^0$ final states. This ratio can be used to disentangle the Cabibbo favored $D^0 \to \bar{K}^0π^0$ and doubly Cabibbo suppressed $D^0 \to K^0 π^0$ amplitudes, and contributes to the important goal of constraining the strong phase $δ_{K π}$ between $D^0 \to K^-

B. Aubert

Using about 23M $B \bar B$ events collected in 1999-2000 with the BABAR detector, we report the observation of several hundred $B \to D^{(*)}\bar D^{(*)}K$ decays with two completely reconstructed D mesons. The preliminary branching fractions of the low background decay modes $B^0\to D^{*-}D^{(*)0}K^+$ are determined to be ${\cal B}(B^0 \to D^{*-}D^{0}K^+) =

E. Coccia, M. Gasperini, C. Ungarelli

We analyze the signal-to-noise ratio for a relic background of scalar gravitational radiation composed of massive, non-relativistic particles, interacting with the monopole mode of two resonant spherical detectors. We find that the possible signal is enhanced with respect to the differential mode of the interferometric detectors. This enhancement is due to:

Petr Hajicek, Claus Kiefer

We discuss a model describing exactly a thin spherically symmetric shell of matter with zero rest mass. We derive the reduced formulation of this system in which the variables are embeddings, their conjugate momenta, and Dirac observables. A non-perturbative quantum theory of this model is then constructed, leading to a unitary dynamics. As a consequence of

Spiros Cotsakis, John Miritzis

We examine theories of gravity which include finitely many coupled scalar fields with arbitrary couplings to the curvature (wavemaps). We show that the most general scalar-tensor $σ$-model action is conformally equivalent to general relativity with a minimally coupled wavemap with a particular target metric. Inflation on the source manifold is then shown to

Hideo Iguchi, Tomohiro Harada

The behaviors of quantum stress tensor for the scalar field on the classical background of spherical dust collapse is studied. In the previous works diverging flux of quantum radiation was predicted. We use the exact expressions in a 2D model formulated by Barve et al. Our present results show that the back reaction does not become important during the semic

M. Sami

We study the evolution of universe with a single scalar field of constant potential minimally coupled to gravity in the brane world cosmology.We find an exact inflationary solution which is not in slow roll.We discuss the limiting cases of the solution.We show that at late times the solution is asymptotic to the de Sitter solution independently of the brane

A. G. Grozin

GNU TeXmacs is a free wysiwyg word processor providing an excellent typesetting quality of texts and formulae. It can also be used as an interface to Computer Algebra Systems (CASs). In the present work, interfaces to three general-purpose CASs have been implemented.

Zbigniew Lonc, Miroslaw Truszczynski

A decision problem is called parameterized if its input is a pair of strings. One of these strings is referred to as a parameter. The problem: given a propositional logic program P and a non-negative integer k, decide whether P has a stable model of size no more than k, is an example of a parameterized decision problem with k serving as a parameter. Paramete

J. M. Lawrence, T. Ebihara, P. S. Riseborough, C. H. Booth

Experimental results for the susceptibility, specific heat, 4f occupation number, Hall effect and magnetoresistance for single crystals of YbAl$_{3}$ show that, in addition to the Kondo energy scale $k_{B}T_{K}$ $% \sim $ 670K, there is a low temperature scale $T_{coh}<50$K for the onset of coherence. Furthermore the crossover from the low temperature Fermi

A. B. Dzyubenko, A. Yu. Sivachenko

The implications of magnetic translations for internal optical transitions of charged mobile electron-hole ($e$--$h$) complexes and ions in a uniform magnetic field $B$ are discussed. It is shown that transitions of such complexes are governed by a novel exact selection rule. Internal intraband transitions of two-dimensional (2D) charged excitons $X^-$ in st

Tomohiro Shibata, Bruce Bunker, John Mitchell, Peter Schiffer

X-ray absorption fine structure measurements of the Sr and La K edges of the solid solution La(1-x)Sr(x)MnO(3) reveal a consistent deviation from a random distribution of Sr at the La/Sr sites for x~0.3. Local structural disorder on the cation sublattice in the low-x samples is also observed to differ in the vicinity of the La-rich and Sr-rich clusters. The

X. H. Zheng

MgB_2 is considered as a binary system with 2D electrons. The classic BCS theory is applied to this system. The transition temperature is found to be relatively high, because 2D electrons are more capable of moving with the atoms, on top of other features of this system to enhance the electron-phonon interaction. This system may also shed light on the nature

S. Biermann, A. Georges, A. Lichtenstein, T. Giamarchi

We investigate a system of one dimensional Hubbard chains of interacting fermions coupled by inter-chain hopping. Using a generalization of the Dynamical Mean Field Theory we study the deconfinement transition from a Mott insulator to a metal and the crossover between Luttinger and Fermi liquid phases. One-particle properties, local spin response and inter-c

I. M. Sokolov, A. Blumen, J. Klafter

We consider the linear response of systems modelled by continuous-time random walks (CTRW) and by fractional Fokker-Planck equations under the influence of time-dependent external fields. We calculate the corresponding response functions explicitely. The CTRW curve exhibits aging, i.e. it is not translationally invariant in the time-domain. This is different

Paolo Politi, Claudio Castellano

The epitaxial growth process of a high symmetry surface occurs because adatoms meet and nucleate new islands, that eventually coalesce and complete atomic layers. During multilayer growth, nucleation usually takes place on top of terraces where the geometry of the diffusion process is well defined: We have studied in detail the spatiotemporal distribution of

M. Ahr, M. Biehl, T. Volkmann

First, we present a two-dimensional lattice gas model with anisotropic interactions which explains the experimentally observed transition from a dominant c(2x2) ordering of the CdTe(001) surface to a local (2x1) arrangement of the Cd atoms as an equilibrium phase transition. Its analysis by means of transfer-matrix and Monte Carlo techniques shows that the s

E. Ahmed, A. S. Hegazi, A. S. Elgazzar, H. M. Yehia

Recent studies in ecology and epidemiology indicate that it is important to include spatial heterogeneity, synchronization and seasonality in the theoretical models. In this work, spatial heterogeneity is introduced via coupled map lattices (CML) and partial differential equations. Stability and persistence of some realistic CML are discussed. Chaos control,

G. M. Bruun, B. R. Mottelson

We consider the low energy collective mode spectrum of a superfluid Fermi gas in a spherical trap in the collisionless regime. Using a self-consistent random-phase approximation, the effects of superfluidity on modes of dipole and quadrupole symmetries are systematically examined. The spectrum is calculated for varying pairing strength and temperature and we

Suzanne Fielding, Peter Sollich

We study the non-equilibrium version of the fluctuation-dissipation theorem (FDT) within the glass phase of Bouchaud&#39;s trap model. We incorporate into the model an arbitrary observable m and obtain its correlation and response functions in closed form. A limiting non-equilibrium FDT plot (of correlator vs response) is approached at long times for most ch

D. Serero, G. Reydellet, P. Claudin, E. Clément

We measured the vertical pressure response function of a layer of sand submitted to a localized normal force at its surface. We found that this response profile depends on the way the layer has been prepared: all profiles show a single centered peak whose width scales with the thickness of the layer, but a dense packing gives a wider peak than a loose one. W

Y. S. Lee, J. S. Lee, K. W. Kim, T. W. Noh

We investiaged the optical properties of four-layer BaRuO$_{3}$, which shows a fermi-liquid-like behavior at low temperature. Its optical conductivity spectra clearly displayed the formation of a pseudogap and the development of a coherent peak with decreasing temperature. Temperature-dependences of the density $n$ and the scattering rate $1/τ$ of the cohere

Cristian Micheletti, Jayanth Banavar, Amos Maritan

We introduce a simple theoretical approach for an equilibrium study of proteins with known native state structures. We test our approach with results on well-studied globular proteins, Chymotrypsin Inhibitor (2ci2), Barnase and the alpha spectrin SH3 domain and present evidence for a hierarchical onset of order on lowering the temperature with significant or

L. Harnau, S. Dietrich

Fluids consisting of hard platelike particles near a hard wall are investigated using density functional theory. The density and orientational profiles as well as the surface tension and the excess coverage are determined and compared with those of a fluid of rodlike particles. Even for low densities slight orientational packing effects are found for the pla

U. Michelucci, F. Venturini, A. P. Kampf

We investigate the mutual influence of impurities in two-dimensional d-wave superconductors involving self-consistent solutions of the Bogoliubov-de Gennes equations. The local order parameter suppression, the local density of states (LDOS) as well as the interference of impurity-induced structures are analyzed. We employ an impurity position averaging schem

A. Pimenov, A. Loidl, D. Dulic, D. van der Marel

The magnetic field and temperature dependence of the transverse and longitudinal plasmons in SmLa_0.8Sr_0.2CuO_{4-δ} have been measured for frequencies 5 < nu < 30 cm^{-1} and magnetic fields 0 < B < 7 T. A transition between a vortex glass and a vortex liquid regime, which revealed different field dependencies of the resonance frequencies, could be clearly

L. Hansen, D. Ferrand, G. Richter, M. Thierley

We report on the MBE-growth and magnetotransport properties of p-type BeMnTe, a new ferromagnetic diluted magnetic semiconductor. BeMnTe thin film structures can be grown almost lattice matched to GaAs for Mn concentrations up to 10% using solid source MBE. A high p-type doping with nitrogen can be achieved by using an RF-plasma source. BeMnTe and BeTe layer

Takayuki Ichikawa, Mikio Ymamoto, Seiji Higashitani, Katsuhiko Nagai

Sound propagation in a Fermi liquid with impurities is studied using the Landau-Boltzmann equation and the result is compared with a recent experiment in liquid ${}^3$He in aerogel by Northwestern University group. The sound absorption calculated using the fixed impurity model is a few orders of magnitude larger than the experiment. We take into account the

C. Vignali, W. N. Brandt, X. Fan, J. E. Gunn

We report exploratory Chandra observations of 14 high-redshift (z=4.06-5.27), optically selected quasars. Ten of these quasars are detected, increasing the number of z>4 X-ray detected quasars by 71%. Our detections include four of the five highest-redshift X-ray detected quasars to date, among them SDSSp J021043.17-001818.4, the highest-redshift (z=4.77) ra

Eiichiro Komatsu, Benjamin D. Wandelt, David N. Spergel, Anthony J. Banday

We measure the angular bispectrum of the cosmic microwave background (CMB) radiation anisotropy from the COBE Differential Microwave Radiometer (DMR) four-year sky maps. The angular bispectrum is the harmonic transform of the three-point correlation function, analogous to the angular power spectrum, the harmonic transform of the two-point correlation functio

John M. Dickey, N. M. McClure-Griffiths, Snezana Stanimirovic, B. M. Gaensler

Using data from the Southern Galactic Plane Survey we have measured the spatial power spectrum of the interstellar neutral atomic hydrogen in the fourth Galactic quadrant. This function shows the same power law behavior that has been found for H I in the second quadrant of the Milky Way and in the Magellanic Clouds, with the same slope. When we average over

Ted K. Wyder

Images of five fields in the Local Group dwarf irregular galaxy NGC 6822 obtained with the {\it Hubble Space Telescope} in the F555W and F814W filters are presented. Photometry for the stars in these images was extracted using the Point-Spread-Function fitting program HSTPHOT/MULTIPHOT. The resulting color-magnitude diagrams reach down to $V\approx26$, a lev

John M. Dickey

This chapter is in three parts. The first presents the fundamental equations of level populations and radiative transfer which govern spectral line emission and absorption. Lines in the cm-wave band have similarities which allow us to simplify the equations. The further simplification of a two level system (a good approximation for H I gives the familiar for