June 2006 arXiv papers — page 19

George Jaroszkiewicz, Jon Eakins

Motivated by Heisenberg's assertion that electron trajectories do not exist until they are observed, we present a new approach to quantum mechanics in which the concept of observer independent system under observation is eliminated. Instead, the focus is only on observers and apparatus, the former describing the latter in terms of labstates. These are qu

R. Schützhold, W. G. Unruh

The fastest quantum algorithms (for the solution of classical computational tasks) known so far are basically variations of the hidden subgroup problem with {$f(U[x])=f(x)$}. Following a discussion regarding which tasks might be solved efficiently by quantum computers, it will be demonstrated by means of a simple example, that the detection of more general h

Bradley J. Frey, Douglas B. Leviton, Timothy J. Madison

Silicon and germanium are perhaps the two most well-understood semiconductor materials in the context of solid state device technologies and more recently micromachining and nanotechnology. Meanwhile, these two materials are also important in the field of infrared lens design. Optical instruments designed for the wavelength range where these two materials ar

I. Lesanovsky, S. Hofferberth, J. Schmiedmayer, P. Schmelcher

We explore properties of atoms whose magnetic hyperfine sub-levels are coupled by an external magnetic radio frequency (rf) field. We perform a thorough theoretical analysis of this driven system and present a number of systematic approximations which eventually give rise to dressed adiabatic radio frequency potentials. The predictions of this analytical inv

Zoltan Eisler, Janos Kertesz

We investigate the correlation properties of transaction data from the New York Stock Exchange. The trading activity f(t) of each stock displays a crossover from weaker to stronger correlations at time scales 60-390 minutes. In both regimes, the Hurst exponent H depends logarithmically on the liquidity of the stock, measured by the mean traded value per minu

M. Tammam, A. Fix, H. Arenhövel

Incoherent pion electroproduction on the deuteron is studied from threshold up to the second resonance region with special emphasis on the influence of final state interaction, in particular on polarization observables. The elementary $γN\toπN$ amplitude is taken from the MAID-2003 model. Final state interaction is included by considering complete rescatteri

NA60 Collaboration, M. Floris, R. Arnaldi, R. Averbeck

NA60 is a fixed-target experiment at the CERN SPS which measured dimuon production in nucleus-nucleus and proton-nucleus collisions. In this paper we report on a precision measurement of low-mass muon pairs in 158 AGeV indium-indium collisions. A significant excess of pairs is observed above the yield expected from neutral meson decays. The excess can be iso

Sven Gnutzmann, Panos D. Karageorge, Uzy Smilansky

Sequences of nodal counts store information on the geometry (metric) of the domain where the wave equation is considered. To demonstrate this statement, we consider the eigenfunctions of the Laplace-Beltrami operator on surfaces of revolution. Arranging the wave functions by increasing values of the eigenvalues, and counting the number of their nodal domains

Jacques H. H. Perk, Helen Au-Yang

Using detailed exact results on pair-correlation functions of Z-invariant Ising models, we can write and run algorithms of polynomial complexity to obtain wavevector-dependent susceptibilities for a variety of Ising systems. Reviewing recent work we compare various periodic and quasiperiodic models, where the couplings and/or the lattice may be aperiodic, an

Gianluca Panati, Christof Sparber, Stefan Teufel

As a simple model for piezoelectricity we consider a gas of infinitely many non-interacting electrons subject to a slowly time-dependent periodic potential. We show that in the adiabatic limit the macroscopic current is determined by the geometry of the Bloch bundle. As a consequence we obtain the King-Smith and Vanderbilt formula up to errors smaller than a

Vsevolod A. Vladimirov, Ekaterina V. Kutafina, Anna Pudelko

We present a review of our recent works directed towards discovery of a periodic, kink-like and soliton-like travelling wave solutions within the models of transport phenomena and the mathematical biology. Analytical description of these wave patterns is carried out by means of our modification of the direct algebraic balance method. In the case when the ana

J. -F. Lafont, I. J. Ortiz

For $Γ$ a relatively hyperbolic group, we construct a model for the universal space among $Γ$-spaces with isotropy on the family VC of virtually cyclic subgroups of $Γ$. We provide a recipe for identifying the maximal infinite virtually cyclic subgroups of Coxeter groups which are lattices in $O^+(n,1)= \iso(\mathbb H^n)$. We use the information we obtain to

Josep Elgueta

In this paper a notion of {\it generalized 2-vector space} is introduced which includes Kapranov and Voevodsky 2-vector spaces. Various kinds of generalized 2-vector spaces are considered and examples are given. The existence of non free generalized 2-vector spaces and of generalized 2-vector spaces which are non Karoubian (hence, non abelian) categories is

N. Josephy, L. Kimball, A. Nagaev, M. Pasniewski

We present an algorithm producing a dynamic non-self-financing hedging strategy in an incomplete market corresponding to investor-relevant risk criterion. The optimization is a two stage process that first determines admissible model parameters that correspond to the market price of the option being hedged. The second stage applies various merit functions to

Barry Monson, Tomaz Pisanski, Egon Schulte, Asia Ivic Weiss

Every finite, self-dual, regular (or chiral) 4-polytope of type {3,q,3} has a trivalent 3-transitive (or 2-transitive) medial layer graph. Here, by dropping self-duality, we obtain a construction for semisymmetric trivalent graphs (which are edge- but not vertex-transitive). In particular, the Gray graph arises as the medial layer graph of a certain universa

Paul Turner

These lecture notes, which were designed for the Summer School "Heegaard-Floer Homology and Khovanov Homology" in Marseilles, 29th May - 2nd June, 2006, provide an elementary introduction to Khovanov homology. The intended audience is graduate students with some minimal background in low-dimensional and algebraic topology. The lectures cover the basi

David A. Cox

This paper gives an explicit construction of the Tate resolution of sheaves arising from the d-fold Veronese embedding of P^n. Our description involves the Bezoutian of n+1 homogenous forms of degree d in n+1 variables. We give applications to duality theorems, including Koszul duality.

Alessio Sancetta

We present a result on topologically equivalent integral metrics (Rachev, 1991, Muller, 1997) that metrize weak convergence of laws with common marginals. This result is relevant for applications, as shown in a few simple examples.

David J. Hand

Rejoinder: Classifier Technology and the Illusion of Progress [math.ST/0606441]

Xiaoping Yuan

The existence of lower dimensional KAM tori is shown for a class of nearly integrable Hamiltonian systems where the second Melnikov's conditions are eliminated. As a consequence, it is proved that there exist many invariant tori and thus quasi-periodic solutions for nonlinear wave equations, Schrödinger equations and other equations of higher spatial dim

David Blanc

Given a suitable functor T:C -> D between model categories, we define a long exact sequence relating the homotopy groups of any X in C with those of TX, and use this to describe an obstruction theory for lifting an object G in D to C. Examples include finding spaces with given homology or homotopy groups.

Robert A. Stine

Comment on Classifier Technology and the Illusion of Progress [math.ST/0606441]

J. Mrcun, P. Semrl

We show that any multiplicative bijection between the algebras of differentiable functions, defined on differentiable manifolds of positive dimension, is an algebra isomorphism, given by composition with a unique diffeomorphism.

Robert C. Holte

Comment: Elaboration on Two Points Raised in ``Classifier Technology and the Illusion of Progress'' [math.ST/0606441]

Svante Janson

We show that a random graph studied by Ioffe and Levit is an example of an inhomogeneous random graph of the type studied by Bollobas, Janson and Riordan, which enables us to give a new, simple, proof of their result on a phase transition.

A. Simis, B. Ulrich, W. V. Vasconcelos

\noindent We study the Zariski tangent cone $T_X\stackrelπ{\lar} X$ to an affine variety $X$ and the closure $\bar{T}_X$ of $π^{-1}({\rm Reg}(X))$ in $T_X$. We focus on the comparison between $T_X$ and $\bar{T}_X$, giving sufficient conditions on $X$ in order that $T_X=\bar{T}_X$. One aspect of the results is to understand when this equality takes place in t

Ross W. Gayler

Comment on Classifier Technology and the Illusion of Progress--Credit Scoring [math.ST/0606441]

Kellen Myers, Aaron Robertson

We show that for any two linear homogenous equations $\mathcal{E}_0,\mathcal{E}_1$, each with at least three variables and coefficients not all the same sign, any 2-coloring of $\mathbb{Z}^+$ admits monochromatic solutions of color 0 to $\mathcal{E}_0$ or monochromatic solutions of color 1 to $\mathcal{E}_1$. We define the 2-color off-diagonal Rado number $R

Vida Dujmovic', David Eppstein, Matthew Suderman, David R. Wood

We study straight-line drawings of planar graphs with few segments and few slopes. Optimal results are obtained for all trees. Tight bounds are obtained for outerplanar graphs, 2-trees, and planar 3-trees. We prove that every 3-connected plane graph on $n$ vertices has a plane drawing with at most ${5/2}n$ segments and at most $2n$ slopes. We prove that ever

Wolfgang Bertram, Harald Loewe

We introduce the notion of intrinsic subspaces of linear and affine pair geometries, which generalizes the one of projective subspaces of projective spaces. We prove that, when the affine pair geometry is the projective geometry of a Lie algebra introduced in [Bertram-Neeb, J. Alg. 277], such intrinsic subspaces correspond to inner ideals in the associated J

Jerome H. Friedman

Comment on Classifier Technology and the Illusion of Progress [math.ST/0606441]

Vida Dujmovic', Matthew Suderman, David R. Wood

The "slope-number" of a graph $G$ is the minimum number of distinct edge slopes in a straight-line drawing of $G$ in the plane. We prove that for $Δ\geq5$ and all large $n$, there is a $Δ$-regular $n$-vertex graph with slope-number at least $n^{1-\frac{8+ε}{Δ+4}}$. This is the best known lower bound on the slope-number of a graph with bounded degree.

Gianluca Argentini

In this paper we present a mathematical model for estimate the collapse time of a gas bubble in a vane of a oil gerotor pump. This amount of time cannot be greater of the total time spent by the pump for filling and then emptying out a vane in a single revolution, otherwise there is a loss of lubrication between internal and external gears. We assume that oi

Frank Hansen

We investigate monotone operator functions of several variables under a trace or a trace-like functional. In particular, we prove the inequality τ(x_1... x_n)\leτ(y_1... y_n) for a trace τon a C^*-algebra and abelian n-tuples (x_1,...,x_n)\le (y_1,...,y_n) of positive elements. We formulate and prove Jensen's inequality for expectation values, and we stu

Thomas Fiedler

Let $ϕ: S^1\times D^2\to S^1$ be the natural projection. An oriented knot $K\hookrightarrow V = S^1\times D^2$ is called an almost closed braid if the restriction of $ϕ$ to K has exactly two (non-degenerate) critical points (and K is a closed braid if the restriction of $ϕ$ has no critical points at all). We introduce new isotopy invariants for closed braids

David J. Hand

A great many tools have been developed for supervised classification, ranging from early methods such as linear discriminant analysis through to modern developments such as neural networks and support vector machines. A large number of comparative studies have been conducted in attempts to establish the relative superiority of these methods. This paper argue

E. Coussement, J. Coussement, W. Van Assche

We establish the asymptotic zero distribution for polynomials generated by a four-term recurrence relation with varying recurrence coefficients having a particular limiting behavior. The proof is based on ratio asymptotics for these polynomials. We can apply this result to three examples of multiple orthogonal polynomials, in particular Jacobi-Pineiro, Lague

Hiromasa Nakayama

We give an algorithm to compute the local $b$ function. In this algorithm, we use the Mora division algorithm in the ring of differential operators and an approximate division algorithm in the ring of differential operators with power series coefficient.

Carlangelo Liverani, Masato Tsujii

In this brief note we present a very simple strategy to investigate dynamical determinants for uniformly hyperbolic systems. The construction builds on the recent introduction of suitable functional spaces which allow to transform simple heuristic arguments in rigorous ones. Although the results so obtained are not exactly optimal the straightforwardness of

Benson Farb

This paper presents a number of problems about mapping class groups and moduli space. The paper will appear in the book "Problems on Mapping Class Groups and Related Topics", ed. by B. Farb, Proc. Symp. Pure Math. series, Amer. Math. Soc.

Ben Green, Sergei Konyagin

Let p be a prime, and let f : Z/pZ -> R be a function with average value 0 and ||f||_A <= 1, where ||f||_A denotes the algebra norm (L^1 norm of the Fourier transform). Then f(x) is small for some x, specifically min_x |f(x)| is no more than O(log p)^{-1/3 + eps}. One should think of f as being ``approximately continuous&#39;&#39;; our result is then an ``ap

Bernhard Keller

Differential graded categories enhance our understanding of triangulated categories appearing in algebra and geometry. In this survey, we review their foundations and report on recent work by Drinfeld, Dugger-Shipley, ..., Toen and Toen-Vaquie.

David R. Wood

It is proved that the rectilinear crossing number of every graph with bounded tree-width and bounded degree is linear in the number of vertices. **** This paper has been withdrawn by the author. **** The results have been superseeded by the author&#39;s paper with Jan Arne Telle: &#34;Planar decompositions and the crossing number of graphs with an excluded m

Bin Zhu

Tilting theory in cluster categories of hereditary algebras has been developed in [BMRRT] and [BMR]. These results are generalized to cluster categories of hereditary abelian categories. Furthermore, for any tilting object $T$ in a hereditary abelian category $\mathcal{H}$, we verify that the tilting functor Hom$_\mathcal{H}(T,-)$ induces a triangle equivale

Louis H. Kauffman, Sofia Lambropoulou

In this paper we prove a Markov Theorem for virtual braids and for some analogs of this structure. The virtual braid group is the natural companion in the category of virtual knots, just as the Artin braid group is the natural companion to classical knots and links. In this paper we follow the L--move methods to prove the Virtual Markov Theorem. One benefit

Stefano Arnone, Tim R. Morris, Oliver J. Rosten

We construct a manifestly gauge invariant Exact Renormalization Group for SU(N) Yang-Mills theory, in a form suitable for calculations without gauge fixing at any order of perturbation theory. The effective cutoff is incorporated via a manifestly realised spontaneously broken SU(N|N) gauge invariance. Diagrammatic methods are developed which allow the calcul

Sean A. Hartnoll

We present results for Wilson loops in strongly coupled gauge theories. The loops may be taken around an arbitrarily shaped contour and in any field theory with a dual IIB geometry of the form M x S^5. No assumptions about supersymmetry are made. The first result uses D5 branes to show how the loop in any antisymmetric representation is computed in terms of

G. Benfatto, P. Falco, V. Mastropietro

We construct a QFT for the Thirring model for any value of the mass in a functional integral approach, by proving that a set of Grassmann integrals converges, as the cutoffs are removed and for a proper choice of the bare parameters, to a set of Schwinger functions verifying the Osterwalder-Schrader axioms. The corresponding Ward Identities have anomalies wh

Serge Massar, Philippe Spindel

We consider the quantum correlations, i.e. the entanglement, between two systems uniformly accelerated with identical acceleration a in opposite Rindler quadrants which have reached thermal equilibrium with the Unruh heat bath. To this end we study an exactly soluble model consisting of two oscillators coupled to a massless scalar field in 1+1 dimensions. We

K. Shizuya

The effect of quantum fluctuations on Bogomol&#39;nyi-Prasad-Sommerfield (BPS)-saturated topological excitations in supersymmetric theories is studied. Focus is placed on a sequence of topological excitations that derive from the same classical soliton or vortex in lower dimensions and it is shown that their quantum characteristics, such as the spectrum and

Pietro Fre&#39;, Pietro Antonio Grassi

The lagrangian formalism for the supermembrane in any 11d supergravity background is constructed in the pure spinor framework. Our gauge-fixed action is manifestly BRST, supersymmetric, and 3d Lorentz invariant. The relation between the Free Differential Algebras (FDA) underlying 11d supergravity and the BRST symmetry of the membrane action is exploited. The

Kazunari Shima, Motomu Tsuda

We investigate for N = 3 supersymmetry (SUSY) in D = 2 the algebraic relation between the Volkov-Akulov (VA) model of nonlinear (NL) SUSY and a (renormalizable) SO(3) vector supermultiplet of linear (L) SUSY. We derive SUSY and SO(3) invariant relations between component fields of the vector supermultiplet and Nambu-Goldstone (NG) fermions of the VA model at

Utpal Sarkar

A simple algorithm to calculate the group theory factor entering in anomalies at four and six dimensions for SU(N) and SO(N) groups in terms of the Casimir invariants of their subgroups is presented. Explicit examples of some of the lower dimensional representations of $SU(n), n \leq 5$ and SO(10) groups are presented, which could be used for model building

M. Ciuchini, E. Franco, D. Guadagnoli, V. Lubicz

We compute the next-to-leading order strong interaction corrections to gluino-mediated Delta F=2 box diagrams in the Minimal Supersymmetric Standard Model. These corrections are given by two loop diagrams which we have calculated in three different regularization schemes in the mass insertion approximation. We obtain the next-to-leading order Wilson coeffici

Ajay Kumar Rai, P C Vinodkumar

The mass spectrum of $c \bar b$ meson is investigated with an effective quark-antiquark potential of the form $\frac{-α_c}{r}$ + $A r^ν$ with $ν$ varying from 0.5 to 2.0. The S and P-wave masses, pseudoscalar decay constant, weak decay partial widths in spectator model and the lifetime of $B_c$ meson are computed. The properties calculated here are found to

B. Betz, M. Bleicher, U. Harbach, T. Humanic

We examine experimental signatures of TeV-mass black hole formation in heavy ion collisions at the LHC. We find that the black hole production results in a complete disappearance of all very high $p_T$ ({$> 500$} GeV) back-to-back correlated di-jets of total mass {$M > M_f \sim 1$}TeV. We show that the subsequent Hawking-decay produces multiple hard mono-jet

Masaharu Iwasaki, Hiromasa Ohnishi, Takahiko Fukutome

We discuss the shear viscosity of the quark matter by using the Kubo-Mori formula. It is found that the shear viscosity is expressed in terms of the quark spectral function. If the spectral function is approximated by a modified Bright-Wigner type, the viscosity decreases as the width of the spectral function increases. We also discuss dependence of the shea

N. N. Nikolaev, F. F. Pavlov

The spin filtering by a multiple passage of a stored beam through a polarized internal gas target is a unique possibility of polarizing high luminosity beam of antiprotons to a high degree of polarization. Apart from the polarization by the spin-dependent transmission, a unique geometrical feature of spin filtering in storage rings is a scattering of stored

CDF Collaboration, A. Abulencia

We present a search for excited and exotic muon states mu*, conducted using an integrated luminosity of 371 pb^{-1} of data collected in p-pbar collisions at sqrt{s} = 1.96 TeV at the Tevatron with the CDF II detector. We search for associated production of mu+mu* followed by the decay mu* -> mu+gamma, resulting in the mu+mu+gamma final state. We compare the

M. Ungaro, P. Stoler, I. Aznauryan, V. D. Burkert

We report a new measurement of the exclusive electroproduction reaction gamma* p -> pi0 p to explore the evolution from soft non-perturbative physics to hard processes via the Q2 dependence of the magnetic (M1+), electric (E1+) and scalar (S1+) multipoles in the N to Delta transition. 9000 differential cross section data points cover W from threshold to 1.4

Valerii Dryuma

An examples of a Ricci-flat of four-dimensional spaces with a Walker metrics and their generalizations are constructed. The properties of corresponding geodesic equations are discussed.

Martin Bojowald, Mikhail Kagan

Non-minimal actions with matter represented by a scalar field coupled to gravity are considered in the context of a homogeneous and isotropic universe. The coupling is of the form $-ξ/2 ϕ^2 R$. The possibility of successful inflation is investigated taking into account features of loop cosmology. For that end a conformal transformation is performed. That bri

A. Mikovic

We give the correct expressions for the spin network evaluations proposed in Class. Quant. Grav. 21 (2004) 3909 as the coefficients of the quantum gravity vacuum wavefunction in the spin network basis.

J. Jalden, B. Ottersten

We consider the detection of binary (antipodal) signals transmitted in a spatially multiplexed fashion over a fading multiple-input multiple-output (MIMO) channel and where the detection is done by means of semidefinite relaxation (SDR). The SDR detector is an attractive alternative to maximum likelihood (ML) detection since the complexity is polynomial rath

Jonathan Ben-Naim

Lehmann, Magidor, and Schlechta developed an approach to belief revision based on distances between any two valuations. Suppose we are given such a distance D. This defines an operator |D, called a distance operator, which transforms any two sets of valuations V and W into the set V |D W of all elements of W that are closest to V. This operator |D defines na

Philippe Chapdelaine

In 1975, Ladner showed that under the hypothesis that P is not equal to NP, there exists a language which is neither in P, nor NP-complete. This result was latter generalized by Schoning and several authors to various polynomial-time complexity classes. We show here that such results also apply to linear-time reductions on RAMs (resp. Turing machines), and h

Sabu . M Thampi, K. Chandra Sekaran

In this paper we present an image retrieval system based on Gabor texture features, steganography, and mobile agents.. By employing the information hiding technique, the image attributes can be hidden in an image without degrading the image quality. Thus the image retrieval process becomes simple. Java based mobile agents manage the query phase of the system

M. V. Tamm, S. K. Nechaev

We consider a ${\rm A}_m{\rm B}_n$ diblock copolymer, whose links are capable of forming local reversible bonds with each other. We assume that the resulting structure of the bonds is RNA--like, i.e. topologically isomorphic to a tree. We show that, depending on the relative strengths of A--A, A--B and B--B contacts, such a polymer can be in one of two diffe

Hong-Yi Chen, Vadim Apalkov, Tapash Chakraborty

We propose a novel approach to explore the properties of a quantum dot in the presence of the spin-orbit interaction and in a tilted magnetic field. The spin-orbit coupling within the quantum dot manifest itself as anti-crossing of the energy levels when the tilt angle is varied. The anti-crossing gap has a non-monotonic dependence on the magnitude of the ma

F. Ronning, C. Capan, N. O. Moreno, J. D. Thompson

We present specific heat and susceptibility data on Sm(La,Sr)CuO4 in magnetic fields up to 9 T and temperatures down to 100 mK. We find a broad peak in specific heat which is insensitive to magnetic field at a temperature of 1.5 K with a value of 2.65 J/mol K. The magnetic susceptibility at 5 T continues to increase down to 2 K, the lowest temperature measur

Andrey Pereverzev, Eric R. Bittner

The time-convolutionless master equation for the electronic populations is derived for a generic electron-phonon Hamiltonian. The equation can be used in the regimes where the golden rule approach is not applicable. The equation is applied to study the electronic relaxation in several models with the finite number normal modes. For such mesoscopic systems th

David Cubero, José Pablo Baltanás, Jesús Casado-Pascual

The effect of a high-frequency signal on the FitzHugh-Nagumo excitable model is analyzed. We show that the firing rate is diminished as the ratio of the high-frequency amplitude to its frequency is increased. Moreover, it is demonstrated that the excitable character of the system, and consequently the firing activity, is suppressed for ratios above a given t

Jean-Michel Billiot, Franck Corset, Eric Fontenas

The Tutte polynomial is a powerfull analytic tool to study the structure of planar graphs. In this paper, we establish some relations between the number of clusters per bond for planar graph and its dual : these relations bring into play the coordination number of the graphs. The factorial moment measure of the number of clusters per bond are given using the

Matthew O. Reese, Daniel F. Santavicca, Luigi Frunzio, Daniel E. Prober

We are developing Nb diffusion-cooled Hot Electron Bolometers (HEBs) for a large-format array submillimeter camera. We have fabricated Nb HEBs using a new angle deposition process. We have characterized these devices using heterodyne mixing at 20 GHz. We also report on optimizations in the fabrication process that improve device performance.

P. Pedrazzini, H. Wilhelm, D. Jaccard, T. Jarlborg

We report on results of electrical resistivity and structural investigations on the cubic modification of FeGe under high pressure. The long-wavelength helical order ($T_C=280$ K) is suppressed at a critical pressure $p_c\approx 19$ GPa. An anomaly in the resistivity data at $T_X(p)$ and strong deviations from a Fermi-liquid behavior in a wide pressure range

I. Pallecchi, M. Monni, C. Ferdeghini, V. Ferrando

Recent experimental data of anisotropic magnetoresistivity measured in MgB2 films have shown an intriguing behaviour: the angular dependence of magnetoresistivity changes dramatically with temperature and disorder. In order to explain such phenomenology, in this work, we extend our previous analyses on multiband transverse magnetoresistivity in magnesium dib

W. J. Mullin, R. J. Ragan

Recent experiments in a mixture of two hyperfine states of trapped Bose gases show behavior analogous to a spin-1/2 system, including transverse spin waves and other familiar Leggett-Rice-type effects. We have derived the kinetic equations applicable to these systems, including the spin dependence of interparticle interactions in the collision integral, and

I. A. Nechaev, I. Nagy, P. M. Echenique, E. V. Chulkov

An instantaneous and zero-range spin-dependent interaction, derived by summing an infinite number of electron-hole ladder diagrams within a local approximation, is analyzed as a function of the electron gas density and the relative spin polarization. The strength of such an interaction is defined by an integral of a statically screened Coulomb interaction wi

R. C. Myers, B. L. Sheu, A. W. Jackson, A. C. Gossard

We study the Curie temperature and hole density of (Ga,Mn)As while systematically varying the As-antisite density. Hole compensation by As-antisites limits the Curie temperature and can completely quench long-range ferromagnetic order in the low doping regime of 1-2% Mn. Samples are grown by molecular beam epitaxy without substrate rotation in order to smoot

J. Kienert, W. Nolting

The magnetic phase diagram of the ferromagnetic Kondo lattice model is determined at T=0 in 1D, 2D, and 3D for various magnitudes of the quantum mechanical localized spins ranging from S=1/2 to classical spins. We consider the ferromagnetic phase, the paramagnetic phase, and the ferromagnetic/antiferromagnetic phase separated regime. There is no significant

V. I. Yukalov, H. Kleinert

A dilute Bose system with Bose-Einstein condensate is considered. It is shown that the Hartree-Fock-Bogolubov approximation can be made both conserving as well as gapless. This is achieved by taking into account all physical normalization conditions, that is, the normalization condition for the condensed particles and that for the total number of particles.

Oscar Iglesias, Xavier Batlle, Amilcar Labarta

We present Monte Carlo simulations of hysteresis loops of a model of a magnetic nanoparticle with a ferromagnetic core and an antiferromegnetic shell with varying values of the core/shell interface exchange coupling which aim to clarify the microscopic origin of exchange bias observed experimentally. We have found loops shifts in the field direction as well

Yubao Sun, Hongmei Ma, Zhidong Zhang, Xinyu Zhu

Twist angle effect on the response time of in-plane-switching liquid crystal displays are analyzed. We propose a device configuration whose top and bottom boundary liquid crystal layers are symmetric to each other with respect to the electric field direction. The analytical results of this device configuration indicate that the response time is improved at l

Tai-Kai Ng, Wai-Tak Tse

In this paper we study the Ginzburg-Landau (GL) equation for Fermi liquid superconductors with strong Landau interactions $F_0$ and $F_1$. We show that Landau interactions renormalize two parameters entering the GL equation leading to renormalization of superfluid density and separation of length and energy scales for amplitude and phase fluctuations. The se

P. D. A. Mann, M. Sutherland, C. Bergemann, S. Yonezawa

We measured the Fermi surface of the recently discovered superconductor Ag5Pb2O6 via a de Haas-van Alphen rotation study. Two frequency branches were observed and identified with the neck and belly orbits of a very simple, nearly free electron Fermi surface. We use the observed Fermi surface geometry to quantitatively deduce superconducting properties such a

R. D. McDonald, J. Singleton, P. A. Goddard, N. Harrison

We describe instrumentation designed to perform millimeter-wave conductivity measurements in pulsed high magnetic fields at low temperatures. The main component of this system is an entirely non-metallic microwave resonator. The resonator utilizes periodic dielectric arrays (photonic bandgap structures) to confine the radiation, such that the resonant modes

Obioma Uche, Salvatore Torquato, Frank Stillinger

Real collective density variables $C(\boldsymbol{k})$ [c.f. Eq.\ref{Equation3})] in many-particle systems arise from non-linear transformations of particle positions, and determine the structure factor $S(\boldsymbol{k})$, where $\bf k$ denotes the wave vector. Our objective is to prescribe $C({\boldsymbol k})$ and then to find many-particle configurations t

Yajiang Hao, Yunbo Zhang, J. -Q. Liang, Shu Chen

We investigate the ground state of the system of N bosons enclosed in a hard-wall trap interacting via a repulsive or attractive $δ$-function potential. Based on the Bethe ansatz method, the explicit ground state wave function is derived and the corresponding Bethe ansatz equations are solved numerically for the full physical regime from the Tonks limit to t

Ph. Jacquod, Robert S. Whitney

We investigate transport properties of quantized chaotic systems in the short wavelength limit. We focus on non-coherent quantities such as the Drude conductance, its sample-to-sample fluctuations, shot-noise and the transmission spectrum, as well as coherent effects such as weak localization. We show how these properties are influenced by the emergence of t

Simone M. Weinmann, Frank C. van den Bosch, Xiaohu Yang, H. J. Mo

Successfully reproducing the galaxy luminosity function and the bimodality in the galaxy distribution requires a mechanism that can truncate star formation in massive haloes. Current models of galaxy formation consider two such truncation mechanisms: strangulation, which acts on satellite galaxies, and AGN feedback, which predominantly affects central galaxi

Brian E. Wood, Margarita Karovska

Recent ultraviolet spectra from the Hubble Space Telescope (HST) and Far Ultraviolet Spectroscopic Explorer (FUSE) satellites demonstrate that UV line and continuum fluxes observed from Mira B are increasing back towards the levels that the International Ultraviolet Explorer observed in 1979-1980 and 1990-1995, after having been found in a very low state by

Ari Heinze, Phil Hinz, Suresh Sivanandam, Daniel Apai

We are carrying out a survey to search for giant extrasolar planets around nearby, moderate-age stars in the mid-infrared L&#39; and M bands (3.8 and 4.8 microns, respectively), using the Clio camera with the adaptive optics system on the MMT telescope. To date we have observed 7 stars, of a total 50 planned, including GJ 450 (distance about 8.55pc, age abou

Grazyna Stasinska

We propose two statistical methods to derive oxygen abundances in HII regions and star forming galaxies and calibrate them with a sample of several hundred giant HII regions in spiral and blue compact galaxies as well as of galaxies from the Sloan Digital Sky Survey. We show the advantages of our new abundance indicators over previous ones.

Emory F. Bunn, Martin White

Measurements of cosmic microwave background (CMB) anisotropies by interferometers offer several advantages over single-dish observations. The formalism for analyzing interferometer CMB data is well developed in the flat-sky approximation, valid for small fields of view. As the area of sky is increased to obtain finer spectral resolution, this approximation n

M. Gieles, S. F. Portegies Zwart, H. Baumgardt, E. Athanassoula

We investigate encounters between giant molecular clouds (GMCs) and star clusters. We propose a single expression for the energy gain of a cluster due to an encounter with a GMC, valid for all encounter distances and GMC properties. This relation is verified with N-body simulations of cluster-GMC encounters and excellent agreement is found. The fractional ma

Chris L. Fryer, Falk Herwig, Aimee Hungerford, Frank Timmes

The conditions for the leading r-process site candidate, neutrino-driven winds, can not be reproduced self-consistently in current supernova models. For that reason, we investigate an alternate model involving the mass ejected by fallback in a supernova explosion, through hydrodynamic and nucleosynthesis calculations. The nucleosynthetic products of this eje

Daniel Kasen

We undertake a theoretical study of the near-infrared (NIR) lightcurves of Type Ia supernovae (SNe Ia). In these bands, the lightcurves are distinguished by a secondary maximum occurring roughly 20 to 30 days after the initial one. Using time-dependent multi-group radiative transfer calculations, we calculate the UBVRIJHK-band lightcurves of model SN Ia ejec

M. Limousin, J-P. Kneib, P. Natarajan

Gravitational lensing has now become a popular tool to measure the mass distribution of structures in the Universe on various scales. Here we focus on the study of galaxy&#39;s scale dark matter halos with galaxy-galaxy lensing techniques: observing the shapes of distant background galaxies which have been lensed by foreground galaxies allows us to map the m

B. Mookerjea, N. G. Kantharia, D. A. Roshi, M. Masur

We have mapped the [C I] emission at 492 GHz toward the supernova remnant Cas A. We detect [C I] emission from the periphery of the diffuse Photon Dominated Region (PDR) covering the disk of Cas A, as traced by the carbon recombination lines, as well as from the denser PDRs associated with the molecular clouds towards the south-east. [C I] emission is detect

Ralf Siebenmorgen, Endrik Kruegel

We provide a library of some 7000 SEDs (available at www.eso.org/~rsiebenm) for the nuclei of starburst and ultra luminous galaxies. Its purpose is to quickly obtain estimates of the basic parameters, such as luminosity, size and dust or gas mass and to predict the flux at yet unobserved wavelengths. The procedure is simple and consists of finding an element