October 2006 arXiv papers — page 20

G. Manfredi, P. -A. Hervieux

We study the Loschmidt echo for a system of electrons interacting through mean-field Coulomb forces. The electron gas is modeled by a self-consistent set of hydrodynamic equations. It is observed that the quantum fidelity drops abruptly after a time that is proportional to the logarithm of the perturbation amplitude. The fidelity drop is related to the break

Zheng-Wei Zhou, Yong-Jian Han, Guang-Can Guo

We provide a scheme for quantum computation in lattice systems via global but periodic manipulation, in which only effective periodic magnetic fields and global nearest neighbor interaction are required. All operations in our scheme are attainable in optical lattice or solid state systems. We also investigate universal quantum operations and quantum simulati

P. W. Bates, G. W. Wei, Shan Zhao

We introduce a novel concept, the minimal molecular surface (MMS), as a new paradigm for the theoretical modeling of biomolecule-solvent interfaces. When a less polar macromolecule is immersed in a polar environment, the surface free energy minimization occurs naturally to stabilizes the system, and leads to an MMS separating the macromolecule from the solve

Liang-You Peng, Xian-Zhou Zhang, Jian-Guo Rao

The quantum spectra of hydrogen atoms in various magnetic fields have been calculated with the closed orbit theory. The magnitude of the magnetic field decreases from 5.96 T to 0.56T with a step of 0.6T. We demonstrate schematically that the closed orbits disappear with the decrease of the magnitude of the magnetic field when the corresponding finite resolut

Sylvain Bourlange, Laurence Jouniaux, Pierre Henry

Permeability measured on three samples in a triaxial cell under effective confining pressure from 0.2 to 2.5 MPa ranges from 10E-18 to 10E-19m2. Overall, results indicate that permeability decreases with effective confining pressure up to 1.5 MPa; however, measurements at low effec-tive pressure are too dispersed to yield a precise general relationship betwe

S. Jain, T. Yamano

We study the persistence phenomenon in a socio-econo dynamics model using computer simulations at a finite temperature on hypercubic lattices in dimensions up to 5. The model includes a ` social\rq local field which contains the magnetization at time $t$. The nearest neighbour quenched interactions are drawn from a binary distribution which is a function of

G. Baur, S. Typel

Intermediate energy Coulomb excitation and dissociation is a useful tool for nuclear structure and astrophysics studies. Low-lying strength in nuclei far from stability was discovered by this method. The effective range theory for low-lying strength in one-neutron halo nuclei is summarized and extended to two-neutron halo nuclei. This is of special interest

Stefan Heusler, Sebastian Müller, Alexander Altland, Petr Braun

We present a semiclassical explanation of the so-called Bohigas-Giannoni-Schmit conjecture which asserts universality of spectral fluctuations in chaotic dynamics. We work with a generating function whose semiclassical limit is determined by quadruplets of sets of periodic orbits. The asymptotic expansions of both the non-oscillatory and the oscillatory part

Grzegorz Litak, Marek Borowiec, Arkadiusz Syta

We have applied the Melnikov criterion to examine a global homoclinic bifurcation and transition to chaos in a case of a double well dynamical system with a nonlinear fractional damping term and external excitation. The usual double well Duffing potential having a negative square term and positive quartic term has been generalized to a double well potential

Lior Albuch, Boris A. Malomed

It is well known that a symmetric soliton in coupled nonlinear Schroedinger (NLS) equations with the cubic nonlinearity loses its stability with the increase of its energy, featuring a transition into an asymmetric soliton via a subcritical bifurcation. A similar phenomenon was found in a dual-core system with quadratic nonlinearity, and in linearly coupled

Rodrigo A. Vicencio, Sergej Flach, Mario I. Molina, Yuri S. Kivshar

We study nonlinear surface modes in two-dimensional {\em anisotropic} periodic photonic lattices and demonstrate that, in a sharp contrast to one-dimensional discrete surface solitons, the mode threshold power is lower at the surface, and two-dimensional discrete solitons can be generated easier near the lattice corners and edges. We analyze the crossover be

K. D. T-R McLaughlin

We present a set of conditions which, if satisfied, provide for a complete asymptotic analysis of random matrices with source term containing two distinct eigenvalues. These conditions are shown to be equivalent to the existence of a particular algebraic curve. For the case of a quartic external field, the curve in question is proven to exist, yielding preci

Johannes Huebschmann

Simple classical mechanical systems and solution spaces of classical field theories involve singularities. In certain situations these singularities can be understood in terms of stratified Kaehler spaces. We give an overview of a research program whose aim is to develop a holomorphic quantization procedure on stratified Kaehler spaces.

Joseph A. Ball, Vladimir Bolotnikov, Quanlei Fang

An interesting and recently much studied generalization of the classical Schur class is the class of contractive operator-valued multipliers $S$ for the reproducing kernel Hilbert space ${\mathcal H}(k_{d})$ on the unit ball ${\mathbb B}^{d} \subset {\mathbb C}^{d}$, where $k_{d}$ is the positive kernel $k_{d}(λ, ζ) = 1/(1 - < λ, ζ>)$ on ${\mathbb B}^{d}$. T

Joseph A. Ball, Vladimir Bolotnikov, Quanlei Fang

An interesting and recently much studied generalization of the classical Schur class is the class of contractive operator-valued multipliers for the reproducing kernel Hilbert space ${\mathcal H}(k_{d})$ on the unit ball ${\mathbb B}^{d} \subset {\mathbb C}^{d}$, where $k_{d}$ is the positive kernel $k_{d}(λ, ζ) = 1/(1 - < λ, ζ>)$ on ${\mathbb B}^{d}$. We st

R. J. Messikh

For the two dimensional Ising model, we construct the adequate surface tension near criticality. The latter quantity has been shown to play a central role in the study of phase coexistence in a joint limit where the temperature approaches the critical point from below and simultaneously the size of the system increases fast enough.

Joseph A. Ball, Vladimir Bolotnikov, Quanlei Fang

We introduce and study a Fock-space noncommutative analogue of reproducing kernel Hilbert spaces of de Branges-Rovnyak type. Results include: use of the de Branges-Rovnyak space ${\mathcal H}(K_{S})$ as the state space for the unique (up to unitary equivalence) observable, coisometric transfer-function realization of the Schur-class multiplier $S$, realizati

Joseph A. Ball, Vladimir Bolotnikov, Quanlei Fang

It is well known that subspaces of the Hardy space over the unit disk which are invariant under the backward shift occur as the image of an observability operator associated with a discrete-time linear system with stable state-dynamics, as well as the functional-model space for a Hilbert space contraction operator. We discuss two multivariable extensions of

Eduardo D. Sontag, Yuan Wang, Alexandre Megretski

This paper asks what classes of input signals are sufficient in order to completely identify the input/output behavior of generic bilinear systems. The main results are that step inputs are not sufficient, nor are single pulses, but the family of all pulses (of a fixed amplitude but varying widths) do suffice for identification.

Dave Benson, Nicole Lemire, Jan Minac, John Swallow

We present several constraints on the absolute Galois groups G_F of fields F containing a primitive pth root of unity, using restrictions on the cohomology of index p normal subgroups from a previous paper by three of the authors. We first classify all maximal p-elementary abelian-by-order p quotients of such G_F. In the case p>2, each such quotient contains

Dave Benson, Nicole Lemire, Jan Minac, John Swallow

We present several constraints on the absolute Galois groups G_F of fields F containing a primitive pth root of unity, using restrictions on the cohomology of index p normal subgroups from a previous paper by three of the authors. We first classify all maximal p-elementary abelian-by-order p quotients of such G_F. In the case p>2, each such quotient contains

Karin Melnick

We prove a structure theorem for compact aspherical Lorentz manifolds with abundant local symmetry. If M is a compact, aspherical, real-analytic, complete Lorentz manifold such that the isometry group of the universal cover has semisimple identity component, then the local isometry orbits in M are roughly fibers of a fiber bundle. A corollary is that if M ha

Artur Avila, Alexander Bufetov

We prove exponential mixing for the Rauzy-Veech-Zorich induction map on the space of interval exchange transformations (Theorem 3)

Ibrahim Assem, Martin Blais, Thomas Brüstle, Audrey Samson

In this paper, we establish a bijection between the set of mutation classes of mutation-cyclic skew-symmetric integral 3x3-matrices and the set of triples of integers (a,b,c) which are all greater than 1 and where the product of the two smaller numbers is greater than or equal to the maximal number. We also give an algorithm allowing to verify whether a matr

George Kyriazis, Pencho Petrushev, Yuan Xu

The Littlewood-Paley theory is extended to weighted spaces of distributions on $[-1,1]$ with Jacobi weights $ \w(t)=(1-t)^α(1+t)^β. $ Almost exponentially localized polynomial elements (needlets) $\{ϕ_ξ\}$, $\{ψ_ξ\}$ are constructed and, in complete analogy with the classical case on $\RR^n$, it is shown that weighted Triebel-Lizorkin and Besov spaces can be

Francois Malgouyres

After a recollection on compression through a projection onto a polyhedral set (which generalizes the compression by coordinates quantization), we express, in this framework, the probability that an image is coded with $K$ coefficients as an explicit function of the approximation error.

Abdallah Khochman

We consider the self-adjoint operator $H=H_0+V$, where $H_0$ is the free semi-classical Dirac operator on $R^3$. We suppose that the smooth matrix-valued potential $V=O(<x>^{-δ}), δ>0,$ has an analytic continuation in a complex sector outside a compact. We define the resonances as the eigenvalues of the non-selfadjoint operator obtained from the Dirac operat

Nigel Kalton, Jan van Neerven, Mark Veraar, Lutz Weis

It is shown that a Banach space $E$ has type $p$ if and only for some (all) $d\ge 1$ the Besov space $B_{p,p}^{(\frac1p-\frac12)d}(\R^d;E)$ embeds into the space $\g(L^2(\R^d),E)$ of $\g$-radonifying operators $L^2(\R^d)\to E$. A similar result characterizing cotype $q$ is obtained. These results may be viewed as $E$-valued extensions of the classical Sobole

B. -Wolfgang Schulze

We discuss intuitive ideas and historical background of concepts in the analysis on configurations with singularities, here in connection with our iterative approach for higher singularities.

I. Nikonov, G. Sharygin

This paper is concerned with the theory of cup-products in Hopf-type cyclic cohomology of algebras and coalgebras. Here we give detailed proofs of the statements, announced in our previous paper. We show that the cyclic cohomology of a coalgebra can be obtained from a construction involving noncommutative Weil algebra. Then we use a generalization of Quillen

Johannes Huebschmann

The Kaehler quotient of a complex reductive Lie group relative to the conjugation action carries a complex algebraic stratified Kaehler structure which reflects the geometry of the group. For the group SL(n,C), we interpret the resulting singular Poisson-Kaehler geometry of the quotient in terms of complex discriminant varieties and variants thereof.

F. Reese Harvey, H. Blaine Lawson

We give a new proof of the Alexander-Wermer Theorem that characterizes the oriented curves in C^n which bound positive holomorphic chains, in terms of the linking numbers of the curve with algebraic cycles in the complement. In fact, we establish a slightly stronger version which applies to a wider class of boundary 1-cycles. Arguments here are based on the

Michael Eastwood, Thomas Leistner

The symmetry operators for the Laplacian in flat space were recently described and here we consider the same question for the square of the Laplacian. Again, there is a close connection with conformal geometry. There are three main steps in our construction. The first is to show that the symbol of a symmetry is constrained by an overdetermined partial differ

John T. Hall, Jeffrey B. Remmel

Given sets X and Y of positive integers and a permutation sigma = sigma_1, sigma_2, ..., sigma_n in S_n, an X,Y-descent of sigma is a descent pair sigma_i > sigma_{i+1} whose &#34;top&#34; sigma_i is in X and whose &#34;bottom&#34; sigma_{i+1} is in Y. We give two formulas for the number P_{n,s}^{X,Y} of sigma in S_n with s X,Y-descents. P_{n,s}^{X,Y} is als

Florentin Smarandache

We present a theorem which generalizes the classical Euler&#39;s theorem on congruencies: if $(a,m)=1$ then $a^ ϕ(m) \equiv 1 (mod m)$ for the case when $a$ and $m$ are not relatively primes.

Rung-Tzung Huang

Braverman and Kappeler introduced a refinement of the Ray-Singer analytic torsion associated to a flat vector bundle over a closed odd-dimensional manifold. We study this notion and improve the Braverman-Kappeler theorem comparing the refined analytic torsion with Farber-Turaev refinement of the combinatorial torsion. Using this result we establish, modulo s

Roland K. W. Roeder, John H. Hubbard, William D. Dunbar

In 1970, E. M. Andreev published a classification of all three-dimensional compact hyperbolic polyhedra having non-obtuse dihedral angles. Given a combinatorial description of a polyhedron, $C$, Andreev&#39;s Theorem provides five classes of linear inequalities, depending on $C$, for the dihedral angles, which are necessary and sufficient conditions for the

Florin Belgun, Nicolas Ginoux, Hans-Bert Rademacher

We study spin structures on orbifolds. In particular, we show that if the singular set has codimension greater than 2, an orbifold is spin if and only if its smooth part is. On compact orbifolds, we show that any non-trivial twistor spinor admits at most one zero which is singular unless the orbifold is conformally equivalent to a round sphere. We show the s

P. Watson, H. Reinhardt

Coulomb gauge Yang-Mills theory is considered within the first order formalism. It is shown that the action is invariant under both the standard BRS transform and an additional component. The Ward-Takahashi identity arising from this non-standard transform is shown to be automatically satisfied by the equations of motion.

R. Jackiw

Homage is paid to E. Majorana by dedicating our recent work in his memory.

Giuseppe Bimonte, Enrico Calloni, Giampiero Esposito, Luigi Rosa

The influence of the gravity acceleration on the regularized energy-momentum tensor of the quantized electromagnetic field between two plane parallel conducting plates is derived. We use Fermi coordinates and work to first order in the constant acceleration parameter. A new simple formula for the trace anomaly is found to first order in the constant accelera

Margherita Disertori, Vincent Rivasseau

The simplest non commutative renormalizable field theory, the $ϕ_4^4$ model on four dimensional Moyal space with harmonic potential is asymptotically safe at one loop, as shown by H. Grosse and R. Wulkenhaar. We extend this result up to three loops. If this remains true at any loop, it should allow a full non perturbative construction of this model.

Clifford V. Johnson

We present a class of solvable models that resemble string theories in many respects but have a strikingly different non-perturbative sector. In particular, there are no exponentially small contributions to perturbation theory in the string coupling, which normally are associated with branes and related objects. Perturbation theory is no longer an asymptotic

Christoph Bergbauer, Dirk Kreimer

In this review we discuss the relevance of the Hochschild cohomology of renormalization Hopf algebras for local quantum field theories and their equations of motion.

Soren Wiesenfeldt

Without supersymmetry, the gauge couplings in the standard model with five Higgs doublets unify around 10^14 GeV. In this case, the trinified model, SU(3)_C x SU(3)_L x SU(3)_R x Z_3, with the minimal Higgs sector required for symmetry breaking, is the ideal grand-unified candidate. Small neutrino masses are generated via a radiative seesaw mechanism, withou

Keith A. Olive

A comparison is made between accelerator and direct detection constraints in constrained versions of the minimal supersymmetric standard model. Models considered are based on mSUGRA, where scalar and gaugino masses are unified at the GUT scale. In addition, the mSUGRA relation between the (unified) A and B parameters is assumed, as is the relation between $m

Gabriel Sanchez-Colon, Augusto Garcia

The latest measurement of the K_S to gamma gamma branching ratio clearly shows an enhancement over the current theoretical prediction. As in other K and B meson decays, this invites to consider the possibility of the contribution of new physics. We study a particular form of the latter, which may be referred to as manifest mirror symmetry. The experimental d

Manuel Drees, Wolfgang Hollik, Qingjun Xu

We calculate one-loop corrections to the decays of the next-to-lightest neutralino $\tildeχ_2^0$ into the lightest neutralino $\tildeχ_1^0$ and two leptons; this includes diagrams where a real photon is emitted. In cases where two-body decays $\tildeχ_2^0 \to \tilde{l}^\pm_1 l^\mp \to \tildeχ_1^0 l^- l^+$ are kinematically allowed, we calculate these decays

Alexander P. Bakulev

We illustrate the general scheme of the Sum Rule (SR) method using 2D Quantum Harmonic Oscillator (2DQHO) as a toy model. We introduce correlator, related to Green function of 2DQHO, and describe the property of Asymptotic Freedom for 2DQHO. We explain how the duality conception allows one to describe excited states. Finally we present numerical results and

G. H. Arakelyan, C. Merino, Yu. M. Shabelski

The asymmetry of strange baryon production in Kp interactions at high energies is considered in the framework of the Quark-Gluon String Model. The contribution of the String-Junction Mechanism to the strange baryon production is analysed.

Abhijit Bandyopadhyay, Amol Dighe, Anjan S. Joshipura

Flavor-dependent long range (LR) leptonic forces, like those mediated by the $L_e-L_μ$ or $L_e -L_τ$ gauge bosons, constitute a minimal extension of the standard model that preserves its renormalizability. We study the impact of such interactions on the solar neutrino oscillations when the interaction range $R_{LR}$ is much larger than the Earth-Sun distance

Xiaoyan Lin

We compare the non-photonic electron and $D^{0}$ meson $p_{T}$ distributions measured at RHIC with the PYTHIA Monte Carlo event generator in p+p collisions at $\sqrt{s_{NN}}=200$ GeV. A delta fragmentation function much harder than the Peterson function, consistent with recombination scheme for charm meson formation, is needed to match the experimental data.

Urs M. Heller

I review recent progress in the determination of the QCD phase diagram at finite temperature, in investigations of the nature of the transition or crossover from the hadronic phase to the quark-gluon plasma phase and in the determination of the equation of state. This talk will focus on results at zero chemical potential.

Jon A. Bailey

In staggered QCD, many staggered baryons correspond to each physical state. Taste violations lift the continuum degeneracies of the baryons and introduce nonzero off-diagonal elements in the mass matrix. While presenting no problem of principle, these splittings and mixings complicate analyses of simulation results. However, in special cases operators with g

A. Hietanen, K. Rummukainen

We use three dimensional reduced effective field theory (EQCD) and lattice calculations to determine the quark number susceptibility of QCD at high temperature. We find our results to agree well with known perturbative expansion as well as with other lattice data.

C. T. H. Davies, E. Follana, K. Hornbostel, G. P. Lepage

We use a relativistic highly improved staggered quark action to discretize charm quarks on the lattice. We calculate the masses and the dispersion relation for heavy-heavy and heavy-light meson states, and show that for lattice spacings below .1 fm, the discretization errors are at the few percent level. We also discuss the prospects for accurate calculation

Branson C. Stephens, Matthew D. Duez, Yuk Tung Liu, Stuart L. Shapiro

The capacity to model magnetohydrodynamical (MHD) flows in dynamical, strongly curved spacetimes significantly extends the reach of numerical relativity in addressing many problems at the forefront of theoretical astrophysics. We have developed and tested an evolution code for the coupled Einstein-Maxwell-MHD equations which combines a BSSN solver with a hig

J. W. Maluf, V. C. de Andrade, J. R. Steiner

We investigate the gravitational radiation produced by a linearly accelerated source in general relativity. The investigation is performed by studying the vacuum C metric, which is interpreted as representing the exterior space-time of an uniformly accelerating spherically symmetric gravitational source, and is carried out in the context of the teleparallel

J. Ambjorn, R. Janik, W. Westra, S. Zohren

We have shown how the quantization of two-dimensional quantum gravity with an action which contains only a positive cosmological constant and boundary cosmological constants leads to the emergence of a spacetime which can be described as a constant negative curvature spacetime with superimposed quantum fluctuations.

L. K. Tsui, P. T. Leung, J. Wu

In this paper the internal structure of a neutron star is shown to be inferrable from its gravitational-wave spectrum. Iteratively applying the inverse scheme of the scaled coordinate logarithmic perturbation method for neutron stars proposed by Tsui and Leung [Astrophys. J. {\bf 631}, 495 (2005)], we are able to determine the mass, the radius and the mass d

José F. Nieves, Palash B. Pal

This is a comment on the paper gr-qc/0605153, by Singh, Mobed and Papini.

Wasley S. Krogdahl

Flat space-time has not heretofore been thought a suitable locus in which to construct model universes because of the presumed necessity of incorporating gravitation in such models and because of the historical lack of a theory of gravitation in flat space-time. It is here shown that a Lorentz-invariant theory of gravitation can be formulated by incorporatin

Serban E. Vlad

The asynchronous systems $f$ are the models of the asynchronous circuits from digital electrical engineering. They are multi-valued functions that associate to each input $u:\mathbf{R}\to \{0,1\}^{m}$ a set of states $x\in f(u),$ where $x:\mathbf{R}\to \{0,1\}^{n}.$ The intersection of the systems allows adding supplementary conditions in modeling and the un

Marcus Hutter, Shane Legg

In evolutionary algorithms, the fitness of a population increases with time by mutating and recombining individuals and by a biased selection of more fit individuals. The right selection pressure is critical in ensuring sufficient optimization progress on the one hand and in preserving genetic diversity to be able to escape from local optima on the other han

Tuomo Kakkonen

In this paper, current dependencybased treebanks are introduced and analyzed. The methods used for building the resources, the annotation schemes applied, and the tools used (such as POS taggers, parsers and annotation software) are discussed.

Kenneth G. Libbrecht

This application note describes how to model diffusion-limited crystal growth from vapor using QuickField - a commercial finite-element analysis code. The crystal growth problem is cast into the format of a steady-state heat diffusion problem, which is one type of problem QuickField is designed to solve, and we derive the relevant conversion factors and corr

Lukasz Fidkowski, Michael Freedman, Chetan Nayak, Kevin Walker

We discuss Hilbert spaces spanned by the set of string nets, i.e. trivalent graphs, on a lattice. We suggest some routes by which such a Hilbert space could be the low-energy subspace of a model of quantum spins on a lattice with short-ranged interactions. We then explain conditions which a Hamiltonian acting on this string net Hilbert space must satisfy in

Ippei Danshita, Shunji Tsuchiya

We study the stability of Bose-Einstein condensates with superfluid currents in a one-dimensional periodic potential. By using the Kronig-Penney model, the condensate and Bogoliubov bands are analytically calculated and the stability of condensates in a periodic potential is discussed. The Landau and dynamical instabilities occur in a Kronig-Penney potential

M. M. Korshunov, S. G. Ovchinnikov

In this paper a mean-field theory for the spin-liquid paramagnetic non-superconducting phase of the p- and n-type High-$T_c$ cuprates is developed. This theory applied to the effective $t-t&#39;-t&#39;&#39;-J^*$ model with the {\it ab initio} calculated parameters and with the three-site correlated hoppings. The static spin-spin and kinematic correlation fun

Mario Cuoco, Julius Ranninger

We study an exchange coupled system of itinerant electrons and localized fermion pairs resulting in a resonant pairing formation. This system inherently contains resonating fermion pairs on bonds which lead to a superconducting phase provided that long range phase coherence between their constituents can be established. The prerequisite is that the resonatin

V. O. Dolocan, P. Lejay, D. Mailly, K. Hasselbach

Magnetic flux structures in single crystals of the layered spin triplet superconductor Sr$\_{2}$RuO$\_{4}$ are studied by scanning micro SQUID Force microscopy. Vortex chains appear as the applied field is tilted along the in-plane direction of the superconductor. The vortex chains align along the direction of the in-plane component of the applied magnetic f

K. Hasselbach, V. O. Dolocan, P. Lejay, D. Mailly

Scanning $μ$SQUID force microscopy is used to study magnetic flux structures in single crystals of the layered spin triplet superconductor Sr$\_{2}$RuO$\_{4}$. Images of the magnetic flux configuration above the $\vec{a}\vec{b}$-face of the cleaved crystal are acquired, mostly after field-cooling the sample. For low applied magnetic fields, individual vortic

Julien Gabelli, Gwendal Fève, Jean-Marc Berroir, Bernard Plaçais

What is the complex impedance of a fully coherent quantum resistance-capacitance (RC) circuit at GHz frequencies in which a resistor and a capacitor are connected in series? While Kirchhoff&#39;s laws predict addition of capacitor and resistor impedances, we report on observation of a different behavior. The resistance, here associated with charge relaxation

A. S. Moskvin

We address the effect of the field induced antiferromagnetism in paramagnetic state of the cuprate weak ferromagnet La$_2$CuO$_4$. The planar oxygen $^{17}$O Knight shift is shown to be an effective tool to inspect the effects of Dzyaloshinsky-Moriya coupling in cuprates in an external magnetic field. Field induced antiferromagnetism and anisotropic antiferr

W. Hellmann, R. Hennig, S. Goedecker, C. Umrigar

Density functional and quantum Monte Carlo calculations challenge the existence of a unique ground state structure for certain Si clusters. For Si clusters with more than a dozen atoms the lowest ten isomers are close in energy and for some clusters entropic effects can change the energetic ordering of the configurations. Isotope pure configurations with rot

J. Lloyd-Hughes, S. K. E. Merchant, F. Lan, H. H. Tan

The carrier dynamics of photoexcited electrons in the vicinity of the surface of (NH4)2S-passivated GaAs were studied via terahertz (THz) emission spectroscopy and optical-pump THz-probe spectroscopy. THz emission spectroscopy measurements, coupled with Monte Carlo simulations of THz emission, revealed that the surface electric field of GaAs reverses after p

V. A. Shalygin, H. Diehl, Ch. Hoffmann, S. N. Danilov

We report on the study of spin photocurrents in (110)-grown quantum well structures. Investigated effects comprise the circular photogalvanic effect and so far not observed circular photon drag effect. The experimental data can be described by an analytical expression derived from a phenomenological theory. A microscopic model of the circular photon drag eff

Takeo Hoshi, Takeo Fujiwara

Fundamental theories and practical methods for large-scale electronic structure calculations are given, in which the computational cost is proportional to the system size. Accuracy controlling methods for microscopic freedoms are focused on two practical solver methods, Krylov-subspace method and generalized-Wannier-state method. A general theory called the

Masahito Mochizuki, Masao Ogata

In order to understand the experimentally proposed phase diagrams of NaxCoO2.yH2O, we theoretically study the CoO2-layer-thickness dependence of magnetic and superconducting (SC) properties by analyzing a multiorbital Hubbard model using the random phase approximation. When the Co valence (s) is +3.4, we show that the magnetic fluctuation exhibits strong lay

Sebastian Müller, Stefan Heusler, Petr Braun, Fritz Haake

We describe a semiclassical method to calculate universal transport properties of chaotic cavities. While the energy-averaged conductance turns out governed by pairs of entrance-to-exit trajectories, the conductance variance, shot noise and other related quantities require trajectory quadruplets; simple diagrammatic rules allow to find the contributions of t

M. -A. Briere, M. V. Chubynsky, Normand Mousseau

Experimental results for covalent glasses have highlighted the existence of a new self-organized phase due to the tendency of glass networks to minimize internal stress. Recently, we have shown that an equilibrated self-organized two-dimensional lattice-based model also possesses an intermediate phase in which a percolating rigid cluster exists with a probab

Christophe Texier, Gilles Montambaux

We study the effect of the electron-electron interaction on the weak localization correction of a ring pierced by a magnetic flux. We compute exactly the path integral giving the magnetoconductivity for an isolated ring. The results are interpreted in a time representation. This allows to characterize the nature of the phase coherence relaxation in the ring.

E. Gubankova, E. Mishchenko, F. Wilczek

We demonstrate when p-wave pairing occurs between species whose free Fermi surfaces are mismatched the gap generally vanishes over a two-dimensional surface. We present detailed calculations of condensation energy, superfluid density (Meissner mass) and specific heat for such states. We also consider stability against separation into mixed phases. According

Shahin Jafarzadeh

The new B and V photoelectric observations of the beta Lyrae eclipsing binary DO Cas were obtained on 6 nights form December 2000 to January 2001. The observations were made at the Biruni Observatory, Shiraz, Iran and the light curves are analyzed using the Wilson light curve synthesis and differential correction code. So, the relative surface luminosities,

T. J. Davidge

Near-infrared images are used to investigate the brightest red stars in the disk of the nearby spiral galaxy M81. Red supergiants (RSGs) form a well-defined sequence on the color-magnitude diagrams (CMDs) that peaks near M_K = -11.5; RSGs with this peak brightness are seen throughout all fields that were studied, indicating that star formation occured over a

Alaina L. Henry, Jean L. Turner, Sara C. Beck, Lucian P. Crostwaite

We present high spectral resolution (v~12-16 km/s) Brackett line spectroscopy of the blue compact dwarf galaxy Henize 2-10 made with NIRSPEC on the Keck Telescope. The spatial resolution is seeing limited, at 1&#34;. We detect two distinct kinematic features separated by approximately 3&#34;, with heliocentric velocities of ~860 and ~890 km/s. In addition to

T. J. Davidge, J. B. Jensen

Broad- and narrow-band images covering the 1 - 4um wavelength interval are used to investigate the properties of the brightest AGB stars in the Local Group galaxy M32. The brightest AGB stars near the center of M32 have peak M_L&#39; brightnesses and K-L&#39; colors that are similar to those of luminous AGB stars in the Galactic disk, while the density of br

Xiaolei Zhang, Ronald J. Buta

Deep surveys conducted during the past decades have shown that galaxies in the distant universe are generally of more irregular shapes, and are disky in appearance and in their star formation rate, compared to galaxies in similar environments in the nearby universe. Given that the merger rate between z=2 and the local universe is far from adequate to account

J. F. Rowe, J. M. Matthews, C. Cameron, D. A. Bohlender

We present a total of 57 days of contiguous, high-cadence photometry (14 days in 2004 and 43 in 2005) of the star BD+18 4914 obtained with the MOST satellite. We detect 16 frequencies down to a signal-to-noise of 3.6 (amplitude \~ 0.5 mmag). Six of these are less than 3 cycles/day, and the other ten are between 7 and 16 cycles/day. We intrepret the low frequ

John J. Bochanski, Andrew A. West, Suzanne L. Hawley, Kevin R. Covey

We present template spectra of low-mass (M0-L0) dwarfs derived from over 4,000 Sloan Digital Sky Survey (SDSS) spectra. These composite spectra are suitable for use as medium-resolution (R ~ 1,800) radial velocity standards. We report mean spectral properties (molecular bandhead strengths,equivalent widths) and use the templates to investigate the effects of

C. M. Carollo, C. Scarlata, M. Stiavelli, R. F. G. Wyse

ABRIDGED: We use HSTACS and NICMOS imaging to study the structure and colors of a sample of nine late-type spirals. We find: (1) A correlation between bulge and disks scale-lengths, and a correlation between the colors of the bulges and those of the inner disks. Our data show a trend for bulges to be more metal-enriched than their surrounding disks, but othe

T. E. Oberst, S. C. Parshley, G. J. Stacey, T. Nikola

We report the first detection of the 205 um 3P1 - 3P0 [NII] line from a ground-based observatory using a direct detection spectrometer. The line was detected from the Carina star formation region using the South Pole Imaging Fabry-Perot Interferometer (SPIFI) on the Antarctic Submillimeter Telescope and Remote Observatory (AST/RO) at South Pole. The [NII] 20

N. Gehrels, J. P. Norris, V. Mangano, S. D. Barthelmy

Gamma ray bursts (GRBs) are known to come in two duration classes, separated at ~2 s. Long bursts originate from star forming regions in galaxies, have accompanying supernovae (SNe) when near enough to observe and are likely caused by massive-star collapsars. Recent observations show that short bursts originate in regions within their host galaxies with lowe

D. Li, T. Velusamy, P. F. Goldsmith, W. D. Langer

We have surveyed submillimeter continuum emission from relatively quiescent regions in the Orion molecular cloud to determine how the core mass function in a high mass star forming region compares to the stellar initial mass function. Such studies are important for understanding the evolution of cores to stars, and for comparison to formation processes in hi

Nickolas Moeckel, John Bally

Most massive stars are found in the center of dense clusters, and have a companion fraction much higher than their lower mass siblings; the massive stars of the Trapezium core in Orion have ~ 1.5 companions each. This high multiplicity could be a consequence of formation via a capture scenario, or it could be due to fragmentation of the cores that form the m

Steven W. Barwick

The ARIANNA concept utilizes the Ross Ice Shelf near the coast of Antarctica to increase the sensitivity to cosmogenic neutrinos by roughly an order of magnitude when compared to the sensitivity of existing detectors and those under construction. Therefore, ARIANNA can test a wide variety of scenarios for GZK neutrino production, and probe for physics beyond

Jeffrey M. Anderson, Zhi-Yun Li, Ruben Krasnopolsky, Roger D. Blandford

Outflows can be loaded and accelerated to high speeds along rapidly rotating, open magnetic field lines by centrifugal forces. Whether such magnetocentrifugally driven winds are stable is a longstanding theoretical problem. As a step towards addressing this problem, we perform the first large-scale 3D MHD simulations that extend to a distance $\sim 10^2$ tim

Carl H. Gibson

The standard model for gravitational structure formation in astrophysics, astronomy, and cosmology is questioned. Cold dark matter (CDM) hierarchical clustering cosmology neglects particle collisions, viscosity, turbulence and diffusion and makes predictions in conflict with observations. From Jeans 1902 and CDMHC, the non-baryonic dark matter NBDM forms sma

S. Desidera

One of the hypothesis to explain the outburst of V838 Mon is the engulfment of planets. More than 170 extrasolar planets were discovered in the past years. Their properties and the characteristics of their host stars can be used to evaluate of the plausibility of this hypothesis. However, the large mass and young age of V838 Mon make the object rather differ

S. Campana, G. Tagliaferri, D. Malesani, L. Stella

A good fraction of GRBs detected by Swift are at a large redshift (up to z=6.3, so far). Their study allows us to investigate, among other things, the cosmic star formation in the early Universe (possibly up to the re-ionization era) and the chemical enrichment of the high-redshift gas. Here we present and discuss a method of selection which identifies high-