October 2008 arXiv papers — page 13

L. J. Goicoechea, V. N. Shalyapin, R. Gil-Merino, A. Ullán

We present a detailed structure function analysis of the UV variability of Q0957+561. From new optical observations, we constructed normalized structure functions of the quasar luminosity at restframe wavelengths of 2100 and 2600 Å. Old optical records also allow the structure function to be obtained at 2100 Å, but 10 years ago in the observer's frame. T

Amir H. Fariborz, Renata Jora, Joseph Schechter

A generalized linear sigma model is employed to study the quark structure of low lying scalar as well as pseudoscalar states. The model allows the possible mixing of quark anti-quark states with others made of two quarks and two antiquarks but no a priori assumption is made about the quark contents of the predicted physical states. Effects of SU(3) symmetry

O. Benichou, J. Desbois

We consider a particle diffusing along the links of a general graph possessing some absorbing vertices. The particle, with a spatially-dependent diffusion constant D(x) is subjected to a drift U(x) that is defined in every point of each link. We establish the boundary conditions to be used at the vertices and we derive general expressions for the average tim

V. A. Kudryavtsev

The paper describes two Monte Carlo codes dedicated to muon simulations: MUSIC (MUon SImulation Code) and MUSUN (MUon Simulations UNderground). MUSIC is a package for muon transport through matter. It is particularly useful for propagating muons through large thickness of rock or water, for instance from the surface down to underground/underwater laboratory.

Marcelo Aguiar, Jean-Christophe Novelli, Jean-Yves Thibon

We construct unital extensions of the higher order peak algebras defined by Krob and the third author in [Ann. Comb. 9 (2005), 411--430.], and show that they can be obtained as homomorphic images of certain subalgebras of the Mantaci-Reutenauer algebras of type B. This generalizes a result of Bergeron, Nyman and the first author [Trans. AMS 356 (2004), 2781-

I. M. Miron, P. -J. Zermatten, G. Gaudin, S. Auffret

We report the direct measurement of the non-adiabatic component of the spin-torque in domain walls. Our method is independent of both the pinning of the domain wall in the wire as well as of the Gilbert damping parameter. We demonstrate that the ratio between the non-adiabatic and the adiabatic components can be as high as 1, and explain this high value by t

S. Marrone, B. B. Wojtsekhowski, A. Acha, E. Cisbani

We report on the design and commissioning of two silica aerogel Cherenkov detectors with different refractive indices. In particular, extraordinary performance in terms of the number of detected photoelectrons was achieved through an appropriate choice of PMT type and reflector, along with some design considerations. After four years of operation, the number

Jisoo Byun, Steven G. Krantz

We study domains in complex $n$-space with automorphism group that does not depend on the full $n$ dimensions of the ambient space. A sufficient geometric condition is obtained to guarantee that a domain has such a "thin" automorphism group. Examples are provided to illustrate the ideas.

Uijin Jung

Given a code from a shift space to an irreducible sofic shift, any two of the following three conditions -- open, constant-to-one, (right or left) closing -- imply the third. If the range is not sofic, then the same result holds when bi-closingness replaces closingness. Properties of open mappings between shift spaces are investigated in detail. In particula

C. Cafaro, S. A. Ali

In this paper, we review our novel information geometrodynamical approach to chaos (IGAC) on curved statistical manifolds and we emphasize the usefulness of our information-geometrodynamical entropy (IGE) as an indicator of chaoticity in a simple application. Furthermore, knowing that integrable and chaotic quantum antiferromagnetic Ising chains are characte

Carlo Cafaro

In this paper, we report our latest research on a novel theoretical information-geometric framework suitable to characterize chaotic dynamical behavior of arbitrary complex systems on curved statistical manifolds. Specifically, an information-geometric analogue of the Zurek-Paz quantum chaos criterion of linear entropy growth and an information-geometric cha

Carlo Cafaro

In this Letter, we propose a novel information-geometric characterization of chaotic (integrable) energy level statistics of a quantum antiferromagnetic Ising spin chain in a tilted (transverse) external magnetic field. Finally, we conjecture our results might find some potential physical applications in quantum energy level statistics.

C. Cafaro, S. A. Ali

A novel information-geometrodynamical approach to chaotic dynamics (IGAC) on curved statistical manifolds based on Entropic Dynamics (ED) is presented and a new definition of information geometrodynamical entropy (IGE) as a measure of chaoticity is proposed. The general classical formalism is illustrated in a relatively simple example. It is shown that the h

Carlo Cafaro

A novel information-geometric approach to chaotic dynamics on curved statistical manifolds based on Entropic Dynamics (ED) is suggested. Furthermore, an information-geometric analogue of the Zurek-Paz quantum chaos criterion is proposed. It is shown that the hyperbolicity of a non-maximally symmetric 6N-dimensional statistical manifold M_{s} underlying an ED

Aparna Maybhate, Paul Goudfrooij, Francois Schweizer, Thomas H. Puzia

We present a study of the globular cluster systems of four early-type poststarburst galaxies using deep g and I-band images from the ACS camera aboard the Hubble Space Telescope (HST). All the galaxies feature shells distributed around their main bodies and are thus likely merger remnants. The color distribution of the globular clusters in all four galaxies

Russell D. Blyth, Francesco Fumagalli, Marta Morigi

We study the non-abelian tensor square $G\otimes G$ for the class of groups G that are finitely generated modulo their derived subgroup. In particular, we find conditions on G/G' so that $G\otimes G$ is isomorphic to the direct product of $\nabla(G)$ and the non-abelian exterior square $G\wedge G$. For any group G, we characterize the non-abelian exterio

V. N. Shalyapin, L. J. Goicoechea, E. Koptelova, A. Ullan

We extend the gr-band time coverage of the gravitationally lensed double quasar Q0957+561. New gr light curves permit us to detect significant intrinsic fluctuations, to determine new time delays, and thus to gain perspective on the mechanism of intrinsic variability in Q0957+561. We use new optical frames of Q0957+561 in the g and r passbands from January 2

Claudine Brucks, Christoph Schommer

For human beings, the processing of text streams of unknown size leads generally to problems because e.g. noise must be selected out, information be tested for its relevance or redundancy, and linguistic phenomenon like ambiguity or the resolution of pronouns be advanced. Putting this into simulation by using an artificial mind-map is a challenge, which offe

C Sivaram, Kenath Arun

Recently there has been a lot of interest in the search for extra dimensions. If gravity propagates in extra dimensions then gravity would become as strong as other interactions. This could also lead to the production of mini black holes. Here we have discussed how even without considering extra dimensions gravitational effects of weak interactions could sho

C Sivaram

The relevant physics for the possible formation of black holes in the LHC is discussed.

Natalya A. Zimbovskaya

In this work we present the results of theoretical analysis of the de Haas-van Alphen oscillations in quasi-two-dimensional conductors. We have been studying the effect of the Fermi-liquid correlations of charge carriers on the above oscillations. It was shown that at reasonably low temperatures and weak electron scattering the Fermi-liquid interactions may

H. Nomura, Y. Aikawa, Y. Nakagawa, T. J. Millar

We have studied the dependence of the profiles of molecular abundances and line emission on the accretion flow in the hot ($\ga 100$K) inner region of protoplanetary disks. The gas-phase reactions initiated by evaporation of the ice mantle on dust grains are calculated along the accretion flow. We focus on methanol, a molecule that is formed predominantly th

D. Sornette

This essay suggests that a proper assessment of the presently unfolding financial crisis, and its cure, requires going back at least to the late 1990s, accounting for the cumulative effect of the ITC, real-estate and financial derivative bubbles. We focus on the deep loss of trust, not only in Wall Street, but more importantly in Main Street, and how to reco

P. Larson, S. Satpathy

We study the changes in the Fermi surface with electron doping in the LaFeAsO$_{1-x}$F$_x$ superconductors with density-functional supercell calculations using the linearized augmented planewave (LAPW) method. The supercell calculations with explicit F substitution are compared with those obtained from the virtual crystal approximation (VCA) and from a simpl

Chuying Fang

n this paper we study ad-nilpotent ideals of a complex simple Lie algebra $\ccg$ and their connections with affine Weyl groups and nilpotent orbits. We define a left equivalence relation for ad-nilpotent ideals based on their normalizer and generators, and prove that the equivalence relation is compatible with the left cell structure of affine Weyl group of

Chuying Fang

In this paper we study ad-nilpotent ideals of a complex simple Lie algebra $\ccg$ and their connections with affine Weyl groups and nilpotent orbits. We define a left equivalence relation for ad-nilpotent ideals based on their normalizer and generators, and prove that the equivalence relation is compatible with the left cell structure of affine Weyl group of

A. N. Lavrov, L. P. Kozeeva, M. R. Trunin, V. N. Zverev

The remarkable sensitivity of the c-axis resistivity and magnetoresistance in cuprates to the spin ordering is used to clarify the doping-induced transformation from an antiferromagnetic (AF) insulator to a superconducting (SC) metal in RBa_2Cu_3O_{6+x} (R = Lu, Y) single crystals. The established phase diagram demonstrates that the AF and SC regions apparen

M. G. Silveirinha, C. A. Fernandes, J. R. Costa, C. R. Medeiros

Following our recent theoretical studies [M. G. Silveirinha, C. A. Fernandes, Phys. Rev. B, 78, 033108, 2008], it is experimentally verified that an array of crossed metallic wires may behave as a nonresonant material with extremely large index of refraction at microwaves, and may enable the realization of ultra-subwavelength waveguides.

R. Campoamor-Stursberg, S. G. Low

Given a semidirect product $\frak{g}=\frak{s}\uplus\frak{r}$ of semisimple Lie algebras $\frak{s}$ and solvable algebras $\frak{r}$, we construct polynomial operators in the enveloping algebra $\mathcal{U}(\frak{g})$ of $\frak{g}$ that commute with $\frak{r}$ and transform like the generators of $\frak{s}$, up to a functional factor that turns out to be a Ca

R. Campoamor-Stursberg

We show that the Inönü-Wigner contraction naturally associated to a reduction chain $\frak{s}\supset \frak{s}^{\prime}$ of semisimple Lie algebras induces a decomposition of the Casimir operators into homogeneous polynomials, the terms of which can be used to obtain additional mutually commuting missing label operators for this reduction. The adjunction of t

M. G. Silveirinha, C. A. Fernandes, J. R. Costa

We propose a superlens formed by an ultra-dense array of crossed metallic wires. It is demonstrated that due to the anomalous interaction between crossed wires, the structured substrate is characterized by an anomalously high index of refraction and supports strongly confined guided modes with very short propagation wavelengths. It is theoretically proven th

Anders Johansson, Dirk Helbing, Habib Z. Al-Abideen, Salim Al-Bosta

The study of crowd dynamics is interesting because of the various self-organization phenomena resulting from the interactions of many pedestrians, which may improve or obstruct their flow. Besides formation of lanes of uniform walking direction and oscillations at bottlenecks at moderate densities, it was recently discovered that stop-and-go waves [D. Helbin

Julien Malzac, Renaud Belmont

We discuss the origin of the dramatically different X-ray spectral shapes observed in the Low Hard State (LHS: dominated by thermal comptonisation) and the High Soft State (HSS: dominated by the accretion disc thermal emission and non-thermal comptonisation in the corona). We present numerical simulations using a new code accounting for the so-called synchro

Anders Johansson, Dirk Helbing, Pradyumn Shukla

Based on suitable video recordings of interactive pedestrian motion and improved tracking software, we apply an evolutionary optimization algorithm to determine optimal parameter specifications for the social force model. The calibrated model is then used for large-scale pedestrian simulations of evacuation scenarios, pilgrimage, and urban environments.

R. Alicki, M. Fannes, M. Horodecki

The thermalization process of the 2D Kitaev model is studied within the Markovian weak coupling approximation. It is shown that its largest relaxation time is bounded from above by a constant independent of the system size and proportional to $\exp(2Δ/kT)$ where $Δ$ is an energy gap over the 4-fold degenerate ground state. This means that the 2D Kitaev model

Karsten Peters, Anders Johansson, Audrey Dussutour, Dirk Helbing

Swarm intelligence is widely recognized as a powerful paradigm of self-organized optimization, with numerous examples of successful applications in distributed artificial intelligence. However, the role of physical interactions in the organization of traffic flows in ants under crowded conditions has only been studied very recently. The related results sugge

W. S. Su, B. R. Wu, T. C. Leung

We have performed a first-principles study on the deformation effect of the electronic structures of graphite nanoribbon arrays with zigzag edges on both sides, and the edge atoms are terminated with hydrogen atoms. A uniaxial strain is considered to have deformation effect on the graphite nanoribbons. We found that the antiferromagnetic arrangement of the s

I. R. Shein, A. L. Ivanovskii

The full-potential linearized augmented plane wave method with the generalized gradient approximation for the exchange and correlation potential (LAPW-GGA) is used to understand the electronic band structure of fluorine-arsenide SrFeAsF as a possible parent material for a new group of oxygen-free FeAs superconductors. The electronic bands, density of states,

Gordon E. Sarty, Laszlo L. Kiss, Richard Huziak, Lionel J. J. Catalan

The high-mass X-ray binary RX J0146.9+6121, with optical counterpart LS I+61 235 (V831 Cas), is an intriguing system on the outskirts of the open cluster NGC 663. It contains the slowest X-ray pulsar known with a pulse period of around 1400s and, primarily from the study of variation in the emission line profile of H alpha, it is known to have a Be decretion

C. Espaillat, J. Muzerolle, J. Hernandez, C. Briceno

Here we present the Spitzer IRS spectrum of CVSO 224, the sole transitional disk located within the ~10 Myr old 25 Orionis group in Orion OB1a. A model fit to the spectral energy distribution of this object indicates a ~7 AU inner disk hole that contains a small amount of optically thin dust. In previous studies, CVSO 224 had been classified as a weak-line T

Lawrence M. Krauss, James Dent, Glenn D. Starkman

The recent suggestion that late time quantum dynamics may be important for resolving cosmological issues associated with our observed universe requires a consideration of several subtle issues associated with quantum cosmology, as we describe here. The resolution of these issues will be important if we are to be able to properly ascribe probability measures

Shihoko Ishii

This paper shows some criteria for a scheme of finite type over an algebraically closed field to be non-singular in terms of jet schemes. For the base field of characteristic zero, the scheme is non-singular if and only if one of the truncation morphisms of its jet schemes is flat. For the positive characteristic case, we obtain a similar characterization un

H. Awaki, Y. Terashima, Y. Higaki, Y. Fukazawa

We have obtained a broad-band spectrum of the Compton-thick Seyfert 2 galaxy NGC 2273 with Suzaku. The spectrum reveals the first detection of hard X-rays above ~10 keV from NGC 2273. The broad-band spectrum is well represented by a three-component model, accompanied by both a strong iron Ka line with an equivalent width of ~ 1.8 keV and several weak lines.

E. Iwaki, E. Jespers, S. O. Juriaans, A. C. Souza Filho

In 1996 Jespers and Wang classified finite semigroups whose integral semigroup ring has finitely many units. In a recent paper, Iwaki-Juriaans-Souza Filho continued this line of research by partially classifying the finite semigroups whose rational semigroup algebra %over a field of characteristic zero, contains a ${\mathbb{Z}}$-order with hyperbolic unit gr

Jacob Shotwell

It is shown that no local periodicity is equivalent to the aperiodicity condition for arbitrary finitely-aligned k-graphs. This allows us to conclude that C*(Λ) is simple if and only if Λis cofinal and has no local periodicity.

Xingbo Zhao, Ralf Rapp

$J/ψ$ production at forward and midrapidity at the Relativistic Heavy-Ion Collider (RHIC) is calculated within a previously constructed rate-equation approach accounting for both direct production and regeneration from $c$ and $\bar c$. The results are compared to experimental data. The observed stronger suppression at forward rapidity can be qualitatively e

Cristian Conde, Gabriel Larotonda

The notion of nonpositive curvature in Alexandrov's sense is extended to include p-uniformly convex Banach spaces. Infinite dimensional manifolds of semi-negative curvature with a p-uniformly convex tangent norm fall in this class on nonpositively curved spaces, and several well-known results, such as existence and uniqueness of best approximations from

S. O. Juriaans, C. Polcino Milies, A. C. Souza Filho

We investigate the structure of an alternative finite dimensional $\Q$-algebra $\mathfrak{A}$ subject to the condition that for a $\Z$-order $Γ\subset \mathfrak{A}$, and thus for every $\Z$-order of $\mathfrak{A}$, the loop of units of $\U (Γ)$ does not contain a free abelian subgroup of rank two. In particular, we prove that the radical of such an algebra a

M. K. McClure

Using \emph{Spitzer} Infrared Spectrograph observations of G0--M4 III stars behind dark clouds, I construct $5-20μ$m empirical extinction curves for $0.3\leq A_K<7$, which is equivalent to $A_V$ between $\approx$ 3 and 50. For $A_K<1$ the curve appears similar to the \citet{mathis90} diffuse interstellar medium extinction curve, but with a greater degree of

Frieda Dukesz, Marina Zilbergerts, Lea F. Santos

We consider a one-dimensional quantum many-body system and investigate how the interplay between interaction and on-site disorder affects spatial localization and quantum correlations. The hopping amplitude is kept constant. To measure localization, we use the number of principal components (NPC), which quantifies the spreading of the system eigenstates over

Colin Morningstar

Progress in extracting excited-state baryon masses in lattice QCD using large sets of spatially-extended operators is presented. The use of stochastic estimates of all-to-all quark propagators with variance reduction techniques is described. Such techniques are crucial for incorporating multi-hadron operators into the correlation matrices of the hadron opera

Mourad E. H. Ismail, Erik Koelink

Given an operator L acting on a function space, the J-matrix method consists of finding a sequence y_n of functions such that the operator L acts tridiagonally on y_n with respect to n. Once such a tridiagonalization is obtained, a number of characteristics of such an operator L can be obtained. In particular, information on eigenvalues and eigenfunctions, b

H L. Worters, M. T. Rushton, S. P. S. Eyres, T. R. Geballe

We present observations of Sakurai's Object obtained at 1-5um between 2003 and 2007. By fitting a radiative transfer model to an echelle spectrum of CO fundamental absorption features around 4.7um, we determine the excitation conditions in the line-forming region. We find 12C/13C~3.5, consistent with CO originating in ejecta processed by the very late therma

Xiaoyan Ma, Holley E. Lynch, Peter C. Scully, M. Shane Hutson

We use laser hole-drilling to assess the mechanics of an embryonic epithelium during development - in vivo and with subcellular resolution. We ablate a subcellular cylindrical hole clean through the epithelium, and track the subsequent recoil of adjacent cells (on ms time scales). We investigate dorsal closure in the fruit fly with emphasis on apical constri

Sinisa Coh, David Vanderbilt

We extend the Berry-phase concept of polarization to insulators having a non-zero value of the Chern invariant. The generalization to such Chern insulators requires special care because of the partial occupation of chiral edge states. We show how the integrated bulk current arising from an adiabatic evolution can be related to a difference of bulk polarizati

Bradly Alicea

In this paper, a model for understanding the effects of selection using systems- level computational approaches is introduced. A number of concepts and principles essential for understanding the motivation for constructing the model will be introduced first. This will be followed by a description of parameters, measurements, and graphical representations use

Marina Seikel, Dominik J. Schwarz

We present a calibration-independent test of the accelerated expansion of the universe using supernova type Ia data. The test is also model-independent in the sense that no assumptions about the content of the universe or about the parameterization of the deceleration parameter are made and that it does not assume any dynamical equations of motion. Yet, the

Brian Meadows

The phenomenon of mixing in neutral meson systems has now been observed in all flavours, but only in the past year in the D0 system. The standard model anticipated that, for the charm sector, the mixing rate would be small, and also that CP violation, either in mixing or in direct decay, would be below the present levels of observability. It is hoped that fu

Jiangyong Jia

We review the physics performance of the ATLAS detector for hard probes in heavy ion collisions, focusing on three topics: jet reconstruction, direct photon measurement, and heavy flavor jet tagging.

Matthew Ando, Andrew J. Blumberg, David J. Gepner, Michael J. Hopkins

We review and extend the theory of Thom spectra and the associated obstruction theory for orientations. We recall (from May, Quinn, and Ray) that a commutative ring spectrum A has a spectrum of units gl(A). To a map of spectra f: b -> bgl(A), we associate a commutative A-algebra Thom spectrum Mf, which admits a commutative A-algebra map to R if and only if b

D. Gross, S. Flammia, J. Eisert

It is often argued that entanglement is at the root of the speedup for quantum compared to classical computation, and that one needs a sufficient amount of entanglement for this speedup to be manifest. In measurement-based quantum computing (MBQC), the need for a highly entangled initial state is particularly obvious. Defying this intuition, we show that qua

Samson Saneblidze

Given a simply connected space $X$ with the cohomology $H^*(X;{\mathbb Z}_2)$ to be polynomial, we calculate the loop cohomology algebra $H^*(ΩX;{\mathbb Z}_2)$ by means of the action of the Steenrod cohomology operation $Sq_1$ on $H^*(X;{\mathbb Z}_2).$ As a consequence we obtain that $H^*(ΩX;{\mathbb Z}_2)$ is the exterior algebra if and only if $Sq_1$ is

Lee Samuel Finn

The derivation of the response function of an interferometric gravitational wave detector is a paradigmatic calculation in the field of gravitational wave detection. Surprisingly, the standard derivation of the response wave detectors makes several unjustifiable assumptions, both conceptual and quantitative, regarding the coordinate trajectory and coordinate

H. Brenner, H. Fischbacher-Weitz

We use geometric and cohomological methods to show that given a degree bound for membership in ideals of a fixed degree type in the polynomial ring P=k[x_0,..., x_d], one obtains a good generic degree bound for membership in the tight closure of an ideal of that degree type in any standard-graded k-algebra R of dimension d+1. This indicates that the tight cl

Martin Kerin

As a means to better understanding manifolds with positive curvature, there has been much recent interest in the study of non-negatively curved manifolds which contain points at which all 2-planes have positive curvature. We show that there are generalisations of the well-known Eschenburg spaces and quotients of $\sph^7 \x \sph^7$ which admit metrics with th

Robert Brandenberger, Hassan Firouzjahi, Johanna Karouby, Shahram Khosravi

The formalism for computing the gravitational power radiation from excitations on cosmic strings forming a junction is presented and applied to the simple case of co-planar strings at a junction when the excitations are generated along one string leg. The effects of polarization of the excitations and of the back-reaction of the gravitational radiation on th

Sevag Gharibian

Given the density matrix rho of a bipartite quantum state, the quantum separability problem asks whether rho is entangled or separable. In 2003, Gurvits showed that this problem is NP-hard if rho is located within an inverse exponential (with respect to dimension) distance from the border of the set of separable quantum states. In this paper, we extend this

T. I. Baturina, A. Yu. Mironov, V. M. Vinokur, M. R. Baklanov

We investigate the insulating phase that forms in a titanium nitride film in a close vicinity of the disorder-driven superconductor-insulator transition. In zero magnetic field the temperature dependence of the resistance reveals a sequence of distinct regimes upon decreasing temperature crossing over from logarithmic to activated behavior with the variable-

Davide Forcella, Amihay Hanany, Alberto Zaffaroni

We analyze the action of Toric (Seiberg) duality on the combined mesonic and baryonic moduli space of quiver gauge theories obtained from D3 branes at Calabi-Yau singularities. We analyze in particular the structure of the master space, the complete moduli space for one brane, for different toric phases of a given singularity. We show that the Hilbert Series

M. H. S. Amin

The adiabatic theorem provides the basis for the adiabatic model of quantum computation. Recently the conditions required for the adiabatic theorem to hold have become a subject of some controversy. Here we show that the reported violations of the adiabatic theorem all arise from resonant transitions between energy levels. In the absence of fast driven oscil

Tyce DeYoung

AMANDA is a first-generation high energy neutrino telescope, which has taken data at the South Pole in its final configuration since 2000. Results from seven years of operation are presented here, including observation of the atmopheric neutrino flux and searches for astrophysical neutrinos from cosmic ray accelerators, gamma ray bursts, and dark matter anni

J. Gorosabel, A. de Ugarte Postigo, A. J. Castro-Tirado, I. Agudo

The possible existence of a continuum encompassing the diversity of explosive stellar deaths,ranging from ordinary SNe to relativistic hypernovae associated with long duration GRBs, is under intense debate. In this context, SN2008D associated with XT080109 could represent a paradigmatic case, since it might exemplify a potential borderline event. The main ai

Nadav Drukker, Jaume Gomis, Donovan Young

We construct vortex loop operators in the three-dimensional N = 6 supersymmetric Chern-Simons theory recently constructed by Aharony, Bergman, Jafferis and Maldacena. These disorder loop operators are specified by a vortex-like singularity for the scalar and gauge fields along a one dimensional curve in spacetime. We identify the 1/2, 1/3 and 1/6 BPS loop op

W. Wester

GammeV is an experiment conducted at Fermilab that employs the light shining through a wall technique to search for axion-like particles and employs a particle in a jar technique to search for dilaton-like chameleon particles. We obtain limits on the coupling of photons to an axion-like particle that extend previous limits for both scalars and pseudoscalars

Ioannis Parissis

Let M denote the maximal function along the polynomial curve p(t)=(t,t^2,...,t^d) in R^d: M(f)=sup_{r>0} (1/2r) \int_{|t|<r} |f(x-p(t))| dt. We show that the L^2-norm of this operator grows at most logarithmically with the parameter d: ||M||_2 < c log d ||f||_2, where c>0 is an absolute constant. The proof depends on the explicit construction of a &#34;parab

Heike Schwager, J. Ignacio Cirac, Géza Giedke

The coherent coupling of flying photonic qubits to stationary matter-based qubits is an essential building block for quantum communication networks. We show how such a quantum interface can be realized between a traveling-wave optical field and the polarized nuclear spins in a singly charged quantum dot strongly coupled to a high-finesse optical cavity. By a

Eric Braaten, Daekyoung Kang, Jungil Lee, Chaehyun Yu

The leading-order parton processes that produce a dilepton with large transverse momentum predict that the transverse polarization should increase with the transverse momentum for almost any choice of the quantization axis for the spin of the virtual photon. The rate of approach to complete transverse polarization depends on the choice of spin quantization a

Álvaro Martínez-Pérez

We prove that a PQ-symmetric homeomorphism between two complete metric spaces can be extended to a quasi-isometry between their hyperbolic approximations. This result is used to prove that two visual Gromov hyperbolic spaces are quasi-isometric if and only if there is a PQ-symmetric homeomorphism between their boundaries.

Manfred Hartl, Christine Vespa

We study polynomial functors of degree 2, called quadratic, with values in the category of abelian groups $Ab$, and whose source category is an arbitrary category $\C$ with null object such that all objects are colimits of copies of a generating object $E$ which is small and regular projective; this includes all pointed algebraic varieties. More specifically

Tomáš Dohnal, Hannes Uecker

Gap solitons near a band edge of a spatially periodic nonlinear PDE can be formally approximated by solutions of Coupled Mode Equations (CMEs). Here we study this approximation for the case of the 2D Periodic Nonlinear Schrödinger / Gross-Pitaevskii Equation with a non-separable potential of finite contrast. We show that unlike in the case of separable poten

Sergey Zaitsev, Alexander Zaitsev, Andrei Leonidov, Vladimir Trainin

Market Mill is a complex dependence pattern leading to nonlinear correlations and predictability in intraday dynamics of stock prices. The present paper puts together previous efforts to build a dynamical model reflecting the market mill asymmetries. We show that certain properties of the conditional dynamics at a single time scale such as a characteristic s

Richard J. Cook

There is a set of first-order differential equations for the curvature tensor in general relativity (the curvature equations or CEs for short) that are strikingly similar to the Maxwell equations of electrodynamics. This paper considers whether Mother Nature may have used the same basic pattern for her laws of gravitation and electrodynamics, in which case t

Louis Crane

We propose a mathematically concrete way of modelling the suggestion that in quantum gravity the spacetime disappears, replacing it with a discrete approximation to the causal path space described as an object in a model category. One of the versions of our models appears as a thickening of spacetime, which we interpret as a formulation of relational geometr

CAST Collaboration, E. Arik, S. Aune, D. Autiero

We have searched for solar axions or other pseudoscalar particles that couple to two photons by using the CERN Axion Solar Telescope (CAST) setup. Whereas we previously have reported results from CAST with evacuated magnet bores (Phase I), setting limits on lower mass axions, here we report results from CAST where the magnet bores were filled with \hefour ga

Ole Steuernagel

Superpositions of paraxial laser beam modes to generate atom-optical lenses based on the optical dipole force are investigated theoretically. Thin, wide, parabolic, cylindrical and circular atom lenses with numerical apertures much greater than those reported in the literature to date can be synthesized. This superposition approach promises to make high qual

Jacob Bernstein, Christine Breiner

In this paper, we show that a complete embedded minimal surface in $\Real^3$ with finite topology and one end is conformal to a once-punctured compact Riemann surface. Moreover, using the conformality and embeddedness, we examine the Weierstrass data and conclude that every such surface has Weierstrass data asymptotic to that of the helicoid. More precisely,

Fabrice Bethuel, Philippe Gravejat, Jean-Claude Saut, Didier Smets

The fact that the Korteweg-de-Vries equation offers a good approximation of long-wave solutions of small amplitude to the one-dimensional Gross-Pitaevskii equation was derived several years ago in the physical literature. In this paper, we provide a rigorous proof of this fact, and compute a precise estimate for the error term. Our proof relies on the integr

Hendrik Bluhm, Nicholas C. Koshnick, Julie A. Bert, Martin E. Huber

The authors have measured the magnetic response of 33 individual cold mesoscopic gold rings, one ring at a time. The response of some sufficiently small rings has a component that is periodic in the flux through the ring and is attributed to a persistent current. Its period is close to h/e, and its sign and amplitude vary between rings. The amplitude distrib

J. D. Thrower, M. P. Collings, F. J. M. Rutten, M. R. S. McCoustra

Experimental results on the thermal desorption of benzene (C6H6) from amorphous silica (SiO2) are presented. The amorphous SiO2 substrate was imaged using atomic force microscopy (AFM), revealing a surface morphology reminiscent of that of interplanetary dust particles (IDPs). Temperature programmed desorption (TPD) experiments were conducted for a wide rang

Wolfgang Rohringer, Robert Buecker, Stephanie Manz, Thomas Betz

We employ an evolutionary algorithm to automatically optimize different stages of a cold atom experiment without human intervention. This approach closes the loop between computer based experimental control systems and automatic real time analysis and can be applied to a wide range of experimental situations. The genetic algorithm quickly and reliably conver

S. G. Bondarenko, V. V. Burov, W. -Y. Pauchy Hwang, E. P. Rogochaya

The multirank separable kernels of the neutron-proton interaction for uncoupled $S$ and $P$ partial waves (with the total angular momentum $J$=0,1) are proposed. Two different methods of a relativistic generalization of initially nonrelativistic form factors parametrizing the kernel are considered. Using the constructed kernels the experimental data for phas

A. N. Yaresko, G. -Q. Liu, V. N. Antonov, O. K. Andersen

The wave-vector q and doping (x,y) dependences of the magnetic energy, iron moment, and effective exchange interactions in LaFeAsO{1-x}F{x} and Ba{1-2y}K{2y}Fe2As2 are studied by self-consistent LSDA calculations for co-planar spin spirals. For the undoped compounds (x=0, y=0), the minimum of the calculated total energy, E(q), is for q corresponding to strip

Manuel Masip, Iacopo Mastromatteo

In models with extra dimensions the fundamental scale of gravity M_D could be of order TeV. In that case the interaction cross section between a cosmic proton of energy E and a dark matter particle χwill grow fast with E for center of mass energies \sqrt{2m_χE} above M_D, and it could reach 1 mbarn at E\approx 10^9 GeV. We show that these gravity-mediated pr

James A. Stickney, Matthew B. Squires, James Scoville, Paul Baker

The coherence time, and thus sensitivity, of trapped atom interferometers that use non-degenerate gasses are limited by the collisions between the atoms. An analytic model that describes the effects of collisions between atoms in an interferometer is developed. It is then applied to an interferometer using a harmonically trapped non-degenerate atomic gas tha

J. Aichelin, K. Werner

In ultrarelativistic heavy ion collisions, the multiplicity of multi-strange baryons per participating nucleon increases with centrality in a different fashion for different systems and energies. At RHIC, for copper+copper (CuCu) collisions the increase is much steeper than for gold-gold (AuAu) collisions. We show that this system size dependence is due to a

Pierre Collet, Jean-Pierre Eckmann, Carlos Mejia-Monasterio

We study heat transport in a one-dimensional chain of a finite number $N$ of identical cells, coupled at its boundaries to stochastic particle reservoirs. At the center of each cell, tracer particles collide with fixed scatterers, exchanging momentum. In a recent paper, \cite{CE08}, a spatially continuous version of this model was derived in a scaling regime

Volodymyr Derzhko, Janusz Jedrzejewski, Taras Krokhmalskii

We discuss striped phases as a state of matter intermediate between two extreme states: a crystalline state and a segregated state. We argue that this state is very sensitive to weak interactions, compared to those stabilizing a crystalline state, and to anisotropies. Moreover, under suitable conditions a 2D system in a striped phase decouples into (quasi) 1

Naoto Tanji

Pair creation in a uniform classical electromagnetic field (Schwinger mechanism) is studied focusing on the time evolution of the distribution of created particles. The time evolution of the distribution in time-dependent fields is also presented as well as effects of back reaction. Motivated by the Glasma flux tube, which may be formed at the initial stage

S. Nijdam, C. G. C. Geurts, E. M. van Veldhuizen, U. Ebert

Pictures show that streamer or sprite discharge channels emerging from the same electrode sometimes seem to reconnect or merge though their heads carry electric charge of the same polarity; one might therefore suspect that reconnections are an artifact of the two-dimensional projection in the pictures. Here we use stereo-photography to investigate the full t

Felipe J. Llanes-Estrada, Pedro Bicudo, Marco Cardoso, Tim Van Cauteren

We report on the first calculation of excited baryons with a chirally symmetric Hamiltonian, modeled after Coulomb gauge QCD (or upgraded from the Cornell meson potential model to a field theory in all of Fock-space) showing the insensitivity to chiral symmetry breaking. As has recently been understood, this leads to doubling between two hadrons of equal spi