April 2009 arXiv papers

J. Daligault, S. Gupta

The thermal conductivity of a dense {\it multi-component} plasma is critical to the modeling of accreting neutron stars. To this end, we perform large-scale molecular dynamics simulations to calculate the static structure factor of the dense multi-component plasma in the neutron star crust from near the photosphere-ocean boundary to the vicinity of the neutr

J. C. Phillips

Optimally doped ceramic superconductors (cuprates, pnictides, ...) exhibit transition temperatures Tc much larger than strongly coupled metallic superconductors like Pb (Tc= 7.2K, Eg/kTc = 4.5), and exhibit many universal features that appear to contradict the BCS theory of superconductivity based on attractive electron-phonon pairing interactions. Here I ar

Barry John Walker

Matthew Ando produced power operations in the Lubin-Tate cohomology theories and was able to classify which complex orientations were compatible with these operations. The methods used by Ando, Hopkins and Rezk to classify orientations of topological modular forms can be applied to complex K-Theory. Using techniques from local analytic number theory, we cons

Chia-Fu Yu

The endomorphism ring End(A) of an abelian variety A is an order in a semi-simple algebra over Q. The co-index of End(A) is the index to a maximal order containing it. We show that for abelian varieties of fixed dimension over any algebraically closed field of characteristic p>0, the p-exponents of the co-indices of their endomorphism rings are bounded. We a

Jean-Paul Allouche, Jeff Shallit

Some of the algorithms for solving the Tower of Hanoi puzzle can be applied "with eyes closed" or "without memory". Here we survey the solution for the classical Tower of Hanoi that uses finite automata, as well as some variations on the original puzzle. In passing, we obtain a new result on morphisms generating the classical and the lazy Tower of Hanoi.

David Batchelor

The magnitude of the strong interaction is characterized by $α_s$, the coupling parameter in Quantum Chromodynamics (QCD), a parameter with an unexplained value in the Standard Model. In this paper, a candidate explanation for $α_s$ is derived from (1) the lifetime of quark-antiquark pairs in vacuum fluctuations given by the Uncertainty Principle, (2) the va

Masahito Hayashi, Damian Markham, Mio Murao, Masaki Owari

In this paper for a class of symmetric multiparty pure states we consider a conjecture related to the geometric measure of entanglement: 'for a symmetric pure state, the closest product state in terms of the fidelity can be chosen as a symmetric product state'. We show that this conjecture is true for symmetric pure states whose amplitudes are all no

Tzu-Chieh Wei, Simone Severini

We point out that a geometric measure of quantum entanglement is related to the matrix permanent when restricted to permutation invariant states. This connection allows us to interpret the permanent as an angle between vectors. By employing a recently introduced permanent inequality by Carlen, Loss and Lieb, we can prove explicit formulas of the geometric me

Ralph V. Chamberlin, Josh V. Vermaas, George H. Wolf

The Boltzmann factor comes from the linear change in entropy of an infinite heat bath during a local fluctuation; small systems have significant nonlinear terms. We present theoretical arguments, experimental data, and Monte-Carlo simulations indicating that nonlinear terms may also occur when a particle interacts directly with a finite number of neighboring

Sebastian A. Reyes, Alexander Struck, Sebastian Eggert

We consider the effect of various defects and boundary structures on the low energy electronic properties in conducting zigzag and armchair carbon nanotubes. The tight binding model of the conduction bands is mapped exactly onto simple lattice models consisting of two uncoupled parallel chains. Imperfections such as impurities, structural defects or caps can

Dmytro Volin

We solve explicitly the crossing equation under sufficiently general assumptions on the structure of the dressing phase. We obtain the BES/BHL dressing phase as a minimal solution of the crossing equation and identify the possible CDD factors.

Edward Frenkel, Constantin Teleman, A. J. Tolland

We introduce a geometric completion of the stack of maps from stable marked curves to the quotient stack [point/GL(1)], and use it to construct some gauge-theoretic analogues of the Gromov-Witten invariants. We also indicate the generalization of these invariants to the quotient stacks [X/GL(1)], where X is a smooth proper complex algebraic variety.

Artur Piȩkosz

In this paper a systematic study of the category GTS of generalized topological spaces (in the sense of H. Delfs and M. Knebusch) and their strictly continuous mappings begins. Some completeness and cocompleteness results are achieved. Generalized topological spaces help to reconstruct the important elements of the theory of locally definable and weakly defi

Baruch Fischer, Moshe Zakai

We add here compared to our former arXiv version an explicit expression for the descendant ratio along the generations The equation that is added here appeared in the Hebrew version published in BDD, Bar Ilan University Press, 23, 71, 2010, titled The distribution route from ancestors to descendants in Equation 11. Otherwise, we don not change nor show here

Nicoletta Gnan, Thomas B. Schrøder, Ulf R. Pedersen, Nicholas P. Bailey

A liquid is termed strongly correlating if its virial and potential energy thermal equilibrium fluctuations in the NVT ensemble are more than 90% correlated [Phys. Rev. Lett. 100, 015701 (2008)]. The fluctuations of a strongly correlating liquid are well approximated by those of an inverse power-law intermolecular potential. Building on this fact we here def

Liana David

We prove that if the fundamental 4-form of an almost-quaternionic Hermitian manifold (M, Q, g) of dimension at least eight satisfies the conformal-Killing equation, then (M, Q, g) is quaternionic-Kahler.

Yuri I. Manin

In this paper I argue that infinities in the classical computation theory such as the unsolvability of the Halting Problem can be addressed in the same way as Feynman divergences in Quantum Field Theory, and that meaningful versions of renormalization in this context can be devised. Connections with quantum computation are also touched upon.

Y. -F. Jiang, L. Ciotti, J. P. Ostriker, A. Spitkovsky

Both radiative and mechanical feedback from Active Galactic Nuclei have been found to be important for the evolution of elliptical galaxies. We compute how a shock may be driven from a central black hole into the gaseous envelope of an elliptical galaxy by mechanical as well as radiative feedback (in the form of nuclear winds) using high resolution 1-D hydro

Shahab Joudaki, Asantha Cooray, Daniel E. Holz

We examine the influence of percent-level dark energy corrections to the nonlinear matter power spectrum on constraints of the dark energy equation of state from future weak lensing probes. We explicitly show that a poor approximation (off by > 10%) to the nonlinear corrections causes a > 1 sigma bias on the determination of the dark energy equation of state

Michela Petrini, Alberto Zaffaroni

We find explicit AdS4 solutions of massive type IIA with N=2 supersymmetry obtained deforming with a Roman mass the type IIA supersymmetric reduction of the M theory background AdS4 times M111. The family of solutions have SU(3) times SU(3) structure and isometry SU(3) times U(1)^2. They are conjectured to be dual to three-dimensional N=2 Chern-Simons theori

LIGO Scientific Collaboration, B. Abbott

We present an all-sky search for gravitational waves in the frequency range 1 to 6 kHz during the first calendar year of LIGO's fifth science run. This is the first untriggered LIGO burst analysis to be conducted above 3 kHz. We discuss the unique properties of interferometric data in this regime. 161.3 days of triple-coincident data were analyzed. No gravit

Kei-Ichi Kondo

We rewrite the Zwanziger horizon condition in terms of the Kugo-Ojima parameter for color confinement. This enables one to explain which value of the Kugo-Ojima parameter is allowed if the horizon condition is imposed. Although all the calculations are performed in the limit of vanishing Gribov parameter for simplicity, the obtained value is consistent with

Elchanan Mossel, Omer Tamuz

We consider n agents located on the vertices of a connected graph. Each agent v receives a signal X_v(0)~N(s, 1) where s is an unknown quantity. A natural iterative way of estimating s is to perform the following procedure. At iteration t + 1 let X_v(t + 1) be the average of X_v(t) and of X_w(t) among all the neighbors w of v. In this paper we consider a var

Tal Lev-Ami, Neil Immerman, Thomas Reps, Mooly Sagiv

This paper shows how to harness existing theorem provers for first-order logic to automatically verify safety properties of imperative programs that perform dynamic storage allocation and destructive updating of pointer-valued structure fields. One of the main obstacles is specifying and proving the (absence) of reachability properties among dynamically allo

J. Michael Shull, Jennifer R. Jones, Charles W. Danforth, Joseph A. Collins

The low Galactic halo is enveloped by a sheath of ionized, low-metallicity gas, which can provide a substantial (1 M_sun/yr) cooling inflow to replenish star formation in the disk. Using absorption spectra from the HST and FUSE toward 37 active galactic nuclei at high latitude, we detect widespread interstellar SiIII 1206.5 absorption: 61 high-velocity cloud

Tamara Broderick, Robert B. Gramacy

Recognizing the successes of treed Gaussian process (TGP) models as an interpretable and thrifty model for nonparametric regression, we seek to extend the model to classification. Both treed models and Gaussian processes (GPs) have, separately, enjoyed great success in application to classification problems. An example of the former is Bayesian CART. In the

Damien Calaque, Carlo A. Rossi, Michel Van den Bergh

In this paper we complete the proof of Caldararu's conjecture on the compatibility between the module structures on differential forms over poly-vector fields and on Hochschild homology over Hochschild cohomology. In fact we show that twisting with the square root of the Todd class gives an isomorphism of precalculi between these pairs of objects. Our me

Martin Erdmann, Peter Schiffer

We present a method to measure cosmic magnetic fields with ultra high energy cosmic rays (UHECRs). We apply an advanced autocorrelation method to simulated UHECRs which includes their directional as well as energy information. Without explicit knowledge of the UHECR sources, such measurements are sensitive to the number of sources and to the magnetic field s

Yael Fregier, Aron Gohr

In hom-associative structures, the associativity condition $(xy)z=x(yz)$ is twisted to $α(x)(yz) = (xy)α(z)$, with $α$ a map in the appropriate category. In the present paper, we consider two different unitality conditions for hom-associative algebras. The first one, existence of a unit in the classical sense, is stronger than the second one, which we call w

Ben A. Ayliffe, Matthew R. Bate

We investigate the properties of circumplanetary discs formed in three-dimensional, self-gravitating radiation hydrodynamical models of gas accretion by protoplanets. We determine disc sizes, scaleheights, and density and temperature profiles for different protoplanet masses, in solar nebulae of differing grain opacities. We find that the analytical predicti

Junichi Aoi, Kohta Murase, Keitaro Takahashi, Kunihito Ioka

We revisit the high-energy spectral cutoff originating from the electron-positron pair creation in the prompt phase of gamma-ray bursts (GRBs) with numerical and analytical calculations. We show that the conventional exponential and/or broken power law cutoff should be drastically modified to a shallower broken power-law in practical observations that integr

Giulio Magli

The Inca citadel of Machu Picchu is usually interpreted as a "royal estate" of the Inca ruler Pachacuti. This idea is challenged here by a critical reappraisal of existing sources and a re-analysis of existing evidences. It is shown that such evidences actually point at a quite different interpretation. This interpretation is suggested, on one side,

Nina J Lorenz, Hans Joachim Schoepe, Holger Reiber, Thomas Palberg

We review recent work on the phase behaviour of binary charged sphere mixtures as a function of particle concentration and composition. Both size ratios and charge ratios are varied over a wide range. By contrast to hard spheres the long ranged Coulomb interaction stabilizes the crystal phase at low particle concentrations and shifts the occurrence of amorph

G. C. Giecold

The Herzog and Son prescription for computing real-time Green functions for finite temperature gauge theories from their gravity dual is generalized to fermions. These notes explain how such an extension involves properties of spinors in a curved, complexified space-time.

Lee Lindblom, Bela Szilagyi

A new gauge driver is introduced for the generalized harmonic (GH) representation of Einstein's equation. This new driver allows a rather general class of gauge conditions to be implemented in a way that maintains the hyperbolicity of the combined evolution system. This driver is more stable and effective, and unlike previous drivers, allows stable evolu

Ron Doney, Mladen Savov

We call a right-continuous increasing process $K_x$ a partial right inverse (PRI) of a given Lévy process $X$ if $X_{K_x}=x$ for at least all $x$ in some random interval $[0,ζ)$ of positive length. In this paper, we give a necessary and sufficient condition for the existence of a PRI in terms of the Lévy triplet.

Anthony Leverrier, Nicolas J. Cerf

The quantum versions of de Finetti's theorem derived so far express the convergence of n-partite symmetric states, i.e., states that are invariant under permutations of their n parties, towards probabilistic mixtures of independent and identically distributed (i.i.d.) states. Unfortunately, these theorems only hold in finite-dimensional Hilbert spaces, a

Pierre Martinetti

We question the notion of line element in some quantum spaces that are expected to play a role in quantum gravity, namely non-commutative deformations of Minkowski spaces. We recall how the implementation of the Leibniz rule forbids to see some of the infinitesimal deformed Poincare transformations as good candidates for Noether symmetries. Then we recall th

Paul B. Slater

The central problem of concern to Serrano, Boguna and Vespignani ("Extracting the multiscale backbone of complex weighted networks", Proc Natl Acad Sci 106:6483-6488 [2009]) can be effectively and elegantly addressed using a well-established two-stage algorithm that has been applied to internal migration flows for numerous nations and several other f

Jonathon Peterson, Timo Seppäläinen

We study the current of particles that move independently in a common static random environment on the one-dimensional integer lattice. A two-level fluctuation picture appears. On the central limit scale the quenched mean of the current process converges to a Brownian motion. On a smaller scale the current process centered at its quenched mean converges to a

Fernando Pastawski, Alastair Kay, Norbert Schuch, Ignacio Cirac

We investigate the possibilities and limitations of passive Hamiltonian protection of a quantum memory against depolarizing noise. Without protection, the lifetime of a single qubit is independent of N, the number of qubits composing the memory. In the presence of a protecting Hamiltonian, the lifetime increases at most logarithmically with N. We construct a

Valentin Feray

In this paper, we look at the number of factorizations of a given permutation into star transpositions. In particular, we give a natural explanation of a hidden symmetry, answering a question of I.P. Goulden and D.M. Jackson. We also have a new proof of their explicit formula. Another result is the normalized class expansion of some central elements of the s

M. Bate, B. Martin, G. Roehrle, R. Tange

In this paper we consider various problems involving the action of a reductive group $G$ on an affine variety $V$. We prove some general rationality results about the $G$-orbits in $V$. In addition, we extend fundamental results of Kempf and Hesselink regarding optimal destabilizing parabolic subgroups of $G$ for such general $G$-actions. We apply our genera

Benjamin J. Owen

Due to their computational limitations, searches for continuous gravitational waves (GW) are significantly more sensitive when informed by observational photon astronomy and theoretical astrophysics. Indirect upper limits on GW emission inferred from photon astronomy indicate which objects are more interesting for GW searches, and also set sensitivity milest

Wei Song, Lin Chen, Shi-Liang Zhu

We introduce the concept of distillability sudden death, i.e., free entangled states can evolve into non-distillable (bound entangled or separable) states in finite time under local noise. We describe the phenomenon through a specific model of local dephasing noise and compare the behavior of states in terms of the Bures fidelity. Then we propose a few metho

Gargi Mitra-Delmotte, A. N. Mitra

The efficiency of bio-molecular motors stems from reversible interactions $\sim$ $k_B T$; weak bonds stabilizing intermediate states (enabling $direct$ conversion of chemical into mechanical energy). For their (unknown) origins, we suggest that a magnetically structured phase (MSP) formed via accretion of super-paramagnetic particles (S-PPs) by magnetic rock

A. B. Butenko, A. A. Leonov, U. K. Rößler, A. N. Bogdanov

In cubic noncentrosymmetric ferromagnets uniaxial distortions suppress the helical states and stabilize Skyrmion lattices in a broad range of thermodynamical parameters. Using a phenomenological theory for modulated and localized states in chiral magnets, the equilibrium parameters of the Skyrmion and helical states are derived as functions of the applied ma

Pascal Boehi, Max F. Riedel, Johannes Hoffrogge, Jakob Reichel

Entanglement-based technologies, such as quantum information processing, quantum simulations, and quantum-enhanced metrology, have the potential to revolutionise our way of computing and measuring and help clarifying the puzzling concept of entanglement itself. Ultracold atoms on atom chips are attractive for their implementation, as they provide control ove

N. Vianello, M. Spolaore, E. Martines, R. Cavazzana

Edge turbulent structures are commonly observed in fusion devices and are generally believed to be responsible for confinement degradation. Among their origin Drift-Alfven turbulence is one of the most commonly suggested. Drift-Alfven paradigm allows the existence of localized vortex-like structures observed also in various systems. Here we present the evide

L. F. Palhares, E. S. Fraga, T. Kodama

We investigate finite-size effects on the chiral phase diagram of strong interactions within the linear sigma model coupled to quarks. We estimate the modification of the pseudocritical transition line and isentropic trajectories for sizes that are representative of the systems created in relativistic heavy ion collision experiments. The corrections are clea

Martin Gaume

In this paper, we consider a class of two-particle tight-binding Hamiltonians, describing pairs of interacting quantum particles on the lattice $\Z^d$, $d\ge 1$ subject to a common external potential $V(x)$ which we assume quasi-periodic and depending on an auxiliary parameter. Such parametric families of ergodic deterministic potentials ("grand ensemble

B. Holdom, W. S. Hou, T. Hurth, M. L. Mangano

This summary of the Workshop "Beyond the 3-generation SM in the LHC era" presents a brief discussion of the following four statements about the fourth generation: 1) It is not excluded by EW precision data; 2) It addresses some of the currently open questions; 3) It can accommodate emerging possible hints of new physics; 4) LHC has the potential to discover

F. Massel, M. J. Leskinen, P. Torma

We consider a strongly repulsive two-component Fermi gas in a one-dimensional (1D) optical lattice described in terms of a Hubbard Hamiltonian. We analyze the response of the system to a periodic modulation of the hopping amplitude in presence of large two body interaction. By (essentially) exact simulations of the time evolution, we find a non-trivial doubl

Claudia V. Rodrigues, Marilia J. Sartori, Jane Gregorio-Hetem, A. Mario Magalhaes

We present a study of the correlation between the direction of the symmetry axis of the circumstellar material around intermediate mass young stellar objects and that of the interstellar magnetic field. We use CCD polarimetric data on 100 Herbig Ae/Be stars. A large number of them shows intrinsic polarization, which indicates that their circumstellar envelop

L. Campanelli, M. Ruggieri

We construct nontopological solitonic solutions in (3+1)-dimensional Minkowski spacetime carrying a conserved global U(1) charge and nonvanishing angular momentum in a supersymmetric extension of the standard model with low-energy, gauge-mediated symmetry breaking.

Birger Horstmann, Benni Reznik, Serena Fagnocchi, J. Ignacio Cirac

In this article we propose to simulate acoustic black holes with ions in rings. If the ions are rotating with a stationary and inhomogeneous velocity profile, regions can appear where the ion velocity exceeds the group velocity of the phonons. In these regions phonons are trapped like light in black holes, even though we have a discrete field theory and a no

Govind S. Krishnaswami

We try to use scale-invariance and the large-N limit to find a non-trivial 4d O(N) scalar field model with controlled UV behavior and naturally light scalar excitations. The principle is to fix interactions by requiring the effective action for space-time dependent background fields to be finite and scale-invariant when regulators are removed. We find a line

Adrian Nachman, Brian Street

We consider the problem of recovering the coefficient σ(x) of the elliptic equation \grad \cdot(σ\grad u)=0 in a body from measurements of the Cauchy data on possibly very small subsets of its surface. We give a constructive proof of a uniqueness result by Kenig, Sjöstrand, and Uhlmann. We construct a uniquely specified family of solutions such that their tr

M. V. Cheremisin

The response of an ungated two-dimensional electron gas(2DEG) to an external electromagnetic excitation is analyzed. The possibility of creating a single-mode resonance detector operating in the terahertz frequency range is demonstrated.

Christian Gutschwager

The Littlewood-Richardson (LR) coefficient counts among many other things the LR tableaux of a given shape and a given content. We prove, that the number of LR tableaux weakly increases if one adds to the shape and the content the shape and the content of another LR tableau. We also investigate the behaviour of the number of LR tableaux, if one repeatedly ad

Remi Gribonval, Karin Schnass

This article treats the problem of learning a dictionary providing sparse representations for a given signal class, via $\ell_1$-minimisation. The problem can also be seen as factorising a $\ddim \times \nsig$ matrix $Y=(y_1 >... y_\nsig), y_n\in \R^\ddim$ of training signals into a $\ddim \times \natoms$ dictionary matrix $\dico$ and a $\natoms \times \nsig

Gilad Lifschytz, Matthew Lippert

We compute the longitudinal and Hall conductivities in the parallel phase of the Sakai-Sugimoto model with a transverse magnetic field. We find that the conductivities behave as if the charge of the system is made out of two different types; one behaves as charge carriers flowing through a dissipative neutral medium, while the other does not feel the dissipa

E. M. Shahverdiev, K. A. Shore

By studying the autocorrelation function of the optoelectronic feedback semiconductor laser output we establish that the signatures of time delays can be erased in systems incorporating modulated feedback time delays. This property is of importance for the suitability of such laser systems for secure chaos-based communication systems. We also make the first

D. Cunnama, A. Faltenbacher, C. Cress, S. Passmoor

We use the Millennium simulation to probe the correlation between cluster velocities and their shapes and the consequences for measurements of the kinetic Sunyaev-Zeldovich (kSZ) effect. Halos are generally prolate ellipsoids with orientations that are correlated with those of nearby halos. We measure the mean streaming velocities of halos along the lines th

Baldo Sahlmueller

Direct photons are a powerful probe to study the properties of the unique matter created in ultrarelativistic heavy-ion collisions. They carry information on the various stages of a heavy-ion collision. At different transverse momenta (pT), different production processes dominate the direct photon yield in heavy-ion collisions. Photons at high pT can be used

Yuichiro Hida, Hiromichi Nakazato, Kazuya Yuasa, Yasser Omar

A qubit (a spin-1/2 particle) prepared in the up state is scattered by local spin-flipping potentials produced by the two target qubits (two fixed spins), both prepared in the down state, to generate an entangled state in the latter when the former is found in the down state after scattering. The scattering process is analyzed in three dimensions, both to lo

A. Laucht, N. Hauke, J. M. Villas-Bôas, F. Hofbauer

We experimentally and theoretically investigate dephasing of zero dimensional microcavity polaritons in electrically tunable single dot photonic crystal nanocavities. Such devices allow us to alter the dot-cavity detuning in-situ and to directly probe the influence on the emission spectrum of varying the incoherent excitation level and the lattice temperatur

Daniel G Cocks, Ian B Whittingham

Photoassociation of spin-polarized metastable helium to the three lowest rovibrational levels of the J=1, $0_u^+$ state asymptoting to 2$s {}^{3}$S$_{1}+2p {}^{3}$P$_{0}$ is studied using a second-order perturbative treatment of the line shifts valid for low laser intensities, and two variants of a non-perturbative close-coupled treatment, one based upon dre

Oana Ivanovici, Fabrice Planchon

We prove that the quintic Schrodinger equation with Dirichlet boundary conditions is locally well posed for H^{1}_{0} data on any smooth, non-trapping domain of R^3. The key ingredient is a smoothing effect in L^{5}_{x}L^{2}_{t} for the linear equation. We also derive scattering results for the whole range of defocusing sub-quintic Schrodinger equations outs

Frédéric Déglise

The proof of the coincidence of the Gysin morphism in motivic cohomology and the usual pushout on Chow groups has been improved (see Lemma 3.3 and Proposition 3.11)

Hajer Bahouri, Clotilde Fermanian-Kammerer, Isabelle Gallagher

This paper has been withdrawn by the authors. A class of pseudodifferential operators on the Heisenberg group is defined. As it should be, this class is an algebra containing the class of differential operators. Furthermore, those pseudodifferential operators act continuously on Sobolev spaces and the loss of derivatives may be controled by the order of the

Heath Emerson

We survey work by the author and Ralf Meyer on equivariant KK-theory. Duality plays a key role in our approach. We organize the survey around the objective of computing a certain homotopy-invariant of a space equipped with a proper action of a group or groupoid called the Lefschetz map. The Lefschetz map associates an equivariant K-homology class to an equiv

R. Akiyoshi, G. Mints

$Ω$-rule was introduced by W. Buchholz to give an ordinal-free cut-elimination proof for a subsystem of analysis with $Π^{1}_{1}$-comprehension. His proof provides cut-free derivations by familiar rules only for arithmetical sequents. When second-order quantifiers are present, they are introduced by $Ω$-rule and some residual cuts are not eliminated. Using a

Bing Dong, H. Y. Fan, X. L. Lei, N. J. M. Horing

We analyze the effects of a distortion of the nuclear potential of a molecular quantum dot (QD), as well as a shift of its equilibrium position, on nonequilibrium-vibration-assisted tunneling through the QD with a single level ($ε_d$) coupled to the vibrational mode. For this purpose, we derive an explicit analytical expression for the Franck-Condon (FC) fac

Niels Kowalzig, Hessel Posthuma

We give a systematic description of the cyclic cohomology theory of Hopf algebroids in terms of its associated category of modules. Then we introduce a dual cyclic homology theory by applying cyclic duality to the underlying cocyclic object. We derive general structure theorems for these theories in the special cases of commutative and cocommutative Hopf alg

Yong Li, Peng Zhang, Z. D. Wang

We consider a trapped two-component atomic Bose-Einstein condensate (BEC), where each atom with three energy-levels is coupled to an optical cavity field and an external classical optical field as well as a microwave field to form the so-called $Δ$-type configuration. After adiabatically eliminating the atomic excited state, an extended JC-Dicke model is der

Assaf Naor, Yuval Peres

We show that if $H$ is a group of polynomial growth whose growth rate is at least quadratic then the $L_p$ compression of the wreath product $\Z\bwr H$ equals $\max{\frac{1}{p},{1/2}}$. We also show that the $L_p$ compression of $\Z\bwr \Z$ equals $\max{\frac{p}{2p-1},\frac23}$ and the $L_p$ compression of $(\Z\bwr\Z)_0$ (the zero section of $\Z\bwr \Z$, equ

Caroline Foster, Lorne A. Nelson

We present a detailed description of our void finding algorithm which is an extension of the prescription by Hoyle and Vogeley (2002). We include a discussion of the reproducibility and robustness of the algorithm as well as the statistical significance of the detected voids. We apply our void finder to the Data Release 5 (DR5) of the Sloan Digital Sky Surve

Kim Griest, Jonathan B. Whitmore, Arthur M. Wolfe, J. Xavier Prochaska

We report on an attempt to accurately wavelength calibrate four nights of data taken with the Keck HIRES spectrograph on QSO PHL957, for the purpose of determining whether the fine structure constant was different in the past. Using new software and techniques, we measured the redshifts of various Ni II, Fe II, Si II, etc. lines in a damped Ly-alpha system a

The BABAR Collaboration, B. Aubert

We present a measurement of the B0 --> Lambda-bar p pi- branching fraction performed using the BaBar detector at the PEP-II asymmetric e+e- collider. Based on a sample of 467 million BB-bar pairs we measure B(B0 --> Lambda-bar p pi-) = [3.07 pm 0.31 (stat.) pm 0.23 (syst.)] x 10^{-6}. The measured differential spectrum as a function of the dibaryon invariant

Vlada Limic, Stanislav Volkov

By a theorem of Volkov (2001) we know that on most graphs with positive probability the linearly vertex-reinforced random walk (VRRW) stays within a finite "trapping" subgraph at all large times. The question of whether this tail behavior occurs with probability one is open in general. In his thesis, Pemantle (1988) proved, via a dynamical system app

Andrey V. Solov'yov, Roman G. Polozkov, Vadim K. Ivanov

Angular resolved photoelectron spectra of metal clusters have been experimentally measured for the first time only recently. These measurements have been performed systematically for sodium clusters in a broad range of cluster sizes. This work attracted a lot of attention and was reported practically at all major international cluster conferences because it

LAT Collaboration

Designed as a high-sensitivity gamma-ray observatory, the Fermi Large Area Telescope is also an electron detector with a large acceptance exceeding 2m^2 sr at 300 GeV. Building on the gamma-ray analysis, we have developed an efficient electron detection strategy which provides sufficient background rejection for measurement of the steeply-falling electron sp

Gan Xiaoying, Shan Da, Zhou Yuan, Zhang Wei

In cognitive radio systems, cyclostationary feature detection plays an important role in spectrum sensing, especially in low SNR cases. To configure the detection threshold under a certain noise level and a pre-set miss detection probability Pf, it's important to derive the theoretical distribution of the observation variable. In this paper, noise distri

Lizette Guzman, Laurent Loinard, Yolanda Gomez, Christophe Morisset

In this paper, we present radio continuum observations of the planetary nebula IC 418 obtained at two epochs separated by more than 20 years. These data allow us to show that the angular expansion rate of the ionization front in IC 418 is 5.8 $\pm$ 1.5 mas yr$^{-1}$. If the expansion velocity of the ionization front is equal to the expansion velocity of the

Stephan Lany, Alex Zunger

Acceptor-bound holes in oxides often localize asymmetrically at one out of several equivalent oxygen ligands. Whereas Hartree-Fock (HF) theory overly favors such symmetry-broken polaronic hole-localization in oxides, standard local density (LD) calculations suffer from spurious delocalization among several oxygen sites. These opposite biases originate from t

David Rideout, Petros Wallden

There are numerous indications that a discrete substratum underlies continuum spacetime. Any fundamentally discrete approach to quantum gravity must provide some prescription for how continuum properties emerge from the underlying discreteness. The causal set approach, in which the fundamental relation is based upon causality, finds it easy to reproduce time

Vinod K. Sangwan, Vincent W. Ballarotto, Karen Siegrist, Ellen D. Williams

A non-destructive technique for obtaining voltage contrast information with photoelectron emission microscopy (PEEM) is described. Samples consisting of electrically isolated metal lines were used to quantify voltage contrast in PEEM. The voltage contrast behavior is characterized by comparing measured voltage contrast with calculated voltage contrast from t

Piotr Kolenderski, Wojciech Wasilewski, Konrad Banaszek

We address the problem of efficient modelling of photon pairs generated in spontaneous parametric down-conversion and coupled into single-mode fibers. It is shown that when the range of relevant transverse wave vectors is restricted by the pump and fiber modes, the computational complexity can be reduced substantially with the help of the paraxial approximat

Andrew H. Norton

To date, classical mass renormalization has been invoked in all tube-based self-force calculations, thus following the method introduced in Dirac's 1938 calculation of the electromagnetic self-force for the classical radiating electron. In this paper a new tube method is described that does not rely on a mass renormalization procedure. As a result, exact

LIGO Scientific Collaboration

We present the results of a LIGO search for short-duration gravitational waves (GWs) associated with the 2006 March 29 SGR 1900+14 storm. A new search method is used, "stacking'' the GW data around the times of individual soft-gamma bursts in the storm to enhance sensitivity for models in which multiple bursts are accompanied by GW emission. We a

S. Galli, F. Iocco, G. Bertone, A. Melchiorri

The injection of secondary particles produced by Dark Matter (DM) annihilation around redshift 1000 would inevitably affect the process of recombination, leaving an imprint on Cosmic Microwave Background (CMB) anisotropies and polarization. We show that the most recent CMB measurements provided by the WMAP satellite mission place interesting constraints on D

J. Christopher Howk

There is now ample evidence that the interstellar thick disks of spiral galaxies are dusty. Although the majority of extraplanar gas in the first few kiloparsecs above the plane of a spiral galaxy is matter that has been expelled from the thin disk, the feedback-driven expulsion does not destroy dust grains altogether (and there is not yet any good measure s

Yoshiyasu Ishigami

The well-known regularity lemma of E. Szemerédi for graphs (i.e. 2-uniform hypergraphs) claims that for any graph there exists a vertex partition with the property of quasi-randomness. We give a simple construction of such a partition. It is done just by taking a constant-bounded number of random vertex samplings only one time (thus, iteration-free). Since i

Athanasios S. Lioumpas, George K. Karagiannidis

Channel estimation at the receiver side is essential to adaptive modulation schemes, prohibiting low complexity systems from using variable rate and/or variable power transmissions. Towards providing a solution to this problem, we introduce a variable-rate (VR) M-PSK modulation scheme, for communications over fading channels, in the absence of channel gain e

P. A. Pinilla, J. R. Luthra

Based on the geometry of entangled three and two qubit states, we present the connection between the entanglement measure of the three-qubit state defined using the last Hopf fibration and the entanglement measures known as two- and three-tangle. Moreover, the generalization of the geometric representation of four qubit state and a potential entanglement mea

Anna Pósfai

In this note we give a proof for the result stated as Theorem 4 in Poisson Approximation in a Poisson Limit Theorem Inspired by Coupon Collecting.

Denis Feyel, Arnaud De La Pradelle

We study the fBm by use of convolution of the standard white noise with a certain distribution. This brings some simplifications and new results.

Piotr Kolenderski, Wojciech Wasilewski

We introduce an effective numerical method of density matrix determination of fiber coupled single photon generated in process of spontaneous parametric down conversion in type I non-collinear configuration. The presented theory has been successfully applied in case of source exploited in Phys. Rev. Lett. 99, 123601 (2007) to demonstrate the experimental cha

Kirill A. Kazakov

The problem of anomalously high levels of flicker noise observed in the normal state of the high-temperature superconductors is addressed. It is argued that the anomaly is the result of incorrect normalization of the power spectra according to the Hooge formula. A careful analysis of the available experimental data is given, which shows that the scaling of t