June 2007 arXiv papers — page 17

Petr Zavada

Covariant version of the quark-parton model is studied. Dependence of the structure functions and parton distributions on the 3D quark intrinsic motion is discussed. The important role of the quark orbital momentum, which is a particular case of intrinsic motion, appears as a direct consequence of the covariant description. Effect of orbital motion is substa

Marc Kamionkowski

This is a short review, aimed at a general audience, of several current subjects of research in cosmology. The topics discussed include the cosmic microwave background (CMB), with particular emphasis on its relevance for testing inflation; dark matter, with a brief review of astrophysical evidence and more emphasis on particle candidates; and cosmic accelera

Maria Tengner, Daniel Ljunggren

We make a thorough analysis of heralded single photon sources regarding how factors such as the detector gate-period, the photon rates, the fiber coupling efficiencies, and the system losses affect the performance of the source. In the course of this we give a detailed description of how to determine fiber coupling efficiencies from experimentally measurable

A. B. Arbuzov, E. S. Scherbakova

The effect of the collinear photon radiation by charged particles is considered in the second order of the perturbation theory. Double and single photon radiation is evaluated. The corresponding radiation factors are obtained. The QED renormalization group approach is exploited in the next-to-leading order. The results are suited to perform a systematic trea

Carlo Iazeolla, Ergin Sezgin, Per Sundell

We formulate four dimensional higher spin gauge theories in spacetimes with signature (4-p,p) and nonvanishing cosmological constant. Among them are chiral models in Euclidean (4,0) and Kleinian (2,2) signature involving half-flat gauge fields. Apart from the maximally symmetric solutions, including de Sitter spacetime, we find: (a) SO(4-p,p) invariant defor

Robert Harlander, Philipp Kant, Luminita Mihaila, Matthias Steinhauser

Recent developments in higher order calculations within the framework of Dimensional Reduction, the preferred regularization scheme for supersymmetric theories, are reported on. Special emphasis is put on the treatment of evanescent couplings, the equivalence to Dimensional Regularization, and the evaluation of $α_s(M_GUT)$ from $α_s(M_Z)$.

Masaki Tsukamoto

We study the mean dimension of the moduli space of Brody curves. We introduce the notion of "mean energy" and show that this can be used to estimate the mean dimension.

Allon M. Klein, David P. Doupe, Philip H. Jones, Benjamin D. Simons

The rules governing cell division and differentiation are central to understanding the mechanisms of development, aging and cancer. By utilising inducible genetic labelling, recent studies have shown that the clonal population in transgenic mouse epidermis can be tracked in vivo. Drawing on these results, we explain how clonal fate data may be used to infer

A. B. Orue, G. Alvarez, F. Montoya, C. Sanchez-Avila

This paper studies the security of a chaotic cryptosystem based on the Chua circuit and implemented with State Controlled Cellular Neural Networks. It is shown that the plaintext can be retrieved by ciphertext band-pass filtering after an imperfect decoding with wrong receiver parameters. It is also shown that the key space of the system can be notably reduc

A. Matzkin, M. Lombardi

We investigate symmetric oscillators, and in particular their quantization, by employing semiclassical and quantum phase functions introduced in the context of Liouville-Green transformations of the Schrödinger equation. For anharmonic oscillators, first order semiclassical quantization is seldom accurate and the higher order expansions eventually break down

Micheline Vigue-Poirrier

Let $X$ be a nilpotent space such that there exists $N\geq 1$ with $H^N(X,\mathbb Q) \ne 0$ and $H^n(X,\mathbb Q)=0$ if $n>N$. Let $Y$ be a m-connected space with $m\geq N+1$ and $H^*(Y,\mathbb Q)$ is finitely generated as algebra. We assume that the odd part of the rational Hurewicz homomorphism: $π_{odd}(X)\otimes \mathbb Q\to H_{odd}(X,\mathbb Q)$ is non-

L. J. Silvers, M. R. E. Proctor

A-type stars have a complex internal structure with the possibility of multiple convection zones. If not sufficiently separated, such zones will interact through the convectively stable regions that lie between them. It is therefore of interest to ask whether the typical conditions that exist within such stars are such that these convections zones can ever b

Hcene Benmohamed, Arnaud Leleve, Patrick Prévot

E-Laboratories are important components of e- learning environments, especially in scientific and technical disciplines. First widespread E-Labs consisted in proposing simulations of real systems (virtual labs), as building remote labs (remote control of real systems) was difficult by lack of industrial standards and common protocols. Nowadays, robotics and

Su-Chan Park, Hyunggyu Park

At non-equilibrium phase transitions into absorbing (trapped) states, it is well known that the directed percolation (DP) critical scaling is shared by two classes of models with a single (S) absorbing state and with infinitely many (IM) absorbing states. We study the crossover behavior in one dimension, arising from a considerable reduction of the number of

A. Kheifets, F. Peherstorfer, P. Yuditskii

Adamjan-Arov (Lax--Phillips) model space is considered as a scattering representation space for a CMV matrix in context of an extended Marchenko--Faddeev scattering theory. That is, there exists a basis in which the multiplication by independent variable is a CMV matrix. This basis as well as Verblunski coefficients are computed explicitly in terms of Nehari

Tonu Kipper, Valentina Klochkova

We analysed the high resolution spectra of a RU Cam, classified as W Vir type star. The atmospheric parameters of RU Cam were estimated Teff=5250K and log g=1.0. The hydrogen deficiency of RU Cam was not confirmed. The iron abundance, [Fe/H]=-0.37, is close to the solar one. Abundances of most other elements are also close to normal. We found considerable ex

Timo Hyart, Alexey V. Shorokhov, Kirill N. Alekseev

We consider a high-frequency response of electrons in a single miniband of superlattice subject to dc and ac electric fields. Action of ac electric field causes oscillations of electron's effective mass in miniband, which result in a parametric resonance. We have established a theoretical feasibility of phase-sensitive parametric amplification at the res

P. Muller, R. Kern

By introducing finite size surface and interfacial excess quantities, interactions between interfaces are shown to modify the usual surface premelting phenomenon. It is the case of surface melting of a thin solid film s deposited on a planar solid substrate S. More precisely to the usual wetting condition of the solid s by its own melt l, necessary for preme

Pablo Piantanida, Gerald Matz, Pierre Duhamel

Classically, communication systems are designed assuming perfect channel state information at the receiver and/or transmitter. However, in many practical situations, only an estimate of the channel is available that differs from the true channel. We address this channel mismatch scenario by using the notion of estimation-induced outage capacity, for which we

F. De Marchi, E. Poretti, M. Montalto, G. Piotto

Aims: This work presents a high--precision variability survey in the field of the old, super metal-rich open cluster NGC 6791. Methods: The data sample consists of more than 75,000 high-precision CCD time series measurements in the V band obtained mainly at the Canada-France-Hawaii Telescope, with additional data from S. Pedro Martir and Loiano observatories

Christian Muller, Patrik Johansson, Maths Karlsson, Philipp Maass

Raman spectra of thin solid electrolyte films obtained by sputtering a lithium sulfate target in nitrogen plasma are measured and compared to ab initio electronic structure calculations for clusters composed of 28 atoms. Agreement between measured and calculated spectra is obtained when oxygen atoms are replaced by nitrogen atoms and when the nitrogen atoms

D. V. Semikoz

Taking into account the Pierre Auger Observatory limits on the photon fraction among the highest energy cosmic rays, we show that the models based on the decay of super-heavy dark matter in the halo of our Galaxy are essentially excluded from being the sources of UHECRs unless their contribution becomes significant only above 100 EeV. Some top-down models ba

E. G. Koerding, S. Migliari, R. Fender, T. Belloni

Recently, it has been shown that soft-state black hole X-ray binaries and active galactic nuclei populate a plane in the space defined by the black hole mass, accretion rate and characteristic frequency. We show that this plane can be extended to hard-state objects if one allows a constant offset for the frequencies in the soft and the hard state. During a s

Akos G. Horvath

We discuss the concept of the shadow boundary of a centrally symmetric convex ball $K$ (actually being the unit ball of a Minkowski normed space) with respect to a direction ${\bf x}$ of the Euclidean n-space $R^n$. We introduce the concept of general parameter spheres of $K$ corresponding to this direction and prove that the shadow boundary is a topological

Irene Garcia-Selfa, Jose M. Tornero

A new characterization of rational torsion subgroups of elliptic curves is found, for points of order greater than 4, through the existence of solution for systems of Thue equations.

C. Sudheesh, S. Lakshmibala, V. Balakrishnan

Using a model Hamiltonian for a single-mode electromagnetic field interacting with a nonlinear medium, we show that quantum expectation values of subsystem observables can exhibit remarkably diverse ergodic properties even when the dynamics of the total system is regular. The time series of the mean photon number is studied over a range of values of the rati

N. Eren, N. Buyukcizmeci, R. Ogul

By a proper choice of the excitation energy per nucleon we analyze the mass distributions of the nuclear fragmentation at various excitation energies. Starting from low energies (between 0.1 and 1 MeV/nucleon) up to higher energies about 12 MeV/n, we classified the mass yield characteristics for heavy nuclei (A>200) on the basis of Statistical Multifragmenta

F. Aguilera-Granja, J. Ferrer, A. Vega

We present a thorough theoretical assessment of the stability of non-collinear spin arrangements in small palladium clusters. We generally find that ferromagnetic order is always preferred, but that antiferromagnetic and non-collinear configurations of different sorts exist and compete for the first excited isomers. We also show that the ground state is inse

Riccardo Scarpa, Renato Falomo, Eric Lerner

The optical properties of a number of supercompact ultraviolet luminous galaxies (UVLG), recently discovered in the local Universe matching GALEX and Sloan Digital Sky Survey (SDSS) data, are discussed. Detailed re-analysis of the SDSS data for these and other similar but nearer galaxies shows that their surface brightness radial profile in both R and u band

Elias P. Gyftopoulos

In a report published in Science, Scully et al propose to generate "phaseonium", and "extract work from a single heat bath via vanishing coherence" [1]. On the basis of the laws of physics, such a proposal is futile for at least two reasons.

A. F. Lanza, C. De Martino, M. Rodono'

Using a simple model based on the characteristics of sunspots and faculae in solar active regions, the effects of surface brightness inhomogeneities on the position of the photocentre of the disk of a solar-like, magnetically active star, are studied. A general law is introduced, giving the maximum amplitude of the photocentre excursion produced by a distrib

Hai Fu, Alan Stockton

We present a correlation between the presence of luminous extended emission-line regions (EELRs) and the metallicity of the broad-line regions (BLRs) of low-redshift quasars. The result is based on ground-based [O III] 5007 narrow-band imaging and Hubble Space Telescope UV spectra of 12 quasars at 0.20 < z < 0.45. Quasars showing luminous EELRs have low-meta

F. -P. Schilling

The Large Hadron Collider is an ideal place for precision measurements of the properties of the electroweak gauge bosons W^\pm, Z^0, as well as of the top quark. In this article, a few highlights of the prospects for performing such measurements with the CMS detector are summarized, with an emphasis on the first few 1/fb of data.

Moez Khenissi, Georgi Vodev

We obtain free of resonances regions for the elasticity system in the exterior of a strictly convex body with dissipative boundary conditions under some natural assumptions on the behaviour of the geodesics on the boundary.

B. Voss, D. Koester, R. Napiwotzki, N. Christlieb

We present a detailed spectroscopic analysis of the stars with helium-dominated spectra in the ESO Supernova Ia Progenitor Survey (SPY). Atmospheric parameters, masses, and abundances of trace hydrogen are determined and discussed in the context of spectral evolution of white dwarfs. Our final sample contains 71 objects, of which 6 are new detections and 14

Claire P. Massen, Jonathan P. K. Doye

It has previously been shown that the network of connected minima on a potential energy landscape is scale-free, and that this reflects a power-law distribution for the areas of the basins of attraction surrounding the minima. Here, we set out to understand more about the physical origins of these puzzling properties by examining how the potential energy lan

Andre Mischke

We report on recent heavy flavor measurements from the STAR experiment at RHIC. The measured charm cross section in heavy-ion collisions scales with the number of binary collisions, which is an indication for exclusive charm production in the initial state of the collision. The observed strong suppression of non-photonic electrons at high $\pt$ in Au+Au coll

A. López-Ortega

By using the sixth order WKB approximation we calculate for an electromagnetic field propagating in D-dimensional Schwarzschild and Schwarzschild de Sitter black holes its quasinormal frequencies for the fundamental mode and first overtones. We study the dependence of these QN frequencies on the value of the cosmological constant and the spacetime dimension.

Yu. Kondratiev, E. Pechersky, S. Pirogov

We study a Markov random process describing a muscle molecular motor behavior. Every motor is either bound up with a thin filament or unbound. In the bound state the motor creates a force proportional to its displacement from the neutral position. In both states the motor spend an exponential time depending on the state. The thin filament moves at its veloci

Hirohito Aizawa, Kazuhiko Kuroki, Yukio Tanaka

We study the effect of the magnetic field (Zeeman splitting) on the triplet pairing. We show generally that the enhancement of spin triplet pairing mediated by coexisting $2k_F$ spin and $2k_F$ charge fluctuations can be much larger than in the case of triplet pairing mediated by ferromagnetic spin fluctuations. We propose that this may be related to the rec

A. Duncan, M. Niedermaier, P. Weisz

Noncompact SO(1,N) sigma-models are studied in terms of their large N expansion in a lattice formulation in dimensions d \geq 2. Explicit results for the spin and current two-point functions as well as for the Binder cumulant are presented to next to leading order on a finite lattice. The dynamically generated gap is negative and serves as a coupling-depende

M. Chertkov, I. Kolokolov, V. Lebedev

Passive scalar turbulence forced steadily is characterized by the velocity correlation scale, $L$, injection scale, $l$, and diffusive scale, $r_d$. The scales are well separated if the diffusivity is small, $r_d\ll l,L$, and one normally says that effects of diffusion are confined to smaller scales, $r\ll r_d$. However, if the velocity is single scale one f

J. H. OH, D. Ahn, Y. S. Yu, S. W. Hwang

We investigate transport properties of gate-all-around Si nanowires using non-equilibrium Green&#39;s function technique. By taking into account of the ionized impurity scattering we calculate Green&#39;s functions self-consistently and examine the effects of ionized impurity scattering on electron densities and currents. For nano-scale Si wires, it is found

Michael Chertkov

We discuss how the loop calculus approach of [Chertkov, Chernyak &#39;06], enhanced by the pseudo-codeword search algorithm of [Chertkov, Stepanov &#39;06] and the facet-guessing idea from [Dimakis, Wainwright &#39;06], improves decoding of graph based codes in the error-floor domain. The utility of the new, Linear Programming based, decoding is demonstrated

Christian Flindt, Alessandro Braggio, Tomas Novotny

We consider the theoretical description of real-time counting of electrons tunneling through a Coulomb-blockade quantum dot using a detector with finite bandwidth. By tracing out the quantum dot we find that the dynamics of the detector effectively is non-Markovian. We calculate the cumulant generating function corresponding to the resulting non-Markovian ra

Tomoteru Fukumura, Hidemi Toyosaki, Kazunori Ueno, Masaki Nakano

A scaling relation of the anomalous Hall effect recently found in a ferromagnetic semiconductor (Ti,Co)O_2_ is compared with those of various ferromagnetic semiconductors and metals. Many of these compounds with relatively low conductivity sigma_xx_ < 10^4 ohm^-1 cm^-1 are also found to exhibit similar relation: anomalous Hall conductivity sigma_AH_ approxim

Ross Street, Elango Panchadcharam

We develop and extend the theory of Mackey functors as an application of enriched category theory. We define Mackey functors on a lextensive category $\E$ and investigate the properties of the category of Mackey functors on $\E$. We show that it is a monoidal category and the monoids are Green functors. Mackey functors are seen as providing a setting in whic

Martyn Gigg, Peter Richardson

We describe the recent development of the Herwig++ event generator.

Angelo F. Neto, Liang Gao, Philip Bett, Shaun Cole

We use the Millennium Simulation (MS) to study the statistics of LCDM halo concentrations at z = 0. Our results confirm that the average halo concentration declines monotonically with mass; a power-law fits well the concentration-mass relation for over 3 decades in mass, up to the most massive objects to form in a LCDM universe (~ 10^15 h^-1 Msol). This is i

Richard Ehrenborg, Stephanie van Willigenburg

We define a class of bipartite graphs that correspond naturally with Ferrers diagrams. We give expressions for the number of spanning trees, the number of Hamiltonian paths when applicable, the chromatic polynomial, and the chromatic symmetric function. We show that the linear coefficient of the chromatic polynomial is given by the excedance set statistic.

N. M. Ercolani, S. C. Venkataramani

We derive a rigorous scaling law for minimizers in a natural version of the regularized Cross-Newell model for pattern formation far from threshold. These energy-minimizing solutions support defects having the same character as what is seen in experimental studies of the corresponding physical systems and in numerical simulations of the microscopic equations

Irinel Caprini, Jan Fischer

Recently, P. M. Brooks and C.J. Maxwell [Phys. Rev. D{\bf 74} 065012 (2006)] claimed that the Landau pole of the one-loop coupling at $Q^2=Λ^2$ is absent from the leading one-chain term in a skeleton expansion of the Euclidean Adler ${\cal D}$ function. Moreover, in this approximation one has continuity along the Euclidean axis and a smooth infrared freezing

S. M. Huang, T. C. Lee, H. Akimoto, K. Kono

We report the observation of strong electron dephasing in a series of disordered Cu$_{93}$Ge$_4$Au$_3$ thin films. A very short electron dephasing time possessing very weak temperature dependence around 6 K, followed by an upturn with further decrease in temperature below 4 K, is found. The upturn is progressively more pronounced in more disordered samples.

Satoshi Aoki, Masami Miyakawa

Suppose several two-valued input-output systems are designed by setting the levels of several controllable factors. For this situation, Taguchi method has proposed to assign the controllable factors to the orthogonal array and use ANOVA model for the standardized SN ratio, which is a natural measure for evaluating the performance of each input-output system.

Takayuki Myo, Kiyoshi Kato, Hiroshi Toki, Kiyomi Ikeda

We study the roles of the tensor and pairing correlations on the halo formation in 11Li with an extended 9Li+n+n model. We first solve the ground state of 9Li in the shell model basis by taking 2p-2h states using the Gaussian functions with variational size parameters to take into account the tensor correlation fully. In 11Li, the tensor and pairing correlat

Stephanie van Willigenburg

We establish simple combinatorial descriptions of the radical and irreducible representations specifically for the descent algebra of a Coxeter group of type $D$ over any field.

M. D. Atkinson, G. Pfeiffer, S. J. van Willigenburg

The concept of descent algebras over a field of characteristic zero is extended to define descent algebras over a field of prime characteristic. Some basic algebraic structure of the latter, including its radical and irreducible modules, is then determined. The decomposition matrix of the descent algebras of Coxeter group types $A$, $B$, and $D$ are calculat

Jason Tumlinson

The characteristic mass of stars at early times may have been higher than today owing to the cosmic microwave background (CMB). This study proposes that (1) the testable predictions of this &#34;CMB-IMF&#34; hypothesis are an increase in the fraction of carbon-enhanced metal-poor (CEMP) stars with declining metallicity and an increase from younger to older p

Zhisheng Duan, Jinzhi Wang, Guanrong Chen, Lin Huang

This paper addresses the energy accumulation problem, in terms of the $H_2$ norm, of linearly coupled dynamical networks. An interesting outer-coupling relationship is constructed, under which the $H_2$ norm of the newly constructed network with column-input and row-output shaped matrices increases exponentially fast with the node number $N$: it increases ge

Zhisheng Duan, Guanrong Chen, Lin Huang

In this paper, the investigation is first motivated by showing two examples of simple regular symmetrical graphs, which have the same structural parameters, such as average distance, degree distribution and node betweenness centrality, but have very different synchronizabilities. This demonstrates the complexity of the network synchronizability problem. For

David A. Boboltz, Kevin B. Marvel

We present Very Long Baseline Array observations of the kinematics of the water masers associated with OH 12.8-0.9, the fourth member of the so-called &#34;water fountain&#34; class of sources. We find that the masers occupy two distinct regions at the ends of a bipolar jet-like structure oriented north-south, with the blue-shifted masers located to the nort

Zhisheng Duan, Guanrong Chen, Lin Huang

This paper addresses the synchronized region problem, which is reduced to a matrix stability problem, for complex dynamical networks. For any natural number $n$, the existence of a network which has $n$ disconnected synchronized regions is theoretically demonstrated. This shows the complexity in network synchronization. Convexity characteristic of stability

Georg H. Hoffstaetter, Christian Spethmann

Here we compute the ion distribution produced by an electron beam when ion-clearing electrodes are installed. This ion density is established as an equilibrium between gas ionization and ion clearing. The transverse ion distributions are shown to strongly peak in the beam&#39;s center, producing very nonlinear forces on the electron beam. We will analyze per

Santabrata Das, Sandip K. Chakrabarti

We solve the magnetohydrodynamic (MHD) equations governing axisymmetric flows around neutron stars and black holes and found all possible solution topologies for adiabatic accretion. We divide the parameter space spanned by the conserved energy and angular momentum of the flow in terms of the flow topologies. We also study the possibility of the formation of

Panagiotis Stinis

We present a collection of algorithms which utilize dimensional reduction to perform mesh refinement and study possibly singular solutions of time-dependent partial differential equations. The algorithms are inspired by constructions used in statistical mechanics to evaluate the properties of a system near a critical point. The first algorithm allows the acc

Santabrata Das, Sandip K. Chakrabarti

We study the properties of the shock waves for a viscous accretion flow having low angular momentum in presence of synchrotron cooling. We present all possible accretion solutions in terms of flow parameters. We identify the region of the parameter space for steady and oscillating shocks and show the effect of various energy dissipation processes on it. We d

Greg Sepesi

A generalization of the heapsort algorithm is proposed. At the expense of about 50% more comparison and move operations for typical cases, the dualheap sort algorithm offers several advantages over heapsort: improved cache performance, better performance if the input happens to be already sorted, and easier parallel implementations.

J. Robrade, J. H. M. M. Schmitt

Using three XMM-Newton observations we study the X-ray emission of RU Lup, a accreting and wind-driving CTTS. In comparison with other bright CTTS we study possible signatures of accretion and winds in their X-ray emission. Results: We find three levels of activity among the observations of RU Lup, clearly of magnetic origin due to the corresponding high pla

I. Klich, C. Lannert, G. Refael

We study the survival of super-currents in a system of impenetrable bosons subject to a quantum quench from its critical superfluid phase to an insulating phase. We show that the evolution of the current when the quench follows a Rosen-Zener profile is exactly solvable. This allows us to analyze a quench of arbitrary rate, from a sudden destruction of the su

F. Canfora, A. Giacomini, S. Willison

Exact solutions with torsion in Einstein-Gauss-Bonnet gravity are derived. These solutions have a cross product structure of two constant curvature manifolds. The equations of motion give a relation for the coupling constants of the theory in order to have solutions with nontrivial torsion. This relation is not the Chern-Simons combination. One of the soluti

David Schuster

The first and most compelling evidence of the universe&#39;s expansion was, and continues to be, the observed redshift of spectra from distant objects. This paper plays &#34;devil&#39;s advocate&#34; by providing an alternative explanation with elementary physics. I assume a steady-state universe that is infinite in both expanse and age, with the observed re

Alex Levchenko, Alex Kamenev

We derive Ginzburg-Landau action by systematically integrating out electronic degrees of freedom in the framework of the Keldysh nonlinear sigma-model of disordered superconductors. The resulting Ginzburg-Landau functional contains a nonlocal $Δ$-dependent contribution to the diffusion constant, which leads, for example, to Maki-Thompson corrections. It also

Alessandro Fedrizzi, Thomas Herbst, Andreas Poppe, Thomas Jennewein

We demonstrate a wavelength-tunable, fiber-coupled source of polarization-entangled photons with extremely high spectral brightness and quality of entanglement. Using a 25 mm PPKTP crystal inside a polarization Sagnac interferometer we detect a spectral brightness of 273000 pairs/(s mW nm), a factor of 28 better than comparable previous sources while state t

Alex Olshevsky, John N. Tsitsiklis

We provide an example proving that there exists no quadratic Lyapunov function for a certain class of linear agreement/consensus algorithms, a fact that had been numerically verified in [5]. We also briefly discuss sufficient conditions for the existence of such a Lyapunov function.

Michael A. Shulman

We prove that the homotopy theory of parametrized spaces embeds fully and faithfully in the homotopy theory of simplicial presheaves, and that its essential image consists of the locally homotopically constant objects. This gives a homotopy-theoretic version of the classical identification of covering spaces with locally constant sheaves. We also prove a new

Vitor M. Pereira, Johan Nilsson, A. H. Castro Neto

We address the problem of an unscreened Coulomb charge in graphene, and calculate the local density of states and displaced charge as a function of energy and distance from the impurity. This is done non-perturbatively in two different ways: (1) solving the problem exactly by studying numerically the tight-binding model on the lattice; (2) using the continuu

Michael Shulman

We introduce a new categorical framework for studying derived functors, and in particular for comparing composites of left and right derived functors. Our central observation is that model categories are the objects of a double category whose vertical and horizontal arrows are left and right Quillen functors, respectively, and that passage to derived functor

Kaushik Majumdar

In this paper a novel architecture for cortical computation has been proposed. This architecture is composed of computing paths consisting of neurons and synapses only. These paths have been decomposed into lateral, longitudinal and vertical components. Cortical computation has then been decomposed into lateral computation (LaC), longitudinal computation (Lo

A. Cuoco, G. Miele, P. D. Serpico

We compare the clustering properties of the combined dataset of ultra-high energy cosmic rays events, reported by the AGASA, HiRes, Yakutsk and Sugar collaborations, with a catalogue of galaxies of the local universe (redshift z<~0.06). We find that the data reproduce particularly well the clustering properties of the nearby universe within z <~0.02. There i

Yanir A. Rubinstein

In this Note we introduce and study dynamical systems related to the Ricci operator on the space of Kahler metrics as discretizations of certain geometric flows. We pose a conjecture on their convergence towards canonical Kahler metrics and study the case where the first Chern class is negative, zero or positive. This construction has several applications in

Spyros D. Avramis, Konstadinos Sfetsos, Konstadinos Siampos

We extend our earlier work, regarding the perturbative stability of string configurations used for computing the interaction potential of heavy quarks within the gauge/gravity correspondence, to cover a more general class of gravity duals. We provide results, mostly based on analytic methods and corroborated by numerical calculations, which apply to strings

Celso C. Nishi

Extensions of the Standard Model with $N$ Higgs doublets are simple extensions presenting a rich mathematical structure. An underlying Minkowski structure emerges from the study of both variable space and parameter space. The former can be completely parametrized in terms of two future lightlike Minkowski vectors with spatial parts forming an angle whose cos

D. Besson, CLEO Collaboration

Using the CLEO III detector, we measure absolute cross sections for e+e- --> hadrons at seven center-of-mass energies between 6.964 and 10.538 GeV. The values of R, the ratio of hadronic and muon pair production cross sections, are determined within 2% total r.m.s. uncertainty.

Ofer Aharony, Sean A. Hartnoll

We analyze in detail a second order phase transition that occurs in large N Gaussian multi-matrix models in which the matrices are constrained to be commuting. The phase transition occurs as the relative masses of the matrices are varied, assuming that there are at least four matrices in the lowest mass level. We also discuss the phase structure of weakly co

Beatriz Gato-Rivera

In 1998 the Adapted Ordering Method was developed for the representation theory of the superconformal algebras in two dimensions. It allows: to determine maximal dimensions for a given type of space of singular vectors, to identify all singular vectors by only a few coefficients, to spot subsingular vectors and to set the basis for constructing embedding dia

A. Marshakov

We discuss microscopic origin of integrability in Seiberg-Witten theory, following mostly the results of hep-th/0612019, as well as present their certain extension and consider several explicit examples. In particular, we discuss in more detail the theory with the only switched on higher perturbation in the ultraviolet, where extra explicit formulas are obta

B. Abdesselam, A. Chakrabarti, V. K. Dobrev, S. G. Mihov

A class of $(2n)^2\times(2n)^2$ multiparameter braid matrices are presented for all $n$ $(n\geq 1)$. Apart from the spectral parameter $θ$, they depend on $2n^2$ free parameters $m_{ij}^{(\pm)}$, $i,j=1,...,n$. For real parameters the matrices $R(θ)$ are nonunitary. For purely imaginary parameters they became unitary. Thus a unification is achieved with odd

D. S. Petrov, G. E. Astrakharchik, D. J. Papoular, C. Salomon

We show that the system of weakly bound molecules of heavy and light fermionic atoms is characterized by a long-range intermolecular repulsion and can undergo a gas-crystal quantum transition if the mass ratio exceeds a critical value. For the critical mass ratio above 100 obtained in our calculations, this crystalline order can be observed as a superlattice

Ana L. C. Pereira, P. A. Schulz

Effects of disorder and valley polarization in graphene are investigated in the quantum Hall regime. We find anomalous localization properties for the lowest Landau level (LL), where disorder can induce wavefunction delocalization (instead of localization), both for white-noise and gaussian-correlated disorder. We quantitatively identify the contribution of

C. A. Ryan, O. Moussa, J. Baugh, R. Laflamme

We show experimental results demonstrating multiple rounds of heat-bath algorithmic cooling in a 3 qubit solid-state nuclear magnetic resonance quantum information processor. By dynamically pumping entropy out of the system of interest and into the heat-bath, we are able show purification of a single qubit to a polarization 1.69 times that of the heat-bath a

Domenico Marinucci, Giovanni Peccati

We study the weak convergence (in the high-frequency limit) of the frequency components associated with Gaussian-subordinated, spherical and isotropic random fields. In particular, we provide conditions for asymptotic Gaussianity and we establish a new connection with random walks on the the dual of SO(3), which mirrors analogous results previously establish

Chi-Tuong Pham, Pedro Patrício, Jose Manuel Romero-Enrique

In this article, we generalize Wenzel law, which assigns an effective contact angle for a droplet on a rough substrate, when the wetting layer has an ordered phase, like a nematic. We estimate the conditions for which the wetting behavior of an ordered fluid can be qualitatively different from the one usually found in a simple fluid. To particularize our gen

M. Grether, M. de Llano, George A. Baker

The Bose-Einstein condensation (BEC) critical temperature in a relativistic ideal Bose gas of identical bosons, with and without the antibosons expected to be pair-produced abundantly at sufficiently hot temperatures, is exactly calculated for all boson number-densities, all boson point rest masses, and all temperatures. The Helmholtz free energy at the crit

Tonći Antunović, Ivan Veselić

We study the low energy asymptotics of periodic and random Laplace operators on Cayley graphs of amenable, finitely generated groups. For the periodic operator the asymptotics is characterised by the van Hove exponent or zeroth Novikov-Shubin invariant. The random model we consider is given in terms of an adjacency Laplacian on site or edge percolation subgr

Jonathan Sondow

This is an elementary note. It corrects a mistake in the reformulation of the Riemann Hypothesis in J. Havil&#39;s book Gamma: Exploring Euler&#39;s Constant.

Naila Rahman, Rajeev Raman

We analyse the average-case cache performance of distribution sorting algorithms in the case when keys are independently but not necessarily uniformly distributed. The analysis is for both `in-place&#39; and `out-of-place&#39; distribution sorting algorithms and is more accurate than the analysis presented in \cite{RRESA00}. In particular, this new analysis

Alan Barros de Oliveira, Giancarlo Franzese, Paulo A. Netz, Marcia C. Barbosa

We investigate by molecular dynamics simulations a continuous isotropic core-softened potential with attractive well in three dimensions, introduced by Franzese [cond-mat/0703681, to appear on Journal of Molecular Liquids], that displays liquid-liquid coexistence with a critical point and water-like density anomaly. Here we find diffusion and structural anom

Elias P. Gyftopoulos, Michael R. von Spakovsky

In a PRL [1], the authors claim to show that &#34;the Clausius inequality can be violated, and that it is even possible to extract work from a thermal bath by cyclic variations of a parameter (&#34;perpetuum mobile&#34;), and that the physical cause for this behavior is traced back to quantum coherence in the presence of the nonequilibrium bath (sic)&#34;.

R. Aloisio, V. Berezinsky, P. Blasi, S. Ostapchenko

We discuss the signatures of the transition from galactic to extragalactic cosmic rays in different scenarios, giving most attention to the dip scenario. The dip is a feature in the diffuse spectrum of ultra-high energy (UHE) protons in the energy range $1\times 10^{18} - 4\times 10^{19}$ eV, which is caused by electron-positron pair production on the cosmic

Stephen A. Fulling

Quantum vacuum energy (Casimir energy) is reviewed for a mathematical audience as a topic in spectral theory. Then some one-dimensional systems are solved exactly, in terms of closed classical paths and periodic orbits. The relations among local spectral densities, energy densities, global eigenvalue densities, and total energies are demonstrated. This mater