January 2005 arXiv papers — page 4

Matt Kalinski

We show that the Unruh-Davies effect is measurable from Trojan wavepackets in muonic Hydrogen as the acceleration on the first muonic Bohr orbit reaches 10^25 of the earth acceleration. It is the biggest acceleration achievable in the laboratory environment which have been ever predicted for the cyclotronic configuration. We calculate the ratio between the p

Dirk-Gunnar Welsch, Christian Raabe

This is the abstract of an invited contribution to be presented at the 9th International Conference on Squeezed States and Uncertainty Relations, ICSSUR '05, Besancon, France, May 2-6, 2005.

Alastair Kay, Jiannis K. Pachos, Charles S. Adams

We present a novel way to manipulate ultra-cold atoms where four atomic levels are trapped by appropriately tuned optical lattices. When employed to perform quantum computation via global control, this unique structure dramatically reduces the number of steps involved in the control procedures, either for the standard, network, model, or for one-way quantum

Aditi Mallik, Keith Runge, Hai-Ping Cheng, James W. Dufty

For problems relating to fracture, a consistent embedding of a quantum (QM) domain in its classical (CM) environment requires that the classical system should yield the same structure and elastic properties as the QM domain for states near equilibrium. It is proposed that an appropriate classical potential can be constructed using ab initio data on the equil

Lei Xu, Wendy W. Zhang, Sidney R. Nagel

The corona splash due to the impact of a liquid drop on a smooth dry substrate is investigated with high speed photography. A striking phenomenon is observed: splashing can be completely suppressed by decreasing the pressure of the surrounding gas. The threshold pressure where a splash first occurs is measured as a function of the impact velocity and found t

James J. Kelly

We analyze data for 12C(e,e&#39;p) with Q^2 < 2 (GeV/c)^2 using the relativistic distorted-wave impulse approximation (RDWIA) based upon Dirac-Hartree wave functions. The 1p normalization extracted from data for Q^2 > 0.6 (GeV/c)^2 is approximately 0.87, independent of Q^2, which is consistent with the predicted depletion by short-range correlations. The tot

James J. Kelly

We use the relativistic distorted-wave impulse approximation (RDWIA) to study the effects of negative-energy components of Dirac wave functions on the left-right asymmetry for (e,e&#39;p) reactions on 16-O with 0.2 < Q^2 < 0.8 and 12-C with 0.6 < Q^2 < 1.8 (GeV/c)^2. Spinor distortion is more important for the bound state than for the ejectile and the net ef

Andriy Kostyuk, Horst Stoecker

The production of the psi&#39; meson in Pb+Pb collisions at CERN SPS is analyzed. It provides an evidence for charmonium regeneration via charm quark-antiquark coalescence at hadronization.

R. Higa, M. R. Robilotta, C. A. da Rocha

The chiral two-pion exchange nucleon-nucleon interaction has nowadays a rather firm conceptual basis, but depends on low-energy constants, which may be extracted from fits to data. In order to facilitate this kind of application, we present here a parametrized version of our relativistic expansion of this component of the force to $O(q^4)$, performed recentl

Gentaro Watanabe, Toshiki Maruyama, Katsuhiko Sato, Kenji Yasuoka

Calculations of equilibrium properties of dense matter predict that at subnuclear densities nuclei can be rodlike or slablike. To investigate whether transitions between phases with non-spherical nuclei can occur during the collapse of a star, we perform quantum molecular dynamic simulations of the compression of dense matter. We have succeeded in simulating

S. Damjanovic

The NA60 experiment at the CERN SPS studies dimuon production in proton-nucleus and nucleus-nucleus collisions. The combined information from a novel vertex telescope made of radiation-tolerant silicon pixel detectors and from the muon spectrometer previously used in NA50 allows for a precise measurement of the muon vertex and a much improved dimuon mass res

P. Fedorets, M. Buescher, V. P. Chernyshev, S. Dymov

The reaction pp -> dpi+eta has been measured at a beam energy of T=2.65 GeV (p=3.46 GeV/c) using the ANKE spectrometer at COSY-Juelich. The missing mass distribution of the detected dpi+ pairs exhibits a peak around the eta mass on top of a strong background of multi-pion pp -> dpi+(n(pi)) events. The differential cross section d^4(sigma)/d(Omega_d)d(Omega_p

Mladen Nikolic, Milan Rajkovic

Some new properties of symmetries that disappear as point symmetries after the first reduction of order of an ODE and reappear after the second are analyzed from the aspect of three-dimensional subalgebra of symmetries of differential equations. The form of a hidden symmetry is shown to consist of two parts, one of which always remains preserved as a point s

C. Adiga, N. Anitha, T. Kim

In this paper we obtain some new transformation formula for Ramanujan summation formula and also establish some eta-function identities. we also deduce a q-Gamma function identity, n q-integral and some interesting series representation.

Justin Tatch Moore

The purpose of this paper is to present some results which suggest that the Singular Cardinals Hypothesis follows from the Proper Forcing Axiom. What will be proved is that a form of simultaneous reflection follows from the Set Mapping Reflection Principle, a consequence of PFA. While the results fall short of showing that MRP implies SCH, it will be shown t

Justin Tatch Moore

In this note we will discuss a new reflection principle which follows from the Proper Forcing Axiom. The immediate purpose will be to prove that the bounded form of the Proper Forcing Axiom implies both that 2^omega = omega_2 and that L(P(omega_1)) satisfies the Axiom of Choice. It will also be demonstrated that this reflection principle implies that combina

Justin Tatch Moore

In this paper I will show that it is relatively consistent with the usual axioms of mathematics (ZFC) together with a strong form of the axiom of infinity (the existence of a supercompact cardinal) that the class of uncountable linear orders has a five element basis. In fact such a basis follows from the Proper Forcing Axiom, a strong form of the Baire Categ

Justin Tatch Moore

In this paper I will construct a non-separable hereditarily Lindelof space (L space) without any additional axiomatic assumptions. I will also show that there is a function f from [omega_1]^2 to omega_1 such that if A,B, subsets of omega_1, are uncountable and x omega_1, then there are a < b in A and B respectively with f(a,b) = x. Previously it was unknown

A. N. Dranishnikov

This is a detailed introductory survey of the cohomological dimension theory of compact metric spaces.

Julio Fernandez, Josep Gonzalez, Joan-C. Lario

Given an odd representation of the absolute Galois group of Q onto PGL(2,3) and a positive integer N, there exists a twisted modular curve defined over Q whose rational points classify the quadratic Q-curves of degree N realizing the representation. The paper gives a method to provide an explicit plane quartic model for this curve in the genus-three case N=5

Donald Yau

The lambda-ring cohomology in dimensions 0 and 1 of certain truncated polynomial filtered lambda-rings are computed. The dimension 1 case is related to deformations of lambda-rings.

Donald Yau

It is shown that most possibly truncated power series rings admit uncountably many filtered lambda-ring structures. The question of how many of these filtered lambda-ring structures are topologically realizable by the K-theory of torsionfree spaces is also considered for truncated polynomial rings.

Donald Yau

Algebraic deformations of modules over a ring are considered. The resulting theory closely resembles Gerstenhaber&#39;s deformation theory of associative algebras.

Donald Yau

We observe that the Rector invariants classifying the genus of BS^3 show up in (orthogonal and unitary) K-theory. We then use this knowledge to show purely algebraically how the K-theory of the spaces in the genus of BS^3 differ. This provides new insights into a result of Notbohm in the case of BS^3.

Donald Yau

A cohomology theory for lambda-rings is developed. This is then applied to study deformations of lambda-rings.

Wolter Groenevelt

The irreducible $*$-representations of the Lie algebra $su(1,1)$ consist of discrete series representations, principal unitary series and complementary series. We calculate Racah coefficients for tensor product representations that consist of at least two discrete series representations. We use the explicit expressions for the Clebsch-Gordan coefficients as

Antoine Ducros

Let $k$ be a non-archimedean complete valued field and let X be a smooth Berkovich analytic $k$-curve. Let $F$ be a finite locally constant étale sheaf on $k$ whose torsion is prime to the residue characteristic. We denote by $|X|$ the underlying topological space and by $π$ the canonical map from the étale site to $|X|$. In this text we define a triangulati

Joaquin Perez, M. Magdalena Rodriguez, Martin Traizet

Let $\mathcal{K}$ be the space of properly embedded minimal tori in quotients of $\R^3$ by two independent translations, with any fixed (even) number of parallel ends. After an appropriate normalization, we prove that $\mathcal{K}$ is a 3-dimensional real analytic manifold that reduces to the finite coverings of the examples defined by Karcher, Meeks and Ros

Giovanni Peccati, Marc Yor

We present three new identities in law for quadratic functionals of conditioned bivariate Gaussian processes. In particular, our results provide a two-parameter generalization of a celebrated identity in law, involving the path variance of a Brownian bridge, due to Watson (1961). The proof is based on ideas from a recent note by J. R. Pycke (2005) and on the

A. Raouf Chouikha

In this work we consider periodic spherically symmetric metrics of constant positive scalar curvature on the n-dimensional cylinder called pseudo-cylindric metrics. These metrics belong to the conformal class $[g_0]$ of the Riemannian product $S^1\times S^{n-1}$ : a circle of length $T$ crossed with the (n-1)-dimensional standard sphere. Such metrics have a

S. Bertone, A. Cellina, E. M. Marchini

In this paper we consider Hopf&#39;s Lemma and the Strong Maximum Principle for supersolutions to a class of non elliptic equations. In particular we prove a sufficient condition for the validity of Hopf&#39;s Lemma and of the Strong Maximum Principle and we give a condition which is at once necessary for the validity of Hopf&#39;s Lemma and sufficient for t

Thomas Brady, Colum Watt

For a finite real reflection group $W$ with Coxeter element $γ$ we give a uniform proof that the closed interval, $[I, γ]$ forms a lattice in the partial order on $W$ induced by reflection length. The proof involves the construction of a simplicial complex which can be embedded in the type W simplicial generalised associahedron.

Mordechai Katzman, Rodney Y. Sharp

This paper is concerned with ideals in a commutative Noetherian ring $R$ of prime characteristic. The main purpose is to show that the Frobenius closures of certain ideals of $R$ generated by regular sequences exhibit a desirable type of `uniform&#39; behaviour. The principal technical tool used is a result, proved by R. Hartshorne and R. Speiser in the case

Guido Gentile, Michele V. Bartuccelli, Jonathan H. B. Deane

We consider a class of second order ordinary differential equations describing one-dimensional systems with a quasi-periodic analytic forcing term and in the presence of damping. As a physical application one can think of a resistor-inductor-varactor circuit with a periodic (or quasi-periodic) forcing function, even if the range of applicability of the theor

Sonia Martinez, Francesco Bullo, Jorge Cortes, Emilio Frazzoli

This paper proposes a formal model for a network of robotic agents that move and communicate. Building on concepts from distributed computation, robotics and control theory, we define notions of robotic network, control and communication law, coordination task, and time and communication complexity. We then analyze a number of basic motion coordination algor

Paolo Lisca, Andras I. Stipsicz

We prove various results on contact structures obtained by contact surgery on a single Legendrian knot in the standard contact three--sphere. Our main tool are the contact Ozsvath--Szabo invariants.

Mathias Beiglböck, Christian Steineder, Reinhard Winkler

Let H be a countable subgroup of the metrizable compact abelian group G and f:H -> T=R/Z a (not necessarily continuous) character of H. Then there exists a sequence (chi_n)_n of (continuous) characters of G such that lim_n chi_n(alpha) = f(alpha) for all alpha in H and (chi_n(alpha))_n does not converge whenever alpha in G\H. If one drops the countability an

Ben Green, Imre Z. Ruzsa

We study the extent to which sets A in Z/NZ, N prime, resemble sets of integers from the additive point of view (``up to Freiman isomorphism&#39;&#39;). We give a direct proof of a result of Freiman, namely that if |A + A| < K|A| and |A| < c(K)N then A is Freiman isomorphic to a set of integers. Because we avoid appealing to Freiman&#39;s structure theorem,

L. N. Granda

We investigate the exact renormalization group (RG) in Einstein gravity coupled to N-component spinor field, working in the effective average action formalism and background field method. The truncated evolution equation is obtained for the Newtonian and cosmological constants. We have shown that screening or antiscreening behaviour of the gravitational coup

P. D. Jarvis, J. W. van Holten

We present a conformal theory of a dissipationless relativistic fluid in 2 space-time dimensions. The theory carries with it a representation of the algebra of 2-$D$ area-preserving diffeomorphisms in the target space of the complex scalar potentials. A complete canonical description is given, and the central charge of the current algebra is calculated. The

B. Eden

We check the recently proposed higher loop Bethe-ansatz for the sl(2) sector of N=4 at two loops by a direct perturbative calculation using N=2 superfields in supersymmetric dimensional reduction. Our method can in principle address operators built from many elementary fields and of arbitrary twist. We work out in detail the spin three, twist three operator

Surya Ganguli, Petr Horava, Anthony Ndirango

The boundary scattering problem in 1+1 dimensional CFT is relevant to a multitude of areas of physics, ranging from the Kondo effect in condensed matter theory to tachyon condensation in string theory. Invoking a correspondence between CFT on 1+1 dimensional manifolds with boundaries and Chern-Simons gauge theory on 2+1 dimensional Z_2 orbifolds, we show tha

Branko Dragovich, Zoran Rakic

We consider classical and quantum mechanics related to an additional noncommutativity, symmetric in position and momentum coordinates. We show that such mechanical system can be transformed to the corresponding one which allows employment of the usual formalism. In particular, we found explicit connections between quadratic Hamiltonians and Lagrangians, in t

Zurab Ratiani

In this diploma thesis vector field is constructed on $R \times S^3$. The free lagrangian on the curved space is invariant under conformal transformations of the dynamical field $A_m(x)$. The gauge fixing term is not conformally invariant, but it is invariant under Poincare transformations of the fields $A_m(x)$. Propagator quantisation is carried out. The e

Michael Duetsch, Klaus Fredenhagen

A fresh look at the renormalization group (in the sense of Stueckelberg-Petermann) from the point of view of algebraic quantum field theory is given, and it is shown that a consistent definition of local algebras of observables and of interacting fields in renormalized perturbative quantum field theory can be given in terms of retarded products. The dependen

D. Dudal, J. A. Gracey, V. E. R. Lemes, M. S. Sarandy

We investigate a dynamical mass generation mechanism for the off-diagonal gluons and ghosts in SU(N) Yang-Mills theories, quantized in the maximal Abelian gauge. Such a mass can be seen as evidence for the Abelian dominance in that gauge. It originates from the condensation of a mixed gluon-ghost operator of mass dimension two, which lowers the vacuum energy

Song Shu, Jia-Rong Li

With the linear sigma model, we have studied Bose-Einstein condensation and the chiral phase transition in the chiral limit for an interacting pion system. A $μ-T$ phase diagram including these two phenomena is presented. It is found that the phase plane has been divided into three areas: the Bose-Einstein condensation area, the chiral symmetry broken phase

L. N. Granda

we investigate the exact renormalization group (RG) in Einstein gravity coupled to N-component scalar field, working in the effective average action formalism and background field method. The truncated evolution equation is obtained for the Newtonian and cosmological constants. We have shown that screening or antiscreening behaviour of the gravitational coup

Dongsu Bak, Seok Kim, Soo-Jong Rey

We find a class of d=4, N=2 supergravity with $R^2$-interactions that admits exact BPS black holes. The prepotential contains quadratic, cubic and chiral curvature-squared terms. Black hole geometry realizes stretched horizon, and consists of anti-de Sitter, intermediate and outermost flat regions. Mass and entropy depends on charges and are modified not onl

Olaf Dreyer

We introduce the notion of background independent quantum field theory. The distinguishing feature of this theory is that the dynamics can be formulated without recourse to a background metric structure. We show in a simple model how the metric properties of spacetime can be recovered from the dynamics. Background independence is not only conceptually desira

Olivier Espinosa

We prove in full generality the thermal operator representation for Matsubara sums in a relativistic field theory of scalar and fermionic particles. It states that the full result of performing the Matsubara sum associated to any given Feynman graph, in the imaginary-time formalism of finite-temperature field theory, can be directly obtained from its corresp

George Sterman

A few comments are made on the role of nonperturbative and perturbative power corrections. This is followed by a description of energy flow observables and correlations that may provide a flexible approach to rapidity distributions in hadronic scattering.

T. P. Ilichova, S. G. Shulga

The mean square radius of the proton charge distribution was studied in the framework of the relativistic quasipotential quark model in assumption of the SU(6)-symmetry. It was shown that the proton charge radius is represented as function f(m/γ)/M^2 for point quarks (m is a quark mass, γis the scale of the coupling energy, M is the nucleon mass, f is undime

D. Yu. Ivanov, G. L. Kotkin, V. G. Serbo

We consider emission of a photon by an electron in the field of a strong laser wave. A probability of this process for circularly or linearly polarized laser photons and for arbitrary polarization of all other particles is calculated. We obtain the complete set of functions which describe such a probability in a compact invariant form. Besides, we discuss in

Jacob L. Bourjaily, Gordon L. Kane

Although a discovery of wimps either at colliders or in direct experiments would have enormous implications for our understanding of particle physics, it would imply less than one would like about our understanding of the dark matter in the universe or in the galactic halo: it surely is possible that the discovered particles account for only a little of the

P. M. Ferreira

We calculate the one-loop contributions to the MSSM effective potential when the scalar top fields have non-zero vacuum expectation values and study their impact on charge and colour breaking bounds.

M. Gockeler, Ph. Hagler, R. Horsley, D. Pleiter

We present here the latest results from the QCDSF collaboration for moments of generalized parton distributions and transversity in two-flavour QCD, including a preliminary analysis of the pion mass dependence.

J. Kiryluk

STAR collected data in proton-proton collisions at sqrt(s)=200 GeV with transverse and longitudinal beam polarizations during the 2003 running period at RHIC. We present preliminary results on single transverse spin asymmetries A_N in the production of forward charged hadrons detected with the Beam-Beam Counters (BBC). The asymmetries A_N measured at pseudor

B. Aubert, BaBar Collaboration

We present updated measurements of the CP-violating parameters S_pipi and C_pipi in B0 -> pi+pi- decays. Using a sample of 227 million Y(4S) -> BBbar decays collected with the BaBar detector at the PEP-II asymmetric-energy e+e- collider at SLAC, we observe 467 +- 33 signal decays and measure S_pipi = -0.30 +- 0.17 (stat) +- 0.03 (syst), and C_pipi = -0.09 +-

ZEUS Collaboration

A search for pentaquarks decaying to Xi^{-} pi^{-} (Xi^{-} pi^{+}) and corresponding antiparticles has been performed with the ZEUS detector at HERA. The data sample consists of deep inelastic ep scattering events at centre-of-mass energies of 300 and 318 GeV, and corresponds to 121 pb^{-1} of integrated luminosity. A clear signal for Xi^{0}(1530) to Xi^{-}

A. Mikovic

We give a brief and a critical review of the Barret-Crane spin foam models of quantum gravity. Then we describe two new spin foam models which are obtained by direct quantization of General Relativity and do not have some of the drawbacks of the Barret-Crane models. These are the model of spin foam invariants for the embedded spin networks in loop quantum gr

Angelo Tartaglia, Matteo Luca Ruggiero, Alessandro Nagar

The aim of this paper is to study the time delay on electromagnetic signals propagating across a binary stellar system. We focus on the antisymmetric gravitomagnetic contribution due to the angular momentum of one of the stars of the pair. Considering a pulsar as the source of the signals, the effect would be manifest both in the arrival times of the pulses

E. A. Tagirov

An origin and necessity of so called conformal (or,Penrose-Chernikov-Tagirov) coupling of scalar field to the metric of n-dimensional Riemannian space-time is discussed in brief. The corresponding general-relativistic field equation implies a one-particle (quantum mechanical) Schrodinger Hamiltonian which depends on the space-time dimensionality n, contrary

Thomas Eiter, Axel Polleres

Answer set programming (ASP) with disjunction offers a powerful tool for declaratively representing and solving hard problems. Many NP-complete problems can be encoded in the answer set semantics of logic programs in a very concise and intuitive way, where the encoding reflects the typical &#34;guess and check&#34; nature of NP problems: The property is enco

Jon Phipps, Diane I. Hillmann, Gordon Paynter

Harvested metadata often suffers from uneven quality to the point that utility is compromised. Although some aggregators have developed methods for evaluating and repairing specific metadata problems, it has been unclear how these methods might be scaled into services that can be used within an automated production environment. The National Science Digital L

Adriel Kind, Alex Grant

Application of the turbo principle to multiuser decoding results in an exchange of probability distributions between two sets of constraints. Firstly, constraints imposed by the multiple-access channel, and secondly, individual constraints imposed by each users&#39; error control code. A-posteriori probability computation for the first set of constraints is

T. A. Aslanyan

We show that a ferroelectric phase transition takes place in the incommensurate phase of the K2SeO4 crystal. The ferroelectric character of the IC phase explains the second-harmonic generation observed in the corresponding temperature range.

Xiuping Tao, D. P. Landau, T. C. Schulthess, G. M. Stocks

Large scale computer simulations are used to elucidate a longstanding controversy regarding the existence, or otherwise, of spin waves in paramagnetic BCC iron. Spin dynamics simulations of the dynamic structure factor of a Heisenberg model of Fe with first principles interactions reveal that well defined peaks persist far above Curie temperature T_c. At lar

V. R. Shaginyan

A tunnelling conductivity between a heavy fermion metal and a simple metallic point is considered. We show that at low temperatures this conductivity can be noticeably dissymmetrical with respect to the change of voltage bias. The dissymmetry can be observed in experiments on the heavy fermion metals whose electronic system has undergone the fermion condensa

V. U. Nazarov, S. Nishigaki, J. M. Pitarke, C. S. Kim

We report a variational approach to the nonlinearly screened interaction of charged particles with a many-electron system. This approach has been developed by introducing a modification of the Schwinger variational principle of scattering theory, which allows to obtain nonperturbative scattering cross-sections of moving projectiles from the knowledge of the

Achille Giacometti, Domenico Gazzillo, Giorgio Pastore, T. Kanti Das

The main goal of this paper is to assess the limits of validity, in the regime of low concentration and strong Coulomb coupling (high molecular charges), for a simple perturbative approximation to the radial distribution functions (RDF), based upon a low-density expansion of the potential of mean force and proposed to describe protein-protein interactions in

J. Dorier, F. Becca, F. Mila

Using exact diagonalizations, Green&#39;s function Monte Carlo simulations and high-order perturbation theory, we study the low-energy properties of the two-dimensional spin-1/2 compass model on the square lattice defined by the Hamiltonian $H = - \sum_{\bm{r}} (J_x σ_{\bm{r}}^x σ_{\bm{r} + \bm{e}_x}^x + J_z σ_{\bm{r}}^z σ_{\bm{r} + \bm{e}_z}^z)$. When $J_x\

Sakari Seitz, Mikko Alava, Pekka Orponen

A local search algorithm solving an NP-complete optimisation problem can be viewed as a stochastic process moving in an &#39;energy landscape&#39; towards eventually finding an optimal solution. For the random 3-satisfiability problem, the heuristic of focusing the local moves on the presently unsatisfiedclauses is known to be very effective: the time to sol

A. A. Taskin, A. N. Lavrov, Yoichi Ando

Single crystals of the layered perovskite GdBaCo_{2}O_{5+x} (GBCO) have been grown by the floating-zone method, and their transport, magnetic, and structural properties have been studied in detail over a wide range of oxygen contents. The obtained data are used to establish a rich phase diagram centered at the &#34;parent&#39;&#39; compound GdBaCo_{2}O_{5.5}

A. Tsukada, M. Noda, H. Yamamoto, M. Naito

We have systematically investigated the effect of oxygen nonstoichiometry in a nominally undoped superconductor T&#39;-(La,Y)2CuO4+y. In the experiments, the reduction condition was changed after the sample growth by MBE. The superconductivity is very sensitive to the reduction condition. With systematically increasingly reduced atmospheres, resistivity show

A. Tsukada, H. Yamamoto, M. Naito

We attempted Ce doping in La2CuO4 with the K2NiF4 (T) structure by molecular beam epitaxy. At low growth temperature and with an appropriate substrate choice, we found that Ce can be incorporated into the K2NiF4 lattice up to x ~ 0.06, which had not yet been realized in bulk synthesis. The doping of Ce makes T-La2-xCexCuO4 more insulating, which is in sharp

M. Noda, A. Tsukada, H. Yamamoto, M. Naito

We have performed a systematic investigation of the variations of the lattice constants with substituent rare-earth element concentration x in the nominally undoped superconductors T&#39;-(La3+)2-x(RE3+)xCuO4 (RE = Sm, Eu, Gd, Tb, Lu, and Y), which we have recently discovered using MBE. The results show both the in-plane and out-of-plane lattice constants (a

R. Y. Gu, V. P. Antropov

Density functional calculations are performed to investigate the phase transition in FeRh alloy. The effective exchange coupling, the critical temperature of magnetic phase transition and the adiabatic spin wave spectrum have been obtained. Different contributions to the free energy of different phases are estimated. It has been found that the antiferro-ferr

Raphael Blumenfeld

The isostaticity theory for stress transmission in macroscopic planar particulate assemblies is extended here to non-rigid particles. It is shown that, provided that the mean coordination number in $d$ dimensions is $d+1$, macroscopic systems can be mapped onto equivalent assemblies of perectly rigid particles that support the same stress field. The error in

Gilles Zumbach

The influence of the past price behaviour on the realized volatility is investigated in the present article. The results show that trending (drifting) prices lead to increased (decreased) realized volatility. This ``volatility induced by trend&#39;&#39; constitutes a new stylized fact. The past price behaviour is measured by a product of 2 non overlapping re

Satoshi Fujimoto

We present a certain class of two-dimensional frustrated quantum Heisenberg spin systems with multiple ring exchange interactions which are rigorously demonstrated to have quantum disordered ground states without magnetic long-range order. The systems considered in this paper are s=1/2 antiferromagnets on a honeycomb and square lattices, and an s=1 antiferro

Yu-Ming Lin, Joerg Appenzeller, Joachim Knoch, Phaedon Avouris

State-of-the-art carbon nanotube field-effect transistors (CNFETs) behave as Schottky barrier (SB)-modulated transistors. It is known that vertical scaling of the gate oxide significantly improves the performance of these devices. However, decreasing the oxide thickness also results in pronounced ambipolar transistor characteristics and increased drain leaka

Andrei Belsky, Stéphane Esnouf, Serguei V. Garnov, Jérôme Gaudin

We used high order harmonics of a femtosecond titanium-doped sapphire system (pulse duration 25 fs) to realise Ultraviolet Photoelectron Spectroscopy (UPS) measurements on diamond. The UPS spectra were measured for harmonics in the range 13 to 27. We also made ab initio calculations of the electronic lifetime of conduction electrons in the energy range produ

Menghui Li, Jinshan Wu, Dahui Wang, Tao Zhou

Inspired by scientific collaboration networks, especially our empirical analysis of the network of econophysicists, an evolutionary model for weighted networks is proposed. Both degree-driven and weight-driven models are considered. Compared with the BA model and other evolving models with preferential attachment, there are two significant generalizations. F

Nicholas R. Goold, Ellak Somfai, Robin C. Ball

We explore the macroscopic consequences of lattice anisotropy for Diffusion Limited Aggregation (DLA) in three dimensions. Simple cubic and BCC lattice growths are shown to approach universal asymptotic states in a coherent fashion, and the approach is accelerated by the use of noise reduction. These states are strikingly anisotropic dendrites with a rich hi

A. G. Bashkirov

The Boltzmann entropy $S^{(B)}$ is true in the case of equal probability of all microstates of a system. In the opposite case it should be averaged over all microstates that gives rise to the Boltzmann--Shannon entropy (BSE). Maximum entropy principle (MEP) for the BSE leads to the Gibbs canonical distribution that is incompatible with power--low distributio

T. Dahm, P. J. Hirschfeld, L. Zhu, D. J. Scalapino

Elastic forward scattering can lead to an anomaly in the ARPES spectrum of the cuprate superconductors. Here we discuss how this anomaly can be used to provide a measurement of the superconducting gap Delta_k for k values away from the Fermi surface.

R. S. Furuya, R. Cesaroni, S. Takahashi, M. Momose

Using the Owens Valley and Nobeyama Radio Observatory interferometers, we carried out an unbiased search for hot molecular cores and ultracompact UC HII regions toward the high-mass star forming region G19.61--0.23. In addition, we performed 1.2 mm imaging with SIMBA, and retrieved 3.5 and 2 cm images from the VLA archive data base. The newly obtained 3 mm i

M. Novello, M. Makler, L. S. Werneck, C. A. Romero

We introduce an extension of the Born-Infeld action for a scalar field and show that it can act as unifying-dark-matter, providing an explanation for both structure formation and the accelerated expansion of the universe. We investigate the cosmological dynamics of this theory in a particular case, referred as the &#34;Milne-Born-Infeld&#34; (MBI) Lagrangian

Jean-Rene Gauthier, Hugo Martel

We present the summary of the theoretical aspects and algorithms used in an undergraduate (JRG) summer project based on numerical N-body simulations of collisionless systems. First, we review the importance of numerical N-body simulations in astrophysics. We introduce the different codes used and their performances. We then introduce four famous density prof

J. E. Smith, A. Robinson, S. Young, D. J. Axon

We present detailed scattering models confirming that distinctive variations in polarization across the broad Halpha line, which are observed in a significant fraction of Seyfert 1 galaxies, can be understood in terms of a rotating line-emitting disc surrounded by a co-planar scattering region (the equatorial scattering region). The predicted polarization pr

L. Georgiev, X. Hernandez

Terminal wind velocity and mass loss rate are the most fundamental parameters of stellar winds. Unfortunately, their determination calls for high resolution spectroscopy in a range of wavelengths spanning from the ultraviolet to the infrared. For weak and/or distant objects, this becomes unfeasible. Nevertheless, it is possible to obtain an accurate estimate

G. Lodato, W. K. M. Rice

In this paper, we extend our previous analysis (Lodato & Rice 2004) of the transport properties induced by gravitational instabilities in cooling, gaseous accretion discs to the case where the disc mass is comparable to the central object. In order to do so, we have performed global, three-dimensional smoothed particle hydrodynamics simulations of massive di

E. Gaztanaga, R. Scoccimarro

We study the behavior of the three-point correlation function xi_3 of dark matter and mock galaxies, concentrating on the effects of redshift-space distortions and the determination of galaxy bias parameters in current redshift galaxy surveys. On large scales, redshift space distortions tend to wash out slightly the configuration dependence of the reduced 3-

T. R. Kendall, J. Bouvier, E. Moraux, D. J. James

We report the first results of our ongoing campaign to discover the first brown dwarfs (BD) in NGC 2264, a young (3 Myr), populous star forming region for which our optical studies have revealed a very high density of potential candidates - 236 in $<$ 1 deg$^2$ - from the substellar limit down to at least $\sim$ 20 M$_{\rm Jup}$ for zero reddening. Candidate

E. Pointecouteau, M. Arnaud, G. W. Pratt

We present the integrated mass profiles for a sample of ten nearby (z<=0.15), relaxed galaxy clusters, covering a temperature range of [2-9]keV, observed with XMM-Newton. The mass profiles were derived from the observed gas density and temperature profiles under the hypothesis of spherical symmetry and hydrostatic equilibrium. All ten mass profiles are well

Otmar Stahl, Kerstin Weis, Dominik J. Bomans, Kris Davidson

We present spectroscopic observations with high spectral resolution of eta Car as seen by the SE lobe of the Homunculus nebula over the 2003.5 &#34;spectroscopic event&#34;. The observed spectra represent the stellar spectrum emitted near the pole of the star and are much less contaminated with nebular emission lines than direct observations of the central o

M. Monelli, C. E. Corsi, V. Castellani, I. Ferraro

We present deep multiband (F435W, F625W, and F658N) photometric data of the Globular Cluster Omega Cen collected with the Advanced Camera for Surveys on board of the Hubble Space Telescope. We identified in the (F435W-F625W, F435W) plane more than two thousand White Dwarf (WD) candidates using three out of nine available pointings. Such a large sample appear

F. Galliano, S. C. Madden, A. P. Jones, C. D. Wilson

We present new 450 and 850 micron SCUBA data and 1.3 mm MAMBO data of the dwarf galaxies II Zw 40, He 2-10 and NGC 1140. Additional ISOCAM, IRAS as well as ground based data are used to construct the observed mid-infrared to millimeter spectral energy distribution of these galaxies. These spectral energy distributions are modeled in a self-consistent way, as

L. Scelsi, A. Maggio, G. Peres, R. Pallavicini

We report on the analysis of XMM-Newton observations of three G-type stars in very different evolutionary phases: the weak-lined T Tauri star HD 283572, the Zero Age Main Sequence star EK Dra and the Hertzsprung-gap giant star 31 Com. They all have high X-ray luminosity (10^31 erg/s for HD 283572 and 31 Com and 10^30 erg/s for EK Dra). We compare the Emissio