January 2004 arXiv papers — page 5

O. Preuss, M. Schuessler, V. Holzwarth, S. K. Solanki

We consider the mechanical equilibrium and stability of matter trapped in the magnetosphere of a rapidly rotating star. Assuming a dipolar magnetic field and arbitrary inclination of the magnetic axis with respect to the axis of rotation we find stable equilibrium positions a) in a (warped) disk roughly aligned with the magnetic equatorial plane and b) at tw

Mark M. McKinnon

The polarization position angles (PA) of pulsar radio emission occupy a distribution that can be much wider than what is expected from the average linear polarization and the off-pulse instrumental noise. Contrary to our limited understanding of the emission mechanism, the excess dispersion in PA implies that pulsar PAs vary in a random fashion. An eigenvalu

A. Asensio Ramos, J. Trujillo Bueno, M. Collados

Here we report the first detection of polarization signals induced by the Zeeman effect in spectral lines of the E^4Π-A^4Πsystem of FeH located around 1.6 $μ$m. Motivated by the tentative detection of this band in the intensity spectrum of late-type dwarfs, we have investigated the full Stokes sunspot spectrum finding circular and linear polarization signatu

C. M. Gutierrez, M. Lopez-Corredoira

Spectroscopy and deep imaging of the group NEQ3 are presented. This system is formed by three compact objects with relative separations of ~2.6 and ~2.8 arcsec, and a lenticular galaxy at ~17 arcsec from the geometric centre of the group. A diffuse filament is located on a line joining the three compact objects and the main galaxy. Analysis of these observat

Daniel Harbeck, John S. Gallagher, Eva K. Grebel

We report results of a photometric survey with the WIYN telescope for carbon stars in the M 31 dwarf spheroidal (dSph) companions And III, And V, And VI, and And VII, as well as in the relatively isolated Local Group dSph Cetus. We find three carbon-star candidates in And VII and one carbon star in each And VI and Cetus. Comparing the carbon star content wit

M. Fellhauer

A new formation scenario for omega-Cen is presented, in which omega-Cen has formed from a star cluster complex (= super-cluster). The star-burst which has led to the formation of this cluster of star clusters was triggered by the infall and destruction of a gas-rich dwarf galaxy during the early build-up phase of the Milky Way. While the star clusters in the

M. E. Filho, F. Fraternali, S. Markoff, N. M. Nagar

We have analyzed new, archival and published high resolution radio and X-ray observations of a sample of composite LINER/HII galaxies known to exhibit AGN-like properties. Five of the 16 AGN candidates have milliarcsecond-scale detections and are found to display a compact, flat spectrum, high brightness temperature radio core, four of which also exhibit ext

Jingqiang Li, Joel H. Kastner, Gregory Y. Prigozhin, Norbert S. Schulz

We further investigate subpixel event repositioning (SER) algorithms in application to Chandra X-ray Observatory (CXO) CCD imaging. SER algorithms have been applied to backside illuminated (BI) Advanced CCD Imaging Spectrometer (ACIS) devices, and demonstrate spatial resolution improvements in Chandra/ACIS observations. Here a new SER algorithm that is charg

Jörn Dunkel

Numerous astrophysical observations have shown that classical Newtonian dynamics fails on galactic scales and beyond, if only visible matter is taken into account. The two most popular theoretical concepts dealing with this problem are Dark Matter (DM) and Modified Newtonian Dynamics (MOND). In the first part of this paper it is demonstrated that a generaliz

Fabrizio Tavecchio

I review the current knowledge of high-energy emission from extragalctic jets. First I discuss gamma-ray emission from blazars, which provides us numerous precious information on the innermost portions of the relativistic jets. I describe the constraints on the dynamics of the jet from the subpc to the pc scale provided by recent VLBI studies of TeV sources,

L. Ciotti, S. Pellegrini

The X-ray emitting interstellar medium of early type galaxies is often used as a tool to determine their total mass M and stellar orbital anisotropy beta profiles, based on the hypothesis of hydrostatic equilibrium for the hot gas. Here we investigate the effects that deviations from equilibrium have on M and beta estimates, by using simple analytical calcul

A. E. Piskunov, A. N. Belikov, N. V. Kharchenko, R. Sagar

Based on the CCD observations of remote young open clusters NGC 2383, NGC 2384, NGC 4103, NGC 4755, NGC 7510 and Hogg 15, we constructed their observed luminosity functions (LFs). The observed LFs are corrected for field star contamination determined with the help of galactic star count model. In the case of Hogg 15 and NGC 2383 we also considered the additi

V. V. Sokolov, T. A. Fatkhullin, V. N. Komarova, V. G. Kurt

We present the earliest BTA (SAO RAS 6-m telescope) spectroscopic observations of the GRB030329 optical transient (OT), which almost coincide in time with the first "break" (t ~ 0.5 day after the GRB) of the OT light curve. The BTA/MPFS (Multi Pupil Fiber Spectrograph) spectra are clearly not smooth: the OT spectra showed a continuum with several bro

Vahé Petrosian, Siming Liu

Stochastic acceleration of electrons and protons by waves propagating parallel to the large scale magnetic fields of magnetized plasmas is studied with emphasis on the feasibility of accelerating particles from a thermal background to relativistic energies and with the aim of determining the relative acceleration of the two species in one source. In general,

Jay Gambetta, T. Askerud, H. M. Wiseman

Non-Markovian evolution of an open quantum system can be `unraveled' into pure state trajectories generated by a non-Markovian stochastic (diffusive) Schrödinger equation, as introduced by Diósi, Gisin, and Strunz. Recently we have shown that such equations can be derived using the modal (hidden variable) interpretation of quantum mechanics. In this pape

G. Gour, V. Suneeta

We compare two area spectra proposed in loop quantum gravity in different approaches to compute the entropy of the Schwarzschild black hole. We describe the black hole in general microcanonical and canonical area ensembles for these spectra. We show that in the canonical ensemble, the results for all statistical quantities for any spectrum can be reproduced

Eduardo Rozo, Scott Dodelson, Joshua A. Frieman

We use the halo model formalism to provide expressions for cluster abundances and bias, as well as estimates for the correlation matrix between these observables. Off-diagonal elements due to scatter in the mass tracer scaling with mass are included, as are observational effects such as biases/scatter in the data, detection rates (completeness), and false de

Enrique Díaz-Herrera, José A. Moreno-Razo, Guillermo Ramírez-Santiago

We have carried out extensive equilibrium molecular dynamics (MD) simulations to study the structure and the interfacial properties in the liquid-vapor (LV) phase coexistence of partially miscible binary Lennard-Jones (LJ) mixtures. By analyzing the structural properties as a function of the miscibility parameter, $ α$, we found that at relatively low temper

Paul M. Alsing, Peter W. Milonni

A detector undergoing uniform acceleration $a$ in a vacuum field responds just as though it were immersed in thermal radiation of temperature $T=\hbar a/2\pi k c$. A simple, intuitive derivation of this result is given for the case of a scalar field in one spatial dimension. The approach is then extended to treat the case where the field seen by the accelera

José A. Zapata

We present an interpretation of loop quantization in the framework of lattice gauge theory. Within this context the lack of appropriate notions of effective theories and renormalization group flow exhibit loop quantization as an incomplete framework. This interpretation includes a construction of embedded spin foam models which does not rely on the choice of

Marco M. Caldarelli, Pedro J. Silva

In this article, we describe giant gravitons in AdS_5 x S^5 moving along generic trajectories in AdS_5. The giant graviton dynamics is solved by proving that the D3-brane effective action reduces to that of a massive point particle in AdS_5 and therefore the solutions are in one to one correspondence with timelike geodesics of AdS_5. All these configurations

Andrzej Krolak, Massimo Tinto, Michele Vallisneri

The LISA time-delay-interferometry responses to a gravitational-wave signal are rewritten in a form that accounts for the motion of the LISA constellation around the Sun; the responses are given in closed analytic forms valid for any frequency in the band accessible to LISA. We then present a complete procedure, based on the principle of maximum likelihood,

M. Porrati, J. -W. Rombouts

We re-examine the problem of strong coupling in a regularized version of DGP (or ``brane-induced'') gravity. We find that the regularization of ref. hep-th/0304148 differs from DGP in that it does not exhibit strong coupling or ghosts up to cubic order in the interactions. We suggest that the nonlocal nature of the theory, when written in terms of th

Krzysztof Turzynski

We analyze the most general version of the supersymmetric minimal see-saw model with only two right-chiral neutrinos which are degenerate in masses at the scale of Grand Unification. We study the renormalization effects that give rise to non-zero CP asymmetries in the decays of these neutrinos and find that their resonant enhancement due to small mass splitt

Richard J. Szabo

This paper is a rudimentary introduction, geared at non-specialists, to how noncommutative field theories arise in physics and their applications to string theory, particle physics and condensed matter systems.

Serguei Popov

We consider a stochastic variant of the game of Bulgarian solitaire [M. Gardner (1983), Sci. Amer. 249, 12-21]. For the stationary measure of the random Bulgarian solitaire, we prove that most of its mass is concentrated on (roughly) triangular configurations of certain type.

Anna Delin, Erio Tosatti

Monatomic nanowires of the nonmagnetic transition metals Ru, Rh, and Pd have been studied theoretically, using first-principles computational techniques, in order to investigate the possible onset of magnetism in these nanosystems. Our fully relativistic spin-polarized all-electron density functional calculations reveal the onset of Hund's rule magnetism

Vicente Vento

We discuss scenarios for scalar glueballs using arguments based on sum rules, spectral decomposition, the $\frac{1}{N_c}$ approximation, the scales of the strong interaction and the topology of the flux tubes. We analyze the phenomenological support of those scenarios and their observational implications. Our investigations hint a rich low lying glueball spe

S. V. Zaitsev-Zotov, V. E. Minakova

Light illumination of thin crystals of CDW conductor TaS$_3$ is found to result in dramatic changes of both linear ($G$) and nonlinear conduction. The increase of $G$ is accompanied by suppression of the collective conduction, growth of the threshold field $E_T$, and appearance of the switching and hysteretic behavior in the nonlinear conduction. The effects

Amit Giveon, Barak Kol, Amos Ori, Amit Sever

Certain time-like singularities are shown to be resolved already in classical General Relativity once one passes from particle probes to scalar waves. The time evolution can be defined uniquely and some general conditions for that are formulated. The Reissner-Nordstrom singularity allows for communication through the singularity and can be termed "beam s

Daniel Errandonea, Y. Meng, M. Somayazulu, D. Hausermann

We investigated the effects of uniaxial stress on the pressure-induced alpha-to-omega transition in pure titanium (Ti) by means of angle dispersive x-ray diffraction in a diamond-anvil cell. Experiments under four different pressure environments reveal that: (1) the onset of the transition depends on the pressure medium used, going from 4.9 GPa (no pressure

Serkan Hosten, Seth Sullivant

We show that the complexity of the Markov bases of multidimensional tables stabilizes eventually if a single table dimension is allowed to vary. In particular, if this table dimension is beyond a computable bound, the Markov bases consist of elements of Markov bases of smaller tables. We give an explicit formula for this bound in terms of Graver bases. We al

J. P. Pridham

By developing a theory of deformations over nilpotent Lie algebras, based on Schlessinger's deformation theory over Artinian rings, this paper investigates the pro-l-unipotent fundamental group of a variety X. If X is smooth and proper, defined over a finite field, then the Weil conjectures imply that this group is quadratically presented. If X is smooth

Katrin Wehrheim

We study bubbling phenomena of anti-self-dual instantons on $\H^2\times§$, where $§$ is a closed Riemann surface. The restriction of the instanton to each boundary slice $\{z\}\times§$, $z\in\pd\H^2$ is required to lie in a Lagrangian submanifold of the moduli space of flat connections over $§$ that arises from the restrictions to the boundary of flat connec

J. Kinnunen, M. Rodriguez, P. Torma

We consider atomic Fermi gases where Feshbach resonances can be used to continuously tune the system from weak to strong interaction regime, allowing to scan the whole BCS-BEC crossover. We show how a probing field transferring atoms out of the superfluid can be used to detect the onset of the superfluid transition in the high-$T_c$ and BCS regimes. The numb

Anders Björner, Irena Peeva, Jessica Sidman

We consider the vanishing ideal of an arrangement of linear subspaces in a vector space and investigate when this ideal can be generated by products of linear forms. We introduce a combinatorial construction (blocker duality) which yields such generators in cases with a lot of combinatorial structure, and we present the examples that motivated our work. We g

Yoonbai Kim, Dong Hyun Park

We consider a complex scalar field in (p+3)-dimensional bulk with a negative cosmological constant and study global vortices in two extra-dimensions. We reexamine carefully the coupled scalar and Einstein equations, and show that the boundary value of scalar amplitude at infinity of the extra-dimensions should be smaller than vacuum expectation value. The br

Andreas Gronlund, Kim Sneppen, Petter Minnhagen

Combinations of random and preferential growth for both on-growing and stationary networks are studied and a hierarchical topology is observed. Thus for real world scale-free networks which do not exhibit hierarchical features preferential growth is probably not the main ingredient in the growth process. An example of such real world networks includes the pr

J. Riess

We consider the Schrodinger time evolution of charged particles subject to a static substrate potential and to a homogeneous, macroscopic electric field (a magnetic field may also be present). We investigate the microscopic velocities and the resulting macroscopic current. We show that the microscopic velocities are in general non-linear with respect to the

Owen Madden, Simon F. Ross

We study the quotients of n+1-dimensional anti-de Sitter space by one-parameter subgroups of its isometry group SO(2,n) for general n. We classify the different quotients up to conjugation by O(2,n). We find that the majority of the classes exist for all n \geq 2. There are two special classes which appear in higher dimensions: one for n \geq 3 and one for n

Shin'ichi Nojiri, Sergei D. Odintsov, Akio Sugamoto

There exists a freedom in a class of four-dimensional electroweak theories proposed by Arkani-Hamed et al. relying on deconstruction and Coleman-Weinberg mechanism. The freedom comes from the winding modes of the link variable (Wilson operator) connecting non-nearest neighbours in the discrete fifth dimension. Using this freedom, dynamical breaking of SU(2)

Y. Z. Zhang, C. Q. Wu, H. Q. Lin

Density matrix renormalization group methods are used to investigate the quantum phase diagram of a one-dimensional half-filled ionic Hubbard model with bond-charge attraction, which can be mapped from the Su-Schrieffer-Heeger-type electron-phonon coupling at the antiadiabatic limit. A bond order wave (dimerized) phase which separates the band insulator from

Ryusuke Ikeda, Kiyokazu Myojin

It is found on the basis of the lowest Landau level approach for the Ginzburg-Landau model that, in bulk type II superconductors with strong line disorder directed {\it perpendicularly} to an applied field, the continuous vortex-glass transition is depressed to the low $T$ limit in the limit of weak {\it point} disorder. An anomalous resistive broadening in

Takeshi Fukuyama, Amon Ilakovac, Tatsuru Kikuchi, Stjepan Meljanac

We make an explicit formulation for the proton decay rate in the minimal renormalizable supersymmetric (SUSY) SO(10) model. In this model, the Higgs fields consist of ${\bf 10}$ and ${\bf \bar{126}}$ SO(10) representations in the Yukawa interactions with matter and of ${\bf 10}$, ${\bf \bar{126}}$, ${\bf 126}$, and ${\bf 210}$ representations in the Higgs po

Kunimasa Miyazaki, David R. Reichman, Ryoichi Yamamoto

We analyze the behavior of supercooled fluids under shear both theoretically and numerically. Theoretically, we generalize the mode-coupling theory of supercooled fluids to systems under stationary shear flow. Our starting point is the set of generalized fluctuating hydrodynamic equations with a convection term. A nonlinear integro-differential equation for

Francesca Alessandrini, Stefano Mancini, Paolo Tombesi

We investigate the possibility of characterizing two-party entanglement by measuring correlations of Stokes operators in polarized bright light beams. We adapt a general separability criterion to such operators. We then show that entanglement purification can only be singled out for a particular protocol.

Yu. P. Rybakov, T. F. Kamalov

Stochastic realization of the wave function in quantum mechanics, with the inclusion of soliton representation of extended particles, is discussed. The concept of Stochastic Qubits is used for quantum computing modeling.

Andrea R. Rossi, Matteo G. A. Paris

Reduction criteria for distillability is applied to general depolarized states and an explicit condition is found in terms of a characteristic polynomial of the density matrix. 3 $\times$ 3 bipartite systems are analyzed in some details.

Jan Soubusta, Antonin Cernoch, Jaromir Fiurasek, Miloslav Dusek

We present an optical implementation of two programmable quantum measurement devices. The first one serves for unambiguous discrimination of two nonorthogonal states of a qubit. The particular pair of states to be discriminated is specified by the quantum state of a program qubit. The second device can perform von Neumann measurements on a single qubit in an

John A. Sidles

A positive P-representation for the spin-j thermal density matrix is given in closed form. The representation is constructed by regarding the wave function as the internal state of a closed-loop control system. A continuous interferometric measurement process is proved to einselect coherent states, and feedback control is proved to be equivalent to a thermal

M. Hotta, M. Morikawa

The quantum Zeno paradox is fully resolved for purely indirect and incomplete measurements performed by the detectors outside the system. If the outside detectors are prepared to observe propagating signals of a decay event of an excited state in the core region, the survival probability of the state is not changed at all by the outside measurements, as long

Michael Faux, Donald Spector

We show that shape invariance appears when a quantum mechanical model is invariant under a centrally extended superalgebra endowed with an additional symmetry generator, which we dub the shift operator. The familiar mathematical and physical results of shape invariance then arise from the BPS structure associated with this shift operator. The shift operator

A. J. Scott

We investigate the average bipartite entanglement, over all possible divisions of a multipartite system, as a useful measure of multipartite entanglement. We expose a connection between such measures and quantum-error-correcting codes by deriving a formula relating the weight distribution of the code to the average entanglement of encoded states. Multipartit

Andrei Khrennikov, Yaroslav Volovich

We analyze statistical consequences of a conjecture that there exists a fundamental (indivisible) quant of time. We study particle dynamics with discrete time. We show that a quantum-like interference pattern could appear as a statistical effect for deterministic particles, i.e. particles that have trajectories and obey deterministic dynamical equations, if

Christopher Quince, Paul Higgs, Alan McKane

We use food webs generated by a model to investigate the effects of deleting species on other species in the web and on the web as a whole. The model incorporates a realistic population dynamics, adaptive foragers and other features which allow for the construction of model webs which resemble empirical food webs. A large number of simulations were carried o

M. D. Nielsen, J. R. Folkenberg, N. A. Mortensen, A. Bjarklev

We experimentally compare the optical bandwidth of a conventional single-mode fiber (SMF) with 3 different photonic crystal fibers (PCF) all optimized for visible applications. The spectral attenuation, single-turn bend loss, and mode-field diameters (MFD) are measured and the PCF is found to have a significantly larger bandwidth than the SMF for an identica

V. A. Rantsev-Kartinov

An analysis of databases of photographic images of ocean's surface, taken from various altitudes and for various types of rough ocean surface, revealed the presence of an ocean's skeletal structures (OSS), which exhibit a tendency toward self-similarity of structuring at various length scales (i.e., within various "generations"). The topology

Giovanni De Ninno, Duccio Fanelli

Local bifurcation control is a topic of fundamental importance in the field of nonlinear dynamical systems. We discuss an original example within the context of storage-ring free-electron laser physics by presenting a new model that enables analytical insight into the system dynamics. The transition between the stable and the unstable regimes, depending on t

E. L. Saldin, E. A. Schneidmiller, M. V. Yurkov

Simple formulas for optimization of VUV and X-ray SASE FELs are presented. The FEL gain length and the optimal beta-function are explicitly expressed in terms of the electron beam and undulator parameters. The FEL saturation length is estimated taking into account quantum diffusion in the undulator. Examples of the FEL optimization are given. Parameters of a

E. L. Saldin, E. A. Schneidmiller, M. V. Yurkov

We propose a technique for the production of attosecond X-ray pulses which is based on the use of X-ray SASE FEL combined with a femtosecond laser system. A few-cycle optical pulse from a Ti:sapphire laser interacts with the electron beam in a two-period undulator resonant to 800 nm wavelength and produces energy modulation within a slice of the electron bun

A. A. Mikhailov

The current state of this problem has briefly been considered. The hypothesis on the formation of the ozone hole due to the action of some molecules emitted by the rockets has been suggested.

L. Lilje, C. Antoine, C. Benvenuti, D. Bloess

The proposed linear electron-positron collider TESLA is based on 1.3 GHz superconducting niobium cavities for particle acceleration. For a centre-of-mass energy of 500 GeV, an accelerating field of 23.4 MV/m is required which is reliably achieved with a niobium surface preparation by chemical etching. An upgrade of the collider to 800 GeV requires an improve

Eric J. Lerner

Fusion with p11B has many advantages, including the almost complete lack of radioactivity and the possibility of direct conversion of charged particle energy to electricity, without expensive steam turbines and generators. But two major challenges must be overcome to achieve this goal: obtaining average ion energies well above 100keV and minimizing losses by

Peter Moller, Arnold J. Sierk, Akira Iwamoto

We present fission-barrier-height calculations for nuclei throught the Periodic Table based on a realistic macroscopic-microscopic model. Compared to other calculations: (1) we use a deformation space of sufficiently high dimension, sampled densely enough to describe the relevant topography of the fission potential, (2) we unambiguously find the physically r

Kei Iida, Kazuhiro Oyamatsu

We examine whether or not the surface tension acts to increase the nucleon density in the nuclear interior within a compressible liquid-drop model. We find that it depends on the density dependence of the surface tension, which may in turn be deduced from the neutron skin thickness of stable nuclei.

A. V. Prozorkevich, S. A. Smolyansky, V. V. Skokov, E. E. Zabrodin

The vacuum parton creation in quickly varying external fields is studied at the time scale of order 1 fm/$c$ typical for the quark-gluon plasma formation and thermalization. To describe the pre-equilibrium evolution of the system the transport kinetic equation is employed. It is shown that the dynamics of production process at times comparable with particle

K. Amos, L. Canton, G. Pisent, J. P. Svenne

Recently, we published a paper (Nucl. Phys. A 728 (2003) 65; see nucl-th/0306068) presenting a new calculational method for nucleon-nucleus elastic scattering at low energies. That method is particularly appropriate for analyses in the region of narrow resonances. The method is based upon the sturmian representation of the S-matrix, and allows inclusion of n

A. Schiller, A. Voinov, E. Algin, J. A. Becker

Two-step-cascade spectra in 172-Yb have been measured after thermal neutron capture. They are compared to calculations based on experimental values of the level density and radiative strength function (RSF) obtained from the 173-Yb(3-He,alpha gamma)172-Yb reaction. The multipolarity of a 6.5(15) mu_N^2 resonance at E_gamma=3.3(1) MeV in the RSF is determined

Mercedes Lopez Noriega

We present preliminary results from a two-pion intensity interferometry analysis from Au+Au collisions at sqrt{s_{NN}}=200 GeV measured in the STAR detector at RHIC. The dependence of the apparent pion source on multiplicity and transverse momentum are discussed and compared with preliminary results from d+Au and p+p collisions at the same beam energy.

Pawan Kumar Netrakanti, Bedangadas Mohanty

We show that the centrality dependence of charged particle and photon pseudorapidity density at midrapidity along with the transverse energy pseudorapidity density at SPS and RHIC energies scales with the number of participating constituent quarks. The number of charged particles and transverse energy per participant constituent quark is found to increase wi

Song-Ju Kim, Ken Umeno, Akio Hasegawa

It is well known that the NIST statistical test suite was used for the evaluation of AES candidate algorithms. We have found that the test setting of Discrete Fourier Transform test and Lempel-Ziv test of this test suite are wrong. We give four corrections of mistakes in the test settings. This suggests that re-evaluation of the test results should be needed

Russell K. Standish

The concept of neutral evolutionary networks being a significant factor in evolutionary dynamics was first proposed by Huynen {\em et al.} about 7 years ago. In one sense, the principle is easy to state -- because most mutations to an organism are deleterious, one would expect that neutral mutations that don't affect the phenotype will have disproportion

Andres Moreira, Nino Boccara, Eric Goles

Number-conserving (or {\em conservative}) cellular automata have been used in several contexts, in particular traffic models, where it is natural to think about them as systems of interacting particles. In this article we consider several issues concerning one-dimensional cellular automata which are conservative, monotone (specially ``non-increasing'&#39

Frederic Helein, Joseph Kouneiher

This papers is concerned with multisymplectic formalisms which are the frameworks for Hamiltonian theories for fields theory. Our main purpose is to study the observable $(n-1)$-forms which allows one to construct observable functionals on the set of solutions of the Hamilton equations by integration. We develop here two different points of view: generalizin

A. Cervellino, S. Ciccariello

The algebraic approach to the phase problem for the case of X-ray scattering from an ideal crystal is extended to the case of the neutron scattering, overcoming the difficulty related to the non-positivity of the scattering density. In this way, it is proven that the atomicity is the crucial assumption while the positiveness of the scattering density only af

Marius Mantoiu, Radu Purice

In the presence of a variable magnetic field, the Weyl pseudodifferential calculus must be modified. The usual modification, based on ``the minimal coupling principle'' at the level of the classical symbols, does not lead to gauge invariant formulae if the magnetic field is not constant. We present a gauge covariant quantization, relying on the magne

Frédéric Latour

In this paper, we classify the irreducible representations of the trigonometric Cherednik algebras of rank 1 in characteristic p > 0. There are two cases. One is the "quantum" case, where "Planck's constant" is nonzero and generic irreducible representations have dimension 2p. In this case, smaller representations exist if and only if the

Alessandro Giacomini

We perform an analysis of the size effect for quasistatic growth of fractures in linearly isotropic elastic bodies under antiplanar shear. In the framework of the variational model proposed by G.A. Francfort and J.-J. Marigo in [14], we prove that if the size of the body tends to infinity, and even if the surface energy is of cohesive form, under suitable bo

Alessandro Giacomini, Marcello Ponsiglione

We propose a time-space discretization of a general notion of quasistatic growth of brittle fractures in elastic bodies proposed in [13] by G. Dal Maso, G.A. Francfort, and R. Toader, which takes into account body forces and surface loads. We employ adaptive triangulations and prove convergence results for the total, elastic and surface energies. In the case

Y. Chen, J. C. Griffin, M. E. H. Ismail

We show how polynomial mappings of degree k from a union of disjoint intervals onto [-1,1] generate a countable number of special cases of a certain generalization of the Chebyshev Polynomials. We also derive a new expression for these generalized Chebyshev Polynomials for any number of disjoint intervals from which the coefficients of x^n can be found expli

Jorge Cortes, Alexandre M. Vinogradov

This paper considers systems subject to nonholonomic constraints which are not uniform on the whole configuration manifold. When the constraints change, the system undergoes a transition in order to comply with the new imposed conditions. Building on previous work on the Hamiltonian theory of impact, we tackle the problem of mathematically describing the cla

Katrin Wehrheim

The main purpose of this paper is to give a general regularity result for Cauchy-Riemann equations in complex Banach spaces with totally real boundary conditions. The usual elliptic $L^p$-regularity results hold true under one crucial assumption: The totally real submanifold has to be modelled on an $L^p$-space or a closed subspace thereof. Secondly, we desc

Mireille Martin-Deschamps

The postulation of Arithmetically Cohen-Macaulay (ACM) subschemes of the projective space ${\mathbb P}^N_k$ is well-known in the case of codimension 2. There are many different ways of recording this numerical information : numerical character of Gruson/Peskine, $h$-vector, postulation character of Martin-Deschamps/Perrin... The first aim of this paper is to

Willem Veys

We provide a gentle introduction to arc spaces, motivic integration and stringy invariants. We explain the basic concepts and first results, including the p-adic number theoretic pre-history, and we provide concrete examples. The text is a slightly adapted version of the 'extended abstract' of the author's talks at the 12th MSJ-IRI "Singulari

Henri Anciaux, Ildefonso Castro, Pascal Romon

We study Lagrangian submanifolds foliated by (n-1)-spheres in R^2n for n>2. We give a parametrization valid for such submanifolds, and refine that description when the submanifold is special Lagrangian, self-similar or Hamiltonian stationary. In all these cases, the submanifold is centered, i.e. invariant under the action of SO(n). It suffices then to solve

Simon Kristensen

We outline a proof of an analogue of Khintchine's Theorem in R^2, where the ordinary height is replaced by a distance function satisfying an irrationality condition as well as certain decay and symmetry conditions.

E. Lytvynov

We identify the representation of the square of white noise obtained by L. Accardi, U. Franz and M. Skeide in [Comm. Math. Phys. 228 (2002), 123--150] with the Jacobi field of a Lévy process of Meixner's type.

Teijo Arponen, Ben Leimkuhler

(Anti)-/ferromagnetic Heisenberg spin models arise from discretization of Landau-Lifshitz models in micromagnetic modelling. In many applications it is essential to study the behavior of the system at a fixed temperature. A formulation for thermostatted spin dynamics was given by Bulgac and Kusnetsov which incorporates a complicated nonlinear dissipation/dri

Sever Silvestru Dragomir

A general divergence measure for monotonic functions is introduced. Its connections with the f-divergence for convex functions are explored. The main properties are pointed out.

Chien-Hao Liu, Kefeng Liu, Shing-Tung Yau

In [L-L-Y1, III: Sec. 5.4] on mirror principle, a method was developed to compute the integral $\int_{X}τ^{\ast}e^{H\cdot t}\cap {\mathbf 1}_d$ for a flag manifold $X=\Fl_{r_1, ..., r_I}({\Bbb C}^n)$ via an extended mirror principle diagram. This method turns the required localization computation on the augmented moduli stack $\bar{\cal M}_{0,0}(\CP^1\times

Michael T. Anderson

This work proves certain general orbifold compactness results for spaces of Riemannian metrics, generalizing earlier results along these lines for Einstein metrics or metrics with bounded Ricci curvature. This is then applied to prove such compactness for spaces of Bach-flat (for example half-conformally flat) metrics on 4-manifolds, and related results for

Daniel Rogalski

We study some properties of graded idealizer rings with an emphasis on applications to the theory of noncommutative projective geometry. In particular we give examples of rings for which the $χ$-conditions of Artin and Zhang and the strong noetherian property have very different behavior on the left and right sides.

Kiran S. Kedlaya

We prove that every geometrically reduced projective variety of pure dimension n over a field of positive characteristic admits a morphism to projective n-space, etale away from the hyperplane H at infinity, which maps a chosen divisor into H and some chosen smooth points not on the divisor to points not in H. This improves our earlier result in math.AG/0207

Katrin Wehrheim

We study a nonlocal boundary value problem for anti-self-dual instantons on 4-manifolds with a space-time splitting of the boundary. The model case is $\R \times Y$, where $Y$ is a compact oriented 3-manifold with boundary $Σ$. The restriction of the instanton to each time slice ${t}\timesΣ$ is required to lie in a fixed (singular) Lagrangian submanifold of

John R. Klauder

Affine quantum gravity involves (i) affine commutation relations to ensure metric positivity, (ii) a regularized projection operator procedure to accomodate first- and second-class quantum constraints, and (iii) a hard-core interpretation of nonlinear interactions to understand and potentially overcome nonrenormalizability. In this program, some of the less

Xavier Calmet

We describe some recent progress in our understanding of Yang-Mills theories formulated on noncommutative spaces and in particular how to formulate the standard model on such spaces.

P. Gaete, E. I. Guendelman

It has been noticed that confinement effects can be described by the addition of a $ \sqrt {- F_{μν}^a F^{aμν}} $ term in the Lagrangian density. We now study the combined effect of such "confinement term" and that of a mass term. The surprising result is that the interplay between these two terms gives rise to a Coulomb interaction. Our picture has

Dan Solomon

Dirac's hole theory and quantum field theory are generally thought to be equivalent. In fact field theory can be derived from hole theory through the process of second quantization. However, it can be shown that problems worked in both theories yield different results. The reason for the difference between the two theories will be examined and the effect

José Figueroa-O'Farrill, Joan Simón

This paper contains a classification of smooth Kaluza--Klein reductions (by one-parameter subgroups) of the maximally supersymmetric anti de Sitter backgrounds of supergravity theories. We present a classification of one-parameter subgroups of isometries of anti de Sitter spaces, discuss the causal properties of their orbits on these manifolds, and discuss t

P. Nicolini

A scalar field in (2+1) dimensional Minkowski space-time is considered. Postulating noncommutative spatial coordinates, one is able to determine the (UV finite) vacuum expectation value of the quantum field energy momentum tensor. Calculation for the (3+1) case has been performed considering only two noncommutative coordinates. The results lead to a vacuum e