January 2005 arXiv papers — page 12

F. Raissi

Coulomb repulsion between two moving electrons loses its spherical symmetry due to relativistic effects. In presence of a uniform positive ion background this asymmetry uncovers an angular dependent attraction potential in the direction of motion. The quantum mechanical response to such an attraction potential is obtained through perturbation. It is shown th

R. Karmakar, S. S. Manna

In a sandpile model addition of a hole is defined as the removal of a grain from the sandpile. We show that hole avalanches can be defined very similar to particle avalanches. A combined particle-hole sandpile model is then defined where particle avalanches are created with probability $p$ and hole avalanches are created with the probability $1-p$. It is obs

German Ka"lbermann

Nonperturbative, oscillatory, winding number one solutions of the Sine-Gordon equation are presented and studied numerically. We call these nonperturbative shape modes {\sl wobble} solitons. Perturbed Sine-Gordon kinks are found to decay to {\sl wobble} solitons.

Lisa A. Crause, Warrick A. Lawson, John W. Menzies, Fred Marang

Following its 2002 February eruption, V838 Mon developed a light echo that continues to expand and evolve as light from the outburst scatters off progressively more distant circumstellar and/or interstellar material. Multi-filter images of the light echo, obtained with the South African Astronomical Observatory (SAAO) 1.0-m telescope between 2002 May and 200

Christina McGough, Geoffrey C. Clayton, Karl D. Gordon, Michael J. Wolff

We critique the method of constructing extinction curves of lensing galaxies using multiply imaged QSOs. If one of the two QSO images is lightly reddened or if the dust along both sightlines has the same properties then the method works well and produces an extinction curve for the lensing galaxy. These cases are likely rare and hard to confirm. However, if

B. V. Vasiliev

All fundamental physical principles are confirmed by numerous experiments and practical certainty and have unambiguous interpretation. But physics of stars is based on few measured effects only. It gives some freedom for figments of the imagination. The goal of this paper is to compare two alternative astrophysical models with measurement data.

G. Shaw, G. J. Ferland, N. P. Abel, P. C. Stancil

Much of the baryonic matter in the Universe is in the form of H2 which includes most of the gas in galactic and extragalactic interstellar clouds. Molecular hydrogen plays a significant role in establishing the thermal balance in many astrophysical environments and can be important as a spectral diagnostic of the gas. Modeling and interpretation of observati

Adam Burrows

Astronomy is at times a science of unexpected discovery. When it is, and if we are lucky, new intellectual territories emerge to challenge our views of the cosmos. The recent indirect detections using high-precision Doppler spectroscopy of now more than one hundred giant planets orbiting more than one hundred nearby stars is an example of such rare serendipi

M. Dietrich, D. M. Crenshaw, S. B. Kraemer

We present optical spectra and emission-line ratios of 12 Narrow-Line Seyfert 1 (NLS1) galaxies that we observed to study the ionizing EUV continuum. A common feature in the EUV continuum of active galactic nuclei is the big blue bump (BBB), generally associated with thermal accretion disk emission. While Galactic absorption prevents direct access to the EUV

J. S. Bagla, Suryadeep Ray

N-Body simulations are a very important tool in the study of formation of large scale structures. Much of the progress in understanding the physics of high redshift universe and comparison with observations would not have been possible without N-Body simulations. Given the importance of this tool, it is essential to understand its limitations as ignoring the

A. Dieball, C. Knigge, D. R. Zurek, M. M. Shara

We present a reanalysis of far-ultraviolet (FUV) observations of the globular cluster NGC 2808 obtained with the Hubble Space Telescope. These data were first analyzed by Brown and coworkers, with an emphasis on the bright, blue horizontal branch (HB) stars in this cluster. Here, our focus is on the population of fainter FUV sources, which include white dwar

Matthias Beck, Frank Sottile

We give new proofs of three theorems of Stanley on generating functions for the integer points in rational cones. The first, Stanley's reciprocity theorem, relates the rational generating functions for the integer points in a cone K and for those in its interior. The second, Stanley's Positivity theorem asserts that the generating function of the Ehr

J. Graetz, Y. Lee, J. J. Reilly, S. Park

The thermodynamics and structural properties of the hexahydride alanates (M2M'AlH6) with the elpasolite structure have been investigated. A series of mixed alkali alanates (Na2LiAlH6, K2LiAlH6 and K2NaAlH6) were synthesized and found to reversibly absorb and desorb hydrogen without the need for a catalyst. Pressure-composition isotherms were measured to

Adrienne M. Juett

We show that the observed relationship between the fraction of low-mass X-ray binaries (LMXBs) found in globular clusters (GCs) and the GC-specific frequency for early-type galaxies is consistent with an LMXB formation model in which the field population of LMXBs is formed in situ via primordial binary formation. The suggestion that a significant fraction of

Erhan Bayraktar, H. Vincent Poor

Stochastic differential games are considered in a non-Markovian setting. Typically, in stochastic differential games the modulating process of the diffusion equation describing the state flow is taken to be Markovian. Then Nash equilibria or other types of solution such as Pareto equilibria are constructed using Hamilton-Jacobi-Bellman (HJB) equations. But i

M. T. Yamashita, T. Frederico, M. S. Hussein

We exploit the possibility of new configurations in three-body halo nuclei - Samba type - (the neutron-core form a bound system) as a doorway to Borromean systems. The nuclei $^{12}$Be, $^{15}$B, $^{23}$N and $^{27}$F are of such nature, in particular $^{23}$N with a half-life of 37.7 s and a halo radius of 6.07 fm is an excellent example of Samba-halo confi

Adrienne M. Juett, Deepto Chakrabarty

We present high-resolution spectroscopy of the neutron star/low-mass X-ray binaries (LMXBs) 4U 1850-087 and 4U 0513-40 as part of our continuing study of known and candidate ultracompact binaries. The LMXB 4U 1850-087 is one of four systems in which we had previously inferred an unusual Ne/O ratio in the absorption along the line of sight, most likely from m

Ko Honda, William H. Kazez, Gordana Matic

We give a necessary and sufficient condition for the addition of a collection of disjoint bypasses to a convex surface to be universally tight -- namely the nonexistence of a polygonal region which we call a virtual pinwheel.

U. Gran, J. Gutowski, G. Papadopoulos

We investigate the Killing spinor equations of IIB supergravity for one Killing spinor. We show that there are three types of orbits of Spin(9,1) in the space of Weyl spinors which give rise to Killing spinors with stability subgroups $Spin(7)\ltimes \bR^8$, $SU(4)\ltimes \bR^8$ and $G_2$. We solve the Killing spinor equations for the $Spin(7)\ltimes \bR^8$

M. Z. Hasan, D. Qian, Y. Li, A. V. Fedorov

Recently discovered class of cobaltate superconductors (Na0.3CoO2.nH2O) is a novel realization of interacting quantum electron systems in a triangular network with low-energy degrees of freedom. We employ angle-resolved photoemission spectroscopy to uncover the nature of microscopic electron motion in the parent superconductors for the first time. Results re

Yann Le Coq, Jocelyn A. Retter, Simon Richard, Alain Aspect

We analyze the advantages of using ultra-cold coherent sources of atoms for matter-wave interferometry in space. We present a proof-of-principle experiment that is based on an analysis of the results previously published in [Richard et al., Phys. Rev. Lett., 91, 010405 (2003)] from which we extract the ratio h/m for 87Rb. This measurement shows that a limita

P. A. Sturrock, D. O. Caldwell, J. D. Scargle, M. S. Wheatland

There have been conflicting claims as to whether or not power-spectrum analysis of the Super-Kamiokande solar neutrino data yields evidence of variability. Comparison of these claims is complicated by the fact that the relevant articles may use different datasets, different methods of analysis, and different procedures for significance estimation. The purpos

Remigiusz Augusiak

A recently formulated version of the eigenchannel method [R. Szmytkowski, Ann. Phys. (N.Y.) {\bf 311}, 503 (2004)] is applied to quantum scattering of Schrödinger particles from non-local separable potentials. Eigenchannel vectors and negative cotangents of eigenphase-shifts are introduced as eigensolutions to some weighted matrix spectral problem, without a

Brian C. Tiburzi

The chiral Lagrangian for the Symanzik action through O(a^2) for baryons is obtained. We consider two flavor unquenched and partially quenched lattice theories, allowing for mixed actions in the latter. As an application, we calculate masses to O(a^2) for the nucleons and deltas, and investigate the corrections due to the violation of O(4) rotational invaria

John Roe

We describe a construction (the `warped cone construction') which produces examples of coarse spaces with large groups of translations. We show that by this construction we can obtain many examples of coarse spaces which do not have property A or which are not uniformly embeddable into Hilbert space.

Harold Steinacker

Non-commutative Euclidean scalar field theory is shown to have an eigenvalue sector which is dominated by a well-defined eigenvalue density, and can be described by a matrix model. This is established using regularizations of R^{2n}_θvia fuzzy spaces for the free and weakly coupled case, and extends naturally to the non-perturbative domain. It allows to stud

Lev Deych

Semiclassical equations of lasing dynamics are re-derived for a lasing medium in a cavity with a spatially non-uniform dielectric constant. It is shown that the non-uniformity causes a radiative coupling between modes of the empty cavity. This coupling results in a renormalization of self- and cross-saturation coefficients, which acquire a non-trivial depend

Donu Arapura

Given two smooth projective varieties X and Y over a field, we say that X motivates Y if the (suitably defined) motive of Y is contained in the category generated from X by taking sums, summands and products. This notion has appeared implicitly in many places, but it seems useful to make it explicit. Some techniques are given for checking this condition, but

Bin Chen, Bo Sun

In this note, we investigate the homogeneous radial dynamics of (Dp, NS5)-systems without and with one compactified transverse direction, in the framework of DBI effective action. During the homogeneous evolution, the electric field on the D-brane is always conserved and the radial motion could be reduced to an one-dimension dynamical system with an effectiv

UTfit Collaboration, M. Bona, M. Ciuchini, E. Franco

Using the latest determinations of several theoretical and experimental parameters, we update the Unitarity Triangle analysis in the Standard Model. The basic experimental constraints come from the measurements of |V_ub/V_cb|, Delta M_d, the lower limit on Delta M_s, epsilon_k, and the measurement of the phase of the B_d - anti B_d mixing amplitude through t

J. A. Vaccaro, F. Anselmi, H. M. Wiseman, K. Jacobs

Superselection rules (SSRs) limit the mechanical and quantum processing resources represented by quantum states. However SSRs can be violated using reference systems to break the underlying symmetry. We show that there is a duality between the ability of a system to do mechanical work and to act as a reference system. Further, for a bipartite system in a glo

K. Fukuda, A. N. Jensen, N. Lauritzen, R. Thomas

The Groebner walk is an algorithm for conversion between Groebner bases for different term orders. It is based on the polyhedral geometry of the Groebner fan and involves tracking a line between cones representing the initial and target term order. An important parameter is explicit numerical perturbation of this line. This usually involves both time and spa

J. Bouttier, P. Di Francesco, E. Guitter

We present a purely combinatorial solution of the problem of enumerating planar bicubic maps with hard particles. This is done by use of a bijection with a particular class of blossom trees with particles, obtained by an appropriate cutting of the maps. Although these trees have no simple local characterization, we prove that their enumeration may be perform

Mark Heinz

We present measurements of the transverse momentum spectra for $\mathrm{K^{0}_{S}}$, $Λ$, $Ξ$ and their antiparticles in p+p collisions at $\sqrt{s}=200 GeV$. The extracted mid-rapidity yields and $<\mathrm{p_{T}}>$ are in agreement with previous $p+\bar{p}$ experiments while they have smaller statistical errors. We compare the measured spectra for $\mathrm{

Marco Chiaberge, Alessandro Capetti, F. Duccio Macchetto

We study a complete and distance-limited sample of 25 LINERs, 21 of which have been imaged with the Hubble Space Telescope. In nine objects we detect an unresolved nucleus. In order to study their physical properties, we compare the radio and optical properties of the nuclei of LINERs with those of other samples of local AGNs, namely Seyfert galaxies and low

V. I. Galkin, A. M. Anokhina, E. Konishi, A. Misaki

In the previous paper, we construct the angular distribution functions for muon and electron as well as their relative fluctuation functions to find suitable discrimination procedure between muon and electron in Superkamiokande experiment. In the present paper, we are able to discriminate muons from electrons in Fully Contained Events with a probability of e

D. Xu, Z. G. Dai, E. W. Liang

Three different methods of measuring cosmology with gamma-ray bursts (GRBs) have been proposed since a relation between the $γ$-ray energy $E_γ $ of a GRB jet and the peak energy $E_p$ of the $νF_ν$ spectrum in the burst frame was reported by Ghirlanda and coauthors. In Method I, to calculate the probability for a favored cosmology, only the contribution of

I. M. Dremin

QCD equations for the generating functions are applied to separate soft and hard jets in $e^+e^-$-processes of multiparticle production. The dependence of average multiplicities and higher moments of multiplicity distributions of particles created in a &#34;newly born&#34; soft subjets on the share of energy devoted to them is calculated in fixed coupling gl

Sergei Sakovich

The original Miura transformation, considered as a nonlinear potential transformation, is applicable to a continual class of evolution equations, not only to discrete integrable equations and their hierarchies. The same continual class of evolution equations appears from a different problem, namely, from the gauge-invariant description of a zero-curvature re

M. Bartolozzi, S. Drozdz, D. B. Leinweber, J. Speth

The presence of log-periodic structures before and after stock market crashes is considered to be an imprint of an intrinsic discrete scale invariance (DSI) in this complex system. The fractal framework of the theory leaves open the possibility of observing self-similar log-periodic structures at different time scales. In the present work we analyze the dail

N. P. Basse

We will in this paper report on suggestive similarities between density fluctuation power versus wavenumber on small (mm) and large (Mpc) scales. The small scale measurements were made in fusion plasmas and compared to predictions from classical fluid turbulence theory. The data is consistent with the dissipative range of 2D turbulence. Alternatively, the re

S. M. Kuzenko, S. A. McCarthy

We analyze the component structure of models for 4D N = 1 supersymmetric nonlinear electrodynamics that enjoy invariance under continuous duality rotations. The N = 1 supersymmetric Born-Infeld action is a member of this family. Such dynamical systems have a more complicated structure, especially in the presence of supergravity, as compared with well-studied

M. Shifman, A. Vainshtein

We present arguments regarding diquarks possible role in low-energy hadron phenomenology that escaped theorists&#39; attention so far. Good diquarks, i.e. the $0^{+}$ states of two quarks, are argued to have a two-component structure with one of the components peaking at distances several times shorter than a typical hadron size (a short-range core). This ca

Sotaro Sasaki, Hiroaki Ikeda, Kosaku Yamada

We investigate the mass enhancement factor and the superconducting transition temperature in the d-p model for the high-$\Tc$ cuprates. We solve the Éliashberg equation using the third-order perturbation theory with respect to the on-site Coulomb repulsion $U$. We find that when the energy difference between d-level and p-level is large, the mass enhancement

Eric Braaten, Dongqing Zhang

Break-up and recombination processes for loosely-bound molecules composed of atoms with a large scattering length $a$ necessarily involve interactions that are nonperturbative in the exact 2-body interaction. If these processes involve atoms with relative momenta much larger than $\hbar/|a|$, the leading contributions to their rates can be separated into sho

R. L. Jaffe, A. Scardicchio

We study the Casimir force on a single surface immersed in an inhomogeneous medium. Specifically we study the vacuum fluctuations of a scalar field with a spatially varying squared mass, $m^{2}+λΔ(x-a)+V(x)$, where $V$ is a smooth potential and $Δ(x)$ is a unit-area function sharply peaked around $x=0$. $Δ(x-a)$ represents a semi-penetrable thin plate placed

Jae-Seung Lee, A. K. Khitrin

It is experimentally demonstrated that an arbitrary quantum state of a single spin 1/2: a|u> + b|d> can be converted into a superposition of the two ferromagnetic states of a spin cluster: a|uu...uu> + b|dd...dd>. The physical system is a cluster of seven dipolar-coupled nuclear spins of single-labeled 13C-benzene molecules in a liquid-crystalline matrix. In

Jae Weon Lee, Dima L. Shepelyansky

Using the methods of quantum trajectories we investigate the effects of dissipative decoherence in a quantum computer algorithm simulating dynamics in various regimes of quantum chaos including dynamical localization, quantum ergodic regime and quasi-integrable motion. As an example we use the quantum sawtooth algorithm which can be implemented in a polynomi

J. J. Halliwell

This is an informal introduction to the ideas of decoherence and emergent classicality, including a simple account of the decoherent histories approach to quantum theory. It is aimed at undergraduates with a basic appreciation of quantum theory. The emphasis is on simple physical ideas and pictures.

Ulrich D. Jentschura, Joerg Evers, Christoph H. Keitel

This paper is concerned with two rather basic phenomena: the incoherent fluorescence spectrum of an atom driven by an intense laser field and the coupling of the atom to the (empty) modes of the radiation field. The sum of the many-photon processes gives rise to the inelastic part of the atomic fluorescence, which, for a two-level system, has a well-known ch

Zhe Sun, XiaoGuang Wang, AnZi Hu, You-Quan Li

We study entanglement in dimerized Heisenberg systems. In particular, we give exact results of ground-state pairwise entanglement for the four-qubit model by identifying a Z_2 symmetry. Although the entanglements cannot identify the critical point of the system, the mean entanglement of nearest-neighbor qubits really does, namely, it reaches a maximum at the

Tzu-Chieh Wei, Joseph B. Altepeter, David Branning, Paul M. Goldbart

Two methods for creating arbitrary two-photon polarization pure states are introduced. Based on these, four schemes for creating two-photon polarization mixed states are proposed and analyzed. The first two schemes can synthesize completely arbitrary two-qubit mixed states, i.e., control all 15 free parameters: Scheme I requires several sets of crystals, whi

J. J. Garcia-Ripoll, P. Zoller, J. I. Cirac

In this paper we develop a unified framework to study the coherent control of trapped ions subject to state-dependent forces. Taking different limits in our theory, we can reproduce two different designs of a two-qubit quantum gate --the pushing gate [1] and the fast gates based on laser pulses from Ref. [2]--, and propose a new design based on continuous la

R. A. Cornelussen, R. J. C. Spreeuw, H. B. van Linden van den Heuvell

We investigate the question whether Michelson type interferometry is possible if the role of the beam splitter is played by a spontaneous process. This question arises from an inspection of trajectories of atoms bouncing inelastically from an evanescent-wave (EW) mirror. Each final velocity can be reached via two possible paths, with a {\it spontaneous} Rama

K. Z. Nanjo, J. B. Rundle, J. R. Holliday, D. L. Turcotte

Pattern informatics (PI) technique can be used to detect precursory seismic activation or quiescence and make earthquake forecast. Here we apply the PI method for optimal forecasting of large earthquakes in Japan, using the data catalogue maintained by the Japan Meteorological Agency. The PI method is tested to forecast large (magnitude m >= 5) earthquakes f

Yaroslav V. Kartashov, Victor A. Vysloukh, Lluis Torner

We study optical solitons in chirped periodic optical lattices whose amplitude or frequency changes in the transverse direction. We discover that soliton propagation in such lattices can be accompanied by the progressive self-bending of the soliton trajectory, and we show that the soliton bending rate and output position can be controlled by varying the latt

P. A. Varotsos, N. V. Sarlis, E. S. Skordas, M. S. Lazaridou

Complexity measures are introduced, that quantify the change of the natural entropy fluctuations at different length scales in time-series emitted from systems operating far from equilibrium. They identify impending sudden cardiac death (SD) by analyzing fifteen minutes electrocardiograms, and comparing to those of truly healthy humans (H). These measures se

P. A. Varotsos, N. V. Sarlis, E. S. Skordas, M. S. Lazaridou

A surrogate data analysis is presented, which is based on the fluctuations of the ``entropy&#39;&#39; $S$ defined in the natural time-domain [Phys. Rev. E {\bf 68}, 031106, 2003]. This entropy is not a static one as, for example, the Shannon entropy. The analysis is applied to three types of time-series, i.e., seismic electric signals, ``artificial&#39;&#39;

K. Staliunas, M. Tlidi

We consider a nonlinear optical system in general, and a broad aperture laser in particular in a resonator where the diffraction coefficients are of opposite signs along two transverse directions. The system is described by the hyperbolic Maxwell-Bloch equations, where the spatial coupling is provided by the DAlambert operator rather than by the Laplace oper

K. Staliunas, R. Herrero

We show that diffraction of electromagnetic radiation (in particular of a visible light) can disappear in propagation through materials with periodically in space modulated refraction index, i.e. photonic crystals. In this way the light beams of arbitrary width can propagate without diffractive broadening and, equivalently, arbitrary light patterns can propa

Bertrand Desplanques

Noticing that the point-form approach referred to in many recent works implies physics described on hyperplanes, an approach inspired from Dirac&#39;s one, which involves a hyperboloid surface, is presented. A few features pertinent to this new approach are emphasized. Consequences as for the calculation of form factors are discussed.

F. Ferro, A. Lavagno, P. Quarati

By minimizing free energy density, we show that the stellar core of a hydrogen burning star is not in a global thermodynamical equilibrium unless density, temperature, mass and composition assume given values. The core (as the solar interior) may be viewed more appropriately as a metastable state with very long lifetime. Slightly non-extensive distribution f

E. Voutier

This paper presents a selected review of the (e,e&#39;p) experimental program recently completed at the Jefferson Laboratory in the domain of high momentum transfer and high recoil momentum. Particular emphasis is put on the current understanding of the reaction mechanisms and of the large final state interaction effects. Their consequences on the study of t

E. J. Beise

The parity violation programs at MIT-Bates, Jefferson Lab and Mainz are presently focused on developing a better understanding of the sea-quark contributions to the vector matrix elements of nucleon structure. The success of these programs will allow precise semi-leptonic tests of the Standard Model such as that planned by the QWeak collaboration. In order t

A. Facchini, S. Bastianoni, N. Marchettini, M. Rustici

Chaos, oscillations, instabilities, intermittency represent only some nonlinear examples apparent in natural world. These phenomena appear in any field of study, and advances in complex and nonlinear dynamic techniques bring about opportunities to better understand animal signals. In this work we suggest an analysis method based on the characterization of th

Zhiyong Xu, Yaroslav V. Kartashov, Lluis Torner

We address the propagation of solitons in reconfigurable two-dimensional networks induced optically by arrays of nondiffracting Bessel beams in Kerr-type nonlinear media. We show that broad soliton beams can move across networks having different topologies almost without radiation losses, opening new prospects for all-optical soliton manipulation. We also di

Samer Ashhab

In many Lagrangian field theories one has a Poisson bracket defined on the space of local functionals. We find necessary and sufficient conditions for a transformation on the space of local functionals to be canonical in three different cases. These three cases depend on the specific dimensions of the vector bundle of the theory and the associated Hamiltonia

A. P. Yefremov

The review of modern study of algebraic, geometric and differential properties of quaternionic (Q) numbers with their applications. Traditional and &#34;tensor&#34; formulation of Q-units with their possible representations are discussed and groups of Q-units transformations leaving Q-multiplication rule form-invariant are determined. A series of mathematica

Cesar R. de Oliveira, Roberto A. Prado

An 1D tight-binding version of the Dirac equation is considered; after checking that it recovers the usual discrete Schr?odinger equation in the nonrelativistic limit, it is found that for two-valued Bernoulli potentials the zero mass case presents absence of dynamical localization for specific values of the energy, albeit it has no continuous spectrum. For

Jean-Marc Bouclet, Francois Germinet, Abel Klein, Jeffrey H. Schenker

We justify the linear response theory for an ergodic Schroedinger operator with magnetic field within the non-interacting particle approximation, and derive a Kubo formula for the electric conductivity tensor. To achieve that, we construct suitable normed spaces of measurable covariant operators where the Liouville equation can be solved uniquely. If the Fer

Michael Joellenbeck

We study the multigraded Poincaré-Betti series of $A=S/\aaf$, where $S$ is the ring of polynomials in $n$ indeterminates divided by the monomial ideal $\aaf$. There is a conjecture about the multigraded Poincaré-Betti series by Charalambous and Reeves which they proved in the case, where the Taylor resolution is minimal. We introduce a conjecture about the m

Jane Gilman, Linda Keen

For two generator free Fuchsian groups, the quotient three manifold is a genus two solid handlebody and its boundary is a hyperelliptic Riemann surface. The convex core is also a hyperelliptic Riemann surface. We find the Weierstrass points of both of these surfaces. We then generalize the notion of a hyperelliptic Riemann surface to a ``hyperelliptic&#39;&#

Mark Shimozono

In the large rank limit, for any nonexceptional affine algebra, the graded branching multiplicities known as one-dimensional sums, are conjectured to have a simple relationship with those of type A, which are known as generalized Kostka polynomials. This is called the X=M=K conjecture. It is proved for tensor products of the symmetric power Kirillov-Reshetik

Anders N. Jensen

The Groebner fan of an ideal $I\subset k[x_1,...,x_n]$, defined by Mora and Robbiano, is a complex of polyhedral cones in $R^n$. The maximal cones of the fan are in bijection with the distinct monomial initial ideals of $I$ as the term order varies. If $I$ is homogeneous the Groebner fan is complete and is the normal fan of the state polytope of $I$. In gene

Alberto Isidori, Lorenzo Marconi, Claudio De Persis

The problem addressed in this paper is to control a plant so as to have its output tracking (a family of) reference commands generated at a remote location and transmitted through a communication channel of finite capacity. The uncertainty due to the presence of the communication channel is counteracted by a suitable choice of the parameters of the regulator

Karin Baur

Parabolic subalgebras of semi-simple Lie algebras decompose as $\frak{p}=\frak{m}\oplus\frak{n}$ where $\frak{m}$ is a Levi factor and $\frak{n}$ the corresponding nilradical. By Richardsons theorem, there exists an open orbit under the action of the adjoint group $P$ on the nilradical. The elements of this dense orbits are known as Richardson elements. In t

Donu Arapura, Su-Jeong Kang

There is a natural descending filtration on the singular cohomology of a complex smooth projective variety called the coniveau filtration. The generalized Hodge conjecture would imply, rather trivially, that the coniveau filtration is compatible with pushforwards, pullbacks and products. The purpose of this paper is to prove this statement unconditionally. T

Ryo Takahashi

Let R be a commutative Noetherian local ring with residue class field k. In this paper, we mainly investigate direct summands of the syzygy modules of k. We prove that R is regular if and only if some syzygy module of k has a semidualizing summand. After that, we consider whether R is Gorenstein if and only if some syzygy module of k has a G-projective summa

Marina V. Semenova, Friedrich Wehrung

For a partially ordered set P, we denote by Co(P) the lattice of order-convex subsets of P. We find three new lattice identities, (S), (U), and (B), such that the following result holds. Theorem. Let L be a lattice. Then L embeds into some lattice of the form Co(P) iff L satisfies (S), (U), and (B). Furthermore, if L has an embedding into some Co(P), then it

Marina V. Semenova, Friedrich Wehrung

For a positive integer n, we denote by SUB (resp., SUBn) the class of all lattices that can be embedded into the lattice Co(P) of all order-convex subsets of a partially ordered set P (resp., P of length at most n). We prove the following results: (1) SUBn is a finitely based variety, for any n &#8805; 1. (2) SUB2 is locally finite. (3) A finite atomistic la

Marina V. Semenova, Friedrich Wehrung

For a partially ordered set P, let Co(P) denote the lattice of all order-convex subsets of P. For a positive integer n, we denote by SUB(LO) (resp., SUB(n)) the class of all lattices that can be embedded into a product of lattices of convex subsets of chains (resp., chains with at most n elements). We prove the following results: (1) Both classes SUB(LO) and

Thomas Lam

We define a new family of symmetric functions which are affine analogues of Stanley symmetric functions. We establish basic properties of these functions including symmetry, dominance and conjugation. We conjecture certain positivity properties in terms of a subfamily of symmetric functions called affine Schur functions. As applications, we show how affine S

Renyi Ma

We prove that there exists at least one close orbit in a given contact hypersurface in some symplectic manifolds.

Johannes Huebschmann

Let R be a local ring and A a connected differential graded algebra over R which is free as a graded R-module. Using homological perturbation theory techniques, we construct a minimal free multi model for A having properties similar to that of an ordinary minimal model over a field; in particular the model is unique up to isomorphism of multialgebras. The at

Jan E. Grabowski

We introduce and study the triple of a quasitriangular Lie bialgebra as a natural extension of the Drinfeld double. The triple is itself a quasitriangular Lie bialgebra. We prove several results about the algebraic structure of the triple, analogous to known results for the double. Among them, we prove that in the factorisable case the triple is isomorphic t

Carl M. Bender, Ines Cavero-Pelaez, Kimball A. Milton, K. V. Shajesh

The Hamiltonian for quantum electrodynamics becomes non-Hermitian if the unrenormalized electric charge $e$ is taken to be imaginary. However, if one also specifies that the potential $A^μ$ in such a theory transforms as a pseudovector rather than a vector, then the Hamiltonian becomes PT symmetric. The resulting non-Hermitian theory of electrodynamics is th

James M. Cline

I review some aspects of obtaining inflation from string theory, in particular brane-antibrane inflation within the framework of KKLMMT, and racetrack inflation. Further, I discuss recent work on the problem of reheating after brane-antibrane annihilation, and possible distinctive features of production of cosmic string and brane defects at this time.

R. Jackiw

To appear in Encyclopedia of Mathematical Physics, published by Elsevier in early 2006. Comments/corrections welcome. The article surveys topological aspects in gauge theories.

Gesualdo Delfino, Giuliano Niccoli

The form factors of the descendant operators in the massive Lee-Yang model are determined up to level 7. This is first done by exploiting the conserved quantities of the integrable theory to generate the solutions for the descendants starting from the lowest non-trivial solutions in each operator family. We then show that the operator space generated in this

R. P. Malik

We show the existence of a time-space noncommutativity (NC) for the physical system of a massive relativistic particle by exploiting the underlying symmetry properties of this system. The space-space NC is eliminated by the consideration of the exact symmetry properties and their consistency with the equations of motion for the above system. The symmetry cor

Maury Goodman

Several new reactor neutrino experiments are being considered to measure the parameter theta-13. The current plans for Angra, Braidwood, Daya Bay, KASKA and KR2DET are reviewed. A case is made that, together with Double-CHOOZ, a future world program should include at least three such experiments.

Kenneth Lane, Adam Martin

We study vacuum alignment in theories in which the chiral symmetry of a set of massless fermions is both spontaneously and explicitly broken. We find that transitions occur between different phases of the fermions&#39; CP symmetry as parameters in their symmetry breaking Hamiltonian are varied. We identify a new phase that we call pseudoCP-conserving. We obs

R. Thomas, K. Gallmeister, S. Zschocke, B. Kampfer

The QCD sum rule approach to in-medium modifications of the omega meson in nuclear matter is reviewed with emphasis of its relation to 4-quark condensates and chiral symmetry restoration. Possible implications of the CB-TAPS experiment for the reaction gamma A -> A&#39; omega (-> pi0 gamma) are sketched and the particularly important role of di-electron prob

Koichi Matsuda, Hiroyuki Nishiura

We propose a mass matrix model that gives a unified description of quark and lepton with the same texture form based on a flavor 2 <-> 3 symmetry. The model is in contrast with the conventional picture that the mass matrix forms in the quark sector will take somewhat different structures from those in the lepton sector. By investigating possible types of ass

Patrick O. Bowman, Urs M. Heller, Derek B. Leinweber, Maria B. Parappilly

We present an unquenched calculation of the quark propagator in Landau gauge with 2+1 flavors of dynamical quarks. We use configurations generated with an improved staggered (``Asqtad'') action by the MILC collaboration. This quark action has been seen to have excellent rotational symmetry and scaling properties in the quenched quark propagator. Quenched and

The BABAR Collaboration, B. Aubert

We search for the factorization-suppressed decays B -> chi_c0 K(*) and B -> chi_c2 K(*), with chi_c0 and chi_c2 decaying into J/psi gamma using a sample of 124 10^6 BBbar events collected with the BABAR detector at the PEP-II storage ring of the Stanford Linear Accelerator Center.

ZEUS Collaboration

Deep inelastic scattering and its diffractive component, ep -> e&#39;gamma*p ->e&#39;XN, have been studied at HERA with the ZEUS detector using an integrated luminosity of 4.2 pb-1. The measurement covers a wide range in the gamma*p c.m. energy W (37 - 245 GeV), photon virtuality Q2 (2.2 - 80 GeV2) and mass Mx. The diffractive cross section for Mx > 2 GeV ri

A. Somov

We present measurements of time-dependent asymmetries in decays of neutral B mesons to the final states B0 -> rho+ pi-. Measurements are based on a 140 fb-1 data sample collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider.

C. Schill

One of the key objectives of the COMPASS experiment at CERN is the determination of the gluon contribution to the nucleon spin. The gluon polarization is measured via photon-gluon fusion in deep-inelastic scattering of 160 GeV/c polarized muons on a polarized 6LiD solid-state target. Photon-gluon fusion is tagged by the observation of charmed mesons or the p

Bijan Saha

We consider a self-consistent system of Bianchi type-I (BI) gravitational field and a binary mixture of perfect fluid and dark energy. The perfect fluid is taken to be the one obeying the usual equation of state, i.e., $p = ζ\ve$, with $ζ\in [0, 1]$ whereas, the dark energy is considered to be obeying a quintessence-like equation of state. Exact solutions to