February 2001 arXiv papers — page 11

R. Foot

Parity and time reversal are obvious and plausible candidates for fundamental symmetries of nature. Hypothesising that these symmetries exist implies the existence of a new form of matter, called mirror matter. The mirror matter theory (or exact parity model) makes four main predictions: 1) Dark matter in the form of mirror matter should exist in the Univers

D. Kielpinski, A. Ben-Kish, J. Britton, V. Meyer

We review recent experiments on entanglement, Bell's inequality, and decoherence-free subspaces in a quantum register of trapped \be ions. We have demonstrated entanglement of up to four ions using the technique of Mølmer and Sørensen. This method produces the state |down down> + |up up> for two ions and the state |down down down down> + |up up up up> fo

H. Bergeron

In this paper, we investigate the connection between Classical and Quantum Mechanics by dividing Quantum Theory in two parts: - General Quantum Axiomatics (a system is described by a state in a Hilbert space, observables are self-adjoint operators and so on) - Quantum Mechanics properly that specifies the Hilbert space, the Heisenberg rule, the free Hamilton

Y. Aharonov, L. Vaidman

Two recent works suggest a possibility of sending signals to a space-like separated region, contrary to the spirit of special relativity. In the first work [J. Grunhaus, S. Popescu, and D. Rohrlich, Phys. Rev. A 53, 3781 (1996)] it has been shown that sending signals to particular union of space-like separated region cannot cause causality paradoxes. Another

Zae-young Ghim, Hwe Ik Zhang

It is argued that the concept of ``physical quantities possessed by the system'' is both redundant and inappropriate. We have examined two versions of the concept of ``possessed values'': one identical with the observed values and the other non-identical. Assuming the existence of such ``physical quantities possessed by the system'' a

Dimitris G. Angelakis, Almut Beige, Peter L. Knight, William J. Munro

Recent experiments to test Bell's inequality using entangled photons and ions aimed at tests of basic quantum mechanical principles. Interesting results have been obtained and many loopholes could be closed. In this paper we want to point out that tests of Bell's inequality also play an important role in verifying atom entanglement schemes. We descri

M. I. Molina, C. A. Bustamante

We solve the continuous one-dimensional Schrödinger equation for the case of an inverted {\em nonlinear} delta-function potential located at the origin, obtaining the bound state in closed form as a function of the nonlinear exponent. The bound state probability profile decays exponentially away from the origin, with a profile width that increases monotonica

M. I. Molina

We introduce and solve in closed form a simple model of a macroscopic body propagating in a one-dimensional resistive medium at temperature T. The assumption of completely inelastic collisions between the body and the particles composing the medium leads to a resistive force that is opposite and proportional to the square of the body's velocity

Peter Woit

A polemical article evaluating string theory from the point of view of a quantum field theorist working in a mathematics department. Comments to the author are encouraged.

K. Doll

We describe the implementation of analytical Hartree-Fock gradients for periodic systems in the code CRYSTAL, emphasizing the technical aspects of this task. The code is now capable of calculating analytical derivatives with respect to nuclear coordinates for systems periodic in 0, 1, 2 and 3 dimensions (i.e. molecules, polymers, slabs and solids). Both clos

Fang Wu, Wei-Mou Zheng

A self-organizing approach is proposed for gene finding based on the model of codon usage for coding regions and positional preference for noncoding regions. The symmetry between the direct and reverse coding regions is adopted for reducing the number of parameters. Without requiring prior training, parameters are estimated by iteration. By employing the win

Franz Gross, Cetin Savkli, John Tjon

A scalar field theory with a $χ^\dagχϕ$ interaction is known to be unstable. Yet it has been used frequently without any sign of instability in standard text book examples and research articles. In order to reconcile these seemingly conflicting results, we show that the theory is stable if the Fock space of all intermediate states is limited to a {\em finite

Rajkumar Roychoudhury, Pinaki Roy, Miloslav Znojil, Ge'za Le'vai

We study a quantum mechanical potential introduced previously as a conditionally exactly solvable (CES) model. Besides an analysis following its original introduction in terms of the point canonical transformation, we also present an alternative supersymmetric construction of it. We demonstrate that from the three roots of the implicit cubic equation definin

Nets Katz, Terence Tao

We establish new estimates on the Minkowski and Hausdorff dimensions of Besicovitch sets and obtain new bounds on the Kakeya maximal operator.

Masayoshi Kaneda, Vern Ival Paulsen

In this paper we give characterizations of essential left ideals of a C*-algebra $A$ in terms of their properties as operator $A$-modules. Conversely, we seek C*-algebraic characterizations of those ideals $J$ in $A$ such that $A$ is an essential extension of $J$ in various categories of operator modules. In the case of two-sided ideals, we prove that all th

Guillermo Cortinas

The title refers to the nilcommutative or $NC$-schemes introduced by M. Kapranov in math.AG/9802041. The latter are noncommutative nilpotent thickenings of commutative schemes. We consider also the parallel theory of nil-Poisson or $NP$-schemes, which are nilpotent thickenings of commutative schemes in the category of Poisson schemes. We study several varian

Thomas Dawson

We compare two known methods of extending a complex, unital, commutative normed algebra so as to include solutions to sets of monic polynomials over the original algebra. (One of these is a generalisation of a construction from the thesis of B. J. Cole and only applies to uniform algebras.) An example is given to show that they can lead to essentially differ

Atanas Iliev, Kristian Ranestad

In this note we show that the apolar cubic forms associated to codimension two linear sections of canonical curves of genus at least eleven are special with respect to their presentation as sums of cubes.

Daniel Smania

We study the dynamics of the renormalization operator for multimodal maps. In particular, we prove the exponential convergence of this operator for infinitely renormalizable maps with same bounded combinatorial type.

C. Dong, H. Li, G. Mason

The notions of vertex Lie algebra and vertex Poisson algebra are presented and connections among vertex Lie algebras, vertex Poisson algebras and vertex algebras are discussed.

Laurent Manivel

We give an explicit combinatorial description of the irreducible components of the singular locus of a Schubert variety in a flag variety of type A. This implies a conjecture of Lakshmibai and Sandhya.

Dorothee Schueth

We construct several new classes of isospectral manifolds with different local geometries. After reviewing a theorem by Carolyn Gordon on isospectral torus bundles and presenting certain useful specialized versions (Chapter 1) we apply these tools to construct the first examples of isospectral four-dimensional manifolds which are not locally isometric (Chapt

Elena Rubei

The main result of this paper is the following: let d be a natural number >= 3; the line bundle O(1,...,1) on the product of d copies of the projective line P^1 satisfies Property N_p of Green-Lazarsfeld if and only if p <= 3.

Meijun Zhu

The main purpose of this paper is to prove a sharp Sobolev inequality in an exterior of a convex bounded domain. There are two ingredients in the proof: One is the observation of some new isoperimetric inequalities with partial free boundary, and the other is an integral inequality (due to Duff [9]) for any nonnegative function under Schwarz equimeasurable r

H. Casini, R. Montemayor, Luis F. Urrutia

We show that the parent Lagrangian method gives a natural generalization of the dual theories concept for non p-form fields. Using this generalization we construct here a three-parameter family of Lagrangians that are dual to the Fierz-Pauli description of a free massive spin-two system. The dual field is a three-index tensor T, which dinamically belongs to

A. A. Bichl, J. M. Grimstrup, L. Popp, M. Schweda

With the help of the Seiberg-Witten map for photons and fermions we define a theta-deformed QED at the classical level. Two possibilities of gauge-fixing are discussed. A possible non-Abelian extension for a pure theta-deformed Yang-Mills theory is also presented.

Ingo Kirsch, Lewis H. Ryder, Friedrich W. Hehl

We consider Dirac&#39;s free electron theory on the first quantized level. We decompose its canonical spin current á la Gordon and find a conserved ``Gordon spin&#39;&#39; current which turns out to be equivalent to the Hilgevoord-Wouthuysen spin. We can conclude therefrom that the Gordon-type decomposition mentioned above corresponds to a Foldy-Wouthuysen t

Sergei V. Ketov

Some instanton corrections to the universal hypermultiplet moduli space metric of the type-IIA string theory compactified on a Calabi-Yau threefold arise due to multiple wrapping of BPS membranes and fivebranes around certain cycles of Calabi-Yau. The classical universal hypermultipet metric is locally equivalent to the Bergmann metric of the symmetric quate

Paolo Budinich

It is shown how the old Cartan&#39;s conjecture on the fundamental role of the geometry of simple (or pure) spinors, as bilinearly underlying euclidean geometry, may be extended also to quantum mechanics of fermions (in first quantization), however in compact momentum spaces, bilinearly constructed with spinors, with signatures unambiguously resulting from t

Charles Gale

We review the production of lepton pairs during high energy nuclear collisions. We highlight the information being carried out of the hot and dense strongly interacting medium. We describe the phenomenon of scalar-vector mixing that can take place in a dense medium and suggest possible measurable signatures of this effect in high energy heavy ion collisions.

Torben Hannah

The amplitude for the anomalous process gamma pi -> pi pi is evaluated to two loops in the chiral expansion by means of a dispersive method. The two new coupling constants that enter at this order are estimated via sum rules derived from a non-perturbative chiral approach. With these coupling constants fixed, the numerical results are given and compared with

M. Passera

We discuss recent calculations of the O(alpha) QED corrections to the recoil electron energy spectrum in neutrino electron scattering, and to the spectrum of the combined energy of the recoil electron and a possible accompanying photon emitted in the scattering process. We then examine the role of these corrections in the interpretation of precise measuremen

Peter Minkowski, Wolfgang Ochs

We present a short survey of the theoretical expectations on glueballs and hybrids as well as of the present phenomenological status. The possibility to obtain new information on gluonic mesons from the study of gluon jets in comparison to quark jets is discussed.

Paolo Checchia, Enrico Piotto

Sensitivity to the supersymmetric scalar states $ϕ$ at the future linear $e^+e^-$ and photon colliders is discussed. In particular it is illustrated a search strategy for massive sgoldstinos, the supersymmetric partners of the goldstino.

Kiwoon Choi

Recent atmospheric and solar neutrino experiments suggest that neutrinos have small but nonzero masses. They further suggest that mass eigenvalues have certain degree of hierarchical structures, and also some mixing angles are near-maximal while the others are small. We first survey possible explanations for the smallness of neutrino masses. We then discuss

Shinji Komine, Takeo Moroi, Masahiro Yamaguchi

Recently, the E821 experiment at the Brookhaven National Laboratory announced their latest result of their muon g-2 measurement which is about 2.6-σaway from the standard model prediction. Taking this result seriously, we examine the possibility to explain this discrepancy by the supersymmetric contribution. Our analysis is performed in the framework of the

A. V. Nesterenko

The mathematical properties of the new analytic running coupling (NARC) in QCD are investigated. This running coupling naturally arises under ``analytization&#39;&#39; of the renormalization group equation. One of the crucial points in our consideration is the relation established between the NARC and its inverse function. The latter is expressed in terms of

The DELPHI Collaboration, P. Abreu

Searches for the Standard Model Higgs boson have been performed in the data collected by the DELPHI experiment at LEP in the year 2000 at centre-of-mass energies between 200 and 209 GeV corresponding to a total integrated luminosity of 224 pb^{-1}. No evidence for a Higgs signal is observed in the kinematically accessible mass range, and a 95% CL lower mass

Motoyuki Saijo, Masaru Shibata, Thomas W. Baumgarte, Stuart L. Shapiro

We study by computational means the dynamical stability against bar-mode deformation of rapidly and differentially rotating stars in a post-Newtonian approximation of general relativity. We vary the compaction of the star $M/R$ (where $M$ is the gravitational mass and $R$ the equatorial circumferential radius) between 0.01 and 0.05 to isolate the influence o

E. N. Glass, J. P. Krisch

Regarding the spin-up of Schwarzschild-Kerr and Banados-Teitelboim-Zanelli systems as a symmetry breaking phase transition, critical exponents are evaluated and compared with classical Landau predictions. We suggest a definition of isothermal compressibity which is independent of spin direction. We find identical exponents for both systems, and possible univ

Luca Lusanna, Stefano Russo

A new version of tetrad gravity in globally hyperbolic, asymptotically flat at spatial infinity spacetimes with Cauchy surfaces diffeomorphic to $R^3$ is obtained by using a new parametrization of arbitrary cotetrads to define a set of configurational variables to be used in the ADM metric action. Seven of the fourteen first class constraints have the form o

Ninan Sajeeth Philip, K. Babu Joseph

This paper discusses mixing of chaotic systems as a dependable method for secure communication. Distribution of the entropy function for steady state as well as plaintext input sequences are analyzed. It is shown that the mixing of chaotic sequences results in a sequence that does not have any state dependence on the information encrypted by them. The genera

J. M. Yanez, M. I. Molina, D. C. Mattis

We calculate thermodynamic properties of a disordered model insulator, starting from the ideal simple-cubic lattice ($g = 0$) and increasing the disorder parameter $g$ to $\gg 1/2$. As in earlier Einstein- and Debye- approximations, there is a phase transition at $g_{c} = 1/2$. For $g<g_{c}$ the low-T heat-capacity $C \sim T^{3}$ whereas for $g>g_{c}$, $C \s

Vladimir Privman, Dima Mozyrsky, Israel D. Vagner

We survey recent work on designing and evaluating quantum computing implementations based on nuclear or bound-electron spins in semiconductor heterostructures at low temperatures and in high magnetic fields. General overview is followed by a summary of results of our theoretical calculations of decoherence time scales and spin-spin interactions. The latter w

C. J. Olson, C. Reichhardt, B. Janko, Franco Nori

We propose and study a novel way to produce a DC transport of vortices when applying an AC electrical current to a sample. Specifically, we study superconductors with a graduated random pinning density, which transports interacting vortices as a ratchet system. We show that a ratchet effect appears as a consequence of the long range interactions between the

D. Sornette, Y. Malevergne

We study and generalize in various ways the model of rational expectation (RE) bubbles introduced by Blanchard and Watson in the economic literature. First, bubbles are argued to be the equivalent of Goldstone modes of the fundamental rational pricing equation, associated with the symmetry-breaking introduced by non-vanishing dividends. Generalizing bubbles

Carlo Acerbi, Claudio Nordio, Carlo Sirtori

We study the properties of Expected Shortfall from the point of view of financial risk management. This measure --- which emerges as a natural remedy in some cases where Value at Risk (VaR) is not able to distinguish portfolios which bear different levels of risk --- is indeed shown to have much better properties than VaR. We show in fact that unlike VaR thi

D. van der Marel, A. A. Tsvetkov

A detailed calculation is presented of the dielectric function in superconducttors consisting of two Josephson coupled superconducting layers per unit cell, taking into account the effect of finite compressibility of the electron fluid. From the model it follows, that two longitudinal, and one transverse optical Josephson plasma resonance exist in these mate

R. Vilela Mendes, R. Lima, T. Araujo

The statistical properties of a stochastic process may be described (1)by the expectation values of the observables, (2)by the probability distribution functions or (3)by probability measures on path space. Here an analysis of level (3) is carried out for market fluctuation processes. Gibbs measures and chains with complete connections are considered. Some o

Abraham Nitzan

Electron transmission through molecules and molecular interfaces has been a subject of intensive research due to recent interest in electron transfer phenomena underlying the operation of the scanning tunneling microscope (STM) on one hand, and in the transmission properties of molecular bridges between conducting leads on the other. In these processes the t

V. Ta Phuoc, E. Olive, R. De Sousa, A. Ruyter

The transverse Meissner effect (TME) in the highly layered superconductor Bi2Sr2CaCu2O(8+y) with columnar defects is investigated by transport measurements. We present detailed evidence for the persistence of the Bose-glass phase when H is tilted at an angle theta < theta_c (T) away from the column direction: (i) the variable-range vortex hopping process for

Ha Youn Lee, Mehran Kardar

Inspired by patterns observed in mixtures of microtubules and molecular motors, we propose continuum equations for the evolution of motor density, and microtubule orientation. The chief ingredients are the transport of motors along tubules, and the alignment of tubules in the process. The macroscopic equations lead to aster and vortex patterns in qualitative

A. I. Lichtenstein, M. I. Katsnelson, G. Kotliar

We present an ab initio quantum theory of the finite temperature magnetism of iron and nickel. A recently developed technique which combines dynamical mean-field theory with realistic electronic structure methods, successfully describes the many-body features of the one electron spectra and the observed magnetic moments below and above the Curie temperature.

Y. Sugita, Y. Okamoto

We review uses of the generalized-ensemble algorithms for free-energy calculations in protein folding. Two of the well-known methods are multicanonical algorithm and replica-exchange method; the latter is also referred to as parallel tempering. We present a new generalized-ensemble algorithm that combines the merits of the two methods; it is referred to as t

Zeno Farkas, Ferenc Szalai, Dietrich E. Wolf, Tamas Vicsek

We report on a segregation scheme for granular binary mixtures, where the segregation is performed by a ratchet mechanism realized by a vertically shaken asymmetric sawtooth-shaped base in a quasi-two-dimensional box. We have studied this system by computer simulations and found that most binary mixtures can be segregated using an appropriately chosen ratche

F. Rullier-Albenque, H. Alloul, R. Tourbot

We report resistivity measurements in underdoped YBa$_{2}$Cu$_{3}$O$_{6.6} $and overdoped Tl$_{2}$Ba$_{2}$CuO$_{6+x}$ single crystals in which the concentration of defects in the CuO$_{2}$ planes is controlled by electron irradiation. Low $T$ upturns of the resistivity are observed in both cases for large defect content. In the Tl compound the decrease of co

G. Sergeeva

With using general properties of superconducting state for 2D systems the universal temperature dependence of the penetration length is found out for quasi-2D HTS, that leads to Uemura plot and evidences about 2D character of superconducting transition. It is shown that from the measurements of c-axis resistivity and of the penetration length the value of th

J. W. van der Eb, A. B. Kuz&#39;menko, D. van der Marel

We determined the optical properties of alpha- and gamma-phase Ce in the photon energy range from 60 meV to 2.5 eV using ellipsometry and grazing incidence reflectometry. We observe significant changes of the optical conductivity, the dynamical scattering rate, and the effective mass between alpha- and gamma-cerium. The alpha-phase is characterized by Fermi-

L. D. Carr, K. W. Mahmud, W. P. Reinhardt

The fundamental question of how Bose-Einstein condensates tunnel into a barrier is addressed. The cubic nonlinear Schrodinger equation with a finite square well potential, which models a Bose-Einstein condensate in a quasi-one-dimensional trap of finite depth, is solved for the complete set of localized and partially localized stationary states, which the fo

J. C. Phillips, J. Jung

The causes of high-temperature superconductivity (HTSC) are still mysterious, although more than 50,000 experiments have studied this subject. The most severe test of any microscopic theory is generally considered to be its ability to predict the results of future experiments. Here we examine recent (99-01)studies of BSCCO films by STM, which have revealed n

R. A. Downes, R. F. Webbink, M. M. Shara, Hans Ritter

The Catalog and Atlas of Cataclysmic Variables (Edition 1 - 1993) and Edition 2 - 1997) has been a valuable source of information for the cataclysmic variable (CV) community. However, the goal of having a central location for all objects is slowly being lost as each new edition is generated. There can also be a long time delay between new information becomin

E. Berger, S. Ball, K. M. Becker, M. Clarke

Brown dwarfs are classified as objects which are not massive enough to sustain nuclear fusion of hydrogen, and are distinguished from planets by their ability to burn deuterium. Old (>10 Myr) brown dwarfs are expected to possess short-lived magnetic fields and, since they no longer generate energy from collapse and accretion, weak radio and X-ray emitting co

T. Di Salvo, N. R. Robba, R. Iaria, L. Stella

We present the results of a BeppoSAX observation of the Z source GX 349+2 covering the energy range 0.1-200 keV. The presence of flares in the light curve indicates that the source was in the flaring branch during the BeppoSAX observation. We accumulated energy spectra separately for the non-flaring intervals and the flares. In both cases the continuum is we

M. Boettcher, R. Saxena, A. W. Crider

We suggest a simple fitting formula to represent Comptonized X- and gamma-ray spectra from a hot ($kT_e \gtrsim 10$ keV), Thomson thick ($τ_T \gtrsim 5$) hybrid thermal/nonthermal plasma in spherical geometry with homogeneous soft-photon injection throughout the Comptonizing region. We have used this formula to fit a large data base of Monte-Carlo generated

I. Valtchanov, M. Pierre, R. Gastaud

Procedures based on current methods to detect sources in X-ray images are applied to simulated XMM images. All significant instrumental effects are taken into account, and two kinds of sources are considered -- unresolved sources represented by the telescope PSF and extended ones represented by a b-profile model. Different sets of test cases with controlled

V. A. De Lorenci, N. Figueiredo, H. H. Fliche, M. Novello

In the context of the static and spherically symmetric solution of a charged compact object, we present the expression for the bending of light in the region just outside the event horizon (the dyadosphere) where vacuum polarization effects are taken into account.

L. Maraschi, F. Tavecchio

We discuss the present knowledge about the Spectral Energy Distributions (SEDs) of blazars within a unified approach emphasizing overall similarities. The properties of the average SEDs of different samples of blazars suggest that more powerful sources contain on average less energetic particles. Detailed studies of TeV emitting blazars show that the energy

Alan Stockton, Susan E. Ridgway

We present deep imaging and spectroscopic observations of the z = 1.195 quasar 3C 190 and its immediate environment. The quasar is surrounded by an asymmetric low-surface-brightness envelope in which there are also several galaxies with characteristic dimensions of 3-5 kpc. Some of these form a linear structure some 50 kpc long in projection, offset from the

H. D. Tran, Z. Tsvetanov, H. C. Ford, J. Davies

We examine the dust properties of a nearby distance-limited sample of early type galaxies using the WFPC2 of the Hubble Space Telescope. Dust is detected in 29 out of 67 galaxies (43%), including 12 with small nuclear dusty disks. In a separate sample of 40 galaxies biased for the detection of dust by virtue of their detection in the IRAS 100 micron band, du

P. Mazzotta, M. Markevitch, A. Vikhlinin, W. R. Forman

We have analyzed the Chandra observation of the distant (z=0.164) galaxy cluster RXJ1720.1+2638 in which we find sharp features in the X-ray surface brightness on opposite sides of the X-ray peak: an edge at about 250 h_50^{-1} kpc to the South-East and a plateau at about 130 h_50^{-1} kpc to the North-West. The surface brightness edge and the plateau can be

C. M. Boily, P. Kroupa, J. Penarrubia-Garrido

We present an efficient method for building equilibrium multi-component galaxies with non-spherical haloes and bulges. The gist of our approach is to tailor the velocity ellipsoid directly to the geometry of the mass distribution. Thus we avoid computing the anisotropic velocity dispersions which leads to large savings in the cpu budget. The computational ti

Jonathan C. Tan, Christopher D. Matzner, Christopher F. McKee

The spatiotemporal coincidence of supernova (SN) 1998bw and gamma-ray burst (GRB) 980425 and this supernova&#39;s unusual optical and radio properties have prompted many theoretical models that produce GRBs from supernovae. We review the salient features of our simple, spherical model in which an energetic supernova explosion shock accelerates a small fracti

Gintaras Duda, Graciela Gelmini, Paolo Gondolo

Here we examine the detectability of collisionless dark matter candidates that may constitute not all but only a subdominant component of galactic cold dark matter. We show that current axion searches are not suited for a subdominant component, while direct WIMP searches would not be severely affected by the reduced density. In fact, the direct detection rat

Oren Bergman, Eric Gimon, Barak Kol

The orbifold lines IIA/I_8 and IIB/$I_8 (-1)^{F_L} possess BPS discrete torsion variants which carry fundamental string (NSNS) charge. We show that these variants are actually classified by an integral electric field F from the twisted RR sector, and compute their tension and NSNS charge as a function of F. The analysis employs equivariant K-theory and the s

P. C. Canfield, D. K. Finnemore, S. L. Bud&#39;ko, J. E. Ostenson

$MgB_2$ becomes superconducting just below 40 K. Whereas porous polycrystalline samples of $MgB_2$ can be synthesized from boron powders, in this letter we demonstrate that dense wires of $MgB_2$ can be prepared by exposing boron filaments to $Mg$ vapor. The resulting wires have a diameter of 160 $μm$, are better than 80% dense and manifest the full $χ= -1/4

E. W. N. Glover, C. Oleari, M. E. Tejeda-Yeomans

We present the O(alpha_s^4) virtual QCD corrections to gluon-gluon scattering due to the interference of tree and two-loop amplitudes. We work in conventional dimensional regularisation and give analytic expressions renormalised in the MSbar scheme. The structure of the infrared divergences agrees with that predicted by Catani while formulae for the finite r

Timothy G. Hawarden, S. K. Leggett, Michael B. Letawsky, David R. Ballantyne

We present high-precision JHK photometry with the 3.8m UK Infrared Telescope (UKIRT) of 83 standard stars, 28 from the widely used preliminary list known as the &#34;UKIRT Faint Standards&#34; (Casali & Hawarden, 1992), referred to here as the Fundamental List, and 55 additional stars referred to as the Extended List. The stars have 9.4<K<15.0 and most shoul

Debajyoti Choudhury, Biswarup Mukhopadhyaya, Subhendu Rakshit

We investigate the status of models containing exotic fermions or extra Z-like neutral gauge bosons in the light of the recent data on anomalous magnetic moment of muon. We find that it is possible to extract interesting bounds on the parameters characterizing such models. The bounds are particularly strong if the new flavour-changing neutral currents are ax

Neil R. Constable, Robert C. Myers, Oyvind Tafjord

We study new solutions of the low-energy equations of motion for the non-abelian D-string. We find a "fuzzy funnel" solution consisting of a noncommutative four-sphere geometry which expands along the length of the D-string. We show that this funnel solution has an interpretation as D-strings ending on a set of orthogonal D5-branes. Although not supersymmetr

Robert L. Oldershaw

The incidence of planetary systems orbiting red dwarf stars with masses less than 0.4 solar masses provides a crucial observational test for the Self-Similar Cosmological paradigm. The discrete self-similarity of the paradigm mandates the prediction of anomalously few planetary systems associated with these lowest mass red dwarf stars, in contrast to convent

T. M. Heckman, K. R. Sembach, G. R. Meurer, D. K. Strickland

We report FUSE far-UV spectroscopy of the prototypical dwarf starburst galaxy NGC 1705. These data allow us for the first time to probe the coronal-phase gas (T = 10E5 to 10E6 K) that may dominate the radiative cooling of the supernova-heated ISM and thereby determine the dynamical evolution of starburst-driven outflows. We detect a broad (100 km/s) and blue

F. A. Dilkes, M. J. Duff, James T. Liu, H. Sati

We show that the recently demonstrated absence of the usual discontinuity for massive spin 2 with a Lambda term is an artifact of the tree approximation, and that the discontinuity reappears at one loop.

Peter Hoyer, Jan Neerbek, Yaoyun Shi

We consider the quantum complexities of the following three problems: searching an ordered list, sorting an un-ordered list, and deciding whether the numbers in a list are all distinct. Letting N be the number of elements in the input list, we prove a lower bound of \frac{1}π(\ln(N)-1) accesses to the list elements for ordered searching, a lower bound of Ω(N

A. S. Alexandrov, C. Sricheewin

We show that the single-particle polaron Green&#39;s function describes SIS tunnelling in cuprates, including the absence of Ohm&#39;s law at high voltages, the dip/hump features in the first derivative of the current, a substantial incoherent spectral weight beyond quasiparticle peaks and unusual shape of the peaks. The theory allows us to determine the cha

M. M. Sheikh-Jabbari

The three dimensional Chern-Simons theory on $\rr^2_θ\times \rr$ is studied. Considering the gauge transformations under the group elements which are going to one at infinity, we show that under arbitrary (finite) gauge transformations action changes with an integer multiple of $2π$ {\it if}, the level of noncommutaitive Chern-Simons is {\it quantized}. We a

T. P. Downes, P. Duffy, S. Komissarov

Relativistic shocks accelerate particles by the first order Fermi mechanism. These particles then emit synchrotron emission in the post shock gas. We have developed a numerical code which integrates the relativistic Euler equations for fluid dynamics with a general equation of state, together with the Liouville equation for the accelerated particles. We pres

Ch. Okonek, A. Teleman

Let $(F,J,ω)$ be an almost Kähler manifold, $α$ a $J$-holomorphic action of a compact Lie group $\hat K$ on $F$, and $K$ a closed normal subgroup of $\hat K$ which leaves $ω$ invariant. We introduce gauge theoretical invariants for such triples $(F,α,K)$. The invariants are associated with moduli spaces of solutions of a certain vortex type equation on a Rie

R. Capovilla, M. Montesinos, V. A. Prieto, E. Rojas

We propose a novel BF-type formulation of real four-dimensional gravity, which generalizes previous models. In particular, it allows for an arbitrary Immirzi parameter. We also construct the analogue of the Urbantke metric for this model.

B. Portelli, P. C. W. Holdsworth, M. Sellitto, S. T. Bramwell

We calculate the probability density function for the order parameter fluctuations in the low temperature phase of the 2D-XY model of magnetism near the line of critical points. A finite correlation length, ξ, is introduced with a small magnetic field, h, and an accurate expression for ξ(h) is developed by treating non-linear contributions to the field energ

T. Huang, Z. -H. Lin, L. -Y. Shan, X. Zhang

A non-universal interaction, which involves only the third family leptons induces lepton flavor violating couplings and contributes to the anomalous magnetic moment of muon. In this paper, we study the effects of non-universal interaction on muon (g-2) and rare decay $τ\to μγ$ by using an effective lagrangian technique, and a phenomenological $Z^\prime$ mode

Antonio H. Castro Neto

We propose a model of a spatially modulated collective charge state of superconducting cuprates. The regions of higher carrier density (stripes) are described in terms of Luttinger liquids and the regions of lower density as a two-dimensional interacting bosonic gas of d_{x^2-y^2} hole pairs. The interactions among the elementary excitations are repulsive an

Svend E. Hjelmeland, Ulf Lindström

We extend the path-integral formulation of Poisson-Lie duality found by Tyurin and von Unge to N=1 supersymmetric sigma-models. Using an explicit representation of the generators of the Drinfel&#39;d double corresponding to GxU(1)^dimG we discuss an application to non-abelian duality. The paper also contains the relevant background and some comments on Poiss

R. A. Schneider, W. Weise

The decays of the omega meson in a heat bath of thermally excited pions is studied within the framework of real-time thermal field theory using an appropriate effective Lagrangian. We show that the omega meson spectrum broadens considerably at temperatures T > 100 MeV, primarily because of omega pi -> pi pi reactions in the thermal environment.

C. D. Fosco, A. Lopez

We study renormalization effects in the Abelian Chern-Simons (CS) action. These effects can be non-trivial when the gauge field is coupled to dynamical matter, since the regularization of the UV divergences in the model forces the introduction of a parity even piece in the gauge field action. This changes the classical (odd) transformation properties of the

D. V. Fedorov, A. S. Jensen

The zero-range potential is customarily employed in various mean-field calculations of many-body systems in atomic and nuclear physics within, correspondingly, Gross-Pitaevskii and Skyrme-Hartree-Fock approach. We argue, however, that a many-body system with zero-range potentials is unstable against clusterization into collapsed three-body subsystems. We sho

Holger Gies, Kurt Langfeld

We propose a numerical technique for calculating effective actions of electromagnetic backgrounds based on the worldline formalism. As a conceptually simple example, we consider scalar electrodynamics in three dimensions to one-loop order. Beyond the constant-magnetic-field case, serving as a benchmark test, we analyze the effective action of a step-function

C. Giusti, F. D. Pacati

The formalism of (${\vec γ},{\vec N}N$) reactions is given where the incident photon is polarized and the outgoing nucleon polarization is detected. Sixteen structure functions and fifteen polarization observables are found in the general case, while only eight structure functions and seven polarizations observables survive in coplanar kinematics. Numerical

M. Haghighat, F. Loran

Bethe-Salpeter equation in the non-commutative space for a scalar-scalar bound state is considered. It is shown that in the non-relativistic limit, the effect of spatial non-commutativity appears as if there exist a magnetic dipole moment coupled to each particle.

S. Habib, K. Lindenberg, G. Lythe, C. Molina-Paris

We consider the dynamics of diffusing particles in one space dimension with annihilation on collision and nucleation (creation of particles) with constant probability per unit time and length. The cases of nucleation of single particles and nucleation in pairs are considered. A new method of analysis permits exact calculation of the steady state density and

Ion I. Cotăescu, Mihai Visinescu

The SO(4,1) gauge-invariant theory of the Dirac fermions in the external field of the Kaluza-Klein monopole is investigated. It is shown that the discrete quantum modes are governed by reducible representations of the o(4) dynamical algebra generated by the components of the angular momentum operator and those of the Runge-Lenz operator of the Dirac theory i