February 2006 arXiv papers — page 7

M. Bortz, J. Sirker

The magnetic susceptibility of the one-dimensional Hubbard model with open boundary conditions at arbitrary filling is obtained from field theory at low temperatures and small magnetic fields, including leading and next-leading orders. Logarithmic contributions to the bulk part are identified as well as algebraic-logarithmic divergences in the boundary contr

Fei Lin, Erik S. Sorensen, Catherine Kallin, A. John Berlinsky

We study cluster perturbation theory [Phys. Rev. Lett. \textbf{84}, 522 (2000)] when auxiliary field quantum Monte Carlo method is used for solving the cluster hamiltonian. As a case study, we calculate the spectral functions of the Hubbard model in one and two dimensions and compare our results for the spectral functions to results obtained using exact diag

I. A. Sergienko, E. Dagotto

With the perovskite multiferroic RMnO3 (R = Gd, Tb, Dy) as guidance, we argue that the Dzyaloshinskii-Moriya interaction (DMI) provides the microscopic mechanism for the coexistence and strong coupling between ferroelectricity and incommensurate magnetism. We use Monte-Carlo simulations and zero temperature exact calculations to study a model incorporating t

J. L. Cheng, M. W. Wu

Spin relaxation under identical Dresselhaus and Rashba coupling strengths in GaAs quantum wells is studied in both the traditional collinear statistics, where the energy spectra do not contain the spin-orbit coupling terms, and the helix statistics, where the spin-orbit couplings are included in the energy spectra. We show that there is only marginal differe

Jian Wang, Baigeng Wang, Wei Ren, Hong Guo

The conventional definition of spin-current, namely spin density multiplied by the group velocity, is not a conserved quantity due to possible spin rotations caused by spin-orbit (SO) interaction. However, in a model with spin-spin interactions, rotation of a spin causes a dynamic response of surrounding spins that opposes the rotation. Such a many-body effe

Andrea Alu, Nader Engheta

The possibility of using plasmonic covers to drastically reduce the total scattering cross section of spherical and cylindrical objects is discussed. While it is intuitively expected that increasing the physical size of an object may lead to an increase in its overall scattering cross section, here we see how a proper design of these lossless metamaterial co

Hendrik Heinz, Wolfgang Paul, Kurt Binder

Local pressures are important in the calculation of interface tensions and in analyzing micromechanical behavior. The calculation of local pressures in computer simulations has been limited to systems with pairwise interactions between the particles, which is not sufficient for chemically detailed systems with many-body potentials such as angles and torsions

Patrick W. Morris, Susan Stolovy, Stefanie Wachter, Alberto Noriega-Crespo

We have discovered an axially symmetric, well-defined shell of material in the constellation of Cepheus, based on imaging acquired as part of the Galactic First Look Survey with the Spitzer Space Telescope. The 86'' x 75'' object exhibits brightened limbs on the minor axis, and is clearly visible at 24 microns, but is not detected in the 3.6,

G. J. Wasserburg, M. Busso, R. Gallino, K. M. Nollett

(Abridged) We review abundances of short-lived nuclides in the early solar system (ESS) and the methods used to determine them. We compare them to the inventory for a uniform galactic production model. Within a factor of two, observed abundances of several isotopes are compatible with this model. I-129 is an exception, with an ESS inventory much lower than e

S. C. Gallagher, W. N. Brandt, G. Chartas, R. Priddey

We present 4-7 ks Chandra observations of 35 Broad Absorption Line (BAL) quasars from the Large Bright Quasar Survey, the largest sample of sensitive, 0.5-8.0 keV X-ray observations of this class of quasars to date. The limited ranges in both redshift (z=1.42-2.90) and UV luminosity (a factor of ~12) of the sample also make it relatively uniform. Of 35 targe

R. C. Nichol, R. K. Sheth, Y. Suto, A. J. Gray

We present measurements of the normalised redshift-space three-point correlation function (Q_z) of galaxies from the Sloan Digital Sky Survey (SDSS) main galaxy sample. We have applied our "npt" algorithm to both a volume-limited (36738 galaxies) and magnitude-limited sample (134741 galaxies) of SDSS galaxies, and find consistent results between the

R. E. Lupu, K. France, S. R. McCandliss

We report the first observation of Ly$α$ pumped molecular hydrogen emission lines in planetary nebulae. The H$_{2}$ emission observed in the ultraviolet spectra of NGC 6853 and NGC 3132 can be explained by excitation of vibrationally hot H$_{2}$ by Ly$α$ photons. Constraints are placed on the nebular Ly$α$ emission profile, as well as the molecular hydrogen

H. B. Hammel, D. K. Lynch, R. W. Russell, M. L. Sitko

We report 8- to 13-micron spectral observations of Neptune and Uranus from the NASA Infrared Telescope Facility spanning more than a decade. The spectroscopic data indicate a steady increase in Neptune's mean atmospheric 12-micron ethane emission from 1985 to 2003, followed by a slight decrease in 2004. The simplest explanation for the intensity variatio

Orsola De Marco, C. R. O'Dell, Pamela Gelfond, R. H. Rubin

We have analyzed HST ACS and WFPC2 new and archival images of eight HII regions to look for new proto-planetary disks (proplyds) similar to those found in the Orion Nebula. We find a wealth of features similar in size (though many are larger) to the bright cusps around the Orion Nebula proplyds. None of them, however, contains a definitive central star. From

N. Kleeorin, I. Rogachevskii

We studied the effect of the turbulent heat flux on the Reynolds stresses in a rotating turbulent convection. To this end we solved a coupled system of dynamical equations which includes the equations for the Reynolds stresses, the entropy fluctuations and the turbulent heat flux. We used a spectral $τ$ approximation in order to close the system of dynamical

Naomi A. Ridge, James Di Francesco, Helen Kirk, Di Li

We present an overview of data available for the Ophiuchus and Perseus molecular clouds from ``Phase I'' of the COMPLETE Survey of Star-Forming Regions. This survey provides a range of data complementary to the Spitzer Legacy Program ``From Molecular Cores to Planet Forming Disks.'' Phase I includes: Extinction maps derived from 2MASS near-in

V. La Parola, V. Mangano, D. Fox, B. Zhang

The short/hard GRB051210 was detected and located by the Swift-BAT instrument and rapidly pointed towards by the narrow field instrumens. The XRT was able to observe a bright X-ray afterglow, one of the few ever observed for this class of bursts. We present the analysis of the prompt and afterglow emission of this event The BAT spectrum is a power-law with p

P. P. Avelino, C. J. A. P. Martins, J. Menezes, R. Menezes

We discuss necessary conditions for a network of cosmic domain walls to have a chance of providing the dark energy that might explain the recent acceleration of the universe. We derive a strong bound on the curvature of the walls, which shows that viable candidate networks must be fine-tuned and non-standard. We also discuss various requirements that any sta

Matteo Maturi, Torsten Ensslin, Carlos Hernandez-Monteagudo, Jose Alberto Rubino-Martin

We discuss how to use the Rees-Sciama (RS) effect associated with merging clusters of galaxies to measure their kinematic properties. In a previous work (Rubino-Martin et al. 2004), the morphology and symmetries of the effect were examined by means of a simplified model. Here, we use realistic N-body simulations to better describe the effect, and to confirm

M. Lopez-Corredoira, C. M. Gutierrez

CONTEXT. Observational follow-up programmes for the characterization of ultra-luminous X-ray sources (ULXs) require the construction of clean samples of such sources in which the contamination by foreground/background sources is minimum. AIMS. In this article we calculate the degree of foreground/background contaminants among the ULX sample candidates in the

T. V. Zaqarashvili, B. Roberts

The weakly nonlinear interaction of sound and linearly polarised Alfv{é}n waves propagating in the same direction along an applied magnetic field is studied. It is found that a sound wave is coupled to the Alfv{é}n wave with double period and wavelength when the sound and Alfv{é}n speeds are equal. The Alfv{é}n wave drives the sound wave through the ponderom

V. Kukhianidze, T. V. Zaqarashvili, E. Khutsishvili

Height series of H$α$ spectra in solar limb spicules obtained with the 53 cm coronagraph of the Abastumani Astrophysical Observatory are analyzed. Each height series covered 8 different heights beginning at 3800 km above the photosphere. The spatial difference between neighboring heights was 1$^{\prime \prime}$, consequently $\sim$ 3800 - 8700 km distance ab

K. Kulczycki, T. Bulik, K. Belczynski, B. Rudak

We analyze the properties of VIRGO detector with the aim of studying its ability to search for coalescing black hole binaries. We focus on the remnants of the Population III stars, which currently should be massive black holes ($\sim 100-1000 M_\odot$), some of them bound in binary systems. The coalescence of such binaries due to emission of gravitational wa

Peter Goldreich, S. Sridhar

A strong case has been made that radio waves from sources within about half a degree of the Galactic Center undergo extreme diffractive scattering. However, problems arise when standard (``Kolmogorov'') models of electron density fluctuations are employed to interpret the observations of scattering in conjunction with those of free-free radio emissio

Albert A. Zijlstra, Mikako Matsuura, Peter R. Wood, G. C. Sloan

We present a Spitzer Space Telescope spectroscopic survey of mass-losing carbon stars (and one oxygen-rich star) in the Large Magellanic Cloud. The spectra cover the wavelength range 5--38 micron. They show varying combinations of dust continuum, dust emission features (SiC, MgS) and molecular absorption bands (C2H2, HCN). A set of four narrow bands, dubbed

A. Merloni, G. Rudnick, T. Di Matteo

We compare all the available observational data on the redshift evolution of the total stellar mass and star formation rate density in the Universe with the mass and accretion rate density evolution of supermassive black holes, estimated from the hard X-ray selected luminosity function of quasars and active galactic nuclei. We find that on average black hole

Fan Zhang, J. L. Qu, C. M. Zhang, W. Chen

In order to probe the activity of the inner disk flow and its effect on the neutron star surface emissions, we carried out the timing analysis of the Rossi X-Ray Timing Explorer (RXTE) observations of the millisecond X-ray pulsar XTE J1807--294, focusing on its correlated behaviors in X-ray intensities, hardness ratios, pulse profiles and power density spect

M. Shimon, Y. Rephaeli, B. W. O'Shea, M. L. Norman

Scattering of the cosmic microwave background (CMB) in clusters of galaxies polarizes the radiation. We explore several polarization components which have their origin in the kinematic quadrupole moments induced by the motion of the scattering electrons, either directed or random. Polarization levels and patterns are determined in a cluster simulated by the

J. N. Bregman, E. J. Lloyd-Davies

A soft X-ray excess has been claimed to exist in and around a number of galaxy clusters and this emission has been attributed to the warm-hot intergalactic medium that may constitute most of the baryons in the local universe. We have re-examined a study of the XMM-Newton observations on this topic by Kaastra et al. (2003) and find that the X-ray excess (or d

A. J. R. Prentice

I report the results of a new set of calculations for the gravitational contraction of the proto-solar cloud to quantify the idea that Titan may be a captured moon of Saturn (Prentice 1981, 1984). It is proposed that Titan initially condensed as a secondary embryo in the same proto-solar gas ring from which the central solid core and gaseous envelope of Satu

Stanislav Boldyrev

We propose a phenomenological theory of strong incompressible magnetohydrodynamic turbulence in the presence of a strong large-scale external magnetic field. We argue that in the inertial range of scales, magnetic-field and velocity-field fluctuations tend to align the directions of their polarizations. However, the perfect alignment cannot be reached, it is

Rychard J. Bouwens, Garth D. Illingworth

HST ACS and NICMOS data are now of sufficient depth and areal coverage to place strong constraints on the formation and evolution of galaxies during the first 1-2 Gyrs of the universe. Of particular interest are galaxies at z~6 since they represent the earliest epoch accessible by current high-efficiency optical instrumentation. To this end, we have construc

D. Fargion, M. Grossi, M. De Santis, P. G. De Sanctis Lucentini

Cerenkov Telescopes and Scintillators set on a Crown-like arrays facing the Horizons may reveal far Cosmic Rays Showers, nearer Anti-Neutrino-Electron + Electron --> W- shower in air and upgoing Tau Neutrino + N--> tau + X, --> Shower, Earth-Skimming tau air-showers. Even UHE SUSY Chi + e--> Selectron--> Chi + e at tens PeVs-EeV energy may blaze at Horizons,

P. Miocinovic, R. C. Field, P. W. Gorham, E. Guillian

We report on further analysis of coherent microwave Cherenkov impulses emitted via the Askaryan mechanism from high-energy electromagnetic showers produced at the Stanford Linear Accelerator Center (SLAC). In this report, the time-domain based analysis of the measurements made with a broadband (nominally 1-18 GHz) log periodic dipole array antenna is describ

J. Ellis, S. Heinemeyer, K. A. Olive, G. Weiglein

Electroweak precision measurements can provide indirect information about the possible scale of supersymmetry already at the present level of accuracy. We update the present-day sensitivities of precision data using the new experimental top-quark mass, m_t = 172.7 \pm 2.9 GeV, within the constrained minimal supersymmetric extension of the Standard Model (CMS

S. Kowalski, J. B. Natowitz, S. Shlomo, R. Wada

Experimental analyses of moderate temperature nuclear gases produced in the violent collisions of 35 MeV/nucleon$^{64}$Zn projectiles with $^{92}$Mo and $^{197}$Au target nuclei reveal a large degree of alpha particle clustering at low densities. For these gases, temperature and density dependent symmetry energy coefficients have been derived from isoscaling

Andrzej Borowiec, Wlodzimierz Godlowski, Marek Szydlowski

Recent supernovae of type Ia measurements and other astronomical observations suggest that our universe is in accelerating phase of evolution at the present epoch. While a dark energy of unknown form is usually proposed as the most feasible mechanism for the acceleration, there are appears some alternative conception that some effects arising from generaliza

Susha L. Parameswaran, Alexander Westphal

We present a new way to construct de Sitter vacua in type IIB flux compactifications, in which moduli stabilization and D-term uplifting can be combined in a manner consistent with the supergravity constraints. Here, the closed string fluxes fix the dilaton and the complex structure moduli while perturbative quantum corrections to the Kahler potential stabil

M. de Llano, J. J. Valencia

A recent Bose-Einstein condensation (BEC) model of several cuprate superconductors is based on bosonic Cooper pairs (CPs) moving in 3D with a quadratic energy-momentum (dispersion) relation. The 3D BEC condensate-fraction vs. temperature (T/Tc, where Tc is the BEC transition temperature) formula poorly fits penetration-depth data for two cuprates in the rang

C. R. Tam, V. M. Kaspi, B. M. Gaensler, E. V. Gotthelf

We present the results of Chandra X-ray Observatory observations of the transient anomalous X-ray pulsar (AXP) candidate AX J1845.0-0258 in apparent quiescence. Within the source's error circle, we find a point source and possible counterpart, which we designate CXOU J184454.6-025653. No coherent pulsations are detected, and no extended emission is seen.

S. S. Afonin, D. Espriu

We show how such important features of QCD as chiral symmetry breaking or the formation of a mass-gap can be directly traced from QCD sum rules for two point functions assuming, in the large number of colors limit, exact duality between the operator product expansion and the spectrum described by linearly (or nearly linear) rising Regge trajectories as predi

Zohar Nussinov, Cristian D. Batista, Eduardo Fradkin

We discuss symmetries intermediate between global and local and formalize the notion of dimensional reduction adduced from such symmetries. We apply this generalization to several systems including liquid crystalline phases of Quantum Hall systems, transition metal orbital systems, frustrated spin systems, (p+ip) superconducting arrays, and sliding Luttinger

Tin-Lun Ho, Hui Zhai

For decades, the conventional view is that an s-wave BCS superfluid can not support uniform spin polarization due to a gap $Δ$ in the quasiparticle excitation spectrum. We show that this is an artifact of the dismissal of quasiparticle interactions $V_{qp}^{}$ in the conventional approach at the outset. Such interactions can cause triplet fluctuations in the

Radu Tatar, Taizan Watari

In string theory, massless particles often originate from a symmetry breaking of a large gauge symmetry G to its subgroup H. The absence of dimension-4 proton decay in supersymmetric theories suggests that (\bar{D},L) are different from \bar{H}(\bar{\bf 5}) in their origins. In this article, we consider a possibility that they come from different irreducible

Yoji Michishita

We investigate classical solutions in closed bosonic string field theory and heterotic string field theory that are obtained order by order starting from solutions of the linearized equations of motion, and we discuss the ``field redefinitions'' which relate massless fields in the string field theory side and the low energy effective theory side. Mas

K. Z. Stanek, X. Dai, J. L. Prieto, D. An

We report on two recent z~4 gamma-ray bursts (GRBs), GRB 060206 and GRB 060210, for which we have obtained well-sampled optical light curves. Our data, combined with early optical data reported in the literature, shows unusual behavior for both afterglows. In R-band GRB 060206 (z=4.045) experienced a slow early decay, followed by a rapid increase in brightne

Kenneth Intriligator, Nathan Seiberg, David Shih

Dynamical supersymmetry breaking in a long-lived meta-stable vacuum is a phenomenologically viable possibility. This relatively unexplored avenue leads to many new models of dynamical supersymmetry breaking. Here, we present a surprisingly simple class of models with meta-stable dynamical supersymmetry breaking: N=1 supersymmetric QCD, with massive flavors.

Witold Maciejewski

When integrals in the standard Tremaine-Weinberg method are evaluated for the case of a realistic model of a doubly barred galaxy, their modifications introduced by the second rotating pattern are in accord with what can be derived from a simple extension of that method, based on separation of tracer's density. This extension yields a qualitative argumen

Frank Ferrari

Using generalized Konishi anomaly equations, it is known that one can express, in a large class of supersymmetric gauge theories, all the chiral operators expectation values in terms of a finite number of a priori arbitrary constants. We show that these constants are fully determined by the requirement of gauge invariance and an additional anomaly equation.

Vyjayanthi Chari, Jacob Greenstein

We study the structure of the category of integrable level zero representations with finite dimensional weight spaces of affine Lie algebras. We show that this category possesses a weaker version of the finite length property, namely that an indecomposable object has finitely many simple constituents which are non-trivial as modules over the corresponding lo

H. Balasin, D. Grumiller

Exact stationary axially symmetric solutions of the 4D Einstein equations with corotating pressureless perfect fluid sources are studied. A particular solution with approximately flat rotation curve is discussed in some detail. We find that simple Newtonian arguments overestimate the amount of matter needed to explain these curves by more than 30%. The cruci

Louis M. Pecora, Linda Moniz, Jonathan Nichols, Thomas L. Carroll

In the analysis of complex, nonlinear time series, scientists in a variety of disciplines have relied on a time delayed embedding of their data, i.e. attractor reconstruction. The process has focused primarily on heuristic and empirical arguments for selection of the key embedding parameters, delay and embedding dimension. This approach has left several long

Benoit Bertrand

Viro method plays an important role in the study of topology of real algebraic hypersurfaces. The T-primitive hypersurfaces we study here appear as the result of Viro's combinatorial patchworking when one starts with a primitive triangulation. We show that the Euler characteristic of the real part of such a hypersurface of even dimension is equal to the

Hsiang-nan Li, Satoshi Mishima

We point out that the B -> rho rho data have seriously constrained the possibility of resolving the B -> pi pi puzzle from the large observed B^0 -> pi^0 pi^0 branching ratio in the available theoretical approaches. The next-to-leading-order (NLO) contributions from the vertex corrections, the quark loops, and the magnetic penguin evaluated in the perturbati

J. Piasecki, J. Talbot, P. Viot

We consider a one-dimensional system consisting of a granular tracer particle of mass $M$ in a bath of thermalized particles each of mass $m$. When the mass ratio, $M/m$, is equal to the coefficient of restitution, $α$, the system maps to a a one-dimensional elastic gas. In this case, Boltzmann equation can be solved exactly. We also obtain expressions for t

T. I. Baturina, C. Strunk, M. R. Baklanov, A. Satta

We investigate ultrathin superconducting TiN films, which are very close to the localization threshold. Perpendicular magnetic field drives the films from the superconducting to an insulating state, with very high resistance. Further increase of the magnetic field leads to an exponential decay of the resistance towards a finite value. In the limit of low tem

Mir Faizal

In this paper we shall consistently third quantize modified gravity. Then we shall analyse certain aspects of virtual black holes in this third quantized modified gravity. We will see how a statistical mechanical origin for the Bekenstein-Hawking entropy naturally arises in this model. Furthermore, in this model the area and thus the entropy of a real macros

Bjorn Andreas, Gottfried Curio

We derive the Standard model gauge group together with chiral fermion generations from the heterotic string by turning on a Wilson line on a non-simply connected Calabi-Yau threefold with an SU(5) gauge group. For this we construct stable ${\bf Z_2}$-invariant $SU(4)\times U(1)$ bundles on an elliptically fibered cover Calabi-Yau threefold of special fibrati

P. Romano, S. Campana, G. Chincarini, J. Cummings

We present observations of GRB 060124, the first event for which both the prompt and the afterglow emission could be observed simultaneously and in their entirety by the three Swift instruments. Indeed, Swift-BAT triggered on a precursor ~570s before the main burst peak, and this allowed Swift to repoint the narrow field instruments to the burst position ~35

Eran Nevo

We generalize the notion of graph minors to all (finite) simplicial complexes. For every two simplicial complexes H and K and every nonnegative integer m, we prove that if H is a minor of K then the non vanishing of Van Kampen's obstruction in dimension m (a characteristic class indicating non embeddability in the (m-1)-sphere) for H implies its non vani

M. T. Yamashita, Lauro Tomio, A. Delfino, T. Frederico

We show that an independent four-body momentum scale $μ_{(4)}$ drives the tetramer binding energy for fixed trimer energy (or three-body scale $μ_{(3)}$) and large scattering length ($a$). The three- and four-body forces from the one-channel reduction of the atomic interaction near a Feshbach resonance disentangle $μ_{(4)}$ and $μ_{(3)}$. The four-body indep

Morihiko Saito

We show that the Bernstein-Sato polynomial (that is, the b-function) of a hyperplane arrangement with a reduced equation is calculable by combining a generalization of Malgrange's formula with the theory of Aomoto complexes due to Esnault, Schechtman, Terao, Varchenko, and Viehweg in certain cases. We prove in general that the roots are greater than -2 a

Marta Gomez-Reino, Claudio A. Scrucca

We perform a general study about the existence of non-supersymmetric minima with vanishing cosmological constant in supergravity models involving only chiral superfields. We study the conditions under which the matrix of second derivatives of the scalar potential is positive definite. We show that there exist very simple and strong necessary conditions for s

Ji-sheng Chen

The dimensionless universal coefficient $ξ$ defines the ratio of the unitary fermions energy density to that for the ideal non-interacting ones in the non-relativistic limit with T=0. The classical Thomson Problem is taken as a nonperturbative quantum many-body arm to address the ground state energy including the low energy nonlinear quantum fluctuation/corr

Qiang Zhao

We discuss the Okubo-Zweig-Iizuka (OZI) rule violation effects in $η_c\to VV$ in light of the new data from BES Collaboration. In particular, a possible non-vanishing branching ratio for $η_c\to ωϕ$ provides a hint of the degrees of OZI violations based on a recent factorization proposed for charmonium hadronic decays. The violation mechanism is studied via

G. A. Karagulyan

We show that for any infinite set of unit vectors $U$ in $\ZR^2$ the maximal operator defined by $$ H_Uf(x)=\sup_{u\in U}\bigg|\pv\int_{-\infty}^\infty \frac{f(x-tu)}{t}dt\bigg|,\quad x\in \ZR^2, $$ is not bounded in $L^2(\ZR^2)$.

A. B. Kaidalov, V. A. Khoze, A. D. Martin, M. G. Ryskin

It is shown that the observation of the spectra of leading neutrons from proton beams can be a good probe of absorptive and migration effects. We quantify how these effects modify the Reggeized pion-exchange description of the measurements of leading neutrons at HERA. We are able to obtain a satisfactory description of all the features of these data. We also

M. H. Dehghani, R. B. Mann

We generalize the quasilocal definition of the stress energy tensor of Einstein gravity to the case of third order Lovelock gravity, by introducing the surface terms that make the action well-defined. We also introduce the boundary counterterm that removes the divergences of the action and the conserved quantities of the solutions of third order Lovelock gra

Max A. Alekseyev

A two-dimensional threshold function of k-valued logic can be viewed as coloring of the points of a k x k square lattice into two colors such that there exists a straight line separating points of different colors. For the number of such functions only asymptotic bounds are known. We give an exact formula for the number of two-dimensional threshold functions

Kenji Goto, Masashi Fujisawa, Hidekazu Tanaka, Yoshiya Uwatoko

Magnetization and neutron elastic scattering measurements under a hydrostatic pressure were performed on KCuCl3, which is a three-dimensionally coupled spin dimer system with a gapped ground state. It was found that an intradimer interaction decreases with increasing pressure, while the sum of interdimer interactions increases. This leads to the shrinkage of

Toshihiro Kubo, Yasuhiro Tokura, Tsuyoshi Hatano, Seigo Tarucha

We theoretically investigate electron transport through an Aharonov-Bohm interferometer containing laterally coupled double quantum dots. We introduce the indirect coupling parameter $α$, which characterizes the strength of the coupling via the reservoirs between two quantum dots. $|α|=1$ indicates the strongest coupling, where only a single mode contributes

A. M. Stewart

It is shown that the mathematical form, obtained in a recent paper, for the angular momentum of the electromagnetic field in the vicinity of electric charge is equivalent to another form obtained previously by Cohen-Tannoudji, Dupont-Roc and Gilbert. In this version of the paper an improved derivation is given.

Reiko Miyaoka

A new proof of the homogeneity of isoparametric hypersurfaces with six simple principal curvatures (Dorfmeister-Neher's theorem) is given in a method applicable to the multiplicity two case.

Kenta Akune, Kei-ichi Maeda, Nobuyoshi Ohta

We present a detailed study of inflationary solutions in M-theory with higher order quantum corrections. We first exhaust all exact and asymptotic solutions of exponential and power-law expansions in this theory with quartic curvature corrections, and then perform a linear perturbation analysis around fixed points for the exact solutions in order to see whic

Iman Benmachiche, Thomas W. Grimm

The four-dimensional N=1 supergravity theories arising in compactifications of type IIA and type IIB on generalized orientifold backgrounds with background fluxes are discussed. The Kahler potentials are derived for reductions on SU(3) structure orientifolds and shown to consist of the logarithm of the two Hitchin functionals. These are functions of even and

Jason Schweinsberg

Let x and y be points chosen uniformly at random from $\Z_n^4$, the four-dimensional discrete torus with side length n. We show that the length of the loop-erased random walk from x to y is of order $n^2 (\log n)^{1/6}$, resolving a conjecture of Benjamini and Kozma. We also show that the scaling limit of the uniform spanning tree on $\Z_n^4$ is the Brownian

Huaxin Lin

We study a general Kishimoto's problem for automorphisms on simple C*-algebras with tracial rank zero. Let $A$ be a unital separable simple C*-algebra with tracial rank zero and let $α$ be an automorphism. Under the assumption that $α$ has certain Rokhlin property, we present a proof that $A\rtimes_α\Z$ has tracial rank zero. We also show that if the ind

F. E. Zimmer, A. André, M. D. Lukin, M. Fleischhauer

We present a detailed analysis of the recently demonstrated technique to generate quasi-stationary pulses of light [M. Bajcsy {\it et al.}, Nature (London) \textbf{426}, 638 (2003)] based on electromagnetically induced transparency. We show that the use of counter-propagating control fields to retrieve a light pulse, previously stored in a collective atomic

Ting Yu, J. H. Eberly

When a composite quantum state interacts with its surroundings, both quantum coherence of individual particles and quantum entanglement will decay. We have shown that under vacuum noise, i.e., during spontaneous emission, two-qubit entanglement may terminate abruptly in a finite time [T. Yu and J. H. Eberly, \prl {93}, 140404 (2004)], a phenomenon termed ent

F. de Melo, L. Aolita, F. Toscano, L. Davidovich

We propose an experimental procedure to directly measure the state of an electromagnetic field inside a resonator, corresponding to a superconducting transmission line, coupled to a Cooper-pair box (CPB). The measurement protocol is based on the use of a dispersive interaction between the field and the CPB, and the coupling to an external classical field tha

Gholamreza Faridfathi, Ramazan Sever

The supersymmetric solutions of PT-symmetric and Hermitian/non-Hermitian forms of quantum systems are obtained by solving the Schrodinger equation for the Exponential-Cosine Screened Coulomb potential. The Hamiltonian hierarchy inspired variational method is used to obtain the approximate energy eigenvalues and corresponding wave functions.

Jorge-Alejandro Reyes-Esqueda, Carlos I. Mendoza, Marcelo del Castillo-Mussot, Gerardo J. Vazquez

The effect of an external applied electric field on the electronic ground state energy of a quantum box with a geometry defined by a wedge is studied by carrying out a variational calculation. This geometry could be used as an approximation for a tip of a cantilever of an atomic force microscope. We study theoretically the Stark effect as function of the par

Jorge-Alejandro Reyes-Esqueda, Carlos I. Mendoza, Marcelo del Castillo-Mussot, Gerardo J. Vazquez

By using a variational calculation, we study the effect of an external applied electric field on the ground state of electrons confined in a quantum box with a geometry defined by a slice of a cake. This geometry is a first approximation for a tip of a cantilever of an Atomic Force Microscope (AFM). By modeling the tip with the slice, we calculate the electr

Ellie D'Hondt, Prakash Panangaden

We construct a formal framework for investigating epistemic and temporal notions in the context of distributed quantum computation. While we rely on structures developed earlier, we stress that our notion of quantum knowledge makes sense more generally in any agent-based model for distributed quantum systems. Several arguments are given to support our view t

Ellie D'Hondt, Prakash Panangaden

We develop a notion of predicate transformer and, in particular, the weakest precondition, appropriate for quantum computation. We show that there is a Stone-type duality between the usual state-transformer semantics and the weakest precondition semantics. Rather than trying to reduce quantum computation to probabilistic programming we develop a notion that

Ellie D'Hondt, Prakash Panangaden

It is well understood that the use of quantum entanglement significantly enhances the computational power of systems. Much of the attention has focused on Bell states and their multipartite generalizations. However, in the multipartite case it is known that there are several inequivalent classes of states, such as those represented by the W-state and the GHZ

Timir Datta

Gravitational field of many common objects are small but in the detectable sub microGal (Gal=g, free fall acceleration) range. Here we show that in a modern analog of the Archimedes problem, it is possible to estimate the interior density distribution of an object, by applying gauss law to the exterior gravity field data. With the development of wide band wi

C. L. Herzenberg

Although cosmic expansion at very small distances is usually dismissed as entirely inconsequential, it appears that these extraordinarily small effects may in fact have a real and significant influence on our world. Calculations suggest that the minute recessional velocities associated with regions encompassed by extended bodies may have a role in creating t

I Campos, J L Fernández-Chapou, A L Salas-Brito, C A Vargas

We analyse the motion of a sphere that rolls without slipping on a conical surface having its axis in the direction of the constant gravitational field of the Earth. This nonholonomic system admits a solution in terms of quadratures. We exhibit that the only circular of the system orbit is stable and furthermore show that all its solutions can be found using

Paul Indelicato, Eric-Olivier Le Bigot, Martino Trassinelli, Detlev Gotta

The average pixel distance as well as the relative orientation of an array of 6 CCD detectors have been measured with accuracies of about 0.5 nm and 50 $μ$rad, respectively. Such a precision satisfies the needs of modern crystal spectroscopy experiments in the field of exotic atoms and highly charged ions. Two different measurements have been performed by il

Wolfgang Singer, Timo A. Nieminen, Ursula J. Gibson, Norman R. Heckenberg

While the alignment and rotation of microparticles in optical traps have received increased attention recently, one of the earliest examples has been almost totally neglected the alignment of particles relative to the beam axis, as opposed to about the beam axis. However, since the alignment torques determine how particles align in a trap, they are directly

Kihong Kim, Dong-Hun Lee

A new version of the invariant imbedding theory for the propagation of coupled waves in inhomogeneous media is applied to the mode conversion of high frequency electromagnetic waves into electrostatic modes in cold, magnetized and stratified plasmas. The cases where the external magnetic field is applied perpendicularly to the direction of inhomogeneity and

Thomas Schaefer

We study the phase diagram of dense quark matter with an emphasis on the role of the strange quark mass. Our approach is based on two effective field theories (EFTs). The first is an EFT that describes quark quasi-particles near the Fermi surface. This EFT is valid at energies small compared to the chemical potential. The second is an EFT for the Goldstone m

E. Bauer, G. Garbarino, A. Parreno, A. Ramos

Recent progress has been experienced in the field of hypernuclear weak decay, especially concerning the ratio of the neutron- to proton-induced Lambda non-mesonic decay rates, G_n/G_p. Theoretical analyses of nucleon coincidence data have been performed in a finite nucleus framework. They led to the extraction of G_n/G_p values in agreement with pure theoret

A. D. Davies, A. E. Stuchbery, P. F. Mantica, P. M. Davidson

The shell structure underlying shape changes in neutron-rich nuclei near N=28 has been investigated by a novel application of the transient field technique to measure the first-excited state g factors in 38S and 40S produced as fast radioactive beams. There is a fine balance between proton and neutron contributions to the magnetic moments in both nuclei. The

I. Didenkulova, N. Zahibo, A. Kurkin, B. Levin

The problem of the sea wave runup on a beach is discussed in the framework of the rigorous solutions of the nonlinear shallow-water theory. Key and novel moment here is the accounting of the asymmetric waves when the face slope steepness exceeds the back slope steepness. It is shown that the runup height growth with increase of the face slope steepness meanw

Adrian Constantin, Rossen I. Ivanov

The Poisson brackets for the scattering data of the Camassa-Holm equation are computed. Consequently, the action-angle variables are expressed in terms of the scattering data.

Craig Westerland

We study a spectral sequence that computes the (mod 2) S^1-equivariant homology of the free loop space LM of a manifold M (the "string homology" of M). Using it and knowledge of the string topology operations on the homology of LM, we compute the string homology of M when M is a sphere or a projective space.

Krzysztof Kurdyka, Laurentiu Paunescu

Let $P(x,z)= z^d +\sum_{i=1}^{d}a_i(x)z^{d-i}$ be a polynomial, where $a_i$ are real analytic functions in an open subset $U$ of $\R^n$. If for any $x \in U$ the polynomial $z\mapsto P(x,z)$ has only real roots, then we can write those roots as locally lipschitz functions of $x$. Moreover, there exists a modification (a locally finite composition of blowing-

Gennady Lyubeznik

Let A be a commutative Noetherian local ring containing a field of characteristic p>0. The integer invariants $λ_{i,j}(A)$ have been introduced in an old paper of ours. In this paper we completely describe $λ_{d,d}(A)$, where d=dimA, in terms of the topology of SpecA.