May 2006 arXiv papers — page 4

P. X. Xu, V. M. Karpan, K. Xia, M. Zwierzycki

A systematic, quantitative study of the effect of interface roughness and disorder on the magnetoresistance of FeCo$|$vacuum$|$FeCo magnetic tunnel junctions is presented based upon parameter-free electronic structure calculations. Surface roughness is found to have a very strong effect on the spin-polarized transport while that of disorder in the leads (lea

L. Stanghellini, P. Garcia Lario, A. Manchado, J. V. Perea Calderon

Planetary nebulae (PNe) in the Magellanic Clouds (LMC, SMC) offer a unique opportunity to study both the population and evolution of low- and intermediate-mass stars in an environment which is free of the distance scale bias that hinder Galactic PN studies. The emission shown by PNe in the 5-40 $μ$m range is characterized by the presence of a combination of

David V. Bowen, Joseph F. Hennawi, Brice Menard, Doron Chelouche

We present the results of a search for metal absorption lines in the spectra of background QSOs whose sightlines pass close to foreground QSOs. We detect MgII(2796,2803) absorption in Sloan Digital Sky Survey (SDSS) spectra of four z>1.5 QSOs whose lines of sight pass within 26-98 kpc of lower redshift (z~0.5-1.5) QSOs. The 100% [4/4 pairs] detection of MgII

E. S. Levine, Leo Blitz, Carl Heiles

We produce a detailed map of the perturbed surface density of neutral hydrogen in the outer Milky Way disk demonstrating that the Galaxy is a non-axisymmetric multi-armed spiral. Spiral structure in the southern half of the Galaxy can be traced out to at least 25 kpc, implying a minimum radius for the gas disk. Overdensities in the surface density are coinci

D. Steeghs, T. R. Marsh, S. C. C. Barros, G. Nelemans

We present time-resolved spectroscopy of the optical counterpart to the proposed ultra-compact binary system V407 Vul (=RX J1914.4+2456). Our Gemini spectra resolve the 9.48 minute periodicity that has previously been reported for this source. We find that the optical counterpart is dominated by a reddened late-type spectrum of type G9V and contains solely u

Ken'ichi Nomoto, Nozomu Tominaga, Hideyuki Umeda, Chiaki Kobayashi

We present new nucleosynthesis yields as functions of the stellar mass, metallicity, and explosion energy (corresponding to normal supernovae and Hypernovae). We apply the results to the chemical evolution of the solar neighborhood. Our new yields are based on the new developments in the observational/theoretical studies of supernovae (SNe) and extremely met

G. Nelemans, P. G. Jonker

A short review of ultra-compact binaries, focused on ultra-compact X-ray binaries, is followed by a discussion of recent results of our VLT campaign to obtain optical spectra of (candidate) ultra-compact X-ray binaries. We find evidence for carbon/oxygen as well as helium/nitrogen discs and no evidence for (traces) of hydrogen. This suggests that the donors

Y. Ascasibar, R. Sevilla, G. Yepes, V. Mueller

The aim of the present work is to show that, contrary to popular belief, galaxy clusters are **not** expected to be self-similar, even when the only energy sources available are gravity and shock-wave heating. In particular, we investigate the scaling relations between mass, luminosity and temperature of galaxy groups and clusters in the absence of radiative

S. Galleti, L. Federici, M. Bellazzini, A. Buzzoni

Aims - We present the first results of a large spectroscopic survey of globular clusters and candidate globular clusters in the nearby M~31 galaxy. The survey is aimed at the classification of known candidate M~31 clusters and at the study of their kinematic properties. Methods - We obtained low-resolution spectroscopy (lambda/Dlambda~800-1300) for 133 targe

T. Sakamoto, L. Barbier, S. Barthelmy, J. Cummings

Thanks to the rapid position notice and response by HETE-2 and Swift, the X-ray afterglow emissions have been found for four recent short gamma-ray bursts (GRBs; GRB 050509b, GRB 050709, GRB 050724, and GRB 050813). The positions of three out of four short GRBs are coincident with galaxies with no current or recent star formation. This discovery tightens the

S A Wrathmall, D R Flower

Cross sections have been computed for rotational transitions of H2, induced by collisions with H atoms, using a recent H - H2 potential calculated by Mielke et al. [1]. These results are compared with those obtained with earlier potentials. Significant discrepancies are found with results deriving from the potential of Boothroyd et al. [3] in the low collisi

Kaori Nagashima, Takaaki Yokoyama

We report a statistical study of flares observed with the Soft X-ray Telescope (SXT) onboard Yohkoh in the year of 2000. We measure physical parameters of 77 flares, such as the temporal scale, the size, and the magnetic flux density and find that the sizes of flares tend to be distributed more broadly as the GOES class becomes weaker and that there is a low

Michael Doran, Joerg Jaeckel

We show that laboratory experiments cannot measure the absolute value of dark energy. All known experiments rely on electromagnetic interactions. They are thus insensitive to particles and fields that interact only weakly with ordinary matter. In addition, Josephson junction experiments only measure differences in vacuum energy similar to Casimir force measu

Robert A. Simcoe

New measurements of the z~6 intergalactic CIV abundance are presented, using moderate resolution IR spectra of two QSOs taken with GNIRS on Gemini South. These data were systematically searched for high redshift CIV absorption lines, using objective selection criteria. Comprehensive tests were performed to quantify sample incompleteness, as well as the rate

Camille Bonvin, Ruth Durrer, Martin Kunz

We show that the dipole of the luminosity distance is a useful observational tool which allows us to determine the Hubble parameter as a function of the redshift H(z). We determine the number of supernovae needed to achieve a given precision for H(z) and to distinguish between different models for dark energy. We analyse a sample of nearby supernovae and fin

Anke Knauf

This article is based on the author's PhD--thesis. We study geometric transitions on the supergravity level using the basic idea of arXiv:hep-th/0403288, where a pair of non-Kaehler backgrounds was constructed, which are related by a geometric transition. Here we embed this idea into an orientifold setup as suggested in arXiv:hep-th/0511099. The non-Kaeh

R. L. Thews

We confront preliminary RHIC data on J/Psi production in nuclear interactions with expectations which follow in scenarios involving charm quark recombination in a region of color deconfinement. The focus is on transverse momentum and rapidity spectra of the J/Psi, which carry a memory of the spectra of the charm quarks. In such a scenario, one predicts that

Gerald Bourgeois

One improves an algebraic attack of NTRU due to Silverman, Smart and Vercauteren; the latter considered the first 2 bits of a Witt vector attached to the research of the secret key; here the first 4 bits are considered, which provides additional equations of degrees 4 and 8.

Michio Hashimoto

We study a Nambu-Jona-Lasinio (NJL) type model with two-flavor quark matter in $β$-equilibrium. It turns out that the system develops instabilities in the dispersion relations of the diquark fields, i.e., the velocity squared $v^2$ becomes negative in a certain region of the electron chemical potential. The critical point is the same as that of the chromomag

Douglas Scott, J. P. Zibin

In the simplest cosmological models consistent with General Relativity, the total volume of the Universe is either finite or infinite, depending on whether or not the spatial curvature is positive. Current data suggest that the curvature is very close to flat, implying that one can place a lower limit on the total volume. In a Universe of finite age, the &#3

Chaur-Jian Hsu, David L. Johnson, Rohit A. Ingale, John J. Valenza

We develop the concept of frequency dependent effective mass, M(omega), of jammed granular materials which occupy a rigid cavity to a filling fraction of 48%, the remaining volume being air of normal room condition or controlled humidity. The dominant features of M(omega) provide signatures of the dissipation of acoustic modes, elasticity and aging effects i

V. Belokurov, N. W. Evans, M. J. Irwin, D. Lynden-Bell

We use Sloan Digital Sky Survey Data Release 5 photometry and spectroscopy to study a tidal stream that extends over 50 degrees in the North Galactic Cap. From the analysis of the path of the stream and the colors and magnitudes of its stars, the stream is about 20 kpc away at its nearest detection (the celestial equator). We detect a distance gradient -- th

Anna Ceresole, Gianguido Dall'Agata, Alexander Giryavets, Renata Kallosh

We develop a theory of static BPS domain walls in stringy landscape and present a large family of BPS walls interpolating between different supersymmetric vacua. Examples include KKLT models, STU models, type IIB multiple flux vacua, and models with several Minkowski and AdS vacua. After the uplifting, some of the vacua become dS, whereas some others remain

Dmitry V. Belyaev

Supersymmetric bulk-brane coupling in Horava-Witten and Randall-Sundrum scenarios, when considered in the orbifold (``upstairs'') picture, enjoys similar features: a modified Bianchi identity and a modified supersymmetry transformation for the ``orthogonal'' part of the gauge field. Using a toy model with a 5D vector multiplet in the bulk (li

A. Safonov

In the following, we describe preliminary results of searches for non-SM higgs bosons at the CDF and D0 experiments. Both experiments use data obtained in pp-bar collisions at the Tevatron at sqrt(s)=1.96 TeV.

A. V. Shurgaia, H. J. W. Mueller-Kirsten

The quantum properties of localized finite energy solutions to classical Euler-Lagrange equations are investigated using the method of collective coordinates. The perturbation theory in terms of inverse powers of the coupling constant $g$ is constructed, taking into account the conservation laws of momentum and angular momentum (invariance of the action with

R. Dabora, S. D. Servetto

In this work we focus on the general relay channel. We investigate the application of estimate-and-forward (EAF) to different scenarios. Specifically, we consider assignments of the auxiliary random variables that always satisfy the feasibility constraints. We first consider the multiple relay channel and obtain an achievable rate without decoding at the rel

C. D. White

In order to successfully describe DIS data, one must take heavy quark mass effects into account. This is often achieved using so called variable flavour number schemes, in which a parton distribution for the heavy quark species is defined above a suitable matching scale. At small x, one must also potentially include high energy corrections to this framework

Chuanwei Zhang, S. L. Rolston, S. Das Sarma

We analyze a scheme to manipulate quantum states of neutral atoms at individual sites of optical lattices using focused laser beams. Spatial distributions of focused laser intensities induce position-dependent energy shifts of hyperfine states, which, combined with microwave radiation, allow selective manipulation of quantum states of individual target atoms

Michael Nakamaye, Nicolas Ratazzi

We establish an improvement of Philippon's zero estimates primarily in the multiplicity setting. The improvement is made possible by a more geometric approach and in particular the use of Seshadri constants.

Artur Avila, Jairo Bochi

Let $M$ be a smooth compact manifold (maybe with boundary, maybe disconnected) of any dimension $d \ge 1$. We consider the set of $C^1$ maps $f:M\to M$ which have no absolutely continuous (with respect to Lebesgue) invariant probability measure. We show that this is a residual (dense $G_δ) set in the $C^1$ topology. In the course of the proof, we need a gene

L. Sudheendra, V. Moshnyaga, B. Damaschke, K. Samwer

In a manganite film without quenched disorder, we show texturing in the form of insulating and metallic stripes above and below Curie temperature (Tc), respectively, by high resolution scanning tunneling microscopy/spectroscopy (STM/STS). The formation of these stripes involves competing orbital and charge orders, and are an outcome of overlapping electron w

Florian Gmeiner, Frederik Witt

For Hitchin's generalised geometries we introduce and analyse the concept of a structured submanifold which encapsulates the classical notion of a calibrated submanifold. Under a suitable integrability condition on the ambient geometry, these generalised calibrated cycles minimise a functional occurring as D-brane energy in type II string theories, invol

E. Schinnerer, T. Boeker, E. Emsellem, U. Lisenfeld

We present high angular resolution ~1" and 0.6" mm-interferometric observations of the 12CO(1-0) and 12CO(2-1) line emission in the central 300pc of the late-type spiral galaxy NGC6946. The data, obtained with the IRAM Plateau de Bure Interferometer (PdBI), allow the first detection of a molecular gas spiral in the inner ~10" (270pc) with a large

M. Capua, S. Fazio, R. Fiore, L. Jenkovszky

A factorized Regge-pole model for deeply virtual Compton scattering is suggested. The use of an effective logarithmic Regge-Pomeron trajectory provides for the description of both ``soft'' (small $|t|$) and ``hard'' (large $|t|$) dynamics. The model contains explicitly the photoproduction and the DIS limits and fits the existing HERA data on

Enrique Ruiz Arriola, Wojciech Broniowski

We analyze the pi -> gamma* gamma* amplitude in the framework of radial Regge models in the large-Nc limit. With the assumption of similarity of the asymptotic Regge rho and omega meson spectra we find that the pion distribution amplitude is constant in the large-$N_c$ limit at the scale Q0 where the QCD radiative corrections are absent -- a result found ear

Lisa J. Kewley, Brent Groves, Guinevere Kauffmann, Tim Heckman

We present an analysis of the host properties of 85224 emission-line galaxies from the Sloan Digital Sky Survey. We show that Seyferts and LINERs form clearly separated branches on the standard optical diagnostic diagrams. We derive a new empirical classification scheme which cleanly separates star-forming galaxies, composite AGN-HII galaxies, Seyferts and L

Michael C. Garrett, David L. Feder

The cluster state, the highly entangled state that is the central resource for one-way quantum computing, can be efficiently generated in a variety of physical implementations via global nearest-neighbor interactions. In practice, a systematic phase error is expected in the entangling process, resulting in imperfect cluster states. We present a stochastic me

Andrea Morello, P. C. E. Stamp, Igor S. Tupitsyn

Experiments involving phase coherent dynamics of networks of spins, such as echo experiments, will only work if decoherence can be suppressed. We show here, by analyzing the particular example of a crystalline network of Fe8 molecules, that most decoherence typically comes from pairwise interactions (particularly dipolar interactions) between the spins, whic

Ruth Lazkoz, Roy Maartens, Elisabetta Majerotto

We investigate a simple braneworld model in which the universe contains only cold dark matter and a cosmological constant, but the effective dark energy is phantom-like because of extra-dimensional gravity effects. Modified gravity screens the cosmological constant Lambda, allowing for a larger Lambda. In practice, observations do not favour any significant

Jeffrey Bub

It is well-known that Shor's factorization algorithm, Simon's period-finding algorithm, and Deutsch's original XOR algorithm can all be formulated as solutions to a hidden subgroup problem. Here the salient features of the information-processing in the three algorithms are presented from a different perspective, in terms of the way in which the a

Krishna Rajagopal, Rishi Sharma

We analyze and compare candidate crystal structures for the crystalline color superconducting phase that may arise in cold, dense but not asymptotically dense, three-flavor quark matter. We determine the gap parameter Delta and free energy Omega(Delta) for many possible crystal structures within a Ginzburg-Landau approximation, evaluating Omega(Delta) to ord

Mohsen Alishahiha, Hajar Ebrahim

By making use of the entropy function formalism we study the generalized attractor equations in the four dimensional N=2 supergravity in presence of higher order corrections. This result might be used to understand a possible ensemble one could associate to an extremal black hole.

Johan Andersson, Gautami Bhowmik

We establish correspondances between factorisations of finite abelian groups (direct factors, unitary factors, non isomorphic subgroup classes) and factorisations of integer matrices. We then study counting functions associated to these factorisations and find average orders.

Bernd A. Berg, Alexei Bazavov

For compact U(1) lattice gauge theory (LGT) we have performed a finite size scaling analysis on $N_τ N_s^3$ lattices for $N_τ$ fixed by extrapolating spatial volumes of size $N_s\le 18$ to $N_s\to\infty$. Within the numerical accuracy of the thus obtained fits we find for $N_τ=4$, 5 and~6 second order critical exponents, which exhibit no obvious $N_τ$ depend

Chian-Shu Chen, Kingman Cheung, Tzu-Chiang Yuan

Little Higgs models with $T$-parity provide a stable neutral particle $A_H$, the lightest $T$-odd particle (LTP), which was recently proposed to explain the cold dark matter of the Universe. In the coannihilation region of the LTP with the Little Higgs partner of the light quark $Q_H$, we propose novel signatures for its detection at hadronic colliders by se

Rashmi R. Nayak, Kamal L. Panigrahi, Sanjay Siwach

A class of time dependent pp-waves with NS-NS flux in type IIA string theory is considered. The background preserves 1/4 supersymmetry and may provide a toy model of Big Bang cosmology with non trivial flux. At the Big Bang singularity in early past, the string theory is strongly coupled and Matrix string model can be used to describe the dynamics. We also c

J. Danon, Yu. V. Nazarov

We study electronic transport through a ferromagnet normal-metal ferromagnet system and we investigate the effect of hyperfine interaction between electrons and nuclei in the normal-metal part. A switching of the magnetization directions of the ferromagnets causes nuclear spins to precess. We show that the effect of this precession on the current through the

Andrzej Okolow

A simple diffeomorphism invariant theory of connections with the non-compact structure group R of real numbers is quantized. The theory is defined on a four-dimensional 'space-time' by an action resembling closely the self-dual Plebanski action for general relativity. The space of quantum states is constructed by means of projective techniques by Kij

Hao Fu, P. R. Berman

An atom recoils when it undergoes spontaneous decay. In this paper we present a microscopic calculation of the recoil of a source atom imbedded in a dielectric medium. We find that the source atom recoils with the canonical photon momentum $n\hbar k_{0,}$ where $n$ is the index of refraction and $\hbar k_{0}$ is the photon momentum calculated at the source a

Jean-Marc Drézet

The primitive curves are the multiple curves that can be locally embedded in smooth surfaces (we will always suppose that the associated reduced curves are smooth). These curves have been defined and studied by C. Banica and O.Forster in 1984. In 1995, D. Bayer and D. Eisenbud gave a complete description of the double curves. We give here a parametrization o

Simon P Morgan

Regularization functionals that lower level set boundary length when used with L^1 fidelity functionals on signal de-noising on images create artifacts. These are (i) rounding of corners, (ii) shrinking of radii, (iii) shrinking of cusps, and (iv) non-smoothing of staircasing. Regularity functionals based upon total curvature of level set boundaries do not c

N. Lazarides, M. Eleftheriou, G. P. Tsironis

Magnetic metamaterials composed of split-ring resonators or $U-$type elements may exhibit discreteness effects in THz and optical frequencies due to weak coupling. We consider a model one-dimensional metamaterial formed by a discrete array of nonlinear split-ring resonators with each ring interacting with its nearest neighbours. On-site nonlinearity and weak

Christopher Deninger

In recent years Lichtenbaum has conjectured a description for the special values of Hasse--Weil zeta functions in terms of ``Weil-étale cohomology''. In earlier papers we studied a class of foliated dynamical systems which had some similarities with arithmetic schemes. Assuming that certain zeta regularized determinants exist we now prove an analogue

Rabin Banerjee, Binayak Dutta Roy, Saurav Samanta

A planar phase space having both position and momentum noncommutativity is defined in a more inclusive setting than that considered elsewhere. The dynamics of a particle in a gravitational quantum well in this space is studied. The use of the WKB approximation and the virial theorem enable analytic discussions on the effect of noncommutativity. Consistent re

Christopher Deninger, Klaus Schmidt

We prove an entropy formula for certain expansive actions of a countable discrete residually finite group $Γ$ by automorphisms of compact abelian groups in terms of Fuglede-Kadison determinants. This extends an earlier result proved by the first author under somewhat more restrictive conditions. The main tools for this generalization are a representation of

Olli-Pentti Saira, Ville Bergholm, Teemu Ojanen, Mikko Mottonen

We study the dynamics of quantum systems under classical and quantum noise, focusing on decoherence in qubit systems. Classical noise is described by a random process leading to a stochastic temporal evolution of a closed quantum system, whereas quantum noise originates from the coupling of the microscopic quantum system to its macroscopic environment. We de

A. J. van Marle, N. Langer, A. Achterberg, G. Garcia-Segura

The progenitor stars of long Gamma-Ray Bursts (GRBs) are thought to be Wolf-Rayet stars, which generate a massive and energetic wind. Nevertheless, about 25 percent of all GRB afterglows light curves indicate a constant density medium close to the exploding star. We explore various ways to produce this, by creating situations where the wind termination shock

E. V. Vakarin, J. P. Badiali

A microscopic mechanism of low-pressure insertion and separation of chain-like molecules in host matrices is proposed. It is shown that the intramolecular correlations combined to appropriate host activities are responsible for a low-pressure condensation of chain molecules. This allows recover a fine structure of the isotherms and to explain recent experime

Michel R. P. Planat, Metod Saniga, Maurice R. Kibler

The paper explores the basic geometrical properties of the observables characterizing two-qubit systems by employing a novel projective ring geometric approach. After introducing the basic facts about quantum complementarity and maximal quantum entanglement in such systems, we demonstrate that the 15$\times$15 multiplication table of the associated four-dime

Shinji Maedan

We investigate the possibility of the spin polarization of quark matter at zero temperature and moderate baryon density.The Nambu-Jona-Lasinio (NJL) model including interactions in vector and axial-vector channel (coupling constant $G_2$) as well as scalar and pseudoscalar channel (coupling constant $G_1$) is used, and the self consistent equations for the s

Emanuela Bianchi, Julio Largo, Piero Tartaglia, Emanuela Zaccarelli

We report theoretical and numerical evaluations of the phase diagram for patchy colloidal particles of new generation. We show that the reduction of the number of bonded nearest neighbours offers the possibility of generating liquid states (i.e. states with temperature $T$ lower than the liquid-gas critical temperature) with a vanishing occupied packing frac

J. Burgdörfer, C. Lemell, K. Schiessl, B. Solleder

Progress in the study of collisions of multiply charged ions with surfaces is reviewed with the help of a few recent examples. They range from fundamental quasi-one electron processes to highly complex ablation and material modification processes. Open questions and possible future directions will be discussed.

Aleksandar Ivić

This paper gives a survey of known results concerning the Laplace transform $$ L_k(s) := \int_0^\infty |ζ(1/2+ ix)|^{2k}{\rm e}^{-sx}{\rm d} x \qquad(k \in N, \R s > 0), $$ and the (modified) Mellin transform $$ {\cal Z}_k(s) := \int_1^\infty|ζ(1/2+ ix)|^{2k}x^{-s}{\rm d} x\qquad(k\in N), $$ where the integral is absolutely convergent for $\R s \ge c(k) > 1$

Lorenzo Zambotti

We study the density of the time average of the Brownian meander/excursion over the time interval [0,1]. Moreover we give an expression for the Brownian meander/excursion conditioned to have a fixed time average.

Michiel Snoek, H. T. C. Stoof

We investigate quantum and temperature fluctuations of a vortex lattice in a one-dimensional optical lattice. We discuss in particular the Bloch bands of the Tkachenko modes and calculate the correlation function of the vortex positions along the direction of the optical lattice. Because of the small number of particles in the pancake Bose-Einstein condensat

A. Conca, M. Jourdan, C. Herbort, H. Adrian

Epitaxial thin films of the highly spin polarized Heusler compound Co2Cr0.6Fe0.4Al are deposited by dc magnetron sputtering. It is shown by XRD and TEM investigations how the use of an Fe buffer layer on MgO(100) substrates supports the growth of highly ordered Co2Cr0.6Fe0.4Al at low deposition temperatures. The as grown samples show a relatively large order

V. D. Rusov, V. Yu. Maksymchuk, R. Ilić, V. M. Pavlovych

A model of precursor manifestation mechanisms, stimulated by tectonic activity and some peculiarities of observer strategy, whose main task is the effective measurement of precursors in the spatial area of their occurrence on the Earth's daylight, are considered. In particular, the applicability of Dobrovolsky's approximation is analyzed, when an unp

A. T. Filippov

We discuss some problems related to dimensional reductions of gravity theories to two-dimensional and one-dimensional dilaton gravity models. We first consider the most general cylindrical reductions of the four-dimensional gravity and derive the corresponding (1+1)-dimensional dilaton gravity, paying a special attention to a possibility of producing nontriv

Hu Zhan

We explore the complementarity between two tomographic probes of the universe: baryon acoustic oscillations (BAOs) and weak lensing (WL). We find that photometric measurements of BAOs alone do not provide very tight constraints on the dark energy equation of state parameters, partially due to our uncertain knowledge of the galaxy bias. WL, on the other hand,

E. M. Epshtein, Yu. V. Gulyaev, P. E. Zilberman

Boundary conditions are derived that determine the penetration of spin current through an interface of two non-collinear ferromagnets with an arbitrary angle between their magnetization vectors. We start from the well-known transformation properties of an electron spin wave functions under the rotation of a quantization axis. It allows directly find the conn

Gabriel G. Carlo, Giuliano Benenti, Giulio Casati, Sandro Wimberger

We present a very simple model for realizing directed transport with cold atoms in a pair of periodically flashed optical lattices. The origin of this ratchet effect is explained and its robustness demonstrated under imperfections typical of cold atom experiments. We conclude that our model offers a clear-cut way to implement directed transport in an atom op

David Rapetti, Steven W. Allen, Mustafa A. Amin, Roger D. Blandford

We present and employ a new kinematical approach to cosmological `dark energy' studies. We construct models in terms of the dimensionless second and third derivatives of the scale factor a(t) with respect to cosmic time t, namely the present-day value of the deceleration parameter q_0 and the cosmic jerk parameter, j(t). An elegant feature of this parame

H. Mohseni Sadjadi, M. Alimohammadi

Assuming the Hubble parameter is a continuous and differentiable function of comoving time, we investigate necessary conditions for quintessence to phantom phase transition in quintom model. For power-law and exponential potential examples, we study the behavior of dynamical dark energy fields and Hubble parameter near the transition time, and show that the

Ee Chang-Young, Hoil Kim

In this paper we investigate the theta vector and quantum theta function over noncommutative T^4 from the embedding of R x Z^2. Manin has constructed the quantum theta functions from the lattice embedding into vector space (x finite group). We extend Manin's construction of the quantum theta function to the embedding of vector space x lattice case. We fi

Toshiki Maruyama, Toshitaka Tatsumi, Tomoki Endo, Satoshi Chiba

We review our recent works about ``pasta'' structures following the first-order phase transition in dense matter, which correspond to the structured mixed phases with geometrical symmetries. Three kinds of phase transitions at different density ranges are examined as the stages of pasta structures: liquid-gas phase transition at subnuclear density, k

Paul E. Barclay, Benjamin Lev, Kartik Srinivasan, Oskar Painter

Micron scale silicon nitride (SiN_x) microdisk optical resonators are demonstrated with Q = 3.6 x 10^6 and an effective mode volume of 15 (λ/ n)^3 at near visible wavelengths. A hydrofluoric acid wet etch provides sensitive tuning of the microdisk resonances, and robust mounting of a fiber taper provides efficient fiber optic coupling to the microdisks while

Roni Waldman, Zalman Barkat

We explore the hypothesis, that helium stars in a certain mass range can evolve to a carbon core explosion similar to what is widely accepted as an explanation for the SN I phenomenon. This should happen when their carbon-oxygen core grows thanks to the helium shell burning above the core. We found that in the mass range of about 1.7-2.2 Msun, indeed this ca

O. G. Isaeva, V. A. Osipov

We formulate and analyze a mathematical model describing immune response to avascular tumor under the influence of immunotherapy and chemotherapy and their combinations as well as vaccine treatments. The effect of vaccine therapy is considered as a parametric perturbation of the model. In the case of a weak immune response, neither immunotherapy nor chemothe

Bhabani Prasad Mandal, Saurabh Gupta

We consider a couple of examples to study the pseudo-Hermitian interaction in relativistic quantum mechanics. Rasbha interaction, commonly used to study the spin Hall effect, is considered with imaginary coupling. The corresponding Dirac Hamiltonian is shown to be parity pseudo-Hermitian. In the other example we consider parity pseudo-Hermitian scalar intera

Reiko Miyaoka

We show that two of the Bryant-Salamon G_2-manifolds have a simple topology ; homeomorphic to the complement of some submanifolds of the 7-dimensional sphere. In this connection, we show there exists a complete Ricci-flat (non-flat) metric on the complement of an m-dimensional sphere in an n-dimensional sphere for some n-1>m. We also give many examples of sp

Masayuki Ohzeki, Hidetoshi Nishimori

We calculate the internal energy of the Potts model on the triangular lattice with two- and three-body interactions at the transition point satisfying certain conditions for coupling constants. The method is a duality transformation. Therefore we have to make assumptions on uniqueness of the transition point and that the transition is of second order. These

Jarrett L. Johnson, Volker Bromm

We investigate the evolution of the primordial gas surrounding the first massive black holes formed by the collapse of Population III stars at redshifts z > 20. Carrying out three-dimensional hydrodynamical simulations using GADGET, we study the dynamical, thermal and chemical evolution of the first relic H II regions. We also carry out simulations of the me

Xiao-Hu Zheng, Ping Dong, Zheng-Yuan Xue, Zhuo-Liang Cao

A scheme for the generation of the cluster states based on the Josephson charge qubit is proposed. The two-qubit generating case is first introduced, and then generalized to multi-qubit case. The scheme is simple and easily manipulated, because any two charge qubits can be selectively and effectively coupled by a common inductance. More manipulations can be

G. Hetet, A. Peng, M. T. Johnsson, M. T. L. Hsu

An inconsistency was found in the equations used to calculate the variance of the quadrature fluctuations of a field propagating through a medium demonstrating electromagnetically induced transparency (EIT). The decoherence term used in our original paper introduces inconsistency under weak probe approximation. In this erratum we give the Bloch equations wit

Vivi Petersen, Klaus Molmer

We present a theoretical analysis of the ability of atomic magnetometers to estimate a fluctuating magnetic field. Our analysis makes use of a Gaussian state description of the atoms and the probing field, and it presents the estimator of the field and a measure of its uncertainty which coincides in the appropriate limit with the achievements for a static fi

T. Hakioglu, A. Tegmen, B. Demircioglu

A theory of non-unitary-invertible as well as unitary canonical transformations is formulated in the context of Weyl's phase space representations. That all quantum canonical transformations without an explicit $\hbar$ dependence are also classical mechanical and vice versa is demonstrated in the phase space. Contrary to some earlier results, it is also

Bernhard G. Bodmann, David W. Kribs, Vern I. Paulsen

The central issue in this article is to transmit a quantum state in such a way that after some decoherence occurs, most of the information can be restored by a suitable decoding operation. For this purpose, we incorporate redundancy by mapping a given initial quantum state to a messenger state on a larger-dimensional Hilbert space via a $C^*$-algebra embeddi

G. Lima, Leonardo Neves, Ivan F. Santos, J. G. Aguirre Gómez

We show the propagation of entangled states of high-dimensional quantum systems. The qudits states were generated using the transverse correlation of the twin photons produced by spontaneous parametric down-conversion. Their free-space distribution was performed at the laboratory scale and the propagated states maintained a high-fidelity with their original

P. B. M. Sousa, R. V. Ramos

Quantum computation has attracted much attention, among other things, due to its potentialities to solve classical NP problems in polynomial time. For this reason, there has been a growing interest to build a quantum computer. One of the basic steps is to implement the quantum circuit able to realize a given unitary operation. This task has been solved using

Juan Carlos Garcia-Escartin, Pedro Chamorro-Posada

We show that universal quantum logic can be achieved using only linear optics and a quantum shutter device. With these elements, we design a quantum memory for any number of qubits and a CNOT gate which are the basis of a universal quantum computer. An interaction-free model for a quantum shutter is given.

S C Tiwari

A critical review of frequency-shift phenomena a la Doppler effect is presented. The importance of Fermi's theory of 1932 is pointed out, and it is argued that there exists a gap in our understanding of this phenomena at a fundamental level. Alternative mechanism in terms of photon number oscillations is suggested for polarization changing experiments. T

Emmanuel Tannenbaum

This paper develops a set of simplified dynamical models with which to explore the conditions under which division of labor leads to optimized system output, as measured by the rate of production of a given product. We consider two models: In the first model, we consider the flow of some resource into a compartment, and the conversion of this resource into s

Sitabhra Sinha, Raj Kumar Pan

The nature of fluctuations in the Indian financial market is analyzed in this paper. We have looked at the price returns of individual stocks, with tick-by-tick data from the National Stock Exchange (NSE) and daily closing price data from both NSE and the Bombay Stock Exchange (BSE), the two largest exchanges in India. We find that the price returns in India

Anirban Chakraborti

We present an outlook of the studies on correlations in the price timeseries of stocks, discussing the construction and applications of "asset tree". The topic discussed here should illustrate how the complex economic system (financial market) enrichens the list of existing dynamical systems that physicists have been studying for long.

Pekka Ikonen, Mikhail Lapine, Igor Nefedov, Sergei Tretyakov

We present a general dyadic vector circuit formalism, applicable for uniaxial magneto-dielectric slabs, with strong spatial dispersion explicitly taken into account. This formalism extends the vector circuit theory, previously introduced only for isotropic and chiral slabs. Here we assume that the problem geometry imposes strong spatial dispersion only in th

Eduardo Tavares Costa, Jorge Andre Girao Albuquerque

In this work, we have studied the MTF optimisation relative to the detector aperture of four digital dental X-ray image systems: 1) Digora and Denoptix systems, based on PSPL detectors; 2) CDR and Sens-A-Ray 2000, based on CCD detectors. The MTF was evaluated by ERF method and linearized as a Gaussian process. The CCD based systems presented Gaussian charact

M. Yokoyama, T. Nobuhara, M. Taguchi, T. Nakaya

The multi-pixel photon counter (MPPC) is a newly developed photodetector with an excellent photon counting capability. It also has many attractive features such as small size, high gain, low operation voltage and power consumption, and capability of operating in magnetic fields and in room temperature. The basic performance of samples has been measured. A ga

L. M. Chen, H. Kotaki, K. Nakajima, J. Koga

An experiment for studying laser self-guiding has been carried out for the high power ultrashort pulse laser interaction with an underdense plasma slab. Formation of an extremely long plasma channel and its bending are observed when the laser pulse power is much higher than the critical power for relativistic self-focusing. The long self-guiding channel form

R. Turchetta

This paper reviews the development of CMOS Monolithic Active Pixel Sensors (MAPS) for future vertex detectors. MAPS are developed in a standard CMOS technology. In the imaging field, where the technology found its first applications, they are also known as CMOS Image Sensors. The use of MAPS as a detector for particle physics was first proposed at the end of