Results for "M. Ashdown"

total 205282took 0.36s
Fast optimal CMB power spectrum estimation with Hamiltonian samplingAug 22 2007May 14 2008We present a method for fast optimal estimation of the temperature angular power spectrum from observations of the cosmic microwave background. We employ a Hamiltonian Monte Carlo (HMC) sampler to obtain samples from the posterior probability distribution ... More
A deconvolution map-making method for experiments with circular scanning strategiesJun 21 2011Aims. To investigate the performance of a deconvolution map-making algorithm for an experiment with a circular scanning strategy, specifically in this case for the analysis of Planck data, and to quantify the effects of making maps using simplified approximations ... More
All-sky component separation for the Planck missionMay 24 2001Jun 19 2002An harmonic-space maximum-entropy method (MEM) is presented for separating the emission from different physical components in all-sky observations by the forthcoming Planck satellite. The analysis is performed at full Planck resolution, with a pixel size ... More
Fast Pixel Space Convolution for CMB Surveys with Asymmetric Beams and Complex Scan Strategies: FEBeCoPMay 11 2010Dec 22 2010Precise measurement of the angular power spectrum of the Cosmic Microwave Background (CMB) temperature and polarization anisotropy can tightly constrain many cosmological models and parameters. However, accurate measurements can only be realized in practice ... More
A Solution for Dynamic Spectrum Management in Mission-Critical UAV NetworksApr 16 2019In this paper, we study the problem of spectrum scarcity in a network of unmanned aerial vehicles (UAVs) during mission-critical applications such as disaster monitoring and public safety missions, where the pre-allocated spectrum is not sufficient to ... More
Optimal Relaying Beamforming in Multiple Access Broadcast Channel (MABC) Bidirectional Cognitive Radio Networks in Presence of InterferersSep 07 2018In this paper, a general cognitive radio system consisting of a set of users with different level of spectrum access including two primary transceivers and several types of secondary users is considered. It is assumed that two secondary users operate ... More
Leader-follower based Coalition Formation in Large-scale UAV Networks, A Quantum Evolutionary ApproachFeb 18 2018The problem of decentralized multiple Point of Interests (PoIs) detection and associated task completion in an unknown environment with multiple resource-constrained and self-interested Unmanned Aerial Vehicles (UAVs) is studied. The UAVs form several ... More
Exploring Cosmic Origins with CORE: The InstrumentMay 05 2017May 22 2017We describe a space-borne, multi-band, multi-beam polarimeter aiming at a precise and accurate measurement of the polarization of the Cosmic Microwave Background. The instrument is optimized to be compatible with the strict budget requirements of a medium-size ... More
A Unified Framework for Joint Mobility Prediction and Object Profiling of Drones in UAV NetworksJul 31 2018In recent years, using a network of autonomous and cooperative unmanned aerial vehicles (UAVs) without command and communication from the ground station has become more imperative, in particular in search-and-rescue operations, disaster management, and ... More
Distributed Cooperative Spectrum Sharing in UAV Networks Using Multi-Agent Reinforcement LearningNov 13 2018In this paper, we develop a distributed mechanism for spectrum sharing among a network of unmanned aerial vehicles (UAV) and licensed terrestrial networks. This method can provide a practical solution for situations where the UAV network may need external ... More
Making Maps from Planck LFI 30GHz Data with Asymmetric Beams and Cooler NoiseJun 19 2008Apr 09 2009The Planck satellite will observe the full sky at nine frequencies from 30 to 857 GHz. The goal of this paper is to examine the effects of four realistic instrument systematics in the 30 GHz frequency maps: non-axially-symmetric beams, sample integration, ... More
Harmonic analysis of cosmic microwave background data I: ring reductions and point-source catalogueDec 12 2001We present a harmonic model for the data analysis of an all-sky cosmic microwave background survey, such as Planck, where the survey is obtained through ring-scans of the sky. In this model, resampling and pixelisation of the data are avoided. The spherical ... More
Wildfire Monitoring in Remote Areas using Autonomous Unmanned Aerial VehiclesApr 15 2019In this paper, we propose a drone-based wildfire monitoring system for remote and hard-to-reach areas. This system utilizes autonomous unmanned aerial vehicles (UAVs) with the main advantage of providing on-demand monitoring service faster than the current ... More
Making sky maps from Planck dataJun 14 2006We compare the performance of multiple codes written by different groups for making polarized maps from Planck-sized, all-sky cosmic microwave background (CMB) data. Three of the codes are based on a destriping algorithm; the other three are implementations ... More
Making Maps from Planck LFI 30GHz DataFeb 19 2007This paper is one of a series describing the performance and accuracy of map-making codes as assessed by the Planck CTP working group. We compare the performance of multiple codes written by different groups for making polarized maps from Planck-sized, ... More
Residual noise covariance for Planck low-resolution data analysisMay 31 2009Aims: Develop and validate tools to estimate residual noise covariance in Planck frequency maps. Quantify signal error effects and compare different techniques to produce low-resolution maps. Methods: We derive analytical estimates of covariance of the ... More
Planck intermediate results. XXIV. Constraints on variation of fundamental constantsJun 29 2014Any variation of the fundamental physical constants, and more particularly of the fine structure constant, $\alpha$, or of the mass of the electron, $m_e$, would affect the recombination history of the Universe and cause an imprint on the cosmic microwave ... More
Planck 2018 results. IX. Constraints on primordial non-GaussianityMay 14 2019We analyse the Planck full-mission cosmic microwave background (CMB) temperature and E-mode polarization maps to obtain constraints on primordial non-Gaussianity (NG). We compare estimates obtained from separable template-fitting, binned, and modal bispectrum ... More
QUIJOTE Scientific results. III. Microwave spectrum of intensity and polarization in the Taurus molecular cloud Complex and L1527Dec 19 2018Jan 14 2019We present new intensity and polarization observations of the Taurus molecular cloud (TMC) region in the frequency range 10-20 GHz with the Multi-Frequency Instrument (MFI) mounted on the first telescope of the QUIJOTE experiment. From the combination ... More
All-sky convolution for polarimetry experimentsAug 16 2000Sep 21 2000We discuss all-sky convolution of the instrument beam with the sky signal in polarimetry experiments, such as the Planck mission which will map the temperature anisotropy and polarization of the cosmic microwave background (CMB). To account properly for ... More
Measurements of the Intensity and Polarization of the Anomalous Microwave Emission in the Perseus molecular complex with QUIJOTEJan 19 2015Anomalous microwave emission (AME) has been observed in numerous sky regions, in the frequency range ~10-60 GHz. One of the most scrutinized regions is G159.6-18.5, located within the Perseus molecular complex. In this paper we present further observations ... More
Planck 2013 results. XIX. The integrated Sachs-Wolfe effectMar 20 2013Nov 25 2013Based on CMB maps from the 2013 Planck Mission data release, this paper presents the detection of the ISW effect, i.e., the correlation between the CMB and large-scale evolving gravitational potentials. The significance of detection ranges from 2 to 4 ... More
Planck 2015 results. XIV. Dark energy and modified gravityFeb 05 2015May 03 2016We study the implications of Planck data for models of dark energy (DE) and modified gravity (MG), beyond the cosmological constant scenario. We start with cases where the DE only directly affects the background evolution, considering Taylor expansions ... More
Planck 2013 results. II. Low Frequency Instrument data processingMar 20 2013Feb 02 2014We describe the data processing pipeline of the Planck Low Frequency Instrument (LFI) data processing centre (DPC) to create and characterize full-sky maps based on the first 15.5 months of operations at 30, 44 and 70 GHz. In particular, we discuss the ... More
Planck Early Results: The Planck missionJan 11 2011Jun 16 2011The European Space Agency's Planck satellite was launched on 14 May 2009, and has been surveying the sky stably and continuously since 13 August 2009. Its performance is well in line with expectations, and it will continue to gather scientific data until ... More
Planck 2013 results. XIV. Zodiacal emissionMar 20 2013Apr 14 2014The Planck satellite provides a set of all-sky maps at nine frequencies from 30 GHz to 857 GHz. Planets, minor bodies, and diffuse interplanetary dust emission (IPD) are all observed. The IPD can be separated from Galactic and other emissions because ... More
Planck 2015 results. XVII. Constraints on primordial non-GaussianityFeb 05 2015Jul 19 2016The Planck full mission cosmic microwave background(CMB) temperature and E-mode polarization maps are analysed to obtain constraints on primordial non-Gaussianity(NG). Using three classes of optimal bispectrum estimators - separable template-fitting (KSW), ... More
Planck 2013 Results. XXIV. Constraints on primordial non-GaussianityMar 20 2013Dec 03 2013The Planck nominal mission cosmic microwave background (CMB) maps yield unprecedented constraints on primordial non-Gaussianity (NG). Using three optimal bispectrum estimators, separable template-fitting (KSW), binned, and modal, we obtain consistent ... More
Planck 2013 results. XVII. Gravitational lensing by large-scale structureMar 20 2013Jul 30 2014On the arcminute angular scales probed by Planck, the CMB anisotropies are gently perturbed by gravitational lensing. Here we present a detailed study of this effect, detecting lensing independently in the 100, 143, and 217GHz frequency bands with an ... More
Planck 2015 results. XVI. Isotropy and statistics of the CMBJun 23 2015Jan 22 2016We test the statistical isotropy and Gaussianity of the cosmic microwave background (CMB) anisotropies using observations made by the Planck satellite. Our results are based mainly on the full Planck mission for temperature, but also include some polarization ... More
Planck 2015 results. XXVIII. The Planck Catalogue of Galactic Cold ClumpsFeb 05 2015We present the Planck Catalogue of Galactic Cold Clumps (PGCC), an all-sky catalogue of Galactic cold clump candidates detected by Planck. This catalogue is the full version of the Early Cold Core (ECC) catalogue, which was made available in 2011 with ... More
Planck 2013 results. VI. High Frequency Instrument data processingMar 20 2013Jul 23 2014We describe the processing of the 531 billion raw data samples from the High Frequency Instrument (hereafter HFI), which we performed to produce six temperature maps from the first 473 days of Planck-HFI survey data. These maps provide an accurate rendition ... More
Planck intermediate results. XXV. The Andromeda Galaxy as seen by PlanckJul 21 2014Sep 08 2015The Andromeda Galaxy (M31) is one of a few galaxies that has sufficient angular size on the sky to be resolved by the Planck satellite. Planck has detected M31 in all of its frequency bands, and has mapped out the dust emission with the High Frequency ... More
Planck early results: Cluster Sunyaev-Zeldovich optical scaling relationsJan 11 2011We present the Sunyaev-Zeldovich (SZ) signal-to-richness scaling relation (Y500-N200) for the MaxBCG cluster catalogue. Employing a multi-frequency matched filter on the Planck sky maps, we measure the SZ signal for each cluster by adapting the filter ... More
Planck early results. IX. XMM-Newton follow-up for validation of Planck cluster candidatesJan 11 2011Sep 27 2011We present the XMM-Newton follow-up for confirmation of Planck cluster candidates. Twenty-five candidates have been observed to date using snapshot (~10 ksec) exposures, ten as part of a pilot programme to sample a low range of signal-to-noise ratios ... More
Planck 2015 results. VI. LFI mapmakingFeb 05 2015This paper describes the mapmaking procedure applied to Planck LFI (Low Frequency Instrument) data. The mapmaking step takes as input the calibrated timelines and pointing information. The main products are sky maps of $I,Q$, and $U$ Stokes components. ... More
The pre-launch Planck Sky Model: a model of sky emission at submillimetre to centimetre wavelengthsJul 16 2012We present the Planck Sky Model (PSM), a parametric model for the generation of all-sky, few arcminute resolution maps of sky emission at submillimetre to centimetre wavelengths, in both intensity and polarisation. Several options are implemented to model ... More
Comparison of Sunyaev-Zel'dovich measurements from Planck and from the Arcminute Microkelvin Imager for 99 galaxy clustersMay 20 2014Jun 15 2015We present observations and analysis of a sample of 123 galaxy clusters from the 2013 Planck catalogue of Sunyaev-Zel'dovich sources with the Arcminute Microkelvin Imager (AMI), a ground-based radio interferometer. AMI provides an independent measurement ... More
Planck intermediate results. XXXII. The relative orientation between the magnetic field and structures traced by interstellar dustSep 23 2014Mar 31 2015The role of the magnetic field in the formation of the filamentary structures observed in the interstellar medium (ISM) is a debated topic. The Planck all-sky maps of linearly polarized emission from dust at 353GHz provide the required combination of ... More
Planck Early Results XVIII: The power spectrum of cosmic infrared background anisotropiesJan 11 2011Aug 17 2011Using Planck maps of six regions of low Galactic dust emission with a total area of about 140 square degrees, we determine the angular power spectra of cosmic infrared background (CIB) anisotropies from multipole l = 200 to l = 2000 at 217, 353, 545 and ... More
Planck 2013 results. I. Overview of products and scientific resultsMar 20 2013Jun 05 2014The ESA's Planck satellite, dedicated to studying the early Universe and its subsequent evolution, was launched 14 May 2009 and has been scanning the microwave and submillimetre sky continuously since 12 August 2009. This paper gives an overview of the ... More
The SCUBA-2 "All-Sky" SurveyApr 24 2007May 02 2007The sub-millimetre wavelength regime is perhaps the most poorly explored over large areas of the sky, despite the considerable effort that has been expended in making deep maps over small regions. As a consequence the properties of the sub-millimetre ... More
The QUIJOTE experiment: project overview and first resultsApr 14 2015QUIJOTE (Q-U-I JOint TEnerife) is a new polarimeter aimed to characterize the polarization of the Cosmic Microwave Background and other Galactic and extragalactic signals at medium and large angular scales in the frequency range 10-40 GHz. The multi-frequency ... More
The QUIJOTE Experiment: Prospects for CMB B-MODE polarization detection and foregrounds characterizationFeb 13 2018QUIJOTE (Q-U-I JOint TEnerife) is an experiment designed to achieve CMB B-mode polarization detection and sensitive enough to detect a primordial gravitational-wave component if the B-mode amplitude is larger than r = 0.05. It consists in two telescopes ... More
Harmonic analysis of cosmic microwave background data II: from ring-sets to the skyDec 12 2001Despite the fact that the physics of the cosmic microwave background anisotropies is most naturally expressed in Fourier space, pixelised maps are almost always used in the analysis and simulation of microwave data. A complementary approach is investigated ... More
Exploring Cosmic Origins with CORE: Extragalactic sources in Cosmic Microwave Background mapsSep 23 2016May 18 2017We discuss the potential of a next generation space-borne Cosmic Microwave Background (CMB) experiment for studies of extragalactic sources. Our analysis has particular bearing on the definition of the future space project, CORE, that has been submitted ... More
Planck intermediate results. LIII. Detection of velocity dispersion from the kinetic Sunyaev-Zeldovich effectJul 01 2017Aug 23 2018Using the ${\it Planck}$ full-mission data, we present a detection of the temperature (and therefore velocity) dispersion due to the kinetic Sunyaev-Zeldovich (kSZ) effect from clusters of galaxies. To suppress the primary CMB and instrumental noise we ... More
Exploring Cosmic Origins with CORE: Cluster ScienceMar 30 2017We examine the cosmological constraints that can be achieved with a galaxy cluster survey with the future CORE space mission. Using realistic simulations of the millimeter sky, produced with the latest version of the Planck Sky Model, we characterize ... More
Planck intermediate results. LIV. Polarized dust foregroundsJan 15 2018The study of polarized dust emission has become entwined with the analysis of the cosmic microwave background (CMB) polarization. We use new Planck maps to characterize Galactic dust emission as a foreground to the CMB polarization. We present Planck ... More
Planck intermediate results. LIV. The Planck Multi-frequency Catalogue of Non-thermal SourcesFeb 23 2018Sep 11 2018This paper presents the Planck Multi-frequency Catalogue of Non-thermal (i.e. synchrotron-dominated) Sources (PCNT) observed between 30 and 857 GHz by the ESA Planck mission. This catalogue was constructed by selecting objects detected in the full mission ... More
Exploring Cosmic Origins with CORE: B-mode Component SeparationApr 14 2017Jun 19 2017We demonstrate that, for the baseline design of the CORE satellite mission, the polarized foregrounds can be controlled at the level required to allow the detection of the primordial cosmic microwave background (CMB) $B$-mode polarization with the desired ... More
Exploring cosmic origins with CORE: effects of observer peculiar motionApr 19 2017Aug 30 2017We discuss the effects on the CMB, CIB, and thermal SZ effect due to the peculiar motion of an observer with respect to the CMB rest frame, which induces boosting effects. We investigate the scientific perspectives opened by future CMB space missions, ... More
Exploring cosmic origins with CORE: mitigation of systematic effectsJul 13 2017We present an analysis of the main systematic effects that could impact the measurement of CMB polarization with the proposed CORE space mission. We employ timeline-to-map simulations to verify that the CORE instrumental set-up and scanning strategy allow ... More
Planck 2018 results. XI. Polarized dust foregroundsJan 15 2018Nov 12 2018The study of polarized dust emission has become entwined with the analysis of the cosmic microwave background (CMB) polarization. We use new Planck maps to characterize Galactic dust emission as a foreground to the CMB polarization. We present Planck ... More
Massive Neutrino in Non-commutative Space-timeDec 24 2007Apr 01 2008We consider the noncommutative standard model based on $SU(3)\times SU(2)\times U(1)$. We study the gauge transformation of right handed neutrino and its direct interaction with photon in the noncommutative space-time. We show that the massive Dirac neutrinos, ... More
Infinite order excitonic Bloch equations for asymmetric nanostructuresJul 04 2003We present a new exciton-based formalism for calculating the coherent response of asymmetric semiconductor multiple quantum well structures to ultra-short optical pulses valid to infinite order in the optical field and including the self-generated intraband ... More
Scalar StoponiumAug 18 1993We study the decays of a scalar \stst\ bound state \sigst, where \st\ is the lighter stop eigenstate. If \st\ has no tree--level 2--body decays, the dominant decay modes of \sigst\ are $gg$ or, if $m_h < \mst \ll \mstt$, a pair of light scalar Higgs bosons ... More
Photon Neutrino Scattering in Non-Commutative SpaceNov 04 2005Jan 19 2006We extend the non-commutative standard model based on the minimal $SU(3)\times SU(2)\times U(1)$ gauge group to include the interaction of photon with neutrino. We show that, in the gauge invariant manner, only the right handed neutrino can directly couple ... More
A new signal for scalar top bound state productionOct 01 1993We study the production and decay of a scalar \stst\ bound state \sigst\ at hadron supercolliders, where \st\ is the lighter stop eigenstate. If \st\ has no tree--level 2--body decays, the dominant decay modes of \sigst\ are $gg$ or, if $m_h < \mst \ll ... More
Planck 2018 results. I. Overview and the cosmological legacy of PlanckJul 17 2018The European Space Agency's Planck satellite, which was dedicated to studying the early Universe and its subsequent evolution, was launched on 14 May 2009. It scanned the microwave and submillimetre sky continuously between 12 August 2009 and 23 October ... More
Production and Decay of Scalar Stoponium Bound StatesDec 02 1993In this paper we discuss possible signatures for the production of scalar \stst\ (stoponium) bound states \sigst\ at hadron colliders, where \st\ is the lighter scalar top eigenstate. We first study the decay of \sigst; explicit expressions are given ... More
Parton Model in Lorentz Invariant Non-Commutative SpaceMay 26 2004Aug 22 2004We consider the Lorentz invariant non-commutative QED and complete the Feynman rules for the theory up to the order $\theta^2$. In the Lorentz invariant version of the non-commutative QED the particles with fractional charges can be also considered. We ... More
Electromagnetic Response of Weyl SemimetalsMar 22 2013Jun 27 2013It has been suggested recently, based on subtle field-theoretical considerations, that the electromagnetic response of Weyl semimetals and the closely related Weyl insulators can be characterized by an axion term E.B with space and time dependent axion ... More
The Charm Quark Contribution to the Proton Structure FunctionOct 14 2006Dec 27 2006The charm quark structure function $F^c_2$ and the longitudinal structure function $F_l^p$ are directly sensitive to the gluon content of proton and therefore are crucial in understanding of proton structure function, in particular at low momentum transfer ... More
Planck intermediate results. XLII. Large-scale Galactic magnetic fieldsJan 04 2016May 18 2016Recent models for the large-scale Galactic magnetic fields in the literature have been largely constrained by synchrotron emission and Faraday rotation measures. We use three different but representative models to compare their predicted polarized synchrotron ... More
Planck 2018 results. VI. Cosmological parametersJul 17 2018We present cosmological parameter results from the final full-mission Planck measurements of the CMB anisotropies. We find good consistency with the standard spatially-flat 6-parameter $\Lambda$CDM cosmology having a power-law spectrum of adiabatic scalar ... More
Planck intermediate results. III. The relation between galaxy cluster mass and Sunyaev-Zeldovich signalApr 12 2012Sep 14 2012We examine the relation between the galaxy cluster mass M and Sunyaev-Zeldovich (SZ) effect signal D_A^2 Y for a sample of 19 objects for which weak lensing (WL) mass measurements obtained from Subaru Telescope data are available in the literature. Hydrostatic ... More
Planck intermediate results. XX. Comparison of polarized thermal emission from Galactic dust with simulations of MHD turbulenceMay 05 2014Sep 25 2014Polarized emission observed by Planck HFI at 353 GHz towards a sample of nearby fields is presented, focusing on the statistics of polarization fractions $p$ and angles $\psi$. The polarization fractions and column densities in these nearby fields are ... More
Planck intermediate results. XVI. Profile likelihoods for cosmological parametersNov 07 2013Dec 06 2013We explore the 2013 Planck likelihood function with a high-precision multi-dimensional minimizer (Minuit). This allows a refinement of the Lambda-cdm best-fit solution with respect to previously-released results, and the construction of frequentist confidence ... More
Lorentz Conserving Noncommutative Standard ModelMar 29 2007May 10 2007We consider Lorentz conserving noncommutative field theory to construct the Lorentz conserving noncommutative standard model based on the gauge group $SU(3)\times SU(2)\times U(1)$. We obtain the enveloping algebra-valued of Higgs field up to the second ... More
Shelving and Probe Efficiency in Trapped Ion ExperimentsFeb 24 2014A generalized probe sequence typical of trapped ion experiments using shelving is studied. Detection efficiency is analyzed for finite shelved state lifetimes and using multi-modal count distributions. Multi-modal distributions are more appropriate for ... More
The Neutralino Relic Density in Minimal N=1 SupergravityJul 10 1992We compute the cosmic relic (dark matter) density of the lightest supersymmetric particle (LSP) in the framework of minimal $N=1$ Supergravity models with radiative breaking of the electroweak gauge symmetry. To this end, we re--calculate the cross sections ... More
Quantization and $2π$ Periodicity of the Axion Action in Topological InsulatorsJun 17 2010Nov 10 2010The Lagrangian describing the bulk electromagnetic response of a three-dimensional strong topological insulator contains a topological `axion' term of the form '\theta E dot B'. It is often stated (without proof) that the corresponding action is quantized ... More
Planck intermediate results. XXVII. High-redshift infrared galaxy overdensity candidates and lensed sources discovered by Planck and confirmed by Herschel-SPIREMar 30 2015Apr 08 2015[Abridged] We use the Planck all-sky submm and mm maps to search for rare sources distinguished by extreme brightness, a few hundreds of mJy, and their potential for being situated at high redshift. These "cold" Planck sources, selected using the High ... More
On the effect of the thermal gas component to the stability of vortices in trapped Bose-Einstein condensatesMar 12 2002We study the stability of vortices in trapped single-component Bose-Einstein condensates within self-consistent mean-field theories--especially we consider the Hartree-Fock-Bogoliubov-Popov theory and its recently proposed gapless extensions. It is shown ... More
Electroweak Baryogenesis in the MSSMMar 05 1999Mar 24 1999We review the baryogenesis scenario in the MSSM at the perturbative level and, in particular, the impact of two-loop corrections on the strength of the phase transition and the amount of generated baryon asymmetry. We confirm the baryogenesis window, ... More
Cosmic Variance and Its Effect on the Luminosity Function Determination in Deep High z SurveysDec 03 2007We study cosmic variance in deep high redshift surveys and its influence on the determination of the luminosity function for high redshift galaxies. For several survey geometries relevant for HST and JWST instruments, we characterize the distribution ... More
Periodic Solutions of Abel Differential EquationsMay 05 2006Jun 09 2006For a class of polynomial non-autonomous differential equations of degree n, we use phase plane analysis to show that each equation in this class has n periodic solutions. The result implies that certain rigid two-dimensional systems have at most one ... More
Hydrogen and muonic-Hydrogen Atomic Spectra in Non-commutative Space-TimeOct 03 2014Dec 16 2014Comparing electronic Hydrogen with muonic Hydrogen shows that the discrepancy in measurement of the Lamb shift in the both systems are relatively of order of $(\frac{m_\mu}{m_e})^{4-5}$. We explore the spectrum of Hydrogen atom in noncommutative $QED$ ... More
Pair excitations and the mean field approximation of interacting Bosons, IAug 18 2012Mar 16 2013In our previous work \cite{GMM1},\cite{GMM2} we introduced a correction to the mean field approximation of interacting Bosons. This correction describes the evolution of pairs of particles that leave the condensate and subsequently evolve on a background ... More
Color-Flavor (Un)lockingFeb 11 2002The structure of the phase diagram of strongly interacting matter at moderate densities is calculated within a 3-flavor NJL-type quark model with realistic quark masses. We focus on the influence of the selfconsistently determined effective strange quark ... More
Residual Diffeomorphisms and Symplectic Softs Hairs: The Need to Refine Strict Statement of Equivalence PrincipleMar 25 2016Sep 05 2016General covariance is the cornerstone of Einstein's General Relativity (GR) and implies that any two metrics related by diffeomorphisms are physically equivalent. There are, however, many examples pointing to the fact that this strict statement of general ... More
AGN pairs: chance superpositions or black hole binaries?Dec 29 2009Several active galactic nuclei (AGN) with multiple sets of emission lines separated by over 2000 km/s have been observed recently. These have been interpreted as being due to massive black hole (MBH) recoil following a black hole merger, MBH binaries, ... More
On Two Approaches to Fractional Supersymmetric Quantum MechanicsOct 26 2001Two complementary approaches of N = 2 fractional supersymmetric quantum mechanics of order k are studied in this article. The first one, based on a generalized Weyl-Heisenberg algebra W(k) (that comprizes the affine quantum algebra Uq(sl(2)) with q to ... More
Two-Photon Spectroscopy Between States of Opposite ParitiesNov 29 1995Magnetic- and electric-dipole two-photon absorption (MED-TPA), recently introduced as a new spectroscopic technique for studying transitions between states of opposite parities, is investigated from a theoretical point of view. A new approximation, referred ... More
Eisenstein series and quantum affine algebrasApr 26 1996Nov 23 1996Let X be a smooth projectibe curve over a finite field. We consider the Hall algebra H whose basis is formed by isomorphism classes of coherent sheaves on X and whose typical structure constant is the number of subsheaves in a given sheaf belonging to ... More
On the q-analog of homological algebraNov 04 1996This is an attempt to generalize some basic facts of homological algebra to the case of "complexes" in which the differential satisfies the condition $d^N=0$ instead of the usual $d^2=0$. Instead of familiar sign factors, the constructions related to ... More
Clusters of CyclesApr 07 2001A {\it cluster of cycles} (or {\it $(r,q)$-polycycle}) is a simple planar 2--co nnected finite or countable graph $G$ of girth $r$ and maximal vertex-degree $q$, which admits {\it $(r,q)$-polycyclic realization} on the plane, denote it by $P(G)$, i.e. ... More
Cosmic Electroweak StringsOct 27 1995We examine the Standard Model field configurations near cosmic strings in a particular class of models. This class is defined by the condition that the generator of the flux in the string, $T_s$, commutes with the Standard Model Lie algebra. We find that ... More
Instabilities of Electroweak StringsMay 22 1995We investigate the instabilities of low winding number electroweak strings using standard numerical techniques of linear algebra. For strings of unit winding we are able to confirm and extend existing calculations of the unstable region in the ($m_H/m_W,\sin^2\theta_W$) ... More
Searching for low weight pseudo-codewordsFeb 04 2007Jul 30 2007Belief Propagation (BP) and Linear Programming (LP) decodings of Low Density Parity Check (LDPC) codes are discussed. We summarize results of instanton/pseudo-codeword approach developed for analysis of the error-floor domain of the codes. Instantons ... More
Ground state spin and excitation energies in half-filled Lieb latticesOct 10 2016We present detailed spectral calculations for small Lieb lattices having up to $N=4$ number of cells, in the regime of half-filling, an instance of particular relevance for the nano-magnetism of discrete systems such as quantum dot arrays, due to the ... More
Shot noise in diffusive ferromagnetic metalsApr 05 2006We show that shot noise in a diffusive ferromagnetic wire connected by tunnel contacts to two ferromagnetic electrodes can probe the intrinsic density of states and the extrinsic impurity scattering spin-polarization contributions in the polarization ... More
Floquet scattering theory for current and heat noise in large amplitude adiabatic pumpsJul 12 2004Feb 05 2005We discuss the statistical correlation properties of currents and energy flows generated by an adiabatic quantum pump. Our approach emphasizes the important role of quantized energy exchange between the sea of electrons and the oscillating scatterer. ... More
Adiabatic quantum pump in the presence of external ac voltagesSep 28 2003We investigate a quantum pump which in addition to its dynamic pump parameters is subject to oscillating external potentials applied to the contacts of the sample. Of interest is the rectification of the ac currents flowing through the mesoscopic scatterer ... More
Heat production and current noise for single- and double-cavity quantum capacitorsMay 29 2009We analyze the frequency-dependent noise and the heat production rate for a dynamical quantum capacitor in the regime in which it emits single particles, electrons and holes. At low temperature and slow driving the relaxation resistance quantum, R_{q} ... More
Magnetic field symmetry of pump currents of adiabatically driven mesoscopic structuresFeb 03 2005Feb 20 2005We examine the scattering properties of a slowly and periodically driven mesoscopic sample using the Floquet function approach. One might expect that at sufficiently low driving frequencies it is only the frozen scattering matrix which is important. The ... More
Floquet scattering theory of quantum pumpsAug 19 2002We develop the Floquet scattering theory for quantum mechanical pumping in mesoscopic conductors. The nonequilibrium distribution function, the dc charge and heat currents are investigated at arbitrary pumping amplitude and frequency. For mesoscopic samples ... More
Excitation of surface dipole and solenoidal modes on toroidal structuresApr 27 2006May 01 2006The time dependent Schrodinger equation inclusive of curvature effects is developed for a spinless electron constrained to motion on a toroidal surface and subjected to circularly polarized and linearly polarized waves in the microwave regime. A basis ... More
Comment on ``Quasiparticle Spectra around a Single Vortex in a d-wave Superconductor''Oct 22 1997In a recent Letter Morita, Kohmoto and Maki analyzed the structure of quasiparticle states near a single vortex in a d-wave superconductor using an approximate version of the Bogoliubov - de Gennes theory. Their principal result is the existence of a ... More