Results for "R. B. Barreiro"

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The Cosmic Microwave Background: State of the ArtJul 07 1999Nov 23 1999We review the current status of the cosmic microwave background (CMB) radiation, including a brief discussion of some basic theoretical aspects as well as a summary of anisotropy detections and CMB experiments. We focus on the description of some relevant ... More
Techniques for compact source extraction on CMB mapsDec 21 2005The detection of compact sources embedded in a background is a very common problem in many fields of Astronomy. In these lecture notes we present a review of different techniques developed for the detection and extraction of compact sources, with a especial ... More
An overview of the current status of CMB observationsJun 04 2009Jun 16 2009In this paper we briefly review the current status of the Cosmic Microwave Background (CMB) observations, summarising the latest results obtained from CMB experiments, both in intensity and polarization, and the constraints imposed on the cosmological ... More
The discriminating power of wavelets to detect non-Gaussianity in the CMBApr 18 2001We investigate the power of wavelet techniques in detecting non-Gaussianity in the cosmic microwave background (CMB). We use the method to discriminate between an inflationary and a cosmic strings model using small simulated patches of the sky. We show ... More
On the recovery of ISW fluctuations using large-scale structure tracers and CMB temperature and polarization anisotropiesFeb 18 2016In this work we present a method to extract the signal induced by the integrated Sachs-Wolfe (ISW) effect in the cosmic microwave background (CMB). It makes use of the Linear Covariance-Based filter introduced by Barreiro et al., and combines CMB data ... More
Gaussian analysis of the CMB with the smooth tests of goodness of fitNov 02 2006The study of the Gaussianity of the cosmic microwave background (CMB) radiation is a key topic to understand the process of structure formation in the Universe. In this paper, we review a very useful tool to perform this type of analysis, the Rayner & ... More
Anomalous variance in the WMAP data and Galactic Foreground residualsMay 07 2010Nov 23 2010A previous work (Monteser\'in et al. 2008) estimated the CMB variance from the three-year WMAP data, finding a lower value than expected from Gaussian simulations using the WMAP best-fit cosmological model. We repeat the analysis on the five-year WMAP ... More
Geometrical estimators as a test of Gaussianity in the CMBSep 22 2000We investigate the power of geometrical estimators on detecting non-Gaussianity in the cosmic microwave background. In particular the number, eccentricity and Gaussian curvature of excursion sets above (and below) a threshold are studied. We compare their ... More
The effect of the linear term on the wavelet estimator of primordial non-GaussianityNov 14 2011Jul 29 2012In this work we present constraints on different shapes of primordial non-Gaussianity using the Wilkinson Microwave Anisotropy Probe (WMAP) 7-year data and the spherical Mexican hat wavelet fnl estimator including the linear term correction. In particular ... More
Regularization and Inverse ProblemsApr 18 2001An overview is given of Bayesian inversion and regularization procedures. In particular, the conceptual basis of the maximum entropy method (MEM) is discussed, and extensions to positive/negative and complex data are highlighted. Other deconvolution methods ... More
Improved constraints on primordial non-Gaussianity for the Wilkinson Microwave Anisotropy Probe 5-yr dataFeb 09 2009Oct 19 2009We present new constraints on the non-linear coupling parameter fnl with the Wilkinson Microwave Anisotropy Probe (WMAP) data. We use an updated method based on the spherical Mexican hat wavelet (SMHW) which provides improved constraints on the fnl parameter. ... More
On the optimality of the spherical Mexican hat wavelet estimator for the primordial non-GaussianityJul 13 2010Nov 07 2010We study the spherical Mexican hat wavelet (SMHW) as a detector of primordial non-Gaussianity of the local type on the Cosmic Microwave Background (CMB) anisotropies. For this purpose we define third order statistics based on the wavelet coefficient maps ... More
Constraints on fNL from Wilkinson Microwave Anisotropy Probe 7-year data using a neural network classifierMay 30 2011Jan 31 2012We present a multi-class neural network (NN) classifier as a method to measure nonGaussianity, characterised by the local non-linear coupling parameter fNL, in maps of the cosmic microwave background (CMB) radiation. The classifier is trained on simulated ... More
Exploring local fNL estimators based on the binned bispectrumMay 03 2013We explore different estimators of the local non-linear coupling parameter, fNL, based on the binned bispectrum presented in Bucher et al. Using simulations of Wilkinson Microwave Anisotropy Probe (WMAP)-7yr data, we compare the performance of a regression ... More
Multi-resolution internal template cleaning: An application to the Wilkinson Microwave Anisotropy Probe 7-yr polarization dataJun 10 2011Nov 14 2011Cosmic microwave background (CMB) radiation data obtained by different experiments contain, besides the desired signal, a superposition of microwave sky contributions. We present a fast and robust method, using a wavelet decomposition on the sphere, to ... More
Exploring two-spin internal linear combinations for the recovery of the CMB polarizationJan 07 2016Apr 04 2016We present a methodology to recover cosmic microwave background (CMB) polarization in which the quantity $P = Q+ iU$ is linearly combined at different frequencies using complex coefficients. This is the most general linear combination of the $Q$ and $U$ ... More
Wilkinson Microwave Anisotropy Probe 7-yr constraints on fNL with a fast wavelet estimatorSep 03 2010Jan 19 2011A new method to constrain the local non-linear coupling parameter fNL based on a fast wavelet decomposition is presented. Using a multiresolution wavelet adapted to the HEALPix pixelization, we have developed a method that is 10^2 times faster than previous ... More
Searching for a dipole modulation in the large-scale structure of the UniverseDec 01 2013Jul 28 2014Several statistical anomalies in the CMB temperature anisotropies seem to defy the assumption of a homogeneous and isotropic universe. In particular, a dipole modulation has been detected both in WMAP and Planck data. We adapt the methodology proposed ... More
Cosmological Aspects of Heterotic M-theoryJan 19 2000In this talk we discuss a few relevant aspects of heterotic M-theory. These are the stabilization of the two relevant moduli (the length of the eleventh segment (pi rho) and the volume of the internal six manifold (V)) in models where supersymmetry is ... More
Moduli as Inflatons in Heterotic M-theoryDec 16 1999Mar 24 2000We consider different cosmological aspects of Heterotic M-theory. In particular we look at the dynamical behaviour of the two relevant moduli in the theory, namely the length of the eleventh segment (pi rho) and the volume of the internal six manifold ... More
CMB polarization as a probe of the anomalous nature of the Cold SpotFeb 22 2010Jul 26 2010One of the most interesting explanations for the non-Gaussian Cold Spot (CS) detected in the WMAP data by Vielva et al. 2004, is that it arises from the interaction of the CMB radiation with a cosmic texture (Cruz et al. 2007b). In this case, a lack of ... More
Some comments on the note "Some comments on the paper 'Filter design for the detection of compact sources based on the Neyman-Pearson detector' by M. Lopez-Caniego et. al (2005, MNRAS 359, 993)" by R. Vio and P. Andreani (astroph/0509394)Sep 23 2005In this note we stress the necessity of a careful check of the arguments used by Vio & Andreani (2005) (VA hereinafter) to criticise the superior performance of the biparametric scale adaptive filter (BSAF) with respect to the classic matched filter (MF) ... More
Higher N-point Amplitudes in Open Superstring TheoryNov 30 2006In this work we report on recent progress in the calculation of open superstring scattering amplitudes, at tree level, with more than four external massless states. We also report on the corresponding terms in the low energy effective lagrangian.
Non-Gaussianity analysis on local morphological measures of WMAP dataJun 15 2007Jan 07 2008The decomposition of a signal on the sphere with the steerable wavelet constructed from the second Gaussian derivative gives access to the orientation, signed-intensity, and elongation of the signal's local features. In the present work, the non-Gaussianity ... More
Constraints on general primordial non-Gaussianity using wavelets for the Wilkinson Microwave anisotropy probe 7-year dataMay 30 2011Jun 21 2011We present constraints on the non-linear coupling parameter fnl with the Wilkinson Microwave Anisotropy Probe (WMAP) data. We use the method based on the spherical Mexican hat wavelet (SMHW) to measure the fnl parameter for three of the most interesting ... More
Statistical analysis of undetected point sources in cosmic microwave background mapsSep 13 2006Cosmic microwave background (CMB) temperature anisotropies follow a Gaussian statistical distribution in the standard inflationary model, but there are non-Gaussian contributions due to astrophysical foregrounds. The detection of the non-Gaussian signal ... More
Filter design for the detection of compact sources based on the Neyman-Pearson detectorMar 07 2005Apr 11 2005This paper considers the problem of compact source detection on a Gaussian background in 1D. Two aspects of this problem are considered: the design of the detector and the filtering of the data. Our detection scheme is based on local maxima and it takes ... More
A Bayesian approach to filter design: detection of compact sourcesMar 07 2005We consider filters for the detection and extraction of compact sources on a background. We make a one-dimensional treatment (though a generalization to two or more dimensions is possible) assuming that the sources have a Gaussian profile whereas the ... More
Integrated Sachs-Wolfe map recovery from NVSS and WMAP 7yr dataAug 11 2012Jan 18 2013We present a map of the Cosmic Microwave Background (CMB) anisotropies induced by the late Integrated Sachs Wolfe effect. The map is constructed by combining the information of the WMAP 7-yr CMB data and the NRAO VLA Sky Survey (NVSS) through a linear ... More
On the regularity of the covariance matrix of a discretized scalar field on the sphereJan 23 2017Apr 11 2017We present a comprehensive study of the regularity of the covariance matrix of a discretized field on the sphere. In a particular situation, the rank of the matrix depends on the number of pixels, the number of spherical harmonics, the symmetries of the ... More
Effect of component separation on the temperature distribution of the CMBMar 02 2005Mar 24 2006We present a study of the effect of component separation on the recovered cosmic microwave background (CMB) temperature distribution, considering Gaussian and non-Gaussian input CMB maps. First, we extract the CMB component from simulated Planck data ... More
Scalar statistics on the sphere: application to the CMBNov 10 2005A method to compute several scalar quantities of Cosmic Microwave Background maps on the sphere is presented. We consider here four type of scalars: the Hessian matrix scalars, the distortion scalars, the gradient related scalars and the curvature scalars. ... More
Goodness-of-fit tests of Gaussianity: constraints on the cumulants of the MAXIMA dataSep 22 2003In this work, goodness-of-fit tests are adapted and applied to CMB maps to detect possible non-Gaussianity. We use Shapiro-Francia test and two Smooth goodness-of-fit tests: one developed by Rayner and Best and another one developed by Thomas and Pierce. ... More
Scale-Adaptive filters for the detection/separation of compact sourcesApr 09 2002This paper presents scale-adaptive filters that optimize the detection/separation of compact sources on a background. We assume that the sources have a multiquadric profile, i. e. $\tau (x) = {[1 + {(x/r_c)}^2]}^{-\lambda}, \lambda \geq {1/2}, x\equiv ... More
Gaussianity of the CMB: Smooth Goodness of Fit Tests Applied to Interferometric DataNov 05 2004We adapt the smooth tests of goodness of fit developed by Rayner and Best to the study of the non-Gaussianity of interferometric observations of the cosmic microwave background (CMB). The interferometric measurements (visibilities) are transformed into ... More
A linear filter to reconstruct the ISW effect from CMB and LSS observationsSep 15 2008The extraction of a signal from some observational data sets that contain different contaminant emissions, often at a greater level than the signal itself, is a common problem in Astrophysics and Cosmology. The signal can be recovered, for instance, using ... More
All-sky component separation in the presence of anisotropic noise and dust temperature variationsMay 25 2004We present an extension of the harmonic-space maximum-entropy component separation method (MEM) for multi-frequency CMB observations that allows one to perform the separation with more plausible assumptions about the receiver noise and foreground astrophysical ... More
Peaks in the Cosmic Microwave Background: flat versus open modelsDec 11 1996We present properties of the peaks (maxima) of the CMB anisotropies expected in flat and open CDM models. We obtain analytical expressions of several topological descriptors: mean number of maxima and the probability distribution of the gaussian curvature ... More
The estimation of the SZ effects with unbiased multifiltersJun 09 2004In this work we study the performance of linear multifilters for the estimation of the amplitudes of the thermal and kinematic Sunyaev-Zel'dovich effects. We show that when both effects are present, estimation of these effects with standard matched multifilters ... More
Comparing filters for the detection of point sourcesFeb 12 2003This paper considers filters (the Mexican hat wavelet, the matched and the scale-adaptive filters) that optimize the detection/separation of point sources on a background. We make a one-dimensional treatment, we assume that the sources have a Gaussian ... More
A low CMB variance in the WMAP dataJun 28 2007Mar 11 2008We have estimated the CMB variance from the three-year WMAP data, finding a value which is significantly lower than the one expected from Gaussian simulations using the WMAP best-fit cosmological model, at a significance level of 98.7 per cent. This result ... More
Detection of non-Gaussianity in the WMAP 1-year data using spherical waveletsOct 09 2003Mar 15 2004A non-Gaussian detection in the WMAP 1-year data is reported. The detection has been found in the combined Q-V-W map proposed by the WMAP team (Komatsu et al. 2003) after applying a wavelet technique based on the Spherical Mexican Hat Wavelet (SMHW). ... More
Correlation of Excursion Sets for Non-Gaussian CMB Temperature DistributionsDec 10 1997We present a method, based on the correlation function of excursion sets above a given threshold, to test the Gaussianity of the CMB temperature fluctuations in the sky. In particular, this method can be applied to discriminate between standard inflationary ... More
Scalar quantities as detectors of non-Gaussianity on CMB mapsApr 17 2006Jul 03 2006We study the power of several scalar quantities constructed on the sphere (presented in Monteserin et al. 2005) to detect non-Gaussianity on the temperature distribution of the cosmic microwave background (CMB). The test has been performed using non-Gaussian ... More
Detection of point sources on two-dimensional images based on peaksMar 07 2005This article considers the detection of point sources in two dimensional astronomical images. The detection scheme we propose is based on peak statistics. We discuss the example of the detection of far galaxies in Cosmic Microwave Background experiments ... More
Wavelets Applied to CMB Maps: a Multiresolution Analysis for DenoisingJun 23 1999Analysis and denoising of Cosmic Microwave Background (CMB) maps are performed using wavelet multiresolution techniques. The method is tested on $12^{\circ}.8\times 12^{\circ}.8$ maps with resolution resembling the experimental one expected for future ... More
An optimal estimator for the CMB-LSS angular power spectrum and its application to WMAP and NVSS dataMar 15 2012We use a Quadratic Maximum Likelihood (QML) method to estimate the angular power spectrum of the cross-correlation between cosmic microwave background and large scale structure maps as well as their individual auto-spectra. We describe our implementation ... More
The effect of point sources on satellite observations of the cosmic microwave backgroundOct 15 1998We study the effect of extragalactic point sources on satellite observations of the cosmic microwave background (CMB). In order to separate the contributions due to different foreground components, a maximum-entropy method is applied to simulated observations ... More
Foreground separation using a flexible maximum-entropy algorithm: an application to COBE dataFeb 05 2003Apr 22 2004A flexible maximum-entropy component separation algorithm is presented that accommodates anisotropic noise, incomplete sky-coverage and uncertainties in the spectral parameters of foregrounds. The capabilities of the method are determined by first applying ... More
Tests of GaussianityOct 24 2003We review two powerful methods to test the Gaussianity of the cosmic microwave background (CMB): one based on the distribution of spherical wavelet coefficients and the other on smooth tests of goodness-of-fit. The spherical wavelet families proposed ... More
WMAP 5-year constraints on fnl with waveletsJul 01 2008Nov 12 2008We present a Gaussianity analysis of the WMAP 5-year Cosmic Microwave Background (CMB) temperature anisotropy data maps. We use several third order estimators based on the spherical Mexican hat wavelet. We impose constraints on the local non-linear coupling ... More
Combined MEM and MHW analysis of CMB observationsNov 07 2000We present a combined maximum-entropy method (MEM) and Mexican Hat wavelet (MHW) analysis in order to recover the different components of the microwave sky. We apply this technique to simulated observations by the ESA Planck satellite in small patches ... More
Looking for non-Gaussianity in the COBE-DMR data with spherical waveletsApr 23 2000We present an analysis of the Gaussianity of the 4-year COBE-DMR data (in HEALPix pixelisation) based on spherical wavelets. The skewness, kurtosis and scale-scale correlation spectra are computed from the detail wavelet coefficients at each scale. The ... More
Testing the Gaussianity of the COBE-DMR data with spherical waveletsApr 14 2000We investigate the Gaussianity of the 4-year COBE-DMR data (in HEALPix pixelisation) using an analysis based on spherical Haar wavelets. We use all the pixels lying outside the Galactic cut and compute the skewness, kurtosis and scale-scale correlation ... More
Comparison of filters for the detection of point sources in Planck simulationsJun 08 2006We study the detection of extragalactic point sources in two-dimensional flat simulations for all the frequencies of the forthcoming ESA's Planck mission. In this work we have used the most recent available templates of the microwave sky: as for the diffuse ... More
Filtering techniques for the detection of Sunyaev-Zel'dovich clusters in multifrequency CMB mapsMar 27 2002Apr 09 2002The problem of detecting Sunyaev-Zel'dovich (SZ) clusters in multifrequency CMB observations is investigated using a number of filtering techniques. A multifilter approach is introduced, which optimizes the detection of SZ clusters on microwave maps. ... More
Combining maximum-entropy and the mexican hat wavelet to reconstruct the microwave skyMay 22 2001We present a maximum-entropy method (MEM) and `Mexican Hat' wavelet (MHW) joint analysis to recover the different components of the microwave sky from simulated observations by the ESA Planck satellite in a small patch of the sky. This combined method ... More
Isotropic Wavelets: a Powerful Tool to Extract Point Sources from CMB MapsDec 22 1999It is the aim of this paper to introduce the use of isotropic wavelets to detect and determine the flux of point sources appearing in CMB maps. The most suited wavelet to detect point sources filtered with a Gaussian beam is the Mexican Hat. An analytical ... More
Combining texture zeros with a remnant CP symmetry in the minimal type-I seesawOct 12 2018In the framework of the two right-handed neutrino seesaw model, we consider maximally-restrictive texture-zero patterns for the lepton Yukawa coupling and mass matrices, together with the existence of a remnant CP symmetry. Under these premisses, we find ... More
Testing Gaussianity on Archeops DataDec 06 2006Jul 20 2007A Gaussianity analysis using a goodness-of-fit test and the Minkowski functionals on the sphere has been performed to study the measured Archeops Cosmic Microwave Background (CMB) temperature anisotropy data for a 143 GHz Archeops bolometer. We consider ... More
Constraints on the non-linear coupling parameter fnl with the Archeops dataApr 01 2008Jun 19 2008We present a Gaussianity analysis of the Archeops Cosmic Microwave Background (CMB) temperature anisotropy data maps at high resolution to constrain the non-linear coupling parameter fnl characterising well motivated non-Gaussian CMB models. We used the ... More
Cosmological applications of a wavelet analysis on the sphereApr 24 2007The cosmic microwave background (CMB) is a relic radiation of the Big Bang and as such it contains a wealth of cosmological information. Statistical analyses of the CMB, in conjunction with other cosmological observables, represent some of the most powerful ... More
The minimal type-I seesaw model with maximally-restricted texture zerosFeb 13 2018In the context of Standard Model (SM) extensions, the seesaw mechanism provides the most natural explanation for the smallness of neutrino masses. In this work we consider the most economical type-I seesaw realization in which two right-handed neutrinos ... More
The very bright SCUBA galaxy count: looking for SCUBA galaxies with the Mexican Hat WaveletMay 07 2004We present the results of a search for bright high-redshift galaxies in two large SCUBA scan-maps of Galactic regions. A Mexican Hat Wavelet technique was used to locate point sources in these maps, which suffer high foreground contamination as well as ... More
Analysis of CMB maps with 2D waveletsSep 29 1999We consider the 2D wavelet transform with two scales to study sky maps of temperature anisotropies in the cosmic microwave background radiation (CMB). We apply this technique to simulated maps of small sky patches of size 12.8 \times 12.8 square degrees ... More
Combining texture zeros with a remnant CP symmetry in the minimal type-I seesawOct 12 2018Feb 27 2019In the framework of the two right-handed neutrino seesaw model, we consider maximally-restrictive texture-zero patterns for the lepton Yukawa coupling and mass matrices, together with the existence of a remnant CP symmetry. Under these premisses, we find ... More
Moduli Evolution in Heterotic ScenariosOct 10 2000Jan 16 2001We discuss several aspects of the cosmological evolution of moduli fields in heterotic string/M-theory scenarios. In particular we study the equations of motion of both the dilaton and overall modulus of these theories in the presence of an expanding ... More
Stabilizing the Dilaton in Superstring CosmologyMay 01 1998We address the important issue of stabilizing the dilaton in the context of superstring cosmology. Scalar potentials which arise out of gaugino condensates in string models are generally exponential in nature. In a cosmological setting this allows for ... More
A QCD Sum Rule Approach to the $s\to dγ$ Contribution to the $Ω^-\to Ξ^-γ$ Radiative DecaySep 14 1995QCD sum rules are used to calculate the contribution of short-distance single-quark transition $s\rightarrow d \gamma$, to the amplitudes of the hyperon radiative decay, $\Omega^-\rightarrow \Xi^-\gamma$. We re-evaluate the Wilson coefficient of the effective ... More
On non-perturbative corrections to the Kahler potentialDec 18 1997We present the results of a detailed investigation into the consequences of adding specific string motivated non-perturbative corrections to the usual tree level Kahler potential in dilaton dominated scenarios. The success of the model is judged through ... More
Spectroscopic observation of the rotational Doppler effectJul 26 2006We report on the first spectroscopic observation of the rotational Doppler shift associated with light beams carrying orbital angular momentum. The effect is evidenced as the broadening of a Hanle/EIT coherence resonance on Rb vapor when the two incident ... More
Can $Ω^- \to Ξ^- γ$ be sensitive to new physics beyond the Standard Model ?Nov 29 1995We investigate the impact of new physics beyond the Standard Model to the $s \rightarrow d \gamma$ process, which is responsible for the short-distance contribution to the radiative decay $\Otogamma$. We study three representative extensions of the Standard ... More
Universal digital quantum simulation with trapped ionsSep 07 2011Oct 07 2011A digital quantum simulator is an envisioned quantum device that can be pro- grammed to efficiently simulate any other local system. We demonstrate and investigate the digital approach to quantum simulation in a system of trapped ions. Using sequences ... More
An ultradeep submillimetre map: beneath the SCUBA confusion limit with lensing and robust source extractionFeb 06 2006Extracting sources with low signal-to-noise from maps with structured background is a non-trivial task which has become important in studying the faint end of the submillimetre number counts. In this article we study source extraction from submillimetre ... More
The Jubilee ISW Project I: simulated ISW and weak lensing maps and initial power spectra resultsJul 05 2013Jul 09 2013We present initial results from the Jubilee ISW project, which models the expected \LambdaCDM Integrated Sachs-Wolfe (ISW) effect in the Jubilee simulation. The simulation volume is (6 Gpc/h)^3, allowing power on very large-scales to be incorporated into ... More
Peripheral N$α$ Scattering: A Tool For Identifying The Two Pion Exchange Component Of The NN PotentialApr 23 1998We study elastic N$\alpha $ scattering and produce a quantitative correlation between the range of the effective potential and the energy of the system. This allows the identification of the waves and energies for which the scattering may be said to be ... More
Advantages of gated silicon single photon detectorsAug 21 2012We present a gated silicon single photon detector based on a commercially available avalanche photodiode. Our detector achieves a photon detection efficiency of 45\pm5% at 808 nm with 2x 10^-6 dark count per ns at -30V of excess bias and -30{\deg}C. We ... More
Moduli evolution in the presence of flux compactificationsJun 06 2005Jun 20 2005We study the cosmological evolution of the volume moduli in a class of recently proposed Inflationary Universe models arising out of Type IIB string theory, where a number of the moduli fields have been stabilised through flux compactifications. Developing ... More
Realization of the Hofstadter Hamiltonian with ultracold atoms in optical latticesAug 01 2013Sep 07 2013We demonstrate the experimental implementation of an optical lattice that allows for the generation of large homogeneous and tunable artificial magnetic fields with ultracold atoms. Using laser-assisted tunneling in a tilted optical potential we engineer ... More
Moduli evolution in the presence of thermal correctionsDec 14 2007Sep 23 2008We study the effect of thermal corrections on the evolution of moduli in effective Supergravity models. This is motivated by previous results in the literature suggesting that these corrections could alter and, even, erase the presence of a minimum in ... More
Anomalous U(1), gaugino condensation and supergravityAug 06 1998Nov 04 1998The interplay between gaugino condensation and an anomalous Fayet-Iliopoulos term in string theories is not trivial and has important consequences concerning the size and type of the soft SUSY breaking terms. In this paper we examine this issue, generalizing ... More
Observation of the Meissner effect with ultracold atoms in bosonic laddersFeb 04 2014We report on the observation of the Meissner effect in bosonic flux ladders of ultracold atoms. Using artificial gauge fields induced by laser-assisted tunneling, we realize arrays of decoupled ladder systems that are exposed to a uniform magnetic field. ... More
Reconstructing the Inflaton Potential --- an OverviewAug 17 1995Oct 25 1996We review the relation between the inflationary potential and the spectra of density (scalar) perturbations and gravitational waves (tensor perturbations) produced, with particular emphasis on the possibility of reconstructing the inflaton potential from ... More
Narrow band amplification of light carrying orbital angular momentumMay 05 2016We report on the amplification of an optical vortex beam carrying orbital angular momentum via induced narrow Raman gain in an ensemble of cold cesium atoms. A 20\% single-pass Raman gain of a weak vortex signal field is observed with a spectral width ... 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
Tests of Gaussianity of CMB mapsOct 17 2000We study two different methods to test Gaussianity in CMB maps. One of them is based on the partition function and the other on the morphology of hot and cold spots. The partition function contains information on all the moments and scales, being a useful ... More
Using HistCite software to identify significant articles in subject searches of the Web of ScienceDec 22 2015HistCite TM is a large-scale computer tool for mapping science. Its power of visualization combines the production of historiographs on the basis of the analysis of co-citations of documents, with the use of bibliometrics specific indicators. The objective ... More
Experimental multiparticle entanglement dynamics induced by decoherenceMay 11 2010Multiparticle entanglement leads to richer correlations than two-particle entanglement and gives rise to striking contradictions with local realism, inequivalent classes of entanglement, and applications such as one-way or topological quantum computing. ... More
Innovation éducative en sciences de l'informationNov 04 2013Concerning its development in the virtual classroom, the web 2.0 educational innovation means the use and the production of textbooks and the personalisation of the classnotes. The controversy, that is a precondition of awareness, organized around the ... More
Measuring the Chern number of Hofstadter bands with ultracold bosonic atomsJul 16 2014Oct 24 2014Sixty years ago, Karplus and Luttinger pointed out that quantum particles moving on a lattice could acquire an anomalous transverse velocity in response to a force, providing an explanation for the unusual Hall effect in ferromagnetic metals. A striking ... More
Component separation methods for the Planck missionMay 02 2008Nov 25 2008The Planck satellite will map the full sky at nine frequencies from 30 to 857 GHz. The CMB intensity and polarization that are its prime targets are contaminated by foreground emission. The goal of this paper is to compare proposed methods for separating ... More
Off-axis retrieval of orbital angular momentum of light stored in cold atomsSep 19 2014We report on the storage of orbital angu- lar momentum (OAM) of light of a Laguerre-Gaussian mode in an ensemble of cold cesium atoms and its re- trieval along an axis different from the incident light beam. We employed a time-delayed four-wave mixing ... More
Storage of orbital angular momenta of light via coherent population oscillationMay 25 2015We report on the storage of Orbital Angular Momentum (OAM) of light via the phenomenon of Coherent Population Oscillation (CPO) in cold cesium atoms. The experiment is performed using a delayed four wave mixing configuration where the transverse optical ... More
Low-Rank Correlations in Heterogeneous Neural CircuitsOct 20 2016A central question in neuroscience is to understand how firing patterns are used to transmit information. Theoretical work shows us that the entire distribution of spiking statistics (such as firing rates) across the population will affect common measures ... More
Generalized Chaplygin Gas in a modified gravity approachAug 10 2004Dec 09 2004We study the generalized Chaplygin gas (GCG) scenario in a modified gravity approach. That is, we impose that our universe has a pure dust configuration, and allow for a modification of gravity that yields a GCG specific scale factor evolution. Moreover, ... More
RNS derivation of N-point disk amplitudes from the revisited S-matrix approachOct 22 2013In the past year, in arXiv:1208.6066 we proposed a revisited S-matrix approach to efficiently find the bosonic terms of the open superstring low energy effective lagrangian (OSLEEL). This approach allows to compute the ${\alpha'}^N$ terms of the OSLEEL ... More
Interacting dark energy collapse with matter components separationAug 31 2012Feb 01 2013We use the spherical collapse model of structure formation to investigate the separation in the collapse of uncoupled matter (essentially baryons) and coupled dark matter in an interacting dark energy scenario. Following the usual assumption of a single ... More
Revisiting the S-matrix approach to the open superstring low energy effective lagrangianAug 30 2012Oct 25 2012The conventional S-matrix approach to the (tree level) open string low energy effective lagrangian assumes that, in order to obtain all its bosonic ${\alpha'}^N$ order terms, it is necessary to know the open string (tree level) $(N+2)$-point amplitude ... More
Practical Approximation Method for Firing Rate Models of Coupled Neural Networks with Correlated InputsFeb 12 2017Sep 29 2017Rapid experimental advances now enable simultaneous electrophysiological recording of neural activity at single-cell resolution across large regions of the nervous system. Models of this neural network activity will necessarily increase in size and complexity, ... More
The QUIJOTE CMB Experiment: status and first results with the multi-frequency instrumentJan 19 2014Feb 05 2014The QUIJOTE (Q-U-I JOint Tenerife) CMB Experiment is designed to observe the polarization of the Cosmic Microwave Background and other Galactic and extragalactic signals at medium and large angular scales in the frequency range of 10-40 GHz. The first ... More