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Results for "J. Caballero"

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A TGAS/Gaia DR1 parallactic distance to the sigma Orionis clusterFeb 20 2017With the new Tycho-Gaia Astrometric Solution, I derive a new parallactic distance to the young sigma Orionis open cluster, which is a cornerstone region for studying the formation and evolution of stars and substellar objects from tens of solar masses ... More
HRC-I/Chandra X-ray observations towards sigma OrionisJun 21 2010Aims: We investigated the X-ray emission from young stars and brown dwarfs in the sigma Orionis cluster (tau~3 Ma, d~385 pc) and its relation to mass, presence of circumstellar discs, and separation to the cluster centre by taking advantage of the superb ... More
Analysis of the MINERvA antineutrino double-differential cross sections within the SuSAv2-MEC modelJul 27 2018Oct 16 2018We compare the results of the SuSAv2 model including meson-exchange currents (MEC) with the recent measurement of the quasielastic-like double differential antineutrino cross section on hydrocarbon performed by the MINERvA Collaboration. The relativistic ... More
Parity violation and dynamical relativistic effects in $(\vec{e},e'N)$ reactionsJan 17 2015It is well known that coincidence quasielastic $(\vec{e},e'N)$ reactions are not appropriate to analyze effects linked to parity violation due the presence of the fifth electromagnetic (EM) response $R^{TL'}$. Nevertheless, in this work we develop a fully ... More
Cool dwarfs in wide multiple systems. Paper 6: A curious quintuple system of a compact Sun-like triple and a close pair of an M dwarf and a very cool white dwarf at a wide separationAug 17 2018The system WDS 16329+0315 is an old, nearby quintuple physical system in the thick Galactic disc formed by a close-resolved, triple primary of solar metallicity, namely HD 149162, and a very wide, common proper motion, secondary pair, formed by the mid-M ... More
Wide sigma Orionis binaries resolved by UKIDSSJul 03 2017In spite of its importance for the study of star formation at all mass domains, the nearby young sigma Orionis cluster still lacks a comprehensive survey for multiplicity. We try to fill that observational gap by looking for wide resolved binaries with ... More
Identification of blue high proper motion objects in the Tycho-2 and 2MASS catalogues using Virtual Observatory toolsSep 17 2010May 23 2011With available Virtual Observatory tools, we looked for new bright blue high proper motion objects in the entire sky: white dwarfs, hot subdwarfs, runaway OB stars, and early-type stars in nearby young moving groups. We performed an all-sky cross-match ... More
Preliminary results on a Virtual Observatory search for companions to Luyten starsOct 11 2008The Aladin sky atlas of the Virtual Observatory has shown to be a powerful and easy-handling tool for the discovery, confirmation, and characterisation of high proper-motion, multiple stellar systems of large separation in the solar vicinity. Some of ... More
Relativistic descriptions of inclusive quasielastic electron scattering: application to scaling and superscaling ideasJun 15 2009An analysis of inclusive quasielastic electron scattering is presented using different descriptions of the final state interactions within the framework of the relativistic impulse approximation. The relativistic Green's function approach is compared ... More
X-ray variability of sigma Orionis young stars with ROSATMar 27 2009We used the Aladin Virtual Obsrvatory tool and High Resolution Imager ROSAT archival data to search for X-ray variability in scale of days in 23 young stars in the sigma Orionis cluster and a background galaxy. Five stars displayed unambiguous flares ... More
Final-State Interactions in the Superscaling Analysis of Neutral-Current Quasielastic Neutrino ScatteringMay 15 2008Effects of strong final-state interactions in the superscaling properties of neutral-current quasielastic neutrino cross sections are investigated using the Relativistic Impulse Approximation as guidance. First- and second-kind scaling are analyzed for ... More
Superscaling and Charge-changing Neutrino Cross SectionsSep 09 2005Sep 12 2005The superscaling function extracted from inclusive electron scattering data is used to predict high energy charge-changing neutrino cross sections in the quasi-elastic and $\Delta$ regions.
Relativistic Effects in Electromagnetic Meson-Exchange Currents for One-Particle Emission ReactionsJun 04 1998Oct 26 1998Following recent studies of non-relativistic reductions of the single-nucleon electromagnetic current operator, here we extend the treatment to include meson exchange current operators. We focus on one-particle emission electronuclear reactions. In contrast ... More
Superscaling in lepton-nucleus scatteringSep 19 2006We suggest that superscaling analyses of few-GeV inclusive electron scattering from nuclei, both in the quasielastic peak and in the region where the $\Delta$-excitation dominates, allow one to make reliable predictions for charge-changing neutrino reactions ... More
Using Electron Scattering Superscaling to predict Charge-changing Neutrino Cross Sections in NucleiSep 30 2004Dec 06 2004Superscaling analyses of few-GeV inclusive electron scattering from nuclei are extended to include not only quasielastic processes, but now also into the region where $\Delta$-excitation dominates. It is shown that, with reasonable assumptions about the ... More
Recent Developments in relativistic models for exclusive (e,e'p) reactionsSep 26 2001A comparison of impulse approximation calculations for the (e,e'p) reaction, based on the Dirac equation and the Schrodinger one is presented. Trivial (kinematics) differences are indicated, as well as how to remove them from the standard nonrelativistic ... More
Relativistic pionic effects in quasielastic electron scatteringJun 15 2001The impact of relativistic pionic correlations and meson-exchange currents on the response functions for electromagnetic quasielastic electron scattering from nuclei is studied in detail. Results in first-order perturbation theory are obtained for one-particle ... More
Relativistic effects in electromagnetic nuclear responses in the quasi-elastic delta regionMay 18 1999A new non-relativistic expansion in terms of the nucleon's momentum inside nuclear matter of the current for isobar electro-excitation from the nucleon is performed. Being exact with respect to the transferred energy and momentum, this yields new current ... More
Ultra low-mass star and substellar formation in sigma OrionisNov 07 2005The nearby young sigma Orionis cluster (~360 pc, ~3 Ma) is becoming one of the most important regions for the study of ultra low-mass star formation and its extension down to the mass regimes of the brown dwarfs and planetary-mass objects. Here, I introduce ... More
General study of superscaling in quasielastic $(e,e')$ and $(ν,μ)$ reactions using the relativistic impulse approximationApr 10 2006Jun 27 2006The phenomenon of superscaling for quasielastic lepton induced reactions at energies of a few GeV is investigated within the framework of the relativistic impulse approximation. A global analysis of quasielastic inclusive electron and charged-current ... More
Gaia and brown dwarfs from SpainAug 11 2014Gaia will not observe 50000 brown dwarfs, but about 100 times less. However, these <~ 500 brown dwarfs will be benchmarks for many substellar topics. It is possible to identify them in advance and make the list public to all astronomers worldwide through ... More
X-ray pulsars: a reviewJun 14 2012Accreting X-ray pulsars are among the most luminous objects in the X-ray sky. In highly magnetized neutron stars (B~10^12 G), the flow of matter is dominated by the strong magnetic field. The general properties of accreting X-ray binaries are presented, ... More
Scaling Function and Nucleon Momentum DistributionApr 23 2010Scaling studies of inclusive quasielastic electron scattering reactions have been used in the past as a basic tool to obtain information on the nucleon momentum distribution in nuclei. However, the connection between the scaling function, extracted from ... More
Low-resolution spectroscopy and spectral energy distributions of selected sources towards sigma OrionisSep 05 2008Aims: We investigated in detail nine sources in the direction of the young sigma Orionis cluster, which is considered a unique site for studying stellar and substellar formation. The nine sources were selected because of some peculiar properties, such ... More
Are isolated planetary-mass objects really isolated? A brown dwarf-exoplanet system candidate in the sigma Orionis clusterAug 30 2006The recent detection by direct imaging of three giant planets at wide separation (50-250 AU) from their primaries has raised the question about the ``true isolation'' of planetary-mass objects in clusters. Our goal was to test the possibility that some ... More
Inelastic electron-nucleus scattering and scaling at high inelasticityNov 24 2003Feb 13 2004Highly inelastic electron scattering is analyzed within the context of the unified relativistic approach previously considered in the case of quasielastic kinematics. Inelastic relativistic Fermi gas modeling that includes the complete inelastic spectrum ... More
The brightest stars of the sigma Orionis clusterJan 03 2007Context: The very young sigma Orionis cluster (about 3 Ma) is a cornerstone for the understanding of the formation of stars and substellar objects down to planetary masses. However, its stellar population is far to be completely known. Aims: This study ... More
(Sub-)stellar variability: from 20 M$_{\odot}$ to 13 M$_{\rm Jup}$Apr 20 2016Massive early-type stars vary; low-mass late-type brown dwarfs vary, too. I will make a short, but illustrative, summary of my previous studies on stellar and sub-stellar photometric variability (including the discovery of the most variable brown dwarf ... More
Relativity in polarized electron scattering observablesNov 07 2002Dec 05 2002Coincidence scattering of polarized electrons from nuclei with polarization transfer to outgoing nucleons is studied within the context of relativistic mean field theory. Effects introduced by the dynamical enhancement of the lower components of the bound ... More
Charged-current neutrino-nucleus reactions within the SuSAv2-MEC approachJul 28 2016Jul 29 2016We present a detailed study of charged-current (CC) neutrino-nucleus reactions in a fully relativis- tic framework and comparisons with recent experiments spanning an energy range from hundreds of MeV up to 100 GeV within the SuperScaling Approach, which ... More
Off-shell effects in the relativistic mean field model and their role in CC (anti)neutrino scattering at MiniBooNE kinematicsOct 02 2013The relativistic mean field (RMF) model is used to describe nucleons in the nucleus and thereby to evaluate the effects of having dynamically off-shell spinors. Compared with free, on-shell nucleons as employed in some other models, within the RMF nucleons ... More
Relativistic description of final-state interactions in neutral-current neutrino and antineutrino cross sectionsJul 16 2013We evaluate semi-inclusive neutral-current quasielastic differential neutrino and antineutrino cross sections within the framework of the relativistic impulse approximation. The results of the relativistic mean field and of the relativistic Green's function ... More
The Gaia Ultra-Cool Dwarf Sample -- II: Structure at the end of the main sequenceFeb 20 2019We identify and investigate known late M, L and T dwarfs in the Gaia second data release. This sample is being used as a training set in the Gaia data processing chain of the ultra cool dwarfs work package. We find 695 objects in the optical spectral ... More
Stellar and substellar mass function of the young open cluster candidates Alessi 5 and beta MonocerotisNov 03 2010Although the stellar and substellar populations have been studied in various young and old open clusters, additional studies in clusters in the age range from 5 to 100 Myr is crucial (e.g. to give more constrains on initial mass function variation with ... More
A revisit to agglomerates of early-type Hipparcos starsJul 06 2008We study the spatial structure and sub-structure of regions rich in Hipparcos stars with blue B_T-V_T colours. These regions, which comprise large stellar complexes, OB associations, and young open clusters, are tracers of on-going star formation in the ... More
Cool dwarfs in wide multiple systems: Paper 2: A distant M8.5V companion to HD 212168 ABMar 19 2012DENIS J222644.3-750342 is a nearby, very-low-mass, M8.5 V-type star that has been repeatedly targeted by kinematic and activity studies. Thought to be an isolated star, it is actually a wide common-proper-companion at 265 arcsec from the bright G0 V Hipparcos ... More
Young stars and brown dwarfs surrounding Alnilam (eps Ori) and Mintaka (del Ori)Apr 14 2008Aims: We look for new regions for the search of substellar objects. Methods: Two circular areas, 45 arcmin-radius each, centred on the young massive star systems Alnilam and Mintaka in the Orion Belt, have been explored. The regions are very young (less ... More
Stellar multipilicity in the σ Orionis cluster: a reviewAug 10 2014The nearby, young, extinction-free {\sigma} Orionis cluster is acknowledged as a cornerstone for studying the stellar and substellar formation and evolution, especially at very low masses. However, the relatively limited knowledge of multiplicity in the ... More
On a $q$-analogue of the number of representations of an integer as a sum of two squaresJan 09 2018Kassel and Reutenauer \cite{kassel2016fourier} introduced a $q$-analogue of the number of representations of an integer as a sum of two squares. We establish some connections between the prime factorization of $n$ and the coefficients of this $q$-analogue. ... More
A relationship between the ideals of $\mathbb{F}_q\left[x, y, x^{-1}, y^{-1} \right]$ and the Fibonacci numbersSep 13 2017Let $C_n(q)$ be the number of ideals of codimension $n$ of $\mathbb{F}_q\left[x, y, x^{-1}, y^{-1} \right]$, where $\mathbb{F}_q$ is the finite field with $q$ elements. Kassel and Reutenauer [KasselReutenauer2015A] proved that $C_n(q)$ is a polynomial ... More
Relative positions of points on the real line and balanced parenthesesSep 13 2017Consider a finite set of positive real numbers $S$. For any real number $\lambda > 1$, a Dyck word denoted $\langle\! \langle S \rangle\! \rangle_{\lambda} \in \{a,b\}^{\ast}$, was defined in [CaballeroWords2017] in order to compute Hooley's $\Delta$-function ... More
Gaia and sigma Orionis from 20 Msol to 3 MJup: the most complete and precise Initial Mass Function with a parallax determination?Dec 03 2011The sigma Orionis cluster is to date the star-forming region with the largest number of confirmed brown dwarfs and substellar objects below the deuterium burning mass limit. The most massive star, sigma Ori Aa, just in the cluster centre, is the \sim20Msol-mass ... More
Reaching the boundary between stellar kinematic groups and very wide binaries. The Washington Double Stars with the widest angular separationsAug 19 2009Aims. I look for and characterise very wide binaries and multiple systems with projected physical separations larger than s = 0.1 pc, which is generally believed to be a sharp upper limit to the distribution of wide binay semimajor axes. Methods. I investigated ... More
Stars and brown dwarfs, spatial distribution, multiplicity, X-rays, discs, and the complete mass function of the sigma Orionis clusterOct 11 2008The young sigma Orionis cluster in the Orion Belt is an incomparable site for studying the formation and evolution of high-mass, solar-like, and low-mass stars, brown dwarfs, and substellar objects below the deuterium burning mass limit. The first version ... More
Development and Uses of Upper-division Conceptual AssessmentOct 14 2014The use of validated conceptual assessments alongside more standard course exams has become standard practice for the introductory courses in many physics departments. These assessments provide a more standard measure of certain learning goals, allowing ... More
Superscaling and Neutral Current Quasielastic Neutrino-Nucleus Scattering beyond the Relativistic Fermi Gas ModelJun 01 2007The superscaling analysis is extended to include quasielastic (QE) scattering via the weak neutral current of neutrinos and antineutrinos from nuclei. The scaling function obtained within the coherent density fluctuation model (used previously in calculations ... More
On the minimum of a conditioned Brownian bridgeNov 18 2015Nov 13 2017We study the law of the minimum of a Brownian bridge, conditioned to take specific values at specific points, and the law of the location of the minimum. They are used to compare some non-adaptive optimisation algorithms for black-box functions for which ... More
Music and AstronomyOct 11 2008Oct 16 2008What do Brian May (the Queen's lead guitarist), William Herschel and the Jupiter Symphony have in common? And a white dwarf, a piano and Lagartija Nick? At first glance, there is no connection between them, nor between Music and Astronomy. However, there ... More
Chemical abundances of late-type pre-main sequence stars in the $σ$-Orionis clusterAug 30 2008The young $\sigma$-Orionis cluster is an important location for understanding the formation and evolution of stars, brown dwarfs, and planetary-mass objects. Its metallicity, although being a fundamental parameter, has not been well determined yet. We ... More
Collaborating with "professional" amateurs: low-mass stars in fragile multiple systemNov 13 2012The boundary between professional and amateur astronomers gets narrower and narrower. We present several real examples, most of them published in refereed journals, of works resulting from fruitful collaborations between key amateur astronomers in Spain ... More
The role of meson exchange currents in charged current (anti)neutrino-nucleus scatteringOct 10 2016We present our recent progress in the description of neutrino-nucleus interaction in the GeV region, of interest for ongoing and future oscillation experiments. In particular, we discuss the weak excitation of two-particle-two-hole states induced by meson ... More
Scaling Function, Spectral Function and Nucleon Momentum Distribution in NucleiApr 01 2011The link between the scaling function extracted from the analysis of (e,e') cross sections and the spectral function/momentum distribution in nuclei is revisited. Several descriptions of the spectral function based on the independent particle model are ... More
Superscaling analysis of inclusive electron scattering and its extension to charge-changing neutrino-nucleus cross sections beyond the relativistic Fermi gas approachSep 19 2006Superscaling analyses of inclusive electron scattering from nuclei are extended from the quasielastic processes to the delta excitation region. The calculations of $(e,e^\prime)$ cross sections for the target nucleus $^{12}$C at various incident electron ... More
New deep XMM-Newton observations to the west of the sigma Orionis clusterSep 05 2008Aims: The objective of this study is to determine the general X-ray properties of the young stars in the external regions of the sigma Orionis cluster (tau ~ 3 Ma, d ~ 385 pc) and yield constraints on the X-ray emission of brown dwarfs. Methods: We carried ... More
Characterizations of umbilic points of isometric immersions in Riemannian and Lorentzian manifoldsDec 03 2015May 12 2016Several characterizations of umbilic points of submanifolds in arbitrary Riemannian and Lorentzian manifolds are given. As a consequence, we obtain new characterizations of spheres in the Euclidean space and of hyperbolic spaces in the Lorentz-Minkowski ... More
Geometric properties of surfaces with the same mean curvature in R^3 and L^3Apr 14 2016Spacelike surfaces in the Lorentz-Minkowski space L^3 can be endowed with two different Riemannian metrics, the metric inherited from L^3 and the one induced by the Euclidean metric of R^3. It is well known that the only surfaces with zero mean curvature ... More
Cool dwarfs in wide multiple systems. Paper 4: a common-proper-motion pair of two identical mid-M dwarfs separated by about 10000 AUJul 22 2012LSPM J0651+1843 and LSPM J0651+1845 are two high-proper-motion stars recently claimed to form a binary system, FMR 83, by Rica (2012). Here we characterize the system in detail, using astrometric and photometric data, and find that the pair consists of ... More
Strangeness on the nucleonJan 24 2014Observables from parity violation in elastic electron-nucleon scattering and neutral current quasi-elastic neutrino-nucleus scattering are employed as tools to improve the current knowledge on the strangeness content in the nucleon.
A Model for Incorporating Computation Without Changing the Course: An example from middle-division classical mechanicsMar 18 2013Nov 17 2013Much of the research done by modern physicists would be impossible without the use of computation. And yet, while computation is a crucial tool of practicing physicists, physics curricula do not generally reflect its importance and utility. To more tightly ... More
Compaction and mobility in randomly agitated granular assembliesApr 25 2005We study the compaction and mobility properties of a dense granular material under weak random vibration. By putting in direct contact millimetric glass beads with piezoelectric transducers we manage to inject energy to the system in a disordered manner ... More
Assessing Student Learning in Middle-Division Classical Mechanics/Math MethodsJun 12 2013Reliable and validated assessments of introductory physics have been instrumental in driving curricular and pedagogical reforms that lead to improved student learning. As part of an effort to systematically improve our sophomore-level Classical Mechanics ... More
CARMENES input catalogue of M dwarfs II. High-resolution imaging with FastCamAug 29 2016Aims: We search for low-mass companions of M dwarfs and characterize their multiplicity fraction with the purpose of helping in the selection of the most appropriate targets for the CARMENES exoplanet survey. Methods: We obtained high-resolution images ... More
Orbital and physical properties of the $σ$ Ori Aa,Ab,B triple systemDec 10 2014We provide a complete characterization of the astrophysical properties of the $\sigma$ Ori Aa,Ab,B hierarchical triple system, and an improved set of orbital parameters for the highly eccentric $\sigma$ Ori Aa,Ab spectroscopic binary. We compiled a spectroscopic ... More
Music and astronomy. II. unitedsoundsofcosmosNov 18 2016We have been congratulated on the stage by a Nobel laureate (he was our curtain raiser), played our music in planetariums, museums, observatories throughout Spain and at the end of the meeting of the ESO telescopes time allocation committee, shocked audiences ... More
The substellar mass function in sigma Orionis. II. Optical, near-infrared and IRAC/Spitzer photometry of young cluster brown dwarfs and planetary-mass objectsMay 07 2007We investigate the mass function in the substellar domain down to a few Jupiter masses in the young sigma Orionis open cluster (3+/-2 Ma, d = 360^+70_-60 pc). We have performed a deep IJ-band search, covering an area of 790 arcmin^2 close to the cluster ... More
Learning Human-Aware Path Planning with Fully Convolutional NetworksMar 01 2018Jul 17 2018This work presents an approach to learn path planning for robot social navigation by demonstration. We make use of Fully Convolutional Neural Networks (FCNs) to learn from expert's path demonstrations a map that marks a feasible path to the goal as a ... More
An Aladin-based search for proper-motion companions to young stars in the Local Association, Tucana-Horologium and beta PictorisJan 20 2012We have used the Aladin sky atlas of the Virtual Observatory to look for new common proper-motion pairs in three young stellar kinematic groups: Local Association (~10-120 Ma), Tucana-Horologium (~30 Ma) and ? Pictoris (~12 Ma). We have found 9 new and ... More
One dimensional scattering of a two body interacting system by an infinite wallOct 24 2010The one-dimensional scattering of a two body interacting system by an infinite wall is studied in a quantum-mechanical framework. This problem contains some of the dynamical features present in the collision of atomic, molecular and nuclear systems. The ... More
Relativistic descriptions of quasielastic charged-current neutrino-nucleus scattering: application to scaling and superscaling ideasMar 03 2011May 20 2011The analysis of the recent experimental data on charged-current neutrino-nucleus scattering cross sections measured at MiniBooNE requires fully relativistic theoretical descriptions also accounting for the role of final state interactions. In this work ... More
Induced Nucleon Polarization and Meson-Exchange Currents in (e,e'p) ReactionsFeb 02 2004May 11 2004Nucleon recoil polarization observables in $(e,e'\vec{p})$ reactions are investigated using a semi-relativistic distorted-wave model which includes one- and two-body currents with relativistic corrections. Results for the induced polarization asymmetry ... More
Uncorrelated scattering approximation for the scattering and break-up of weakly bound nuclei on heavy targetsMay 07 2001The scattering of a weakly bound (halo) projectile nucleus by a heavy target nucleus is investigated. A new approach, called the Uncorrelated Scattering Approximation, is proposed. The main approximation involved is to neglect the correlation between ... More
Meson Exchange Currents in (e,e'p) recoil polarization observablesMay 26 2003Jul 31 2003A study of the effects of meson-exchange currents and isobar configurations in $A(\vec{e},e'\vec{p})B$ reactions is presented. We use a distorted wave impulse approximation (DWIA) model where final-state interactions are treated through a phenomenological ... More
Explicit identities for Lévy processes associated to symmetric stable processesNov 03 2009In this paper we introduce a new class of L\'evy processes which we call hypergeometric-stable L\'evy processes, because they are obtained from symmetric stable processes through several transformations and where the Gauss hypergeometric function plays ... More
Uncorrelated scattering approximation revisitedMay 21 2004May 24 2004The formalism to describe the scattering of a weakly bound projectile nucleus by a heavy target is investigated, using the Uncorrelated Scattering Approximation. The main assumption involved is to neglect the correlation between the fragments of the projectile ... More
A third massive star component in the σ Orionis AB systemAug 23 2011We report on the detection of a third massive star component in the \sigma\ Orionis AB system, traditionally considered as a binary system. The system has been monitored by the IACOB spectroscopic survey of Northern Massive stars program, obtaining 23 ... More
On the Lamperti stable processesFeb 06 2008Mar 06 2008We consider a new family of $\R^d$-valued L\'{e}vy processes that we call Lamperti stable. One of the advantages of this class is that the law of many related functionals can be computed explicitely (see for instance \cite{cc}, \cite{ckp}, \cite{kp} and ... More
From bulk to microphase separation in scalar active matter: A perturbative renormalization group analysisSep 27 2018Nov 26 2018We consider a dynamical field theory (Active Model B+) that minimally extends the equilibrium Model B for diffusive phase separation of a scalar field, by adding leading-order terms that break time-reversal symmetry. It was recently shown that such active ... More
Skewed recoil polarization in (e,e'p) reactions from polarized nucleiNov 11 2004The general formalism describing $\vec{A}(\vec{e},e'\vec{p})B$ reactions, involving polarization of the electron beam, target and ejected proton, is presented within the framework of the relativistic plane wave impulse approximation for medium and heavy ... More
Analysis of Meson Exchange and Isobar Currents in (e,e'p) Reactions from O-16Apr 12 1999Apr 13 1999An analysis of the effects of meson exchange and isobar currents in exclusive (e,e'p) processes from O-16 under quasi-free kinematics is presented. A model that has probed its feasibility for inclusive quasi-elastic (e,e') processes is considered. Sensitivity ... More
Contamination by field late-M, L and T dwarfs in deep surveysMay 29 2008Jun 01 2008Context: Deep photometric surveys for substellar objects in young clusters and for high-redshift quasars are affected by contaminant sources at different heliocentric distances.If not correctly taken into account, the contamination may have a strong effect ... More
The high-energy emission from GX 339-4 as seen with INTEGRAL and XMM-NewtonDec 07 2008GX 339--4 is a well-known microquasar. In this contribution we show the obtained results with the INTEGRAL and XMM-Newton observatories of the outburst undertaken on 2007. The observations cover spectral evolution from the hard, soft intermediate states ... More
The high energy emission from black holesNov 06 2007The origin of the high energy emission (X-rays and gamma-rays) from black holes is still a matter of debate. We present new evidence that hard X-ray emission in the low/hard state may not be dominated by thermal Comptonization. We present an alternative ... More
A Case Study: Novel Group Interactions through Introductory Computational PhysicsNov 17 2015With the advent of high-level programming languages capable of quickly rendering three-dimensional simulations, the inclusion of computers as a learning tool in the classroom has become more prevalent. Although work has begun to study the patterns seen ... More
Parity violation in quasielastic electron-nucleus scattering within the relativistic impulse approximationJan 17 2015We study parity violation in quasielastic (QE) electron-nucleus scattering using the relativistic impulse approximation. Different fully relativistic approaches have been considered to estimate the effects associated with the final-state interactions. ... More
Kinematical versus dynamical relativistic effects in A(\vec{e},e'\vec{p})BJul 30 2001The relativistic mean field approach is applied to the description of coincidence $A(e,e'p)B$ reactions where both the incident electron beam and knockout proton are polarized. Effects introduced by the dynamical enhancement of the lower components of ... More
RPWIA analysis of dynamical relativistic contributions in $^{16}O(\vec{e},e'\vec{p})$ reactionsJan 03 2002Apr 05 2002Coincidence scattering of polarized electrons from nuclei with polarization transfer to outgoing nucleons is studied within the context of relativistic mean field theory. Effects introduced by the dynamical enhancement of the lower components of the bound ... More
Rubidium resonant squeezed light from a diode-pumped optical-parametric oscillatorJul 27 2008We demonstrate a diode-laser-pumped system for generation of quadrature squeezing and polarization squeezing. Due to their excess phase noise, diode lasers are challenging to use in phase-sensitive quantum optics experiments such as quadrature squeezing. ... More
Using electron scattering to constrain the axial-vector form factorJan 16 2015We present an analysis of elastic and quasielastic parity-violating (PV) electron scattering processes. These reactions can help to constrain the weak neutral current form factors of the nucleon that play an essential role in the description of neutrino ... More
Cool dwarfs in wide multiple systems. Paper 5: New astrometry of 54 wide pairs with M dwarfsJan 21 2015We investigate the membership in double, triple or higher-order-multiplicity systems of 54 pairs with at least one bright M dwarf in the solar neighbourhood. These M dwarfs are potential targets of radial-velocity surveys for exoplanets. We measure angular ... More
Parity Violation in Elastic Electron-Nucleon Scattering: Strangeness Content in the NucleonNov 29 2011Oct 05 2012Parity violation in elastic electron-nucleon scattering is studied with the basic goal of improving the understanding of electroweak hadronic structure with special emphasis on the strangeness content in the nucleon. Models for the parity-violating (PV) ... More
Kinematical relativistic effects in $(\vec{e},e'\vec{N})$ reactionsJan 03 2002Apr 05 2002Kinematical relativistic effects are analyzed within the plane-wave impulse approximation for outgoing nucleon polarized responses in coincidence electron scattering. Following recent approaches for non-relativistic reductions of the electromagnetic current ... More
${\rm P}^3$: A Practice Focused Learning EnvironmentJul 15 2016There has been an increased focus on the integration of practices into physics curricula, with a particular emphasis on integrating computation into the undergraduate curriculum of scientists and engineers. In this paper, we present a university-level, ... More
Outburst of GX 304-1 monitored with INTEGRAL: positive correlation between the cyclotron line energy and fluxMay 24 2012X-ray spectra of many accreting pulsars exhibit significant variations as a function of flux and thus of mass accretion rate. In some of these pulsars, the centroid energy of the cyclotron line(s), which characterizes the magnetic field strength at the ... More
Shear Viscosity of the outer crust of Neutron stars: Ion ContributionJul 28 2008Oct 30 2008The shear viscosity of the crust might have a damping effect on the amplitude of r-modes of rotating neutron stars. This damping has implications for the emission of gravitational waves. We calculate the contribution to the shear viscosity coming from ... More
SHARDS: stellar populations and star formation histories of a mass-selected sample of 0.65<z<1.1 galaxiesJun 24 2013We report on results from the analysis of a stellar mass-selected (log M*>9.0) sample of 1644 galaxies at 0.65<z<1.1 with ultra-deep (m<26.5) optical medium-band (R~50) photometry from the Survey for High-z Absorption Red and Dead Sources (SHARDS). The ... More
Generalized scattering-matrix approach for magneto-optics in periodically patterned multilayer systemsFeb 07 2012We present here a generalization of the scattering-matrix approach for the description of the propagation of electromagnetic waves in nanostructured magneto-optical systems. Our formalism allows us to describe all the key magneto-optical effects in any ... More
Thermal conductivity and phase separation of the crust of accreting neutron starsApr 28 2008Jan 15 2009Recently, crust cooling times have been measured for neutron stars after extended outbursts. These observations are very sensitive to the thermal conductivity $\kappa$ of the crust and strongly suggest that $\kappa$ is large. We perform molecular dynamics ... More
Neutrino Scattering in Heterogeneous Supernova PlasmasJul 25 2006Neutrinos in core collapse supernovae are likely trapped by neutrino-nucleus elastic scattering. Using molecular dynamics simulations, we calculate neutrino mean free paths and ion-ion correlation functions for heterogeneous plasmas. Mean free paths are ... More
Global analysis of parity-violating asymmetry data for elastic electron scatteringMar 20 2014Jul 18 2014We perform a statistical analysis of the full set of parity-violating asymmetry data for elastic electron scattering including the most recent high precision measurement from $Q$-weak. Given the basis of the present analysis, our estimates appear to favor ... More
Teaching Computation in Introductory Physics using Complex ProblemsSep 16 2017Computation is a central aspect of modern science and engineering work, and yet, computational instruction has yet to fully pervade university STEM curricula. In physics, we have begun to integrate computation into our courses in a variety of ways. Here, ... More