Boudreault, S., Goldman, B., Henning, T., Caballero, J. A.
[Abridged] In this paper, we present the results of a photometric survey to identify low mass and brown dwarf members of the old open cluster Praesepe (age of 590[+150][-120]Myr and distance of...
Relativistic Models of Quasielastic Electron and Neutrino-Nucleus Scattering (2009)
Giusti, C., Meucci, A., Pacati, F. D., Caballero, J. A., Udias, J. N.
Relativistic models developed for the exclusive and inclusive quasielastic (QE) electron scattering have been extended to charged-current (CC) and neutral-current (NC) neutrino-nucleus scattering....
Nuclear effects in electron reactions and their impact on neutrino processes (2009)
Barbaro, M. B., Amaro, J. E., Caballero, J. A., Cenni, R., Donnelly, T. W., Molinari, A., ...
We suggest that superscaling in electroweak interactions with nuclei, namely the observation that the reduced electron-nucleus cross sections are to a large degree independent of the momentum...
Neutrino Interactions Importance for Nuclear Physics (2009)
Amaro, J. E., Maieron, C., Valverde, M., Nieves, J., Barbaro, M. B., Caballero, J. A., ...
We review the general interplay between Nuclear Physics and neutrino-nucleus cross sections at intermediate and high energies. The effects of different reaction mechanisms over the neutrino...
Candidate free-floating super-Jupiters in the young sigma Orionis open cluster (2009)
Bihain, G., Rebolo, R., Osorio, M. R. Zapatero, Béjar, V. J. S., Villó-Pérez, I., Díaz-Sánchez, A., ...
Free-floating substellar candidates with estimated theoretical masses of as low as ~5 Jupiter masses have been found in the ~3 Myr old sigma Orionis open cluster. As the overlap with the planetary...
Relativistic models for electron and neutrino-nucleus scattering (2009)
Giusti, C., Meucci, A., Pacati, F. D., Caballero, J. A., Udias, J. M.
Relativistic models developed for the exclusive and inclusive quasielastic (QE) electron scattering have been extended to charged-current (CC) and neutral-current (NC) neutrino-nucleus scattering....
Superscaling of non-quasielastic electron-nucleus scattering (2009)
Maieron, C., Amaro, J. E., Barbaro, M. B., Caballero, J. A., Donnelly, T. W., Williamson, C. F.
The present study is focused on the superscaling behavior of electron-nucleus cross sections in the region lying above the quasielastic peak, especially the region dominated by electroexcitation of...
Amaro, J. E., Barbaro, M. B., Caballero, J. A., Donnelly, T. W., Maieron, C., Udias, J. M.
The effects of meson-exchange currents (MEC) are computed for the one-particle one-hole transverse response function for finite nuclei at high momentum transfers $q$ in the region of the quasielastic...
Meucci, Andrea, Caballero, J. A., Giusti, C., Pacati, F. D., Udias, J. M.
An 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...
Polarisation of very-low-mass stars and brown dwarfs (2009)
Goldman, B., Pitann, J., Osorio, M. R. Zapatero, Bejar, V. J. S., Caballero, J. A., ...
Ultra-cool dwarfs of the L spectral type (Teff=1400-2200K) are known to have dusty atmospheres. Asymmetries of the dwarf surface may arise from rotationally-induced flattening and dust-cloud...
X-ray variability of sigma Orionis young stars with ROSAT (2009)
Caballero, J. A., Lopez-Santiago, J., De Castro, E., Cornide, M.
We 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...
Longitudinal and Transverse Scaling Functions within the Coherent Density Fluctuation Model (2009)
Antonov, A. N., Ivanov, M. V., Barbaro, M. B., Caballero, J. A., De Guerra, E. Moya
We extend our previous description of the superscaling phenomenon in inclusive electron scattering within the Coherent Density Fluctuation Model (CDFM). This model is a natural extension to finite...
Preliminary results on a Virtual Observatory search for companions to Luyten stars (2008)
Caballero, J. A., Miret, F. X., Genebriera, J., Tobal, T., Cairol, J., Montes, D.
The 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...
Caballero, J. A., Sanchez, S. Gonzalez, Caballero, I.
What 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...
New deep XMM-Newton observations to the west of the sigma Orionis cluster (2008)
Lopez-Santiago, J., Caballero, J. A.
Aims: 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...
Caballero, J. A., Valdivielso, L., Martin, E. L., Montes, D., Pascual, S., Perez-Gonzalez, P. G.
Aims: 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...
Chemical abundances of late-type pre-main sequence stars in the $\sigma$-Orionis cluster (2008)
Hernández, J. I. González, Caballero, J. A., Rebolo, R., Béjar, V. J. S., Navascués, D. Barrado Y, Martín, E. L., ...
The 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...
CLOUDS search for variability in brown dwarf atmospheres (2008)
Goldman, B., Cushing, M. C., Marley, M. S., Artigau, É., Baliyan, K. S., Béjar, V. J. S., ...
Context. L-type ultra-cool dwarfs and brown dwarfs have cloudy atmospheres that could host weather-like phenomena. The detection of photometric or spectral variability would provide insight into...
A revisit to agglomerates of early-type Hipparcos stars (2008)
We 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...
Contamination by field late-M, L and T dwarfs in deep surveys (2008)
Caballero, J. A., Burgasser, A. J., Klement, R.
Context: 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...
Martinez, M. C., Caballero, J. A., Donnelly, T. W., Udias, J. M.
Effects of strong final-state interactions in the superscaling properties of neutral-current quasielastic neutrino cross sections are investigated using the Relativistic Impulse Approximation as...
Young stars and brown dwarfs surrounding Alnilam (eps Ori) and Mintaka (del Ori) (2008)
Aims: 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...
Ivanov, M. V., Barbaro, M. B., Caballero, J. A., Antonov, A. N., De Guerra, E. Moya, Gaidarov, M. K.
The superscaling analysis using the scaling function obtained within the coherent density fluctuation model is extended to calculate charge-changing neutrino and antineutrino scattering on $^{12}$C...
Superscaling Predictions for Neutral Current Quasielastic Neutrino-Nucleus Scattering (2008)
Martinez, M. C., Caballero, J. A., Donnelly, T. W., Udias, J. M.
The application of superscaling ideas to predict neutral-current (NC) quasielastic (QE) neutrino cross sections is investigated. Results obtained within the relativistic impulse approximation (RIA)...
CLOUDS search for variability in brown dwarf atmospheres (2008)
Goldman, B., Cushing, M. C., Marley, M. S., Artigau, É., Baliyan, K. S., Béjar, V. J. S., ...
Context: L-type ultra-cool dwarfs and brown dwarfs have cloudy atmospheres that could host weather-like phenomena. The detection of photometric or spectral variability would provide insight into...
New constraints on the membership of the T dwarf S Ori 70 in the σ Orionis cluster (2008)
Zapatero Osorio, M. R., Béjar, V. J. S., Bihain, G., Martín, E. L., Rebolo, R., Villó-Pérez, I., ...
Aims.The nature of S Ori 70 (S Ori J053810.1-023626), a faint mid-T type object found towards the direction of the young sigma Orionis cluster, is still under debate. We intend to find out whether it...
Goldman, B., Cushing, M. C., Marley, M. S., Artigau, É, Baliyan, K. S., Béjar, V. J. S., ...
Context: L-type ultra-cool dwarfs and brown dwarfs have cloudy atmospheres that could host weather-like phenomena. The detection of photometric or spectral variability would provide insight into...
Contamination by field late-M, L, and T dwarfs in deep surveys (2008)
Caballero, J. A., Burgasser, A. J., Klement, R.
Context: Deep photometric surveys of substellar objects in young clusters and high-redshift quasars are affected by contaminant sources at different heliocentric distances. If not correctly taken...
Young stars and brown dwarfs surrounding Alnilam (ε Orionis) and Mintaka (δ Orionis) (2008)
Aims. We look for new regions to search for substellar objects. Methods: Two circular areas, 45 arcmin-radius each, centred on the young massive star systems Alnilam and Mintaka in the Orion Belt,...
Stars and brown dwarfs in the σ Orionis cluster: the Mayrit catalogue (2008)
Context: The young sigma Orionis cluster is an indispensable basis for understanding the formation and evolution of stars, brown dwarfs, and planetary-mass objects. Our knowledge of its stellar...
Science with the new generation high energy gamma- ray experiments (2007)
Alvarez, M., D'Armiento, D., Agnetta, G., Alberdi, A., Antonelli, A., Argan, A., ...
This Conference is the fifth of a series of Workshops on High Energy Gamma- ray Experiments, following the Conferences held in Perugia 2003, Bari 2004, Cividale del Friuli 2005, Elba Island 2006....
Electron and neutrino scattering in the $\Delta$-resonance region and beyond (2007)
Barbaro, M. B., Amaro, J. E., Caballero, J. A., Maieron, C.
We present a unified relativistic approach to inclusive electron scattering based on the relativistic Fermi gas model and on a phenomenological extension of it which accounts for the superscaling...
New constraints on the membership of the T dwarf S Ori 70 in the sigma Orionis cluster (2007)
Osorio, M. R. Zapatero, Bejar, V. J. S., Bihain, G., Martin, E. L., Rebolo, R., Villo-Perez, I., ...
(Abridged) The nature of S Ori 70, a faint mid-T type object found towards the direction of the young sigma Orionis cluster, is still under debate. We intend to disentangle whether it is a field...
GAW - An Imaging Atmospheric Cherenkov Telescope with Large Field of View (2007)
Cusumano, G., Agnetta, G., Alberdi, A., Alvarez, M., Assis, P., Biondo, B., ...
GAW, acronym for Gamma Air Watch, is a Research and Development experiment in the TeV range, whose main goal is to explore the feasibility of large field of view Imaging Atmospheric Cherenkov...
Antonov, A. N., Ivanov, M. V., Barbaro, M. B., Caballero, J. A., De Guerra, E. Moya, Gaidarov, M. K.
The 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...
Caballero, J. A., Amaro, J. E., Barbaro, M. B., Donnelly, T. W., Udias, J. M.
The role of isospin in quasielastic electron scattering and charge-changing neutrino reactions is investigated in the relativistic impulse approximation. We analyze proton and neutron scaling...
Caballero, J. A., Béjar, V. J. S., Rebolo, R., Eislöffel, J., Osorio, M. R. Zapatero, Mundt, R., ...
We 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,...
GRB 051028: an intrinsically faint GRB at high redshift? (2007)
Castro-Tirado, A. J., Jelinek, M., Pandey, S. B., McBreen, S., De Jong, J., Sahu, D. K., ...
We present multiwavelength observations of the gamma-ray burst GRB 051028 detected by HETE-2 in order to derive its afterglow emission parameters and to determine the reason for its optical faintness...
The brightest stars of the sigma Orionis cluster (2007)
Context: 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...
Discs of planetary-mass objects in s Orionis (2007)
Zapatero Osorio, M. R., Caballero, J. A., Béjar, V. J. S., Rebolo, R., Bihain, G., ...
Aims.We searched for infrared flux excesses of planetary-mass candidates in the sigma Orionis cluster (~3 Myr, ~350 pc). Methods: Using IJHKs data from the literature and the [3.6], [4.5], [5.8], and...
Caballero, J. A., Béjar, V. J. S., Rebolo, R., Eislöffel, J., Zapatero Osorio, M. R., Mundt, R., ...
Aims.We 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). Methods: We have performed a deep...
The widest ultracool binary (2007)
Aims.I test the ejection scenario for the formation of brown dwarfs and low-mass stars through the detection of a very wide ultracool binary. Methods: .LEHPM 494 (M6.0 ± 1.0 V) and DENIS-P...
The brightest stars of the s Orionis cluster (2007)
Context: The very young sigma Orionis cluster (~3 Ma) is a cornerstone in understanding the formation of stars and substellar objects down to planetary masses. However, its stellar population is far...
Solvability of a recursive functional equation in the sequence Banach space (2007)
Caballero, J. A., Harjani, J., López, B.L., Sadarangani, Kishin B.
The main aim of this paper is to study the existence of solutions of the following recursive functional equation x(n) = f(n, x(n), x(n - 1)) in the space l2, under general assumptions. The main tools...
Amaro, J. E., Barbaro, M. B., Caballero, J. A., Donnelly, T. W., Udias, J. M.
The semi-relativistic approach to electron and neutrino quasielastic scattering from nuclei is extended to include final-state interactions. Starting with the usual non-relativistic continuum shell...
Quasielastic Charged Current Neutrino-nucleus Scattering (2006)
Amaro, J. E., Barbaro, M. B., Caballero, J. A., Donnelly, T. W.
We provide integrated cross sections for quasielastic charged-current neutrino-nucleus scattering. Results evaluated using the phenomenological scaling function extracted from the analysis of...
GRB 051028: an intrinsically faint GRB at high redshift? (2006)
Castro-Tirado, A. J., Jelinek, M., Pandey, S. B., McBreen, S., De Jong, J., Sahu, D. K., ...
We present multiwavelength observations of the gamma-ray burst GRB 051028 detected by HETE-2 in order to derive its afterglow emission parameters and to determine the reason for its optical faintness...
Antonov, A. N., Ivanov, M. V., Gaidarov, M. K., De Guerra, E. Moya, Caballero, J. A., Barbaro, M. B., ...
Superscaling 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...
Superscaling in lepton-nucleus scattering (2006)
Barbaro, M. B., Amaro, J. E., Caballero, J. A., Donnelly, T. W.
We 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...
A search for substellar members in the Praesepe and sigma Orionis clusters (2006)
Gonzalez-Garcia, B. M., Osorio, M. R. Zapatero, Bejar, V. J. S., Bihain, G., Navascues, D. Barrado Y, Caballero, J. A., ...
(Abridged). We have conducted deep photometric searches for substellar members of the Praesepe (0.5-1 Gyr) and sigma Orionis (3 Myr) star clusters using the Sloan i' and z' filters, the 3.5-m and the...
Caballero, J. A., Martin, E. L., Dobbie, P. D., Navascues, D. Barrado Y
The 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...
Pleiades low-mass brown dwarfs: the cluster L dwarf sequence (2006)
Bihain, G., Rebolo, R., Bejar, V. J. S., Caballero, J. A., Mundt, R., ...
We present a search for low-mass brown dwarfs in the Pleiades open cluster. The identification of Pleiades members fainter and cooler than those currently known allows us to constrain evolutionary...
The 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...
Superscaling and neutral current quasielastic neutrino-nucleus scattering (2006)
Amaro, J. E., Barbaro, M. B., Caballero, J. A., Donnelly, T. W.
The superscaling approach is applied to studies of neutral current neutrino reactions in the quasielastic regime. Using input from scaling analyses of electron scattering data, predictions for...
GRB 051028: An intrinsically faint gamma-ray burst at high redshift? (2006)
Castro-Tirado, A. J., Jelínek, M., Pandey, S. B., McBreen, S., De Jong, J., Sahu, D. K., ...
GRB 051028: an intrinsically faint gamma-ray burst at high redshift? (2006)
Castro-Tirado, A. J., Jelínek, M., Pandey, S. B., McBreen, S., De Jong, J., Sahu, D. K., ...
Aims.We present multiwavelength observations of the gamma-ray burst GRB 051028 detected by HETE-2 in order to derive its afterglow emission parameters and to determine the reason for its optical...
Caballero, J. A., Martín, E. L., Dobbie, P. D.
Context: .Free-floating planetary-mass objects have masses below the deuterium burning mass limit at about 13 Jupiter masses, and have mostly been found in very young open clusters. Their origin and...
Pleiades low-mass brown dwarfs: the cluster L dwarf sequence (2006)
Bihain, G., Rebolo, R., Béjar, V. J. S., Caballero, J. A., Mundt, R., ...
Aims.We present a search for low-mass brown dwarfs in the Pleiades open cluster. The identification of Pleiades members fainter and cooler than those currently known allows us to constrain...
Proper motion Pleiades candidate L-type brown dwarfs (2005)
Bihain, G., Rebolo, R., Bejar, V. J. S., Caballero, J. A., Mundt, R.
We present results of an optical and near-infrared (IR) 1.8 deg^2 survey in the Pleiades open cluster to search for substellar objects. From optical I-band images from the CFHT and J-band images from...
Ultra low-mass star and substellar formation in sigma Orionis (2005)
The 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...
S Ori J053825.4-024241: A Classical T Tauri-like object at the substellar boundary (2005)
Caballero, J. A., Martín, E. L., Osorio, M. R. Zapatero, Béjar, V. J. S., Rebolo, R., Pavlenko, Ya., ...
We present a spectrophotometric analysis of S Ori J053825.4-024241, a candidate member close to the substellar boundary of the young (1-8 Myr), nearby (~360 pc) sigma Orionis star cluster. Our...
Superscaling and Charge-changing Neutrino Cross Sections (2005)
Barbaro, M. B., Amaro, J. E., Caballero, J. A., Donnelly, T. W., Molinari, A., Sick, I.
The 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.
A search for planetary-mass objects and brown dwarfs in the Upper Scorpius association (2005)
Costado, M. T., Bejar, V. J. S., Caballero, J. A., Rebolo, R., Acosta-Pulido, J., Manchado, A.
We report the results of a deep photometric search for planets and brown dwarfs in the nearby young OB Upper Scorpius association. We obtained optical (I) and near-infrared (JKs) images around nine...
Caballero, J. A., Amaro, J. E., Barbaro, M. B., Donnelly, T. W., Maieron, C., Udias, J. M.
Superscaling of the quasielastic cross section in charged current neutrino-nucleus reactions at energies of a few GeV is investigated within the framework of the relativistic impulse approximation....
Amaro, J. E., Barbaro, M. B., Caballero, J. A., Donnelly, T. W., Maieron, C.
The so-called semi-relativistic expansion of the weak charged current in powers of the initial nucleon momentum is performed to describe charge-changing, quasielastic neutrino reactions...
Proper motion Pleiades candidate L-type brown dwarfs (2005)
Bihain, G., Rebolo, R., Béjar, V. J. S., Caballero, J. A., Mundt, R.
We present results of an optical and near-infrared (IR) 1.8 deg2 survey in the Pleiades open cluster to search for substellar objects. From optical I-band images from the CFHT and J-band images from...
Amaro, J. E., Caballero, J. A., Donnelly, T. W., Tabatabaei, F. Kazemi
A study of the total cross section for polarized proton knockout in $(e,e'{\vec p})$ reactions is carried out for the closed-shell nucleus $^{40}$Ca. The dependence of FSI effects on polarization...
Optical Linear Polarization of Late M- and L-Type Dwarfs (2004)
Osorio, M. R. Zapatero, Caballero, J. A., Bejar, V. J. S.
(Abridged). We report on the linear polarimetric observations in the Johnson I filter of 44 M6-L7.5 ultracool dwarfs (2800-1400 K). Eleven (10 L and 1 M) dwarfs appear to have significant linear...
Skewed recoil polarization in (e,e'p) reactions from polarized nuclei (2004)
Amaro, J. E., Barbaro, M. B., Caballero, J. A.
The 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...
A( e→ , e' p→ )B responses: From bare nucleons to complex nuclei (2004)
Vignote, Javier R., Martínez, M.C., Caballero, J.A., Moya De Guerra, Elvira, Udias, J.M.
12 pages, 1 table, 5 figures, 2 appendices.--PACS nrs.: 25.30.Rw; 24.10.Jv; 21.60.Cs.--ArXiv pre-print available at: http://arxiv.org/abs/nucl-th/0312076v2
Amaro, J. E., Barbaro, M. B., Caballero, J. A., Donnelly, T. W., Molinari, A., Sick, I.
Superscaling 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....
Electromagnetic (${\vec e},e'{\vec p}$) Observables & Relativistic Nucleon Dynamics (2004)
Caballero, J. A., Donnelly, T. W., Martínez, M. C., De Guerra, E. Moya, Udías, J. M., Vignote, J. R.
At present there exists a great interest in the search for evidence of possible modification of the nucleon form factors inside the nuclear medium. Recent theoretical work predict changes in the form...
Final state interaction effects in neutrino-nucleus quasielastic scattering (2004)
Maieron, C., Martinez, M. C., Caballero, J. A., Udias, J. M.
We consider the charged-current quasielastic scattering of muon neutrinos on an Oxygen 16 target, described within a relativistic shell model and, for comparison, the relativistic Fermi gas. Final...
Photometric variability of young brown dwarfs in the sigma Orionis open cluster (2004)
Caballero, J. A., Bejar, V. J. S., Rebolo, R., Osorio, M. R. Zapatero
We have carried out multi-epoch, time-series differential I-band photometry of a large sample of objects in the south-east region of the young (~3 Myr), nearby (~350 pc) sigma Orionis open cluster. A...
Uncorrelated scattering approximation revisited (2004)
Moro, A. M., Caballero, J. A., Gomez-Camacho, J.
The 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...
Induced Nucleon Polarization and Meson-Exchange Currents in (e,e'p) Reactions (2004)
Tabatabaei, F. Kazemi, Amaro, J. E., Caballero, J. A.
Nucleon 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...
Nuclear transparencies in relativistic A(e,e'p) models (2004)
Lava, P., Martinez, M. C., Ryckebusch, J., Caballero, J. A., Udias, J. M.
Relativistic and unfactorized calculations for the nuclear transparency extracted from exclusive A(e,e'p) reactions for 0.3 \leq Q^2 \leq 10 (GeV/c)^2 are presented for the target nuclei C, Si, Fe...
A$(\vec{e},e'\vec{p})$B responses: from bare nucleons to complex nuclei (2003)
Vignote, Javier R., Martinez, M. C., Caballero, J. A., De Guerra, E. Moya, Udias, J. M.
We study the occurrence of factorization in polarized and unpolarized observables in coincidence quasi-elastic electron scattering. Starting with the relativistic distorted wave impulse...
Meson Exchange Currents in (\vec{e},e'\vec{p}) observables (2003)
Tabatabaei, Fariba Kazemi, Amaro, J. E., Caballero, J. A., Barbaro, M. B.
Our main aim in this work is to study the effects of meson-exchange currents (MEC) over asymmetries and recoil polarization observables in A(e,e'p)B reactions. This DWIA+MEC model takes care of...
Inelastic electron-nucleus scattering and scaling at high inelasticity (2003)
Barbaro, M. B., Caballero, J. A., Donnelly, T. W., Maieron, C.
Highly 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...
Martínez, M. C., Vignote, J. R., Caballero, J. A., Donnelly, T. W., De Guerra, E. Moya, Udías, J. M.
Recoil nucleon transferred polarization observables in coincidence quasielastic electron scattering are studied within the relativistic distorted wave impulse approximation. Results for response...
Photometric variability of a young, low-mass brown dwarf (2003)
Osorio, M. R. Zapatero, Caballero, J. A., Bejar, V. J. S., Rebolo, R.
We report differential I-band and J-band photometry of S Ori 45, a cool (M8.5), young (1-8 Myr) brown dwarf of the sigma Orionis cluster with a likely mass estimated at around 20 times the mass of...
Meson Exchange Currents in (e,e'p) recoil polarization observables (2003)
Tabatabaei, F. Kazemi, Amaro, J. E., Caballero, J. A.
A 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...
Nuclear model effects in Charged Current neutrino--nucleus quasielastic scattering (2003)
Maieron, C., Martínez, M. C., Caballero, J. A., Udías, J. M.
The quasielastic scattering of muon neutrinos on oxygen 16 is studied for neutrino energies between 200 MeV and 1 GeV using a relativistic shell model. Final state interactions are included within...
Semi-relativistic meson exchange currents in (e,e') and (e,e'p) reactions (2003)
Amaro, J. E., Barbaro, M. B., Caballero, J. A., Tabatabaei, F. Kazemi
Electron-induced one-nucleon knock-out observables are computed for moderate to high momentum transfer making use of semi-relativistic expressions for the one-body and two-body meson-exchange current...
Delta-isobar relativistic meson exchange currents in quasielastic electron scattering (2003)
Amaro, J. E., Barbaro, M. B., Caballero, J. A., Donnelly, T. W., Molinari, A.
We study the role of the $\Delta$-isobar current on the response functions for high energy inclusive quasielastic electron scattering from nuclei. We consider a general Lagrangian which is compatible...
Oliva Paterna, F.J., Andreu, A., Miñano, P.A., Caballero, J. A., Egea Gras, María Antonia, Torralva, M. Mar, ...
The Substellar Population in s Orionis (2003)
Zapatero Osorio, M. R., Béjar, V. J. S., Rebolo, R., Caballero, J. A., Martín, E. L., ...
Relativity in polarized electron scattering observables (2002)
Caballero, J. A., Martínez, M. C., Donnelly, T. W., De Guerra, E. Moya, Udías, J. M., Vignote, J. R.
Coincidence 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...
A Methane Isolated Planetary Mass Object in Orion (2002)
Osorio, M. R. Zapatero, Bejar, V. J. S., Martin, E. L., Rebolo, R., Navascues, D. Barrado Y, Mundt, R., ...
We report on the discovery of a free-floating methane dwarf toward the direction of the young star cluster sigma Orionis. Based on the object's far-red optical and near-infrared photometry and...
Momentum distribution of relativistic nuclei with Hartree-Fock mesonic correlations (2002)
Amaro, J. E., Barbaro, M. B., Caballero, J. A., Donnelly, T. W., Molinari, A.
The impact of Hartree-Fock correlations on the nuclear momentum distribution is studied in a fully relativistic one boson exchange model. Hartree-Fock equations are exactly solved to first order in...
Amaro, J. E., Barbaro, M. B., Caballero, J. A., Donnelly, T. W., Molinari, A.
A consistent analysis of relativistic pionic correlations and meson-exchange currents for electroweak quasielastic electron scattering from nuclei is carried out. Fully-relativistic one-pion-exchange...
Kinematical relativistic effects in $(\vec{e},e'\vec{N})$ reactions (2002)
Martínez, M. C., Caballero, J. A., Donnelly, T. W.
Kinematical relativistic effects are analyzed within the plane-wave impulse approximation for outgoing nucleon polarized responses in coincidence electron scattering. Following recent approaches for...
Martínez, M. C., Caballero, J. A., Donnelly, T. W.
Coincidence 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...
A Methane, Isolated, Planetary-Mass Object in Orion (2002)
Zapatero Osorio, M. R., Béjar, V. J. S., Martín, E. L., Rebolo, R., Navascués, D. Barrado Y., Mundt, R., ...
Direct Imaging and Spectroscopy of a Young Jupiter-like Object (2002)
Martin, E. L., Zapatero Osorio, M. R., Bejar, V. J. S., Rebolo, R., Mundt, R., ...
We report on our continuing effort to identify extremely low-mass members of the cluster around the hot star sigma Orionis. Using the KeckI telescope in Hawaii and the Isaac Newton telescope in La...
Recent Developments in relativistic models for exclusive (e,e'p) reactions (2001)
Udias, J. M., Vignote, Javier R., De Guerra, E. Moya, Escuderos, A., Caballero, J. A.
A 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...
Kinematical versus dynamical relativistic effects in A(\vec{e},e'\vec{p})B (2001)
Martínez, M. C., Caballero, J. A., Donnelly, T. W.
The 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...
Consistent one-pion exchange currents in electron scattering from a relativistic Fermi gas (2001)
Amaro, J. E., Barbaro, M. B., Caballero, J. A., Donnelly, T. W., Molinari, A.
A set of fully relativistic one-pion-exchange electromagnetic operators is developed for use in one-particle emission reactions induced by electrons. To preserve the gauge invariance of the theory...
Relativistic pionic effects in quasielastic electron scattering (2001)
Amaro, J. E., Barbaro, M. B., Caballero, J. A., Donnelly, T. W., Molinari, A.
The 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...
Moro, A. M., Caballero, J. A., Gómez-Camacho, J.
The 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...
Udias, J. M., Caballero, J. A., De Guerra, E. Moya, Vignote, Javier R., Escuderos, A.
We use the relativistic distorted wave impulse approximation to analyze data on 16O(e,e'p)15N at |Q^2|\leq 0.4 (GeV/c)^2 that were obtained by different groups and seemed controversial. Results for...
Relativistic effects in electromagnetic nuclear responses in the quasi-elastic delta region (1999)
Amaro, J. E., Barbaro, M. B., Caballero, J. A., Donnelly, T. W., Molinari, A.
A 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...
Quaiselastic scattering from relativistic bound nucleons: Transverse-Longitudinal response (1999)
Udias, J. M., Caballero, J. A., De Guerra, E. Moya, Amaro, J. E., Donnelly, T. W.
Predictions for electron induced proton knockout from the $p_{1/2}$ and $p_{3/2}$ shells in $^{16}$O are presented using various approximations for the relativistic nucleonic current. Results for the...
Analysis of Meson Exchange and Isobar Currents in (e,e'p) Reactions from O-16 (1999)
Amaro, J. E., Lallena, A. M., Caballero, J. A.
An 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...
Alberico, W. M., Barbaro, M. B., Bilenky, S. M., Caballero, J. A., Giunti, C., Maieron, C., ...
We consider ratios of elastic neutrino(antineutrino)-proton cross sections measured by the Brookhaven BNL-734 experiment and use them to obtain the neutral current (NC) over charged current (CC)...
Caballero, J. A., Donnelly, T. W., De Guerra, E. Moya, Udias, J. M.
Scalar, baryon and vector--current densities in coordinate and momentum space are calculated within a relativistic mean--field model. The role of the low components of the bound nucleon wave function...
Amaro, J. E., Barbaro, M. B., Caballero, J. A., Donnelly, T. W., Molinari, A.
Following 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...
Inclusive quasielastic scattering of polarized electrons from polarized nuclei (1998)
Amaro, J. E., Caballero, J. A., Donnelly, T. W., De Guerra, E. Moya
The inclusive quasielastic response functions that appear in the scattering of polarized electrons from polarized nuclei are computed and analyzed for several closed-shell-minus-one nuclei with...
Alberico, W. M., Barbaro, M. B., Bilenky, S. M., Caballero, J. A., Giunti, C., Maieron, C., ...
We calculate the ratio of proton and neutron yields in NC induced neutrino(antineutrino)-nucleus inelastic scattering at neutrino energies of about 1 GeV. We show that this ratio depends very weakly...
Caballero, J. A., Donnelly, T. W., De Guerra, E. Moya, Udias, J. M.
The issue of factorization within the context of coincidence quasi-elastic electron scattering is reviewed. Using a relativistic formalism for the entire reaction mechanism and restricting ourselves...
Inelastic neutrino and antineutrino scattering on nuclei and ``strangeness'' of the nucleon (1997)
Alberico, W. M., Barbaro, M. B., Bilenky, S. M., Caballero, J. A., Giunti, C., Maieron, C., ...
Possibilities to extract information on the strange form factors of the nucleon from neutrino (antineutrino) inelastic scattering on nuclei, in an energy range from 200 MeV to 1 GeV and more, are...
Relativistic analysis of the 208Pb(e,e'p)207Tl reaction at high momentum (1996)
Udias, J. M., Sarriguren, P., De Guerra, E. Moya, Caballero, J. A.
The recent 208Pb(e,e'p)207Tl data from NIKHEF-K at high missing momentum (p_m>300 MeV/c) are compared to theoretical results obtained with a fully relativistic formalism previously applied to analyze...
Parity violation in quasielastic electron scattering from closed-shell nuclei (1995)
Amaro, J. E., Caballero, J. A., Donnelly, T. W., Lallena, A. M., De Guerra, E. Moya, Udias, J. M.
The electromagnetic and weak neutral current matrix elements that enter in the analysis of parity-violating quasielastic electron scattering are calculated using a continuum nuclear shell model. New...
Probing Deformed Orbitals with \vec{A}(\vec{e}, e' N)B reactions (1994)
Garrido, E., Caballero, J. A., De Guerra, E. Moya, Sarriguren, P., Udias, J. M.
We present results for response functions and asymmetries in the nuclear reactions 37\vec{Ar}(\vec{e},e'n)36Ar and 37\vec{K}(\vec{e},e' p)36Ar at quasifree kinematics. We compare PWIA results...
Spin dependent Momentum Distributions in Deformed Nuclei (1994)
Caballero, J. A., Garrido, E., De Guerra, E. Moya, Sarriguren, P., Udias, J. M.
We study the properties of the spin dependent one body density in momentum space for odd--A polarized deformed nuclei within the mean field approximation. We derive analytic expressions connecting...
Relativistic versus Nonrelativistic Optical Potentials in A(e,e'p)B Reactions (1993)
Udias, J. M., Sarriguren, P., De Guerra, E. Moya, Garrido, E., Caballero, J. A.
We investigate the role of relativistic and nonrelativistic optical potentials used in the analysis of ($e,e'p$) data. We find that the relativistic calculations produce smaller ($e,e'p$) cross...
Spectroscopic Factors in $^{40}$Ca and $^{208}$Pb from $(e,e'p)$: Fully Relativistic Analysis (1993)
Udias, J. M., Sarriguren, P., De Guerra, E. Moya, Garrido, E., Caballero, J. A.
We present results for spectroscopic factors of the outermost shells in $^{40}$Ca and $^{208}$Pb, which have been derived from the comparison between the available quasielastic ($e,e'p$) data from...
Caballero, J. A., Donnelly, T. W., Poulis, G. I., Garrido, E., De Guerra, E. Moya
Coincidence reactions of the type $\svec{A}(\svec{e},e'N)B$ involving the scattering of polarized electrons from deformed polarized targets are discussed within the context of the plane--wave impulse...