Inclusive Nucleon Emission Induced by Quasi--Elastic Neutrino--Nucleus Interactions

We study the quasi--elastic contribution to the inclusive $(\nu_l,\nu_l N)$, $(\nu_l,l^- N)$, $({\bar \nu}_l,{\bar \nu}_l N)$ and $({\bar \nu}_l,l^+ N)$ reactions in nuclei using a Monte Carlo simulation method to account for the rescattering of the outgoing nucleon. As input, we take the reaction probability from the microscopical many body framework developed in Phys. Rev. {\bf C70} (2004) 055503 for charged-current induced reactions, while for neutral currents we use results from a natural extension of the model described in that reference. The nucleon emission process studied here is a clear signal for neutral--current neutrino driven reactions, that can be used in the analysis of future neutrino experiments.Comment: 23 pages, 17 figures; Version 2: few typos correcte

Antisymmetrized random phase approximation for quasielastic scattering in nuclear matter: Non-relativistic potentials

Many-body techniques for the calculation of quasielastic nuclear matter response functions in the fully antisymmetrized random phase approximation on a Hartree-Fock basis are discussed in detail. The methods presented here allow for an accurate evaluation of the response functions with little numerical effort. Formulae are given for a generic non-relativistic potential parameterized in terms of meson exchanges; on the other hand, relativistic kinematical effects have been accounted for.Comment: 27 pages, 7 figures; uses revtex and epsfig; minor changes; typos in some formulae have been corrected and references have been adde

Unusual Bronchopulmonary Foregut Malformation Associated with Pericardial Defect: Bronchogenic Cyst Communicating with Tubular Esophageal Duplication

We report a case of unusual bronchopulmonary foregut malformation composed of a mediastinal bronchogenic cyst with sequestrated lung tissue and communicating tubular esophageal duplication associated with complete pericardial defect. A 18-yr-old man, who had suffered from dry cough and mild dyspnea, was admitted because of an incidentally detected chest mass. A computed tomography scan demonstrated a cystic mass with an air fluid level connected with esophagus in the middle mediastinum. The surgically resected mass was a pleural invested accessory lobe of the lung (8.0×7.0×4.5 cm) connected with the esophageal wall by a tubular structure (3.0 cm in length and 2.0 cm in diameter). A complete left pericardial defect was also identified. Histologically, the cystic wall was composed of fibrovascular connective tissue with a smooth muscle layer, mixed seromucous glands and cartilage, and the inner surface of the cyst was lined by ciliated pseudostratified columnar epithelium. The inner surface of the tubular structure was lined by non-keratinizing or keratinizing squamous epithelium, and the wall contained submucosal mucous glands, muscularis mucosa, and duplicated muscularis propria. This case is important in understanding the embryological pathogenesis of the variable spectrum of the bronchopulmonary foregut malformation

Structure and Coulomb dissociation of 23O within the quark-meson coupling model

We study the ground-state structure of nuclei in the vicinity of the one-neutron dripline within the latest version of the quark-meson coupling (QMC) model with a particular emphasis on 23O. For this nucleus the model predicts a [22O(0+) + n (2s_{1/2})] configuration for its ground state, with a one neutron separation energy in close agreement with the corresponding experimental value. The wave function describing the valence neutron-core relative motion was then used to calculate the Coulomb dissociation of 23O on a lead target at a beam energy of 422 MeV/nucleon. The experimental neutron-core relative energy spectrum and the total one-neutron removal cross sections are well described by the calculations. The widths of the longitudinal momentum distributions of the 22O fragment are found to be broad, which do not support the formation of a neutron halo in this nucleus.Comment: Revised and extended version, accepted for publication in Nucl. Phys.

Many Body approach to the inclusive (e,e′)(e,e') reaction from the quasielastic to the Δ\Delta excitation region

We have performed a many body calculation of the inclusive (e,e') cross section which runs over the three traditional regions at intermediate energies: the quasielastic peak, the dip region and the delta region. The longitudinal and transverse response functions in the quasielastic peak have also been evaluated. Traditional effects like polarization, meson exchange currents, final state interaction and delta renormalization in the nuclear medium have been included. Meson exchange currents are generated from a model of pion electroproduction on the nucleon which reproduces accurately the experimental data. The inclusive cross section accounts for 1N,2N,3N mechanisms of virtual photon absorption and one pion production. Meson exchange currents associated to the (\gamma^*,2\pi) reaction are also accounted for. We obtain good results for the (e,e') cross sections in the whole energy range and for different nuclei. The response functions are also in good agreement with the latest experimental analysis. On the other hand, the method provides the separation of the contribution to the inclusive cross section from different physical channels which is a necessary input to evaluate cross sections like (e,e' N), (e,e' NN), (e,e' \pi) etc.Comment: 65 pages (LaTeX + ps-figure files

Coherent Photoproduction of Eta-Mesons on Spin-Zero Nuclei in a Relativistic, Non-local Model

The coherent photoproduction of $\eta$-mesons on spin-zero nuclei is studied in a relativistic, non-local model, which we have previously applied to the coherent photoproduction of pions. We find that different off-shell extrapolations of the elementary production operator lead to large effects in the cross section. We also show that the almost complete suppression of the N(1535) seen in earlier studies on this reaction is a result of the local or factorization approximation used in these works. Non-local effects can lead to a considerable contribution from this resonance. The relative size of the N(1535) contribution depends on the structure of the nucleus under consideration. We give an estimate for the contribution of the N(1520) resonance and discuss the effect of an $\eta$-nucleus optical potentialComment: 29 pages, 14 figures; slight changes in presentation, extended discussion, one new figur

The Axial Charge Renormalization in a Relativistic Description of Finite Nuclei

Starting from a realistic One-Boson-Exchange model of the nucleon nucleon interaction the relativistic mean field for nucleons is determined within the Dirac Brueckner Hartree Fock approach for finite nuclei. The matrix elements of the axial charge operator evaluated for the solutions of the Dirac equation with this selfenergy are investigated. These matrix elements are enhanced with respect to the equivalent non relativistic ones obtained from the solutions of the Schr\'odinger equation with the non relativistic equivalent potential. The present results confirm at a qualitative level the results for the axial charge renormalization obtained with perturbative approaches. However, the results obtained differ in size from those of the perturbative approach and are nucleus and state dependent

Neutrino-nucleus quasi-elastic scattering and strange quark effects

A relativistic distorted-wave impulse-approximation model is applied to quasi-elastic neutrino-nucleus scattering. The bound state is obtained in the framework of the relativistic mean field theory and the final state interaction is taken into account in the scattering state. Results for the charged- and neutral-current neutrino (antineutrino) reactions on $^{12}$C target nucleus are presented and the sensitivity of various quantities to the strange quark content of the nucleon weak current is discussed.Comment: 18 pages, 10 figure

Sensitivities of the Proton-Nucleus Elastical Scattering Observables of 6He and 8He at Intermediate Energies

We investigate the use of proton-nucleus elastic scattering experiments using secondary beams of 6He and 8He to determine the physical structure of these nuclei. The sensitivity of these experiments to nuclear structure is examined by using four different nuclear structure models with different spatial features using a full-folding optical potential model. The results show that elastic scattering at intermediate energies (<100 MeV per nucleon) is not a good constraint to be used to determine features of structure. Therefore researchers should look elsewhere to put constraints on the ground state wave function of the 6He and 8He nuclei.Comment: To be published in Phys. Rev.

Presence of Mycoplasma fermentans in the bloodstream of Mexican patients with rheumatoid arthritis and IgM and IgG antibodies against whole microorganism

<p>Abstract</p> <p>Background</p> <p>Increasing evidence incriminates bacteria, especially <it>Mycoplasma fermentans</it>, as possible arthritogenic agents in humans. The purpose of this study was to investigate <it>M. fermentans </it>in the bloodstream of patients with rheumatoid arthritis.</p> <p>Methods</p> <p>Two hundred and nineteen blood samples from patients with rheumatoid arthritis, systemic lupus erythematosus, antiphospholipid syndrome, and healthy individuals were screened by bacterial culture and direct PCR in order to detect mycoplasmas; IgM and IgG against <it>M. fermentans </it>PG18 were also detected by ELISA and Immunoblotting assays in patients with rheumatoid arthritis and healthy individuals.</p> <p>Results</p> <p>Blood samples from patients with antiphospholipid syndrome and healthy individuals were negative for mycoplasma by culture or direct PCR. In blood samples from patients with systemic lupus erythematosus were detected by direct PCR <it>M. fermentans </it>in 2/50 (2%), <it>M. hominis </it>in 2/50 (2%) and <it>U. urealyticum </it>in 1/50 (0.5%). In patients with RA <it>M. fermentans </it>was detected by culture in 13/87 blood samples and in 13/87 by direct PCR, however, there was only concordance between culture and direct PCR in six samples, so <it>M. fermentans </it>was detected in 20/87(23%) of the blood samples from patients with RA by either culture or PCR. Antibody-specific ELISA assay to <it>M. fermentans </it>PG18 was done, IgM was detected in sera from 40/87 patients with RA and in sera of 7/67 control individuals, IgG was detected in sera from 48/87 RA patients and in sera from 7/67 healthy individuals. Antibody-specific immunoblotting to <it>M. fermentans </it>PG18 showed IgM in sera from 35/87 patients with RA and in sera from 4/67 healthy individuals, IgG was detected in sera from 34/87 patients and in sera from 5/67 healthy individuals.</p> <p>Conclusion</p> <p>Our findings show that only <it>M. fermentans </it>produce bacteremia in a high percentage of patients with RA. This finding is similar to those reported in the literature. IgM and IgG against <it>M. fermentans </it>PG18 were more frequent in patients with RA than healthy individuals.</p