10,141 research outputs found
Prosas dispersas de Vicente Barbieri
No full textTabla de contenidos: Prosas dispersas. Contribución a la bibliografía de Vicente Barbieri
Prosas dispersas de Vicente Barbieri
No full textTabla de contenidos: Prosas dispersas. Contribución a la bibliografía de Vicente Barbieri
Prosas dispersas de Vicente Barbieri
No full textTabla de contenidos: Prosas dispersas. Contribución a la bibliografía de Vicente Barbieri
Algebraic diagrammatic construction formalism with three-body interactions
No full textBackground: Self-consistent Green's function theory has recently been extended to the basic formalism needed to account for three-body interactions [Carbone, Cipollone, Barbieri, Rios, and Polls, Phys. Rev. C 88, 054326 (2013)PRVCAN0556-281310.1103/PhysRevC.88.054326]. The contribution of three-nucleon forces has so far been included in ab initio calculations on nuclear matter and finite nuclei only as averaged two-nucleon forces. Purpose: We derive the working equations for all possible two- and three-nucleon terms that enter the expansion of the self-energy up to the third order, thus including the interaction-irreducible (i.e., not averaged) diagrams with three-nucleon forces that have been previously neglected. Methods: We employ the algebraic diagrammatic construction up to the third order as an organization scheme for generating a nonperturbative self-energy, in which ring (particle-hole) and ladder (particle-particle) diagrams are resummed to all orders. Results: We derive expressions of the static and dynamic self-energy up to the third order, by taking into account the set of diagrams required when either the skeleton or nonskeleton expansions of the single-particle propagator are assumed. A hierarchy of importance among different diagrams is revealed, and a particular emphasis is given to a third-order diagram [see Fig. 2(c)] that is expected to play a significant role among those featuring an interaction-irreducible three-nucleon force. Conclusion: A consistent formalism to resum at infinite order correlations induced by three-nucleon forces in the self-consistent Green's function theory is now available and ready to be implemented in the many-body solvers
[Barbieri Mattioli (c.1817), funerary sculpture]
No full textFrom Berresford: Barbieri Mattioli (c.1817), Giovanni Putti, Cimitero della Certosa, Bologna.Portrait medallion of Isabella Barbieri Mattioli on tomb with figures surrounding monument.Title from Berresford
A stable auroral red arc over Europe
No full textUsing a new all-sky-imaging system, M Mendillo, C Barbieri, J Baumgardner, J Wroten, G Cremonese and G Umbriaco observed two distinctive types of aurora over London and western Europe on the night of 26-27 September 2011, including the first ground-based image of a stable auroral red arc over Europe. 2012 Royal Astronomical Society
Prefazione [La fantasia del reale. Esopo e la favola]
No full textNella Prefazione al volume, i due curatori - Nicola Barbieri e Annamaria Contini - ricostruiscono le motivazioni all'origine della lettura della favola in chiave interdisciplinare, discutendo alcune teorie contemporanee e soffermandosi sulle valenze formative del racconto
Chiral three-nucleon forces and the evolution of correlations along the oxygen isotopic chain
No full textBackground: Three-nucleon forces (3NFs) have nontrivial implications on the evolution of correlations at extreme proton-neutron asymmetries. Recent ab initio calculations show that leading-order chiral interactions are crucial to obtain the correct binding energies and neutron driplines along the O, N, and F chains [A. Cipollone, C. Barbieri, and P. Navrátil, Phys. Rev. Lett. 111, 062501 (2013)PRLTAO0031-900710.1103/PhysRevLett.111.062501]. Purpose: Here we discuss the impact of 3NFs along the oxygen chain for other quantities of interest, such has the spectral distribution for attachment and removal of a nucleon, spectroscopic factors, and radii. The objective is to better delineate the general effects of 3NFs on nuclear correlations. Methods: We employ self-consistent Green's function (SCGF) theory which allows a comprehensive calculation of the single-particle spectral function. For the closed subshell isotopes, O14, O16, O22, O24, and O28, we perform calculations with the Dyson-ADC(3) method, which is fully nonperturbative and is the state of the art for both nuclear physics and quantum chemistry applications. The remaining open-shell isotopes are studied using the newly developed Gorkov-SCGF formalism up to second order. Results: We produce complete plots for the spectral distributions. The spectroscopic factors for the dominant quasiparticle peaks are found to depend very little on the leading-order (NNLO) chiral 3NFs. The latter have small impact on the calculated matter radii, which, however, are consistently obtained smaller than experiment. Similarly, single-particle spectra tend to be too spread with respect to the experiment. This effect might hinder, to some extent, the onset of correlations and screen the quenching of calculated spectroscopic factors. The most important effect of 3NFs is thus the fine tuning of the energies for the dominant quasiparticle states, which governs the shell evolution and the position of driplines. Conclusions: Although present chiral NNLO 3NFs interactions do reproduce the binding energies correctly in this mass region, the details of the nuclear spectral function remain at odds with the experiment showing too-small radii and a too-spread single-particle spectrum, similar to what has already been pointed out for larger masses. This suggests a lack of repulsion in the present model of NN+3N interactions, which is mildly apparent already for masses in the A=14-28 mass range
Dentro il cabinet. Novità istituzionali nei rapporti tra ministri
No full textUn quadro comparativo sulla distribuzione del potere entro il cabinet. Il caso italiano e i cambiamenti degli ultimi lustri
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