Ponente
Prof.
Xavier Viñas
(Universitat de Barcelona)
Descripción
The nuclear symmetry energy J is an essential quantity in nuclear physics and astrophysics because it governs important properties of small entities like atomic nuclei and of very large objects as neutron stars. The nuclear symmetry energy represents the energy cost of changing protons in neutrons in symmetric nuclear matter. The symmetry energy can be estimated as a function of the density as the difference between the energy per particle in pure neutron matter and in symmetric nuclear matter. The behaviour of the symmetry energy as a function of the density is basically ruled by the its slope respect to the density computed at saturation L. Although the symmetry energy and its slope are not strictly observables, many different experiments have been devised to estimate these quantities using strong and electromagnetic probes [1]. We will discuss here our predictions of the symmetry energy and its slope obtained from three different experiments. First, we estimate the slope of the symmetry energy L from experimental data of the neutron skin thickness extracted from antiprotonic atoms [2-5]. Second, we discuss the ability of parity-violating elastic electron scattering at low momentum transfer to obtain information on the neutron skin thickness in 208Pb and to constraint the density dependence of the nuclear symmetry energy [6-7]. Finally, we compare the experimental electric dipole polarizability obtained via polarized proton inelastic scattering at forward angles in 208Pb, 120Sn and 68Ni [8,9] with the corresponding theoretical RPA calculations, which allow to estimate the symmetry energy J and its slope L.
All these experiments provide different constraints on the slope L of the symmetry energy but the corresponding values have a considerable overlap in a range around , in reasonable agreement with other estimates that use different observables and methods to extract L. A global review about our work on these three topics can be found in Refs [10,11].
Referencias
[1]. Bao-An Li, Xiao Han, Phys. Lett. B727 (2013) 276.
[2]. M. Centelles, X. Roca-Maza, X. Viñas, M. Warda, Phys. Rev. Lett. 102 (2009) 122502 .
[3]. M. Warda, M. Centelles, X. Roca-Maza, X. Viñas, Phys. Rev. C80 (2009) 024316.
[4]. M. Warda, M. Centelles, X, Roca-Maza, X. Viñas, Phys. Rev. C81 (2010) 054309.
[5]. M. Warda, M. Centelles, X. Viñas, X. Roca-Maza, Phys. Rev. C89 (2014) 064302 .
[6]. M. Centelles, X. Roca-Maza, X. Viñas, M. Warda, Phys. Rev. C82 (2010) 054314.
[7]. X. Roca-Maza, M. Centelles, X. Viñas, M. Warda, Phys. Rev. Lett. 106 (2011) 252501.
[8]. X. Roca-Maza et al, Phys. Rev. C88 (2013) 024316 .
[9]. X. Roca-Maza et al, Phys. Rev. C92 (2015) 064304 .
[10]. X. Viñas, M. Centelles, X. Roca-Maza, M. Warda, Eur. Phys. J. 50 (2014) 27 .
[11]. X. Viñas, M. Centelles, X. Roca-Maza, M. Warda, AIP Proceedings 1606 (2013) 256.
Autor primario
Prof.
Xavier Viñas
(Universitat de Barcelona)
