Lauro Tomio

Bethe–Salpeter bound-state structure in Minkowski space

Abstract The quantitative investigation of the scalar Bethe–Salpeter equation in Minkowski space, within the ladder-approximation framework, is extended to include the excited states. This study has been carried out for an interacting system composed by two massive bosons exchanging a massive scalar, by adopting (i) the Nakanishi integral representation of the Bethe–Salpeter amplitude, and (ii) the formally exact projection onto the null plane. Our analysis, on one hand, confirms the reliability of the method already applied to the ground state and, on the other one, extends the investigation from the valence distribution in momentum space to the corresponding quantity in the impact-parameter space, pointing out some relevant features, like (i) the equivalence between Minkowski and Euclidean transverse-momentum amplitudes, and (ii) the leading exponential fall-off of the valence wave function in the impact-parameter space.

Neutron-19C scattering: Emergence of universal properties in a finite range potential

The low-energy properties of the elastic s-wave scattering for the n-19C are studied near the critical condition for the occurrence of an excited Efimov state in n–n-18C. It is established to which extent the universal scaling laws, strictly valid in the zero-range limit, survive when finite range potentials are considered. By fixing the two-neutrons separation energy in 20C with available experimental data, it is studied the scaling of the real (δ0R) and imaginary parts of the s-wave phase-shift with the variation of the n-18C binding energy. We obtain some universal characteristics given by the pole-position of kcot⁡(δ0R) and effective-range parameters. By increasing the n-18C binding energy, it was verified that the excited state of 20C goes to a virtual state, resembling the neutron–deuteron behavior in the triton. It is confirmed that the analytical structure of the unitary cut is not affected by the range of the potential or mass asymmetry of the three-body system.

Core momentum distribution in two-neutron halo nuclei

Abstract The core momentum distribution of a weakly-bound neutron–neutron–core exotic nucleus is computed within a renormalized zero-range three-body model, with interactions in the s-wave channel. The halo wave-function in momentum space is obtained by using as inputs the two-body scattering lengths and the two-neutron separation energy. The core momentum densities are computed for 11 Li, 14 Be 20 C and 22 C. The model describes the experimental data for 11 Li, 14 Be and to some extent 20 C. The recoil momentum distribution of the 20 C from the breakup of 22 C nucleus is computed for different two-neutron separation energies, and from the comparison with recent experimental data the two-neutron separation energy is estimated in the range 100 ≲ S 2 n ≲ 400 keV . The recoil momentum distribution depends weakly on the neutron- 20 C scattering length, while the matter radius is strongly sensitive to it. The expected universality of the momentum distribution width is verified by also considering excited states for the system.

Universality in the Neutron–\(^{\mathbf {19}}\)C Scattering Using Finite-Range Separable Interactions

We report a study on the low-energy properties of the elastic s-wave scattering of a neutron (n) in the carbon isotope

On the Kaon-prime anti-s structure function from the strangeness asymmetry in the nucleon

^{19}

Minkowski space approach for the Bethe-Salpeter equation

19C near the critical condition for the occurrence of an excited Efimov state in the three-body n–n–

\kappa

^{18}