Three-body soft dipole mode and astrophysical applications


Seminar “Nuclear Theory”

Date and Time: Monday, 19 October 2020, at 3:30 PM

Venue: Online conference in Zoom, Bogoliubov Laboratory of Theoretical Physics

Seminar topic: «Three-body soft dipole mode and astrophysical applications»

Authors: L. V. Grigorenko1,2,3, Yu. L. Parfenova1, N. B. Shulgina3,4, M.V. Zhukov5

1 – FLNR, JINR, Dubna, Russia
2 – NRN University “MEPhI”, Moscow, Russia
3 – NRC “Kurchatov Institute” Moscow, Russia
4 – BLTP, JINR, Dubna, Russia
5 – Chalmers University of Technology, Goteborg, Sweden

Speaker: N. B. Shulgina


Theoretical methods have been developed that allow correct describing of soft dipole excitations in a wide range of energies: from very small ∼10-500 keV, which are important for nuclear astrophysics, to ∼10 MeV, where the dipole excitations are no longer soft. For the first time, correct low-energy asymptotics for E1 strength functions of three-body radiative captures “core + n + n” and “core + p + p” and the corresponding correct low-temperature asymptotics of astrophysical rates of three-body radiative captures are obtained. The results for the studied cases of 6He and 17Ne differ sharply (by orders of magnitude) from all previously obtained results. It is shown that for radiative captures of “core + n + n” the dynamics of the n-n interaction in the final state dominates, while for radiative captures of “core + p + p” the dynamics of interaction in the subsystem “core + p” dominates, which is well described in the semi-analytical model with a simplified three-body Hamiltonian. A completely analytical generalization of the method of asymptotic normalization coefficients is constructed for the case of nonresonant three-body proton captures at astrophysical energies. The high accuracy of this approximation is substantiated.

(to be nominated for the JINR Prize 2020)