Bogoliubov Laboratory of Theoretical Physics

Seminar on Nuclear Theory

Date and Time: Monday, 25 October 2021, at 3:30 PM

Venue: Blokhintsev lecture hall (4th floor), Bogoliubov Laboratory of Theoretical Physics, online seminar on Zoom

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Seminar topic: “Superoperator approach to the theory of hot nuclei and astrophysical applications”

Speaker: Alan A. Dzhioev

Abstract:

The method of superoperators in Liouville space was applied to study equilibrium and excited states of hot nuclei. It is shown for the first time that properly defined fermionic superoperators allow us to generalize the equation of motion method to hot nuclei. Within the developed approach and using the Skyrme energy density functional, we derived the equations of thermal quasiparticle random phase approximation. From these equations one can calculate the strength functions of charge-exchange and charge-neutral excitations of hot nuclei in a thermodynamically consistent way, avoiding the use of the Axel-Brink hypothesis and violation of the detailed balance principle. Based on the quasiparticle phonon nuclear model a method for accounting the coupling of simple and complex configurations in hot nuclei is proposed. By the example of selected iron group nuclei and neutron-rich nuclei with N∼50, the temperature effects on the rates and cross sections of various weak-interaction mediated reactions (electron capture, inelastic neutrino scattering, etc.) playing an important role at the late stages of massive star evolution, were studied. It is shown that thermodynamically consistent incorporation of thermal effects leads to a stronger temperature dependence of the rates and cross sections than predicted by the shell model calculations.

(based on the doctoral thesis)