Bogoliubov Laboratory of Theoretical Physics

Seminar on Nuclear Theory

Date and Time: Monday, 3 October 2022, at 3:30 PM

Venue: Blokhintsev lecture hall, Bogoliubov Laboratory of Theoretical Physics, online on Zoom

Information about seminar and link to join

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.

Applying a developed approach, 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 in hot nuclei in a thermodynamically consistent way. The method ensures the fulfillment of the detailed balance principle and, unlike shell model calculations, does not require the use of the Brink-Axel hypothesis. Based on the quasiparticle-phonon nuclear model, equations are obtained considering the effect of the coupling of simple and complex configurations on the excitation strength functions in hot nuclei.

On the example of selected iron group nuclei and neutron-rich nuclei with N ≈ 50 and using the Skyrme EDF the influence of temperature on the rates and cross sections for various weak-interaction reactions (electron capture, inelastic neutrino scattering, etc.), which play an important role in the late stages of massive star evolution, was 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.

(To be nominated for the JINR Prize 2022)