Estimation of 2p2h effect on Gamow-Teller transition with Second Tamm-Dancoff-Approximation

TL;DR

This paper investigates the impact of 2p2h effects on Gamow-Teller transitions in neutron-rich nuclei using the second Tamm-Dancoff approximation with Skyrme interaction, revealing significant quenching and fragmentation of GT strengths.

Contribution

It introduces a novel application of the second Tamm-Dancoff approximation to study 2p2h effects on GT transitions, highlighting the role of tensor forces in strength distribution.

Findings

20% quenching and downward shift of GT giant resonances.

17-26% of GT strength shifted to high energy above GTGRs.

Tensor force significantly affects high-energy GT strength distribution.

Abstract

Two-particle two-hole (2p2h) effect on the Gamow-Teller (GT) transition for neutron-rich nuclei is studied by the second Tamm-Dancoff approximation (STDA) with the Skyrme interaction. Unstable $^{24}$O and $^{34}$Si, and stable $^{48}$Ca nuclei are chosen to study the quenching and fragmentation of the GT strengths. Correlation of the 2p2h configurations causes $20$\% quenching and downward shift of GT giant resonances (GTGRs). The residual interaction changing relative angular momentum, appeared in the tensor force part, gives a meaningful effect to the GT strength distributions. In this work, $17$ to $26$ \% of the total GT strengths are brought to high energy region above GTGRs. In particular, the tensor force brings strengths to high energy more than $50$ MeV. STDA calculation within a small model space for 2p2h configuration is also performed and experimental data of $^{48}$Ca is reproduced reasonably.