Hoyle-analogue state in 13C studied with Antisymmetrized Molecular Dynamics

TL;DR

This study investigates cluster states in 13C using antisymmetrized molecular dynamics, identifying a Hoyle-analogue state and analyzing transition strengths to understand their structure and properties.

Contribution

It reveals the structure of excited states in 13C, especially identifying the 1/2+_2 state as a Hoyle-analogue, and analyzes transition strengths to distinguish different configurations.

Findings

The 1/2+_2 state is a Hoyle-analogue with a specific cluster configuration.

Excited 1/2- states show strong isoscalar monopole transitions.

Excited 1/2+ states generally have weak isoscalar dipole transitions.

Abstract

The cluster states in $^{13}{\rm C}$ are investigated by antisymmetrized molecular dynamics. By investigating the spectroscopic factors, the cluster configurations of the excited states are discussed. It is found that the $1/2^+_2$ state is dominantly composed of the $^{12}{\rm C}(0^+_2)\otimes s_{1/2}$ configuration and can be regarded as a Hoyle analogue state. On the other hand, the p-wave states ($3/2^-$ and $1/2^-$) do not have such structure, because of the coupling with other configurations. The isoscalar monopole and dipole transition strengths from the ground to the excited states are also studied. It is shown that the excited $1/2^-$ states have strong isoscalar monopole transition strengths consistent with the observation. On the other hand, the excited $1/2^+$ states unexpectedly have weak isoscalar dipole transitions except for the $1/2^+_1$ state. It is discussed that the suppression of the dipole transition is attributed to the property of the dipole operator.