Ab initio calculations of mirror energy difference in sd-shell nuclei

Mirror energy difference is a key observable in isospin symmetry breaking,containing rich information about nuclear structure.Understanding the mechanisms underlying mirror energy difference is important in nuclear physics.In the present work,we extensively investigated mirror energy difference using ab initio valence-space inmedium similarity renormalization group approach,focusing specifically on sd-shell nuclei.The low-lying spectra of Al isotopes and N=8 isotones,together with their mirror nuclei,were calculated,followed by a systematic analysis of the evolution of the mirror energy difference.The results suggest that the large mirror energy difference is mainly caused by the weakly-bound effects and large average occupations of the 1s1/2 orbit.Lastly,we compare the results of our ab initio calculations with shell model results,elucidating the relationship and coherence between these two models.