On the prediction of mirror symmetry violation in rotational properties for A ≈ 80 nuclei*

Abstract Within the framework of the microscopic-macroscopic model, using total Routhian surface calculations in the three-dimensional space ( , γ , and ), a systematic investigation of mirror-pair nuclei 74 Kr- 74 Sr, 78 Sr- 78 Zr, and 82 Zr- 82 Mo is conducted to predict the mirror symmetry violation in their rotational properties. The empirical P -factor, energy ratio , energies of the first excited state , and binding energies of these mirror partner nuclei are presented, together with the primary deformations and . Our calculations indicate the shape coexistence in the ground state of all these mirror partner nuclei. The moments of inertia of these mirror partner nuclei are not always the same in the yrast band. The rotational frequencies at which upbending occurs in 74 Kr and 74 Sr are nearly identical. However, in 78 Sr and 82 Zr, the upbending occurs earlier than in their mirror partners 78 Zr and 82 Mo. The upbending phenomenon in 74 Kr and 74 Sr is attributed to the simultaneous alignment of protons and neutrons. Taking the nuclei 78 Sr- 78 Zr as examples, we suggest that the first upbending is attributed to the alignment of protons and neutrons within the orbitals, as evidenced by the calculated single-particle energy levels. These specific band crossings are further elucidated through quasiparticle Routhian diagrams, which characterize the alignment of high- j , low-Ω pairs, and reveal the underlying microscopic mechanism. Our results show that 74 Kr and 74 Sr maintain strong mirror symmetry in their rotational behavior. 78 Sr and 82 Zr exhibit earlier upbending than their mirrors, indicating possible mirror symmetry breaking. This study may provide new insights for future research into the mirror symmetry violation in nuclear excited states.