Shape coexistence in 76Se within the neutron-proton interacting boson model

We have investigated the low-lying energy spectrum and electromagnetic transition strengths in even-even Se-76 using the proton-neutron interacting boson model (IBM-2). The theoretical calculation for the energy levels and E2 and M1 transition strengths is in good agreement with the experimental data. Specifically, the excitation energy and E2 transition of 0(2)(+) state, which is intimately associated with shape coexistence, can be accurately reproduced. The analysis on low-lying states and the key structure indicators R-1, R-2, (R)3 and R-4 and M1 transitions indicates that there is a coexistence between spherical shape and gamma-soft shape in Se-76.