Mass-symmetry breaking in three-body ions

The ground-state energy of three-body ions (M+,M+,m-) evolves when the like-charge constituents are given different masses. The comparison of (m1+,m2+,m-) with the average of (m1+,m1+,m-) and (m2+,m2+,m-) reveals a competition between the symmetric term and the antisymmetric one. The former dominates in the Born-Oppenheimer regime such as the (p,t,e) case, while the latter wins for H--like systems with two negative light particles surrounding a heavy nucleus. A comparison is also made with the case of baryons in simple quark models with flavor independence