  We study the $2e^-2e^+$ equal-mass charge-neutral four-body system in the
adiabatic hyperspherical framework. The lowest few adiabatic potentials are
calculated for zero orbital angular momentum, positive parity, and charge
conjugation symmetries. Propagating the R-matrix, the low-energy $s$-wave
scattering lengths of the singlet-singlet and triplet-triplet spin
configurations are calculated. Lastly, we calculate the S-matrix for energies
above the ionic threshold to estimate the transition rates between the single
ionic fragmentation channel and the lowest few dimer-dimer fragmentation
channels.
