You guessed in the wrong direction methinks.
"After they are produced axions rapidly decay into 2 electron pairs, an electron and a positron."
Seems like axions have enough mass to form the 2 particles and some energy is usually given off during decay. Unless the decomposition is endothermic but the decay apperars to go from high enery to lower energy particles. Thats why a super collider is needed to make them.