  Q-balls are non-topological solitonic solutions to a wide class of field
theories that possess global symmetries. Here we show that in these same
theories there also exists a tower of novel composite Q-ball solutions where,
within one composite Q-ball, positive and negative charges co-exist and swap at
a frequency lower than the natural frequency of an individual Q-ball. These
charge-swapping Q-balls are constructed by assembling Q-balls and anti-Q-balls
tightly such that their nonlinear cores overlap. We explain why charge-swapping
Q-balls can form and why they swap charges.
