  In Affleck-Dine baryogenesis, the observed baryon asymmetry of the Universe
is generated through the evolution of the vacuum expectation value (VEV) of a
scalar condensate. This scalar condensate generically fragments into
non-topological solitons (Q-balls). If they are sufficiently long-lived, they
lead to an early matter domination epoch, which enhances the primordial
gravitational wave signal for modes that enter the horizon during this epoch.
The sudden decay of the Q-balls into fermions results in a rapid transition
from matter to radiation domination, producing a sharp peak in the
gravitational wave power spectrum. Avoiding the problem of gravitino
over-abundance favours scenarios where the peak frequency of the resonance is
within the range of the Einstein Telescope and/or Decigo. Therefore, we show
this scenario provides an observable signal, providing a mechanism to test
Affleck-Dine baryogenesis.
