  Q-balls are non-topological solitons that coherently rotate in field space.
We show that these coherent rotations can induce superradiance for scattering
waves, thanks to the fact that the scattering involves two coupled modes.
Despite the conservation of the particle number in the scattering, the mismatch
between the frequencies of the two modes allows for the enhancement of the
energy and angular momentum of incident waves. When the Q-ball spins in real
space, additional rotational superradiance is also possible, which can further
boost the enhancements. We identify the criteria for the energy and angular
momentum superradiance to occur. The Zel'dovich criterion for rotational
superradiance is violated in this system.

High Energy Physics - Theory;General Relativity and Quantum Cosmology;High Energy Physics - Phenomenology