Particle creation from Q-balls

Non-topological solitons, Q-balls can arise in many particle theories with U(1) global symmetries. As was shown by Cohen et al. [A.G. Cohen, S.R. Coleman, H. Georgi, A. Manohar, The evaporation of Q-balls, Nucl. Phys. B 272 (1986) 301], if the corresponding scalar field couples to massless fermions, large Q-balls are unstable and evaporate, producing a fermion flux proportional to the Q-ball's surface. In this paper we analyse Q-ball instabilities as a function of Q-ball size ans fermion mass. In particular, we construct an exact quantum-mechanical description of the evaporating Q-ball. This new construction provides an alternative method to compute Q-ball's evaporation rates. We shall also find the new expression for the upper bound on evaporation as a function of the produced fermion mass and study the effects of Q ball's size on particle production.