Q-ball formation in the wake of Hubble-induced radiative corrections

We discuss some interesting aspects of Q-ball formation during the early oscillations of the flat directions. These oscillations are triggered by the running of a soft (mass)² stemming from the nonzero energy density of the Universe. However, this is quite different from standard Q-ball formation. The running in the presence of gauge and Yukawa couplings becomes strong if m1/2/m₀ is sufficiently large. Moreover, Q balls which are formed during the early oscillations constantly evolve, due to the redshift of the Hubble-induced soft mass, until the low-energy supersymmtery breaking becomes dominant. For smaller m1/2/m₀, Q balls are not formed during early oscillations because of the shrinking of the instability band due to the Hubble expansion. In this case, Q balls are formed only at the weak scale, but typically carry smaller charges, as a result of their amplitude redshift. Therefore, the Hubble-induced corrections to the flat directions give rise to a successful Q-ball cosmology.