Q-ball formation in the gravity-mediated SUSY breaking scenario - art. no.023512

We study the formation of Q balls which are made of flat directions that ap pear in the supersymmetric extension of the standard model in the contest o f gravity-mediated supersymmetry breaking. The full nonlinear calculations for the dynamics of the complex scalar field are made. Since the scaler pot ential in this model is flatter than phi(2), we have found that fluctuation s develop and go nonlinear to form nontopological solitons, Q balls. The si ze of a Q ball is determined by the most amplified mode, which is completel y determined by the model parameters. On the other hand, the charge of a ba lls depends linearly on the initial charge density of the Affleck-Dine (AD) held. Almost all the charges are absorbed into Q balls, and only a tiny fr action of the charges is carried by a relic XD field. It may lead to some c onstraints on the baryogenesis and/or parameters in the particle theory. Th e peculiarity of gravity mediation is the moving Q balls. This results in c ollisions between Q balls. It may increase the charge of the Q balls, and c hange its fate.