Supersymmetric Q-balls: A Numerical Study

We study numerically a class of nontopological solitons, the Q-balls, arising in a supersymmetric extension of the standard model with low-energy, gauge-mediated symmetry breaking. Taking into account the exact form of the supersymmetric potential giving rise to Q-balls, we find that there is a lower limit on the value of the charge Q in order to make them classically stable: Q greater than or similar to 5x10(2)Q(cr), where Q(cr) is constant depending on the parameters defining the potential and can be in the range 1 less than or similar to Q(cr)less than or similar to 10(8/16). If Q is the baryon number, stability with respect to the decay into protons requires Q greater than or similar to 10(17)Q(cr), while if the gravitino mass is greater then m(3/2)greater than or similar to 61 MeV, no stable gauge-mediation supersymmetric Q-balls exist. Finally, we find that energy and radius of Q-balls can be parametrized as E similar to xi(E)Q(3/4) and R similar to xi(R)Q(1/4), where xi(E) and xi(R) are slowly varying functions of the charge.