Analytical and numerical properties of Q-balls

Stable non-topological solitons, Q-balls, are studied using analytical and numerical methods. Three different physically interesting potentials that s upport Q-ball solutions are considered: two typical polynomial potentials a nd a logarithmic potential inspired by supersymmetry. It is shown that Q-ba lls in these potentials exhibit different properties in the thick-wall limi t where the charge of a Q-ball is typically considerably smaller than in th e thin-wall limit. Analytical criteria are derived to check whether stable Q-balls exist in the thick-wall limit for typical potentials. Q-ball charge , energy and profiles are presented for each potential studied. Evaporation rates are calculated in the perfect thin-wall limit and for realistic Q-ba ll profiles. It is shown that in each case the evaporation rate increases w ith decreasing charge. (C) 2000 Elsevier Science B.V. All rights reserved.