Multifragmentation of finite many-body systems under long-range forces and an exactly solvable model of fragmentation with strict mass-conservation and quantum-symmetry

During the last 2 years multifragmentation of hot nuclei has become a well established phenomenon. Model calculations suggest that this is likely connected to the occurence of new, well defined, phase-transitions driven by the repulsive long-range Coulomb force. The origin of the transitions and the possible significance for other systems in physics is emphasised. In these transitions the critical fluctuations give further insight into the relevant physical mechanisms. For a detailed discussion of these fluctuation an exactly solvable model of fragmentation is presented. The effect of mass-conservation and quantum-symmetry can rigorously be considered. As a function of a tuning parameter self similar mass-distributions with realistic power-laws and/or fluctuations which show intermittency can be generated. Thus the relation of both critical phenomena can be studied analytically. It is found that they are unlinked. There are cases of the model where the mass distribution has a power-law with realistic exponents between τ=-2 and τ=-3 but no intermittency, or vice versa. (orig.)