The influence of Coulomb on the liquid-gas phase transition and nuclear multifragmentation

The liquid-gas phase transition is analyzed from the topologic properties of the event distribution in the obervables space. A multi-canonical formalism allows to directly relate the standard phase transition with neutral particles to the case where the non saturating Coulomb interaction is present, and to interpret the effect of Coulomb as a deformation of the probability distributions and a rotation of the order parameter. This formalism is applied to a statistical multifragmentation model and consequences for the nuclear multifragmentation phase transitions are drawn.