SURVIVAL PROBABILITY AND FIELD-THEORY IN SYSTEMS WITH ABSORBING STATES

An important quantity in the analysis of systems with absorbing states is the survival probability P-s(t), the probability that an initial l ocalized seed of particles has not completely disappeared after time t . At the transition into the absorbing phase, this probability scales for large t like t(-delta). It is not at all obvious how to compute de lta in continuous field theories, where P-s(t) is strictly unity for a ll finite t. We propose here an interpretation for delta in field theo ry and devise a practical method to determine it analytically. The met hod is applied to field theories representing absorbing-state systems in several distinct universality classes. Scaling relations are system atically derived and the known exact delta value is obtained for the v oter model universality class.