asymptotic states

Asymptotic states refer to the behavior of particles or systems observed at very large time intervals, either far in the future or past. In physics, especially quantum field theory, these states represent particles before they interact or after they have completed their interactions, effectively existing "at the edges" of the process. They help scientists analyze complex interactions by simplifying the initial and final situations, allowing for clearer understanding of how particles behave and transform during events such as collisions. Essentially, asymptotic states are the "start" and "end" snapshots used to study dynamic processes in a structured way.