Finite-size effect on two-particle production

The formalism allowing one to account for the effect of a finite spacetime extent of a particle production region is given. Its applications to the lifetime measurement of hadronic atoms produced by a high-energy beam in a thin target, as well as to the femtoscopy techniques widely used to measure spacetime characteristics of the production processes, are discussed. The theoretical systematic errors due to the usual neglect of non-equal emission times in the pair center-of-mass system, the spacetime coherence and the residual charge are shown to be negligible.