2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/177479A cut on the maximum lifetime in a lifetime fit not only reduces the number of events, but also, in some circumstances dramatically, decreases the statistical significance of each event. The upper impact parameter cut in the hadronic B trigger at CDF, which is due to technical limitations, has the same effect. In this note we describe and quantify the consequences of such a cut on lifetime measurements. We find that even moderate upper lifetime cuts, leaving event numbers nearly unchanged, can dramatically increase the statistical uncertainty of the fit result.Changes to latest revision: added DOI link, took the opportunity to correct some minor typos added one small clarificationHigh Energy Physics - Experimenttext