2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/217813Kinematic fitting is a well-established tool to improve jet energy and invariant mass resolutions by fitting the measured values under constraints (e.g. energy conservation). However, in the presence of substantial ISR and Beamstrahlung, naive energy and (longitudinal) momentum constraints fail due to the a priori unknown amount of undetected momentum carried away by collinear photons. It is possible to take care of those two effects and thus obtain significantly higher mass resolutions.4 pages, 11 figures, conference proceeding of International Linear Collider Workshop 2008, ChicagoHigh Energy Physics - ExperimentData Analysis, Statistics and Probabilitytext