2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/203199In this paper we describe a new model of multiple partonic interactions that has been implemented in Herwig++. Tuning its two free parameters we find a good description of CDF underlying event data. We show extrapolations to the LHC.25 pages, 16 figures, plots and tune updated for Herwig++ 2.2.1, additional paragraph on the LHC extrapolationHigh Energy Physics - Phenomenologytext