Associated production of charged Higgs bosons and top quarks with POWHEG Michael Klasen, Karol Kovařík, Paolo Nason and Carole Weydert Eur. Phys. J. C, 72 9 (2012) 2088 Published online: 07 September 2012 DOI: 10.1140/epjc/s10052-012-2088-9