Associated production of a top quark pair with a heavy electroweak gauge boson at NLO+NNLL accuracy Anna Kulesza, Leszek Motyka, Daniel Schwartländer, Tomasz Stebel and Vincent Theeuwes Eur. Phys. J. C, 79 3 (2019) 249 Published online: 20 March 2019 DOI: 10.1140/epjc/s10052-019-6746-z