The generation of single top production in the Wt channel at NLO gives rise
to doubly-resonant diagrams that overlap with ttˉ, and similarly for
associated production with a Z or Higgs boson. Several methods exist to
remove this overlap, thus avoiding double counting and separating the two
processes. In Diagram Removal 1, the amplitudes of doubly-resonant diagrams are
set to zero, which also removes the interference of Wt with ttˉ. If a
measurement is performed in a region where this interference is not negligible,
it would be of interest to take it into account. Another method, Diagram
Subtraction, preserves the interference. However, it relies upon momentum
reshuffling, which introduces uncertainties to the prediction. An alternative
method, Diagram Removal 2, does not involve reshuffling and preserves the
interference by subtracting the amplitude squared of the doubly-resonant
diagrams from the total. The predictions of Diagram Removal 2 from MG5_aMC@NLO
are compared with other predictions for Wt and tWZ production in the
context of analyses at the ATLAS experiment. Implications of using Diagram
Removal 2 are discussed, both for measurements of single top processes and when
Wt or tWZ are treated as a background. Differential distributions are
shown, investigating in what regions the predictions differ the most.Comment: Conference: The 9th International Workshop of Top Quark Physics 2016
5 pages including title page, 7 figure