For the first time the next-to-leading-order electroweak corrections to the
full off-shell production of two top quarks that decay leptonically are
presented. This calculation includes all off-shell, non-resonant, and
interference effects for the 6-particle phase space. While the electroweak
corrections are below one per cent for the integrated cross section, they reach
up to 15% in the high-transverse-momentum region of distributions. To support
the results of the complete one-loop calculation, we have in addition evaluated
the electroweak corrections in two different pole approximations, one requiring
two on-shell top quarks and one featuring two on-shell W bosons. While the
former deviates by up to 10% from the full calculation for certain
distributions, the latter provides a very good description for most
observables. The increased centre-of-mass energy of the LHC makes the inclusion
of electroweak corrections extremely relevant as they are particularly large in
the Sudakov regime where new physics is expected to be probed.Comment: 33 pages,23 eps-figures. Matches the published version. Typo fixed in
equations (2.18) and (2.19
