Anatomy of inclusive $t\overline{t}W$ production at hadron colliders

Abstract

In LHC searches for new and rare phenomena the top-associated channel $pp\to t\overline{t}{W}^{\pm }+X$ is a challenging background that multilepton analyses must overcome. Motivated by sustained measurements of enhanced rates of same-sign and multi-lepton final states, we reexamine the importance of higher jet multiplicities in $pp\to t\overline{t}{W}^{\pm }+X$ that enter at $\mathcal{O}({\alpha }_s^3\alpha )$ and $\mathcal{O}({\alpha }_s^4\alpha )$, i.e., that contribute at NLO and NNLO in QCD in inclusive $t\overline{t}{W}^{\pm }$ production. Using fixed-order computations, we estimate that a mixture of real and virtual corrections at $\mathcal{O}({\alpha }_s^4\alpha )$ in well-defined regions of phase space can arguably increase the total $t\overline{t}{W}^{\pm }$ rate at NLO by at least $10\%-14\%$. However, by using non-unitary NLO multi-jet matching, we estimate that these same corrections are at most $10\%-12\%$, and at the same time exhibit the enhanced jet multiplicities that are slightly favored by data. This seeming incongruity suggests a need for the full NNLO result. We comment on implications for the $t\overline{t}Z$ process.

Comments: 11 pages, 4 figures (7 files), 3 tables, journal version (results unchanged)