Abstract
Recently a slight tension between data and predictions has been reported in tbar{t}W production by both the CMS and ATLAS collaborations. We revisit the theoretical predictions for this process, focussing on the following two effects. We disentangle various effects that lead to asymmetries among the leptonic decay products of the (anti-)top quarks and W bosons, for which we find that the spin correlations in the top-quark pair are the dominant source. We also discuss the impact of the large, formally subleading, electroweak corrections to tbar{t}W production at the LHC. We find that this effect changes the tbar{t}W cross section significantly in the signature phase-space regions, and should therefore be included differentially in the theory to data comparisons.
Highlights
With the 13 TeV LHC run, both ATLAS and CMS collaborations have measured the ttV (V = Z, W ) cross sections
We focus on the jetmultiplicity cross sections, since that is shown by the ATLAS collaboration in Ref. [3]
Since the data has not been unfolded, we cannot directly compare to it. We can study this distribution at the theoretical level to see firstly whether and how it is shaped by the spin correlations and secondly if the EWsub effects considered in this work might have a significant influence on the ATLAS analysis
Summary
With the 13 TeV LHC run, both ATLAS and CMS collaborations have measured the ttV (V = Z , W ) cross sections These processes are studied either independently [1,2] or as irreducible backgrounds to ttH (multilepton) searches [3,4]. The largest tension for ttW is found when it enters as the main background in the ttH multi-lepton analyses It is reported in [3] that the normalisation factor for the ttW background in the two same sign lepton signature is 1.56+−00..3208 (at low jet multiplicity) and in the three lepton signature is 1.68+−00..3208, which indicate in both cases the lower theoretical ttW cross section in comparison with the data. C (2020) 80:803 we include the subleading EW corrections in a consistent matching to the parton shower The latter allows us to investigate the effects from these large corrections differentially in the fiducial region relevant to the ttH multi-lepton signatures.
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