Modeling uncertainties of ttW multilepton signatures

Modeling uncertainties of \(t\bar{t}W^\pm\) multilepton signatures

Authors: G. Bevilacqua, H.Y. Bi, F. Febres Cordero, H.B. Hartanto, M. Kraus, J. Nasufi, L. Reina, M. Worek

Abstract: In light of recent discrepancies between the modeling of \(t\bar{t} W^\pm\) signatures and measurements reported by the Large Hadron Collider (LHC) experimental collaborations, we investigate in detail theoretical uncertainties for multi-lepton signatures. We compare results from the state-of-the-art full off-shell calculation and its Narrow Width Approximation to results obtained from the on-shell \(t\bar{t} W^\pm\) calculation, with approximate spin-correlations in top-quark and \(W\) decays, matched to parton showers. In the former case double-, single-, and non-resonant contributions together with interference effects are taken into account, while the latter two cases are only based on the double resonant top-quark contributions. The comparison is performed for the LHC at \(\sqrt{s} = 13\) TeV for which we study separately the multi-lepton signatures as predicted from the dominant NLO contributions at the perturbative orders \(\mathcal{O}(\alpha_s^3\alpha^6)\) and \(\mathcal{O}(\alpha_s\alpha^8)\). Furthermore, we combine both contributions and propose a simple way to approximately incorporate the full off-shell effects in the NLO computation of on-shell \(pp\to t\bar{t} W^\pm\) matched to parton showers.

(Bevilacqua et al., 2022)