Top-quark pair production in association with a W gauge boson in the POWHEG-BOX
Top-quark pair production in association with a \(W^\pm\) gauge boson in the POWHEG-BOX
Authors: F. Febres Cordero, M. Kraus, L. Reina
Abstract: We present a new Monte Carlo event generator for the production of a top-quark pair in association with a \(W^\pm\) boson at hadron colliders in the POWHEG-BOX framework. We consider the next-to-leading-order QCD corrections to the \(pp\to t\bar{t} W^\pm\) cross section, corresponding to the \(\mathcal{O}(\alpha_s^3\alpha)\) and \(\mathcal{O}(\alpha_s\alpha^3)\) terms in the perturbative expansion of the parton-level cross section, and model the decays of \(W\) and top quarks at leading order retaining spin correlations. The fixed-order QCD calculation is further interfaced with the Pythia8 parton-shower event generator via the POWHEG method as implemented in the POWHEG-BOX. The corresponding code is now part of the public repository of the POWHEG-BOX. We perform a comparison of different event generators for both the case of inclusive production and the case of the two same-sign leptons signature at the Large Hadron Collider operating at a center-of-mass energy of \(13\) TeV. We investigate theoretical uncertainties in the modelling of the fiducial volume stemming from missing higher-order corrections, the different parton shower matching schemes, and the modelling of decays. We find that the subleading contribution at \(\mathcal{O}(\alpha_s\alpha^3)\) is particularly sensitive to differences in the matching scheme and higher-order parton shower effects. We observe that in particular jet observables can differ quite visibly although these differences play only a subordinate role in the description of physical observables once all contributions are combined.
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